Sample records for t91 grade steels

  1. Long-term strength and allowable stresses of grade 10Kh9MFB and X10CrMoVNb9-1 (T91/P91) chromium heat-resistant steels

    NASA Astrophysics Data System (ADS)

    Skorobogatykh, V. N.; Danyushevskiy, I. A.; Schenkova, I. A.; Prudnikov, D. A.

    2015-04-01

    Currently, grade X10CrMoVNb9-1 (T91, P91) and 10Kh9MFB (10Kh9MFB-Sh) chromium steels are widely applied in equipment manufacturing for thermal power plants in Russia and abroad. Compilation and comparison of tensile, impact, and long-term strength tests results accumulated for many years of investigations of foreign grade X10CrMoVNb9-1, T91, P91, and domestic grade 10Kh9MFB (10Kh9MFB-Sh) steels is carried out. The property identity of metals investigated is established. High strength and plastic properties of steels, from which pipes and other products are made, for operation under creep conditions are confirmed. Design characteristics of long-term strength on the basis of tests with more than one million of hour-samples are determined ( and at temperatures of 500-650°C). The table of recommended allowable stresses for grade 10Kh9MFB, 10Kh9MFB-SH, X10CrMoVNb9-1, T91, and P91 steels is developed. The long-time properties of pipe welded joints of grade 10Kh9MFB+10Kh9MFB, 10Kh9MFB-Sh+10Kh9MFB-Sh, X10CrMoVNb9-1+X10CrMoVNb9-1, P91+P91, T91+T91, 10Kh9MFB (10Kh9MFB-Sh)+X10CrMoVNb9-1(T/P91) steels is researched. The welded joint reduction factor is experimentally determined.

  2. High-temperature creep properties and life predictions for T91 and T92 steels

    NASA Astrophysics Data System (ADS)

    Pan, J. P.; Tu, S. H.; Sun, G. L.; Zhu, X. W.; Tan, L. J.; Hu, B.

    2018-01-01

    9-11%Cr heat-resistant steels are widely used in high-temperature and high-pressure boilers of advanced power plants. In the current paper, high-temperature creep behaviors of T91 and T92 steels have been investigated. Creep tests were performed for both steels at varied temperatures. The creep mechanisms of T91 and T92 steels were elucidated by analyzing the creep rupture data of the two steels. In addition, Manson-Haferd model was employed to predict the creep life of T91 and T92 steels, the results of which indicate that the Manson-Haferd model works well for the two steels.

  3. Estimation of the aging grade of T91 steel by laser-induced breakdown spectroscopy coupled with support vector machines

    NASA Astrophysics Data System (ADS)

    Lu, Shengzi; Dong, Meirong; Huang, Jianwei; Li, Wenbing; Lu, Jidong; Li, Jun

    2018-02-01

    T91 steel is a representative martensitic heat-resistant steel widely used in high temperature compression components of industrial equipment. During the service period, the operation safety and the service life of the equipment will be affected by the change of structure and mechanical properties of the steel components, which is called material aging. In order to develop a rapid in-situ aging estimation technology of high temperature compression components surface, laser-induced breakdown spectroscopy (LIBS) coupled with support vector machine (SVM) was employed in this paper. The spectral characteristics of 10 T91 steel specimens with different aging grades were analyzed. Line intensities and the line intensity ratios (ionic/atomic and alloying element/matrix element) that indicate the change of metallographic structure were used to establish SVM models, and the results using different variable sets were compared. The model was optimized by comparing different pulse number for practical effectiveness, and the robustness of the model was investigated in dealing with the inhomogeneity of steel composition. The study results show that the estimation model obtained the best performance using line intensities and line intensity ratios averaged from 31st-60th laser pulses as input variables. The estimation accuracy of validation set was greatly improved from 75.8% to 95.3%. In addition, the model showed the outstanding capacity for handling the fluctuations of spectral signals between measuring-points (spots), which indicated that the aging estimation based on a few measuring-points is feasible. The studies presented here demonstrate that the LIBS coupled with SVM is a new useful technique for the aging estimation of steel, and would be well-suited for fast safety assessment in industrial field.

  4. Creep behavior of Grade 91 steel under uniaxial and multiaxial state of stress

    NASA Astrophysics Data System (ADS)

    Ren, Facai; Tang, Xiaoying

    2017-09-01

    Creep rupture behavior of Grade 91 heat-resistant steel used for steam cooler under uniaxial and multiaxial state of stress was investigated. Creep tests were conducted at the temperature of 923K under the stress 125MPa. The notch root radii (r) of doubled circumferentially U-notched specimens were 0.6 and 6 mm. The creep rupture life of Grade 91 steel was found to increase with the increasing of notch acuity ratio. The creep rupture mechanism was investigated based on the SEM fractography analysis.

  5. Heat Transfer Analysis of Localized Heat-Treatment for Grade 91 Steel

    NASA Astrophysics Data System (ADS)

    Walker, Jacob D.

    Many of the projects utilizing Grade 91 steel are large in scale, therefore it is necessary to assemble on site. The assembly of the major pieces requires welding in the assembly; this drastically changes the superior mechanical properties of Grade 91 steel that it was specifically developed for. Therefore, because of the adverse effects of welding on the mechanical properties of Grade 91, it is necessary to do a localized post weld heat treatment. As with most metallic materials grade 91 steel requires a very specific heat treatment process. This process includes a specific temperature and duration at that temperature to achieve the heat treatment desired. Extensive research has been done to determine the proper temperatures and duration to provide the proper microstructure for the superior mechanical properties that are inherent to Grade 91 steel. The welded sections are typically large structures that require local heat treatments and cannot be placed in an oven. The locations of these structures vary from indoors in a controlled environment to outdoors with unpredictable environments. These environments can be controlled somewhat, however in large part the surrounding conditions are unchangeable. Therefore, there is a need to develop methods to accurately apply the surrounding conditions and geometries to a theoretical model in order to provide the proper requirements for the local heat treatment procedure. Within this requirement is the requirement to define unknowns used in the heat transfer equations so that accurate models can be produced and accurate results predicted. This study investigates experimentally and numerically the heat transfer and temperature fields of Grade 91 piping in a local heat treatment. The objective of this thesis research is to determine all of the needed heat transfer coefficients. The appropriate heat transfer coefficients are determined through the inverse heat conduction method utilizing a ceramic heat blanket. This will be done

  6. Creep, creep-rupture tests of Al-surface-alloyed T91 steel in liquid lead bismuth at 500 and 550 °C

    NASA Astrophysics Data System (ADS)

    Weisenburger, A.; Jianu, A.; An, W.; Fetzer, R.; Del Giacco, Mattia; Heinzel, A.; Müller, G.; Markov, V. G.; Kasthanov, A. D.

    2012-12-01

    Surface layers made of FeCrAl alloys on T91 steel have shown their capability as corrosion protection barriers in lead bismuth. Pulsed electron beam treatment improves the density and more over the adherence of such layers. After the treatment of previously deposited coatings a surface graded material is achieved with a metallic bonded interface. Creep-rupture tests of T91 in lead-alloy at 550 °C reveal significant reduced creep strength of non-modified T91 test specimens. Oxide scales protecting the steels from attacks of the liquid metal will crack at a certain strain leading to a direct contact between the steel and the liquid metal. The negative influence of the lead-alloy on the creep behavior of non-modified T91 is stress dependent, but below a threshold stress value of 120 MPa at 550 °C this influence becomes almost negligible. At 500 °C and stress values of 200 MPa and 220 MPa the creep rates are comparable between them and significantly lower than creep rates at 180 MPa of original T91 in air at 550 °C. No signs of LBE influence are detected. The surface modified specimens tested at high stress levels instead had creep-rupture times similar to T91 (original state) tested in air. The thin oxide layers formed on the surface modified steel samples are less susceptible to crack formation and therefore to lead-alloy enhanced creep.

  7. Characterization of films formed by the aluminizing of T91 steel

    NASA Astrophysics Data System (ADS)

    Sanabria Cala, J. A.; Conde Rodríguez, G. R.; Y Peña Ballesteros, D.; Laverde Cataño, D.; Quintero Rangel, L. S.

    2017-12-01

    The aluminizing of a T91 martensitic ferritic steel was carried out by a novel modification to the traditional technique of packed cementation, with the objective of producing a diffusion coating of aluminum in a shorter time and operating cost, from a technique that allows the reuse of powder packaging and which the coating of metal parts with complex shapes can be secured. As an aluminum source, commercial foil is used to wrap the piece to be coated, while the powder packaging contains aluminum oxide Al2O3 and an activating salt, ammonium chloride NH4Cl. During the deposition process of the coating, the NH4Cl is decomposed by reacting with foil, and thus, aluminum halides can be transferred to the metallic substrate, which deposit aluminum on the T91 steel surface while Al2O3 can be recycled for subsequent processes. The results of the diffractograms and micrographs indicated the strong influence of temperature, exposure time and ammonium chloride concentration in the formation and growth evolution of a stable coating of iron-aluminum and iron-aluminum-nickel on the T91 steel surface, which was effectively deposited at a temperature of 700°C and an exposure period of 9 hours. The coating formed on the T91 steel surface could play a protective role towards the material by acting as a physical barrier between the alloy and other corrosive species in high temperature operated systems.

  8. Effects of the Tempering and High-Pressure Torsion Temperatures on Microstructure of Ferritic/Martensitic Steel Grade 91

    PubMed Central

    Ganeev, Artur; Nikitina, Marina; Sitdikov, Vil; Islamgaliev, Rinat; Hoffman, Andrew; Wen, Haiming

    2018-01-01

    Grade 91 (9Cr-1Mo) steel was subjected to various heat treatments and then to high-pressure torsion (HPT) at different temperatures. Its microstructure was studied using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Effects of the tempering temperature and the HPT temperature on the microstructural features and microhardness in the ultrafine-grained (UFG) Grade 91 steel were researched. The study of the UFG structure formation takes into account two different microstructures observed: before HPT in both samples containing martensite and in fully ferritic samples. PMID:29671761

  9. Creep Deformation, Rupture Analysis, Heat Treatment and Residual Stress Measurement of Monolithic and Welded Grade 91 Steel for Power Plant Components

    NASA Astrophysics Data System (ADS)

    Shrestha, Triratna

    Modified 9Cr-1 Mo (Grade 91) steel is currently considered as a candidate material for reactor pressure vessels (RPVs) and reactor internals for the Very High Temperature Reactor (VHTR), and in fossil-fuel fired power plants at higher temperatures and stresses. The tensile creep behavior of Grade 91 steel was studied in the temperature range of 600°C to 750°C and stresses between 35 MPa and 350 MPa. Heat treatment of Grade 91 steel was studied by normalizing and tempering the steel at various temperatures and times. Moreover, Thermo-Ca1c(TM) calculation was used to predict the precipitate stability and their evolution, and construct carbon isopleths of Grade 91 steel. Residual stress distribution across gas tungsten arc welds (GTAW) in Grade 91 steel was measured by the time-of-flight neutron diffraction using the Spectrometer for Materials Research at Temperature and Stress (SMARTS) diffractometer at Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, NM, USA. Analysis of creep results yielded stress exponents of ˜9-11 in the higher stress regime and ˜1 in the lower stress regime. The creep behavior of Grade 91 steel was described by the modified Bird-Mukherjee-Dorn relation. The rate-controlling creep deformation mechanism in the high stress regime was identified as the edge dislocation climb with a stress exponent of n = 5. On the other hand, the deformation mechanism in the Newtonian viscous creep regime (n = 1) was identified as the Nabarro-Herring creep. Creep rupture data were analyzed in terms of Monkman-Grant relation and Larson-Miller parameter. Creep damage tolerance factor and stress exponent were used to identify the cause of creep damage. The fracture surface morphology of the ruptured specimens was studied by scanning electron microscopy to elucidate the failure mechanisms. Fracture mechanism map for Grade 91 steel was developed based on the available material parameters and experimental observations. The microstructural

  10. Creep Tests and Modeling Based on Continuum Damage Mechanics for T91 and T92 Steels

    NASA Astrophysics Data System (ADS)

    Pan, J. P.; Tu, S. H.; Zhu, X. W.; Tan, L. J.; Hu, B.; Wang, Q.

    2017-12-01

    9-11%Cr ferritic steels play an important role in high-temperature and high-pressure boilers of advanced power plants. In this paper, a continuum damage mechanics (CDM)-based creep model was proposed to study the creep behavior of T91 and T92 steels at high temperatures. Long-time creep tests were performed for both steels under different conditions. The creep rupture data and creep curves obtained from creep tests were captured well by theoretical calculation based on the CDM model over a long creep time. It is shown that the developed model is able to predict creep data for the two ferritic steels accurately up to tens of thousands of hours.

  11. Effect of heat treatment on microstructure and hardness of Grade 91 steel

    DOE PAGES

    Shrestha, Triratna; Alsagabi, Sultan; Charit, Indrajit; ...

    2015-01-21

    The modified 9Cr-1Mo steel (Grade 91) is a material of choice in fossil-fuel-fired power plants with increased efficiency, service life, and reduction in emission of greenhouse gases. It is also considered a prospective material for the Next Generation Nuclear Power Plant for application in reactor pressure vessels at temperatures up to 650°C. In this paper, heat treatment of the modified 9Cr-1Mo steel was studied by normalizing and tempering the steel at various temperatures and times, with the ultimate goal of improving its creep resistance and optimizing material hardness. The microstructural evolution of the heat treated steels was correlated with themore » differential scanning calorimetric results. Optical microscopy, scanning and transmission electron microscopy in conjunction with microhardness profiles and calorimetric plots were used to understand the evolution of microstructure including precipitate structures in modified 9Cr-1Mo steel and relate it to the mechanical behavior of the steel. Thermo-CalcTM calculations were used to support experimental work and provide guidance in terms of the precipitate stability and microstructural evolution. Furthermore, the carbon isopleth and temperature dependencies of the volume fraction of different precipitates were constructed. The predicted and experimentally observed results were found to be in good agreement.« less

  12. Creep Rupture of the Simulated HAZ of T92 Steel Compared to that of a T91 Steel.

    PubMed

    Peng, Yu-Quan; Chen, Tai-Cheng; Chung, Tien-Jung; Jeng, Sheng-Long; Huang, Rong-Tan; Tsay, Leu-Wen

    2017-02-08

    The increased thermal efficiency of fossil power plants calls for the development of advanced creep-resistant alloy steels like T92. In this study, microstructures found in the heat-affected zone (HAZ) of a T92 steel weld were simulated to evaluate their creep-rupture-life at elevated temperatures. An infrared heating system was used to heat the samples to 860 °C (around A C1 ), 900 °C (slightly below A C3 ), and 940 °C (moderately above A C3 ) for one minute, before cooling to room temperature. The simulated specimens were then subjected to a conventional post-weld heat treatment (PWHT) at 750 °C for two hours, where both the 900 °C and 940 °C simulated specimens had fine grain sizes. In the as-treated condition, the 900 °C simulated specimen consisted of fine lath martensite, ferrite subgrains, and undissolved carbides, while residual carbides and fresh martensite were found in the 940 °C simulated specimen. The results of short-term creep tests indicated that the creep resistance of the 900 °C and 940 °C simulated specimens was poorer than that of the 860 °C simulated specimens and the base metal. Moreover, simulated T92 steel samples had higher creep strength than the T91 counterpart specimens.

  13. Creep Rupture of the Simulated HAZ of T92 Steel Compared to that of a T91 Steel

    PubMed Central

    Peng, Yu-Quan; Chen, Tai-Cheng; Chung, Tien-Jung; Jeng, Sheng-Long; Huang, Rong-Tan; Tsay, Leu-Wen

    2017-01-01

    The increased thermal efficiency of fossil power plants calls for the development of advanced creep-resistant alloy steels like T92. In this study, microstructures found in the heat-affected zone (HAZ) of a T92 steel weld were simulated to evaluate their creep-rupture-life at elevated temperatures. An infrared heating system was used to heat the samples to 860 °C (around AC1), 900 °C (slightly below AC3), and 940 °C (moderately above AC3) for one minute, before cooling to room temperature. The simulated specimens were then subjected to a conventional post-weld heat treatment (PWHT) at 750 °C for two hours, where both the 900 °C and 940 °C simulated specimens had fine grain sizes. In the as-treated condition, the 900 °C simulated specimen consisted of fine lath martensite, ferrite subgrains, and undissolved carbides, while residual carbides and fresh martensite were found in the 940 °C simulated specimen. The results of short-term creep tests indicated that the creep resistance of the 900 °C and 940 °C simulated specimens was poorer than that of the 860 °C simulated specimens and the base metal. Moreover, simulated T92 steel samples had higher creep strength than the T91 counterpart specimens. PMID:28772500

  14. Study on creep behavior of Grade 91 heat-resistant steel using theta projection method

    NASA Astrophysics Data System (ADS)

    Ren, Facai; Tang, Xiaoying

    2017-10-01

    Creep behavior of Grade 91 heat-resistant steel used for steam cooler was characterized using the theta projection method. Creep tests were conducted at the temperature of 923K under the stress ranging from 100-150MPa. Based on the creep curve results, four theta parameters were established using a nonlinear least square fitting method. Four theta parameters showed a good linearity as a function of stress. The predicted curves coincided well with the experimental data and creep curves were also modeled to the low stress level of 60MPa.

  15. FY17 Status Report on the Micromechanical Finite Element Modeling of Creep Fracture of Grade 91 Steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Messner, M. C.; Truster, T. J.; Cochran, K. B.

    Advanced reactors designed to operate at higher temperatures than current light water reactors require structural materials with high creep strength and creep-fatigue resistance to achieve long design lives. Grade 91 is a ferritic/martensitic steel designed for long creep life at elevated temperatures. It has been selected as a candidate material for sodium fast reactor intermediate heat exchangers and other advanced reactor structural components. This report focuses on the creep deformation and rupture life of Grade 91 steel. The time required to complete an experiment limits the availability of long-life creep data for Grade 91 and other structural materials. Design methodsmore » often extrapolate the available shorter-term experimental data to longer design lives. However, extrapolation methods tacitly assume the underlying material mechanisms causing creep for long-life/low-stress conditions are the same as the mechanisms controlling creep in the short-life/high-stress experiments. A change in mechanism for long-term creep could cause design methods based on extrapolation to be non-conservative. The goal for physically-based microstructural models is to accurately predict material response in experimentally-inaccessible regions of design space. An accurate physically-based model for creep represents all the material mechanisms that contribute to creep deformation and damage and predicts the relative influence of each mechanism, which changes with loading conditions. Ideally, the individual mechanism models adhere to the material physics and not an empirical calibration to experimental data and so the model remains predictive for a wider range of loading conditions. This report describes such a physically-based microstructural model for Grade 91 at 600° C. The model explicitly represents competing dislocation and diffusional mechanisms in both the grain bulk and grain boundaries. The model accurately recovers the available experimental creep curves at higher

  16. FY17 Status Report on the Initial Development of a Constitutive Model for Grade 91 Steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Messner, M. C.; Phan, V. -T.; Sham, T. -L.

    Grade 91 is a candidate structural material for high temperature advanced reactor applications. Existing ASME Section III, Subsection HB, Subpart B simplified design rules based on elastic analysis are setup as conservative screening tools with the intent to supplement these screening rules with full inelastic analysis when required. The Code provides general guidelines for suitable inelastic models but does not provide constitutive model implementations. This report describes the development of an inelastic constitutive model for Gr. 91 steel aimed at fulfilling the ASME Code requirements and being included into a new Section III Code appendix, HBB-Z. A large database ofmore » over 300 experiments on Gr. 91 was collected and converted to a standard XML form. Five families of Gr. 91 material models were identified in the literature. Of these five, two are potentially suitable for use in the ASME code. These two models were implemented and evaluated against the experimental database. Both models have deficiencies so the report develops a framework for developing and calibrating an improved model. This required creating a new modeling method for representing changes in material rate sensitivity across the full ASME allowable temperature range for Gr. 91 structural components: room temperature to 650° C. On top of this framework for rate sensitivity the report describes calibrating a model for work hardening and softening in the material using genetic algorithm optimization. Future work will focus on improving this trial model by including tension/compression asymmetry observed in experiments and necessary to capture material ratcheting under zero mean stress and by improving the optimization and analysis framework.« less

  17. Elevated Temperature Corrosion Studies of AlCrN and TiAlN Coatings by PAPVD on T91 Boiler Steel

    NASA Astrophysics Data System (ADS)

    Goyal, Lucky; Chawla, Vikas; Hundal, Jasbir Singh

    2017-11-01

    The present investigation discusses the hot corrosion behavior of AlCrN and TiAlN nano-coatings on T91 boiler steel by PAPVD process subjected to molten salt of Na2SO4-60%V2O5 at 900 °C for 50 cycles. Surface and cross-sectional studies were performed by AFM, SEM/EDS and XRD techniques to understand the corrosion kinetics and mechanism. T91 bare boiler steel as well as TiAlN-coated specimen has shown higher internal oxidation as well as weight gain. The better corrosion resistance of AlCrN-coated specimen has been observed by virtue of higher availability of Cr and Al in the oxide scale as well as adherent and dense coating. The betterment of AlCrN coating can be attributed to low internal oxidation as well as movement of Cr and Al toward oxide scale to form protective corrosion barriers.

  18. FY17 Status Report on the Initial EPP Finite Element Analysis of Grade 91 Steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Messner, M. C.; Sham, T. -L.

    This report describes a modification to the elastic-perfectly plastic (EPP) strain limits design method to account for cyclic softening in Gr. 91 steel. The report demonstrates that the unmodified EPP strain limits method described in current ASME code case is not conservative for materials with substantial cyclic softening behavior like Gr. 91 steel. However, the EPP strain limits method can be modified to be conservative for softening materials by using softened isochronous stress-strain curves in place of the standard curves developed from unsoftened creep experiments. The report provides softened curves derived from inelastic material simulations and factors describing the transformationmore » of unsoftened curves to a softened state. Furthermore, the report outlines a method for deriving these factors directly from creep/fatigue tests. If the material softening saturates the proposed EPP strain limits method can be further simplified, providing a methodology based on temperature-dependent softening factors that could be implemented in an ASME code case allowing the use of the EPP strain limits method with Gr. 91. Finally, the report demonstrates the conservatism of the modified method when applied to inelastic simulation results and two bar experiments.« less

  19. High-Temperature Behavior of a NiCr-Coated T91 Boiler Steel in the Platen Superheater of Coal-Fired Boiler

    NASA Astrophysics Data System (ADS)

    Chatha, Sukhpal Singh; Sidhu, Hazoor S.; Sidhu, Buta S.

    2013-06-01

    Ni-20Cr coating was deposited on T91 boiler tube steel by high-velocity oxy-fuel (HVOF) process to enhance high-temperature oxidation resistance. High-temperature performance of bare, as well as HVOF-coated steel specimens was evaluated for 1500 h under in the platen superheater zone of coal-fired boiler, where the temperature was around 900 °C. Experiments were carried out for 15 cycles, each of 100-h duration followed by 1-h cooling at ambient temperature. The extent of degradation of the specimens was assessed by the thickness loss and depth of internal corrosion attack. Ni-20Cr-coated steel performed better than the uncoated steel in actual boiler environment. The improved degradation resistance of Ni-20Cr coating can be attributed to the presence of Cr2O3 in the top oxide scale and dense microstructure.

  20. Ion-irradiation-induced microstructural modifications in ferritic/martensitic steel T91

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Xiang; Miao, Yinbin; Li, Meimei

    In this paper, in situ transmission electron microscopy investigations were carried out to study the microstructural evolution of ferritic/martensitic steel T91 under 1 MeV Krypton ion irradiation up to 4.2 x 10(15) ions/cm(2) at 573 K, 673 K, and 773 K. At 573 K, grown-in defects are strongly modified by black dot loops, and dislocation networks together with black-dot loops were observed after irradiation. At 673 K and 773 K, grown-in defects are only partially modified by dislocation loops; isolated loops and dislocation segments were commonly found after irradiation. Post irradiation examination indicates that at 4.2 x 1015 ions/cm(2), aboutmore » 51% of the loops were a(0)/2 < 111 > type for the 673 K irradiation, and the dominant loop type was a(0)< 100 > for the 773 K irradiation. Finally, a dispersed barrier hardening model was employed to estimate the change in yield strength, and the calculated ion data were found to follow the similar trend as the existing neutron data with an offset of 100-150 MPa. (C) 2017 Elsevier B.V. All rights reserved.« less

  1. Microstructural evolution of neutron-irradiated T91 and NF616 to ~4.3 dpa at 469 °C

    DOE PAGES

    Tan, Lizhen; Kim, B. K.; Yang, Ying; ...

    2017-05-30

    Ferritic-martensitic steels such as T91 and NF616 are candidate materials for several nuclear applications. Here, this study evaluates radiation resistance of T91 and NF616 by examining their microstructural evolutions and hardening after the samples were irradiated in the Advanced Test Reactor to ~4.3 displacements per atom (dpa) at an as-run temperature of 469 °C. In general, this irradiation did not result in significant difference in the radiation-induced microstructures between the two steels. Compared to NF616, T91 had a higher number density of dislocation loops and a lower level of radiation-induced segregation, together with a slightly higher radiation-hardening. Unlike dislocation loopsmore » developed in both steels, radiation-induced cavities were only observed in T91 but remained small with sub-10 nm sizes. Lastly, other than the relatively stable M 23C 6, a new phase (likely Sigma phase) was observed in T91 and radiation-enhanced MX → Z phase transformation was identified in NF616. Laves phase was not observed in the samples.« less

  2. Liquid metal embrittlement of T91 and 316L steels by heavy liquid metals: A fracture mechanics assessment

    NASA Astrophysics Data System (ADS)

    Auger, T.; Hamouche, Z.; Medina-Almazàn, L.; Gorse, D.

    2008-06-01

    LME of the martensitic T91 and the austenitic 316L steels have been investigated in the CCT geometry in the plane-stress condition. Using such a geometry, premature cracking induced by a liquid metal (PbBi and Hg) can be studied using a fracture mechanics approach based on CTOD, J-Δ a and fracture assessment diagram. One is able to measure a reduction of the crack tip blunting and a reduction of the energy required for crack propagation induced by the liquid metal. In spite of some limitations, this qualitative evaluation shows that liquid metals do not induce strong embrittlement on steels in plane-stress condition. Rather, the effect of the liquid metal seems to promote a fracture mode by plastic collapse linked with strain localization. It indicates that the materials, in spite of a potential embrittlement, should still be acceptable in terms of safety criteria.

  3. Alloy Design of Martensitic 9Cr-Boron Steel for A-USC Boiler at 650 °C — Beyond Grades 91, 92 and 122

    NASA Astrophysics Data System (ADS)

    Abe, Fujio; Tabuchi, M.; Tsukamoto, S.

    Boundary hardening is shown to be the most important strengthening mechanism in creep of tempered martensitic 9% Cr steel base metal and welded joints at 650 °C. The enrichment of soluble boron near prior austenite grain boundaries (PAGBs) by the GB segregation is essential for the reduction of coarsening rate of M23C6 carbides near PAGBs, enhancing the boundary and sub-boundary hardening near PAGBs, and also for the change in α/γ transformation behavior in heat-affected-zone (HAZ) of welded joints during heating of welding, producing the same microstructure in HAZ as in the base metal. Excess addition of nitrogen to the 9Cr-boron steel promotes the formation of boron nitrides during normalizing heat treatment, which consumes most of soluble boron and degrades the creep strength. A NIMS 9Cr steel (MARBN; Martensitic 9Cr steel strengthened by boron and MX nitrides) with 120-150 ppm boron and 60-90 ppm nitrogen, where no boron nitride forms during normalizing heat treatment, exhibits not only much higher creep strength of base metal than Grades 91, 92 and 122 but also substantially no degradation in creep strength due to Type IV fracture in HAZ of welded joints at 650°C. The protective Cr2O3-rich scale forms on the surface of 9Cr steel by pre-oxidation treatment in Ar gas, which significantly improves the oxidation resistance in steam at 650°C.

  4. Identification and Characterization of Intercritical Heat-Affected Zone in As-Welded Grade 91 Weldment

    NASA Astrophysics Data System (ADS)

    Wang, Yiyu; Kannan, Rangasayee; Li, Leijun

    2016-12-01

    A metallurgical method is proposed for locating the intercritical heat-affected zone in the as-welded Grade 91 steel. New austenitic grains, preferentially formed along the original prior austenite grain boundaries, are characterized to contain finer M23C6 carbides and higher strain levels than the original prior austenite grains. Kurdjumov-Sachs Group 1 variant pairs, with a low misorientation of 7 deg within a martensitic block, are identified as the dominant variants in the new PAGs.

  5. Study on service performance of 880 MPa-grade and 980 MPa-grade rail steels

    NASA Astrophysics Data System (ADS)

    Zhu, M.; Xu, G.; Zhou, J. H.; Wang, R. M.; Gan, X. L.

    2017-09-01

    With the rapid development of economy in China, the requirement for railway passenger and cargo transportation becomes higher and higher. Increasing speed and developing heavy-haul transportation can effectively improve the transportation capacity of railway. The requirement for rail steels with higher ability of abrasion resistance becomes urgent. Two kinds of rails, i.e., 880 MPa-grade and 980 MPa-grade rail steels, were laid on cargo line with 500 m short radius curve. The service performances of the tested steels were continuously tracked and analyzed during operation of total 22.5 million tons loads. Macro morphology, light band width, surface hardness and profile of rails were investigated. The results show that the performance of 980 MPa-grade rail steel is superior to that of 880 MPa-grade rail steel at same circumstance. Therefore, 980 MPa-grade rail should be selected in the cargo line with small radius curve.

  6. Characterization of corrosion phenomena and kinetics on T91 ferritic/martensitic steel exposed at 450 and 550 °C to flowing Pb-Bi eutectic with 10-7 mass% dissolved oxygen

    NASA Astrophysics Data System (ADS)

    Tsisar, Valentyn; Schroer, Carsten; Wedemeyer, Olaf; Skrypnik, Aleksandr; Konys, Jürgen

    2017-10-01

    Corrosion behavior of two heats of T91 ferritic/martensitic steel, with slightly different Cr content, was investigated in flowing (2 m/s) Pb-Bi with 10-7 mass%O at 450 and 550 °C. The observed corrosion modes are: protective scale formation; accelerated oxidation and solution-based corrosion attack. Accelerated oxidation at 450 °C results in general metal recession of about 10 μm after ∼9000 h exposure and ∼15 μm at 550 °C after 2000 h. More severe and local solution-based corrosion results in a maximum depth of attack of 50-960 μm and 115-190 μm, correspondingly. Incubation period for solution-based corrosion is 500-5000 h at 450 °C and ≤500 h at 550 °C. The slightly higher chromium content in one of the heat of T91 steel prolongs the incubation period by improving the stability of the Cr-based oxide film.

  7. 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

  8. Correlation Between Intercritical Heat-Affected Zone and Type IV Creep Damage Zone in Grade 91 Steel

    NASA Astrophysics Data System (ADS)

    Wang, Yiyu; Kannan, Rangasayee; Li, Leijun

    2018-04-01

    A soft zone in Cr-Mo steel weldments has been reported to accompany the infamous Type IV cracking, the highly localized creep damage in the heat-affected zone of creep-resistant steels. However, the microstructural features and formation mechanism of this soft zone are not well understood. In this study, using microhardness profiling and microstructural verification, the initial soft zone in the as-welded condition was identified to be located in the intercritical heat-affected zone of P91 steel weldments. It has a mixed structure, consisting of Cr-rich re-austenitized prior austenite grains and fine Cr-depleted, tempered martensite grains retained from the base metal. The presence of these further-tempered retained grains, originating from the base metal, is directly responsible for the hardness reduction of the identified soft zone in the as-welded condition. The identified soft zone exhibits a high location consistency at three thermal stages. Local chemistry analysis and thermodynamic calculation show that the lower chromium concentrations inside these retained grains thermodynamically decrease their potentials for austenitic transformation during welding. Heterogeneous grain growth is observed in the soft zone during postweld heat treatment. The mismatch of strengths between the weak Cr-depleted grains and strong Cr-rich grains enhances the creep damage. Local deformation of the weaker Cr-depleted grains accelerates the formation of creep cavities.

  9. Semisolid forming of S48C steel grade

    NASA Astrophysics Data System (ADS)

    Plata, Gorka; Lozares, Jokin; Azpilgain, Zigor; Hurtado, Iñaki; Loizaga, Iñigo; Idoyaga, Zuriñe

    2017-10-01

    Steel production and component manufacturing industries have to face the challenge of globalization, trying to overcome the economic pressure to remain competitive. Moreover, the lightweighting trend of the latter years implies an even higher challenge to maintain the steel use. Therefore, advanced manufacturing processes will be the cornerstone. In this field, Semisolid forming (SSF) has demonstrated the capability of obtaining complex geometries and saving raw material and energy. Despite it is complicated the SSF of sound components, in Mondragon Unibertsitatea it has been successfully demonstrated the capability of producing strong enough automotive components with 42CrMo4 steel grade. In this work, we demonstrate the capability of SSF S48C steel grade with great mechanical properties.

  10. Demonstration and Validation of Stainless Steel Materials for Critical Above Grade Piping in Highly Corrosive Locations

    DTIC Science & Technology

    2017-05-01

    Protecting And Bonding Reinforcing Steel In Cement -Based Composites, Corrosion 2009, Atlanta, GA, 22-26 March 2009. 7. Hock, V., O. Marshall, S...ER D C/ CE RL T R- 17 -1 3 DoD Corrosion Prevention and Control Program Demonstration and Validation of Stainless Steel Materials for...ERDC/CERL TR-17-13 May 2017 Demonstration and Validation of Stainless Steel Materials for Critical Above-Grade Piping in Highly Corrosive

  11. Ductile Tearing Resistance Indexing of Automotive Grade DP 590 Steel Sheets: EWF Testing Using DENT Specimens

    NASA Astrophysics Data System (ADS)

    Sahoo, Subhadra; Padmapriya, N.; De, Partha Sarathi; Chakraborti, P. C.; Ray, S. K.

    2018-03-01

    The essential work of fracture (EWF) method has been explored for indexing the ductile tearing resistance of DP 590 automotive grade dual-phase steel sheet both in longitudinal (L-T) and transverse (T-L) orientations. The simplest possible test and analysis procedures have been adopted. The EWF method is found to be eminently suitable for routine quality control and product development purposes for such materials. Areas for further research for improving the experimental strategy are highlighted. For the investigated steel sheet, the estimated tearing resistance is found to be distinctly higher for the L-T orientation compared to the T-L orientation; the reason thereof merits further investigation.

  12. Automatic Detection of Pearlite Spheroidization Grade of Steel Using Optical Metallography.

    PubMed

    Chen, Naichao; Chen, Yingchao; Ai, Jun; Ren, Jianxin; Zhu, Rui; Ma, Xingchi; Han, Jun; Ma, Qingqian

    2016-02-01

    To eliminate the effect of subjective factors during manually determining the pearlite spheroidization grade of steel by analysis of optical metallography images, a novel method combining image mining and artificial neural networks (ANN) is proposed. The four co-occurrence matrices of angular second moment, contrast, correlation, and entropy are adopted to objectively characterize the images. ANN is employed to establish a mathematical model between the four co-occurrence matrices and the corresponding spheroidization grade. Three materials used in coal-fired power plants (ASTM A315-B steel, ASTM A335-P12 steel, and ASTM A355-P11 steel) were selected as the samples to test the validity of our proposed method. The results indicate that the accuracies of the calculated spheroidization grades reach 99.05, 95.46, and 93.63%, respectively. Hence, our newly proposed method is adequate for automatically detecting the pearlite spheroidization grade of steel using optical metallography.

  13. Evaluation of Argon ion irradiation hardening of ferritic/martensitic steel-T91 using nanoindentation, X-ray diffraction and TEM techniques

    NASA Astrophysics Data System (ADS)

    Naveen Kumar, N.; Tewari, R.; Mukherjee, P.; Gayathri, N.; Durgaprasad, P. V.; Taki, G. S.; Krishna, J. B. M.; Sinha, A. K.; Pant, P.; Revally, A. K.; Dutta, B. K.; Dey, G. K.

    2017-08-01

    In the present study, microstructures of Ferritic-martensitic T-91 steel irradiated at room temperature for 5, 10 and 20 dpa using 315 KeV Ar+9 ions have been characterized by grazing incident X-ray diffraction (GIXRD) and by transmission electron microscopy (TEM). Line profiles of GIXRD patterns have shown that the size of domain continuously reduced with increasing dose of radiation. TEM investigations of irradiated samples have shown the presence of black dots, the number density of which decreases with increasing dose. Microstructures of irradiated samples have also revealed the presence of point defect clusters, such as dislocation loops and bubbles. In addition, dissolution of precipitates due to irradiation was also observed. Nano-indentation studies on the irradiated samples have shown saturation behavior in hardness as a function of dose which could be correlated with the changes in the yield strength of the alloy.

  14. FY17 Status Report on Testing Supporting the Inclusion of Grade 91 Steel as an Acceptable Material for Application of the EPP Methodology

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Messner, Mark C.; Sham, Sam; Wang, Yanli

    This report summarizes the experiments performed in FY17 on Gr. 91 steels. The testing of Gr. 91 has technical significance because, currently, it is the only approved material for Class A construction that is strongly cyclic softening. Specific FY17 testing includes the following activities for Gr. 91 steel. First, two types of key feature testing have been initiated, including two-bar thermal ratcheting and Simplified Model Testing (SMT). The goal is to qualify the Elastic – Perfectly Plastic (EPP) design methodologies and to support incorporation of these rules for Gr. 91 into the ASME Division 5 Code. The preliminary SMT testmore » results show that Gr. 91 is most damaging when tested with compression hold mode under the SMT creep fatigue testing condition. Two-bar thermal ratcheting test results at a temperature range between 350 to 650o C were compared with the EPP strain limits code case evaluation, and the results show that the EPP strain limits code case is conservative. The material information obtained from these key feature tests can also be used to verify its material model. Second, to provide experimental data in support of the viscoplastic material model development at Argonne National Laboratory, selective tests were performed to evaluate the effect of cyclic softening on strain rate sensitivity and creep rates. The results show the prior cyclic loading history decreases the strain rate sensitivity and increases creep rates. In addition, isothermal cyclic stress-strain curves were generated at six different temperatures, and a nonisothermal thermomechanical testing was also performed to provide data to calibrate the viscoplastic material model.« less

  15. Influence of carbon steel grade on the initial attachment of bacteria and microbiologically influenced corrosion.

    PubMed

    Javed, M A; Neil, W C; Stoddart, P R; Wade, S A

    2016-01-01

    The influence of the composition and microstructure of different carbon steel grades on the initial attachment (≤ 60 min) of Escherichia coli and subsequent longer term (28 days) corrosion was investigated. The initial bacterial attachment increased with time on all grades of carbon steel. However, the rate and magnitude of bacterial attachment varied on the different steel grades and was significantly less on the steels with a higher pearlite phase content. The observed variations in the number of bacterial cells attached across different steel grades were significantly reduced by applying a fixed potential to the steel samples. Longer term immersion studies showed similar levels of biofilm formation on the surface of the different grades of carbon steel. The measured corrosion rates were significantly higher in biotic conditions compared to abiotic conditions and were found to be positively correlated with the pearlite phase content of the different grades of carbon steel coupons.

  16. Outbursts formation on low carbon and trip steel grades during hot-dip galvanisation

    NASA Astrophysics Data System (ADS)

    Petit, E. J.; Lamm, L.; Gilles, M.

    2004-12-01

    Low carbon and TRIP grade steels have been hot dip galvanised in order to study outbursts formation. Microstructure and texture of intermetallic phases have been observed after selective electrochemical etching by scanning electron microscopy. Potential versus time (chronopotentiometric) characteristics were recorded in order to monitor surface modifications. This combination of techniques enable to quantify and observe intermetallic phase one by one. The overall thickness of coating on both substrates are similar. However, microstructures of Fe-Zn intermetallic phases are very different on both grades. In particular, the V phase is dense on standard steel but develops a highly branched filament structure on TRIP steel. The transformation of V phase to d and G1 are limited on TRIP steel. Differences of texture provide clues for understanding mechanisms of formation of outbursts. They can account for the differences of mechanical properties and corrosion resistance. Silicon from the substrate influences the reactivity of TRIP steels due to capping and local reactions. La formation des outbursts a été étudiée sur un acier bas carbone et sur un acier TRIP galvanisés. Les épaisseurs des revêtements sont similaires. Néanmoins, les observations microscopiques et les érosions électrochimiques montrent que la répartition des phases intermétalliques et leurs microstructures diffèrent sensiblement en fonction de la nature du substrat. Ces différences expliquent les propriétés mécaniques et anticorrosions. L’encapsulation de la surface par les oxydes de silicium freine la transformation de la phase dzêta en delta et gamma sur l’acier TRIP.

  17. Evaluation of Crack Arrest Toughness ( K IA) of P91 Steel in Various Cold Worked and Thermally Aged Conditions

    NASA Astrophysics Data System (ADS)

    Sathyanarayanan, S.; Moitra, A.; Sasikala, G.; Bhaduri, A. K.

    2015-02-01

    K IA is increasingly being regarded as a characteristic fracture toughness below which cleavage fracture does not occur. Its evaluation from small-sized Charpy specimens would be advantageous for applications in power plant industries. In this study, K IA has been evaluated for P91 steel in various cold worked and thermally aged conditions. Evaluation of K IA requires determination of crack arrest load( P arrest) and crack arrest length( a arrest). The main challenge is in the determination of a arrest due to the non-availability of standard methodologies and the absence of unequivocal microstructural signatures on the fracture surface in this steel to identify crack arrest. a arrest has been determined using the analytical Key- Curve methodology which has proven successful for this steel in unaged condition. The applicability of the Key- Curve method is validated by the good agreement of the determined final crack length with that measured optically on unbroken specimens of N&T and subsequently 15% cold-worked P91 steel which had been previously aged at 650 °C for 5000 h. Mean K IA varies from 47.46 MPa√m (NT steel aged at 600 °C for 5000 h) to 69.85 MPa√m(NT + 15% cw steel aged at 650 °C for 10000 h) for the various cold worked and aged datasets. K IA is found to be an average property unlike initiation toughness ( K Jd) which shows statistical scatter. Mean K IA is found to be in reasonable agreement with the lower bound values of cleavage initiation toughness ( K Jd) for the datasets in this study.

  18. Generalized Constitutive-Based Theoretical and Empirical Models for Hot Working Behavior of Functionally Graded Steels

    NASA Astrophysics Data System (ADS)

    Vanini, Seyed Ali Sadough; Abolghasemzadeh, Mohammad; Assadi, Abbas

    2013-07-01

    Functionally graded steels with graded ferritic and austenitic regions including bainite and martensite intermediate layers produced by electroslag remelting have attracted much attention in recent years. In this article, an empirical model based on the Zener-Hollomon (Z-H) constitutive equation with generalized material constants is presented to investigate the effects of temperature and strain rate on the hot working behavior of functionally graded steels. Next, a theoretical model, generalized by strain compensation, is developed for the flow stress estimation of functionally graded steels under hot compression based on the phase mixture rule and boundary layer characteristics. The model is used for different strains and grading configurations. Specifically, the results for αβγMγ steels from empirical and theoretical models showed excellent agreement with those of experiments of other references within acceptable error.

  19. Gas metal arc weldability of 1.5 GPa grade martensitic steels

    NASA Astrophysics Data System (ADS)

    Hwang, Insung; Yun, Hyeonsang; Kim, Dongcheol; Kang, Munjin; Kim, Young-Min

    2018-01-01

    The gas metal arc weldability of 1.5 GPa grade martensitic (MART) steel was evaluated using both inverter direct current (DC) and DC pulse power type welders, under conditions of different welding currents, welding speeds, and shielding gasses. By investigating the bead appearance, tensile strength, and arc stability, it was determined that DC pulse power is better than inverter DC power for arc welding of 1.3 mm thick 1.5 GPa grade MART steel. Further, from the results of the weldability for various shielding gases, it was determined that mixed shielding gas is more effective for welding 1.5 GPa grade MART steel than is pure inert gas (Ar) or active (CO2) gas. In the case of pure shielding gas, no sound bead was formed under any conditions. However, when the mixed shielding gas was used, sound and fine beads were obtained.

  20. Development of 780MPa grade gal annealed dual phase steel sheets for automobile

    NASA Astrophysics Data System (ADS)

    Jiang, Yinghua; Xie, Chunqian; Kuang, Shuang

    2018-01-01

    As the weight reduction of automotive body and crash safety become much more important factors, in an effort to satisfy these requirements, Shougang has developed 780MPa grade galvannealed dual phase steel sheet. Steel chemistry with low C and low Si was designed for good zinc wettability and spot weldability. And some of elements were added to improve the hole expansibility and work hardening capacity of steel as these effectively refine the microstructure and introduce retained austenite. Newly developed 780MPa grade galvannealed dual phase steels have a high yield strength and a good hole expansibility.

  1. Formability of new high performance A710 grade 50 structural steel.

    DOT National Transportation Integrated Search

    2014-01-01

    This project compared the formability of modified ASTM A710 Grade B50 ksi yield strength steel, jointly developed by : Northwestern University and the Illinois Department of Transportation, with ASTM A606 Type 4 weathering steel used in Illinois : an...

  2. Optimization of Grade 100 High-Performance Steel Butt Welds [Tech Brief

    DOT National Transportation Integrated Search

    2013-11-01

    In the development of the high performance steels (HPS) grades, three advisory groups were formed to oversee and guide the development of the steels in terms of their design, welding, and corrosion aspects. One of the aspects considered by the Weldin...

  3. Effect of strain rate and notch geometry on tensile properties and fracture mechanism of creep strength enhanced ferritic P91 steel

    NASA Astrophysics Data System (ADS)

    Pandey, Chandan; Mahapatra, M. M.; Kumar, Pradeep; Saini, N.

    2018-01-01

    Creep strength enhanced ferritic (CSEF) P91 steel were subjected to room temperature tensile test for quasi-static (less than 10-1/s) strain rate by using the Instron Vertical Tensile Testing Machine. Effect of different type of notch geometry, notch depth and angle on mechanical properties were also considered for different strain rate. In quasi-static rates, the P91 steel showed a positive strain rate sensitivity. On the basis of tensile data, fracture toughness of P91 steel was also calculated numerically. For 1 mm notch depth (constant strain rate), notch strength and fracture toughness were found to be increased with increase in notch angle from 45° to 60° while the maximum value attained in U-type notch. Notch angle and notch depth has found a minute effect on P91 steel strength and fracture toughness. The fracture surface morphology was studied by field emission scanning electron microscopy (FESEM).

  4. [Stainless steels for medical instruments].

    PubMed

    Feofilov, R N

    1981-01-01

    Both in the USSR and abroad similar types of martensitic and austenitic stainless steel are used for the manufacture of medical instruments. Martensitic steel, the cheapest and most economically alloyed, has the best combination of properties necessary for medical instruments. The analysis of the Soviet and foreign experience in using different grades of steel for the production of medical instruments demonstrates the expediency and possibility of improving the quality of martensitic steel and rolled stock, as well as that of medical instruments manufactured from these materials, by improving, the operations of the metallurgical and technological processes and by specifying more precisely the requirements for medical instruments. The possibility and expediency of using, in some technically justified cases, lower grades of alloyed steel instead of grade 12X18H9T for clamps and other instruments made of stainless steel, as well as highly corrosive grades of steel for microinstruments, have been established.

  5. A Study to Increase Weld Penetration in P91 Steel During TIG Welding by using Activating Fluxes

    NASA Astrophysics Data System (ADS)

    Singh, Akhilesh Kumar; Kumar, Mayank; Dey, Vidyut; Naresh Rai, Ram

    2017-08-01

    Activated Flux TIG (ATIG) welding is a unique joining process, invented at Paton Institute of electric welding in 1960. ATIG welding process is also known as flux zoned TIG (FZTIG). In this process, a thin layer of activating flux is applied along the line on the surface of the material where the welding is to be carries out. The ATIG process aids to increase the weld penetration in thick materials. Activating fluxes used in the literature show the use of oxides like TiO2, SiO2, Cr2O3, ZnO, CaO, Fe2O3, and MnO2 during welding of steels. In the present study, ATIG was carried out on P-91 steel. Though, Tungsten Inert Gas welding gives excellent quality welds, but the penetration obtained in such welding is still demanding. P91 steel which is ferritic steel is used in high temperature applications. As this steel is, generally, used in thick sections, fabrication of such structures with TIG welding is limited, due to its low depth of penetration. To increase the depth of penetration in P91while welding with ATIG, the role of various oxides were investigated. Apart from the oxides mentioned above, in the present study the role of B2O3, V2O5 and MgO, during ATIG welding of P91 was investigated. It was seen that, compared to TIG welding, there was phenomenal increase in weld penetration during ATIG welding. Amongst all the oxides used in this study, maximum penetration was achieved in case of B2O3. The measurements of weld penetration, bead width and heat affected zone of the weldings were carried out using an image analysis technique.

  6. 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.

  7. Creep and microstructural processes in a low-alloy 2.25%Cr1.6%W steel (ASTM Grade 23)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kucharova, K.; Sklenicka, V., E-mail: sklen@ipm.cz; CEITEC — IPM, Institute of Physics of Materials, Academy of Sciences of the Czech Republic, CZ-616 62 Brno

    2015-11-15

    A low-alloy 2.25%Cr1%Mo steel (ASTM Grade 22) has been greatly improved by the substitution of almost all of the 1%Mo by 1.6%W. The improved material has been standardized as P/T23 steel (Fe–2.25Cr–1.6W–0.25V–0.05Nb–0.07C). The present investigation was conducted on T23 steel in an effort to obtain a more complete description and understanding of the role of the microstructural evolution and deformation processes in high-temperature creep. Constant load tensile creep tests were carried out in an argon atmosphere in the temperature range 500–650 °C at stresses ranging from 50 to 400 MPa. It was found that the diffusion in the matrix latticemore » is the creep-rate controlling process. The results of an extensive transmission electron microscopy (TEM) analysis programme to investigate microstructure evolution as a function of temperature are described and compared with the thermodynamic calculations using the software package Thermo-Calc. The significant creep-strength drop of T23 steel after long-term creep exposures can be explained by the decrease in dislocation hardening, precipitation hardening and solid solution hardening due to the instability of the microstructure at high temperature. - Highlights: • The constant load creep tests of T23 steel were carried out at 500–650 °C. • The stress exponents of the creep rate correspond to power law (dislocation) creep. • Diffusion in the matrix lattice is the creep-rate controlling process. • The microstructure instability is the main creep degradation process in T23 steel.« less

  8. Investigation of diffusional interaction between P91 grade ferritic steel and Fe-15 wt.%B alloy and study of kinetics of boride formation at high temperature

    NASA Astrophysics Data System (ADS)

    Rai, Arun Kumar; Vijayashanthi, N.; Tripathy, H.; Hajra, R. N.; Raju, S.; Murugesan, S.; Saroja, S.

    2017-11-01

    In the present study, the feasibility of employing the indigenously developed ferroboron alloy (Fe-15 wt.%B) as an alternate neutron shield material in combination with 9Cr-based ferritic steel (P91) clad in future Indian fast breeder reactors (FBR), has been investigated from a metallurgical perspective. Towards this goal, a series of diffusion couple experiments have been conducted at three different temperatures namely, 600, 700 and 800 °C for time durations up to 5000 h. The thickness of interaction layer has been monitored using standard metallographic procedures. The experiments revealed that ferroboron/P91 combination exhibited a tendency to form complex intermetallic borides at the interface. The structural and microstructural characterization of the interface confirmed that the reaction layer consists predominantly of borides of Fe and Cr of type FeB, Fe2B, (Fe,Cr)2B and (Fe,Cr)B. The measured variation of interaction layer thickness as a function of time and temperature have been modelled in terms of diffusion mediated interaction. The growth kinetics of borided layer has followed the parabolic law at each temperature, and the apparent activation energy for boride layer formation is found to be of the order of 115 kJ mol-1. This indicates that the kinetics of boriding could be governed by diffusion of B into the P91 matrix. Based on the findings of present study, an extrapolative estimate of the clad attack thickness at 550 °C for 60 years of operating time has been made and it turns out to be 210 ± 15 μm, which is less than the clad thickness of FBR shielding subassembly (4 mm) [1]. Thus, this study confirms that at testing temperatures from 550 to 600 °C, the ferroboron/P91 steel combination can be safely employed for shielding subassembly applications in fast reactors.

  9. Compatibility of martensitic/austenitic steel welds with liquid lead bismuth eutectic environment

    NASA Astrophysics Data System (ADS)

    Van den Bosch, J.; Almazouzi, A.

    2009-04-01

    The high-chromium ferritic/martensitic steel T91 and the austenitic stainless steel 316L are to be used in contact with liquid lead-bismuth eutectic (LBE), under high irradiation doses. Both tungsten inert gas (TIG) and electron beam (EB) T91/316L welds have been examined by means of metallography, scanning electron microscopy (SEM-EDX), Vickers hardness measurements and tensile testing both in inert gas and in LBE. Although the T91/316L TIG weld has very good mechanical properties when tested in air, its properties decline sharply when tested in LBE. This degradation in mechanical properties is attributed to the liquid metal embrittlement of the 309 buttering used in TIG welding of T91/316L welds. In contrast to mixed T91/316L TIG welding, the mixed T91/316L EB weld was performed without buttering. The mechanical behaviour of the T91/316L EB weld was very good in air after post weld heat treatment but deteriorated when tested in LBE.

  10. Acoustic emission during tensile deformation of M250 grade maraging steel

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Chandan Kumar; Rajkumar, Kesavan Vadivelu; Chandra Rao, Bhaghi Purna; Jayakumar, Tamanna

    2012-05-01

    Acoustic emission (AE) generated during room temperature tensile deformation of varyingly heat treated (solution annealed and thermally aged) M250 grade maraging steel specimens have been studied. Deformation of microstructure corresponding to different heat treated conditions in this steel could be distinctly characterized using the AE parameters such as RMS voltage, counts and peak amplitude of AE hits (events).

  11. High temperature deformation behavior, thermal stability and irradiation performance in Grade 92 steel

    NASA Astrophysics Data System (ADS)

    Alsagabi, Sultan

    The 9Cr-2W ferritic-martensitic steel (i.e. Grade 92 steel) possesses excellent mechanical and thermophysical properties; therefore, it has been considered to suit more challenging applications where high temperature strength and creep-rupture properties are required. The high temperature deformation mechanism was investigated through a set of tensile testing at elevated temperatures. Hence, the threshold stress concept was applied to elucidate the operating high temperature deformation mechanism. It was identified as the high temperature climb of edge dislocations due to the particle-dislocation interactions and the appropriate constitutive equation was developed. In addition, the microstructural evolution at room and elevated temperatures was investigated. For instance, the microstructural evolution under loading was more pronounced and carbide precipitation showed more coarsening tendency. The growth of these carbide precipitates, by removing W and Mo from matrix, significantly deteriorates the solid solution strengthening. The MX type carbonitrides exhibited better coarsening resistance. To better understand the thermal microstructural stability, long tempering schedules up to 1000 hours was conducted at 560, 660 and 760°C after normalizing the steel. Still, the coarsening rate of M23C 6 carbides was higher than the MX-type particles. Moreover, the Laves phase particles were detected after tempering the steel for long periods before they dissolve back into the matrix at high temperature (i.e. 720°C). The influence of the tempering temperature and time was studied for Grade 92 steel via Hollomon-Jaffe parameter. Finally, the irradiation performance of Grade 92 steel was evaluated to examine the feasibility of its eventual reactor use. To that end, Grade 92 steel was irradiated with iron (Fe2+) ions to 10, 50 and 100 dpa at 30 and 500°C. Overall, the irradiated samples showed some irradiation-induced hardening which was more noticeable at 30°C. Additionally

  12. Optimization of BI test parameters to investigate mechanical properties of Grade 92 steel

    NASA Astrophysics Data System (ADS)

    Barbadikar, Dipika R.; Vincent, S.; Ballal, Atul R.; Peshwe, Dilip R.; Mathew, M. D.

    2018-04-01

    The ball indentation (BI) testing is used to evaluate the tensile properties of materials namely yield strength, strength coefficient, ultimate tensile strength, and strain hardening exponent. The properties evaluated depend on a number of BI test parameters. These parameters include the material constants like yield slope (YS), constraint factor (CF), yield offset parameter (YOP). Number of loading/unloading cycles, preload, indenter size and depth of penetration of indenter also affects the properties. In present investigation the effect of these parameters on the stress-strain curve of normalized and tempered Grade 92 steel is evaluated. Grade 92 is a candidate material for power plant application over austenitic stainless steel and derives its strength from M23C6, MX precipitates and high dislocation density. CF, YS and YOP changed the strength properties considerably. Indenter size effect resulted in higher strength for smaller indenter. It is suggested to use larger indenter diameter and higher number of loading cycles for GRADE 92 steel to get best results using BI technique.

  13. Influence of low nickel (0.09 wt%) content on microstructure and toughness of P91 steel welds

    NASA Astrophysics Data System (ADS)

    Arivazhagan, B.; Vasudevan, M.; Kamaraj, M.

