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Sample records for ferrite-martensite steel surface

  1. Tritium retention in reduced-activation ferritic/martensitic steels

    SciTech Connect

    Hatano, Y.; Abe, S.; Matsuyama, M.; Alimov, V.K.; Spitsyn, A.V.; Bobyr, N.P.; Cherkez, D.I.; Khripunov, B.I.; Golubeva, A.V.; Ogorodnikova, O.V.; Klimov, N.S.; Chernov, V.M.; Oyaidzu, M.; Yamanishi, T.

    2015-03-15

    Reduced-activation ferritic/martensitic (RAFM) steels are structural material candidates for breeding blankets of future fusion reactors. Therefore, tritium (T) retention in RAFM steels is an important problem in assessing the T inventory of blankets. In this study, specimens of RAFM steels were subjected to irradiation of 20 MeV W ions to 0.54 displacements per atom (dpa), exposure to high flux D plasmas at 400 and 600 K and that to pulsed heat loads. The specimens thus prepared were exposed to DT gas at 473 K. Despite severe modification in the surface morphology, heat loads had negligible effects on T retention. Significant increase in T retention at the surface and/or subsurface was observed after D plasma exposure. However, T trapped at the surface/subsurface layer was easily removed by maintaining the specimens in the air at about 300 K. Displacement damage led to increase in T retention in the bulk due to the trapping effects of defects, and T trapped was stable at 300 K. It was therefore concluded that displacement damages had the largest influence on T retention under the present conditions.

  2. Irradiation-induced grain growth in nanocrystalline reduced activation ferrite/martensite steel

    SciTech Connect

    Liu, W. B.; Chen, L. Q.; Zhang, C. Yang, Z. G.; Ji, Y. Z.; Zang, H.; Shen, T. L.

    2014-09-22

    In this work, we investigate the microstructure evolution of surface-nanocrystallized reduced activation ferrite/martensite steels upon high-dose helium ion irradiation (24.3 dpa). We report a significant irradiation-induced grain growth in the irradiated buried layer at a depth of 300–500 nm, rather than at the peak damage region (at a depth of ∼840 nm). This phenomenon can be explained by the thermal spike model: minimization of the grain boundary (GB) curvature resulting from atomic diffusion in the cascade center near GBs.

  3. Mechanical properties and microstructure of advanced ferritic-martensitic steels used under high dose neutron irradiation

    NASA Astrophysics Data System (ADS)

    Shamardin, V. K.; Golovanov, V. N.; Bulanova, T. M.; Povstianko, A. V.; Fedoseev, A. E.; Goncharenko, Yu. D.; Ostrovsky, Z. E.

    Some results of the study of mechanical properties and structure of ferritic-martensitic chromium steels with 13% and 9% chromium, irradiated in the BOR-60 reactor up to different damage doses are presented in this report. Results concerning the behaviour of commercial steels, containing to molybdenum, vanadium and niobium, and developed for the use in fusion reactors, are compared to low-activation steels in which W and Ta replaced Mo and Nb. It is shown that after irradiation to the dose of ˜10 dpa at 400°C 0.1C-9Cr-1W, V, Ta steels are prone to lower embrittlement as deduced from fracture surface observations of tensile specimens. Peculiarities of fine structure and fracture mode, composition and precipitation reactions in steels during irradiation are discussed.

  4. Proceedings of the IEA Working Group meeting on ferritic/martensitic steels

    SciTech Connect

    Klueh, R.L.

    1996-12-31

    An IEA working group on ferritic/martensitic steels for fusion applications, consisting of researchers from Japan, European Union, USA, and Switzerland, met at the headquarters of the Joint European Torus, Culham, UK. At the meeting, preliminary data generated on the large heats of steels purchased for the IEA program and on other heats of steels were presented and discussed. Second purpose of the meeting was to continue planning and coordinating the collaborative test program in progress on reduced-activation ferritic/martensitic steels. The majority of this report consists of viewographs for the presentations.

  5. Liquid metal embrittlement susceptibility of ferritic martensitic steel in liquid lead alloys

    NASA Astrophysics Data System (ADS)

    Van den Bosch, J.; Bosch, R. W.; Sapundjiev, D.; Almazouzi, A.

    2008-06-01

    The susceptibility of the ferritic-martensitic steels T91 and EUROFER97 to liquid metal embrittlement (LME) in lead alloys has been examined under various conditions. T91, which is currently the most promising candidate material for the high temperature components of the future accelerator driven system (ADS) was tested in liquid lead bismuth eutectic (LBE), whereas the reduced activation steel, EUROFER97 which is under consideration to be the structural steel for fusion reactors was tested in liquid lead lithium eutectic. These steels, similar in microstructure and mechanical properties in the unirradiated condition were tested for their susceptibility to LME as function of temperature (150-450 °C) and strain rate (1 × 10 -3-1 × 10 -6 s -1). Also, the influence of pre-exposure and surface stress concentrators was evaluated for both steels in, respectively, liquid PbBi and PbLi environment. To assess the LME effect, results of the tests in liquid metal environment are compared with tests in air or inert gas environment. Although both unirradiated and irradiated smooth ferritic-martensitic steels do not show any or little deterioration of mechanical properties in liquid lead alloy environment compared to their mechanical properties in gas as function of temperature and strain rate, pre-exposure or the presence of surface stress concentrators does lead to a significant decrease in total elongation for certain test conditions depending on the type of liquid metal environment. The results are discussed in terms of wetting enhanced by liquid metal corrosion or crack initiation processes.

  6. Friction Stir Welding of HT9 Ferritic-Martensitic Steel: An Assessment of Microstructure and Properties

    DTIC Science & Technology

    2013-06-01

    development. While high speed steel or WC-Co tools can be used for aluminum and copper alloys, FSW of steel generally requires even more refractory... steel and the microstructure produced by FSW is much more critical than in aluminum alloys. The αγδ phase transformations can cause complex, multi...thesis explores the processing-microstructure-property relationships in friction stir welded ( FSW ) HT9A ferritic-martensitic steel . HT9 has previously

  7. Summary of the IEA workshop/working group meeting on ferritic/martensitic steels for fusion

    SciTech Connect

    Klueh, R.L.

    1997-04-01

    An International Energy Agency (IEA) Working Group on Ferritic/Martensitic Steels for Fusion Applications, consisting of researchers from Japan, the European Union, the United States, and Switzerland, met at the headquarters of the Joint European Torus (JET), Culham, United Kingdom, 24-25 October 1996. At the meeting preliminary data generated on the large heats of steel purchased for the IEA program and on other heats of steels were presented and discussed. The second purpose of the meeting was to continue planning and coordinating the collaborative test program in progress on reduced-activation ferritic/martensitic steels. The next meeting will be held in conjunction with the International Conference on Fusion Reactor Materials (ICFRM-8) in Sendai, Japan, 23-31 October 1997.

  8. Fatigue strength of low-activation ferritic-martensitic high-chromium EK-181 steel

    NASA Astrophysics Data System (ADS)

    Kolmakov, A. G.; Terent'ev, V. F.; Prosvirnin, D. V.; Chernov, V. M.; Leont'eva-Smirnova, M. V.

    2016-04-01

    The static and cyclic mechanical properties of low-activation ferritic-martensitic EK-181 (Fe‒12Cr-2W-V-Ta-B-C) steel are studied in the temperature range 20-920°C (static tests) and at 20°C (cyclic tests). The fracture mechanisms of the steel under static tension and fatigue fracture conditions are analyzed by scanning electron microscopy.

  9. Effect of ultrasonic impact peening on the corrosion of ferritic-martensitic steels in supercritical water

    NASA Astrophysics Data System (ADS)

    Dong, Ziqiang; Liu, Zhe; Li, Ming; Luo, Jing-Li; Chen, Weixing; Zheng, Wenyue; Guzonas, Dave

    2015-02-01

    Ferritic-Martensitic (F/M) steels are important candidate alloys to be used in the next generation (Generation-IV) SCWRs. In this work, two F/M steels with the same Cr content of around 12 wt.% and varied Si content from 0.6 wt.% to 2.2 wt.% were evaluated in supercritical water (SCW) at 500 °C and 25 MPa for up to 1000 h. The effect of ultrasonic shot peening on the oxidation behavior of these F/M steels have been investigated. The results showed that the oxidation was affected by the Si content as well as the surface modification. The F/M steel with low Si concentration exhibited higher corrosion resistance than that of the alloy with high Si content. Shot peening, which could modify the microstructure at the surface, showed significantly beneficial effect to improving the oxidation resistance. A thin, uniform oxide layer formed on the peened sample could be attributed to the enhanced diffusion of Cr induced by the surface modification.

  10. Corrosion of ferritic-martensitic steels and nickel-based alloys in supercritical water

    NASA Astrophysics Data System (ADS)

    Ren, Xiaowei

    The corrosion behavior of ferritic/martensitic (F/M) steels and Ni-based alloys in supercritical water (SCW) has been studied due to their potential applications in future nuclear reactor systems, fossil fuel power plants and waste treatment processes. 9˜12% chromium ferritic/martensitic steels exhibit good radiation resistance and stress corrosion cracking resistance. Ni-based alloys with an austenitic face-centered cubic (FCC) structure are designed to retain good mechanical strength and corrosion/oxidation resistance at elevated temperatures. Corrosion tests were carried out at three temperatures, 360°C, 500°C and 600°C, with two dissolved oxygen contents, 25 ppb and 2 ppm for up to 3000 hours. Alloys modified by grain refinement and reactive element addition were also investigated to determine their ability to improve the corrosion resistance in SCW. A duplex oxide structure was observed in the F/M steels after exposure to 25 ppb oxygen SCW, including an outer oxide layer with columnar magnetite grains and an inner oxide layer constituted of a mixture of spinel and ferrite phases in an equiaxed grain structure. An additional outermost hematite layer formed in the SCW-exposed samples when the oxygen content was increased to 2 ppm. Weight gain in the F/M steels increased with exposure temperatures and times, and followed parabolic growth kinetics in most of the samples. In Ni-based alloys after exposure to SCW, general corrosion and pitting corrosion were observed, and intergranular corrosion was found when exposed at 600°C due to formation of a local healing layer. The general oxide structure on the Ni-based alloys was characterized as NiO/Spinel/(CrxFe 1-x)2O3/(Fe,Ni). No change in oxidation mechanism was observed in crossing the critical point despite the large change in water properties. Corrosion resistance of the F/M steels was significantly improved by plasma-based yttrium surface treatment because of restrained outward diffusion of iron by the

  11. Microstructure property analysis of HFIR-irradiated reduced-activation ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Tanigawa, H.; Hashimoto, N.; Sakasegawa, H.; Klueh, R. L.; Sokolov, M. A.; Shiba, K.; Jitsukawa, S.; Kohyama, A.

    2004-08-01

    The effects of irradiation on the Charpy impact properties of reduced-activation ferritic/martensitic steels were investigated on a microstructural basis. It was previously reported that the ductile-brittle transition temperature (DBTT) of F82H-IEA and its heat treatment variant increased by about 130 K after irradiation at 573 K up to 5 dpa. Moreover, the shifts in ORNL9Cr-2WVTa and JLF-1 steels were much smaller, and the differences could not be interpreted as an effect of irradiation hardening. The precipitation behavior of the irradiated steels was examined by weight analysis and X-ray diffraction analysis on extraction residues, and SEM/EDS analysis was performed on extraction replica samples and fracture surfaces. These analyses suggested that the difference in the extent of DBTT shift could be explained by (1) smaller irradiation hardening at low test temperatures caused by irradiation-induced lath structure recovery (in JLF-1), and (2) the fracture stress increase caused by the irradiation-induced over-solution of Ta (in ORNL9Cr-2WVTa).

  12. Using nonlinear ultrasound measurements to track thermal aging in modified 9%Cr ferritic martensitic steel

    NASA Astrophysics Data System (ADS)

    Marino, Daniel; Kim, Jin-Yeon; Jacobs, Laurence J.; Ruiz, Alberto; Joo, Young-Sang

    2015-03-01

    This study investigates early thermal aging in 9%Cr ferritic martensitic (FM) steel, which is caused by the formation of second phases during high temperature exposure. This study employs a recently developed nonlinear ultrasonic technique to explore the sensitivity of the nonlinearity parameter. Experimental results show that the nonlinearity parameter is sensitive to certain changes in material's properties such as thermal embrittlement and hardness changes; therefore, it can be used as an indicator of the thermal damage. The specimens investigated are heat treated for different holding times ranging from 200h to 3000h at 650°C. Nonlinear ultrasonic experiments are conducted for each specimen using a wedge transducer to generate and an air-coupled transducer to detect Raleigh surface waves. The amplitudes of the first and second order harmonics are measured at different propagation distances and these amplitudes are used to obtain the relative nonlinearity parameter for each specimen with a different holding time. The nonlinear ultrasonic results are compared with independent mechanical measurements and metallographic images. This research proposes the nonlinear ultrasonic technique as a nondestructive evaluation tool not only to detect thermal damage in early stages, and also to qualitatively assess the stage of thermal damage.

  13. Report on thermal aging effects on tensile properties of ferritic-martensitic steels.

    SciTech Connect

    Li, M.; Soppet, W.K.; Rink, D.L.; Listwan, J.T.; Natesan, K.

    2012-05-10

    This report provides an update on the evaluation of thermal-aging induced degradation of tensile properties of advanced ferritic-martensitic steels. The report is the first deliverable (level 3) in FY11 (M3A11AN04030103), under the Work Package A-11AN040301, 'Advanced Alloy Testing' performed by Argonne National Laboratory, as part of Advanced Structural Materials Program for the Advanced Reactor Concepts. This work package supports the advanced structural materials development by providing tensile data on aged alloys and a mechanistic model, validated by experiments, with a predictive capability on long-term performance. The scope of work is to evaluate the effect of thermal aging on the tensile properties of advanced alloys such as ferritic-martensitic steels, mod.9Cr-1Mo, NF616, and advanced austenitic stainless steel, HT-UPS. The aging experiments have been conducted over a temperature of 550-750 C for various time periods to simulate the microstructural changes in the alloys as a function of time at temperature. In addition, a mechanistic model based on thermodynamics and kinetics has been used to address the changes in microstructure of the alloys as a function of time and temperature, which is developed in the companion work package at ANL. The focus of this project is advanced alloy testing and understanding the effects of long-term thermal aging on the tensile properties. Advanced materials examined in this project include ferritic-martensitic steels mod.9Cr-1Mo and NF616, and austenitic steel, HT-UPS. The report summarizes the tensile testing results of thermally-aged mod.9Cr-1Mo, NF616 H1 and NF616 H2 ferritic-martensitic steels. NF616 H1 and NF616 H2 experienced different thermal-mechanical treatments before thermal aging experiments. NF616 H1 was normalized and tempered, and NF616 H2 was normalized and tempered and cold-rolled. By examining these two heats, we evaluated the effects of thermal-mechanical treatments on material microstructures and

  14. Radiation hardening and deformation behavior of irradiated ferritic-martensitic steels

    SciTech Connect

    Robertson, J.P.; Klueh, R.L.; Rowcliffe, A.F.; Shiba, K.

    1998-03-01

    Tensile data from several 8--12% Cr alloys irradiated in the High Flux Isotope Reactor (HFIR) to doses up to 34 dpa at temperatures ranging from 90 to 600 C are discussed in this paper. One of the critical questions surrounding the use of ferritic-martensitic steels in a fusion environment concerns the loss of uniform elongation after irradiation at low temperatures. Irradiation and testing at temperatures below 200--300 C results in uniform elongations less than 1% and stress-strain curves in which plastic instability immediately follows yielding, implying dislocation channeling and flow localization. Reductions in area and total elongations, however, remain high.

  15. Development and characterization of advanced 9Cr ferritic/martensitic steels for fission and fusion reactors

    NASA Astrophysics Data System (ADS)

    Saroja, S.; Dasgupta, A.; Divakar, R.; Raju, S.; Mohandas, E.; Vijayalakshmi, M.; Bhanu Sankara Rao, K.; Raj, Baldev

    2011-02-01

    This paper presents the results on the physical metallurgy studies in 9Cr Oxide Dispersion Strengthened (ODS) and Reduced Activation Ferritic/Martensitic (RAFM) steels. Yttria strengthened ODS alloy was synthesized through several stages, like mechanical milling of alloy powders and yttria, canning and consolidation by hot extrusion. During characterization of the ODS alloy, it was observed that yttria particles possessed an affinity for Ti, a small amount of which was also helpful in refining the dispersoid particles containing mixed Y and Ti oxides. The particle size and their distribution in the ferrite matrix, were studied using Analytical and High Resolution Electron Microscopy at various stages. The results showed a distribution of Y 2O 3 particles predominantly in the size range of 5-20 nm. A Reduced Activation Ferritic/Martensitic steel has also been developed with the replacement of Mo and Nb by W and Ta with strict control on the tramp and trace elements (Mo, Nb, B, Cu, Ni, Al, Co, Ti). The transformation temperatures ( Ac1, Ac3 and Ms) for this steel have been determined and the transformation behavior of the high temperature austenite phase has been studied. The complete phase domain diagram has been generated which is required for optimization of the processing and fabrication schedules for the steel.

  16. Microstructure and Mechanical Properties of a Nitride-Strengthened Reduced Activation Ferritic/Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Zhou, Qiangguo; Zhang, Wenfeng; Yan, Wei; Wang, Wei; Sha, Wei; Shan, Yiyin; Yang, Ke

    2012-12-01

    Nitride-strengthened reduced activation ferritic/martensitic (RAFM) steels are developed taking advantage of the high thermal stability of nitrides. In the current study, the microstructure and mechanical properties of a nitride-strengthened RAFM steel with improved composition were investigated. Fully martensitic microstructure with fine nitrides dispersion was achieved in the steel. In all, 1.4 pct Mn is sufficient to suppress delta ferrite and assure the steel of the full martensitic microstructure. Compared to Eurofer97, the steel showed similar strength at room temperature but higher strength at 873 K (600 °C). The steel exhibited very high impact toughness and a low ductile-to-brittle transition temperature (DBTT) of 243 K (-30 °C), which could be further reduced by purification.

  17. Reduction method of DBTT shift due to irradiation for reduced-activation ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Wakai, E.; Okubo, N.; Ando, M.; Yamamoto, T.; Takada, F.

    2010-03-01

    The method for reducing irradiation-induced DBTT shift of reduced-activation ferritic/martensitic steels was examined. F82H-LN (low nitrogen, 20 ppm), F82H+60 ppm 11B+200 ppmN and F82H+60 ppm 10B+200 ppmN steels tempered at 780 °C for 0.5 h were irradiated at 250 °C to 2 dpa, and the results for Charpy impact tests were analyzed. The upper shelf energy of F82H+ 11B+N steel was hardly changed by the irradiation, and DBTT shift was very small. From our research, DBTT shift due to irradiation can be reduced by the control of tempered conditions before irradiation, and it is found to be furthermore reduced by impurity doping with 60 ppm 11B and 200 ppmN to F82H steel.

  18. Mechanical property changes of low activation ferritic/martensitic steels after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Kohno, Y.; Kohyama, A.; Hirose, T.; Hamilton, M. L.; Narui, M.

    Mechanical property changes of Fe- XCr-2W-0.2V,Ta ( X: 2.25-12) low activation ferritic/martensitic steels including Japanese Low Activation Ferritic/martensitic (JLF) steels and F82H after neutron irradiation were investigated with emphasis on Charpy impact property, tensile property and irradiation creep properties. Dose dependence of ductile-to-brittle transition temperature (DBTT) in JLF-1 (9Cr steel) irradiated at 646-700 K increased with irradiation up to 20 dpa and then decreased with further irradiation showing highest DBTT of 260 K at 20 dpa. F82H showed similar dose dependence in DBTT to JLF-1 with higher transition temperature than that of JLF-1 at the same displacement damage. Yield strength in JLF steels and F82H showed similar dose dependence to that of DBTT. Yield strength increased with irradiation up to 15-20 dpa and then decreased to saturate above about 40 dpa. Irradiation hardening in 7-9%Cr steels (JLF-1, JLF-3, F82H) were observed to be smaller than those in steels with 2.25%Cr (JLF-4) or 12%Cr (JLF-5). Dependences of creep strain on applied hoop stress and neutron fluence were measured to be 1.5 and 1, respectively. Temperature dependence of creep coefficient showed a maximum at about 700 K which was caused by irradiation induced void formation or irradiation enhanced creep deformation. Creep coefficient of F82H was larger than those of JLF steels above 750 K. This was considered to be caused by the differences in N and Ta concentration between F82H and JLF steels.

  19. Load partitioning between ferrite/martensite and dispersed nanoparticles of a 9Cr ferritic/martensitic (F/M) ODS steel at high temperatures

    SciTech Connect

    Zhang, Guangming; Mo, Kun; Miao, Yinbin; Liu, Xiang; Almer, Jonathan; Zhou, Zhangjian; Stubbins, James F.

    2015-06-18

    In this study, a high-energy synchrotron radiation X-ray technique was used to investigate the tensile deformation processes of a 9Cr-ODS ferritic/martensitic (F/M) steel at different temperatures. Two minor phases within the 9Cr-ODS F/M steel matrix were identified as Y2Ti2O7 and TiN by the high-energy X-ray diffraction, and confirmed by the analysis using energy dispersive X-ray spectroscopy (EDS) of scanning transmission electron microscope (STEM). The lattice strains of the matrix and particles were measured through the entire tensile deformation process. During the tensile tests, the lattice strains of the ferrite/martensite and the particles (TiN and Y2Ti2O7) showed a strong temperature dependence, decreasing with increasing temperature. Analysis of the internal stress at three temperatures showed that the load partitioning between the ferrite/martensite and the particles (TiN and Y2Ti2O7) was initiated during sample yielding and reached to a peak during sample necking. At three studied temperatures, the internal stress of minor phases (Y2Ti2O7 and TiN) was about 2 times that of F/M matrix at yielding position, while the internal stress of Y2Ti2O7 and TiN reached about 4.5-6 times and 3-3.5 times that of the F/M matrix at necking position, respectively. It indicates that the strengthening of the matrix is due to minor phases (Y2Ti2O7 and TiN), especially Y2Ti2O7 particles. Although the internal stresses of all phases decreased with increasing temperature from RT to 600 degrees C, the ratio of internal stresses of each phase at necking position stayed in a stable range (internal stresses of Y2Ti2O7 and TiN were about 4.5-6 times and 3-3.5 times of that of F/M matrix, respectively). The difference between internal stress of the F/M matrix and the applied stress at 600 degrees C is slightly lower than those at RI and 300 degrees C, indicating that the nanoparticles still have good strengthening effect at 600 degrees C. (C) 2015 Elsevier B.V. All rights reserved.

  20. Neutron irradiation effects on the ductile-brittle transition of ferritic/martensitic steels

    SciTech Connect

    Klueh, R.L.; Alexander, D.J.

    1997-08-01

    Ferritic/martensitic steels such as the conventional 9Cr-1MoVNb (Fe-9Cr-1Mo-0.25V-0.06Nb-0.1C) and 12Cr-1MoVW (Fe-12Cr-1Mo-0.25V-0.5W-0.5Ni-0.2C) steels have been considered potential structural materials for future fusion power plants. The major obstacle to their use is embrittlement caused by neutron irradiation. Observations on this irradiation embrittlement is reviewed. Below 425-450{degrees}C, neutron irradiation hardens the steels. Hardening reduces ductility, but the major effect is an increase in the ductile-brittle transition temperature (DBTT) and a decrease in the upper-shelf energy, as measured by a Charpy impact test. After irradiation, DBTT values can increase to well above room temperature, thus increasing the chances of brittle rather than ductile fracture.

  1. Mechanical Performance of Ferritic Martensitic Steels for High Dose Applications in Advanced Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Anderoglu, Osman; Byun, Thak Sang; Toloczko, Mychailo; Maloy, Stuart A.

    2013-01-01

    Ferritic/martensitic (F/M) steels are considered for core applications and pressure vessels in Generation IV reactors as well as first walls and blankets for fusion reactors. There are significant scientific data on testing and industrial experience in making this class of alloys worldwide. This experience makes F/M steels an attractive candidate. In this article, tensile behavior, fracture toughness and impact property, and creep behavior of the F/M steels under neutron irradiations to high doses with a focus on high Cr content (8 to 12) are reviewed. Tensile properties are very sensitive to irradiation temperature. Increase in yield and tensile strength (hardening) is accompanied with a loss of ductility and starts at very low doses under irradiation. The degradation of mechanical properties is most pronounced at <0.3 T M ( T M is melting temperature) and up to 10 dpa (displacement per atom). Ferritic/martensitic steels exhibit a high fracture toughness after irradiation at all temperatures even below 673 K (400 °C), except when tested at room temperature after irradiations below 673 K (400 °C), which shows a significant reduction in fracture toughness. Creep studies showed that for the range of expected stresses in a reactor environment, the stress exponent is expected to be approximately one and the steady state creep rate in the absence of swelling is usually better than austenitic stainless steels both in terms of the creep rate and the temperature sensitivity of creep. In short, F/M steels show excellent promise for high dose applications in nuclear reactors.

  2. Improvement of High Temperature Mechanical Property by Precipitation Hardening of Reduced Activation Ferritic/Martensitic Steels

    SciTech Connect

    Sakasegawa, H.; Kohyama, A.; Katoh, Y.; Tamura, M.; Khono, Y.; Kimura, A.

    2003-07-15

    Reduced Activation Ferritic/Martensitic steels (RAFs) are leading candidates for blanket and first wall structures of the D-T fusion reactors. Recently, in order to achieve better efficiency of energy conversion by using RAFs in advanced blanket systems, improvement of high temperature mechanical property of RAFs is desired. In this work, experimental alloys, FETA-series (Fe-Ta-C or N) steels, were prepared to observe precipitation hardening mechanism by MX-type particles at elevated temperatures in detail. According to the results, innovative improvement of creep property can be achieved by applying of precipitation hardening by very fine TaX (X=C, N) particles. With increasing tantalum content, finer dispersion of MX-type particles, dislocation structures and sub-grain structures were observed by TEM (Transmission Electron Microscopy). These fine structures contributed to the improvement of creep property.

  3. Oxidation behavior of ferritic-martensitic and ODS steels in supercritical water

    NASA Astrophysics Data System (ADS)

    Bischoff, Jeremy

    water corroded much faster than those in steam (1.5 to 2 times faster). Additionally, during these corrosion tests a marker experiment was performed with the deposition of micrometric palladium markers on the surface of some samples prior to oxidation. The markers were found at the outer-inner layer interface, consistent with a corrosion mechanism of outward migration of iron to form the outer layer and inward migration of oxygen to form the inner layer. The discrepancy between the SCW and steam environments suggests that the outward migration of iron may be the rate-limiting step. A detailed study of the oxide advancement was performed using the TEM by analyzing the inner and diffusion layer structure. Energy-filtered TEM images were acquired to analyze the micrometric and nanometric distribution of elements in these layers. Such images from the inner layer revealed the presence of localized chromium enrichment regions associated with the presence of pores. Additionally, an iron-chromium nanometric segregation was observed and may be associated with the mixture of Fe3O4 and FeCr2O4. In the diffusion layer, small nanometric chromium-rich oxide particles were seen within metal grains. The (Fe,Cr)3O4 spinel oxide has an inverse spinel structure as Fe3O4 but becomes normal spinel as FeCr 2O4, thus the structure changes depending on the chromium content. Additionally, the spinel structure was analyzed using the ligand theory and showed that chromium does not migrate and that the main diffusing species is the Fe2+ ion. Calculations of the amount of iron leaving the inner layer showed that this amount accounted for the amount of iron necessary to form the outer layer, thus no dissolution of oxide in SCW is observed. Additionally, the differences in oxidation behavior in steam and SCW suggest that the rate-limiting step for the corrosion of ferritic-martensitic steels is the iron outward migration. The iron migration is driven by the gradient in the Fe2+/Fe 3+ ratio and is

  4. Low-Cycle Fatigue Properties of P92 Ferritic-Martensitic Steel at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen; Hu, ZhengFei; Schmauder, Siegfried; Mlikota, Marijo; Fan, KangLe

    2016-04-01

    The low-cycle fatigue behavior of P92 ferritic-martensitic steel and the corresponding microstructure evolution at 873 K has been extensively studied. The test results of fatigue lifetime are consistent with the Coffin-Manson relationship over a range of controlled total strain amplitudes from 0.15 to 0.6%. The influence of strain amplitude on the fatigue crack initiation and growth has been observed using optical microscopy and scanning electron microscopy. The formation mechanism of secondary cracks is established according to the observation of fracture after fatigue process and there is an intrinsic relationship between striation spacing, current crack length, and strain amplitude. Transmission electron microscopy has been employed to investigate the microstructure evolution after fatigue process. It indicates the interaction between carbides and dislocations together with the formation of cell structure inhibits the cyclic softening. The low-angle sub-boundary elimination in the martensite is mainly caused by the cyclic stress.

  5. Current status and recent research achievements in ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Tavassoli, A.-A. F.; Diegele, E.; Lindau, R.; Luzginova, N.; Tanigawa, H.

    2014-12-01

    When the austenitic stainless steel 316L(N) was selected for ITER, it was well known that it would not be suitable for DEMO and fusion reactors due to its irradiation swelling at high doses. A parallel programme to ITER collaboration already had been put in place, under an IEA fusion materials implementing agreement for the development of a low activation ferritic/martensitic steel, known for their excellent high dose irradiation swelling resistance. After extensive screening tests on different compositions of Fe-Cr alloys, the chromium range was narrowed to 7-9% and the first RAFM was industrially produced in Japan (F82H: Fe-8%Cr-2%W-TaV). All IEA partners tested this steel and contributed to its maturity. In parallel several other RAFM steels were produced in other countries. From those experiences and also for improving neutron efficiency and corrosion resistance, European Union opted for a higher chromium lower tungsten grade, Fe-9%Cr-1%W-TaV steel (Eurofer), and in 1997 ordered the first industrial heats. Other industrial heats have been produced since and characterised in different states, including irradiated up to 80 dpa. China, India, Russia, Korea and US have also produced their grades of RAFM steels, contributing to overall maturity of these steels. This paper reviews the work done on RAFM steels by the fusion materials community over the past 30 years, in particular on the Eurofer steel and its design code qualification for RCC-MRx.

  6. Neodymium-rich precipitate phases in a high-chromium ferritic/martensitic steel

    NASA Astrophysics Data System (ADS)

    Shen, Yinzhong; Zhou, Xiaoling; Shang, Zhongxia

    2016-05-01

    Neodymium being considered as nitride forming element has been used in a design of advanced ferritic/martensitic (FM) steels for fossil fired power plants at service temperatures of 630 °C to 650 °C to effectively improve the creep strength of the steels. To fully understand the characteristics of neodymium precipitates in high-Cr FM steels, precipitate phases in an 11Cr FM steel with 0.03 wt% addition of Nd have been investigated by transmission electron microscopy. Three neodymium phases with a face-centered cubic crystal structure and different composition were observed in the steel. They consisted of neodymium carbonitride with an average lattice parameter of 1.0836 nm, Nd-rich carbonitride mainly containing Mn, and Nd-rich MN nitride mainly containing Mn and Co. Other three Nd-rich and Nd-containing phases, which appear to be Nd-Co-Cr/Nd-rich intermetallic compounds and Cr-Fe-rich nitride containing Nd, were also detected in the steel. Nd-relevant precipitates were found to be minor phases compared with M23C6 and Nb/V/Ta-rich MX phases in the steel. The content of Nd in other precipitate phases was very low. Most of added Nd is considered to be present as solid solution in the matrix of the steel.

  7. Metallography studies and hardness measurements on ferritic/martensitic steels irradiated in STIP

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Long, B.; Dai, Y.

    2008-06-01

    In this work metallography investigations and microhardness measurements have been performed on 15 ferritic/martensitic (FM) steels and 6 weld metals irradiated in the SINQ Target Irradiation Program (STIP). The results demonstrate that all the steels have quite similar martensite lath structures. However, the sizes of the prior austenite grain (PAG) of these steels are quite different and vary from 10 to 86 μm. The microstructure in the fusion zones (FZ) of electron-beam welds (EBWs) of 5 steels (T91, EM10, MANET-II, F82H and Optifer-IX) is similar in respect to the martensite lath structure and PAG size. The FZ of the inert-gas-tungsten weld (TIGW) of the T91 steel shows a duplex structure of large ferrite gains and martensite laths. The microhardness measurements indicate that the normalized and tempered FM steels have rather close hardness values. The unusual high hardness values of the EBW and TIGW of the T91 steel were detected, which suggests that these materials are without proper tempering or post-welding heat treatment.

  8. Studies on A-TIG welding of Low Activation Ferritic/Martensitic (LAFM) steel

    NASA Astrophysics Data System (ADS)

    Vasantharaja, P.; Vasudevan, M.

    2012-02-01

    Low Activation Ferritic-Martensitic steels (LAFM) are chosen as the candidate material for structural components in fusion reactors. The structural components are generally fabricated by welding processes. Activated Tungsten Inert Gas (A-TIG) welding is an emerging process for welding of thicker components. In the present work, attempt was made to develop A-TIG welding technology for LAFM steel plates of 10 mm thick. Activated flux was developed for LAFM steel by carrying out various bead-on-plate TIG welds without flux and with flux. The optimum flux was identified as one which gave maximum depth of penetration at minimum heat input values. With the optimized flux composition, LAFM steel plate of 10 mm thickness was welded in square butt weld joint configuration using double side welding technique. Optical and Scanning Electron Microscopy was used for characterizing the microstructures. Microhardness measurements were made across the weld cross section for as welded and post weld heat treated samples. Tensile and impact toughness properties were determined. The mechanical properties values obtained in A-TIG weld joint were comparable to that obtained in weld joints of LAFM steel made by Electron beam welding process.

  9. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels.

    PubMed

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-02-02

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400-450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0-1.2 GPa at room temperature, which is nearly 3-5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

  10. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

    PubMed Central

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-01-01

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400–450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0–1.2 GPa at room temperature, which is nearly 3–5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry. PMID:28150692

  11. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

    NASA Astrophysics Data System (ADS)

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-02-01

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400–450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0–1.2 GPa at room temperature, which is nearly 3–5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

  12. Evolution of the mechanical properties and microstructure of ferritic-martensitic steels irradiated in the BOR-60 reactor

    NASA Astrophysics Data System (ADS)

    Shamardin, V. K.; Golovanov, V. N.; Bulanova, T. M.; Povstyanko, A. V.; Fedoseev, A. E.; Ostrovsky, Z. E.; Goncharenko, Yu. D.

    2002-12-01

    The effect of neutron irradiation on mechanical properties of low-activation ferritic-martensitic (FM) steels 0.1C-9Cr-1W, V, Ta, B and 0.1C-12Cr-2W, V, Ti, B is studied under tension at temperatures of 330-540 °C and doses of 50 dpa. Steel 0.1C-13Cr-Mo, V, Nb, B was chosen for comparison. At irradiation temperatures of 330-340 °C, the radiation hardening of steel with 9%Cr achieves saturation at a dose of 10 dpa. In this case as compared to steels with 12%Cr, the fracture surface is characterized as ductile without cleavage traces. At irradiation temperatures higher than 420 °C, there is no difference in the behavior of the materials under investigation. The data on radiation creep obtained by direct measurement and from the profilometry data satisfy a model ɛ¯/ σ¯=B 0+D Ṡ, when B0 and D have the values typical for steels of FM type.

  13. On the (in)adequacy of the Charpy impact test to monitor irradiation effects of ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Chaouadi, R.

    2007-02-01

    Irradiation embrittlement studies rely very often on Charpy impact data, in particular the ductile-to-brittle transition temperature (DBTT). However, while the DBTT-shift is equivalent to the increase of the fracture toughness transition temperature of ferritic steels, it is not the case for ferritic/martensitic steels. The aim of this study is to critically assess experimental data obtained on a 9%Cr-ferritic/martensitic steel, Eurofer-97, to better understand the underlying mechanisms involved during the fracture process. More specifically, a dedicated analysis using the load diagram approach allows to unambiguously reveal the actual effects of irradiation on physically rather than empirically based parameters. A comparison is made between a ferritic and ferritic/martensitic steel to better identify the possible similarities and differences. Tensile, Charpy impact and fracture toughness tests data are examined in a global approach to assess the actual rather than apparent irradiation effects. The adequacy or inadequacy of the Charpy impact test to monitor irradiation effects is extensively discussed.

  14. Precipitate phases in normalized and tempered ferritic/martensitic steel P92

    NASA Astrophysics Data System (ADS)

    Shen, Yinzhong; Liu, Huan; Shang, Zhongxia; Xu, Zhiqiang

    2015-10-01

    Ferritic/martensitic steel P92 is a promising candidate for cladding and duct applications in Sodium-Cooled Fast Reactor. The precipitate phases of the P92 steel normalized at 1323 K (1050 °C) for 30 min and tempered at 1038 K (765 °C) for 1 h have been investigated using transmission electron microscopes. Four types of phases consisting of M23C6, MX, M2X and sigma-FeCr were identified in the steel. MX phases consist of Nb-rich M(C,N) carbonitride, Nb-rich MC carbide, V-rich M(C,N) carbonitride, V-rich MC carbide, V-rich MN nitride, and complex MC carbides with Nb-rich MC core and V-rich MC wings. M2X phases consist of Cr-rich M2(C,N) carbonitride, Cr-rich M2C carbide and M2N nitride. Sigma-FeCr has a simple tetragonal lattice and a typical chemical formula of Fe0.45Cr0.45W0.1. M23C6 and MX are the dominant phases, while the sigma-FeCr has the lowest content. The formation of sigma-FeCr and M2X phases in the steel is also discussed.

  15. Microstructural evolution of ferritic-martensitic steels under heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Topbasi, Cem

    Ferritic-martensitic steels are primary candidate materials for fuel cladding and internal applications in the Sodium Fast Reactor, as well as first-wall and blanket materials in future fusion concepts because of their favorable mechanical properties and resistance to radiation damage. Since microstructure evolution under irradiation is amongst the key issues for these materials in these applications, developing a fundamental understanding of the irradiation-induced microstructure in these alloys is crucial in modeling and designing new alloys with improved properties. The goal of this project was to investigate the evolution of microstructure of two commercial ferritic-martensitic steels, NF616 and HCM12A, under heavy ion irradiation at a broad temperature range. An in situ heavy ion irradiation technique was used to create irradiation damage in the alloy; while it was being examined in a transmission electron microscope. Electron-transparent samples of NF616 and HCM12A were irradiated in situ at the Intermediate Voltage Electron Microscope (IVEM) at Argonne National Laboratory with 1 MeV Kr ions to ˜10 dpa at temperatures ranging from 20 to 773 K. The microstructure evolution of NF616 and HCM12A was followed in situ by systematically recording micrographs and diffraction patterns as well as capturing videos during irradiation. In these irradiations, there was a period during which no changes are visible in the microstructure. After a threshold dose (˜0.1 dpa between 20 and 573 K, and ˜2.5 dpa at 673 K) black dots started to become visible under the ion beam. These black dots appeared suddenly (from one frame to the next) and are thought to be small defect clusters (2-5 nm in diameter), possibly small dislocation loops with Burgers vectors of either ½ or . The overall density of these defect clusters increased with dose and saturated around 6 dpa. At saturation, a steady-state is reached in which defects are eliminated and created at the same rates so that the

  16. Parametric study of irradiation effects on the ductile damage and flow stress behavior in ferritic-martensitic steels

    NASA Astrophysics Data System (ADS)

    Chakraborty, Pritam; Biner, S. Bulent

    2015-10-01

    Ferritic-martensitic steels are currently being considered as structural materials in fusion and Gen-IV nuclear reactors. These materials are expected to experience high dose radiation, which can increase their ductile to brittle transition temperature and susceptibility to failure during operation. Hence, to estimate the safe operational life of the reactors, precise evaluation of the ductile to brittle transition temperatures of ferritic-martensitic steels is necessary. Owing to the scarcity of irradiated samples, particularly at high dose levels, micro-mechanistic models are being employed to predict the shifts in the ductile to brittle transition temperatures. These models consider the ductile damage evolution, in the form of nucleation, growth and coalescence of voids; and the brittle fracture, in the form of probabilistic cleavage initiation, to estimate the influence of irradiation on the ductile to brittle transition temperature. However, the assessment of irradiation dependent material parameters is challenging and influences the accuracy of these models. In the present study, the effects of irradiation on the overall flow stress and ductile damage behavior of two ferritic-martensitic steels is parametrically investigated. The results indicate that the ductile damage model parameters are mostly insensitive to irradiation levels at higher dose levels though the resulting flow stress behavior varies significantly.

  17. Proceedings of the IEA working group meeting on ferritic/martensitic steels

    SciTech Connect

    Klueh, R.L.

    1995-02-01

    An International Energy Agency (IEA) working group consist- ng of researchers from Japan, the European Union (EU), and the United States, met at the Oak Ridge National Laboratory (ORNL) 16 February 1995 to continue planning a collaborative test program on reduced-activation ferritic/martensitic steels for fusion applications. Plates from a 5-ton, a 1-ton, and three 150 kg heats of reduced-activation martensitic steels have been melted and processed to 7.5- and 15-mm plates in Japan. Plates were delivered in 1994 to the three parties that will participate in the test program. A second 5-ton IEA heat of modified F82H steel was produced in Japan in late 1994, and it was processed into 15- and 25-mm plates, which are to be shipped in February, 1995. Weldments will be produced on plates from this heat, and they will be shipped in April, 1995. At the ORNL meeting, a detailed test program and schedule was presented by the EU representatives, and less detailed programs were presented by the Japanese and US representatives. Detailed program schedules are required from the latter two programs to complete the program planning stage. A meeting is planned for 19--20 September 1995 in Switzerland to continue the planning and coordination of the test program and to present the preliminary results obtained in the collaboration.

  18. Effect of silicon on the microstructure and mechanical properties of reduced activation ferritic/martensitic steel

    NASA Astrophysics Data System (ADS)

    Chen, Shenghu; Rong, Lijian

    2015-04-01

    The effect of Si in the range of 0.05-0.77 wt.% on the microstructure, tensile properties and impact toughness of reduced activation ferritic/martensitic (RAFM) steels has been investigated. An increase in Si content affected the prior austenite grain size resulting in an increase in the tensile strength at room temperature. The tensile strength of steels tested above 773 K did not change significantly with the addition of Si, which was due to the diminished carbide hardening effect and boundary strengthening effect. Detailed fractographic analysis revealed that tear fractures occurred in the samples tensile tested at room temperature, while cup and cone fractures were found in samples tensile tested at temperatures above 773 K, which were induced by the easing of dislocation pile-ups. The ductile-to-brittle transition temperature (DBTT) decreased when the Si content increased to 0.22 wt.%. However, the DBTT increased when the Si content reached 0.77 wt.% and this was due to the precipitation of Laves phase. The RAFM steel with approximately 0.22 wt.% Si content was found to possess an optimized combination of microstructure, tensile properties and impact toughness.

  19. Microstructure control for high strength 9Cr ferritic-martensitic steels

    NASA Astrophysics Data System (ADS)

    Tan, L.; Hoelzer, D. T.; Busby, J. T.; Sokolov, M. A.; Klueh, R. L.

    2012-03-01

    Ferritic-martensitic (F-M) steels with 9 wt.%Cr are important structural materials for use in advanced nuclear reactors. Alloying composition adjustment, guided by computational thermodynamics, and thermomechanical treatment (TMT) were employed to develop high strength 9Cr F-M steels. Samples of four heats with controlled compositions were subjected to normalization and tempering (N&T) and TMT, respectively. Their mechanical properties were assessed by Vickers hardness and tensile testing. Ta-alloying showed significant strengthening effect. The TMT samples showed strength superior to the N&T samples with similar ductility. All the samples showed greater strength than NF616, which was either comparable to or greater than the literature data of the PM2000 oxide-dispersion-strengthened (ODS) steel at temperatures up to 650 °C without noticeable reduction in ductility. A variety of microstructural analyses together with computational thermodynamics provided rational interpretations on the strength enhancement. Creep tests are being initiated because the increased yield strength of the TMT samples is not able to deduce their long-term creep behavior.

  20. Development of new generation reduced activation ferritic-martensitic steels for advanced fusion reactors

    NASA Astrophysics Data System (ADS)

    Tan, L.; Snead, L. L.; Katoh, Y.

    2016-09-01

    International development of reduced activation ferritic-martensitic (RAFM) steels has focused on 9 wt percentage Cr, which primarily contain M23C6 (M = Cr-rich) and small amounts of MX (M = Ta/V, X = C/N) precipitates, not adequate to maintain strength and creep resistance above ∼500 °C. To enable applications at higher temperatures for better thermal efficiency of fusion reactors, computational alloy thermodynamics coupled with strength modeling have been employed to explore a new generation RAFM steels. The new alloys are designed to significantly increase the amount of MX nanoprecipitates, which are manufacturable through standard and scalable industrial steelmaking methods. Preliminary experimental results of the developed new alloys demonstrated noticeably increased amount of MX, favoring significantly improved strength, creep resistance, and Charpy impact toughness as compared to current RAFM steels. The strength and creep resistance were comparable or approaching to the lower bound of, but impact toughness was noticeably superior to 9-20Cr oxide dispersion-strengthened ferritic alloys.

  1. End Closure Joining of Ferritic-Martensitic and Oxide-Dispersion Strengthened Steel Cladding Tubes by Magnetic Pulse Welding

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Gu; Park, Jin-Ju; Lee, Min-Ku; Rhee, Chang-Kyu; Kim, Tae-Kyu; Spirin, Alexey; Krutikov, Vasiliy; Paranin, Sergey

    2015-07-01

    The magnetic pulse welding (MPW) technique was employed for the end closure joining of fuel pin cladding tubes made of ferritic-martensitic (FM) steel and oxide-dispersion strengthened (ODS) steel. The technique is a solid-state impact joining process based on the electromagnetic force, similar to explosive welding. For a given set of optimal process parameters, e.g., the end-plug geometry, the rigid metallurgical bonding between the tube and end plug was obtained by high-velocity impact collision accompanied with surface jetting. The joint region showed a typical wavy morphology with a narrow grain boundary-like bonding interface. There was no evidence of even local melting, and only the limited grain refinement was observed in the vicinity of the bonding interface without destructing the original reinforcement microstructure of the FM-ODS steel, i.e., a fine grain structure with oxide dispersion. No leaks were detected during helium leakage test, and moreover, the rupture occurred in the cladding tube section without leaving any joint damage during internal pressure burst test. All of the results proved the integrity and durability of the MPWed joints and signified the great potential of this method of end closure joining for advanced fast reactor fuel pin fabrication.

  2. Microstructural analysis of ferritic-martensitic steels irradiated at low temperature in HFIR

    SciTech Connect

    Hashimoto, N.; Robertson, J.P.; Rowcliffe, A.F.; Wakai, E.

    1998-09-01

    Disk specimens of ferritic-martensitic steel, HT9 and F82H, irradiated to damage levels of {approximately}3 dpa at irradiation temperatures of either {approximately}90 C or {approximately}250 C have been investigated by using transmission electron microscopy. Before irradiation, tempered HT9 contained only M{sub 23}C{sub 6} carbide. Irradiation at 90 C and 250 C induced a dislocation loop density of 1 {times} 10{sup 22} m{sup {minus}3} and 8 {times} 10{sup 21} m{sup {minus}3}, respectively. in the HT9 irradiated at 250 C, a radiation-induced phase, tentatively identified as {alpha}{prime}, was observed with a number density of less than 1 {times} 10{sup 20} m{sup {minus}3}. On the other hand, the tempered F82H contained M{sub 23}C{sub 6} and a few MC carbides; irradiation at 250 C to 3 dpa caused minor changes in these precipitates and induced a dislocation loop density of 2 {times} 10{sup 22} m{sup {minus}3}. Difference in the radiation-induced phase and the loop microstructure may be related to differences in the post-yield deformation behavior of the two steels.

  3. Void swelling in high dose ion-irradiated reduced activation ferritic-martensitic steels

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Monterrosa, Anthony M.; Zhang, Feifei; Huang, Hao; Yan, Qingzhi; Jiao, Zhijie; Was, Gary S.; Wang, Lumin

    2015-07-01

    To determine the void swelling resistance of reduced-activation ferritic-martensitic steels CNS I and CNS II at high doses, ion irradiation was performed up to 188 dpa (4.6 × 1017 ion/cm2) at 460 °C using 5 MeV Fe++ ions. Helium was pre-implanted at levels of 10 and 100 appm at room temperature to investigate the role of helium on void swelling. Commercial FM steel T91 was also irradiated in this condition and the swelling results are of included in this paper as a reference. Voids were observed in all conditions. The 9Cr CNS I samples implanted with 10 appm helium exhibited lower swelling than 9Cr T91 irradiated at the same condition. The 12Cr CNS II with 10 and 100 appm helium showed significantly lower swelling than CNS I and T91. The swelling rate for CNS I and CNS II were determined to be 0.02%/dpa and 0.003%/dpa respectively. Increasing the helium content from 10 to 100 appm shortened the incubation region and increased the void density but had no effect on the swelling rates.

  4. Blister formation on 13Cr2MoNbVB ferritic-martensitic steel exposed to hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Nikitin, A. V.; Tolstolutskaya, G. D.; Ruzhytskyi, V. V.; Voyevodin, V. N.; Kopanets, I. E.; Karpov, S. A.; Vasilenko, R. L.; Garner, F. A.

    2016-09-01

    The influence of pre-irradiation specimen deformation level on surface blister formation and sub-surface cracking of dual-phase 13Cr2MoNbVB ferritic-martensitic steel was studied using glow discharge hydrogen plasma with ion energy of 1 keV to fluences of 2 × 1025 H/m2. Protium was used for most studies, but deuterium was used for measuring the depth dependence of hydrogen diffusion. Formation of blisters was observed in the temperature range 230-340 K. It was found that pre-irradiation deformation caused changes in the threshold fluences of blister formation and also in blister size distribution. Subsurface cracks located on grain boundaries far beyond the implantation zone were formed concurrently with blisters, arising from hydrogen diffusion and trapping at defects. It was observed that cracks as long as 1 mm in length were formed in 95% deformed steel at depths up to 500 μm from surface.

  5. Neutron irradiation effects on the ductile-brittle transition of ferritic/martensitic steels

    SciTech Connect

    Klueh, R.L.; Alexander, D.J.

    1997-06-01

    Ferritic/martensitic steels such as the conventional 9Cr-1MoVNb (Fe-9Cr-1Mo-0.25V-0.06Nb-0.1C) and 12Cr-1MoVW (Fe-12Cr-1Mo-0.25V-0.5W-0.5Ni-0.2C) steels have been considered potential structural materials for future fusion power plants. The major obstacle to their use is embrittlement caused by neutron irradiation. Observations on this irradiation embrittlement will be reviewed. Below 425-450{degrees}C, neutron irradiation hardens the steels. Hardening reduces ductility, but the major effect is an increase in the ductile-brittle transition temperature (DBTT) and a decrease in the upper-shelf energy, as measured by a Charpy impact test. After irradiation, DBTT values can increase to well above room temperature, thus increasing the chances of brittle rather than ductile fracture. In addition to irradiation hardening, neutrons from the fusion reaction will produce large amounts of helium in the steels used to construct fusion power plant components. Tests to simulate the fusion environment indicate that helium can also affect the toughness. Steels are being developed for fusion applications that have a low DBTT prior to irradiation and then show only a small shift after irradiation. A martensitic 9Cr-2WVTa (nominally Fe-9Cr-2W-0.25V-0.07Ta-0.1C) steel had a much lower DBTT than the conventional 9Cr-1MoVNb steel prior to neutron irradiation and showed a much smaller increase in DBTT after irradiation. 27 refs., 5 figs., 1 tab.

  6. Assessment of Tungsten Content on Tertiary Creep Deformation Behavior of Reduced Activation Ferritic-Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Vanaja, J.; Laha, Kinkar

    2015-10-01

    Tertiary creep deformation behavior of reduced activation ferritic-martensitic (RAFM) steels having different tungsten contents has been assessed. Creep tests were carried out at 823 K (550 °C) over a stress range of 180 to 260 MPa on three heats of the RAFM steel (9Cr-W-0.06Ta-0.22V) with tungsten content of 1, 1.4, and 2.0 wt pct. With creep exposure, the steels exhibited minimum in creep rate followed by progressive increase in creep rate until fracture. The minimum creep rate decreased, rupture life increased, and the onset of tertiary stage of creep deformation delayed with the increase in tungsten content. The tertiary creep behavior has been assessed based on the relationship, , considering minimum creep rate () instead of steady-state creep rate. The increase in tungsten content was found to decrease the rate of acceleration of tertiary parameter ` p.' The relationships between (1) tertiary parameter `p' with minimum creep rate and time spent in tertiary creep deformation and (2) the final creep rate with minimum creep rate revealed that the same first-order reaction rate theory prevailed in the minimum creep rate as well as throughout the tertiary creep deformation behavior of the steel. A master tertiary creep curve of the steels has been developed. Scanning electron microscopic investigation revealed enhanced coarsening resistance of carbides in the steel on creep exposure with increase in tungsten content. The decrease in tertiary parameter ` p' with tungsten content with the consequent decrease in minimum creep rate and increase in rupture life has been attributed to the enhanced microstructural stability of the steel.

  7. Influence of structural-phase state of ferritic-martensitic steels on the helium porosity development

    NASA Astrophysics Data System (ADS)

    Chernov, I. I.; Staltsov, M. S.; Kalin, B. A.; Bogachev, I. A.; Guseva, L. Yu; Dzhumaev, P. S.; Emelyanova, O. V.; Drozhzhina, M. V.; Manukovsky, K. V.; Nikolaeva, I. D.

    2016-04-01

    Transmission electron microscopy (TEM) has been used to study the effect of the initial structural-phase state (SPhS) of ferritic-martensitic steels EK-181, EP-450 and EP-450- ODS (with 0.5 wt.% nanoparticles of Y2O3) on the of helium porosity formation and gas swelling. Different SPhS of steel EK-181 was produced by water quenching, annealing, normalizing plus tempered, intensive plastic deformation by torsion (HPDT). Irradiation was carried out by He+-40 keV ions at 923 K up to fluence of 5-1020 He+/m2. It is shown that the water quenching causes the formation of uniformly distributed small bubbles (d¯ ∼ 2 nm) of the highest density (ρ∼ 1025 m-3). After normalization followed by tempering as well as after annealing bubbles distribution is highly non-uniform both by volume and in size. Very large faceted bubbles (pre-equilibrium gas-filled voids) are formed in ferrite grains resulting in high level of gas swelling of the irradiated layer with S = 4,9 ± 1,2 and 3.8 ± 0.9% respectively. Nano- and microcrystalline structure created by HPDT completely degenerate at irradiation temperature and ion irradiation formed bubbles of the same parameters as in the annealed steel. Bubbles formed in EP-450-ODS steel are smaller in size and density, which led to a decrease of helium swelling by 4 times (S = 0.8 ± 0.2%) as compared to the swelling of the matrix steel EP-450 (S = 3.1 ± 0.7%).

  8. Impact of the use of the ferritic/martensitic ODS steels cladding on the fuel reprocessing PUREX process

    NASA Astrophysics Data System (ADS)

    Gwinner, B.; Auroy, M.; Mas, D.; Saint-Jevin, A.; Pasquier-Tilliette, S.

    2012-09-01

    Some ferritic/martensitic oxide dispersed strengthened (F/M ODS) steels are presently developed at CEA for the fuel cladding of the next generation of sodium fast nuclear reactors. The objective of this work is to study if this change of cladding could have any consequences on the spent fuel reprocessing PUREX process. During the fuel dissolution stage the cladding can actually be corroded by nitric acid. But some process specifications impose not to exceed a limit concentration of the corrosion products such as iron and chromium in the dissolution medium. For that purpose the corrosion behavior of these F/M ODS steels is studied in hot and concentrated nitric acid. The influence of some metallurgical parameters such as the chromium content, the elaboration process and the presence of the yttrium oxides is first discussed. The influence of environmental parameters such as the nitric acid concentration, the temperature and the presence of oxidizing species coming from the fuel is then analyzed. The corrosion rate is characterized by mass loss measurements and electrochemical tests. Analyses of the corroded surface are carried out by X-ray photoelectron spectroscopy.

  9. A reassessment of the effects of helium on Charpy impact properties of ferritic/martensitic steels

    SciTech Connect

    Gelles, D.S.; Hamilton, M.L.; Hankin, G.L.

    1998-03-01

    To test the effect of helium on Charpy impact properties of ferritic/martensitic steels, two approaches are reviewed: quantification of results of tests performed on specimens irradiated in reactors with very different neutron spectra, and isotopic tailoring experiments. Data analysis can show that if the differences in reactor response are indeed due to helium effects, then irradiation in a fusion machine at 400 C to 100 dpa and 1000 appm He will result in a ductile to brittle transition temperature shift of over 500 C. However, the response as a function of dose and helium level is unlikely to be simply due to helium based on physical reasoning. Shear punch tests and microstructural examinations also support this conclusion based on irradiated samples of a series of alloys made by adding various isotopes of nickel in order to vary the production of helium during irradiation in HFIR. The addition of nickel at any isotopic balance to the Fe-12Cr base alloy significantly increased the shear yield and maximum strengths of the alloys. However, helium itself, up to 75 appm at over 7 dpa appears to have little effect on the mechanical properties of the alloys. This behavior is instead understood to result from complex precipitation response. The database for effects of helium on embrittlement based on nickel additions is therefore probably misleading and experiments should be redesigned to avoid nickel precipitation.

  10. A review of some effects of helium on charpy impact properties of ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Gelles, D. S.; Hankin, G. L.; Hamilton, M. L.

    1998-10-01

    To evaluate the effect of helium on Charpy impact properties of ferritic/martensitic steels, two approaches are reviewed: quantification of results of earlier tests performed by other researchers on specimens irradiated in reactors with very different neutron spectra, and evaluation of isotopic tailoring experiments. Data analysis can show that if the differences in reactor response are indeed due to helium effects, then irradiation in a fusion machine at 400°C to 100 dpa and 1000 appm He will result in a ductile-to-brittle transition temperature (DBTT) shift of over 500°C. However, it can be shown that the response as a function of dose and helium level is unlikely to be simply due to helium based on physical reasoning. Shear punch tests and microstructural examinations support this conclusion based on irradiated samples of a series of alloys made by adding various isotopes of nickel in order to vary the production of helium during irradiation in High Flux Isotope Reactor (HFIR). The addition of nickel at any isotopic balance to the Fe-12Cr base alloy significantly increased the shear yield and maximum strengths of the alloys. However, helium itself, up to 75 appm at over 7 dpa appears to have little effect on the mechanical properties of the alloys. This behavior is instead understood to result from complex precipitation response. The database for effects of helium on embrittlement based on nickel additions is therefore probably misleading and experiments should be redesigned to avoid nickel precipitation.

  11. The development of ferritic-martensitic steels with reduced long-term activation

    NASA Astrophysics Data System (ADS)

    Ehrlich, K.; Kelzenberg, S.; Röhrig, H.-D.; Schäfer, L.; Schirra, M.

    1994-09-01

    Ferritic-martensitic 9-12% CrMoVNb steels of MANET type possess a number of advantageous properties for fusion reactor application. Their optimization has led to improved creep and fracture-toughness properties. New 9-10% CrWVTa alloys have been developed by KfK/IMF in collaboration with the SAARSTAHL GmbH which have a reduced long-term activation and show in addition superior fracture toughness properties. The calculation of dose rate and other radiological parameters with the presently available FISPACT/EAF codes, extended by KfK files for sequential reactions has shown that the long-term dose-rate in these alloys is governed by the remaining 'impurity level' of Nb and the alloying elements W and Ta. Sequential reactions — though relevant for single alloying elements like Cr, Mn, V and N — provide only a second order effect in Fe-based alloys. A challenge for the future materials development is the production of alloys with the desired narrow specification of elements and impurities, which necessitates new ways of steelmaking.

  12. Formation and Oxidation Performance of Low-Temperature Pack Aluminide Coatings on Ferritic-Martensitic Steels

    SciTech Connect

    Bates, Brian; Wang, Y. Q.; Zhang, Ying; Pint, Bruce A

    2009-01-01

    A pack cementation process was developed to coat commercial 9% Cr ferritic-martensitic steel T91 at temperatures below its normal tempering temperature to avoid any potential detrimental effect on the mechanical properties of the coated alloy. In order to prevent the formation of Fe{sub 2}Al{sub 5} coatings, the Al activity in the pack cementation process was reduced by substituting the pure Al masteralloy with binary Cr-Al masteralloys containing either 15 or 25 wt.% Al. When the Cr-25Al masteralloy was used, a duplex coating was formed at 700 C, consisting of a thin Fe{sub 2}Al{sub 5} outer layer and an inner layer of FeAl. With the Cr-15Al masteralloy, an FeAl coating of {approx} 12 {micro}m thick was achieved at 700 C. The pack aluminide coatings fabricated at 700 C are being evaluated in air + 10 vol.% H{sub 2}O at 650 C and 700 C to determine their long-term oxidation performance.

  13. In-beam fatigue of a ferritic-martensitic steel. First results

    NASA Astrophysics Data System (ADS)

    Marmy, P.

    1994-09-01

    Due to its pulsed operation mode, a fusion device will have to sustain thermal stresses and at the same time be exposed to a flux of 14 MeV neutrons. In order to simulate this irradiation condition, a new irradiation device has been developed, in which the specimen can be stress and strain-controlled during the irradiation. For the simulation of the fusion neutrons, a 590 MeV proton beam is used. This type of particle produces from spallation reactions the displacement damage and the helium typical of fusion neutrons in the material. The influence of the in situ deformation on the low cycle fatigue of a 12% Cr ferritic-martensitic steel (MANET II) has been investigated. The results are compared with results from non-irradiated specimens and from specimens tested after irradiation to the same end-of-life fluence. The effects of the different conditions are reported for a temperature TTest = TIrr = 573 K and a total imposed strain of 0.7%.

  14. High strain fatigue properties of F82H ferritic martensitic steel under proton irradiation

    NASA Astrophysics Data System (ADS)

    Marmy, P.; Oliver, B. M.

    2003-05-01

    During the up and down cycles of a fusion reactor, the first wall is exposed concomitantly to a flux of energetic neutrons that generates radiation defects and to a thermal flux that induces thermal stresses. The resulting strains may exceed the elastic limit and induce plastic deformation in the material. A similar situation occurs in the window of a spallation liquid source target and results in the same type of damage. This particular loading has been simulated in F82H ferritic-martensitic steel, using a device allowing a fatigue test to be carried out during irradiation with 590 MeV protons. All fatigue tests were carried out in a strain controlled test at strain levels around 0.8% and at 300 °C. Two different signals have been used: a fully symmetrical triangle wave signal ( R=-1) and a triangle ramp with 2 min tension holds. The fatigue was investigated under three different conditions: unirradiated, irradiated and post-irradiation tested, and finally in-beam tested. The main result is that the in-beam tested specimens have the lowest life as compared to the post-irradiation tested specimen and unirradiated specimen. Hydrogen is suspected to be the main contributor to the observed embrittlement.

  15. Diffusive transport parameters of deuterium through China reduced activation ferritic-martensitic steels

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Liu, Lingbo; Xiang, Xin; Rao, Yongchu; Ye, Xiaoqiu; Chen, Chang An

    2016-03-01

    Reduced Activation Ferritic/Martensitic (RAFM) steels have been considered as the most promising candidate structure materials for a fusion reactor. In the recent decades, two new types of RAFM steels, called China Low Activation Martensitic (CLAM) steel and China Low-activation Ferritic (CLF-1) steel, have been developed. The gas evolution permeation technique has been used to investigate diffusive transport parameters of deuterium through CLAM and CLF-1 over the temperature range 623 ∼ 873 K at deuterium pressure of 105 Pa. The resultant transport parameters are: Φ (mol. m-1 s-1 Pa-1/2) = 5.40 × 10-8 exp (-46.8 (kJ. mol-1)/RT), D(m2 s-1) = 3.81 × 10-7 exp(-24.0(kJ. mol-1)/RT) and S (mol. m-3 Pa-1/2) = 1.42 × 10-1 exp(-22.8(kJ. mol-1)/RT) for CLAM; while Φ(mol m-1 s-1 Pa-1/2) = 1.76 × 10-8 exp(-43.9(kJ. mol-1)/RT), D(m2. s-1) = 1.02 × 10-7 exp(-16.9(kJ. mol-1)/RT) and S(mol. m-1 Pa-1/2) = 1.73 × 10-1 exp(-27.0(kJ. mol-1) /RT) for CLF-1. The results show that CLAM is more permeable than CLF-1, thus it is easier for hydrogen isotopes to transport and be removed.

  16. Irradiation performance of 9--12 Cr ferritic/martensitic stainless steels and their potential for in-core application in LWRs

    SciTech Connect

    Jones, R.H.; Gelles, D.S.

    1993-08-01

    Ferritic-martensitic stainless steels exhibit radiation stability and stress corrosion resistance that make them attractive replacement materials for austenitic stainless steels for in-core applications. Recent radiation studies have demonstrated that 9% Cr ferritic/martensitic stainless steel had less than a 30C shift in ductile-to-brittle transition temperature (DBTT) following irradiation at 365C to a dose of 14 dpa. These steels also exhibit very low swelling rates, a result of the microstructural stability of these alloys during radiation. The 9 to 12% Cr alloys to also exhibit excellent corrosion and stress corrosion resistance in out-of-core applications. Demonstration of the applicability of ferritic/martensitic stainless steels for in-core LWR application will require verification of the irradiation assisted stress corrosion cracking behavior, measurement of DBTT following irradiation at 288C, and corrosion rates measurements for in-core water chemistry.

  17. Fractographic examination of reduced activation ferritic/martensitic steel charpy specimens irradiated to 30 dpa at 370{degrees}C

    SciTech Connect

    Gelles, D.S.; Hamilton, M.L.; Schubert, L.E.

    1996-10-01

    Fractographic examinations are reported for a series of reduced activation ferritic/Martensitic steel Charpy impact specimens tested following irradiation to 30 dpa at 370{degrees}C in FFTF. One-third size specimens of six low activation steels developed for potential application as structural materials in fusion reactors were examined. A shift in brittle fracture appearance from cleavage to grain boundary failure was noted with increasing manganese content. The results are interpreted in light of transmutation induced composition changes in a fusion environment.

  18. Influence of helium on deuterium retention in reduced activation ferritic martensitic steel (F82H) under simultaneous deuterium and helium irradiation

    NASA Astrophysics Data System (ADS)

    Yakushiji, K.; Lee, H. T.; Oya, M.; Hamaji, Y.; Ibano, K.; Ueda, Y.

    2016-02-01

    Deuterium and helium retention in Japanese reduced activation ferritic martensitic (RAFM) steel (F82H) under simultaneous D-He irradiation at 500, 625, 750, and 818 K was studied. This study aims to clarify tritium retention behavior in RAFM steels to assess their use as plasma facing materials. The irradiation fluence was kept constant at 1 × 1024 D m-2. Four He desorption peaks were observed with He retention greatest at 625 K. At T > 625 K a monotonic decrease in He retention was observed. At all temperatures a systematic reduction in D retention was observed for the simultaneous D-He case in comparison to D-only case. This suggests that He implanted at the near surface in RAFM steels may reduce the inward penetration of tritium in RAFM steels that would result in lower tritium inventory for a given fluence.

  19. Gap Analysis of Material Properties Data for Ferritic/Martensitic HT-9 Steel

    SciTech Connect

    Brown, Neil R.; Serrano De Caro, Magdalena; Rodriguez, Edward A.

    2012-08-28

    The US Department of Energy (DOE), Office of Nuclear Energy (NE), is supporting the development of an ASME Code Case for adoption of 12Cr-1Mo-VW ferritic/martensitic (F/M) steel, commonly known as HT-9, primarily for use in elevated temperature design of liquid-metal fast reactors (LMFR) and components. In 2011, Los Alamos National Laboratory (LANL) nuclear engineering staff began assisting in the development of a small modular reactor (SMR) design concept, previously known as the Hyperion Module, now called the Gen4 Module. LANL staff immediately proposed HT-9 for the reactor vessel and components, as well as fuel clad and ducting, due to its superior thermal qualities. Although the ASME material Code Case, for adoption of HT-9 as an approved elevated temperature material for LMFR service, is the ultimate goal of this project, there are several key deliverables that must first be successfully accomplished. The most important key deliverable is the research, accumulation, and documentation of specific material parameters; physical, mechanical, and environmental, which becomes the basis for an ASME Code Case. Time-independent tensile and ductility data and time-dependent creep and creep-rupture behavior are some of the material properties required for a successful ASME Code case. Although this report provides a cursory review of the available data, a much more comprehensive study of open-source data would be necessary. This report serves three purposes: (a) provides a list of already existing material data information that could ultimately be made available to the ASME Code, (b) determines the HT-9 material properties data missing from available sources that would be required and (c) estimates the necessary material testing required to close the gap. Ultimately, the gap analysis demonstrates that certain material properties testing will be required to fulfill the necessary information package for an ASME Code Case.

  20. Development of Advanced 9Cr Ferritic-Martensitic Steels and Austenitic Stainless Steels for Sodium-Cooled Fast Reactor

    SciTech Connect

    Sham, Sam; Tan, Lizhen; Yamamoto, Yukinori

    2013-01-01

    Ferritic-martensitic (FM) steel Grade 92, with or without thermomechanical treatment (TMT), and austenitic stainless steels HT-UPS (high-temperature ultrafine precipitate strengthening) and NF709 were selected as potential candidate structural materials in the U.S. Sodium-cooled Fast Reactor (SFR) program. The objective is to develop advanced steels with improved properties as compared with reference materials such as Grade 91 and Type 316H steels that are currently in nuclear design codes. Composition modification and/or processing optimization (e.g., TMT and cold-work) were performed to improve properties such as resistance to thermal aging, creep, creep-fatigue, fracture, and sodium corrosion. Testings to characterize these properties for the advanced steels were conducted by the Idaho National Laboratory, the Argonne National Laboratory and the Oak Ridge National Laboratory under the U.S. SFR program. This paper focuses on the resistance to thermal aging and creep of the advanced steels. The advanced steels exhibited up to two orders of magnitude increase in creep life compared to the reference materials. Preliminary results on the weldment performance of the advanced steels are also presented. The superior performance of the advanced steels would improve reactor design flexibility, safety margins and economics.

  1. Annealing effects on the microstructure and coercive field of two ferritic-martensitic Eurofer steels: A comparative study

    NASA Astrophysics Data System (ADS)

    Oliveira, V. B.; Sandim, M. J. R.; Stamopoulos, D.; Renzetti, R. A.; Santos, A. D.; Sandim, H. R. Z.

    2013-04-01

    Reduced-activation ferritic-martensitic steels are promising candidates for structural applications in future nuclear fusion power plants. Oxide dispersion strengthened ODS-Eurofer and Eurofer 97 steels were cold rolled to 80% reduction in thickness and annealed in vacuum for 1 h from 200 to 1350 °C to evaluate both their thermal stability and magnetic behavior. The microstructural changes were followed by magnetic measurements, in particular the corresponding variation of the coercive field (Hc), as a function of both annealing and tempering treatments. Results show that Y2O3 nanoparticles strongly affect the mechanical properties of ODS-Eurofer steel but leave their magnetic properties fairly unchanged when compared with Eurofer-97 steel.

  2. Diffusion Bonding Beryllium to Reduced Activation Ferritic Martensitic Steel: Development of Processes and Techniques

    NASA Astrophysics Data System (ADS)

    Hunt, Ryan Matthew

    Only a few materials are suitable to act as armor layers against the thermal and particle loads produced by magnetically confined fusion. These candidates include beryllium, tungsten, and carbon fiber composites. The armor layers must be joined to the plasma facing components with high strength bonds that can withstand the thermal stresses resulting from differential thermal expansion. While specific joints have been developed for use in ITER (an experimental reactor in France), including beryllium to CuCrZr as well as tungsten to stainless steel interfaces, joints specific to commercially relevant fusion reactors are not as well established. Commercial first wall components will likely be constructed front Reduced Activation Ferritic Martensitic (RAFM) steel, which will need to be coating with one of the three candidate materials. Of the candidates, beryllium is particularly difficult to bond, because it reacts during bonding with most elements to form brittle intermetallic compounds. This brittleness is unacceptable, as it can lead to interface crack propagation and delamination of the armor layer. I have attempted to overcome the brittle behavior of beryllium bonds by developing a diffusion bonding process of beryllium to RAFM steel that achieves a higher degree of ductility. This process utilized two bonding aids to achieve a robust bond: a. copper interlayer to add ductility to the joint, and a titanium interlayer to prevent beryllium from forming unwanted Be-Cu intermetallics. In addition, I conducted a series of numerical simulations to predict the effect of these bonding aids on the residual stress in the interface. Lastly, I fabricated and characterized beryllium to ferritic steel diffusion bonds using various bonding parameters and bonding aids. Through the above research, I developed a process to diffusion bond beryllium to ferritic steel with a 150 M Pa tensile strength and 168 M Pa shear strength. This strength was achieved using a Hot Isostatic

  3. HEAT INPUT AND POST WELD HEAT TREATMENT EFFECTS ON REDUCED-ACTIVATION FERRITIC/MARTENSITIC STEEL FRICTION STIR WELDS

    SciTech Connect

    Tang, Wei; Chen, Gaoqiang; Chen, Jian; Yu, Xinghua; Frederick, David Alan; Feng, Zhili

    2015-01-01

    Reduced-activation ferritic/martensitic (RAFM) steels are an important class of structural materials for fusion reactor internals developed in recent years because of their improved irradiation resistance. However, they can suffer from welding induced property degradations. In this paper, a solid phase joining technology friction stir welding (FSW) was adopted to join a RAFM steel Eurofer 97 and different FSW parameters/heat input were chosen to produce welds. FSW response parameters, joint microstructures and microhardness were investigated to reveal relationships among welding heat input, weld structure characterization and mechanical properties. In general, FSW heat input results in high hardness inside the stir zone mostly due to a martensitic transformation. It is possible to produce friction stir welds similar to but not with exactly the same base metal hardness when using low power input because of other hardening mechanisms. Further, post weld heat treatment (PWHT) is a very effective way to reduce FSW stir zone hardness values.

  4. Irradiation effects on precipitation and its impact on the mechanical properties of reduced-activation ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Tanigawa, H.; Sakasegawa, H.; Hashimoto, N.; Klueh, R. L.; Ando, M.; Sokolov, M. A.

    2007-08-01

    It was previously reported that reduced-activation ferritic/martensitic steels (RAFs) showed a variety of changes in ductile-brittle transition temperature (DBTT) and yield stress after irradiation at 573 K up to 5 dpa. The precipitation behavior of the irradiated steels was examined and the presence of irradiation induced precipitation which works as if it was forced to reach the thermal equilibrium state at irradiation temperature 573 K. In this study, transmission electron microscopy was performed on extraction replica specimens to analyze the size distribution of precipitates. It turned out that the hardening level multiplied by the square root of the average block size showed a linear dependence on the extracted precipitate weight. This dependence suggests that the difference in irradiation hardening between RAFs was caused by different precipitation behavior on block, packet and prior austenitic grain boundaries during irradiation. The simple Hall-Petch law could be applicable for interpreting this dependence.

  5. Charpy Impact Properties of Reduced-Activation Ferritic/Martensitic Steels Irradiated in HFIR up to 20 dpa

    SciTech Connect

    Tanigawa, H.; Shiba, K.; Sokolov, M.A.; Klueh, R.L.

    2003-07-15

    The effects of irradiation up to 20 dpa on the Charpy impact properties of reduced-activation ferritic/martensitic steels (RAFs) were investigated. The ductile-brittle transition temperature (DBTT) of F82H-IEA shifted up to around 323K. TIG weldments of F82H showed a fairly small variation on their impact properties. A finer prior austenite grain size in F82H-IEA after a different heat treatment resulted in a 20K lower DBTT compared to F82H-IEA after the standard heat treatment, and that effect was maintained even after irradiation. Helium effects were investigated utilizing Ni-doped F82H, but no obvious evidence of helium effects was obtained. ORNL9Cr-2WVTa and JLF-1 steels showed smaller DBTT shifts compared to F82H-IEA.

  6. IRRADIATION CREEP AND MECHANICAL PROPERTIES OF TWO FERRITIC-MARTENSITIC STEELS IRRADIATED IN THE BN-350 FAST REACTOR

    SciTech Connect

    Porollo, S. I.; Konobeev, Yu V.; Dvoriashin, A. M.; Budylkin, N. I.; Mironova, E. G.; Leontyeva-Smirnova, M. V.; Loltukhovsky, A. G.; Bochvar, A. A.; Garner, Francis A.

    2002-09-01

    Russian ferritic/martensitic steels EP-450 and EP-823 were irradiated to 20-60 dpa in the BN-350 fast reactor in the form of pressurized creep tubes and small rings used for mechanical property tests. Data derived from these steels serves to enhance our understanding of the general behavior of this class of steels. It appears that these steels exhibit behavior that is very consistent with that of Western steels. Swelling is relatively low at high neutron exposure and confined to temperatures less then 420 degrees C, but may be camouflaged somewhat by precipitation-related densification. The irradiation creep studies confirm that the creep compliance of F/M steels is about one-half that of austenitic steels, and that the loss of strength at test temperatures above 500 degrees C is a problem generic to all F/M steels. This conclusion is supported by post-irradiation measurement of short-term mechanical properties. At temperatures below 500 degrees C both steels retain their high strength (yield stress 0.2=550-600 MPa), but at higher test temperatures a sharp decrease of strength properties occurs. However, the irradiated steels still retain high post-irradiation ductility at test temperatures in the range of 20-700 degrees C.

  7. Effect of constituent phase on mechanical properties of 9Cr-1WVTa reduced activation ferritic-martensitic steels

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Hoon; Moon, Joonoh; Park, Min-Gu; Lee, Tae-Ho; Jang, Min-Ho; Kim, Hyoung Chan; Suh, Dong-Woo

    2014-12-01

    Influence of the formation of ferrite and accompanying carbides in martensite matrix on the tensile and Charpy impact properties was investigated for reduced activation ferritic-martensitic (RAFM) 9Cr-1WVTa steel. As the fractions of ferrite and carbide adjacent to the ferrite grain boundary increase, both tensile and Charpy impact properties deteriorated in as-normalized condition. In particular, the tensile strength and elongation decreased simultaneously, which is believed to be led by the localized deformation in ferrite which is softer than martensite, promoting the formation and growth of voids. In addition, the formation of ferrite was also detrimental to the Charpy impact properties regarding to the absorbed energy because the precipitation of carbides around ferrite were vulnerable to the nucleation and propagation of cleavage cracks. The degradation of tensile properties can be recovered by tempering, but the DBTT temperature still increases with presence of ferrite.

  8. Determining the shear fracture properties of HIP joints of reduced-activation ferritic/martensitic steel by a torsion test

    NASA Astrophysics Data System (ADS)

    Nozawa, Takashi; Noh, Sanghoon; Tanigawa, Hiroyasu

    2012-08-01

    Hot isostatic pressing (HIP) is a key technology used to fabricate a first wall with cooling channels for the fusion blanket system utilizing a reduced-activation ferritic/martensitic steel. To qualify the HIPped components, small specimen test techniques are beneficial not only to evaluate the thin-wall cooling channels containing the HIP joint but also to use in neutron irradiation studies. This study aims to develop the torsion test method with special emphasis on providing a reasonable and comprehensive method to determine interfacial shear properties of HIP joints during the torsional fracture process. Torsion test results identified that the torsion process shows yield of the base metal followed by non-elastic deformation due to work hardening of the base metal. By considering this work hardening issue, we propose a reasonable and realistic solution to determine the torsional yield shear stress and the ultimate torsional shear strength of the HIPped interface. Finally, a representative torsion fracture process was identified.

  9. Effect of Austenization Temperature on the Microstructure and Strength of 9% and 12% Cr Ferritic-Martensitic Steels

    SciTech Connect

    Terry C. Totemeier

    2004-10-01

    The effect of reduced-temperature austenization on the microstructure and strength of two ferritic-martensitic steels was studied. Prototypic 9% and 12% Cr steels, grade 91 (9Cr-1MoVNb) and type 422 stainless (12Cr-1MoVW), respectively, were austenized at 925°C and 1050°C and tempered at 760°C. The reduced austenization temperature was intended to simulate potential inadequate austenization during field construction of large structures and also the thermal cycle experienced in the Type IV region of weld heat affected zones (HAZ). The microstructure, tensile behavior, and creep strength were characterized for both steels treated at each condition. The reduced austenization temperature resulted in general coarsening of carbides in both steels and polygonization of the tempered martensite structure in type 422. For this steel, a marked reduction in microhardness was observed, while there was little change in microhardness for grade 91. Slight reductions in tensile strength were observed for both steels at room temperature and elevated temperatures of 450 and 550°C. The strength reduction was greater for type 422 than for grade 91. At 650°C the tensile strength reduction was minimal for both steels. Marked reductions in creep rupture lives were observed for both steels at 650°C; the reductions were less at 600°C and minimal at 550°C. Overall, the higher Cr content steel was observed to be more sensitive to variations in heat treatment conditions.

  10. Summary Report of Summer Work: High Purity Single Crystal Growth & Microstructure of Ferritic-Martensitic Steels

    SciTech Connect

    Pestovich, Kimberly Shay

    2015-08-18

    Harnessing the power of the nuclear sciences for national security and to benefit others is one of Los Alamos National Laboratory’s missions. MST-8 focuses on manipulating and studying how the structure, processing, properties, and performance of materials interact at the atomic level under nuclear conditions. Within this group, single crystal scintillators contribute to the safety and reliability of weapons, provide global security safeguards, and build on scientific principles that carry over to medical fields for cancer detection. Improved cladding materials made of ferritic-martensitic alloys support the mission of DOE-NE’s Fuel Cycle Research and Development program to close the nuclear fuel cycle, aiming to solve nuclear waste management challenges and thereby increase the performance and safety of current and future reactors.

  11. Microstructural characterization of weld joints of 9Cr reduced activation ferritic martensitic steel fabricated by different joining methods

    SciTech Connect

    Thomas Paul, V.; Saroja, S.; Albert, S.K.; Jayakumar, T.; Rajendra Kumar, E.

    2014-10-15

    This paper presents a detailed electron microscopy study on the microstructure of various regions of weldment fabricated by three welding methods namely tungsten inert gas welding, electron beam welding and laser beam welding in an indigenously developed 9Cr reduced activation ferritic/martensitic steel. Electron back scatter diffraction studies showed a random micro-texture in all the three welds. Microstructural changes during thermal exposures were studied and corroborated with hardness and optimized conditions for the post weld heat treatment have been identified for this steel. Hollomon–Jaffe parameter has been used to estimate the extent of tempering. The activation energy for the tempering process has been evaluated and found to be corresponding to interstitial diffusion of carbon in ferrite matrix. The type and microchemistry of secondary phases in different regions of the weldment have been identified by analytical transmission electron microscopy. - Highlights: • Comparison of microstructural parameters in TIG, electron beam and laser welds of RAFM steel • EBSD studies to illustrate the absence of preferred orientation and identification of prior austenite grain size using phase identification map • Optimization of PWHT conditions for indigenous RAFM steel • Study of kinetics of tempering and estimation of apparent activation energy of the process.

  12. Fracture toughness of the IEA heat of F82H ferritic/martensitic stainless steel as a function of loading mode

    SciTech Connect

    Li, Huaxin; Gelles, D.S.; Hirth, J.P.

    1997-04-01

    Mode I and mixed-mode I/III fracture toughness tests were performed for the IEA heat of the reduced activation ferritic/martensitic stainless steel F82H at ambient temperature in order to provide comparison with previous measurements on a small heat given a different heat treatment. The results showed that heat to heat variations and heat treatment had negligible consequences on Mode I fracture toughness, but behavior during mixed-mode testing showed unexpected instabilities.

  13. Recent status and improvement of reduced-activation ferritic-martensitic steels for high-temperature service

    DOE PAGES

    Tan, L.; Katoh, Y.; Tavassoli, A. -A. F.; ...

    2016-07-26

    Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. Additionally, to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti,more » X = C/N) precipitates and reducing coarse M23C6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. We present and compare limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic with data for F82H and Eurofer97 irradiated up to ~70 displacements per atom at ~300–325 °C.« less

  14. Recent status and improvement of reduced-activation ferritic-martensitic steels for high-temperature service

    NASA Astrophysics Data System (ADS)

    Tan, L.; Katoh, Y.; Tavassoli, A.-A. F.; Henry, J.; Rieth, M.; Sakasegawa, H.; Tanigawa, H.; Huang, Q.

    2016-10-01

    Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. In addition to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti, X = C/N) precipitates and reducing coarse M23C6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. Limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic are presented and compared with data for F82H and Eurofer97 irradiated up to ∼70 displacements per atom at ∼300-325 °C.

  15. Recent status and improvement of reduced-activation ferritic-martensitic steels for high-temperature service

    SciTech Connect

    Tan, L.; Katoh, Y.; Tavassoli, A. -A. F.; Henry, J.; Rieth, M.; Sakasegawa, H.; Tanigawa, H.; Huang, Q.

    2016-07-26

    Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. Additionally, to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti, X = C/N) precipitates and reducing coarse M23C6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. We present and compare limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic with data for F82H and Eurofer97 irradiated up to ~70 displacements per atom at ~300–325 °C.

  16. Effects of alloying elements and heat treatments on mechanical properties of Korean reduced-activation ferritic-martensitic steel

    NASA Astrophysics Data System (ADS)

    Chun, Y. B.; Kang, S. H.; Noh, S.; Kim, T. K.; Lee, D. W.; Cho, S.; Jeong, Y. H.

    2014-12-01

    As part of an alloy development program for Korean reduced-activation ferritic-martensitic (RAFM) steel, a total of 37 program alloys were designed and their mechanical properties were evaluated with special attention being paid to the effects of alloying elements and heat treatments. A reduction of the normalizing temperature from 1050 °C to 980 °C was found to have a positive effect on the impact resistance, resulting in a decrease in ductile-brittle transition-temperature (DBTT) of the program alloys by an average of 30 °C. The yield strength and creep rupture time are affected strongly by the tempering time at 760 °C but at the expense of ductility. Regarding the effects of the alloying elements, the addition of trace amounts of Zr enhances both the creep and impact resistance: the lowest DBTT was observed for the alloys containing 0.005 wt.% Zr, whereas the addition of 0.01 wt.% Zr extends the creep rupture-time under an accelerated condition. The enhanced impact resistance owing to the normalizing at lower temperature is attributed to a more refined grain structure, which provides more barriers to the propagation of cleavage cracks. Solution softening by Zr addition is suggested as a possible mechanism for enhanced resistance to both impact and creep of the program alloys.

  17. Microstructural evolution in a ferritic-martensitic stainless steel and its relation to high-temperature deformation and rupture models

    SciTech Connect

    DiMelfi, R.J.; Gruber, E.E.; Kramer, J.M.

    1991-01-01

    The ferritic-martensitic stainless steel HT-9 exhibits an anomalously high creep strength in comparison to its high-temperature flow strength from tensile tests performed at moderate rates. A constitutive relation describing its high-temperature tensile behavior over a wide range of conditions has been developed. When applied to creep conditions the model predicts deformation rates orders of magnitude higher than observed. To account for the observed creep strength, a fine distribution of precipitates is postulated to evolve over time during creep. The precipitate density is calculated at each temperature and stress to give the observed creep rate. The apparent precipitation kinetics thereby extracted from this analysis is used in a model for the rupture-time kinetics that compares favorably with observation. Properly austenitized and tempered material was aged over times comparable to creep conditions, and in a way consistent with the precipitation kinetics from the model. Microstructural observations support the postulates and results of the model system. 16 refs., 10 figs.

  18. Microstructure and mechanical property of ferritic-martensitic steel cladding under a 650 °C liquid sodium environment

    NASA Astrophysics Data System (ADS)

    Kim, Jun Hwan; Kim, Sung Ho

    2013-11-01

    A study was carried out to investigate the effect of liquid sodium on the microstructural and mechanical property of ferritic-martensitic steel (FMS) used for a Sodium-cooled Fast Reactor (SFR) cladding tube. A quasi-dynamic device characterized by natural circulation was constructed and a compatibility test between FMS and liquid sodium was performed. HT9 (12Cr-1MoWVN) and Gr.92 (9Cr-2WNbVNB) coupons as well as a Gr.92 cladding tube were immersed in the 650 °C liquid sodium up to 3095 h and a microstructural observation, a mechanical property evaluation such as nanoindentation, and a ring tension test were also done in this study. The results showed that both HT9 and Gr.92 exhibited macroscopic weight loss behavior where pitting and decarburization took place. Weight loss as well as the decarburization process decreased as the chromium content increased. A compatibility test over the cladding tube revealed that a decrease of the mechanical property caused by the aging process governed the whole mechanical property of the cladding tube.

  19. Fabrication and integrity test preparation of HIP-joined W and ferritic-martensitic steel mockups for fusion reactor development

    NASA Astrophysics Data System (ADS)

    Lee, Dong Won; Shin, Kyu In; Kim, Suk Kwon; Jin, Hyung Gon; Lee, Eo Hwak; Yoon, Jae Sung; Choi, Bo Guen; Moon, Se Youn; Hong, Bong Guen

    2014-10-01

    Tungsten (W) and ferritic-martensitic steel (FMS) as armor and structural materials, respectively, are the major candidates for plasma-facing components (PFCs) such as the blanket first wall (BFW) and the divertor, in a fusion reactor. In the present study, three W/FMS mockups were successfully fabricated using a hot isostatic pressing (HIP, 900 °C, 100 MPa, 1.5 hrs) with a following post-HIP heat treatment (PHHT, tempering, 750 °C, 70 MPa, 2 hrs), and the W/FMS joining method was developed based on the ITER BFW and the test blanket module (TBM) development project from 2004 to the present. Using a 10-MHz-frequency flat-type probe to ultrasonically test of the joint, we found no defects in the fabricated mockups. For confirmation of the joint integrity, a high heat flux test will be performed up to the thermal lifetime of the mockup under the proper test conditions. These conditions were determined through a preliminary analysis with conventional codes such as ANSYS-CFX for thermal-hydraulic conditions considering the test facility, the Korea heat load test facility with an electron beam (KoHLT-EB), and its water coolant system at the Korea Atomic Energy Research Institute (KAERI).

  20. A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

    NASA Astrophysics Data System (ADS)

    Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han; Maloy, Stuart A.

    2017-02-01

    The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This study aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide a comparative assessment of their high-temperature structural performance. The KJQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared that at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.

  1. A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

    DOE PAGES

    Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han; ...

    2016-12-07

    The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This paper aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide amore » comparative assessment of their high-temperature structural performance. The KJQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared that at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Finally, irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.« less

  2. A comparative assessment of the fracture toughness behavior of ferritic-martensitic steels and nanostructured ferritic alloys

    SciTech Connect

    Byun, Thak Sang; Hoelzer, David T.; Kim, Jeoung Han; Maloy, Stuart A.

    2016-12-07

    The Fe-Cr alloys with ultrafine microstructures are primary candidate materials for advanced nuclear reactor components because of their excellent high temperature strength and high resistance to radiation-induced damage such as embrittlement and swelling. Mainly two types of Fe-Cr alloys have been developed for the high temperature reactor applications: the quenched and tempered ferritic-martensitic (FM) steels hardened primarily by ultrafine laths and carbonitrides and the powder metallurgy-based nanostructured ferritic alloys (NFAs) by nanograin structure and nanoclusters. This paper aims at elucidating the differences and similarities in the temperature and strength dependences of fracture toughness in the Fe-Cr alloys to provide a comparative assessment of their high-temperature structural performance. The KJQ versus yield stress plots confirmed that the fracture toughness was inversely proportional to yield strength. It was found, however, that the toughness data for some NFAs were outside the band of the integrated dataset at given strength level, which indicates either a significant improvement or deterioration in mechanical properties due to fundamental changes in deformation and fracture mechanisms. When compared to the behavior of NFAs, the FM steels have shown much less strength dependence and formed narrow fracture toughness data bands at a significantly lower strength region. It appeared that at high temperatures ≥600 °C the NFAs cannot retain the nanostructure advantage of high strength and high toughness either by high-temperature embrittlement or by excessive loss of strength. Finally, irradiation studies have revealed, however, that the NFAs have much stronger radiation resistance than tempered martensitic steels, such as lower radiation-induced swelling, finer helium bubble formation, lower irradiation creep rate and reduced low temperature embrittlement.

  3. Modification in the Microstructure of Mod. 9Cr-1Mo Ferritic Martensitic Steel Exposed to Sodium

    NASA Astrophysics Data System (ADS)

    Prasanthi, T. N.; Sudha, Cheruvathur; Paul, V. Thomas; Bharasi, N. Sivai; Saroja, S.; Vijayalakshmi, M.

    2014-09-01

    Mod. 9Cr-1Mo is used as the structural material in the steam generator circuit of liquid metal-cooled fast breeder reactors. Microstructural modifications on the surface of this steel are investigated after exposing to flowing sodium at a temperature of 798 K (525 °C) for 16000 hours. Sodium exposure results in the carburization of the ferritic steel up to a depth of ~218 µm from the surface. Electron microprobe analysis revealed the existence of two separate zones with appreciable difference in microchemistry within the carburized layer. Differences in the type, morphology, volume fraction, and microchemistry of the carbides present in the two zones are investigated using analytical transmission electron microscopy. Formation of separate zones within the carburized layer is understood as a combined effect of leaching, diffusion of the alloying elements, and thermal aging. Chromium concentration on the surface in the α-phase suggested possible degradation in the corrosion resistance of the steel. Further, concentration-dependent diffusivities for carbon are determined in the base material and carburized zones using Hall's and den Broeder's methods, respectively. These are given as inputs for simulating the concentration profiles for carbon using numerical computation technique based on finite difference method. Predicted thickness of the carburized zone agrees reasonably well with that of experiment.

  4. Effect of δ-ferrite evolution and high-temperature annealing on mechanical properties of 11Cr3W3Co ferritic/martensitic steel

    NASA Astrophysics Data System (ADS)

    Shang, Zhongxia; Shen, Yinzhong; Ji, Bo; Zhang, Lanting

    2016-03-01

    An 11Cr3W3Co ferritic/martensitic steel was annealed at 1100 °C for different time to gradually dissolve δ-ferrite, and then conducted tensile, hardness, and short-term creep tests in combination with microstructural characterization to study the effect of δ-ferrite on the mechanical properties of high-Cr ferritic/martensitic steels. The amount of δ-ferrite gradually decreased to a minimum value with increasing annealing time up to 10 h, and then tended to an ascending tendency when annealed for 15 and 20 h. Accordingly the tensile strength at 300 and 650 °C, and Vickers hardness of the steel had an increase and a decrease tendency when δ-ferrite amount decreased down to its minimum value and increased again, respectively. The short-term creep property at 210 MPa at 650 °C of the steel exhibited a serious degradation as annealing time gradually increased to 15 h. The morphology and orientation of δ-ferrite grains seriously affected the short-term creep property of the steel. δ-ferrite with a continuously bamboo-like shape parallel to loading direction effectively improved the short-term creep property of the steel at high temperature, while δ-ferrite with a granular or block shape seriously damaged the short-term creep property of the steel. These findings have also been discussed.

  5. New nano-particle-strengthened ferritic/martensitic steels by conventional thermo-mechanical treatment

    NASA Astrophysics Data System (ADS)

    Klueh, R. L.; Hashimoto, N.; Maziasz, P. J.

    2007-08-01

    For increased fusion power plant efficiency, steels for operation at 650 °C and higher are sought. Based on the science of precipitate strengthening, a thermo-mechanical treatment (TMT) was developed that increased the strength from room temperature to 700 °C of commercial nitrogen-containing steels and new steels designed for the TMT. At 700 °C increases in yield stress of 80 and 200% were observed for a commercial steel and a new steel, respectively, compared to commercial normalized-and-tempered steels. Creep-rupture strength was similarly improved. Depending on the TMT, precipitates were up to eight-times smaller at a number density four orders of magnitude greater than those in a conventionally heat treated steel of similar composition.

  6. Toughness of 12%Cr ferritic/martensitic steel welds produced by non-arc welding processes

    SciTech Connect

    Ginn, B.J.; Gooch, T.G.

    1998-08-01

    Low carbon 12%Cr steels can offer reduced life cycle costs in many applications. The present work examined the behavior of commercial steels of varying composition when subject to low heat input welding by the electron beam (EB) process and to a forge cycle by linear friction welding (LFW). Charpy impact testing was carried out on the high temperature heat-affected zone (HAZ)/fusion boundary or weld interface, with metallographic examination. With EB welding, the ductile-brittle transition temperature (DBTT) was below 0 C (32 F) only for steel of low ferrite factor giving a fully martensitic weld area. Higher ferrite factor alloys showed predominantly ferritic transformed microstructures and a transition well above room temperature. Grain coarsening was found even with low EB process power, the peak grain size increasing with both heat input and steel ferrite factor. Use of LFW gave a fine weld area structure and DBTTs around 0 C even in high ferrite factor (FF) material.

  7. Mixed-mode I/III fracture toughness of a ferritic/martensitic stainless steel

    SciTech Connect

    Li, Huaxin; Jones, R.H.; Gelles, D.S.; Hirth, J.P.

    1993-10-01

    The critical J-integrals of mode I (J{sub IC}), mixed-mode I/III (J{sub MC}), and mode III (J{sub IIIC}) were examined for a ferritic stainless steel (F-82H) at ambient temperature. A determination of J{sub MC} was made using modified compact-tension specimens. Different ratios of tension/shear stress were achieved by varying the principal axis of the crack plane between 0 and 55 degrees from the load line. Results showed that J{sub MC} and tearing modulus (T{sub M}) values varied with the crack angles and were lower than their mode I and mode III counterparts. Both the minimum J{sub MC} and T{sub M} values occurred at a crack angle between 40 and 50 degrees, where the load ratio of {sigma}{sub i}/{sigma}{sub iii} was 1.2 to 0.84. The J{sub min} was 240 Kj/M{sup 2}, and ratios of J{sub IC}/J{sub min} and J{sub IIIC}/J{sub min} were 2.1 and 1.9, respectively. The morphology of fracture surfaces was consistent with the change of J{sub MC} and T{sub M} values. While the upper shelf-fracture toughness of F-82H depends on loading mode, the J{sub min} remains very high. Other important considerations include the effect of mixed-mode loading on the DBT temperature, and effects of hydrogen and irradiation on J{sub min}.

  8. Boron effect on the microstructure of 9% Cr ferritic-martensitic steels

    NASA Astrophysics Data System (ADS)

    Klimenkov, M.; Materna-Morris, E.; Möslang, A.

    2015-07-01

    The microstructure of reduces-activation 9Cr-WTaV steel alloyed with 83 and 1160 wt. ppm 10B was detailed analysed using transmission electron microscopy. The influence of boron content on the precipitation behaviour of M23C6 and MX (VN and TaC) phases and, hence, on the formation process of steel's grain and lath structure was studied. VN precipitates, which play an important role in the stabilisation of the lath structure, exhibit most sensitive reaction on presence of boron. Their spatial density significantly reduces in the alloy with 83 ppm boron. In the steel with 1160 wt. ppm boron, no formation of VN was detected, whereas TaC particles precipitate at the lath and grain boundaries. These changes in the structure stabilisation mechanism lead to an increasing lath width and a decreasing thermal stability of laths and grains. Analytical investigations of several BN particles reveal their complex multi-phase structure and allow conclusions to be drawn with respect to their precipitation sequence.

  9. Onset of plasticity of helium-implanted ferritic/martensitic steels during nanoindentation

    NASA Astrophysics Data System (ADS)

    Chen, Siwei; Wang, Yongming; Hashimoto, Naoyuki; Ohnuki, Somei

    2014-07-01

    The onset of plasticity during nanoindentation is a new method to investigate the irradiation damage of structural materials in fission and fusion reactors. In this paper, nanoindentation experiment was carried out to helium implanted F82H-IEA and nano-sized oxide dispersion strengthened F82H-ODS steels for studying the elastic-plastic transition at a constant loading rate. The onset of plasticity shifted after helium implantation. By a statistical thermal activation model, activation volume was extracted to discuss the strength of barrier for dislocation motion. The results reveal an increase in the pinning force and number density of effective obstacles for dislocation motion in He-implanted F82H-IEA, and a decrease in the local pinning force without changing the density of effective obstacles in He-implanted F82H-ODS.

  10. Fracture mechanisms in dual phase steels based on the acicular ferrite + martensite/austenite microstructure

    NASA Astrophysics Data System (ADS)

    Poruks, Peter

    The fracture mechanisms of low carbon microalloyed plate steels based on the acicular ferrite + marten site/austenite microstructure (AF + M/A) are investigated. The final microstructure consists of a dispersed phase of submicron equi-axed martensite particles with a bainitic ferrite matrix. A series of plates with M/A volume fractions of 0.076--0.179 are studied. Brittle fracture is investigated by Instrumented Charpy impact testing of samples at -196°C and subsequent metallography. The M/A particles are identified as the crack nucleation sites and the cleavage fracture stress calculated to be 2400 MPa in a complete AF microstrucuture. This value is significantly larger than in steels that contain significant proportions of conventional bainite. Standard Charpy and Instrumented Charpy impact testing is conducted through a temperature range from -80 to + 22°C to study ductile fracture behaviour. The total absorbed energy is separated into energies of crack nucleation and of crack propagation. It is found that the energy of crack nucleation is weakly dependent on the volume fraction of M/A and completely independent of temperature over the range studied. The crack propagation energy varies significantly with both variables, decreasing with increased volume fraction of M/A and with decreasing temperature. The peak load in the instrumented Charpy data is used to calculate the dynamic fracture toughness, KId, which is found to be 105--120 MPa-m1/2. The void nucleation and void growth stages of ductile fracture are studied by metallographic examination of tensile bars. The sites of void nucleation are identified as inclusions and M/A particles. Voids nucleate at the M/A particles by decohesion of the particle-matrix interface. A constant void nucleation strain of epsilon = 0.90 +/- 0.05 is measured for all of the samples independent of the volume fraction of M/A. A stress-based criterion is used to predict void nucleation and the interface strength is determined to be

  11. High Strain Fatigue Properties of the F82H Ferritic-Martensitic Steel under Proton Irradiation.

    SciTech Connect

    Marmy, P; Oliver, Brian M. )

    2003-05-15

    During the up and down cycles of a fusion reactor, the first wall is exposed concomitantly to a flux of energetic neutrons that generates radiation defects and to a neutron thermal flux that induces thermal stresses. The resulting strains may exceed the elastic limit and induce a plastic deformation in the material. A similar situation occurs in the window of a spallation liquid source target and results in the same type of damage. This particular loading has been simulated in F82H martensitic ferritic steel, using a device allowing a fatigue test to be carried out during irradiation with 590 MeV protons. All fatigue tests were carried out at 300?C, in a strain controlled test at strain levels around 0.8%. Two different signals have been used: a fully symmetrical triangle wave signal (R=-1) and a triangle ramp with 2 min tension holds. The fatigue was investigated under three different conditions: unirradiated , irradiated and post irradiation tested, and finally in beam tested. The main result is that the in beam tested specimens have the lowest life as compared to the post irradiation tested specimens and unirradiated specimens. Hydrogen is suspected to be the main contributor to the observed embrittlement.

  12. Tritium permeation experiments using reduced activation ferritic/martensitic steel tube and erbium oxide coating

    SciTech Connect

    Takumi Chikada; Masashi Shimada; Robert Pawelko; Takayuki Terai; Takeo Muroga

    2013-09-01

    Low concentration tritium permeation experiments have been performed on uncoated F82H and Er2O3-coated tubular samples in the framework of the Japan-US TITAN collaborative program. Tritium permeability of the uncoated sample with 1.2 ppm tritium showed one order of magnitude lower than that with 100% deuterium. The permeability of the sample with 40 ppm tritium was more than twice higher than that of 1.2 ppm, indicating a surface contribution at the lower tritium concentration. The Er2O3-coated sample showed two orders of magnitude lower permeability than the uncoated sample, and lower permeability than that of the coated plate sample with 100% deuterium. It was also indicated that the memory effect of ion chambers in the primary and secondary circuits was caused by absorption of tritiated water vapor that was generated by isotope exchange reactions between tritium and surface water on the coating.

  13. Fabrication of 13Cr-2Mo Ferritic/Martensitic Oxide-Dispersion-Strengthened Steel Components by Mechanical Alloying and Spark-Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Bogachev, I.; Grigoryev, E.; Khasanov, O. L.; Olevsky, E.

    2014-06-01

    The outcomes of the mechanical alloying of 13Cr-2Mo ferritic/martensitic steel and yttria (oxide-dispersion-strengthened steel) powders in a ball mill are reported in terms of the powder particle size and morphology evolution. The optimal ball mill rotation speed and the milling time are discussed. The densification kinetics of the mechanically alloyed powder during the process of spark-plasma sintering is analyzed. An optimal set of the compaction processing parameters, including the maximum temperature, the dwell time, and the heating rate, is determined. The specifics of the densification are discussed in terms of the impact of major spark-plasma sintering parameters as well as the possible phase transformations occurring during compaction processing.

  14. SANS and TEM of ferritic-martensitic steel T91 irradiated in FFTF up to 184 dpa at 413 °C

    NASA Astrophysics Data System (ADS)

    Van den Bosch, J.; Anderoglu, O.; Dickerson, R.; Hartl, M.; Dickerson, P.; Aguiar, J. A.; Hosemann, P.; Toloczko, M. B.; Maloy, S. A.

    2013-09-01

    Ferritic-martensitic steel T91 was previously irradiated in the Materials Open Test Assembly (MOTA) program of the Fast Flux Test Reactor Facility (FFTF) at 413 °C up to 184 dpa. The microstructure was analyzed by small angle neutron scattering (SANS) and transmission electron microscopy (TEM). Both SANS and TEM revealed a large fraction of voids with an average size of 29-32 nm leading to a calculated void swelling of 1.2-1.6% based on the volume fraction of the voids in the sample. SANS gave no indication of second phase particles having formed under irradiation in the material. Using TEM, one zone was found where a few G-phase particles were analyzed. Quantities were however too low to state reliable particle densities. No alpha prime (α') or Laves phase were observed in any of the investigated zones.

  15. Effect of microstructural evolution by isothermal aging on the mechanical properties of 9Cr-1WVTa reduced activation ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Park, Min-Gu; Lee, Chang-Hoon; Moon, Joonoh; Park, Jun Young; Lee, Tae-Ho; Kang, Namhyun; Chan Kim, Hyoung

    2017-03-01

    The influence of microstructural changes caused by aging condition on tensile and Charpy impact properties was investigated for reduced activation ferritic-martensitic (RAFM) 9Cr-1WVTa steels having single martensite and a mixed microstructure of martensite and ferrite. For the mixed microstructure of martensite and ferrite, the Charpy impact properties deteriorated in both as-normalized and tempered conditions due to the ferrite and the accompanying M23C6 carbides at the ferrite grain boundaries which act as path and initiation sites for cleavage cracks, respectively. However, aging at 550 °C for 20-100 h recovered gradually the Charpy impact toughness without any distinct drop in strength, as a result of the spheroidization of the coarse M23C6 carbides at the ferrite grain boundaries, which makes crack initiation more difficult.

  16. Silicon-containing ferritic/martensitic steel after exposure to oxygen-containing flowing lead-bismuth eutectic at 450 and 550 °C

    NASA Astrophysics Data System (ADS)

    Schroer, Carsten; Koch, Verena; Wedemeyer, Olaf; Skrypnik, Aleksandr; Konys, Jürgen

    2016-02-01

    A ferritic/martensitic (f/m) steel with 9 and 3 mass% of chromium (Cr) and silicon (Si), respectively, was tested on performance in flowing lead-bismuth eutectic (LBE) at 450 and 550 °C, each at concentrations of solved oxygen of both 10-7 and 10-6 mass%. The 9Cr-3Si steel generally exhibits the same basic corrosion modes as other f/m materials with 9 mass% Cr and typically lower Si content, namely Steel T91. The Si-rich steel shows an overall improved performance in comparison to T91 at 450 °C and 10-7 mass% solved oxygen, but especially at 450 °C and 10-6 mass% solved oxygen. The advantage of higher Si-content in 9Cr steel is less clear at 550 °C. Especially high oxygen content in flowing LBE at 550 °C, between >10-6 mass% and oxygen saturation, seems detrimental for the high-Si material in respect of the initiation and progress of a solution-based corrosion.

  17. Effect of Tungsten on Long-Term Microstructural Evolution and Impression Creep Behavior of 9Cr Reduced Activation Ferritic/Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Thomas Paul, V.; Vijayanand, V. D.; Sudha, C.; Saroja, S.

    2017-01-01

    The present study describes the changes in the creep properties associated with microstructural evolution during thermal exposures to near service temperatures in indigenously developed reduced activation ferritic-martensitic steels with varying tungsten (1 and 1.4 wt pct W) contents. The creep behavior has been studied employing impression creep (IC) test, and the changes in impression creep behavior with tungsten content have been correlated with the observed microstructures. The results of IC test showed that an increase in 0.4 pct W decreases the creep rate to nearly half the value. Creep strength of 1.4 pct W steel showed an increase in steels aged for short durations which decreased as aging time increased. The microstructural changes include coarsening of precipitates, reduction in dislocation density, changes in microchemistry, and formation of new phases. The formation of various phases and their volume fractions have been predicted using the JMatPro software for the two steels and validated by experimental methods. Detailed transmission electron microscopy analysis shows coarsening of precipitates and formation of a discontinuous network of Laves phase in 1.4 W steel aged for 10,000 hours at 823 K (550 °C) which is in agreement with the JMatPro simulation results.

  18. Dependence of mode I and mixed mode I/III fracture toughness on temperature for a ferritic/martensitic stainless steel

    SciTech Connect

    Li, H.; Jones, R.H.; Gelles, D.S.

    1995-04-01

    The objective is to investigate the dependence of mode I and mixed mode I/III fracture toughness on temperature in the range of {minus}95{degrees}C to 25{degrees}C for a low activation ferritic/martensitic stainless steel (F82-H). Mode I and mixed Mode I/III fracture toughnesses were investigated in the range of {minus}95 to 25{degree}C for a F82-H steel heat-treated in the following way; 1000{degree}C/20 h/air-cooled (AC), 1100{degree}C/7 min/AC, and 700{degree}C/2 h/AC. The results indicate that crack tip plasticity was increased by mixed mode loading, and suggest that at low temperature, mode I fracture toughness is the critical design parameter, but at temperatures above room temperature, expecially concerning fatigure and creep-fatigue crack growth rate, a mixed mode loading may be more harmful than a mode I loading for this steel because a mixed mode loading results in lower fracture toughness and higher crack tip plasticity (or dislocation activity).

  19. Triple Ion-Beam Studies of Radiation Damage in 9Cr2WVTa Ferritic/Martensitic Steel for a High Power Spallation Neutron Source

    SciTech Connect

    Lee, EH

    2001-08-01

    To simulate radiation damage under a future Spallation Neutron Source (SNS) environment, irradiation experiments were conducted on a candidate 9Cr-2WVTa ferritic/martensitic steel using the Triple Ion Facility (TIF) at ORNL. Irradiation was conducted in single, dual, and triple ion beam modes using 3.5 MeV Fe{sup 2}, 360 keV He{sup +}, and 180 keV H{sup +} at 80, 200, and 350 C. These irradiations produced various defects comprising black dots, dislocation loops, line dislocations, and gas bubbles, which led to hardening. The largest increase in hardness, over 63%, was observed after 50 dpa for triple beam irradiation conditions, revealing that both He and H are augmenting the hardening. Hardness increased less than 30% after 30 dpa at 200 C by triple beams, compatible with neutron irradiation data from previous work which showed about a 30% increase in yield strength after 27.2 dpa at 365 C. However, the very large concentrations of gas bubbles in the matrix and on lath and grain boundaries after these simulated SNS irradiations make predictions of fracture behavior from fission reactor irradiations to spallation target conditions inadvisable.

  20. Energy-filtered TEM imaging and EELS study of ODS particles and argon-filled cavities in ferritic-martensitic steels.

    PubMed

    Klimiankou, M; Lindau, R; Möslang, A

    2005-01-01

    Oxide-dispersion-strengthened (ODS) ferritic-martensitic steels with yttrium oxide (Y(2)O(3)) have been produced by mechanical alloying and hot isostatic pressing for use as advanced material in fusion power reactors. Argon gas, usually widely used as inert gas during mechanical alloying, was surprisingly detected in the nanodispersion-strengthened materials. Energy-filtered transmission electron microscopy (EFTEM) and electron energy loss spectroscopy (EELS) led to the following results: (i) chemical composition of ODS particles, (ii) voids with typical diameters of 1-6 nm are formed in the matrix, (iii) these voids are filled with Ar gas, and (iv) the high-density nanosized ODS particles serve as trapping centers for the Ar bubbles. The Ar L(3,2) energy loss edge at 245 eV as well as the absorption features of the ODS particle elements were identified in the EELS spectrum. The energy resolution in the EEL spectrum of about 1.0 eV allows to identify the electronic structure of the ODS particles.

  1. High heat flux test with HIP-bonded Ferritic Martensitic Steel mock-up for the first wall of the KO HCML TBM

    NASA Astrophysics Data System (ADS)

    Won Lee, Dong; Dug Bae, Young; Kwon Kim, Suk; Yun Shin, Hee; Guen Hong, Bong; Cheol Bang, In

    2011-10-01

    In order for a Korean Helium Cooled Molten Lithium (HCML) Test Blanket Module (TBM) to be tested in the International Thermonuclear Experimental Reactor (ITER), fabrication method for the TBM FW such as Hot Isostatic Pressing (HIP, 1050 °C, 100 MPa, 2 h) has been developed including post HIP heat treatment (PHHT, normalizing at 950 °C for 2 h and tempering at 750 °C for 2 h) with Ferritic Martensitic Steel (FMS). Several mock-ups were fabricated using the developed methods and one of them, three-channel mock-up, was used for performing a High Heat Flux (HHF) test to verify the joint integrity. Test conditions were determined using the commercial code, ANSYS-11, and the test was performed in the Korea Heat Load Test (KoHLT) facility, which was used a radiation heating with a graphite heater. The mock-up survived up to 1000 cycles under 1.0 MW/m 2 heat flux and there is no delamination or failure during the test.

  2. Irradiation-induced impurity segregation and ductile-to-brittle transition temperature shift in high chromium ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Faulkner, R. G.; Flewitt, P. E. J.

    2007-08-01

    A model is presented to predict irradiation-induced impurity segregation and its contribution to the ductile-to-brittle transition temperature (DBTT) shift in high chromium ferritic steels. The hardening contribution (dislocation loops, voids and precipitates) is also considered in this study. The predicted results are compared with the experimental DBTT shifts data for irradiated 9Cr1MoVNb and 12Cr1MoVW steels with different grain sizes.

  3. Effect of loading mode on the fracture toughness of a reduced activation ferritic/martensitic stainless steel

    SciTech Connect

    Li, H.; Hirth, J.P.; Jones, R.H.; Gelles, D.S.

    1993-09-01

    The critical J integrals of mode I (J{sub IC}), mixed-mode I/III (J{sub MC}), and mode III (J{sub IIIC}) were examined for a ferritic stainless steel (F-82H) at ambient temperature. A determination of J{sub MC} was made using modified compact-tension specimens. Different ratios of tension/shear stress were achieved by varying the principal axis of the crack plane between 0 and 55 degrees from the load line. The results showed that J{sub MC}s and tearing moduli (T{sub M}) varied with the crack angles and were lower than their mode I and mode III counterparts. Both the minimum J{sub MC} and T{sub M} occurred at a crack angle between 40 and 50 degrees, where {sigma}{sub i}/{sigma}{sub iii} was 1.2 to 0.84. The J{sub min} was 240 kJ/m{sup 2}, and ratios of J{sub IC}/J{sub min} and J{sub IIIC}/J{sub min} were about 2.1 and 1.9, respectively. Morphology of fracture surfaces was consistent with the change of J{sub MC} and T{sub M} values. While the upper shelf-fracture toughness of F-82H depends on loading mode, the J{sub min} remains very high. Other important considerations include the effect of mixed-mode loading on the DBT temperature, and effects of hydrogen and irradiation on J{sub min}.

  4. Effects of boron and phosphorus on creep properties of a ferritic/martensitic steel for fast reactor cladding applications

    SciTech Connect

    Not Available

    1994-10-01

    The thermal efficiencies of both conventional and supercritical fossil-fueled power plants can be improved by increasing the operating temperatures and pressures. Increased thermal efficiency would also result in significant fuel cost savings, as well as reduced environmental emissions per megawatt generated. Creep properties of materials currently used as tubes in the hottest areas of the boiler, the superheater and reheater sections, limit the operating temperature. As such, steels with improved creep strength compared to these conventional alloys are needed to increase the operational efficiencies of thermal-electric generating stations. A new class of creep-resistant, 10%Cr martensitic steel has been developed for use as high temperature components, especially in the electric utility, petrochemical & chemical industries. The steel differs from other 9-12%Cr steels in two important ways: It is strengthened by a uniform dispersion of very fine, coarsening-resistant TiC particles rather than chromium-rich, M{sub 23}C{sub 6} precipitates; and the TiC particles are precipitated in austenite prior to the martensitic transformation, not during tempering. By carefully controlling the thermo-mechanical treatment, three TiC sizes were incorporated into the matrix: 4, 12 and 25 nm; grain size and precipitate volume fraction (0.005) were kept constant. Creep tests on these three specimen types were done at 550{degrees}C, 600{degrees}C and 650{degrees}C. Results indicate that reducing the average particle size from 25 to 4 nm (thereby also reducing the average inter-particle spacing) decreases the steady-state creep rate by more than four orders of magnitude. The prototype steel`s composition must now be optimized, and in doing so the effects of boron and phosphorus are investigated.

  5. Investigation of a Novel NDE Method for Monitoring Thermomechanical Damage and Microstructure Evolution in Ferritic-Martensitic Steels for Generation IV Nuclear Energy Systems

    SciTech Connect

    Nagy, Peter

    2013-09-30

    The main goal of the proposed project is the development of validated nondestructive evaluation (NDE) techniques for in situ monitoring of ferritic-martensitic steels like Grade 91 9Cr-1Mo, which are candidate materials for Generation IV nuclear energy structural components operating at temperatures up to ~650{degree}C and for steam-generator tubing for sodium-cooled fast reactors. Full assessment of thermomechanical damage requires a clear separation between thermally activated microstructural evolution and creep damage caused by simultaneous mechanical stress. Creep damage can be classified as "negligible" creep without significant plastic strain and "ordinary" creep of the primary, secondary, and tertiary kind that is accompanied by significant plastic deformation and/or cavity nucleation and growth. Under negligible creep conditions of interest in this project, minimal or no plastic strain occurs, and the accumulation of creep damage does not significantly reduce the fatigue life of a structural component so that low-temperature design rules, such as the ASME Section III, Subsection NB, can be applied with confidence. The proposed research project will utilize a multifaceted approach in which the feasibility of electrical conductivity and thermo-electric monitoring methods is researched and coupled with detailed post-thermal/creep exposure characterization of microstructural changes and damage processes using state-of-the-art electron microscopy techniques, with the aim of establishing the most effective nondestructive materials evaluation technique for particular degradation modes in high-temperature alloys that are candidates for use in the Next Generation Nuclear Plant (NGNP) as well as providing the necessary mechanism-based underpinnings for relating the two. Only techniques suitable for practical application in situ will be considered. As the project evolves and results accumulate, we will also study the use of this technique for monitoring other GEN IV

  6. Analysis of stress-induced Burgers vector anisotropy in pressurized tube specimens of irradiated ferritic-martensitic steel: JLF-1

    SciTech Connect

    Gelles, D.S.; Shibayama, T.

    1998-09-01

    A procedure for determining the Burgers vector anisotropy in irradiated ferritic steels allowing identification of all a<100> and all a/2<111> dislocations in a region of interest is applied to a pressurized tube specimen of JLF-1 irradiated at 430 C to 14.3 {times} 10{sup 22} n/cm{sup 2} (E > 0.1 MeV) or 61 dpa. Analysis of micrographs indicates large anisotropy in Burgers vector populations develop during irradiation creep.

  7. Microstructural Variations Across a Dissimilar 316L Austenitic: 9Cr Reduced Activation Ferritic Martensitic Steel Weld Joint

    NASA Astrophysics Data System (ADS)

    Thomas Paul, V.; Karthikeyan, T.; Dasgupta, Arup; Sudha, C.; Hajra, R. N.; Albert, S. K.; Saroja, S.; Jayakumar, T.

    2016-03-01

    This paper discuss the microstructural variations across a dissimilar weld joint between SS316 and 9Cr-RAFM steel and its modifications on post weld heat treatments (PWHT). Detailed characterization showed a mixed microstructure of austenite and martensite in the weld which is in agreement with the phases predicted using Schaeffler diagram based on composition measurements. The presence of very low volume fraction of δ-ferrite in SS316L has been identified employing state of the art electron back-scattered diffraction technique. PWHT of the ferritic steel did not reduce the hardness in the weld metal. Thermal exposure at 973 K (700 °C) showed a progressive reduction in hardness of weld joint with duration of treatment except in austenitic base metal. However, diffusion annealing at 1073 K (800 °C) for 100 hours resulted in an unexpected increase in hardness of weld metal, which is a manifestation of the dilution effects and enrichment of Ni on the transformation characteristics of the weld zone. Migration of carbon from ferritic steel aided the precipitation of fine carbides in the austenitic base metal on annealing at 973 K (700 °C); but enhanced diffusion at 1073 K (880 °C) resulted in coarsening of carbides and thereby reduction of hardness.

  8. Fatigue crack propagation in dual-phase steels: Effects of ferritic-martensitic microstructures on crack path morphology

    NASA Astrophysics Data System (ADS)

    Dutta, V. B.; Suresh, S.; Ritchie, R. O.

    1984-06-01

    microstructures with maximum resistance to fatigue crack extension while maintaining high strength levels. A wide range of crack growth rates has been examined, from ~10-8 to 10-3 mm per cycle, in a series of duplex microstructures of comparable yield strength and prior austenite grain size where intercritical heat treatments were used to vary the proportion, morphology, and distribution of the ferrite and martensite phases. Results of fatigue crack propagation tests, conducted on “long cracks” in room temperature moist air environments, revealed a very large influence of microstructure over the entire spectrum of growth rates at low load ratios. Similar trends were observed at high load ratio, although the extent of the microstructural effects on crack growth behavior was significantly less marked. Specifically, microstructures containing fine globular or coarse martensite in a coarse-grained ferritic matrix demonstrated exceptionally high resistance to crack growth without loss in strength properties. To our knowledge, these microstructures yielded the highest ambient temperature fatigue threshold stress intensity range ΔK0 values reported to date, and certainly the highest combination of strength and ΔK0 for steels ( i.e., ΔK0 values above 19 MPa√m with yield strengths in excess of 600 MPa). Such unusually high crack growth resistance is attributed primarily to a tortuous morphology of crack path which results in a reduction in the crack driving force from crack deflection and roughness-induced crack closure mechanisms. Quantitative metallography and experimental crack closure measurements, applied to currently available analytical models for the deflection and closure processes, are presented to substantiate such interpretations.

  9. Study of MHD Corrosion and Transport of Corrosion Products of Ferritic/Martensitic Steels in the Flowing PbLi and its Application to Fusion Blanket

    NASA Astrophysics Data System (ADS)

    Saeidi, Sheida

    Two important components of a liquid breeder blanket of a fusion power reactor are the liquid breeder/coolant and the steel structure that the liquid is enclosed in. One candidate combination for such components is Lead-Lithium (PbLi) eutectic alloy and advanced Reduced Activation Ferritic/Martensitic (RAFM) steel. The research performed here is aimed at: (1) better understanding of corrosion processes in the system including RAFM steel and flowing PbLi in the presence of a strong magnetic field and (2) prediction of corrosion losses in conditions of a Dual Coolant Lead Lithium (DCLL) blanket, which is at present the key liquid metal blanket concept in the US. To do this, numerical and analytical tools have been developed and then applied to the analysis of corrosion processes. First, efforts were taken to develop a computational suite called TRANSMAG (Transport phenomena in Magnetohydrodynamic Flows) as an analysis tool for corrosion processes in the PbLi/RAFM system, including transport of corrosion products in MHD laminar and turbulent flows. The computational approach in TRANSMAG is based on simultaneous solution of flow, energy and mass transfer equations with or without a magnetic field, assuming mass transfer controlled corrosion and uniform dissolution of iron in the flowing PbLi. Then, the new computational tool was used to solve an inverse mass transfer problem where the saturation concentration of iron in PbLi was reconstructed from the experimental data resulting in the following correlation: CS = e 13.604--12975/T, where T is the temperature of PbLi in K and CS is in wppm. The new correlation for saturation concentration was then used in the analysis of corrosion processes in laminar flows in a rectangular duct in the presence of a strong transverse magnetic field. As shown in this study, the mass loss increases with the magnetic field such that the corrosion rate in the presence of a magnetic field can be a few times higher compared to purely

  10. The evolution of internal stress and dislocation during tensile deformation in a 9Cr ferritic/martensitic (F/M) ODS steel investigated by high-energy X-rays

    SciTech Connect

    Zhang, Guangming; Zhou, Zhangjian; Mo, Kun; Miao, Yinbin; Liu, Xiang; Almer, Jonathan; Stubbins, James F.

    2015-12-01

    An application of high-energy wide angle synchrotron X-ray diffraction to investigate the tensile deformation of 9Cr ferritic/martensitic (F/M) ODS steel is presented. With tensile loading and in-situ Xray exposure, the lattice strain development of matrix was determined. The lattice strain was found to decrease with increasing temperature, and the difference in Young's modulus of six different reflections at different temperatures reveals the temperature dependence of elastic anisotropy. The mean internal stress was calculated and compared with the applied stress, showing that the strengthening factor increased with increasing temperature, indicating that the oxide nanoparticles have a good strengthening impact at high temperature. The dislocation density and character were also measured during tensile deformation. The dislocation density decreased with increasing of temperature due to the greater mobility of dislocation at high temperature. The dislocation character was determined by best-fit methods for different dislocation average contrasts with various levels of uncertainty. The results shows edge type dislocations dominate the plastic strain at room temperature (RT) and 300 C, while the screw type dislocations dominate at 600 C. The dominance of edge character in 9Cr F/M ODS steels at RT and 300 C is likely due to the pinning effect of nanoparticles for higher mobile edge dislocations when compared with screw dislocations, while the stronger screw type of dislocation structure at 600 C may be explained by the activated cross slip of screw segments.

  11. Postirradiation thermocyclic loading of ferritic-martensitic structural materials

    NASA Astrophysics Data System (ADS)

    Belyaeva, L.; Orychtchenko, A.; Petersen, C.; Rybin, V.

    Thermonuclear fusion reactors of the Tokamak-type will be unique power engineering plants to operate in thermocyclic mode only. Ferritic-martensitic stainless steels are prime candidate structural materials for test blankets of the ITER fusion reactor. Beyond the radiation damage, thermomechanical cyclic loading is considered as the most detrimental lifetime limiting phenomenon for the above structure. With a Russian and a German facility for thermal fatigue testing of neutron irradiated materials a cooperation has been undertaken. Ampule devices to irradiate specimens for postirradiation thermal fatigue tests have been developed by the Russian partner. The irradiation of these ampule devices loaded with specimens of ferritic-martensitic steels, like the European MANET-II, the Russian 05K12N2M and the Japanese Low Activation Material F82H-mod, in a WWR-M-type reactor just started. A description of the irradiation facility, the qualification of the ampule device and the modification of the German thermal fatigue facility will be presented.

  12. Surface modification of structural materials by low-energy high-current pulsed electron beam treatment

    SciTech Connect

    Panin, A. V. E-mail: kms@ms.tsc.ru; Kazachenok, M. S. E-mail: kms@ms.tsc.ru; Sinyakova, E. A.; Borodovitsina, O. M.; Ivanov, Yu. F.; Leontieva-Smirnova, M. V.

    2014-11-14

    Microstructure formation in surface layers of pure titanium and ferritic-martensitic steel subjected to electron beam treatment is studied. It is shown that low energy high-current pulsed electron beam irradiation leads to the martensite structure within the surface layer of pure titanium. Contrary, the columnar ferrite grains grow during solidification of ferritic-martensitic steel. The effect of electron beam energy density on the surface morphology and microstructure of the irradiated metals is demonstrated.

  13. Use of double and triple-ion irradiation to study the influence of high levels of helium and hydrogen on void swelling of 8-12% Cr ferritic-martensitic steels

    NASA Astrophysics Data System (ADS)

    Kupriiyanova, Y. E.; Bryk, V. V.; Borodin, O. V.; Kalchenko, A. S.; Voyevodin, V. N.; Tolstolutskaya, G. D.; Garner, F. A.

    2016-01-01

    In accelerator-driven spallation (ADS) devices, some of the structural materials will be exposed to intense fluxes of very high energy protons and neutrons, producing not only displacement damage, but very high levels of helium and hydrogen. Unlike fission flux-spectra where most helium and hydrogen are generated by transmutation in nickel and only secondarily in iron or chromium, gas production in ADS flux-spectra are rather insensitive to alloy composition, such that Fe-Cr base ferritic alloys also generate very large gas levels. While ferritic alloys are known to swell less than austenitic alloys in fission spectra, there is a concern that high gas levels in fusion and especially ADS facilities may strongly accelerate void swelling in ferritic alloys. In this study of void swelling in response to helium and hydrogen generation, irradiation was conducted on three ferritic-martensitic steels using the Electrostatic Accelerator with External Injector (ESUVI) facility that can easily produce any combination of helium to dpa and/or hydrogen to dpa ratios. Irradiation was conducted under single, dual and triple beam modes using 1.8 MeV Cr+3, 40 keV He+, and 20 keV H+. In the first part of this study we investigated the response of dual-phase EP-450 to variations in He/dpa and H/dpa ratio, focusing first on dual ion studies and then triple ion studies, showing that there is a diminishing influence on swelling with increasing total gas content. In the second part we investigated the relative response of three alloys spanning a range of starting microstructure and composition. In addition to observing various synergisms between He and H, the most important conclusion was that the tempered martensite phase, known to lag behind the ferrite phase in swelling in the absence of gases, loses much of its resistance to void nucleation when irradiated at large gas/dpa levels.

  14. Comparative Tensile Flow and Work-Hardening Behavior of 9 Pct Chromium Ferritic-Martensitic Steels in the Framework of the Estrin-Mecking Internal-Variable Approach

    NASA Astrophysics Data System (ADS)

    Choudhary, B. K.; Christopher, J.

    2016-06-01

    The comparative tensile flow and work-hardening behavior of P9 steel in two different product forms, normalized and tempered plate and thick section tube plate forging, and P91 steel were investigated in the framework of the dislocation dynamics based Estrin-Mecking (E-M) one-internal-variable approach. The analysis indicated that the flow behavior of P9 and P91 steels was adequately described by the E-M approach in a wide range of temperatures. It was suggested that dislocation dense martensite lath/cell boundaries and precipitates together act as effective barriers to dislocation motion in P9 and P91 steels. At room and intermediate temperatures, the evolution of the internal-state variable, i.e., the dislocation density with plastic strain, exhibited insignificant variations with respect to temperature. At high temperatures, a rapid evolution of dislocation density with plastic strain toward saturation with increasing temperature was observed. The softer P9 steel tube plate forging exhibited higher work hardening in terms of larger gains in the dislocation density and flow stress contribution from dislocations than the P9 steel plate and P91 steel at temperatures ranging from 300 K to 873 K (27 °C to 600 °C). The evaluation of activation energy suggests that the deformation is controlled by cross-slip of dislocations at room and intermediate temperatures, and climb of dislocations at high temperatures. The relative influence of initial microstructure on flow and work-hardening parameters associated with the E-M approach was discussed in the three temperature regimes displayed by P9 and P91 steels.

  15. The effect of low dose irradiation on the impact fracture energy and tensile properties of pure iron and two ferritic martensitic steels

    NASA Astrophysics Data System (ADS)

    Belianov, I.; Marmy, P.

    1998-10-01

    Two batches of subsize V-notched impact bend specimens and subsize tensile specimens have been irradiated in the Saphir test reactor of the Paul Scherrer Institute (PSI). The first batch of specimen has been irradiated at 250°C to a dose of 2.65 × 10 19 n/cm 2 (0.042 dpa) and the second batch has been irradiated at 400°C to a dose of 8.12 × 10 19 n/cm 2 (0.13 dpa). Three different materials in three different microstructures were irradiated: pure iron and two ferritic steels, the alloy MANET 2 and a low activation composition CETA. The results of the impact tests and of the corresponding tensile tests are presented. Despite the very low neutron dose, a significant shift of the ductile to brittle transition temperature (DBTT) is observed. The influence of the test temperature on the impact energy is discussed for the irradiated and unirradiated conditions, with special emphasis on the microstructure.

  16. Creep behavior of pack cementation aluminide coatings on Grade 91 ferritic martensitic alloy

    SciTech Connect

    Bates, Brian; Zhang, Ying; Dryepondt, Sebastien N; Pint, Bruce A

    2014-01-01

    The creep behavior of various pack cementation aluminide coatings on Grade 91 ferritic-martensitic steel was investigated at 650 C in laboratory air. The coatings were fabricated in two temperature regimes, i.e., 650 or 700 C (low temperature) and 1050 C(high temperature), and consisted of a range of Al levels and thicknesses. For comparison, uncoated specimens heat-treated at 1050 C to simulate the high temperature coating cycle also were included in the creep test. All coated specimens showed a reduction in creep resistance, with 16 51% decrease in rupture life compared to the as-received bare substrate alloy. However, the specimens heat-treated at 1050 C exhibited the lowest creep resistance among all tested samples, with a surprisingly short rupture time of < 25 h, much shorter than the specimen coated at 1050 C. Factors responsible for the reduction in creep resistance of both coated and heat-treated specimens were discussed.

  17. Influence of displacement damage on deuterium and helium retention in austenitic and ferritic-martensitic alloys considered for ADS service

    NASA Astrophysics Data System (ADS)

    Voyevodin, V. N.; Karpov, S. A.; Kopanets, I. E.; Ruzhytskyi, V. V.; Tolstolutskaya, G. D.; Garner, F. A.

    2016-01-01

    The behavior of ion-implanted hydrogen (deuterium) and helium in austenitic 18Cr10NiTi stainless steel, EI-852 ferritic steel and ferritic/martensitic steel EP-450 and their interaction with displacement damage were investigated. Energetic argon irradiation was used to produce displacement damage and bubble formation to simulate nuclear power environments. The influence of damage morphology and the features of radiation-induced defects on deuterium and helium trapping in structural alloys was studied using ion implantation, the nuclear reaction D(3He,p)4He, thermal desorption spectrometry and transmission electron microscopy. It was found in the case of helium irradiation that various kinds of helium-radiation defect complexes are formed in the implanted layer that lead to a more complicated spectra of thermal desorption. Additional small changes in the helium spectra after irradiation with argon ions to a dose of ≤25 dpa show that the binding energy of helium with these traps is weakly dependent on the displacement damage. It was established that retention of deuterium in ferritic and ferritic-martensitic alloys is three times less than in austenitic steel at damage of ˜1 dpa. The retention of deuterium in steels is strongly enhanced by presence of radiation damages created by argon ion irradiation, with a shift in the hydrogen release temperature interval of 200 K to higher temperature. At elevated temperatures of irradiation the efficiency of deuterium trapping is reduced by two orders of magnitude.

  18. Surface modification of ferritic steels using MEVVA and duoplasmatron ion sources

    SciTech Connect

    Kulevoy, Timur V. Orlov, Nikolay N.; Rogozhkin, Sergey V.; Bogachev, Alexey A.; Nikitin, Alexander A.; Iskandarov, Nasib A.; Golubev, Alexander A.; Chalyhk, Boris B.; Fedin, Petr A.; Sitnikov, Alexey L.; Kozlov, Alexander V.; Kuibeda, Rostislav P.; Andrianov, Stanislav L.; Kravchuk, Konstantin S.; Useinov, Alexey S.; Oks, Efim M.

    2016-02-15

    Metal Vapor Vacuum Arc (MEVVA) ion source (IS) is a unique tool for production of high intensity metal ion beam that can be used for material surface modification. From the other hand, the duoplasmatron ion source provides the high intensity gas ion beams. The MEVVA and duoplasmatron IS developed in Institute for Theoretical and Experimental Physics were used for the reactor steel surface modification experiments. Response of ferritic-martensitic steel specimens on titanium and nitrogen ions implantation and consequent vacuum annealing was investigated. Increase in microhardness of near surface region of irradiated specimens was observed. Local chemical analysis shows atom mixing and redistribution in the implanted layer followed with formation of ultrafine precipitates after annealing.

  19. Mechanism of the Formation of a Protective Fluoride Coating on Steel Surfaces Contacting Freons as Candidates for Brest-Type Reactors

    NASA Astrophysics Data System (ADS)

    Zagrebaev, S. A.; Orlova, E. A.; Alekseev, V. V.; Zhmurin, V. G.; Orlov, M. A.; Shirshov, Ya. N.; Torbenkova, I. Yu.; Tychinskii, P. I.

    2015-01-01

    The mechanism of the formation of MgF2 coatings on ferritic-martensitic and austenitic steels contacting liquid magnesium and gaseous silicon tetrafluoride (SiF4) has been investigated. An MgF2 coating on steel possesses high plastic properties. The proposed method can be used to improve corrosion resistance of steels contacting freons and other fluorine-containing materials.

  20. Investigation of Magnetic Signatures and Microstructures for Heat-Treated Ferritic/Martensitic HT-9 Alloy

    SciTech Connect

    Henager, Charles H.; McCloy, John S.; Ramuhalli, Pradeep; Edwards, Danny J.; Hu, Shenyang Y.; Li, Yulan

    2013-05-01

    There is increased interest in improved methods for in-situ nondestructive interrogation of materials for nuclear reactors in order to ensure reactor safety and quantify material degradation (particularly embrittlement) prior to failure. Therefore, a prototypical ferritic/martensitic alloy, HT-9, of interest to the nuclear materials community was investigated to assess microstructure effects on micromagnetics measurements – Barkhausen noise emission, magnetic hysteresis measurements, and first-order reversal curve analysis – for samples with three different heat-treatments. Microstructural and physical measurements consisted of high-precision density, resonant ultrasound elastic constant determination, Vickers microhardness, grain size, and texture. These were varied in the HT-9 alloy samples and related to various magnetic signatures. In parallel, a meso-scale microstructure model was created for alpha iron and effects of polycrystallinity and demagnetization factor were explored. It was observed that Barkhausen noise emission decreased with increasing hardness and decreasing grain size (lath spacing) while coercivity increased. The results are discussed in terms of the use of magnetic signatures for nondestructive interrogation of radiation damage and other microstructural changes in ferritic/martensitic alloys.

  1. Surface modification and deuterium retention in reduced-activation steels under low-energy deuterium plasma exposure. Part I: undamaged steels

    NASA Astrophysics Data System (ADS)

    Ogorodnikova, O. V.; Zhou, Z.; Sugiyama, K.; Balden, M.; Gasparyan, Yu.; Efimov, V.