    2015-05-01

    Modified 9Cr-1Mo (P91) steel is widely used as a high temperature structural material in the fabrication of power plant components. Alloying elements significantly influences the microstructure and mechanical properties of P91 steel weldments. The alloying elements manganese and nickel significantly influence the lower critical phase transformation temperature (AC1) as well as tempering response of welds. In the existing published information there was wide spread use of high Mn+Ni filler wire. In the present study, weldment preparation was completed using GTA filler wire having low Nickel content (Mn+Ni of 0.58 wt% including nickel content of 0.09 wt%). Microstructure and mechanical properties characterization was done. There is a requirement on minimum toughness of 47 Joules for P91 steel tempered welds at room temperature. Microstructural observation revealed that the GTA welds have low δ-ferrite content (<0.5%) in the martensite matrix. In the as-weld condition, the toughness was 28 Joules whereas after PWHT at 760 °C-2 h it was 115 Joules. In the present study, toughness of low nickel weld was higher due to low δ-ferrite content (<0.5%), multipass grain refinement and weld metal deposition of single pass per layer of weldment.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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 themore » 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.« less

  15. Creep of A508/533 Pressure Vessel Steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Richard Wright

    2014-08-01

    ABSTRACT Evaluation of potential Reactor Pressure Vessel (RPV) steels has been carried out as part of the pre-conceptual Very High Temperature Reactor (VHTR) design studies. These design studies have generally focused on American Society of Mechanical Engineers (ASME) Code status of the steels, temperature limits, and allowable stresses. Initially, three candidate materials were identified by this process: conventional light water reactor (LWR) RPV steels A508 and A533, 2¼Cr-1Mo in the annealed condition, and Grade 91 steel. The low strength of 2¼Cr-1Mo at elevated temperature has eliminated this steel from serious consideration as the VHTR RPV candidate material. Discussions with themore » very few vendors that can potentially produce large forgings for nuclear pressure vessels indicate a strong preference for conventional LWR steels. This preference is based in part on extensive experience with forging these steels for nuclear components. It is also based on the inability to cast large ingots of the Grade 91 steel due to segregation during ingot solidification, thus restricting the possible mass of forging components and increasing the amount of welding required for completion of the RPV. Grade 91 steel is also prone to weld cracking and must be post-weld heat treated to ensure adequate high-temperature strength. There are also questions about the ability to produce, and very importantly, verify the through thickness properties of thick sections of Grade 91 material. The availability of large components, ease of fabrication, and nuclear service experience with the A508 and A533 steels strongly favor their use in the RPV for the VHTR. Lowering the gas outlet temperature for the VHTR to 750°C from 950 to 1000°C, proposed in early concept studies, further strengthens the justification for this material selection. This steel is allowed in the ASME Boiler and Pressure Vessel Code for nuclear service up to 371°C (700°F); certain excursions above that

  16. 35. PRATER GRADE ROAD VIEW, FACING NW. NOTE WEATHERING STEEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. PRATER GRADE ROAD VIEW, FACING NW. NOTE WEATHERING STEEL RAIL AND ROAD CUT IN DISTANCE. MONTEZUMA VALLEY OVERLOOK IS JUST TO RIGHT OF DISTANT ROAD CUT. - Mesa Verde National Park Main Entrance Road, Cortez, Montezuma County, CO

  17. Graded High-Strength Spring-Steels by a Special Inductive Heat T reatment

    NASA Astrophysics Data System (ADS)

    Tump, A.; Brandt, R.

    2016-03-01

    A method for effective lightweight design is the use of materials with high specific strength. As materials e.g. titanium are very expensive, steel is still the most important material for manufacturing automotive components. Steel is cost efficient, easy to recycle and its tensile strength easily exceeds 2,000 MPa by means of modern QT-technology (Quenched and Tempered). Therefore, lightweight design is still feasible in spite of the high density of steel. However, a further increase of tensile strength is limited, especially due to an increasing notch sensitivity and exposure to a corrosive environment. One solution is a special QT-process for steel, which creates a hardness gradient from the surface to the core of the material. This type of tailored material possesses a softer layer, which improves material properties such as fracture toughness and notch sensitivity. This leads to a better resistance to stress corrosion cracking and corrosion fatigue. Due to this optimization, a weight reduction is feasible without the use of expensive alloying elements. To understand the damage mechanism a comprehensive testing procedure was performed on homogeneous and gradient steels. Some results regarding the fracture mechanic behavior of such steels will be discussed.

  18. Machining-induced deformation in stepped specimens of PH 13-8 Mo, 18 nickel maraging steel grade 200T1 and grain-refined HP 9-4-20

    NASA Technical Reports Server (NTRS)

    Wigley, D. A.

    1985-01-01

    The results of a study to evaluate the dimensional changes created during machining and subsequent cycling to cryogenic temperatures for three different metallic alloys are presented. Experimental techniques are described and results presented for 18 Ni Grade 200 maraging steel, PH-13-8 Mo stainless steel, and Grain-refined HP 9-4-20.

  19. Additive manufacturing of complex-shaped graded TiC/steel composites

    DOE PAGES

    Levy, Asaf; Miriyev, Aslan; Elliott, Amy; ...

    2017-01-12

    Complex-shaped TiCx ceramic preforms with a gradient of carbon content in the titanium carbide phase (x changes from 0.7 to 0.98) were fabricated for the first time by Binder jet 3D printing technology. The complex-shaped preforms were infiltrated with molten carbon steel (0.7 wt.%C). Thermodynamic considerations showed that carbon could be transferred from titanium carbide to steel and vice versa according to the initial concentration of carbon (activity) in both phases. After infiltration, solidification and slow cooling, a microstructural gradient was obtained throughout the steel matrix from ferrite, in the region where the steel was in contact with titanium carbidemore » of low carbon content (x=0.7), to pearlite, in the region where the steel underwent interactions with stoichiometric titanium carbide (x=0.98). After annealing at 900°C and quenching in oil, a structural gradient in the steel matrix from ferrite to martensite was obtained, resulting in a hardness gradient of 700-1600 HV. The suggested processing approach allows for fabrication of complex-shaped graded composites with the desired property gradient suitable for a wide range of practical applications.« less

  20. Additive manufacturing of complex-shaped graded TiC/steel composites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Levy, Asaf; Miriyev, Aslan; Elliott, Amy

    Complex-shaped TiCx ceramic preforms with a gradient of carbon content in the titanium carbide phase (x changes from 0.7 to 0.98) were fabricated for the first time by Binder jet 3D printing technology. The complex-shaped preforms were infiltrated with molten carbon steel (0.7 wt.%C). Thermodynamic considerations showed that carbon could be transferred from titanium carbide to steel and vice versa according to the initial concentration of carbon (activity) in both phases. After infiltration, solidification and slow cooling, a microstructural gradient was obtained throughout the steel matrix from ferrite, in the region where the steel was in contact with titanium carbidemore » of low carbon content (x=0.7), to pearlite, in the region where the steel underwent interactions with stoichiometric titanium carbide (x=0.98). After annealing at 900°C and quenching in oil, a structural gradient in the steel matrix from ferrite to martensite was obtained, resulting in a hardness gradient of 700-1600 HV. The suggested processing approach allows for fabrication of complex-shaped graded composites with the desired property gradient suitable for a wide range of practical applications.« less

  1. Long term corrosion on T91 and AISI1 316L steel in flowing lead alloy and corrosion protection barrier development: Experiments and models

    NASA Astrophysics Data System (ADS)

    Weisenburger, A.; Schroer, C.; Jianu, A.; Heinzel, A.; Konys, J.; Steiner, H.; Müller, G.; Fazio, C.; Gessi, A.; Babayan, S.; Kobzova, A.; Martinelli, L.; Ginestar, K.; Balbaud-Célerier, F.; Martín-Muñoz, F. J.; Soler Crespo, L.

    2011-08-01

    Considering the status of knowledge on corrosion and corrosion protection and especially the need for long term compatibility data of structural materials in HLM a set of experiments to generate reliable long term data was defined and performed. The long term corrosion behaviour of the two structural materials foreseen in ADS, 316L and T91, was investigated in the design relevant temperature field, i.e. from 300 to 550 °C. The operational window of the two steels in this temperature range was identified and all oxidation data were used to develop and validate the models of oxide scale growth in PbBi. A mechanistic model capable to predict the oxidation rate applying some experimentally fitted parameters has been developed. This model assumes parabolic oxidation and might be used for design and safety relevant investigations in future. Studies on corrosion barrier development allowed to define the required Al content for the formation of thin alumina scales in LBE. These results as well as future steps and required improvements are discussed. Variation of experimental conditions clearly showed that specific care has to be taken with respect to local flow conditions and oxygen concentrations.

  2. Ballistic-Failure Mechanisms in Gas Metal Arc Welds of MIL A46100 Armor-Grade Steel: A Computational Investigation

    DTIC Science & Technology

    2014-06-12

    distribution is unlimited. Ballistic-Failure Mechanisms in Gas Metal Arc Welds of Mil A46100 Armor-Grade Steel : A Computational Investigation The views...Welds of Mil A46100 Armor-Grade Steel : A Computational Investigation Report Title In our recent work, a multi-physics computational model for the...introduction of the sixth module in the present work in recognition of the fact that in thick steel GMAW weldments, the overall ballistic performance

  3. Multi-response optimization of process parameters for GTAW process in dissimilar welding of Incoloy 800HT and P91 steel by using grey relational analysis

    NASA Astrophysics Data System (ADS)

    vellaichamy, Lakshmanan; Paulraj, Sathiya

    2018-02-01

    The dissimilar welding of Incoloy 800HT and P91 steel using Gas Tungsten arc welding process (GTAW) This material is being used in the Nuclear Power Plant and Aerospace Industry based application because Incoloy 800HT possess good corrosion and oxidation resistance and P91 possess high temperature strength and creep resistance. This work discusses on multi-objective optimization using gray relational analysis (GRA) using 9CrMoV-N filler materials. The experiment conducted L9 orthogonal array. The input parameter are current, voltage, speed. The output response are Tensile strength, Hardness and Toughness. To optimize the input parameter and multiple output variable by using GRA. The optimal parameter is combination was determined as A2B1C1 so given input parameter welding current at 120 A, voltage at 16 V and welding speed at 0.94 mm/s. The output of the mechanical properties for best and least grey relational grade was validated by the metallurgical characteristics.

  4. Fracture toughness and the master curve for modified 9Cr-1Mo steel

    NASA Astrophysics Data System (ADS)

    Yoon, Ji-Hyun; Yoon, Eui-Pak

    2006-12-01

    Modified 9Cr-1Mo steel is a primary candidate material for the reactor pressure vessel of a Very High Temperature Gas-Cooled Reactor (VHTR) in the Korean Nuclear Hydrogen Development and Demonstration (NHDD) program. In this study, the T0 reference temperature, J-R fracture resistance and Charpy impact properties were evaluated for commercial Grade 91 steel as part of the preliminary testing for a selection of the RPV material for the VHTR. The fracture toughness of the modified 9Cr-1Mo steel was compared with that of SA508-Gr.3. The objective of this study was to obtain the pre-irradiation fracture toughness properties of the modified 9Cr-1Mo steel as reference data for an investigation of radiation effects. Charpy impact properties of the modified 9Cr-1Mo steel were similar to those of SA508-Gr.3. T0 reference temperatures were measured as -67.7 and -72.4°C from the tests with standard PCVN (pre-cracked Charpy V-notch) and half-sized PCVN specimens respectively, which were similar to the results for SA508-Gr.3. The KJc values of the modified 9Cr-1Mo steel with the test temperatures are successfully expressed by the Master Curve. The J-R fracture resistance of the modified 9Cr-1Mo steel at room temperature was nearly identical to that of SA508-Gr.3; in contrast, it was slightly higher at an elevated temperature.

  5. Study of the structure and properties of metal of the major steam lines of a CCGT-420 unit made from high-chromium X10CrMoVNb9-1 (P91) steel

    NASA Astrophysics Data System (ADS)

    Grin', E. A.; Anokhov, A. E.; Pchelintsev, A. V.; Krüger, E.-T.

    2016-07-01

    The technology of manufacture of live steam lines and hot reheat lines at FINOW Rohrsysteme GmbH are discussed. These pipelines are designed for high-performance CCGT units and are made from high-chromium martensitic steel X10CrMoVNb9-1 (P91). The principles of certification and evaluation of conformance of thermal and mechanical equipment made from new construction materials with the TRCU 032-2013 technical regulation of the Customs Union are detailed. The requirements outlined in Russian and international regulatory documents regarding the manufacture of pipes and semifinished products for pipeline systems are compared. The characteristic features of high-chromium martensitic steel, which define the requirements for its heat treatment and welding, are outlined. The methodology and the results of a comprehensive analysis of metal of pipes, fittings, and weld joints of steam lines are presented. It is demonstrated that the short-term mechanical properties of metal (P91 steel) of pipes, bends, and weld joints meet the requirements of European standards and Russian technical specifications. The experimental data on long-term strength of metal of pipes from a live steam line virtually match the corresponding reference curve from the European standard, while certain experimental points for metal of bends of this steam line and metal of pipes and bends from a hot reheat line lie below the reference curve, but they definitely stay within the qualifying (20%) interval of the scatter band. The presence of a weakened layer in the heat-affected zone of weld joints of steel P91 is established. It is shown that the properties of this zone govern the short-term and long-term strength of weld joints in general. The results of synthesis and analysis of research data support the notion that the certification testing of steam lines and other equipment made from chromium steels should necessarily involve the determination of long-term strength parameters.

  6. Creep Strength Behavior of Boron Added P91 Steel and its Weld in the Temperature Range of 600-650°C

    NASA Astrophysics Data System (ADS)

    Swaminathan, J.; Das, C. R.; Baral, Jayashree; Phaniraj, C.; Ghosh, R. N.; Albert, S. K.; Bhaduri, A. K.

    One of the promising ways for mitigation of Type IV cracking — a failure by cracking at the intercritical /fine grained heat affected zone, a life limiting problem in advanced 9-12 Cr ferritic steel weld like that of P91 is through modification of alloy composition by addition of boron. Addition of boron was observed to improve the microstructure at the weld zone and hence the creep strength. In the present work, boron (100 ppm with controlled nitrogen) added P91 steel after normalizing at 1050°C and 1150°C and tempered at 760°C were studied for the creep behavior in the base metal and welded condition in the temperature range of 600-650°C. Creep strength was characterized in terms of stress and temperature dependence of creep rate and rupture time. Weld creep life was reduced compared to the base metal with rupture occurring at the ICHAZ (Type IV crack). However at longer time (at lower stress levels) exposure creep crack moves from weld metal to HAZ (Type II crack). Rupture life was found to superior for the base and weld in the boron containing steel when higher normalizing temperature is used. Estimation of 105 h was attempted based on short term rupture data available and weld strength factors were calculated. Observed values are better for P91BH condition than the values for P91BLcondition as well as those available for P91 in open literature

  7. Comparative impact analysis of laser radiation on steel grades 1045 and 5140

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lobankova, Olga V., E-mail: lobankovaov@gmail.com, E-mail: zilyu@yandex.ru; Zykov, Ilya Y., E-mail: lobankovaov@gmail.com, E-mail: zilyu@yandex.ru; Melnikov, Alexander G., E-mail: melnikov-ag@tpu.ru

    2014-11-14

    There are results of experiments with deep engraving steel grades 1045 and 5140. The deep engraving was made by laser system equipped with a pulsed ytterbium fiber laser. The objectives of the work is to evaluate the change in the structure and properties of the material in the laser exposure area. Microsections of materials have been investigated and microhardness was measured for this purpose. The optimal parameters of laser material removal were considered. It is shown that various changes occur in the metal structure, which depends on the composition of the steel. In particular, when processing with identical laser parameters,more » tempered steel 1045 remelts and its hardness changes, while steel 5140 does not change its structure.« less

  8. Characterization of Anisotropic Behavior for High Grade Pipes

    NASA Astrophysics Data System (ADS)

    Yang, Kun; Huo, Chunyong; Ji, Lingkang; Li, Yang; Zhang, Jiming; Ma, Qiurong

    With the developing requirement of nature gas, the property needs of steel for pipe line are higher and higher, especially in strength and toughness. It is necessary to improve the steel grade in order to ensure economic demand and safety. However, with the rise of steel grade, the differences on properties in different orientations (anisotropic behaviors) become more and more obvious after the process of hot rolling, which may affect the prediction of fracture for the pipes seriously (Thinking of isotropic mechanical properties for material in traditional predict way). In order to get the reason for anisotropic mechanics, a series of tests are carried out for high grade steel pipes, including not only mechanical properties but also microstructures. Result indicates that there are obviously anisotropic behaviors for high grade steel pipes in two orientations (rolling orientation and transverse orientation). Strength is better in T orientation because Rm is higher and Rt 0.5 rises more in T orientation, and toughness is better in L orientation because of the higher Akv and SA in L orientation under a same temperature. Banded structures are formed in T orientation, and the spatial distribution of inclusion and precipitated phases are different in T, L and S orientation. The anisotropic arrangement for the matrix in space (banded structures), which is formed after the process of hot rolling, may affect the mechanical properties in different orientation. Moreover, the elasticity modulus of particles is different from the elasticity modulus of matrix, deformation between particles and matrix may cause stress concentration, and damage forms in this place. Because of the different distribution of particles in space, the level of damage is anisotropic in different orientations, and the anisotropic mechanical properties occur finally. Therefore, the anisotropic mechanical properties are determined by the anisotropic microstructures, both the anisotropic of matrix and the

  9. Effect of Long-Term Service on Microstructure and Mechanical Properties of Martensitic 9% Cr Steel

    NASA Astrophysics Data System (ADS)

    Golański, Grzegorz; Zielińska-Lipiec, Anna; Zieliński, Adam; Sroka, Marek

    2017-03-01

    The paper presents the results of research on the X10CrMoVNbN9-1 (T91) steel after long-term service. The material for testing was taken from a pipe section of a boiler superheater coil serviced for around 105,000 h at the temperature of 540 °C, at the pressure of 12.5 MPa. A quantitative analysis including the measurement of mean diameter of subgrains and precipitates as well as the density of dislocations of the examined steel was performed by means of TEM. The microscopic tests of T91 steel were complemented with the results of tests on mechanical properties which included also the short creep tests. After service, the investigated steel was characterized by a retained lath microstructure of tempered martensite with fine subgrain and quite large density of dislocations as well as numerous precipitates. In the microstructure, apart from the particles of M23C6 and MX (VX, NbC, V-wings), the precipitates of Laves phase and single particles of Z phase were revealed. It has been shown that the extent of degradation of the T91 steel microstructure was minor, which resulted from its low temperature of service. Performed tests of mechanical properties showed that these properties fulfilled the minimum requirements for this steel in the as-received condition. A favorable influence of fine precipitates of Laves phase on mechanical properties was observed. Moreover, an insignificant influence of single precipitates of Z phase on the creep resistance of the examined steel was stated.

  10. Investigation of the Microstructural, Mechanical and Corrosion Properties of Grade A Ship Steel-Duplex Stainless Steel Composites Produced via Explosive Welding

    NASA Astrophysics Data System (ADS)

    Kaya, Yakup; Kahraman, Nizamettin; Durgutlu, Ahmet; Gülenç, Behçet

    2017-08-01

    Grade A ship-building steel-AISI 2304 duplex stainless steel composite plates were manufactured via explosive welding. The AISI 2304 plates were used to clad the Grade A plates. Optical microscopy studies were conducted on the joining interface for characterization of the manufactured composite plates. Notch impact, tensile-shear, microhardness, bending and twisting tests were carried out to determine the mechanical properties of the composites. In addition, the surfaces of fractured samples were examined by scanning electron microscopy (SEM), and neutral salt spray (NSS) and potentiodynamic polarization tests were performed to examine corrosion behavior. Near the explosion zone, the interface was completely flat, but became wavy as the distance from the explosion zone increased. The notch impact tests indicated that the impact strength of the composites decreased with increasing distance from the explosion zone. The SEM studies detected brittle behavior below the impact transition temperature and ductile behavior above this temperature. Microhardness tests revealed that the hardness values increased with increasing distance from the explosion zone and mechanical tests showed that no visible cracking or separation had occurred on the joining interface. The NSS and potentiodynamic polarization tests determined that the AISI 2304 exhibited higher corrosion resistance than the Grade A steel.

  11. SPERTI Terminal Building (PER604). Concrete foundation is at grade. Steel ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SPERT-I Terminal Building (PER-604). Concrete foundation is at grade. Steel frame has been erected, and some siding has been affixed. Photographer: R.G. Larsen. Date: April 22, 1955. INEEL negative no. 55-1003 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  12. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  13. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  14. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  15. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  16. 49 CFR 192.109 - Nominal wall thickness (t) for steel pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Nominal wall thickness (t) for steel pipe. 192.109 Section 192.109 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND... Nominal wall thickness (t) for steel pipe. (a) If the nominal wall thickness for steel pipe is not known...

  17. Long-term creep characterization of Gr. 91 steel by modified creep constitutive equations

    NASA Astrophysics Data System (ADS)

    Kim, Woo-Gon; Kim, Sung-Ho; Lee, Chan-Bock

    2011-06-01

    This paper focuses on the long-term creep characterization of Gr. 91 steel using creep constitutive equations. The models of three such equations, a combination of power-law form and omega model (CPO), a combination of exponential form and omega model (CEO), and a combination of logarithmic form and omega model (CLO), which are described as sum decaying primary creep and accelerating tertiary creep, are proposed. A series of creep rupture data was obtained through creep tests with various applied loads at 600 °C. On the basis of the creep data, a nonlinear least-square fitting (NLSF) analysis was carried out to provide the best fit with the experimental data in optimizing the parameter constants of an individual equation. The results of the NLSF analysis showed that in the lower stress regions of 160 MPa (σ/σys <0.65), the CEO model showed a match with the experimental creep data comparable to those of the CPO and CLO models; however, in the higher stress regions of 160 MPa (σ/σy > 0.65), the CPO model showed better agreement than the other two models. It was found that the CEO model was superior to the CPO and CLO models in the modeling of long-term creep curves. Using the CEO model, the long-term creep curves of Gr. 91 steel were numerically characterized, and its creep life was predicted accurately.

  18. The effect of microstructure and strength on the fracture toughness of an 18 ni, 300 grade maraging steel

    NASA Technical Reports Server (NTRS)

    Psioda, J. A.; Low, J. R., Jr.

    1974-01-01

    Methods for increasing the strength of maraging steels are discussed. An investigation was conducted to systematically vary the strength of 18 weight percent nickel, 300 grade maraging steel, to isolate any attending microstructural changes, and to study the effects of these changes on the fracture toughness of the alloy. A study aimed at determining the aging behavior of the program alloy was carried out to provide data by which to estimate yield strength. The effects of various alloying materials on the strength of the maraging steel are examined. The mechanical properties of the 300 grade maraging steel were determined by tension tests, fatigue precracked Charpy impact tests, and plane strain fracture toughness tests.

  19. Steel tanks T5 and T4 with overhead pipeline between. Redwood ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Steel tanks T5 and T4 with overhead pipeline between. Redwood tanks seen in background - Hawaii Volcanoes National Park Water Collection System, Hawaii Volcanoes National Park, Volcano, Hawaii County, HI

  20. The effect of microstructure and strength on the fracture toughness of an 18 Ni, 300 grade maraging steel

    NASA Technical Reports Server (NTRS)

    Psioda, J. A.; Low, J. R., Jr.

    1975-01-01

    A 300 grade maraging steel was chosen as a vehicle by which to understand the inverse relationship between strength and toughness in high strength alloys such as the 18 Ni maraging steels. The 18 Ni, 300 grade maraging material was a commercial grade consumable-electrode, vacuum arc remelted heat obtained in the form of forged and annealed plate. The matrix contained a population of second-phase impurity inclusions which was a product of the casting and hot working processes. These inclusions did not change with subsequent precipitation hardening. Changes in microstructure resulting in strength increases were brought about by variations in aging temperature and time. Maximum strength was attained in the 300 grade maraging steel by aging at 427 C (800 F) for 100 hours. Tensile, fatigue precracked Charpy impact, and plane-strain fracture toughness tests were performed at room temperature, 20 C (68 F). With increasing strength the fracture toughness decreases as smaller and smaller inclusions act as sites for void initiation.

  1. Master Curve and Conventional Fracture Toughness of Modified 9Cr-1Mo Steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ji-Hyun, Yoon; Sung-Ho, Kim; Bong-Sang, Lee

    2006-07-01

    Modified 9Cr-1Mo steel is a primary candidate material for reactor pressure vessel of Very High Temperature Gas-Cooled Reactor (VHTR) in Korean Nuclear Hydrogen Development and Demonstration (NHDD) program. In this study, T0 reference temperature, J-R fracture resistance and Charpy impact properties were evaluated for commercial Grade 91 steel as preliminary tests for the selection of the RPV material for VHTR. The fracture toughness of the modified 9Cr-1Mo steel was compared with those of SA508-Gr.3. The objective of this study was to obtain pre-irradiation fracture toughness properties of modified 9Cr-1Mo steel as reference data for the radiation effects investigation. The resultsmore » are as follows. Charpy impact properties of the modified 9Cr-1Mo steel were similar to those of SA508-Gr.3. T0 reference temperatures were measured as -67.7 deg C and -72.4 deg C from the tests with standard PCVN (pre-cracked Charpy V-notch) and half sized PCVN specimens respectively, which were similar to results for SA508-Gr.3. The K{sub Jc} values of modified 9Cr-1Mo with test temperatures are successfully expressed with the Master Curve. The J-R fracture resistance of modified 9Cr-1Mo steel at room temperature was almost the same as that of SA508-Gr.3. On the other hand it was a little bit higher at an elevated temperature. (authors)« less

  2. Tribological performances of new steel grades for hot stamping tools

    NASA Astrophysics Data System (ADS)

    Medea, F.; Venturato, G.; Ghiotti, A.; Bruschi, S.

    2017-09-01

    In the last years, the use of High Strength Steels (HSS) as structural parts in car body-in-white manufacturing has rapidly increased thanks to their favourable strength-to-weight ratio and stiffness, which allow a reduction of the fuel consumption to accommodate the new restricted regulations for CO2 emissions control. The survey of the technical and scientific literature shows a large interest in the development of different coatings for the blanks from the traditional Al-Si up to new Zn-based coatings and on the analysis of hard PVD, CVD coatings and plasma nitriding applied on the tools. By contrast, fewer investigations have been focused on the development and test of new tools steels grades capable to improve the wear resistance and the thermal properties that are required for the in-die quenching during forming. On this base, the paper deals with the analysis and comparison the tribological performances in terms of wear, friction and heat transfer of new tool steel grades for high-temperature applications, characterized by a higher thermal conductivity than the commonly used tools. Testing equipment, procedures as well as measurements analyses to evaluate the friction coefficient, the wear and heat transfer phenomena are presented. Emphasis is given on the physical simulation techniques that were specifically developed to reproduce the thermal and mechanical cycles on the metal sheets and dies as in the industrial practice. The reference industrial process is the direct hot stamping of the 22MnB5 HSS coated with the common Al-Si coating for automotive applications.

  3. 21. Detail of steel ribs at south wall, T18; Note ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. Detail of steel ribs at south wall, T-18; Note composition of ribs--two steel channels welded together - Advance Base Depot Davisville, Building T-17, Ninth Street southeast of Davisville Road, Davisville, Washington County, RI

  4. 40 CFR 420.91 - Specialized definitions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... STANDARDS IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY Acid Pickling Subcategory § 420.91 Specialized definitions. (a) The term sulfuric acid pickling means those operations in which steel products are immersed... steel products are immersed in hydrochloric acid solutions to chemically remove oxides and scale, and...

  5. Study on the dynamic recrystallization model and mechanism of nuclear grade 316LN austenitic stainless steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Shenglong; Zhang, Mingxian; Wu, Huanchun

    In this study, the dynamic recrystallization behaviors of a nuclear grade 316LN austenitic stainless steel were researched through hot compression experiment performed on a Gleeble-1500 simulator at temperatures of 900–1250 °C and strain rates of 0.01–1 s{sup −1}. By multiple linear regressions of the flow stress-strain data, the dynamic recrystallization mathematical models of this steel as functions of strain rate, strain and temperature were developed. Then these models were verified in a real experiment. Furthermore, the dynamic recrystallization mechanism of the steel was determined. The results indicated that the subgrains in this steel are formed through dislocations polygonization and thenmore » grow up through subgrain boundaries migration towards high density dislocation areas and subgrain coalescence mechanism. Dynamic recrystallization nucleation performs in grain boundary bulging mechanism and subgrain growth mechanism. The nuclei grow up through high angle grain boundaries migration. - Highlights: •Establish the DRX mathematical models of nuclear grade 316LN stainless steel •Determine the DRX mechanism of this steel •Subgrains are formed through dislocations polygonization. •Subgrains grow up through subgrain boundaries migration and coalescence mechanism. •DRX nucleation performs in grain boundary bulging mechanism and subgrain growth mechanism.« less

  6. The Mechanical Property of Batch Annealed High Strength Low Alloy Steel HC260LA

    NASA Astrophysics Data System (ADS)

    Yang, Xiaojiang; Xia, Mingsheng; Zhang, Hongbo; Han, Bin; Li, Guilan

    Cold rolled high strength low alloy steel is widely applied in the automotive parts due to its excellent formability and weldability. In this paper, the steel grade HC260LA according to European Norm was developed with batch annealing process. With commercial C-Mn mild steel as a benchmark, three different groups of chemistry namely C-Mn-Si, C-Mn-Nb-Ti and C-Mn-Nb were compared in terms of yield-tensile strength (Y/T) ratio. Microstructure and mechanical properties were characterized as well. Based on industrial production results, chemistry and detailed process parameters for batch annealing were identified. In the end the optimal Y/T ratio was proposed for this steel grade under batch annealing process.

  7. Fabrication of thick multilayered steel structure using A516 Grade 70 by multipass friction stir welding †

    DOE PAGES

    Lim, Y. C.; Sanderson, S.; Mahoney, M.; ...

    2016-04-06

    Here, we fabricated a thick-sectioned multilayered steel structure by multipass friction stir welding on A516 Grade 70 steel. Tensile strength of the multilayered samples was comparable to that of the base metal. Failure was located in the base metal when a defect-free sample was tested. Charpy impact toughness was higher in the stir zone and heat affected zone than in the base metal. For higher microhardness values were found in the stir zone and heat affected zone than the base metal due to grain refinement and modification of the microstructures. As a result, improved mechanical properties compared to the basemore » metal were found in the weld zones of friction stir welded A516 Grade 70 steel.« less

  8. Characterization of Aging Behavior in M250 Grade Maraging Steel Using Ultrasonic Measurements

    NASA Astrophysics Data System (ADS)

    Rajkumar, K. V.; Kumar, Anish; Jayakumar, T.; Raj, Baldev; Ray, K. K.

    2007-02-01

    Ultrasonic measurements have been carried out in M250 grade maraging steel specimens subjected to solution annealing at 1093 K for 1 hour followed by aging at 755 K for various durations in the range of 0.25 to 100 hours. The influence of aging on microstructure, room temperature hardness, and ultrasonic parameters (longitudinal and shear wave velocities and Poisson’s ratio) has been studied in order to derive correlations among these parameters in aged M250 maraging steel. Both hardness and ultrasonic velocities exhibit almost similar behaviors with aging time. They increase with the precipitation of intermetallic phases, Ni3Ti and Fe2Mo, and decrease with the reversion of martensite to austenite. Ultrasonic shear wave velocity is found to be more influenced by the precipitation of intermetallic phases, whereas longitudinal wave velocity is influenced more by the reversion of martensite to austenite. Unlike hardness and ultrasonic velocities, the Poisson’s ratio exhibits a monotonous decrease with aging time and, hence, can be used for unambiguous monitoring of the aging process in M250 maraging steel. Further, none of the parameters, i.e., hardness, ultrasonic velocity, or Poisson’s ratio, alone could identify the initiation of the reversion of austenite at early stage; however, the same could be identified from the correlation between ultrasonic velocity and Poisson’s ratio, indicating the advantage of using the multiparametric approach for comprehensive characterization of complex aging behavior in M250 grade maraging steel.

  9. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Temperature derating factor (T) for steel pipe. 192.115 Section 192.115 Transportation Other Regulations Relating to Transportation (Continued... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in...

  10. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Temperature derating factor (T) for steel pipe. 192.115 Section 192.115 Transportation Other Regulations Relating to Transportation (Continued... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in...

  11. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Temperature derating factor (T) for steel pipe. 192.115 Section 192.115 Transportation Other Regulations Relating to Transportation (Continued... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in...

  12. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Temperature derating factor (T) for steel pipe. 192.115 Section 192.115 Transportation Other Regulations Relating to Transportation (Continued... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in...

  13. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Temperature derating factor (T) for steel pipe. 192.115 Section 192.115 Transportation Other Regulations Relating to Transportation (Continued... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in...

  14. Structure formation in grade 20 steel during equal-channel angular pressing and subsequent heating

    NASA Astrophysics Data System (ADS)

    Dobatkin, S. V.; Odesskii, P. D.; Raab, G. I.; Tyutin, M. R.; Rybalchenko, O. V.

    2016-11-01

    The structure formation and the mechanical properties of quenched and tempered grade 20 steel after equal-channel angular pressing (ECAP) at various true strains and 400°C are studied. Electron microscopy analysis after ECAP shows a partially submicrocrystalline and partially subgrain structure with a structural element size of 340-375 nm. The structural element size depends on the region in which the elements are formed (polyhedral ferrite, needle-shaped ferrite, tempered martensite, and pearlite). Heating of the steel after ECAP at 400 and 450°C increases the fraction of high-angle boundaries and the structural ferrite element size to 360-450 nm. The fragmentation and spheroidization of cementite lamellae of pearlite and subgrain coalescence in the regions of needle-shaped ferrite and tempered martensite take place at a high ECAP true strain and heating temperature. Structural refinement ensures considerable strengthening, namely, UTS 742-871 MPa at EL 11-15.3%. The strength slightly increases, whereas the plasticity slightly decreases when the true strain increases during ECAP. After ECAP and heating, the strength and plastic properties of the grade 20 steel remain almost the same.

  15. Ennoblement, corrosion, and biofouling in brackish seawater: Comparison between six stainless steel grades.

    PubMed

    Huttunen-Saarivirta, E; Rajala, P; Marja-Aho, M; Maukonen, J; Sohlberg, E; Carpén, L

    2018-04-01

    In this work, six common stainless steel grades were compared with respect to ennoblement characteristics, corrosion performance and tendency to biofouling in brackish sea water in a pilot-scale cooling water circuit. Two tests were performed, each employing three test materials, until differences between the materials were detected. Open circuit potential (OCP) was measured continuously in situ. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements were conducted before and after the tests. Exposed specimens were further subjected to examinations by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), and the biofouling was studied using epifluorescence microscopy, quantitative polymerase chain reaction (qPCR) and high-throughput sequencing (HTP sequencing). The results revealed dissimilarities between the stainless steel grades in corrosion behaviour and biofouling tendency. The test material that differed from the most of the other studied alloys was grade EN 1.4162. It experienced fastest and most efficient ennoblement of OCP, its passive area shrank to the greatest extent and the cathodic reaction was accelerated to a significant degree by the development of biofilm. Furthermore, microbiological analyses revealed that bacterial community on EN 1.4162 was dominated by Actinobacteria, whereas on the other five test materials Proteobacteria was the main bacterial phylum. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Study of microstress state of P91 steel using complementary mechanical Barkhausen, magnetoacoustic emission, and X-ray diffraction techniques

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Augustyniak, Bolesław, E-mail: bolek@mif.pg.gda.pl; Piotrowski, Leszek; Maciakowski, Paweł

    2014-05-07

    The paper deals with assessment of microstress state of martensite P91 steel using three complementary techniques: mechanical Barkhausen emission, magnetoacoustic emission (MAE), and X-ray diffraction (XRD) profile analysis. Magnetic coercivity Hc and microstructure were investigated with inductive magnetometry and magnetic force microscopy (MFM), respectively. Internal stress level of P91 steel was modified by heat treatment. Steel samples were austenitized, quenched, and then tempered at three temperatures (720 °C, 750 °C, and 780 °C) during increasing time (from 15 min up to 240 min). The microstrain level ε{sub i} was evaluated using Williamson–Hall method. It was revealed that during tempering microstrain systematically decreases from ε{sub i} = 2.5more » × 10{sup −3} for as quenched state down to ε{sub i} = 0.3 × 10{sup −3} for well tempered samples. Both mechanical hardness (Vicker's HV) and magnetic hardness (coercivity) decrease almost linearly with decreasing microstrain while the MAE and MBE intensities strongly increase. Tempering leads to evident shift of the MeBN intensity maximum recorded for the first load towards lower applied strain values and to increase of MAE intensity. This indicates that the microstress state deduced by magnetic techniques is correlated with microstrains evaluated with XRD technique.« less

  17. Proceedings of the Joint Seminar; Hydrogen Management in Steel Weldments, Melbourne, Australia, 23rd October 1996.

    DTIC Science & Technology

    1997-01-01

    Cr-Mo quenched and tempered (Q&T) steel . Both A723 Grade 1 and Grade 2 compositions were evaluated to determine the effects of strength, composition ...15] Craig, B., "Limitations of Alloying to Improve the Threshold for Hydrogen Stress Cracking of Steels ", Hydrogen Effects on Material Behavior ...considered are as follows: 1. Hydrogen mass transfer in steels and welded joints: analytical equipment; effect of element composition of weld metal and

  18. Hybrid Laser-Arc Welding Tanks Steels

    NASA Astrophysics Data System (ADS)

    Turichin, G.; Tsibulskiy, I.; Kuznetsov, M.; Akhmetov, A.; Klimova-Korsmik, O.

    2016-04-01

    The results investigate hybrid laser-arc welding of high strength steels using design responsible metallic construction and the highest strength body of vehicles. Welds from modern high strength steels grade Hardox 400, Hardox 450, Armox 600T and AB were created. High power fiber laser LS-15 with output 15 kW and arc rectifier VDU - 1500 DC were used in the experiment. Results of the metallographic research and mechanical tests are presented.

  19. Phase Separation in Lean Grade Duplex Stainless Steel 2101

    DOE PAGES

    Garfinkel, D.; Poplawsky, Jonathan D.; Guo, Wei; ...

    2015-08-19

    The use of duplex stainless steels (DSS) in nuclear power generation systems is limited by thermal instability that leads to embrittlement in the temperature range of 204°C - 538°C. New lean grade alloys, such as 2101, offer the potential to mitigate these effects. Thermal embrittlement was quantified through impact toughness and hardness testing on samples of alloy 2101 after aging at 427°C for various durations (1-10,000 hours). Additionally, atom probe tomography (APT) was utilized in order to observe the kinetics of α-α’ separation and G-phase formation. Mechanical testing and APT data for two other DSS alloys, 2003 and 2205 weremore » used as a reference to 2101. The results show that alloy 2101 exhibits superior performance compared to the standard grade DSS alloy, 2205, but inferior to the lean grade alloy, 2003, in mechanical testing. APT data demonstrates that the degree of α-α’ separation found in alloy 2101 closely resembles that of 2205, and greatly exceeds 2003. Additionally, contrary to what was observed in 2003, 2101 demonstrated G-phase like precipitates after long aging times, though precipitates were not as abundant as was observed in 2205.« less

  20. Transformations of Supercooled Austenite in a Promising High-Strength Steel Grade Under Continuous Cooling Conditions

    NASA Astrophysics Data System (ADS)

    Maisuradze, M. V.; Ryzhkov, M. A.; Yudin, Yu. V.; Kuklina, A. A.

    2017-11-01

    Special features of the transformations of supercooled austenite occurring under continuous cooling of a promising high-strength steel grade not standardized in the Russian Federation are determined. A method for evaluating the volume fractions of structure constituents formed in the steel as a result of cooling from 925°C at various constant rates within 0.025 - 75 K/sec is proposed and tested. The results are generalized in the form of a thermokinetic diagram of transformations of supercooled austenite.

  1. Behavior of ferritic/martensitic steels after n-irradiation at 200 and 300 °C

    NASA Astrophysics Data System (ADS)

    Matijasevic, M.; Lucon, E.; Almazouzi, A.

    2008-06-01

    High chromium ferritic/martensitic (F/M) steels are considered as the most promising structural materials for accelerator driven systems (ADS). One drawback that needs to be quantified is the significant hardening and embrittlement caused by neutron irradiation at low temperatures with production of spallation elements. In this paper irradiation effects on the mechanical properties of F/M steels have been studied and comparisons are provided between two ferritic/martensitic steels, namely T91 and EUROFER97. Both materials have been irradiated in the BR2 reactor of SCK-CEN/Mol at 300 °C up to doses ranging from 0.06 to 1.5 dpa. Tensile tests results obtained between -160 °C and 300 °C clearly show irradiation hardening (increase of yield and ultimate tensile strengths), as well as reduction of uniform and total elongation. Irradiation effects for EUROFER97 starting from 0.6 dpa are more pronounced compared to T91, showing a significant decrease in work hardening. The results are compared to our latest data that were obtained within a previous program (SPIRE), where T91 had also been irradiated in BR2 at 200 °C (up to 2.6 dpa), and tested between -170 °C and 300 °C. Irradiation effects at lower irradiation temperatures are more significant.

  2. Evaluation of Cavitation Erosion Behavior of Commercial Steel Grades Used in the Design of Fluid Machinery

    NASA Astrophysics Data System (ADS)

    Tzanakis, I.; Bolzoni, L.; Eskin, D. G.; Hadfield, M.

    2017-05-01

    The erosion response under cavitation of different steel grades was assessed by studying the erosion rate, the volume removal, the roughness evolution, and the accumulated strain energy. A 20 kHz ultrasonic transducer with a probe diameter of 5 mm and peak-to-peak amplitude of 50 μm was deployed in distilled water to induce damage on the surface of commercial chromium and carbon steel samples. After a relatively short incubation period, cavitation induced the formation of pits, cracks, and craters whose features strongly depended on the hardness and composition of the tested steel. AISI 52100 chromium steel showed the best performance and is, therefore, a promising design candidate for replacing the existing fluid machinery materials that operate within potential cavitating environments.

  3. Precipitation and Dislocation Strengthening Behaviour of Grade X80 Steel for Pipeline with Strain Based Design

    NASA Astrophysics Data System (ADS)

    Sun, Weihua; Hu, Shu-e.; Li, Guobao; Yu, Hao

    This paper analyzes precipitation and dislocation strengthening behaviors of a 27mm thick Niobium-bearing Grade X80 steel plate for strain based design line pipe manufacture. The steel is produced by thermal-mechanical processing (TMCP) and is characterized with granular bainite and polygonal ferrite microstructure. Mechanical properties of both the steel and the UOE pipe are briefly introduced. Transmission electron microscope (TEM) is used to investigate the fine grain structure, distribution of the precipitates and dislocations in the steel. Precipitate morphologies, volume fractions of M(C,N), M3C, CaS, AlN and Cu are extensively studied respectively by Electrolytic Chemical Phase Analysis (ECPA) and X-ray Small Angle Diffraction (X-ray SAD). Dislocations in the steel are characterized with Positron Annihilation analysis. The results prove that precipitation hardening reveal a 58.1MPa strengthening contribution by the precipitates less than 20nm in size. Dislocation hardening is approximately 176MPa to the present studied steel and 198MPa to the pipe.

  4. Effect of Pulse Detonation-Plasma Technology Treatment on T8 Steel Microstructures

    NASA Astrophysics Data System (ADS)

    Yu, Jiuming; Zhang, Linwei; Liu, Keming; Lu, Lei; Lu, Deping; Zhou, Haitao

    2017-12-01

    T8 steel surfaces were treated by pulse detonation-plasma technology (PDT) at capacitance values of 600, 800, and 1000 μF, and the effects of PDT were analyzed using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron back-scattered diffraction, and micro-hardness tester and friction wear tester. The surface of T8 steel is first smoothed out, and then, craters are formed due to the inhomogeneity of the PDT energy and targeting during PDT treatment. The initial martensite in the T8 steel surface layer changes to austenite, and Fe3N is formed due to nitriding. The thickness of the modified layer, which is composed of columnar and fine grain structures, increases with the increasing capacity. Preferential orientation occurred in the {110} 〈 001 〉 direction in the modified layer, and the number of low-angle grain boundaries increased significantly after PDT treatment. The micro-hardness and wear resistance of the T8 steel was improved by PDT treatment, even doubled after the treatment with the capacitance of 1000 μF.

  5. Cycles for Science: Biology Curriculum Supplement for Grades 9-12. A Steel Cycles Program.

    ERIC Educational Resources Information Center

    Rogers, Diana; Laymon, Carol

    This document contains project-oriented lessons and hands-on activities developed to integrate steel recycling, natural resource conservation, and solid waster management into science learning. It is designed to assist secondary teachers and students (grades 9-12) in meeting state and local goals for learning in biology, chemistry, general science…

  6. Study of biocompatibility of medical grade high nitrogen nickel-free austenitic stainless steel in vitro.

    PubMed

    Li, Menghua; Yin, Tieying; Wang, Yazhou; Du, Feifei; Zou, Xingzheng; Gregersen, Hans; Wang, Guixue

    2014-10-01

    Adverse effects of nickel ions being released into the living organism have resulted in development of high nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also improves steel properties. The cell cytocompatibility, blood compatibility and cell response of high nitrogen nickel-free austenitic stainless steel were studied in vitro. The mechanical properties and microstructure of this stainless steel were compared to the currently used 316L stainless steel. It was shown that the new steel material had comparable basic mechanical properties to 316L stainless steel and preserved the single austenite organization. The cell toxicity test showed no significant toxic side effects for MC3T3-E1 cells compared to nitinol alloy. Cell adhesion testing showed that the number of MC3T3-E1 cells was more than that on nitinol alloy and the cells grew in good condition. The hemolysis rate was lower than the national standard of 5% without influence on platelets. The total intracellular protein content and ALP activity and quantification of mineralization showed good cell response. We conclude that the high nitrogen nickel-free austenitic stainless steel is a promising new biomedical material for coronary stent development. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Histogram analysis of T2*-based pharmacokinetic imaging in cerebral glioma grading.

    PubMed

    Liu, Hua-Shan; Chiang, Shih-Wei; Chung, Hsiao-Wen; Tsai, Ping-Huei; Hsu, Fei-Ting; Cho, Nai-Yu; Wang, Chao-Ying; Chou, Ming-Chung; Chen, Cheng-Yu

    2018-03-01

    To investigate the feasibility of histogram analysis of the T2*-based permeability parameter volume transfer constant (K trans ) for glioma grading and to explore the diagnostic performance of the histogram analysis of K trans and blood plasma volume (v p ). We recruited 31 and 11 patients with high- and low-grade gliomas, respectively. The histogram parameters of K trans and v p , derived from the first-pass pharmacokinetic modeling based on the T2* dynamic susceptibility-weighted contrast-enhanced perfusion-weighted magnetic resonance imaging (T2* DSC-PW-MRI) from the entire tumor volume, were evaluated for differentiating glioma grades. Histogram parameters of K trans and v p showed significant differences between high- and low-grade gliomas and exhibited significant correlations with tumor grades. The mean K trans derived from the T2* DSC-PW-MRI had the highest sensitivity and specificity for differentiating high-grade gliomas from low-grade gliomas compared with other histogram parameters of K trans and v p . Histogram analysis of T2*-based pharmacokinetic imaging is useful for cerebral glioma grading. The histogram parameters of the entire tumor K trans measurement can provide increased accuracy with additional information regarding microvascular permeability changes for identifying high-grade brain tumors. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Development in high-grade dual phase steels with low C and Si design

    NASA Astrophysics Data System (ADS)

    Zhu, Guo-hui; Zhang, Xue-hui; Mao, Wei-min

    2009-12-01

    Cold rolled dual phase steels with low C and Si addition were investigated in terms of combination of composition and processing in order to improve mechanical properties and workability including welding and galvanizing. Mo and Cr could be used as alloying elements to partially replace C and Si to assure enough hardening ability of the steels and also give solute-hardening. Mo addition is more effective than Cr addition in terms of obtaining the required volume fraction of martensite and mechanical strength. The ferrite grain was effectively refined by addition of Nb microalloying, which gives optimized mechanical properties. The experimental results show that it is possible to obtain the required mechanical properties of high grade 800 MPa dual phase steel, i.e., tensile strength > 780 MPa, elongation > 15%, and yield/tensile strength ratio < 0.6 in the condition of low carbon (C < 0.11 wt.%) and low silicon design (Si < 0.05 wt.%) through adequate combination of composition and processing.

  9. Effects of aggregate grading on the properties of steel fibre-reinforced concrete

    NASA Astrophysics Data System (ADS)

    Acikgens Ulas, M.; Alyamac, K. E.; Ulucan, Z. C.

    2017-09-01

    This study investigates the effects of changing the aggregate grading and maximum aggregate size (D max ) on the workability and mechanical properties of steel fibre-reinforced concrete (SFRC). Four different gradations and two different D max were used to produce SFRC mixtures with constant cement dosages and water/cement ratios. Twelve different concrete series were tested. To observe the properties of fresh concrete, slump and Ve-Be tests were performed immediately after the mixing process to investigate the effects of time on workability. The hardened properties, such as the compressive, splitting tensile and flexural strengths, were also evaluated. In addition, the toughness of the SFRC was calculated. Based on our test results, we can conclude that the grading of the aggregate and the D max have remarkable effects on the properties of fresh and hardened SFRC. In addition, the toughness of the SFRC was influenced by changing the grading of the aggregate and the D max .

  10. Effect of Groove Design and Post-Weld Heat Treatment on Microstructure and Mechanical Properties of P91 Steel Weld

    NASA Astrophysics Data System (ADS)

    Pandey, C.; Mahapatra, M. M.

    2016-07-01

    The martensitic creep-resistant steel designated as ASTM A335 for plate and as P91 for pipe is primarily used for high-temperature and high-pressure applications in steam power plants due to its excellent high-temperature properties such as high creep strength, high thermal conductivity, low thermal expansion, and so on. However, in the case of welded joints of such steels, the presence of an inter-critical heat-affected zone (IC-HAZ) can cause the joint to have lower creep strength than the base metal. In the present study, the effect of post-welding heat treatment (PWHT) and weld groove designs on the overall microstructure and mechanical properties of P91 steel pipe welds produced by the gas tungsten arc welding process was studied. Various regions of welded joints were characterized in detail for hardness and metallographic and tensile properties. Sub-size tensile samples were also tested to evaluate the mechanical properties of the weld metal and heat-affected zone (HAZ) with respect to PWHT. After PWHT, a homogenous microstructure was observed in the HAZ and tensile test fracture samples revealed shifting of the fracture location from the IC-HAZ to the fine-grained heat-affected zone. Before PWHT, the conventional V-grooved welded joints exhibited higher tensile strength compared to the narrow-grooved joints. However, after PWHT, both narrow- and V-grooved joints exhibited similar strength. Fractography of the samples indicates the presence of carbide precipitates such as Cr23C6, VC, and NbC on the fracture surface.

  11. Microstructure-property relationships and constitutive response of plastically graded case hardened steels

    NASA Astrophysics Data System (ADS)

    Klecka, Michael A.

    Case hardened materials, popularly used in many demanding engineering applications such as bearings, gears, and wear/impact surfaces, have high surface hardness and a gradient in material properties (hardness, yield strength, etc.) as a function of depth; therefore, they behave as plastically graded materials. In the current study, two different commercially available case carburized steels along with two through hardened steels are characterized to obtain relationships among the volume fraction of subsurface carbides, indentation hardness, elastic modulus, and yield strength as a function of depth. A variety of methods including microindentation, nanoindentation, ultrasonic measurements, compression testing, rule of mixtures, and upper and lower bound models are used to determine the relationships for elastic modulus and compare the experimental results with model predictions. In addition, the morphology, composition, and properties of the carbide particles are also determined. The gradient in hardness with depth in graded materials is commonly determined using microindentation on the cross-section of the material which contains the gradation in microstructure or composition. In the current study, a novel method is proposed to predict the hardness gradient profile using solely surface indentations at a range of loads. The method does not require the graded material to be sectioned, and has practical utility in the surface heat-treatment industry. For a material with a decreasing gradient in hardness, higher indent loads result in a lower measured hardness due to the influence of the softer subsurface layers. A power-law model is presented which relates the measured surface indentation hardness under increasing load to the subsurface gradient in hardness. A coordinated experimental and numerical study is presented to extract the constitutive response of graded materials, utilizing relationships between hardness, plastic deformation, and strain hardening response

  12. Microstructural Characterization of the Heat-Affected Zones in Grade 92 Steel Welds: Double-Pass and Multipass Welds

    NASA Astrophysics Data System (ADS)

    Xu, X.; West, G. D.; Siefert, J. A.; Parker, J. D.; Thomson, R. C.

    2018-04-01

    The microstructure in the heat-affected zone (HAZ) of multipass welds typical of those used in power plants and made from 9 wt pct chromium martensitic Grade 92 steel is complex. Therefore, there is a need for systematic microstructural investigations to define the different regions of the microstructure across the HAZ of Grade 92 steel welds manufactured using the traditional arc welding processes in order to understand possible failure mechanisms after long-term service. In this study, the microstructure in the HAZ of an as-fabricated two-pass bead-on-plate weld on a parent metal of Grade 92 steel has been systematically investigated and compared to a complex, multipass thick section weldment using an extensive range of electron and ion-microscopy-based techniques. A dilatometer has been used to apply controlled thermal cycles to simulate the microstructures in distinctly different regions in a multipass HAZ using sequential thermal cycles. A wide range of microstructural properties in the simulated materials were characterized and compared with the experimental observations from the weld HAZ. It has been found that the microstructure in the HAZ can be categorized by a combination of sequential thermal cycles experienced by the different zones within the complex weld metal, using the terminology developed for these regions based on a simpler, single-pass bead-on-plate weld, categorized as complete transformation, partial transformation, and overtempered.

  13. Toward Improving the Type IV Cracking Resistance in Cr-Mo Steel Weld Through Thermo-Mechanical Processing

    DOE PAGES

    Shassere, Benjamin A.; Yamamoto, Yukinori; Babu, Sudarsanam Suresh

    2016-02-23

    Detailed microstructure characterization of Grade 91 (Modified 9Cr-1Mo, ASTM A387) steel subjected to a thermo-mechanical treatment (TMT) process was performed to rationalize the cross-weld creep properties. A series of thermo-mechanical processing in the austenite phase region, followed by isothermal aging at temperatures at 973 to 1173 K (700 to 900ºC) was applied to the Grade 91 steel to promote precipitation kinetics of MX (M: Nb and V, X: C and N) in the austenite matrix. Detailed characterization of the base metals after standard tempering confirmed the presence of fine MX dispersion within the tempered martensitic microstructure in steels processed at/andmore » above 1073 K (800 ºC). Relatively low volume fraction of M 23C 6 precipitates was observed after processing at 1073 K (800 ºC). The cross-weld creep strength after processing was increased with respect to the increase of MX dispersion, indicating that these MX precipitates maintained during weld thermal cycles in the fine grained heat affected zone (FGHAZ) region and thereby contribute to improved creep resistant of welds in comparison to the welds made with the standard “normalization and tempering” processes. Lastly, the steels processed in this specific processing condition showed improved cross-weld creep resistance and sufficient room-temperature toughness. The above data is also analysed based on existing theories of creep deformation based on dislocation climb mechanism.« less

  14. Toward Improving the Type IV Cracking Resistance in Cr-Mo Steel Weld Through Thermo-Mechanical Processing

    NASA Astrophysics Data System (ADS)

    Shassere, Benjamin A.; Yamamoto, Yukinori; Babu, Sudarsanam Suresh

    2016-05-01

    Detailed microstructure characterization of Grade 91 (Modified 9Cr-1Mo, ASTM A387) steel subjected to a thermo-mechanical treatment process was performed to rationalize the cross-weld creep properties. A series of thermo-mechanical processing in the austenite phase region, followed by isothermal aging at temperatures at 973 K to 1173 K (700 °C to 900 °C), was applied to the Grade 91 steel to promote precipitation kinetics of MX (M: Nb and V, X: C and N) in the austenite matrix. Detailed characterization of the base metals after standard tempering confirmed the presence of fine MX dispersion within the tempered martensitic microstructure in steels processed at/and above 1073 K (800 °C). Relatively low volume fraction of M23C6 precipitates was observed after processing at 1073 K (800 °C). The cross-weld creep strength after processing was increased with respect to the increase of MX dispersion, indicating that these MX precipitates maintained during weld thermal cycles in the fine-grained heat-affected zone region and thereby contribute to improved creep resistant of welds in comparison to the welds made with the standard "normalization and tempering" processes. The steels processed in this specific processing condition showed improved cross-weld creep resistance and sufficient room temperature toughness. The above data are also analyzed based on existing theories of creep deformation based on dislocation climb mechanism.

  15. Toward Improving the Type IV Cracking Resistance in Cr-Mo Steel Weld Through Thermo-Mechanical Processing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shassere, Benjamin A.; Yamamoto, Yukinori; Babu, Sudarsanam Suresh

    Detailed microstructure characterization of Grade 91 (Modified 9Cr-1Mo, ASTM A387) steel subjected to a thermo-mechanical treatment (TMT) process was performed to rationalize the cross-weld creep properties. A series of thermo-mechanical processing in the austenite phase region, followed by isothermal aging at temperatures at 973 to 1173 K (700 to 900ºC) was applied to the Grade 91 steel to promote precipitation kinetics of MX (M: Nb and V, X: C and N) in the austenite matrix. Detailed characterization of the base metals after standard tempering confirmed the presence of fine MX dispersion within the tempered martensitic microstructure in steels processed at/andmore » above 1073 K (800 ºC). Relatively low volume fraction of M 23C 6 precipitates was observed after processing at 1073 K (800 ºC). The cross-weld creep strength after processing was increased with respect to the increase of MX dispersion, indicating that these MX precipitates maintained during weld thermal cycles in the fine grained heat affected zone (FGHAZ) region and thereby contribute to improved creep resistant of welds in comparison to the welds made with the standard “normalization and tempering” processes. Lastly, the steels processed in this specific processing condition showed improved cross-weld creep resistance and sufficient room-temperature toughness. The above data is also analysed based on existing theories of creep deformation based on dislocation climb mechanism.« less

  16. EVALUATION OF SPECIFICATION RANGES FOR CREEP STRENGTH ENHANCED FERRITIC STEELS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shingledecker, John P; Santella, Michael L; Wilson, Keely A

    2008-01-01

    Creep Strength Enhanced Ferritic Steels (CSEF) such as Gr. 91, 911, 92, and 122 require a fully martensitic structure for optimum properties, mainly good creep strength. However, broad chemical compositional ranges are specified for these steel grades which can strongly influence the microstructures obtained. In this study, we have produced chemical compositions within the specification ranges for these alloys which intentionally cause the formation of ferrite or substantially alter the lower intercritical temperatures (A1) so as to affect the phase transformation behavior during tempering. Thermodynamic modeling, thermo-mechanical simulation, tensile testing, creep testing, and microstructural analysis were used to evaluate thesemore » materials. The results show the usefulness of thermodynamic calculations for setting rational chemical composition ranges for CSEF steels to control the critical temperatures, set heat-treatment temperature limits, and eliminate the formation of ferrite.« less

  17. Development and Application of High Performance Quenched and Tempered Wear Resistant Steels in Material Handling and Construction Machinery

    NASA Astrophysics Data System (ADS)

    Su, Fenwei; Sidiras, Evangelos

    The demand for more sustainable development promotes the need for components and steel structures with a longer useful life and better performance. Upgrade of wear steel plate used in key industry segments such as mining, recycling and road building results in the stable growth of global market with high quality grade Q&T wear plates (Hardness HBW≥400, and Yield strength ≥690 Mpa). SSAB has now expanded its wear steel product range by both thicker and thinner Q&T plate to meet the needs of the market, and can offer wear plates from 0.7 mm to 160 mm. The continuous research and development is being done to offer even thicker plates. This article introduces the performance and advantages of high quality grade Q&T wear resistant steel products (plate, strip, tube and round bars) produced in SSAB, and also describes typical applications in some industrial segments such as material handling and construction machinery.

  18. Spinodal Decomposition in Functionally Graded Super Duplex Stainless Steel and Weld Metal

    NASA Astrophysics Data System (ADS)

    Hosseini, Vahid A.; Thuvander, Mattias; Wessman, Sten; Karlsson, Leif

    2018-04-01

    Low-temperature phase separations (T < 500 °C), resulting in changes in mechanical and corrosion properties, of super duplex stainless steel (SDSS) base and weld metals were investigated for short heat treatment times (0.5 to 600 minutes). A novel heat treatment technique, where a stationary arc produces a steady state temperature gradient for selected times, was employed to fabricate functionally graded materials. Three different initial material conditions including 2507 SDSS, remelted 2507 SDSS, and 2509 SDSS weld metal were investigated. Selective etching of ferrite significantly decreased in regions heat treated at 435 °C to 480 °C already after 3 minutes due to rapid phase separations. Atom probe tomography results revealed spinodal decomposition of ferrite and precipitation of Cu particles. Microhardness mapping showed that as-welded microstructure and/or higher Ni content accelerated decomposition. The arc heat treatment technique combined with microhardness mapping and electrolytical etching was found to be a successful approach to evaluate kinetics of low-temperature phase separations in SDSS, particularly at its earlier stages. A time-temperature transformation diagram was proposed showing the kinetics of 475 °C-embrittlement in 2507 SDSS.

  19. Spinodal Decomposition in Functionally Graded Super Duplex Stainless Steel and Weld Metal

    NASA Astrophysics Data System (ADS)

    Hosseini, Vahid A.; Thuvander, Mattias; Wessman, Sten; Karlsson, Leif

    2018-07-01

    Low-temperature phase separations (T < 500 °C), resulting in changes in mechanical and corrosion properties, of super duplex stainless steel (SDSS) base and weld metals were investigated for short heat treatment times (0.5 to 600 minutes). A novel heat treatment technique, where a stationary arc produces a steady state temperature gradient for selected times, was employed to fabricate functionally graded materials. Three different initial material conditions including 2507 SDSS, remelted 2507 SDSS, and 2509 SDSS weld metal were investigated. Selective etching of ferrite significantly decreased in regions heat treated at 435 °C to 480 °C already after 3 minutes due to rapid phase separations. Atom probe tomography results revealed spinodal decomposition of ferrite and precipitation of Cu particles. Microhardness mapping showed that as-welded microstructure and/or higher Ni content accelerated decomposition. The arc heat treatment technique combined with microhardness mapping and electrolytical etching was found to be a successful approach to evaluate kinetics of low-temperature phase separations in SDSS, particularly at its earlier stages. A time-temperature transformation diagram was proposed showing the kinetics of 475 °C-embrittlement in 2507 SDSS.

  20. Effect of welding on creep damage evolution in P91B steel

    NASA Astrophysics Data System (ADS)

    Baral, J.; Swaminathan, J.; Chakrabarti, D.; Ghosh, R. N.

    2017-07-01

    Study of creep behavior of base metal (without weld) and welded specimens of P91B steel over a range of temperatures (600-650 °C) and stresses (50-180 MPa) showed similar values of minimum creep-rates for both specimens at higher stress regime (>100 MPa) whilst, significantly higher creep rates in the case of welded specimens at lower stress regime. Considering that welded specimen is comprised of two distinct structural regimes, i.e. weld affected zone and base metal, a method has been proposed for estimating the material parameters describing creep behavior of those regimes. Stress-strain distribution across welded specimen predicted from finite element analysis based on material parameters revealed preferential accumulation of stress and creep strain at the interface between weld zone and base metal. This is in-line with the experimental finding that creep rupture preferentially occurs at inter-critical heat affected zone in welded specimens owing to ferrite-martensite structure with coarse Cr23C6 particles.

  1. Microstructural Evolution and Constitutive Relationship of M350 Grade Maraging Steel During Hot Deformation

    NASA Astrophysics Data System (ADS)

    Chakravarthi, K. V. A.; Koundinya, N. T. B. N.; Narayana Murty, S. V. S.; Nageswara Rao, B.

    2017-03-01

    Maraging steels exhibit extraordinary strength coupled with toughness and are therefore materials of choice for critical structural applications in defense, aerospace and nuclear engineering. Thermo-mechanical processing is an important step in the manufacture of these structural components. This process assumes significance as these materials are expensive and the mechanical properties obtained depend on the microstructure evolved during thermo-mechanical processing. In the present study, M350 grade maraging steel specimens were hot isothermally compressed in the temperature range of 900-1200 °C and in the strain rate range of 0.001-100 s-1, and true stress-true strain curves were generated. The microstructural evolution as a function of strain rate and temperature in the deformed compression specimens was studied. The effect of friction between sample and compression dies was evaluated, and the same was found to be low. The measured flow stress data was used for the development of a constitutive model to represent the hot deformation behavior of this alloy. The proposed equation can be used as an input in the finite element analysis to obtain the flow stress at any given strain, strain rate, and temperature useful for predicting the flow localization or fracture during thermo-mechanical simulation. The activation energy for hot deformation was calculated and is found to be 370.88 kJ/mol, which is similar to that of M250 grade maraging steel.

  2. Biomechanics of bone-fracture fixation by stiffness-graded plates in comparison with stainless-steel plates

    PubMed Central

    Ganesh, VK; Ramakrishna, K; Ghista, Dhanjoo N

    2005-01-01

    Background In the internal fixation of fractured bone by means of bone-plates fastened to the bone on its tensile surface, an on-going concern has been the excessive stress-shielding of the bone by the excessively-stiff stainless-steel plate. The compressive stress-shielding at the fracture-interface immediately after fracture-fixation delays callus formation and bone healing. Likewise, the tensile stress-shielding of the layer of the bone underneath the plate can cause osteoporosis and decrease in tensile strength of this layer. Method In order to address this problem, we propose to use stiffness-graded plates. Accordingly, we have computed (by finite-element analysis) the stress distribution in the fractured bone fixed by composite plates, whose stiffness is graded both longitudinally and transversely. Results It can be seen that the stiffness-graded composite-plates cause less stress-shielding (as an example: at 50% of the healing stage, stress at the fracture interface is compressive in nature i.e. 0.002 GPa for stainless steel plate whereas stiffness graded plates provides tensile stress of 0.002 GPa. This means that stiffness graded plate is allowing the 50% healed bone to participate in loadings). Stiffness-graded plates are more flexible, and hence permit more bending of the fractured bone. This results in higher compressive stresses induced at the fractured faces accelerate bone-healing. On the other hand, away from the fracture interface the reduced stiffness and elastic modulus of the plate causes the neutral axis of the composite structure to be lowered into the bone resulting in the higher tensile stress in the bone-layer underneath the plate, wherein is conducive to the bone preserving its tensile strength. Conclusion Stiffness graded plates (with in-built variable stiffness) are deemed to offer less stress-shielding to the bone, providing higher compressive stress at the fractured interface (to induce accelerated healing) as well as higher tensile

  3. An investigation of the plastic fracture of AISI 4340 and 18 nickel - 200 grade maraging steels

    NASA Technical Reports Server (NTRS)

    Cox, T. B.; Low, J. R., Jr.

    1974-01-01

    The mechanisms of plastic fracture (dimpled rupture) in high-purity and commercial 18 Ni, 200 grade maraging steels and quenched and tempered AISI 4340 steels have been studied. Plastic fracture takes place in the maraging alloys through void initiation by fracture of titanium carbo-nitride inclusions and the growth of these voids until impingement results in coalescence and final fracture. The fracture of AISI 4340 steel at a yield strength of 200 ksi occurs by nucleation and subsequent growth of voids formed by fracture of the interface between manganese sulfide inclusions and the matrix. The growth of these inclusion-nucleated voids is interrupted long before coalescence by impingement, by the formation of void sheets which connect neighboring sulfide-nucleated voids.

  4. Hot Deformation Behavior of As-Cast 2101 Grade Lean Duplex Stainless Steel and the Associated Changes in Microstructure and Crystallographic Texture

    NASA Astrophysics Data System (ADS)

    Patra, Sudipta; Ghosh, Abhijit; Singhal, Lokesh Kumar; Podder, Arijit Saha; Sood, Jagmohan; Kumar, Vinod; Chakrabarti, Debalay

    2017-01-01

    The hot deformation behavior of 2101 grade lean duplex stainless steel (DSS, containing 5 wt pct Mn, 0.2 wt pct N, and 1.4 wt pct Ni) and associated microstructural changes within δ-ferrite and austenite ( γ) phases were investigated by hot-compression testing in a GLEEBLE 3500 simulator over a range of deformation temperatures, T def [1073 K to 1373 K (800 °C to 1100 °C)], and applied strains, ɛ (0.25 to 0.80), at a constant true strain rate of 1/s. The microstructural softening inside γ was dictated by discontinuous dynamic recrystallization (DDRX) at a higher T def [1273 K to 1373 K (1000 °C to 1100 °C)], while the same was dictated by continuous dynamic recrystallization (CDRX) at a lower T def (1173 K (900 °C)]. Dynamic recovery (DRV) and CDRX dominated the softening inside δ-ferrite at T def ≥ 1173 K (900 °C). The dynamic recrystallization (DRX) inside δ and γ could not take place upon deformation at 1073 K (800 °C). The average flow stress level increased 2 to 3 times as the T def dropped from 1273 to 1173 K (1000 °C to 900 °C) and finally to 1073 K (800 °C). The average microhardness values taken from δ-ferrite and γ regions of the deformed samples showed a different trend. At T def of 1373 K (1100 °C), microhardness decreased with the increase in strain, while at T def of 1173 K (900 °C), microhardness increased with the increase in strain. The microstructural changes and hardness variation within individual phases of hot-deformed samples are explained in view of the chemical composition of the steel and deformation parameters ( T def and ɛ).

  5. Study of the continuous corrosion in an oxidation environment derived from the theoretical combustion products in a refinery. Case study: Ferritic steel ASTM A335 P91

    NASA Astrophysics Data System (ADS)

    Alviz Meza, A.; Kafarov, V.; Y Peña Ballesteros, D.

    2017-12-01

    Corrosion studies are key element that ensure the correct functioning of equipment in the industrial sector. The oxidation phenomena were evaluated, taking as a case study steel ASTM A335 P91 (P91), a steel of typical use in equipment that work at high temperatures. Five (5) exposure times were selected for the experimental development: 1, 20, 50, 100 and 200h; as well as four (4) analysis temperatures: 450, 550, 650 and 750°C. Through the metallographic analysis was possible to evidence the presence of multiple carbide precipitates and a ferritic structure, after all the temperatures tested. On the other hand, the analysis of hardness and microhardness showed an increase for all the evaluated temperatures. These increases were mainly related to the precipitation of carbides in the coupons of P91. Regarding to the chemical analysis, it was possible to conclude that after 200h of experimentation in each temperature, a layer of duplex oxide, composed mainly of hematite, magnetite and spinel iron-chromium, was formed in the O2/H2O atmosphere. Finally, the kinetic study demonstrated that the oxide layer formed on each coupon of P91 was of protective character.

  6. Compatibility tests of steels in flowing liquid lead-bismuth

    NASA Astrophysics Data System (ADS)

    Barbier, F.; Benamati, G.; Fazio, C.; Rusanov, A.

    2001-06-01

    The behaviour of steels exposed to flowing Pb-55Bi was evaluated. The materials tested are the two austenitic steels AISI 316L and 1.4970, and the six martensitic steels Optifer IVc, T91, Batman 27, Batman 28, EP823 and EM10 which were exposed to flowing Pb-55Bi for 1000, 2000 and 3000 h and at two temperatures (573 and 743 K). The corrosion tests were conducted in the non-isothermal loop of IPPE-Obninsk under a controlled oxygen level (10 -6 wt%). The compatibility study showed that at a lower temperature, a very thin oxide layer (<1 μm) was formed on the steels. At higher temperature, austenitic steels also exhibited a thin oxide layer sufficient to prevent their dissolution in the melt. A thicker oxide, which grew according to a parabolic law, was observed on the surface of the martensitic steels. The oxidation resistance behaviour of the martensitic steels was correlated with their alloying elements.

  7. High Temperature Oxidation of Hot-Dip Aluminized T92 Steels

    NASA Astrophysics Data System (ADS)

    Abro, Muhammad Ali; Hahn, Junhee; Lee, Dong Bok

    2018-03-01

    The T92 steel plate was hot-dip aluminized, and oxidized in order to characterize the high-temperature oxidation behavior of hot-dip aluminized T92 steel. The coating consisted of Al-rich topcoat with scattered Al3Fe grains, Al3Fe-rich upper alloy layer with scattered (Al, Al5Fe2, AlFe)-grains, and Al5Fe2-rich lower alloy layer with scattered (Al5Fe2, AlFe)-grains. Oxidation at 800 °C for 20 h formed (α-Al2O3 scale)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer), while oxidation at 900 °C for 20 h formed (α-Al2O3 scale plus some Fe2O3)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer) from the surface. During oxidation, outward migration of all substrate elements, inward diffusion of oxygen, and back and forth diffusion of Al occurred according to concentration gradients. Also, diffusion transformed and broadened AlFe and AlFe3 layers dissolved with some oxygen and substrate alloying elements. Hot-dip aluminizing improved the high-temperature oxidation resistance of T92 steel through preferential oxidation of Al at the surface.

  8. High Temperature Oxidation of Hot-Dip Aluminized T92 Steels

    NASA Astrophysics Data System (ADS)

    Abro, Muhammad Ali; Hahn, Junhee; Lee, Dong Bok

    2018-05-01

    The T92 steel plate was hot-dip aluminized, and oxidized in order to characterize the high-temperature oxidation behavior of hot-dip aluminized T92 steel. The coating consisted of Al-rich topcoat with scattered Al3Fe grains, Al3Fe-rich upper alloy layer with scattered (Al, Al5Fe2, AlFe)-grains, and Al5Fe2-rich lower alloy layer with scattered (Al5Fe2, AlFe)-grains. Oxidation at 800 °C for 20 h formed (α-Al2O3 scale)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer), while oxidation at 900 °C for 20 h formed (α-Al2O3 scale plus some Fe2O3)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer) from the surface. During oxidation, outward migration of all substrate elements, inward diffusion of oxygen, and back and forth diffusion of Al occurred according to concentration gradients. Also, diffusion transformed and broadened AlFe and AlFe3 layers dissolved with some oxygen and substrate alloying elements. Hot-dip aluminizing improved the high-temperature oxidation resistance of T92 steel through preferential oxidation of Al at the surface.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    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,more » 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.« less

  10. Experimental Investigation of Mechanical Properties of Welded Corten Steel A588 Grade Plate Using ER70S - 6 Filler Material for Construction Application

    NASA Astrophysics Data System (ADS)

    Deepak, J. R.; Bupesh Raja, V. K.; Janardhan Guptha, Mittapalli; Durga Prasad, Palaparthi Hari; Sriram, V.

    2017-05-01

    ASTM A588 Grade A steel plate is a high strength, low alloy structural steel with 0.19 % of carbon content. When exposed to the atmosphere, A588 Grade A is suitable for construction in the bare (paint - free) condition. The main problems are lack of fusion, lack of penetration and corrosion on heat affected zone. In this research work Corten ASTM A588 Grade steel of 3mm thickness is electroplated with copper and then both raw and copper electroplated are welded by GMAW welding process with ER70S-6 as a filler material. The welded ASTM A588 is cut according to ASTM size for further testing of mechanical properties. Considering its welding strength after the process of electroplating, this research clearly states the metal can be utilized for better results in any given field. Here both the tensile and hardness are higher in copper electroplated welded when compare to raw welded.

  11. ESF GROUND SUPPORT - MATERIAL DEDICATION ANALYSIS FOR STRUCTURAL STEEL AND ACCESSORIES FROM A COMMERCIAL GRADE SOURCE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    M.D. Stine

    1996-01-23

    The purpose of this analysis is to select the critical characteristics to be verified for steel sets and accessories and the verification methods to be implemented through a material dedication process for the procurement and use of commercial grade structural steel sets and accessories (which have a nuclear safety function) to be used in ground support (with the exception of alcove ground support and alcove opening framing, which are not addressed in this analysis) for the Exploratory Studies Facility (ESF) Topopah Spring (TS) Loop. The ESF TS Loop includes the North Ramp, Main Drift, and South Ramp underground openings.

  12. Effects of Variations in Heat Treatment on the Mechanical Properties and Microstructure of ASTM A710 Grade A Class 3 Steel.

    DTIC Science & Technology

    1983-05-01

    CLASS 3 STEEL - by G. E. Hitcho *L. C. Smith S. Singhal R. J. Fields U.S. Department of Commerce National Bureau of Standards Fracture and Deformation...IN HEAT TREATMENT ON THE Research & Development MECHANICAL PROPERTIES AND MICROSTRUCTURE OF ASTM A710 GRADE A CLASS 3 STEEL 4. PERFORMING ORGM REPORT...NOTES SIS 1IS. KEY MaR05 (C~ueus ee m. .E If .eum Edalr br Slek ami.) Age hardening steel Microstructure Cleavage fracture Precipitate Ductile

  13. Braze alloy process and strength characterization studies for 18 nickel grade 200 maraging steel with application to wind tunnel models

    NASA Technical Reports Server (NTRS)

    Bradshaw, James F.; Sandefur, Paul G., Jr.; Young, Clarence P., Jr.

    1991-01-01

    A comprehensive study of braze alloy selection process and strength characterization with application to wind tunnel models is presented. The applications for this study include the installation of stainless steel pressure tubing in model airfoil sections make of 18 Ni 200 grade maraging steel and the joining of wing structural components by brazing. Acceptable braze alloys for these applications are identified along with process, thermal braze cycle data, and thermal management procedures. Shear specimens are used to evaluate comparative shear strength properties for the various alloys at both room and cryogenic (-300 F) temperatures and include the effects of electroless nickel plating. Nickel plating was found to significantly enhance both the wetability and strength properties for the various braze alloys studied. The data are provided for use in selecting braze alloys for use with 18 Ni grade 200 steel in the design of wind tunnel models to be tested in an ambient or cryogenic environment.

  14. T2* mapping of hip joint cartilage in various histological grades of degeneration.

    PubMed

    Bittersohl, B; Miese, F R; Hosalkar, H S; Herten, M; Antoch, G; Krauspe, R; Zilkens, C

    2012-07-01

    To evaluate T2* values in various histological severities of osteoarthritis (OA). Magnetic resonance imaging (MRI) and T2* mapping including a three-dimensional (3D) double-echo steady-state (DESS) sequence for morphological cartilage assessment and a 3D multiecho data image combination (MEDIC) sequence for T2* mapping were conducted in 21 human femoral head specimens with varying severities of OA. Subsequently, histological assessment was undertaken in all specimens to correlate the observations of T2* mapping with histological analyses. According to the Mankin score, four grades of histological changes were determined: grade 0 (Mankin scores of 0-4), grade I (scores of 5-8), grade II (scores of 9-10), and grade III (scores of 11-14). For reliability assessment, cartilage T2* measurements were repeated after 4 weeks in 10 randomly selected femoral head specimens. T2* values decreased significantly with increasing cartilage degeneration (total P-values <0.001) ranging from 36.3 ± 4.3 ms in grade 0 regions to 22.8 ± 4.3 ms in regions with grade III changes. Pearson correlation analysis proved a fair correlation between T2* values and Mankin score (correlation coefficient = -0.362) that was statistically significant (P-value <0.001). Intra-class correlation (ICC) analysis demonstrated high intra-observer reproducibility for the T2* measurement (ICC: 0.949, P < 0.001). Given the advantages of the T2* mapping technique with no need for contrast medium, high image resolution and ability to perform 3D biochemically sensitive imaging, T2* mapping may be a strong addition to the currently evolving era of cartilage biochemical imaging. Copyright © 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  15. Zr-92(d,p)Zr-93 and Zr-92(d,t)Zr-91

    NASA Technical Reports Server (NTRS)

    Baron, N.; Fink, C. L.; Christensen, P. R.; Nickels, J.; Torsteinsen, T.

    1972-01-01

    The structures of Zr-93 and Zr-91 were studied by the stripping reaction Zr-92(d,p)Zr-93 and the pick-up reaction Zr-92(d,t)Zr-91 using 13 MeV incident deuterons. The reaction product particles were detected by counter telescope. Typical spectra from the reactions were analyzed by a nonlinear least squares peak fitting program which included a background search. Spin and parity assignments to observed excited levels were made by comparing experimental angular distributions with distorted wave Born approximation calculations.

  16. Microstructure evolution of T91 irradiated in the BOR60 fast reactor

    NASA Astrophysics Data System (ADS)

    Jiao, Z.; Taller, S.; Field, K.; Yeli, G.; Moody, M. P.; Was, G. S.

    2018-06-01

    Microstructures of T91 neutron irradiated in the BOR60 reactor at five temperatures between 376 °C and 524 °C to doses between 15.4 and 35.1 dpa were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and atom probe tomography (APT). Type a<100> dislocation loops were observed at 376-415 °C and network dislocations dominated at 460 °C and 524 °C. Cavities appeared in a bimodal distribution with a high density of small bubbles less than 2 nm at irradiation temperatures between 376 °C and 415 °C. Small bubbles were also observed at 460 °C and 524 °C but cavities greater than 2 nm were absent. Enrichment of Cr, Ni, and Si at the grain boundary was observed at all irradiation temperatures. Radiation-induced segregation (RIS) of Cr, Ni and Si appeared to saturate at 17.1 dpa and 376 °C. The temperature dependence of RIS of Cr, Ni and Si at the grain boundary, which showed a peak Cr enrichment temperature of 460 °C and a lower peak Ni and Si enrichment temperature of ∼400 °C, was consistent with observations of RIS of Cr in proton irradiated T91, suggesting that the same RIS mechanism may also apply to BOR60 irradiated T91. G-phase and Cu-rich precipitates were observed at 376-415 °C but were absent at 460 °C and 524 °C. The absence of G-phase at 524 °C could be related to the minimal segregation of Ni and Si in that condition.

  17. Groups graded by root systems and property (T)

    PubMed Central

    Ershov, Mikhail; Jaikin-Zapirain, Andrei; Kassabov, Martin; Zhang, Zezhou

    2014-01-01

    We establish property (T) for a large class of groups graded by root systems, including elementary Chevalley groups and Steinberg groups of rank at least 2 over finitely generated commutative rings with 1. We also construct a group with property (T) which surjects onto all finite simple groups of Lie type and rank at least two. PMID:25425669

  18. 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.

  19. Fabrication of Hadfield-Cored Multi-layer Steel Sheet by Roll-Bonding with 1.8-GPa-Strength-Grade Hot-Press-Forming Steel

    NASA Astrophysics Data System (ADS)

    Chin, Kwang-Geun; Kang, Chung-Yun; Park, Jaeyeong; Lee, Sunghak

    2018-03-01

    An austenitic Hadfield steel was roll-bonded with a 1.8-GPa-strength-grade martensitic hot-press-forming (HPF) steel to fabricate a multi-layer steel (MLS) sheet. Near the Hadfield/HPF interface, the carburized and decarburized layers were formed by the carbon diffusion from the Hadfield (1.2%C) to HPF (0.35%C) layers, and could be regarded as kinds of very thin multi-layers of 35 μm in thickness. The tensile test and fractographic data indicated that the MLS sheet was fractured abruptly within the elastic range by the intergranular fracture occurred in the carburized layer. This was because C was mainly segregated at prior austenite grain boundaries in the carburized layer, which weakened grain boundaries to induce the intergranular fracture. In order to solve the intergranular facture problem, the MLS sheet was tempered at 200 °C. The stress-strain curve of the tempered MLS sheet lay between those of the HPF and Hadfield sheets, and a rule of mixtures was roughly satisfied. Tensile properties of the MLS sheet were dramatically improved after the tempering, and the intergranular fracture was erased completely. In particular, the yield strength up to 1073 MPa along with the high strain hardening and excellent ductility of 32.4% were outstanding because the yield strength over 1 GPa was hardly achieved in conventional austenitic steels.

  20. Fabrication of Hadfield-Cored Multi-layer Steel Sheet by Roll-Bonding with 1.8-GPa-Strength-Grade Hot-Press-Forming Steel

    NASA Astrophysics Data System (ADS)

    Chin, Kwang-Geun; Kang, Chung-Yun; Park, Jaeyeong; Lee, Sunghak

    2018-05-01

    An austenitic Hadfield steel was roll-bonded with a 1.8-GPa-strength-grade martensitic hot-press-forming (HPF) steel to fabricate a multi-layer steel (MLS) sheet. Near the Hadfield/HPF interface, the carburized and decarburized layers were formed by the carbon diffusion from the Hadfield (1.2%C) to HPF (0.35%C) layers, and could be regarded as kinds of very thin multi-layers of 35 μm in thickness. The tensile test and fractographic data indicated that the MLS sheet was fractured abruptly within the elastic range by the intergranular fracture occurred in the carburized layer. This was because C was mainly segregated at prior austenite grain boundaries in the carburized layer, which weakened grain boundaries to induce the intergranular fracture. In order to solve the intergranular facture problem, the MLS sheet was tempered at 200 °C. The stress-strain curve of the tempered MLS sheet lay between those of the HPF and Hadfield sheets, and a rule of mixtures was roughly satisfied. Tensile properties of the MLS sheet were dramatically improved after the tempering, and the intergranular fracture was erased completely. In particular, the yield strength up to 1073 MPa along with the high strain hardening and excellent ductility of 32.4% were outstanding because the yield strength over 1 GPa was hardly achieved in conventional austenitic steels.

  1. Development and Technology of Large Thickness TMCP Steel Plate with 390MPA Grade Used for Engineering Machinery

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoshu; Zhang, Zhijun; Zhang, Peng

    Recently, with the rapid upgrading of the equipment in the steel Corp, the rolling technology of TMCP has been rapidly developed and widely applied. A large amount of steel plate has been produced by using the TMCP technology. The TMCP processes have been used more and more widely and replaced the heat treatment technology of normalizing, quenching and tempering heat process. In this paper, low financial input is considered in steel plate production and the composition of the steel has been designed with low C component, a limited alloy element of the Nb, and certain amounts of Mn element. During the continuous casting process, the size of the continuous casting slab section is 300 mm × 2400 mm. The rolling technology of TMCP is controlled at a lower rolling and red temperature to control the transformation of the microstructure. Four different rolling treatments are chosen to test its effects on the 390MPa grade low carbon steel of bainitic microstructure and properties. This test manages to produce a proper steel plate fulfilling the standard mechanical properties. Specifically, low carbon bainite is observed in the microstructure of the steel plate and the maximum thickness of steel plate under this TMCP technology is up to 80mm. The mechanical property of the steel plate is excellent and the KV2 at -40 °C performs more than 200 J. Moreover, the production costs are greatly reduced when the steel plate is produced by this TMCP technology when replacing the current production process of quenching and tempering. The low cost steel plate could well meet the requirements of producing engineering machinery in the steel market.

  2. Microstructure evolution of T91 irradiated in the BOR60 fast reactor

    DOE PAGES

    Jiao, Z.; Taller, S.; Field, K.; ...

    2018-03-14

    In this paper, microstructures of T91 neutron irradiated in the BOR60 reactor at five temperatures between 376 °C and 524 °C to doses between 15.4 and 35.1 dpa were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and atom probe tomography (APT). Type a<100> dislocation loops were observed at 376–415 °C and network dislocations dominated at 460 °C and 524 °C. Cavities appeared in a bimodal distribution with a high density of small bubbles less than 2 nm at irradiation temperatures between 376 °C and 415 °C. Small bubbles were also observed at 460 °C and 524more » °C but cavities greater than 2 nm were absent. Enrichment of Cr, Ni, and Si at the grain boundary was observed at all irradiation temperatures. Radiation-induced segregation (RIS) of Cr, Ni and Si appeared to saturate at 17.1 dpa and 376 °C. The temperature dependence of RIS of Cr, Ni and Si at the grain boundary, which showed a peak Cr enrichment temperature of 460 °C and a lower peak Ni and Si enrichment temperature of ~400 °C, was consistent with observations of RIS of Cr in proton irradiated T91, suggesting that the same RIS mechanism may also apply to BOR60 irradiated T91. G-phase and Cu-rich precipitates were observed at 376–415 °C but were absent at 460 °C and 524 °C. Finally, the absence of G-phase at 524 °C could be related to the minimal segregation of Ni and Si in that condition.« less

  3. Microstructure evolution of T91 irradiated in the BOR60 fast reactor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jiao, Z.; Taller, S.; Field, K.

    In this paper, microstructures of T91 neutron irradiated in the BOR60 reactor at five temperatures between 376 °C and 524 °C to doses between 15.4 and 35.1 dpa were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and atom probe tomography (APT). Type a<100> dislocation loops were observed at 376–415 °C and network dislocations dominated at 460 °C and 524 °C. Cavities appeared in a bimodal distribution with a high density of small bubbles less than 2 nm at irradiation temperatures between 376 °C and 415 °C. Small bubbles were also observed at 460 °C and 524more » °C but cavities greater than 2 nm were absent. Enrichment of Cr, Ni, and Si at the grain boundary was observed at all irradiation temperatures. Radiation-induced segregation (RIS) of Cr, Ni and Si appeared to saturate at 17.1 dpa and 376 °C. The temperature dependence of RIS of Cr, Ni and Si at the grain boundary, which showed a peak Cr enrichment temperature of 460 °C and a lower peak Ni and Si enrichment temperature of ~400 °C, was consistent with observations of RIS of Cr in proton irradiated T91, suggesting that the same RIS mechanism may also apply to BOR60 irradiated T91. G-phase and Cu-rich precipitates were observed at 376–415 °C but were absent at 460 °C and 524 °C. Finally, the absence of G-phase at 524 °C could be related to the minimal segregation of Ni and Si in that condition.« less

  4. Characterizing T-cell response in low-grade and high-grade vulval intraepithelial neoplasia, study of CD3, CD4 and CD8 expressions.

    PubMed

    Gul, Nahid; Ganesan, Raji; Luesley, David M

    2004-07-01

    The objective of our study was to compare immunocyte infiltrates in vulval epithelium from low-grade and high-grade vulval intraepithelial neoplasia (VIN) lesions to determine if difference in T-cell presence reflected the grade of VIN. Thirty-six vulval specimens were obtained from 24 patients who had previously undergone vulval biopsies for VIN, 14 high-grade diseases (VIN 3 with or without HPV) and 14 low-grade diseases (VIN 1 and VIN 2 with or without HPV). Eight samples of normal vulval tissue were selected from the excision margins of resected vulval biopsies. The lymphocyte surface markers included CD3 (Pan T-cell marker), CD4 (T helper cells), and CD8 (T cytotoxic cells). Each tissue section was visualized under high power magnification and cells were counted in 10 random areas at the dermo-epidermal junction. A significantly higher number of total mean T lymphocytes were detected in VIN specimens compared to normal vulval tissue (P = 0.002). In low-grade VIN, there were significantly more CD8 cells than CD4 when compared to high-grade VIN. This difference in CD4/CD8 ratio was significant (P = 0.001). This study suggests that increased CD8 response in VIN is a feature of low-grade disease and we speculate that this may be a protective mechanism. In high-grade disease, both CD4 cells and CD8 cells are equally present with preservation of normal CD4/CD8 ratio.

  5. Investigation of the plastic fracture of high strength steels

    NASA Technical Reports Server (NTRS)

    Cox, T. B.; Low, J. R., Jr.

    1972-01-01

    An investigation of the plastic fracture process to improve tensile strength in high strength steels is presented. Two generic types of steels are considered: a quenched and tempered grade and a maraging grade, in order to compare two different matrix microstructures. Each type of steel was studied in commercial grade purity and in special melted high purity form, low in residual and impurity elements. The specific alloys dealt with include AISI 4340 and 18 Ni, 200 grade maraging steel, both heat treated to the same yield strength level of approximately 200 ksi.

  6. Corrosion behaviour of stainless steels in flowing LBE at low and high oxygen concentration

    NASA Astrophysics Data System (ADS)

    Aiello, A.; Azzati, M.; Benamati, G.; Gessi, A.; Long, B.; Scaddozzo, G.

    2004-11-01

    The corrosion behaviours of austenitic steel AISI 316L and martensitic steel T91 were investigated in flowing lead-bismuth eutectic (LBE) at 400 °C. The tests were performed in the LECOR and CHEOPE III loops, which stood for the low oxygen concentration and high oxygen concentration in LBE, respectively. The results obtained shows that steels were affected by dissolution at the condition of low oxygen concentration ( C[O 2] = 10 -8-10 -10 wt%) and were oxidized at the condition of high oxygen concentration ( C[O 2] = 10 -5-10 -6 wt%). The oxide layers detected are able to protect the steels from dissolution in LBE. Under the test condition adopted, the austenitic steel behaved more resistant to corrosion induced by LBE than the martensitic steel.

  7. Stress corrosion cracking susceptibility of 18 Ni maraging steel

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Nelson, E. E.

    1974-01-01

    The stress corrosion cracking (SCC) resistance of 18Ni maraging steel (grades 200, 250, 300, and 350) was determined in 3.5 percent salt (NaCl) solution, synthetic sea water, high humidity, and outside MSFC atmosphere. All grades of the maraging steel were found to be susceptible to SCC in varying degrees according to their strengths, with the lowest strength steel (grade 200) being the least susceptible and the highest strength steel (grade 350), the most susceptible to SCC. The SCC resistance of 250 grade maraging steel was also evaluated in salt and salt-chromate solutions using fracture mechanics techniques. The threshold value, K sub SCC, was found to be approximately 44 MN/sq m square root m, (40 ksi square root in.) or 40 percent of the K sub Q value.

  8. Assessment of the influence of surface finishing and weld joints on the corrosion/oxidation behaviour of stainless steels in lead bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Martín-Muñoz, F. J.; Soler-Crespo, L.; Gómez-Briceño, D.

    2011-09-01

    The objective of this paper is to gain some insight into the influence of the surface finishing in the oxidation/corrosion behaviour of 316L and T91 steels in lead bismuth eutectic (LBE). Specimens of both materials with different surface states were prepared (as-received, grinded, grinded and polished, and electrolitically polished) and oxidation tests were carried out at 775 and 825 K from 100 to 2000 h for two different oxygen concentrations and for H 2/H 2O molar ratios of 3 and 0.03. The general conclusion for these tests is that the effect of surface finishing on the corrosion/protection processes is not significant under the tested conditions. In addition the behaviour of weld joints, T91-T91 Tungsten Inert Gas (TIG) and T91-316L have been also studied under similar conditions. The conclusions are that, whereas T91-T91 welded joint shows the same corrosion properties as the parent materials for the conditions tested, AISI 316L-T91 welded joint, present an important dissolution over seam area that it associated to the electrode 309S used for the fabrication process.

  9. Corrosion of stainless steels in lead-bismuth eutectic up to 600 °C

    NASA Astrophysics Data System (ADS)

    Soler, L.; Martín, F. J.; Hernández, F.; Gómez-Briceño, D.

    2004-11-01

    An experimental program has been carried out to understand the differences in the corrosion behaviour between different stainless steels: the austenitic steels 304L and 316L, the martensitic steels F82Hmod, T91 and EM10, and the low alloy steel P22. The influence of oxygen level in Pb-Bi, temperature and exposure time is studied. At 600 °C, the martensitic steels and the P22 steel exhibit thick oxide scales that grow with time, following a linear law for the wet environment and a parabolic law for the dry one. The austenitic stainless steels show a better corrosion behaviour, especially AISI 304L. Under reducing conditions, the steels exhibit dissolution, more severe for the austenitic stainless steels. At 450 °C, all the materials show an acceptable behaviour provided a sufficient oxygen level in the Pb-Bi. At reducing conditions, the martensitic steels and the P22 steel have a good corrosion resistance, while the austenitic steels exhibit already dissolution at the longer exposures.

  10. Phase transformations in steel studied by 3DXRD microscopy

    NASA Astrophysics Data System (ADS)

    Offerman, S. E.; van Dijk, N. H.; Sietsma, J.; Lauridsen, E. M.; Margulies, L.; Grigull, S.; Poulsen, H. F.; van der Zwaag, S.

    2006-05-01

    The ferrite grain nucleation mechanism during the austenite/ferrite phase transformation is studied in situ in the bulk of three different steel grades by three-dimensional X-ray diffraction (3DXRD) microscopy. The main difference between the three steel grades is the carbon concentration. For each steel grade the ferrite fraction, nucleus density and nucleation rate are measured simultaneously during continuous cooling. By comparing the measured nucleation rate to the classical nucleation theory it is concluded that the activation energy for ferrite nucleation is about two orders of magnitude smaller than the current models predict for the three steel grades. During slow cooling the same nucleation behaviour is found for the three steel grades concerning the balance between the energy that is released by the elimination of interfaces and the energy that is required for the formation new interfaces during ferrite nucleation.

  11. Low-grade and high-grade mammary carcinomas in WAP-T transgenic mice are independent entities distinguished by Met expression.

    PubMed

    Otto, Benjamin; Gruner, Katharina; Heinlein, Christina; Wegwitz, Florian; Nollau, Peter; Ylstra, Bauke; Pantel, Klaus; Schumacher, Udo; Baumbusch, Lars O; Martin-Subero, José Ignacio; Siebert, Reiner; Wagener, Christoph; Streichert, Thomas; Deppert, Wolfgang; Tolstonog, Genrich V

    2013-03-15

    Mammary carcinomas developing in SV40 transgenic WAP-T mice arise in two distinct histological phenotypes: as differentiated low-grade and undifferentiated high-grade tumors. We integrated different types of information such as histological grading, analysis of aCGH-based gene copy number and gene expression profiling to provide a comprehensive molecular description of mammary tumors in WAP-T mice. Applying a novel procedure for the correlation of gene copy number with gene expression on a global scale, we observed in tumor samples a global coherence between genotype and transcription. This coherence can be interpreted as a matched transcriptional regulation inherited from the cells of tumor origin and determined by the activity of cancer driver genes. Despite common recurrent genomic aberrations, e.g. gain of chr. 15 in most WAP-T tumors, loss of chr. 19 frequently occurs only in low-grade tumors. These tumors show features of "basal-like" epithelial differentiation, particularly expression of keratin 14. The high-grade tumors are clearly separated from the low-grade tumors by strong expression of the Met gene and by coexpression of epithelial (e.g. keratin 18) and mesenchymal (e.g. vimentin) markers. In high-grade tumors, the expression of the nonmutated Met protein is associated with Met-locus amplification and Met activity. The role of Met as a cancer driver gene is supported by the contribution of active Met signaling to motility and growth of mammary tumor-derived cells. Finally, we discuss the independent origin of low- and high-grade tumors from distinct cells of tumor origin, possibly luminal progenitors, distinguished by Met gene expression and Met signaling. Copyright © 2012 UICC.

  12. Report on Understanding and Predicting Effects of Thermal Aging on Microstructure and Tensile Properties of Grade 91 Steel for Structural Components

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Meimei; Natesan, K.; Chen, Weiying

    This report provides an update on understanding and predicting the effects of long-term thermal aging on microstructure and tensile properties of G91 to corroborate the ASME Code rules in strength reduction due to elevated temperature service. The research is to support the design and long-term operation of G91 structural components in sodium-cooled fast reactors (SFRs). The report is a Level 2 deliverable in FY17 (M2AT-17AN1602017), under the Work Package AT-17AN160201, “SFR Materials Testing” performed by the Argonne National Laboratory (ANL), as part of the Advanced Reactor Technologies Program.

  13. Utility of dysphagia grade in predicting endoscopic ultrasound T-stage of non-metastatic esophageal cancer.

    PubMed

    Fang, T C; Oh, Y S; Szabo, A; Khan, A; Dua, K S

    2016-08-01

    Patients with non-metastatic esophageal cancer routinely undergo endoscopic ultrasound (EUS) for loco-regional staging. Neoadjuvant therapy is recommended for ≥T3 tumors while upfront surgery can be considered for ≤T2 lesions. The aim of this study was to determine if the degree of dysphagia can predict the EUS T-stage of esophageal cancer. One hundred eleven consecutive patients with non-metastatic esophageal cancer were retrospectively reviewed from a database. Prior to EUS, patients' dysphagia grade was recorded. Correlation between dysphagia grade and EUS T-stage, especially in reference to predicting ≥T3 stage, was determined. The correlation of dysphagia grade with EUS T-stage (Kendall's tau coefficient) was 0.49 (P < 0.001) for the lower and 0.59 (P = 0.008) for the middle esophagus. The sensitivity and specificity of dysphagia grade ≥2 (can only swallow semi-solids/liquids) for T3 cancer were 56% (95% confidence interval [CI] 43-67%) and 93% (95% CI 79-98%), respectively. The sensitivity, specificity, and positive predictive value of dysphagia grade ≥3 (can only swallow liquids or total dysphagia) for T3 lesions were 36% (95% CI 25-48%), 100% (95% CI 89-100%), and 100% (95% CI 83-100%), respectively. Overall, there was a significant positive correlation between dysphagia grade and the EUS T-stage of esophageal cancer. All patients with dysphagia grade ≥3 had T3 lesions. This may have clinical implications for patients who can only swallow liquids or have complete dysphagia by allowing for prompt initiation of neoadjuvant therapy, especially in countries/centers where EUS service is difficult to access in a timely manner or not available. © 2015 International Society for Diseases of the Esophagus.

  14. Microstructural Evolution of Thor™ 115 Creep-Strength Enhanced Ferritic Steel

    NASA Astrophysics Data System (ADS)

    Ortolani, Matteo; D'Incau, Mirco; Ciancio, Regina; Scardi, Paolo

    2017-12-01

    A new ferritic steel branded as Thor™ 115 has been developed to enhance high-temperature resistance. The steel design combines an improved oxidation resistance with long-term microstructural stability. The new alloy, cast to different product forms such as plates and tubes, was extensively tested to assess the high-temperature time-dependent mechanical behavior (creep). The main strengthening mechanism is precipitation hardening by finely dispersed carbide and nitride phases. Information on the evolution of secondary phases and time-temperature-precipitation behavior of the alloy, essential to ensure long-term property stability, was obtained by scanning transmission electron microscopy with energy dispersive spectroscopy, and by X-ray Powder Diffraction on specimens aged up to 50,000 hours. A thermodynamic modeling supports presentation and evaluation of the experimental results. The evolution of precipitates in the new alloy confirms the retention of the strengthening by secondary phases, even after long-term exposure at high temperature. The deleterious conversion of nitrides into Z phase is shown to be in line with, or even slower than that of the comparable ASME grade 91 steel.

  15. Steel Industry Analysis Brief

    EIA Publications

    2009-01-01

    The steel industry is critical to the U.S. economy. Steel is the material of choice for many elements of construction, transportation, manufacturing, and a variety of consumer products. It is the backbone of bridges, skyscrapers, railroads, automobiles, and appliances. Most grades of steel used today - particularly high-strength steels that are lighter and more versatile - were not available a decade ago.

  16. Calculation of {alpha}/{gamma} equilibria in SA508 grade 3 steels for intercritical heat treatment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, B.J.; Kim, H.D.; Hong, J.H.

    1998-05-01

    An attempt has been made to suggest an optimum temperature for intercritical heat treatment of an SA508 grade 3 steel for nuclear pressure vessels, based on thermodynamic calculation of the {alpha}/{gamma} phase equilibria. A thermodynamic database constructed for the Fe-Mn-Ni-Mo-Cr-Si-V-Al-C-N ten-component system and an empirical criterion that the amount of reformed austenite should be around 40 pct were used for thermodynamic calculation and derivation of the optimum heat-treatment temperature, respectively. The calculated optimum temperature, 720 C, was in good agreement with an experimentally determined temperature of 725 C obtained through an independent experimental investigation of the same steel. The agreementmore » between the calculated and measured fraction of reformed austenite during the intercritical heat treatment was also confirmed. Based on the agreement between calculation and experiment, it could be concluded that thermodynamic calculations can be successfully applied to the materials and/or process design as an additive tool to the already established technology, and that the currently constructed thermodynamic database for steel systems shows an accuracy that makes such applications possible.« less

  17. Experimental investigation and optimization of welding process parameters for various steel grades using NN tool and Taguchi method

    NASA Astrophysics Data System (ADS)

    Soni, Sourabh Kumar; Thomas, Benedict

    2018-04-01

    The term "weldability" has been used to describe a wide variety of characteristics when a material is subjected to welding. In our analysis we perform experimental investigation to estimate the tensile strength of welded joint strength and then optimization of welding process parameters by using taguchi method and Artificial Neural Network (ANN) tool in MINITAB and MATLAB software respectively. The study reveals the influence on weldability of steel by varying composition of steel by mechanical characterization. At first we prepare the samples of different grades of steel (EN8, EN 19, EN 24). The samples were welded together by metal inert gas welding process and then tensile testing on Universal testing machine (UTM) was conducted for the same to evaluate the tensile strength of the welded steel specimens. Further comparative study was performed to find the effects of welding parameter on quality of weld strength by employing Taguchi method and Neural Network tool. Finally we concluded that taguchi method and Neural Network Tool is much efficient technique for optimization.

  18. Examining the microtexture evolution in a hole-edge punched into 780 MPa grade hot-rolled steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shin, J.H.; Kim, M.S.

    The deformation behavior in the hole-edge of 780 MPa grade hot-rolled steel during the punching process was investigated via microstructure characterization and computational simulation. Microstructure characterization was conducted to observe the edges of punched holes through the thickness direction, and electron back-scattered diffraction (EBSD) was used to analyze the heterogeneity of the deformation. Finite element analysis (FEA) that could account for a ductile fracture criterion was conducted to simulate the deformation and fracture behaviors of 780 MPa grade hot-rolled steel during the punching process. Calculation of rotation rate fields at the edges of the punched holes during the punching processmore » revealed that metastable orientations in Euler space were confined to specific orientation groups. Rotation-rate fields effectively explained the stability of the initial texture components in the hole-edge region during the punching process. A visco-plastic self-consistent (VPSC) polycrystal model was used to calculate the microtexture evolution in the hole-edge region during the punching process. FEA revealed that the heterogeneous effective strain was closely related to the heterogeneity of the Kernel average misorientation (KAM) distribution in the hole-edge region. A simulation of the deformation microtexture evolution in the hole-edge region using a VPSC model was in good agreement with the experimental results. - Highlights: •We analyzed the microstructure in a hole-edge punched in HR 780HB steel. •Rotation rate fields revealed the stability of the initial texture components. •Heterogeneous effective stain was closely related to the KAM distribution. •VPSC model successfully simulated the deformation microtexture evolution.« less

  19. Investigation of Hot Deformation Behavior of Duplex Stainless Steel Grade 2507

    NASA Astrophysics Data System (ADS)

    Kingklang, Saranya; Uthaisangsuk, Vitoon

    2017-01-01

    Recently, duplex stainless steels (DSSs) are being increasingly employed in chemical, petro-chemical, nuclear, and energy industries due to the excellent combination of high strength and corrosion resistance. Better understanding of deformation behavior and microstructure evolution of the material under hot working process is significant for achieving desired mechanical properties. In this work, plastic flow curves and microstructure development of the DSS grade 2507 were investigated. Cylindrical specimens were subjected to hot compression tests for different elevated temperatures and strain rates by a deformation dilatometer. It was found that stress-strain responses of the examined steel strongly depended on the forming rate and temperature. The flow stresses increased with higher strain rates and lower temperatures. Subsequently, predictions of the obtained stress-strain curves were done according to the Zener-Hollomon equation. Determination of material parameters for the constitutive model was presented. It was shown that the calculated flow curves agreed well with the experimental results. Additionally, metallographic examinations of hot compressed samples were performed by optical microscope using color tint etching. Area based phase fractions of the existing phases were determined for each forming condition. Hardness of the specimens was measured and discussed with the resulted microstructures. The proposed flow stress model can be used to design and optimize manufacturing process at elevated temperatures for the DSS.

  20. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Steel Minimum service temperature, °F. A-333, 9 percent Ni, grade 8 −320 A-334, 9 percent Ni, grade 8 −320 A-353, 9 percent Ni, double normalized and tempered −320 A-522, 9 percent Ni, NNT, Q and T, forging −320 A-553, 9 percent Ni, quenched and tempered −320 (b) The materials permitted under paragraph...

  1. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Steel Minimum service temperature, °F. A-333, 9 percent Ni, grade 8 −320 A-334, 9 percent Ni, grade 8 −320 A-353, 9 percent Ni, double normalized and tempered −320 A-522, 9 percent Ni, NNT, Q and T, forging −320 A-553, 9 percent Ni, quenched and tempered −320 (b) The materials permitted under paragraph...

  2. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., and service pressure. A DOT 3T cylinder is a seamless steel cylinder with a minimum water capacity of...) Wall thickness. The minimum wall thickness must be such that the wall stress at the minimum specified... the physical tests required in paragraphs (j) and (k) of this section. A wall stress of more than 90...

  3. Effects of DC bias on magnetic performance of high grades grain-oriented silicon steels

    NASA Astrophysics Data System (ADS)

    Ma, Guang; Cheng, Ling; Lu, Licheng; Yang, Fuyao; Chen, Xin; Zhu, Chengzhi

    2017-03-01

    When high voltage direct current (HVDC) transmission adopting mono-polar ground return operation mode or unbalanced bipolar operation mode, the invasion of DC current into neutral point of alternating current (AC) transformer will cause core saturation, temperature increasing, and vibration acceleration. Based on the MPG-200D soft magnetic measurement system, the influence of DC bias on magnetic performance of 0.23 mm and 0.27 mm series (P1.7=0.70-1.05 W/kg, B8>1.89 T) grain-oriented (GO) silicon steels under condition of AC / DC hybrid excitation were systematically realized in this paper. For the high magnetic induction GO steels (core losses are the same), greater thickness can lead to stronger ability of resisting DC bias, and the reasons for it were analyzed. Finally, the magnetostriction and A-weighted magnetostriction velocity level of GO steel under DC biased magnetization were researched.

  4. Mechanical Characteristics of Submerged Arc Weldment in API Gas Pipeline Steel of Grade X65

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hashemi, S. H.; Mohammadyani, D.

    The mechanical properties of submerged arc weldment (SAW) in gas transportation pipeline steel of grade API X65 (65 ksi yield strength) were investigated. This steel is produced by thermo mechanical control rolled (TMC), and is largely used in Iran gas piping systems and networks. The results from laboratory study on three different regions; i.e. base metal (BM), fusion zone (FZ) and heat affected zone (HAZ) were used to compare weldment mechanical characteristics with those specified by API 5L (revision 2004) standard code. Different laboratory experiments were conducted on test specimens taken from 48 inch outside diameter and 14.3 mm wallmore » thickness gas pipeline. The test results showed a gradient of microstructure and Vickers hardness data from the centerline of FZ towards the unaffected MB. Similarly, lower Charpy absorbed energy (compared to BM) was observed in the FZ impact specimens. Despite this, the API specifications were fulfilled in three tested zones, ensuring pipeline structural integrity under working conditions.« less

  5. Effect of W and N on mechanical properties of reduced activation ferritic/martensitic EUROFER-based steel grades

    NASA Astrophysics Data System (ADS)

    Puype, A.; Malerba, L.; De Wispelaere, N.; Petrov, R.; Sietsma, J.

    2018-04-01

    The C, N, and W content in EUROFER97, a 9CrWVTa reduced-activation ferritic/martensitic (RAFM) steel, was varied to obtain an experimental assessment of the main effects of the compositional variation on the mechanical properties and microstructural characteristics of six different experimental grades. Light optical microscopy (LOM) and electron back-scattered diffraction (EBSD) revealed in almost all cases a fine tempered lath martensite structure. Analyses of transmission electron micrographs, together with inductively coupled plasma mass spectrometry (ICPMS) and energy-dispersive x-ray spectroscopy (EDS) data, shows the precipitation state and spatial distribution of MxCy (M = Cr, W and Fe) and MX (M = V and/or Ta, X = C or N) carbonitrides within the matrix. The mechanical characterization of the six different steel grades was carried out by means of A50 tensile testing and Charpy tests on standard specimens (55 × 10 × 10 mm3). Lowering the carbon content and keeping the nitrogen content higher than 0.02 wt%, leads to a reduction of the ductile-to-brittle-transition-temperature (DBTT) in comparison with EUROFER97-2. The addition of tungsten further reduces the DBTT to - 94 °C, while maintaining good tensile strength and elongation.

  6. 7 CFR 91.2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Definitions. 91.2 Section 91.2 Agriculture Regulations... AND GENERAL INFORMATION Administration § 91.2 Definitions. Words used in the regulations in this part... person or organization requesting services provided by the Science and Technology (S&T) programs. Legal...

  7. Change of nonlinear acoustics in ASME grade 122 steel welded joint during creep

    NASA Astrophysics Data System (ADS)

    Ohtani, Toshihiro; Honma, Takumi; Ishii, Yutaka; Tabuchi, Masaaki; Hongo, Hiromichi; Hirao, Masahiko

    2016-02-01

    In this paper, we described the changes of two nonlinear acoustic characterizations; resonant frequency shift and three-wave interaction, with electromagnetic acoustic resonance (EMAR) throughout the creep life in the welded joints of ASME Grade 122, one of high Cr ferritic heat resisting steels. EMAR was a combination of the resonant acoustic technique with a non-contact electromagnetic acoustic transducer (EMAT). These nonlinear acoustic parameters decreased from the start to 50% of creep life. After slightly increased, they rapidly increased from 80% of creep life to rupture. We interpreted these phenomena in terms of dislocation recovery, recrystallization, and restructuring related to the initiation and growth of creep void, with support from the SEM and TEM observation.

  8. Castings, Steel, Homogenization of Steel Castings

    DTIC Science & Technology

    1942-12-05

    concerninr.. the ef- fe~ct of homogenizing herat-- treAment u-non the ballistic prop- erties -%f cLast steel armo--iercinr nrro jectilt:s. .arden.YD- 1 t...of hLmogenizing- treAments upon the3 corrosi;.A -.f quenched- Lr(- t c,-.rnered. c-.st steel. Harich, Riffin, -ri Bolotsk-2 .. ade two-bec-d weldahtil

  9. Effect of Multiple Local Repairs on Microstructure and Mechanical Properties of T24 Steel Welded Joint

    NASA Astrophysics Data System (ADS)

    Chaus, Alexander S.; Kuhajdová, Andrea; Marônek, Milan; Dománková, Mária

    2018-05-01

    The effect of multiple local repairs on the microstructure and mechanical properties of the T24 steel welded joints was studied. T24 steel tubes were butt-welded by the GTAW method. Peripheral welded joints were made in four locations of the tube. In order to simulate the repair procedure, the welds were cut off from the root and the first local repair was performed. Other two local repairs were carried out in the same way. After each local repair, the microstructure and mechanical properties of the joints were evaluated. The results of the mechanical tests demonstrate that only two local repairs can be performed on the T24 steel peripheral welded joint. After the third local repair, impact energy of the welded joint was lower than required value, which is attributed to the coarser martensite and the coarser carbide precipitates formed in the heat-affected zone, compared with the weld metal.