    2017-03-01

    In this paper, reduced-activation ferritic/martensitic (RAFM) steels including Eurofer (9Cr) and oxide dispersion strengthening (ODS) steels by the addition of Y2O3 particles with different amounts of Cr, namely, (9-16)Cr were exposed to low energy deuterium (D) plasma (~20-200 eV per D) up to a fluence of 2.9  ×  1025 D m-2 in the temperature range from 290 K to 700 K. The depth profile of D in steels was measured up to 8 µm depth by nuclear reaction analysis (NRA) and the total retained amount of D in those materials was determined by thermal desorption spectroscopy (TDS). It was found that the D retention in ODS steels is higher compared to Eurofer due to the much higher density of fine dispersoids and finer grain size. This work shows that in addition to the sintering temperature and time, the type, size and concentration of the doping particles have an enormous effect on the increase in the D retention. The D retention in undamaged ODS steels strongly depends on the Cr content: ODS with 12Cr has a minimum and the D retention in the case of ODS with (14-16)Cr is higher compared to (9-12)Cr. The replacing of Ti by Al in ODS-14Cr steels reduces the D retention. The formation of nano-structure surface roughness enriched in W or Ta due to combination of preferential sputtering of light elements and radiation-induced segregation was observed at incident D ion energy of 200 eV for both Eurofer and ODS steels. Both the surface roughness and the eroded layer enhance with increasing the temperature. The surface modifications result in a reduction of the D retention near the surface due to increasing the desorption flux and can reduce the overall D retention.

  2. ODS Ferritic/martensitic alloys for Sodium Fast Reactor fuel pin cladding

    NASA Astrophysics Data System (ADS)

    Dubuisson, Philippe; Carlan, Yann de; Garat, Véronique; Blat, Martine

    2012-09-01

    The development of ODS materials for the cladding for Sodium Fast Reactors is a key issue to achieve the objectives required for the GEN IV reactors. CEA, AREVA and EDF have launched in 2007 an important program to determine the optimal fabrication parameters, and to measure and understand the microstructure and properties before, under and after irradiation of such cladding materials. The aim of this paper is to present the French program and the major results obtained recently at CEA on Fe-9/14/18Cr1WTiY2O3 ferritic/martensitic ODS materials. The first step of the program was to consolidate Fe-9/14/18Cr ODS materials as plates and bars to study the microstructure and the mechanical properties of the new alloys. The second step consists in producing tubes at a geometry representative of the cladding of new Sodium Fast Reactors. The optimization of the fabrication route at the laboratory scale is conducted and different tubes were produced. Their microstructure depends on the martensitic (Fe-9Cr) or ferritic (Fe-14Cr) structure. To join the plug to the tube, the reference process is the welding resistance. A specific approach is developed to model the process and support the development of the welds performed within the "SOPRANO" facility. The development at CEA of Fe-9/14/18Cr new ODS materials for the cladding for GENIV Sodium Fast Reactors is in progress. The first microstructural and mechanical characterizations are very encouraging and the full assessment and qualification of this new alloys and products will pass through the irradiation of specimens, tubes, fuel pins and subassemblies up to high doses.

  3. Influence of microstructure on impact properties of 9-18%Cr ODS steels for fusion/fission applications

    NASA Astrophysics Data System (ADS)

    Hadraba, H.; Fournier, B.; Stratil, L.; Malaplate, J.; Rouffié, A.-L.; Wident, P.; Ziolek, L.; Béchade, J.-L.

    2011-04-01

    The paper describes the influence of the microstructure (coming from the extrusion shape, the chemical composition and the thermo-mechanical treatments) of (9-18%)Cr-W-Ti-Y 2O 3 ODS steels on their impact fracture properties. The extrusion shape plays a major role on the impact properties, materials extruded as a rod present a higher upper shelf energy (USE) and a lower ductile to brittle transition temperature (DBTT) compared to materials extruded as plates. The DBTT for the non-recrystallized 14%Cr ferritic steels was shifted towards higher temperatures compared to the 9%Cr tempered ferritic-martensitic steel. Increasing the W and Ti content in 9%Cr tempered ferritic-martensitic ODS steel leads to a USE and a DBTT shifted towards higher energies and higher temperatures respectively. Increasing the yttria content leads to a drop of the impact energy and a shift of the DBTT of ferritic ODS steel towards higher temperatures. The present study highlights extensive splitting of the fracture surfaces and a dependency of the impact energy on the fracture plane orientation according to the microstructure anisotropy.

  4. Diffusion Couple Alloying of Refractory Metals in Austenitic and Ferritic/Martensitic Steels

    DTIC Science & Technology

    2012-03-01

    diffusion couple method, the relative size of the solutes plays an important factor. Zirconium and hafnium, for example, would most likely be...smaller atoms from grain boundaries (Figure 2). The size of the solute is not the sole factor in determining the direction of diffusion, however...loss of Cr from the grain boundaries reduces the passive oxide -forming ability at that location, which makes the grain boundaries more susceptible

  5. Low temperature embrittlement behaviour of different ferritic-martensitic alloys for fusion applications

    NASA Astrophysics Data System (ADS)

    Rieth, M.; Dafferner, B.

    1996-10-01

    In the last few years a lot of different low activation CrWVTa steels have been developed world-wide. Without irradiation some of these alloys show clearly a better low temperature embrittlement behaviour than commercial CrNiMoV(Nb) alloys. Within the MANITU project a study was carried out to compare, prior to the irradiation program, the embrittlement behaviour of different alloys in the unirradiated condition performing instrumented Charpy impact bending tests with sub-size specimens. The low activation materials (LAM) considered were different OPTIFER alloys (Forschungszentrum Karlsruhe), F82H (JAERI), 9Cr2WVTa (ORNL), and GA3X (PNL). The modified commercial 10-11% CrNiMoVNb steels were MANET and OPTIMAR. A meaningful comparison between these alloys could be drawn, since the specimens of all materials were manufactured and tested under the same conditions.

  6. High strength, high ductility low carbon steel

    DOEpatents

    Koo, Jayoung; Thomas, Gareth

    1978-01-01

    A high strength, high ductility low carbon steel consisting essentially of iron, 0.05-0.15 wt% carbon, and 1-3 wt% silicon. Minor amounts of other constituents may be present. The steel is characterized by a duplex ferrite-martensite microstructure in a fibrous morphology. The microstructure is developed by heat treatment consisting of initial austenitizing treatment followed by annealing in the (.alpha. + .gamma.) range with intermediate quenching.

  7. Surface modification and deuterium retention in reduced-activation steels under low-energy deuterium plasma exposure. Part II: steels pre-damaged with 20 MeV W ions and high heat flux

    NASA Astrophysics Data System (ADS)

    Ogorodnikova, O. V.; Zhou, Z.; Sugiyama, K.; Balden, M.; Pintsuk, G.; Gasparyan, Yu.; Efimov, V.

    2017-03-01

    The reduced-activation ferritic/martensitic (RAFM) steels including Eurofer (9Cr) and oxide dispersion strengthened (ODS) steels by the addition of Y2O3 particles investigated in Part I were pre-damaged either with 20 MeV W ions at room temperature at IPP (Garching) or with high heat flux at FZJ (Juelich) and subsequently exposed to low energy (~20-200 eV per D) deuterium (D) plasma up to a fluence of 2.9  ×  1025 D m-2 in the temperature range from 290 K to 700 K. The pre-irradiation with 20 MeV W ions at room temperature up to 1 displacement per atom (dpa) has no noticeable influence on the steel surface morphology before and after the D plasma exposure. The pre-irradiation with W ions leads to the same concentration of deuterium in all kinds of investigated steels, regardless of the presence of nanoparticles and Cr content. It was found that (i) both kinds of irradiation with W ions and high heat flux increase the D retention in steels compared to undamaged steels and (ii) the D retention in both pre-damaged and undamaged steels decreases with a formation of surface roughness under the irradiation of steels with deuterium ions with incident energy which exceeds the threshold of sputtering. The increase in the D retention in RAFM steels pre-damaged either with W ions (damage up to ~3 µm) or high heat flux (damage up to ~10 µm) diminishes with increasing the temperature. It is important to mention that the near surface modifications caused by either implantation of high energy ions or a high heat flux load, significantly affect the total D retention at low temperatures or low fluences but have a negligible impact on the total D retention at elevated temperatures and high fluences because, in these cases, the D retention is mainly determined by bulk diffusion.

  8. Interdiffusion Behavior of Al-Rich Oxidation Resistant Coatings on Ferritic-Martensitic Alloys

    SciTech Connect

    Velraj, S.; Zhang, Ying; Hawkins, W. E.; Pint, Bruce A.

    2012-06-21

    We investigated interdiffusion of thin Al-rich coatings synthesized by chemical vapor deposition (CVD) and pack cementation on 9Cr ferritic–martensitic alloys in the temperature range of 650–700°C. The compositional changes after long-term exposures in laboratory air and air + 10 vol% H2O were examined experimentally. Interdiffusion was modeled by a modified coating oxidation and substrate interdiffusion model (COSIM) program. The modification enabled the program to directly input the concentration profiles of the as-deposited coating determined by electron probe microanalysis (EPMA). Reasonable agreement was achieved between the simulated and experimental Al profiles after exposures. Moreover, the model was also applied to predict coating lifetime at 650–700°C based on a minimum Al content (Cb) required at the coating surface to re-form protective oxide scale. In addition to a Cb value established from the failure of a thin CVD coating at 700°C, values reported for slurry aluminide coatings were also included in lifetime predictions.

  9. Irradiation response in weldment and HIP joint of reduced activation ferritic/martensitic steel, F82H

    SciTech Connect

    Hirose, Takanori; Sokolov, Mikhail A; Ando, M.; Tanigawa, H.; Shiba, K.; Stoller, Roger E; Odette, G.R.

    2013-11-01

    This work investigates irradiation response in the joints of F82H employed for a fusion breeding blanket. The joints, which were prepared using welding and diffusion welding, were irradiated up to 6 dpa in the High Flux Isotope Reactor at the Oak Ridge National Laboratory. Post-irradiation tests revealed hardening in weldment (WM) and base metal (BM) greater than 300 MPa. However, the heat affected zones (HAZ) exhibit about half that of WM and BM. Therefore, neutron irradiation decreased the strength of the HAZ, leaving it in danger of local deformation in this region. Further the hardening in WM made with an electron beam was larger than that in WM made with tungsten inert gas welding. However the mechanical properties of the diffusion-welded joint were very similar to those of BM even after the irradiation.

  10. Corrosion of stainless steel, 2. edition

    SciTech Connect

    Sedriks, A.J.

    1996-10-01

    The book describes corrosion characteristics in all the major and minor groups of stainless steels, namely, in austenitic, ferritic, martensitic, duplex, and precipitation hardenable steels. Several chapters are spent on those special forms of corrosion that are investigated in the great detail in stainless steels, namely, pitting corrosion, crevice corrosion, and stress corrosion cracking. The influences of thermal treatment (heat affected zone cases), composition, and microstructure on corrosion are given good coverage. Corrosive environments include high temperature oxidation, sulfidation as well as acids, alkalis, various different petroleum plant environments, and even human body fluids (stainless steels are commonly used prosthetic materials).

  11. Multiscale Modeling of the Deformation of Advanced Ferritic Steels for Generation IV Nuclear Energy

    SciTech Connect

    Nasr M. Ghoniem; Nick Kioussis

    2009-04-18

    The objective of this project is to use the multi-scale modeling of materials (MMM) approach to develop an improved understanding of the effects of neutron irradiation on the mechanical properties of high-temperature structural materials that are being developed or proposed for Gen IV applications. In particular, the research focuses on advanced ferritic/ martensitic steels to enable operation up to 650-700°C, compared to the current 550°C limit on high-temperature steels.

  12. Assessment of the Critical Parameters Influencing the Edge Stretchability of Advanced High-Strength Steel Sheet

    NASA Astrophysics Data System (ADS)

    Pathak, N.; Butcher, C.; Worswick, M.

    2016-11-01

    The edge formability of ferritic-martensitic DP (dual-phase) and ferritic-bainitic CP (complex-phase) steels was evaluated using a hole expansion test for different edge conditions. Hole expansion tests involving the standard conical punch as well as a custom flat punch were performed to investigate formability when the hole is expanded out-of-plane (conical punch) and in-plane using the flat punch. A range of edge conditions were considered, in order to isolate the influence of a range of factors thought to influence edge formability. The results demonstrate that work hardening and void damage at the sheared edge govern formability, while the sheared surface quality plays a minor or secondary role. A comparison of the edge stretching limits of DP and CP steels demonstrates the advantages of a ferritic-bainitic microstructure for forming operations with severe local deformation as in a stretch-flanging operation. A comparison of a traditional DP780 steel with a CP steel of similar strength showed that the edge stretching limit of the CP steel was three times larger than that of the DP780.

  13. A comparative study of the mechanical properties and the behavior of carbon and boron in stainless steel cladding tubes fabricated by PM HIP and traditional technologies

    NASA Astrophysics Data System (ADS)

    Shulga, A. V.

    2013-03-01

    The ring tensile test method was optimized and successfully used to obtain precise data for specimens of the cladding tubes of AISI type 316 austenitic stainless steels and ferritic-martensitic stainless steel. The positive modifications in the tensile properties of the stainless steel cladding tubes fabricated by powder metallurgy and hot isostatic pressing of melt atomized powders (PM HIP) when compared with the cladding tubes produced by traditional technology were found. Presently, PM HIP is also used in the fabrication of oxide dispersion strengthened (ODS) ferritic-martensitic steels. The high degree of homogeneity of the distribution of carbon and boron as well the high dispersivity of the phase-structure elements in the specimens manufactured via PM HIP were determined by direct autoradiography methods. These results correlate well with the increase of the tensile properties of the specimens produced by PM HIP technology.

  14. Joining techniques for a reduced activation 12Cr steel for inertial fusion energy

    SciTech Connect

    Hunt, R. M.; El-Dasher, B.; Choi, B. W.; Torres, S. G.

    2014-10-01

    At Lawrence Livermore National Laboratory, we are developing a reduced activation ferritic martensitic steel that is based on the ferritic martensitic steel HT-9. As a part of the development of this steel, we tested a series of welding processes for characterization, including conventional welds (electron beam, tungsten inert gas, and laser) as well as solid-state welds (hot isostatic pressing). We also heat treated the joints at various temperatures between 750 °C and 1050 °C to find a suitable normalization scheme. The modified HT-9 reduced activation ferritic martensitic steel appears highly suitable to welding and diffusion bonding. All welds showed good quality fusion zones with insignificant cracking or porosity. Additionally, a heat treatment schedule of 950 °C for one hour caused minimal grain growth while still converging the hardness of the base metal with that of the fusion and heat-affected zones. Also, modified HT-9 diffusion bonds that were created at temperatures of at least 950 °C for two hours at 103 MPa had interface tensile strengths of greater than 600 MPa. The diffusion bonds showed no evidence of increased hardness nor void formation at the diffusion bonded interface.

  15. Thermophysical and mechanical properties of Fe-(8-9)%Cr reduced activation steels

    SciTech Connect

    Zinkle, S.J.; Robertson, J.P.; Klueh, R.L.

    1998-09-01

    The key thermophysical and mechanical properties for 8--9%Cr reduced activation ferritic/martensitic steels are summarized, including temperature-dependent tensile properties in the unirradiated and irradiated conditions, stress-rupture behavior, elastic constants, thermal conductivity, thermal expansion, specific heat, and ductile-to-brittle transition temperature. The estimated lower and upper temperatures limits for structural applications are 250 and 550 C due to radiation hardening/embrittlement and thermal creep considerations, respectively.

  16. SCC and corrosion evaluations of the F/M steels for a supercritical water reactor

    NASA Astrophysics Data System (ADS)

    Hwang, Seong Sik; Lee, Byung Hak; Kim, Jung Gu; Jang, Jinsung

    2008-01-01

    As one of the Generation IV nuclear reactors, a supercritical water cooled reactor (SCWR) is being considered as a candidate reactor due to its high thermal efficiency and simple reactor design without steam generators and steam separators. For the application of a structural material to a core's internals and a fuel cladding, the material should be evaluated in terms of its corrosion and stress corrosion cracking susceptibility. Stress corrosion cracking and general corrosion tests of ferritic-martensitic (F/M) steels, high Ni alloys and an oxide dispersion strengthened (ODS) alloy were performed. Stress corrosion cracking (SCC) was not observed on the fractured surface of the T 91 steel in the supercritical water at 500, 550 and 600 °C. As the test temperature increased, the ultimate tensile strength (UTS) and yield strength (YS) of T 91 decreased, and a high dissolved oxygen level induced corrosion and low ductility. The F/M steels showed a high corrosion rate whereas the Ni base alloys showed a little corrosion at 500 and 550 °C. Corrosion rate of the F/M steels at 600 °C test was up to three times larger than that at 500 °C. A thin layer composed of Mo and Ni seems to retard the Cr diffusion into the out layer of the corrosion product of T 92 and T 122.

  17. Subcascade formation ratio in neutron-irradiated stainless steels

    NASA Astrophysics Data System (ADS)

    Yoshiie, T.; Satoh, Y.; Huang, S. S.; Horiki, M.; Sato, K.; Xu, Q.

    2016-01-01

    High-energy-particle irradiation in metals produces cascade damage. If the particle energy is high enough, a cascade is divided into subcascades. In each subcascade, a vacancy rich area is surrounded by an interstitial area. Vacancy clusters are expected to form directly in the vacancy rich area. In this study, the vacancy cluster formation ratio in subcascades was estimated by positron annihilation lifetime spectroscopy and transmission electron microscopy in commercial stainless steels and their model alloys. The vacancy cluster formation ratio was 1.7×10-3 and 9.1×10-5 in austenitic stainless steel and ferritic/martensitic stainless steel, respectively

  18. Effects of helium on ductile-brittle transition behavior of reduced-activation ferritic steels after high-concentration helium implantation at high temperature

    NASA Astrophysics Data System (ADS)

    Hasegawa, A.; Ejiri, M.; Nogami, S.; Ishiga, M.; Kasada, R.; Kimura, A.; Abe, K.; Jitsukawa, S.

    2009-04-01

    The effects of He on the fracture behavior of reduced-activation ferritic/martensitic steels, including oxide dispersion-strengthened (ODS) steels and F82H, was determined by characterizing the microstructural evolution in and fracture behavior of these steels after He implantation up to 1000 appm at around 550 °C. He implantation was carried out by a cyclotron with a beam of 50 MeV α-particles. In the case of F82H, the ductile-to-brittle transition temperature (DBTT) increase induced by He implantation was about 70 °C and the grain boundary fracture surface was only observed in the He-implanted area of all the ruptured specimens in brittle manner. By contrast, no DBTT shift or fracture mode change was observed in He-implanted 9Cr-ODS and 14Cr-ODS steels. Microstructural characterization suggested that the difference in the bubble formation behavior of F82H and ODS steels might be attributed to the grain boundary rupture of He-implanted F82H.

  19. Improvement of impact toughness of 5Mn-1Al-0.5Ti steel by intercritical annealing

    NASA Astrophysics Data System (ADS)

    Yi, Il-Cheol; Ha, Yumi; Lee, Hakcheol; Zargaran, A.; Kim, Nack J.

    2017-02-01

    The present study is aimed at improving the impact toughness of 5Mn-1Al-0.5Ti steel by incorporating ferrite-martensite dual phase microstructure by intercritical annealing. Although (8-12)Mn martensitic steels usually show very low impact toughness due to the occurrence of intergranular fracture, the martensitic structure of the present 5Mn-1Al-0.5Ti steel fails by transgranular cleavage fracture due to higher grain boundary strength than matrix strength incurred by reduced Mn content and segregation of Ti along grain boundaries. Nevertheless, it still shows very poor impact toughness at room temperature due to its coarse grain size. The application of intercritical annealing, i.e., formation of dual phase microstructure, is shown to significantly decrease ductile-to-brittle transition temperature (DBTT), with only a small degradation of tensile properties; however, microstructural examinations show that most of ferrite/martensite interfaces have a character of low angle boundaries and therefore such decrease in DBTT is not necessarily due to the formation of ferrite-martensite dual phase structure, but rather to the refinement of grain size by low temperature annealing.

  20. Improvement of impact toughness of 5Mn-1Al-0.5Ti steel by intercritical annealing

    NASA Astrophysics Data System (ADS)

    Yi, Il-Cheol; Ha, Yumi; Lee, Hakcheol; Zargaran, A.; Kim, Nack J.

    2017-03-01

    The present study is aimed at improving the impact toughness of 5Mn-1Al-0.5Ti steel by incorporating ferrite-martensite dual phase microstructure by intercritical annealing. Although (8-12)Mn martensitic steels usually show very low impact toughness due to the occurrence of intergranular fracture, the martensitic structure of the present 5Mn-1Al-0.5Ti steel fails by transgranular cleavage fracture due to higher grain boundary strength than matrix strength incurred by reduced Mn content and segregation of Ti along grain boundaries. Nevertheless, it still shows very poor impact toughness at room temperature due to its coarse grain size. The application of intercritical annealing, i.e., formation of dual phase microstructure, is shown to significantly decrease ductile-to-brittle transition temperature (DBTT), with only a small degradation of tensile properties; however, microstructural examinations show that most of ferrite/martensite interfaces have a character of low angle boundaries and therefore such decrease in DBTT is not necessarily due to the formation of ferrite-martensite dual phase structure, but rather to the refinement of grain size by low temperature annealing.

  1. Microstructure evolution during helium irradiation and post-irradiation annealing in a nanostructured reduced activation steel

    NASA Astrophysics Data System (ADS)

    Liu, W. B.; Ji, Y. Z.; Tan, P. K.; Zhang, C.; He, C. H.; Yang, Z. G.

    2016-10-01

    Severe plastic deformation, intense single-beam He-ion irradiation and post-irradiation annealing were performed on a nanostructured reduced activation ferritic/martensitic (RAFM) steel to investigate the effect of grain boundaries (GBs) on its microstructure evolution during these processes. A surface layer with a depth-dependent nanocrystalline (NC) microstructure was prepared in the RAFM steel using surface mechanical attrition treatment (SMAT). Microstructure evolution after helium (He) irradiation (24.8 dpa) at room temperature and after post-irradiation annealing was investigated using Transmission Electron Microscopy (TEM). Experimental observation shows that GBs play an important role during both the irradiation and the post-irradiation annealing process. He bubbles are preferentially trapped at GBs/interfaces during irradiation and cavities with large sizes are also preferentially trapped at GBs/interfaces during post-irradiation annealing, but void denuded zones (VDZs) near GBs could not be unambiguously observed. Compared with cavities at GBs and within larger grains, cavities with smaller size and higher density are found in smaller grains. The average size of cavities increases rapidly with the increase of time during post-irradiation annealing at 823 K. Cavities with a large size are observed just after annealing for 5 min, although many of the cavities with small sizes also exist after annealing for 240 min. The potential mechanism of cavity growth behavior during post-irradiation annealing is also discussed.

  2. Microstructure and mechanical strength of diffusion bonded joints between silicon carbide and F82H steel

    NASA Astrophysics Data System (ADS)

    Zhong, Zhihong; Hinoki, Tatsuya; Kohyama, Akira

    2011-10-01

    The combination of SiC and reduced activation ferritic/martensitic steels is attractive for fusion applications because it is expected to offer high thermal efficiency, high reliability and superior safety characteristic under a neutron irradiation environment. In this paper, diffusion bonding of SiC to F82H steel has been investigated. Direct joining of SiC to F82H was unsuccessful due to a large residual stress generated in the joint. A double W/Cu and a multiple W/Ni/Cu/Ni interlayer were used to reduce the residual stress, and encouraging results were obtained. The interfacial microstructure examination revealed that the various interfaces were bonded well. Diffusion products in the reaction zones were identified. The shear strength of the SiC/F82H joints measured by knife-edge tests at room temperature was found to increase with the increase in the joining temperature, and reached a maximum of 41.3 MPa. The fracture surfaces of the joints were also analyzed.

  3. Modified Law of Mixture to Describe the Tensile Deformation Behavior of Thermomechanically Processed Dual-Phase Steel

    NASA Astrophysics Data System (ADS)

    Ahmad, E.

    2013-08-01

    Low alloy steel containing 0.09 wt.% C was thermomechanically processed with various rolling reductions at intercritical temperature of 790 °C, followed by quenching in the iced brine solution. The flow of the material due to this plastic deformation increased the aspect ratio of the microstructure (α + γ) in the rolling than in the transverse directions. The strengths, both in the longitudinal and transverse directions of rolling were increased because of the development of substructure in ferrite, observed previously. The fibrous microstructure formed after rolling increased the surface area of contact of ferrite and martensite. During tensile deformation the fibrous dual-phase composite had positioned itself for better stress transfer from soft ferrite to hard martensite particles. These microstructural changes associated with hot deformation of the material were accommodated in current modifications in the law of mixture applied to dual-phase steel. A computer simulation was developed to present the deformation behavior of ferrite, martensite, and composite from the experimental tensile data (loads and strain). Different variables were introduced in the simulation for allowing the composite curves to pass through the experimental data points to demonstrate the tensile deformation behavior of ferrite and martensite. The systematic changes in these variables with degree of hot rolling in the intercritical region clearly described the deformation behaviour of ferrite and martensite individually.

  4. Mechanical Properties of Laser Heat Treated 6 mm Thick UHSS-Steel

    SciTech Connect

    Jaervenpaeae, Antti; Maentyjaervi, Kari; Maeaettae, Antti; Hietala, Mikko; Merklein, Marion; Karjalainen, Jussi

    2011-05-04

    In this work abrasion resistant (AR) steel with a sheet thickness of 6 mm was heat treated by a 4 kW Nd:YAG and a 4 kW Yb:Yag-laser, followed by self-quenching. In the delivered condition, test material blank (B27S) is water quenched from 920 deg. C. In this condition, fully martensitic microstructure provides excellent hardness of over 500 HB. The test material is referred to AR500 from now onwards. Laser heat treatment was carried out only on top surface of the AR500 sheet: the achieved maximum temperature in the cross-section varies as a function of the depth. Consequently, the microstructure and mechanical properties differ between the surfaces and the centre of the cross-section (layered microstructure). For better understanding, all layers were tested in tensile tests. For a wide heat treatment track, the laser beam was moved by scanning. Temperatures were measured using thermographic camera and thermocouples. Laser heat treated AR500 samples were tested in hardness tests and by air bending using a press brake machine. Microstructures were studied using a light microscope and FE-SEM/SEM-EBSD. At least three kind of microstructure layers were observed: 1) Dual-Phase ferritic/martensitic (T = A{sub C1}-A{sub C3}), 2) ferritic (T{approx}A{sub C3}) and 3) bainitic/martensitic (T>A{sub C3}).

  5. Phase analysis on dual-phase steel using band slope of electron backscatter diffraction pattern.

    PubMed

    Kang, Jun-Yun; Park, Seong-Jun; Moon, Man-Been

    2013-08-01

    A quantitative and automated phase analysis of dual-phase (DP) steel using electron backscatter diffraction (EBSD) was attempted. A ferrite-martensite DP microstructure was produced by intercritical annealing and quenching. An EBSD map of the microstructure was obtained and post-processed for phase discrimination. Band slope (BS), which was a measure of pattern quality, exhibited much stronger phase contrast than another conventional one, band contrast. Owing to high sensitivity to lattice defect and little orientation dependence, BS provided handiness in finding a threshold for phase discrimination. Its grain average gave a superior result on the discrimination and volume fraction measurement of the constituent phases in the DP steel.

  6. Hydrogen compatibility handbook for stainless steels

    SciTech Connect

    Caskey, G.R. Jr.

    1983-06-01

    This handbook compiles data on the effects of hydrogen on the mechanical properties of stainless steels and discusses this data within the context of current understanding of hydrogen compatibility of metals. All of the tabulated data derives from continuing studies of hydrogen effects on materials that have been conducted at the Savannah River Laboratory over the past fifteen years. Supplementary data from other sources are included in the discussion. Austenitic, ferritic, martensitic, and precipitation hardenable stainless steels have been studied. Damage caused by helium generated from decay of tritium is a distinctive effect that occurs in addition to the hydrogen isotopes protium and deuterium. The handbook defines the scope of our current knowledge of hydrogen effects in stainless steels and serves as a guide to selection of stainless steels for service in hydrogen.

  7. Electrochemically enhanced surface plasticity of steels

    NASA Astrophysics Data System (ADS)

    Gutman, E. M.; Unigovski, Ya.; Shneck, R.; Ye, F.; Liang, Y.

    2016-12-01

    There are serious problems with the formability of alloys which are relatively hard and brittle below ambient temperatures, e.g., in cold extrusion and drawing processes. It is known that electrochemical surface treatment can decrease residual stresses and hardness of the surface layer as a result of the chemomechanical effect (CME), and also improve the plastic deformation ability, e.g., deep drawing of high-strength alloys. Plastic deformation ability of materials can be characterized by hardness measurements. The present study shows some possibilities to improve the surface ductility of carbon steels and FeSi6.5 steel under anodic polarization depending on the current density, composition and pH of acids and chloride electrolytes. The relative Vickers hardness (RVH) amounting to a squared ratio of the penetration depth of a cone indenter in air as compared to that in a solution (hair/hsol)2 was found as a function of the current density and the electrolyte composition. A decrease in hardness of the surface layer as a result of anodic electrochemical polarization was found for different steels.

  8. Specular steel surfaces for solar mirror substrates

    NASA Astrophysics Data System (ADS)

    Tracy, C. E.; Gross, G. E.

    1988-04-01

    The long-range objective is to develop a process for making a silvered stainless steel mirror that has the optical performance and service life of a mirror coupled with the mechanical durability, structural strength, and flexibility of sheet steel. Such reflectors are expected to minimize the cost handling, shipping, and fabrication into concentrators. Applications for helistats are assumed to require a lifetime average reflectance of 90 percent in a full-cone aperture angle of 8 mrad. Specifically, this work is designed to produce thin metal membranes with sufficiently fine surface finishes to serve as substrates for direct silver deposition or indirectly for silvered polymer films or silvered sol-gel coatings in heliostat, parabolic trough, and dish applications. Our focus is on the effect of the sheet metal finish on specularity and the ways to obtain the optimum surface finish by conventional manufacturing processes. This report addresses the relationship of optical quality to surface finish and the results of a cooperative research venture with a commercial sheet manufacturer to produce specular stainless steel surfaces by cold-rolling with highly polished rollers.

  9. Hybrid Laser-Arc Welding of 10-mm-Thick Cast Martensitic Stainless Steel CA6NM: As-Welded Microstructure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Mirakhorli, Fatemeh; Cao, Xinjin; Pham, Xuan-Tan; Wanjara, Priti; Fihey, Jean-Luc

    2016-07-01

    Cast CA6NM martensitic stainless steel plates, 10 mm in thickness, were welded using hybrid laser-arc welding. The effect of different welding speeds on the as-welded joint integrity was characterized in terms of the weld bead geometry, defects, microstructure, hardness, ultimate tensile strength, and impact energy. Significant defects such as porosity, root humping, underfill, and excessive penetration were observed at a low welding speed (0.5 m/min). However, the underfill depth and excessive penetration in the joints manufactured at welding speeds above 0.75 m/min met the specifications of ISO 12932. Characterization of the as-welded microstructure revealed untempered martensite and residual delta ferrite dispersed at prior-austenite grain boundaries in the fusion zone. In addition, four different heat-affected zones in the weldments were differentiated through hardness mapping and inference from the Fe-Cr-Ni ternary phase diagram. The tensile fracture occurred in the base metal for all the samples and fractographic analysis showed that the crack path is within the martensite matrix, along primary delta ferrite-martensite interfaces and within the primary delta ferrite. Additionally, Charpy impact testing demonstrated slightly higher fracture energy values and deeper dimples on the fracture surface of the welds manufactured at higher welding speeds due to grain refinement and/or lower porosity.

  10. Concepts for the Development of Nanoscale Stable Precipitation-Strengthened Steels Manufactured by Conventional Methods

    NASA Astrophysics Data System (ADS)

    Yablinsky, C. A.; Tippey, K. E.; Vaynman, S.; Anderoglu, O.; Fine, M. E.; Chung, Y.-W.; Speer, J. G.; Findley, K. O.; Dogan, Ö. N.; Jablonski, P. D.; Maloy, S. A.; Hackenberg, R. E.; Clarke, A. J.; Clarke, K. D.

    2014-12-01

    The development of oxide dispersion strengthened ferrous alloys has shown that microstructures designed for excellent irradiation resistance and thermal stability ideally contain stable nanoscale precipitates and dislocation sinks. Based upon this understanding, the microstructures of conventionally manufactured ferritic and ferritic-martensitic steels can be designed to include controlled volume fractions of fine, stable precipitates and dislocation sinks via specific alloying and processing paths. The concepts proposed here are categorized as advanced high-Cr ferritic-martensitic (AHCr-FM) and novel tailored precipitate ferritic (TPF) steels, which have the potential to improve the in-reactor performance of conventionally manufactured alloys. AHCr-FM steels have modified alloy content relative to current reactor materials (such as alloy NF616/P92) to maximize desirable precipitates and control phase stability. TPF steels are designed to incorporate nickel aluminides, in addition to microalloy carbides, in a ferritic matrix to produce fine precipitate arrays with good thermal stability. Both alloying concepts may also benefit from thermomechanical processing to establish dislocation sinks and modify phase transformation behaviors. Alloying and processing paths toward designed microstructures are discussed for both AHCr-FM and TPF material classes.

  11. Concepts for the development of nanoscale stable precipitation-strengthened steels manufactured by conventional methods

    DOE PAGES

    Yablinsky, C. A.; Tippey, K. E.; Vaynman, S.; ...

    2014-11-11

    In this study, the development of oxide dispersion strengthened ferrous alloys has shown that microstructures designed for excellent irradiation resistance and thermal stability ideally contain stable nanoscale precipitates and dislocation sinks. Based upon this understanding, the microstructures of conventionally manufactured ferritic and ferritic-martensitic steels can be designed to include controlled volume fractions of fine, stable precipitates and dislocation sinks via specific alloying and processing paths. The concepts proposed here are categorized as advanced high-Cr ferritic-martensitic (AHCr-FM) and novel tailored precipitate ferritic (TPF) steels, which have the potential to improve the in-reactor performance of conventionally manufactured alloys. AHCr-FM steels have modifiedmore » alloy content relative to current reactor materials (such as alloy NF616/P92) to maximize desirable precipitates and control phase stability. TPF steels are designed to incorporate nickel aluminides, in addition to microalloy carbides, in a ferritic matrix to produce fine precipitate arrays with good thermal stability. Both alloying concepts may also benefit from thermomechanical processing to establish dislocation sinks and modify phase transformation behaviors. Alloying and processing paths toward designed microstructures are discussed for both AHCr-FM and TPF material classes.« less

  12. Concepts for the development of nanoscale stable precipitation-strengthened steels manufactured by conventional methods

    SciTech Connect

    Yablinsky, C. A.; Tippey, K. E.; Vaynman, S.; Anderoglu, O.; Fine, M. E.; Chung, Y. -W.; Speer, J. G.; Findley, K. O.; Dogan, O. N.; Jablonski, P. D.; Maloy, S. A.; Hackenberg, R. E.; Clarke, A. J.; Clarke, K. D.

    2014-11-11

    In this study, the development of oxide dispersion strengthened ferrous alloys has shown that microstructures designed for excellent irradiation resistance and thermal stability ideally contain stable nanoscale precipitates and dislocation sinks. Based upon this understanding, the microstructures of conventionally manufactured ferritic and ferritic-martensitic steels can be designed to include controlled volume fractions of fine, stable precipitates and dislocation sinks via specific alloying and processing paths. The concepts proposed here are categorized as advanced high-Cr ferritic-martensitic (AHCr-FM) and novel tailored precipitate ferritic (TPF) steels, which have the potential to improve the in-reactor performance of conventionally manufactured alloys. AHCr-FM steels have modified alloy content relative to current reactor materials (such as alloy NF616/P92) to maximize desirable precipitates and control phase stability. TPF steels are designed to incorporate nickel aluminides, in addition to microalloy carbides, in a ferritic matrix to produce fine precipitate arrays with good thermal stability. Both alloying concepts may also benefit from thermomechanical processing to establish dislocation sinks and modify phase transformation behaviors. Alloying and processing paths toward designed microstructures are discussed for both AHCr-FM and TPF material classes.

  13. Iron cycling at corroding carbon steel surfaces.

    PubMed

    Lee, Jason S; McBeth, Joyce M; Ray, Richard I; Little, Brenda J; Emerson, David

    2013-01-01

    Surfaces of carbon steel (CS) exposed to mixed cultures of iron-oxidizing bacteria (FeOB) and dissimilatory iron-reducing bacteria (FeRB) in seawater media under aerobic conditions were rougher than surfaces of CS exposed to pure cultures of either type of microorganism. The roughened surface, demonstrated by profilometry, is an indication of loss of metal from the surface. In the presence of CS, aerobically grown FeOB produced tight, twisted helical stalks encrusted with iron oxides. When CS was exposed anaerobically in the presence of FeRB, some surface oxides were removed. However, when the same FeOB and FeRB were grown together in an aerobic medium, FeOB stalks were less encrusted with iron oxides and appeared less tightly coiled. These observations suggest that iron oxides on the stalks were reduced and solubilized by the FeRB. Roughened surfaces of CS and denuded stalks were replicated with culture combinations of different species of FeOB and FeRB under three experimental conditions. Measurements of electrochemical polarization resistance established different rates of corrosion of CS in aerobic and anaerobic media, but could not differentiate rate differences between sterile controls and inoculated exposures for a given bulk concentration of dissolved oxygen. Similarly, total iron in the electrolyte could not be used to differentiate treatments. The experiments demonstrate the potential for iron cycling (oxidation and reduction) on corroding CS in aerobic seawater media.

  14. Effect of grain size on the mechanical properties of dual phase Fe/Si/C steels

    SciTech Connect

    Ahn, J.H.

    1983-08-01

    For an Fe/2Si/0.1C steel with an intermediate quenching heat treatment, it was found that as the prior austenite grain size is refined, significant improvements in total elongation, reduction in area and impact toughness can be achieved, while uniform elongation, yield and tensile strengths are not affected. These improvements are analyzed in terms of microstructure and fracture characteristics. The cleavage cracks propagate nearly straight without deviation at the ferrite/martensite interfaces within the sub-units of the DFM structure, but change their path at high angle sub-unit boundaries. The crack is less likely to be deflected at the ferrite/martensite interface because the interface is coherent. Comparison of optical micrographs and SEM fractographs has shown that there is close agreement between the sub-unit size and cleavage facet size. The observations lead to the conclusion that the sub-unit size is the basic microstructure unit controlling the fracture behavior of DFM steels produced by the intermediate quenching heat treatment. A controlled rolling process was undertaken to obtain grain refined DFM steels. Results showed that this produces micro-duplex structures with attractive mechanical properties in an economicl way.

  15. Friction Stir Welding of ODS and RAFM Steels

    SciTech Connect

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; Tan, Lizhen; Sokolov, Mikhail A.

    2015-09-14

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this paper, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW on grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Finally, post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.

  16. Friction Stir Welding of ODS and RAFM Steels

    NASA Astrophysics Data System (ADS)

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; Tan, Lizhen; Sokolov, Mikhail A.

    2015-09-01

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this work, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW on grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.

  17. Friction Stir Welding of ODS and RAFM Steels

    DOE PAGES

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; ...

    2015-09-14

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this paper, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW onmore » grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Finally, post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.« less

  18. Laser surface texturing of tool steel: textured surfaces quality evaluation

    NASA Astrophysics Data System (ADS)

    Šugár, Peter; Šugárová, Jana; Frnčík, Martin

    2016-05-01

    In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

  19. Surface design methodology - challenge the steel

    NASA Astrophysics Data System (ADS)

    Bergman, M.; Rosen, B.-G.; Eriksson, L.; Anderberg, C.

    2014-03-01

    The way a product or material is experienced by its user could be different depending on the scenario. It is also well known that different materials and surfaces are used for different purposes. When optimizing materials and surface roughness for a certain something with the intention to improve a product, it is important to obtain not only the physical requirements, but also the user experience and expectations. Laws and requirements of the materials and the surface function, but also the conservative way of thinking about materials and colours characterize the design of medical equipment. The purpose of this paper is to link the technical- and customer requirements of current materials and surface textures in medical environments. By focusing on parts of the theory of Kansei Engineering, improvements of the companys' products are possible. The idea is to find correlations between desired experience or "feeling" for a product, -customer requirements, functional requirements, and product geometrical properties -design parameters, to be implemented on new improved products. To be able to find new materials with the same (or better) technical requirements but a higher level of user stimulation, the current material (stainless steel) and its surface (brushed textures) was used as a reference. The usage of focus groups of experts at the manufacturer lead to a selection of twelve possible new materials for investigation in the project. In collaboration with the topical company for this project, three new materials that fulfil the requirements -easy to clean and anti-bacterial came to be in focus for further investigation in regard to a new design of a washer-disinfector for medical equipment using the Kansei based Clean ability approach CAA.

  20. Surface modified stainless steels for PEM fuel cell bipolar plates

    DOEpatents

    Brady, Michael P [Oak Ridge, TN; Wang, Heli [Littleton, CO; Turner, John A [Littleton, CO

    2007-07-24

    A nitridation treated stainless steel article (such as a bipolar plate for a proton exchange membrane fuel cell) having lower interfacial contact electrical resistance and better corrosion resistance than an untreated stainless steel article is disclosed. The treated stainless steel article has a surface layer including nitrogen-modified chromium-base oxide and precipitates of chromium nitride formed during nitridation wherein oxygen is present in the surface layer at a greater concentration than nitrogen. The surface layer may further include precipitates of titanium nitride and/or aluminum oxide. The surface layer in the treated article is chemically heterogeneous surface rather than a uniform or semi-uniform surface layer exclusively rich in chromium, titanium or aluminum. The precipitates of titanium nitride and/or aluminum oxide are formed by the nitriding treatment wherein titanium and/or aluminum in the stainless steel are segregated to the surface layer in forms that exhibit a low contact resistance and good corrosion resistance.

  1. High-throughput design of low-activation, high-strength creep-resistant steels for nuclear-reactor applications

    NASA Astrophysics Data System (ADS)

    Lu, Qi; van der Zwaag, Sybrand; Xu, Wei

    2016-02-01

    Reduced-activation ferritic/martensitic steels are prime candidate materials for structural applications in nuclear power reactors. However, their creep strength is much lower than that of creep-resistant steel developed for conventional fossil-fired power plants as alloying elements with a high neutron activation cannot be used. To improve the creep strength and to maintain a low activation, a high-throughput computational alloy design model coupling thermodynamics, precipitate-coarsening kinetics and an optimization genetic algorithm, is developed. Twelve relevant alloying elements with either low or high activation are considered simultaneously. The activity levels at 0-10 year after the end of irradiation are taken as optimization parameter. The creep-strength values (after exposure for 10 years at 650 °C) are estimated on the basis of the solid-solution strengthening and the precipitation hardening (taking into account precipitate coarsening). Potential alloy compositions leading to a high austenite fraction or a high percentage of undesirable second phase particles are rejected automatically in the optimization cycle. The newly identified alloys have a much higher precipitation hardening and solid-solution strengthening at the same activity level as existing reduced-activation ferritic/martensitic steels.

  2. Characteristic results and prospects of the 13Cr-1W-0.3Ti-0.3Y 2O 3 ODS steel

    NASA Astrophysics Data System (ADS)

    Eiselt, Ch. Ch.; Klimenkov, M.; Lindau, R.; Möslang, A.

    2009-04-01

    For specific blanket and divertor applications in future fusion power reactors a replacement of presently considered reduced activation ferritic martensitic (RAFM) steels as structural material by suitable oxide dispersion strengthened (ODS) ferritic martensitic steels would allow a substantial increase of the operating temperature from ˜550 °C to about 650 °C. Temperatures above 700 °C in the He cooled modular divertor concept necessitates the use of ferritic (RAF) ODS steels, which are not limited by a phase transition. Therefore a 13Cr-1W-0.3Ti-0.3Y 2O 3 ferritic ODS steel is being developed, using an Attritor with varying milling parameters. Afterwards the mechanically alloyed powders were encapsulated, sealed and consolidated in a hot isostatic press device. In this work, the effects of several parameter variations on the microstructure of the produced ferritic ODS-alloys, analysed by optical microscopy (OM) and high resolution TEM, as well as results of conducted mechanical tests are presented.

  3. Microstructure and mechanical properties of newly developed low activation martensitic steels

    NASA Astrophysics Data System (ADS)

    Victoria, M.; Gavillet, D.; Spätig, P.; Rezai-Aria, F.; Rossmann, S.

    1996-10-01

    The reference ferritic-martensitic steel of the European Fusion Technology Program, the 10CrMoNbV MANET cast, has been modified by replacing the elements that result in long term residual radioactivity when irradiated under a fusion neutron spectra by others which have shorter activation periods. A base composition of a 9CrWVTa steel has been so defined. Two different compositions of the base alloy have been cast from high purity components, which the Mn and N contents have been varied. The extracted carbide types and their size distribution have been studied under the electron microscope. The mechanical properties of both compositions have been determined. Both steel compositions have a ductile-brittle transition temperature (DBTT) well below room temperature while their tensile properties are comparable to those of the parent (MANET) steel.

  4. Abnormal grain growth in Eurofer-97 steel in the ferrite phase field

    NASA Astrophysics Data System (ADS)

    Oliveira, V. B.; Sandim, H. R. Z.; Raabe, D.

    2017-03-01

    Reduced-activation ferritic-martensitic (RAFM) Eurofer-97 steel is a candidate material for structural applications in future fusion reactors. Depending on the amount of prior cold rolling strain and annealing temperature, important solid-state softening reactions such as recovery, recrystallization, and grain growth occur. Eurofer-97 steel was cold rolled up to 70, 80 and 90% reductions in thickness and annealed in the ferrite phase field (below ≈ 800 °C). Changes in microstructure, micro-, and mesotexture were followed by orientation mappings provided by electron backscatter diffraction (EBSD). Eurofer-97 steel undergoes abnormal grain growth above 650 °C and this solid-state reaction seems to be closely related to the high mobility of a few special grain boundaries that overcome pinning effects caused by fine particles. This solid-state reaction promotes important changes in the microstructure and microtexture of this steel. Abnormal grain growth kinetics for each condition was determined by means of quantitative metallography.

  5. Structural-phase states and wear resistance of surface formed on steel by surfacing

    SciTech Connect

    Kapralov, Evgenie V.; Raykov, Sergey V.; Vaschuk, Ekaterina S.; Budovskikh, Evgenie A. Gromov, Victor E.; Ivanov, Yuri F.

    2014-11-14

    Investigations of elementary and phase structure, state of defect structure and tribological characteristics of a surfacing, formed on a low carbon low-alloy steel by a welding method were carried out. It was revealed that a surfacing, formed on a steel surface is accompanied by the multilayer formation, and increases the wear resistance of the layer surfacing as determined.

  6. The effect of processing variables on steel surface chemistry

    SciTech Connect

    Shaw, G.S.

    1993-12-31

    Differences in processing at all stages in the steel making process can effect the surface chemistry of steel. The surface chemistry can dictate the performance of many different products and processes including electrogalvanized steel. If the steel chemistry is not controlled sufficiently, the zinc electrodeposit will be subject to hydrogen blistering. This dissertation examined the effect of many processing variables on both the organic and inorganic contaminants on steel surfaces. Processes both before the electrogalvanizing line and those after the electrogalvanizing line were examined. Mechanisms were determined for reactions of organic oils with the steel surface. Reaction between the carbonyl functionality, present as an acid or an ester, and iron hydroxide to form a tenaciously adherent iron soap was demonstrated using infrared spectroscopy and mass spectrometry. Thermodynamics and kinetics of segregation of metallic elements to the surface of the steel were determined. It was shown that the primary mechanism for segregation of elements such as aluminum, silicon, chromium, and titanium is oxidation during the anneal. Analysis of the kinetics indicated the feasibility of this mechanism. The mechanism of electrocleaning were elucidated, based on both electrochemical and physical effects. Improved methods of electrocleaning were described based upon optimization of the cleaning frequency. It was found that increasing the frequency of anodic and cathodic cycling increasing the cleaning efficiency up to about 5 Hz. Above this frequency bubbles, which provide physical scrubbing and convection near the interface, can not form rapidly enough to be effective. Increased current density was shown to be effective in improving electrocleaning.

  7. Electrolytic etching process provides effective bonding surface on stainless steel

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Electrolytic etching process prepares surfaces of a stainless steel shell for reliable, high strength adhesive bonding to dielectric materials. The process uses a 25 percent aqueous solution of phosphoric acid.

  8. Antibacterial effect of silver nanofilm modified stainless steel surface

    NASA Astrophysics Data System (ADS)

    Fang, F.; Kennedy, J.; Dhillon, M.; Flint, S.

    2015-03-01

    Bacteria can attach to stainless steel surfaces, resulting in the colonization of the surface known as biofilms. The release of bacteria from biofilms can cause contamination of food such as dairy products in manufacturing plants. This study aimed to modify stainless steel surfaces with silver nanofilms and to examine the antibacterial effectiveness of the modified surface. Ion implantation was applied to produce silver nanofilms on stainless steel surfaces. 35 keV Ag ions were implanted with various fluences of 1 × 1015 to 1 × 1017 ions•cm-2 at room temperature. Representative atomic force microscopy characterizations of the modified stainless steel are presented. Rutherford backscattering spectrometry spectra revealed the implanted atoms were located in the near-surface region. Both unmodified and modified stainless steel coupons were then exposed to two types of bacteria, Pseudomonas fluorescens and Streptococcus thermophilus, to determine the effect of the surface modification on bacterial attachment and biofilm development. The silver modified coupon surface fluoresced red over most of the surface area implying that most bacteria on coupon surface were dead. This study indicates that the silver nanofilm fabricated by the ion implantation method is a promising way of reducing the attachment of bacteria and delay biofilm formation.

  9. Micromechanics of plastic deformation and phase transformation in a three-phase TRIP-assisted advanced high strength steel: Experiments and modeling

    NASA Astrophysics Data System (ADS)

    Srivastava, Ankit; Ghassemi-Armaki, Hassan; Sung, Hyokyung; Chen, Peng; Kumar, Sharvan; Bower, Allan F.

    2015-05-01

    The micromechanics of plastic deformation and phase transformation in a three-phase advanced high strength steel are analyzed both experimentally and by microstructure-based simulations. The steel examined is a three-phase (ferrite, martensite and retained austenite) quenched and partitioned sheet steel with a tensile strength of ~980 MPa. The macroscopic flow behavior and the volume fraction of martensite resulting from the austenite-martensite transformation during deformation were measured. In addition, micropillar compression specimens were extracted from the individual ferrite grains and the martensite particles, and using a flat-punch nanoindenter, stress-strain curves were obtained. Finite element simulations idealize the microstructure as a composite that contains ferrite, martensite and retained austenite. All three phases are discretely modeled using appropriate crystal plasticity based constitutive relations. Material parameters for ferrite and martensite are determined by fitting numerical predictions to the micropillar data. The constitutive relation for retained austenite takes into account contributions to the strain rate from the austenite-martensite transformation, as well as slip in both the untransformed austenite and product martensite. Parameters for the retained austenite are then determined by fitting the predicted flow stress and transformed austenite volume fraction in a 3D microstructure to experimental measurements. Simulations are used to probe the role of the retained austenite in controlling the strain hardening behavior as well as internal stress and strain distributions in the microstructure.

  10. Low Temperature Surface Carburization of Stainless Steels

    SciTech Connect

    Collins, Sunniva R; Heuer, Arthur H; Sikka, Vinod K

    2007-12-07

    Low-temperature colossal supersaturation (LTCSS) is a novel surface hardening method for carburization of austenitic stainless steels (SS) without the precipitation of carbides. The formation of carbides is kinetically suppressed, enabling extremely high or colossal carbon supersaturation. As a result, surface carbon concentrations in excess of 12 at. % are routinely achieved. This treatment increases the surface hardness by a factor of four to five, improving resistance to wear, corrosion, and fatigue, with significant retained ductility. LTCSS is a diffusional surface hardening process that provides a uniform and conformal hardened gradient surface with no risk of delamination or peeling. The treatment retains the austenitic phase and is completely non-magnetic. In addition, because parts are treated at low temperature, they do not distort or change dimensions. During this treatment, carbon diffusion proceeds into the metal at temperatures that constrain substitutional diffusion or mobility between the metal alloy elements. Though immobilized and unable to assemble to form carbides, chromium and similar alloying elements nonetheless draw enormous amounts of carbon into their interstitial spaces. The carbon in the interstitial spaces of the alloy crystals makes the surface harder than ever achieved before by more conventional heat treating or diffusion process. The carbon solid solution manifests a Vickers hardness often exceeding 1000 HV (equivalent to 70 HRC). This project objective was to extend the LTCSS treatment to other austenitic alloys, and to quantify improvements in fatigue, corrosion, and wear resistance. Highlights from the research include the following: • Extension of the applicability of the LTCSS process to a broad range of austenitic and duplex grades of steels • Demonstration of LTCSS ability for a variety of different component shapes and sizes • Detailed microstructural characterization of LTCSS-treated samples of 316L and other alloys

  11. Bactericidal behavior of Cu-containing stainless steel surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyu; Huang, Xiaobo; Ma, Yong; Lin, Naiming; Fan, Ailan; Tang, Bin

    2012-10-01

    Stainless steels are one of the most common materials used in health care environments. However, the lack of antibacterial advantage has limited their use in practical application. In this paper, antibacterial stainless steel surfaces with different Cu contents have been prepared by plasma surface alloying technology (PSAT). The steel surface with Cu content 90 wt.% (Cu-SS) exhibits strong bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) within 3 h. Although the Cu-containing surface with Cu content 2.5 wt.% (CuNi-SS) can also kill all tested bacteria, this process needs 12 h. SEM observation of the bacterial morphology and an agarose gel electrophoresis were performed to study the antibacterial mechanism of Cu-containing stainless steel surfaces against E. coli. The results indicated that Cu ions are released when the Cu-containing surfaces are in contact with bacterial and disrupt the cell membranes, killing the bacteria. The toxicity of Cu-alloyed surfaces does not cause damage to the bacterial DNA. These results provide a scientific explanation for the antimicrobial applications of Cu-containing stainless steel. The surfaces with different antibacterial abilities could be used as hygienic surfaces in healthcare-associated settings according to the diverse requirement of bactericidal activities.

  12. Surface nanocrystallization of stainless steel for reduced biofilm adherence

    NASA Astrophysics Data System (ADS)

    Yu, Bin; Davis, Elisabeth M.; Hodges, Robert S.; Irvin, Randall T.; Li, D. Y.

    2008-08-01

    Stainless steel is one of the most common metallic biomedical materials. For medical applications, its resistance to the adherence of biofilms is of importance to the elimination or minimization of bacterial infections. In this study, we demonstrate the effectiveness of a process combining surface nanocrystallization and thermal oxidation (or a recovery heat treatment in air) for reducing the biofilm's adherence to stainless steel. During this treatment, a target surface was sandblasted and the resultant dislocation cells in the surface layer were turned into nanosized grains by a subsequent recovery treatment in air. This process generated a more protective oxide film that blocked the electron exchange or reduced the surface activity more effectively. As a result, the biofilm's adherence to the treated surface was markedly minimized. A synthetic peptide was utilized as a substitute of biofilms to evaluate the adhesion between a treated steel surface and biofilms using an atomic force microscope (AFM) through measuring the adhesive force between the target surface and a peptide-coated AFM tip. It was shown that the adhesive force decreased with a decrease in the grain size of the steel. The corresponding surface electron work function (EWF) of the steel was also measured, which showed a trend of variation in EWF with the grain size, consistent with corresponding changes in the adhesive force.

  13. Mechanical properties and TEM examination of RAFM steels irradiated up to 70 dpa in BOR-60

    NASA Astrophysics Data System (ADS)

    Gaganidze, E.; Petersen, C.; Materna-Morris, E.; Dethloff, C.; Weiß, O. J.; Aktaa, J.; Povstyanko, A.; Fedoseev, A.; Makarov, O.; Prokhorov, V.

    2011-10-01

    Mechanical properties of Reduced Activation Ferritic/Martensitic (RAFM) steels were studied after irradiation in BOR-60 reactor to a neutron displacement damage of 70 dpa at 330-340 °C. Yield stress and Ductile-to-Brittle-Transition-Temperature of EUROFER97 indicate saturation of hardening and embrittlement. The phenomenological models for description of microstructure evolution and resulting irradiation hardening and embrittlement are discussed. The evolution of yield stress with dose is qualitatively understood within a Whapham and Makin model. Dislocation loops examined in TEM are considered a main source for low-temperature irradiation hardening. The analysis of the fatigue data in terms of the inelastic strain reveals comparable fatigue behaviour both for unirradiated and irradiated conditions, which can be described by a common Manson-Coffin relation. The study of helium effects in B-doped model steels indicated progressive material embrittlement with helium content. Post-irradiation annealing of RAFM steels yielded substantial recovery of mechanical properties.

  14. Size-dependent characteristics of ultra-fine oxygen-enriched nanoparticles in austenitic steels

    NASA Astrophysics Data System (ADS)

    Miao, Yinbin; Mo, Kun; Zhou, Zhangjian; Liu, Xiang; Lan, Kuan-Che; Zhang, Guangming; Miller, Michael K.; Powers, Kathy A.; Stubbins, James F.

    2016-11-01

    Here, a coordinated investigation of the elemental composition and morphology of ultra-fine-scale nanoparticles as a function of size within a variety of austenitic oxide dispersion-strengthened (ODS) steels is reported. Atom probe tomography was utilized to evaluate the elemental composition of these nanoparticles. Meanwhile, the crystal structures and orientation relationships were determined by high-resolution transmission electron microscopy. The nanoparticles with sufficient size (>4 nm) to maintain a Y2Ti2-xO7-2x stoichiometry were found to have a pyrochlore structure, whereas smaller YxTiyOz nanoparticles lacked a well-defined structure. The size-dependent characteristics of the nanoparticles in austenitic ODS steels differ from those in ferritic/martensitic ODS steels.

  15. Tensile properties of CLAM steel irradiated up to 20.1 dpa in STIP-V

    NASA Astrophysics Data System (ADS)

    Ge, Hongen; Peng, Lei; Dai, Yong; Huang, Qunying; Ye, Minyou

    2016-01-01

    Specimens of China low activation martensitic steel (CLAM) were irradiated in the fifth experiment of SINQ Target Irradiation Program (STIP-V) up to 20.1 dpa/1499 appm He/440 °C. Tensile tests were performed at room temperature (R.T) and irradiation temperatures (Tirr) in the range of 25-450 °C. The tensile results demonstrated strong effect of irradiation dose and irradiation temperature on hardening and embrittlement. With Tirr below ˜314 °C, CLAM steel specimens tested at R.T and Tirr showed similar evolution trend with irradiation dose, compared to other reduced activation ferritic/martensitic (RAFM) steels in similar irradiation conditions. At higher Tirr above ˜314 °C, it is interesting that the hardening effect decreases and the ductility seems to recover, probably due to a strong effect of high irradiation temperature.

  16. Investigation of the sensitivity to EAC of steel T91 in contact with liquid LBE

    NASA Astrophysics Data System (ADS)

    Di Gabriele, F.; Doubková, A.; Hojná, A.

    2008-06-01

    The ferritic-martensitic steel T91 is one of the most promising material for application in the generation IV type reactors. However, there are critical issues, such as the susceptibility to damage of the steel in contact with the heavy liquid metals and their effect on the mechanical properties of structural materials. In this context, it was initiated a study of the boundary conditions, necessary to ascertain the sensitivity of the T91 to environmentally assisted cracking when loaded in contact with the liquid lead-bismuth eutectic. A series of tensile tests were carried out in a cell where the specimens were immersed in static LBE. Results showed that at high temperature the steel in contact with the liquid metal had a slight decrease of yield and UTS value and a marked increase in the elongation to rupture. However, at low temperature the elongation to rupture and the reduction of area decreased, indicating the sensitivity to EAC.

  17. Intrinsic adhesion force of lubricants to steel surface.

    PubMed

    Lee, Jonghwi

    2004-09-01

    The intrinsic adhesion forces of lubricants and other pharmaceutical materials to a steel surface were quantitatively compared using Atomic Force Microscopy (AFM). A steel sphere was attached to the tip of an AFM cantilever, and its adhesion forces to the substrate surfaces of magnesium stearate, sodium stearyl fumarate, lactose, 4-acetamidophenol, and naproxen were measured. Surface roughness varied by an order of magnitude among the materials. However, the results clearly showed that the two lubricants had about half the intrinsic adhesion force as lactose, 4-acetamidophenol, and naproxen. Differences in the intrinsic adhesion forces of the two lubricants were insignificant. The lubricant molecules were unable to cover the steel surface during AFM measurements. Intrinsic adhesion force can slightly be modified by surface treatment and compaction, and its tip-to-tip variation was not greater than its difference between lubricants and other pharmaceutical particles. This study provides a quantitative fundamental basis for understanding adhesion related issues.

  18. Steel surface in-line inspection using machine vision

    NASA Astrophysics Data System (ADS)

    Liu, Hsiao-Wei; Lan, Yu-Ying; Lee, Han-Wen; Liu, Ding-Kun

    2016-07-01

    A roll of steel might have various defects of scratch, stains, and chisel mark after slitting process. However, the traditional steel surface inspection method is via the human inspection that not only takes amount of time but also causes inconsistent inspection consequences. As a result, this paper proposed an in-line visual inspection hardware and software system. The hardware is composed of upper and lower optical module. The defect inspection algorithm includes automatic region of interesting (ROI) searching and defect detection by using Sobel method. Experimentations revealed that the successful detection rate is up to 80% and the inspection speed of per image with 3K in width and 1K in length is less than 80 milliseconds. The contribution is that the proposed method can provide suitable inspection results of the steel surface defect and meet the steel industry demands.

  19. Surface treatment and corrosion behaviour of austenitic stainless steel biomaterial

    NASA Astrophysics Data System (ADS)

    Oravcová, M.; Palček, P.; Zatkalíková, V.; Tański, T.; Król, M.

    2017-02-01

    In this article results from corrosion behaviour of austenitic stainless steel AISI 316L after different surface treatments are published. “As received” surface and surface after grinding resulted in lower resistance to pitting corrosion in physiological solution than electrochemically polished in H3PO4+H2SO4+H2O. Electropolishing also improved the surface roughness in comparison with the “as received” surface. Deposition of Al2O3 nanometric ALD coating improves the corrosion resistance of stainless steel in chloride-containing environment by shifting the breakdown potential toward more positive values. This oxide coating not only improves the corrosion resistance but it also affects the wettability of the surface, resulting in hydrophobic surface.

  20. Work of adhesion of dairy products on stainless steel surface

    PubMed Central

    Bernardes, Patrícia Campos; Araújo, Emiliane Andrade; dos Santos Pires, Ana Clarissa; Queiroz Fialho Júnior, José Felício; Lelis, Carini Aparecida; de Andrade, Nélio José

    2012-01-01

    The adhesion of the solids presents in food can difficult the process of surface cleaning and promotes the bacterial adhesion process and can trigger health problems. In our study, we used UHT whole milk, chocolate based milk and infant formula to evaluate the adhesion of Enterobacter sakazakii on stainless steel coupons, and we determine the work of adhesion by measuring the contact angle as well as measured the interfacial tension of the samples. In addition we evaluated the hydrophobicity of stainless steel after pre-conditioning with milk samples mentioned. E. sakazakii was able to adhere to stainless steel in large numbers in the presence of dairy products. The chocolate based milk obtained the lower contact angle with stainless steel surface, higher interfacial tension and consequently higher adhesion work. It was verified a tendency of decreasing the interfacial tension as a function of the increasing of protein content. The preconditioning of the stainless steel coupons with milk samples changed the hydrophobic characteristics of the surfaces and became them hydrophilic. Therefore, variations in the composition of the milk products affect parameters important that can influence the procedure of hygiene in surface used in food industry. PMID:24031951

  1. Designing high-temperature steels via surface science and thermodynamics

    NASA Astrophysics Data System (ADS)

    Gross, Cameron T.; Jiang, Zilin; Mathai, Allan; Chung, Yip-Wah

    2016-06-01

    Electricity in many countries such as the US and China is produced by burning fossil fuels in steam-turbine-driven power plants. The efficiency of these power plants can be improved by increasing the operating temperature of the steam generator. In this work, we adopted a combined surface science and computational thermodynamics approach to the design of high-temperature, corrosion-resistant steels for this application. The result is a low-carbon ferritic steel with nanosized transition metal monocarbide precipitates that are thermally stable, as verified by atom probe tomography. High-temperature Vickers hardness measurements demonstrated that these steels maintain their strength for extended periods at 700 °C. We hypothesize that the improved strength of these steels is derived from the semi-coherent interfaces of these thermally stable, nanosized precipitates exerting drag forces on impinging dislocations, thus maintaining strength at elevated temperatures.

  2. Studies on oxidation and deuterium permeation behavior of a low temperature α-Al2O3-forming Fesbnd Crsbnd Al ferritic steel

    NASA Astrophysics Data System (ADS)

    Xu, Yu-Ping; Zhao, Si-Xiang; Liu, Feng; Li, Xiao-Chun; Zhao, Ming-Zhong; Wang, Jing; Lu, Tao; Hong, Suk-Ho; Zhou, Hai-Shan; Luo, Guang-Nan

    2016-08-01

    To evaluate the capability of Fesbnd Crsbnd Al ferritic steels as tritium permeation barrier in fusion systems, the oxidation behavior together with the permeation behavior of a Fesbnd Crsbnd Al steel was investigated. Gas driven permeation experiments were performed. The permeability of the oxidized Fesbnd Crsbnd Al steel was obtained and a reduced activation ferritic/martensitic steel CLF-1 was used as a comparison. In order to characterize the oxide layer, SEM, XPS, TEM, HRTEM were used. Al2O3 was detected in the oxide film by XPS, and HRTEM showed that Al2O3 in the α phase was found. The formation of α-Al2O3 layer at a relatively low temperature may result from the formation of Cr2O3 nuclei.

  3. Long-term microstructural stability of oxide-dispersion strengthened Eurofer steel annealed at 800 °C

    NASA Astrophysics Data System (ADS)

    Zilnyk, K. D.; Sandim, H. R. Z.; Bolmaro, R. E.; Lindau, R.; Möslang, A.; Kostka, A.; Raabe, D.

    2014-05-01

    Oxide-dispersion strengthened ferritic martensitic steels such as ODS-Eurofer grade are good candidates for structural applications in future fusion power reactors. Long-term annealing treatments in vacuum were carried out in cold-rolled samples (80% reduction in thickness) from 1 h up to 4320 h (6 months) at 800 °C, i.e. the maximum temperature in the ferritic phase field, to follow its softening behavior. The microstructural stability of this steel was mapped using several characterization techniques including scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, Vickers microhardness testing, X-ray diffraction texture measurements, low-temperature electrical resistivity, and magnetic coercive field measurements. ODS-Eurofer steel displays good microstructural stability. Discontinuous recrystallization occurs at the early stages of annealing resulting in a low volume fraction of recrystallized grains. Extended recovery is the predominant softening mechanism at this temperature for longer times.

  4. Effects of hydrogen isotopes in the irradiation damage of CLAM steel

    NASA Astrophysics Data System (ADS)

    Zhao, M. Z.; Liu, P. P.; Zhu, Y. M.; Wan, F. R.; He, Z. B.; Zhan, Q.

    2015-11-01

    The isotope effect of hydrogen in irradiation damage plays an important role in the development of reduced activation Ferritic/Martensitic steels in nuclear reactors. The evolutions of microstructures and mechanical properties of China low active martensitic (CLAM) steel subjected to hydrogen and deuterium ions irradiation are studied comparatively. Under the same irradiation conditions, larger size and smaller density of dislocation loops are generated by deuterium ion than by hydrogen ion. Irradiation hardening occurs under the ion irradiation and the hardening induced by hydrogen ion is higher than by deuterium ion. Moreover, the coarsening of M23C6 precipitates is observed, which can be explained by the solute drag mechanisms. It turns out that the coarsening induced by deuterium ion irradiation is more distinct than by hydrogen ion irradiation. No distinct variations for the compositions of M23C6 precipitates are found by a large number of statistical data after hydrogen isotopes irradiation.

  5. Oxide dispersion strengthened ferritic steels: a basic research joint program in France

    NASA Astrophysics Data System (ADS)

    Boutard, J.-L.; Badjeck, V.; Barguet, L.; Barouh, C.; Bhattacharya, A.; Colignon, Y.; Hatzoglou, C.; Loyer-Prost, M.; Rouffié, A. L.; Sallez, N.; Salmon-Legagneur, H.; Schuler, T.

    2014-12-01

    AREVA, CEA, CNRS, EDF and Mécachrome are funding a joint program of basic research on Oxide Dispersion Strengthened Steels (ODISSEE), in support to the development of oxide dispersion strengthened 9-14% Cr ferritic-martensitic steels for the fuel element cladding of future Sodium-cooled fast neutron reactors. The selected objectives and the results obtained so far will be presented concerning (i) physical-chemical characterisation of the nano-clusters as a function of ball-milling process, metallurgical conditions and irradiation, (ii) meso-scale understanding of failure mechanisms under dynamic loading and creep, and, (iii) kinetic modelling of nano-clusters nucleation and α/α‧ unmixing.

  6. Austenite Stability Effects on Tensile Behavior of Manganese-Enriched-Austenite Transformation-Induced Plasticity Steel

    NASA Astrophysics Data System (ADS)

    Gibbs, P. J.; de Moor, E.; Merwin, M. J.; Clausen, B.; Speer, J. G.; Matlock, D. K.

    2011-12-01

    Manganese enrichment of austenite during prolonged intercritical annealing was used to produce a family of transformation-induced plasticity (TRIP) steels with varying retained austenite contents. Cold-rolled 0.1C-7.1Mn steel was annealed at incremental temperatures between 848 K and 948 K (575 °C and 675 °C) for 1 week to enrich austenite in manganese. The resulting microstructures are comprised of varying fractions of intercritical ferrite, martensite, and retained austenite. Tensile behavior is dependent on annealing temperature and ranged from a low strain-hardening "flat" curve to high strength and ductility conditions that display positive strain hardening over a range of strain levels. The mechanical stability of austenite was measured using in-situ neutron diffraction and was shown to depend significantly on annealing temperature. Variations in austenite stability between annealing conditions help explain the observed strain hardening behaviors.

  7. Effect of tempering on the microstructure, electrical, and magnetic properties of Eurofer-97 steel

    NASA Astrophysics Data System (ADS)

    Sandim, M. J. R.; Farrão, F. U.; Oliveira, V. B.; Bredda, E. H.; Santos, A. D.; dos Santos, C. A. M.; Sandim, H. R. Z.

    2015-06-01

    Reduced-activation ferritic-martensitic Eurofer-97 steel is a potential candidate for structural application in future nuclear fusion reactors. Samples of Eurofer-97 steel were cold rolled to 80% reduction in thickness, austenitized at 1050 and 1150 °C for 30 min and tempered at several temperatures up to 800 °C for 2 h each. The microstructural characterization of the samples was performed using Vickers microhardness testing and electron backscatter diffraction (EBSD). Electrical resistivity and coercive field measurements were also performed to follow microstructural changes during isothermal tempering. Results were discussed with focus on the precipitation of MX and M23C6 carbides and related changes in these properties.

  8. Excimer surface treatment to enhance bonding in coated steels

    NASA Astrophysics Data System (ADS)

    Mueller, Robert E.; Olfert, M.; Duley, Walter W.; North, T.; Hood, J.; Sakai, D.

    1996-04-01

    Zinc coated sheet steel in the form of temper rolled galvanize and galvanneal are used extensively in the automotive industry. Through a process of excimer laser surface treatment, we have succeeded in significantly enhancing the adhesion characteristics of these coated steels. The laser treatment is performed by scanning focused excimer laser radiation in a raster pattern over the surface to be bonded. Adhesion tests have been carried out in the form of T peel tests, using either a hot melt nylon resin or an epoxy as the adhesive. An increase in bond strength was observed over a substantial range of surface treatment conditions. The largest improvement observed was more than a factor of three greater than for untreated surfaces. With the improved surface condition, the bond strength became limited by the cohesive strength of the adhesive. The physical structure and chemical composition of the parent and excimer treated surfaces have been examined using scanning electron microscopy and X-ray photoelectron spectroscopy to determine the nature and extent of the changes caused by the surface treatment. The effects of the observed changes on the bonding performance will be discussed. Surfaces have been processed under an inert atmosphere to isolate the effects of physical surface modification and surface oxidation. An attempt will be made to correlate the surface changes with the bonding characteristics and thereby indicate which changes are most beneficial. The ultimate goal is to optimize the surface condition for bonding and maximize the process rate.

  9. Role of Steel Object Surface Condition on Behavior During Deformation

    NASA Astrophysics Data System (ADS)

    D'yachenko, S. S.; Ponomarenko, I. V.; Dub, S. N.

    2015-09-01

    Comparative analysis is provided for specimen mechanical properties of steels 18KhGT and 20Kh with tensile testing in relation to surface treatment: grinding, polishing, nitriding, carburizing, and ion-plasma treatment. It is shown that surface condition has a considerable effect on specimen behavior during deformation. It is established that the most favorable effect applies to ion bombardment with low-energy ions recommended as an effective method for improving component structural strength.

  10. Laser surface modification of 316L stainless steel.

    PubMed

    Balla, Vamsi Krishna; Dey, Sangeetha; Muthuchamy, Adiyen A; Janaki Ram, G D; Das, Mitun; Bandyopadhyay, Amit

    2017-02-28

    Medical grade 316L stainless steel was laser surface melted (LSM) using continuous wave Nd-YAG laser in argon atmosphere at 1 and 5 mm/s. The treated surfaces were characterized using electron backscatter diffraction to study the influence of top surface crystallographic orientation and type of grain boundaries on corrosion resistance, wettability, and biocompatibility. The laser scan velocity was found to have a marginal influence on the surface roughness and the type of grain boundaries. However, the crystal orientation density was found to be relatively high in 1 mm/s samples. The LSM samples showed a higher concentration of {101} and {123} planes parallel to the sample surface as well as a higher fraction of low-angle grain boundaries. The LSM samples were found to exhibit better surface wettability and enhanced the viability and proliferation of human fetal osteoblast cells in vitro when compared to the untreated samples. Further, the corrosion protection efficiency of 316L stainless steel was improved up to 70% by LSM in as-processed condition. The increased concentration of {101} and {123} planes on surfaces of LSM samples increases their surface energy, which is believed to be responsible for the improved in vitro cell proliferation. Further, the increased lattice spacing of these planes and high concentration of low-energy grain boundaries in LSM samples would have contributed to the better in vitro corrosion resistance than untreated 316L stainless steel. Our results indicate that LSM can be a potential treatment option for 316L stainless steel-based biomedical devices to improve biocompatibility and corrosion resistance. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017.

  11. SQA(TM): Surface Quality Assured Steel Bar Program

    SciTech Connect

    Chang, Tzyy-Shuh; Shi, Jianjun; Zhou, Shiyu

    2009-03-03

    OG Technologies, Inc. (OGT) has led this SQA (Surface Quality Assured Steel Bar) program to solve the major surface quality problems plaguing the US special quality steel bars and rods industry and their customers, based on crosscutting sensors and controls technologies. Surface defects in steel formed in a hot rolling process are one of the most common quality issues faced by the American steel industry, accounting for roughly 50% of the rejects or 2.5% of the total shipment. Unlike other problems such as the mechanical properties of the steel product, most surface defects are sporadic and cannot be addressed based on sampling techniques. This issue hurts the rolling industry and their customers in their process efficiency and operational costs. The goal of this program is to develop and demonstrate an SQA prototype, with synergy of HotEye® and other innovations, that enables effective rolling process control and efficient quality control. HotEye®, OGT’s invention, delivers high definition images of workpieces at or exceeding 1,450°C while the workpieces travel at 100 m/s. The elimination of surface defect rejects will be achieved through the integration of imaging-based quality assessment, advanced signal processing, predictive process controls and the integration with other quality control tools. The SQA program team, composed of entities capable of and experienced in (1) research, (2) technology manufacturing, (3) technology sales and marketing, and (4) technology end users, is very strong. There were 5 core participants: OGT, Georgia Institute of Technology (GIT), University of Wisconsin (UW), Charter Steel (Charter) and ArcelorMittal Indiana Harbor (Inland). OGT served as the project coordinator. OGT participated in both research and commercialization. GIT and UW provided significant technical inputs to this SQA project. The steel mills provided access to their rolling lines for data collection, design of experiments, host of technology test and

  12. Fabrication of superhydrophobic and lyophobic slippery surface on steel substrate

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Xiong, Dangsheng; Pan, Sai; Deng, Yaling; Shi, Yan

    2016-11-01

    Superhydrophobic/oleophilic coating was prepared on steel via wet chemical etching, and followed by surface modification. Surface grafting was manifested to be realized mainly on the oxidized area. Slippery liquid infused porous surface(s) (SLIPS) was prepared by infusing perfluorinated lubricant into the prepared superhydrophobic coating, to repel water, coffee, kerosene, and even hexane, suggesting a transition from superoleophilicity to lyophobicity. Furthermore, the lyohobicity was accessible only when the substrate is fluorinated. Moreover, the kinematic viscosity was demonstrated to be negatively correlated to the traveling speed of the liquids on the SLIPS.

  13. Must we use ferritic steel in TBM?

    SciTech Connect

    Salavy, Jean-Francois; Boccaccini, Lorenzo V.; Chaudhuri, Paritosh; Cho, Seungyon; Enoeda, Mikio; Giancarli, Luciano; Kurtz, Richard J.; Luo, Tian Y.; Rao, K. Bhanu Sankara; Wong, Clement

    2010-12-13

    Mock-ups of DEMO breeding blankets, called Test Blanket Modules (TBMs), inserted and tested in ITER in dedicated equatorial ports directly facing the plasma, are expected to provide the first experimental answers on the necessary performance of the corresponding DEMO breeding blankets. Several DEMO breeding blanket designs have been studied and assessed in the last 20 years. At present, after considering various coolant and breeder combinations, all the TBM concepts proposed by the seven ITER Parties use Reduced-Activation Ferritic/Martensitic (RAFM) steel as the structural material. In order to perform valuable tests in ITER, the TBMs are expected to use the same structural material as corresponding DEMO blankets. However, due to the fact that this family of steels is ferromagnetic, their presence in the ITER vacuum vessel will create perturbations of the ITER magnetic fields that could reduce the quality of the plasma confinement during H-mode. As a consequence, a legitimate question has been raised on the necessity of using RAFM steel for TBMs structural material in ITER. By giving a short description of the main TBM testing objectives in ITER and assessing the consequences of not using such a material, this paper gives a comprehensive answer to this question. According to the working group author of the study, the use of RAFM steel as structural material for TBM is judged mandatory.

  14. Influence of Thermal Aging on the Microstructure and Mechanical Behavior of Dual-Phase, Precipitation-Hardened, Powder Metallurgy Stainless Steels

    NASA Astrophysics Data System (ADS)

    Stewart, J. L.; Williams, J. J.; Chawla, N.

    2012-01-01

    The effects of thermal aging on the microstructure and mechanical behavior of dual-phase, precipitation-hardened, powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels, and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 811 K (538 °C) in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite nanohardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties.

  15. Interaction of cobalt with a stainless steel oxide surface

    SciTech Connect

    Taylor, J.B. )

    1991-01-01

    The deposition of radioactive cobalt ions from aqueous solutions in the pH range from 1 to 12 onto the internal surface of a stainless steel vessel or pipework can lead to the buildup of tenacious surface activity. For liquid streams of low specific activity (measured in becquerels per millilitre), the surface activity buildup may create a more dominant gamma radiation field than the activity suspended in the liquid. Failure to adequately predict this buildup for an operational nuclear plant can lead to an underestimate of potential gamma dose rates. This may lead to an economic penalty if additional shielding or other protective measures are necessary following plant operation. A theoretical method of determining the cobalt mass/activity deposition from aqueous liquor onto stainless steel is outlined in this paper. A validation of the method is given, and the limits of its application are discussed.

  16. Determination of Surface Stress Distributions in Steel Using Laser-Generated Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Shi; Yifei; Ni; Chenyin; Shen; Zhonghua; Ni; Xiaowu; Lu; Jian

    2008-05-01

    High frequency surface acoustic waves (SAWs) are excited by a pulsed laser and detected by a specially designed poly(vinylidene fluoride) (PVDF) transducer to investigate surface stress distribution. Two kinds of stressed surfaces are examined experimentally. One is a steel plate elastically deformed under simple bending forces, where the surface stress varies slowly. The other is a welded steel plate for which the surface stress varies very rapidly within a small area near the welding seam. Applying a new signal processing method developed from correlation technique, the velocity distribution of the SAWs, which reflects the stress distribution, is obtained in these two samples with high resolution.

  17. Surface interactions of cesium and boric acid with stainless steel

    SciTech Connect

    Grossman-Canfield, N.

    1995-08-01

    In this report, the effects of cesium hydroxide and boric acid on oxidized stainless steel surfaces at high temperatures and near one atmosphere of pressure are investigated. This is the first experimental investigation of this chemical system. The experimental investigations were performed using a mass spectrometer and a mass electrobalance. Surfaces from the different experiments were examined using a scanning electron microscope to identify the presence of deposited species, and electron spectroscopy for chemical analysis to identify the species deposited on the surface. A better understanding of the equilibrium thermodynamics, the kinetics of the steam-accelerated volatilizations, and the release kinetics are gained by these experiments. The release rate is characterized by bulk vaporization/gas-phase mass transfer data. The analysis couples vaporization, deposition, and desorption of the compounds formed by cesium hydroxide and boric acid under conditions similar to what is expected during certain nuclear reactor accidents. This study shows that cesium deposits on an oxidized stainless steel surface at temperatures between 1000 and 1200 Kelvin. Cesium also deposits on stainless steel surfaces coated with boric oxide in the same temperature ranges. The mechanism for cesium deposition onto the oxide layer was found to involve the chemical reaction between cesium and chromate. Some revaporization in the cesium hydroxide-boric acid system was observed. It has been found that under the conditions given, boric acid will react with cesium hydroxide to form cesium metaborate. A model is proposed for this chemical reaction.

  18. Surface modification of SKD-61 steel by ion implantation technique

    SciTech Connect

    Wen, F. L.; Lo, Y.-L.; Yu, Y.-C.

    2007-07-15

    The purpose of this study is to investigate how ion implantation affects the surface characteristics and nitrogenizing depth of the thin film by the use of a NEC 9SDH-2 3 MV Pelletron accelerator that implants nitrogen ions into SKD-61 tool steels for surface modification. Nitrogen ions were implanted into the surface layer of materials so that the hardness of modified films could be improved. Also, the nitride film stripping problems of the traditional nitrogenizing treatment could be overcome by a new approach in surface process engineering. As nitrogen ions with high velocity impacted on the surface of the substrate, the ions were absorbed and accumulated on the surface of the substrate. The experiments were performed with two energies (i.e., 1 and 2 MeV) and different doses (i.e., 2.5x10{sup 15}, 7.5x10{sup 15}, and 1.5x10{sup 16} ions/cm{sup 2}). Nitrogen ions were incorporated into the interface and then diffused through the metal to form a nitride layer. Analysis tools included the calculation of stopping and range of ions in matter (SRIM), the detection of a secondary ion mass spectrometry (SIMS), and nanoindentation testing. Through the depth analysis of SIMS, the effects of the ion-implanted SKD-61 steels after heating at 550 deg. C in a vacuum furnace were examined. The nanoindenting results indicate the variation of hardness of SKD-61 steels with the various ion doses. It reaches two to three times the original hardness of SKD-61 steels.

  19. Technology of Strengthening Steel Details by Surfacing Composite Coatings

    NASA Astrophysics Data System (ADS)

    Burov, V. G.; Bataev, A. A.; Rakhimyanov, Kh M.; Mul, D. O.

    2016-04-01

    The article considers the problem of forming wear resistant meal ceramic coatings on steel surfaces using the results of our own investigations and the analysis of achievements made in the country and abroad. Increasing the wear resistance of surface layers of steel details is achieved by surfacing composite coatings with carbides or borides of metals as disperse particles in the strengthening phase. The use of surfacing on wearing machine details and mechanisms has a history of more than 100 years. But still engineering investigations in this field are being conducted up to now. The use of heating sources which provide a high density of power allows ensuring temperature and time conditions of surfacing under which composites with peculiar service and functional properties are formed. High concentration of energy in the zone of melt, which is created from powder mixtures and the hardened surface layer, allows producing the transition zone between the main material and surfaced coating. Surfacing by the electron beam directed from vacuum to the atmosphere is of considerable technological advantages. They give the possibility of strengthening surface layers of large-sized details by surfacing powder mixtures without their preliminary compacting. A modified layer of the main metal with ceramic particles distributed in it is created as a result of heating surfaced powders and the detail surface layer by the electron beam. Technology of surfacing allows using powders of refractory metals and graphite in the composition of powder mixtures. They interact with one another and form the particles of the hardening phase of the composition coating. The chemical composition of the main and surfaced materials is considered to be the main factor which determines the character of metallurgical processes in local zones of melt as well as the structure and properties of surfaced composition.

  20. Effect of Surface Treatment on the Surface Characteristics of AISI 316L Stainless Steel

    NASA Technical Reports Server (NTRS)

    Trigwell, Steve; Selvaduray, Guna

    2005-01-01

    The ability of 316L stainless steel to maintain biocompatibility, which is dependent upon the surface characteristics, is critical to its effectiveness as an implant material. The surfaces of mechanically polished (MP), electropolished (EP) and plasma treated 316L stainless steel coupons were characterized by X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) for chemical composition, Atomic Force Microscopy for surface roughness, and contact angle measurements for critical surface tension. All surfaces had a Ni concentration that was significantly lower than the bulk concentration of -43%. The Cr content of the surface was increased significantly by electropolishing. The surface roughness was also improved significantly by electropolishing. Plasma treatment had the reverse effect - the surface Cr content was decreased. It was also found that the Cr and Fe in the surface exist in both the oxide and hydroxide states, with the ratios varying according to surface treatment.

  1. Atomic diffusion in laser surface modified AISI H13 steel

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2013-07-01

    This paper presents a laser surface modification process of AISI H13 steel using 0.09 and 0.4 mm of laser spot sizes with an aim to increase surface hardness and investigate elements diffusion in laser modified surface. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, pulse repetition frequency (PRF), and overlap percentage. The hardness properties were tested at 981 mN force. Metallographic study and energy dispersive X-ray spectroscopy (EDXS) were performed to observe presence of elements and their distribution in the sample surface. Maximum hardness achieved in the modified surface was 1017 HV0.1. Change of elements composition in the modified layer region was detected in the laser modified samples. Diffusion possibly occurred for C, Cr, Cu, Ni, and S elements. The potential found for increase in surface hardness represents an important method to sustain tooling life. The EDXS findings signify understanding of processing parameters effect on the modified surface composition.

  2. Dynamic recrystallization in friction surfaced austenitic stainless steel coatings

    SciTech Connect

    Puli, Ramesh Janaki Ram, G.D.

    2012-12-15

    Friction surfacing involves complex thermo-mechanical phenomena. In this study, the nature of dynamic recrystallization in friction surfaced austenitic stainless steel AISI 316L coatings was investigated using electron backscattered diffraction and transmission electron microscopy. The results show that the alloy 316L undergoes discontinuous dynamic recrystallization under conditions of moderate Zener-Hollomon parameter during friction surfacing. - Highlights: Black-Right-Pointing-Pointer Dynamic recrystallization in alloy 316L friction surfaced coatings is examined. Black-Right-Pointing-Pointer Friction surfacing leads to discontinuous dynamic recrystallization in alloy 316L. Black-Right-Pointing-Pointer Strain rates in friction surfacing exceed 400 s{sup -1}. Black-Right-Pointing-Pointer Estimated grain size matches well with experimental observations in 316L coatings.

  3. Iodine susceptibility of pseudomonads grown attached to stainless steel surfaces

    NASA Technical Reports Server (NTRS)

    Pyle, B. H.; McFeters, G. A.

    1990-01-01

    Pseudomonads were adapted to grow in phosphate-buffered water and on stainless steel surfaces to study the iodine sensitivity of attached and planktonic cells. Cultures adapted to low nutrient growth were incubated at room temperature in a circulating reactor system with stainless steel coupons to allow biofilm formation on the metal surfaces. In some experiments, the reactor was partially emptied and refilled with buffer at each sampling time to simulate a "fill-and-draw" water system. Biofilms of attached bacteria, resuspended biofilm bacteria, and reactor suspension, were exposed to 1 mg l-1 iodine for 2 min. Attached bacterial populations which established on coupons within 3 to 5 days displayed a significant increase in resistance to iodine. Increased resistance was also observed for resuspended cells from the biofilm and planktonic bacteria in the system suspension. Generally, intact biofilms and resuspended biofilm cells were most resistant, followed by planktonic bacteria and phosphate buffer cultures. Thus, biofilm formation on stainless steel surfaces within water systems can result in significantly increased disinfection resistance of commonly-occurring water-borne bacteria that may enhance their ability to colonise water treatment and distribution systems.

  4. Laser beam surface melting of high alloy austenitic stainless steel

    SciTech Connect

    Woollin, P.

    1996-12-31

    The welding of high alloy austenitic stainless steels is generally accompanied by a substantial reduction in pitting corrosion resistance relative to the parent, due to microsegregation of Mo and Cr. This prevents the exploitation of the full potential of these steels. Processing to achieve remelting and rapid solidification offers a means of reducing microsegregation levels and improving corrosion resistance. Surface melting of parent UNS S31254 steel by laser beam has been demonstrated as a successful means of producing fine, as-solidified structures with pitting resistance similar to that of the parent, provided that an appropriate minimum beam travel speed is exceeded. The use of N{sub 2} laser trail gas increased the pitting resistance of the surface melted layer. Application of the technique to gas tungsten arc (GTA) melt runs has shown the ability to raise the pitting resistance significantly. Indeed, the use of optimized beam conditions, N{sub 2} trail gas and appropriate surface preparation prior to laser treatment increased the pitting resistance of GTA melt runs to a level approaching that of the parent material.

  5. Bulk Nanostructured FCC Steels With Enhanced Radiation Tolerance

    SciTech Connect

    Zhang, Xinghang; Hartwig, K. Ted; Allen, Todd; Yang, Yong

    2012-10-27

    The objective of this project is to increase radiation tolerance in austenitic steels through optimization of grain size and grain boundary (GB) characteristics. The focus will be on nanocrystalline austenitic Fe-Cr-Ni alloys with an fcc crystal structure. The long-term goal is to design and develop bulk nanostructured austenitic steels with enhanced void swelling resistance and substantial ductility, and to enhance their creep resistance at elevated temperatures via GB engineering. The combination of grain refinement and grain boundary engineering approaches allows us to tailor the material strength, ductility, and resistance to swelling by 1) changing the sink strength for point defects, 2) by increasing the nucleation barriers for bubble formation at GBs, and 3) by changing the precipitate distributions at boundaries. Compared to ferritic/martensitic steels, austenitic stainless steels (SS) possess good creep and fatigue resistance at elevated temperatures, and better toughness at low temperature. However, a major disadvantage of austenitic SS is that they are vulnerable to significant void swelling in nuclear reactors, especially at the temperatures and doses anticipated in the Advanced Burner Reactor. The lack of resistance to void swelling in austenitic alloys led to the switch to ferritic/martensitic steels as the preferred material for the fast reactor cladding application. Recently a type of austenitic stainless steel, HT-UPS, was developed at ORNL, and is expected to show enhanced void swelling resistance through the trapping of point defects at nanometersized carbides. Reducing the grain size and increasing the fraction of low energy grain boundaries should reduce the available radiation-produced point defects (due to the increased sink area of the grain boundaries), should make bubble nucleation at the boundaries less likely (by reducing the fraction of high-energy boundaries), and improve the strength and ductility under radiation by producing a higher

  6. Adaptive classifier for steel strip surface defects

    NASA Astrophysics Data System (ADS)

    Jiang, Mingming; Li, Guangyao; Xie, Li; Xiao, Mang; Yi, Li

    2017-01-01

    Surface defects detection system has been receiving increased attention as its precision, speed and less cost. One of the most challenges is reacting to accuracy deterioration with time as aged equipment and changed processes. These variables will make a tiny change to the real world model but a big impact on the classification result. In this paper, we propose a new adaptive classifier with a Bayes kernel (BYEC) which update the model with small sample to it adaptive for accuracy deterioration. Firstly, abundant features were introduced to cover lots of information about the defects. Secondly, we constructed a series of SVMs with the random subspace of the features. Then, a Bayes classifier was trained as an evolutionary kernel to fuse the results from base SVMs. Finally, we proposed the method to update the Bayes evolutionary kernel. The proposed algorithm is experimentally compared with different algorithms, experimental results demonstrate that the proposed method can be updated with small sample and fit the changed model well. Robustness, low requirement for samples and adaptive is presented in the experiment.

  7. Effect of irradiation temperature on void swelling of China Low Activation Martensitic steel (CLAM)

    SciTech Connect

    Zhao Fei; Qiao Jiansheng; Huang Yina; Wan Farong Ohnuki, Soumei

    2008-03-15

    CLAM is one composition of a Reduced Activation Ferritic/Martensitic steel (RAFM), which is being studied in a number of institutes and universities in China. The effect of electron-beam irradiation temperature on irradiation swelling of CLAM was investigated by using a 1250 kV High Voltage Electron Microscope (HVEM). In-situ microstructural observations indicated that voids formed at each experimental temperature - 723 K, 773 K and 823 K. The size and number density of voids increased with increasing irradiation dose at each temperature. The results show that CLAM has good swelling resistance. The maximum void swelling was produced at 723 K; the swelling was about 0.3% when the irradiation damage was 13.8 dpa.

  8. Analysis of cavitation on the surface of steel under the ultrasonic cleaning

    NASA Astrophysics Data System (ADS)

    Tsybry, I. K.; Vyalikov, I. L.

    2017-02-01

    The article presents: the results of studies on the effects of cavitation on the surface of steel during processing in a liquid medium; the analysis of changes of the microstructure and the microhardness of steel under the effect of cavitation; the features of hardening and destruction of the surface layers of steel with a structure of granular pearlite and the martensitic steel structure. Comparative analysis of the structural transformations of the surface layers of steels 12H17 and U8 allows us to select the optimum time of ultrasonic treatment for a complete cleaning of the surface without destroying it.

  9. Formation of Surface Corrosion-Resistant Nanocrystalline Structures on Steel.

    PubMed

    Nykyforchyn, Hryhoriy; Kyryliv, Volodymyr; Maksymiv, Olha; Slobodyan, Zvenomyra; Tsyrulnyk, Oleksandr

    2016-12-01

    Engineering materials with nanocrystalline structure could be exploited under simultaneous action of mechanical loading and corrosion environments; therefore, their corrosion resistance is important. Surface nanocrystalline structure was generated on middle carbon steels by severe plastic deformation using the method of mechanical pulse friction treatment. This treatment additionally includes high temperature phase transformation and alloying. Using a complex of the corrosive, electrochemical and physical investigations, it was established that nanocrystalline structures can be characterized by lower or increased corrosion resistance in comparison with the reference material. It is caused by the action of two confronting factors: arising energy level and anticorrosive alloying of the surface layer.

  10. Surface hardening of steel by laser and electron beam. (Latest citations from METADEX). Published Search

    SciTech Connect

    Not Available

    1994-09-01

    The bibliography contains citations concerning electron beam hardening of steels and alloys. Among the materials surface hardened are carbon and alloy steels, aircraft spur gears, nitrocarburized steel, turbine blades, titanium-carbon steel, titanium, and rolling bearings. Effect of transformation plasticity on residual stress fields in laser surface hardening treatment is also examined. (Contains a minimum of 93 citations and includes a subject term index and title list.)

  11. Surface hardening of steel by laser and electron beam. (Latest citations from Metadex). Published Search

    SciTech Connect

    1996-08-01

    The bibliography contains citations concerning electron beam hardening of steels and alloys. Among the materials surface hardened are carbon and alloy steels, aircraft spur gears, nitrocarburized steel, turbine blades, titanium-carbon steel, titanium, and rolling bearings. Effect of transformation plasticity on residual stress fields in laser surface hardening treatment is also examined.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  12. Inhibition efficiency of aminobenzonitrile compounds on steel surface

    NASA Astrophysics Data System (ADS)

    Sığırcık, Gökmen; Tüken, Tunç; Erbil, Mehmet

    2015-01-01

    The aim of this study is to investigate the inhibition efficiency of benzonitriles with functional amine groups in different positions, for mild steel corrosion in 0.5 M HCl solution. For this purpose, electrochemical impedance spectroscopy and potentiodynamic measurements were realized. Besides, these electrochemical analyses were carried out at different temperatures in order to obtain temperature dependency of inhibition efficiency. By using atomic absorption spectroscopy techniques, the amount of iron ions that released to the solution was determined, during immersion time. The surface analysis was also carried out by scanning electron microscopy technique. The results show that all these inhibitors have a good inhibition effect on mild steel in 0.5 M HCl solution, and it depends on the position of amine group.

  13. Surface preparation for non-destructive detection of surface cracks in stainless steel and carbon steel piping

    SciTech Connect

    Funderburg, I.M.

    1996-07-01

    Engineers within the chemical process industries are among other things, charged with the task of determining the reliability of piping and equipment. As part of this evaluation, the surfaces of process equipment and piping are often examined for evidence of stress corrosion cracking (SCC) or other tightly closed surface cracks. Presently there is no consensus as to which is the ``best`` technique for preparing and inspecting carbon steel and stainless steel vessels or piping for surface cracks. The specific concern within industry is that Stress Corrosion Cracking (SCC) might go undetected if the surface preparation closes over such tight cracks. This paper presents results of a study, MTI commissioned to collect additional data, examine the literature, and interview industrial materials engineers, independent inspection specialists, non-destructive examination consultants, and other representatives of industries that have equipment which must be inspected for surface cracks. Discussed are the differing surface preparation techniques used, the use of standards for evaluating the effectiveness of the techniques, and what is felt to be the ``Key Learnings`` from the investigation.

  14. Laser surface modification of stainless steels for cavitation erosion resistance

    NASA Astrophysics Data System (ADS)

    Kwok, Chi Tat

    1999-12-01

    Austenitic stainless steel UNS S31603 (Fe -17.6Cr -11.2Ni -2.5Mo -1.4Mn -0.4Si -0.03C) has higher pitting corrosion resistance but lower cavitation erosion resistance than that of UNS S30400. This is because of its lower tendency for strain induced martensitic transformation and higher stacking fault energy as compared with those of UNS S30400. In order to improve its cavitation erosion resistance, surface modification of S31603 was performed by laser surface melting and laser surface alloying using a 2-kW CW Nd-YAG laser and a 3-kW CW CO2 laser. For laser surface melting, austenitic stainless steel UNS S30400, super duplex stainless steel UNS S32760 and martensitic stainless steel UNS S42000 were also investigated for comparison purpose. For laser surface alloying, alloying materials including various elements (Co, Cr, Ni, Mo, Mn, Si & C), alloys (AlSiFe & NiCrSiB), ceramics (Si3N 4, SiC, Cr3C2, TiC, CrB & Cr2O 3) and alloys-ceramics (Co-WC, Ni-WC, Ni-Al2O3, Ni-Cr2C3) were used to modify the surface of S31603. The alloyed surface was achieved first by flame spraying or pre-placing of the alloy powder on the S31603 surface and then followed by laser surface remelting. The cavitation erosion characteristics of laser surface modified specimens in 3.5% NaCl solution at 23°C were studied by means of a 20-kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 mum. In addition, their pitting corrosion behaviour was evaluated by electrochemical techniques. The microstructures, compositions, phase changes and damage mechanisms under cavitation erosion were investigated by optical microscopy, SEM, EDAX and X-ray diffractometry. Mechanical properties such as microhardness profile were also examined. The cavitation erosion resistance Re (reciprocal of the mean depth of penetration rate) of laser surface melted S31603 was found to be improved by 22% and was attributed to the existence of tensile residual stress. Improvement on the Re of S42000 was found to be 8.5 times

  15. Electric arc surfacing on low carbon steel: Structure and properties

    NASA Astrophysics Data System (ADS)

    Ivanov, Yurii; Gromov, Victor; Kormyshev, Vasilii; Konovalov, Sergey; Kapralov, Evgenii; Semin, Alexander

    2016-11-01

    By the methods of modern materials science, the structure-phase state and microhardness distribution along the cross-section of single and double coatings surfaced on martensite low carbon steel by alloy powder-cored wire were studied. It was established that the increased mechanical properties of surfaced layer are determined by the sub-micro and nanodispersed martensite structure formation, containing iron borides forming the eutectic of lamellar form. The plates of Fe2B are formed mainly in the eutectic of a single-surfaced layer, while FeB is formed in a double-surfaced layer. The existence of bend extinction contours indicating the internal stress fields formation at the boundaries of Fe borides-α-Fe phases were revealed.

  16. Tempering of Mn and Mn-Si-V dual-phase steels

    NASA Astrophysics Data System (ADS)

    Speich, G. R.; Schwoeble, A. J.; Huffman, G. P.

    1983-06-01

    Changes in the yield behavior, strength, and ductility of a Mn and a Mn-Si-V d11Al-phase (ferrite-martensite) steel were investigated after tempering one hour at 200 to 600 °C. The change in yield behavior was complex in both steels with the yield strength first increasing and then decreasing as the tempering temperature was increased. This complex behavior is attributed to a combination of factors including carbon segregation to dislocations, a return of discontinuous yielding, and the relief of resid11Al stresses. In contrast, the tensile strength decreased continuously as the tempering temperature was increased in a manner that could be predicted from the change in hardness of the martensite phase using a simple composite strengthening model. The initial tensile ductility (total elongation) of the Mn-Si-V steel was much greater than that of the Mn steel. However, upon tempering up to 400 °C, the ductility of the Mn-Si-V decreased whereas that of the Mn steel increased. As a result, both steels had similar ductilities after tempering at 400 °C or higher temperatures. These results are attributed to the larger amounts of retained austenite in the Mn-Si-V steel (9 pct) compared to the Mn steel (3 pct) and its contribution to tensile ductility by transforming to martensite during plastic straining. Upon tempering at 400 °C, the retained austenite decomposes to bainite and its contribution to tensile ductility is eliminated.

  17. Elevated-Temperature Ferritic and Martensitic Steels and Their Application to Future Nuclear Reactors

    SciTech Connect

    Klueh, RL

    2005-01-31

    In the 1970s, high-chromium (9-12% Cr) ferritic/martensitic steels became candidates for elevated-temperature applications in the core of fast reactors. Steels developed for conventional power plants, such as Sandvik HT9, a nominally Fe-12Cr-1Mo-0.5W-0.5Ni-0.25V-0.2C steel (composition in wt %), were considered in the United States, Europe, and Japan. Now, a new generation of fission reactors is in the planning stage, and ferritic, bainitic, and martensitic steels are again candidates for in-core and out-of-core applications. Since the 1970s, advances have been made in developing steels with 2-12% Cr for conventional power plants that are significant improvements over steels originally considered. This paper will review the development of the new steels to illustrate the advantages they offer for the new reactor concepts. Elevated-temperature mechanical properties will be emphasized. Effects of alloying additions on long-time thermal exposure with and without stress (creep) will be examined. Information on neutron radiation effects will be discussed as it applies to ferritic and martensitic steels.

  18. Evaluation of Alternate Stainless Steel Surface Passivation Methods

    SciTech Connect

    Clark, Elliot A.

    2005-05-31

    Stainless steel containers were assembled from parts passivated by four commercial vendors using three passivation methods. The performance of these containers in storing hydrogen isotope mixtures was evaluated by monitoring the composition of initially 50% H{sub 2} 50% D{sub 2} gas with time using mass spectroscopy. Commercial passivation by electropolishing appears to result in surfaces that do not catalyze hydrogen isotope exchange. This method of surface passivation shows promise for tritium service, and should be studied further and considered for use. On the other hand, nitric acid passivation and citric acid passivation may not result in surfaces that do not catalyze the isotope exchange reaction H{sub 2} + D{sub 2} {yields} 2HD. These methods should not be considered to replace the proprietary passivation processes of the two current vendors used at the Savannah River Site Tritium Facility.

  19. Surface Modification of Commercial Low-Carbon Steel using Glow Discharge Nitrogen Plasma and its Characterization

    NASA Astrophysics Data System (ADS)

    Srikanth, S.; Saravanan, P.; Joseph, Alphonsa; Ravi, K.

    2013-09-01

    Plasma nitriding under glow discharge nitrogen plasma has been undertaken on laboratory scale for surface engineering of commercial low carbon steels. The treatment has been shown to confer exceptional improvement in surface properties, viz., hardness and corrosion resistance. The results have been discussed in light of microstructural changes occurring on steel surface and its interior as a result of Fickian nitrogen diffusion and correlated with influences of nitriding-temperature and alloying elements (Mn, Nb, and Si) in steel.

  20. PLEPS study of ions implanted RAFM steels

    NASA Astrophysics Data System (ADS)

    Sojak, S.; Slugeň, V.; Egger, W.; Ravelli, L.; Petriska, M.; Veterníková, J.; Stacho, M.; Sabelová, V.

    2014-04-01

    Current nuclear power plants (NPP) require radiation, heat and mechanical resistance of their structural materials with the ability to stay operational during NPP planned lifetime. Radiation damage much higher, than in the current NPP, is expected in new generations of nuclear power plants, such as Generation IV and fusion reactors. Investigation of perspective structural materials for new generations of nuclear power plants is among others focused on study of reduced activation ferritic/martensitic (RAFM) steels. These steels have good characteristics as reduced activation, good resistance to volume swelling, good radiation, and heat resistance. Our experiments were focused on the study of microstructural changes of binary Fe-Cr alloys with different chromium content after irradiation, experimentally simulated by ion implantations. Fe-Cr alloys were examined, by Pulsed Low Energy Positron System (PLEPS) at FRM II reactor in Garching (Munich), after helium ion implantations at the dose of 0.1 C/cm2. The investigation was focused on the chromium effect and the radiation defects resistivity. In particular, the vacancy type defects (monovacancies, vacancy clusters) have been studied. Based on our previous results achieved by conventional lifetime technique, the decrease of the defects size with increasing content of chromium is expected also for PLEPS measurements.

  1. Surface and Bulk Carbide Transformations in High-Speed Steel

    NASA Astrophysics Data System (ADS)

    Godec, M.; Večko Pirtovšek, T.; Šetina Batič, B.; McGuiness, P.; Burja, J.; Podgornik, B.

    2015-11-01

    We have studied the transformation of carbides in AISI M42 high-speed steels in the temperature window used for forging. The annealing was found to result in the partial transformation of the large, metastable M2C carbides into small, more stable grains of M6C, with an associated change in the crystal orientation. In addition, MC carbides form during the transformation of M2C to M6C. From the high-speed-steel production point of view, it is beneficial to have large, metastable carbides in the cast structure, which later during annealing, before the forging, transform into a structure of polycrystalline carbides. Such carbides can be easily decomposed into several small carbides, which are then randomly distributed in the microstructure. The results also show an interesting difference in the carbide-transformation reactions on the surface versus the bulk of the alloy, which has implications for in-situ studies of bulk phenomena that are based on surface observations.

  2. Surface and Bulk Carbide Transformations in High-Speed Steel.

    PubMed

    Godec, M; Večko Pirtovšek, T; Šetina Batič, B; McGuiness, P; Burja, J; Podgornik, B

    2015-11-05

    We have studied the transformation of carbides in AISI M42 high-speed steels in the temperature window used for forging. The annealing was found to result in the partial transformation of the large, metastable M2C carbides into small, more stable grains of M6C, with an associated change in the crystal orientation. In addition, MC carbides form during the transformation of M2C to M6C. From the high-speed-steel production point of view, it is beneficial to have large, metastable carbides in the cast structure, which later during annealing, before the forging, transform into a structure of polycrystalline carbides. Such carbides can be easily decomposed into several small carbides, which are then randomly distributed in the microstructure. The results also show an interesting difference in the carbide-transformation reactions on the surface versus the bulk of the alloy, which has implications for in-situ studies of bulk phenomena that are based on surface observations.

  3. Surface and Bulk Carbide Transformations in High-Speed Steel

    PubMed Central

    Godec, M.; Večko Pirtovšek, T.; Šetina Batič, B.; McGuiness, P.; Burja, J.; Podgornik, B.

    2015-01-01

    We have studied the transformation of carbides in AISI M42 high-speed steels in the temperature window used for forging. The annealing was found to result in the partial transformation of the large, metastable M2C carbides into small, more stable grains of M6C, with an associated change in the crystal orientation. In addition, MC carbides form during the transformation of M2C to M6C. From the high-speed-steel production point of view, it is beneficial to have large, metastable carbides in the cast structure, which later during annealing, before the forging, transform into a structure of polycrystalline carbides. Such carbides can be easily decomposed into several small carbides, which are then randomly distributed in the microstructure. The results also show an interesting difference in the carbide-transformation reactions on the surface versus the bulk of the alloy, which has implications for in-situ studies of bulk phenomena that are based on surface observations. PMID:26537780

  4. Development of India-specific RAFM steel through optimization of tungsten and tantalum contents for better combination of impact, tensile, low cycle fatigue and creep properties

    NASA Astrophysics Data System (ADS)

    Laha, K.; Saroja, S.; Moitra, A.; Sandhya, R.; Mathew, M. D.; Jayakumar, T.; Rajendra Kumar, E.

    2013-08-01

    Effects of tungsten and tantalum contents on impact, tensile, low cycle fatigue and creep properties of Reduced Activation Ferritic-Martensitic (RAFM) steel were studied to develop India-specific RAFM steel. Four heats of the steel have been melted with tungsten and tantalum contents in the ranges 1-2 wt.% and 0.06-0.14 wt.% respectively. Increase in tungsten content increased the ductile-to-brittle transition temperature (DBTT), low cycle fatigue and creep strength of the steel, whereas the tensile strength was not changed significantly. Increase in tantalum content increased the DBTT and low cycle fatigue strength of the steel whereas the tensile and creep strength decreased. Detailed TEM investigations revealed enhanced microstructural stability of the steel against creep exposure on tungsten addition. The RAFM steel having 1.4 wt.% tungsten with 0.06 wt.% tantalum was found to possess optimum combination of impact, tensile, low cycle fatigue and creep properties and is considered for Indian-specific RAFM steel. Low temperature impact energy of the RAFM steel is quite sensitive to the contents of tungsten and tantalum. The DBTT increased with both the tungsten and tantalum contents. Tungsten and tantalum contents in the investigated ranges had no appreciable effect on the tensile properties of the RAFM steel. Low cycle fatigue life of the RAFM steel increased with the increase in tungsten and tantalum contents. The softening rate with cyclic exposure was lowest for tungsten content of 1.4 wt.%, further increase in tungsten led to an increase in softening rate. Creep deformation and rupture strength of the RAFM steel were found to be quite sensitive to the tungsten and tantalum contents. Creep strength of the steel increased with increase in tungsten content and decreased with increase in tantalum content. Based on the study, the chemical composition of India-specific RAFM steel has been established as 9Cr-1.4W-0.06Ta-V, having optimum combination of strength and

  5. Regular subwavelength surface structures induced by femtosecond laser pulses on stainless steel.

    PubMed

    Qi, Litao; Nishii, Kazuhiro; Namba, Yoshiharu

    2009-06-15

    In this research, we studied the formation of laser-induced periodic surface structures on the stainless steel surface using femtosecond laser pulses. A 780 nm wavelength femtosecond laser, through a 0.2 mm pinhole aperture for truncating fluence distribution, was focused onto the stainless steel surface. Under different experimental condition, low-spatial-frequency laser-induced periodic surface structures with a period of 526 nm and high-spatial-frequency laser-induced periodic surface structures with a period of 310 nm were obtained. The mechanism of the formation of laser-induced periodic surface structures on the stainless steel surface is discussed.

  6. Imaging surface conditions of ferromagnetic steel using Barkhausen technique

    SciTech Connect

    Negley, M.A.; Jiles, D.C. . Center for NDE)

    1994-11-01

    When ferromagnetic materials are magnetized, the resulting hysteresis curve consists of discontinuous changes in magnetization. This Barkhausen effect is produced by discontinuous domain mechanisms such as the domain wall breaking away from pinning sites due to the application of a magnetic field. For this reason, the Barkhausen effect is very useful for analyzing the microstructure of a material, since inhomogeneities in the microstructure act as pinning sites which restrict domain wall motion. It can be shown that Barkhausen data, in the form of an rms Barkhausen signal amplitude, can be used to image flaws on the surface of ferromagnetic steels. The material surface conditions, such as stress, cracking, oxidation, plastic deformation and pitting produce signal changes which can be visualized through a computer generated image of the related Barkhausen parameters.

  7. Orientation dependence of microfracture behavior in a dual-phase high-strength low-alloy steel

    SciTech Connect

    Suh, D.; Lee, S.; Kim, N.J.; Kwon, D.

    1997-02-01

    In selecting the processing conditions and evaluating the reliability of structural materials, microscopic observations and identification of the fracture mechanisms in local cracking behavior are required. An important instance in the failure of the local brittle zone (LBZ) in the welding zone. The LBZ, which is very brittle, is the coarse-grained heat-affected zone near the fusion line, a zone known to be critical to the fracture toughness of welded parts. Thus, maintaining stable fracture resistance by predicting the microfracture behavior is important when using high-strength low-alloy (HSLA) steels in offshore structural steel welds. Depending on the thermal cycles involved during welding, the ferrite/martensite structure can have various morphologies of martensite particles, for example, fibrous and blocky martensite. In summary, in situ SEM fracture tests reveal that in the L-oriented IQ DCB specimen, a microcrack tends to propagate relatively uniformly throughout the ferrite and well-distributed fine fibrous martensite, yielding good elongation with high strength level. Also, the IQ structure in the T orientation shows similar microfracture behavior. On the other hand, in the SQ structure, where blocky-type martensite is mixed with ferrite, strain is localized into shear bands mostly in the ferrite region, and a local microcrack propagates along the strain-localized band formed in the ferrite, resulting in the SQ structure in the T orientation, where the ferrite-martensite bands are parallel to the notch direction, the martensite cannot act as an efficient barrier to microcrack advance, and thus the tensile ductility is decreased.

  8. Neutron Irradiation Resistance of RAFM Steels

    SciTech Connect

    Gaganidze, Ermile; Dafferner, Bernhard; Aktaa, Jarir

    2008-07-01

    The neutron irradiation resistance of the reduced-activation ferritic/martensitic (RAFM) steel EUROFER97 and international reference steels (F82H-mod, OPTIFER-Ia, GA3X and MANET-I) have been investigated after irradiation in the Petten High Flux Reactor up to 16.3 dpa at different irradiation temperatures (250-450 deg. C). The embrittlement behavior and hardening are investigated by instrumented Charpy-V tests with sub-size specimens. Neutron irradiation-induced embrittlement and hardening of EUROFER97 was studied under different heat treatment conditions. Embrittlement and hardening of as-delivered EUROFER97 steel are comparable to those of reference steels. Heat treatment of EUROFER97 at a higher austenitizing temperature substantially improves the embrittlement behaviour at low irradiation temperatures. Analysis of embrittlement vs. hardening behavior of RAFM steels within a proper model in terms of the parameter C={delta}DBTT/{delta}{sigma} indicates hardening-dominated embrittlement at irradiation temperatures below 350 deg. C with 0.17 {<=} C {<=} 0.53 deg. C/MPa. Scattering of C at irradiation temperatures above 400 deg. C indicates non hardening embrittlement. A role of He in a process of embrittlement is investigated in EUROFER97 based steels, that are doped with different contents of natural B and the separated {sup 10}B-isotope (0.008-0.112 wt.%). Testing on small scale fracture mechanical specimens for determination of quasi-static fracture toughness will be also presented in a view of future irradiation campaigns. (authors)

  9. Characterization of corrosion products formed on different surfaces of steel exposed to simulated groundwater solution

    NASA Astrophysics Data System (ADS)

    Xu, Qiufa; Gao, Kewei; Wang, Yanbin; Pang, Xiaolu

    2015-08-01

    The corrosion behavior of a low alloy steel in simulated groundwater was investigated. The upward surface of the steel underwent more serious corrosion than the downward surface. The corrosion products formed on the upward and downward surfaces were characterized by SEM, EDX, and XRD, and the electrochemical properties of bare and rusted samples were analyzed. The difference in the corrosion rates of the different surfaces of the steel could be attributed to the potential difference between the upward and downward surfaces as well as the higher amount of CaCO3 deposits on the downward surface leading to a compact corrosion product.

  10. New research progressing of surface modification of medical 316L stainless steels

    NASA Astrophysics Data System (ADS)

    Xu, Lin; Ba, Dechun; Wang, Qing; Guo, Deyu

    2013-12-01

    316L stainless steels are widely used in clinical and medical fields because of their comprehensive performance. This paper analyses the current development situation and major existing problems of medical 316L stainless steels. The new methods and research achievement of surface modification in recent years are described in detail. It indicates that surface modification is an effective way to solve clinical application problems, and provides new opportunities for medical 316L stainless steels in medical applications.

  11. Wetting Properties of Liquid Lithium on Stainless Steel and Enhanced Stainless Steel Surfaces

    NASA Astrophysics Data System (ADS)

    Fiflis, P.; Xu, W.; Raman, P.; Andruczyk, D.; Ruzic, D. N.; Curreli, D.

    2012-10-01

    Research into lithium as a first wall material has proven its ability to effectively getter impurities and reduce recycling of hydrogen ions at the wall. Current schemes for introducing lithium into a fusion device consist of lithium evaporators, however, as these devices evolve from pulsed to steady state, new methods will need to be employed such as the LIMIT concept of UIUC, or thin flowing film lithium walls. Critical to their implementation is understanding the interactions of liquid lithium with various surfaces. One such interaction is the wetting of materials by lithium, which may be characterized by the contact angle between the lithium and the surface. Experiments have been performed at UIUC into the contact angle of liquid lithium with a given surface, as well as methods to increase it. To reduce the oxidation rate of the droplets, the experiments were performed in vacuum, using a lithium injector to deposit drops on each surface. Among the materials investigated are stainless steel, both untreated and coated with a diamond like carbon (DLC) layer, molybdenum, and boronized molybdenum. The contact angle and its dependence on temperature is measured.

  12. Research on the illumination model based on light scattering properties of steel surface

    NASA Astrophysics Data System (ADS)

    Liu, Yuanjiong; Kong, Jianyi; Xu, Pan; Liu, Cancan; Zheng, Guo

    2015-12-01

    Experimental scheme was designed based on the steel production process, surface optical characteristics and BRDF (Bidirectional Reflectance Distribution Function) illumination model theory. The relationship between the light incidence angle, surface roughness and laws of light scattering under a particular light-source conditions were found through a series of light scattering characteristics experiments for different steel plate surface. The results showed that there was an apparent specular reflection peak on steel surface. surface light scattering was influenced greatly by light incidence angle and surface roughness, and it showed the law of exponential distribution functions. Thus the improved semi-empirical light scattering mathematical model which based on roughness factor and surface Gaussian distribution of micro-plane components has been formed through non-linear model fitting and optimization. The surface illumination model has been proposed to accurately describe the light intensity distribution of steel plate surface and provide a theoretical method for the design of optimal imaging system.

  13. Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2011-01-01

    This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 μm and 150 μm. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 μm. The maximum hardness achieved was between 728 and 905 HV0.1. These findings are significant to modern development of hard coatings for wear resistant applications.

  14. SURFACE PREPARATION OF STEEL SUBSTRATES USING GRIT-BLASTING

    SciTech Connect

    Donna Post Guillen; D. J. Varacalle, Jr.; D. Deason; W. Rhodaberger; E. Sampson

    2005-05-01

    The primary purpose of grit blasting for thermal spray applications is to ensure a strong mechanical bond between the substrate and the coating by the enhanced roughening of the substrate material. This study presents statistically designed experiments that were accomplished to investigate the effect of abrasives on roughness for A36/1020 steel. The experiments were conducted using a Box statistical design of experiment (SDE) approach. Three grit blasting parameters and their effect on the resultant substrate roughness were investigated. These include blast media, blast pressure, and working distance. The substrates were characterized for roughness using surface profilometry. These attributes were correlated with the changes in operating parameters. Twin-Wire Electric Arc (TWEA) coatings of aluminum and zinc/aluminum were deposited on the grit-blasted substrates. These coatings were then tested for bond strength. Bond strength studies were conducted utilizing a portable adhesion tester following ASTM standard D4541.

  15. Comparison of corrosion behavior of EUROFER and CLAM steels in flowing Pb-15.7Li

    NASA Astrophysics Data System (ADS)

    Konys, J.; Krauss, W.; Zhu, Z.; Huang, Q.

    2014-12-01

    Ferritic martensitic steels are envisaged to be applied as structural materials in HCLL blanket systems. Their compatibility with the liquid breeder, which is in direct contact with the structural alloy, will be essential for reliable and safe operation of the designed blankets. Formerly performed corrosion tests of RAFM steels in PICOLO loop of KIT were mainly done at high flow velocities, e.g., 0.22 m/s and delivered severe attack with material loss rates above 400 μm/yr at 823 K. Meanwhile, flow velocities for corrosion testing have been reduced into the "cm range" to be near fusion relevant conditions. Among the international ITER-partners, many varieties of RAFM steels have been developed and manufactured within the last decade, e.g., the so-called Chinese Low Activation Martensitic steel (CLAM). In this paper, the long term corrosion behavior of EUROFER and CLAM steel in flowing Pb-15.7Li will be presented at a flow velocity of about 0.10 m/s and compared with earlier obtained results of RAFM steels exposed at other operation parameters of PICOLO loop. The observed corrosion attack is near 220 μm/yr and fits well to predictions made by MATLIM-modeling for low flow velocities in the turbulent flow regime.

  16. Microstructural Analysis of Orientation-Dependent Recovery and Recrystallization in a Modified 9Cr-1Mo Steel Deformed by Compression at a High Strain Rate

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenbo; Zhang, Yubin; Mishin, Oleg V.; Tao, Nairong; Pantleon, Wolfgang; Juul Jensen, Dorte

    2016-09-01

    The evolution of the microstructure and texture during annealing of a modified ferritic/martensitic 9Cr-1Mo steel compressed by dynamic plastic deformation (DPD) to a strain of 2.3 has been investigated using transmission electron microscopy and electron backscatter diffraction. It is found that the duplex <111> + <100> fiber texture formed by DPD is transformed during annealing to a dominant <111> fiber texture, and that crystallites of the <111> component have an advantage during both nucleation and growth. Detailed characterization of the microstructural morphology, and estimation of the stored energies in <111>- and <100>-oriented regions in deformed and annealed samples, as well as investigations of the growth of recrystallizing grains, are used to analyze the annealing behavior. It is concluded that recrystallization in the given material occurs by a combination of oriented nucleation and oriented growth.

  17. PARAMETERS OF TREATED STAINLESS STEEL SURFACES IMPORTANT FOR RESISTANCE TO BACTERIAL CONTAMINATION

    EPA Science Inventory

    Use of materials that are resistant to bacterial contamination could enhance food safety during processing. Common finishing treatments of stainless steel surfaces used for components of poultry processing equipment were tested for resistance to bacterial attachment. Surface char...

  18. Compatibility Assessment of Advanced Stainless Steels in Sodium

    SciTech Connect

    Pawel, Steven J

    2012-01-01

    Type 316L stainless steel capsules containing commercially pure sodium and miniature tensile specimens of HT-UPS (austenitic, 14Cr-16Ni), NF-616 (ferritic/martensitic, 9Cr-2W-0.5Mo), or 316L (austenitic, 17Cr-10Ni-2Mo) stainless steel were exposed at 600 or 700 C for 100 and 400 h as a screening test for compatibility. Using weight change, tensile testing, and metallographic analysis, HT-UPS and 316L were found to be largely immune to changes resulting from sodium exposure, but NF-616 was found susceptible to substantial decarburization at 700 C. Subsequently, two thermal convection loops (TCLs) constructed of 316L and loaded with commercially pure sodium and miniature tensile specimens of HT-UPS and 316L were operated for 2000 h each one between 500 and 650 C, the other between 565 and 725 C at a flow rate of about 1.5 cm/s. Changes in specimen appearance, weight, and tensile properties were observed to be very minor in all cases, and there was no metallographic evidence of microstructure changes, composition gradients, or mass transfer resulting from prolonged exposure in a TCL. Thus, it appears that HT-UPS and 316L stainless steels are similarly compatible with commercially pure sodium under these exposure conditions.

  19. An Evaluation of the Corrosion and Mechanical Performance of Interstitially Surface Hardened Stainless Steel

    DTIC Science & Technology

    2013-05-10

    deep circumferential notches, created with a thread cutting tool , were machined to expose the base metal during SSRT tests conducted in air and...interstitial carbon atoms into stainless steel surfaces without the formation of carbides . Surface hardening of machine elements such as impellors or...developed to introduce interstitial carbon atoms into stainless steel surfaces without the formation of carbides . Surface hardening of machine elements

  20. Tribological thin films on steel rolling element bearing surfaces

    NASA Astrophysics Data System (ADS)

    Evans, Ryan David

    Tribological thin films are of interest to designers and end-users of friction management and load transmission components such as steel rolling element bearings. This study sought to reveal new information about the properties and formation of such films, spanning the scope of their technical evolution from natural oxide films, to antiwear films from lubricant additives, and finally engineered nanocomposite metal carbide/amorphous hydrocarbon (MC/a-C:H) films. Transmission electron microscopy (TEM) was performed on the near-surface material (depth < 500 nm) of tapered roller bearing inner rings (cones) that were tested at two levels of boundary-lubricated conditions in mineral oil with and without sulfur- and phosphorus-containing gear oil additives. Site-specific thinning of cross-section cone surface sections for TEM analyses was conducted using the focused ion beam milling technique. Two types of oxide surface films were characterized for the cones tested in mineral oil only, each one corresponding to a different lubrication severity. Continuous and adherent antiwear films were found on the cone surfaces tested with lubricant additives, and their composition depended on the lubrication conditions. A sharp interface separated the antiwear film and base steel. Various TEM analytical techniques were used to study the segregation of elements throughout the film volume. The properties of nanocomposite tantalum carbide/amorphous hydrocarbon (TaC/a-C:H) thin films depend sensitively on reactive magnetron sputtering deposition process conditions. TaC/a-C:H film growth was studied as a function of three deposition parameters in designed experiments: acetylene flow rate, applied d.c. bias voltage, and substrate carousel rotation rate. Empirical models were developed for the following film characteristics to identify process-property trend relationships: Ta/C atomic ratio, hydrogen content, film thickness. TaC crystallite size, Raman spectrum, compressive stress, hardness

  1. Surface modification to improve fireside corrosion resistance of Fe-Cr ferritic steels

    DOEpatents

    Park, Jong-Hee; Natesan, Krishnamurti; Rink, David L.

    2010-03-16

    An article of manufacture and a method for providing an Fe--Cr ferritic steel article of manufacture having a surface layer modification for corrosion resistance. Fe--Cr ferritic steels can be modified to enhance their corrosion resistance to liquid coal ash and other chemical environments, which have chlorides or sulfates containing active species. The steel is modified to form an aluminide/silicide passivating layer to reduce such corrosion.

  2. Raman mapping of intact biofilms on stainless steel surfaces

    NASA Astrophysics Data System (ADS)

    Nguyen, Julie K.; Heighton, Lynne; Xu, Yunfeng; Nou, Xiangwu; Schmidt, Walter F.

    2016-05-01

    Many issues occur when microbial bacteria contaminates human food or water; it can be dangerous to the public. Determining how the microbial are growing, it can help experts determine how to prevent the outbreaks. Biofilms are a tightly group of microbial cells that grow on living surfaces or surrounding themselves. Though biofilms are not necessarily uniform; when there are more than one type of microbial bacteria that are grown, Raman mapping is performed to determine the growth patterns. Depending on the type of microbial bacteria, they can grow in various patterns such as symmetrical or scattered on the surface. The biofilms need to be intact in order to preclude and potentially figuring out the relative intensity of different components in a biofilm mixture. In addition, it is important to determine whether one biofilms is a substrate for another biofilm to be detected. For example, it is possible if layer B appears above layer A, but layer A doesn't appear above layer B. In this case, three types of biofilms that are grown includes Listeria(L), Ralstonia(R), and a mixture of the two (LR). Since microbe deposits on metal surfaces are quite suitable, biofilms were grown on stainless steel surface slides. Each slide was viewed under a Raman Microscope at 100X and using a 532nm laser to provide great results and sharp peaks. The mapping of the laser helps determine how the bacteria growth, at which intensity the bacteria appeared in order to identify specific microbes to signature markers on biofilms.

  3. Enhancing steel properties through in situ formation of ultrahard ceramic surface.

    PubMed

    Pahlevani, Farshid; Kumar, Rahul; Gorjizadeh, Narjes; Hossain, Rumana; Cholake, Sagar T; Privat, Karen; Sahajwalla, Veena

    2016-12-08

    Abrasion and corrosion resistant steel has attracted considerable interest for industrial application as a means of minimising the costs associated with product/component failures and/or short replacement cycles. These classes of steels contain alloying elements that increase their resistance to abrasion and corrosion. Their benefits, however, currently come at a potentially prohibitive cost; such high performance steel products are both more technically challenging and more expensive to produce. Although these methods have proven effective in improving the performance of more expensive, high-grade steel components, they are not economically viable for relatively low cost steel products. New options are needed. In this study, a complex industrial waste stream has been transformed in situ via precisely controlled high temperature reactions to produce an ultrahard ceramic surface on steel. This innovative ultrahard ceramic surface increases both the hardness and compressive strength of the steel. Furthermore, by modifying the composition of the waste input and the processing parameters, the ceramic surface can be effectively customised to match the intended application of the steel. This economical new approach marries industry demands for more cost-effective, durable steel products with global imperatives to address resource depletion and environmental degradation through the recovery of resources from waste.

  4. Enhancing steel properties through in situ formation of ultrahard ceramic surface

    NASA Astrophysics Data System (ADS)

    Pahlevani, Farshid; Kumar, Rahul; Gorjizadeh, Narjes; Hossain, Rumana; Cholake, Sagar T.; Privat, Karen; Sahajwalla, Veena

    2016-12-01

    Abrasion and corrosion resistant steel has attracted considerable interest for industrial application as a means of minimising the costs associated with product/component failures and/or short replacement cycles. These classes of steels contain alloying elements that increase their resistance to abrasion and corrosion. Their benefits, however, currently come at a potentially prohibitive cost; such high performance steel products are both more technically challenging and more expensive to produce. Although these methods have proven effective in improving the performance of more expensive, high-grade steel components, they are not economically viable for relatively low cost steel products. New options are needed. In this study, a complex industrial waste stream has been transformed in situ via precisely controlled high temperature reactions to produce an ultrahard ceramic surface on steel. This innovative ultrahard ceramic surface increases both the hardness and compressive strength of the steel. Furthermore, by modifying the composition of the waste input and the processing parameters, the ceramic surface can be effectively customised to match the intended application of the steel. This economical new approach marries industry demands for more cost-effective, durable steel products with global imperatives to address resource depletion and environmental degradation through the recovery of resources from waste.

  5. Enhancing steel properties through in situ formation of ultrahard ceramic surface

    PubMed Central

    Pahlevani, Farshid; Kumar, Rahul; Gorjizadeh, Narjes; Hossain, Rumana; Cholake, Sagar T; Privat, Karen; Sahajwalla, Veena

    2016-01-01

    Abrasion and corrosion resistant steel has attracted considerable interest for industrial application as a means of minimising the costs associated with product/component failures and/or short replacement cycles. These classes of steels contain alloying elements that increase their resistance to abrasion and corrosion. Their benefits, however, currently come at a potentially prohibitive cost; such high performance steel products are both more technically challenging and more expensive to produce. Although these methods have proven effective in improving the performance of more expensive, high-grade steel components, they are not economically viable for relatively low cost steel products. New options are needed. In this study, a complex industrial waste stream has been transformed in situ via precisely controlled high temperature reactions to produce an ultrahard ceramic surface on steel. This innovative ultrahard ceramic surface increases both the hardness and compressive strength of the steel. Furthermore, by modifying the composition of the waste input and the processing parameters, the ceramic surface can be effectively customised to match the intended application of the steel. This economical new approach marries industry demands for more cost-effective, durable steel products with global imperatives to address resource depletion and environmental degradation through the recovery of resources from waste. PMID:27929096

  6. Effect of microstructure on low cycle fatigue properties of ODS steels

    NASA Astrophysics Data System (ADS)

    Kubena, Ivo; Fournier, Benjamin; Kruml, Tomas

    2012-05-01

    Low cycle fatigue properties at room temperature, 650 °C and 750 °C of three high chromium steels (9%Cr ferritic-martensitic and two 14%Cr ferritic steels) strengthened by oxide dispersion were studied and compared. Cyclic softening/hardening curves, cyclic deformation curves, S-N curves and Coffin-Manson curves are presented together with microstructural observations. Differences in cyclic response, stress level and fatigue life are attributed to differences in the matrix microstructure. The oxide particles stabilize the cyclic response, even if cyclic softening is detected for some experimental conditions. The strength of these steels is discussed in terms of strengthening mechanisms such as grain size effect, particle-dislocations interaction and dislocation density. Comparing three different ODS steels offers an opportunity to tests the contribution of individual mechanisms to the cyclic strength. The reduction of fatigue life in one of the ferritic steels is explained by the presence of large grains, facilitating the fatigue crack nucleation and the early growth.

  7. Ferritic steels for sodium-cooled fast reactors: Design principles and challenges

    NASA Astrophysics Data System (ADS)

    Raj, Baldev; Vijayalakshmi, M.

    2010-09-01

    An overview of the current status of development of ferritic steels for emerging fast reactor technologies is presented in this paper. The creep-resistant 9-12Cr ferritic/martensitic steels are classically known for steam generator applications. The excellent void swelling resistance of ferritic steels enabled the identification of their potential for core component applications of fast reactors. Since then, an extensive knowledge base has been generated by identifying the empirical correlations between chemistry of the steels, heat treatment, structure, and properties, in addition to their in-reactor behavior. A few concerns have also been identified which pertain to high-temperature irradiation creep, embrittlement, Type IV cracking in creep-loaded weldments, and hard zone formation in dissimilar joints. The origin of these problems and the methodologies to overcome the limitations are highlighted. Finally, the suitability of the ferritic steels is re-evaluated in the emerging scenario of the fast reactor technology, with a target of achieving better breeding ratio and improved thermal efficiency.

  8. Impurity content of reduced-activation ferritic steels and a vanadium alloy

    SciTech Connect

    Klueh, R.L.; Grossbeck, M.L.; Bloom, E.E.

    1997-04-01

    Inductively coupled plasma mass spectrometry was used to analyze a reduced-activation ferritic/martensitic steel and a vanadium alloy for low-level impurities that would compromise the reduced-activation characteristics of these materials. The ferritic steel was from the 5-ton IEA heat of modified F82H, and the vanadium alloy was from a 500-kg heat of V-4Cr-4Ti. To compare techniques for analysis of low concentrations of impurities, the vanadium alloy was also examined by glow discharge mass spectrometry. Two other reduced-activation steels and two commercial ferritic steels were also analyzed to determine the difference in the level of the detrimental impurities in the IEA heat and steels for which no extra effort was made to restrict some of the tramp impurities. Silver, cobalt, molybdenum, and niobium proved to be the tramp impurities of most importance. The levels observed in these two materials produced with present technology exceeded the limits for low activation for either shallow land burial or recycling. The chemical analyses provide a benchmark for the improvement in production technology required to achieve reduced activation; they also provide a set of concentrations for calculating decay characteristics for reduced-activation materials. The results indicate the progress that has been made and give an indication of what must still be done before the reduced-activation criteria can be achieved.

  9. Three-Dimensional Surface Parameters and Multi-Fractal Spectrum of Corroded Steel.

    PubMed

    Shanhua, Xu; Songbo, Ren; Youde, Wang

    2015-01-01

    To study multi-fractal behavior of corroded steel surface, a range of fractal surfaces of corroded surfaces of Q235 steel were constructed by using the Weierstrass-Mandelbrot method under a high total accuracy. The multi-fractal spectrum of fractal surface of corroded steel was calculated to study the multi-fractal characteristics of the W-M corroded surface. Based on the shape feature of the multi-fractal spectrum of corroded steel surface, the least squares method was applied to the quadratic fitting of the multi-fractal spectrum of corroded surface. The fitting function was quantitatively analyzed to simplify the calculation of multi-fractal characteristics of corroded surface. The results showed that the multi-fractal spectrum of corroded surface was fitted well with the method using quadratic curve fitting, and the evolution rules and trends were forecasted accurately. The findings can be applied to research on the mechanisms of corroded surface formation of steel and provide a new approach for the establishment of corrosion damage constitutive models of steel.

  10. Three-Dimensional Surface Parameters and Multi-Fractal Spectrum of Corroded Steel

    PubMed Central

    Shanhua, Xu; Songbo, Ren; Youde, Wang

    2015-01-01

    To study multi-fractal behavior of corroded steel surface, a range of fractal surfaces of corroded surfaces of Q235 steel were constructed by using the Weierstrass-Mandelbrot method under a high total accuracy. The multi-fractal spectrum of fractal surface of corroded steel was calculated to study the multi-fractal characteristics of the W-M corroded surface. Based on the shape feature of the multi-fractal spectrum of corroded steel surface, the least squares method was applied to the quadratic fitting of the multi-fractal spectrum of corroded surface. The fitting function was quantitatively analyzed to simplify the calculation of multi-fractal characteristics of corroded surface. The results showed that the multi-fractal spectrum of corroded surface was fitted well with the method using quadratic curve fitting, and the evolution rules and trends were forecasted accurately. The findings can be applied to research on the mechanisms of corroded surface formation of steel and provide a new approach for the establishment of corrosion damage constitutive models of steel. PMID:26121468

  11. Improved wear resistance by phase transformation of surface nanocrystalline 1090 steel prepared by sandblasting technique

    NASA Astrophysics Data System (ADS)

    Peng, Rong; Fu, Licai; Zhou, Lingping

    2016-12-01

    A surface nanocrystalline 1090 steel has been fabricated by using sandblasting technique. The surface average grain size was about 78 nm. The high strain rate and strain in sandblasting were main reasons for surface nanocrystallization. The wear resistance of 1090 steel was considerably enhanced as grain size decreased. The microstructure and hardness of contact zones before and after wear tests have been examined by XRD, SEM and TEM. Except the higher hardness, the results demonstrated that parts of ferrite transferred to cementite and martensite. It was additional beneficial for improving the wear resistance of 1090 steel as the grain size decreased.

  12. Adhesion of a fluorinated poly(amic acid) with stainless steel surfaces

    NASA Astrophysics Data System (ADS)

    Jung, Youngsuk; Song, Sunjin; Kim, Sangmo; Yang, Yooseong; Chae, Jungha; Park, Tai-Gyoo; Dong Cho, Myung

    2013-01-01

    The authors elucidate an origin and probable mechanism of adhesion strength change at an interface of fluorinated poly(amic acid) and stainless steel. Fluorination provides favorable delamination with release strength weaker than 0.08 N/mm from a metal surface, once the amount of residual solvent becomes less than 35 wt. %. However, the release strength critically depends on film drying temperature. Characterization on stainless steel surfaces and thermodynamic analyses on wet films reveal a drying temperature of 80 °C fosters interaction between the metal oxides at stainless steel surface and the free electron donating groups in poly(amic acid).