  10. Characterization of carbon ion implantation induced graded microstructure and phase transformation in stainless steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Kai; Wang, Yibo; Li, Zhuguo, E-mail: lizg@sjtu.edu.cn

    Austenitic stainless steel 316L is ion implanted by carbon with implantation fluences of 1.2 × 10{sup 17} ions-cm{sup −} {sup 2}, 2.4 × 10{sup 17} ions-cm{sup −} {sup 2}, and 4.8 × 10{sup 17} ions-cm{sup −} {sup 2}. The ion implantation induced graded microstructure and phase transformation in stainless steel is investigated by X-ray diffraction, X-ray photoelectron spectroscopy and high resolution transmission electron microscopy. The corrosion resistance is evaluated by potentiodynamic test. It is found that the initial phase is austenite with a small amount of ferrite. After low fluence carbon ion implantation, an amorphous layer and ferrite phase enrichedmore » region underneath are formed. Nanophase particles precipitate from the amorphous layer due to energy minimization and irradiation at larger ion implantation fluence. The morphology of the precipitated nanophase particles changes from circular to dumbbell-like with increasing implantation fluence. The corrosion resistance of stainless steel is enhanced by the formation of amorphous layer and graphitic solid state carbon after carbon ion implantation. - Highlights: • Carbon implantation leads to phase transformation from austenite to ferrite. • The passive film on SS316L becomes thinner after carbon ion implantation. • An amorphous layer is formed by carbon ion implantation. • Nanophase precipitate from amorphous layer at higher ion implantation fluence. • Corrosion resistance of SS316L is improved by carbon implantation.« less

  11. Mechanical characteristics of welded joints between different stainless steels grades

    NASA Astrophysics Data System (ADS)

    Topolska, S.; Łabanowski, J.

    2017-08-01

    Investigation of mechanical characteristics of welded joints is one of the most important tasks that allow determining their functional properties. Due to the very high, still rising, cost of some stainless steels it is justified, on economic grounds, welding austenitic stainless steel with steels that are corrosion-resistant like duplex ones. According to forecasts the price of corrosion resistant steels stil can increase by 26 ÷ 30%. For technical reasons welded joints require appropriate mechanical properties such as: tensile strength, bending, ductility, toughness, and resistance to aggressive media. Such joints are applied in the construction of chemical tankers, apparatus and chemical plants and power steam stations. Using the proper binder makes possible the welds directly between the elements of austenitic stainless steels and duplex ones. It causes that such joits behave satisfactorily in service in such areas like maritime constructions and steam and chemical plants. These steels have high mechanical properties such as: the yield strength, the tensile strength and the ductility as well as the resistance to general corrosion media. They are resistant to both pitting and stress corrosions. The relatively low cost of production of duplex steels, in comparison with standard austenitic steels, is inter alia, the result of a reduced amount of scarce and expensive Nickel, which is seen as a further advantage of these steels.

  12. Stress-strain relationship of high-strength steel (HSS) reinforcing bars

    NASA Astrophysics Data System (ADS)

    Anggraini, Retno; Tavio, Raka, I. Gede Putu; Agustiar

    2018-05-01

    The introduction of High-Strength Steel (HSS) reinforcing bars in reinforced concrete members has gained much attention in recent years and led to many advantages such as construction timesaving. It is also more economical since it can reduce the amount of reinforcing steel bars used in concrete members which in turn alleviates the congestion of reinforcement. Up to present, the building codes, e.g. American Concrete Institute (ACI) 318M-14 and Standard National Indonesia (SNI) 2847:2013, still restrict the use of higher-strength steel reinforcing bars for concrete design up to Grade 420 MPa due to the possible suspected brittle behavior of concrete members. This paper evaluates the characteristics of stress-strain relationships of HSS bars if they are comparable to the characteristics of those of Grade 420 MPa. To achieve the objective of the study, a series of steel bars from various grades (420, 550, 650, and 700 MPa) was selected. Tensile tests of these steel samples were conducted under displacement-controlled mode to capture the complete stress-strain curves and particularly the post-yield response of the steel bars. The results indicate that all the steel bars tested had the actual yield strengths greater than the corresponding specified values. The stress-strain curves of HSS reinforcing bars (Grade 550, 650, and 700 MPa) performed slightly different characteristics with those of Grade 420 MPa.

  13. 46 CFR 154.170 - Outer hull steel plating.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... strake must be at least Grade E steel or a grade of steel that has equivalent chemical properties, mechanical properties, and heat treatment, and that is specially approved by the Commandant (CG-522). (2) The... chemical properties, mechanical properties, and heat treatment, and that is specially approved by the...

  14. Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy

    PubMed Central

    Brooks, Emily K.; Tobias, Menachem E.; Yang, Shuying; Bone, Lawrence B.; Ehrensberger, Mark T.

    2015-01-01

    This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin) and outer layer resistance (Rout) were lower for samples without cells cultured on the surface at 3 days (Rin = 2.64 e4 Ω/cm2, Rout = 140 Ω/cm2) compared to 21 days (Rin = 3.60 e4 Ω/cm2, Rout = 287 Ω/cm2) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin = 1.88 e5 Ω/cm2, Rout = 1060 Ω/cm2) which was observed to increase over time (21 day, Rin = 2.99 e4 Ω/cm2, Rout = 287 Ω/cm2). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91. PMID:25715925

  15. Characteristics of Ni-Cr-Fe laser clad layers on EA4T steel

    NASA Astrophysics Data System (ADS)

    Chen, Wenjing; Chen, Hui; Wang, Yongjing; Li, Congchen; Wang, Xiaoli

    2017-07-01

    The Ni-Cr-Fe metal powder was deposited on EA4T steel by laser cladding technology. The microstructure and chemical composition of the cladding layer were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bonding ability between the cladding layer and the matrix was measured. The results showed that the bonding between the cladding layer and the EA4T steel was metallurgical bonding. The microstructure of cladding layer was composed of planar crystals, columnar crystals and dendrite, which consisted of Cr2Ni3, γ phase, M23C6 and Ni3B phases. When the powder feeding speed reached 4 g/min, the upper bainite occurred in the heat affected zone (HAZ). Moreover, the tensile strength of the joint increased, while the yield strength and the ductility decreased.

  16. Corrosion resistance of BIS 2062-grade steel coated with nano-metal-oxide mixtures of iron, cerium, and titanium in the marine environment

    NASA Astrophysics Data System (ADS)

    Ashraf, P. Muhamed; Anuradha, R.

    2018-02-01

    BIS 2062-grade carbon steel is extensively used for fishing boat construction. The steel is highly susceptible to corrosion on the hull and welding joints under marine environment. Here, we demonstrate the application of a novel multifunctional nano-metal-oxide mixture comprised of iron, titanium, and cerium as a marine coating to prevent corrosion. The electrochemical performance of nano-metal-oxide mixture coatings, applied over boat-building steel, was evaluated at 3.5% NaCl medium. The nano-mixture surface coatings showed an efficient corrosion resistance with increased polarization resistance of 6043 Ω cm2 and low corrosion current density of 3.53 × 10-6 A cm-2. The electrochemical impedance spectral data exhibited improvement in the polarization resistance of outermost surface and internal layers. The coating responded faster recovery to normal state when subjected to an induced stress over the coating. The nano-material in the coating behaves as a semiconductor; this enhanced electronic activity over the surface of the steel.

  17. Strengthening and Toughening of a Heavy Plate Steel for Shipbuilding with Yield Strength of Approximately 690 MPa

    NASA Astrophysics Data System (ADS)

    Liu, Dongsheng; Cheng, Binggui; Chen, Yuanyuan

    2013-01-01

    HSLA-100 steel with high content of alloying elements (nominally in wt pct, 3.5 Ni, 1.6 Cu, and 0.6Mo) is now used to produce heavy plates for constructing a hull and drilling platform. We proposed here a substantially leaner steel composition (containing 1.7 Ni, 1.1 Cu, and 0.5Mo) to produce a heavy plate to 80 mm thickness with mechanical properties comparable with those of the HSLA-100 grade. A continuous cooling transformation (CCT) diagram of the steel was constructed. Key parameters of thermal treatment and revealing mechanisms of strengthening and toughening were derived based on industrial production trials. The microstructures of the 80-mm-thick plate were lath-like bainite (LB) at near surface of the quarter thickness ( t/4), and granular bainite (GB)+LB at center thickness ( t/2) after solutionizing and water quenching (Q). The effect of tempering (T) on the microstructures and properties of the plate was investigated. Excellent combination of room temperature strength and low-temperature Charpy V-notch (CVN) toughness approximately equivalent to that of the HSLA 100 grade (YS > 690 MPa, CVN energy >100 J even at 193 K [-80 °C]) was achieved in the plate treated by the QT process with tempering temperature of 898 K (625 °C). The combination of strength and toughness at t/4 is superior to that at t/2 of the plate under both as-quenched and QT conditions. This result is attributed to that the fraction of high-angle grain boundaries (HAGBs) at t/4 is higher than that at t/2.

  18. Construction of continuous cooling transformation (CCT) diagram using Gleeble for coarse grained heat affected zone of SA106 grade B steel

    NASA Astrophysics Data System (ADS)

    Vimalan, G.; Muthupandi, V.; Ravichandran, G.

    2018-05-01

    A continuous cooling transformation diagram is constructed for simulated coarse grain heat affected zone (CGHAZ) of SA106 grade B carbon steel. Samples are heated to a peak temperature of 1200°C in the Gleeble thermo mechanical simulator and then cooled at different cooling rates varying from 0.1°C/s to 100°C/s. Microstructure of the specimens simulated at different cooling rates were characterised by optical microscopy and hardness was assessed by Vicker's hardness test and micro-hardness test. Transformation temperatures and the corresponding phase fields were identified from dilatometric curves and the same could be confirmed by correlating with the microstructures at room temperature. These data were used to construct the CCT diagram. Phase fields were found to have ferrite, pearlite, bainite and martensite or their combinations. With the help of this CCT diagram it is possible to predict the microstructure and hardness of coarse grain HAZ experiencing different cooling rates. The constructed CCT diagram becomes an important tool in evaluating the weldability of SA106 grade B carbon steel.

  19. Embrittlement in CN3MN Grade Superaustenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Başkan, Mertcan; Chumbley, Scott L.; Kalay, Yunus Eren

    2014-05-01

    Superaustenitic stainless steels (SSS) are widely used in extreme environments such as off-shore oil wells, chemical and food processing equipment, and seawater systems due to their excellent corrosion resistance and superior toughness. The design of the corresponding heat treatment process is crucial to create better mechanical properties. In this respect, the short-term annealing behavior of CN3MN grade SSS was investigated by a combined study of Charpy impact tests, hardness measurements, scanning and transmission electron microscopy. Specimens were heat treated at 1200 K (927 °C) for up to 16 minutes annealing time and their impact strengths and hardnesses were tested. The impact toughness was found to decrease to less than the half of the initial values while hardness stayed the same. Detailed fracture surface analyses revealed a ductile to brittle failure transition for relatively short annealing times. Brittle fracture occurred in both intergranular and transgranular modes. SEM and TEM indicated precipitation of nano-sized intermetallics, accounting for the intergranular embrittlement, along the grain boundaries with respect to annealing time. The transgranular fracture originated from linear defects seen to exist within the grains. Close observation of such defects revealed stacking-fault type imperfections, which lead to step-like cracking observed in microlength scales.

  20. Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy.

    PubMed

    Brooks, Emily K; Tobias, Menachem E; Yang, Shuying; Bone, Lawrence B; Ehrensberger, Mark T

    2016-02-01

    This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin ) and outer layer resistance (Rout ) were lower for samples without cells cultured on the surface at 3 days (Rin  = 2.64 e4 Ω/cm(2) , Rout  = 140 Ω/cm(2) ) compared to 21 days (Rin  = 3.60 e4 Ω/cm(2) , Rout  = 287 Ω/cm(2) ) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin  = 1.88 e5 Ω/cm(2) , Rout  = 1060 Ω/cm(2) ) which was observed to increase over time (21 day, Rin  = 2.99 e4 Ω/cm(2) , Rout  = 287 Ω/cm(2) ). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91. © 2015 Wiley Periodicals, Inc.

  1. Johnson-Cook Strength Model for Automotive Steels

    NASA Astrophysics Data System (ADS)

    Vedantam, K.

    2005-07-01

    Over the last few years most automotive companies are engaged in performing simulations of the capability of individual components or entire structure of a motor vehicle to adequately sustain the shock (impacts) and to protect the occupants from injuries during crashes. These simulations require constitutive material models (e.g., Johnson-Cook) of the sheet steel and other components based on the compression/tension data obtained in a series of tests performed at quasi-static (˜1/s) to high strain rates (˜2000/s). One such study is undertaken by the recently formed IISI (International Iron and Steel Institute) in organizing the round robin tests to compare the tensile data generated at our Laboratory at strain rates of ˜1/s, ˜300/s, ˜800/s, and ˜2000/s on two grades of automotive steel (Mild steel and Dual Phase-DP 590) using split Hopkinson bar with those generated at high strain rate testing facilities in Germany and Japan. Our tension data on mild steel (flow stress ˜ 500 MPa) suggest a relatively small strain rate sensitivity of the material. The second steel grade (DP-590) tested exhibits significant strain rate sensitivity in that the flow stress increases from about 700 MPa (at ˜1/s) to 900 MPa (at ˜2000/s). J-C strength model constants (A, B, n, and C) for the two steel grades will be presented.

  2. Corrosion-free precast prestressed concrete piles made with stainless steel reinforcement : construction, test and evaluation.

    DOT National Transportation Integrated Search

    2015-03-01

    The use of duplex high-strength stainless steel (HSSS) grade 2205 prestressing strand and : austenitic stainless steel (SS) grade 304 spiral wire reinforcement is proposed as a replacement of : conventional prestressing steel, in order to provide a 1...

  3. 46 CFR 154.172 - Contiguous steel hull structure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Contiguous steel hull structure. 154.172 Section 154.172... Structure § 154.172 Contiguous steel hull structure. (a) Except as allowed in paragraphs (b) and (c) of this... construction of the contiguous steel hull structure must meet the thickness and steel grade in Table 1 for the...

  4. 46 CFR 154.172 - Contiguous steel hull structure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Contiguous steel hull structure. 154.172 Section 154.172... Structure § 154.172 Contiguous steel hull structure. (a) Except as allowed in paragraphs (b) and (c) of this... construction of the contiguous steel hull structure must meet the thickness and steel grade in Table 1 for the...

  5. 46 CFR 154.172 - Contiguous steel hull structure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Contiguous steel hull structure. 154.172 Section 154.172... Structure § 154.172 Contiguous steel hull structure. (a) Except as allowed in paragraphs (b) and (c) of this... construction of the contiguous steel hull structure must meet the thickness and steel grade in Table 1 for the...

  6. 46 CFR 154.172 - Contiguous steel hull structure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Contiguous steel hull structure. 154.172 Section 154.172... Structure § 154.172 Contiguous steel hull structure. (a) Except as allowed in paragraphs (b) and (c) of this... construction of the contiguous steel hull structure must meet the thickness and steel grade in Table 1 for the...

  7. Release of nickel and chromium in common foods during cooking in 18/10 (grade 316) stainless steel pots.

    PubMed

    Guarneri, Fabrizio; Costa, Chiara; Cannavò, Serafinella P; Catania, Stefania; Bua, Giuseppe D; Fenga, Concettina; Dugo, Giacomo

    2017-01-01

    Literature data on the release of nickel and chromium from stainless steel cookware during food preparation are contrasting, have often been obtained with uncommon foods and/or procedures, and are thus not widely applicable. To assess the release of nickel and chromium from 18/10 (grade 316) stainless steel pots in cooking conditions that are common in an urban lifestyle. Tomato sauce and lemon marmalade were cooked for 1 h, alone or with added EDTA, in used or unused stainless steel pots from different manufacturers. Additionally, aqueous solutions at pH 2.3, 7.7 and 9 were boiled for 1 h in the same pots. Metal release was assessed with inductively coupled plasma mass spectrometry. The release of nickel and chromium increased with cooking/boiling time, was higher with unused pots, at low pH or with EDTA, and was sometimes remarkably different between manufacturers. In all experiments, the amounts released were below known allergy-triggering thresholds. Under common conditions, the use of 18/10 stainless steel pots is considered to be safe for the majority of nickel-allergic and/or chromium-allergic subjects. However, the total amount of nickel contained in foods and released from pots may exceed the individual threshold for triggering allergy, potentially causing problems for highly sensitive patients, or, conversely, contribute to induction of immunotolerance by oral low-dose exposure. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. An Approach to Maximize Weld Penetration During TIG Welding of P91 Steel Plates by Utilizing Image Processing and Taguchi Orthogonal Array

    NASA Astrophysics Data System (ADS)

    Singh, Akhilesh Kumar; Debnath, Tapas; Dey, Vidyut; Rai, Ram Naresh

    2017-10-01

    P-91 is modified 9Cr-1Mo steel. Fabricated structures and components of P-91 has a lot of application in power and chemical industry owing to its excellent properties like high temperature stress corrosion resistance, less susceptibility to thermal fatigue at high operating temperatures. The weld quality and surface finish of fabricated structure of P91 is very good when welded by Tungsten Inert Gas welding (TIG). However, the process has its limitation regarding weld penetration. The success of a welding process lies in fabricating with such a combination of parameters that gives maximum weld penetration and minimum weld width. To carry out an investigation on the effect of the autogenous TIG welding parameters on weld penetration and weld width, bead-on-plate welds were carried on P91 plates of thickness 6 mm in accordance to a Taguchi L9 design. Welding current, welding speed and gas flow rate were the three control variables in the investigation. After autogenous (TIG) welding, the dimension of the weld width, weld penetration and weld area were successfully measured by an image analysis technique developed for the study. The maximum error for the measured dimensions of the weld width, penetration and area with the developed image analysis technique was only 2 % compared to the measurements of Leica-Q-Win-V3 software installed in optical microscope. The measurements with the developed software, unlike the measurements under a microscope, required least human intervention. An Analysis of Variance (ANOVA) confirms the significance of the selected parameters. Thereafter, Taguchi's method was successfully used to trade-off between maximum penetration and minimum weld width while keeping the weld area at a minimum.

  9. Design of Reforma 509 with High Strength Steel

    NASA Astrophysics Data System (ADS)

    Smith, Stuart; Whitby, William; Easton, Marc

    Reforma 509 is a high-rise building located in the heart of the Central Business District of Mexico City. The building is comprised of office, hotel, residential and parking and forms part of a cluster of tall buildings in the area. If completed today, Reforma 509 would be the tallest building in Mexico, at 238m. All of the building's gravity and lateral (wind and seismic) loads are carried by an architecturally expressed perimeter frame that is formed from highly efficient Steel Reinforced Concrete (SRC) columns coupled together by steel tube perimeter bracing. This paper investigates the implications of substituting a grade 50 (fy=345 MPa) carbon steel with a higher strength micro-alloyed grade 70 (fy=480 MPa) steel in the design of Reforma 509.

  10. High temperature oxidation in boiler environment of chromized steel

    NASA Astrophysics Data System (ADS)

    Alia, F. F.; Kurniawan, T.; Asmara, Y. P.; Ani, M. H. B.; Nandiyanto, A. B. D.

    2017-10-01

    The demand for increasing efficiency has led to the development and construction of higher operating temperature power plant. This condition may lead to more severe thickness losses in boiler tubes due to excessive corrosion process. Hence, the research to improve the corrosion resistance of the current operated material is needed so that it can be applied for higher temperature application. In this research, the effect of chromizing process on the oxidation behaviour of T91 steel was investigated under steam condition. In order to deposit chromium, mixture of chromium (Cr) powder as master alloy, halide salt (NH4Cl) powder as activator and alumina (Al2O3) powder as inert filler were inserted into alumina retort together with the steel sample and heated inside furnace at 1050°C for ten hours under argon gas environment. Furthermore, for the oxidation process, steels were exposed at 700°C at different oxidation time (6h-24h) under steam condition. From FESEM/EDX analysis, it was found that oxidation rate of pack cemented steel was lower than the un-packed steel. These results show that Cr from chromizing process was able to become reservoir for the formation of Cr2O3 in high temperature steam oxidation, and its existence can be used for a longer oxidation time.

  11. Nonalcoholic Fatty Liver Disease: Diagnostic and Fat-Grading Accuracy of Low-Flip-Angle Multiecho Gradient-Recalled-Echo MR Imaging at 1.5 T

    PubMed Central

    Yokoo, Takeshi; Bydder, Mark; Hamilton, Gavin; Middleton, Michael S.; Gamst, Anthony C.; Wolfson, Tanya; Hassanein, Tarek; Patton, Heather M.; Lavine, Joel E.; Schwimmer, Jeffrey B.; Sirlin, Claude B.

    2009-01-01

    Purpose: To assess the accuracy of four fat quantification methods at low-flip-angle multiecho gradient-recalled-echo (GRE) magnetic resonance (MR) imaging in nonalcoholic fatty liver disease (NAFLD) by using MR spectroscopy as the reference standard. Materials and Methods: In this institutional review board–approved, HIPAA-compliant prospective study, 110 subjects (29 with biopsy-confirmed NAFLD, 50 overweight and at risk for NAFLD, and 31 healthy volunteers) (mean age, 32.6 years ± 15.6 [standard deviation]; range, 8–66 years) gave informed consent and underwent MR spectroscopy and GRE MR imaging of the liver. Spectroscopy involved a long repetition time (to suppress T1 effects) and multiple echo times (to estimate T2 effects); the reference fat fraction (FF) was calculated from T2-corrected fat and water spectral peak areas. Imaging involved a low flip angle (to suppress T1 effects) and multiple echo times (to estimate T2* effects); imaging FF was calculated by using four analysis methods of progressive complexity: dual echo, triple echo, multiecho, and multiinterference. All methods except dual echo corrected for T2* effects. The multiinterference method corrected for multiple spectral interference effects of fat. For each method, the accuracy for diagnosis of fatty liver, as defined with a spectroscopic threshold, was assessed by estimating sensitivity and specificity; fat-grading accuracy was assessed by comparing imaging and spectroscopic FF values by using linear regression. Results: Dual-echo, triple-echo, multiecho, and multiinterference methods had a sensitivity of 0.817, 0.967, 0.950, and 0.983 and a specificity of 1.000, 0.880, 1.000, and 0.880, respectively. On the basis of regression slope and intercept, the multiinterference (slope, 0.98; intercept, 0.91%) method had high fat-grading accuracy without statistically significant error (P > .05). Dual-echo (slope, 0.98; intercept, −2.90%), triple-echo (slope, 0.94; intercept, 1.42%), and

  12. Quantitative T2 evaluation at 3.0T compared to morphological grading of the lumbar intervertebral disc: a standardized evaluation approach in patients with low back pain.

    PubMed

    Stelzeneder, David; Welsch, Goetz Hannes; Kovács, Balázs Krisztián; Goed, Sabine; Paternostro-Sluga, Tatjana; Vlychou, Marianna; Friedrich, Klaus; Mamisch, Tallal Charles; Trattnig, Siegfried

    2012-02-01

    The purpose of our investigation was to compare quantitative T2 relaxation time measurement evaluation of lumbar intervertebral discs with morphological grading in young to middle-aged patients with low back pain, using a standardized region-of-interest evaluation approach. Three hundred thirty lumbar discs from 66 patients (mean age, 39 years) with low back pain were examined on a 3.0T MR unit. Sagittal T1-FSE, sagittal, coronal, and axial T2-weighted FSE for morphological MRI, as well as a multi-echo spin-echo sequence for T2 mapping, were performed. Morphologically, all discs were classified according to Pfirrmann et al. Equally sized rectangular regions of interest (ROIs) for the annulus fibrosus were selected anteriorly and posteriorly in the outermost 20% of the disc. The space between was defined as the nucleus pulposus. To assess the reproducibility of this evaluation, inter- and intraobserver statistics were performed. The Pfirrmann scoring of 330 discs showed the following results: grade I: six discs (1.8%); grade II: 189 (57.3%); grade III: 96 (29.1%); grade IV: 38 (11.5%); and grade V: one (0.3%). The mean T2 values (in milliseconds) for the anterior and the posterior annulus, and the nucleus pulposus for the respective Pfirrmann groups were: I: 57/30/239; II: 44/67/129; III: 42/51/82; and IV: 42/44/56. The nucleus pulposus T2 values showed a stepwise decrease from Pfirrmann grade I to IV. The posterior annulus showed the highest T2 values in Pfirrmann group II, while the anterior annulus showed relatively constant T2 values in all Pfirrmann groups. The inter- and intraobserver analysis yielded intraclass correlation coefficients (ICC) for average measures in a range from 0.82 (anterior annulus) to 0.99 (nucleus). Our standardized method of region-specific quantitative T2 relaxation time evaluation seems to be able to characterize different degrees of disc degeneration quantitatively. The reproducibility of our ROI measurements is sufficient to

  13. Prognostic Value and Grading of MRI-Based T Category in Patients With Nasopharyngeal Carcinoma Without Lymph Node Metastasis Undergoing Intensity-Modulated Radiation Therapy

    PubMed Central

    Chen, Yu-Pei; Tang, Ling-Long; Zhang, Wen-Na; Mao, Yan-Ping; Chen, Lei; Sun, Ying; Liu, Li-Zhi; Li, Wen-Fei; Liu, Xu; Zhou, Guan-Qun; Guo, Rui; Mai, Hai-Qiang; Shao, Jian-Yong; Lin, Ai-Hua; Li, Li; Ma, Jun

    2015-01-01

    Abstract We investigated the prognostic value and gradation of the T category in N0 nasopharyngeal carcinoma (NPC) patients undergoing magnetic resonance imaging (MRI) and intensity-modulated radiotherapy (IMRT). A total of 749 patients were retrospectively reviewed, and a total of 181 N0 NPC patients were included in this retrospective study. All patients were restaged according to the 7th edition of the American Joint Committee on Cancer staging system. The following endpoints were estimated: overall survival (OS), progression-free survival (PFS), locoregional relapse-free survival (LRFS), and distant metastasis-free survival (DMFS). The 5-year survival rates for T1 to T4 were: OS (97.3%, 100.0%, 86.1%, and 82.8%; P = 0.007), PFS (94.6%, 96.9%, 76.5%, and 76.7%; P = 0.002), LRFS (98.5%, 100.0%, 92.2%, and 86.7%; P < 0.001), and DMFS (97.3%, 96.9%, 85.5%, and 85.7%; P = 0.042), respectively. Pairwise comparisons showed that the OS, PFS, and LRFS rates were significantly poorer in the advanced T categories (T3 and T4) than the early ones (T1 and T2), and no significant differences between T1 and T2, and T3 and T4 were found. In Cox's proportional hazard analysis, T category was found to be an independent prognostic factor only for PFS (P = 0.003). According to the primary tumor extent, we then graded all 181 N0 patients into 3 groups: group 1, early T category (n = 107); group 2, low-risk advanced T category (n = 35); and group 3, high-risk advanced T category (n = 39). The 5-year survival rates for the 3 groups were: OS (98.1%, 94.1%, and 76.3%; P < 0.001), PFS (95.3%, 88.2%, and 66.2%; P < 0.001), LRFS (99.0%, 97.0%, and 83.4%; P < 0.001), and DMFS (97.2%, 91.1%, and 80.4%; P = 0.002). The 5-year OS, PFS, and LRFS rates of group 3 differed significantly from those of groups 1 and 2, and a significant difference was observed in the DMFS rate only between groups 3 and 1. In Cox's proportional hazard analysis, the 3

  14. Use of Niobium High Strength Steels with 450 MPA Yield Strength for Construction

    NASA Astrophysics Data System (ADS)

    Silvestre, Leonardo; Langenberg, Peter; Amaral, Thiago; Carboni, Marcelo; Meira, Marcos; Jordão, Alexandre

    This paper presents an actual case of a new industrial building at CBMM's plant in Araxá, Brazil as an example of lean design using microalloyed steels. The structure consists mostly of microalloyed ASTM A572 steel grades 65 and 50 instead of the conventional carbon manganese ASTM A36 steel. The application of grade 65 with more than 450 MPa of yield strength is an innovative solution for this type of construction in South America. A complete welding evaluation performed on the low carbon, niobium microalloyed grade 65 steel showed the welding properties and benefits. Niobium's effect of increasing strength and toughness simultaneously resulted in relevant savings in total steel consumption for the project. The paper also quantifies the expected savings in costs, energy and carbon dioxide emissions.

  15. Stainless steel leaches nickel and chromium into foods during cooking.

    PubMed

    Kamerud, Kristin L; Hobbie, Kevin A; Anderson, Kim A

    2013-10-02

    Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel saucepan, cooking times of 2-20 h, 10 consecutive cooking cycles, and four commercial tomato sauces. After a simulated cooking process, samples were analyzed by ICP-MS for Ni and Cr. After 6 h of cooking, Ni and Cr concentrations in tomato sauce increased up to 26- and 7-fold, respectively, depending on the grade of stainless steel. Longer cooking durations resulted in additional increases in metal leaching, where Ni concentrations increased 34-fold and Cr increased approximately 35-fold from sauces cooked without stainless steel. Cooking with new stainless steel resulted in the largest increases. Metal leaching decreases with sequential cooking cycles and stabilized after the sixth cooking cycle, although significant metal contributions to foods were still observed. The tenth cooking cycle resulted in an average of 88 μg of Ni and 86 μg of Cr leached per 126 g serving of tomato sauce. Stainless steel cookware can be an overlooked source of nickel and chromium, where the contribution is dependent on stainless steel grade, cooking time, and cookware usage.

  16. Stainless Steel Leaches Nickel and Chromium into Foods During Cooking

    PubMed Central

    Kamerud, Kristin L.; Hobbie, Kevin A.; Anderson, Kim A.

    2014-01-01

    Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel saucepan; cooking times of 2 to 20 hours, ten consecutive cooking cycles, and four commercial tomato sauces. After a simulated cooking process, samples were analyzed by ICP-MS for Ni and Cr. After six hours of cooking, Ni and Cr concentrations in tomato sauce increased up to 26- and 7-fold respectively, depending on the grade of stainless steel. Longer cooking durations resulted in additional increases in metal leaching, where Ni concentrations increased 34 fold and Cr increased approximately 35 fold from sauces cooked without stainless steel. Cooking with new stainless steel resulted in the largest increases. Metal leaching decreases with sequential cooking cycles and stabilized after the sixth cooking cycle, though significant metal contributions to foods were still observed. The tenth cooking cycle, resulted in an average of 88 μg of Ni and 86 μg of Cr leached per 126 g serving of tomato sauce. Stainless steel cookware can be an overlooked source of nickel and chromium, where the contribution is dependent on stainless steel grade, cooking time, and cookware usage. PMID:23984718

  17. A new MRI grading system for chondromalacia patellae.

    PubMed

    Özgen, Ali; Taşdelen, Neslihan; Fırat, Zeynep

    2017-04-01

    Background Chondromalacia patellae is a very common disorder. Although magnetic resonance imaging (MRI) is widely used to investigate patellar cartilage lesions, there is no descriptive MRI-based grading system for chondromalacia patellae. Purpose To propose a new MRI grading system for chondromalacia patellae with corresponding high resolution images which might be useful in precisely reporting and comparing knee examinations in routine daily practice and used in predicting natural course and clinical outcome of the patellar cartilage lesions. Material and Methods High resolution fat-saturated proton density (FS PD) images in the axial plane with corresponding T2 mapping images were reviewed. A detailed MRI grading system covering the deficiencies of the existing gradings has been set and presented on these images. Two experienced observers blinded to clinical data examined 44 knee MR images and evaluated patellar cartilage changes according to the proposed grading system. Inter- and intra-rater validity testing using kappa statistics were calculated. Results A descriptive and detailed grading system with corresponding FS PD and T2 mapping images has been presented. Inter-rater agreement was 0.80 (95% confidence interval [CI], 0.71-0.89). Intra-rater agreements were 0.83 (95% CI, 0.74-0.91) for observer A and 0.79 (95% CI, 0.70-0.88) for observer B (k-values). Conclusion We present a new MRI grading system for chondromalacia patellae with corresponding images and good inter- and intra-rater agreement which might be useful in reporting and comparing knee MRI examinations in daily practice and may also have the potential for using more precisely predicting prognosis and clinical outcome of the patients.

  18. High Strength Reinforcing Steel Bars : Concrete Shear Friction Interface : final report : Part A.

    DOT National Transportation Integrated Search

    2017-03-01

    High-strength steel (HSS) reinforcement, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) steel reinf...

  19. High strength reinforcing steel bars : concrete shear friction interface : final report : Part A.

    DOT National Transportation Integrated Search

    2017-03-01

    High-strength steel (HSS) reinforcement, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) steel reinf...

  20. High strength reinforcing steel bars : low cycle fatigue behavior : final report - part B.

    DOT National Transportation Integrated Search

    2017-03-01

    High-strength steel (HSS) reinforcing steel, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) reinfor...

  1. High strength reinforcing steel bars : low-cycle fatigue behavior : final report - part B.

    DOT National Transportation Integrated Search

    2017-03-01

    High-strength steel (HSS) reinforcing steel, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) reinfor...

  2. T cell infiltrate and outcome following resection of intermediate-grade primary neuroendocrine tumours and liver metastases.

    PubMed

    Katz, Steven C; Donkor, Charan; Glasgow, Kristen; Pillarisetty, Venu G; Gönen, Mithat; Espat, N Joseph; Klimstra, David S; D'Angelica, Michael I; Allen, Peter J; Jarnagin, William; Dematteo, Ronald P; Brennan, Murray F; Tang, Laura H

    2010-12-01

    Tumour-infiltrating lymphocytes (TILs) have been shown to predict survival in numerous malignancies. The importance of TILs in primary pancreatic neuroendocrine tumours (NETs) and NET liver metastases (NETLMs) has not been defined. We identified 87 patients with NETs and 39 with NETLMs who had undergone resection. Immunohistochemistry was performed to determine TIL counts. Recurrence-free survival (RFS) and overall survival (OS) were determined using the log-rank test. The median follow-up time was 62 months in NET patients and 48 months in NETLM patients. Vascular invasion and histologic grade were the only independent predictors of outcome for NETs and NETLMs, respectively. Analysis of intermediate-grade NETs indicated that a dense T cell (CD3+) infiltrate was associated with a median RFS of 128 months compared with 61 months for those with low levels of intratumoral T cells (P= 0.05, univariate analysis). Examination of NETLMs revealed that a low level of infiltrating regulatory T cells (Treg, FoxP3+) was a predictor of prolonged survival (P < 0.01, univariate analysis). A robust T cell infiltrate is associated with improved RFS following resection of intermediate-grade NETs, whereas the presence of more Treg correlated with shorter OS after treatment of NETLMs. Further study of the immune response to intermediate-grade NETs and NETLMs is warranted.

  3. 40 CFR 91.316 - Hydrocarbon analyzer calibration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... operating adjustment using the appropriate fuel (see § 91.312) and purified synthetic air or zero-grade nitrogen. (2) One of the following procedures is required for FID or HFID optimization: (i) The procedure...) Initial and periodic calibration. Prior to introduction into service and monthly thereafter, or within one...

  4. Microstructure and corrosion behavior of shielded metal arc-welded dissimilar joints comprising duplex stainless steel and low alloy steel

    NASA Astrophysics Data System (ADS)

    Srinivasan, P. Bala; Muthupandi, V.; Sivan, V.; Srinivasan, P. Bala; Dietzel, W.

    2006-12-01

    This work describes the results of an investigation on a dissimilar weld joint comprising a boiler-grade low alloy steel and duplex stainless steel (DSS). Welds produced by shielded metal arc-welding with two different electrodes (an austenitic and a duplex grade) were examined for their microstructural features and properties. The welds were found to have overmatching mechanical properties. Although the general corrosion resistance of the weld metals was good, their pitting resistance was found to be inferior when compared with the DSS base material.

  5. Application of the Materials-by-Design Methodology to Redesign a New Grade of the High-Strength Low-Alloy Class of Steels with Improved Mechanical Properties and Processability

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Snipes, J. S.; Ramaswami, S.

    2016-01-01

    An alternative to the traditional trial-and-error empirical approach for the development of new materials is the so-called materials-by-design approach. Within the latter approach, a material is treated as a complex system and its design and optimization is carried out by employing computer-aided engineering analyses, predictive tools, and available material databases. In the present work, the materials-by-design approach is utilized to redesign a grade of high-strength low-alloy (HSLA) class of steels with improved mechanical properties (primarily strength and fracture toughness), processability (e.g., castability, hot formability, and weldability), and corrosion resistance. Toward that end, a number of material thermodynamics, kinetics of phase transformations, and physics of deformation and fracture computational models and databases have been developed/assembled and utilized within a multi-disciplinary, two-level material-by-design optimization scheme. To validate the models, their prediction is compared against the experimental results for the related steel HSLA100. Then the optimization procedure is employed to determine the optimal chemical composition and the tempering schedule for a newly designed grade of the HSLA class of steels with enhanced mechanical properties, processability, and corrosion resistance.

  6. Gliomas: Application of Cumulative Histogram Analysis of Normalized Cerebral Blood Volume on 3 T MRI to Tumor Grading

    PubMed Central

    Kim, Hyungjin; Choi, Seung Hong; Kim, Ji-Hoon; Ryoo, Inseon; Kim, Soo Chin; Yeom, Jeong A.; Shin, Hwaseon; Jung, Seung Chai; Lee, A. Leum; Yun, Tae Jin; Park, Chul-Kee; Sohn, Chul-Ho; Park, Sung-Hye

    2013-01-01

    Background Glioma grading assumes significant importance in that low- and high-grade gliomas display different prognoses and are treated with dissimilar therapeutic strategies. The objective of our study was to retrospectively assess the usefulness of a cumulative normalized cerebral blood volume (nCBV) histogram for glioma grading based on 3 T MRI. Methods From February 2010 to April 2012, 63 patients with astrocytic tumors underwent 3 T MRI with dynamic susceptibility contrast perfusion-weighted imaging. Regions of interest containing the entire tumor volume were drawn on every section of the co-registered relative CBV (rCBV) maps and T2-weighted images. The percentile values from the cumulative nCBV histograms and the other histogram parameters were correlated with tumor grades. Cochran’s Q test and the McNemar test were used to compare the diagnostic accuracies of the histogram parameters after the receiver operating characteristic curve analysis. Using the parameter offering the highest diagnostic accuracy, a validation process was performed with an independent test set of nine patients. Results The 99th percentile of the cumulative nCBV histogram (nCBV C99), mean and peak height differed significantly between low- and high-grade gliomas (P = <0.001, 0.014 and <0.001, respectively) and between grade III and IV gliomas (P = <0.001, 0.001 and <0.001, respectively). The diagnostic accuracy of nCBV C99 was significantly higher than that of the mean nCBV (P = 0.016) in distinguishing high- from low-grade gliomas and was comparable to that of the peak height (P = 1.000). Validation using the two cutoff values of nCBV C99 achieved a diagnostic accuracy of 66.7% (6/9) for the separation of all three glioma grades. Conclusion Cumulative histogram analysis of nCBV using 3 T MRI can be a useful method for preoperative glioma grading. The nCBV C99 value is helpful in distinguishing high- from low-grade gliomas and grade IV from III gliomas. PMID:23704910

  7. Life Assessment for Cr-Mo Steel Dissimilar Joints by Various Filler Metals Using Accelerated Creep Testing

    NASA Astrophysics Data System (ADS)

    Petchsang, S.; Phung-on, I.; Poopat, B.

    2016-12-01

    Accelerated creep rupture tests were performed on T22/T91 dissimilar metal joints to determine the fracture location and rupture time of different weldments. Four configurations of deposited filler metal were tested using gas tungsten arc welding to estimate the service life for Cr-Mo steel dissimilar joints at elevated temperatures in power plants. Results indicated that failure in all configurations occurred in the tempered original microstructure and tempered austenite transformation products (martensite or bainite structure) as type IV cracking at the intercritical area of the heat-affected zone (ICHAZ) for both T22 and T91 sides rather than as a consequence of the different filler metals. Creep damage occurred with the formation of precipitations and microvoids. The correlation between applied stress and the Larson-Miller parameter (PLM) was determined to predict the service life of each material configuration. Calculated time-to-failure based on the PLM and test results for both temperature and applied stress parameters gave a reasonable fit. The dissimilar joints exhibited lower creep rupture compared to the base material indicating creep degradation of the weldment.

  8. 49 CFR Appendix A to Part 178 - Specifications for Steel

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specifications for Steel A Appendix A to Part 178... to Part 178—Specifications for Steel Table 1 [Open-hearth, basic oxygen, or electric steel of uniform... limit for manganese on ladle analysis may be 1.40 percent. 6 Rephosphorized Grade 3 steels containing no...

  9. 49 CFR Appendix A to Part 178 - Specifications for Steel

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specifications for Steel A Appendix A to Part 178... to Part 178—Specifications for Steel Table 1 [Open-hearth, basic oxygen, or electric steel of uniform... limit for manganese on ladle analysis may be 1.40 percent. 6 Rephosphorized Grade 3 steels containing no...

  10. 49 CFR Appendix A to Part 178 - Specifications for Steel

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specifications for Steel A Appendix A to Part 178... to Part 178—Specifications for Steel Table 1 [Open-hearth, basic oxygen, or electric steel of uniform... limit for manganese on ladle analysis may be 1.40 percent. 6 Rephosphorized Grade 3 steels containing no...

  11. Quantitative T2 Magnetic Resonance Imaging Compared to Morphological Grading of the Early Cervical Intervertebral Disc Degeneration: An Evaluation Approach in Asymptomatic Young Adults

    PubMed Central

    Han, Zhihua; Shao, Lixin; Xie, Yan; Wu, Jianhong; Zhang, Yan; Xin, Hongkui; Ren, Aijun; Guo, Yong; Wang, Deli; He, Qing; Ruan, Dike

    2014-01-01

    Objective The objective of this study was to evaluate the efficacy of quantitative T2 magnetic resonance imaging (MRI) for quantifying early cervical intervertebral disc (IVD) degeneration in asymptomatic young adults by correlating the T2 value with Pfirrmann grade, sex, and anatomic level. Methods Seventy asymptomatic young subjects (34 men and 36 women; mean age, 22.80±2.11 yr; range, 18–25 years) underwent 3.0-T MRI to obtain morphological data (one T1-fast spin echo (FSE) and three-plane T2-FSE, used to assign a Pfirrmann grade (I–V)) and for T2 mapping (multi-echo spin echo). T2 values in the nucleus pulposus (NP, n = 350) and anulus fibrosus (AF, n = 700) were obtained. Differences in T2 values between sexes and anatomic level were evaluated, and linear correlation analysis of T2 values versus degenerative grade was conducted. Findings Cervical IVDs of healthy young adults were commonly determined to be at Pfirrmann grades I and II. T2 values of NPs were significantly higher than those of AF at all anatomic levels (P<0.000). The NP, anterior AF and posterior AF values did not differ significantly between genders at the same anatomic level (P>0.05). T2 values decreased linearly with degenerative grade. Linear correlation analysis revealed a strong negative association between the Pfirrmann grade and the T2 values of the NP (P = 0.000) but not the T2 values of the AF (P = 0.854). However, non-degenerated discs (Pfirrmann grades I and II) showed a wide range of T2 relaxation time. T2 values according to disc degeneration level classification were as follows: grade I (>62.03 ms), grade II (54.60–62.03 ms), grade III (<54.60 ms). Conclusions T2 quantitation provides a more sensitive and robust approach for detecting and characterizing the early stage of cervical IVD degeneration and to create a reliable quantitative in healthy young adults. PMID:24498384

  12. Quantitative T2 magnetic resonance imaging compared to morphological grading of the early cervical intervertebral disc degeneration: an evaluation approach in asymptomatic young adults.

    PubMed

    Chen, Chun; Huang, Minghua; Han, Zhihua; Shao, Lixin; Xie, Yan; Wu, Jianhong; Zhang, Yan; Xin, Hongkui; Ren, Aijun; Guo, Yong; Wang, Deli; He, Qing; Ruan, Dike

    2014-01-01

    The objective of this study was to evaluate the efficacy of quantitative T2 magnetic resonance imaging (MRI) for quantifying early cervical intervertebral disc (IVD) degeneration in asymptomatic young adults by correlating the T2 value with Pfirrmann grade, sex, and anatomic level. Seventy asymptomatic young subjects (34 men and 36 women; mean age, 22.80±2.11 yr; range, 18-25 years) underwent 3.0-T MRI to obtain morphological data (one T1-fast spin echo (FSE) and three-plane T2-FSE, used to assign a Pfirrmann grade (I-V)) and for T2 mapping (multi-echo spin echo). T2 values in the nucleus pulposus (NP, n = 350) and anulus fibrosus (AF, n = 700) were obtained. Differences in T2 values between sexes and anatomic level were evaluated, and linear correlation analysis of T2 values versus degenerative grade was conducted. Cervical IVDs of healthy young adults were commonly determined to be at Pfirrmann grades I and II. T2 values of NPs were significantly higher than those of AF at all anatomic levels (P<0.000). The NP, anterior AF and posterior AF values did not differ significantly between genders at the same anatomic level (P>0.05). T2 values decreased linearly with degenerative grade. Linear correlation analysis revealed a strong negative association between the Pfirrmann grade and the T2 values of the NP (P = 0.000) but not the T2 values of the AF (P = 0.854). However, non-degenerated discs (Pfirrmann grades I and II) showed a wide range of T2 relaxation time. T2 values according to disc degeneration level classification were as follows: grade I (>62.03 ms), grade II (54.60-62.03 ms), grade III (<54.60 ms). T2 quantitation provides a more sensitive and robust approach for detecting and characterizing the early stage of cervical IVD degeneration and to create a reliable quantitative in healthy young adults.

  13. Laser beam welding of new ultra-high strength and supra-ductile steels

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin

    2015-03-01

    Ultra-high strength and supra-ductile are entering fields of new applications. Those materials are excellent candidates for modern light-weight construction and functional integration. As ultra-high strength steels the stainless martensitic grade 1.4034 and the bainitic steel UNS 53835 are investigated. For the supra-ductile steels stand two high austenitic steels with 18 and 28 % manganese. As there are no processing windows an approach from the metallurgical base on is required. Adjusting the weld microstructure the Q+P and the QT steels require weld heat treatment. The HSD steel is weldable without. Due to their applications the ultra-high strength steels are welded in as-rolled and strengthened condition. Also the reaction of the weld on hot stamping is reflected for the martensitic grades. The supra-ductile steels are welded as solution annealed and work hardened by 50%. The results show the general suitability for laser beam welding.

  14. Report on Northwestern's Air-cooled, Copper Precipitation Hardened, High Strength, Weldable Steel Cast and Hot Rolled at Oregon Steel Mills

    DOT National Transportation Integrated Search

    1996-09-27

    This research has shown that a Grade 70 construction steel of 1/2- to 1-inch plate thicknesses can be produced without a quench and temper or accelerated cooling from hot-rolling if the Cu content in the steel is sufficiently high. Coherent very fine...

  15. MR elastography of the liver at 3.0 T in diagnosing liver fibrosis grades; preliminary clinical experience.

    PubMed

    Yoshimitsu, Kengo; Mitsufuji, Toshimichi; Shinagawa, Yoshinobu; Fujimitsu, Ritsuko; Morita, Ayako; Urakawa, Hiroshi; Hayashi, Hiroyuki; Takano, Koichi

    2016-03-01

    To clarify the usefulness of 3.0-T MR elastography (MRE) in diagnosing the histological grades of liver fibrosis using preliminary clinical data. Between November 2012 and March 2014, MRE was applied to all patients who underwent liver MR study at a 3.0-T clinical unit. Among them, those who had pathological evaluation of liver tissue within 3 months from MR examinations were retrospectively recruited, and the liver stiffness measured by MRE was correlated with histological results. Institutional review board approved this study, waiving informed consent. There were 70 patients who met the inclusion criteria. Liver stiffness showed significant correlation with the pathological grades of liver fibrosis (rho = 0.89, p < 0.0001, Spearman's rank correlation). Areas under the receiver operating characteristic curve were 0.93, 0.95, 0.99 and 0.95 for fibrosis score greater than or equal to F1, F2, F3 and F4, with cut-off values of 3.13, 3.85, 4.28 and 5.38 kPa, respectively. Multivariate analysis suggested that grades of necroinflammation also affected liver stiffness, but to a significantly lesser degree as compared to fibrosis. 3.0-T clinical MRE was suggested to be sufficiently useful in assessing the grades of liver fibrosis. MR elastography may help clinicians assess patients with chronic liver diseases. Usefulness of 3.0-T MR elastography has rarely been reported. Measured liver stiffness correlated well with the histological grades of liver fibrosis. Measured liver stiffness was also affected by necroinflammation, but to a lesser degree. 3.0-T MRE could be a non-invasive alternative to liver biopsy.

  16. Galvanic coupling between D6AC steel, 6061-T6 aluminum, Inconel 718 and graphite-epoxy composite material: Corrosion occurrence and prevention

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Higgins, R. H.

    1983-01-01

    The effects of galvanic coupling between D6AC steel, 6061-T6 aluminum, Inconel 718, and graphite-epoxy composite material (G/E) in 3.5% NaCl were studied. Measurements of corrosion potentials, galvanic currents and corrosion rates of the bare metals using weight-loss methods served to establish the need for corrosion protection in cases where D6AC steel and 6061-T6 aluminum are galvanically coupled to G/E in salt water while Inconel 718 was shown to be compatible with G/E. Six tests were made to study corrosion protective methods for eliminating galvanic corrosion in the cases of D6AC steel and 6061-T6 aluminum coupled to G/E. These results indicate that, when the G/E is completely coated with paint or a paint/polyurethane resin combination, satisfactory protection of the D6AC steel is achieved with either a coat of zinc-rich primer or a primer/topcoat combination. Likewise, satisfactory corrosion protection of the aluminum is achieved by coating it with an epoxy coating system.

  17. Tribological evaluation of high-speed steels with a regulated carbide phase

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Richter, Janusz

    2003-06-15

    Wear resistance of a commercial steel and titanium-niobium high-speed steels with a regulated carbide phase was evaluated by employing a micro-scale abrasive wear test with alumina particles. The worn volumes and corresponding wear coefficients were the lowest for the new non-ledeburitic grades containing titanium, then the two niobium grades, the conventional (both wrought and by powder metallurgy) steels exhibited the worse wear resistance. Fractography SEM observations together with energy-dispersive X-ray (EDX) chemical analysis revealed the decisive role of the steels' MC particles in the wear process. These carbides influenced the abrasion by stoppage of the wear scars and/or changing theirmore » trajectories. Directional and nondirectional abrasion modes in the steels tested using alumina and carborundum abrasives were found and are discussed.« less

  18. Welding Metallurgy and Weldability of Stainless Steels

    NASA Astrophysics Data System (ADS)

    Lippold, John C.; Kotecki, Damian J.

    2005-03-01

    Welding Metallurgy and Weldability of Stainless Steels, the first book in over twenty years to address welding metallurgy and weldability issues associated with stainless steel, offers the most up-to-date and comprehensive treatment of these topics currently available. The authors emphasize fundamental metallurgical principles governing microstructure evolution and property development of stainless steels, including martensistic, ferric, austenitic, duplex, and precipitation hardening grades. They present a logical and well-organized look at the history, evolution, and primary uses of each stainless steel, including detailed descriptions of the associated weldability issues.

  19. The World Health Organization 1973 classification system for grade is an important prognosticator in T1 non-muscle-invasive bladder cancer.

    PubMed

    van de Putte, Elisabeth E Fransen; Bosschieter, Judith; van der Kwast, Theo H; Bertz, Simone; Denzinger, Stefan; Manach, Quentin; Compérat, Eva M; Boormans, Joost L; Jewett, Michael A S; Stoehr, Robert; van Leenders, Geert J L H; Nieuwenhuijzen, Jakko A; Zlotta, Alexandre R; Hendricksen, Kees; Rouprêt, Morgan; Otto, Wolfgang; Burger, Maximilian; Hartmann, Arndt; van Rhijn, Bas W G

    2018-04-10

    To compare the prognostic value of the World Health Organization (WHO) 1973 and 2004 classification systems for grade in T1 bladder cancer (T1-BC), as both are currently recommended in international guidelines. Three uro-pathologists re-revised slides of 601 primary (first diagnosis) T1-BCs, initially managed conservatively (bacille Calmette-Guérin) in four hospitals. Grade was defined according to WHO1973 (Grade 1-3) and WHO2004 (low-grade [LG] and high-grade [HG]). This resulted in a lack of Grade 1 tumours, 188 (31%) Grade 2, and 413 (69%) Grade 3 tumours. There were 47 LG (8%) vs 554 (92%) HG tumours. We determined the prognostic value for progression-free survival (PFS) and cancer-specific survival (CSS) in Cox-regression models and corrected for age, sex, multiplicity, size and concomitant carcinoma in situ. At a median follow-up of 5.9 years, 148 patients showed progression and 94 died from BC. The WHO1973 Grade 3 was negatively associated with PFS (hazard ratio [HR] 2.1) and CSS (HR 3.4), whilst WHO2004 grade was not prognostic. On multivariable analysis, WHO1973 grade was the only prognostic factor for progression (HR 2.0). Grade 3 tumours (HR 3.0), older age (HR 1.03) and tumour size >3 cm (HR 1.8) were all independently associated with worse CSS. The WHO1973 classification system for grade has strong prognostic value in T1-BC, compared to the WHO2004 system. Our present results suggest that WHO1973 grade cannot be replaced by the WHO2004 classification in non-muscle-invasive BC guidelines. © 2018 The Authors BJU International © 2018 BJU International Published by John Wiley & Sons Ltd.

  20. Creation of superhydrophobic stainless steel surfaces by acid treatments and hydrophobic film deposition.

    PubMed

    Li, Lester; Breedveld, Victor; Hess, Dennis W

    2012-09-26

    In this work, we present a method to render stainless steel surfaces superhydrophobic while maintaining their corrosion resistance. Creation of surface roughness on 304 and 316 grade stainless steels was performed using a hydrofluoric acid bath. New insight into the etch process is developed through a detailed analysis of the chemical and physical changes that occur on the stainless steel surfaces. As a result of intergranular corrosion, along with metallic oxide and fluoride redeposition, surface roughness was generated on the nano- and microscales. Differences in alloy composition between 304 and 316 grades of stainless steel led to variations in etch rate and different levels of surface roughness for similar etch times. After fluorocarbon film deposition to lower the surface energy, etched samples of 304 and 316 stainless steel displayed maximum static water contact angles of 159.9 and 146.6°, respectively. However, etching in HF also caused both grades of stainless steel to be susceptible to corrosion. By passivating the HF-etched samples in a nitric acid bath, the corrosion resistant properties of stainless steels were recovered. When a three step process was used, consisting of etching, passivation and fluorocarbon deposition, 304 and 316 stainless steel samples exhibited maximum contact angles of 157.3 and 134.9°, respectively, while maintaining corrosion resistance.

  1. Fatigue performance of blade steel T552 in a corrosive environment

    NASA Astrophysics Data System (ADS)

    Janoušek, J.; Hřeben, S.; Špirit, Z.; Strejcius, J.; Kasl, J.

    2017-02-01

    This contribution is based on an experimental programme which deals with the issue of blade steel T552 corrosion fatigue damage. The specimens were taken from a reference material delivered for blade production and tested in a corrosion cell under pre-stress of 300 MPa. A chloride solution of 35 ppm was chosen as the environment at a temperature of 80 °C. Such an environment can be considered as the limit state that should not occur during the operating regime. The results are summarized and compared with experiments conducted at another workplace.

  2. Review of "Incomplete: How Middle Class Schools Aren't Making the Grade". Think Tank Review

    ERIC Educational Resources Information Center

    Baker, Bruce D.

    2011-01-01

    "Incomplete: How Middle Class Schools Aren't Making the Grade" is a new report from Third Way, a Washington, D.C.-based policy think tank. The report aims to convince parents, taxpayers and policymakers that they should be as concerned about middle-class schools not making the grade as they are about the failures of the nation's large, poor, urban…

  3. Radiation response of alloy T91 at damage levels up to 1000 peak dpa

    DOE PAGES

    Gigax, J. G.; Chen, T.; Kim, Hyosim; ...

    2016-10-04

    Ferritic/martensitic alloys are required for advanced reactor components to survive 500–600 neutron-induced dpa. In this paper, ion-induced void swelling of ferritic/martensitic alloy T91 in the quenched and tempered condition has been studied using a defocused, non-rastered 3.5 MeV Fe-ion beam at 475 °C to produce damage levels up to 1000 peak displacements per atom (dpa). The high peak damage level of 1000 dpa is required to reach 500–600 dpa level due to injected interstitial suppression of void nucleation in the peak dpa region, requiring data extraction closer to the surface at lower dpa levels. At a relatively low peak damagemore » level of 250 dpa, voids began to develop, appearing first in the near-surface region. With increasing ion fluence, swelling was observed deeper in the specimen, but remained completely suppressed in the back half of the ion range, even at 1000 peak dpa. The local differences in dpa rate in the front half of the ion range induce an “internal temperature shift” that strongly influences the onset of swelling, with shorter transient regimes resulting from lower dpa rates, in agreement not only with observations in neutron irradiation studies but also in various ion irradiations. Swelling was accompanied by radiation-induced precipitation of Cu-rich and Si, Ni, Mn-rich phases were observed by atom probe tomography, indicating concurrent microchemical evolution was in progress. Finally, in comparison to other ferritic/martensitic alloys during ion irradiation, T91 exhibits good swelling resistance with a swelling incubation period of about 400 local dpa.« less

  4. Investigations on Laser Beam Welding of Different Dissimilar Joints of Steel and Aluminum Alloys for Automotive Lightweight Construction

    NASA Astrophysics Data System (ADS)

    Seffer, Oliver; Pfeifer, Ronny; Springer, André; Kaierle, Stefan

    Due to the enormous potential of weight saving, and the consequential reduction of pollutant emissions, the use of hybrid components made of steel and aluminum alloys is increasing steadily, especially concerning automotive lightweight construction. However, thermal joining of steel and aluminum is still being researched, due to a limited solubility of the binary system of iron and aluminum causing the formation of hard and brittle intermetallic phases, which decrease the strength and the formability of the dissimilar seam. The presented results show the investigation of laser beam welding for joining different dissimilar hybrid components of the steel materials HX220LAD+Z100, 22MnB5+AS150 and 1.4301, as well as the aluminum alloy AA6016-T4 as a lap joint. Among other things, the influences of the energy per unit length, the material grade, the sheet thickness t, the weld type (lap weld, fillet weld) and the arrangement of the base materials in a lap joint (aluminum-sided irradiation, steel-sided irradiation) on the achievable strengths are analyzed. The characterization of the dissimilar joints includes tensile shear tests and metallographic analyses, depending on the energy per unit length.