  13. Steel-surface defect detection using a switching-lighting scheme.

    PubMed

    Jeon, Yong-Ju; Choi, Doo-Chul; Lee, Sang Jun; Yun, Jong Pil; Kim, Sang Woo

    2016-01-01

    In this paper a novel filtering scheme combined with a lighting method is proposed for defect detection in steel surfaces. A steel surface has non-uniform brightness and various shaped defects, which cause difficulties in defect detection. To solve this problem we propose a sub-optimal filtering that is combined with a switching-lighting method. First, dual-light switching lighting (DLSL) is explained, which decreases the effect of non-uniformity of surface brightness and improves the detection accuracy. By using the DLSL method, defects are represented as alternated black and white patterns regardless of the size, shape, or orientation of defects. Therefore, defects can be detected by finding alternated black and white patterns. Second, we propose a scheme for detecting defects in steel-surface images acquired using the DLSL method. The presence of scales strongly affects the optical properties of the surface. Moreover, the textures of steel-plate images vary greatly because of the temperature and grade of steel. Therefore, conventional filter-design methods are not effective for different image textures. A sub-optimal scheme based on an optimized general-finite impulse-response filter is also proposed. Finally, experimental results conducted on steel-surface images from an actual steel-production line show the effectiveness of the proposed algorithm.

  14. Fabrication of superhydrophobic textured steel surface for anti-corrosion and tribological properties

    NASA Astrophysics Data System (ADS)

    Zhang, Hongmei; Yang, Jin; Chen, Beibei; Liu, Can; Zhang, Mingsuo; Li, Changsheng

    2015-12-01

    We describe a simple and rapid method to fabricate superhydrophobic textured steel surface with excellent anti-corrosion and tribological properties on S45C steel substrate. The steel substrate was firstly ground using SiC sandpapers, and then polished using diamond paste to remove scratches. The polished steel was subsequently etched in a mixture of HF and H2O2 solution for 30 s at room temperature to obtain the textured steel surface with island-like protrusions, micro-pits, and nano-flakes. Meanwhile, to investigate the formation mechanism of the multiscale structures, the polished steel was immersed in a 3 wt% Nital solution for 5 s to observe the metallographic structures. The multiscale structures, along with low-surface-energy molecules, led to the steel surface that displayed superhydrophobicity with the contact angle of 158 ± 2° and the sliding angle of 3 ± 1°. The chemical stability and potentiodynamic polarization test indicated that the as-prepared superhydrophobic surface had excellent corrosion resistance that can provide effective protection for the steel substrate. The tribological test showed that the friction coefficient of the superhydrophobic surface maintained 0.11 within 6000 s and its superhydrophobicity had no obvious decrease after the abrasion test. The theoretical mechanism for the excellent anti-corrosion and tribological properties on the superhydrophobic surface were also analyzed respectively. The advantages of facile production, anti-corrosion, and tribological properties for the superhydrophobic steel surface make it to be a good candidate in practical applications.

  15. Finite element simulation for damage detection of surface rust in steel rebars using elastic waves

    NASA Astrophysics Data System (ADS)

    Tang, Qixiang; Yu, Tzuyang

    2016-04-01

    Steel rebar corrosion reduces the integrity and service life of reinforced concrete (RC) structures and causes their gradual and sudden failures. Early stage detection of steel rebar corrosion can improve the efficiency of routine maintenance and prevent sudden failures from happening. In this paper, detecting the presence of surface rust in steel rebars is investigated by the finite element method (FEM) using surface-generated elastic waves. Simulated wave propagation mimics the sensing scheme of a fiber optic acoustic generator mounted on the surface of steel rebars. Formation of surface rust in steel rebars is modeled by changing material's property at local elements. In this paper, various locations of a fiber optic acoustic transducer and a receiver were considered. Megahertz elastic waves were used and different sizes of surface rust were applied. Transient responses of surface displacement and pressure were studied. It is found that surface rust is most detectable when the rust location is between the transducer and the receiver. Displacement response of intact steel rebar is needed in order to obtain background-subtracted response with a better signal-to-noise ratio. When the size of surface rust increases, reduced amplitude in displacement was obtained by the receiver.

  16. Study of helium embrittlement in boron doped EUROFER97 steels

    NASA Astrophysics Data System (ADS)

    Gaganidze, E.; Petersen, C.; Aktaa, J.

    2009-04-01

    To simulate helium effects in Reduced Activation Ferritic/Martensitic steels, experimental heats ADS2, ADS3 and ADS4 with the basic composition of EUROFER97 (9%Cr-WVTa) were doped with different contents of natural boron and separated 10B-isotope (0.008-0.112 wt.%) and irradiated in High Flux Reactor (HFR) Petten up to 16.3 dpa at 250-450 °C and in Bor-60 fast reactor in Dimitrovgrad up to 31.8 dpa at 332-338 °C. The embrittlement and hardening are investigated by instrumented Charpy-V tests with subsize specimens. Complete burn-up of 10B isotope under neutron irradiation in HFR Petten led to generation of 84, 432 and 5580 appm He and partial boron-to-helium transformation in Bor-60 led to generation of 9, 46, 880 appm He in ADS2, ADS3 and ADS4 heats, respectively. At low irradiation temperatures Tirr ⩽ 340 °C the boron doped steels show progressive embrittlement with increasing helium amount. Irradiation induced DBTT shift of EUROFER97 based heat doped with 1120 wppm separated 10B isotope could not be quantified due to large embrittlement found in the investigated temperature range. At Tirr ⩽ 340 °C helium induced extra embrittlement is attributed to material hardening induced by helium bubbles and described in terms of phenomenological model.

  17. Effects of surface condition on the stress corrosion cracking of line pipe steel

    SciTech Connect

    Beavers, J.A.; Christman, T.K.; Parkins, R.N.

    1988-04-01

    The relationship between surface properties of line pipe steels and external stress corrosion cracking (SCC) is reviewed. Surface factors discussed include mill scale, surface pitting, decarburization, surface residual stresses, and near-surface stress state. Recent research results have demonstrated that the susceptibility of a line pipe steel to SCC initiation is dependent on complicated interaction among these properties. However, these studies also show that relatively simple surface preparation procedures such as grit blasting can be effective in reducing the susceptibility of pipelines to crack initiation.

  18. Type 304L stainless steel surface microstructure: Performance in hydride storage and acid cleaning

    SciTech Connect

    Clark, E.A.

    1994-07-01

    The performance of stainless steel as the container in hydride storage bed systems has been evaluated, primarily using scanning electron microscopy. No adverse reaction between Type 304L stainless steel and either LaNi{sub 5{minus}x},Al{sub x}, or palladium supported on Kieselguhr granules (silica) during exposure in hydrogen was found in examination of retired prototype storage bed containers and special compatibility test samples. Intergranular surface ditching, observed on many of the stainless steel surfaces examined, was shown to result from air annealing and acid cleaning of stainless steel during normal fabrication. The ditched air annealed and acid cleaned stainless steel samples were more resistant to subsequent acid attack than vacuum annealed or polished samples without ditches.

  19. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

    PubMed Central

    Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

    2015-01-01

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining. PMID:26482559

  20. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel.

    PubMed

    Tesler, Alexander B; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

    2015-10-20

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.

  1. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

    NASA Astrophysics Data System (ADS)

    Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

    2015-10-01

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.

  2. Dynamics of cathode spots in low-pressure arc plasma removing oxide layer on steel surfaces

    NASA Astrophysics Data System (ADS)

    Tang, Z. L.; Yang, K.; Liu, H. X.; Zhang, Y. C.; Li, H.; Zhu, X. D.

    2016-03-01

    The dynamics of cathode spots has been investigated in low-pressure arc plasma for removing oxide layer on low carbon steel surfaces. The motion of cathode spots was observed with a high speed camera, and the arc voltage was analyzed by fast Fourier transform. The spots move on clean steel surface as a random walk, and the low-frequency components dominated the voltage waveform. However, the spots on steel surfaces with oxide layer tend to burn on the rim of the eroded area formed in the previous arcing, and the low-frequency components decrease correspondingly. The "color" of the colored random noise for arc voltage varies from the approximate brown noise for clean steel surface to pink noise for thick oxide layer, where the edge effect of boundary is considered to play a significant role.

  3. Nanosized controlled surface pretreatment of biometallic alloy 316L stainless steel.

    PubMed

    Abdel-Fattah, Tarek M; Loftis, Derek; Mahapatro, Anil

    2011-12-01

    Stainless steel (AISI 316L) is a medical grade stainless steel alloy used extensively in medical devices and in the biomedical field. 316L stainless steel was successfully electropolished via an ecologically friendly and biocompatible ionic liquid (IL) medium based on Vitamin B4 (NB4) and resulting in nanosized surface roughness and topography. Voltammetry and chronoamperometry tests determined optimum polishing conditions for the stainless steel alloy while atomic force microscopy (AFM) and scanning electron microscopy (SEM) provided surface morphology comparisons to benchmark success of each electropolishing condition. Energy dispersive X-ray analysis (EDX) combined with SEM revealed significantly smoother surfaces for each alloy surface while indicating that the constituent metals comprising each alloy effectively electropolished at uniform rates.

  4. Interactions of N,N'-dimethylaminoethanol with steel surfaces in alkaline and chlorine containing solutions

    NASA Astrophysics Data System (ADS)

    Welle, A.; Liao, J. D.; Kaiser, K.; Grunze, M.; Mäder, U.; Blank, N.

    1997-10-01

    Formulations based on dilute aqueous solutions of N,N'-dimethylethanolamine (DMEA) are used to protect reinforcement steel bars ('rebar') in concrete from corrosion. In a previous paper we discussed the usefulness of X-ray photoelectron spectroscopy (XPS) to detect DMEA adsorbed from solution and the application of secondary neutral mass spectrometry (SNMS) to study migration of DMEA through a cement matrix. In this report we present XPS data of DMEA adsorbed on steel surfaces from alkaline and chlorine containing solutions of variable concentration range and discuss models for the interaction of DMEA with the oxidized steel surface and the mechanism of corrosion inhibition of DMEA. DMEA is strongly bonded to the steel surface and displaces ionic species from the substrate/solution interface hence protecting the ironoxide surface from ionic attack.

  5. Damage Susceptibility of Grain Boundaries in HT9 Steel Subjected to High-Temperature Creep

    NASA Astrophysics Data System (ADS)

    Leng, Zhe; Field, David P.

    2012-10-01

    HT9 steel is an attractive ferritic/martensitic steel that is used in components of nuclear and fossil power plants because of its high strength and good swelling resistance. Specific phenomena (such as segregation, voiding, cracking, etc.) are prevalent along grain boundaries since these interfaces act as efficient sources for vacancies. The accumulation of vacancies in grain boundaries may result in intergranular fracture. In this study, HT9 steel was subjected to creep tests at elevated temperature (about 0.5 T m) and two different creep conditions (where creep lifetimes were about 100 and about 1000 hours, respectively). The grain boundaries in HT9 steel after creep tests were studied by the use of scanning electron microscopy in order to establish the relationship between the grain boundary structure and creep damage. Images and data obtained using electron backscatter diffraction reveal a high susceptibility of high-angle boundaries to creep cavitation, as expected. In addition, the Σ3 boundaries are also susceptible to damage under these conditions at a similar or even higher rate as compared with random high-angle boundaries.

  6. Effects of tantalum content on the microstructure and mechanical properties of low-carbon RAFM steel

    NASA Astrophysics Data System (ADS)

    Chen, Jianguo; Liu, Chenxi; Liu, Yongchang; Yan, Biyu; Li, Huijun

    2016-10-01

    In order to explore the influence of tantalum content on the microstructure and mechanical properties of low carbon RAFM (reduced activation ferritic/martensitic) steels, three low carbon RAFM steels with different tantalum contents (0%, 0.027%, 0.073%) were designed. The precipitation behavior and effect of precipitates on the mechanical properties of the Low-C RAFM steel were investigated. The results indicate that increase of tantalum content causes decrease of the prior austenite grain size and the amount of M23C6 carbides precipitated along prior austenite grain boundaries and packet boundaries as well as increase of the amount of MX nano-sized particles within intragranular regions. The impact properties of low carbon RAFM steels are excellent regardless of the tantalum content. The impact properties and hardness are obviously improved by increasing tantalum content, which may be related to increase of the number of MX and decrease of M23C6. Furthermore, the tensile properties at elevated temperature below 600 °C are hardly changed with increase of tantalum content, yet those at 800 °C are improved with increasing tantalum content. This implies that MX carbides would be more important for tensile properties at higher temperature.

  7. Thermal annealing recovery of fracture toughness in HT9 steel after irradation to high doses

    SciTech Connect

    Byun, Thak Sang; Baek, Jong-Hyuk; Anderoglu, Osman; Maloy, Stuart A.; Toloczko, Mychailo B.

    2013-08-03

    The HT9 ferritic/martensitic steel with a nominal chemistry of Fe(bal.)–12%Cr–1%MoVW has been used as a primary core material for fast fission reactors such as FFTF because of its high resistance to radiationinduced swelling and embrittlement. Both static and dynamic fracture test results have shown that the HT9 steel can become brittle when it is exposed to high dose irradiation at a relatively low temperature 430 °C). This article aims at a comprehensive discussion on the thermal annealing recovery of fracture toughness in the HT9 steel after irradiation up to 3–148 dpa at 378–504 °C. A specimen reuse technique has been established and applied to this study: the fracture specimens were tested Charpy specimens or broken halves of Charpy bars (13 3 4 mm). The post-anneal fracture test results indicated that much of the radiation-induced damage can be recovered by a simple thermal annealing schedule: the fracture toughness was incompletely recovered by 550 °C annealing, while nearly complete or complete recovery occurred after 650 °C annealing. This indicates that thermal annealing is a feasible damage mitigation technique for the reactor components made of HT9 steel. The partial recovery is probably due to the non-removable microstructural damages such as void or gas bubble formation, elemental segregation and precipitation.

  8. Friction stir welding of F82H steel for fusion applications

    NASA Astrophysics Data System (ADS)

    Noh, Sanghoon; Ando, Masami; Tanigawa, Hiroyasu; Fujii, Hidetoshi; Kimura, Akihiko

    2016-09-01

    In the present study, friction stir welding was employed to join F82H steels and develop a potential joining technique for a reduced activation ferritic/martensitic steel. The microstructures and mechanical properties on the joint region were investigated to evaluate the applicability of friction stir welding. F82H steel sheets were successfully butt-joined with various welding parameters. In welding conditions, 100 rpm and 100 mm/min, the stirred zone represented a comparable hardness distribution with a base metal. Stirred zone induced by 100 rpm reserved uniformly distributed precipitates and very fine ferritic grains, whereas the base metal showed a typical tempered martensite with precipitates on the prior austenite grain boundary and lath boundary. Although the tensile strength was decreased at 550 °C, the stirred zone treated at 100 rpm showed comparable tensile behavior with base metal up to 500 °C. Therefore, friction stir welding is considered a potential welding method to preserve the precipitates of F82H steel.

  9. Effect of Surface Roughness on Contact Angle Measurement of Nanofluid on Surface of Stainless Steel 304 by Sessile Drop Method

    NASA Astrophysics Data System (ADS)

    Prajitno, D. H.; Maulana, A.; Syarif, D. G.

    2016-08-01

    Contact angles play an important role in the mass and heat transfer. Stainless steel 304 has been used for nuclear power plan structure material until now. An experiment to measure contact angle of demineralized aqua and nanofluid containing nano particle of zirconia on metal surface of stainless steel 304 with sessile drop method was conducted. The measurement to measure the static contact angle and drop of nano fluid containing nano particle zirconia on stainless steel with different surface roughness was carried out. It was observed that stainless steel 304 was good hydrophylic properties with decreasing surface roughness of stainless steel during drop of aqua demineralized and nano fluid respectively. As a result the contact angle of demineralized aqua is decreased from 97.39 to 78.42 and contact angle of nano fluid from 94.3 to 67.50, respectively with decreasing surface roughness of stainless stee 304. Wettability of nanofluid on surface stainless steel 304 is better than aqua demineralized.

  10. The mechanical properties and microstructures of vanadium bearing high strength dual phase steels processed with continuous galvanizing line simulations

    NASA Astrophysics Data System (ADS)

    Gong, Yu

    For galvanized or galvannealed steels to be commercially successful, they must exhibit several attributes: (i) easy and inexpensive processing in the hot mill, cold mill and on the coating line, (ii) high strength with good formability and spot weldability, and (iii) good corrosion resistance. At the beginning of this thesis, compositions with a common base but containing various additions of V or Nb with or without high N were designed and subjected to Gleeble simulations of different galvanizing(GI), galvannealing(GA) and supercooling processing. The results revealed the phase balance was strongly influenced by the different microalloying additions, while the strengths of each phase were somewhat less affected. Our research revealed that the amount of austenite formed during intercritical annealing can be strongly influenced by the annealing temperature and the pre-annealing conditions of the hot band (coiling temperature) and cold band (% cold reduction). In the late part of this thesis, the base composition was a low carbon steel which would exhibit good spot weldability. To this steel were added two levels of Cr and Mo for strengthening the ferrite and increasing the hardenability of intercritically formed austenite. Also, these steels were produced with and without the addition of vanadium in an effort to further increase the strength. Since earlier studies revealed a relationship between the nature of the starting cold rolled microstructure and the response to CGL processing, the variables of hot band coiling temperature and level of cold reduction prior to annealing were also studied. Finally, in an effort to increase strength and ductility of both the final sheet (general formability) and the sheared edges of cold punched holes (local formability), a new thermal path was developed that replaced the conventional GI ferrite-martensite microstructure with a new ferrite-martensite-tempered martensite and retained austenite microstructure. The new

  11. Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential

    PubMed Central

    de Oliveira, Maíra Maciel Mattos; Brugnera, Danilo Florisvaldo; Alves, Eduardo; Piccoli, Roberta Hilsdorf

    2010-01-01

    An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4) stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 °C and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM) after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential. PMID:24031469

  12. Pulsed ion beam surface treatment for preparing rapidly solidified corrosion resistant steel and aluminum surfaces

    SciTech Connect

    Buchheit, R.G.; Maestas, L.M.; McIntyre, D.C.; Stinnett, R.W.; Greenly, J.B.

    1995-03-01

    Intense, pulsed ion beams were used to melt and rapidly resolidify Types 316F, 316L and sensitized 304 stainless steel surfaces to eliminate the negative effects of microstructural heterogeneity on localized corrosion resistance. Anodic polarization curves determined for 316F and 316L showed that passive current densities were reduced and pitting potentials were increased due to ion beam treatment. Type 304 samples sensitized at 600 C for 100 h showed no evidence of grain boundary attack when surfaces were ion beam treated. Equivalent ion beam treatments were conducted with a 6061-T6 aluminum alloy. Electrochemical impedance experiments conducted with this alloy exposed to an aerated chloride solution showed that the onset of pitting was delayed compared to untreated control samples.

  13. Oriented microtexturing on the surface of high-speed steel cutting tool

    NASA Astrophysics Data System (ADS)

    Filippov, A. V.; Tarasov, S. Yu.; Podgornyh, O. A.; Shamarin, N. N.; Filippova, E. O.

    2016-11-01

    Microtexturing the metal cutting tool surfaces is a novel technique intended for enhancing the workability of these tools. The microtexturing is used in machining the titanium alloys for air-space applications for reducing the adhesion wear of metal cutting blades. This paper is focused on forming the microtextured dotted, banded and overlapped areas on the surfaces of high-speed steel samples. The treated areas have been examined using laser scanning microscopy for the microtexture pattern and roughness. It has been shown that the microtextured surfaces obtained on the high-speed steel samples were free of cracks. Surface pattern and roughness of all three microtextured areas have been examined and analyzed.

  14. Colorizing of the stainless steel surface by single-beam direct femtosecond laser writing

    NASA Astrophysics Data System (ADS)

    Ahsan, Md. Shamim; Kim, Yeong Gyu; Lee, Man Seop

    2011-03-01

    This paper reports on the colorizing of the stainless steel surface by controlling the irradiation conditions of a single-beam femtosecond laser. We change the color of the stainless steel surface by femtosecond laser induced periodic self-organized nanogratings or microgratings on the sample surface. Colorizing of metal surface by periodic microholes, produced by femtosecond laser, is achieved for the first time. The laser modified stainless steel surfaces show different colors under different incident or azimuthal angles of the incident light, which changes in color indicate the dependence of the metal color on the angles (incident and azimuthal) of the incident light. We report, for the first time, the changes of metal color due to the change of the azimuthal angles of the incident light. Furthermore, the changes in the color of the laser modified metal surfaces are mainly due to the excitation of surface plasmon polaritons (SPPs) on the metal surface. The resonant angle of SPPs is different for different wavelength of light. As a result, under different incident or azimuthal angles different wavelength of light is trapped on the surface depending on the resonance for that particular wavelength; light of other wavelengths react naturally and contributes for the color change of the stainless steel surfaces. Finally, we discovered that the nanostructures produced inside the self-organized nanogratings and microholes play important roles for the propagation of the SPPs in parallel with the nanogratings and mcroholes, which nanostructures are responsible for a complex SPPs excitation on the sample surface.

  15. Silver deposition on stainless steel container surfaces in contact with disinfectant silver aqueous solutions

    NASA Astrophysics Data System (ADS)

    Petala, M.; Tsiridis, V.; Mintsouli, I.; Pliatsikas, N.; Spanos, Th.; Rebeyre, P.; Darakas, E.; Patsalas, P.; Vourlias, G.; Kostoglou, M.; Sotiropoulos, S.; Karapantsios, Th.

    2017-02-01

    Silver is the preservative used on the Russian segment of the International Space Station (ISS) to prevent microbial proliferation within potable water supplies. Yet, in the frame of the European Automated Transfer Vehicle (ATV) missions to ISS, silver depletion from water has been detected during ground transportation of this water to launch site, thereby indicating a degradation of water quality. This study investigates the silver loss from water when in contact with stainless steel surfaces. Experiments are conducted with several types of stainless steel surfaces being exposed to water containing 10 or 0.5 mg/L silver ions. Results show that silver deposits on stainless steel surfaces even when a passivation layer protects the metallic surface. The highest protection to silver deposition is offered by acid passivated and electropolished SS 316L. SEM and XPS experiments were carried out at several locations of the sample area that was in contact with the Ag solution and found similar morphological (SEM) and compositional (sputter-etch XPS) results. The results reveal that silver deposits uniformly across the wetted surface to a thickness larger than 3 nm. Moreover, evidence is provided that silver deposits in its metallic form on all stainless steel surfaces, in line with a galvanic deposition mechanism. Combination of ICP-MS and XPS results suggests a mechanism for Ag deposition/reduction with simultaneous substrate oxidation resulting in oxide growth at the exposed stainless steel surface.

  16. Ozone decay on stainless steel and sugarcane bagasse surfaces

    NASA Astrophysics Data System (ADS)

    Souza-Corrêa, Jorge A.; Oliveira, Carlos; Amorim, Jayr

    2013-07-01

    Ozone was generated using dielectric barrier discharges at atmospheric pressure to treat sugarcane bagasse for bioethanol production. It was shown that interaction of ozone molecules with the pretreatment reactor wall (stainless steel) needs to be considered during bagasse oxidation in order to evaluate the pretreatment efficiency. The decomposition coefficients for ozone on both materials were determined to be (3.3 ± 0.2) × 10-8 for stainless steel and (2.0 ± 0.3) × 10-7 for bagasse. The results have indicated that ozone decomposition has occurred more efficiently on the biomass material.

  17. A real-time surface inspection system for precision steel balls based on machine vision

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Ji; Tsai, Jhy-Cherng; Hsu, Ya-Chen

    2016-07-01

    Precision steel balls are one of the most fundament components for motion and power transmission parts and they are widely used in industrial machinery and the automotive industry. As precision balls are crucial for the quality of these products, there is an urgent need to develop a fast and robust system for inspecting defects of precision steel balls. In this paper, a real-time system for inspecting surface defects of precision steel balls is developed based on machine vision. The developed system integrates a dual-lighting system, an unfolding mechanism and inspection algorithms for real-time signal processing and defect detection. The developed system is tested under feeding speeds of 4 pcs s-1 with a detection rate of 99.94% and an error rate of 0.10%. The minimum detectable surface flaw area is 0.01 mm2, which meets the requirement for inspecting ISO grade 100 precision steel balls.

  18. Development of new generation reduced activation ferritic-martenstic steels for advanced fusion reactors

    SciTech Connect

    Tan, Lizhen; Snead, Lance Lewis; Katoh, Yutai

    2016-05-26

    International development of reduced activation ferritic-martensitic (RAFM) steels has focused on 9 wt percentage Cr, which primarily contain M23C6 (M = Cr-rich) and small amounts of MX (M = Ta/V, X = C/N) precipitates, not adequate to maintain strength and creep resistance above ~500 °C. To enable applications at higher temperatures for better thermal efficiency of fusion reactors, computational alloy thermodynamics coupled with strength modeling have been employed to explore a new generation RAFM steels. The new alloys are designed to significantly increase the amount of MX nanoprecipitates, which are manufacturable through standard and scalable industrial steelmaking methods. Preliminary experimental results of the developed new alloys demonstrated noticeably increased amount of MX, favoring significantly improved strength, creep resistance, and Charpy impact toughness as compared to current RAFM steels. Furthermore, the strength and creep resistance were comparable or approaching to the lower bound of, but impact toughness was noticeably superior to 9–20Cr oxide dispersion-strengthened ferritic alloys.

  19. Development of new generation reduced activation ferritic-martenstic steels for advanced fusion reactors

    DOE PAGES

    Tan, Lizhen; Snead, Lance Lewis; Katoh, Yutai

    2016-05-26

    International development of reduced activation ferritic-martensitic (RAFM) steels has focused on 9 wt percentage Cr, which primarily contain M23C6 (M = Cr-rich) and small amounts of MX (M = Ta/V, X = C/N) precipitates, not adequate to maintain strength and creep resistance above ~500 °C. To enable applications at higher temperatures for better thermal efficiency of fusion reactors, computational alloy thermodynamics coupled with strength modeling have been employed to explore a new generation RAFM steels. The new alloys are designed to significantly increase the amount of MX nanoprecipitates, which are manufacturable through standard and scalable industrial steelmaking methods. Preliminary experimentalmore » results of the developed new alloys demonstrated noticeably increased amount of MX, favoring significantly improved strength, creep resistance, and Charpy impact toughness as compared to current RAFM steels. Furthermore, the strength and creep resistance were comparable or approaching to the lower bound of, but impact toughness was noticeably superior to 9–20Cr oxide dispersion-strengthened ferritic alloys.« less

  20. Study of martensitic-ferritic dual phase steels produced by hot stamping

    NASA Astrophysics Data System (ADS)

    Erişir, E.; Bilir, O. G.

    2017-02-01

    The effects of heat treatment and initial microstructure on tensile properties of 22MnB5 and 30MnB5 high-strength hot stamping steels with martensite-ferrite matrix were investigated. Hot stamping steels possessed limited elongations of about 5% in a tensile strength ranging from 1300 to 1500 MPa when quenched at temperatures above A3 temperatures. The total elongations were tried to improve by partial austenization between Ac1 and Ac3 temperature and quenching. Ac1 and Ac3 temperatures were calculated via ThermoCalc. Microstructural characterization was made by using Light Microscope and Scanning Electron Microscope. Microstructure is composed of ferrite+martensite. It was seen that annealing temperature affects the volume fraction of phases. It was concluded that initial microstructure is an important parameter for the final microstructure. This method can be used for automobile parts which require higher TE with sufficient yield and tensile strength. Also this process may be a way of using Zn coated steel sheets in hot stamping process.

  1. Non-vacuum electron-beam carburizing and surface hardening of mild steel

    NASA Astrophysics Data System (ADS)

    Bataev, I. A.; Golkovskii, M. G.; Losinskaya, A. A.; Bataev, A. A.; Popelyukh, A. I.; Hassel, T.; Golovin, D. D.

    2014-12-01

    In this paper, we study the structure, microhardness, and tribological properties of surface layers of mild (0.19% C) steel, which was formed by electron-beam cladding with an iron-graphite powder mixture followed by quenching and tempering. A 1.4 MeV electron beam that was extracted into air was used. Cladding of steel with the iron-graphite mixture at a beam current of 24 and 26 mA formed a hypoeutectic cast iron layer (2.19% C) and a hypereutectoid steel (1.57% C) layer, which were 2.0 and 2.6 mm thick, respectively. The microhardness of the surface-quenched and tempered steel and cast iron layers was 7 and 8 GPa, respectively. Electron-beam quenching of the surface layers of hypoeutectic cast iron was accompanied with multiple cracking. During the quenching of the 1.57% C steel layer, crack formation was not observed. In friction tests against fixed and loose abrasive particles, the surface layers of hypereutectoid steel and hypoeutectic cast iron that were produced by electron-beam cladding and quenching had lower wear rates than mild steel after pack carburizing, quenching, and tempering. In the sliding wear tests, the cast iron clad layer, which was subjected to electron-beam quenching and tempering, exhibited the highest wear resistance. Electron-beam treatment can be used to harden local areas of large workpieces. It is reasonable to treat clad layers of high-carbon steel with electron-beam quenching and tempering. To prevent multiple cracking, white cast iron layers should not be quenched.

  2. Direct patterning in sub-surface of stainless steel using laser pulses.

    PubMed

    Li, Z L; Liu, T; Khin, C C; Tan, A C; Khoong, L E; Zheng, H Y; Zhou, W

    2010-07-19

    This paper reports for the first time on the direct creating microcavities in sub-surface of stainless steel using a single Nd:YAG laser pulse. The low peak power density is used in the process, which is in the order of 1 MW/cm(2). The formation of the microcavities in the sub-surface of stainless steel is an evidence of volume expulsion during laser-metal interaction. Direct patterning in the sub-surface of stainless steel is demonstrated by realizing a series of microcavities to form a pre-designed pattern. Potential applications of sub-surface patterning in metal, such as security marking, micro-heater, micro-insulator and micro-sensor, are discussed.

  3. Galvanic Liquid Applied Coating System for Protection of Embedded Steel Surfaces from Corrosion

    NASA Technical Reports Server (NTRS)

    Curran, Joseph; MacDowell, Louis; Voska, N. (Technical Monitor)

    2002-01-01

    The corrosion of reinforcing steel in concrete is an insidious problem for the Kennedy Space Center, government agencies, and the general public. Existing corrosion protection systems on the market are costly, complex, and time-consuming to install, require continuous maintenance and monitoring, and require specialized skills for installation. NASA's galvanic liquid-applied coating offers companies the ability to conveniently protect embedded steel rebar surfaces from corrosion. Liquid-applied inorganic galvanic coating contains one ore more of the following metallic particles: magnesium, zinc, or indium and may contain moisture attracting compounds that facilitate the protection process. The coating is applied to the outer surface of reinforced concrete so that electrical current is established between metallic particles and surfaces of embedded steel rebar; and electric (ionic) current is responsible for providing the necessary cathodic protection for embedded rebar surfaces.

  4. Hardness of Carburized Surfaces in 316LN Stainless Steel after Low Temperature Neutron Irradiation

    SciTech Connect

    Byun, TS

    2005-01-31

    A proprietary surface carburization treatment is being considered to minimize possible cavitation pitting of the inner surfaces of the stainless steel target vessel of the SNS. The treatment gives a large supersaturation of carbon in the surface layers and causes substantial hardening of the surface. To answer the question of whether such a hardened layer will remain hard and stable during neutron irradiation, specimens of the candidate materials were irradiated in the High Flux Isotope Reactor (HFIR) to an atomic displacement level of 1 dpa. Considerable radiation hardening occurred in annealed 316LN stainless steel and 20% cold rolled 316LN stainless steel, and lesser radiation hardening in Kolsterised layers on these materials. These observations coupled with optical microscopy examinations indicate that the carbon-supersaturated layers did not suffer radiation-induced decomposition and softening.

  5. Surface hardening of steel by boriding in a cold rf plasma

    NASA Technical Reports Server (NTRS)

    Finberg, I.; Avni, R.; Grill, A.; Spalvins, T.; Buckley, D. H.

    1985-01-01

    Scanning electron spectroscopy, X-ray diffractometry, Auger electron spectroscopy, and microhardness measurements, are used to study the surfaces of 4340-steel samples that have been borided in a cold RF plasma which had been initiated in a gas mixture of 2.7 percent diborane in Ar. As a result of the dislocation of the diborane in the plasma, boron is deposited on the surface of the steel substrate and two crystalline phases, tetragonal Fe2B and orthorhombic FeB, are formed. The formation of boride phases then increases the surface microhardness from 2650 MPa to a maximum value of 7740 MPa.

  6. Surface hardening of stainless steel by runaway electrons preionized diffuse discharge in air atmosphere

    NASA Astrophysics Data System (ADS)

    Erofeev, M. V.; Shulepov, M. A.; Oskomov, K. V.; Tarasenko, V. F.

    2015-11-01

    In this paper we present microhardness measurements of stainless steel surface treated by diffuse discharge in air atmosphere. The cleaning from carbon in comparison to the initial sample was observed at a depth exceeding 20 nm. The oxygen concentration was also increased in comparison to that in the initial sample at a depth of up to about 50 nm. Comparative analysis shows that after treatment the microhardness of stainless steel surface increased in 2 times due to interaction of near-surface layers with product of plasma chemical reactions produced in diffuse discharge.

  7. Improving intergranular corrosion resistance of sensitized type 316 austenitic stainless steel by laser surface melting

    NASA Astrophysics Data System (ADS)

    Mudali, U. K.; Dayal, R. K.

    1992-06-01

    An attempt was made to modify the surface microstructure of a sensitized austenitic stainless steel, without affecting the bulk properties, using laser surface melting techniques. AISI type 316 stainless steel specimens sensitized at 923 K for 20 hr were laser surface melted using a pulsed ruby laser at 6 J energy. Two successive pulses were given to ensure uniform melting and homogenization. The melted layers were characterized by small angle X- ray diffraction and scanning electron microscopy. Intergranular corrosion tests were carried out on the melted region as per ASTM A262 practice A (etch test) and electrochemical potentiokinetic reactivation test. The results indicated an improvement in the intergranular corrosion resistance after laser surface melting. The results are explained on the basis of homogeneous and nonsensitized microstructure obtained at the surface after laser surface melting. It is concluded that laser surface melting can be used as an in situ method to increase the life of a sensitized component by modifying the surface microstructure.

  8. PERFORMANCE IMPROVEMENT OF CREEP-RESISTANT FERRITIC STEEL WELDMENTS THROUGH THERMO-MECHANICAL TREATMENT AND ALLOY DESIGN

    SciTech Connect

    Yamamoto, Yukinori; Babu, Prof. Sudarsanam Suresh; Shassere, Benjamin; Yu, Xinghua

    2016-01-01

    Two different approaches have been proposed for improvement of cross-weld creep properties of the high temperature ferrous structural materials for fossil-fired energy applications. The traditional creep strength-enhanced ferritic (CSEF) steel weldments suffer from Type IV failures which occur at the fine-grained heat affected zone (FGHAZ). In order to minimize the premature failure at FGHAZ in the existing CSEF steels, such as modified 9Cr-1Mo ferritic-martensitic steels (Grade 91), a thermo-mechanical treatment consisting of aus-forging/rolling and subsequent aus-aging is proposed which promotes the formation of stable MX carbonitrides prior to martensitic transformation. Such MX remains undissolved during welding process, even in FGHAZ, which successfully improves the cross-weld creep properties. Another approach is to develop a new fully ferrtic, creep-resistant FeCrAl alloy which is essentially free from Type IV failure issues. Fe-30Cr-3Al base alloys with minor alloying additions were developed which achieved a combination of good oxidation/corrosion resistance and improved tensile and creep performance comparable or superior to Grade 92 steel.

  9. Prediction of yield stress in highly irradiated ferritic steels

    NASA Astrophysics Data System (ADS)

    Windsor, Colin G.; Cottrell, Geoff; Kemp, Richard

    2008-03-01

    The design of any fusion power plant requires information on the irradiation hardening of low-activation ferritic/martensitic steels beyond the range of most present measurements. Neural networks have been used by Kemp et al (J. Nucl. Mater. 348 311-28) to model the yield stress of some 1811 irradiated alloys. The same dataset has been used in this study, but has been divided into a training set containing the majority of the dataset with low irradiation levels, and a test set which contains just those alloys which have been irradiated above a given level. For example some 4.5% of the alloys were irradiated above 30 displacements per atom. For this 'prediction' problem it is found that simpler networks with fewer inputs are advantageous. By using target-driven dimensionality reduction, linear combinations of the atomic inputs reduce the test residual below that achievable by adding inputs from single atoms. It is postulated that these combinations represent 'mechanisms' for the prediction of irradiated yield stress.

  10. Materials design data for reduced activation martensitic steel type EUROFER

    NASA Astrophysics Data System (ADS)

    Tavassoli, A.-A. F.; Alamo, A.; Bedel, L.; Forest, L.; Gentzbittel, J.-M.; Rensman, J.-W.; Diegele, E.; Lindau, R.; Schirra, M.; Schmitt, R.; Schneider, H. C.; Petersen, C.; Lancha, A.-M.; Fernandez, P.; Filacchioni, G.; Maday, M. F.; Mergia, K.; Boukos, N.; Baluc; Spätig, P.; Alves, E.; Lucon, E.

    2004-08-01

    Materials design limits derived so far from the data generated in Europe for the reduced activation ferritic/martensitic (RAFM) steel type Eurofer are presented. These data address the short-term needs of the ITER Test Blanket Modules and a DEMOnstration fusion reactor. Products tested include plates, bars, tubes, TIG and EB welds, as well as powder consolidated blocks and solid-solid HIP joints. Effects of thermal ageing and low dose neutron irradiation are also included. Results are sorted and screened according to design code requirements before being introduced in reference databases. From the physical properties databases, variations of magnetic properties, modulus of elasticity, density, thermal conductivity, thermal diffusivity, specific heat, mean and instantaneous linear coefficients of thermal expansion versus temperature are derived. From the tensile and creep properties databases design allowable stresses are derived. From the instrumented Charpy impact and fracture toughness databases, ductile to brittle transition temperature, toughness and behavior of materials in different fracture modes are evaluated. From the fatigue database, total strain range versus number of cycles to failure curves are plotted and used to derive fatigue design curves. Cyclic curves are also derived and compared with monotonic hardening curves. Finally, irradiated and aged materials data are compared to ensure that the safety margins incorporated in unirradiated design limits are not exceeded.

  11. Improved Criteria for Acceptable Yield Point Elongation in Surface Critical Steels

    SciTech Connect

    Dr. David Matlock; Dr. John Speer

    2007-05-30

    Yield point elongation (YPE) is considered undesirable in surface critical applications where steel is formed since "strain lines" or Luders bands are created during forming. This project will examine in detail the formation of luders bands in industrially relevant strain states including the influence of substrate properties and coatings on Luders appearance. Mechanical testing and surface profilometry were the primary methods of investigation.

  12. Changes Found on Run-In and Scuffed Surfaces of Steel Chrome Plate, and Cast Iron

    NASA Technical Reports Server (NTRS)

    Good, J. N.; Godfrey, Douglas

    1947-01-01

    A study was made of run-in and scuffed steel, chrome-plate, and cast-iron surfaces. X-ray and electron diffraction techniques, micro-hardness determinations, and microscopy were used. Surface changes varied and were found to include three classes: chemical reaction, hardening, and crystallite-size alteration. The principal chemical reactions were oxidation and carburization.

  13. COMPARISON OF SCANNING ELECTRON AND ATOMIC FORCE MICROSCOPY OF SURFACE FINISHES ON STAINLESS STEEL THAT REDUCE BACTERIAL ATTACHMENT

    EPA Science Inventory

    Bacteria adhere to food products and processing surfaces that can cross-contaminate other products and work surfaces (Arnold, 1998). Using materials for food processing surfaces that are resistant to bacterial contamination could enhance food safety. Stainless steel, although sus...

  14. Surface Selective Oxidation of Sn-Added CMnSi TRIP Steel

    NASA Astrophysics Data System (ADS)

    Cho, Lawrence; Seo, Eun Jung; Jung, Geun Su; Suh, Dong Woo; De Cooman, Bruno C.

    2016-04-01

    The influence of the addition of Sn on the selective oxidation and the reactive wetting of CMnSi transformation-induced plasticity (TRIP) steels was studied by means of galvanizing simulator tests. A reference TRIP steel and TRIP steels containing Sn in the range of 0.05 to 1 wt pct were intercritically annealed at 1093 K (820 °C) in an N2+ 5 pct H2 gas atmosphere with a dew point of -60 °C. The thin-film oxides formed on the surface of the Sn-added CMnSi TRIP steel were investigated using transmission electron microscopy and 3-dimensional atom probe tomography. The addition of Sn (≥0.05 wt pct) changed the morphology of the xMnO·SiO2 surface oxides from a continuous film morphology to a lens-shaped island morphology. It also suppressed the formation of the Mn-rich oxides of MnO and 2MnO·SiO2. The changes in the morphology and chemistry of the surface oxides were clearly related to the surface segregation of Sn, which appeared to result in a decrease of the oxygen permeability at the surface. The formation of lens-shaped oxides improved the wettability of the CMnSi TRIP steel surface by the molten Zn. The improved wetting effect was attributed to an increased area fraction of the surface where the oxide layer was thinner. This enabled a direct, unhindered reaction between Fe and the Al in the liquid Zn and the formation of the inhibition layer in the initial stages of the hot dipping. The addition of a small amount of Sn was also found to decrease significantly the density of Zn-coating defects on CMnSi TRIP steel.

  15. AISI/DOE Technology Roadmap Program: Improved Surface Quality of Exposed Automotive Sheet Steels

    SciTech Connect

    John G. Speer; David K. Matlock; Noel Meyers; Young-Min Choi

    2002-10-10

    Surface quality of sheet steels is an important economic and technical issue for applications such as critical automotive surfaces. This project was therefore initiated to develop a more quantitative methodology for measuring surface imperfections, and to assess their response to forming and painting, particularly with respect to their visibility or invisibility after painting. The objectives were met, and included evaluation of a variety of imperfections present on commercial sheet surfaces or simulated using methods developed in the laboratory. The results are expected to have significant implications with respect to the methodology for assessing surface imperfections, development of quantitative criteria for surface inspection, and understanding and improving key painting process characteristics that influence the perceived quality of sheet steel surfaces.

  16. Rapid surface hardening and enhanced tribological performance of 4140 steel by friction stir processing

    SciTech Connect

    Lorenzo-Martin, Cinta; Ajayi, Oyelayo O.

    2015-06-06

    Tribological performance of steel materials can be substantially enhanced by various thermal surface hardening processes. For relatively low-carbon steel alloys, case carburization is often used to improve surface performance and durability. If the carbon content of steel is high enough (>0.4%), thermal treatments such as induction, flame, laser, etc. can produce adequate surface hardening without the need for surface compositional change. This paper presents an experimental study of the use of friction stir processing (FSP) as a means to hardened surface layer in AISI 4140 steel. The impacts of this surface hardening process on the friction and wear performance were evaluated under both dry and lubricated contact conditions in reciprocating sliding. FSP produced the same level of hardening and superior tribological performance when compared to conventional thermal treatment, using only 10% of the energy and without the need for quenching treatments. With FSP surface hardness of about 7.8 GPa (62 Rc) was achieved while water quenching conventional heat treatment produced about 7.5 GPa (61 Rc) hardness. Microstructural analysis showed that both FSP and conventional heat treatment produced martensite. Although the friction behavior for FSP treated surfaces and the conventional heat treatment were about the same, the wear in FSP processed surfaces was reduced by almost 2× that of conventional heat treated surfaces. Furthermore, the superior performance is attributed to the observed grain refinement accompanying the FSP treatment in addition to the formation of martensite. As it relates to tribological performance, this study shows FSP to be an effective, highly energy efficient, and environmental friendly (green) alternative to conventional heat treatment for steel.

  17. Rapid surface hardening and enhanced tribological performance of 4140 steel by friction stir processing

    DOE PAGES

    Lorenzo-Martin, Cinta; Ajayi, Oyelayo O.

    2015-06-06

    Tribological performance of steel materials can be substantially enhanced by various thermal surface hardening processes. For relatively low-carbon steel alloys, case carburization is often used to improve surface performance and durability. If the carbon content of steel is high enough (>0.4%), thermal treatments such as induction, flame, laser, etc. can produce adequate surface hardening without the need for surface compositional change. This paper presents an experimental study of the use of friction stir processing (FSP) as a means to hardened surface layer in AISI 4140 steel. The impacts of this surface hardening process on the friction and wear performance weremore » evaluated under both dry and lubricated contact conditions in reciprocating sliding. FSP produced the same level of hardening and superior tribological performance when compared to conventional thermal treatment, using only 10% of the energy and without the need for quenching treatments. With FSP surface hardness of about 7.8 GPa (62 Rc) was achieved while water quenching conventional heat treatment produced about 7.5 GPa (61 Rc) hardness. Microstructural analysis showed that both FSP and conventional heat treatment produced martensite. Although the friction behavior for FSP treated surfaces and the conventional heat treatment were about the same, the wear in FSP processed surfaces was reduced by almost 2× that of conventional heat treated surfaces. Furthermore, the superior performance is attributed to the observed grain refinement accompanying the FSP treatment in addition to the formation of martensite. As it relates to tribological performance, this study shows FSP to be an effective, highly energy efficient, and environmental friendly (green) alternative to conventional heat treatment for steel.« less

  18. Frication Property of Mo-Cr-Infiltrated Steel Layer by Plasma Surface Metallurgy

    NASA Astrophysics Data System (ADS)

    Xu, Jinyong; Kang, Zhicheng; Liu, Yanping; Wang, Jianzhong; Gao, Yuan; Xu, Zhong

    2006-07-01

    Introduced in this article is the technique to acquire a high performance strengthened layer on carbon steel samples, namely, plasma alloying on the surface of Q235 steel and heat treatment technology. With this technique the alloying elements of Mo, Cr, and C can be obtained on the surface of Q235 steel samples. The content of the constituent elements is approximately up to high speed steels (HSS). The surface property required for the HSS after hardening and low tempering is attained. In the test, the alloying elements Mo and Cr were penetrated into the Q235 steel samples by glow discharge sputtering so that the content of the alloyed layer on the surface of the Q235 steel samples was about 20% Mo and 10% Cr. Two kinds of experiments were conducted. One was to carry out ultra-saturated carburization. The alloyed layer's composition was similar to molybdenum HSS with surface carburizing of more than 2.0%. The carbides of the alloyed layer were compact, uniform and disperse without a coarse eutectic ledeburite structure. The another was ion nitriding after the alloying elements of Mo and Cr were penetrated. The first process included hardening with low tempering and hardening with cryogenic treatment for 2 hr and low tempering. The second one was ion nitriding only. It was found that the surface hardness after cryogenic treatment is up to 1600 HV, much higher than that without cryogenic treatment. The abrasion test results indicate that, without the penetrated alloy elements Mo and Cr and without cryogenic treatment and ion nitriding, the friction coefficient is lower by one order of magnitude. The change in relative resistance is similar to the change in the friction coefficient, but without a proportional relationship.

  19. High-speed measurements of steel-plate deformations during laser surface processing.

    PubMed

    Jezersek, Matija; Gruden, Valter; Mozina, Janez

    2004-10-04

    In this paper we present a novel approach to monitoring the deformations of a steel plate's surface during various types of laser processing, e.g., engraving, marking, cutting, bending, and welding. The measuring system is based on a laser triangulation principle, where the laser projector generates multiple lines simultaneously. This enables us to measure the shape of the surface with a high sampling rate (80 Hz with our camera) and high accuracy (+/-7 microm). The measurements of steel-plate deformations for plates of different thickness and with different illumination patterns are presented graphically and in an animation.

  20. The effect of surface layer properties on bendability of ultra-high strength steel

    NASA Astrophysics Data System (ADS)

    Arola, Anna-Maija; Kaijalainen, Antti; Kesti, Vili

    2016-10-01

    Bendability is an important property for ultra-high strength steel because air-bending is the most common forming process for the material. In this paper the bendability of two ultra-high strength steels with similar mechanical properties but different bendability was investigated using tensile testing with optical strain measurements. The tensile tests were conducted also for specimens cut from the surface layer and the middle layer of the sheet. It was discovered that the mechanical properties of the surface of the sheet affect the bendability in great manner.

  1. Optimization and testing results of Zr-bearing ferritic steels

    SciTech Connect

    Tan, Lizhen; Yang, Ying; Tyburska-Puschel, Beata; Sridharan, K.

    2014-09-01

    The mission of the Nuclear Energy Enabling Technologies (NEET) program is to develop crosscutting technologies for nuclear energy applications. Advanced structural materials with superior performance at elevated temperatures are always desired for nuclear reactors, which can improve reactor economics, safety margins, and design flexibility. They benefit not only new reactors, including advanced light water reactors (LWRs) and fast reactors such as sodium-cooled fast reactor (SFR) that is primarily designed for management of high-level wastes, but also life extension of the existing fleet when component exchange is needed. Developing and utilizing the modern materials science tools (experimental, theoretical, and computational tools) is an important path to more efficient alloy development and process optimization. Ferritic-martensitic (FM) steels are important structural materials for nuclear reactors due to their advantages over other applicable materials like austenitic stainless steels, notably their resistance to void swelling, low thermal expansion coefficients, and higher thermal conductivity. However, traditional FM steels exhibit a noticeable yield strength reduction at elevated temperatures above ~500°C, which limits their applications in advanced nuclear reactors which target operating temperatures at 650°C or higher. Although oxide-dispersion-strengthened (ODS) ferritic steels have shown excellent high-temperature performance, their extremely high cost, limited size and fabricability of products, as well as the great difficulty with welding and joining, have limited or precluded their commercial applications. Zirconium has shown many benefits to Fe-base alloys such as grain refinement, improved phase stability, and reduced radiation-induced segregation. The ultimate goal of this project is, with the aid of computational modeling tools, to accelerate the development of a new generation of Zr-bearing ferritic alloys to be fabricated using conventional

  2. Analysis of the influence of electrolyte on surface finish in electropolished stainless steel

    NASA Astrophysics Data System (ADS)

    Hernando, M.; Núñez, P. J.; García, E.; Trujillo, R.

    2012-04-01

    Electropolishing is a surface finishing process of metals and alloys that enhances brilliant surface finishes with low surface roughness values. The most widely used electrolytes for the electropolishing of stainless steel are varying concentrations of phosphoric and sulphuric acid, and occasionally additives such as chromic acid. The objective of this study was to assess the performance of three commonly used industrial electrolytes in terms of the surface finish of electropolished stainless steel AISI 316L. Each electrolyte had varying sulphuric-phosphoric acid combinations with or without chromic acid. The following electropolishing conditions were assessed: current density, bath temperature, electropolishing time, and initial surface texture. The results revealed that adding chromic acid to the electrolyte did not significantly enhance surface finish, and electropolishing ranges were quite similar for all three electrolytes.

  3. Cost-Benefit Analysis For Alternative Low-Emission Surface Preparation/ Depainting Technologies for Structural Steel

    NASA Technical Reports Server (NTRS)

    Lewis, Pattie

    2007-01-01

    Stennis Space Center (SSC), Kennedy Space Center (KSC) and Air Force Space Command (AFSPC) identified particulate emissions and waste generated from the depainting process of steel structures as hazardous materials to be eliminated or reduced. A Potential Alternatives Report, Potential Alternatives Report for Validation of Alternative Low Emission Surface Preparation/Depainting Technologies for Structural Steel, provided a technical analyses of identified alternatives to the current coating removal processes, criteria used to select alternatives for further analysis, and a list of those alternatives recommended for testing. The initial coating removal alternatives list was compiled using literature searches and stakeholder recommendations. The involved project participants initially considered approximately 13 alternatives. In late 2003, core project members selected the following depainting processes to be further evaluated: (1) Plastic Blast Media-Quickstrip(R)-A. (2) Hard Abrasive-Steel-Magic(R). (3) Sponge Blasting-Sponge-Jet(R). (4) Liquid Nitrogen-NItroJet(R). (5) Mechanical Removal with Vacuum Attachment-DESCO and OCM Clean-Air (6) Laser Coating Removal Alternatives were tested in accordance with the Joint Test Protocol for Validation of Alternative Low-Emission Surface Preparation/Depainting Technologies for Structural Steel, and the Field Evaluation Test Plan for Validation of Alternative Low-Emission Surface Preparation/Depainting Technologies for Structural Steel. Results of the testing are documented in the Joint Test Report. This Cost-Benefit Analysis (CBA) focuses on the three alternatives (Quickstrip(R)-A, SteelMagic (R), and Sponge-Jet(R)) that were considered viable alternatives for large area operations based on the results of the field demonstration and lab testing. This CBA was created to help participants determine if implementation of the candidate alternatives is economically justified. Each of the alternatives examined reduced Environmental

  4. High surface area stainless steel brushes as cathodes in microbial electrolysis cells.

    PubMed

    Call, Douglas F; Merrill, Matthew D; Logan, Bruce E

    2009-03-15

    Microbial electrolysis cells (MECs) are an efficient technology for generating hydrogen gas from organic matter, but alternatives to precious metals are needed for cathode catalysts. We show here that high surface area stainless steel brush cathodes produce hydrogen at rates and efficiencies similar to those achieved with platinum-catalyzed carbon cloth cathodes in single-chamber MECs. Using a stainless steel brush cathode with a specific surface area of 810 m2/m3, hydrogen was produced at a rate of 1.7 +/- 0.1 m3-H2/m3-d (current density of 188 +/- 10 A/m3) at an applied voltage of 0.6 V. The energy efficiency relative to the electrical energy input was 221 +/- 8%, and the overall energy efficiency was 78 +/- 5% based on both electrical energy and substrate utilization. These values compare well to previous results obtained using platinum on flat carbon cathodes in a similar system. Reducing the cathode surface area by 75% decreased performance from 91 +/- 3 A/m3 to 78 +/- 4 A/m3. A brush cathode with graphite instead of stainless steel and a specific surface area of 4600 m2/m3 generated substantially less current (1.7 +/- 0.0 A/m3), and a flat stainless steel cathode (25 m2/m3) produced 64 +/- 1 A/m3, demonstrating that both the stainless steel and the large surface area contributed to high current densities. Linear sweep voltammetry showed that the stainless steel brush cathodes both reduced the overpotential needed for hydrogen evolution and exhibited a decrease in overpotential over time as a result of activation. These results demonstrate for the first time that hydrogen production can be achieved at rates comparable to those with precious metal catalysts in MECs without the need for expensive cathodes.

  5. Laser Surface Modification of H13 Die Steel using Different Laser Spot Sizes

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Naher, S.; Brabazon, D.

    2011-05-01

    This paper presents a laser surface modification process of AISI H13 tool steel using three sizes of laser spot with an aim to achieve reduced grain size and surface roughness. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). Metallographic study and image analysis were done to measure the grain size and the modified surface roughness was measured using two-dimensional surface profilometer. From metallographic study, the smallest grain sizes measured by laser modified surface were between 0.51 μm and 2.54 μm. The minimum surface roughness, Ra, recorded was 3.0 μm. This surface roughness of the modified die steel is similar to the surface quality of cast products. The grain size correlation with hardness followed the findings correlate with Hall-Petch relationship. The potential found for increase in surface hardness represents an important method to sustain tooling life.

  6. Nanoscale evaluation of laser-based surface treated 12Ni maraging steel

    NASA Astrophysics Data System (ADS)

    Grum, J.; Slabe, J. M.

    2005-07-01

    Maraging steels are used in several high-tech areas. Among them are highly thermo-mechanically loaded vital parts of die casting dies for pressure die casting of aluminium and magnesium alloys. From the economic point of view, the operation life of dies is extremely important to the price of the castings. Operational life can be successfully extended by a regular maintenance of die parts. Laser surfacing is a very promising process for rebuilding of worn out surfaces of vital die parts. In this research, the state in the maraging steel 1.2799 (DIN) after the application of laser surfacing process has been analysed using scanning electron microscope. The analysis revealed diverse microstructure through-depth of the laser-surfaced specimens. On the basis of the estimated size and volume fraction of the nano-precipitates in the individual microstructure zones located through-depth of the heat-affected zone, a through-depth variation of microhardness was predicted. The results are supported by Vickers microhardness tests. It was confirmed that the mechanical properties of the 1.2799 maraging steel strongly depend on the characteristic at the nano or micro level. Some of the results obtained can be also applied to laser surface heat treatment of maraging steels.

  7. Surface characteristics and mechanical properties of high-strength steel wires in corrosive conditions

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Li, Shunlong; Li, Hui; Yan, Weiming

    2013-04-01

    Cables are always a critical and vulnerable type of structural components in a long-span cable-stayed bridge in normal operation conditions. This paper presents the surface characteristics and mechanical performance of high-strength steel wires in simulated corrosive conditions. Four stress level (0MPa, 300MPa, 400MPa and 500MPa) steel wires were placed under nine different corrosive exposure periods based on the Salt Spray Test Standards ISO 9227:1990. The geometric feathers of the corroded steel wire surface were illustrated by using fractal dimension analysis. The mechanical performance index including yielding strength, ultimate strength and elastic modulus at different periods and stress levels were tested. The uniform and pitting corrosion depth prediction model, strength degradation prediction model as well as the relationship between strength degradation probability distribution and corrosion crack depth would be established in this study.

  8. Uncertainty studies of topographical measurements on steel surface corrosion by 3D scanning electron microscopy.

    PubMed

    Kang, K W; Pereda, M D; Canafoglia, M E; Bilmes, P; Llorente, C; Bonetto, R

    2012-02-01

    Pitting corrosion is a damage mechanism quite serious and dangerous in both carbon steel boiler tubes for power plants which are vital to most industries and stainless steels for orthopedic human implants whose demand, due to the increase of life expectation and rate of traffic accidents, has sharply increased. Reliable methods to characterize this kind of damage are becoming increasingly necessary, when trying to evaluate the advance of damage and to establish the best procedures for component inspection in order to determine remaining lives and failure mitigation. A study about the uncertainties on the topographies of corrosion pits from 3D SEM images, obtained at low magnifications (where errors are greater) and different stage tilt angles were carried out using an in-house software previously developed. Additionally, measurements of pit depths on biomaterial surfaces, subjected to two different surface treatments on stainless steels, were carried out. The different depth distributions observed were in agreement with electrochemical measurements.

  9. Development of rapidly quenched brazing foils to join tungsten alloys with ferritic steel

    NASA Astrophysics Data System (ADS)

    Kalin, B. A.; Fedotov, V. T.; Sevrjukov, O. N.; Moeslang, A.; Rohde, M.

    2004-08-01

    Results on rapidly solidified filler metals for tungsten brazing are presented. A rapidly quenched foil-type filler metal based on Ni bal-15Cr-4Mo-4Fe-(0.5-1.0)V-7.5Si-1.5B was developed to braze tungsten to ferritic/martensitic Crl3Mo2NbVB steel (FS) for helium gas cooled divertors and plasma facing components. Polycrystalline W-2CeO 2 and monocrystalline pure tungsten were brazed to the steel under vacuum at 1150 °C, using a 0.5 mm thick foil spacer made of a 50Fe-50Ni alloy. As a result of thermocycling tests (100 cycles between 700 °C/20 min and air-water cooling/3-5 min) on brazed joints, tungsten powder metallurgically processed W-2CeO 2 failed due to residual stresses, whereas the brazed joint with zone-melted monocrystalline tungsten withstood the thermocycling tests.

  10. Effects of Strain Rates on Mechanical Properties and Fracture Mechanism of DP780 Dual Phase Steel

    NASA Astrophysics Data System (ADS)

    Li, Shengci; Kang, Yonglin; Zhu, Guoming; Kuang, Shuang

    2015-06-01

    The mechanical properties of DP780 dual phase steel were measured by quasi-static and high-speed tensile tests at strain rates between 0.001 and 1000 s-1 at room temperature. The deformation and fracture mechanisms were analyzed by observation of the tensile fracture and microstructure near the fracture. Dynamic factor and feret ratio quantitative methods were applied to study the effect of strain rate on the microstructure and properties of DP780 steel. The constitutive relation was described by a modified Johnson-Cook and Zerilli-Armstrong model. The results showed that the strain rate sensitivity of yield strength is bigger than that of ultimate tensile strength; as strain rate increased, the formation of microcracks and voids at the ferrite/martensite interface can be alleviated; the strain rate effect is unevenly distributed in the plastic deformation region. Moreover, both models can effectively describe the experimental results, while the modified Zerilli-Armstrong model is more accurate because the strain-hardening rate of this model is independent of strain rate.

  11. Positron annihilation Doppler broadening spectroscopy study on Fe-ion irradiated NHS steel

    NASA Astrophysics Data System (ADS)

    Zhu, Huiping; Wang, Zhiguang; Gao, Xing; Cui, Minghuan; Li, Bingsheng; Sun, Jianrong; Yao, Cunfeng; Wei, Kongfang; Shen, Tielong; Pang, Lilong; Zhu, Yabin; Li, Yuanfei; Wang, Ji; Song, Peng; Zhang, Peng; Cao, Xingzhong

    2015-02-01

    In order to study the evolution of irradiation-induced vacancy-type defects at different irradiation fluences and temperatures, a new type of ferritic/martensitic (F/M) steel named NHS (Novel High Silicon) was irradiated by 3.25 MeV Fe-ion at room temperature and 723 K to fluences of 4.3 × 1015 and 1.7 × 1016 ions/cm2. After irradiation, vacancy-type defects were investigated with variable-energy positron beam Doppler broadening spectra. Energetic Fe-ions produced a large number of vacancy-type defects in the NHS steel, but one single main type of vacancy-type defect was observed in both unirradiated and irradiated samples. The concentration of vacancy-type defects decreased with increasing temperature. With the increase of irradiation fluence, the concentration of vacancy-type defects increased in the sample irradiated at RT, whereas for the sample irradiated at 723 K, it decreased. The enhanced recombination between vacancies and excess interstitial Fe atoms from deeper layers, and high diffusion rate of self-interstitial atoms further improved by diffusion via grain boundary and dislocations at high temperature, are thought to be the main reasons for the reversed trend of vacancy-type defects between the samples irradiated at RT and 723 K.

  12. Fabrication of biomimetic superhydrophobic steel surface under an oxygen rich environment

    NASA Astrophysics Data System (ADS)

    Yin, Liang; Zhang, Haifeng; Li, Yuyang; Wang, Yang; Zhang, Ruimin; Chen, Weiping; Liu, Xiaowei

    2016-09-01

    A novel and facile approach was proposed to fabricate superhydrophobic surface with similar micro- and nanostructures of lotus leaf on the steel foil. The acidic solution was used to grow Fe3O4 nanosheet films consisted of hydrochloric acid and potassium chloride under an O2 rich environment. The as-prepared superhydrophobic steel surfaces had water CA (contact angle) of 166 ± 2°. The water SA (sliding angle) was less than 2°. In order to estimate the drag reduction property of the as-prepared surface, the experimental setup of the liquid-solid friction drag was proposed. The drag reduction ratio for superhydrophobic surface was 61.3% compare with untreated surface at a flow velocity of 1.66 m s-1.

  13. Detection of surface defects on raw milled steel blocks using range imaging

    NASA Astrophysics Data System (ADS)

    Pernkopf, Franz; Pernkopf, Friedrich; O'Leary, Paul

    2002-03-01

    This paper shows an efficient and reliable method for the detection of surface defects with a three dimensional characteristic whereby the surface reflection properties are altering strongly. Due to this fact traditional intensity imaging techniques yield inferior performance. Therefore, light sectioning in conjunction with fast imaging sensors is applied to gather the range image of the steel block. Two different approaches for defect detection are treated, whereby the first algorithm is based on a line-wise examination of the acquired profiles by unwrapping the surface using spline interpolation. The noise in the unwrapped orthogonal distance may be reduced by applying statistical measures. The second method refers to surface segments and is based on the mean square error between the segment and its approximation gained from singular value decomposition. Due to vibrations the acquired profiles are arbitrary located within a range of a few millimeters which requires a geometric transformation to reconstruct the three dimensional surface of the steel block.

  14. Novel technique to suppress hydrocarbon contamination for high accuracy determination of carbon content in steel by FE-EPMA

    PubMed Central

    Yamashita, Takako; Tanaka, Yuji; Yagoshi, Masayasu; Ishida, Kiyohito

    2016-01-01

    In multiphase steels, control of the carbon contents in the respective phases is the most important factor in alloy design for achieving high strength and high ductility. However, it is unusually difficult to determine the carbon contents in multiphase structures with high accuracy by electron probe microanalysis (EPMA) due to the unavoidable effect of hydrocarbon contamination during measurements. We have investigated new methods for suppressing hydrocarbon contamination during field emission (FE) EPMA measurements as well as a conventional liquid nitrogen trap. Plasma cleaner inside the specimen chamber results in a improvement of carbon-content determination by point analysis, increasing precision tenfold from the previous 0.1 mass%C to 0.01 mass%C. Stage heating at about 100 °C dramatically suppresses contamination growth during continuous point measurement and mapping. By the combination of above two techniques, we successfully visualized the two-dimensional carbon distribution in a dual-phase steel. It was also noted that the carbon concentrations at the ferrite/martensite interfaces were not the same across all interfaces, and local variation was observed. The developed technique is expected to be a powerful tool for understanding the mechanisms of mechanical properties and microstructural evolution, thereby contributing to the design of new steel products with superior properties. PMID:27431281

  15. Novel technique to suppress hydrocarbon contamination for high accuracy determination of carbon content in steel by FE-EPMA.

    PubMed

    Yamashita, Takako; Tanaka, Yuji; Yagoshi, Masayasu; Ishida, Kiyohito

    2016-07-19

    In multiphase steels, control of the carbon contents in the respective phases is the most important factor in alloy design for achieving high strength and high ductility. However, it is unusually difficult to determine the carbon contents in multiphase structures with high accuracy by electron probe microanalysis (EPMA) due to the unavoidable effect of hydrocarbon contamination during measurements. We have investigated new methods for suppressing hydrocarbon contamination during field emission (FE) EPMA measurements as well as a conventional liquid nitrogen trap. Plasma cleaner inside the specimen chamber results in a improvement of carbon-content determination by point analysis, increasing precision tenfold from the previous 0.1 mass%C to 0.01 mass%C. Stage heating at about 100 °C dramatically suppresses contamination growth during continuous point measurement and mapping. By the combination of above two techniques, we successfully visualized the two-dimensional carbon distribution in a dual-phase steel. It was also noted that the carbon concentrations at the ferrite/martensite interfaces were not the same across all interfaces, and local variation was observed. The developed technique is expected to be a powerful tool for understanding the mechanisms of mechanical properties and microstructural evolution, thereby contributing to the design of new steel products with superior properties.

  16. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

    SciTech Connect

    Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

    2015-10-20

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. Furthermore, to illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.

  17. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

    DOE PAGES

    Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; ...

    2015-10-20

    Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extrememore » temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. Furthermore, to illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.« less

  18. Effect of ultrasonic nanocrystal surface modification on surface and fatigue properties of quenching and tempering S45C steel

    NASA Astrophysics Data System (ADS)

    Wu, Bo; Zhang, Jianxun; Zhang, Linjie; Pyoun, Young-Shik; Murakami, Ri-ichi

    2014-12-01

    Ultrasonic nanocrystal surface modification (USNM) utilizing ultrasonic vibration energy is a method which induces severe plastic deformation to a material's surface and an enhanced surface layer in order to produce a nano-structured surface. In this paper, USNM was performed to enhance the surface properties of quenched and tempered S45C steel by producing a nanostructured surface layer. Various processing parameters, such as static loading (50 N, 60 N and 70 N) and processing density (34,000 mm-2 and 68,000 mm-2), were applied in the surface treatment. The microstructure, hardness and residual stress of the material were analyzed. A rotating bending fatigue test was used to investigate the fatigue properties of the enhanced surface layer. A maximum static load of about 50 N was found for S45C steel process. As the strike number increased, a deeper refined grain layer and higher compressive residual stress was produced on the material's surface. The fatigue strength can be improved from 464 Mpa to about 550 Mpa through this process. Surface cracks, formed due to a heightened processing density of 68,000 mm-2, were found on the top surface layer of the material and large processing density was the reason of the formation of cracks.

  19. Preparation and surface characterization of HMDI-activated 316L stainless steel for coronary artery stents.

    PubMed

    Chuang, T-W; Chen, M-H; Lin, F-H

    2008-06-01

    Poor compatibility between blood and metallic coronary artery stents is one reason for arterial restenosis. Immobilization of anticoagulant agents on the stent's surface is feasible for improving compatibility. We examined possible surface-coupling agents for anticoagulant agent immobilization. Hexamethylene diisocyanate (HMDI) and 3-aminopropyl-triethoxysilane (APTS) were examined as surface-coupling agents to activate 316L stainless steel (e.g., stent material). The activated surface was characterized using Fourier transformation infrared spectroscopy (FTIR), atomic force microscope (AFM), surface plasmon resonance (SPR), and trinitrobenzene sulfonic acid (TNBS) assay. In FTIR analysis, HMDI and APTS were both covalently linked to 316L stainless steel. In AFM analysis, it was found that the HMDI-activated surface was smoother than the APTS-activated one. In SPR test, the shift of SPR angle for the APTS-activated surface was much higher than that for the HMDI-activated surface after being challenged with acidic solution. TNBS assay was used to determine the amount of immobilized primary amine groups. The HMDI-activated surface was found to consist of about 1.32 micromol/cm(2) amine group, whereas the APTS-activated surface consisted of only 0.89 micromol/cm(2) amine group. We conclude that the HMDI-activated surface has more desirable surface characteristics than the APTS-activated surface has, such as chemical stability and the amount of active amine groups.

  20. Grafting of ionic liquids on stainless steel surface for antibacterial application.

    PubMed

    Pang, Li Qing; Zhong, Li Juan; Zhou, Hui Fang; Wu, Xue E; Chen, Xiao Dong

    2015-02-01

    Stainless steel (SS) is favored for many uses due to its excellent chemical resistance, thermal stability and mechanical properties. Biofilms can be formed on stainless steel and may lead to serious hygiene problems and economic losses in many areas, e.g. food processing, public infrastructure and healthcare. For the first time, our work endeavored to make SS having antibacterial properties, ionic liquids (ILs) were grafted on SS surface via silane treatment followed by thiol-ene click reaction. The chemical structure and composition of the ILs grafted stainless-steel coupon surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The antibacterial activity has been investigated, and the results showed that the ILs grafted SS surface exhibited significant antibacterial effects against Gram-negative Escherichia coli. Additionally, the results obtained here indicated that the ILs used here having bromide anion showed much better antibacterial activity against E. coli than the corresponding ILs with tetrafluoroborate and hexafluorophosphate as anions. These results obtained here can help to design novel and more efficient stainless steel having antibacterial surface.

  1. Portable hyperspectral fluorescence imaging system for detection of biofilms on stainless steel surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A rapid nondestructive technology is needed to detect bacterial contamination on the surfaces of food processing equipment to reduce public health risks. A portable hyperspectral fluorescence imaging system was used to evaluate potential detection of microbial biofilm on stainless steel typically u...

  2. Enhanced Radiation-tolerant Oxide Dispersion Strengthened Steel and its Microstructure Evolution under Helium-implantation and Heavy-ion Irradiation

    PubMed Central

    Lu, Chenyang; Lu, Zheng; Wang, Xu; Xie, Rui; Li, Zhengyuan; Higgins, Michael; Liu, Chunming; Gao, Fei; Wang, Lumin

    2017-01-01

    The world eagerly needs cleanly-generated electricity in the future. Fusion reactor is one of the most ideal energy resources to defeat the environmental degradation caused by the consumption of traditional fossil energy. To meet the design requirements of fusion reactor, the development of the structural materials which can sustain the elevated temperature, high helium concentration and extreme radiation environments is the biggest challenge for the entire material society. Oxide dispersion strengthened steel is one of the most popular candidate materials for the first wall/blanket applications in fusion reactor. In this paper, we evaluate the radiation tolerance of a 9Cr ODS steel developed in China. Compared with Ferritic/Martensitic steel, this ODS steel demonstrated a significantly higher swelling resistance under ion irradiation at 460 °C to 188 displacements per atom. The role of oxides and grain boundaries on void swelling has been explored. The results indicated that the distribution of higher density and finer size of nano oxides will lead a better swelling resistance for ODS alloy. The original pyrochlore-structured Y2Ti2O7 particles dissolved gradually while fine Y-Ti-O nano clusters reprecipitated in the matrix during irradiation. The enhanced radiation tolerance is attributed to the reduced oxide size and the increased oxide density. PMID:28079191

  3. Enhanced Radiation-tolerant Oxide Dispersion Strengthened Steel and its Microstructure Evolution under Helium-implantation and Heavy-ion Irradiation

    NASA Astrophysics Data System (ADS)

    Lu, Chenyang; Lu, Zheng; Wang, Xu; Xie, Rui; Li, Zhengyuan; Higgins, Michael; Liu, Chunming; Gao, Fei; Wang, Lumin

    2017-01-01

    The world eagerly needs cleanly-generated electricity in the future. Fusion reactor is one of the most ideal energy resources to defeat the environmental degradation caused by the consumption of traditional fossil energy. To meet the design requirements of fusion reactor, the development of the structural materials which can sustain the elevated temperature, high helium concentration and extreme radiation environments is the biggest challenge for the entire material society. Oxide dispersion strengthened steel is one of the most popular candidate materials for the first wall/blanket applications in fusion reactor. In this paper, we evaluate the radiation tolerance of a 9Cr ODS steel developed in China. Compared with Ferritic/Martensitic steel, this ODS steel demonstrated a significantly higher swelling resistance under ion irradiation at 460 °C to 188 displacements per atom. The role of oxides and grain boundaries on void swelling has been explored. The results indicated that the distribution of higher density and finer size of nano oxides will lead a better swelling resistance for ODS alloy. The original pyrochlore-structured Y2Ti2O7 particles dissolved gradually while fine Y-Ti-O nano clusters reprecipitated in the matrix during irradiation. The enhanced radiation tolerance is attributed to the reduced oxide size and the increased oxide density.

  4. Enhanced Radiation-tolerant Oxide Dispersion Strengthened Steel and its Microstructure Evolution under Helium-implantation and Heavy-ion Irradiation.

    PubMed

    Lu, Chenyang; Lu, Zheng; Wang, Xu; Xie, Rui; Li, Zhengyuan; Higgins, Michael; Liu, Chunming; Gao, Fei; Wang, Lumin

    2017-01-12

    The world eagerly needs cleanly-generated electricity in the future. Fusion reactor is one of the most ideal energy resources to defeat the environmental degradation caused by the consumption of traditional fossil energy. To meet the design requirements of fusion reactor, the development of the structural materials which can sustain the elevated temperature, high helium concentration and extreme radiation environments is the biggest challenge for the entire material society. Oxide dispersion strengthened steel is one of the most popular candidate materials for the first wall/blanket applications in fusion reactor. In this paper, we evaluate the radiation tolerance of a 9Cr ODS steel developed in China. Compared with Ferritic/Martensitic steel, this ODS steel demonstrated a significantly higher swelling resistance under ion irradiation at 460 °C to 188 displacements per atom. The role of oxides and grain boundaries on void swelling has been explored. The results indicated that the distribution of higher density and finer size of nano oxides will lead a better swelling resistance for ODS alloy. The original pyrochlore-structured Y2Ti2O7 particles dissolved gradually while fine Y-Ti-O nano clusters reprecipitated in the matrix during irradiation. The enhanced radiation tolerance is attributed to the reduced oxide size and the increased oxide density.

  5. Development of a surface topography instrument for automotive textured steel plate

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Wang, Shenghuai; Chen, Yurong; Xie, Tiebang

    2010-08-01

    The surface topography of automotive steel plate is decisive to its stamping, painting and image clarity performances. For measuring this kind of surface topography, an instrument has been developed based on the principle of vertical scanning white light microscopy interference principle. The microscopy interference system of this instrument is designed based on the structure of Linnik interference microscopy. The 1D worktable of Z direction is designed and introduced in details. The work principle of this instrument is analyzed. In measuring process, the interference microscopy is derived as a whole and the measured surface is scanned in vertical direction. The measurement accuracy and validity is verified by templates. Surface topography of textured steel plate is also measured by this instrument.

  6. Removal of the long-lived {sup 222}Rn daughters from steel and germanium surfaces

    SciTech Connect

    Wojcik, Marcin; Zuzel, Grzegorz; Majorovits, Bela

    2011-04-27

    Removal of the long-lived {sup 222}Rn daughters ({sup 210}Pb, {sup 210}Bi and {sup 210}Po) from stainless steel and germanium surfaces was investigated. As cleaning technique etching was applied to samples in a form of discs exposed earlier to a strong radon source. Reduction of the {sup 210}Pb activity was tested using a HPGe spectrometer, for {sup 210}Bi a beta spectrometer and for {sup 210}Po an alpha spectrometer was used. According to the conducted measurements all the isotopes were removed very efficiently from germanium. Results obtained for stainless steel were worse but still better than those achieved for copper.

  7. Modification of the Steel Surface Treated by a Volume Discharge Plasma in Nitrogen at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Erofeev, M. V.; Shulepov, M. A.; Ivanov, Yu. F.; Oskomov, K. V.; Tarasenko, V. F.

    2016-03-01

    Effect of volume discharge plasma initiated by an avalanche electron beam on the composition, structure, and properties of the surface steel layer is investigated. Voltage pulses with incident wave amplitude up to 30 kV, full width at half maximum of about 4 ns, and wave front of about 2.5 ns were applied to the gap with an inhomogeneous electric field. Changes indicating the hardening effect of the volume discharge initiated by an avalanche electron beam are revealed in St3-grade steel specimens treated by the discharge of this type.

  8. Corrosion behavior of surface films on boron-implanted high purity iron and stainless steels

    NASA Technical Reports Server (NTRS)

    Kim, H. J.; Carter, W. B.; Hochman, R. F.; Meletis, E. I.

    1985-01-01

    Boron (dose, 2 x 10 to the 17th ions/sq cm) was implanted into high purity iron, AISI 316 austenitic stainless steel, and AISI 440C martensitic stainless steel, at 40 keV. The film structure of implanted samples was examined and characterized by contrast and diffraction analyses utilizing transmission electron microscopy. The effect of B(+) ion implantation on the corrosion behavior was studied using the potentiodynamic polarization technique. Tests were performed in deaerated 1 N H2SO4 and 0.1 M NaCl solutions. Scanning electron microscopy was used to examine the morphology of the corroded surfaces after testing.

  9. Effects Of Milling On Surface Integrity Of Low-Carbon Steel

    SciTech Connect

    Rodrigues, Alessandro Roger; Matsumoto, Hidekasu; Yamakami, Wyser Jose; Tokimatsu, Ruis Camargo; Menezes, Miguel Angelo; Suyama, Daniel Iwao; Norcino, Adriana Bruno; Vendrame, Saimon

    2011-01-17

    This work measured the effect of milling parameters on the surface integrity of low-carbon alloy steel. The Variance Analysis showed that only depth of cut did not influence on the workpiece roughness and the Pearson's Coefficient indicated that cutting speed was more influent than tool feed. All cutting parameters introduced tensile residual stress in workpiece surface. The chip formation mechanism depended specially on cutting speed and influenced on the roughness and residual stress of workpiece.

  10. Portable hyperspectral fluorescence imaging system for detection of biofilms on stainless steel surfaces

    NASA Astrophysics Data System (ADS)

    Jun, Won; Lee, Kangjin; Millner, Patricia; Sharma, Manan; Chao, Kuanglin; Kim, Moon S.

    2008-04-01

    A rapid nondestructive technology is needed to detect bacterial contamination on the surfaces of food processing equipment to reduce public health risks. A portable hyperspectral fluorescence imaging system was used to evaluate potential detection of microbial biofilm on stainless steel typically used in the manufacture of food processing equipment. Stainless steel coupons were immersed in bacterium cultures, such as E. coli, Pseudomonas pertucinogena, Erwinia chrysanthemi, and Listeria innocula. Following a 1-week exposure, biofilm formations were assessed using fluorescence imaging. In addition, the effects on biofilm formation from both tryptic soy broth (TSB) and M9 medium with casamino acids (M9C) were examined. TSB grown cells enhance biofilm production compared with M9C-grown cells. Hyperspectral fluorescence images of the biofilm samples, in response to ultraviolet-A (320 to 400 nm) excitation, were acquired from approximately 416 to 700 nm. Visual evaluation of individual images at emission peak wavelengths in the blue revealed the most contrast between biofilms and stainless steel coupons. Two-band ratios compared with the single-band images increased the contrast between the biofilm forming area and stainless steel coupon surfaces. The 444/588 nm ratio images exhibited the greatest contrast between the biofilm formations and stainless coupon surfaces.

  11. Spreading of lithium on a stainless steel surface at room temperature

    SciTech Connect

    Skinner, C. H.; Capece, A. M.; Roszell, J. P.; Koel, B. E.

    2015-11-10

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. Here, the spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separate experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (Edes = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (Edes = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding.

  12. Restoration of obliterated engraved marks on steel surfaces by chemical etching reagent.

    PubMed

    Song, Qingfang

    2015-05-01

    Chemical etching technique is widely used for restoration of obliterated engraved marks on steel surface in the field of public security. The consumed thickness of steel surface during restoration process is considered as a major criterion for evaluating the efficiency of the chemical etching reagent. The thinner the consumed thickness, the higher the restoration efficiency. According to chemical principles, maintaining the continuous oxidative capabilities of etching reagents and increasing the kinetic rate difference of the reaction between the engraved and non-engraved area with the chemical etching reagent can effectively reduce the consumed steel thickness. The study employed steel surface from the engine case of motorcycle and the car frame of automobile. The chemical etching reagents are composed of nitric acid as the oxidizer, hydrofluoric acid as the coordination agent and mixed with glacial acetic acid or acetone as the solvents. Based on the performance evaluation of three different etching reagents, the one composed of HNO3, HF and acetone gave the best result.

  13. Spreading of lithium on a stainless steel surface at room temperature

    DOE PAGES

    Skinner, C. H.; Capece, A. M.; Roszell, J. P.; ...

    2015-11-10

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. Here, the spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separatemore » experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (Edes = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (Edes = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding.« less

  14. Effect of Milk Proteins on Adhesion of Bacteria to Stainless Steel Surfaces

    PubMed Central

    Barnes, L.-M.; Lo, M. F.; Adams, M. R.; Chamberlain, A. H. L.

    1999-01-01

    Stainless steel coupons were treated with skim milk and subsequently challenged with individual bacterial suspensions of Staphylococcus aureus, Pseudomonas fragi, Escherichia coli, Listeria monocytogenes, and Serratia marcescens. The numbers of attached bacteria were determined by direct epifluorescence microscopy and compared with the attachment levels on clean stainless steel with two different surface finishes. Skim milk was found to reduce adhesion of S. aureus, L. monocytogenes, and S. marcescens. P. fragi and E. coli attached in very small numbers to the clear surfaces, making the effect of any adsorbed protein layer difficult to assess. Individual milk proteins α-casein, β-casein, κ-casein, and α-lactalbumin were also found to reduce the adhesion of S. aureus and L. monocytogenes. The adhesion of bacteria to samples treated with milk dilutions up to 0.001% was investigated. X-ray photoelectron spectroscopy was used to determine the proportion of nitrogen in the adsorbed films. Attached bacterial numbers were inversely related to the relative atomic percentage of nitrogen on the surface. A comparison of two types of stainless steel surface, a 2B and a no. 8 mirror finish, indicated that the difference in these levels of surface roughness did not greatly affect bacterial attachment, and reduction in adhesion to a milk-treated surface was still observed. Cross-linking of adsorbed proteins partially reversed the inhibition of bacterial attachment, indicating that protein chain mobility and steric exclusion may be important in this phenomenon. PMID:10508087

  15. A facile electrodeposition process to fabricate corrosion-resistant superhydrophobic surface on carbon steel

    NASA Astrophysics Data System (ADS)

    Fan, Yi; He, Yi; Luo, Pingya; Chen, Xi; Liu, Bo

    2016-04-01

    Superhydrophobic Fe film with hierarchical micro/nano papillae structures is prepared on C45 steel surface by one-step electrochemical method. The superhydrophobic surface was measured with a water contact angle of 160.5 ± 0.5° and a sliding angle of 2 ± 0.5°. The morphology of the fabricated surface film was characterized by field emission scanning electron microscopy (FE-SEM), and the surface structure seems like accumulated hierarchical micro-nano scaled particles. Furthermore, according to the results of Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectroscopy (XPS), the chemical composition of surface film was iron complex with organic acid. Besides, the electrochemical measurements showed that the superhydrophobic surface improved the corrosion resistance of carbon steel in 3.5 wt.% NaCl solution significantly. The superhydrophobic layer can perform as a barrier and provide a stable air-liquid interface which inhibit penetration of corrosive medium. In addition, the as-prepared steel exhibited an excellent self-cleaning ability that was not favor to the accumulation of contaminants.

  16. Surface Preparation of Powder Metallurgical Tool Steels by Means of Wire Electrical Discharge Machining

    NASA Astrophysics Data System (ADS)

    Hatami, Sepehr; Shahabi-Navid, Mehrdad; Nyborg, Lars

    2012-09-01

    The surface of two types of powder metallurgical (PM) tool steels ( i.e., with and without nitrogen) was prepared using wire electrical discharge machining (WEDM). From each grade of tool steel, seven surfaces corresponding to one to seven passes of WEDM were prepared. The WEDM process was carried out using a brass wire as electrode and deionized water as dielectric. After each WEDM pass the surface of the tool steels was thoroughly examined. Surface residual stresses were measured by the X-ray diffraction (XRD) technique. The measured stresses were found to be of tensile nature. The surface roughness of the WEDM specimens was measured using interference microscopy. The surface roughness as well as the residual stress measurements indicated an insignificant improvement of these parameters after four passes of WEDM. In addition, the formed recast layer was characterized by means of scanning electron microscopy (SEM), XRD, and X-ray photoelectron spectroscopy (XPS). The characterization investigation clearly shows diffusion of copper and zinc from the wire electrode into the work material, even after the final WEDM step. Finally, the importance of eliminating excessive WEDM steps is thoroughly discussed.

  17. The effect of surface morphology on the friction of electrogalvanized sheet steel in forming processes

    SciTech Connect

    Skarpelos, Peter N.

    1993-12-01

    The effect in the drawbead simulator test were evaluated for a set of commercially coated steels and a set of laboratory coated steels with underlying surfaces produced by laser textured, shot blast, and electro-discharge textured rolls. In general, surfaces with higher roughness (Ra parameter) measured lower friction in the DBS tests. The requisite roughness amplitude necessary for low friction was moderated somewhat by having a more closely spaced roughness as described by the median wavelength, λm, of the power spectrum. This effect is due to interaction with the lubricant by the micro-roughness imparted by the galvanizing process. The lubricant tends to be retained better by the surfaces with the micro-roughness, thereby increasing the amount of elasto- and plasto-hydrodynamic support of the load. Other variables, such as large variations in thickness of the sheet can mask the effect of the surface by changing the actual distance of sliding contact during the DBS test. For tests where the amount of sliding is similar, the effect of roughness is significant. The friction measured for EG steels in the DBS test is dominated by deformation of the surface with plowing by the asperities of the tooling adding to that caused by the deformation. The size of the plow marks in the deformed surfaces corresponds to the roughness of the tooling and no significant evidence of wear particles was observed.

  18. Removal of the long-lived 222Rn daughters from copper and stainless steel surfaces

    NASA Astrophysics Data System (ADS)

    Zuzel, G.; Wójcik, M.

    2012-06-01

    Removal of the long-lived 222Rn daughters from copper and stainless steel surfaces was investigated. Etching and electropolishing were applied to discs exposed earlier to a strong radon source for 210Pb, 210Bi and 210Po deposition. Cleaning efficiency for 210Pb was tested with a n-type high purity germanium spectrometer, for 210Bi a beta spectrometer and for 210Po an alpha spectrometer was used. According to the performed measurements electropolishing removes very effectively all the isotopes from copper and stainless steel. Copper etching reduces efficiently lead and bismuth however for polonium the effect is negligible because of its fast re-deposition. For stainless steel, etching is much more effective compared to copper and it also works for 210Po.

  19. Surface Characterization of Stainless Steel Part by Eddy Current

    SciTech Connect

    Andersen, Eric S.; Hockey, Ronald L.; Prince, James M.; Good, Morris S.

    2003-10-01

    The Pacific Northwest National Laboratory (PNNL) has nearly a 40 year history of research and development in the field of nondestructive evaluation (NDE). One area of NDE expertise at PNNL is electromagnetic testing which includes a field of eddy current testing (ET). One benefit is that ET can typically be performed at high speeds, and as a result has found many applications in process monitoring and poduction lines. ET has been used in the nuclear, aerospace, and automotive industries for many years. Et technology lends itself well to the detection of near-surface or surface breaking defects such as surface scratches. This paper provides an overview of theory regarding the usage of ET, selected application studies performed by PNNL, a safety analysis, and a wrtie up pertaining to the operations of ET to detect surface scratches.

  20. Effect of Initial Microtopography and Ultrasonic Treatment Mode on Steel Surface Layer Quality

    NASA Astrophysics Data System (ADS)

    Zaitsev, K. V.; Lychagin, D. V.; Arkhipova, D. A.

    2016-04-01

    The article presents results of studies on the effect of pre-lathed surface micro-relief on surface micro-hardness after ultrasonic plastic treatment, as well as the effect of ultrasonic treatment on structure and properties of surface layers of steels 20 and 40X. The effect of ultrasonic treatment processing modes on roughness and micro-hardness of the surface layers was studied. It is shown that roughness values as well as form of ridges and grooves, obtained by pre-lathing, effect the growth of micro-hardness values after ultrasonic plastic treatment.

  1. Development of Fractal Dimension and Characteristic Roughness Models for Turned Surface of Carbon Steels

    NASA Astrophysics Data System (ADS)

    Zuo, Xue; Zhu, Hua; Zhou, Yuankai; Ding, Cong; Sun, Guodong

    2016-08-01

    Relationships between material hardness, turning parameters (spindle speed and feed rate) and surface parameters (surface roughness Ra, fractal dimension D and characteristic roughness τ∗) are studied and modeled using response surface methodology (RSM). The experiments are carried out on a CNC lathe for six carbon steel material AISI 1010, AISI 1020, AISI 1030, AISI 1045, AISI 1050 and AISI 1060. The profile of turned surface and the surface roughness value are measured by a JB-5C profilometer. Based on the profile data, D and τ∗ are computed through the root-mean-square method. The analysis of variance (ANOVA) reveals that spindle speed is the most significant factors affecting Ra, while material hardness is the most dominant parameter affecting τ∗. Material hardness and spindle speed have the same influence on D. Feed rate has less effect on three surface parameters than spindle speed and material hardness. The second-order models of RSM are established for estimating Ra, D and τ∗. The validity of the developed models is approximately 80%. The response surfaces show that a surface with small Ra and large D and τ∗ can be obtained by selecting a high speed and a large hardness material. According to the established models, Ra, D and τ∗ of six carbon steels surfaces can be predicted under cutting conditions studied in this paper. The results have an instructive meaning to estimate the surface quality before turning.

  2. Laser surface melting and subsequent treatment of 440C stainless steel

    SciTech Connect

    Magee, K.H.; Merchant, V.E.

    1996-12-31

    Surface treatments of 440C martensitic stainless steel is complicated by the alloy microstructure which contains large primary carbides and finer secondary carbides. Surface melting, followed by rapid solidification, breaks up the carbides resulting in a more homogeneous microstructure which was used as a starting point for further processing. Laser surface melting of the 440C samples produced a primary austenite structure with negligible carbide precipitation. Emersion in liquid nitrogen and elevated temperature treatments carried out in an attempt to stimulate carbide precipitation failed to produce significant hardening. Surface melting followed by a double temper treatment with air cooling between the tempers did result in surface hardening. Rapid nucleation and growth of carbide particles was observed along the grain boundaries, attributed to a high diffusion rate for carbon. The tempering time required to produce maximum hardening was found to depend on the heat input in surface melting. The laser surface melted material was also subjected to a high temperature soak, followed by water quench and a tempering treatment. Microstructural examination showed the surface melted region to contain a network of fine carbides, whereas the base metal contained a wide range of carbide sizes including large primary carbides. The significance of applying a laser surface melting treatment to the 440C steel prior to the standard quench and temper operation is the elimination of the large carbides in the surface microstructure. This has the potential to improve the service performance of the material in many applications.

  3. Laser Surface Alloying of SUS316 Stainless Steel with Al-Si

    NASA Astrophysics Data System (ADS)

    Zherebtsov, Sergey; Maekawa, Katsuhiro; Hayashi, Terutake; Futakawa, Masatoshi

    The effect of varying temperature of the type 316 stainless steel substrate on the structure and properties of laser alloyed layer was investigated. The material for alloying (Al-Si powder mixture) was placed on the surface of stainless steel substrate by pasting. The surface was scanned by a pulsed Nd: YAG laser beam to achieve surface alloying. The temperature of substrate continuously increased during laser treatment to about 830°C. The microstructure, chemical and phase composition and microhardness of the modified layer were studied then. It has been found that four different types of structure were formed in the alloyed zone depending on the temperature of the substrate. These structures differ from each other in phase composition, microhardness and relation to cracking. Based on the results, optimal parameters for the production of a uniform, crack-free layer with a high hardness were developed.

  4. Effect of surface polishing and vacuum firing on electron stimulated desorption from 316LN stainless steel

    SciTech Connect

    Malyshev, Oleg B. Hogan, Benjamin T.; Pendleton, Mark

    2014-09-01

    The reduction of thermal outgassing from stainless steel by surface polishing or vacuum firing is well-known in vacuum technology, and the consequent use of both techniques allows an even further reduction of outgassing. The aim of this study was to identify the effectiveness of surface polishing and vacuum firing for reducing electron-stimulated desorption (ESD) from 316LN stainless steel, which is a frequently used material for particle accelerator vacuum chambers and components. It was found that, unlike for thermal outgassing, surface polishing does not reduce the ESD yield and may even increase it, while vacuum firing of nonpolished sample reduces only the H{sub 2} ESD yield by a factor 2.

  5. Laser surface pretreatment of 100Cr6 bearing steel - Hardening effects and white etching zones

    NASA Astrophysics Data System (ADS)

    Buling, Anna; Sändker, Hendrik; Stollenwerk, Jochen; Krupp, Ulrich; Hamann-Steinmeier, Angela

    2016-08-01

    In order to achieve a surface pretreatment of the bearing steel 100Cr6 (1-1.5 wt.% Cr) a laser-based process was used. The obtained modification may result in an optimization of the adhesive properties of the surface with respect to an anticorrosion polymer coating on the basis of PEEK (poly-ether-ether-ketone), which is applied on the steel surface by a laser melting technique. This work deals with the influence of the laser-based pretreatment regarding the surface microstructure and the micro-hardness of the steel, which has been examined by scanning electron microscopy (SEM), light microscopy and automated micro-hardness testing. The most suitable parameter set for the laser-based pretreatment leads to the formation of very hard white etching zones (WEZ) with a thickness of 23 μm, whereas this pretreatment also induces topographical changes. The occurrence of the white etching zones is attributed to near-surface re-austenitization and rapid quenching. Moreover, dark etching zones (DEZ) with a thickness of 32 μm are found at the laser path edges as well as underneath the white etching zones (WEZ). In these areas, the hardness is decreased due to the formation of oxides as a consequence of re-tempering.

  6. Surface Treatments for Improved Performance of Spinel-coated AISI 441 Ferritic Stainless Steel

    SciTech Connect

    Stevenson, Jeffry W.; Riel, Eric M.; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2013-01-01

    Ferritic stainless steels are promising candidates for IT-SOFC interconnect applications due to their low cost and resistance to oxidation at SOFC operating temperatures. However, steel candidates face several challenges; including long term oxidation under interconnect exposure conditions, which can lead to increased electrical resistance, surface instability, and poisoning of cathodes due to volatilization of Cr. To potentially extend interconnect lifetime and improve performance, a variety of surface treatments were performed on AISI 441 ferritic stainless steel coupons prior to application of a protective spinel coating. The coated coupons were then subjected to oxidation testing at 800 and 850°C in air, and electrical testing at 800°C in air. While all of the surface-treatments resulted in improved surface stability (i.e., increased spallation resistance) compared to untreated AISI 441, the greatest degree of improvement (through 20,000 hours of testing at 800°C and 14,000 hours of testing at 850°C) was achieved by surface blasting.

  7. Surface microstructures and antimicrobial properties of copper plasma alloyed stainless steel

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyu; Huang, Xiaobo; Jiang, Li; Ma, Yong; Fan, Ailan; Tang, Bin

    2011-12-01

    Bacterial adhesion to stainless steel surfaces is one of the major reason causing the cross-contamination and infection in many practical applications. An approach to solve this problem is to enhance the antibacterial properties on the surface of stainless steel. In this paper, novel antibacterial stainless steel surfaces with different copper content have been prepared by a plasma surface alloying technique at various gas pressures. The microstructure of the alloyed surfaces was investigated using glow discharge optical emission spectroscopy (GDOES) and scanning electron microscopy (SEM). The viability of bacteria attached to the antibacterial surfaces was tested using the spread plate method. The antibacterial mechanism of the alloyed surfaces was studied by X-ray photoelectron spectroscopy (XPS). The results indicate that gas pressure has a great influence on the surface elements concentration and the depth of the alloyed layer. The maximum copper concentration in the alloyed surface obtained at the gas pressure of 60 Pa is about 7.1 wt.%. This alloyed surface exhibited very strong antibacterial ability, and an effective reduction of 98% of Escherichia coli (E. coli) within 1 h was achieved by contact with the alloyed surface. The maximum thickness of the copper alloyed layer obtained at 45 Pa is about 6.5 μm. Although the rate of reduction for E. coli of this alloyed surface was slower than that of the alloyed surface with the copper content about 7.1 wt.% over the first 3 h, few were able to survive more than 12 h and the reduction reached over 99.9%. The XPS analysis results indicated that the copper ions were released when the copper alloyed stainless steel in contact with bacterial solution, which is an important factor for killing bacteria. Based on an overall consideration of bacterial killing rate and durability, the alloyed surface with the copper content of 2.5 wt.% and the thickness of about 6.5 μm obtained at the gas pressure of 45 Pa is expected

  8. Characterization of the thrombogenic potential of surface oxides on stainless steel for implant purposes

    NASA Astrophysics Data System (ADS)

    Shih, Chun-Che; Shih, Chun-Ming; Su, Yea-Yang; Chang, Mau-Song; Lin, Shing-Jong

    2003-12-01

    Marketed stents are manufactured from various metals and passivated with different degrees of surface oxidation. The functional surface oxides on the degree of antithrombotic potential were explored through a canine femoral extracorporeal circuit model. Related properties of these oxide films were studied by open-circuit potential, current density detected at open-circuit potential, the electrochemical impedance spectroscopy, transmission electron microscopy, Auger spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. Experimental evidences showed that blood clot weight after a 30-min follow-up was significantly lower for the stainless steel wire passivated with amorphous oxide (AO) compared to the wire passivated with polycrystalline oxide (PO) or commercial as-received wire coils (AS). Surface characterizations showed that a stable negative current density at open-circuit potential and a significant lower potential were found for the wire surface passivated with AO than for the surface passivated with PO. Time constant of AO is about 25 times larger than that of polycrystalline oxide. Significant difference in oxide grain sizes was found between PO and AO. Surface chemistries revealed by the AES and XPS spectra indicated the presence of a Cr- and oxygen-rich surface oxide for AO, and a Fe-rich and oxygen-lean surface oxide for PO. These remarkable characteristics of AO surface film might have a potential to provide for excellent antithrombotic characteristics for the 316L stainless steel stents.

  9. Barkhausen effect in steels and its dependence on surface condition

    SciTech Connect

    Parakka, A.P.; Jiles, D.C.; Gupta, H.; Zang, M.

    1997-04-01

    Micromagnetic Barkhausen signals from magnetic materials originate from the discontinuous changes in magnetization under the action of a changing applied magnetic field. Barkhausen emissions that are detected by a sense coil come predominantly from a surface layer. In iron based materials this layer is about 500 {mu}m thick. The Barkhausen signal is affected by changes in material microstructure and the presence of residual stress, since these affect the dynamics of domain wall motion. The selective attenuation of high frequency components of the Barkhausen signal due to eddy currents in electrically conducting materials is used to evaluate changes in material condition at different depths inside the material. Barkhausen measurements on specimens subjected to different thermal treatment during surface conditioning procedures are presented. Also presented for comparison are analysis of the material condition using x-ray diffraction for assessment of residual stress, and microhardness measurements which evaluate the surface microstructure condition. The results show that Barkhausen emissions can be utilized to evaluate changes in the surface condition of materials. {copyright} {ital 1997 American Institute of Physics.}

  10. Surface Properties of a Hooked Steel Fiber and their Effects on the Fiber Pullout and Composite Cracking 1. Experimental Study

    NASA Astrophysics Data System (ADS)

    Zesers, A.; Krūmiņš, J.

    2014-09-01

    Concrete as a material is brittle, but adding short steel fibers to the matrix can significantly improve its mechanical properties. The chemical adhesion between concrete and steel is weak, and the fiber pullout properties are based on fiber geometry and frictional forces. Single-fiber pullout tests of steel fibers with toothed and smooth surfaces were performed in order to characterize the effects of fiber surface facture. The influence of fiber form, surface facture, and fiber orientation (relative to the pullout direction) on the fiber withdrawal resistance and the maximum pullout force were studied.

  11. A Novel Single-Step Surface-Treatment Process for Forming Cr-Nitride Coatings on Steels

    NASA Astrophysics Data System (ADS)

    Lu, X. J.; Xiang, Z. D.

    2017-02-01

    A novel single-step surface-treatment process is demonstrated for forming Cr-nitride coatings on steels. The process was carried out at 1327 K (1100 °C) for two steel grades with differing carbon concentrations. For steel grade with 0.42 to 0.5C (wt pct), the coatings formed consisted of an outer Cr2N layer and an inner Cr-carbide layer with a Cr-enriched interdiffusion zone underneath. However, for steel grade with C ≤ 0.17 wt pct, the inner Cr-carbide layer was absent.

  12. Application of slightly acidic electrolyzed water for decontamination of stainless steel surfaces in animal transport vehicles.

    PubMed

    Ni, Li; Zheng, Weichao; Zhang, Qiang; Cao, Wei; Li, Baoming

    2016-10-01

    The effectiveness of slightly acidic electrolyzed water (SAEW) in reducing Escherichia coli, Salmonella typhimurim, Staphylococcus aureus or bacterial mixtures on stainless steel surfaces was evaluated and compared its efficacy with composite phenol solution for reducing total aerobic bacteria in animal transport vehicles. Stainless steel surfaces were inoculated with these strains individually or in a mixture, and sprayed with SAEW, composite phenol, or alkaline electrolyzed water for 0.5, 1, 1.5 and 2min. The bactericidal activity of SAEW increased with increasing available chlorine concentration and spraying duration. The SAEW solution of 50mgl(-1) of available chlorine concentration showed significantly higher effectiveness than composite phenol in reducing the pathogens on stainless steel surfaces (P<0.05). Complete inactivation of pathogens on stainless steel surfaces were observed after treatment with alkaline electrolyzed water followed by SAEW at 50mgl(-1) of available chlorine concentration for 2min or alkaline electrolyzed water treatment followed by SAEW treatment at 90mgl(-1) of available chlorine concentration for 0.5min. The efficacy of SAEW in reducing total aerobic bacteria in animal transport vehicles was also determined. Vehicles in the disinfection booth were sprayed with the same SAEW, alkaline electrolyzed water and composite phenol solutions using the automatic disinfection system. Samples from vehicle surfaces were collected with sterile cotton swabs before and after each treatment. No significant differences in bactericidal efficiency were observed between SAEW and composite phenol for reducing total aerobic bacteria in the vehicles (P>0.05). SAEW was also found to be more effective when used in conjunction with alkaline electrolyzed water. Results suggest that the bactericidal efficiency of SAEW was higher than or equivalent to that of composite phenol and SAEW may be used as effective alternative for reducing microbial contamination of

  13. Influence of Shot Peening on Surface Characteristics of High-Speed Steels

    NASA Astrophysics Data System (ADS)

    Harada, Yasunori; Fukaura, Kenzo

    High-speed steels are generally used for the cutting of other hard materials. These are hard materials, and can be used at high temperatures. Therefore, some of them are used for warm metal forming such as forging. However, in the tools used in hot working, an excellent hot hardness and long-life fatigue are strongly required. In the present study, the influence of shot peening on the surface characteristics of high-speed steels was investigated. Shot peening imparts compressive residual stresses on the metal surface, thus improving the fatigue life of the machine parts. In the experiment, the shot peening treatment was performed using an air-type shot peening machine. The shots made of cemented carbide were used. The workpieces were two types, W-type and Mo-type alloys. Surface roughness, compressive residual stress, and hardness of the peened workpieces were measured. It was found that shot peening using the hard shot media was effective in improving the surface characteristics of high-speed steels.

  14. Nanoscaled periodic surface structures of medical stainless steel and their effect on osteoblast cells.

    PubMed

    Elter, Patrick; Sickel, Franka; Ewald, Andrea

    2009-06-01

    Nanoscaled lamellar surface structures have been prepared on medical stainless steel AISI 316LVM surfaces by chemical etching of the decomposed phases. The effect of this structure on osteoblastic cells has been investigated. Long filopodia were developed by the cells perpendicular to the lamellar structure while almost no or only short filopodia were formed parallel to the lamellae. These results are explained in terms of a topographical influence of the nanostructure. During the growth process of the filopodia a nearly flat surface was recognized parallel to the lamellae while a topographical change was sensed perpendicular to the structure, which was preferred by the cells.

  15. Optimization of the chemical composition and manufacturing route for ODS RAF steels for fusion reactor application

    NASA Astrophysics Data System (ADS)

    Oksiuta, Z.; Baluc, N.

    2009-05-01

    As the upper temperature for use of reduced activation ferritic/martensitic steels is presently limited by a drop in mechanical strength at about 550 °C, Europe, Japan and the US are actively researching steels with high strength at higher operating temperatures, mainly using stable oxide dispersion. In addition, the numerous interfaces between matrix and oxide particles are expected to act as sinks for the irradiation-induced defects. The main R&D activities aim at finding a compromise between good tensile and creep strength and sufficient ductility, especially in terms of fracture toughness. Oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steels appear as promising materials for application in fusion power reactors up to about 750 °C. Six different ODS RAF steels, with compositions of Fe-(12-14)Cr-2W-(0.1-0.3-0.5)Ti-0.3Y2O3 (in wt%), were produced by powder metallurgy techniques, including mechanical alloying, canning and degassing of the milled powders and compaction of the powders by hot isostatic pressing, using various devices and conditions. The materials have been characterized in terms of microstructure and mechanical properties. The results have been analysed in terms of optimal chemical composition and manufacturing conditions. In particular, it was found that the composition of the materials should lie in the range Fe-14Cr-2W-(0.3-0.4)Ti-(0.25-0.3)Y2O3, as 14Cr ODS RAF steels exhibit higher tensile strength and better Charpy impact properties and are more stable than 12Cr materials (no risk of martensitic transformation), while materials with 0.5% Ti or more should not be further investigated, due to potential embrittlement by large TiO2 particles.

  16. Corrosion Phenomena of Eurofeer Steel in Pb-17Li Stationary Flow at Magnetic Field

    SciTech Connect

    Platacis, E.; Bucenieks, I.; Muktepavela, F.; Shishko, A.

    2006-07-01

    Search of new energy sources draws the increasing attention to use for this purpose of reactors. In the Europe some years the program EUROATOM uniting scientific of the many countries for the decision of constructive problems at designing of fusion reactors operates. One of the main things in this program is the problem of liquid metals breeder blanket behaviour. Structural material of blanket should meet high requirements because of extreme operating conditions. Therefore the knowledge of the effect of metals flow velocity, temperatures and also a neutron irradiation and a magnetic field on the corrosion processes are necessary. At the moment the eutectic lead -lithium (Pb-17Li) is considered as the most suitable tritium breeder material. In turn as a structural material have been tested both many austenitic and ferritic-martensitic steels. As the optimum variant is considered steel EUROFER 97, which corrosion rate in liquid Pb-17Li eutectic is the least. However, these results have been received without taking into account influence of a strong magnetic field. At the same time, this influence should be essential, as because of change of hydrodynamics of a liquid metal flow, and because of interaction of a magnetic field with a ferromagnetic steel. It has been shown that the magnetic field leads to increase of corrosion rate for austenitic (316L) and martensitic (1,4914) steels. Experimental data for EUROFER 97, and also a theoretical substantiation of the phenomenon are absent, that creates essential difficulties for forecasting working capacity of blanket construction. The aim of presented work were the theoretical and experimental investigations of magnetic field influence on the corrosion of EUROFER 97 steel exposed to flowing Pb-17Li in specific designed loop. (authors)

  17. Improving electrochemical properties of AISI 1045 steels by duplex surface treatment of plasma nitriding and aluminizing

    NASA Astrophysics Data System (ADS)

    Haftlang, Farahnaz; Habibolahzadeh, Ali; Sohi, Mahmoud Heydarzadeh

    2015-02-01

    Improvement in electrochemical behavior of AISI 1045 steel after applying aluminum nitride coating was investigated in 3.5% NaCl solution, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analyses. Aluminum nitride coating was applied on the steel surface by duplex treatment of pack aluminizing and plasma nitriding. Some specimens were plasma nitrided followed by aluminizing (PN-Al), while the others were pack aluminized followed by plasma nitriding (Al-PN). Topological and structural studies of the modified surfaces were conducted using scanning electron microscope (SEM) equipped by energy dispersive X-ray spectroscope (EDS), and X-ray diffractometer (XRD). The electrochemical measurements showed that the highest corrosion and polarization (Rp) resistances were obtained in PN-Al specimens, having single phase superficial layer of AlN. Pitting mechanism was dominant reason of lower corrosion resistance in the Al-PN specimens.

  18. Fracture toughness of the F-82H steel-effect of loading modes, hydrogen, and temperature

    NASA Astrophysics Data System (ADS)

    Li, H.-X.; Jones, R. H.; Hirth, J. P.; Gelles, D. S.

    1996-10-01

    The effects of loading mode, hydrogen, and temperature on fracture toughness and tearing modulus were examined for a ferritic/martensitic steel (F-82H). The introduction of a shear load component, mode III, significantly decreased the initiation and propagation resistance of cracks compared to the opening load, mode I, behavior. Mode I crack initiation and propagation exhibited the highest resistance. A minimum resistance occurred when the mode I and mode III loads were nearly equal. The presence of 4 wppm hydrogen decreased the cracking resistance compared to behavior without H regardless of the loading mode. The minimum mixed-mode fracture toughness with the presence of hydrogen was about 30% of the hydrogen-free mode I fracture toughness. The mixed-mode toughness exhibited a lesser sensitivity to temperature than the mode I toughness. The JIC value was 284 kJ/m 2 at room temperature, but only 60 kJ/m 2 at -55°C and 30 kJ/m 2 at -90°C. The ductile to brittle transition temperature (DBTT) was apparently higher than -55°C.

  19. Characterization of dual-phase steel microstructure by combined submicrometer EBSD and EPMA carbon measurements.

    PubMed

    Pinard, Philippe T; Schwedt, Alexander; Ramazani, Ali; Prahl, Ulrich; Richter, Silvia

    2013-08-01

    Electron backscatter diffraction (EBSD) and electron probe microanalysis (EPMA) measurements are combined to characterize an industrial produced dual-phase steel containing some bainite fraction. High-resolution carbon mappings acquired on a field emission electron microprobe are utilized to validate and improve the identification of the constituents (ferrite, martensite, and bainite) performed by EBSD using the image quality and kernel average misorientation. The combination eliminates the ambiguity between the identification of bainite and transformation-induced dislocation zones, encountered if only the kernel average misorientation is considered. The detection of carbon in high misorientation regions confirms the presence of bainite. These results are corroborated by secondary electron images after nital etching. Limitations of this combined method due to differences between the spatial resolution of EBSD and EPMA are assessed. Moreover, a quantification procedure adapted to carbon analysis is presented and used to measure the carbon concentration in martensite and bainite on a submicrometer scale. From measurements on reference materials, this method gives an accuracy of 0.02 wt% C and a precision better than 0.05 wt% C despite unavoidable effects of hydrocarbon contamination.

  20. Prediction of yield stress and Charpy transition temperature in highly neutron irradiated ferritic steels

    NASA Astrophysics Data System (ADS)

    Windsor, Colin; Cottrell, Geoff; Kemp, Richard

    2010-07-01

    Recent predictions have been made of metallurgical properties of low-activation ferritic/martensitic steels alloys at the high irradiation levels (displacements per atom or dpa) needed for a fusion power plant as based on measurements at low irradiation levels where more data are available. These predictions have been published for the yield stress and for the Charpy ductile to brittle transition temperature shift. The neural network model predictions use training data up to a certain dpa level to predict metallurgical properties above this level. This 'extrapolation' mode of neural networks is explored in some detail. Our studies revealed an increasing accuracy of predictions as the test dpa level is increased for both yield stress and Charpy shift predictions. This result suggests that a model exists for these metallurgical properties as a function of dpa level which becomes more accurate as the available irradiation range in the training data is increased. The explanation suggested is that the metallurgical annealing, which occurs as the irradiation level is increased, simplifies the microstructure and makes prediction more reliable.

  1. Interatomic potential to study the formation of NiCr clusters in high Cr ferritic steels

    NASA Astrophysics Data System (ADS)

    Bonny, G.; Bakaev, A.; Olsson, P.; Domain, C.; Zhurkin, E. E.; Posselt, M.

    2017-02-01

    Under irradiation NiSiPCr clusters are formed in high-Cr ferritic martensitic steels as well as in FeCr model alloys. In the literature little is known about the origin and contribution to the hardening of these clusters. In this work we performed density functional theory (DFT) calculations to study the stability of small substitutional NiCr-vacancy clusters and interstitial configurations in bcc Fe. Based on DFT data and experimental considerations a ternary potential for the ferritic FeNiCr system was developed. The potential was applied to study the thermodynamic stability of NiCr clusters by means of Metropolis Monte Carlo (MMC) simulations. The results of our simulations show that Cr and Ni precipitate as separate fractions and suggest only a limited synergetic effect between Ni and Cr. Therefore our results suggest that the NiCrSiP clusters observed in experiments must be the result of other mechanisms than the synergy of Cr and Ni at thermal equilibrium.

  2. Mechanically robust superhydrophobic steel surface with anti-icing, UV-durability, and corrosion resistance properties.

    PubMed

    Wang, Nan; Xiong, Dangsheng; Deng, Yaling; Shi, Yan; Wang, Kun

    2015-03-25

    A superhydrophobic steel surface was prepared through a facile method: combining hydrogen peroxide and an acid (hydrochloric acid or nitric acid) to obtain hierarchical structures on steel, followed by a surface modification treatment. Empirical grid maps based on different volumes of H2O2/acid were presented, revealing a wettability gradient from "hydrophobic" to "rose effect" and finally to "lotus effect". Surface grafting has been demonstrated to be realized only on the oxidized area. As-prepared superhydrophobic surfaces exhibited excellent anti-icing properties according to the water-dripping test under overcooled conditions and the artificial "steam-freezing" (from 50 °C with 90% humidity to the -20 °C condition) test. In addition, the surfaces could withstand peeling with 3M adhesive tape at least 70 times with an applied pressure of 31.2 kPa, abrasion by 400 grid SiC sandpaper for 110 cm under 16 kPa, or water impacting for 3 h without losing superhydrophobicity, suggesting superior mechanical durability. Moreover, outstanding corrosion resistance and UV-durability were obtained on the prepared surface. This successful fabrication of a robust, anti-icing, UV-durable, and anticorrosion superhydrophobic surface could yield a prospective candidate for various practical applications.

  3. Laser surface modification of 316 L stainless steel with bioactive hydroxyapatite.

    PubMed

    Balla, Vamsi Krishna; Das, Mitun; Bose, Sreyashree; Ram, G D Janaki; Manna, Indranil

    2013-12-01

    Laser-engineered net shaping (LENS™), a commercial additive manufacturing process, was used to modify the surfaces of 316 L stainless steel with bioactive hydroxyapatite (HAP). The modified surfaces were characterized in terms of their microstructure, hardness and apatite forming ability. The results showed that with increase in laser energy input from 32 J/mm(2) to 59 J/mm(2) the thickness of the modified surface increased from 222±12 μm to 355±6 μm, while the average surface hardness decreased marginally from 403±18 HV0.3 to 372±8 HV0.3. Microstructural studies showed that the modified surface consisted of austenite dendrites with HAP and some reaction products primarily occurring in the inter-dendritic regions. Finally, the surface-modified 316 L samples immersed in simulated body fluids showed significantly higher apatite precipitation compared to unmodified 316 L samples.

  4. Slurry Erosion Studies on Surface Modified 13Cr-4Ni Steels: Effect of Angle of Impingement and Particle Size

    NASA Astrophysics Data System (ADS)

    Manisekaran, T.; Kamaraj, M.; Sharrif, S. M.; Joshi, S. V.

    2007-10-01

    Hydroturbine steels, such as 13Cr-4Ni martensitic steels, are generally subjected to heavy-erosive wear and loss of efficiency due to solid particulate entrainment in the water. Surface-modified steels have proven to give better performance in terms of erosive wear resistance. In the present study, an attempt is made to investigate the effect of angle of impingement and particle size on slurry-jet erosion behavior of pulsed plasma nitrided and laser hardened 13Cr-4Ni steels. Laser hardening process has shown good performance at all angles of impingement due to martensitic transformation of retained austenite. Plastic deformation mode of material removal was also an evident feature of all laser-hardened surface damage locations. However, pulsed-plasma nitrided steels have exhibited chip formation and micro-cutting mode of erosive wear. Erosion with 150-300 μm size was twice compared to 150 μm size slurry particulates.

  5. Nanoscale surface analysis on second generation advanced high strength steel after hot dip galvanizing.

    PubMed

    Arndt, M; Duchoslav, J; Preis, K; Samek, L; Stifter, D

    2013-09-01

    Second generation advanced high strength steel is one promising material of choice for modern automotive structural parts because of its outstanding maximal elongation and tensile strength. Nonetheless there is still a lack of corrosion protection for this material due to the fact that cost efficient hot dip galvanizing cannot be applied. The reason for the insufficient coatability with zinc is found in the segregation of manganese to the surface during annealing and the formation of manganese oxides prior coating. This work analyses the structure and chemical composition of the surface oxides on so called nano-TWIP (twinning induced plasticity) steel on the nanoscopic scale after hot dip galvanizing in a simulator with employed analytical methods comprising scanning Auger electron spectroscopy (SAES), energy dispersive X-ray spectroscopy (EDX), and focused ion beam (FIB) for cross section preparation. By the combination of these methods, it was possible to obtain detailed chemical images serving a better understanding which processes exactly occur on the surface of this novel kind of steel and how to promote in the future for this material system galvanic protection.

  6. Quantitative characterization of the atomic-scale structure of oxyhydroxides in rusts formed on steel surfaces

    SciTech Connect

    Saito, M.; Suzuki, S. . E-mail: ssuzuki@tagen.tohoku.ac.jp; Kimura, M.; Suzuki, T.; Kihira, H.; Waseda, Y.

    2005-11-15

    Quantitative X-ray structural analysis coupled with anomalous X-ray scattering has been used for characterizing the atomic-scale structure of rust formed on steel surfaces. Samples were prepared from rust layers formed on the surfaces of two commercial steels. X-ray scattered intensity profiles of the two samples showed that the rusts consisted mainly of two types of ferric oxyhydroxide, {alpha}-FeOOH and {gamma}-FeOOH. The amounts of these rust components and the realistic atomic arrangements in the components were estimated by fitting both the ordinary and the environmental interference functions with a model structure calculated using the reverse Monte Carlo simulation technique. The two rust components were found to be the network structure formed by FeO{sub 6} octahedral units, the network structure itself deviating from the ideal case. The present results also suggest that the structural analysis method using anomalous X-ray scattering and the reverse Monte Carlo technique is very successful in determining the atomic-scale structure of rusts formed on the steel surfaces.

  7. Surface Roughness of Stainless Steel Bender Mirrors for FocusingSoft X-rays

    SciTech Connect

    Yashchuk, Valeriy V.; Gullikson, Eric M.; Howells, Malcolm R.; Irick, Steve C.; MacDowell, Alastair A.; McKinney, Wayne R.; Salmassi,Farhad; Warwick, Tony; Metz, James P.; Tonnessen, Thomas W.

    2005-10-11

    We have used polished stainless steel as a mirror substrate to provide focusing of soft x-rays in grazing incidence reflection. The substrate is bent to an elliptical shape with large curvature and high stresses in the substrate require a strong elastic material. Conventional material choices of silicon or of glass will not withstand the stress required. The use of steel allows the substrates to be polished and installed flat, using screws in tapped holes. The ultra-high-vacuum bender mechanism is motorized and computer controlled. These mirrors are used to deliver focused beams of soft x-rays onto the surface of a sample for experiments at the Advanced Light Source (ALS). They provide an illumination field that can be as small as the mirror demagnification allows, for localized study, and can be enlarged, under computer control,for survey measurements over areas of the surface up to several millimeters. The critical issue of the quality of the steel surface, polished and coated with gold, which limits the minimum achievable focused spot size is discussed in detail. Comparison is made to a polished, gold coated, electroless nickel surface, which provides a smoother finish. Surface measurements are presented as power spectral densities, as a function of spatial frequency. The surface height distributions measured with an interferometric microscope, and complemented by atomic force microscope measurements, are used to compute power spectral densities and then to evaluate the surface roughness. The effects of roughness in reducing the specular reflectivity are verified by soft x-ray measurements.

  8. Stainless steel surface functionalization for immobilization of antibody fragments for cardiovascular applications.

    PubMed

    Foerster, A; Hołowacz, I; Sunil Kumar, G B; Anandakumar, S; Wall, J G; Wawrzyńska, M; Paprocka, M; Kantor, A; Kraskiewicz, H; Olsztyńska-Janus, S; Hinder, S J; Bialy, D; Podbielska, H; Kopaczyńska, M

    2016-04-01

    Stainless steel 316 L material is commonly used for the production of coronary and peripheral vessel stents. Effective biofunctionalization is a key to improving the performance and safety of the stents after implantation. This paper reports the method for the immobilization of recombinant antibody fragments (scFv) on stainless steel 316 L to facilitate human endothelial progenitor cell (EPC) growth and thus improve cell viability of the implanted stents for cardiovascular applications. The modification of stent surface was conducted in three steps. First the stent surface was coated with titania based coating to increase the density of hydroxyl groups for successful silanization. Then silanization with 3 aminopropyltriethoxysilane (APTS) was performed to provide the surface with amine groups which presence was verified using FTIR, XPS, and fluorescence microscopy. The maximum density of amine groups (4.8*10(-5) mol/cm(2)) on the surface was reached after reaction taking place in ethanol for 1 h at 60 °C and 0.04M APTS. On such prepared surface the glycosylated scFv were subsequently successfully immobilized. The influence of oxidation of scFv glycan moieties and the temperature on scFv coating were investigated. The fluorescence and confocal microscopy study indicated that the densest and most uniformly coated surface with scFv was obtained at 37 °C after oxidation of glycan chain. The results demonstrate that the scFv cannot be efficiently immobilized without prior aminosilanization of the surface. The effect of the chemical modification on the cell viability of EPC line 55.1 (HucPEC-55.1) was performed indicating that the modifications to the 316 L stainless steel are non-toxic to EPCs.

  9. Surface Oxidation of the High-Strength Steels Electrodeposited with Cu or Fe and the Resultant Defect Formation in Their Coating during the Following Galvanizing and Galvannealing Processes

    NASA Astrophysics Data System (ADS)

    Choi, Yun-Il; Beom, Won-Jin; Park, Chan-Jin; Paik, Doojin; Hong, Moon-Hi

    2010-12-01

    This study examined the surface oxidation of high-strength steels electrodeposited with Cu or Fe and the resultant defect formation in their coating during the following galvanizing and galvannealing processes. The high-strength steels were coated with an Cu or Fe layer by the electroplating method. Then, the coated steels were annealed in a reducing atmosphere, dipped in a molten zinc, and finally transformed into galvannealed steels through the galvannealing process. The formation of Si and Mn oxides on the surface of the high-strength steel was effectively suppressed, and the density of surface defects on the galvanized steel was significantly reduced by the pre-electrodeposition of Cu and Fe. This effect was more prominent for the steels electrodeposited at higher cathodic current densities. The finer electrodeposit layer formed at higher cathodic current density on the steels enabled the suppression of partial surface oxidation by Mn or Si and better wetting of Zn on the surface of the steels in the following galvanizing process. Furthermore, the pre-electrodeposited steels exhibited a smoother surface without surface cracks after the galvannealing process compared with the untreated steel. The diffusion of Fe and Zn in the Zn coating layer in the pre-electrodeposited steels appears to occur more uniformly during the galvannealing process due to the low density of surface defects induced by oxides.

  10. SURFACE FINISHES ON STAINLESS STEEL REDUCE BACTERIAL ATTACHMENT AND EARLY BIOFILM FORMATION: SCANNING ELECTRON AND ATOMIC FORCE MICROSCOPY STUDY

    EPA Science Inventory

    Three common finishing treatments of stainless steel that are used for equipment during poultry processing were tested for resistance to bacterial contamination. Methods were developed to measure attached bacteria and to identify factors that make surface finishes susceptible or ...

  11. Application of steel 40Kh surface hardened by high-frequency currents in the production of gate valve parts

    SciTech Connect

    Veliev, T.K.; Arifulin, R.K.; Fataliev, N.S.; Safarov, R.S.

    1986-09-01

    Bench tests were performed to determine the change in roughness, planeness, and hardness of the sealing surfaces of parts of gate valves made with steel 40Kh surface-hardened by high-frequency currents (HFC). Most parts of the gate valves for oil wells are now made of steel 38Kh2MYuA containing molybdenum. It was of interest to conduct tests to find another steel (40Kh) with less precious alloying elements and to increase the hardness of the sealing surfaces. The tests showed that steel 40Kh with HFC surface hardening may be recommended for gate parts of straight-through gate valves with specific contact pressure of up to 70 MPa. The torque for controlling the gate must be 0.8-1kN. Tests were also conducted on an experimental batch of Christmas trees and tubing heads; those results are presented.

  12. Surface-protein interactions on different stainless steel grades: effects of protein adsorption, surface changes and metal release.

    PubMed

    Hedberg, Y; Wang, X; Hedberg, J; Lundin, M; Blomberg, E; Wallinder, I Odnevall

    2013-04-01

    Implantation using stainless steels (SS) is an example where an understanding of protein-induced metal release from SS is important when assessing potential toxicological risks. Here, the protein-induced metal release was investigated for austenitic (AISI 304, 310, and 316L), ferritic (AISI 430), and duplex (AISI 2205) grades in a phosphate buffered saline (PBS, pH 7.4) solution containing either bovine serum albumin (BSA) or lysozyme (LSZ). The results show that both BSA and LSZ induce a significant enrichment of chromium in the surface oxide of all stainless steel grades. Both proteins induced an enhanced extent of released iron, chromium, nickel and manganese, very significant in the case of BSA (up to 40-fold increase), whereas both proteins reduced the corrosion resistance of SS, with the reverse situation for iron metal (reduced corrosion rates and reduced metal release in the presence of proteins). A full monolayer coverage is necessary to induce the effects observed.

  13. Surface layer structure of AISI 1020 steel at different stages of dry sliding under electric current of high density

    NASA Astrophysics Data System (ADS)

    Aleutdinov, K. A.; Rubtsov, V. Ye; Fadin, V. V.; Aleutdinova, M. I.

    2016-02-01

    Wear intensity of the sliding electric contact steel 1020/steel 1045 depending on sliding time is presented at the contact current density higher than 100 A/cm2 without lubricant. It is shown that wear intensity of 1020 steel decreases at increasing of sliding time. Wear intensity is stabilized after some sliding time. This time (burn-in time) decreases at reduction of current density. Structural changes are realized in surface layer. Signs of liquid phase are observed on sliding surface. This liquid isn't a result of melting. It is established using Auger spectrometry that the contact layer contains up to 50 at.% of oxygen.

  14. Influence of steel implant surface microtopography on soft and hard tissue integration.

    PubMed

    Hayes, J S; Klöppel, H; Wieling, R; Sprecher, C M; Richards, R G

    2017-03-21

    After implantation of an internal fracture fixation device, blood contacts the surface, followed by protein adsorption, resulting in either soft-tissue adhesion or matrix adhesion and mineralization. Without protein adsorption and cell adhesion under the presence of micro-motion, fibrous capsule formation can occur, often surrounding a liquid filled void at the implant-tissue interface. Clinically, fibrous capsule formation is more prevalent with electropolished stainless steel (EPSS) plates than with current commercially pure titanium (cpTi) plates. We hypothesize that this is due to lack of micro-discontinuities on the standard EPSS plates. To test our hypothesis, four EPSS experimental surfaces with varying microtopographies were produced and characterized for morphology using the scanning electron microscope, quantitative roughness analysis using laser profilometry and chemical analysis using X-ray photoelectron spectroscopy. Clinically used EPSS (smooth) and cpTi (microrough) were included as controls. Six plates of each type were randomly implanted, one on both the left and right intact tibia of 18 white New Zealand rabbits for 12 weeks, to allow for a surface interface study. The results demonstrate that the micro-discontinuities on the upper surface of internal steel fixation plates reduced the presence of liquid filled voids within soft-tissue capsules. The micro-discontinuities on the plate under-surface increased bony integration without the presence of fibrous tissue interface. These results support the hypothesis that the fibrous capsule and the liquid filled void formation occurs mainly due to lack of micro-discontinuities on the polished smooth steel plates and that bony integration is increased to surfaces with higher amounts of micro-discontinuities. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017.

  15. Influence of Thermal Aging on the Microstructure and Mechanical Behavior of Dual Phase Precipitation Hardened Powder Metallurgy Stainless Steels

    NASA Astrophysics Data System (ADS)

    Stewart, Jennifer

    2011-12-01

    Increasing demand for high strength powder metallurgy (PM) steels has resulted in the development of dual phase PM steels. In this work, the effects of thermal aging on the microstructure and mechanical behavior of dual phase precipitation hardened powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 538°C in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite hardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties. Due to the complex non-uniform stresses and strains associated with conventional nanoindentation, micropillar compression has become an attractive method to probe local mechanical behavior while limiting strain gradients and contributions from surrounding features. In this study, micropillars of ferrite and martensite were fabricated by focused ion beam (FIB) milling of dual phase precipitation hardened powder metallurgy (PM) stainless steels. Compression testing was conducted using a nanoindenter equipped with a flat punch indenter. The stress-strain curves of the individual microconstituents were calculated from the load-displacement curves less the extraneous displacements of the system. Using a rule of mixtures approach in conjunction with porosity corrections, the mechanical properties of ferrite and martensite were combined for comparison to tensile tests of the bulk material, and reasonable agreement was found for the ultimate tensile

  16. Influence of Alginate on Attachment of Vibrio spp. to Stainless Steel Surfaces in Seawater

    PubMed Central

    Gordon, Andrew S.

    1987-01-01

    The influence of alginate on the attachment of Vibrio alginolyticus and Vibrio pelagius biovar II to stainless steel was investigated. When the bacteria were in stationary phase, alginate decreased the number of attached bacteria in the case of each Vibrio sp. In contrast, when V. pelagius biovar II was grown on alginate and harvested in log phase, attachment was increased. This effect may be due to nutrient availability at the surface or to receptors on the bacterial surface which interact with alginate adsorbed to the metal. PMID:16347345

  17. Macro-carriers of plastic deformation of steel surface layers detected by digital image correlation

    SciTech Connect

    Kopanitsa, D. G. Ustinov, A. M.; Potekaev, A. I.; Klopotov, A. A.; Kopanitsa, G. D.

    2016-01-15

    This paper presents a study of characteristics of an evolution of deformation fields in surface layers of medium-carbon low-alloy specimens under compression. The experiments were performed on the “Universal Testing Machine 4500” using a digital stereoscopic image processing system Vic-3D. A transition between stages is reflected as deformation redistribution on the near-surface layers. Electronic microscopy shows that the structure of the steel is a mixture of pearlite and ferrite grains. A proportion of pearlite is 40% and ferrite is 60%.

  18. Surface roughness analysis of hardened steel after high-speed milling.

    PubMed

    Twardowski, Paweł; Wojciechowski, Szymon; Wieczorowski, Michał; Mathia, Thomas

    2011-01-01

    The work refers to analysis of various factors affecting surface roughness after end milling of hardened steel in high-speed milling (HSM) conditions. Investigations of milling parameters (cutting speed v(c) , axial depth of cut a(p) ) and the process dynamics that influence machined surface roughness were presented, and a surface roughness model, including cutter displacements, was elaborated. The work also involved analysis of surface profile charts from the point of view of vibrations and cutting force components. The research showed that theoretic surface roughness resulting from the kinematic-geometric projection of cutting edge in the workpiece is significantly different from the reality. The dominant factor in the research was not feed per tooth f(z) (according to the theoretical model) but dynamical phenomena and feed per revolution f.

  19. Study on surface finish of AISI 2080 steel based on the Taguchi method

    NASA Astrophysics Data System (ADS)

    Yalcinkaya, S.; Şahin, Y.

    2017-02-01

    Surface finish and dimensional accuracy play a vital role in manufacturing engineering applications. Grinding is one of the most important methods for producing a better surface quality. This paper describes a study of the influences of cutting parameters such as table speed, depth of cut and feed rate on surface finish of AISI 2080 steels, based on the Taguchi (L27) method. The experimental results showed that the table speed was the machining parameter, which had a greater effect on the surface finish, followed by depth of cut, whereas feed rate showed no significant effect. Analysis of variance indicated that a better surface finish was obtained at 190 m/min speed, 0.003 mm depth of cut and 0.08 mm/rev feed rate.

  20. EVALUATION OF ALTERNATE STAINLESS STEEL SURFACE TREATMENTS FOR MASS SPECTROSCOPY AND OTHER TRITIUM SYSTEMS

    SciTech Connect

    Clark, E.; Mauldin, C.; Neikirk, K.

    2012-02-29

    There are specific components in the SRS Tritium Facilities that are required to introduce as few chemical impurities (such as protium and methane) as possible into the process gas. Two such components are the inlet systems for the mass spectroscopy facilities and hydrogen isotope mix standard containers. Two vendors now passivate stainless steel components for these systems, and both are relatively small businesses whose future viability can be questioned, which creates the need for new sources. Stainless steel containers were designed to evaluate alternate surface treatment vendors for tritium storage and handling for these high purity tritium systems. Five vendors applied their own 'best' surface treatments to two containers each - one was a current vendor, another was a chemical vapor deposited silicon coating, and the other three were electropolishing and chemical cleaning vendors. Pure tritium gas was introduced into all ten containers and the composition was monitored over time. The only observed impurities in the gas were some HT, less CT{sub 4}, and very small amounts of T{sub 2}O in all cases. The currently used vendor treated containers contained the least impurities. The chemical vapor deposited silicon treatment resulted in the highest impurity levels. Sampling one set of containers after about one month of tritium exposure revealed the impurity level to be nearly the same as that after more than a year of exposure - this result suggests that cleaning new stainless steel components by tritium gas contact for about a month may be a worthy operation.

  1. Effect of microbial treatment on the prevention and removal of paraffin deposits on stainless steel surfaces.

    PubMed

    Xiao, Meng; Li, Wen-Hong; Lu, Mang; Zhang, Zhong-Zhi; Luo, Yi-Jing; Qiao, Wei; Sun, Shan-Shan; Zhong, Wei-Zhang; Zhang, Min

    2012-11-01

    In this study, biosurfactant-producing strain N2 and non-biosurfactant producing stain KB18 were used to investigate the effects of microbial treatment on the prevention and removal of paraffin deposits on stainless steel surfaces. Strain N2, with a biosurfactant production capacity, reduced the contact angle of stainless steel to 40.04°, and the corresponding adhesion work of aqueous phase was decreased by 26.5 mJ/m(2). By contrast, KB18 could only reduce the contact angle to 50.83°, with a corresponding 7.6 mJ/m(2) decrease in the aqueous phase work adhesion. The paraffin removal test showed that the paraffin removal efficiencies of strain N2 and KB18 were 79.0% and 61.2%, respectively. Interestingly, the N2 cells could attach on the surface of the oil droplets to inhibit droplets coalescence. These results indicate that biosurfactant-producing strains can alter the wettability of stainless steel and thus eliminate paraffin deposition.

  2. Facile fabrication of micro-nano-rod structures for inducing a superamphiphobic property on steel surface

    NASA Astrophysics Data System (ADS)

    Li, Hao; Yu, Sirong

    2016-01-01

    The development of the lyophobic surface has potentially practical value in many fields. In this study, a superamphiphobic ZnO film was fabricated on X90 pipeline steel surface via a combined approach using electrodeposition, hydrothermal treatment and chemical modification. The ZnO with micro-nano-rod structures was in situ grown on the deposited Zn coating, and the chemical modification achieved superomniphobic property of the ZnO film. The contact angles of water and glycerol on this film were about 157.59° and 153.76°, respectively, and the sliding angles of them were <10°. In addition, the superamphiphobic ZnO film was excellent repellent to other liquids, including salted water, ethanol-water, crude oil and wax. Both the morphology and the low-surface-energy material play key roles in fabricating the superamphiphobic ZnO film on the steel surface. Importantly, the deposited Zn coating and the superamphiphobic ZnO film ensure the surface with corrosion resistance and excellent lyophobic property, respectively.

  3. An investigation of phase transformation and crystallinity in laser surface modified H13 steel

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2013-03-01

    This paper presents a laser surface modification process of AISI H13 tool steel using 0.09, 0.2 and 0.4 mm size of laser spot with an aim to increase hardness properties. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). X-ray diffraction analysis (XRD) was conducted to measure crystallinity of the laser-modified surface. X-ray diffraction patterns of the samples were recorded using a Bruker D8 XRD system with Cu K α ( λ=1.5405 Å) radiation. The diffraction patterns were recorded in the 2 θ range of 20 to 80°. The hardness properties were tested at 981 mN force. The laser-modified surface exhibited reduced crystallinity compared to the un-processed samples. The presence of martensitic phase was detected in the samples processed using 0.4 mm spot size. Though there was reduced crystallinity, a high hardness was measured in the laser-modified surface. Hardness was increased more than 2.5 times compared to the as-received samples. These findings reveal the phase source of the hardening mechanism and grain composition in the laser-modified surface.