  5. Recrystallization and modification of the stainless-steel surface relief under photonic heat load in powerful plasma discharges

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Budaev, V. P., E-mail: budaev@mail.ru; Martynenko, Yu. V.; Khimchenko, L. N.

    Targets made of ITER-grade 316L(N)-IG stainless steel and Russian-grade 12Cr18Ni10Ti stainless steel with a close composition were exposed at the QSPA-T plasma gun to plasma photonic radiation pulses simulating conditions of disruption mitigation in ITER. After a large number of pulses, modification of the stainless-steel surface was observed, such as the formation of a wavy structure, irregular roughness, and cracks on the target surface. X-ray and optic microscopic analyses of targets revealed changes in the orientation and dimensions of crystallites (grains) over a depth of up to 20 μm for 316L(N)-IG stainless steel after 200 pulses and up to 40more » μm for 12Cr18Ni10Ti stainless steel after 50 pulses, which is significantly larger than the depth of the layer melted in one pulse (∼10 μm). In a series of 200 tests of ITER-grade 316L(N)-IG ITER stainless steel, a linear increase in the height of irregularity (roughness) with increasing number of pulses at a rate of up to ∼1 μm per pulse was observed. No alteration in the chemical composition of the stainless-steel surface in the series of tests was revealed. A model is developed that describes the formation of wavy irregularities on the melted metal surface with allowance for the nonlinear stage of instability of the melted layer with a vapor/plasma flow above it. A decisive factor in this case is the viscous flow of the melted metal from the troughs to tops of the wavy structure. The model predicts saturation of the growth of the wavy structure when its amplitude becomes comparable with its wavelength. Approaches to describing the observed stochastic relief and roughness of the stainless-steel surface formed in the series of tests are considered. The recurrence of the melting-solidification process in which mechanisms of the hill growth compete with the spreading of the material from the hills can result in the formation of a stochastic relief.« less

  6. Fatigue Performance of Advanced High-Strength Steels (AHSS) GMAW Joints

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Zhili; Sang, Yan; Jiang, Cindy

    2009-01-01

    The fatigue performance of gas metal arc welding (GMAW) joints of advanced high strength steels (AHSS) are compared and analyzed. The steel studied included a number of different grades of AHSS and baseline mild steels: DP600, DP780, DP980, M130, M220, solution annealed boron steel, fully hardened boron steels, HSLA690 and DR210 (a mild steel). Fatigue testing was conducted under a number of nominal stress ranges to obtain the S/N curves of the weld joints. A two-phase analytical model is developed to predict the fatigue performance of AHSS welds. It was found that there are appreciable differences in the fatigue S/Nmore » curves among different AHSS joints made using the same welding practices, suggesting that the local microstructure in the weld toe and root region plays non-negligible role in the fatigue performance of AHSS welds. Changes in weld parameters can influence the joint characteristics which in turn influence fatigue life of the weld joints, particularly of those of higher strength AHSS. The analytical model is capable of reasonably predicting the fatigue performance of welds made with various steel grades in this study.« less

  7. Investigation of corrosion of welded joints of austenitic and duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Topolska, S.

    2016-08-01

    Investigation of corrosion resistance of materials is one of the most important tests that allow determining their functional properties. Among these tests the special group consist electrochemical investigations, which let to accelerate the course of the process. These investigations allow rapidly estimating corrosion processes occurring in metal elements under the influence of the analysed environment. In the paper are presented results of investigations of the resistance to pitting corrosion of the steel of next grades: austenitic 316L and duplex 2205. It was also analysed the corrosion resistance of welded joints of these grades of steel. The investigations were conducted in two different corrosion environments: in the neutral one (3.5 % sodium chloride) and in the aggressive one (0.1 M sulphuric acid VI). The obtained results indicate different resistance of analysed grades of steel and their welded joints in relation to the corrosion environment. The austenitic 316L steel characterizes by the higher resistance to the pitting corrosion in the aggressive environment then the duplex 2205 steel. In the paper are presented results of potentiodynamic tests. They showed that all the specimens are less resistant to pitting corrosion in the environment of sulphuric acid (VI) than in the sodium chloride one. The 2205 steel has higher corrosion resistance than the 316L stainless steel in 3.5% NaCl. On the other hand, in 0.1 M H2SO4, the 316L steel has a higher corrosion resistance than the 2205 one. The weld has a similar, very good resistance to pitting corrosion like both steels.

  8. Effects of Preheat on Weldments of NICOP Steel.

    DTIC Science & Technology

    1983-09-01

    copper in this low alloy steel . Taken into solid solution in the austenite phase , the copper can precipitate as fine... low alloy steel was intro- duced which contains 1.0-1.3% copper with a maximum of 0.07% carbon. This steel is designated as AST4 A710 grade A for... ferrite has formed, some copper may precipitate as a fine epsilon copper phase in the ferrite as the solubility of

  9. Process Hood Stand Support Steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    VAN KATWIJK, C.

    2000-04-03

    This package is written to comply with EN-6-035-00 for upgrade dedication of commercial grade items (CGI). The SNF-5953 CGI package provides the Technical evaluation to identify the critical characteristics and the acceptance criteria associated with the safety function of the Hood Stand Support Steel. Completion of the technical and quality requirements identified in the dedication package will provide enough data to be reasonably assured that CGI Hood Stand Support Steel will perform its SC function.

  10. Investigation of the plastic fracture of high strength steels

    NASA Technical Reports Server (NTRS)

    Cox, T. B.; Low, J. R., Jr.

    1972-01-01

    This investigation deals in detail with the three recognized stages of plastic fracture in high strength steels, namely, void initiation, void growth, and void coalescence. The particular steels under investigation include plates from both commercial purity and high purity heats of AISI 4340 and 18 Ni, 200 grade maraging steels. A scanning electron microscope equipped with an X-ray energy dispersive analyzer, together with observations made using light microscopy, revealed methods of improving the resistance of high strength steels to plastic fracture.

  11. Effect of mechanical vibrations on the wear behavior of AZ91 Mg alloy

    NASA Astrophysics Data System (ADS)

    Chaturvedi, V.; Pandel, U.; Sharma, A.

    2018-02-01

    AZ91 Mg alloy is the most promising alloy used for structural applications. The vibration induced methods are effective and economic viable in term of mechanical properties. Sliding wear tests were performed on AZ91 Mg alloy using a pin-on- disc configuration. Wear rates were measured at 5 N and 10N at a sliding velocity of 1m/s for varied frequency within the range of 5- 25Hz and a constant amplitude of 2mm. Microstructures of worn surfaces and wear debris were characterized by field emission scanning electron microscopy (FESEM). It is observed that wear resistance of vibrated AZ91 alloy at 15Hz frequency ad 2mm amplitude was superior than cast AZ91 Mg alloy. Finer grain size and equiaxed grain shape both are important parameters for better wear resistance in vibrated AZ91 Mg alloys. FESEM analysis revealed that wear is considerably affected due to frictional heat generated by the relative motion between AZ91 Mg alloy and EN31 steel surface. No single mechanism was responsible for material loss.

  12. Seismic performance of interior precast concrete beam-column connections with T-section steel inserts under cyclic loading

    NASA Astrophysics Data System (ADS)

    Ketiyot, Rattapon; Hansapinyo, Chayanon

    2018-04-01

    An experimental investigation was conducted to study the performance of precast beam-column concrete connections using T-section steel inserts into the concrete beam and joint core, under reversed cyclic loading. Six 2/3-scale interior beam-column subassemblies, one monolithic concrete specimen and five precast concrete specimens were tested. One precast specimen was a simple connection for a gravity load resistant design. Other precast specimens were developed with different attributes to improve their seismic performance. The test results showed that the performance of the monolithic specimen M1 represented ductile seismic behavior. Failure of columns and joints could be prevented, and the failure of the frame occurred at the flexural plastic hinge formation at the beam ends, close to the column faces. For the precast specimens, the splitting crack along the longitudinal lapped splice was a major failure. The precast P5 specimen with double steel T-section inserts showed better seismic performance compared to the other precast models. However, the dowel bars connected to the steel inserts were too short to develop a bond. The design of the precast concrete beams with lap splice is needed for longer lap lengths and should be done at the beam mid span or at the low flexural stress region.

  13. Distribution of Stress in Deformation Zone of Niobium Microalloyed Steel

    NASA Astrophysics Data System (ADS)

    Jandrlić, Ivan; Rešković, Stoja; Brlić, Tin

    2018-03-01

    Microalloyed steels today represent a significant part of total world production and processing of steel. Although widely used, there are scarce data on the stress distribution in the deformation zone of these steels. Research was carried out on two steel grades, both low-carbon structural steels with the same basic chemical composition, with one of them additionally microalloyed with niobium. Differences in the stress distribution in the deformation zone between two tested steels were continuously observed and measured using the methods of digital image correlation and thermography. It has been found out that niobium microalloyed steel has significantly more complex material flow and stress distribution in the deformation zone when compared to the plain low carbon steel.

  14. Distribution of Stress in Deformation Zone of Niobium Microalloyed Steel

    NASA Astrophysics Data System (ADS)

    Jandrlić, Ivan; Rešković, Stoja; Brlić, Tin

    2018-07-01

    Microalloyed steels today represent a significant part of total world production and processing of steel. Although widely used, there are scarce data on the stress distribution in the deformation zone of these steels. Research was carried out on two steel grades, both low-carbon structural steels with the same basic chemical composition, with one of them additionally microalloyed with niobium. Differences in the stress distribution in the deformation zone between two tested steels were continuously observed and measured using the methods of digital image correlation and thermography. It has been found out that niobium microalloyed steel has significantly more complex material flow and stress distribution in the deformation zone when compared to the plain low carbon steel.

  15. Machine-learning in grading of gliomas based on multi-parametric magnetic resonance imaging at 3T.

    PubMed

    Citak-Er, Fusun; Firat, Zeynep; Kovanlikaya, Ilhami; Ture, Ugur; Ozturk-Isik, Esin

    2018-06-15

    The objective of this study was to assess the contribution of multi-parametric (mp) magnetic resonance imaging (MRI) quantitative features in the machine learning-based grading of gliomas with a multi-region-of-interests approach. Forty-three patients who were newly diagnosed as having a glioma were included in this study. The patients were scanned prior to any therapy using a standard brain tumor magnetic resonance (MR) imaging protocol that included T1 and T2-weighted, diffusion-weighted, diffusion tensor, MR perfusion and MR spectroscopic imaging. Three different regions-of-interest were drawn for each subject to encompass tumor, immediate tumor periphery, and distant peritumoral edema/normal. The normalized mp-MRI features were used to build machine-learning models for differentiating low-grade gliomas (WHO grades I and II) from high grades (WHO grades III and IV). In order to assess the contribution of regional mp-MRI quantitative features to the classification models, a support vector machine-based recursive feature elimination method was applied prior to classification. A machine-learning model based on support vector machine algorithm with linear kernel achieved an accuracy of 93.0%, a specificity of 86.7%, and a sensitivity of 96.4% for the grading of gliomas using ten-fold cross validation based on the proposed subset of the mp-MRI features. In this study, machine-learning based on multiregional and multi-parametric MRI data has proven to be an important tool in grading glial tumors accurately even in this limited patient population. Future studies are needed to investigate the use of machine learning algorithms for brain tumor classification in a larger patient cohort. Copyright © 2018. Published by Elsevier Ltd.

  16. Camp Pendleton Saves 91% in Parking Lot Lighting

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    None

    2016-01-01

    Case study describes how Camp Pendleton Marine Corps Base replaced high-pressure sodium (HPS) fixtures in one parking lot with high-efficiency induction fixtures for 91% savings in energy use and $5,700 in cost savings annually. This parking lot is estimated to have a simple payback of 2.9 years. Sitewide up-grades yielded annual savings of 1 million kWh.

  17. 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.

  18. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tan, Lizhen; Kim, B. K.; Yang, Ying

    Ferritic-martensitic steels such as T91 and NF616 are candidate materials for several nuclear applications. Here, this study evaluates radiation resistance of T91 and NF616 by examining their microstructural evolutions and hardening after the samples were irradiated in the Advanced Test Reactor to ~4.3 displacements per atom (dpa) at an as-run temperature of 469 °C. In general, this irradiation did not result in significant difference in the radiation-induced microstructures between the two steels. Compared to NF616, T91 had a higher number density of dislocation loops and a lower level of radiation-induced segregation, together with a slightly higher radiation-hardening. Unlike dislocation loopsmore » developed in both steels, radiation-induced cavities were only observed in T91 but remained small with sub-10 nm sizes. Lastly, other than the relatively stable M 23C 6, a new phase (likely Sigma phase) was observed in T91 and radiation-enhanced MX → Z phase transformation was identified in NF616. Laves phase was not observed in the samples.« less

  19. In-pile tritium-permeation measurements on T91 tubes with double walls or a Fe-Al/Al 2O 3 coating

    NASA Astrophysics Data System (ADS)

    Conrad, R.; Bakker, K.; Chabrol, C.; Fütterer, M. A.; van der Laan, J. G.; Rigal, E.; Stijkel, M. P.

    2000-12-01

    Two new irradiation projects are being performed at the HFR Petten, named EXOTIC-8.9 and EXOTIC-8.10. Issues such as tritium release from candidate ceramic breeder pebbles for the HCPB blanket and tritium permeation through cooling tubes of the WCLL blanket are investigated simultaneously. In EXOTIC-8.9, the tritium release behaviour of a Li 2TiO 3 pebble bed is measured along with the tritium-permeation rate through a double-wall tube (DWT) of T91 with a Cu interlayer. In EXOTIC-8.10, the tritium release behaviour of a Li 4SiO 4 pebble bed is measured along with the tritium permeation rate through a T91 tube with a Fe-Al/Al 2O 3 coating as tritium permeation barrier (TPB). Tritium permeation phenomena are studied by variations of temperatures and purge gas conditions. This paper reports on the results of the first 100 irradiation days.

  20. Preoperative Albumin-Bilirubin Grade Predicts Recurrences After Radical Gastrectomy in Patients with pT2-4 Gastric Cancer.

    PubMed

    Kanda, Mitsuro; Tanaka, Chie; Kobayashi, Daisuke; Uda, Hiroaki; Inaoka, Kenichi; Tanaka, Yuri; Hayashi, Masamichi; Iwata, Naoki; Yamada, Suguru; Fujii, Tsutomu; Sugimoto, Hiroyuki; Murotani, Kenta; Fujiwara, Michitaka; Kodera, Yasuhiro

    2018-03-01

    The albumin-bilirubin (ALBI) score was initially developed for assessing liver dysfunction severity and was suggested to have prognostic value in patients with hepatocellular carcinoma. We aimed to evaluate the prognostic impact of ALBI grade in patients with advanced gastric cancer (GC) after radical gastrectomy. This study included 283 patients who underwent radical gastrectomy for pT2-4 GC without preoperative treatment. ALBI was calculated as follows: (log 10 bilirubin (μmol/L) × 0.66) + (albumin (g/L) × -0.0852) and categorized into grades 1 (≤-2.60), 2 (-2.60<, ≤-1.39) and 3 (-1.39<). The median ALBI score was -2.96, and a number of patients in ALBI grades 1, 2 and 3 were 228, 55 and 0, respectively. Patients with ALBI grade 2 had a lower administration rate of adjuvant chemotherapy than those with ALBI grade 1, whereas no significant differences were found in morbidity rate and disease stage. The ALBI grade 2 group was more likely to have shorter disease-specific and disease-free survival compared with the ALBI grade 1 group. Multivariable analysis identified ALBI grade 2 as an independent prognostic factor for disease-free survival (hazard ratio 1.97, 95% confidence interval 1.10-3.47, p = 0.0242). Survival differences between ALBI grade 1 and 2 groups were increased in the patient subset that received adjuvant chemotherapy. ALBI grade 2 was correlated with a shortened duration of administration of postoperative S-1 adjuvant. ALBI grade serves as a simple and promising predictive factor for disease-free and disease-specific survival in patients with pT2-4 GC after radical gastrectomy.

  1. Ultrahigh Ductility, High-Carbon Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Qin, Shengwei; Liu, Yu; Hao, Qingguo; Zuo, Xunwei; Rong, Yonghua; Chen, Nailu

    2016-10-01

    Based on the proposed design idea of the anti-transformation-induced plasticity effect, both the additions of the Nb element and pretreatment of the normalization process as a novel quenching-partitioning-tempering (Q-P-T) were designed for Fe-0.63C-1.52Mn-1.49Si-0.62Cr-0.036Nb hot-rolled steel. This high-carbon Q-P-T martensitic steel exhibits a tensile strength of 1890 MPa and elongation of 29 pct accompanied by the excellent product of tensile and elongation of 55 GPa pct. The origin of ultrahigh ductility for high-carbon Q-P-T martensitic steel is revealed from two aspects: one is the softening of martensitic matrix due to both the depletion of carbon in the matensitic matrix during the Q-P-T process by partitioning of carbon from supersaturated martensite to retained austenite and the reduction of the dislocation density in a martensitic matrix by dislocation absorption by retained austenite effect during deformation, which significantly enhances the deformation ability of martensitic matrix; another is the high mechanical stability of considerable carbon-enriched retained austenite, which effectively reduces the formation of brittle twin-type martensite. This work verifies the correctness of the design idea of the anti-TRIP effect and makes the third-generation advanced high-strength steels extend to the field of high-carbon steels from low- and medium-carbon steels.

  2. Magnetic Resonance Imaging for Patellofemoral Chondromalacia: Is There a Role for T2 Mapping?

    PubMed

    van Eck, Carola F; Kingston, R Scott; Crues, John V; Kharrazi, F Daniel

    2017-11-01

    Patellofemoral pain is common, and treatment is guided by the presence and grade of chondromalacia. To evaluate and compare the sensitivity and specificity in detecting and grading chondral abnormalities of the patella between proton density fat suppression (PDFS) and T2 mapping magnetic resonance imaging (MRI). Cohort study; Level of evidence, 2. A total of 25 patients who underwent MRI of the knee with both a PDFS sequence and T2 mapping and subsequently underwent arthroscopic knee surgery were included. The cartilage surface of the patella was graded on both MRI sequences by 2 independent, blinded radiologists. Cartilage was then graded during arthroscopic surgery by a sports medicine fellowship-trained orthopaedic surgeon. Reliability, sensitivity, specificity, and accuracy were determined for both MRI methods. The findings during arthroscopic surgery were considered the gold standard. Intraobserver and interobserver agreement for both PDFS (98.5% and 89.4%, respectively) and T2 mapping (99.4% and 91.3%, respectively) MRI were excellent. For T2 mapping, the sensitivity (61%) and specificity (64%) were comparable, whereas for PDFS there was a lower sensitivity (37%) but higher specificity (81%) in identifying cartilage abnormalities. This resulted in a similar accuracy for PDFS (59%) and T2 mapping (62%). Both PDFS and T2 mapping MRI were reliable but only moderately accurate in predicting patellar chondromalacia found during knee arthroscopic surgery.

  3. Effect of Heat Input on Geometry of Austenitic Stainless Steel Weld Bead on Low Carbon Steel

    NASA Astrophysics Data System (ADS)

    Saha, Manas Kumar; Hazra, Ritesh; Mondal, Ajit; Das, Santanu

    2018-05-01

    Among different weld cladding processes, gas metal arc welding (GMAW) cladding becomes a cost effective, user friendly, versatile method for protecting the surface of relatively lower grade structural steels from corrosion and/or erosion wear by depositing high grade stainless steels onto them. The quality of cladding largely depends upon the bead geometry of the weldment deposited. Weld bead geometry parameters, like bead width, reinforcement height, depth of penetration, and ratios like reinforcement form factor (RFF) and penetration shape factor (PSF) determine the quality of the weld bead geometry. Various process parameters of gas metal arc welding like heat input, current, voltage, arc travel speed, mode of metal transfer, etc. influence formation of bead geometry. In the current experimental investigation, austenite stainless steel (316) weld beads are formed on low alloy structural steel (E350) by GMAW using 100% CO2 as the shielding gas. Different combinations of current, voltage and arc travel speed are chosen so that heat input increases from 0.35 to 0.75 kJ/mm. Nine number of weld beads are deposited and replicated twice. The observations show that weld bead width increases linearly with increase in heat input, whereas reinforcement height and depth of penetration do not increase with increase in heat input. Regression analysis is done to establish the relationship between heat input and different geometrical parameters of weld bead. The regression models developed agrees well with the experimental data. Within the domain of the present experiment, it is observed that at higher heat input, the weld bead gets wider having little change in penetration and reinforcement; therefore, higher heat input may be recommended for austenitic stainless steel cladding on low alloy steel.

  4. Correlation of mechanical properties with metallurgical structure for 18Ni 200 grade maraging steel at room and cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Wagner, J. A.

    1991-01-01

    An extensive metallurgical study is presented which is intended to explain variations in the mechanical properties of Ni18 200 grade maraging steel in various product forms and orientations. Fracture toughness and Charpy impact values are found to decrease with decreasing temperature and be dependent on product form, specimen orientation, and metallurgical condition. Fatigue crack growth rates are dependent on temperature only. Fractographic analysis reveals that the decrease in toughness at -170 C is not associated with cleavage-type fracture morphology. Those specimens exhibiting low fracture toughness at room temperature or -170 C are found to have a significantly larger number of titanium-rich particles associated with dimple formation on the fracture surface.

  5. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Meimei; Wang, Leyun; Almer, Jonathan D.

    Deformation processes in Grade 91 (Fe–9%Cr–1%Mo–V,Nb) and Grade 92 (Fe–9%Cr–0.5%Mo–2%W–V,Nb) ferritic–martensitic steels were investigated at temperatures between 20 and 650 °C using high-energy synchrotron X-ray diffraction with in situ thermal–mechanical loading. The change of the dislocation density with strain was quantified by X-ray diffraction line profile analysis complemented by transmission electron microscopy measurements. The relationship between dislocation density and strain during uniform deformation was described by a dislocation model, and two critical materials parameters, namely dislocation mean free path and dynamic recovery coefficient, were determined as a function of temperature. Effects of alloy chemistry, thermal–mechanical treatment and temperature on themore » tensile deformation process in Grade 91 and Grade 92 steels can be well understood by the dislocation evolution behavior.« less

  6. The influence of surface microstructure and chemical composition on corrosion behaviour in fuel-grade bio-ethanol of low-alloy steel modified by plasma nitro-carburizing and post-oxidizing

    NASA Astrophysics Data System (ADS)

    Boniatti, Rosiana; Bandeira, Aline L.; Crespi, Ângela E.; Aguzzoli, Cesar; Baumvol, Israel J. R.; Figueroa, Carlos A.

    2013-09-01

    The interaction of bio-ethanol on steel surfaces modified by plasma-assisted diffusion technologies is studied for the first time. The influence of surface microstructure and chemical composition on corrosion behaviour of AISI 4140 low-alloy steel in fuel-grade bio-ethanol was investigated. The steel surfaces were modified by plasma nitro-carburizing followed plasma oxidizing. X-ray diffraction, scanning electron microscopy, optical microscopy, X-ray dispersive spectroscopy, and glow-discharge optical emission spectroscopy were used to characterize the modified surface before and after immersion tests in bio-ethanol up to 77 days. The main corrosion mechanism is pit formation. The pit density and pit size were measured in order to quantify the corrosion resistance which was found to depend more strongly on microstructure and morphology of the oxide layer than on its thickness. The best corrosion protection was observed for samples post-oxidized at 480 °C and 90 min.

  7. Enhancement of biocompatibility of 316LVM stainless steel by cyclic potentiodynamic passivation.

    PubMed

    Shahryari, Arash; Omanovic, Sasha; Szpunar, Jerzy A

    2009-06-15

    Passivation of stainless steel implants is a common procedure used to increase their biocompatibility. The results presented in this work demonstrate that the electrochemical cyclic potentiodynamic polarization (CPP) of a biomedical grade 316LVM stainless steel surface is a very efficient passivation method that can be used to significantly improve the material's general corrosion resistance and thus its biocompatibility. The influence of a range of experimental parameters on the passivation/corrosion protection efficiency is discussed. The passive film formed on a 316LVM surface by using the CPP method offers a significantly higher general corrosion resistance than the naturally grown passive film. The corresponding relative corrosion protection efficiency measured in saline during a 2-month period was 97% +/- 1%, which demonstrates a very high stability of the CPP-formed passive film. Its high corrosion protection efficiency was confirmed also at temperatures and chloride concentrations well above normal physiological levels. It was also shown that the CPP is a significantly more effective passivation method than some other surface-treatment methods commonly used to passivate biomedical grade stainless steels. In addition, the CPP-passivated 316LVM surface showed an enhanced biocompatibility in terms of preosteoblast (MC3T3) cells attachment. An increased thickness of the CPP-formed passive film and its enrichment with Cr(VI) and oxygen was determined to be the origin of the material's increased general corrosion resistance, whereas the increased surface roughness and surface (Volta) potential were suggested to be the origin of the enhanced preosteoblast cells attachment. Copyright 2008 Wiley Periodicals, Inc.

  8. Ultra-Low Carbon Bainitic Steels for Heavy Plate Applications

    DTIC Science & Technology

    1990-12-01

    these steels. The CCT diagrams 7 of steels typical of the HY grades indicate that the nose of the proeutectoid ferrite/pearlite reactions is located...austenite, carbides, and martensite. An example of the type of CCT diagram for one of the steels used in this investigation is presented in Figure 12...introduce a "bay" of unstable austenite which acts to separate the ferrite "nose" from the bainite/martensite regions on TTT or CCT diagrams , see Figure

  9. Preparing clinical grade Ag-specific T cells for adoptive immunotherapy trials

    PubMed Central

    DiGiusto, DL; Cooper, LJN

    2007-01-01

    The production of clinical-grade T cells for adoptive immunotherapy has evolved from the ex vivo numerical expansion of tumor-infiltrating lymphocytes to sophisticated bioengineering processes often requiring cell selection, genetic modification and other extensive tissue culture manipulations, to produce desired cells with improved therapeutic potential. Advancements in understanding the biology of lymphocyte signaling, activation, homing and sustained in vivo proliferative potential have redefined the strategies used to produce T cells suitable for clinical investigation. When combined with new technical methods in cell processing and culturing, the therapeutic potential of T cells manufactured in academic centers has improved dramatically. Paralleling these technical achievements in cell manufacturing is the development of broadly applied regulatory standards that define the requirements for the clinical implementation of cell products with ever-increasing complexity. In concert with academic facilities operating in compliance with current good manufacturing practice, the prescribing physician can now infuse T cells with a highly selected or endowed phenotype that has been uniformly manufactured according to standard operating procedures and that meets federal guidelines for quality of investigational cell products. In this review we address salient issues related to the technical, immunologic, practical and regulatory aspects of manufacturing these advanced T-cell products for clinical use. PMID:17943498

  10. Patellofemoral instability in children: T2 relaxation times of the patellar cartilage in patients with and without patellofemoral instability and correlation with morphological grading of cartilage damage.

    PubMed

    Kang, Chang Ho; Kim, Hee Kyung; Shiraj, Sahar; Anton, Christopher; Kim, Dong Hoon; Horn, Paul S

    2016-07-01

    Patellofemoral instability is one of the most common causes of cartilage damage in teenagers. To quantitatively evaluate the patellar cartilage in patients with patellofemoral instability using T2 relaxation time maps (T2 maps), compare the values to those in patients without patellofemoral instability and correlate them with morphological grades in patients with patellofemoral instability. Fifty-three patients with patellofemoral instability (mean age: 15.9 ± 2.4 years) and 53 age- and gender-matched patients without patellofemoral instability were included. Knee MR with axial T2 map was performed. Mean T2 relaxation times were obtained at the medial, central and lateral zones of the patellar cartilage and compared between the two groups. In the patellofemoral instability group, morphological grading of the patellar cartilage (0-4) was performed and correlated with T2 relaxation times. Mean T2 relaxation times were significantly longer in the group with patellofemoral instability as compared to those of the control group across the patellar cartilage (Student's t-test, P<0.05) with the longest time at the central area. Positive correlation was seen between mean T2 relaxation time and morphological grading (Pearson correlation coefficiency, P<0.001). T2 increased with severity of morphological grading from 0 to 3 (mixed model, P<0.001), but no statistical difference was seen between grades 3 and 4. In patellofemoral instability, patellar cartilage damage occurs across the entire cartilage with the highest T2 values at the apex. T2 relaxation times directly reflect the severity in low-grade cartilage damage, which implies an important role for T2 maps in differentiating between normal and low-grade cartilage damage.

  11. Corrosion Behavior of Steels in Supercritical CO 2 for Power Cycle Applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Repukaiti, Richard; Teeter, Lucas; Ziomek-Moroz, Margaret

    In order to understand issues with corrosion of heat exchanger materials in direct supercritical carbon dioxide (sCO 2) power cycles, a series of autoclave exposure experiments and electrochemical experiments have been conducted. Corrosion behaviors of 347H stainless steel and P91 martensitic-ferrtic steel in sCO 2 environment have been compared. In autoclave exposure tests performed at 50°C- 245°C and 80 bar. Mass change measurements, surface characterization, and corrosion product analysis have been conducted to understand the corrosion behavior of steels in sCO 2 containing H 2O and O 2. Electrochemical tests performed at room temperature and 50°C, a simulation environment ofmore » water condensation phase with dissolved CO 2 was prepared to evaluate the corrosion resistance of materials. From both types of experiments, generally 347H showed higher corrosion resistance than P91.« less

  12. T1 mapping combined with Gd-EOB-DTPA-enhanced magnetic resonance imaging in predicting the pathologic grading of hepatocellular carcinoma.

    PubMed

    Chen, C Y; Chen, J; Xia, C C; Huang, Z X; Song, B

    2017-01-01

    The aim of this study was to investigate the value of Gd-EOB-DTPA-enhanced MRI on hepatobiliary phase (HBP) imaging and T1 mapping sequence in the differentiation of hepatocellular carcinoma (HCC). A total of 45 patients with HCC who were to undergo a resection were enrolled in this study. Gd-EOB-DTPA-enhanced magnetic resonance examination was performed prior to resection. T1 mapping was performed before and 20 min after injection of Gd-EOB-DTPA. T1 values of the lesions were measured on pre-contrast (T1p) and during HBP (T1-HBP) on T1 maps. The signal intensity, the diameter and the margin of HCC lesions on HBP images were analyzed. The reduction in T1 value (T1d) and the reduction rate (ΔT1%) of T1 mapping between pre-contrast and HBP were calculated. The Edmondson-Steiner classification of each lesion was made after surgery. The SPSS software package was used for statistical analysis and the analysis of receiver operator characteristic (ROC) curve and area under the curve (AUC) were carried out by using MedCalc software package. Mean values of T1p and T1-HBP were 1935.4±730.8 ms and 1257.1±529.1 ms, respectively. T1p accuracy (AUC = 0.685, p = 0.037) in predicting pathological grading was similar to that of T1-HBP (AUC = 0.751, p = 0.005). A T1p of 1648.2 ms or greater had a sensitivity and specificity of 85.19% and 61.11%, respectively. A T1-HBP of 1006 ms or greater had a sensitivity and specificity of 81.84% and 61.11%, respectively. The number of HCCs with a non-smooth tumor margin was 20 (44.4%), and a non-smooth tumor margin correlated moderately with the Edmondson-Steiner grade (Spearman r = 0.491, p = 0.041). There was no significant correlation between T1d, ΔT1%, HCC signal intensity on HBP image and lesion diameter with pathologic grading. T1 mapping in pre-contrast and HBP of Gd-EOB-DTPA-enhanced MRI, a non-smooth tumor margin in the HBP of Gd-EOB-DTPA-enhanced MRI, are useful in predicting the pathologic grading of HCC.

  13. Superstrength of nanograined steel with nanoscale intermetallic precipitates transformed from shock-compressed martensitic steel

    PubMed Central

    Yu, Hailiang; Yan, Ming; Lu, Cheng; Tieu, Anh Kiet; Li, Huijun; Zhu, Qiang; Godbole, Ajit; Li, Jintao; Su, Lihong; Kong, Charlie

    2016-01-01

    An increasing number of industrial applications need superstrength steels. It is known that refined grains and nanoscale precipitates can increase strength. The hardest martensitic steel reported to date is C0.8 steel, whose nanohardness can reach 11.9 GPa through incremental interstitial solid solution strengthening. Here we report a nanograined (NG) steel dispersed with nanoscale precipitates which has an extraordinarily high hardness of 19.1 GPa. The NG steel (shock-compressed Armox 500T steel) was obtained under these conditions: high strain rate of 1.2 μs−1, high temperature rise rate of 600 Kμs−1 and high pressure of 17 GPa. The mean grain size achieved was 39 nm and reinforcing precipitates were indexed in the NG steel. The strength of the NG steel is expected to be ~3950 MPa. The discovery of the NG steel offers a general pathway for designing new advanced steel materials with exceptional hardness and excellent strength. PMID:27892460

  14. Improving the prediction of the final part geometry in high strength steels U drawing by means of advanced material and friction models

    NASA Astrophysics Data System (ADS)

    de Argandoña, Eneko Saenz; Mendiguren, Joseba; Otero, Irune; Mugarra, Endika; Otegi, Nagore; Galdos, Lander

    2018-05-01

    Steel has been used in vehicles from the automotive industry's inception. Different steel grades are continually being developed in order to satisfy new fuel economy requirements. For example, advanced high strength steel grades (AHSS) are widely used due to their good strength/weight ratio. Because each steel grade has a different microstructure composition and hardness, they show different behaviors when they are subjected to different strain paths. Similarly, the friction behavior when using different contact pressures is considerably altered. In the present paper, four different steel grades, ZSt380, DP600, DP780 and Fortiform 1050 materials are deeply characterized using uniaxial and cyclic tension-compression tests. Coefficient of friction (COF) is also obtained using strip drawing tests. These results have been used to calibrate mixed kinematic-hardening material models as well as pressure dependent friction models. Finally, the geometrical accuracy of the different material and friction models has been evaluated by comparing the numerical predictions with experimental demonstrators obtained using a U-Drawing tester.

  15. Heterogeneous strain and composite P-T paths: the key for unravelling complex tectonic histories in polymetamorphic high-grade terrains

    NASA Astrophysics Data System (ADS)

    van Reenen, Dirk D.; Smit, C. Andre

    2010-05-01

    Leonid Perchuk calculated the first P-T paths for eclogites almost 40 years ago [1] and since then he has shown that P-T paths if correctly constructed, represent an accurate record of the thermal and dynamic evolution of high-grade metamorphic complexes [2]. This implies that P-T paths might serve as the basis for geodynamic models for the formation and exhumation of such complexes from the lower crustal levels [2]. His continued research in the Limpopo Complex of southern Africa also played an important role in the next direction in the study of complex high-grade polymetamorphic complexes. This new direction involves the link between composite (kinked) P-T paths [5; 6; 8] and the critical role of heterogeneous strain in the development and preservation of distinct granulite facies events at the regional, outcrop, hand specimen, and thin section scales [7; 9; 10]. Heterogeneous deformation that operated on the thin section scale allowed the construction of kinked P-T paths from single thin sections [5; 6; 9] and the integration of the P-T data with structural and isotopic geochronology [7; 9; 10]. D-P-T-t paths thus constructed not only allow the nature of polymetamorphism in the Limpopo Complex of southern Africa to be established, but also assisted in the construction of tectonic models for the evolution of this complex high-grade polymetamorphic complex. This complex evolution is demonstrated by the configuration of a kinked P-T path (5; 9) that reflects the following distinct stages of the multi-cycle D-P-T-t evolution of the Central Zone: (i) the earliest DC1 path reflects the emplacement before ~2.63Ga of the Limpopo Complex at the crustal level of ~20km. The DC1 stage of the D1/M1 exhumation event was accompanied by the formation of early D2A isoclinal folds; (ii) The DC2 stage of the D1/M1 exhumation event reflects the emplacement before ~2.61Ga of the rocks at the crustal level of ~15km. The DC2 stage was accompanied by the formation of major D2B sheath

  16. Assessment of weld quality of aerospace grade metals by using ultrasonic matrix phased array technology

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-03-01

    Advantages of two dimensional electronic ultrasonic beam focusing, steering and scanning with the matrix phased array (MPA) technology has been used to visualize the conditions of resistance spot welds in auto vehicle grade advanced high strength steel carbon steels nondestructively. Two of the commonly used joining techniques, resistance spot welding and resistance seam welding, for thin aerospace grade plates made of aluminum, titanium, and stainless steels have also been inspected with the same MPA NDE system. In this study, a detailed discussions of the current MPA based ultrasonic real time imaging methodology has been made followed by some of the NDT results obtained with various welded test coupons.

  17. Dissimilar Arc Welding of Advanced High-Strength Car-Body Steel Sheets

    NASA Astrophysics Data System (ADS)

    Russo Spena, P.; D'Aiuto, F.; Matteis, P.; Scavino, G.

    2014-11-01

    A widespread usage of new advanced TWIP steel grades for the fabrication of car-body parts is conditional on the employment of appropriate welding methods, especially if dissimilar welding must be performed with other automotive steel grades. Therefore, the microstructural features and the mechanical response of dissimilar butt weld seams of TWIP and 22MnB5 steel sheets after metal-active-gas arc welding are examined. The microstructural and mechanical characterization of the welded joints was carried out by optical metallography, microhardness and tensile testing, and fractographic examination. The heat-affected zone on the TWIP side was fully austenitic and the only detectable effect was grain coarsening, while on the 22MnB5 side it exhibited newly formed martensite and tempered martensite. The welded tensile specimens exhibited a much larger deformation on the TWIP steel side than on the 22MnB5. The fracture generally occurred at the interface between the fusion zone and the heat-affected zones, with the fractures surfaces being predominantly ductile. The ultimate tensile strength of the butt joints was about 25% lower than that of the TWIP steel.

  18. Effect of Ladle Usage on Cleanliness of Bearing Steel

    NASA Astrophysics Data System (ADS)

    Chi, Yunguang; Deng, Zhiyin; Zhu, Miaoyong

    2018-02-01

    To investigate the effects of ladle usage on the inclusions and total oxygen contents of bearing steel, MgO refractory rods with different glazes were used to simulate different ladle usages. The results show that the effects of different ladle usages on the cleanliness of the steel differ from each other. The total oxygen content of steel increases with the decreasing glaze basicity. Ladle glaze having a lower basicity has a more negative impact on the cleanliness of steel in the subsequent production. Inclusions can be generated by the flush-off of ladle glaze, and the initial glaze is important in the evolution of inclusions in the subsequent heats. To avoid the negative effect of ladle usage and to improve the steel cleanliness as much as possible, specialized ladles were suggested for producing high-quality steel grades.

  19. The corrosion performance of high chromium stainless steels and titanium alloys at a reverse osmosis plant in Arabian Gulf seawater

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Al-Odwani, A.; Al-Tabatabaei, M.; Carew, J.

    1997-08-01

    Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion performance of four high chromium stainless steels and Grade 2 titanium in flowing Arabian Gulf natural seawater. The EIS provided information concerning the changes to the interfacial impedance as a function of exposure time for these alloys. The impedance spectra for all the alloys showed slight changes at the low frequency region over the exposure period. The open-circuit potentials (OCP) of these alloys were also monitored as a function of exposure time. The stainless steel alloys exhibited slight fluctuation in potential around the initial exposure potential. However, Grade 2 titaniummore » initial potential was more active and then gradually shifted towards the noble direction. The linear polarization resistance (LPR) method indicated that Grade 2 titanium exhibited the lowest corrosion rate with respect to the stainless steel alloys. The results of the EIS analysis and OCP indicated that Grade 2 titanium performed better than the four high chromium stainless steel alloys.« less

  20. Corrosion resistance of 0Kh18N10T steel in gadolinium nitrate solutions in the liquid regulation of the reactivity of nuclear reactors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ganzha, V.D.; Konoplev, K.A.; Mashchetov, V.P.

    1986-03-01

    This study was carried out in connection with the preparation of the design for the PIK research reactor. The corrosion resistance of 0Kh18N10T steel in gadolinium nitrate solutions was tested in laboratory, ampule, and loop corrosion tests. At all stages of the tests, the authors investigated the effect produced on the corrosion processes by factors related to the technology of preparation of the equipment (mechanical working of the surfaces, welding, sensitizing, annealing, stressed state of the material, cracks, etc.). Ampule tests were conducted in order to determine the effect produced by reactor radiation and shutdown regimes on the corrosion resistancemore » of the steel. Special ampules made of 0Kh18N10T steel were filled with gadolinium nitrate solutions of various concentrations, sealed, and irradiated for a long period in the core of the VVR-M reactor at a temperature of 20-50 degrees C. The results of the tests are shown. The investigations showed that the corrosion of 0Kh18N10T steel in solutions of gadolinium nitrate is uniform, regardless of the state of the surface, the concentration of gadolinium nitrate, the duration of the tests, the action of the reactor radiation under static and dynamic conditions, and the presence of mechanical stresses.« less

  1. Clinical-Grade Human Multipotent Adult Progenitor Cells Block CD8+ Cytotoxic T Lymphocytes

    PubMed Central

    Dekimpe, Emily; Van Woensel, Matthias; Roobrouck, Valerie D.; Bullens, Dominique M.; Pinxteren, Jef; Verfaillie, Catherine M.; Van Gool, Stefaan W.

    2016-01-01

    MultiStem cells are clinical-grade multipotent adult bone marrow-derived progenitor cells (MAPCs), with extensive replication potential and broader differentiation capacity compared with mesenchymal stem cells. Human MAPCs suppress T-cell proliferation induced by alloantigens and mutually interact with allogeneic natural killer cells. In this study, the interaction between MultiStem and CD8+ cytotoxic T lymphocytes (CTLs) was addressed for the first time. In an in vitro setting, the immunogenicity of MultiStem, the susceptibility of MultiStem toward CTL-mediated lysis, and its effects on CTL function were investigated. MultiStem was nonimmunogenic for alloreactive CTL induction and was—even after major histocompatibility complex class I upregulation—insensitive to alloantigen-specific CTL-mediated lysis. Furthermore, MultiStem reduced CTL proliferation and significantly decreased perforin expression during the T-cell activation phase. As a consequence, MultiStem dose-dependently impaired the induction of CTL function. These effects of MultiStem were mediated predominantly through contact-dependent mechanisms. Moreover, MultiStem cells considerably influenced the expression of T-cell activation markers CD25, CD69, and human leukocyte antigen-DR. The MultiStem-induced CD8−CD69+ T-cell population displayed a suppressive effect on the induction of CTL function during a subsequent mixed-lymphocyte culture. Finally, the killer activity of activated antigen-specific CTLs during their cytolytic effector phase was also diminished in the presence of MultiStem. This study confirms that these clinical-grade MAPCs are an immune-modulating population that inhibits CTL activation and effector responses and are, consequently, a highly valuable cell population for adoptive immunosuppressive therapy in diseases where damage is induced by CTLs. Significance Because multipotent adult progenitor cells (MAPCs) are among the noteworthy adult mesenchymal stem cell populations for

  2. Clinical-Grade Human Multipotent Adult Progenitor Cells Block CD8+ Cytotoxic T Lymphocytes.

    PubMed

    Plessers, Jeroen; Dekimpe, Emily; Van Woensel, Matthias; Roobrouck, Valerie D; Bullens, Dominique M; Pinxteren, Jef; Verfaillie, Catherine M; Van Gool, Stefaan W

    2016-12-01

    : MultiStem cells are clinical-grade multipotent adult bone marrow-derived progenitor cells (MAPCs), with extensive replication potential and broader differentiation capacity compared with mesenchymal stem cells. Human MAPCs suppress T-cell proliferation induced by alloantigens and mutually interact with allogeneic natural killer cells. In this study, the interaction between MultiStem and CD8 + cytotoxic T lymphocytes (CTLs) was addressed for the first time. In an in vitro setting, the immunogenicity of MultiStem, the susceptibility of MultiStem toward CTL-mediated lysis, and its effects on CTL function were investigated. MultiStem was nonimmunogenic for alloreactive CTL induction and was-even after major histocompatibility complex class I upregulation-insensitive to alloantigen-specific CTL-mediated lysis. Furthermore, MultiStem reduced CTL proliferation and significantly decreased perforin expression during the T-cell activation phase. As a consequence, MultiStem dose-dependently impaired the induction of CTL function. These effects of MultiStem were mediated predominantly through contact-dependent mechanisms. Moreover, MultiStem cells considerably influenced the expression of T-cell activation markers CD25, CD69, and human leukocyte antigen-DR. The MultiStem-induced CD8 - CD69 + T-cell population displayed a suppressive effect on the induction of CTL function during a subsequent mixed-lymphocyte culture. Finally, the killer activity of activated antigen-specific CTLs during their cytolytic effector phase was also diminished in the presence of MultiStem. This study confirms that these clinical-grade MAPCs are an immune-modulating population that inhibits CTL activation and effector responses and are, consequently, a highly valuable cell population for adoptive immunosuppressive therapy in diseases where damage is induced by CTLs. Because multipotent adult progenitor cells (MAPCs) are among the noteworthy adult mesenchymal stem cell populations for immune therapy

  3. Long-Term Corrosion Fatigue of Welded Marine Steels.

    DTIC Science & Technology

    1984-01-01

    MPa ksi MPa I C API 5L Grade B 35 240 60 min. 415 mrin. ASTM A53 Grade B 35 240 60 min. 415 min. ASTM A135 Grade B 35 240 60 min. 415 min. ASTM A139...2% max. cold expansion 42 290 60 min. 415 min. API 5LX Grade X52 2% max. cold expansion 52 360 66 min. 455 min. ASTM AS00 Grade B 42-46 290-320 58 mi...Environments 3.38 " 3.5 Influence of Load Ratio on the Corrosion Fatigue Crack Growth Rates in API X-70 Linepipe Steel in 3.5% NaCl (From (3.30]) 3.39 3.6

  4. Cyclic softening based on dislocation annihilation at sub-cell boundary for SA333 Grade-6 C-Mn steel

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, S.; Dhar, S.; Acharyya, S. K.; Gupta, S. K.

    2018-01-01

    In this work, the response of SA333 Grade-6 C-Mn steel subjected to uniaxial and in-phase biaxial tension-torsion cyclic loading is experimented and an attempt is made to model the material behaviour. Experimentally observed cyclic softening is modelled based on ‘dislocation annihilation at low angle grain boundary’, while Ohno-Wang kinematic hardening rule is used to simulate the stress-strain hysteresis loops. The relevant material parameters are extracted from the appropriate experimental results and metallurgical investigations. The material model is plugged as user material subroutine into ABAQUS FE platform to simulate pre-saturation low cycle fatigue loops with cyclic softening and other cyclic plastic behaviour under prescribed loading. The stress-strain hysteresis loops and peak stress with cycles were compared with the experimental results and good agreements between experimental and simulated results validated the material model.

  5. Formation of Wear Resistant Steel Surfaces by Plasma Immersion Ion Implantation

    NASA Astrophysics Data System (ADS)

    Mändl, S.; Rauschenbach, B.

    2003-08-01

    Plasma immersion ion implantation (PIII) is a versatile and fast method for implanting energetic ions into large and complex shaped three-dimensional objects where the ions are accelerated by applying negative high voltage pulses to a substrate immersed in a plasma. As the line-of-sight restrictions of conventional implanters are circumvented, it results in a fast and cost-effective technology. Implantation of nitrogen at 30 - 40 keV at moderate temperatures of 200 - 400 °C into steel circumvents the diminishing thermal nitrogen activation encountered, e.g., in plasma nitriding in this temperature regime, thus enabling nitriding of additional steel grades. Nitride formation and improvement of the mechanical properties after PIII are presented for several steel grades, including AISI 316Ti (food industry), AISI D2 (used for bending tools) and AISI 1095 (with applications in the textile industry).

  6. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., or electric furnace process steel of uniform quality is authorized. The steel analysis must conform... inches in diameter. (4) All openings must be circular. (5) All openings must be threaded. Threads must be in compliance with the following: (i) Each thread must be clean cut, even, without any checks, and to...

  7. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., or electric furnace process steel of uniform quality is authorized. The steel analysis must conform... inches in diameter. (4) All openings must be circular. (5) All openings must be threaded. Threads must be in compliance with the following: (i) Each thread must be clean cut, even, without any checks, and to...

  8. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., or electric furnace process steel of uniform quality is authorized. The steel analysis must conform... inches in diameter. (4) All openings must be circular. (5) All openings must be threaded. Threads must be in compliance with the following: (i) Each thread must be clean cut, even, without any checks, and to...

  9. Ultrasonic Characterization of Aging Behavior in M250 Grade Maraging Steel

    NASA Astrophysics Data System (ADS)

    Yeheskel, Ori

    2009-03-01

    The increase in sound velocities during the aging of M250 maraging steel reported by Rajkumar et al. was analyzed. The present article provides a new perspective on why and to what extent the sound velocities change during aging. The main parameter that affects the elastic moduli and the sound velocities in the early and intermediate stages of aging in maraging steel is the depletion of Ni from the martensitic matrix due to Ni3Ti and Ni3Mo formation. The issue of sound velocity increase with aging time was addressed here in a few different ways to support the validity of Ni depletion.

  10. Production of Nanocrystalline Ni-20Cr Coatings for High-Temperature Applications

    NASA Astrophysics Data System (ADS)

    Kumar, Manoj; Singh, Harpreet; Singh, Narinder

    2014-04-01

    Presynthesized nanocrystalline Ni-20Cr powder was deposited on SA 516 and T91 boiler steels by a high-velocity oxy-fuel spraying process. Ni-20Cr powder was synthesized by the ball milling approach. The high-temperature oxidation behavior of bare and coated samples was then studied under cyclic isothermal conditions at 900 °C for 50 cycles. The kinetics of oxidation was established using weight change measurements for the bare and coated boiler steels. Uncoated and coated samples of T91 steel were exposed to the superheated zone of a power plant boiler at 750 °C under cyclic conditions for 15 cycles. Each cycle consisted of 100 h of heating followed by 1 h of cooling. Attempts were made to study the kinetics of erosion-corrosion using weight change and thickness loss data for the samples. Different characterization techniques were used to study the oxidized and eroded-corroded samples, including x-ray diffraction, scanning electron microscopy/energy-dispersive spectroscopy, and x-ray mapping analyses. The Ni-20Cr alloy powder coating was found to offer excellent oxidation resistance to the base steels and was successful in reducing the weight gain of SA 516 steel by 98.5 % and that of T91 steel by 65 %. The coating was observed to reduce the erosion-corrosion rate of T91 steel by 86 % in terms of thickness loss. This indicates that the investigated nanostructured coating can be a better choice over conventional coating for erosion-corrosion control of boiler tubes.

  11. Tensile strength/yield strength (TS/YS) ratios of high-strength steel (HSS) reinforcing bars

    NASA Astrophysics Data System (ADS)

    Tavio, Anggraini, Retno; Raka, I. Gede Putu; Agustiar

    2018-05-01

    The building codes such as American Concrete Institute (ACI) 318M-14 and Standard National Indonesia (SNI) 2847:2013 require that the ratio of tensile strength (TS) and yield strength (YS) should not less than 1.25. The requirement is based on the assumption that a capability of a structural member to develop inelastic rotation capacity is a function of the length of the yield region. This paper reports an investigation on various steel grades, namely Grades 420, 550, 650, and 700 MPa, to examine the impact of different TS/YS ratios if it is less or greater than the required value. Grades 550, 650, and 700 MPa were purposely selected with the intention to examine if these higher grades are still promising to be implemented in special structural systems since they are prohibited by the building codes for longitudinal reinforcement, whereas Grade 420 MPa bars are the maximum limit of yield strength of reinforcing bars that is allowable for longitudinal reinforcement of special structural systems. Tensile tests of these steel samples were conducted under displacement controlled mode to capture the complete stress-strain curves and particularly the post-yield response of the steel bars. From the study, it can be concluded that Grade 420 performed higher TS/YS ratios and they were able to reach up to more than 1.25. However, the High Strength Still (HSS) bars (Grades 550, 600, and 700 MPa) resulted in lower TS/YS ratios (less than 1.25) compared with those of Grade 420 MPa.

  12. Effect of formation and state of interface on joint strength in friction stir spot welding for advanced high strength steel sheets

    NASA Astrophysics Data System (ADS)

    Taniguchi, Koichi; Matsushita, Muneo; Ikeda, Rinsei; Oi, Kenji

    2014-08-01

    The tensile shear strength and cross tension strength of friction stir spot welded joints were evaluated in the cases of lap joints of 270 N/mm2 grade and 980 N/mm2 grade cold rolled steel sheets with respect to the stir zone area, hardness distribution, and interface condition between the sheets. The results suggested that both the tensile shear strength and cross tension strength were based on the stir zone area and its hardness in both grades of steel. The "hook" shape of the interface also affected the joint strength. However, the joining that occurred across the interfaces had a significant influence on the value of the joint strength in the case of the 270 N/mm2 grade steel.

  13. Effect of decreased hot-rolling reduction treatment on fracture toughness of low-alloy structural steels

    NASA Astrophysics Data System (ADS)

    Tomita, Yoshiyuki

    1990-09-01

    Commercial low-alloy structural steels, 0.45 pct C (AISI 1045 grade), 0.40 pct C-Cr-Mo (AISI 4140 grade), and 0.40 pct C-Ni-Cr-Mo (AISI 4340 grade), have been studied to determine the effect of the decreased hot-rolling reduction treatment (DHRRT) from 98 to 80 pct on fracture toughness of quenched and highly tempered low-alloy structural steels. The significant conclusions are as follows: (1) the sulfide inclusions were modified through the DHRRT from a stringer (mean aspect ratio: 16.5 to 17.6) to an ellipse (mean aspect ratio: 3.8 to 4.5), independent of the steels studied; (2) the DHRRT significantly improved J Ic in the long-transverse and shorttransverse orientations, independent of the steels studied; and (3) the shelf energy in the Charpy V-notch impact test is also greatly improved by the DHRRT, independent of testing orientation and steels studied; however, (4) the ductile-to-brittle transition temperature was only slightly affected by the DHRRT. The beneficial effect on the J Ic is briefly discussed in terms of a crack extension model involving the formation of voids at the inclusion sites and their growth and eventual linking up through the rupture of the intervening ligaments by local shear.

  14. Diagnostic accuracy of magnetic resonance imaging techniques for treatment response evaluation in patients with high-grade glioma, a systematic review and meta-analysis.

    PubMed

    van Dijken, Bart R J; van Laar, Peter Jan; Holtman, Gea A; van der Hoorn, Anouk

    2017-10-01

    Treatment response assessment in high-grade gliomas uses contrast enhanced T1-weighted MRI, but is unreliable. Novel advanced MRI techniques have been studied, but the accuracy is not well known. Therefore, we performed a systematic meta-analysis to assess the diagnostic accuracy of anatomical and advanced MRI for treatment response in high-grade gliomas. Databases were searched systematically. Study selection and data extraction were done by two authors independently. Meta-analysis was performed using a bivariate random effects model when ≥5 studies were included. Anatomical MRI (five studies, 166 patients) showed a pooled sensitivity and specificity of 68% (95%CI 51-81) and 77% (45-93), respectively. Pooled apparent diffusion coefficients (seven studies, 204 patients) demonstrated a sensitivity of 71% (60-80) and specificity of 87% (77-93). DSC-perfusion (18 studies, 708 patients) sensitivity was 87% (82-91) with a specificity of 86% (77-91). DCE-perfusion (five studies, 207 patients) sensitivity was 92% (73-98) and specificity was 85% (76-92). The sensitivity of spectroscopy (nine studies, 203 patients) was 91% (79-97) and specificity was 95% (65-99). Advanced techniques showed higher diagnostic accuracy than anatomical MRI, the highest for spectroscopy, supporting the use in treatment response assessment in high-grade gliomas. • Treatment response assessment in high-grade gliomas with anatomical MRI is unreliable • Novel advanced MRI techniques have been studied, but diagnostic accuracy is unknown • Meta-analysis demonstrates that advanced MRI showed higher diagnostic accuracy than anatomical MRI • Highest diagnostic accuracy for spectroscopy and perfusion MRI • Supports the incorporation of advanced MRI in high-grade glioma treatment response assessment.

  15. Fatigue Crack Growth Behavior of Gas Metal Arc Welded AISI 409 Grade Ferritic Stainless Steel Joints

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, A. K.; Shanmugam, K.; Balasubramanian, V.

    2009-10-01

    The effect of filler metals such as austenitic stainless steel, ferritic stainless steel, and duplex stainless steel on fatigue crack growth behavior of the gas metal arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm thickness were used as the base material for preparing single ‘V’ butt welded joints. Center cracked tensile specimens were prepared to evaluate fatigue crack growth behavior. Servo hydraulic controlled fatigue testing machine with a capacity of 100 kN was used to evaluate the fatigue crack growth behavior of the welded joints. From this investigation, it was found that the joints fabricated by duplex stainless steel filler metal showed superior fatigue crack growth resistance compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Higher yield strength and relatively higher toughness may be the reasons for superior fatigue performance of the joints fabricated by duplex stainless steel filler metal.

  16. Measuring secondary phases in duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Calliari, I.; Brunelli, K.; Dabalà, M.; Ramous, E.

    2009-01-01

    The use of duplex stainless steels is limited by their susceptibility to the formation of dangerous intermetallic phases resulting in detrimental effects on impact toughness and corrosion resistance. This precipitation and the quantitative determinations of the phases have received considerable attention and different precipitation sequences (σ phase, χ phase, and carbides) have been suggested. This study investigates the phase transformation during continuous cooling and isothermal treatments in commercial duplex stainless steel grades and the effects on alloy properties, and compares the most common techniques of analysis.

  17. 9 Cr-- 1 Mo steel material for high temperature application

    DOEpatents

    Jablonski, Paul D; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-11-27

    One or more embodiments relates to a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The 9 Cr-1 Mo steel has a tempered martensite microstructure and is comprised of both large (0.5-3 .mu.m) primary titanium carbides and small (5-50 nm) secondary titanium carbides in a ratio of. from about 1:1.5 to about 1.5:1. The 9 Cr-1 Mo steel may be fabricated using exemplary austenizing, rapid cooling, and tempering steps without subsequent hot working requirements. The 9 Cr-1 Mo steel exhibits improvements in total mass gain, yield strength, and time-to-rupture over ASTM P91 and ASTM P92 at the temperature and time conditions examined.

  18. Effect of Heat Treatment Technique on the Low Temperature Impact Toughness of Steel EQ70 for Offshore Structure

    NASA Astrophysics Data System (ADS)

    Tao, Su-Fen; Xia, Yun-Jin; Wang, Fu-Ming; Li, Jie; Fan, Ding-Dong

    2017-09-01

    Circle quenching and tempering (CQ&T), intercritical quenching and tempering (IQ&T) and regular quenching and tempering (Q&T) were used to study the influence of heat treatment techniques on the low temperature impact toughness of steel EQ70 for offshore structure. The steels with 2.10 wt. % Ni (steel A) and 1.47 wt. % Ni (steel B) were chosen to analyze the effect of Ni content on the low temperature impact toughness of steel EQ70 for offshore structure. The fracture morphologies were examined by using a scanning electron microscope (SEM, JSM-6480LV), and microstructures etched by 4 vol. % nitric acid were observed on a type 9XB-PC optical microscope. The results show that the impact toughness of steel A is higher than that of steel B at the same test temperature and heat treatment technique. For steel B, the energy absorbed is, in descending order, CQ&T, Q&T and IQ&T, while for steel A, that is CQ&T, IQ&T and Q&T. The effects of heat treatment on the low temperature impact toughness are different for steels A and B, the absorbed energy changes more obviously for steel A. The results can be significant references for actual heat treatment techniques in steel plant.

  19. In Situ Local Measurement of Austenite Mechanical Stability and Transformation Behavior in Third-Generation Advanced High-Strength Steels

    NASA Astrophysics Data System (ADS)

    Abu-Farha, Fadi; Hu, Xiaohua; Sun, Xin; Ren, Yang; Hector, Louis G.; Thomas, Grant; Brown, Tyson W.

    2018-05-01

    Austenite mechanical stability, i.e., retained austenite volume fraction (RAVF) variation with strain, and transformation behavior were investigated for two third-generation advanced high-strength steels (3GAHSS) under quasi-static uniaxial tension: a 1200 grade, two-phase medium Mn (10 wt pct) TRIP steel, and a 980 grade, three-phase TRIP steel produced with a quenching and partitioning heat treatment. The medium Mn (10 wt pct) TRIP steel deforms inhomogeneously via propagative instabilities (Lüders and Portevin Le Châtelier-like bands), while the 980 grade TRIP steel deforms homogenously up to necking. The dramatically different deformation behaviors of these steels required the development of a new in situ experimental technique that couples volumetric synchrotron X-ray diffraction measurement of RAVF with surface strain measurement using stereo digital image correlation over the beam impingement area. Measurement results with the new technique are compared to those from a more conventional approach wherein strains are measured over the entire gage region, while RAVF measurement is the same as that in the new technique. A determination is made as to the appropriateness of the different measurement techniques in measuring the transformation behaviors for steels with homogeneous and inhomogeneous deformation behaviors. Extension of the new in situ technique to the measurement of austenite transformation under different deformation modes and to higher strain rates is discussed.

  20. In Situ Local Measurement of Austenite Mechanical Stability and Transformation Behavior in Third-Generation Advanced High-Strength Steels

    NASA Astrophysics Data System (ADS)

    Abu-Farha, Fadi; Hu, Xiaohua; Sun, Xin; Ren, Yang; Hector, Louis G.; Thomas, Grant; Brown, Tyson W.

    2018-07-01

    Austenite mechanical stability, i.e., retained austenite volume fraction (RAVF) variation with strain, and transformation behavior were investigated for two third-generation advanced high-strength steels (3GAHSS) under quasi-static uniaxial tension: a 1200 grade, two-phase medium Mn (10 wt pct) TRIP steel, and a 980 grade, three-phase TRIP steel produced with a quenching and partitioning heat treatment. The medium Mn (10 wt pct) TRIP steel deforms inhomogeneously via propagative instabilities (Lüders and Portevin Le Châtelier-like bands), while the 980 grade TRIP steel deforms homogenously up to necking. The dramatically different deformation behaviors of these steels required the development of a new in situ experimental technique that couples volumetric synchrotron X-ray diffraction measurement of RAVF with surface strain measurement using stereo digital image correlation over the beam impingement area. Measurement results with the new technique are compared to those from a more conventional approach wherein strains are measured over the entire gage region, while RAVF measurement is the same as that in the new technique. A determination is made as to the appropriateness of the different measurement techniques in measuring the transformation behaviors for steels with homogeneous and inhomogeneous deformation behaviors. Extension of the new in situ technique to the measurement of austenite transformation under different deformation modes and to higher strain rates is discussed.

  1. Induced magnetic moment in stainless steel components of orthodontic appliances in 1.5 T MRI scanners

    PubMed Central

    Rollins, Nancy K.; Liang, Hui; Park, Yong Jong

    2015-01-01

    Purpose: Most orthodontic appliances are made of stainless steel materials and induce severe magnetic susceptibility artifacts in brain MRI. In an effort for correcting these artifacts, it is important to know the value of induced magnetic moments in all parts of orthodontic appliances. In this study, the induced magnetic moment of stainless steel orthodontic brackets, molar bands, and arch-wires from several vendors is measured. Methods: Individual stainless steel brackets, molar bands, and short segments of arch-wire were positioned in the center of spherical flask filled with water through a thin plastic rod. The induced magnetic moment at 1.5 T was determined by fitting the B0 map to the z-component of the magnetic dipole field using a computer routine. Results: The induced magnetic moment at 1.5 T was dominated by the longitudinal component mz, with a small contribution from the transverse components. The mz was insensitive to the orientation of the metal parts. The orthodontic brackets collectively dominated the magnetic dipole moment in orthodontic appliances. In brackets from six vendors, the total induced mz from 20 brackets for nonmolar teeth ranged from 0.108 to 0.158 (median 0.122) A ⋅ m2. The mz in eight molar bands with bracket attachment from two vendors ranged from 0.0004 to 0.0166 (median 0.0035) A ⋅ m2. Several full length arch wires had induced magnetic moment in the range of 0.006–0.025 (median 0.015) A ⋅ m2. Conclusions: Orthodontic brackets collectively contributed most to the total magnetic moment. Different types of brackets, molar bands, and arch wires all exhibit substantial variability in the induced magnetic moment. PMID:26429261

  2. Computer-Aided Grading of Lymphangioleiomyomatosis (LAM) using HRCT

    PubMed Central

    Yao, Jianhua; Avila, Nilo; Dwyer, Andrew; Taveira-DaSilva, Angelo M.; Hathaway, Olanda M.; Moss, Joel

    2010-01-01

    Lymphangioleiomyomatosis (LAM) is a multisystem disorder associated with proliferation of smooth muscle-like cells, which leads to destruction of lung parenchyma. Subjective grading of LAM on HRCT is imprecise and can be arduous especially in cases with severe involvement. We propose a computer-aided evaluation system that grades LAM involvement based on analysis of lung texture patterns. A committee of support vector machines is employed for classification. The system was tested on 36 patients. The computer grade demonstrates good correlation with subjective radiologist grade (R=0.91, p<0.0001) and pulmonary functional tests (R=0.85, p<0.0001). The grade also provides precise progression assessment of disease over time. PMID:21625320

  3. High Temperature Behavior of Cr3C2-NiCr Coatings in the Actual Coal-Fired Boiler Environment

    NASA Astrophysics Data System (ADS)

    Bhatia, Rakesh; Sidhu, Hazoor Singh; Sidhu, Buta Singh

    2015-03-01

    Erosion-corrosion is a serious problem observed in steam-powered electricity generation plants, and industrial waste incinerators. In the present study, four compositions of Cr3C2-(Ni-20Cr) alloy coating powder were deposited by high-velocity oxy-fuel spray technique on T-91 boiler tube steel. The cyclic studies were performed in a coal-fired boiler at 1123 K ± 10 K (850 °C ± 10 °C). X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis and elemental mapping analysis techniques were used to analyze the corrosion products. All the coatings deposited on T-91 boiler tube steel imparted hot corrosion resistance. The 65 pctCr3C2 -35 pct (Ni-20Cr)-coated T-91 steel sample performed better than all other coated samples in the given environment.

  4. Hydrogen enhanced crack growth in 18 Ni maraging steels

    NASA Technical Reports Server (NTRS)

    Hudak, S. J., Jr.; Wei, R. P.

    1976-01-01

    The kinetics of sustained-load subcritical crack growth for 18 Ni maraging steels in high-purity hydrogen are examined using the crack-tip stress intensity factor K as a measure of crack driving force. Crack growth rate as a function of stress intensity exhibited a clearly defined K-independent stage (Stage II). Crack growth rates in an 18 Ni (grade 250) maraging steel are examined for temperatures from -6 to +100 C. A critical temperature was observed above which crack growth rates became diminishingly small. At lower temperatures the activation energy for Stage II crack growth was found to be 16.7 plus or minus 3.3 kJ/mole. Temperature and hydrogen partial pressure are shown to interact in a complex manner to determine the apparent Kth (stress intensity level below which no observable crack growth occurs) and the crack growth behavior. Comparison of results on '250' and '300' grades of 18 Ni maraging steel indicate a significant influence of alloy composition and/or strength level on the crack growth behavior.

  5. CD 10 expression intensity in various grades and stages of urothelial carcinoma of urinary bladder.

    PubMed

    Atique, Muhammad; Abbasi, Muhammad Sajjad; Jamal, Shahid; Khadim, Muhammad Tahir; Akhtar, Farhan; Jamal, Nighat

    2014-05-01

    To evaluate CD10 expression in urothelial carcinoma of the urinary bladder and the association of immunohistochemical (IHC) CD10 expression intensity with grade and stage. Descriptive cross-sectional analytical study. Armed Forces Institute of Pathology, Rawalpindi, from January to December 2011. Fifty consecutive cases of urothelial bladder carcinomas, obtained through transurethral resections, were included in this study. Hematoxylin-eosin (HE) stained sections from each case were re-evaluated histopathologically according to WHO 2004 grading system. The TNM system was used for pathologic staging. On selected slides IHC CD10 marker was applied and a semiquantitative scoring for its expression based on the percentage of positive cells and intensity was performed. Data was entered and analysed on SPSS version 17. Fisher's exact test was used to compare grades, stages of urothelial carcinoma with CD 10 expression and age groups. P < 0.05 was taken as level of significance. Urothelial carcinoma was more common in males. The male to female ratio was 9:1. The older patients > 50 years had higher grade and stage as compared to the younger patients. All cases of high grade urothelial carcinoma showed higher positivity for CD 10. Twenty cases (86.95%) of high grade urothelial carcinoma were positive with +2 immunostaining while 3 cases (13.04 %) were positive with +1 staining. None of the tumors of stage pTa was positive for CD 10 expression. Of all patients with stage pT 1 tumor, 1 case (5.3%) was CD 10 negative and 17 cases (89.9%) were CD 10 positive having +1 staining with 5 - 50% staining and 1 case (5.3%) had +2 staining with more then 50% expression. Out of all patients with stage pT 2, no tumor was CD 10 negative, 3 (13.6%) patients were CD 10 positive with +1 staining and 19 (86.4%) with stage pT 2 tumor had stained positive with +2 staining. CD 10 expression was greater in high grade and invasive urothelial carcinomas; it may be associated with tumor progression

  6. Effect of Shear Strain on the Structure and Properties of Chromium-Nickel Corrosion-Resistant Steels

    NASA Astrophysics Data System (ADS)

    Dobatkin, S. V.; Rybal'chenko, O. V.; Kliauga, A.; Tokar', A. A.

    2015-07-01

    The structure and properties of metastable austenitic steel 08Kh18N10T and stable austenitic steel ASTM F138 under shear deformation implemented by torsion under hydrostatic pressure (THP) at T = 300 and 450°C and by equichannel angular pressing (ECAP) at T = 400°C are studied. The THP yields an ultrafine-grain structure in a fully austenitic matrix with grain size 45 - 70 nm in steel ASTM F138 and 87 - 123 nm in steel 08Kh1810T. The ECAP at 400°C yields a grain-subgrain structure with structural elements 100 - 300 nm in size in steel 08Kh18N10T and 200 - 400 nm in size in steel ASTM F138.

  7. Validating the Early Childhood Classroom Observation Measure in First and Third Grade Classrooms

    ERIC Educational Resources Information Center

    Tang, Xin; Pakarinen, Eija; Lerkkanen, Marja-Kristiina; Kikas, Eve; Muotka, Joona; Nurmi, Jari-Erik

    2017-01-01

    The present study reports on the psychometric properties of the Early Childhood Classroom Observation Measure (ECCOM) in Finnish and Estonian first and third grade classrooms. The observation data were collected from 91 first grade teachers and 70 third grade teachers. Teachers' curriculum goals, teaching experience and the classroom size were…

  8. Improving the machinability of leaded free cutting steel through process optimization

    NASA Astrophysics Data System (ADS)

    Sathyamurthy, P.; Vetrivelmurugan, R.; Sooryaprakash, J.

    2018-02-01

    Free cutting steel grades are high sulphur grades which can be classified under two categories as Leaded and Non-Leaded. These grades are used for manufacturing components like Nuts, bolts, studs, hydraulic fittings, brake pistons where higher machining is required to get intricate shape. Machinability of these grades are affected by hard oxide inclusions and highly deformed manganese sulphide inclusions. At JSW, machinability of leaded free cutting steel is improved by various process modifications namely deoxidation through carbon and manganese, Tellurium (Rare earth element) addition and maintaining the oxygen level at 80- 120ppm. Former one avoids the formation of hard SiO2 and Al2O3 compounds, Tellurium addition forms PbTe compound at the tail of MnS inclusions which resists the deformation of MnS inclusions and increased oxygen level favours the formation of less deformable oxy- sulphide inclusions. Above process modifications have resulted in achieving the low silicate content, better aspect ratio of MnS inclusions in the final rolled product. They are assessed by the characteristics of chip formation and surface roughness of machined part.

  9. 14 CFR 91.615-91.699 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Additional Equipment and Operating Requirements for Large and Transport Category Aircraft §§ 91.615-91.699 [Reserved] ...

  10. Solidification Sequence of Spray-Formed Steels

    NASA Astrophysics Data System (ADS)

    Zepon, Guilherme; Ellendt, Nils; Uhlenwinkel, Volker; Bolfarini, Claudemiro

    2016-02-01

    Solidification in spray-forming is still an open discussion in the atomization and deposition area. This paper proposes a solidification model based on the equilibrium solidification path of alloys. The main assumptions of the model are that the deposition zone temperature must be above the alloy's solidus temperature and that the equilibrium liquid fraction at this temperature is reached, which involves partial remelting and/or redissolution of completely solidified droplets. When the deposition zone is cooled, solidification of the remaining liquid takes place under near equilibrium conditions. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to analyze the microstructures of two different spray-formed steel grades: (1) boron modified supermartensitic stainless steel (SMSS) and (2) D2 tool steel. The microstructures were analyzed to determine the sequence of phase formation during solidification. In both cases, the solidification model proposed was validated.

  11. 49 CFR 192.105 - Design formula for steel pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Design formula for steel pipe. 192.105 Section 192... for steel pipe. (a) The design pressure for steel pipe is determined in accordance with the following... § 192.113. T=Temperature derating factor determined in accordance with § 192.115. (b) If steel pipe that...

  12. 49 CFR 192.105 - Design formula for steel pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Design formula for steel pipe. 192.105 Section 192... for steel pipe. (a) The design pressure for steel pipe is determined in accordance with the following... § 192.113. T=Temperature derating factor determined in accordance with § 192.115. (b) If steel pipe that...

  13. 49 CFR 192.105 - Design formula for steel pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Design formula for steel pipe. 192.105 Section 192... for steel pipe. (a) The design pressure for steel pipe is determined in accordance with the following... § 192.113. T=Temperature derating factor determined in accordance with § 192.115. (b) If steel pipe that...

  14. 49 CFR 192.105 - Design formula for steel pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Design formula for steel pipe. 192.105 Section 192... for steel pipe. (a) The design pressure for steel pipe is determined in accordance with the following... § 192.113. T=Temperature derating factor determined in accordance with § 192.115. (b) If steel pipe that...

  15. 49 CFR 192.105 - Design formula for steel pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Design formula for steel pipe. 192.105 Section 192... for steel pipe. (a) The design pressure for steel pipe is determined in accordance with the following... § 192.113. T=Temperature derating factor determined in accordance with § 192.115. (b) If steel pipe that...

  16. Evaluation of steel slag coarse aggregate in hot mix asphalt concrete.

    PubMed

    Ahmedzade, Perviz; Sengoz, Burak

    2009-06-15

    This paper presents the influences of the utilization of steel slag as a coarse aggregate on the properties of hot mix asphalt. Four different asphalt mixtures containing two types of asphalt cement (AC-5; AC-10) and coarse aggregate (limestone; steel slag) were used to prepare Marshall specimens and to determine optimum bitumen content. Mechanical characteristics of all mixtures were evaluated by Marshall stability, indirect tensile stiffness modulus, creep stiffness, and indirect tensile strength tests. The electrical sensitivity of the specimens were also investigated in accordance with ASTM D257-91. It was observed that steel slag used as a coarse aggregate improved the mechanical properties of asphalt mixtures. Moreover, volume resistivity values demonstrated that the electrical conductivity of steel slag mixtures were better than that of limestone mixtures.

  17. Enhanced Inactivation of Salmonella and Pseudomonas Biofilms on Stainless Steel by Use of T-128, a Fresh-Produce Washing Aid, in Chlorinated Wash Solutions

    PubMed Central

    Shen, Cangliang; Luo, Yaguang; Nou, Xiangwu; Bauchan, Gary; Zhou, Bin; Wang, Qin

    2012-01-01

    The effect of the washing aid T-128 (generally recognized as safe [GRAS] formulation, composed mainly of phosphoric acid and propylene glycol) on inactivation of Salmonella and Pseudomonas populations in biofilms on stainless steel was evaluated under conditions of increasing organic matter loads in chlorinated wash solutions dominated by hypochlorous acid. Biofilms were formed statically on stainless steel coupons suspended in 2% lettuce extract after inoculation with Salmonella enterica serovar Thompson or Newport or with Pseudomonas fluorescens. Coupons with biofilms were washed in chlorine solutions (0, 0.5, 1, 2, 5, 10, or 20 mg/liter at pH 6.5, 5.0 and 2.9), with or without T-128, and with increasing loads of organic matter (0, 0.25, 0.5, 0.75, or 1.0% lettuce extract). Cell populations on coupons were dispersed using intermittent, pulsed ultrasonication and vortexing and enumerated by colony counts on XLT-4 or Pseudomonas agars. Cell responses to fluorescent viability staining of biofilm treatment washing solutions were examined using confocal laser scanning microscopy. Results showed that 0.1% T-128 (without chlorine) reduced P. fluorescens biofilm populations by 2.5 log10 units but did not reduce Salmonella populations. For both Salmonella and Pseudomonas, the sanitizing effect of free chlorine (1.0 to 5.0 mg/liter) was enhanced (P < 0.05) when it was combined with T-128. Application of T-128 decreased the free chlorine depletion rate caused by increasing organic matter in wash waters and significantly (P < 0.05) augmented inactivation of bacteria in biofilms compared to treatments without T-128. Image analysis of surfaces stained with SYTO and propidium iodide corroborate the cultural assay results showing that T-128 can aid in reducing pathogen viability in biofilms and thus can aid in sanitizing stainless steel contact surfaces during processing of fresh-cut produce. PMID:22752180

  18. The Mechanism of High Ductility for Novel High-Carbon Quenching-Partitioning-Tempering Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Qin, Shengwei; Liu, Yu; Hao, Qingguo; Wang, Ying; Chen, Nailu; Zuo, Xunwei; Rong, Yonghua

    2015-09-01

    In this article, a novel quenching-partitioning-tempering (Q-P-T) process was applied to treat Fe-0.6C-1.5Mn-1.5Si-0.6Cr-0.05Nb hot-rolled high-carbon steel and the microstructures including retained austenite fraction and the average dislocation densities in both martensite and retained austenite were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, respectively. The Q-P-T steel exhibits high strength (1950 MPa) and elongation (12.4 pct). Comparing with the steel treated by traditional quenching and tempering (Q&T) process, the mechanism of high ductility for high-carbon Q-P-T steel is revealed as follows. Much more retained austenite existing in Q-P-T steel than in Q&T one remarkably enhances the ductility by the following two effects: the dislocation absorption by retained austenite effect and the transformation-induced plasticity effect. Besides, lower dislocation density in martensite matrix produced by Q-P-T process plays an important role in the improvement of ductility. However, some thin plates of twin-type martensite embedded in dislocation-type martensite matrix in high-carbon Q-P-T steel affect the further improvement of ductility.

  19. Seventh Grade Students' Conceptions of Global Warming and Climate Change

    ERIC Educational Resources Information Center

    Shepardson, Daniel P.; Niyogi, Dev; Choi, Soyoung; Charusombat, Umarporn

    2009-01-01

    The purpose of this study was to investigate seventh grade students' conceptions of global warming and climate change. The study was descriptive in nature and involved the collection of qualitative data from 91 seventh grade students from three different schools in the Midwest, USA. An open response and draw and explain assessment instrument was…

  20. Surface modification of steels and magnesium alloy by high current pulsed electron beam

    NASA Astrophysics Data System (ADS)

    Hao, Shengzhi; Gao, Bo; Wu, Aimin; Zou, Jianxin; Qin, Ying; Dong, Chuang; An, Jian; Guan, Qingfeng

    2005-11-01

    High current pulsed electron beam (HCPEB) is now developing as a useful tool for surface modification of materials. When concentrated electron flux transferring its energy into a very thin surface layer within a short pulse time, superfast processes such as heating, melting, evaporation and consequent solidification, as well as dynamic stress induced may impart the surface layer with improved physico-chemical and mechanical properties. This paper presents our research work on surface modification of steels and magnesium alloy with HCPEB of working parameters as electron energy 27 keV, pulse duration ∼1 μs and energy density ∼2.2 J/cm2 per pulse. Investigations performed on carbon steel T8, mold steel D2 and magnesium alloy AZ91HP have shown that the most pronounced changes of phase-structure state and properties occurring in the near-surface layers, while the thickness of the modified layer with improved microhardness (several hundreds of micrometers) is significantly greater than that of the heat-affected zone. The formation mechanisms of surface cratering and non-stationary hardening effect in depth are discussed based on the elucidation of non-equilibrium temperature filed and different kinds of stresses formed during pulsed electron beam melting treatment. After the pulsed electron beam treatments, samples show significant improvements in measurements of wear and corrosion resistance.

  1. Foreign Object Damage Behavior of Two Gas-turbine Grade Silicon Nitrides by Steel Ball Projectiles at Ambient Temperature

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Pereira, J. Michael; Janosik, Lesley A.; Bhatt, Ramakrishna T.

    2002-01-01

    Foreign object damage (FOD) behavior of two commercial gas-turbine grade silicon nitrides, AS800 and SN282, was determined at ambient temperature through strength testing of flexure test specimens impacted by steel-ball projectiles with a diameter of 1.59 mm in a velocity range from 220 to 440 m/s. AS800 silicon nitride exhibited a greater FOD resistance than SN282, primarily due to its greater value of fracture toughness (K(sub IC)). Additionally, the FOD response of an equiaxed, fine-grained silicon nitride (NC132) was also investigated to provide further insight. The NC132 silicon nitride exhibited the lowest fracture toughness of the three materials tested, providing further evidence that K(sub IC) is a key material parameter affecting FOD resistance. The observed damage generated by projectile impact was typically in the forms of well- or ill-developed ring or cone cracks with little presence of radial cracks.

  2. Diagnostic accuracy of dynamic contrast-enhanced MR imaging using a phase-derived vascular input function in the preoperative grading of gliomas.

    PubMed

    Nguyen, T B; Cron, G O; Mercier, J F; Foottit, C; Torres, C H; Chakraborty, S; Woulfe, J; Jansen, G H; Caudrelier, J M; Sinclair, J; Hogan, M J; Thornhill, R E; Cameron, I G

    2012-09-01

    The accuracy of tumor plasma volume and K(trans) estimates obtained with DCE MR imaging may have inaccuracies introduced by a poor estimation of the VIF. In this study, we evaluated the diagnostic accuracy of a novel technique by using a phase-derived VIF and "bookend" T1 measurements in the preoperative grading of patients with suspected gliomas. This prospective study included 46 patients with a new pathologically confirmed diagnosis of glioma. Both magnitude and phase images were acquired during DCE MR imaging for estimates of K(trans)_φ and V(p_)φ (calculated from a phase-derived VIF and bookend T1 measurements) as well as K(trans)_SI and V(p_)SI (calculated from a magnitude-derived VIF without T1 measurements). Median K(trans)_φ values were 0.0041 minutes(-1) (95 CI, 0.00062-0.033), 0.031 minutes(-1) (0.011-0.150), and 0.088 minutes(-1) (0.069-0.110) for grade II, III, and IV gliomas, respectively (P ≤ .05 for each). Median V(p_)φ values were 0.64 mL/100 g (0.06-1.40), 0.98 mL/100 g (0.34-2.20), and 2.16 mL/100 g (1.8-3.1) with P = .15 between grade II and III gliomas and P = .015 between grade III and IV gliomas. In differentiating low-grade from high-grade gliomas, AUCs for K(trans)_φ, V(p_φ), K(trans)_SI, and V(p_)SI were 0.87 (0.73-1), 0.84 (0.69-0.98), 0.81 (0.59-1), and 0.84 (0.66-0.91). The differences between the AUCs were not statistically significant. K(trans)_φ and V(p_)φ are parameters that can help in differentiating low-grade from high-grade gliomas.

  3. An Experimental Investigation on Hardness and Microstructure of Heat Treated EN 9 Steel

    NASA Astrophysics Data System (ADS)

    Biswas, Palash; Kundu, Arnab; Mondal, Dhiraj

    2017-08-01

    In the modern engineering world, extensive research has led to the development of some special grades of steel, often suited for enhanced functions. EN 9 steel is one such grade, having major applications in power plants, automobile and aerospace industry. Different heat treatment processes are employed to achieve high hardness and high wear resistance, but machinability subsequently decreases. Existing literature is not sufficient to achieve a balance between hardness and machinability. The aim of this experimental work is to determine the hardness values and observe microstructural changes in EN9 steel, when it is subjected to annealing, normalizing and quenching. Finally, the effects of tempering after each of these heat treatments on hardness and microstructure have also been shown. It is seen that the tempering after normalizing the specimen achieved satisfactory results. The microstructure was also observed to be consisting of fine grains.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hatano, Y.; Abe, S.; Matsuyama, M.

    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. Significantmore » 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.« less

  5. Transformation of localized necking of strain space into stress space for advanced high strength steel sheet

    NASA Astrophysics Data System (ADS)

    Nakwattanaset, Aeksuwat; Suranuntchai, Surasak

    2018-03-01

    Normally, Forming Limit Curves (FLCs) can’t explain for shear fracture better than Damage Curve, this article aims to show the experimental of Forming Limit Curve (FLC) for Advanced High Strength Steel (AHSS) sheets grade JAC780Y with the Nakazima forming test and tensile tests of different sample geometries. From these results, the Forming Limit Curve (strain space) was transformed to damage curve (stress space) between plastic strain and stress triaxiality. Therefore, Stress space transformed using by Hill-48 and von-Mises yield function. This article shows that two of these yield criterions can use in the transformation.

  6. Angiographic flow grading and graft arrangement of arterial conduits.

    PubMed

    Nakajima, Hiroyuki; Kobayashi, Junjiro; Tagusari, Osamu; Niwaya, Kazuo; Funatsu, Toshihiro; Kawamura, Atsushi; Yagihara, Toshikatsu; Kitamura, Soichiro

    2006-11-01

    We sought to delineate the effects of competitive and reverse flow on the intermediate-term patency of arterial conduits and examined graft arrangements for maximizing antegrade bypass flow. The angiograms of 2083 bypass grafts in 570 patients who underwent off-pump total arterial revascularization without aortic manipulation since December 2000 were reviewed. The blood flow in the bypass grafts were graded A (antegrade), B (competitive), C (reverse), or O (occlusion). The mean number of distal anastomoses was 3.65 +/- 0.94 per patient. In the early angiography 91.3% (1901/2083) of the bypasses were grade A. Thirty (1.4%) bypasses were grade O, whereas 2.9% (61/2083) were grade B, and 4.4%(91/2083) were grade C. In the multivariate analysis the end-to-side anastomosis (P < .0001), 4 or more distal anastomoses of the conduit (P = .01), native coronary stenosis of less than 75% (P < .0001), and target branch location of the right coronary artery territory (P < .0001) and left circumflex artery territory (P = .02) significantly correlated with grade non-A. The patency rate in the late angiography of the bypasses graded B or C in the early angiography was 7 (28.0%) of 25, whereas that of the bypasses graded A was 164 (89.1%) of 184 (P < .0001). The actuarial graft patency rate of the bypasses graded A was 72.3% at 3 years and was significantly higher than that of the bypasses graded B or C (28.6% at 3 years after surgical intervention, P < .0001). The sufficient antegrade bypass flow had a favorable effect on the graft patency of arterial conduits. The graft arrangement should be adjusted for each patient so as to maximize the antegrade bypass flow and to confirm the advantage of arterial grafts.

  7. A possible recycling method for high grade steels EAFD in polymer composites.

    PubMed

    Niubó, M; Fernández, A I; Chimenos, J M; Haurie, L

    2009-11-15

    This work evaluates the feasibility of incorporating electric arc furnace dust (EAFD), as filler in a polymer matrix, to obtain a moldable heavyweight sheet, useful for acoustic insulation in automotive industry. For this purpose EAFD from a steel factory that manufactures high quality steels, was characterized and different formulations of composites were prepared. Physical and mechanical properties, as well as fire behaviour were tested and compared with a polymer composite compounded with common mineral fillers. Optimum formulation with 25% EAFD fulfils the RoHs Directive used by automotive industry to regulate heavy metals content. Leaching test was also performed on prepared composites to classify the material after use.

  8. Reaction of Unalloyed and Cr-Mo Alloyed Steels with Nitrogen from the Sintering Atmosphere

    NASA Astrophysics Data System (ADS)

    Dlapka, Magdalena; Gierl-Mayer, Christian; Calderon, Raquel de Oro; Danninger, Herbert; Bengtsson, Sven; Dudrova, Eva

    2016-12-01

    Nitrogen is usually regarded as an inert sintering atmosphere for PM steels; however, this cannot be taken for granted in particular for steels alloyed with nitride forming elements. Among those elements, chromium has become more and more important as an alloying element in sintered low alloy structural steels in the last decade due to the moderate alloying cost and the excellent mechanical properties obtainable, in particular when sinter hardening is applied. The high affinity of Cr to oxygen and the possible ways to overcome related problems have been the subject of numerous studies, while the fact that chromium is also a fairly strong nitride forming element has largely been neglected at least for low alloy steel grades, although frequently used materials like steels from Cr and Cr-Mo prealloyed powders are commonly sintered in atmospheres consisting mainly of nitrogen. In the present study, nitrogen pickup during sintering at different temperatures and for varying times has been studied for Cr-Mo prealloyed steel grades as well as for unalloyed carbon steel. Also the effect of the cooling rate and its influence on the properties, of the microstructure and the composition have been investigated. It showed that the main nitrogen uptake occurs not during isothermal sintering but rather during cooling. It could be demonstrated that a critical temperature range exists within which the investigated CrM-based steel is particularly sensitive to nitrogen pickup.

  9. Method to Predict Tempering of Steels Under Non-isothermal Conditions

    NASA Astrophysics Data System (ADS)

    Poirier, D. R.; Kohli, A.

    2017-05-01

    A common way of representing the tempering responses of steels is with a "tempering parameter" that includes the effect of temperature and time on hardness after hardening. Such functions, usually in graphical form, are available for many steels and have been applied for isothermal tempering. In this article, we demonstrate that the method can be extended to non-isothermal conditions. Controlled heating experiments were done on three grades in order to verify the method.

  10. Effect of Ethanol Chemistry on SCC of Carbon Steel

    DOT National Transportation Integrated Search

    2011-02-22

    Pipeline companies have a keen interest in assessing the feasibility of transporting fuel grade ethanol (FGE) and ethanol blends in existing pipelines. Previous field experience and laboratory research, funded by PRCI and API, has shown that steel ca...

  11. The Effect of Different Non-Metallic Inclusions on the Machinability of Steels

    PubMed Central

    Ånmark, Niclas; Karasev, Andrey; Jönsson, Pär Göran

    2015-01-01

    Considerable research has been conducted over recent decades on the role of non-metallic inclusions and their link to the machinability of different steels. The present work reviews the mechanisms of steel fractures during different mechanical machining operations and the behavior of various non-metallic inclusions in a cutting zone. More specifically, the effects of composition, size, number and morphology of inclusions on machinability factors (such as cutting tool wear, power consumption, etc.) are discussed and summarized. Finally, some methods for modification of non-metallic inclusions in the liquid steel are considered to obtain a desired balance between mechanical properties and machinability of various steel grades. PMID:28787969

  12. The Effect of Different Non-Metallic Inclusions on the Machinability of Steels.

    PubMed

    Ånmark, Niclas; Karasev, Andrey; Jönsson, Pär Göran

    2015-02-16

    Considerable research has been conducted over recent decades on the role of non‑metallic inclusions and their link to the machinability of different steels. The present work reviews the mechanisms of steel fractures during different mechanical machining operations and the behavior of various non-metallic inclusions in a cutting zone. More specifically, the effects of composition, size, number and morphology of inclusions on machinability factors (such as cutting tool wear, power consumption, etc .) are discussed and summarized. Finally, some methods for modification of non-metallic inclusions in the liquid steel are considered to obtain a desired balance between mechanical properties and machinability of various steel grades.

  13. Evaluation of grades 3 and 4 chondromalacia of the knee using T2*-weighted 3D gradient-echo articular cartilage imaging.

    PubMed

    Murphy, B J

    2001-06-01

    To determine the accuracy of T2*-weighted three-dimensional (3D) gradient-echo articular cartilage imaging in the identification of grades 3 and 4 chondromalacia of the knee. A retrospective evaluation of 80 patients who underwent both arthroscopic and MRI evaluation was performed. The 3D images were interpreted by one observer without knowledge of the surgical results. The medial and lateral femoral condyles, the medial and lateral tibial plateau, the patellar cartilage and trochlear groove were evaluated. MR cartilage images were considered positive if focal reduction of cartilage thickness was present (grade 3 chondromalacia) or if complete loss of cartilage was present (grade 4 chondromalacia). Comparison of the 3D MR results with the arthroscopic findings was performed. Eighty patients were included in the study group. A total of 480 articular cartilage sites were evaluated with MRI and arthroscopy. Results of MR identification of grades 3 and 4 chondromalacia, all sites combined, were: sensitivity 83%, specificity 97%, false negative rate 17%, false positive rate 3%, positive predictive value 87%, negative predictive value 95%, overall accuracy 93%. The results demonstrate that T2*-weighted 3D gradient-echo articular cartilage imaging can identify grades 3 and 4 chondromalacia of the knee.

  14. A Comparison of Mechanical Properties and Hydrogen Embrittlement Resistance of Austempered vs Quenched and Tempered 4340 Steel

    NASA Astrophysics Data System (ADS)

    Tartaglia, John M.; Lazzari, Kristen A.; Hui, Grace P.; Hayrynen, Kathy L.

    2008-03-01

    This study was conducted to compare the hydrogen embrittlement (HE) resistance of austempered 4340 steel with quenched and tempered (Q&T) 4340 steel with an identical yield strength (YS) of 1340 MPa (194 ksi). A baseline comparison showed that the austempered steel with a lower bainite microstructure exhibited higher hardness, tensile strengths, Charpy V-notch (CVN) impact toughness, and ductility at both low 233 K (-40 F) and ambient temperatures, as compared to the Q&T steel with a martensite microstructure. After machining and just prior to testing, subsized CVN specimens and notched bend specimens were immersed in hydrochloric acid-water baths. The HE resistance was higher for the austempered steel than the Q&T steel. No differences in room-temperature CVN energy resulted from hydrogen charging of the austempered and Q&T steels vs their unexposed counterparts. However, in the notched bend specimens, the hydrogen charging caused significant peak load decreases (40 pct) for the Q&T steel, while the austempered steel exhibited only small (6 pct) decreases in peak load. Intergranular (IG) fracture occurred solely in the charged Q&T bend samples, which is further evidence of their embrittlement.

  15. Hydrogen Embrittlement of Automotive Advanced High-Strength Steels

    NASA Astrophysics Data System (ADS)

    Lovicu, Gianfranco; Bottazzi, Mauro; D'Aiuto, Fabio; De Sanctis, Massimo; Dimatteo, Antonella; Santus, Ciro; Valentini, Renzo

    2012-11-01

    Advanced high-strength steels (AHSS) have a better combination between strength and ductility than conventional HSS, and higher crash resistances are obtained in concomitance with weight reduction of car structural components. These steels have been developed in the last few decades, and their use is rapidly increasing. Notwithstanding, some of their important features have to be still understood and studied in order to completely characterize their service behavior. In particular, the high mechanical resistance of AHSS makes hydrogen-related problems a great concern for this steel grade. This article investigates the hydrogen embrittlement (HE) of four AHSS steels. The behavior of one transformation induced plasticity (TRIP), two martensitic with different strength levels, and one hot-stamping steels has been studied using slow strain rate tensile (SSRT) tests on electrochemically hydrogenated notched samples. The embrittlement susceptibility of these AHSS steels has been correlated mainly to their strength level and to their microstructural features. Finally, the hydrogen critical concentrations for HE, established by SSRT tests, have been compared to hydrogen contents absorbed during the painting process of a body in white (BIW) structure, experimentally determined during a real cycle in an industrial plant.

  16. Rolling Bearing Steels - A Technical and Historical Perspective

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    2012-01-01

    Starting about 1920 it becomes easier to track the growth of bearing materials technology. Until 1955, with few exceptions, comparatively little progress was made in this area. AISI 52100 and some carburizing grades (AISI 4320, AISI 9310) were adequate for most applications. The catalyst to quantum advances in high-performance rolling-element bearing steels was the advent of the aircraft gas turbine engine. With improved bearing manufacturing and steel processing together with advanced lubrication technology, the potential improvements in bearing life can be as much as 80 times that attainable in the late 1950s or as much as 400 times that attainable in 1940. This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability. The single most important variable that has significantly increased bearing life and reliability is vacuum processing of bearing steel. Differences between through hardened, case carburized and corrosion resistant steels are discussed. The interrelation of alloy elements and carbides and their effect on bearing life are presented. An equation relating bearing life, steel hardness and temperature is given. Life factors for various steels are suggested and discussed. A relation between compressive residual stress and bearing life is presented. The effects of retained austenite and grain size are discussed.

  17. Influence of nitrogen as grain refiner in low carbon and microalloyed steels

    NASA Astrophysics Data System (ADS)

    Hasan, B. M.; Sathyamurthy, P.

    2018-02-01

    Microalloyed steel is replacing using of low alloy steel in automotive industry. Microalloying elements like vanadium, niobium and titanium are used to enhance the steel property. The current work is focused on using nitrogen as a strengthening element in existing steel grade. Nitrogen in free form acts as solid solution strengthener and in combined form as precipitates acts as grain refiner for enhancing strength. The problem of grain coarsening at high temperature in case carburizing steel was avoided by increasing nitrogen level from 60ppm to 200ppm. Grain size of ASTM no 10 is obtained at carburizing temperature of 950 °C by increasing nitrogen content from grain size no 6 with lower nitrogen. Mostly crankshaft is made from Cr-Mo alloyed steel. At JSW, nitrogen in the level of 130-200ppm is added to medium carbon steel to meet property requirement for crankshaft application

  18. Effect of post weld heat treatment on the microstructure and mechanical properties of ITER-grade 316LN austenitic stainless steel weldments

    NASA Astrophysics Data System (ADS)

    Xin, Jijun; Fang, Chao; Song, Yuntao; Wei, Jing; Xu, Shen; Wu, Jiefeng

    2017-04-01

    The effect of postweld heat treatment (PWHT) on the microstructure and mechanical properties of ITER-grade 316LN austenitic stainless steel joints with ER316LMn filler material was investigated. PWHT aging was performed for 1 h at four different temperatures of 600 °C, 760 °C, 870 °C and 920 °C, respectively. The microstructure revealed the sigma phase precipitation occurred in the weld metals heat-treated at the temperature of 870 °C and 920 °C. The PWHT temperatures have the less effect on the tensile strength, and the maximum tensile strength of the joints is about 630 MPa, reaching the 95% of the base metal, whereas the elongation is enhanced with the rise of PWHT temperatures. Meanwhile, the sigma phase precipitation in the weld metals reduces the impact toughness.

  19. A mortality study among mild steel and stainless steel welders.

    PubMed Central

    Moulin, J J; Wild, P; Haguenoer, J M; Faucon, D; De Gaudemaris, R; Mur, J M; Mereau, M; Gary, Y; Toamain, J P; Birembaut, Y

    1993-01-01

    A mortality study was carried out in conjunction with the European mortality study among welders coordinated by the International Agency for Research on Cancer (IARC). The study was aimed at assessing risks for lung cancer in relation to exposure to asbestos, welding fumes containing chromium and nickel, and tobacco smoke. The study included a cohort of 2721 welders and an internal comparison group of 6683 manual workers employed in 13 factories in France. The mortality of the two cohorts was studied from 1975 to 1988 by the historical prospective method. Job histories of welders were traced including welding processes used, metals welded, and proportion of worktime spent in welding. Data on smoking habits were collected from medical records. The observed number of deaths were compared with those expected (standardised mortality ratio (SMR)) based on national rates with adjustments for age, sex, and calendar time. The smoking habits of 87% of the whole study population were known. The distribution of welders and controls according to smoking was not statistically different. The overall mortality was slightly higher for welders (SMR = 1.02, 95% confidence interval (95% CI) 0.89-1.18) than for controls (SMR = 0.91, 95% CI 0.84-0.99). For lung cancer, the SMR was 1.24 (95% CI 0.75-1.94) for welders, whereas the corresponding value was lower for controls (SMR = 0.94, 95% CI 0.68-1.26). The SMR for lung cancer was 1.59 among non-shipyard mild steel welders (95% CI 0.73-3.02). This contrasted with the results for all stainless steel welders (SMR = 0.92, 95% CI 0.19-2.69), and for stainless steel welders predominantly exposed to chromium VI (SMR = 1.03, 95% CI 0.12-3.71). Moreover, SMRs for lung cancer for mild steel welders tended to increase with duration of exposure and time since first exposure, leading to significant excesses for duration > or = 20 years and latency > or = 20 years. Such a pattern was not found for stainless steel welders. PMID:8457490

  20. Presence of Antigen-Experienced T Cells with Low Grade of Differentiation and Proliferative Potential in Chronic Chagas Disease Myocarditis

    PubMed Central

    Cabeza-Meckert, Patricia; Viotti, Rodolfo; Garelli, Fernando; Favaloro, Liliana E.; Favaloro, Roberto R.; Laguens, Rubén; Laucella, Susana A.

    2014-01-01

    Background The main consequence of chronic Trypanosoma cruzi infection is the development of myocarditis in approximately 20–30% of infected individuals but not until 10–20 years after the initial infection. We have previously shown that circulating interferon-γ-secreting T cells responsive to Trypanosoma cruzi antigens in chronic Chagas disease patients display a low grade of differentiation and the frequency of these T lymphocytes decreases along with the severity of heart disease. This study thought to explore the expression of inhibitory receptors, transcription factors of type 1 or regulatory T cells, and markers of T cell differentiation, immunosenescence or active cell cycle in cardiac explants from patients with advanced Chagas disease myocarditis. Methodology/Principal Findings The expression of different markers for T and B cells as well as for macrophages was evaluated by immunohistochemistry and immunofluorescence techniques in cardiac explants from patients with advanced chronic Chagas disease submitted to heart transplantation. Most infiltrating cells displayed markers of antigen-experienced T cells (CD3+, CD4+, CD8+, CD45RO+) with a low grade of differentiation (CD27+, CD57−, CD45RA−, PD-1−). A skewed T helper1/T cytotoxic 1 profile was supported by the expression of T-bet; whereas FOXP3+ cells were scarce and located only in areas of severe myocarditis. In addition, a significant proliferative capacity of CD3+ T cells, assessed by Ki67 staining, was found. Conclusions/Significance The quality of T cell responses and immunoregulatory mechanisms might determine the pattern of the cellular response and the severity of disease in chronic Trypanosoma cruzi infection. PMID:25144227

  1. Localized CO2 corrosion of carbon steel with different microstructures in brine solutions with an imidazoline-based inhibitor

    NASA Astrophysics Data System (ADS)

    Zhang, Huan-huan; Pang, Xiaolu; Gao, Kewei

    2018-06-01

    CO2 corrosion behavior of carbon steel with different microstructures (H steel: coarse laminar pearlite; T steel: globular and shot rod shaped pearlite) was analyzed in 3 wt.% NaCl solution at 60 °C with imidazoline-based inhibitor by electrochemical and weight loss methods. Electrochemical measurements showed that, compared to H steel, the inhibitor film adsorbed on T steel had a higher pitting corrosion resistance and the inhibition efficiency for T steel was larger at each concentration of inhibitor. Weight loss results exhibited that both steels suffered general corrosion in absence of inhibitor; however, localized corrosion was observed on the samples with insufficient concentration of inhibitor. H steel suffered more severe localized corrosion than T steel, it was related to that H steel had a higher density of dislocations in the pearlite area and the larger driving force for galvanic corrosion. The localized corrosion on H steel mainly distributed on the laminar pearlite area.

  2. Stress Corrosion Cracking of Ferritic Materials for Fossil Power Generation Applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pawel, Steven J; Siefert, John A.

    2014-01-01

    Creep strength enhanced ferritic (CSEF) steels Grades 23, 24, 91, and 92 have been widely implemented in the fossil fired industry for over two decades. The stress corrosion cracking (SCC) behavior of these materials with respect to mainstay Cr-Mo steels (such as Grades 11, 12 and 22) has not been properly assessed, particularly in consideration of recent reported issues of SCC in CSEF steels. This report details the results of Jones test exposures of a wide range of materials (Grades 11, 22, 23, 24, and 92), material conditions (as-received, improper heat treatments, normalized, weldments) and environments (salt fog; tube cleaningmore » environments including decreasing, scale removal, and passivation; and high temperature water) to compare the susceptibility to cracking of these steels. In the as-received (normalized and tempered) condition, none of these materials are susceptible to SCC in the environments examined. However, in the hardened condition, certain combinations of environment and alloy reveal substantial SCC susceptibility.« less

  3. Prospective In Vivo Comparison of Damaged and Healthy-Appearing Articular Cartilage Specimens in Patients With Femoroacetabular Impingement: Comparison of T2 Mapping, Histologic Endpoints, and Arthroscopic Grading.

    PubMed

    Ho, Charles P; Surowiec, Rachel K; Frisbie, David D; Ferro, Fernando P; Wilson, Katharine J; Saroki, Adriana J; Fitzcharles, Eric K; Dornan, Grant J; Philippon, Marc J

    2016-08-01

    To describe T2 mapping values in arthroscopically determined International Cartilage Repair Society (ICRS) grades in damaged and healthy-appearing articular cartilage waste specimens from arthroscopic femoroacetabular impingement (FAI) treatment. Furthermore, we sought to compare ICRS grades of the specimens with biochemical, immunohistochemistry and histologic endpoints and assess correlations with T2 mapping. Twenty-four patients were prospectively enrolled, consecutively, between December 2011 and August 2012. Patients were included if they were aged 18 years or older and met criteria that followed the clinical indications for arthroscopy to treat FAI. Patients with prior hip trauma including fracture or dislocation or who have undergone prior hip surgery were excluded. All patients received a preoperative sagittal T2 mapping scan of the hip joint. Cartilage was graded intraoperatively using the ICRS grading system, and graded specimens were collected as cartilage waste for histologic, biochemical, and immunohistochemistry analysis. Forty-four cartilage specimens (22 healthy-appearing, 22 damaged) were analyzed. Median T2 values were significantly higher among damaged specimens (55.7 ± 14.9 ms) than healthy-appearing specimens (49.3 ± 12.3 ms; P = .043), which was most exaggerated among mild (grade 1 or 2) defects where the damaged specimens (58.1 ± 16.4 ms) were significantly higher than their paired healthy-appearing specimens (48.7 ± 15.4 ms; P = .026). Severely damaged specimens (grade 3 or 4) had significantly lower cumulative H&E than their paired healthy-appearing counterparts (P = .02) but was not statistically significant among damaged specimens with mild (grade 1 or 2) defects (P = .198). Among healthy-appearing specimens, median T2 and the percentage of collagen fibers oriented parallel were significantly correlated (rho = 0.425, P = .048). This study outlines the potential for T2 mapping to identify early cartilage degeneration in

  4. Delta One T Cells for Immunotherapy of Chronic Lymphocytic Leukemia: Clinical-Grade Expansion/Differentiation and Preclinical Proof of Concept.

    PubMed

    Almeida, Afonso R; Correia, Daniel V; Fernandes-Platzgummer, Ana; da Silva, Cláudia L; da Silva, Maria Gomes; Anjos, Diogo Remechido; Silva-Santos, Bruno

    2016-12-01

    The Vδ1 + subset of γδ T lymphocytes is a promising candidate for cancer immunotherapy, but the lack of suitable expansion/differentiation methods has precluded therapeutic application. We set out to develop and test (preclinically) a Vδ1 + T-cell-based protocol that is good manufacturing practice compatible and devoid of feeder cells for prompt clinical translation. We tested multiple combinations of clinical-grade agonist antibodies and cytokines for their capacity to expand and differentiate (more than 2-3 weeks) Vδ1 + T cells from the peripheral blood of healthy donors and patients with chronic lymphocytic leukemia (CLL). We characterized the phenotype and functional potential of the final cellular product, termed Delta One T (DOT) cells, in vitro and in vivo (xenograft models of CLL). We describe a very robust two-step protocol for the selective expansion (up to 2,000-fold in large clinical-grade cell culture bags) and differentiation of cytotoxic Vδ1 + (DOT) cells. These expressed the natural cytotoxicity receptors, NKp30 and NKp44, which synergized with the T-cell receptor to mediate leukemia cell targeting in vitro When transferred in vivo, DOT cells infiltrated tumors and peripheral organs, and persisted until the end of the analysis without showing signs of loss of function; indeed, DOT cells proliferated and produced abundant IFNγ and TNFα, but importantly no IL17, in vivo Critically, DOT cells were capable of inhibiting tumor growth and preventing dissemination in xenograft models of CLL. We provide a clinical-grade method and the preclinical proof of principle for application of a new cellular product, DOT cells, in adoptive immunotherapy of CLL. Clin Cancer Res; 22(23); 5795-804. ©2016 AACR. ©2016 American Association for Cancer Research.

  5. Impact of High Temperature Creep on the Buckling of Axially Compressed Steel Members

    NASA Astrophysics Data System (ADS)

    Włóka, Agata; Pawłowski, Kamil; Świerzko, Robert

    2017-10-01

    The paper presents results of the laboratory tests of the impact of creep on the buckling of axially compressed steel members at elevated temperatures. Tests were conducted on samples prepared of normal strength steel (S235JR) and high strength steel (S355J2). Samples were made in the form of a prismatic bar of a rectangular cross section 12 x 30 mm and a length of 500 mm. Support type of the specimens during tests was hinged on both ends. The tests were done at 600, 700 and 800°C. Experiments were carried out at static loads corresponding to values 0,8Ncr,T, 0,9Ncr,T, 1,0Ngr,T, where Ncr,T was theoretical value of Euler’s critical load at given temperature. Short-term creep analyses were performed in the universal testing machine Instron/Satec KN 600 equipped with a furnace for high-temperature testing type SF-16 2230, that enables testing at temperatures up to 1200°C. Temperature of the sample placed inside the furnace was verified and recorded with use of the compactRIO cRIO-9076 controller, equipped with a module for the connection of NI 9211 and K-type thermocouples. The system for the measurement and recording of the temperature of the analysed samples operated in the LabVIEW software environment. To measure lateral and longitudinal displacements LVTD Solatron ACR 100 displacement transducer was used. During the tests, the samples were heated to the given temperature (600, 700 or 800°C) and then subjected to a constant compressive load. During each test, for each sample following data was registered: the temperature on the surface of samples, longitudinal and lateral displacements in the middle of the sample. Basing on the conducted tests it was noted, for both analysed steel types, at the temperature of 800°C, growth of lateral displacements due to creep was very rapid, and tested elements were losing bearing capacity over the period of tens to hundreds of seconds, depending on stress level and the grade of the steel. At a temperature of 700°C growth

  6. Additive manufacturing for steels: a review

    NASA Astrophysics Data System (ADS)

    Zadi-Maad, A.; Rohib, R.; Irawan, A.

    2018-01-01

    Additive manufacturing (AM) of steels involves the layer by layer consolidation of powder or wire feedstock using a heating beam to form near net shape products. For the past decades, the AM technique reaches the maturation of both research grade and commercial production due to significant research work from academic, government and industrial research organization worldwide. AM process has been implemented to replace the conventional process of steel fabrication due to its potentially lower cost and flexibility manufacturing. This paper provides a review of previous research related to the AM methods followed by current challenges issues. The relationship between microstructure, mechanical properties, and process parameters will be discussed. Future trends and recommendation for further works are also provided.

  7. C3H7NO2S effect on concrete steel-rebar corrosion in 0.5 M H2SO4 simulating industrial/microbial environment

    NASA Astrophysics Data System (ADS)

    Okeniyi, Joshua Olusegun; Nwadialo, Christopher Chukwuweike; Olu-Steven, Folusho Emmanuel; Ebinne, Samaru Smart; Coker, Taiwo Ebenezer; Okeniyi, Elizabeth Toyin; Ogbiye, Adebanji Samuel; Durotoye, Taiwo Omowunmi; Badmus, Emmanuel Omotunde Oluwasogo

    2017-02-01

    This paper investigates C3H7NO2S (Cysteine) effect on the inhibition of reinforcing steel corrosion in concrete immersed in 0.5 M H2SO4, for simulating industrial/microbial environment. Different C3H7NO2S concentrations were admixed, in duplicates, in steel-reinforced concrete samples that were partially immersed in the acidic sulphate environment. Electrochemical monitoring techniques of open circuit potential, as per ASTM C876-91 R99, and corrosion rate, by linear polarization resistance, were then employed for studying anticorrosion effect in steel-reinforced concrete samples by the organic hydrocarbon admixture. Analyses of electrochemical test-data followed ASTM G16-95 R04 prescriptions including probability distribution modeling with significant testing by Kolmogorov-Smirnov and student's t-tests statistics. Results established that all datasets of corrosion potential distributed like the Normal, the Gumbel and the Weibull distributions but that only the Weibull model described all the corrosion rate datasets in the study, as per the Kolmogorov-Smirnov test-statistics. Results of the student's t-test showed that differences of corrosion test-data between duplicated samples with the same C3H7NO2S concentrations were not statistically significant. These results indicated that 0.06878 M C3H7NO2S exhibited optimal inhibition efficiency η = 90.52±1.29% on reinforcing steel corrosion in the concrete samples immersed in 0.5 M H2SO4, simulating industrial/microbial service-environment.

  8. Agreement Between Magnetic Resonance Imaging Proton Density Fat Fraction Measurements and Pathologist-Assigned Steatosis Grades of Liver Biopsies From Adults With Nonalcoholic Steatohepatitis.