  4. RESULTS OF CHARACTERIZATION TESTS OF THE SURFACES OF A COMMERCIALLY CARBURIZED AUSTENITIC STAINLESS STEEL

    SciTech Connect

    Farrell, K

    2004-01-07

    A commercial surface carburization treatment that shows promise for hardening the surfaces of the stainless steel target vessel of the Spallation Neutron Source against cavitation erosion and pitting caused by the action of pulsed pressure waves in the liquid mercury target has been investigated. To verify promotional claims for the treatment and to uncover any factors that might be of concern for the integrity of a carburized target vessel, some characterization tests of the nature of the surface layers of carburized austenitic 316LN stainless steel were conducted. The findings support most of the claims. The carburized layer is about 35 {micro}m thick. Its indentation hardness is about five times larger than that of the substrate steel and declines rapidly with depth into the layer. The surface is distorted by the treatment, and the austenite lattice is enlarged. The corrosion resistance of the carburized layer in an acid medium is greater than that for untreated austenite. The layer is not brittle; it is plastically deformable and is quite resistant to cracking during straining. Contrary to the provider's assertations, the maximum carbon content of the layer is much less than 6-7 wt% carbon, and the carbon is not simply contained in supersaturated solid solution; some of it is present in a previously unreported iron carbide phase located at the very surface. Large variations were found in the thickness of the layer, and they signify that controls may be needed to ensure a uniform thickness for treatment of the SNS target vessel. Inclusion stringers and {delta}-ferrite phase embraced in the treated layer are less resistant to chemical attack than the treated austenite. From a cavitation pitting perspective under SNS bombardment, such non-austenitic phases may provide preferential sites for pitting. The shallow depth of the hardened layer will require use of protection measures to avoid mishandling damage to the layer during assembly and installation of a target

  5. Assessment of precipitation in alloy steel using nonlinear Rayleigh surface waves

    NASA Astrophysics Data System (ADS)

    Thiele, Sebastian; Matlack, Kathryn H.; Kim, Jin-Yeon; Qu, Jianmin; Wall, James J.; Jacobs, Laurence J.

    2014-02-01

    Nonlinear ultrasonic waves have shown to be sensitive to various microstructural changes in metals including coherent precipitates; these precipitates introduce a strain field in the lattice structure. The thermal aging of certain alloy steels leads to the formation of coherent precipitates, which pin dislocations and contribute to the generation of a second harmonic component. A precipitate hardenable material namely 17-4 PH stainless steel is thermally treated in this research to obtain different precipitation stages, and then the influence of precipitates on the acoustic nonlinearity parameter is assessed. Conclusions about the microstrucutural changes in the material are drawn based on the results from a nonlinear Rayleigh surface wave measurement and complementary thermo-electric power, hardness and ultrasonic velocity measurements. The results show that the nonlinear parameter is sensitive to coherent precipitates in the material and moreover that precipitation characteristics can be characterized based on the obtained experimental data.

  6. Surface modification of superaustenitic and maraging stainless steels by low-temperature gas-phase carburization

    NASA Astrophysics Data System (ADS)

    Gentil, Johannes

    Low-temperature gas-phase carburization of 316L austenitic stainless steel was developed in recent years by the Swagelok company. This process generates great mechanical and electrochemical surface properties. Hardness, wear resistance, fatigue behavior, and corrosion resistance are dramatically improved, while the formation of carbides is effectively suppressed. This new technique is of technical, economical, but especially of scientific interest because the surface properties of common stainless steel can be enhanced to a level of more sophisticated and more expensive superalloys. The consequential continuation of previous research is the application of the carburization process to other steel grades. Differences in chemical composition, microstructure, and passivity between the various alloys may cause technical problems and it is expected that the initial process needs to be optimized for every specific material. This study presents results of low-temperature carburization of AL-6XN (superaustenitic stainless steel) and PH13-8Mo (precipitation-hardened martensitic stainless steel). Both alloys have been treated successfully in terms of creating a hardened surface by introducing high amounts of interstitially dissolved carbon. The surface hardness of AL-6XN was increased to 12GPa and is correlated with a colossal carbon supersaturation at the surface of up to 20 at.%. The hardened case develops a carburization time-dependent thickness between 10mum after one carburization cycle and up to 35mum after four treatments and remains highly ductile. Substantial broadening of X-ray diffraction peaks in low-temperature carburized superaustenitic stainless steels are attributed to the generation of very large compressive biaxial residual stresses. Those large stresses presumably cause relaxations of the surface, so-called undulations. Heavily expanded regions of carburized AL-6XN turn ferromagnetic. Non-carburized AL-6XN is known for its outstanding corrosion resistance

  7. The use of physicochemical methods to detect organic food soils on stainless steel surfaces.

    PubMed

    Whitehead, K A; Benson, P; Smith, L A; Verran, J

    2009-11-01

    Food processing surfaces fouled with organic material pose problems ranging from aesthetic appearance, equipment malfunction and product contamination. Despite the importance of organic soiling for subsequent product quality, little is known about the interaction between surfaces and organic soil components. A range of complex and defined food soils was applied to 304 stainless steel (SS) surfaces to determine the effect of type and concentration of soil on surface physicochemical parameters, viz surface hydrophobicity (DeltaG(iwi)), surface free energy (gamma(s)), Lifshitz van der Waals (gamma_LW(s)), Lewis acid base (gamma_AB(s)), electron acceptor (gamma_+(s) ) and electron donor (gamma_-(s) ) measurements. When compared to the control surface, changes in gamma_AB(s), gamma_+(s) and gamma_-(s) were indicative of surface soiling. However, soil composition and surface coverage were heterogeneous, resulting in complex data being generated from which trends could not be discerned. These results demonstrate that the retention of food soil produces changes in the physicochemical parameters of the surface that could be used to indicate the hygienic status of a surface.

  8. Corrosion in Supercritical carbon Dioxide: Materials, Environmental Purity, Surface Treatments, and Flow Issues

    SciTech Connect

    Sridharan, Kumar; Anderson, Mark

    2013-12-10

    The supercritical CO{sub 2} Brayton cycle is gaining importance for power conversion in the Generation IV fast reactor system because of its high conversion efficiencies. When used in conjunction with a sodium fast reactor, the supercritical CO{sub 2} cycle offers additional safety advantages by eliminating potential sodium-water interactions that may occur in a steam cycle. In power conversion systems for Generation IV fast reactors, supercritical CO{sub 2} temperatures could be in the range of 30°C to 650°C, depending on the specific component in the system. Materials corrosion primarily at high temperatures will be an important issue. Therefore, the corrosion performance limits for materials at various temperatures must be established. The proposed research will have four objectives centered on addressing corrosion issues in a high-temperature supercritical CO{sub 2} environment: Task 1: Evaluation of corrosion performance of candidate alloys in high-purity supercritical CO{sub 2}: The following alloys will be tested: Ferritic-martensitic Steels NF616 and HCM12A, austenitic alloys Incoloy 800H and 347 stainless steel, and two advanced concept alloys, AFA (alumina forming austenitic) steel and MA754. Supercritical CO{sub 2} testing will be performed at 450°C, 550°C, and 650°C at a pressure of 20 MPa, in a test facility that is already in place at the proposing university. High purity CO{sub 2} (99.9998%) will be used for these tests. Task 2: Investigation of the effects of CO, H{sub 2}O, and O{sub 2} impurities in supercritical CO{sub 2} on corrosion: Impurities that will inevitably present in the CO{sub 2} will play a critical role in dictating the extent of corrosion and corrosion mechanisms. These effects must be understood to identify the level of CO{sub 2} chemistry control needed to maintain sufficient levels of purity to manage corrosion. The individual effects of important impurities CO, H{sub 2}O, and O{sub 2} will be investigated by adding them

  9. Evaluation of peracetic acid sanitizers efficiency against spores isolated from spoiled cans in suspension and on stainless steel surfaces.

    PubMed

    André, S; Hédin, S; Remize, F; Zuber, F

    2012-02-01

    The aim of this study was to determine the inactivation effect of industrial formulations of peracetic acid biocides on bacterial spores adhering to stainless steel surfaces. A standardized protocol was used to validate biocide activity against spores in suspension. To validate sporicidal activity under practical conditions, we developed an additional protocol to simulate industrial sanitization of stainless steel surfaces with a foam sanitizer. Spores of three spore-forming bacteria, Clostridium sporogenes PA3679, Geobacillus stearothermophilus, and Moorella thermoacetica/thermoautotrophica, were sprayed onto stainless steel as bioaerosols. Sporicidal activity was high against the C. sporogenes spore suspension, with more than 5 log CFU ml(-1) destroyed at all liquid biocide contact times. Sporicidal activity also was high against G. stearothermophilus and M. thermoacetica/thermoautotrophica spores after 30 min of contact, but we found no population reduction at the 5-min contact time for the highest sporicide concentration tested. The foam biocide effectively inactivated C. sporogenes spores adhered to stainless steel but had a reduced decontamination effect on other species. For G. stearothermophilus spores, sanitization with the foam sporicide was more efficient on horizontal steel than on vertical steel, but foam sanitization was ineffective against M. thermoacetica/thermoautotrophica whatever the position. These results highlight that decontamination efficiency may differ depending on whether spores are suspended in an aqueous solution or adhered to a stainless steel surface. Biocide efficiency must be validated using relevant protocols and bacteria representative of the microbiological challenges and issues affecting each food industry.

  10. Characterization of Surface Films Formed During Corrosion of a Pipeline Steel in H2S Environments

    NASA Astrophysics Data System (ADS)

    Huang, F.; Cheng, P.; Dong, Y. Y.; Liu, J.; Hu, Q.; Zhao, X. Y.; Cheng, Y. Frank

    2017-02-01

    In this work, the surface films formed on an X52 pipeline steel in H2S-containing environments with various pH values and H2S concentrations were characterized by surface analysis techniques and electrochemical impedance spectroscopy. A stoichiometric FeS film is formed during H2S corrosion of the steel. At low pH (e.g., 3.5) and low H2S concentration (e.g., 0.2 mmol/L), the film is primarily crystalline FeS. When the H2S concentration increases to 2 and 20 mmol/L, mackinawite is also formed. At high pH of 5.5 and low H2S concentration of 0.2 mmol/L, the film is amorphous FeS. With the increase in the H2S concentration to 2 and 20 mmol/L, the film changes to crystalline FeS and the mixture of crystalline FeS and mackinawite, respectively. In low-pH solution (pH 3.5), the compact, crystalline FeS is more protective for steel corrosion compared to mackinawite. As the H2S concentration increases, the corrosion is increased. At high pH of 5.5, when the H2S concentration is 0.2 mmol/L, the low corrosivity of the environment causes production of amorphous FeS only. As the H2S concentration is increased, a thick film is generated, reducing somewhat the steel corrosion.

  11. Characterization of Surface Films Formed During Corrosion of a Pipeline Steel in H2S Environments

    NASA Astrophysics Data System (ADS)

    Huang, F.; Cheng, P.; Dong, Y. Y.; Liu, J.; Hu, Q.; Zhao, X. Y.; Cheng, Y. Frank

    2017-01-01

    In this work, the surface films formed on an X52 pipeline steel in H2S-containing environments with various pH values and H2S concentrations were characterized by surface analysis techniques and electrochemical impedance spectroscopy. A stoichiometric FeS film is formed during H2S corrosion of the steel. At low pH (e.g., 3.5) and low H2S concentration (e.g., 0.2 mmol/L), the film is primarily crystalline FeS. When the H2S concentration increases to 2 and 20 mmol/L, mackinawite is also formed. At high pH of 5.5 and low H2S concentration of 0.2 mmol/L, the film is amorphous FeS. With the increase in the H2S concentration to 2 and 20 mmol/L, the film changes to crystalline FeS and the mixture of crystalline FeS and mackinawite, respectively. In low-pH solution (pH 3.5), the compact, crystalline FeS is more protective for steel corrosion compared to mackinawite. As the H2S concentration increases, the corrosion is increased. At high pH of 5.5, when the H2S concentration is 0.2 mmol/L, the low corrosivity of the environment causes production of amorphous FeS only. As the H2S concentration is increased, a thick film is generated, reducing somewhat the steel corrosion.

  12. The features of steel surface hardening with high energy heating by high frequency currents and shower cooling

    NASA Astrophysics Data System (ADS)

    Ivancivsky, V. V.; Skeeba, V. Yu; Bataev, I. A.; Lobanov, D. V.; Martyushev, N. V.; Sakha, O. V.; Khlebova, I. V.

    2016-11-01

    The paper examines the process of surface hardening of steel 45 with the help of high energy heating by high frequency currents with simultaneous shower water cooling. We theoretically justified and experimentally proved a possibility of liquid phase forming in the course of heating not on the surface, but in the depth of the surface layer.

  13. Method of Electrolyte-Plasma Surface Hardening of 65G and 20GL Low-Alloy Steels Samples

    NASA Astrophysics Data System (ADS)

    Rakhadilov, Bauyrzhan; Zhurerova, Laila; Pavlov, Alexander

    2016-08-01

    This work is devoted to formation of modified surface layers in 65G and 20GL steels which using for the manufacture of railway transport parts, as well as the study of influence of the parametersof electrolyte-plasma surface hardening methodon the changes in structural-phase states, improving of wear-resistance. The process of electrolyte-plasma surface hardening of 65G and 20GL steels samples conducted in the electrolyte from water solution of 20% sodium carbonate, in the mode ~850°C - 2 seconds, ∼⃒1200°C - 3 seconds. It is established that in the initial state 20GL steel has ferrite-pearlite structure, and the 60G steel consists of pearlite and cement structure. After application of electrolyte-plasma surface hardening is observed the formation of carbides particles and martensite phase components in the structure of 20GL and 60G steels. It is determined that after electrolyte-plasma surface hardening with heating time - 2 seconds, the abrasive wear-resistance of 65G and 20GL steels increased to 1.3 times and 1.2 times, respectively, and the microhardness is increased to 1.6 times and 1.3 times, respectively.

  14. Effects of inoculation level, material hydration, and stainless steel surface roughness on the transfer of listeria monocytogenes from inoculated bologna to stainless steel and high-density polyethylene.

    PubMed

    Rodríguez, Andrés; Autio, Wesley R; McLandsborough, Lynne A

    2007-06-01

    The influence of inoculation level, material hydration, and stainless steel surface roughness on the transfer of Listeria monocytogenes from inoculated bologna to processing surfaces (stainless steel and polyethylene) was assessed. Slices of bologna (14 g) were inoculated with Listeria at different levels, from 10(5) to 10(9) CFU/cm2. Transfer experiments were done at a constant contact time (30 s) and pressure (45 kPa) with a universal testing machine. After transfer, cells that had been transferred to sterile stainless steel and polyethylene were removed and counted, and the efficiency of transfer (EOT) was calculated. As the inoculation level increased from 10(5) to 10(9) CFU/cm(2), the absolute level of transfer increased in a similar fashion. By calculating EOTs, the data were normalized, and the initial inoculation level had no effect on the transfer (P > 0.05). The influence of hydration level on stainless steel, high-density polyethylene, and material type was investigated, and the EOTs ranged from 0.1 to 1 under all the conditions tested. Our results show that transfers to wetted processing surfaces (mean EOT = 0.43) were no different from dried processing surfaces (mean EOT = 0.35) (P > 0.05). Material type was shown to be a significant factor, with greater numbers of Listeria transferring from bologna to stainless steel (mean EOT = 0.49) than from bologna to polyethylene (mean EOT = 0.28) (P < 0.01). Stainless steel with three different surface roughness (Ra) values of <0.8 microm (target Ra = 0.25, 0.50, and 0.75 Vmicrom) and two different finishes (mechanically polished versus mechanically polished and further electropolished) was used to evaluate its effect on the transfer. The surface roughness and finish on the stainless steel did not have any effect on the transfer of Listeria (P > 0.05). Our results showed that when evaluating the transfer of Listeria, the use of EOTs rather than the absolute transfer values is essential to allow comparisons of

  15. Machining Performance and Surface Integrity of AISI D2 Die Steel Machined Using Electrical Discharge Surface Grinding Process

    NASA Astrophysics Data System (ADS)

    Choudhary, Rajesh; Kumar, Harmesh; Singh, Shankar

    2013-12-01

    The aim of this study is to establish optimum machining conditions for EDSG of AISI D2 die steel through an experimental investigation using Taguchi Methodology. To achieve combined grinding and electrical discharge machining, metal matrix composite electrodes (Cu-SiCp) were processed through powder metallurgy route. A rotary spindle attachment was developed to perform the EDSG experimental runs on EDM machine. Relationships were developed between various input parameters such as peak current, speed, pulse-on time, pulse-off time, abrasive particle size, and abrasive particle concentration, and output characteristics such as material removal rate and surface roughness. The optimized parameters were further validated by conducting confirmation experiments.

  16. Surface modification of AISI H13 tool steel by laser cladding with NiTi powder

    NASA Astrophysics Data System (ADS)

    Norhafzan, B.; Aqida, S. N.; Chikarakara, E.; Brabazon, D.

    2016-04-01

    This paper presents laser cladding of NiTi powder on AISI H13 tool steel surface for surface properties enhancement. The cladding process was conducted using Rofin DC-015 diffusion-cooled CO2 laser system with wavelength of 10.6 µm. NiTi powder was pre-placed on H13 tool steel surface. The laser beam was focused with a spot size of 90 µm on the sample surface. Laser parameters were set to 1515 and 1138 W peak power, 18 and 24 % duty cycle and 2300-3500 Hz laser pulse repetition frequency. Hardness properties of the modified layer were characterized by Wilson Hardness tester. Metallographic study and chemical composition were conducted using field emission scanning electron microscope and energy-dispersive X-ray spectrometer (EDXS) analysis. Results showed that hardness of NiTi clad layer increased three times that of the substrate material. The EDXS analysis detected NiTi phase presence in the modified layer up to 9.8 wt%. The metallographic study shows high metallurgical bonding between substrate and modified layer. These findings are significant to both increased hardness and erosion resistance of high-wear-resistant components and elongating their lifetime.

  17. Evaluation of a Surface Treatment on the Performance of Stainless Steels for SOFC Interconnect Applications

    SciTech Connect

    Alman, D.E.; Holcomb, Adler, T.A.; G.R.; Wilson, R.D.; Jablonski, P.D.

    2007-04-01

    Pack cementation-like Cerium based surface treatments have been found to be effective in enhancing the oxidation resistance of ferritic steels (Crofer 22APU) for solid oxide fuel cell (SOFC) applications. The application of either a CeN- or CeO2 based surface treatment results in a decrease in weight gain by a factor of three after 4000 hours exposure to air+3%H2O at 800oC. Similar oxide scales formed on treated and untreated surfaces, with a continuous Cr-Mn outer oxide layer and a continuous inner Cr2O3 layer formed on the surface. However, the thickness of the scales, and the amount of internal oxidation were significantly reduced with the treatment, leading to the decrease in oxidation rate. This presentation will detail the influence of the treatment on the electrical properties of the interconnect. Half-cell experiments (LSM cathode sandwiched between two steel interconnects) and full SOFC button cell experiments were run with treated and untreated interconnects. Preliminary results indicate the Ce treatment can improve SOFC performance.

  18. Formation of Al2O3/FeAl coatings on a 9Cr-1Mo steel, and corrosion evaluation in flowing Pb-17Li loop

    NASA Astrophysics Data System (ADS)

    Majumdar, Sanjib; Paul, Bhaskar; Chakraborty, Poulami; Kishor, Jugal; Kain, Vivekanand; Dey, Gautam Kumar

    2017-04-01

    Iron aluminide coating layers were formed on a ferritic martensitic grade 9Cr-1Mo (P 91) steel using pack aluminizing process. The formation of different aluminide compositions such as orthorhombic-Fe2Al5, B2-FeAl and A2-Fe(Al) on the pack chemistry and heat treatment conditions have been established. About 4-6 μm thick Al2O3 scale was formed on the FeAl phase by controlled heat treatment. The corrosion tests were conducted using both the FeAl and Al2O3/FeAl coated specimens in an electro-magnetic pump driven Pb-17Li Loop at 500 °C for 5000 h maintaining a flow velocity of 1.5 m/s. The detailed characterization studies using scanning electron microscopy, back-scattered electron imaging and energy dispersive spectrometry revealed no deterioration of the coating layers after the corrosion tests. Self-healing oxides were formed at the cracks generated in the aluminide layers during thermal cycling and protected the base alloy (steel) from any kind of elemental dissolution or microstructural degradation.

  19. Surface Microstructure and Properties of Pulsed Laser Micro Melted S7 Tool Steel

    NASA Astrophysics Data System (ADS)

    Morrow, Justin D.

    The objective of this work is to better understand the changes that occur in the surface microstructure and hardness due to pulsed laser micro melting (PLmuM) on AISI S7 tool steel and how these results change with the laser processing parameters. Pulsed laser micro polishing (PLmuP), using PLmuM on rough surfaces for smoothing, has been well studied at UW - Madison, but is still generally a small research area and previous work at UW - Madison as well as the bulk of related work from other universities and research institutes has focused on surface smoothing, not surface microstructure and properties. Therefore, the present work focuses on characterizing the effect of PLmuM on the surface microstructure transformations, hardness, and wear resistance in AISI S7 tool steel. An observational approach was taken to characterize the microstructure that is formed during PLmuM and evaluate the hardness and wear resistance of this final surface. Several experimental methods were used: The surface microstructure was evaluated using metallographic polishing and etching along with scanning electron microscopy (SEM) and x-ray diffraction (XRD). This work found that the microstructure after PLmuM is martensitic (lath martensite) and after overlapping to form a melted area, significant carbide precipitation can occur near the overlap regions. It was found that the size and prevalence of the carbides varies locally and carbides are coarser closer to the overlap region. The amount of carbide precipitation (tempering) was also found to depend on the laser parameters used. An XRD study showed that tempering could also be observed as a shifting of the martensite peak that correlated with hardness and tempering observed with SEM. The surface properties were also evaluated using nanoindentation and nanoscratch testing. These tests showed that the local tempering variation observed in the microstructure translated into local hardness variation with an inverse relationship between

  20. Surface preparation effects on GTA (gas tungsten arc) weld penetration in JBK-75 stainless steel

    SciTech Connect

    Campbell, R.D.; Heiple, C.R.; Sturgill, P.L.; Robertson, A.M.; Jamsay, R.

    1989-01-01

    The results of a study are reported here on the effects of surface preparation on the shape of GTA welds on JBK-75, an austenitic precipitation hardenable stainless steel similar to A286. Minor changes in surface (weld groove) preparation produced substantial changes in the penetration characteristics and welding behavior of this alloy. Increased and more consistent weld penetration (higher d/w ratios) along with improved arc stability and less arc wander result from wire brushing and other abrasive surface preparations, although chemical and machining methods did not produce any improvement in penetration. Abrasive treatments roughen the surface, increase the surface area, and increase the surface oxide thickness. The increased weld d/w ratio is attributed to oxygen added to the weld pool from the surface oxide on the base metal. The added oxygen alters the surface-tension driven fluid flow pattern in the weld pool. Similar results were observed with changes in filler wire surface oxide thickness, caused by changes in wire production conditions. 15 refs., 14 figs., 4 tabs.

  1. Detailed analysis of surface asperity deformation mechanism in diffusion bonding of steel hollow structural components

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Li, H.; Li, M. Q.

    2016-05-01

    This study focused on the detailed analysis of surface asperity deformation mechanism in similar diffusion bonding as well as on the fabrication of high quality martensitic stainless steel hollow structural components. A special surface with regular patterns was processed to be joined so as to observe the extent of surface asperity deformation under different bonding pressures. Results showed that an undamaged hollow structural component has been obtained with full interfacial contact and the same shear strength to that of base material. Fracture surface characteristic combined with surface roughness profiles distinctly revealed the enhanced surface asperity deformation as the applied pressure increases. The influence of surface asperity deformation mechanism on joint formation was analyzed: (a) surface asperity deformation not only directly expanded the interfacial contact areas, but also released deformation heat and caused defects, indirectly accelerating atomic diffusion, then benefits to void shrinkage; (b) surface asperity deformation readily introduced stored energy difference between two opposite sides of interface grain boundary, resulting in strain induced interface grain boundary migration. In addition, the influence of void on interface grain boundary migration was analyzed in detail.

  2. Macrophage responses to 316L stainless steel and cobalt chromium alloys with different surface topographies.

    PubMed

    Anderson, Jordan A; Lamichhane, Sujan; Mani, Gopinath

    2016-11-01

    The surface topography of a biomaterial plays a vital role in determining macrophage interactions and influencing immune response. In this study, we investigated the effect of smooth and microrough topographies of commonly used metallic biomaterials such as 316 L stainless steel (SS) and cobalt-chromium (CoCr) alloys on macrophage interactions. The macrophage adhesion was greater on CoCr compared to SS, irrespective of their topographies. The macrophage activation and the secretion of most pro-inflammatory cytokines (TNF-α, IL-6, and IP-10) were greater on microrough surfaces than on smooth surfaces by day-1. However, by day-2, the macrophage activation on smooth surfaces was also significantly increased up to the same level as observed on the microrough surfaces, with more amount of cytokines secreted. The secretion of anti-inflammatory cytokine (IL-10) was significantly increased from day-1 to day-2 on all the alloy surfaces with the effect most prominently observed on microrough surfaces. The production of nitric oxide by the macrophages did not show any major substrate-dependent effect. The foreign body giant cells formed by macrophages were least observed on the microrough surfaces of CoCr. Thus, this study demonstrated that the nature of material (SS or CoCr) and their surface topographies (smooth or microrough) strongly influence the macrophage responses. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2658-2672, 2016.

  3. Surface preparation effects on GTA weld shape in JBK-75 stainless steel

    SciTech Connect

    Campbell, R.D.; Robertson, A.M. ); Heiple, C.R. ); Sturgill, P.L.; Jamsay, R.

    1993-02-01

    The results of a study are reported here on the effects of surface preparation on the shape of autogenous gas tungsten arc (GTA) welds in JBK-75, an austenitic precipitation hardenable stainless steel similar to A286. Minor changes in surface preparation produced substantial changes in the fusion zone shape and welding behavior of this alloy. Increased and more consistent depth of fusion (higher d/w ratios) along with improved arc stability and less arc wander resulted from wire brushing and other abrasive surface preparations, although chemical and machining methods did not produce any increase in depth of fusion. Abrasive treatments roughen the surface, increase the surface area, increase the surface oxide thickness, and entrap oxide. The increased weld d/w ratio is attributed to oxygen added to the weld pool from the surface oxide on the base metal. The added oxygen alters the surface-tension-driven fluid flow pattern in the weld pool. Increased depth of fusion in wire-fed U-groove weld joints also resulted when welding wire with a greater surface oxide thickness was used. Increasing the amount of wire brushing produced even deeper welds. However, a maximum in depth of fusion was observed with further wire brushing, beyond which weld fusion depth decreased.

  4. Ultrastructural effect of self-ligating bracket materials on stainless steel and superelastic NiTi wire surfaces.

    PubMed

    Choi, Samjin; Lee, Sunghoon; Cheong, Youjin; Park, Ki-Ho; Park, Hun-Kuk; Park, Young-Guk

    2012-08-01

    Frictional interactions between wires and brackets reduce the efficacy in orthodontic treatments. Self-ligating brackets (SLBs) are now more often used due to lower frictional forces when compared with conventional-ligating brackets. In this study, scanning electron microscopy and atomic force microscopy were used to examine the microstructural effects of stainless steel and ceramic SLBs on the surface roughness of stainless steel and superelastic NiTi wires both after in vivo clinical orthodontic treatment as well as in in vitro three-point bending experiments. A combination of two wires-0.019 in. × 0.025 in. stainless steel wires and 0.016 in. superelastic NiTi wires-and two SLBs-both passive-type stainless steel SLBs and active-type ceramic SLBs-was applied for 4 months (bicuspid-extraction) in an in vivo setting and for 1 month in an in vitro setting (200 g loads). After the SLB treatments, all wires exhibited severe scratches secondary to frictional interactions with the brackets. When used with the stainless steel SLBs (Damon 3MX®), the surfaces of 0.019 in. × 0.025 in. stainless steel (P < 0.0001) and 0.016 in. superelastic NiTi wires (P < 0.05) were significantly smoother than when used with the ceramic SLBs (Clippy-C®). Such results suggest that orthodontic treatments with stainless steel SLBs are more effective than with ceramic SLBs.

  5. Carbon segregation and inclusions effects on surface fracture morphology of a 12% chromium stainless steel

    NASA Astrophysics Data System (ADS)

    Souami, N.; Saidi, D.; Negache, M.; Ati, A.

    2003-12-01

    Martensitic 12% chromium stainless steel is generally used for the manufacture of water vapour turbine blades. This material, under these environmental conditions, develops fatigue corrosion with failure as a result of the segregation of certain constituent elements such as phosphorus (P) and sulphur (S),[1 3] or the presence of some types of inclusions.[2 4] To be able to understand and explain these phenomena, in situ characterization of the fractured surfaces were performed for two types of samples: steel 1 as manufactured turbine material whose fracture mode is intergranular and steel 2 issued from last stage turbine blades after 100 000 h service at 40 °C whose fracture mode is transgranular. The techniques used for characterization were scanning electron microscopy (SEM) coupled with the x-ray analysis by energy dispersive spectroscopy (EDS), and auger electron spectroscopy (AES). The Auger results enabled the understanding of the brittle to ductile transition for the material by showing the simultaneous diffusion of carbon from grain boundaries (GB) to grains (G) and chromium from G to GB. Furthermore, the heavy segregation of phosphorus at the GBs could explain the intergranular crack rupture traces observed in steel 2. SEM observations coupled with EDS analysis showed the presence of different types of non-metallic inclusions such as silicon-based complex inclusions and manganese sulfides (MnS). The presence of silicon-based complex inclusions at GB could explain the intergranular fracture mode previously reported. The characterization of the fracture appearance suggests also that MnS inclusions can act as nucleation sites for secondary microcracks at the GB level that were observed after service.

  6. Delaying Frost Formation by Controlling Surface Chemistry of Carbon Nanotube-Coated Steel Surfaces.

    PubMed

    Zhang, Yu; Klittich, Mena R; Gao, Min; Dhinojwala, Ali

    2017-02-22

    Superhydrophobic surfaces are appealing as anti-icing surfaces, given their excellent water repellent performance. However, when water condenses on the surface due to high humidity, the water becomes pinned, and superhydrophobic surfaces fail to perform. Here we studied how the stability of the superhydrophobicity affected water condensation and frost formation. We created rough surfaces with the same surface structure, but with a variety of surface chemistries, and compared their antifrost properties as a function of intrinsic contact angle. Frost initiation was significantly delayed on surfaces with higher intrinsic contact angles. We coupled these macromeasurements with environmental scanning electron microscopy of water droplet initiation under high humidity conditions. These provide experimental evidence toward previous hypotheses that for a lower intrinsic-angle rough surface, Wenzel state is thermodynamically favorable, whereas the higher intrinsic-angle surface maintains a Cassie-Baxter state. Surfaces with a thermodynamically stable Cassie-Baxter state can then act both as antisteam and antifrost surfaces. This research could answer the persistent question of why superhydrophobic surfaces sometimes are not icephobic; anti-icing performance depends on the surface chemistry, which plays a critical role in the stability of the superhydrophobic surfaces.

  7. Temperature effects on the static and dynamic fracture behaviors of low-silicon CA-15 tempered stainless steel castings

    NASA Astrophysics Data System (ADS)

    Hsu, Cheng-Hsun; Teng, Hwei-Yuan

    2005-04-01

    In this research we studied the effect of testing temperature on both static and dynamic fracturing behaviors of low-silicon CA-15 martensitic stainless steel (MSS) castings after austenitizing and tempering treatments. The results showed that the material's microstructure was influenced by heat treatment and various testing temperatures would cause different fracturing mechanisms. In static tensile tests, the 573-673 K tempered specimens occurred secondary strengthening at 423 K and 298 K testing temperatures. However, there is a contrast of weakening occurred at 123 K for the same type of tempered samples. The phenomenon was mainly triggered by local cracking at the ferrite/martensitic interface and incoherent precipitate site in the materials because of the existence of shrinkage stress under subzero temperature. In the dynamic strain-rate tests, impact embrittlement occurred in the 573-673 K tempered samples as a result of the tempered martensite embrittlement (TME) phenomenon. The ductile-to-brittle transition temperature (DBTT) of the tempered material was obviously lower than that of the as-cast material. Also, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to correlate the properties attained to the microstructural observation.

  8. Oxidation mechanism of T91 steel in liquid lead-bismuth eutectic: with consideration of internal oxidation

    PubMed Central

    Ye, Zhongfei; Wang, Pei; Dong, Hong; Li, Dianzhong; Zhang, Yutuo; Li, Yiyi

    2016-01-01

    Clarification of the microscopic events that occur during oxidation is of great importance for understanding and consequently controlling the oxidation process. In this study the oxidation product formed on T91 ferritic/martensitic steel in oxygen saturated liquid lead-bismuth eutectic (LBE) at 823 K was characterized at the nanoscale using focused-ion beam and transmission electron microscope. An internal oxidation zone (IOZ) under the duplex oxide scale has been confirmed and characterized systematically. Through the microscopic characterization of the IOZ and the inner oxide layer, the micron-scale and nano-scale diffusion of Cr during the oxidation in LBE has been determined for the first time. The micron-scale diffusion of Cr ensures the continuous advancement of IOZ and inner oxide layer, and nano-scale diffusion of Cr gives rise to the typical appearance of the IOZ. Finally, a refined oxidation mechanism including the internal oxidation and the transformation of IOZ to inner oxide layer is proposed based on the discussion. The proposed oxidation mechanism succeeds in bridging the gap between the existing models and experimental observations. PMID:27734928

  9. Suppression effect of nano-sized oxide particles on helium irradiation hardening in F82H-ODS steel

    NASA Astrophysics Data System (ADS)

    Chen, S.; Wang, Y.; Tadaki, K.; Hashimoto, N.; Ohnuki, S.

    2014-12-01

    Helium implantation was performed to investigate irradiation hardening in ferritic/martensitic steels. Depth dependence of nano-hardness was obtained using a Berkovich nano-indenter, and then nano-hardness was extracted from Nix-Gao model. The correlation between irradiation hardening and the concentration 500-2000 appm of helium was plotted. Nano-hardness increases as a function of helium concentration. F82H-ODS with a higher nano-hardness provides a lower irradiation hardening than F82H-IEA. Cross-sectional transmission electron microscopy (XTEM) revealed that cavities with a uniform distribution were formed after helium implantation at 2000 appm helium concentration, showing a mean size of 1.1 nm with an average number density of 4.9 × 1023 m-3 in F82H-IEA and 1.3 nm with 7.4 × 1023 m-3 in F82H-ODS. Orowan model was applied to evaluate the hardening from dispersed cavities. The significant difference of hardening between calculation and nano-indentation result of F82H-ODS indicates that oxide particles may shield the hardening effect from cavities because of the complex multi-interaction.

  10. Oxidation mechanism of T91 steel in liquid lead-bismuth eutectic: with consideration of internal oxidation

    NASA Astrophysics Data System (ADS)

    Ye, Zhongfei; Wang, Pei; Dong, Hong; Li, Dianzhong; Zhang, Yutuo; Li, Yiyi

    2016-10-01

    Clarification of the microscopic events that occur during oxidation is of great importance for understanding and consequently controlling the oxidation process. In this study the oxidation product formed on T91 ferritic/martensitic steel in oxygen saturated liquid lead-bismuth eutectic (LBE) at 823 K was characterized at the nanoscale using focused-ion beam and transmission electron microscope. An internal oxidation zone (IOZ) under the duplex oxide scale has been confirmed and characterized systematically. Through the microscopic characterization of the IOZ and the inner oxide layer, the micron-scale and nano-scale diffusion of Cr during the oxidation in LBE has been determined for the first time. The micron-scale diffusion of Cr ensures the continuous advancement of IOZ and inner oxide layer, and nano-scale diffusion of Cr gives rise to the typical appearance of the IOZ. Finally, a refined oxidation mechanism including the internal oxidation and the transformation of IOZ to inner oxide layer is proposed based on the discussion. The proposed oxidation mechanism succeeds in bridging the gap between the existing models and experimental observations.

  11. The effect of stress and magnetic field orientation on surface Barkhausen noise in pipeline steel

    SciTech Connect

    Jagadish, C.; Clapham, L.; Atherton, D.L. . Dept. of Physics)

    1990-01-01

    Surface Barkhausen noise (SBN) measurements were mae on a 2-percent Mn pipeline steel sample subjected to different levels of applied tensile and compressive isostress. The magnetic field direction was varied through a full 360{degrees}. SBN voltage was found to depend on both stress level and magnetic field direction. The results were analyzed in terms of the reorientation of magnetic moments from axial to circumferential directions with increasing tension. Compression was found to re-align the magnetic moments in the axial direction.

  12. Innovative Approaches To Improving The Bond Between Concrete and Steel Surfaces

    DTIC Science & Technology

    2006-11-01

    silicates developed in Portland cement (di- and tri-calcium silicates, calcium aluminates ) and firing the mixture onto the surface of the...developed for undercoating over mild steel. Critical components, especially cobalt and nickel, in the frit assure that the iron oxide on the...0.07 nil Manganese dioxide MnO2 1.39 1 - 2 Ni oxide NiO 1.04 1 - 2 Cobalt Oxide Co3O4 0.93 .5 – 1.5 Phosphorus

  13. Two dimensional finite element thermal model of laser surface glazing for H13 tool steel

    NASA Astrophysics Data System (ADS)

    Kabir, I. R.; Yin, D.; Naher, S.

    2016-10-01

    A two dimensional (2D) transient thermal model with line-heat-source was developed by Finite Element Method (FEM) for laser surface glazing of H13 tool steel using commercial software-ANSYS 15. The geometry of the model was taken as a transverse circular cross-section of cylindrical specimen. Two different power levels (300W, 200W) were used with 0.2mm width of laser beam and 0.15ms exposure time. Temperature distribution, heating and cooling rates, and the dimensions of modified surface were analysed. The maximum temperatures achieved were 2532K (2259°C) and 1592K (1319°C) for laser power 300W and 200W respectively. The maximum cooling rates were 4.2×107 K/s for 300W and 2×107 K/s for 200W. Depths of modified zone increased with increasing laser power. From this analysis, it can be predicted that for 0.2mm beam width and 0.15ms time exposer melting temperature of H13 tool steel is achieved within 200-300W power range of laser beam in laser surface glazing.

  14. Wear Resistance of Steels with Surface Nanocrystalline Structure Generated by Mechanical-Pulse Treatment

    NASA Astrophysics Data System (ADS)

    Nykyforchyn, Hryhoriy; Kyryliv, Volodymyr; Maksymiv, Olha

    2017-02-01

    The influence of the surface mechanical-pulse treatment based on high-speed friction with a rapid cooling by the technological environment on the wear resistance of medium- and high-carbon steels was considered. The treatment due to a severe plastic deformation enabled obtaining the nanocrystalline structure with a grain size of 14-40 nm. A high positive effect of this treatment was obtained not only because of metal nanocrystallization but also thanks to other factors, namely, structural-phase transformations, carbon saturation of the surface due to decomposition of the coolant and the friction coefficient decrease. Higher carbon content leads to better strengthening of the surface, and its microhardness can reach 12 GPa.

  15. Noncontact monitoring of surface-wave nonlinearity for predicting the remaining life of fatigued steels

    NASA Astrophysics Data System (ADS)

    Ogi, Hirotsugu; Hirao, Masahiko; Aoki, Shinji

    2001-07-01

    A nonlinear acoustic measurement is studied for fatigue damage monitoring. An electromagnetic acoustic transducer (EMAT) magnetostrictively couples to a surface-shear-wave resonance along the circumference of a rod specimen during rotating bending fatigue of carbon steels. Excitation of the EMAT at half of the resonance frequency caused the standing wave to contain only the second-harmonic component, which was received by the same EMAT to determine the second-harmonic amplitude. Thus measured surface-wave nonlinearity always showed two distinct peaks at 60% and 85% of the total life. We attribute the earlier peak to crack nucleation and growth, and the later peak to an increase of free dislocations associated with crack extension in the final stage. This noncontact resonance-EMAT measurement can monitor the evolution of the surface-shear-wave nonlinearity throughout the metal's fatigue life and detect the pertinent precursors of the eventual failure.

  16. Temperature thresholds for surface blistering of platinum and stainless steel exposed to curium-242 alpha radiations

    SciTech Connect

    McDonell, W R; Dillich, S

    1981-01-01

    Implantation of helium in materials exposed to alpha-emitting radionuclides such as /sup 242/Cm causes surface blistering at elevated temperatures. The temperature thresholds for such blistering are of practical importance to the selection of suitable container materials for radionuclides, and are of fundamental interest with regard to the mechanisms of helium blistering of materials in radiation environments. The purpose of this investigation was to establish temperature thresholds for surface blistering of platinum and stainless-steel container materials by post-irradiation heating of specimens exposed at room temperature to alpha particles from an external /sup 242/Cm source. These thresholds were compared with (1) the analogous temperature thresholds for surface blistering of materials exposed to external beams of accelerator helium ions, and (2) thresholds for swelling and grain-boundary cracking of materials in which helium is generated internally by (n,..cap alpha..) reactions during reactor exposures.

  17. Very high cycle fatigue behavior of SAE52100 bearing steel by ultrasonic nanocrystalline surface modification.

    PubMed

    Cho, In Shik; He, Yinsheng; Li, Kejian; Oh, Joo Yeon; Shin, Keesam; Lee, Chang Soon; Park, In Gyu

    2014-11-01

    In this paper, the SAE52100 bearing steel contained large quantities of cementite dispersed in ferrite matrix was subjected to the ultrasonic nanocrystalline surface modification (UNSM) treatment that aims for the extension of fatigue life. The microstructure and fatigue life of the untreated and treated specimens were studied by using electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM), and a developed ultra-high cycle fatigue test (UFT). After UNSM treatment, the coarse ferrite grains (- 10 μm) were refined to nanosize (- 200 nm), therefore, nanostructured surface layers were fabricated. Meanwhile, in the deformed layer, the number density and area fraction of cementite were increased up to - 400% and - 550%, respectively, which increased with the decrease in depth from the topmost treated surface. The improvement of hardness (from 200 Hv to 280 Hv) and high cycles fatigue strength by - 10% were considered the contribution of the developed nanostructure in the UNSM treated specimen.

  18. Surface composition effect of nitriding Ni-free stainless steel as bipolar plate of polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Shironita, Sayoko; Nakatsuyama, Kunio; Souma, Kenichi; Umeda, Minoru

    2016-12-01

    In order to increase the corrosion resistance of low cost Ni-free SUS445 stainless steel as the bipolar plate of a polymer electrolyte fuel cell, a nitriding surface treatment experiment was carried out in a nitrogen atmosphere under vacuum conditions, while an Ar atmosphere was used for comparison. The electrochemical performance, microstructure, surface chemical composition and morphology of the sample before and after the electrochemical measurements were investigated using linear sweep voltammetry (LSV), X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDS) and laser scanning microscopy (LSM) measurements. The results confirmed that the nitriding heat treatment not only increased the corrosion resistance, but also improved the surface conductivity of the Ni-free SUS445 stainless steel. In contrast, the corrosion resistance of the SUS445 stainless steel decreased after heat treatment in an Ar atmosphere. These results could be explained by the different surface compositions between these samples.

  19. Survival of Salmonella Enteritidis on four types of stainless steel surface under a dry condition and recovery by swabbing.

    PubMed

    Miwa, Norinaga; Konuma, Hirotaka; Kumagai, Susumu

    2013-01-01

    The survival and recovery of Salmonella Enteritidis inoculated on stainless steel surfaces with different metal contents and surface finishes were examined. Two S. Enteritidis strains possessing different levels of biofilm productivity were inoculated with tryptone soya broth (TSB) and egg yolk emulsion (EY) on the surface of stainless steel squares (1 cm × 1 cm) and stored at 22℃ under a dry condition. After storage, cells were recovered from the stainless steel surfaces by swabbing with a cotton swab. The numbers of cells recovered by swabbing and the cells remaining on the stainless steel squares were counted. The survival ratio of the strain possessing high biofilm productivity was greater than that of the strain possessing low biofilm productivity. The survival ratio of S. Enteritidis suspended in TSB was often higher than that in EY. There were no significant differences in the survival and recovery ratios of S. Enteritidis based on stainless steel composition or surface finish. From all except one sample, more than 98% of viable cells of S. Enteritidis were recovered by swabbing with a cotton swab.

  20. Plasma-enhanced synthesis of bactericidal quaternary ammonium thin layers on stainless steel and cellulose surfaces.

    PubMed

    Jampala, Soujanya N; Sarmadi, M; Somers, E B; Wong, A C L; Denes, F S

    2008-08-19

    We have investigated bottom-up chemical synthesis of quaternary ammonium (QA) groups exhibiting antibacterial properties on stainless steel (SS) and filter paper surfaces via nonequilibrium, low-pressure plasma-enhanced functionalization. Ethylenediamine (ED) plasma under suitable conditions generated films rich in secondary and tertiary amines. These functional structures were covalently attached to the SS surface by treating SS with O 2 and hexamethyldisiloxane plasma prior to ED plasma treatment. QA structures were formed by reaction of the plasma-deposited amines with hexyl bromide and subsequently with methyl iodide. Structural compositions were examined by electron spectroscopy for chemical analysis and Fourier transform infrared spectroscopy, and surface topography was investigated with atomic force microscopy and water contact angle measurements. Modified SS surfaces exhibited greater than a 99.9% decrease in Staphylococcus aureus counts and 98% in the case of Klebsiella pneumoniae. The porous filter paper surfaces with immobilized QA groups inactivated 98.7% and 96.8% of S. aureus and K. pneumoniae, respectively. This technique will open up a novel way for the synthesis of stable and very efficient bactericidal surfaces with potential applications in development of advanced medical devices and implants with antimicrobial surfaces.

  1. Dwell Time and Surface Parameter Effects on Removal of Silicone Oil From D6ac Steel Using TCA

    NASA Technical Reports Server (NTRS)

    Boothe, R. E.

    2003-01-01

    This study was conducted to evaluate the impact of dwell time, surface roughness, and the surface activation state on 1,1,1-trichloroethane's (TCA's) effectiveness for removing silicone oil from D6ac steel. Silicone-contaminated test articles were washed with TCA solvent, and then the surfaces were analyzed for residue, using Fourier transform infrared spectroscopy. The predominant factor affecting the ability to remove the silicone oil was surface roughness.

  2. Corrosion behavior of surface treated steel in liquid sodium negative electrode of liquid metal battery

    NASA Astrophysics Data System (ADS)

    Lee, Jeonghyeon; Shin, Sang Hun; Lee, Jung Ki; Choi, Sungyeol; Kim, Ji Hyun

    2016-03-01

    While liquid metal batteries are attractive options for grid-scale energy storage applications as they have flexible siting capacities and small footprints, the compatibility between structural materials such as current collectors and negative electrode such as sodium is one of major issues for liquid metal batteries. Non-metallic elements such as carbon, oxygen, and nitrogen in the liquid sodium influence the material behaviors of the cell construction materials in the battery system. In this study, the compatibility of structural materials with sodium is investigated in high temperature liquid sodium, and electrochemical impedance spectroscopy (EIS) is used to monitor in-situ the corrosion behavior at the surface of materials in sodium. Chemical vapor deposition (CVD) coatings of SiC and Si3N4 are applied as protective barriers against dissolution and corrosion on the steel surface. The results show that CVD coating of Si compounds can delay corrosion of steel in high temperature liquid sodium comparing to the result of as-received specimens, while SiC coating is more durable than Si3N4 coating in high temperature liquid sodium.

  3. New idea of suppressing free surface vortex during tapping liquid steel from converter

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Jin; Kim, Sang-Joon; Lee, Hae-Geon

    2016-01-01

    During tapping liquid steel from a converter to a ladle, slag may carry over due to a formation of free surface vortex. Such vortex should be suppressed in order to minimize contamination of the steel by slag. In the present study, a new idea is proposed to minimize the vortex formation by applying dual tapping hole system. The idea was tested using a rectangular shape water vessel with dual tapping holes, supplemented by a numerical simulations, in order to evaluate feasibility of the dual tapping hole system. Both the water model experiment and the numerical simulation showed similar tendencies that the dual tapping hole system is promising to prevent the vortex formation. Experimental results showed that the free surface vortex formation is highly sensitive to shape and configuration of the nozzle. From the numerical simulation, flow characteristics were obtained, and vortex canceling between two nozzles is confirmed. Effect of dual tapping hole increased with increasing distance between two holes in the present experimental condition. Finally, a 1/7.8 scale-down water vessel simulating a real converter was employed in order to confirm the validity of the above findings. The result showed almost the same tendencies with the previous findings.

  4. Nano- and Macro-wear of Bio-carbo-nitrided AISI 8620 Steel Surfaces

    NASA Astrophysics Data System (ADS)

    Arthur, Emmanuel Kwesi; Ampaw, Edward; Zebaze Kana, M. G.; Adetunji, A. R.; Olusunle, S. O. O.; Adewoye, O. O.; Soboyejo, W. O.

    2015-12-01

    This paper presents the results of an experimental study of nano- and macro-scale wear in a carbo-nitrided AISI 8620 steel. Carbo-nitriding is carried out using a novel method that involves the use of dried, cyanide-containing cassava leaves, as sources of carbon and nitrogen. These are used in a pack cementation that is used to diffuse carbon and nitrogen into case layers at intermediate temperatures [673.15 K, 723.15 K, 773.15 K, and 823.15 K (400 °C, 450 °C, 500 °C, and 550 °C)]. Nano- and macro-scale wear properties are studied in the case-hardened surfaces, using a combination of nano-scratch and pin-on-disk experiments. The measured wear volumes (at both nano- and macro-length scales) are shown to increase with decreasing pack cyaniding temperature. The nano- and macro-wear resistances are also shown to be enhanced by the in situ diffusion of carbon and nitrogen from cyanide-containing bio-processed waste. The underlying wear mechanisms are also elucidated via atomic force microscopy and scanning electron microscopy observations of the wear tracks. The implications of the results are discussed for the design of hardened carbo-nitrided steel surfaces with improved wear resistance.

  5. Precipitation Hardening of Laser-Surfaced Layer of Maraging Alloy at the Surface of Steel 3Kh3M3F

    NASA Astrophysics Data System (ADS)

    Stavrev, D. S.; Shcherbakov, V. S.

    2016-09-01

    The structure and fracture behavior of a layer of maraging alloy deposited by laser surfacing on steel 3Kh3M3F is studied in the initial condition and after precipitation hardening at 550 and 600°C. Microhardness is measured in layer cross sections, and fractures after surfacing and aging are analyzed in an electron microscope.

  6. In vitro bioactivity of micro metal injection moulded stainless steel with defined surface features.

    PubMed

    Bitar, Malak; Friederici, Vera; Imgrund, Philipp; Brose, Claudia; Bruinink, Arie

    2012-05-04

    Micrometre- and nanometre-scale surface structuring with ordered topography features may dramatically enhance orthopaedic implant integration. In this study we utilised a previously optimised micron metal injection moulding (µ-MIM) process to produce medical grade stainless steel surfaces bearing micrometre scale, protruding, hemispheres of controlled dimensions and spatial distribution. Additionally, the structured surfaces were characterised by the presence of submicrometre surface roughness resulting from metal grain boundary formation. Following cytocompatibility (cytotoxicity) evaluation using 3T3 mouse fibroblast cell line, the effect on primary human cell functionality was assessed focusing on cell attachment, shape and cytoskeleton conformation. In this respect, and by day 7 in culture, significant increase in focal adhesion size was associated with the microstructured surfaces compared to the planar control. The morphological conformation of the seeded cells, as revealed by fluorescence cytoskeleton labelling, also appeared to be guided in the vertical dimension between the hemisphere bodies. Quantitative evaluation of this guidance took place using live cytoplasm fluorescence labelling and image morphometry analysis utilising both, compactness and elongation shape descriptors. Significant increase in cell compactness was associated with the hemisphere arrays indicating collective increase in focused cell attachment to the hemisphere bodies across the entire cell population. Micrometre-scale hemisphere array patterns have therefore influenced cell attachment and conformation. Such influence may potentially aid in enhancing key cellular events such as, for example, neo-osteogenesis on implanted orthopaedic surfaces.

  7. Formation of the Goss orientation near the surface of 3 pct silicon steel during hot rolling

    NASA Astrophysics Data System (ADS)

    Shimizu, Y.; Ito, Y.; Iida, Y.

    1986-08-01

    The influence of hot rolling conditions such as reduction rate, rolling temperature, rolling speed, lubrication, and initial orientation on the formation of the Goss orientation near the surface of hot rolled 3 Pct silicon steel was studied. A (110) [001] orientation was stably formed at the reduction rate of over 85 Pct in any initial orientation used, even from (100) [001] and (100) [011] single crystals. A strong (110) [001] orientation was obtained in the specimen hot rolled by multi-pass rolling (low reduction rate per pass) and by slower speed rolling in the range of 6 to 50 m/min. It was found that the Goss orientation was formed not by recrystallization during and after hot rolling but by slip rotation near the surface due to constrained deformation. The high friction between the roll and sheet characteristic to hot rolling was important for this texture formation.

  8. Absorptivity modulation on wavy molten steel surfaces: The influence of laser wavelength and angle of incidence

    SciTech Connect

    Kaplan, A. F. H.

    2012-10-08

    The modulation of the angle-dependent Fresnel absorptivity across wavy molten steel surfaces during laser materials processing, like drilling, cutting, or welding, has been calculated. The absorptivity is strongly altered by the grazing angle of incidence of the laser beam on the processing front. Owing to its specific Brewster-peak characteristics, the 10.64 {mu}m wavelength CO{sub 2}-laser shows an opposite trend with respect to roughness and angle-of-incidence compared to lasers in the wavelength range of 532-1070 nm. Plateaus or rings of Brewster-peak absorptivity can lead to hot spots on a wavy surface, often in close proximity to cold spots caused by shadow domains.

  9. Simulation of surface profile formation in oxygen laser cutting of mild steel due to combustion cycles

    NASA Astrophysics Data System (ADS)

    Ermolaev, G. V.; Kovalev, O. B.

    2009-09-01

    A physicomathematical model of cyclic iron combustion in an oxygen flow during oxygen laser cutting of metal sheets is developed. The combustion front is set into motion by focused laser radiation and a heterogeneous oxidation reaction in oxygen. The burning rate is limited by oxygen supply from the gas phase towards the metal surface, and the interface motion depends on the local temperature. A 3D numerical simulation predicts wavy structures on the metal surface; their linear sizes depend on the scanning speed of the laser beam, the thickness of the produced liquid oxide film and the parameters of the oxygen jet flow. Simulation results help in understanding the mechanism of striation formation during oxygen gas-laser cutting of mild steel and are in qualitative agreement with experimental findings.

  10. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    SciTech Connect

    Pawel, Steven J; Hsu, Julia

    2010-11-01

    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  11. Analysis of thermomechanical states in single-pass GMAW surfaced steel element

    NASA Astrophysics Data System (ADS)

    Winczek, Jerzy; Gawronska, Elzbieta; Murcinkova, Zuzana; Hatala, Michal; Pavlenko, Slavko; Makles, Krzysztof

    2017-03-01

    In the paper the model of temperature field, phase changes and stress states calculation during single-pass arc weld surfacing have been presented. In temperature field solution the temperature changes caused by the heat of weld and by electric arc have been taken into consideration. Kinetics of phase changes during heating is limited by temperature values at the beginning and at the end of austenitic transformation, while progress of phase transformations during cooling has been determined on the basis of time-temperature-transformation (TTT) - welding diagram. The analysis of stress state has been presented for S235 steel flat assuming planar section hypothesis and using integral equations of stress equilibrium. It has enabled a clear interpretation of influence of temperature field and phase transformation on stresses caused by surfacing using Gas Metal Arc Welding (GMAW) method.

  12. Surface temperature distribution of GTA weld pools on thin-plate 304 stainless steel

    SciTech Connect

    Zacharia, T.; David, S.A.; Vitek, J.M.; Kraus, H.G.

    1995-11-01

    A transient multidimensional computational model was utilized to study gas tungsten arc (GTA) welding of thin-plate 304 stainless steel (SS). The model eliminates several of the earlier restrictive assumptions including temperature-independent thermal-physical properties. Consequently, all important thermal-physical properties were considered as temperature dependent throughout the range of temperatures experienced by the weld metal. The computational model was used to predict surface temperature distribution of the GTA weld pools in 1.5-mm-thick AISI 304 SS. The welding parameters were chosen so as to correspond with an earlier experimental study that produced high-resolution surface temperature maps. One of the motivations of the present study was to verify the predictive capability of the computational model. Comparison of the numerical predictions and experimental observations indicate excellent agreement, thereby verifying the model.

  13. Verification of the effect of surface preparation on Hot Isostatic Pressing diffusion bonding joints of CLAM steel

    NASA Astrophysics Data System (ADS)

    Zhao, Yanyun; Li, Chunjing; Huang, Bo; Liu, Shaojun; Huang, Qunying

    2014-12-01

    Hot Isostatic Pressing (HIP) diffusion bonding with CLAM steel is the primary candidate fabrication technique for the first wall (FW) of DFLL-TBM. Surface state is one of the key factors for the joints quality. The effect of surface state prepared with grinder and miller on HIP diffusion bonding joints of CLAM steel was investigated. HIP diffusion bonding was performed at 140 MPa and 1373 K within 3 h. The mechanical properties of the joints were investigated with instrumented Charpy V-notch impact tests and the microstructures of the joints were analyzed with scanning electron microscopy (SEM). The results showed that the milled samples with fine surface roughness were more suitable for CLAM steel HIP diffusion bonding.

  14. Resistance of pathogenic bacteria on the surface of stainless steel depending on attachment form and efficacy of chemical sanitizers.

    PubMed

    Bae, Young-Min; Baek, Seung-Youb; Lee, Sun-Young

    2012-02-15

    Various bacteria including food spoilage bacteria and pathogens can form biofilms on different food processing surfaces, leading to potential food contamination or spoilage. Therefore, the survival of foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium, Staphylococcus aureus, Cronobacter sakazakii) in different forms (adhered cells, biofilm producing in TSB, biofilm producing at RH 100%) on the surface of stainless steel and stored at various relative humidities (RH 23%, 43%, 68%, 85%, and 100%) at room temperature for 5 days was investigated in this study. Additionally, the efficacy of chemical sanitizers (chlorine-based and alcohol-based commercial sanitizers) on inhibiting various types of biofilms of E. coli O157:H7 and S. aureus on the surface of stainless steel was investigated. The number of pathogens on the surface of stainless steel in TSB stored at 25°C for 7 days or RH 100% at 25°C for 7 days was significantly increased and resulted in the increase of 3 log(10) CFU/coupon after 1 day, and these levels were maintained for 7 days. When stainless steel coupons were stored at 25°C for 5 days, the number of pathogens on the surface of stainless steel was significantly reduced after storage at RH 23%, 43%, 68%, and 85%, but not at 100%. When the bacteria formed biofilms on the surface of stainless steel in TSB after 6 days, the results were similar to those of the attached form. However, levels of S. aureus and C. sakazakii biofilms were more slowly reduced after storage at RH 23%, 43%, 68%, and 85% for 5 days than were those of the other pathogens. Formation of biofilms stored at RH 100% for 5 days displayed the highest levels of resistance to inactivation. Treatment with the alcohol sanitizer was very effective at inactivating attached pathogens or biofilms on the surface of stainless steel. Reduction levels of alcohol sanitizer treatment ranged from 1.91 to 4.77 log and from 4.35 to 5.35 log CFU/coupon in E. coli

  15. Surface modifications of steels to improve corrosion resistance in sulfidizing-oxidizing environments

    NASA Astrophysics Data System (ADS)

    Behrani, Vikas

    Industrial and power generation processes employ units like boilers and gasifiers to burn sulfur containing fuels to produce steam and syn gas (H 2 and CO), which can generate electricity using turbines and fuel cells. These units often operate under environments containing gases such as H 2S, SO2, O2 etc, which can attack the metallic structure and impose serious problems of corrosion. Corrosion control in high temperature sulfur bearing environments is a challenging problem requiring information on local gaseous species at the surface of alloy and mechanisms of degradation in these environments. Coatings have proved to be a better alternative for improving corrosion resistance without compromising the bulk mechanical properties. Changes in process conditions may result in thermal and/or environment cycling between oxidizing and sulfidizing environments at the alloy surface, which can damage the protective scale formed on the alloy surface, leading to increase in corrosion rates. Objective of this study was to understand the effect of fluctuating environments on corrosion kinetics of carbon steels and develop diffusion based coatings to mitigate the high temperatures corrosion under these conditions. More specifically, the focus was: (1) to characterize the local gaseous environments at the surface of alloys in boilers; (2) optimizing diffusion coatings parameters for carbon steel; (3) understand the underlying failure mechanisms in cyclic environments; (4) to improve aluminide coating behavior by co-deposition of reactive elements such as Yttrium and Hafnium; (5) to formulate a plausible mechanism of coating growth and effects of alloying elements on corrosion; and (6) to understand the spallation behavior of scale by measuring stresses in the scales. The understanding of coating mechanism and effects of fluctuating gaseous environments provides information for designing materials with more reliable performance. The study also investigates the mechanism behind

  16. Changing the surface properties on naval steel as result of non-thermal plasma treatment

    NASA Astrophysics Data System (ADS)

    Hnatiuc, B.; Sabău, A.; Dumitrache, C. L.; Hnatiuc, M.; Crețu, M.; Astanei, D.

    2016-08-01

    The problem of corrosion, related to Biofouling formation, is an issue with very high importance in the maritime domain. According to new rules, the paints and all the technologies for the conditioning of naval materials must fulfil more restrictive environmental conditions. In order to solve this issue, different new clean technologies have been proposed. Among them, the use of non-thermal plasmas produced at atmospheric pressure plays a very important role. This study concerns the opportunity of plasma treatment for preparation or conditioning of naval steel OL36 type. The plasma reactors chosen for the experiments can operate at atmospheric pressure and are easy to use in industrial conditions. They are based on electrical discharges GlidArc and Spark, which already proved their efficiency for the surface activation or even for coatings of the surface. The non-thermal character of the plasma is ensured by a gas flow blown through the electrical discharges. One power supply has been used for reactors that provide a 5 kV voltage and a maximum current of 100 mA. The modifications of the surface properties and composition have been studied by XPS technique (X-ray Photoelectron Spectroscopy). There were taken into consideration 5 samples: 4 of them undergoing a Mini-torch plasma, a Gliding Spark, a GlidArc with dry air and a GlidArc with CO2, respectively the fifth sample which is the untreated witness. Before the plasma treatment, samples of naval steel were processed in order to obtain mechanical gloss. The time of treatment was chosen to 12 minutes. In the spectroscopic analysis, done on a ULVAC-PHI, Inc. PHI 5000 Versa Probe scanning XPS microprobe, a monocromated Al Kα X-ray source with a spot size of 100 μm2 was used to scan each sample while the photoelectrons were collected at a 45-degree take-off angle. Differences were found between atomic concentrations in each individual case, which proves that the active species produced by each type of plasma affects

  17. Surface working of 304L stainless steel: Impact on microstructure, electrochemical behavior and SCC resistance

    SciTech Connect

    Acharyya, S.G.; Khandelwal, A.; Kain, V.; Kumar, A.; Samajdar, I.

    2012-10-15

    The effect of surface working operations on the microstructure, electrochemical behavior and stress corrosion cracking resistance of 304L stainless steel (SS) was investigated in this study. The material was subjected to (a) solution annealing (b) machining and (c) grinding operations. Microstructural characterization was done using stereo microscopy and electron back scattered diffraction (EBSD) technique. The electrochemical nature of the surfaces in machined, ground and solution annealed condition were studied using potentiodynamic polarization and scanning electrochemical microscopy (SECM) in borate buffer solution. The stress corrosion cracking resistance of 304L SS in different conditions was studied by exposing the samples to boiling MgCl{sub 2} environment. Results revealed that the heavy plastic deformation and residual stresses present near the surface due to machining and grinding operations make 304L SS electrochemically more active and susceptible to stress corrosion cracking. Ground sample showed highest magnitude of current density in the passive potential range followed by machined and solution annealed 304L SS. Micro-electrochemical studies established that surface working promotes localized corrosion along the surface asperities which could lead to crack initiation. - Highlights: Black-Right-Pointing-Pointer Machining/grinding produce extensive grain fragmentation near the surface of 304L SS. Black-Right-Pointing-Pointer Machining/grinding result in martensitic transformation near the surface of 304L SS. Black-Right-Pointing-Pointer Machining/grinding drastically reduce the SCC resistance of 304L SS in chloride. Black-Right-Pointing-Pointer Machining/grinding make the surface of 304L SS electrochemically much more active. Black-Right-Pointing-Pointer SECM study reveal that preferential dissolution takes place along surface asperities.

  18. Homogenous photocatalytic decontamination of prion infected stainless steel and titanium surfaces.

    PubMed

    Berberidou, Chrysanthi; Xanthopoulos, Konstantinos; Paspaltsis, Ioannis; Lourbopoulos, Athanasios; Polyzoidou, Eleni; Sklaviadis, Theodoros; Poulios, Ioannis

    2013-01-01

    Prions are notorious for their extraordinary resistance to traditional methods of decontamination, rendering their transmission a public health risk. Iatrogenic Creutzfeldt-Jakob disease (iCJD) via contaminated surgical instruments and medical devices has been verified both experimentally and clinically. Standard methods for prion inactivation by sodium hydroxide or sodium hypochlorite have failed, in some cases, to fully remove prion infectivity, while they are often impractical for routine applications. Prion accumulation in peripheral tissues and indications of human-to-human bloodborne prion transmission, highlight the need for novel, efficient, yet user-friendly methods of prion inactivation. Here we show both in vitro and in vivo that homogenous photocatalytic oxidation, mediated by the photo-Fenton reagent, has the potential to inactivate the pathological prion isoform adsorbed on metal substrates. Photocatalytic oxidation with 224 μg mL(-1) Fe (3+), 500 μg mL(-1) h(-1) H 2O 2, UV-A for 480 min lead to 100% survival in golden Syrian hamsters after intracranial implantation of stainless steel wires infected with the 263K prion strain. Interestingly, photocatalytic treatment of 263K infected titanium wires, under the same experimental conditions, prolonged the survival interval significantly, but failed to eliminate infectivity, a result that we correlate with the increased adsorption of PrP(Sc) on titanium, in comparison to stainless steel. Our findings strongly indicate that our, user--and environmentally--friendly protocol can be safely applied to the decontamination of prion infected stainless steel surfaces.

  19. Homogenous photocatalytic decontamination of prion infected stainless steel and titanium surfaces

    PubMed Central

    Berberidou, Chrysanthi; Xanthopoulos, Konstantinos; Paspaltsis, Ioannis; Lourbopoulos, Athanasios; Polyzoidou, Eleni; Sklaviadis, Theodoros; Poulios, Ioannis

    2013-01-01

    Prions are notorious for their extraordinary resistance to traditional methods of decontamination, rendering their transmission a public health risk. Iatrogenic Creutzfeldt–Jakob disease (iCJD) via contaminated surgical instruments and medical devices has been verified both experimentally and clinically. Standard methods for prion inactivation by sodium hydroxide or sodium hypochlorite have failed, in some cases, to fully remove prion infectivity, while they are often impractical for routine applications. Prion accumulation in peripheral tissues and indications of human-to-human bloodborne prion transmission, highlight the need for novel, efficient, yet user-friendly methods of prion inactivation. Here we show both in vitro and in vivo that homogenous photocatalytic oxidation, mediated by the photo-Fenton reagent, has the potential to inactivate the pathological prion isoform adsorbed on metal substrates. Photocatalytic oxidation with 224 μg mL−1 Fe3+, 500 μg mL−1 h−1 H2O2, UV-A for 480 min lead to 100% survival in golden Syrian hamsters after intracranial implantation of stainless steel wires infected with the 263K prion strain. Interestingly, photocatalytic treatment of 263K infected titanium wires, under the same experimental conditions, prolonged the survival interval significantly, but failed to eliminate infectivity, a result that we correlate with the increased adsorption of PrPSc on titanium, in comparison to stainless steel. Our findings strongly indicate that our, user- and environmentally friendly protocol can be safely applied to the decontamination of prion infected stainless steel surfaces. PMID:24247293

  20. Application of diffuse discharges of atmospheric pressure formed by runaway electrons for modification of copper and stainless steel surface

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Shulepov, M. A.; Erofeev, M. V.

    2015-12-01

    The results of studies devoted to the influence of a runaway electron pre-ionized diffuse discharge (REP DD) formed in air and nitrogen at atmospheric pressure on the surface of copper and stainless steel are presented. Nanosecond high-voltage pulses were used to obtain REP DD in different gases at high pressures in a chamber with a flat anode and a cathode possessing a small radius of curvature. This mode of discharge was implemented owing to the generation of runaway electrons and X-rays. The conditions under which the surface of copper and stainless steel was cleaned from carbon and oxidized are described.

  1. Application of diffuse discharges of atmospheric pressure formed by runaway electrons for modification of copper and stainless steel surface

    SciTech Connect

    Tarasenko, V. F. Shulepov, M. A.; Erofeev, M. V.

    2015-12-15

    The results of studies devoted to the influence of a runaway electron pre-ionized diffuse discharge (REP DD) formed in air and nitrogen at atmospheric pressure on the surface of copper and stainless steel are presented. Nanosecond high-voltage pulses were used to obtain REP DD in different gases at high pressures in a chamber with a flat anode and a cathode possessing a small radius of curvature. This mode of discharge was implemented owing to the generation of runaway electrons and X-rays. The conditions under which the surface of copper and stainless steel was cleaned from carbon and oxidized are described.

  2. Chromium(III) and chromium(VI) surface treated galvanized steel for outdoor constructions: environmental aspects.

    PubMed

    Lindström, David; Hedberg, Yolanda; Odnevall Wallinder, Inger

    2010-06-01

    The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at nonsheltered urban and marine exposure conditions for 2 years are investigated. Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after 2 years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inverse. Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m(-2) yr(-1) (Zn-Cr(VI)) after 1 year of urban exposure. Aging by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI). Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site.