    PubMed

    Middleton, Michael S; Heba, Elhamy R; Hooker, Catherine A; Bashir, Mustafa R; Fowler, Kathryn J; Sandrasegaran, Kumar; Brunt, Elizabeth M; Kleiner, David E; Doo, Edward; Van Natta, Mark L; Lavine, Joel E; Neuschwander-Tetri, Brent A; Sanyal, Arun; Loomba, Rohit; Sirlin, Claude B

    2017-09-01

    We assessed the diagnostic performance of magnetic resonance imaging (MRI) proton density fat fraction (PDFF) in grading hepatic steatosis and change in hepatic steatosis in adults with nonalcoholic steatohepatitis (NASH) in a multi-center study, using central histology as reference. We collected data from 113 adults with NASH participating in a multi-center, randomized, double-masked, placebo-controlled, phase 2b trial to compare the efficacy cross-sectionally and longitudinally of obeticholic acid vs placebo. Hepatic steatosis was assessed at baseline and after 72 weeks of obeticholic acid or placebo by liver biopsy and MRI (scanners from different manufacturers, at 1.5T or 3T). We compared steatosis estimates by PDFF vs histology. Histologic steatosis grade was scored in consensus by a pathology committee. Cross-validated receiver operating characteristic (ROC) analyses were performed. At baseline, 34% of subjects had steatosis grade 0 or 1, 39% had steatosis grade 2, and 27% had steatosis grade 3; corresponding mean PDFF values were 9.8%±3.7%, 18.1%±4.3%, and 30.1%±8.1%. PDFF classified steatosis grade 0-1 vs 2-3 with an area under the ROC curve (AUROC) of 0.95 (95% CI, 0.91-0.98), and grade 0-2 vs grade 3 steatosis with an AUROC of 0.96 (95% CI, 0.93-0.99). PDFF cut-off values at 90% specificity were 16.3% for grades 2-3 and 21.7% for grade 3, with corresponding sensitivities of 83% and 84%. After 72 weeks' of obeticholic vs placebo, 42% of subjects had a reduced steatosis grade (mean reduction in PDFF from baseline of 7.4%±8.7%), 49% had no change in steatosis grade (mean increase in PDFF from baseline of 0.3%±6.3%), and 9% had an increased steatosis grade (mean increase in PDFF from baseline of 7.7%±6.0%). PDFF change identified subjects with reduced steatosis grade with an AUROC of 0.81 (95% CI, 0.71-0.91) and increased steatosis grade with an AUROC of 0.81 (95% CI, 0.63-0.99). A PDFF reduction of 5.15% identified subjects with reduced steatosis grade

  9. Brittle crack arrestability of thick steel plate welds in large structure

    NASA Astrophysics Data System (ADS)

    An, Gyu Baek; Park, Joon Sik

    2011-10-01

    Recently, there has been such a critical issue in shipbuilding industry that much larger and stronger ships are required to develop oil and gas in the Arctic region. Attention has been paid to obtaining high strength, good toughness at low temperature, and good weldability. An experimental study was performed to evaluate the brittle crack arrest toughness value (Kca) and brittle crack arrest method of welded joints using EH40 grade steel with a thickness of 80 mm. The test specimens were made by both flux cored arc welding (FCAW) and combined welding (EGW+FCAW) processes. Temperature gradient ESSO test was performed to measure the Kca of the base metal. Also, a constant temperature (-10 °C) ESSO test was performed to establish a brittle crack arrest method using high toughness welding consumable with real structural specimens. The research aims in this study were to investigate the effect of joint design and welding consumable for the crack arrestability of thick steel plates using EH40 grade shipbuilding steel of straight block joint weld line with two kinds of welding processes.

  10. Associations of adiponectin and leptin with stage and grade of PSA-detected prostate cancer: the ProtecT study.

    PubMed

    Burton, Anya; Martin, Richard M; Holly, Jeff; Lane, J Athene; Donovan, Jenny L; Hamdy, Freddie C; Neal, David E; Tilling, Kate

    2013-02-01

    Obesity has been associated with an increased risk of advanced and fatal prostate cancer; adipokines may mediate this association. We examined associations of the adipokines leptin and adiponectin with the stage and grade of PSA-detected prostate cancer. We conducted a nested case-control study comparing 311 men with mainly locally advanced (≥T3, N1, or M1 cases) vs. 413 men with localized (T ≤2 & NX-0 & M0 controls) PSA-detected prostate cancer, recruited 2001-2009 from 9 UK regions to the ProtecT study. Associations of body mass index and adipokine levels with prostate cancer stage were determined by conditional logistic regression and with grade (Gleason score ≥7 vs. ≤6) by unconditional logistic regression. Adiponectin was inversely associated with prostate cancer stage in overweight and obese men (OR 0.62; 95 % CI 0.42-0.90; p = 0.01), but not in normal weight men (OR 1.48; 0.77-2.82; p = 0.24) (p for interaction 0.007), or all men (OR 0.86; 0.66-1.11; p = 0.24). There was no compelling evidence of associations between leptin or leptin to adiponectin ratio and prostate cancer stage. No strong associations of adiponectin, leptin, or leptin:adiponectin ratio with grade were seen. This study provides some evidence that adiponectin levels may be associated with prostate cancer stage, dependent on the degree of adiposity of the man. Our results are consistent with adiponectin countering the adverse effects of obesity on prostate cancer progression.

  11. P/M Processing of Rare Earth Modified High Strength Steels.

    DTIC Science & Technology

    1980-12-01

    AA094 165 TRW INC CLEVELAND OH MATERIALS TECHNOLOGY F 6 P/N PROCESSING OF RARE EARTH MODIFIED HIGH STRENGTH STEELS DEC So A A SHEXM(ER NOOŕT76-C...LEVEL’ (7 PIM PROCESSING OF RARE EARTH MODIFIED HIGH STRENGTH STEELS By A. A. SHEINKER 00 TECHNICAL REPORT Prepared for Office of Naval Research...Processing of Rare Earth Modified High 1 Technical -’ 3t eC"Strength Steels * 1dc4,093Se~ 9PEFRIGOGNZTONAEADADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK

  12. Microstructure-Property Correlations in Fiber Laser Welded Nb-Ti Microalloyed C-Mn Steel

    NASA Astrophysics Data System (ADS)

    Sun, Qian; Nie, Xiao-Kang; Li, Yang; Di, Hong-Shuang

    2018-02-01

    Mechanical Performance of traditional gas-shielded arc welded joints of 700 MPa grade microalloyed C-Mn steel cannot meet service requirements. Laser welding, with its characteristic high energy density, is known to improve the welding performance of experimental steels. In the present study, Nb-Ti microalloyed steel with a thickness of 4.5 mm was welded using a 4 kW fiber laser. The microstructure, precipitation, and mechanical properties of the welded joints were studied. The hardness and tensile strength of the welded joints were higher than those of the base metal (BM). The microstructure of the fusion zone (FZ) and coarse grain heat affected zone (CGHAZ) was lath martensite (LM), while the microstructure of the fine grain HAZ and mixed grain HAZ consisted of ferrite and martensite/austenite islands. Although LM was observed in both the FZ and CGHAZ, the hardness and calculated tensile strength of the FZ were lower than those of the CGHAZ, due to a reduction in solid solution strengthening by element loss and the dissolution of high-hardness precipitates in FZ. Most precipitates such as [(Nb,Ti)C and (Nb,Ti)(C,N)] that were present in the BM were dissolved, which led to an increase in C and N in solid solution in the FZ. Thus, the elastic modulus of the FZ was higher than that of the BM. Similarly, the elastic modulus of the CGHAZ was higher than that of the BM due to the segregation of C and N atoms during the welding process. The toughness of the FZ was superior to that of the BM, and the toughness of the HAZ approached 91% of that of the BM. The change in toughness primarily depended on the microstructural refinement, the increase in the fraction of grains with high misorientation, the residual austenite in the FZ and CGHAZ, and the dissolution of coarse precipitates.

  13. Effects of Surface Roughness, Oxidation, and Temperature on the Emissivity of Reactor Pressure Vessel Alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    King, J. L.; Jo, H.; Tirawat, R.

    Thermal radiation will be an important mode of heat transfer in future high-temperature reactors and in off-normal high-temperature scenarios in present reactors. In this work, spectral directional emissivities of two reactor pressure vessel (RPV) candidate materials were measured at room temperature after exposure to high-temperature air. In the case of SA508 steel, significant increases in emissivity were observed due to oxidation. In the case of Grade 91 steel, only very small increases were observed under the tested conditions. Effects of roughness were also investigated. To study the effects of roughening, unexposed samples of SA508 and Grade 91 steel were roughenedmore » via one of either grinding or shot-peening before being measured. Significant increases were observed only in samples having roughness exceeding the roughness expected of RPV surfaces. While the emissivity increases for SA508 from oxidation were indeed significant, the measured emissivity coefficients were below that of values commonly used in heat transfer models. Based on the observed experimental data, recommendations for emissivity inputs for heat transfer simulations are provided.« less

  14. Diagnostic accuracy of automatic normalization of CBV in glioma grading using T1- weighted DCE-MRI.

    PubMed

    Sahoo, Prativa; Gupta, Rakesh K; Gupta, Pradeep K; Awasthi, Ashish; Pandey, Chandra M; Gupta, Mudit; Patir, Rana; Vaishya, Sandeep; Ahlawat, Sunita; Saha, Indrajit

    2017-12-01

    Aim of this retrospective study was to compare diagnostic accuracy of proposed automatic normalization method to quantify the relative cerebral blood volume (rCBV) with existing contra-lateral region of interest (ROI) based CBV normalization method for glioma grading using T1-weighted dynamic contrast enhanced MRI (DCE-MRI). Sixty patients with histologically confirmed gliomas were included in this study retrospectively. CBV maps were generated using T1-weighted DCE-MRI and are normalized by contralateral ROI based method (rCBV_contra), unaffected white matter (rCBV_WM) and unaffected gray matter (rCBV_GM), the latter two of these were generated automatically. An expert radiologist with >10years of experience in DCE-MRI and a non-expert with one year experience were used independently to measure rCBVs. Cutoff values for glioma grading were decided from ROC analysis. Agreement of histology with rCBV_WM, rCBV_GM and rCBV_contra respectively was studied using Kappa statistics and intra-class correlation coefficient (ICC). The diagnostic accuracy of glioma grading using the measured rCBV_contra by expert radiologist was found to be high (sensitivity=1.00, specificity=0.96, p<0.001) compared to the non-expert user (sensitivity=0.65, specificity=0.78, p<0.001). On the other hand, both the expert and non-expert user showed similar diagnostic accuracy for automatic rCBV_WM (sensitivity=0.89, specificity=0.87, p=0.001) and rCBV_GM (sensitivity=0.81, specificity=0.78, p=0.001) measures. Further, it was also observed that, contralateral based method by expert user showed highest agreement with histological grading of tumor (kappa=0.96, agreement 98.33%, p<0.001), however; automatic normalization method showed same percentage of agreement for both expert and non-expert user. rCBV_WM showed an agreement of 88.33% (kappa=0.76,p<0.001) with histopathological grading. It was inferred from this study that, in the absence of expert user, automated normalization of CBV using the

  15. 76 FR 54735 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Opportunity To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-02

    ... Grade Ammonium Nitrate, A-823- 9/1/10-8/31/11 810 Steel Concrete Reinforcing Bars, A-823-809....... 9/1...(d)(1), a party that has requested a review may withdraw that request within 90 days of the date of...

  16. Experimental investigation of microbiologically influenced corrosion of selected steels in sugarcane juice environment.

    PubMed

    Wesley, Sunil Bala; Maurya, Devendra Prasad; Goyal, Hari Sharan; Negi, Sangeeta

    2013-12-01

    In the current study, ferritic stainless grades AISI 439 and AISI 444 were investigated as possible construction materials for machinery and equipment in the cane-sugar industry. Their performance in corrosive cane-sugar juice environment was compared with the presently used low carbon steel AISI 1010 and austenitic stainless steel AISI 304. The Tafel plot electrochemical technique was used to evaluate general corrosion performance. Microbiologically influenced corrosion (MIC) behaviour in sugarcane juice environment was studied. Four microbial colonies were isolated from the biofilms on the metal coupon surfaces on the basis of their different morphology. These were characterized as Brevibacillus parabrevis, Bacillus azotoformans, Paenibacillus lautus and Micrococcus sp. The results of SEM micrographs showed that AISI 439 and AISI 304 grades had suffered maximum localized corrosion. MIC investigations revealed that AISI 444 steel had the best corrosion resistance among the tested materials. However from the Tafel plots it was evident that AISI 1010 had the least corrosion resistance and AISI 439 the best corrosion resistance.

  17. Stainless steels for cryogenic bolts and nuts (in French)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Leroy, F.; Rabbe, P.; Odin, G.

    1975-03-01

    Stainless steel for cryogenic applications are generally austenitic steels which, under the effect of cold-drawing, can or cannot undergo a partial martensitic transformation according to their composition. It has been shown that very high ductility and endurance characteristics at low temperatures, together with very high yield strength and resistances values, can be attained with grades of nitrogenous steels of types Z2CN18-10N and Z3CMN18-8-6N. Optimum ductility values are obtained by employing to the best possible, the martensitic transformations which develop during cold-drawing. From the plotting of the rational traction curves, it is possible to analyse very simply the influence of themore » composition on the martensitic transformations. (FR)« less

  18. 40 CFR 91.603 - Applicability of part 91, subpart F.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Applicability of part 91, subpart F. 91.603 Section 91.603 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES Selective Enforcement Auditing...

  19. Direction of R&D and Current Status of Understanding of Advanced Gear Steels

    DTIC Science & Technology

    1986-02-01

    our laboratory. A-Z 9-4 CBS600 was developed by Timken as a carburizing grade bearing steel for service above 150C. The philosophy used in designing...melted (VIM-VAR) steels . The effect of long time aging at 230C on the Charpy energy for CBS600 is currently underway at AMMRC. M50 NIL General Electric, in...contact fatigue life and hot hardness as high as for P50 (the high hot hardness bearing steel widely used in aircraft gas turbine engines in the USA) the

  20. Welding High Strength Modern Line Pipe Steel

    NASA Astrophysics Data System (ADS)

    Goodall, Graeme Robertson

    The effect of modern mechanized girth welding on high strength line pipe has been investigated. The single cycle grain coarsened heat affected zone in three grade 690 line pipe steels and a grade 550 steel has been simulated using a Gleeble thermo-mechanical simulator. The continuous cooling transformation diagrams applicable to the grain coarsened heat affected zone resulting from a range of heat inputs applicable to modern mechanized welding have been established by dilatometry and metallography. The coarse grained heat affected zone was found to transform to lath martensite, bainite, and granular bainite depending on the cooling rate. The impact toughness of the steels was measured using Charpy impact toughness and compared to the toughness of the grain coarsened heat affected zone corresponding to a welding thermal cycle. The ductile to brittle transition temperature was found to be lowest for the steel with the highest hardenability. The toughness resulting from three different thermal cycles including a novel interrupted intercritically reheated grain coarsened (NTR ICR GC HAZ) that can result from dual torch welding at fast travel speed and close torch spacing have been investigated. All of the thermally HAZ regions showed reduced toughness that was attributed to bainitic microstructure and large effective grain sizes. Continuous cooling transformation diagrams for five weld metal chemistries applicable to mechanized pulsed gas metal arc welding of modern high strength pipe steel (SMYS>550 MPa) have been constructed. Welds at heat inputs of 1.5 kJmm-1 and 0.5 kJmm-1 have been created for simulation and analysis. Dilatometric analysis was performed on weld metal specimens cut from single pass 1.5 kJmm-1 as deposited beads. The resulting microstructures were found to range from martensite to polygonal ferrite. There is excellent agreement between the simulated and as deposited weld metal regions. Toughness testing indicates improved energy absorption at -20

  1. Publications - PDF 91-6 | Alaska Division of Geological & Geophysical

    Science.gov Websites

    content DGGS PDF 91-6 Publication Details Title: Summary of Alaska's mineral industry for 1990 Authors ., Bundtzen, T.K., and Wood, J.E., 1991, Summary of Alaska's mineral industry for 1990: Alaska Division of

  2. Thermophysical and Electronic Properties of Foreign Stainless Steels, A Comprehensive Survey of the World Literature,

    DTIC Science & Technology

    1981-11-01

    included in its companion volume on nonstainless alloy steels carbon steels and cast irons. The TEPIAC retrieval system is based on assigning a seven...LOEFFILIENTS OF STRTUCTURAL M;.TE.)IALS AT LOW A. T,-E Tt-i!1AL 0,)NCuCfIVITY AND ITHE THERIIAL T ImA-FRi.Tu’ES. 11,fC’.4T OF IROI. AND STEELS It, THE Hlf...PROPERTIES OF FOREIGN STAINLESS STEELS A Comprehensive Survey of the World Literature P.D. DESAI CINDAS REPORT 61 November 1981 DTICS ELECTE Prepared by 0U

  3. Oxidation of Uncoated and Aluminized 9-12% Cr Boiler Steels at 550-650 °C

    NASA Astrophysics Data System (ADS)

    Metsäjoki, J.; Huttunen-Saarivirta, E.; Lepistö, T.

    2011-03-01

    In this paper, oxidation behavior of 9-12% Cr steels P91 and HCM12A is studied in air and in a mixture of air and water vapor. Comparison is made between these steels in uncoated condition and coated with aluminum diffusion coating by a slurry method. Oxidation tests were carried out at 550, 600, and 650 °C for a discontinued duration of 1000 h; every 250 h the specimens were slowly cooled to room temperature and weighed. SEM + EDS and XRD characterization were performed after 500 and 1000 h. The results showed that oxidation rate of uncoated P91 and HCM12A was significantly higher in the mixture of air and water vapor than in air. Oxidation resistance of the studied materials improved substantially when they were aluminized.

  4. Effects of Post Annealing on I-V-T Characteristics of (Ni/Au)/Al0.09Ga0.91N Schottky Barrier Diodes

    NASA Astrophysics Data System (ADS)

    Akkaya, Abdullah; Ayyıldız, Enise

    2016-04-01

    Post annealing is a simple, effective and suitable method for improving the diode parameters, especially when the used chemically stable substrates like Si, III-N and ternary alloys. In our work, we were applied this method to (Ni/Au)/Al0.09Ga0.91N Schottky Barrier Diodes (SBDs) and investigated by temperature-dependent current-voltage (I-V-T) characteristics at optimum conditions. Optimum annealing temperature was 600°C, which it’s determined with respect to have a highest barrier height value. The temperature-dependent electrical characteristics of the annealed at 600°C (Ni/Au)/Al0.09Ga0.91N SBDs were investigated in the wide temperature range of 95-315K. The diode parameters such as ideality factor (n) and Schottky barrier height (Vb0) were obtained to be strongly temperature dependent. The observed variation in Vb0 and n can be attributed to the spatial barrier inhomogeneities in Schottky barrier height by assuming a triple Gaussian distribution (TGD) of barrier heights (BHs) at 95-145K, 145-230K and 230-315K. The modified Richardson plots and T0 analysis was performed to provide an experimental Richardson constants and bias coefficients of the mean barrier height. Furthermore, the chemical composition of the contacts was examined by the XPS depth profile analysis.

  5. Ballistic-Failure Mechanisms in Gas Metal Arc Welds of Mil A46100 Armor-Grade Steel: A Computational Investigation

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Snipes, J. S.; Galgalikar, R.; Ramaswami, S.; Yavari, R.; Yen, C.-F.; Cheeseman, B. A.

    2014-09-01

    In our recent work, a multi-physics computational model for the conventional gas metal arc welding (GMAW) joining process was introduced. The model is of a modular type and comprises five modules, each designed to handle a specific aspect of the GMAW process, i.e.: (i) electro-dynamics of the welding-gun; (ii) radiation-/convection-controlled heat transfer from the electric-arc to the workpiece and mass transfer from the filler-metal consumable electrode to the weld; (iii) prediction of the temporal evolution and the spatial distribution of thermal and mechanical fields within the weld region during the GMAW joining process; (iv) the resulting temporal evolution and spatial distribution of the material microstructure throughout the weld region; and (v) spatial distribution of the as-welded material mechanical properties. In the present work, the GMAW process model has been upgraded with respect to its predictive capabilities regarding the spatial distribution of the mechanical properties controlling the ballistic-limit (i.e., penetration-resistance) of the weld. The model is upgraded through the introduction of the sixth module in the present work in recognition of the fact that in thick steel GMAW weldments, the overall ballistic performance of the armor may become controlled by the (often inferior) ballistic limits of its weld (fusion and heat-affected) zones. To demonstrate the utility of the upgraded GMAW process model, it is next applied to the case of butt-welding of a prototypical high-hardness armor-grade martensitic steel, MIL A46100. The model predictions concerning the spatial distribution of the material microstructure and ballistic-limit-controlling mechanical properties within the MIL A46100 butt-weld are found to be consistent with prior observations and general expectations.

  6. Stainless Steel Permeability

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Buchenauer, Dean A.; Karnesky, Richard A.

    An understanding of the behavior of hydrogen isotopes in materials is critical to predicting tritium transport in structural metals (at high pressure), estimating tritium losses during production (fission environment), and predicting in-vessel inventory for future fusion devices (plasma driven permeation). Current models often assume equilibrium diffusivity and solubility for a class of materials (e.g. stainless steels or aluminum alloys), neglecting trapping effects or, at best, considering a single population of trapping sites. Permeation and trapping studies of the particular castings and forgings enable greater confidence and reduced margins in the models. For FY15, we have continued our investigation of themore » role of ferrite in permeation for steels of interest to GTS, through measurements of the duplex steel 2507. We also initiated an investigation of the permeability in work hardened materials, to follow up on earlier observations of unusual permeability in a particular region of 304L forgings. Samples were prepared and characterized for ferrite content and coated with palladium to prevent oxidation. Issues with the poor reproducibility of measurements at low permeability were overcome, although the techniques in use are tedious. Funding through TPBAR and GTS were secured for a research grade quadrupole mass spectrometer (QMS) and replacement turbo pumps, which should improve the fidelity and throughput of measurements in FY16.« less

  7. Bond characteristics of reinforcing steel embedded in geopolymer concrete

    NASA Astrophysics Data System (ADS)

    Kathirvel, Parthiban; Thangavelu, Manju; Gopalan, Rashmi; Raja Mohan Kaliyaperumal, Saravana

    2017-07-01

    The force transferring between reinforcing steel and the surrounding concrete in reinforced concrete is influenced by several factors. Whereas, the study on bond behaviour of geopolymer concrete (GPC) is lagging. In this paper, an experimental attempt has been made to evaluate the geopolymer concrete bond with reinforcing steel of different diameter and embedded length using standard pull out test. The geopolymer concrete is made of ground granulated blast furnace slag (GGBFS) as geopolymer source material (GSM). The tests were conducted to evaluate the development of bond between steel and concrete of grade M40 and M50 with 12 and 16 mm diameter reinforcing steel for geopolymer and cement concrete mixes and to develop a relation between bond strength and compressive strength. From the experimental results, it has been observed that the bond strength of the geopolymer concrete mixes was more compared to the cement concrete mixes and increases with the reduction in the diameter of the bar.

  8. 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

  9. 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.

  10. Optimization of the A-TIG welding for stainless steels

    NASA Astrophysics Data System (ADS)

    Jurica, M.; Kožuh, Z.; Garašić, I.; Bušić, M.

    2018-03-01

    The paper presents the influence of the activation flux and shielding gas on tungsten inert gas (A-TIG) welding of the stainless steel. In introduction part, duplex stainless steel was analysed. The A-TIG process was explained and the possibility of welding stainless steels using the A-TIG process to maximize productivity and the cost-effectiveness of welded structures was presented. In the experimental part duplex, 7 mm thick stainless steel has been welded in butt joint. The influence of activation flux chemical composition upon the weld penetration has been investigated prior the welding. The welding process was performed by a robot with TIG equipment. With selected A-TIG welding technology preparation of plates and consumption of filler material (containing Cr, Ni and Mn) have been avoided. Specimens sectioned from the produced welds have been subjected to tensile strength test, macrostructure analysis and corrosion resistance analysis. The results have confirmed that this type of stainless steel can be welded without edge preparation and addition of filler material containing critical raw materials as Cr, Ni and Mn when the following welding parameters are set: current 200 A, welding speed 9,1 cm/min, heat input 1,2 kJ/mm and specific activation flux is used.

  11. Thrust exhumation of the Southern Marginal Zone of the Limpopo Complex in the Neoarchaean: link of distinct high-grade shear zones with DC and IC P-T-t paths

    NASA Astrophysics Data System (ADS)

    Smit, C. Andre; van Reenen, Dirk D.

    2010-05-01

    The Limpopo Complex is a ~750km long E-W trending zone of predominantly granulite facies rocks situated between the Archaean Kaapvaal and Zimbabwe cratons of southern Africa. Large ductile shear zones are an integral part of the Limpopo architecture, defining the boundaries between the belt and the adjacent cratons and are interpreted to have been responsible for uplift (exhumation) of over thickened crust during the Neoarchaean [10 and references therein; 1]. The Hout River Shear Zone forms the terrane boundary between the granite-greenstone terrane of the Kaapvaal craton in the south and the high-grade Southern Marginal Zone (SMZ) of the Limpopo Complex in the north. Integrated structural, metamorphic, magmatic and age data collected over a period of more than 30 years provide convincing evidence for a Neoarchean high-grade tectono-metamorphic event that affected the SMZ in the interval ~2.72 - 2.60 Ga [4; 5, 6; 7; 2; 8; 9; 11]. The thrust-controlled exhumation of the SMZ is demonstrated by the convergence of a retrograde P-T path in the hanging wall (SMZ) and a prograde P-T loop in the footwall (Kaapvaal Craton) of the steeply SW-verging Hout River Shear Zone [4; 5]. The coeval ages (~2.69 Ga) of the two contrasting metamorphic histories are indicated by geochronological data [2; 3]. In addition, the establishment of a retrograde isograd and zone of rehydrated granulites in the hanging wall by hydrous CO2-rich fluids derived by dehydration of the low-grade rocks in the footwall provides another convincing link between the two contrasting metamorphic environments [10]. Distinct retrograde P-T paths [4; 6; 8] linked to distinct shear deformational events document evidence for a two-stage post-peak exhumation history of the SMZ: (i) granulites sampled far from the contact with the cool rocks of the Kaapvaal Craton are characterized by P-T paths with two distinct decompression-cooling (DC) stages (DC=>DC paths), (ii) granulites sampled close to this contact are

  12. Outlook of the world steel cycle based on the stock and flow dynamics.

    PubMed

    Hatayama, Hiroki; Daigo, Ichiro; Matsuno, Yasunari; Adachi, Yoshihiro

    2010-08-15

    We present a comprehensive analysis of steel use in the future compiled using dynamic material flow analysis (MFA). A dynamic MFA for 42 countries depicted the global in-use stock and flow up to the end of 2005. On the basis of the transition of steel stock for 2005, the growth of future steel stock was then estimated considering the economic growth for every country. Future steel demand was estimated using dynamic analysis under the new concept of "stocks drive flows". The significant results follow. World steel stock reached 12.7 billion t in 2005, and has doubled in the last 25 years. The world stock in 2005 mainly consisted of construction (60%) and vehicles (10%). Stock in these end uses will reach 55 billion t in 2050, driven by a 10-fold increase in Asia. Steel demand will reach 1.8 billion t in 2025, then slightly decrease, and rise again by replacement of buildings. The forecast of demand clearly represents the industrial shift; at first the increase is dominated by construction, and then, after 2025, demand for construction decreases and demand for vehicles increases instead. This study thus provides the dynamic mechanism of steel stock and flow toward the future, which contributes to the design of sustainable steel use.

  13. Novel Investigation on Nanostructured Multilayer and Functionally Graded Ni-P Electroless Coatings on Stainless Steel

    NASA Astrophysics Data System (ADS)

    Anvari, S. R.; Monirvaghefi, S. M.; Enayati, M. H.

    2015-06-01

    In this study, step-wise multilayer and functionally graded Ni-P coatings were deposited with electroless in which the content of phosphorus and nickel would be changed gradually and step-wise through the thickness of the coatings, respectively. To compare the properties of these coatings with Ni-P single-layer coatings, three types of coatings with different phosphorus contents were deposited. Heat treatment of coatings was performed at 400 °C for 1 h. The microstructure and phase transformation of coatings were characterized by SEM/EDS, TEM, and XRD. The mechanical properties of coatings were studied by nanoindentation test. According to the results of the single-layer coatings, low P coating had the maximum hardness and also the ratio of hardness ( H) to elasticity modulus ( E) for the mentioned coating was maximum. In addition, low and medium P coatings had crystalline and semi-crystalline structure, respectively. The mentioned coatings had <111> texture and after heat treatment their texture didn't change. While high P coating had amorphous structure, after heat treatment it changed to crystalline structure with <100> texture for nickel grains. Furthermore, the results showed that functionally graded and step-wise multilayer coatings were deposited successfully by using the same initial bath and changing the temperature and pH during deposition. Nanoindentation test results showed that the hardness of the mentioned coatings changed from 670 Hv near the substrate to 860 Hv near the top surface of coatings. For functionally graded coating the hardness profile had gradual changes, while step-wise multilayer coating had step-wise hardness profile. After heat treatment trend of hardness profiles was changed, so that near the substrate, hardness was measured 1400 Hv and changed to 1090 Hv at the top coat.

  14. Identification of the propionicin F bacteriocin immunity gene (pcfI) and development of a food-grade cloning system for Propionibacterium freudenreichii.

    PubMed

    Brede, Dag Anders; Lothe, Sheba; Salehian, Zhian; Faye, Therese; Nes, Ingolf F

    2007-12-01

    This report describes the first functional analysis of a bacteriocin immunity gene from Propionibacterium freudenreichii and its use as a selection marker for food-grade cloning. Cloning of the pcfI gene (previously orf5 [located as part of the pcfABC propionicin F operon]) rendered the sensitive host 1,000-fold more tolerant to the propionicin F bacteriocin. The physiochemical properties of the 127-residue large PcfI protein resemble those of membrane-bound immunity proteins from bacteriocin systems found in lactic acid bacteria. The high level of immunity conferred by pcfI allowed its use as a selection marker for plasmid transformation in P. freudenreichii. Electroporation of P. freudenreichii IFO12426 by use of the pcfI expression plasmid pSL102 and propionicin F selection (200 bacteriocin units/ml) yielded 10(7) transformants/microg DNA. The 2.7-kb P. freudenreichii food-grade cloning vector pSL104 consists of the pLME108 replicon, a multiple cloning site, and pcfI expressed from the constitutive P(pampS) promoter for selection. The pSL104 vector efficiently facilitated cloning of the propionicin T1 bacteriocin in P. freudenreichii. High-level propionicin T1 production (640 BU/ml) was obtained with the IFO12426 strain, and the food-grade propionicin T1 expression plasmid pSL106 was maintained by approximately 91% of the cells over 25 generations in the absence of selection. To the best of our knowledge this is the first report of an efficient cloning system that facilitates the generation of food-grade recombinant P. freudenreichii strains.

  15. Tribological behavior of CrN-coated Cr-Mo-V steels used as die materials

    NASA Astrophysics Data System (ADS)

    Çelik, Gülşah Aktaş; Polat, Şeyda; Atapek, Ş. Hakan

    2017-12-01

    DIN 1.2343 and 1.2367 steels are commonly used as die materials in aluminum extrusion, and single/duplex/multi-coatings enhance their surface properties. The design of an appropriate substrate/coating system is important for improving the tribological performance of these steels under service conditions because the load-carrying capacity of the system can be increased by decreasing the plastic deformation of the substrate. In this study, the tribological behavior of CrN-coated Cr-Mo-V steels (DIN 1.2343, 1.2367, and 1.2999 grades) was investigated using different setups and tribological pairs at room and elevated temperatures. The aim of this study was to reveal the wear resistance of a suggested system (1.2999/CrN) not yet studied and to understand both the wear and the failure characteristics of coated systems. The results showed that (i) among the steels studied, the DIN 1.2999 grade steel exhibited the lowest friction coefficient because it had the highest load-carrying capacity as a result of secondary hardening at elevated temperatures; (ii) at room temperature, both abrasive tracks and adhesive layers were observed on the worn surfaces; and (iii) a combination of chemical reactions and progressive oxidation caused aluminum adhesion on the worn surface, and the detachment of droplets and microcracking were the characteristic damage mechanisms at high temperatures.

  16. Hazard report. Don't use industrial-grade gases for clinical applications.

    PubMed

    2010-01-01

    The use of industrial-grade gases instead of medical-grade gases for clinical applications increases the risk of introducing undesirable and even toxic contaminants into the clinical environment. Hospitals should have policies in place to ensure that gases of the appropriate type and grade are used for the intended application.

  17. Vacuum brazing of 316L stainless steel based on additively manufactured and conventional material grades

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Henning, T.; Wojarski, L.

    2018-06-01

    Many industrial applications require components with an increasing geometric complexity and specific material properties. Furthermore, the production costs and the affordable production time have to be minimized in order to ensure competitiveness. These divergent objectives are difficult to achieve with a single manufacturing technology. Therefore, joining of selective laser melted (SLM) complex shaped parts to conventionally produced high-volume components provides a high potential. The current investigation focuses on vacuum brazing conventionally manufactured to non-hipped SLM generated AISI 316L stainless steel. Cylindrical samples (Ø 14 mm) were brazed using a B-Ni2 foil (50 µm) at 1050 °C for 30 minutes in vacuum (< 4.5·10-5 mbar) and directly cooled down to room temperature with 4 bar overpressure to prevent the formation of chromium carbides within the base material. It could be proven that the brazing quality is extremely sensitive to even marginal porosities (< 0.2 %) and/or oxide inclusions of the SLM microstructure. Therefore, the fracture mirror in SLM/conventional steel brazements was at the joint braze/SLM steel interface, leading to a joint strength of 317.4 MPa. This corresponds to only 67.4 % of the joint strength obtained with conventional steel, where the fracture propagated through the diffusion area.

  18. European developments in the application of structural austenitic and duplex stainless steels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cochrane, D.J.

    1995-12-31

    Stainless steel is increasingly being specified for structural applications. Principally, this is due to the aesthetic appeal of the material, no need for surface protection, durability, and the growing awareness, and use, of Life Cycle Cost analysis for assessing costs over the longer term, However, use of stainless steel in the U.K. offshore oil and gas platforms for fire and blast walls, has highlighted valuable properties of stainless steel that may be unfamiliar to structural designers. It is the purpose of this paper to demonstrate these properties. Additionally, new design guidance has become available in Europe as a result ofmore » a 4 year research program into the structural use of stainless steel. The ``Design Manual for Structural Stainless Steel`` was issued by Euro Inox and the Nickel Development Institute in 1994. This new manual will be outlined in this paper together with its influence on new European Building Standards and new European material standards for structural stainless steel. Currently in preparation, these include high strength grades with significantly higher strength than structural carbon steels. Finally, this paper will address the use of stainless steel for the reinforcement of concrete structures.« less

  19. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Meimei; Natesan, K.; Chen, Wei-Ying

    This report provides an update on the understanding of the effect of sodium exposures on microstructure and tensile properties of Grade 91 (G91) steel in support of the design and operation of G91 components in sodium-cooled fast reactors (SFRs). The report is a Level 3 deliverable in FY17 (M3AT-17AN1602018), under the Work Package AT-17AN160201, “SFR Materials Testing” performed by the Argonne National Laboratory (ANL), as part of the Advanced Reactor Technologies Program.

  20. Corrosion Effects on the Fatigue Crack Propagation of Giga-Grade Steel and its Heat Affected Zone in pH Buffer Solutions for Automotive Application

    NASA Astrophysics Data System (ADS)

    Lee, H. S.

    2018-03-01

    Corrosion fatigue crack propagation test was conducted of giga-grade steel and its heat affected zone in pH buffer solutions, and the results were compared with model predictions. Pure corrosion effect on fatigue crack propagation, particularly, in corrosive environment was evaluated by means of the modified Forman equation. As shown in results, the average corrosion rate determined from the ratio of pure corrosion induced crack length to entire crack length under a cycle load were 0.11 and 0.37 for base metal and heat affected zone, respectively, with load ratio of 0.5, frequency of 0.5 and pH 10.0 environment. These results demonstrate new interpretation methodology for corrosion fatigue crack propagation enabling the pure corrosion effects on the behavior to be determined.

  1. Final Report on MEGAPIE Target Irradiation and Post-Irradiation Examination

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yong, Dai

    2015-06-30

    Megawatt pilot experiment (MEGAPIE) was successfully performed in 2006. One of the important goals of MEGAPIE is to understand the behaviour of structural materials of the target components exposed to high fluxes of high-energy protons and spallation neutrons in flowing LBE (liquid lead-bismuth eutectic) environment by conducting post-irradiation examination (PIE). The PIE includes four major parts: non-destructive test, radiochemical analysis of production and distribution of radionuclides produced by spallation reaction in LBE, analysis of LBE corrosion effects on structural materials, T91 and SS 316L steels, and mechanical testing of the T91 and SS 316L steels irradiated in the lower partmore » of the target. The non-destructive test (NDT) including visual inspection and ultrasonic measurement was performed in the proton beam window area of the T91 calotte of the LBE container, the most intensively irradiated part of the MEGAPIE target. The visual inspection showed no visible failure and the ultrasonic measurement demonstrated no detectable change in thickness in the beam window area. Gamma mapping was also performed in the proton beam window area of the AlMg 3 safety-container. The gamma mapping results were used to evaluate the accumulated proton fluence distribution profile, the input data for determining irradiation parameters. Radiochemical analysis of radionuclides produced by spallation reaction in LBE is to improve the understanding of the production and distribution of radionuclides in the target. The results demonstrate that the radionuclides of noble metals, 207Bi, 194Hg/Au are rather homogeneously distributed within the target, while radionuclides of electropositive elements are found to be deposited on the steel-LBE interface. The corrosion effect of LBE on the structural components under intensive irradiation was investigated by metallography. The results show that no evident corrosion damages. However, unexpected deep cracks were found in the

  2. Study of Cold Coiling Spring Steel on Microstructure and Cold Forming Performance

    NASA Astrophysics Data System (ADS)

    Jiang, Y.; Liang, Y. L.; Ming, Y.; Zhao, F.

    2017-09-01

    Medium-carbon cold-coiling locomotive spring steels were treated by a novel Q-P-T (quenching-partitioning-tempering) process. Scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD) were used to characterize the relevant parameters of the steel. Results show that the microstructure of tested steel treated by Q-P-T process is a complex microstructures composed of martensite, bainite and retained austenite. The volume fraction of retained austenite (wt.%) is up to 31%. After pre-deforming and tempering again at 310°C, the plasticity of samples treated by Q-P-T process is still well. Fracture images show that the Q-P-T samples are ductile fracture. It is attributed to the higher volume fraction of the retained austenite and the interactions between the multi-phases in Q-P-T processed sample.

  3. Heat treated 9 Cr-1 Mo steel material for high temperature application

    DOEpatents

    Jablonski, Paul D.; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-08-21

    The invention relates to a composition and heat treatment for a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The novel combination of composition and heat treatment produces a heat treated material containing both large primary titanium carbides and small secondary titanium carbides. The primary titanium carbides contribute to creep strength while the secondary titanium carbides act to maintain a higher level of chromium in the finished steel for increased oxidation resistance, and strengthen the steel by impeding the movement of dislocations through the crystal structure. The heat treated material provides improved performance at comparable cost to commonly used high-temperature steels such as ASTM P91 and ASTM P92, and requires heat treatment consisting solely of austenization, rapid cooling, tempering, and final cooling, avoiding the need for any hot-working in the austenite temperature range.

  4. Physical Properties of AZ91D Measured Using the Draining Crucible Method: Effect of SF6

    NASA Astrophysics Data System (ADS)

    Roach, Steven J.; Henein, Hani

    2012-03-01

    The draining crucible (DC) technique was used for measurements on AZ91D under Ar and SF6. The DC technique is a new method developed to simultaneously measure the physical properties of fluids, the density, surface tension, and viscosity. Based on the relationship between the height of a metal in a crucible and the outgoing flow rate, a multi-variable regression is used to calculate the values of these fluid properties. Experiments performed with AZ91D at temperatures from 923 K to 1173 K indicate that under argon, the surface tension (N · m-1) and density (kg · m-3) are [0.63 - 2.13 × 10-4 ( T - T L)] and [1656 - 0.158 ( T - T L)], respectively. The viscosity (Pa · s) has been determined to be [1.455 × 10-3 - 1.209 × 10-5 ( T - T L)] over the temperature range from 921 K to 967 K superheat. Above 967 K, the viscosity of the alloy under argon seems to be constant at (2.66 × 10-4 ± 8.67 × 10-5) Pa · s. SF6 reduces the surface tension of AZ91D.

  5. Nanocomposite coatings on biomedical grade stainless steel for improved corrosion resistance and biocompatibility.

    PubMed

    Nagarajan, Srinivasan; Mohana, Marimuthu; Sudhagar, Pitchaimuthu; Raman, Vedarajan; Nishimura, Toshiyasu; Kim, Sanghyo; Kang, Yong Soo; Rajendran, Nallaiyan

    2012-10-24

    The 316 L stainless steel is one of the most commonly available commercial implant materials with a few limitations in its ease of biocompatibility and long-standing performance. Hence, porous TiO(2)/ZrO(2) nanocomposite coated over 316 L stainless steels was studied for their enhanced performance in terms of its biocompatibility and corrosion resistance, following a sol-gel process via dip-coating technique. The surface composition and porosity texture was studied to be uniform on the substrate. Biocompatibility studies on the TiO(2)/ZrO(2) nanocomposite coatings were investigated by placing the coated substrate in a simulated body fluid (SBF). The immersion procedure resulted in the complete coverage of the TiO(2)/ZrO(2) nanocomposite (coated on the surface of 316 L stainless steel) with the growth of a one-dimensional (1D) rod-like carbonate-containing apatite. The TiO(2)/ZrO(2) nanocomposite coated specimens showed a higher corrosion resistance in the SBF solution with an enhanced biocompatibility, surpassing the performance of the pure oxide coatings. The cell viability of TiO(2)/ZrO(2) nanocomposite coated implant surface was examined under human dermal fibroblasts culture, and it was observed that the composite coating enhances the proliferation through effective cellular attachment compared to pristine 316 L SS surface.

  6. NASA Astrophysics Data System (ADS)

    Scapin, M.; Peroni, L.; Fichera, C.; Cambriani, A.

    2014-08-01

    High chromium ferritic/martensitic steel T91 (9% Cr, 1% Mo), on account of its radiation resistance, is a candidate material for nuclear reactor applications. Its joining by an impact method to create a cold joint is tested in the realm of scoping tests toward the safe operation of nuclear fuels, encapsulated in representative T91 materials. Hitherto, T91 mechanical characterization at high strain rates is relatively unknown, particularly, in relation to impact joining and also to nuclear accidents. In this study, the mechanical characterization of T91 steel was performed in tension by varying the strain-rate (10-3 up to 104 s-1) and temperature (20-800°C) on dog-bone specimens, using standard testing machines or Hopkinson Bar apparati. As expected, the material is both temperature and strain-rate sensitive and different sets of parameters for the Johnson-Cook strength model were extracted via a numerical inverse procedure, in order to obtain the most suitable set to be used in this field of applications.

  7. Microstructure Characterization and Corrosion Resistance Behavior of New Cobalt-Free Maraging Steel Produced Through ESR Techniques

    NASA Astrophysics Data System (ADS)

    Seikh, Asiful H.; Halfa, Hossam; Baig, Muneer; Khan, Sohail M. A.

    2017-04-01

    In this study, two different grades (M23 and M29) of cobalt-free low nickel maraging steel have been produced through electroslag remelting (ESR) process. The corrosion resistance of these ESR steels was investigated in 1 M H2SO4 solution using linear potentiodynamic polarization (LPP) and electrochemical impedance spectroscopy (EIS) techniques. The experiments were performed for different immersion time and solution temperature. To evaluate the corrosion resistance of the ESR steels, some significant characterization parameters from LPP and EIS curves were analyzed and compared with that of conventional C250 maraging steel. Irrespective of measurement techniques used, the results show that the corrosion resistance of the ESR steels was higher than the C250 steel. The microstructure of ESR steels was composed of uniform and well-distributed martensite accompanied with little amount of retained austenite in comparison with C250 steel.

  8. A Comparison of Concrete and Virtual Manipulative Use in Third- and Fourth-Grade Mathematics

    ERIC Educational Resources Information Center

    Burns, Barbara A.; Hamm, Ellen M.

    2011-01-01

    The primary purpose of this classroom experiment was to examine the effectiveness of concrete (hands-on) manipulatives as compared with virtual (computer-based) manipulatives on student review of fraction concepts in third grade and introduction of symmetry concepts in fourth grade. A pretest-posttest design was employed with a sample of 91

  9. Effect of Ni Addition on Bainite Transformation and Properties in a 2000 MPa Grade Ultrahigh Strength Bainitic Steel

    NASA Astrophysics Data System (ADS)

    Tian, Junyu; Xu, Guang; Jiang, Zhengyi; Hu, Haijiang; Zhou, Mingxing

    2018-05-01

    The effects of Nickle (Ni) addition on bainitic transformation and property of ultrahigh strength bainitic steels are investigated by three austempering processes. The results indicate that Ni addition hinders the isothermal bainite transformation kinetics, and decreases the volume fraction of bainite due to the decrease of chemical driving force for nucleation and growth of bainite transformation. Moreover, the product of tensile strength and total elongation (PSE) of high carbon bainitic steels decreases with Ni addition at higher austempering temperatures (220 and 250 °C), while it shows no significant difference at lower austempering temperature (200 °C). For the same steel (Ni-free or Ni-added steel), the amounts of bainite and RA firstly increase and then decrease with the increase of the austempering temperature, resulting in the highest PSE in the sample austempered at temperature of 220 °C. In addition, the effects of austempering time on bainite amount and property of high carbon bainitic steels are also analyzed. It indicates that in a given transformation time range of 30 h, more volume of bainite and better mechanical property in high carbon bainitic steels can be obtained by increasing the isothermal transformation time.

  10. Frequency of Interferon-Resistance Conferring Substitutions in Amino Acid Positions 70 and 91 of Core Protein of the Russian HCV 1b Isolates Analyzed in the T-Cell Epitopic Context

    PubMed Central

    Soboleva, N. V.; Karlsen, A. A.; Isaeva, O. V.; Isaguliants, M. G.; Mikhailov, M. I.

    2018-01-01

    Amino acid substitutions R70Q/H and L91M in HCV subtype 1b core protein can affect the response to interferon and are associated with the development of hepatocellular carcinoma. We found that the rate of R70Q/H in HCV 1b from Russia was 31.2%, similar to that in HCV strains from Asia (34.0%), higher than that in the European (18.0%, p = 0.0010), but lower than that in the US HCV 1b strains (62.8%, p < 0.0001). Substitution L91M was found in 80.4% of the Russian HCV 1b isolates, higher than in Asian isolates (43.8%, p < 0.0001). Thus, a significant proportion of Russian HCV 1b isolates carry the unfavorable R70Q/H and/or L91M substitution. In silico analysis of the epitopic structure of the regions of substitutions revealed that both harbor clusters of T-cell epitopes. Peptides encompassing these regions were predicted to bind to a panel of HLA class I molecules, with substitutions impairing peptide recognition by HLA I molecules of the alleles prevalent in Russia. This indicates that HCV 1b with R70Q/H and L91M substitutions may have evolved as the immune escape variants. Impairment of T-cell recognition may play a part in the negative effect of these substitutions on the response to IFN treatment. PMID:29577052

  11. The effect of microstructure and strength on the fracture toughness of an 18 Ni, 300 grade maraging steel

    NASA Technical Reports Server (NTRS)

    Psioda, J. A.; Low, J. R., Jr.

    1977-01-01

    Fractography and metallographic sectioning were used to investigate the influence of microstructure and strength on the fracture toughness (KIc) and fracture mechanism of an 18 Ni, 300 grade maraging steel. Increased yield strength from 1442 to 2070 MN/m squared through precipitation hardening results in a KIc loss from 143 to 55 MN/m superscript 3/2. Ti (C,N) Ti2S, and TiC inclusions in sizes from 1 to 8, 1 to 15, and 0.1 to 2 microns respectively serve as sites for void nucleation and lead to fracture by the dimpled rupture process in all strength levels considered. TiC nucleated dimples occupy more than half the fracture in all conditions. Void nucleation rate and resultant number of dimples per unit area of fracture increase with increasing yield strength. Average dimple size decreases with increasing strength and/or overaging which follows from the decreasing amount of stable void growth measured by sectioning tensile specimens. Void growth is assisted by crack branching along a path of TiC inclusions. Coalescence occurs in the highest strength materials by a combination of TiC void nucleation and premature separation at strengthening precipitates.

  12. The influence of assist gas on magnetic properties of electrotechnical steel sheets cut with laser

    NASA Astrophysics Data System (ADS)

    Gaworska-Koniarek, Dominika; Szubzda, Bronisław; Wilczyński, Wiesław; Drosik, Jerzy; Karaś, Kazimierz

    2011-07-01

    The paper presents the influence of assist gas (air and nitrogen) during laser cutting on magnetization, magnetic permeability and loss characteristics of non-oriented electrical steels. The research was made on an non-oriented M330-50A grade electrical steels by means of single sheet tester. In order to enhance the effect of cutting and the same degradation zone on magnetic properties, strips with different width were achieved. Measurements results indicate that application of air as assist gas has more destructive effect on magnetic properties of electrical steels than nitrogen one.

  13. Novel 1.5 GPa-strength with 50%-ductility by transformation-induced plasticity of non-recrystallized austenite in duplex steels.

    PubMed

    Sohn, Seok Su; Song, Hyejin; Jo, Min Chul; Song, Taejin; Kim, Hyoung Seop; Lee, Sunghak

    2017-04-28

    Needs for steel designs of ultra-high strength and excellent ductility have been an important issue in worldwide automotive industries to achieve energy conservation, improvement of safety, and crashworthiness qualities. Because of various drawbacks in existing 1.5-GPa-grade steels, new development of formable cold-rolled ultra-high-strength steels is essentially needed. Here we show a plausible method to achieve ultra-high strengths of 1.0~1.5 GPa together with excellent ductility above 50% by actively utilizing non-recrystallization region and TRansformation-Induced Plasticity (TRIP) mechanism in a cold-rolled and annealed Fe-Mn-Al-C-based steel. We adopt a duplex microstructure composed of austenite and ultra-fine ferrite in order to overcome low-yield-strength characteristics of austenite. Persistent elongation up to 50% as well as ultra-high yield strength over 1.4 GPa are attributed to well-balanced mechanical stability of non-crystallized austenite with critical strain for TRIP. Our results demonstrate how the non-recrystallized austenite can be a metamorphosis in 1.5-GPa-grade steel sheet design.

  14. X-Ray Diffraction Profile Analysis for Characterizing Isothermal Aging Behavior of M250 Grade Maraging Steel

    NASA Astrophysics Data System (ADS)

    Mahadevan, S.; Jayakumar, T.; Rao, B. P. C.; Kumar, Anish; Rajkumar, K. V.; Raj, Baldev

    2008-08-01

    X-ray diffraction (XRD) studies were carried out to characterize aging behavior of M250 grade maraging steel samples subjected to isothermal aging at 755 K for varying durations of 0.25, 1, 3, 10, 40, 70, and 100 hours. Earlier studies had shown typical features of precipitation hardening, wherein the hardness increased to a peak value due to precipitation of intermetallics and decreased upon further aging (overaging) due to reversion of martensite to austenite. Intermetallic precipitates, while coherent, are expected to increase the microstrain in the matrix. Hence, an attempt has been made in the present study to understand the microstructural changes in these samples using XRD line profile analysis. The anisotropic broadening with diffraction angle observed in the simple Williamson Hall (WH) plot has been addressed using the modified WH (mWH) approach, which takes into account the contrast caused by dislocations on line profiles, leading to new scaling factors in the WH plot. The normalized mean square strain and crystallite size estimated from mWH have been used to infer early precipitation and to characterize aging behavior. The normalized mean square strain has been used to determine the Avrami exponent in the Johnson Mehl Avrami (JMA) equation, which deals with the kinetics of precipitation. The Avrami exponent thus determined has matched well with values found by other methods, as reported in literature.

  15. Application of Response Surface Methodology for Modeling of Postweld Heat Treatment Process in a Pressure Vessel Steel ASTM A516 Grade 70.

    PubMed

    Peasura, Prachya

    2015-01-01

    This research studied the application of the response surface methodology (RSM) and central composite design (CCD) experiment in mathematical model and optimizes postweld heat treatment (PWHT). The material of study is a pressure vessel steel ASTM A516 grade 70 that is used for gas metal arc welding. PWHT parameters examined in this study included PWHT temperatures and time. The resulting materials were examined using CCD experiment and the RSM to determine the resulting material tensile strength test, observed with optical microscopy and scanning electron microscopy. The experimental results show that using a full quadratic model with the proposed mathematical model is YTS = -285.521 + 15.706X1 + 2.514X2 - 0.004X1(2) - 0.001X2(2) - 0.029X1X2. Tensile strength parameters of PWHT were optimized PWHT time of 5.00 hr and PWHT temperature of 645.75°C. The results show that the PWHT time is the dominant mechanism used to modify the tensile strength compared to the PWHT temperatures. This phenomenon could be explained by the fact that pearlite can contribute to higher tensile strength. Pearlite has an intensity, which results in increased material tensile strength. The research described here can be used as material data on PWHT parameters for an ASTM A516 grade 70 weld.

  16. Application of Response Surface Methodology for Modeling of Postweld Heat Treatment Process in a Pressure Vessel Steel ASTM A516 Grade 70

    PubMed Central

    Peasura, Prachya

    2015-01-01

    This research studied the application of the response surface methodology (RSM) and central composite design (CCD) experiment in mathematical model and optimizes postweld heat treatment (PWHT). The material of study is a pressure vessel steel ASTM A516 grade 70 that is used for gas metal arc welding. PWHT parameters examined in this study included PWHT temperatures and time. The resulting materials were examined using CCD experiment and the RSM to determine the resulting material tensile strength test, observed with optical microscopy and scanning electron microscopy. The experimental results show that using a full quadratic model with the proposed mathematical model is Y TS = −285.521 + 15.706X 1 + 2.514X 2 − 0.004X 1 2 − 0.001X 2 2 − 0.029X 1 X 2. Tensile strength parameters of PWHT were optimized PWHT time of 5.00 hr and PWHT temperature of 645.75°C. The results show that the PWHT time is the dominant mechanism used to modify the tensile strength compared to the PWHT temperatures. This phenomenon could be explained by the fact that pearlite can contribute to higher tensile strength. Pearlite has an intensity, which results in increased material tensile strength. The research described here can be used as material data on PWHT parameters for an ASTM A516 grade 70 weld. PMID:26550602

  17. Characterization of the austenitic stability of metastable austenitic stainless steel with regard to its formability

    NASA Astrophysics Data System (ADS)

    Schneider, Matthias; Liewald, Mathias

    2018-05-01

    During the last decade, the stainless steel market showed a growing volume of 3-5% p.a.. The austenitic grades are losing market shares to ferritic or 200-series grades due to the high nickel price, but still playing the most important role within the stainless steel market. Austenitic stainless steel is characterized by the strain-induced martensite formation, causing the TRIP-effect (Transformation Induced Plasticity) which is responsible for good formability and high strength. The TRIP-effect itself is highly dependent on the forming temperature, the strain as well as the chemical composition which has a direct influence on the stability of the austenite. Today the austenitic stability is usually characterized by the so called Md30-temperature, which was introduced by Angel and enhanced by several researches, particularly Nohara. It is an empirical formula based on the chemical composition and the grain size of a given material, calculating the temperature which is necessary to gain a 50 % martensite formation after 30 % of elongation in a tensile test. A higher Md30-temperature indicates a lower stability and therefore a higher tendency towards martensite formation. The main disadvantage of Md30 -temperature is the fact that it is not based on forming parameters and only describes a single point instead of the whole forming process. In this paper, an experimental set up for measuring martensite and temperature evolution in a non-isothermal tensile test is presented, which is based on works of Hänsel and Schmid. With this set up, the martensite formation rate for different steels of the steel grade EN 1.4301 and EN 1.4310 is measured. Based on these results a new austenitic stability criterion is defined. This criterion and the determined Md30-temperatures are related to the stretch formability of the materials. The results show that the new IFU criterion is with regard to the formability a much more useful characteristic number for metastable austenitic steels

  18. The Effectiveness of the New 9th Grade Biology Curriculum on Students' Environmental Awareness

    ERIC Educational Resources Information Center

    Cetin, Gulcan; Nisanci, Seda Hilal

    2010-01-01

    The aim of this study was to examine the effectiveness of a new 9th grade biology curriculum on students' environmental awareness. Participants included 91 ninth grade students in a high school in Balikesir during the spring semester of the 2008-2009 academic years. Two classrooms, including 22 and 24 students respectively, were randomly assigned…

  19. "This Is My Best": The Report of Vermont's Writing Assessment Program, Pilot Year 1990-91.

    ERIC Educational Resources Information Center

    Vermont State Dept. of Education, Montpelier.