  3. Preparation of multi-functional superhydrophobic lanthanum surface on carbon steel via facile electrochemical method

    NASA Astrophysics Data System (ADS)

    Chen, Xi; He, Yi; Fan, Yi; Yang, Qiangbin; Li, Han

    2016-12-01

    We have constructed a superhydrophobic surface with lanthanum palmitate on carbon steel via a facile one-step electrodeposition. The morphology and chemical composition of the superhydrophobic surface were characterized by field-emission scanning electron microscopy with attached energy dispersive X-ray spectrum, Fourier transform infrared spectra and X-ray photoelectron spectroscopy, respectively. The as-prepared surface with hierarchical structure has a largest contact angle of 160° ± 0.5° and a lowest sliding angle of 2° ± 0.5°. We found that both high electrodeposition potential and high concentrations lanthanum nitrate can accelerate the formation of superhydrophobic film. The electrochemical measurements demonstrated that the superhydrophobic surface exhibited excellent anti-corrosion performance in 3.5 wt% NaCl solution. Moreover, we also investigated the chemical stability, self-cleaning and oil/water separation of the superhydrophobic film. We believe that the facile fabrication method provides a promising strategy to fabricate multi-functional superhydrophobic surface with lanthanide series rare-earth elements on kinds of substrates.

  4. Tribological properties and surface structures of ion implanted 9Cr18Mo stainless steels

    NASA Astrophysics Data System (ADS)

    Fengbin, Liu; Guohao, Fu; Yan, Cui; Qiguo, Sun; Min, Qu; Yi, Sun

    2013-07-01

    The polished quenched-and-tempered 9Cr18Mo steels were implanted with N ions and Ti ions respectively at a fluence of 2 × 1017 ions/cm2. The mechanical properties of the samples were investigated by using nanoindenter and tribometer. The results showed that the ion implantations would improve the nanohardness and tribological property, especially N ion implantation. The surface analysis of the implanted samples was carried out by using XRD, XPS and AES. It indicated that the surface exhibits graded layers after ion implantation. For N ion implantation, the surface about 20 nm thickness is mainly composed of supersaturated interstitial N solid solution, oxynitrides, CrxCy phase and metal nitrides. In the subsurface region, the metal nitrides dominate and the other phases disappear. For Ti ion implantation, the surface of about 20 nm thickness is mainly composed of titanium oxides and carbon amorphous phase, the interstitial solid solution of Ti in Fe is abundant in the subsurface region. The surface components and structures have significant contributions to the improved mechanical properties.

  5. Non-destructive enhancement of latent fingerprints on stainless steel surfaces by electrochemiluminescence.

    PubMed

    Xu, Linru; Li, Yan; He, Yayun; Su, Bin

    2013-04-21

    Visualization and detection of latent fingerprints (LFPs) on metal surfaces are of highly practical importance, e.g., in identifying gun cartridges. We report herein the visualization of LFPs on stainless steel surfaces by electrochemiluminescence (ECL). Since organic residues, such as fatty acids, in the fingerprint deposit make the underlying surface electrochemically inert or less active, an ECL reaction occurs only on the metal portions untouched by the fingertip, hence generating a negative image of the fingerprint. The popular ECL reaction solution, consisting of ruthenium(ii) tris(2,2'-bipyridyl) and tri-n-propylamine, was used for this imaging purpose. Factors, including the applied potential and the concentration of ECL luminophore, as well as the stability of ECL negative images, were investigated to achieve a satisfactory visualization enhancement. This imaging approach is simple, rapid, non-invasive, and no pre-treatment either on the background or on the fingerprint itself is needed. It constitutes a powerful tool for visualizing LFPs on metal surfaces. This method was also demonstrated to be suitable for enhancing LFPs collected from various surfaces.

  6. How to guide lubricants - Tailored laser surface patterns on stainless steel

    NASA Astrophysics Data System (ADS)

    Grützmacher, Philipp G.; Rosenkranz, Andreas; Gachot, Carsten

    2016-05-01

    In this experimental study, periodic line-like structures with different periodicities (5, 10, 19, and 300 μm) and structural depths (approximately 1 and 4 μm) were fabricated on stainless steel samples (AISI-304) by short-pulse laser interference and ultrashort-pulse laser patterning. A detailed characterization of the resulting surface topography was performed by white light interferometry and scanning electron microscopy. The spreading dynamics of additive-free synthetic polyalphaolefine oil on a polished reference sample are compared to laser patterned surfaces. These studies are conducted using a newly developed test rig, which allowed for controlled temperature gradients and a precise recording of the spreading dynamics of lubricants on sample surfaces. It could be demonstrated that the spreading velocity parallel to the surface pattern is higher for all samples which can be explained by increased capillary forces and liquid pinning induced by the surface patterning. Furthermore, a decline of the spreading velocity over time for all samples and orientations is clearly visible which can be traced back to a viscosity increase induced by the temperature gradient and a reduced droplet volume. For parallel orientation, the experimental findings are in good agreement with the Lucas-Washburn equation and established models.

  7. Corrosion of ferritic steels by molten lithium: Influence of competing thermal gradient mass transfer and surface product reactions

    SciTech Connect

    Tortorelli, P.F.

    1987-10-01

    An Fe-12Cr-1MoVW steel was exposed to thermally convective lithium for 6962 h. Results showed that the weight change profile of Fe-12Cr-1MoVW steel changed substantially as the maximum loop temperature was raised from 500 to 600/sup 0/C. Furthermore, for a particular loop experiment, changes in the structure and composition of the exposed surfaces did not reflect typical thermal gradient mass transfer effects for all elements: the surface concentration of chromium was often a maximum at intermediate temperatures, while nickel (present at low concentrations in the starting material) tended to be transported to the coldest part of the loop. Such data were interpreted in terms of a qualitative model in which there are different dominant reactions or the various constituents of the ferritic steels (surface product formation involving nitrogen and/or carbon and solubility-driven elemental transport). This competition among different reactions is important in evaluating overall corrosion behavior and the effects of temperature. The overall corrosion rate of the 12Cr-1MoVW steel was relatively low when compared to that for austenitic stainless steel exposed under similar conditions.

  8. Modification of Low-Alloy Steel Surface by Plasma Electrolytic Nitriding

    NASA Astrophysics Data System (ADS)

    Kusmanov, S. A.; Smirnov, A. A.; Silkin, S. A.; Belkin, P. N.

    2016-07-01

    The structure of the low-alloy steel after plasma electrolytic nitriding (PEN) in electrolyte containing ammonium nitrate was investigated. The cross-sectional microstructure, composition, and phase constituents of modified layer under different processing conditions were characterized. It is shown that anode PEN provides the saturation of steel with nitrogen and formation of α-Fe2O3, FeO, and Fe3O4 oxides, Fe2-3N nitride, and martensite. The aqueous solution that contained 15 wt.% NH4Cl and 5 wt.% NH4NO3 allows one to obtain the hardened layer with a thickness of 80 μm and a microhardness up to 740 HV during 5 min at 850 °C. Surface roughness decreases from 1.5 to 0.8 μm after 5-min PEN at 650 °C. The proposed electrolyte and processing mode (750 °C, 10 min) enable to obtain the decrease in the weight loss after lubricate wear testing by a factor of 2.7. The base-nitrate electrolyte conditioned a decrease in the corrosion current density by a factor of 9 due to passivating effect of the oxide and nitride of iron.

  9. Niobium boride layers deposition on the surface AISI D2 steel by a duplex treatment

    SciTech Connect

    Kon, O.; Pazarlioglu, S.

    2015-03-30

    In this paper, we investigated the possibility of deposition of niobium boride layers on the surface of AISI D2 steel by a duplex treatment. At the first step of duplex treatment, boronizing was performed on AISI D2 steel samples at 1000{sup o}C for 2h and then pre-boronized samples niobized at 850°C, 900°C and 950°C using thermo-reactive deposition method for 1–4 h. The presence of the niobium boride layers such as NbB, NbB{sub 2} and Nb{sub 3}B{sub 4} and also iron boride phases such as FeB, Fe{sub 2}B were examined by X-ray diffraction analysis. Scanning electron microscope (SEM) and micro-hardness measurements were realized. Experimental studies showed that the depth of the coating layers increased with increasing temperature and times and also ranged from 0.42 µm to 2.43 µm, depending on treatment time and temperature. The hardness of the niobium boride layer was 2620±180 HV{sub 0.005}.

  10. Surface engineering of stainless steel materials by covalent collagen immobilization to improve implant biocompatibility.

    PubMed

    Müller, Rainer; Abke, Jochen; Schnell, Edith; Macionczyk, Frank; Gbureck, Uwe; Mehrl, Robert; Ruszczak, Zbigniev; Kujat, Richard; Englert, Carsten; Nerlich, Michael; Angele, Peter

    2005-12-01

    It was shown recently that the deposition of thin films of tantalum and tantalum oxide enhanced the long-term biocompatibility of stainless steel biomaterials due to an increase in their corrosion resistance. In this study, we used this tantalum oxide coating as a basis for covalent immobilization of a collagen layer, which should result in a further improvement of implant tissue integration. Because of the high degradation rate of natural collagen in vivo, covalent immobilization as well as carbodiimide induced cross-linking of the protein was performed. It was found that the combination of the silane-coupling agent aminopropyl triethoxysilane and the linker molecule N,N'-disulphosuccinimidyl suberate was a very effective system for collagen immobilizing. Mechanical and enzymatic stability testing revealed a higher stability of covalent bound collagen layers compared to physically adsorbed collagen layers. The biological response induced by the surface modifications was evaluated by in vitro cell culture with human mesenchymal stem cells as well as by in vivo subcutaneous implantation into nude mice. The presence of collagen clearly improved the cytocompatibility of the stainless steel implants which, nevertheless, significantly depended on the cross-linking degree of the collagen layer.

  11. Biofilms formed by Mycobacterium tuberculosis on cement, ceramic, and stainless steel surfaces and their controls.

    PubMed

    Adetunji, Victoria; Kehinde, Aderemi; Bolatito, Olayemi; Chen, Jinru

    2014-04-01

    This study assessed the biofilms formed by selected strains of Mycobacterium tuberculosis and investigated the efficacy of three different treatments to control the biofilms. Two M. tuberculosis strains were inoculated separately in 150 ml of Middlebrook 7H9-Tween 80 (0.1%) broth with 5% liver extract and 10% oleic albumin dextrose catalase (OADC) supplement, 5% liver extract alone, or 10% OADC alone in sterile jars, each containing a 2-cm2 coupon of cement, ceramic, or stainless steel for biofilm development at 37 °C, with agitation for 2, 3, or 4 weeks. Biofilms on the coupons were exposed to 10 ml of 2% sanitizer A or 0.5% sanitizer B at 28 and 45 °C and to hot water at 85 °C for 5 min. Residual biofilms on treated and untreated coupons were assessed. Both strains of M. tuberculosis formed biofilms on the three surfaces; however, one strain formed more biofilms. More biofilms were formed when media containing 5% liver extract was used. Biofilm mass increased as incubation time increased until the third week. More biofilms were formed on cement than on ceramic and stainless steel coupons. Sanitizing treatments at 45 °C removed more biofilms than those at 28 °C. However, neither treatment completely eliminated the biofilms.

  12. Influence of pre-heating on the surface modification of powder-metallurgy processed cold-work tool steel during laser surface melting

    NASA Astrophysics Data System (ADS)

    Šturm, Roman; Štefanikova, Maria; Steiner Petrovič, Darja

    2015-01-01

    In this study we determine the optimal parameters for surface modification using the laser surface melting of powder-metallurgy processed, vanadium-rich, cold-work tool steel. A combination of steel pre-heating, laser surface melting and a subsequent heat treatment creates a hardened and morphologically modified surface of the selected high-alloy tool steel. The pre-heating of the steel prior to the laser surface melting ensures a crack- and pore-free modified surface. Using a pre-heating temperature of 350 °C, the extremely fine microstructure, which typically evolves during the laser-melting, became slightly coarser and the volume fraction of retained austenite was reduced. In the laser-melted layer the highest values of microhardness were achieved in the specimens where a subsequent heat treatment at 550 °C was applied. The performed thermodynamic calculations were able to provide a very valuable assessment of the liquidus temperature and, especially, a prediction of the chemical composition as well as the precipitation and dissolution sequence for the carbides.

  13. Correlation between surface physicochemical properties and the release of iron from stainless steel AISI 304 in biological media.

    PubMed

    Hedberg, Yolanda; Karlsson, Maria-Elisa; Blomberg, Eva; Odnevall Wallinder, Inger; Hedberg, Jonas

    2014-10-01

    Stainless steel is widely used in biological environments, for example as implant material or in food applications, where adsorption-controlled ligand-induced metal release is of importance from a corrosion, health, and food safety perspective. The objective of this study was to elucidate potential correlations between surface energy and wettability of stainless steel surfaces and the release of iron in complexing biological media. This was accomplished by studying changes in surface energies calculated from contact angle measurements, surface oxide composition (X-ray photoelectron spectroscopy), and released iron (graphite furnace atomic absorption spectroscopy) for stainless steel grade AISI 304 immersed in fluids containing bovine serum albumin or citric acid, and non-complexing fluids such as NaCl, NaOH, and HNO3. It was shown that the surface wettability and polar surface energy components were all influenced by adventitious atmospheric carbon (surface contamination of low molecular weight), rather than differences in surface oxide composition in non-complexing solutions. Adsorption of both BSA and citrate, which resulted in ligand-induced metal release, strongly influenced the wettability and the surface energy, and correlated well with the measured released amount of iron.

  14. Energy of the surface layer deterioration of 1020 steel and copper at dry sliding against 1045 steel with a high electric current density

    NASA Astrophysics Data System (ADS)

    Fadin, V. V.; Aleutdinova, M. I.; Rubtsov, V. E.

    2016-11-01

    Dry sliding of copper and 1020 steel against 1045 steel under the influence of the contact current density higher than 250 A/cm2 is carried out by using the pin-on-ring testing scheme. The change in the surface layer structure and the formation of a tribolayer consisting of iron, copper, and FeO oxide are shown. It is noted that the thin contact layer contains near 40 at % of oxygen. The specific wear rate is calculated based on the data of wear and current-voltage characteristics of the contact. A limited applicability of this parameter for the description of the surface layer deterioration is shown. We propose a wear parameter close to it, which characterizes more correctly the specimen tribolayer deterioration. These wear characteristics increase with a current density increase. It is established that the work of tribolayer deterioration can be close to a half of energy generated in contact. Some increase in the work of tribolayer deterioration due to a reduction in heat flow to the specimen is noted. It is shown that these wear characteristics of copper are considerably lower than that of 1020 steel. It is explained by the presence of copper in the tribolayer of the copper specimen that allows an easier stress relaxation to be realized.

  15. Liquid Metal Embrittlement in Resistance Spot Welding and Hot Tensile Tests of Surface-refined TWIP Steels

    NASA Astrophysics Data System (ADS)

    Barthelmie, J.; Schram, A.; Wesling, V.

    2016-03-01

    Automotive industry strives to reduce vehicle weight and therefore fuel consumption and carbon dioxide emissions. Especially in the auto body, material light weight construction is practiced, but the occupant safety must be ensured. These requirements demand high-strength steels with good forming and crash characteristics. Such an approach is the use of high- manganese-content TWIP steels, which achieve strengths of around 1,000 MPa and fracture strains of more than 60%. Welding surface-refined TWIP steels reduces their elongation at break and produces cracks due to the contact with liquid metal and the subsequent liquid metal embrittlement (LME). The results of resistance spot welds of mixed joints of high-manganese- content steel in combination with micro-alloyed ferritic steel and hot tensile tests are presented. The influence of different welding parameters on the sensitivity to liquid metal embrittlement is investigated by means of spot welding. In a high temperature tensile testing machine, the influence of different parameters is determined regardless of the welding process. Defined strains just below or above the yield point, and at 25% of elongation at break, show the correlation between the applied strain and liquid metal crack initiation. Due to the possibility to carry out tensile tests on a wide range of temperatures, dependencies of different temperatures of the zinc coating to the steel can be identified. Furthermore, the attack time of the zinc on the base material is investigated by defined heating periods.

  16. Shear-flow induced detachment of Saccharomyces cerevisiae from stainless steel: influence of yeast and solid surface properties.

    PubMed

    Guillemot, Gaëlle; Vaca-Medina, Guadalupe; Martin-Yken, Helene; Vernhet, Aude; Schmitz, Philippe; Mercier-Bonin, Muriel

    2006-05-01

    The present study focused on the shear-induced detachment of Saccharomyces cerevisiae in adhesive contact with a 316L stainless steel surface using a shear stress flow chamber, with a view to determining the respective influence of the yeast surface properties and the support characteristics. The effect of cultivation of S. cerevisiae yeast cells on their subsequent detachment from the solid surface was particularly investigated. In order to elucidate the role of stainless steel, non-metallic supports were used as control, covering a broad range of surface properties such as surface free energy and roughness: polypropylene (hydrophobic), polystyrene (mildly hydrophobic, similar to stainless steel) and glass (hydrophilic). All materials were very smooth with respect to the size of yeast. First, experiments were carried out on two types of yeast cells, just rehydrated in saline solution, a biological model widely used in the literature. The influence of the ionic strength (1.5 and 150 mM NaCl) on glass and stainless steel was evaluated. Unlike on glass, no clear evidence was found for electrostatic repulsion with stainless steel since high adhesion was observed whatever the ionic strength. A lack of correlation in adhesion results was also obtained when considering the surface physico-chemical characteristics of type I (hydrophilic) and type II (hydrophobic) rehydrated cells and those of both polymers. It was postulated that unavoidable "sticky" compounds were present on the cell wall, which could not be completely removed during the successive washings of the rehydrated cell suspension before use. This could dramatically alter the yeast surface properties and modify the adhesion strength, thus clearly demonstrating the necessity to work with yeast coming from fresh cultures. Biologically active yeast cells were then used. Once cultured, type I- and type II-yeast cells were shown to exhibit the same hydrophilic properties. Regardless of the material used, for the

  17. Melt expulsion during ultrasonic vibration-assisted laser surface processing of austenitic stainless steel.

    PubMed

    Alavi, S Habib; Harimkar, Sandip P

    2015-05-01

    Simultaneous application of ultrasonic vibrations during conventional materials processing (casting, welding) and material removal processes (machining) has recently been gaining widespread attention due to improvement in metallurgical quality and efficient material removal, respectively. In this paper, ultrasonic vibration-assisted laser surface melting of austenitic stainless steel (AISI 316) is reported. While the application of ultrasonic vibrations during laser processing delays the laser interaction with material due to enhancement of surface convection, it resulted in expulsion of melt from the irradiated region (forming craters) and transition from columnar to equiaxed dendritic grain structure in the resolidified melt films. Systematic investigations on the effect of ultrasonic vibrations (with vibrations frequency of 20 kHz and power output in the range of 20-40%) on the development of microstructure during laser surface melting (with laser power of 900 W and irradiation time in the range of 0.30-0.45 s) are reported. The results indicate that the proposed ultrasonic vibration-assisted laser processing can be designed for efficient material removal (laser machining) and improved equiaxed microstructure (laser surface modifications) during materials processing.

  18. Microstructural investigation, using small-angle neutron scattering (SANS), of Optifer steel after low dose neutron irradiation and subsequent high temperature tempering

    NASA Astrophysics Data System (ADS)

    Coppola, R.; Lindau, R.; Magnani, M.; May, R. P.; Möslang, A.; Valli, M.

    2007-08-01

    The microstructural effect of low dose neutron irradiation and subsequent high temperature tempering in the reduced activation ferritic/martensitic steel Optifer (9.3 Cr, 0.1 C, 0.50 Mn, 0.26 V, 0.96 W, 0.66 Ta, Fe bal wt%) has been studied using small-angle neutron scattering (SANS). The investigated Optifer samples had been neutron irradiated, at 250 °C, to dose levels of 0.8 dpa and 2.4 dpa. Some of them underwent 2 h tempering at 770 °C after the irradiation. The SANS measurements were carried out at the D22 instrument of the High Flux Reactor at the Institut Max von Laue - Paul Langevin, Grenoble, France. The differences observed in nuclear and magnetic SANS cross-sections after subtraction of the reference sample from the irradiated one suggest that the irradiation and the subsequent post-irradiation tempering produce the growth of non-magnetic defects, tentatively identified as microvoids.

  19. NEAMS-ATF M3 Milestone Report: Literature Review of Modeling of Radiation-Induced Swelling in Fe-Cr-Al Steels

    SciTech Connect

    Bai, Xianming; Biner, Suleyman Bulent; Jiang, Chao

    2015-12-01

    Fe-Cr-Al steels are proposed as accident-tolerant-fuel (ATF) cladding materials in light water reactors due to their excellent oxidation resistance at high temperatures. Currently, the understanding of their performance in reactor environment is still limited. In this review, firstly we reviewed the experimental studies of Fe-Cr-Al based alloys with particular focus on the radiation effects in these alloys. Although limited data are available in literature, several previous and recent experimental studies have shown that Fe-Cr-Al based alloys have very good void swelling resistance at low and moderate irradiation doses but the growth of dislocation loops is very active. Overall, the behavior of radiation damage evolution is similar to that in Fe-Cr ferritic/martensitic alloys. Secondly, we reviewed the rate theory-based modeling methods for modeling the coevolution of voids and dislocation loops in materials under irradiation such as Frenkel pair three-dimensional diffusion model (FP3DM) and cluster dynamics. Finally, we summarized and discussed our review and proposed our future plans for modeling radiation damage in Fe-Cr-Al based alloys.

  20. The Effect of Surface Preparation on the Precipitation of Sigma During High Temperature Exposure of S32205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Jepson, Mark A. E.; Rowlett, Matthew; Higginson, Rebecca L.

    2017-01-01

    Although the formation of sigma phase in duplex stainless steels is reasonably well documented, the effect of surface finish on its formation rate in surface regions has not been previously noted. The growth of the sigma phase precipitated in the subsurface region (to a maximum depth of 120 μm) has been quantified after heat treatment of S32205 duplex stainless steel at 1073 K (800 °C) and 1173 K (900 °C) after preparation to two surface finishes. Here, results are presented that show that there is a change in the rate of sigma phase formation in the surface region of the material, with a coarser surface finish leading to a greater depth of precipitation at a given time and temperature of heat treatment. The growth rate and morphology of the precipitated sigma has been examined and explored in conjunction with thermodynamic equilibrium phase calculations.

  1. The Effect of Surface Preparation on the Precipitation of Sigma During High Temperature Exposure of S32205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Jepson, Mark A. E.; Rowlett, Matthew; Higginson, Rebecca L.

    2017-03-01

    Although the formation of sigma phase in duplex stainless steels is reasonably well documented, the effect of surface finish on its formation rate in surface regions has not been previously noted. The growth of the sigma phase precipitated in the subsurface region (to a maximum depth of 120 μm) has been quantified after heat treatment of S32205 duplex stainless steel at 1073 K (800 °C) and 1173 K (900 °C) after preparation to two surface finishes. Here, results are presented that show that there is a change in the rate of sigma phase formation in the surface region of the material, with a coarser surface finish leading to a greater depth of precipitation at a given time and temperature of heat treatment. The growth rate and morphology of the precipitated sigma has been examined and explored in conjunction with thermodynamic equilibrium phase calculations.

  2. Microhardness and Surface Integrity in Turning Process of Duplex Stainless Steel (DSS) for Different Cutting Conditions

    NASA Astrophysics Data System (ADS)

    Krolczyk, G.; Nieslony, P.; Legutko, S.

    2014-03-01

    The objective of the investigation was to identify microhardness of surface integrity (SI) after turning with wedges of coated sintered carbide. SI is important in determining corrosion resistance, and also in fatigue crack initiation. The investigation included microhardness analyses in dry and wet machining of duplex stainless steel. The microhardness of SI for various cutting speeds was compared. It has been shown that wet cutting leads to the decrease of SI hardening depth, while increasing the rounded cutting edge radius of the wedge increases the maximum microhardness values and the hardening depth. An infinite focus measurement machine has been used for the rounded cutting edge radius analysis. The study has been performed within a production facility during the production of electric motor parts and deep-well pumps as well as explosively cladded sheets.

  3. Preparation, characterization and dissolution of passive oxide film on the 400 series stainless steel surfaces

    NASA Astrophysics Data System (ADS)

    Sathyaseelan, V. S.; Rufus, A. L.; Chandramohan, P.; Subramanian, H.; Velmurugan, S.

    2015-12-01

    Full system decontamination of Primary Heat Transport (PHT) system of Pressurised Heavy Water Reactors (PHWRs) resulted in low decontamination factors (DF) on stainless steel (SS) surfaces. Hence, studies were carried out with 403 SS and 410 SS that are the material of construction of "End-Fitting body" and "End-Fitting Liner tubes". Three formulations were evaluated for the dissolution of passive films formed over these alloys viz., i) Two-step process consisting of oxidation and reduction reactions, ii) Dilute Chemical Decontamination (DCD) and iii) High Temperature Process. The two-step and high temperature processes could dissolve the oxide completely while the DCD process could remove only 60%. Various techniques like XRD, Raman spectroscopy and SEM-EDX were used for assessing the dissolution process. The two-step process is time consuming, laborious while the high temperature process is less time consuming and is recommended for SS decontamination.

  4. Materials selection of surface coatings in an advanced size reduction facility. [For decommissioned stainless steel equipment

    SciTech Connect

    Briggs, J. L.; Younger, A. F.

    1980-06-02

    A materials selection test program was conducted to characterize optimum interior surface coatings for an advanced size reduction facility. The equipment to be processed by this facility consists of stainless steel apparatus (e.g., glove boxes, piping, and tanks) used for the chemical recovery of plutonium. Test results showed that a primary requirement for a satisfactory coating is ease of decontamination. A closely related concern is the resistance of paint films to nitric acid - plutonium environments. A vinyl copolymer base paint was the only coating, of eight paints tested, with properties that permitted satisfactory decontamination of plutonium and also performed equal to or better than the other paints in the chemical resistance, radiation stability, and impact tests.

  5. Simulating microbiologically influenced corrosion by depositing extracellular biopolymers on mild steel surfaces

    SciTech Connect

    Roe, F.L.; Lewandowski, Z.; Funk, T.

    1996-10-01

    Electrochemical properties of corroding mild steel (MS) surfaces were measured in real time using three closely spaced microelectrodes. Dissolved oxygen, pH, and ion currents were mapped simultaneously and noninvasively above a MS coupon partially coated with biopolymer gels. Calcium alginate (Ca-Alg [an extracellular biopolymer containing carboxylate functional groups]) and agarose (one without carboxylate functional groups) were tested. Corrosion occurred at approximately the same rate under the two biopolymer spots on the same coupon. Corrosion rates under these biopolymers were {approx} 4 mpy in a weak saline solution. Results suggested corrosion was not influenced by chemical properties of the biopolymer but possibly was controlled by oxygen reduction in noncoated regions of the coupon (i.e., a differential aeration cell).

  6. Initial colloid deposition on bare and zeolite-coated stainless steel and aluminum: influence of surface roughness.

    PubMed

    Chen, Gexin; Bedi, Rajwant S; Yan, Yushan S; Walker, Sharon L

    2010-08-03

    The impact of surface roughness of bare and zeolite ZSM-5 coated stainless steel and aluminum alloy on colloid deposition has been investigated using a parallel plate flow chamber system in an aqueous environment. The metals were systematically polished to alter the surface roughness from nanoscale to microscale, with the subsequent surface roughness of both the bare and coated surfaces varying from 11.2 to 706 nm. The stainless steel and aluminum alloy surfaces are extensively characterized, both as bare and as coated surfaces. Experimental results suggest that ZSM-5 coating and surface roughness have a pronounced impact on the kinetics of the colloid deposition. The ZSM-5 coating reduced colloid adhesion compared to the corresponding bare metal surface. In general, the greater surface roughness of like samples resulted in higher colloid deposition. Primarily, this is due to greater surface roughness inducing less reduction in the attractive interactions occurring between colloids and collector surfaces. This effect was sensitive to ionic strength and was found to be more pronounced at lower ionic strength conditions. For the most electrostatically unfavorable scenario (ZSM-5 coatings in 1 mM KNO(3)), the enhanced deposition may also be attributed to inherent surface charge heterogeneity of ZSM-5 coatings due to aluminum in the crystalline structure. The two exceptions are ZSM-5 coated mirror-polished stainless steel and the unpolished aluminum surfaces, which are rougher than the other two samples of the same metal type but result in the least deposition. The reasons for these observations are discussed, as well as the effect of surface charge and hydrophobicity on the adhesion. The relative importance of surface roughness versus contributions of electrostatic interactions and hydrophobicity to the colloid deposition is also discussed.

  7. Influence of a Cerium surface treatment on the oxidation behavior of type 347 stainless steel

    SciTech Connect

    Alman, D.E.; Jablonski, P.D.

    2007-04-01

    A surface treatment was applied to the surface of Type 347 stainless steel to enhance oxidation resistance. The treatment consisted of dip coating coupons in a CeO2 and halide activator slurry, followed by a thermal treatment at 900C in an inert atmosphere for 12 hours. Cyclical oxidation tests were conducted at 800C in either dry air or air+3%H2O. In dry air, the treatment reduced the oxidation rate (reduced the magnitude of weight gain) of the alloy by a factor of three. Protective chromium based oxide and spinel ((Mn,Cr)3O4 and (Cr,Fe)2O3) phases formed on the surface of the untreated and treated alloy. More significantly, the treatment suppressed the oxide scale spallation that occurred upon cyclical exposure of this alloy to moist air. In moist air, less protective chromite (FeCr2O4), magnetite (Fe+2Fe2+3O4), and hematite (Fe2O3) formed as oxide products on the surface of the base alloy. The treated alloy did not spall during exposure to moist air, and interestingly, the treated alloy possessed similar oxidation rates (magnitude of weight gain) in both moist and dry air. The same protective chromium based oxide and spinel ((Mn,Cr)3O4 and (Cr,Fe)2O3) phases formed on the surface of the treated alloy exposed to both moist and dry air. In the aggressive moist environment, the Ce surface treatment suppressed the formation of less protective iron-oxides, and concomitant oxide scale spallation during thermal cycling.

  8. Quartz Crystal Microbalance Investigation of the Structure of Adsorbed Soybean Oil and Methyl Oleate onto Steel Surface

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The adsorption of soybean oil (SBO) and methyl oleate (MO) onto steel was investigated using quartz crystal microbalance with dissipation monitoring (QCM-D). Adsorption of both SBO and MO increased with increasing concentrations. At full surface coverage, SBO and MO formed rigid thin films and ach...

  9. Research of surface activating influence on formation of adhesion between gas-thermal coating and steel substrate

    NASA Astrophysics Data System (ADS)

    Kovalevskaya, Z.; Klimenov, V.; Zaitsev, K.

    2015-09-01

    Estimation of influence of physical and thermal activating on adhesion between steel substrates and thermal coatings has been performed. The substrates with surfaces obtained by and ultrasonic surface plastic deformation were used. To evaluate physical activating, preheating of the substrates to 600°C was performed. To evaluate the effect of thermal activating, the substrate surfaces after interfacial detachment were examined. Bonded areas on the substrate surfaces were measured by means of optical profilometry. The experiments have shown that surface physical activating is the main factor in formation of the adhesive bond between the coating and the substrate processed with the proposed methods.

  10. Investigations on Surface Milling of Hardened AISI 4140 Steel with Pulse Jet MQL Applicator

    NASA Astrophysics Data System (ADS)

    Bashir, Mahmood Al; Mia, Mozammel; Dhar, Nikhil Ranjan

    2016-06-01

    In this article, an experimental investigation was performed in milling hardened AISI 4140 steel of hardness 40 HRC. The machining was performed in both dry and minimal quantity lubricant (MQL) conditions, as part of neat machining, to make a strong comparison of the undertaken machining environments. The MQL was impinged int the form of pulse jet, by using the specially developed pulse-jet-attachment, to ensure that the cutting fluid can be applied in different timed pulses and quantities at critical zones. The tool wear, cutting force and surface roughness were taken as the quality responses while cutting speed, table feed rate and flow rate of the pulse were considered as influential factors. The depth of cut was kept constant at 1.50 mm because of its less significant effects and the straight oil was adopted as cutting fluid in pulse-jet-MQL. The effects of different factors, on the quality responses, are analyzed using ANOVA. It is observed that MQL applicator system exhibits overall better performance when compared to dry milling by reducing surface roughness, cutting force and prolonging tool life but a flow rate of 150 ml/h has tremendous effects on the responses. This investigation and afterward results are expected to aid the industrial practitioner and researcher to adopt the pulse-MQL in high speed milling to prolong tool life, reduce tool wear, diminish cutting force generation and promote better surface finish.

  11. The role of nitrogen in the preferential chromium segregation on the ferritic stainless steel (1 1 1) surface

    NASA Astrophysics Data System (ADS)

    Yuhara, J.; Matsui, T.

    2010-03-01

    The temperature dependence on the segregation behavior of the ferritic stainless steel single crystal (1 1 1) surface morphology has been examined by scanning tunneling microscopy (STM), Auger electron spectroscopy (AES), and low energy electron diffraction (LEED). AES clearly showed the surface segregations of chromium and nitrogen upon annealing. Nanoscale triangular chromium nitride clusters were formed around 650 °C and were regularly aligned in a hexagonal configuration. In contrast, for the ferritic stainless steel (1 1 1) surface with low-nitrogen content, chromium and carbon were found to segregate on the surface upon annealing and Auger spectra of carbon displayed the characteristic carbide peak. For the low-nitrogen surface, LEED identified a facetted surface with (2 × 2) superstructure at 650 °C. High-resolution STM identified a chromium carbide film with segregated carbon atoms randomly located on the surface. The facetted (2 × 2) superstructure changed into a (3 × 3) superstructure with no faceting upon annealing at 750 °C. Also, segregated sulfur seems to contribute to the reconstruction or interfacial relaxation between the ferritic stainless steel (1 1 1) substrate and chromium carbide film.

  12. An in vitro comparison of four surface preparation techniques for veneering a compomer to stainless steel.

    PubMed

    Salama, F S; el-Mallakh, B F

    1997-01-01

    Compomers are a new class of materials reportedly having the anticariogenicity and the bonding ability to metals similar to glass ionomers while maintaining the high esthetic qualities of composite resins. The purpose of this study was to determine and evaluate the shear bond strength and fracture pattern of a compomer (Dyract) to stainless steel crowns (SSCs) using different mechanical and chemical retention procedures for possible future development of a chair-side technique of producing esthetic SSCs. Thirty-two Unitek SSCs, divided into four groups, were mounted in autopolymerizing acrylic resin so that the resulting specimen has the crown's flat lingual surface projecting above and parallel to the top surface of the acrylic resin block. Dyract was placed in transparent nylon cylinders (3 x 3 mm) and bonded to SSC's surfaces directly (group 1) or following sandblasting of the SSCs (group 2). In group 3, Dyract was bonded to stainless steel lingual cleats that were previously spot-welded to the SSCs. In group 4, Dyract was bonded to sandblasted SSC's surfaces using Scotchbond Multi-Purpose Plus dental adhesive. Specimens were placed in deionized water for 1 hr at 37 degrees C. Shear bond strength was measured using a universal testing machine. The mean (SD) shear bond strengths in MPa for groups 1-4 respectively were as follows: 2.998 (1.381), 9.518 (2.464), 13.909 (1.653), and 9.372 (3.723). One-way ANOVA and Tukey's multiple range tests revealed a statistically significant difference between the groups (P < 0.00001). While no significant difference was found between groups 2 and 4 in which Dyract-PSA prime/adhesive and Scotchbond Multi-Purpose Plus dental adhesive were used, group 3 had significantly higher shear bond strength than other groups. Stereoscopic and SEM examinations revealed adhesive and mixed bond failures. It is concluded that the bond strength of Dyract to SSCs could be enhanced significantly by applying simple mechanical means of retention

  13. Biofouling of Cr-Nickel Spray Coated Films on Steel Surfaces

    NASA Astrophysics Data System (ADS)

    Yoshida, Kento; Kanematsu, Hideyuki; Kuroda, Daisuke; Ikigai, Hajime; Kogo, Takeshi; Yokoyama, Seiji

    2012-03-01

    Nowadays, corrosion of metals brings us serious economic loss and it often reaches several percentage of GNP. Particularly the marine corrosion was serious and the counter measure was very hard to be established, since the number of factors is huge and complicated. One of the complicated factors in marine corrosion is biofouling. Biofouling was classified into two main categories, microfouling and macrofouling. The former is composed of biofilm formation mainly. Marine bacteria are attached to material surfaces, seeking for nutrition in oligotrophic environment and they excrete polysaccharide to form biofilm on metal surfaces. Then larger living matters are attached on the biofilms to develop biofouling on metal surfaces, which often lead loss and failures of metals in marine environments. From the viewpoint of corrosion protection and maintenance of marine structures, biofouling should be mitigated as much as possible. In this study, we applied spray coating to steels and investigated if chromium-nickel spray coating could mitigate the biofouling, being compared with the conventional aluminium-zinc spray coating in marine environments. The specimens used for this investigation are aluminium, zinc, aluminium-zinc, stacked chromium/nickel and those films were formed on carbon steel (JIS SS400). And the pores formed by spray coating were sealed by a commercial reagent for some specimens. All of those specimens were immersed into sea water located at Marina Kawage (854-3, Chisato, Tsu, Mie Prefecture) in Ise Bay for two weeks. The depth of the specimen was two meter from sea water surface and the distance was always kept constant, since they were suspended from the floating pier. The temperature in sea water changed from 10 to 15 degrees Celsius during the immersion test. The biofouling behavior was investigated by low vacuum SEM (Hitachi Miniscope TM1000) and X-ray fluorescent analysis. When the spray coated specimens with and without sealing agents were compared

  14. Accumulation of radioactive corrosion products on steel surfaces of VVER type nuclear reactors. I. 110mAg

    NASA Astrophysics Data System (ADS)

    Hirschberg, Gábor; Baradlai, Pál; Varga, Kálmán; Myburg, Gerrit; Schunk, János; Tilky, Péter; Stoddart, Paul

    Formation, presence and deposition of corrosion product radionuclides (such as 60Co, 51Cr, 54Mn, 59Fe and/or 110mAg) in the primary circuits of water-cooled nuclear reactors (PWRs) throw many obstacles in the way of normal operation. During the course of the work presented in this series, accumulations of such radionuclides have been studied at austenitic stainless steel type 08X18H10T (GOST 5632-61) surfaces (this austenitic stainless steel corresponds to AISI 321). Comparative experiments have been performed on magnetite-covered carbon steel (both materials are frequently used in some Soviet VVER type PWRs). For these laboratory-scale investigations a combination of the in situ radiotracer `thin gap' method and voltammetry is considered to be a powerful tool due to its high sensitivity towards the detection of the submonolayer coverages of corrosion product radionuclides. An independent technique (XPS) is also used to characterize the depth distribution and chemical state of various contaminants in the passive layer formed on austenitic stainless steel. In the first part of the series the accumulation of 110mAg has been investigated. Potential dependent sorption of Ag + ions (cementation) is found to be the predominant process on austenitic steel, while in the case of magnetite-covered carbon steel the silver species are mainly depleted in the form of Ag 2O. The XPS depth profile of Ag gives an evidence about the embedding of metallic silver into the entire passive layer of the austenitic stainless steel studied.

  15. Influence of the post-weld surface treatment on the corrosion resistance of the duplex stainless steel 1.4062

    NASA Astrophysics Data System (ADS)

    Rosemann, P.; Müller, C.; Baumann, O.; Modersohn, W.; Halle, T.

    2017-03-01

    The duplex stainless steel 1.4062 (X2CrNiN22-2) is used as alternative material to austenitic stainless steels in the construction industry. The corrosion resistance of welded seams is influenced by the base material, the weld filler material, the welding process and also by the final surface treatment. The scale layer next to the weld seam can be removed by grinding, pickling, electro-polished or blasting depending on the application and the requested corrosion resistance. Blasted surfaces are often used in industrial practice due to the easier and cheaper manufacturing process compared to pickled or electro-polished surfaces. Furthermore blasting with corundum-grain is more effective than blasting with glass-beads which also lower the process costs. In recent years, stainless steel surfaces showed an unusually high susceptibility to pitting corrosion after grinding with corundum. For this reason, it is now also questioned critically whether the corrosion resistance is influenced by the applied blasting agent. This question was specifically investigated by comparing grinded, pickled, corundum-grain- and glass-bead-blasted welding seams. Results of the SEM analyses of the blasting agents and the blasted surfaces will be presented and correlated with the different performed corrosion tests (potential measurement, KorroPad-test and pitting potential) on welding seams with different surface treatments.

  16. Microstructure and its effect on toughness and wear resistance of laser surface melted and post heat treated high speed steel

    NASA Astrophysics Data System (ADS)

    Åhman, Leif

    1984-10-01

    High speed steel hacksaw blade blanks were laser surface melted and rapidly solidified along one edge. The laser melting resulted in complete carbide dissolution. By subsequent machining and heat treatments saw teeth were manufactured with a refined internal structure of the edges and corners. The structure was fully martensitic with a uniform and dense dispersion of small primary carbides. Sawing tests in quenched and tempered steel showed that blade life was somewhat improved, as compared to conventionally heat treated blades. The increased wear resistance is believed to be due to improved toughness along with high hardness caused by the refined carbide structure. Sawing tests in austenitic stainless steel did not give any significant improvement in performance. The effect of the altered microstructure on performance is likely to be more or less pronounced depending on application, tool and work material.

  17. Manganese-Cobalt Mixed Spinel Oxides as Surface Modifiers for Stainless Steel Interconnects of Solid Oxide Fuel Cells

    SciTech Connect

    Xia, Gordon; Yang, Z Gary; Stevenson, Jeffry W.

    2006-11-06

    Ferritic stainless steels are promising candidates for interconnect applications in low- and mid-temperature solid oxide fuel cells (SOFCs). A couple of issues however remain for the particular application, including the chromium poisoning due to chromia evaporation, and long-term surface and electrical stability of the scale grown on these steels. Application of a manganese colbaltite spinel protection layer on the steels appears to be an effective approach to solve the issues. For an optimized performance, Mn{sub 1+x}Co{sub 2-x}O{sub 4} (-1 {le} x {le} 2) spinels were investigated against properties relative for protection coating applications on ferritic SOFC interconnects. Overall it appears that the spinels with x around 0.5 demonstrate a good CTE match to ceramic cell components, a relative high electrical conductivity, and a good thermal stability up to 1,250 C. This was confirmed by a long-term test on the Mn{sub 1.5}Co{sub 1.5}O{sub 4} protection layer that was thermally grown on Crofer22 APU, indicating the spinel protection layer not only significantly decreased the contact resistance between a LSF cathode and the stainless steel interconnects, but also inhibited the sub-scale growth on the stainless steels.

  18. A Black Phosphate Conversion Coating on Steel Surface Using Antimony(III)-Tartrate as an Additive

    NASA Astrophysics Data System (ADS)

    Li, Feng; Wang, Guiping

    2016-05-01

    A novel black phosphate conversion coating was formed on steel surface through a Zn-Mn phosphating bath containing mainly ZnO, H3PO4, Mn(H2PO4)2, and Ca(NO3)2, where antimony(III)-tartrate was used as the blackening agent of phosphatization. The surface morphology and composition of the coating were characterized by scanning electron microscopy, energy dispersion spectroscopy, and x-ray photoelectron spectroscopy. Corrosion resistance of the coating was studied by potentiodynamic polarization curves and electrochemical impedance spectroscopy. The pH value of the solution had significant influence on the formation and corrosion resistance of the coating. The experimental results indicated that the Sb plays a vital role in the blackening of phosphate conversion coating. The optimal concentration of antimony(III)-tartrate in the phosphating bath used in this experiment was 1.0 g L-1, as higher values reduced the corrosion resistance of the coating. In addition, by saponification and oil seals, the corrosion duration of the black phosphate coating in a copper sulfate spot test can be as long as 20 min.

  19. Cleaning verification: Exploring the effect of the cleanliness of stainless steel surface on sample recovery.

    PubMed

    Haidar Ahmad, Imad A; Tam, James; Li, Xue; Duffield, William; Tarara, Thomas; Blasko, Andrei

    2017-02-05

    The parameters affecting the recovery of pharmaceutical residues from the surface of stainless steel coupons for quantitative cleaning verification method development have been studied, including active pharmaceutical ingredient (API) level, spiking procedure, API/excipient ratio, analyst-to-analyst variability, inter-day variability, and cleaning procedure of the coupons. The lack of a well-defined procedure that consistently cleaned coupon surface was identified as the major contributor to low and variable recoveries. Assessment of acid, base, and oxidant washes, as well as the order of treatment, showed that a base-water-acid-water-oxidizer-water wash procedure resulted in consistent, accurate spiked recovery (>90%) and reproducible results (Srel≤4%). By applying this cleaning procedure to the previously used coupons that failed the cleaning acceptance criteria, multiple analysts were able to obtain consistent recoveries from day-to-day for different APIs, and API/excipient ratios at various spike levels. We successfully applied our approach for cleaning verification of small molecules (MW<1000Da) as well as large biomolecules (MW up to 50,000Da). Method robustness was greatly influenced by the sample preparation procedure, especially for analyses using total organic carbon (TOC) determination.

  20. Computer simulation of the relationship between selected properties of laser remelted tool steel surface layer

    NASA Astrophysics Data System (ADS)

    Bonek, Mirosław; Śliwa, Agata; Mikuła, Jarosław

    2016-12-01

    Investigations >The language in this paper has been slightly changed. Please check for clarity of thought, and that the meaning is still correct, and amend if necessary.include Finite Element Method simulation model of remelting of PMHSS6-5-3 high-speed steel surface layer using the high power diode laser (HPDL). The Finite Element Method computations were performed using ANSYS software. The scope of FEM simulation was determination of temperature distribution during laser alloying process at various process configurations regarding the laser beam power and method of powder deposition, as pre-coated past or surface with machined grooves. The Finite Element Method simulation was performed on five different 3-dimensional models. The model assumed nonlinear change of thermal conductivity, specific heat and density that were depended on temperature. The heating process was realized as heat flux corresponding to laser beam power of 1.4, 1.7 and 2.1 kW. Latent heat effects are considered during solidification. The molten pool is composed of the same material as the substrate and there is no chemical reaction. The absorptivity of laser energy was dependent on the simulated materials properties and their surface condition. The Finite Element Method simulation allows specifying the heat affected zone and the temperature distribution in the sample as a function of time and thus allows the estimation of the structural changes taking place during laser remelting process. The simulation was applied to determine the shape of molten pool and the penetration depth of remelted surface. Simulated penetration depth and molten pool profile have a good match with the experimental results. The depth values obtained in simulation are very close to experimental data. Regarding the shape of molten pool, the little differences have been noted. The heat flux input considered in simulation is only part of the mechanism for heating; thus, the final shape of solidified molten pool will depend

  1. Surface textural features and its formation process of AISI 304 stainless steel subjected to massive LSP impacts

    NASA Astrophysics Data System (ADS)

    Luo, K. Y.; Yao, H. X.; Dai, F. Z.; Lu, J. Z.

    2014-04-01

    The effects of massive laser shock peening (LSP) impacts on surface textural feature of AISI 304 stainless steel (AISI 304 SS), including surface waviness, surface roughness, and machining texture and direction, have been investigated by using WKYO-NT1100 surface profiler and TR300 stylus roughness shape measuring instrument. Experimental results show that massive LSP impacts have an important influence on the surface waviness of the AISI 304 SS sample, but do not have a measurable impact on the surface roughness. Moreover, massive LSP impacts with constraint and ablation mode generate a novel compound texture on the surface of the AISI 304 SS sample. In addition, the formation process of surface compound texture in AISI 304 SS by massive LSP impacts is also entirely revealed.

  2. Report on sodium compatibility of advanced structural materials.

    SciTech Connect

    Li, M.; Natesan, K.; Momozaki, Y.; Rink, D.L.; Soppet, W.K.; Listwan, J.T.

    2012-07-09

    alloys was comparable after sodium exposures at 550 C; the weight loss of ferritic-martensitic steels, G92 and G91 is more significant than that of austenitic stainless steel, HT-UPS after sodium exposures at 650 C. Sodium exposures up to 2700 h at 550 C had no significant influence on tensile properties, while sodium exposures up to 5064 h at 650 C dramatically lowered the tensile strengths of the four alloys. The ultimate tensile strength of H1 G92, H2 G92, and G91 ferritic-martensitic steels was reduced to as much as nearly half of its initial value after sodium exposures at 650 C. Though the uniform elongation was recovered to some extent, these three ferritic-martensitic steels showed considerable strain softening after sodium exposures. The yield stress of HT-UPS austenitic stainless steel increased, the ultimate tensile strength decreased, and the total elongation was reduced after sodium exposures at 650 C. The dynamic strain aging effect observed in the as-received HT-UPS specimens became less pronounced after sodium exposures at 650 C. Microstructural characterization of sodium-exposed specimens showed no appreciable surface deterioration or grain structure changes under an optical microscope, except for the H2 G92 steel, in which the martensite structure transformed to large grain ferrite after sodium exposures at 650 C. TEM observations of the sodium-exposed H2 G92 steel showed significant recrystallization after sodium exposure for 2700 h at 550 C, and transformation of martensite to ferrite and high density of precipitates in nearly dislocation-free matrix after sodium exposures at 650 C. Further microstructural analysis and evaluation of decarburization/carburization behavior is needed to understand the dramatic changes in the tensile strengths of advanced ferritic-martensitic and austenitic steels after sodium exposures at 650 C.

  3. Absorption of Nickel, Chromium, and Iron by the Root Surface of Primary Molars Covered with Stainless Steel Crowns

    PubMed Central

    Keinan, David; Mass, Eliyahu; Zilberman, Uri

    2010-01-01

    Objective. The purpose of this study was to analyze the absorption of metal ions released from stainless steel crowns by root surface of primary molars. Study Design. Laboratory research: The study included 34 primary molars, exfoliated or extracted during routine dental treatment. 17 molars were covered with stainless-steel crowns for more than two years and compared to 17 intact primary molars. Chemical content of the mesial or distal root surface, 1 mm apically to the crown or the cemento-enamel junction (CEJ), was analyzed. An energy dispersive X-ray spectrometer (EDS) was used for chemical analysis. Results. Higher amounts of nickel, chromium, and iron (5-6 times) were found in the cementum of molars covered with stainless-steel crowns compared to intact molars. The differences between groups were highly significant (P < .001). Significance. Stainless-steel crowns release nickel, chromium, and iron in oral environment, and the ions are absorbed by the primary molars roots. The additional burden of allergenic metals should be reduced if possible. PMID:21274429

  4. Surface Studies of Ultra Strength Drilling Steel after Corrosion Fatigue in Simulated Sour Environment

    SciTech Connect

    M. Ziomek-Moroz; J.A. Hawk; R. Thodla; F. Gui

    2012-05-06

    The Unites States predicted 60% growth in energy demand by 2030 makes oil and natural gas primary target fuels for energy generation. The fact that the peak of oil production from shallow wells (< 5000 m) is about to be reached, thereby pushing the oil and natural gas industry into deeper wells. However, drilling to depths greater than 5000 m requires increasing the strength-to weight ratio of the drill pipe materials. Grade UD-165 is one of the ultra- high yield strength carbon steels developed for ultra deep drilling (UDD) activities. Drilling UDD wells exposes the drill pipes to Cl{sup -}, HCO{sub 3}{sup -}/CO{sub 3}{sup 2-}, and H{sub 2}S-containig corrosive environments (i.e., sour environments) at higher pressures and temperatures compared to those found in conventional wells. Because of the lack of synergism within the service environment, operational stresses can result in catastrophic brittle failures characteristic for environmentally assisted cracking (EAC). Approximately 75% of all drill string failures are caused by fatigue or corrosion fatigue. Since there is no literature data on the corrosion fatigue performance of UD-165 in sour environments, research was initiated to better clarify the fatigue crack growth (FCGR) behavior of this alloy in UDD environments. The FCGR behavior of ultra-strength carbon steel, grade UD-165, was investigated by monitoring crack growth rate in deaerated 5%NaCl solution buffered with NaHCO{sub 3}/Na{sub 2}CO{sub 3} and in contact with H{sub 2}S. The partial pressure of H{sub 2}S (p{sub H2S}) was 0.83 kPa and pH of the solution was adjusted by NaOH to 12. The fatigue experiments were performed at 20 and 85 C in an autoclave with surface investigations augmented by scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectroscopy. In this study, research focused on surface analyses supported by the fatigue crack growth rate measurements. Fig. 1 shows an SEM micrograph of the crack that propagated from the

  5. The design of superhydrophobic stainless steel surfaces by controlling nanostructures: A key parameter to reduce the implantation of pathogenic bacteria.

    PubMed

    Bruzaud, Jérôme; Tarrade, Jeanne; Celia, Elena; Darmanin, Thierry; Taffin de Givenchy, Elisabeth; Guittard, Frédéric; Herry, Jean-Marie; Guilbaud, Morgan; Bellon-Fontaine, Marie-Noëlle

    2017-04-01

    Reducing bacterial adhesion on substrates is fundamental for various industries. In this work, new superhydrophobic surfaces are created by electrodeposition of hydrophobic polymers (PEDOT-F4 or PEDOT-H8) on stainless steel with controlled topographical features, especially at a nano-scale. Results show that anti-bioadhesive and anti-biofilm properties require the control of the surface topographical features, and should be associated with a low adhesion of water onto the surface (Cassie-Baxter state) with limited crevice features at the scale of bacterial cells (nano-scale structures).

  6. Observations of Surface Relief of Proeutectoid Widmanstätten Cementite Plates in a Hypereutectoid Carbon Steel

    NASA Astrophysics Data System (ADS)

    Yan, Jia-Yi; Zhang, Wen-Zheng; Borgenstam, Annika

    2013-09-01

    Proeutectoid Widmanstätten cementite in a hypereutectoid carbon steel was found to be associated with a surface relief effect. A hot-stage microscope was used for heat treatment and in situ observation. Widmanstätten cementite plates were obtained near the surface of the specimen. The surface relief effect of Widmanstätten cementite plates was quantitatively characterized by atomic force microscopy. It was found that the relief had either a typical tent shape or apex-lost tent shape. The relief tilt angles were of considerable dispersion, ranging from 20 deg to 50 deg.

  7. Microstructure and properties of borocarburized 15CrNi6 steel after laser surface modification

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Pertek, A.

    2004-09-01

    The paper presents the results of laser heat treatment (LHT) of the borided layers produced on the carburized 15CrNi6 low-carbon steel. The two-step treatment carburizing followed by boriding is termed borocarburizing. Laser tracks were arranged by CO 2 laser beam as a single track and as multiple tracks formed in the shape of helical line. The microstructure in both cases consists of the following zones: iron borides (FeB and Fe 2B) of laser modified morphology, needle-like iron borides, carburized layer with heat affected zone (martensite and alloyed cementite), carburized layer without heat treatment and the substrate (ferrite and pearlite). X-ray microanalysis of the laser modified borocarburized specimen confirmed the presence of the same two types of iron borides (FeB and Fe 2B), like those indicated in the as-borided layer. The layer after borocarburizing and LHT has a high microhardness of iron borides, reducing the hardness gradient between the diffusion layer and the substrate in comparison with only borided layer. Probably, the brittleness of this layer is lower. The improved wear resistance of this layer has been found in comparison with borided and borocarburized layers after conventional heat treatment. It is probably result of globular iron boride presence after laser surface modification.

  8. Control of cultured human cells with femtosecond laser ablated patterns on steel and plastic surfaces.

    PubMed

    Nuutinen, Tarmo; Silvennoinen, Martti; Päiväsaari, Kimmo; Vahimaa, Pasi

    2013-04-01

    The purpose of the present study is to explore topographical patterns produced with femtosecond laser pulses as a means of controlling the behaviour of living human cells (U2OS) on stainless steel surfaces and on negative plastic imprints (polycarbonate). The results show that the patterns on both types of material strongly affect cell behaviour and are particularly powerful in controlling cell spreading/elongation, localization and orientation. Analysis by fluorescence and scanning electron microscopy shows that on periodic 1D grating structures, cells and cell nuclei are highly elongated and aligned, whereas on periodic 2D grid structures, cell spreading and shape is affected. The results also show that the density and morphology of the cells can be affected. This was observed particularly on pseudo-periodic, coral-like structures which clearly inhibited cell growth. The results suggest that these patterns could be used in a variety of applications among the fields of clinical research and implant design, as well as in diagnosis and in cell and drug research. Furthermore, this article highlights the noteworthy aspects and the unique strengths of the technique and proposes directions for further research.

  9. A Stainless-Steel, Uranium-Dioxide, Potassium-Heatpipe-Cooled Surface Reactor

    SciTech Connect

    Amiri, Benjamin W.; Sims, Bryan T.; Poston, David I.; Kapernick, Richard J.

    2006-01-20

    One of the primary goals in designing a fission power system is to ensure that the system can be developed at a low cost and on an acceptable schedule without compromising reliability. The Heatpipe Power System (HPS) is one possible approach for producing near-term, low-cost, space fission power. The Heatpipe Operated Moon Exploration Reactor (HOMER-25) is a HPS designed to produce 25-kWe on the lunar surface for 5 full-power years. The HOMER-25 core is made up of 93% enriched UO2 fuel pins and stainless-steel (SS)/potassium (K) heatpipes in a SS monolith. The heatpipes transport heat generated in the core through the water shield to a potassium boiler, which drives six Stirling engines. The operating heatpipe temperature is 880 K and the peak fast fluence is 1.6e21 n/cm2, which is well within an established database for the selected materials. The HOMER-25 is designed to be buried in 1.5 m of lunar regolith during operation. By using technology and materials which do not require extensive technology development programs, the HOMER-25 could be developed at a relatively low cost. This paper describes the attributes, specifications, and performance of the HOMER-25 reactor system.

  10. Biomimetic PEG-catecholates for stabile antifouling coatings on metal surfaces: applications on TiO2 and stainless steel.

    PubMed

    Khalil, Faiza; Franzmann, Elisa; Ramcke, Julian; Dakischew, Olga; Lips, Katrin S; Reinhardt, Alexander; Heisig, Peter; Maison, Wolfgang

    2014-05-01

    Trimeric catecholates have been designed for the stable immobilization of effector molecules on metal surfaces. The design of these catecholates followed a biomimetic approach and was inspired by natural multivalent metal binders, such as mussel adhesion proteins (MAPs) and siderophores. Three catecholates have been conjugated to central scaffolds based on adamantyl or trisalkylmethyl core structures. The resulting triscatecholates have been immobilized on TiO2 and stainless steel. In a proof of concept study we have demonstrated the high stability of the resulting nanolayers at neutral and slightly acidic pH. Furthermore, polyethylene glycol (PEG) conjugates of our triscatecholates have been synthesized and were immobilized on TiO2 and stainless steel. The PEG coated surfaces showed excellent antifouling properties upon exposure to human blood and bacteria as demonstrated by fluorescence microscopy, ellipsometry and a bacterial assay with Staphylococcus epidermidis. In addition, our PEG-triscatecholates showed no cytotoxicity against bone-marrow stem cells on TiO2.

  11. Investigation of Stainless Steel Corrosion in Ultrahigh-Purity Water and Steam Systems by Surface Analytical Techniques

    NASA Astrophysics Data System (ADS)

    Dong, Xia; Iacocca, Ronald G.; Bustard, Bethany L.; Kemp, Craig A. J.

    2010-02-01

    Stainless steel pipes with different degrees of rouging and a Teflon®-coated rupture disc with severe corrosion were thoroughly investigated by combining multiple surface analytical techniques. The surface roughness and iron oxide layer thickness increase with increasing rouge severity, and the chromium oxide layer coexists with the iron oxide layer in samples with various degrees of rouging. Unlike the rouging observed for stainless steel pipes, the fast degradation of the rupture disc was caused by a crevice corrosion environment created by perforations in the protective Teflon coating. This failure analysis clearly shows the highly corrosive nature of ultrapure water used in the manufacture of pharmaceutical products, and demonstrates some of the unexpected corrosion mechanisms that can be encountered in these environments.

  12. Ionic fluids in lubrication of aluminium-steel contacts. Surface and tribochemical interactions

    NASA Astrophysics Data System (ADS)

    Jimenez Ballesta, Ana Eva

    Room-temperature ionic liquids (ILs) are high performance fluids with a wide thermal stability range. They are being studied as new lubricants in a variety of sliding contacts. One of their more interesting tribological applications is that of steel-aluminium lubrication. In this work we study the influence of the lateral alkyl chain length and of the anion on the lubricating ability of six imidazolium ILs, a pyridinium and a phosphonium derivative. For first time, these ILs have been studied as neat lubricants and as 1wt.% base oil additives in variable conditions of velocity, load and temperature in pin-on-disk tests for AISI 52100 steel-ASTM 2011 aluminium contacts. In this work we present the first study of ILs as lubricants under extreme temperature conditions. The tribological performance of ILs has been compared with that of a mineral oil and of a synthetic ester. Under these conditions, ILs show lower friction and wear values than conventional oils at all temperatures. As 1wt.% additives, the conditions of optimum lubrication and the transitions between regimes and lubrication mechanisms have been determined. We have also studied the performance of ILs as 1wt.% additives of the synthetic oil. A relationship between additive polarity and wear index has been established. If the more soluble phosphonium IL additive is used, no friction or wear reduction takes place due to competition between solvation and adsorption processes. Electronic microscopy (SEM), energy dispersive (EDS) and X-ray photoelectron (XPS) spectroscopies have been used to study the wear mechanisms and tribochemical processes that take place in the contact. Finally, we have studied the performance of three aluminium alloys in corrosion and erosion-corrosion tests. In immersion tests with free-water ILs, the aluminium alloy 2011 shows a good resistance to corrosion, but dilution of 1-ethyl, 3-methylimidazolium tetrafluoroborate in water produces the hydrolysis of the anion and the corrosion of

  13. Surface modification of functional self-assembled monolayers on 316L stainless steel via lipase catalysis.

    PubMed

    Mahapatro, Anil; Johnson, David M; Patel, Devang N; Feldman, Marc D; Ayon, Arturo A; Agrawal, C Mauli

    2006-01-31

    Lipase catalyzed esterification of therapeutic drugs to functional self-assembled monolayers (SAMs) on 316L stainless steel (SS) after assembly has been demonstrated. SAMs of 16-mercaptohexadecanoic acid (-COOH SAM) and 11-mercapto-1-undecanol (-OH SAM) were formed on 316L SS, and lipase catalysis was used to attach therapeutic drugs, perphenazine and ibuprofen, respectively, on these SAMs. The reaction was carried out in toluene at 60 degrees C for 5 h using Novozyme-435 as the biocatalyst. The FTIR spectra after surface modification of -OH SAMs showed the presence of the C=O stretching bands at 1745 cm(-1), which was absent in the FTIR spectra of -OH SAMs. Similarly, the FTIR spectra after the reaction of the -COOH SAM with perphenazine showed two peaks in the carbonyl region, a peak at 1764 cm(-1), which is the representative peak for the C=O stretching for esters. The second peak at 1681 cm(-1) is assigned to the C=O stretching of the remaining unreacted terminal COOH. XPS spectra after lipase catalysis with ibuprofen showed a photoelectron peak evolving at 288.5 eV which arises from the carbon (C=O) of the carboxylic acid of the drug (ibuprofen). Similarly for -COOH SAMs, after esterifiation we see a small, photoelectron peak evolving at 286.5 eV which corresponds to the C in the methylene groups adjacent to the oxygen (C-O), which should evolve only after the esterification of perphenazine with the -COOH SAM. Thus, lipase catalysis provides an alternate synthetic methodology for surface modification of functional SAMs after assembly.

  14. Performance Optimization of Cold Rolled Type 316L Stainless Steel by Sand Blasting and Surface Linishing Treatment

    NASA Astrophysics Data System (ADS)

    Krawczyk, B.; Heine, B.; Engelberg, D. L.

    2016-03-01

    Sand blasting followed by a surface linishing treatment was applied to optimize the near-surface microstructure of cold rolled type 316L stainless steel. The introduction of cold rolling led to the formation of α-martensite. Specimens with large thickness reductions (40, 53%) were more susceptible to localized corrosion. The application of sand blasting produced a near-surface deformation layer containing compressive residual stresses with significantly increased surface roughness, resulting in reduced corrosion resistance. The most resistant microstructure was obtained with the application of a final linishing treatment after sand blasting. This treatment produced microstructures with compressive near-surface residual stresses, reduced surface roughness, and increased resistance to localized corrosion.

  15. Effect of laser-remelting of surface cracks on microstructure and residual stresses in 12Ni maraging steel

    NASA Astrophysics Data System (ADS)

    Grum, J.; Slabe, J. M.

    2006-04-01

    The paper presents the results of a study on possible application of laser-remelting to repair of narrow and comparatively deep cracks at the surface of highly thermo-mechanically loaded parts made of 12% Ni hot-working maraging tool steel. Laser-remelting of maraging steel is, due to very good weldability and flexibility of the process, very prospective for repair of fatigued surfaces of parts made of this steel at which the presence of surface microcracks may be observed. In addition to the efficiency of crack remelting, the influence of laser-remelting on the heat-affected zone in terms of its microstructure and residual stresses was also studied. The microstructure in the laser-remelted track is cellular/dendritic. In the heat-affected zone surrounding the laser-remelted track, the microstructure varies considerably. A microstructure analysis revealed, in the heat-affected zone, five microstructural zones and sub-zones. Residual stresses measured after laser-remelting are with reference to gradual through-depth changing of the stresses favourable.

  16. Effect of Carbon Distribution During the Microstructure Evolution of Dual-Phase Steels Studied Using Cellular Automata, Genetic Algorithms, and Experimental Strategies

    NASA Astrophysics Data System (ADS)

    Halder, Chandan; Karmakar, Anish; Hasan, Sk. Md.; Chakrabarti, Debalay; Pietrzyk, Maciej; Chakraborti, Nirupam

    2016-12-01

    The development of ferrite-martensite dual-phase microstructures by cold-rolling and intercritical annealing of 0.06 wt pct carbon steel was systematically studied using a dilatometer for two different heating rates (1 and 10 K/s). A step quenching treatment has been designed to develop dual-phase structures having a similar martensite fraction for two different heating rates. An increase in heating rate seemed to refine the ferrite grain size, but it increased the size and spacing of the martensitic regions. As a result, the strength of the steel increased with heating rate; however, the formability was affected. It has been concluded that the distribution of C during the annealing treatment of cold-rolled steel determines the size, distribution, and morphology of martensite, which ultimately influences the mechanical properties. Experimental detection of carbon distribution in austenite is difficult during annealing of the cold-rolled steel as the phase transformation occurs at a high temperature and C is an interstitial solute, which diffuses fast at that temperature. Therefore, a cellular automata (CA)-based phase transformation model is proposed in the present study for the prediction of C distribution in austenite during annealing of steel as the function of C content and heating rate. The CA model predicts that the carbon distribution in austenite becomes more inhomogeneous when the heating rate increases. In the CA model, the extent of carbon inhomogeneity is measured using a kernel averaging method for different orders of neighbors, which accounts for the different physical space during calculation. The obtained results reveal that the 10th order (covering 10- µm physical spaces around the cell of interest) is showing the maximum inhomogeneity of carbon and the same effect has been investigated and confirmed using auger electron spectroscopy (AES) for 0.06 wt pct carbon steel. Furthermore, the optimization of carbon homogeneity with respect to heating

  17. In Situ Surface Studies Of Conversion Coatings For Steel And Aluminum

    DTIC Science & Technology

    1992-11-10

    functional electrolyte groups such as carboxylic acid (-COOH) and sulfonic acid (-S03H). Sugama et al.1413 found poly(acrylic acid ), herein referred to as PAA... acid (PAA) complexed zinc phosphate conversion coatings on steel. Atomic force microscopy (AFM) using tunnel current control was developed and applied...Microscopy Studies of Zinc Phosphate and Polyacrylic Acid Complexed Zinc Phosphate Conversion Coatings on Steel 11 1. Background 12 2. Samples 12 3

  18. Surface metallurgical and tribological characteristics of TiN-coated bearing steels

    NASA Technical Reports Server (NTRS)

    Erdemir, A.; Hochman, R. F.

    1988-01-01

    The rolling contact fatigue (RCF) characteristics of an aerospace bearing steel 440C coated with TiN films of various thicknesses are studied. The wear and corrosion properties of the film-substrate system are examined as well as how these properties correlate with the RCF behavior. It is found that TiN coatings with thicknesses below 1 micron resulted in significant improvements in the RCF lives of base steel substrates under both mild and heavy loading conditions.

  19. Microbiota formed on attached stainless steel coupons correlates with the natural biofilm of the sink surface in domestic kitchens.

    PubMed

    Moen, Birgitte; Røssvoll, Elin; Måge, Ingrid; Møretrø, Trond; Langsrud, Solveig

    2016-02-01

    Stainless steel coupons are frequently used in biofilm studies in the laboratory, as this material is commonly used in the food industry. The coupons are attached to different surfaces to create a "natural" biofilm to be studied further in laboratory trials. However, little has been done to investigate how well the microbiota on such coupons represents the surrounding environment. The microbiota on sink wall surfaces and on new stainless steel coupons attached to the sink wall for 3 months in 8 domestic kitchen sinks was investigated by next-generation sequencing (MiSeq) of the 16S rRNA gene derived from DNA and RNA (cDNA), and by plating and identification of colonies. The mean number of colony-forming units was about 10-fold higher for coupons than sink surfaces, and more variation in bacterial counts between kitchens was seen on sink surfaces than coupons. The microbiota in the majority of biofilms was dominated by Moraxellaceae (genus Moraxella/Enhydrobacter) and Micrococcaceae (genus Kocuria). The results demonstrated that the variation in the microbiota was mainly due to differences between kitchens (38.2%), followed by the different nucleic acid template (DNA vs RNA) (10.8%), and that only 5.1% of the variation was a result of differences between coupons and sink surfaces. The microbiota variation between sink surfaces and coupons was smaller for samples based on the