    A study examined the background, methods, and results of the pilot year of Vermont's Writing Assessment program. Students and teachers from 46 Vermont schools were invited to participate in the 1990-91 pilot year of portfolio assessment. Students in grades 4 and 8 chose samples of their best writing from the school year. Each portfolio was…

  20. Determination of Proper Austenitization Temperatures for Hot Stamping of AISI 4140 Steel

    NASA Astrophysics Data System (ADS)

    Samadian, Pedram; Parsa, Mohammad Habibi; Shakeri, Amid

    2014-04-01

    High strength steels are desirable materials for use in automobile bodies in order to reduce vehicle weight and increase the safety of car passengers, but steel grades with high strength commonly show poor formability. Recently, steels with controlled microstructures and compositions are used to gain adequate strength after hot stamping while maintaining good formability during processing. In this study, microstructure evolutions and changes in mechanical properties of AISI 4140 steel sheets resulting from the hot stamping process at different austenitization temperatures were investigated. To determine the proper austenitization temperatures, the results were compared with those of the cold-worked and cold-worked plus quench-tempered specimens. Comparisons showed that the austenitization temperatures of 1000 and 1100 °C are proper for hot stamping of 3-mm-thick AISI 4140 steel sheets due to the resultant martensitic microstructure which led to the yield and ultimate tensile strength of 1.3 and 2.1 GPa, respectively. Such conditions resulted in more favorable simultaneous strength and elongation than those of hot-stamped conventional boron steels.

  1. DIN 1.7035 Steel Modification with High Intensity Nitrogen Ion Implantation

    NASA Astrophysics Data System (ADS)

    Ryabchikov, A. I.; Sivin, D. O.; Anan'in, P. S.; Ivanova, A. I.; Uglov, V. V.; Korneva, O. S.

    2018-06-01

    The paper presents research results on the formation of deep ion-modified layers of the grade DIN 1.7035 alloy steel due to a high intensity, repetitively-pulsed nitrogen ion beams with the ion current density of up to 0.5 A/cm2. The formation of a low-energy, high intensity nitrogen ion beam is based on a plasma immersion ion extraction followed by the ballistic focusing in the equipotential drift region. The nitrogen ion implantation in steel specimens is performed at a 1.2 keV energy and 450, 500, 580 and 650°C temperatures during 60 minutes. The morphology, elementary composition and mechanical properties are investigated in deep layers of steel specimens alloyed with nitrogen ions.

  2. Metallurgical Examination of a Cast Turret Manufactured by the American Steel Foundries

    DTIC Science & Technology

    1945-03-28

    ferrite and a structure stmlar to tempered bainite tnd fine carb ides. 4. The results of this investigatio l inCicate that the American Steel Foundries...1hirrot No 11Mufac t~redj~ t!Le American~ Steel Poidcries J.J Wil jr;I 4?1 ’JJ No. B171; 11000 Picral Structure simuilar to temnpered bainite Lavsociated wita fine carbides and ferrite patcha.. FIGM I ...examination has been conducted on two samples of the. cast turret to. 3171 for the Hedium Tank II4, maiufactured by the i.meriaan Steel Foundries, which

  3. Study on underclad cracking in nuclear reactor vessel steels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Horiya, T.; Takeda, T.; Yamato, K.

    1985-02-01

    Susceptibility to underclad cracking in nuclear reactor vessel steels, such as SA533 Grade B Class 1 and SA508 Class 2, was studied in detail. A convenient simulation test method using simulated HAZ specimens of small size has been developed for quantitative evaluation of susceptibility to underclad cracks. The method can predict precisely the cracking behavior in weldments of steels with relative low crack susceptibility. The effect of chemical compositions on susceptibility to the cracking was examined systematically using the developed simulation test method and the following index was obtained from the test results: U = 20(V) + 7(C) + 4(Mo)more » + (Cr) + (Cu) - 0.5(Mn) + 1.5 log(X) X = Al . . . Al/2N less than or equal to 1 X = 2N . . . Al/2N > 1 It was confirmed that the new index (U) is useful for the prediction of crack susceptibility of the nuclear vessel steels; i.e., no crack initiation is detected in weldments in the roller bend test for steels having U value below 0.90.« less

  4. The effect of various deformation processes on the corrosion behavior of casing and tubing carbon steels in sweet environment

    NASA Astrophysics Data System (ADS)

    Elramady, Alyaa Gamal

    The aim of this research project is to correlate the plastic deformation and mechanical instability of casing steel materials with corrosion behavior and surface change, in order to identify a tolerable degree of deformation for casing steel materials. While the corrosion of pipeline and casing steels has been investigated extensively, corrosion of these steels in sweet environments with respect to plastic deformation due to bending, rolling, autofrettage, or handling needs more investigation. Downhole tubular expansion of pipes (casings) is becoming standard practice in the petroleum industry to repair damaged casings, shutdown perforations, and ultimately achieve mono-diameter wells. Tubular expansion is a cold-drawing metal forming process, which consists of running conical mandrels through casings either mechanically using a piston or hydraulically by applying a back pressure. This mechanism subjects the pipes to large radial plastic deformations of up to 30 pct. of the inner diameter. It is known that cold-working is a way of strengthening materials such as low carbon steel, but given that this material will be subjected to corrosive environments, susceptibility to stress corrosion cracking (SCC) should be investigated. This research studies the effect of cold-work, in the form of cold-rolling and cold-expansion, on the surface behavior of API 5CT steels when it is exposed to a CO2-containing environment. Cold-work has a pronounced influence on the corrosion behavior of both API 5CT K55 and P110 grade steels. The lowest strength grade steel, API 5CT K55, performed poorly in a corrosive environment in the slow strain rate test. The ductile material exhibited the highest loss in strength and highest susceptibility to stress corrosion cracking in a CO 2-containing environment. The loss in strength declined with cold-rolling, which can be ascribed to the surface compressive stresses induced by cold-work. On the other hand, API 5CT P110 grade steels showed higher

  5. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Section 178.45 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS SPECIFICATIONS... limits. Permanent closures formed by spinning are prohibited. (b) Material, steel. Only open hearth...

  6. Utilization of FEM model for steel microstructure determination

    NASA Astrophysics Data System (ADS)

    Kešner, A.; Chotěborský, R.; Linda, M.; Hromasová, M.

    2018-02-01

    Agricultural tools which are used in soil processing, they are worn by abrasive wear mechanism cases by hard minerals particles in the soil. The wear rate is influenced by mechanical characterization of tools material and wear rate is influenced also by soil mineral particle contents. Mechanical properties of steel can be affected by a technology of heat treatment that it leads to a different microstructures. Experimental work how to do it is very expensive and thanks to numerical methods like FEM we can assumed microstructure at low cost but each of numerical model is necessary to be verified. The aim of this work has shown a procedure of prediction microstructure of steel for agricultural tools. The material characterizations of 51CrV4 grade steel were used for numerical simulation like TTT diagram, heat capacity, heat conduction and other physical properties of material. A relationship between predicted microstructure by FEM and real microstructure after heat treatment shows a good correlation.

  7. Effect of Cyclic Thermal Process on Ultrafine Grain Formation in AISI 304L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Ravi Kumar, B.; Mahato, B.; Sharma, Sailaja; Sahu, J. K.

    2009-12-01

    As-received hot-rolled commercial grade AISI 304L austenitic stainless steel plates were solution treated at 1060 °C to achieve chemical homogeneity. Microstructural characterization of the solution-treated material revealed polygonal grains of about 85- μm size along with annealing twins. The solution-treated plates were heavily cold rolled to about 90 pct of reduction in thickness. Cold-rolled specimens were then subjected to thermal cycles at various temperatures between 750 °C and 925 °C. X-ray diffraction showed about 24.2 pct of strain-induced martensite formation due to cold rolling of austenitic stainless steel. Strain-induced martensite formed during cold rolling reverted to austenite by the cyclic thermal process. The microstructural study by transmission electron microscope of the material after the cyclic thermal process showed formation of nanostructure or ultrafine grain austenite. The tensile testing of the ultrafine-grained austenitic stainless steel showed a yield strength 4 to 6 times higher in comparison to its coarse-grained counterpart. However, it demonstrated very poor ductility due to inadequate strain hardenability. The poor strain hardenability was correlated with the formation of strain-induced martensite in this steel grade.

  8. Yb-fibre Laser Welding of 6 mm Duplex Stainless Steel 2205

    NASA Astrophysics Data System (ADS)

    Bolut, M.; Kong, C. Y.; Blackburn, J.; Cashell, K. A.; Hobson, P. R.

    Duplex stainless steel (DSS) is one of the materials of choice for structural and nuclear applications, having high strength and good corrosion resistance when compared with other grades of stainless steel. The welding process used to join these materials is critical as transformation of the microstructure during welding directly affects the material properties. High power laser welding has recently seen an increase in research interest as it offers both speed and flexibility. This paper presents an investigation into the important parameters affecting laser welding of DSS grade 2205, with particular focus given to the critical issue of phase transformation during welding. Bead-on-plate melt-run trials without filler material were performed on 6mm thick plates using a 5 kW Yb-fibre laser. The laser beam was characterized and a Design of Experiment approach was used to quantify the impact of the process parameters. Optical metallographic methods were used to examine the resulting microstructures.

  9. Rapid Thermal Processing to Enhance Steel Toughness.

    PubMed

    Judge, V K; Speer, J G; Clarke, K D; Findley, K O; Clarke, A J

    2018-01-11

    Quenching and Tempering (Q&T) has been utilized for decades to alter steel mechanical properties, particularly strength and toughness. While tempering typically increases toughness, a well-established phenomenon called tempered martensite embrittlement (TME) is known to occur during conventional Q&T. Here we show that short-time, rapid tempering can overcome TME to produce unprecedented property combinations that cannot be attained by conventional Q&T. Toughness is enhanced over 43% at a strength level of 1.7 GPa and strength is improved over 0.5 GPa at an impact toughness of 30 J. We also show that hardness and the tempering parameter (TP), developed by Holloman and Jaffe in 1945 and ubiquitous within the field, is insufficient for characterizing measured strengths, toughnesses, and microstructural conditions after rapid processing. Rapid tempering by energy-saving manufacturing processes like induction heating creates the opportunity for new Q&T steels for energy, defense, and transportation applications.

  10. Evaluation of Lumbar Intervertebral Disc Degeneration Using T1ρ and T2 Magnetic Resonance Imaging in a Rabbit Disc Injury Model.

    PubMed

    Ishikawa, Tetsuhiro; Watanabe, Atsuya; Kamoda, Hiroto; Miyagi, Masayuki; Inoue, Gen; Takahashi, Kazuhisa; Ohtori, Seiji

    2018-04-01

    An in vivo histologic and magnetic resonance imaging (MRI) study of lumbar intervertebral disc (IVD) degeneration was conducted. To clarify the sensitivity and efficacy of T1ρ/T2 mapping for IVD degeneration, the correlation between T1ρ/T2 mapping and degenerative grades and histological findings in the lumbar IVD were investigated. The early signs of IVD degeneration are proteoglycan loss, dehydration, and collagen degradation. Recently, several quantitative MRI techniques have been developed; T2 mapping can be used to evaluate hydration and collagen fiber integrity within cartilaginous tissue, and T1ρ mapping can be used to evaluate hydration and proteoglycan content. Using New Zealand White rabbits, annular punctures of the IVD were made 10 times at L2/3, 5 times at L3/4, and one time at L4/5 using an 18-gauge needle (n=6) or a 21-gauge needle (n=6). At 4 and 8 weeks post-surgery, MRI was performed including T1ρ and T2 mapping. The degree of IVD degeneration was macroscopically assessed using the Thompson grading system. All specimens were cut for hematoxylin and eosin, safranin-O, and toluidine blue staining. Disc degeneration became more severe as the number of punctures increased and when the larger needle was used. T1ρ and T2 values were significantly different between grade 1 and grade 3 IVDs, grade 1 and grade 4 IVDs, grade 2 and grade 3 IVDs, and grade 2 and grade 4 IVDs ( p <0.05). There was a significant difference between grade 1 and grade 2 IVDs only in terms of T1ρ values ( p <0.05). T1ρ and T2 quantitative MRI could detect these small differences. Our results suggest that T1ρ and T2 mapping are sensitive to degenerative changes of lumbar IVDs and that T1ρ mapping can be used as a clinical tool to identify early IVD degeneration.

  11. A microstructural comparison of two nuclear-grade martensitic steels using small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Coppola, R.; Fiori, F.; Little, E. A.; Magnani, M.

    1997-06-01

    Results are presented of a small-angle neutron scattering (SANS) study on two 10-13% Cr martensitic stainless steels of interest for nuclear applications, viz. DIN 1.4914 (MANET specification, for fusion reactors) and AISI 410. The investigation has focussed principally on microstructural effects associated with the differences in chromium content between the two alloys. The size distribution functions determined from nuclear and magnetic SANS components for the two steels given identical heat treatments are in accord with an interpretation based on the presence of ˜ 1 nm size CCr aggregates in the microstructure. Much larger (˜ 10 nm) scattering inhomogeneities with different magnetic contrast are also present and tentatively identified as carbides.

  12. The Effect of Different Delivery Conditions on the Accelerated Degradation of Structural Steel in the Coal Mine Environment / Wpływ Różnego Stanu Dostawy Na Przyspieszoną Degradację Stali Konstrukcyjnej W Środowisku Kopalnianym

    NASA Astrophysics Data System (ADS)

    Pawłowski, Bogdan; Bała, Piotr

    2012-12-01

    The main objective of this work was to determine the effect of different delivery conditions on the accelerated degradation of structural steels used for lifting beams (rails) of the monorail transport systems. Some of these rails, made of the same steel grade as others, undergoes accelerated corrosion in the coal mine environment. Corrosion degradation occurs much faster (more than two times faster), comparing to the same steel grade rails operated under the same conditions but with different microstructures. However, all the provided rails meet the requirements of appropriate standards for steel on the lifting beams of the monorail transport systems. The investigations were carried out on rails made of the same steel grade but with different microstructures and showed that the main factor influencing the accelerated corrosion degradation of tested steels is the delivery condition, so-called "as rolled" condition. The greatest resistance to the accelerated corrosion showed rails in the normalized or normalizing rolling condition.

  13. Microstructure, Hardness, and Residual Stress Distributions in T-Joint Weld of HSLA S500MC Steel

    NASA Astrophysics Data System (ADS)

    Frih, Intissar; Montay, Guillaume; Adragna, Pierre-Antoine

    2017-03-01

    This paper investigates the characterization of the microstructure, hardness, and residual stress distributions of MIG-welded high-strength low-alloy S500MC steel. The T-joint weld for 10-mm-thick plates was joined using a two passes MIG welding technology. The contour method was performed to measure longitudinal welding residual stress. The obtained results highlighted a good correlation between the metallurgical phase constituents and hardness distribution within the weld zones. In fact, the presence of bainite and smaller ferrite grain size in the weld-fusion zone might be the reason for the highest hardness measured in this region. A similar trend of the residual stress and hardness distributions was also obtained.

  14. Nuclear reactor containment structure with continuous ring tunnel at grade

    DOEpatents

    Seidensticker, Ralph W.; Knawa, Robert L.; Cerutti, Bernard C.; Snyder, Charles R.; Husen, William C.; Coyer, Robert G.

    1977-01-01

    A nuclear reactor containment structure which includes a reinforced concrete shell, a hemispherical top dome, a steel liner, and a reinforced-concrete base slab supporting the concrete shell is constructed with a substantial proportion thereof below grade in an excavation made in solid rock with the concrete poured in contact with the rock and also includes a continuous, hollow, reinforced-concrete ring tunnel surrounding the concrete shell with its top at grade level, with one wall integral with the reinforced concrete shell, and with at least the base of the ring tunnel poured in contact with the rock.

  15. Phase-field modelling of microstructure formation during the solidification of continuously cast low carbon and HSLA steels

    NASA Astrophysics Data System (ADS)

    Böttger, B.; Apel, M.; Santillana, B.; Eskin, D. G.

    2012-07-01

    Cracking in continuous casting of steels has been one of the main problems for decades. Many of the cracks that occur during solidification are hot tears. To better understand the factors leading to this defect, microstructure formation is simulated for a low carbon (LCAK) and two high strength low alloyed (HSLA) steel grades during the initial stage of the process where the first solidified shell is formed inside the mould and where breakouts typically occur. 2D simulation is performed using the multiphase-field software MICRESS [1], which is coupled to the thermodynamic database TCFE6 [2] and the mobility database MOB2 [2], taking into account all elements which may have a relevant effect on the mechanical properties and structure formation during or subsequent to solidification. The use of a moving-frame boundary condition allows travelling through the entire solidification history starting from the slab surface, and tracking the morphology changes during growth of the shell. A heterogeneous nucleation model is included to permit the description of morphological transitions between the initial solidification and the subsequent columnar growth region. Furthermore, a macroscopic one-dimensional temperature solver is integrated to account for the transient and nonlinear temperature field during the initial stage of continuous casting. The external heat flux boundary conditions for this process were derived from thermal process data of the industrial slab caster. The simulation results for the three steel grades have been validated by thickness measurements of breakout shells and microstructure observation of the corresponding grades. Furthermore, the primary dendrite spacing has been measured across the whole thickness of the shell and compared with the simulated microstructures. Significant microstructure differences between the steel grades are discussed and correlated with their hot-cracking behavior.

  16. 40 CFR 91.603 - Applicability of part 91, subpart F.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... violations of the Clean Air Act and the regulations thereunder. (Authorized Company Representative.) (9.... 91.603 Section 91.603 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... representative of the manufacturer: This report is submitted pursuant to Sections 213 and 208 of the Clean Air...

  17. 40 CFR 91.603 - Applicability of part 91, subpart F.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... violations of the Clean Air Act and the regulations thereunder. (Authorized Company Representative.) (9.... 91.603 Section 91.603 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... representative of the manufacturer: This report is submitted pursuant to Sections 213 and 208 of the Clean Air...

  18. 40 CFR 91.603 - Applicability of part 91, subpart F.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... violations of the Clean Air Act and the regulations thereunder. (Authorized Company Representative.) (9.... 91.603 Section 91.603 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... representative of the manufacturer: This report is submitted pursuant to Sections 213 and 208 of the Clean Air...

  19. Corrosion-induced release of the main alloying constituents of manganese-chromium stainless steels in different media.

    PubMed

    Herting, Gunilla; Wallinder, Inger Odnevall; Leygraf, Christofer

    2008-09-01

    The main focus of this paper is the assessment of release rates of chromium, nickel, iron and manganese from manganese-chromium stainless steel grades of low nickel content. The manganese content varied between 9.7 and 1.5 wt% and the corresponding nickel content between 1 and 5 wt%. All grades were exposed to artificial rain and two were immersed in a synthetic body fluid of similar pH but of different composition and exposure conditions. Surface compositional studies were performed using X-ray photoelectron spectroscopy (XPS) in parallel to correlate the metal release process with changes in surface oxide properties. All grades, independent of media, revealed a time-dependent metal release process with a preferential low release of iron and manganese compared to nickel and chromium while the chromium content of the surface oxide increased slightly. Manganese was detected in the surface oxide of all grades, except the grade of the lowest manganese bulk content. No nickel was observed in the outermost surface oxide. Stainless steel grades of the lowest chromium content (approximately 16 wt%) and highest manganese content (approximately 7-9 wt%), released the highest quantity of alloy constituents in total, and vice versa. No correlation was observed between the release rate of manganese and the alloy composition. Released main alloy constituents were neither proportional to the bulk alloy composition nor to the surface oxide composition.

  20. Preoperative grading of supratentorial gliomas using high or standard b-value diffusion-weighted MR imaging at 3T.

    PubMed

    Cihangiroglu, M M; Ozturk-Isik, E; Firat, Z; Kilickesmez, O; Ulug, A M; Ture, U

    2017-03-01

    The goal of this study was to compare diffusion-weighted magnetic resonance imaging (DW-MRI) using high b-value (b=3000s/mm 2 ) to DW-MRI using standard b-value (b=1000s/mm 2 ) in the preoperative grading of supratentorial gliomas. Fifty-three patients with glioma had brain DW-MRI at 3T using two different b-values (b=1000s/mm 2 and b=3000s/mm 2 ). There were 35 men and 18 women with a mean age of 40.5±17.1 years (range: 18-79 years). Mean, minimum, maximum, and range of apparent diffusion coefficient (ADC) values for solid tumor ROIs (ADC mean , ADC min , ADC max , and ADC diff ), and the normalized ADC (ADC ratio ) were calculated. A Kruskal-Wallis statistic with Bonferroni correction for multiple comparisons was applied to detect significant ADC parameter differences between tumor grades by including or excluding 19 patients with an oligodendroglioma. Receiver operating characteristic curve analysis was conducted to define appropriate cutoff values for grading gliomas. No differences in ADC derived parameters were found between grade II and grade III gliomas. Mean ADC values using standard b-value were 1.17±0.27×10 -3 mm 2 /s [range: 0.63-1.61], 1.05±0.22×10 -3 mm 2 /s [range: 0.73-1.33], and 0.86±0.23×10 -3 mm 2 /s [range: 0.52-1.46] for grades II, III and IV gliomas, respectively. Using high b-value, mean ADC values were 0.89±0.24×10 -3 mm 2 /s [range: 0.42-1.25], 0.82±0.20×10 -3 mm 2 /s [range: 0.56-1.10], and 0.59±0.17×10 -3 mm 2 /s [range: 0.40-1.01] for grades II, III and IV gliomas, respectively. ADC mean , ADC ratio , ADC max , and ADC min were different between grade II and grade IV gliomas at both standard and high b-values. Differences in ADC mean , ADC max , and ADC diff were found between grade III and grade IV only using high b-value. ADC parameters derived from DW-MRI using a high b-value allows a better differential diagnosis of gliomas, especially for differentiating grades III and IV, than those derived from DW-MRI using a standard

  1. Selection of Wire Electrical Discharge Machining Process Parameters on Stainless Steel AISI Grade-304 using Design of Experiments Approach

    NASA Astrophysics Data System (ADS)

    Lingadurai, K.; Nagasivamuni, B.; Muthu Kamatchi, M.; Palavesam, J.

    2012-06-01

    Wire electrical discharge machining (WEDM) is a specialized thermal machining process capable of accurately machining parts of hard materials with complex shapes. Parts having sharp edges that pose difficulties to be machined by the main stream machining processes can be easily machined by WEDM process. Design of Experiments approach (DOE) has been reported in this work for stainless steel AISI grade-304 which is used in cryogenic vessels, evaporators, hospital surgical equipment, marine equipment, fasteners, nuclear vessels, feed water tubing, valves, refrigeration equipment, etc., is machined by WEDM with brass wire electrode. The DOE method is used to formulate the experimental layout, to analyze the effect of each parameter on the machining characteristics, and to predict the optimal choice for each WEDM parameter such as voltage, pulse ON, pulse OFF and wire feed. It is found that these parameters have a significant influence on machining characteristic such as metal removal rate (MRR), kerf width and surface roughness (SR). The analysis of the DOE reveals that, in general the pulse ON time significantly affects the kerf width and the wire feed rate affects SR, while, the input voltage mainly affects the MRR.

  2. The effects of a common stainless steel orthodontic bracket on the diagnostic quality of cranial and cervical 3T- MR images: a prospective, case-control study.

    PubMed

    Cassetta, Michele; Pranno, Nicola; Stasolla, Alessandro; Orsogna, Nicola; Fierro, Davide; Cavallini, Costanza; Cantisani, Vito

    2017-08-01

    To evaluate the effect of orthodontic stainless steel brackets and two different types of archwires on the diagnostic quality of 3-T MR images. This prospective, case-control study was conducted following Strengthening the Reporting of Observational Studies in Epidemiology guidelines. The recruitment was conducted among orthodontic patients. 80 subjects, requiring MRI for the presence of temporomandibular disorders, were enrolled and divided into four groups: 20 patients using aligners (control group); 20 patients with stainless steel brackets without archwires; 20 patients with stainless steel brackets and nickel-titanium archwires; and 20 patients with stainless steel brackets and stainless steel archwires. Two experts in neuroradiology evaluated the images to determine the amount of distortion in 6 regions and 48 districts. A score was subjectively assigned according to a modified receiver operating characteristic method of distortion classification. Any disagreement was resolved through consensus seeking; when this was not possible, a third neuroradiologist was consulted. The following statistical methods were used: descriptive statistics, Cohen's kappa coefficient (k), Kruskal-Wallis test, pairwise comparisons using the Dunn-Bonferroni approach. The significance was set at p ≤ 0.05. The presence of stainless steel brackets with or without archwires negatively influenced MRI of the cervical region, paranasal sinuses, head and neck region, and cervical vertebrae but did not influence MRI of brain and temporomandibular joint regions. Patients with a stainless steel multibracket orthodontic appliance should remove it before cervical vertebrae, cervical region, paranasal sinuses, and head and neck MRI scans. The brain and temporomandibular joint region MRI should not require the removal of such appliances.

  3. Identification of the Propionicin F Bacteriocin Immunity Gene (pcfI) and Development of a Food-Grade Cloning System for Propionibacterium freudenreichii▿ †

    PubMed Central

    Brede, Dag Anders; Lothe, Sheba; Salehian, Zhian; Faye, Therese; Nes, Ingolf F.

    2007-01-01

    This report describes the first functional analysis of a bacteriocin immunity gene from Propionibacterium freudenreichii and its use as a selection marker for food-grade cloning. Cloning of the pcfI gene (previously orf5 [located as part of the pcfABC propionicin F operon]) rendered the sensitive host 1,000-fold more tolerant to the propionicin F bacteriocin. The physiochemical properties of the 127-residue large PcfI protein resemble those of membrane-bound immunity proteins from bacteriocin systems found in lactic acid bacteria. The high level of immunity conferred by pcfI allowed its use as a selection marker for plasmid transformation in P. freudenreichii. Electroporation of P. freudenreichii IFO12426 by use of the pcfI expression plasmid pSL102 and propionicin F selection (200 bacteriocin units/ml) yielded 107 transformants/μg DNA. The 2.7-kb P. freudenreichii food-grade cloning vector pSL104 consists of the pLME108 replicon, a multiple cloning site, and pcfI expressed from the constitutive PpampS promoter for selection. The pSL104 vector efficiently facilitated cloning of the propionicin T1 bacteriocin in P. freudenreichii. High-level propionicin T1 production (640 BU/ml) was obtained with the IFO12426 strain, and the food-grade propionicin T1 expression plasmid pSL106 was maintained by ∼91% of the cells over 25 generations in the absence of selection. To the best of our knowledge this is the first report of an efficient cloning system that facilitates the generation of food-grade recombinant P. freudenreichii strains. PMID:17933941

  4. Delta-Ferrite Distribution in a Continuous Casting Slab of Fe-Cr-Mn Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Cheng, Guoguang

    2017-10-01

    The delta-ferrite distribution in a continuous casting slab of Fe-Cr-Mn stainless steel grade (200 series J4) was analyzed. The results showed that the ferrite fraction was less than 3 pct. The "M" type distribution was observed in the thickness direction. For the distribution at the centerline, the maximum ferrite content was found in the triangular zone of the macrostructure. In addition, in this zone, the carbon and sulfur were severely segregated. Furthermore, an equilibrium solidification calculation by Thermo-Calc® software indicates that the solidification mode of the composition in this triangular zone is the same as the solidification mode of the averaged composition, i.e., the FA (ferrite-austenite) mode. None of the nickel-chromium equivalent formulas combined with the Schaeffler-type diagram could predict the ferrite fraction of the Cr-Mn stainless steel grade in a reasonable manner. The authors propose that more attention should be paid to the development of prediction models for the ferrite fraction of stainless steels under continuous casting conditions.

  5. Development of Low Alloy Ti-B Steels for High Temperature Service Applications

    DTIC Science & Technology

    1952-04-01

    Ti-B steels . Ordinarily, martensite or a hardened acicular ferrite structure in steel is associated with extremely low creep strength. However, the...12000 F. The ability of the Ti-B sheet steels to suppress the ferrite transformation to the martensite or lower bainite temperature range upon air...APPROVED FOR PUBLIC mEESX_ DISTRIBUTION UNjfljarT, • WJADC TECHNICAL REPORT 52-77 DEVELOPMENT OF LOW ALLOY Ti-B STEELS FOR HIGH TEMPERATURE SERVICE

  6. Difference in metallic wear distribution released from commercially pure titanium compared with stainless steel plates.

    PubMed

    Krischak, G D; Gebhard, F; Mohr, W; Krivan, V; Ignatius, A; Beck, A; Wachter, N J; Reuter, P; Arand, M; Kinzl, L; Claes, L E

    2004-03-01

    Stainless steel and commercially pure titanium are widely used materials in orthopedic implants. However, it is still being controversially discussed whether there are significant differences in tissue reaction and metallic release, which should result in a recommendation for preferred use in clinical practice. A comparative study was performed using 14 stainless steel and 8 commercially pure titanium plates retrieved after a 12-month implantation period. To avoid contamination of the tissue with the elements under investigation, surgical instruments made of zirconium dioxide were used. The tissue samples were analyzed histologically and by inductively coupled plasma atomic emission spectrometry (ICP-AES) for accumulation of the metals Fe, Cr, Mo, Ni, and Ti in the local tissues. Implant corrosion was determined by the use of scanning electron microscopy (SEM). With grades 2 or higher in 9 implants, steel plates revealed a higher extent of corrosion in the SEM compared with titanium, where only one implant showed corrosion grade 2. Metal uptake of all measured ions (Fe, Cr, Mo, Ni) was significantly increased after stainless steel implantation, whereas titanium revealed only high concentrations for Ti. For the two implant materials, a different distribution of the accumulated metals was found by histological examination. Whereas specimens after steel implantation revealed a diffuse siderosis of connective tissue cells, those after titanium exhibited occasionally a focal siderosis due to implantation-associated bleeding. Neither titanium- nor stainless steel-loaded tissues revealed any signs of foreign-body reaction. We conclude from the increased release of toxic, allergic, and potentially carcinogenic ions adjacent to stainless steel that commercially pure Ti should be treated as the preferred material for osteosyntheses if a removal of the implant is not intended. However, neither material provoked a foreign-body reaction in the local tissues, thus cpTi cannot be

  7. What We Talk about When We Don't Talk about Grades

    ERIC Educational Resources Information Center

    O'Connor, John S.; Lessing, Avi D.

    2017-01-01

    In this article, John O'Connor and Avi Lessing discuss their decision to create gradeless classrooms. They reached this decision by witnessing the profound cost grades hold for students and teachers alike. Grades threaten to reduce students to mere scores and teachers to bookkeepers, both groups focused more on grades than learning. By eliminating…

  8. Correlation study between facet joint cartilage and intervertebral discs in early lumbar vertebral degeneration using T2, T2* and T1ρ mapping

    PubMed Central

    Zhang, Yi; Hu, Jianzhong; Duan, Chunyue; Hu, Ping; Lu, Hongbin; Peng, Xianjing

    2017-01-01

    Recent advancements in magnetic resonance imaging have allowed for the early detection of biochemical changes in intervertebral discs and articular cartilage. Here, we assessed the feasibility of axial T2, T2* and T1ρ mapping of the lumbar facet joints (LFJs) to determine correlations between cartilage and intervertebral discs (IVDs) in early lumbar vertebral degeneration. We recruited 22 volunteers and examined 202 LFJs and 101 IVDs with morphological (sagittal and axial FSE T2-weighted imaging) and axial biochemical (T2, T2* and T1ρ mapping) sequences using a 3.0T MRI scanner. IVDs were graded using the Pfirrmann system. Mapping values of LFJs were recorded according to the degeneration grades of IVDs at the same level. The feasibility of T2, T2* and T1ρ in IVDs and LFJs were analyzed by comparing these mapping values across subjects with different rates of degeneration using Kruskal-Wallis tests. A Pearson’s correlation analysis was used to compare T2, T2* and T1ρ values of discs and LFJs. We found excellent reproducibility in the T2, T2* and T1ρ values for the nucleus pulposus (NP), anterior and posterior annulus fibrosus (PAF), and LFJ cartilage (intraclass correlation coefficients 0.806–0.955). T2, T2* and T1ρ mapping (all P<0.01) had good Pfirrmann grade performances in the NP with IVD degeneration. LFJ T2* values were significantly different between grades I and IV (PL = 0.032, PR = 0.026), as were T1ρ values between grades II and III (PL = 0.002, PR = 0.006) and grades III and IV (PL = 0.006, PR = 0.001). Correlations were moderately negative for T1ρ values between LFJ cartilage and NP (rL = −0.574, rR = −0.551), and between LFJ cartilage and PAF (rL = −0.551, rR = −0.499). T1ρ values of LFJ cartilage was weakly correlated with T2 (r = 0.007) and T2* (r = −0.158) values. Overall, we show that axial T1ρ effectively assesses early LFJ cartilage degeneration. Using T1ρ analysis, we propose a link between LFJ degeneration and IVD NP or

  9. Steel skin - SMC laminate structures for lightweight automotive manufacturing

    NASA Astrophysics Data System (ADS)

    Quagliato, Luca; Jang, Changsoon; Murugesan, Mohanraj; Kim, Naksoo

    2017-09-01

    In the present research work an innovative material, made of steel skin and sheet molding compound core, is presented and is aimed to be utilized for the production of automotive body frames. For a precise description of the laminate structure, the material properties of all the components, including the adhesive utilized as an interlayer, have been carried out, along with the simple tension test of the composite material. The result have shown that the proposed laminate structure has a specific yield strength 114% higher than 6061 T6 aluminum, 34% higher than 7075 T6 aluminum, 186% higher than AISI 304 stainless steel (30HRC) and 42% than SK5 high-strength steel (52HRC), showing its reliability and convenience for the realization of automotive components. After calibrating the material properties of the laminate structure, and utilizing as reference the simple tension results of the laminate structure, the derived material properties have been utilized for the simulation of the mechanical behavior of an automotive B-pillar. The results have been compared with those of a standard B-pillar made of steel, showing that the MS-SMC laminate structure manifests load and impact carry capacity comparable with those of high strength steel, while granting, at least, an 11% weight reduction.

  10. Effect of thermal exposure in helium on mechanical properties and microstructure of 316L and P91

    NASA Astrophysics Data System (ADS)

    Kunzova, Klara; Berka, Jan; Siegl, Jan; Hausild, Petr

    2016-04-01

    In this paper, the effects of high temperature exposure in air as well as in impure He on mechanical properties of 316L and P91 steels were investigated. The experimental programme was part of material design of new experimental facility - high temperature helium loop. Some of the specimens were exposed in air at 750 °C for up to 1000 h. Another set of specimens were exposed in impure helium containing 1 ppmv CO2, 2 ppmv O2, 35 ppmv CH4, 250 ppmv CO and 400 ppmv H2 at 750 °C for up to 1000 h. Metalographical analysis, tensile tests, fracture toughness and hardness tests of exposed and non-exposed specimens were carried out. After the exposure both in air and He, the ultimate tensile strength of P91 decreased significantly more than that of 316L. After the exposure in He, the fracture toughness of 316L was reduced to 60% while fracture toughness of P91 showed no significant changes. The hardness of P91 decreased with exposure time in air. The measurement of the hardness of 316L was very scattered the most probably due to the heterogeneities in microstructure, the trend was not possible to evaluate.

  11. Steel selection for UBC steel bridge

    NASA Astrophysics Data System (ADS)

    Liu, Haoyu

    2018-03-01

    This report conducts a material selection of different types of steel for UBC Steel Bridge Team. I am a third-year material engineering student, so the result from this material selection can only be taken into consideration but not fully adopted. As part of my academic journey, it is possible for technical mistakes in this material selection process. The mechanic properties are the most effective category of properties, making it necessary to be justified from the steel bridge design and chosen in accordance with the objective of the team. An introduction for currently-used steel properties and the expected steel properties is provided. The examination focus on how different alloy compositions of steel changes its properties. The properties of the steel are examined in three main aspects: hardness, strength, and toughness. The results suggest that more nickel, manganese, and chromium in the steel provide better steel for the team to use. Further research is needed if a more precise material selection is required.

  12. Constitutive equations for multiphase TRIP steels at high rates of strain

    NASA Astrophysics Data System (ADS)

    van Slycken, J.; Verleysen, P.; Degrieck, J.; Bouquerel, J.

    2006-08-01

    Multiphase TRansformation Induced Plasticity (TRIP) steels show an excellent combination of high strength and high strain values, making them ideally suited for use in vehicle body structures. A complex synergy of three different phases (ferrite, bainite and austenite) on the one hand, and the meta-stable character of the austenite on the other hand, give the material indeed a high energy absorption potential. The knowledge and understanding of the dynamic behaviour of these sheet steels is essential to investigate the impact-dynamic characteristics of the structures. Therefore split Hopkinson tensile tests are performed in a strain rate range of 500 to 2000 s-1. Three TRIP steel grades with a different Al and Si content were studied. The experimental results show that these steels preserve their excellent shock-absorbing properties in dynamic conditions. The typical high strain rate loading conditions and the complex behaviour of TRIP steels offer a unique investigation opportunity. This behaviour can be described with phenomenological material models that can be used for numerical simulations of car crashes. The Johnson-Cook model, a frequently used model in finite element codes, is well-suited to describe the dynamic behaviour of the investigated TRIP steels. This model is compared to the Rusinek-Klepaczko model.

  13. On the Processing of Martensitic Steels in Continuous Galvanizing Lines: Part 1

    NASA Astrophysics Data System (ADS)

    Song, Taejin; Kwak, Jaihyun; de Cooman, B. C.

    2012-01-01

    Whereas low-carbon (<0.2 mass pct) martensitic grades can be produced easily in continuous annealing processing lines equipped with the required cooling capacity, the thermal cycles in continuous galvanizing lines make it difficult to produce hot-dip Zn or Zn-alloy coated high-strength martensitic grades. This is because of the tempering processes occurring during dipping of the strip in the liquid Zn bath and, in the case of galvannealed sheet steel, the short thermal treatment required to achieve the alloying between the Zn and the steel. These short additional thermal treatments last less than 30 seconds but severely degrade the mechanical properties. Using a combination of internal friction, X-ray diffraction, and transmission electron microscopy, it is shown that the ultrafine-grained lath microstructure allows for a rapid dislocation recovery and carbide formation during the galvanizing processes. In addition, the effective dislocation pinning occurring during the galvannealing process results in strain localization and the suppression of strain hardening.

  14. Effects of Testing Method on Stretch-Flangeability of Dual-Phase 980/1180 Steel Grades

    NASA Astrophysics Data System (ADS)

    Madrid, Mykal; Van Tyne, Chester J.; Sadagopan, Sriram; Pavlina, Erik J.; Hu, Jun; Clarke, Kester D.

    2018-04-01

    Challenging fuel economy and safety standards in the automotive industry have led to the need for materials with higher strength while maintaining levels of formability that meet component manufacturing requirements. Advanced high-strength steels, such as dual-phase steels with tensile strengths of 980 MPa and 1180 MPa, are of interest to address this need. Increasing the strength of these materials typically comes at the expense of ductility, which may result in problems when stamping parts with trimmed or sheared edges, as cracking at the sheared edge may occur at lower strains. Here, hole expansion tests were performed with different punch geometries (conical and flat-bottom) and different edge conditions (sheared and machined) to understand the effects of testing conditions on performance, and these results are discussed in terms of mechanical properties and microstructures.

  15. Effects of Testing Method on Stretch-Flangeability of Dual-Phase 980/1180 Steel Grades

    NASA Astrophysics Data System (ADS)

    Madrid, Mykal; Van Tyne, Chester J.; Sadagopan, Sriram; Pavlina, Erik J.; Hu, Jun; Clarke, Kester D.

    2018-06-01

    Challenging fuel economy and safety standards in the automotive industry have led to the need for materials with higher strength while maintaining levels of formability that meet component manufacturing requirements. Advanced high-strength steels, such as dual-phase steels with tensile strengths of 980 MPa and 1180 MPa, are of interest to address this need. Increasing the strength of these materials typically comes at the expense of ductility, which may result in problems when stamping parts with trimmed or sheared edges, as cracking at the sheared edge may occur at lower strains. Here, hole expansion tests were performed with different punch geometries (conical and flat-bottom) and different edge conditions (sheared and machined) to understand the effects of testing conditions on performance, and these results are discussed in terms of mechanical properties and microstructures.

  16. Utility of early dynamic and delayed post-diuretic 18F-FDG PET/CT SUVmax in predicting tumour grade and T-stage of urinary bladder carcinoma: results from a prospective single centre study.

    PubMed

    Sharma, Abhishek; Mete, Uttam K; Sood, Ashwani; Kakkar, Nandita; Gorla, Arun K R; Mittal, Bhagwant R

    2017-04-01

    Accurate pre-treatment grading and staging of bladder cancer are vital for better therapeutic decision and prognosis. The aim of the present study was to evaluate the correlation between maximum standardized uptake value (SUV max ) calculated during early dynamic and post-diuretic fluorine-18 fludeoxyglucose ( 18 F-FDG) positron emission tomography (PET)/CT studies with grade and pT-stage of bladder cancer. 39 patients with suspected/proven bladder carcinoma underwent 10-min early dynamic pelvic imaging and delayed post-diuretic whole-body FDG PET/CT imaging. SUV max of the lesions derived from both studies was compared with grade and pT-stage. Relationship of SUV max with grade and pT-stage was analyzed using independent sample t-test and analysis of variance. SUV max of the early dynamic imaging showing tumour perfusion was independent from the SUV max of delayed imaging. High-grade tumours showed higher SUV max than low-grade tumours in the early dynamic imaging (5.4 ± 1.4 vs 4.7 ± 1.6; p-value 0.144) with statistically significant higher value in Stage pT1 tumours (6.8 ± 0.8 vs 5.5 ± 1.2; p-value 0.04). Non-invasive pTa tumours had significantly less SUV max than higher stage tumours during early dynamic imaging [F(4,29) = 6.860, p 0.001]. Early dynamic imaging may have a role in predicting the grade and aggressiveness of the bladder tumours and thus can help in treatment planning and prognostication. Advances in knowledge: Dynamic PET/CT is a limitedly explored imaging technique. This prospective pilot study demonstrates the utility of this modality as a potential adjunct to standard FDG PET/CT imaging in predicting the grade and aggressiveness of the bladder tumours and thus can impact the patient management.

  17. Microstructure and properties of aluminium-aluminium oxide graded composite materials

    NASA Astrophysics Data System (ADS)

    Kamaruzaman, F. F.; Nuruzzaman, D. M.; Ismail, N. M.; Hamedon, Z.; Iqbal, A. K. M. A.; Azhari, A.

    2018-03-01

    In this research works, four-layered aluminium-aluminium oxide (Al-Al2O3) graded composite materials were fabricated using powder metallurgy (PM) method. In processing, metal-ceramic graded composite materials of 0%, 10%, 20% and 30% weight percentage of ceramic concentration were prepared under 30 ton compaction load using a cylindrical die-punch set made of steel. After that, two-step pressureless sintering was carried out at sintering temperature and time 600°C and 3 hours respectively. It was observed that the sintered cylindrical specimens of 30 mm diameter were prepared successfully. The graded composite specimens were analysed and the properties such as density, microstructure and hardness were measured. It was found that after sintering process, the diameter of the graded cylindrical structure was decreased. Using both Archimedes method and rule of mixture (ROM), he density of structure was measured. The obtained results revealed that the microvickers hardness was increased as the ceramic component increases in the graded layer. Moreover, it was observed that the interface of the graded structure is clearly distinguished within the multilayer stack and the ceramic particles are almost uniformly distributed in the Al matrix.

  18. Correlation between grade of pearlite spheroidization and laser induced spectra

    NASA Astrophysics Data System (ADS)

    Yao, Shunchun; Dong, Meirong; Lu, Jidong; Li, Jun; Dong, Xuan

    2013-12-01

    Laser induced breakdown spectroscopy (LIBS) which is used traditionally as a spectrochemical analytical technique was employed to analyze the grade of pearlite spheroidization. Three 12Cr1MoV steel specimens with different grades of pearlite spheroidization were ablated to produce plasma by pulse laser at 266 nm. In order to determine the optimal temporal condition and plasma parameters for correlating the grade of pearlite spheroidization and laser induced spectra, a set of spectra at different delays were analyzed by the principal component analysis method. Then, the relationship between plasma temperature, intensity ratios of ionic to atomic lines and grade of pearlite spheroidization was studied. The analysis results show that the laser induced spectra of different grades of pearlite spheroidization can be readily identifiable by principal component analysis in the range of 271.941-289.672 nm with 1000 ns delay time. It is also found that a good agreement exists between the Fe ionic to atomic line ratios and the tensile strength, whereas there is no obvious difference in the plasma temperature. Therefore, LIBS may be applied not only as a spectrochemical analytical technique but also as a new way to estimate the grade of pearlite spheroidization.

  19. 9 CFR 91.28 - Stanchions and rails.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., galvanized, extra strong, medium carbon steel. Steel pipes or other steel profiles shall consist of not less... work. Pins, plates, and parts other than pipe shall be made of galvanized steel. All areas where galvanizing of the steel has eroded or has been damaged shall be finished with a rust preventative. (5) Pipe...

  20. 9 CFR 91.28 - Stanchions and rails.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., galvanized, extra strong, medium carbon steel. Steel pipes or other steel profiles shall consist of not less... work. Pins, plates, and parts other than pipe shall be made of galvanized steel. All areas where galvanizing of the steel has eroded or has been damaged shall be finished with a rust preventative. (5) Pipe...

  1. 9 CFR 91.28 - Stanchions and rails.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., galvanized, extra strong, medium carbon steel. Steel pipes or other steel profiles shall consist of not less... work. Pins, plates, and parts other than pipe shall be made of galvanized steel. All areas where galvanizing of the steel has eroded or has been damaged shall be finished with a rust preventative. (5) Pipe...

  2. 9 CFR 91.28 - Stanchions and rails.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., galvanized, extra strong, medium carbon steel. Steel pipes or other steel profiles shall consist of not less... work. Pins, plates, and parts other than pipe shall be made of galvanized steel. All areas where galvanizing of the steel has eroded or has been damaged shall be finished with a rust preventative. (5) Pipe...

  3. 9 CFR 91.28 - Stanchions and rails.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., galvanized, extra strong, medium carbon steel. Steel pipes or other steel profiles shall consist of not less... work. Pins, plates, and parts other than pipe shall be made of galvanized steel. All areas where galvanizing of the steel has eroded or has been damaged shall be finished with a rust preventative. (5) Pipe...

  4. Influence of thermo-mechanical treatment in ferritic phase field on microstructure and mechanical properties of reduced activation ferritic-martensitic steel

    NASA Astrophysics Data System (ADS)

    Prakash; Vanaja, J.; Laha, K.; Nageswara Rao, G. V. S.

    2018-03-01

    The present study focuses on the evaluation of microstructure and mechanical properties of reduced activation ferritic-martensitic (RAFM) steel (9Cr-1W-0.06Ta) subjected to thermo-mechanical treatment (TMT) in ferritic phase field. The results obtained were compared with the steel in conventional normalised plus tempered (N+T) condition. The microstructure of the steel in N+T and TMT conditions was assessed by optical and scanning electron microscopes. Hardness, tensile and creep studies were carried out and the results were correlated with the microstructural studies. While the TMT processed steel resulted in coarser prior austenite grains and exhibited ferritic microstructure with large distribution of fine M23C6 and MX precipitates, the N+T steel reveals tempered martensitic structure with finer prior austenitic grains with coarser M23C6 and MX precipitates. Although ferritic structure is present in TMT processed steel, it exhibits better tensile and creep rupture strengths than N+T steel due to the presence of increased dislocation density and finer distribution of precipitates.

  5. Mathematical and physical modeling of thermal stratification phenomena in steel ladles

    NASA Astrophysics Data System (ADS)

    Putan, V.; Vilceanu, L.; Socalici, A.; Putan, A.

    2018-01-01

    By means of CFD numerical modeling, a systematic analysis of the similarity between steel ladles and hot-water model regarding natural convection phenomena was studied. The key similarity criteria we found to be dependent on the dimensionless numbers Fr and βΔT. These similarity criteria suggested that hot-water models with scale in the range between 1/5 and 1/3 and using hot water with temperature of 45 °C or higher are appropriate for simulating natural convection in steel ladles. With this physical model, thermal stratification phenomena due to natural convection in steel ladles were investigated. By controlling the cooling intensity of water model to correspond to the heat loss rate of steel ladles, which is governed by Fr and βΔT, the temperature profiles measured in the water bath of the model were to deduce the extent of thermal stratification in liquid steel bath in the ladles. Comparisons between mathematically simulated temperature profiles in the prototype steel ladles and those physically simulated by scaling-up the measured temperatures profiles in the water model showed good agreement. This proved that it is feasible to use a 1/5 scale water model with 45 °C hot water to simulate natural convection in steel ladles. Therefore, besides mathematical CFD models, the physical hot-water model provided an additional means of studying fluid flow and heat transfer in steel ladles.

  6. Modeling and Simulation of Quenching and Tempering Process in steels

    NASA Astrophysics Data System (ADS)

    Deng, Xiaohu; Ju, Dongying

    Quenching and tempering (Q&T) is a combined heat treatment process to achieve maximum toughness and ductility at a specified hardness and strength. It is important to develop a mathematical model for quenching and tempering process for satisfy requirement of mechanical properties with low cost. This paper presents a modified model to predict structural evolution and hardness distribution during quenching and tempering process of steels. The model takes into account tempering parameters, carbon content, isothermal and non-isothermal transformations. Moreover, precipitation of transition carbides, decomposition of retained austenite and precipitation of cementite can be simulated respectively. Hardness distributions of quenched and tempered workpiece are predicted by experimental regression equation. In order to validate the model, it is employed to predict the tempering of 80MnCr5 steel. The predicted precipitation dynamics of transition carbides and cementite is consistent with the previous experimental and simulated results from literature. Then the model is implemented within the framework of the developed simulation code COSMAP to simulate microstructure, stress and distortion in the heat treated component. It is applied to simulate Q&T process of J55 steel. The calculated results show a good agreement with the experimental ones. This agreement indicates that the model is effective for simulation of Q&T process of steels.

  7. View of the Flume above Sally May Siphon ("Steel Flume ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of the Flume above Sally May Siphon ("Steel Flume on Trestles" in narrative inventory). At far end is Flume Tunnel No. 3 (AZ-65-T) through Purple Mountain. Looking southwest - Childs-Irving Hydroelectric Project, Childs System, Steel Flume on Trestles, Forest Service Road 708/502, Camp Verde, Yavapai County, AZ

  8. Electrochemical Corrosion Behavior of Spray-Formed Boron-Modified Supermartensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Zepon, Guilherme; Nogueira, Ricardo P.; Kiminami, Claudio S.; Botta, Walter J.; Bolfarini, Claudemiro

    2017-04-01

    Spray-formed boron-modified supermartensitic stainless steel (SMSS) grades are alloys developed to withstand severe wear conditions. The addition of boron to the conventional chemical composition of SMSS, combined with the solidification features promoted by the spray forming process, leads to a microstructure composed of low carbon martensitic matrix reinforced by an eutectic network of M2B-type borides, which considerably increases the wear resistance of the stainless steel. Although the presence of borides in the microstructure has a very beneficial effect on the wear properties of the alloy, their effect on the corrosion resistance of the stainless steel was not comprehensively evaluated. The present work presents a study of the effect of boron addition on the corrosion resistance of the spray-formed boron-modified SMSS grades by means of electrochemical techniques. The borides fraction seems to have some influence on the repassivation kinetics of the spray-formed boron-modified SMSS. It was shown that the Cr content of the martensitic matrix is the microstructural feature deciding the corrosion resistance of this sort of alloys. Therefore, if the Cr content in the alloy is increased to around 14 wt pct to compensate for the boron consumed by the borides formation, the corrosion resistance of the alloy is kept at the same level of the alloy without boron addition.

  9. 9 CFR 91.20 - General construction.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... adjacent to the ship's sides which have steel casing, frames, stays or similar fittings, the carrier shall... accessible to animals. A combination of wood and steel pipe or other steel profile construction may be...

  10. 9 CFR 91.20 - General construction.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... adjacent to the ship's sides which have steel casing, frames, stays or similar fittings, the carrier shall... accessible to animals. A combination of wood and steel pipe or other steel profile construction may be...

  11. Effect of young’s modulus on springback for low, medium and high carbon steels during cold drawing of seamless tubes

    NASA Astrophysics Data System (ADS)

    Karanjule, D. B.; Bhamare, S. S.; Rao, T. H.

    2018-04-01

    Cold drawing is widely used deformation process for seamless tube manufacturing. Springback is one of the major problem faced in tube drawing. Springback is due to the elastic energy stored in the tubes during forming process. It is found that this springback depends upon Young’s modulus of the material. This paper reports mechanical testing of three grades of steels viz. low carbon steel, medium carbon steel and high carbon steel to measure their Young’s modulus and corresponding springback. The results shows that there is 10-20 % variation in the Young’s modulus and inverse proportion between the springback and Young’s modulus. More the percentage of carbon, more the strength, less the value of Young’s modulus and more will springback. The study further leads to identify optimum die semi angle of 15 degree, land width of 10 mm and drawing speed of 8, 6 and 4 m/min for least springback in all the three grades respectively and die semi angle as a most dominant factor causing springback.

  12. A Fundamental Study of Tool Steels Processed from Rapidly Solidified Powders.

    DTIC Science & Technology

    1981-12-01

    structures, HIP or HIP and hot-worked high speed tool steels and powder forgings of low and medium alloy steels for load- bearing automotive...M7, M7S, M41, M42, M43S, T15 and M50 . These P/M tool steels exhibit a degree of alloy homogeneity and a fineness/uniformity of carbide dispersion...AD-AIl2 758 DREXEL UNIV PHILADEL.PH IA PA DEPT OF MATERIALS ENGINEERING F/6 11/6 A FUNDAMENTAL STUDY OF TOOL STEELS PROCESSED FROM L DEC 81 A

  13. Structure of zirconium-93 and zirconium-91 as shown by the reactions Zr-92(d,p)Zr-93 and Zr-92(d,t)Zr-91

    NASA Technical Reports Server (NTRS)

    Baron, N.; Leonard, R. F.; Stewart, W. M.; Fink, C. L.; Christensen, P. R.; Nickles, J.; Thorsteinsen, T. F.

    1972-01-01

    Deuterons of 13-MeV incident energy were scattered from Zr-92(d,p)Zr-93. The Zr-92(d,p)Zr-93 data analysis resulted in the location of 47 levels up to an excitation energy of 4.84 MeV, and the spins of 43 of these levels were identified. Essentially all the strength of the 2d5/2, 3s1/2, 2d3/2, and 1g7/2 shells was observed; and the excitation energy of their centroids was computed to be 0.00, 1.21, 2.23, and 2.37 MeV, respectively. Also, 43 percent of the 1h11/2 strength, 21 percent of the 2f7/2 strength, and 3 percent of the 3p3/2 strength were observed. In addition, the Zr-92(d,t)Zr-91 data analysis resulted in the location of 26 levels up to an excitation energy of 4.01 MeV, and the spins of 21 of these levels were identified. Most of the expected strength of the 2d5/2 and 1g9/2 shells was obtained, and the excitation energy of their centroids was computed to be 0.31 and 3.19 MeV, respectively. In addition, six l=1 states are populated belonging to either the 2p1/2 or 2p3/2 shells.

  14. Multiphysics Modeling and Simulations of Mil A46100 Armor-Grade Martensitic Steel Gas Metal Arc Welding Process

    DTIC Science & Technology

    2013-05-23

    simulation of the conventional Gas Metal Arc Welding (GMAW) process, and the application of the developed methods and tools for prediction of the...technology in many industries such as chemical, oil , aerospace, and shipbuilding construction. In fact, within the metal fabrication industry as a...Mechanical Properties of Low Alloy Steel Products. Hardenability Concepts with Applications to Steel, The Metallurgical Society of AIME, Chicago, 1978, p

  15. Role of Chloride in the Corrosion and Fracture Behavior of Micro-Alloyed Steel in E80 Simulated Fuel Grade Ethanol Environment

    PubMed Central

    Joseph, Olufunmilayo O.; Loto, Cleophas A.; Sivaprasad, Seetharaman; Ajayi, John A.; Tarafder, Soumitra

    2016-01-01

    In this study, micro-alloyed steel (MAS) material normally used in the production of auto parts has been immersed in an E80 simulated fuel grade ethanol (SFGE) environment and its degradation mechanism in the presence of sodium chloride (NaCl) was evaluated. Corrosion behavior was determined through mass loss tests and electrochemical measurements with respect to a reference test in the absence of NaCl. Fracture behavior was determined via J-integral tests with three-point bend specimens at an ambient temperature of 27 °C. The mass loss of MAS increased in E80 with NaCl up to a concentration of 32 mg/L; beyond that threshold, the effect of increasing chloride was insignificant. MAS did not demonstrate distinct passivation behavior, as well as pitting potential with anodic polarization, in the range of the ethanol-chloride ratio. Chloride caused pitting in MAS. The fracture resistance of MAS reduced in E80 with increasing chloride. Crack tip blunting decreased with increasing chloride, thus accounting for the reduction in fracture toughness. PMID:28773601

  16. Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

    DTIC Science & Technology

    2013-08-01

    and Watanabe et el. who used energy dispersive spectroscopy to identify AlFe and Al3Fe IMC particles formed in the WZ of 5083 Al to 400 stainless steel ...joint of 304 stainless steel and AA6056 were also rich in chromium, nickel and manganese [33]. Precipitation of second phase particles rich in Cu, Mg...Friction stir welding of dissimilar Al 6013-T4 to X5CrNi18-10 stainless steel .” Mater Design 26 (2005) 41-46. 4. R.M. Leal, A. Loureiro. “Effect of

  17. Mechanical Properties of Heat Affected Zone of High Strength Steels

    NASA Astrophysics Data System (ADS)

    Sefcikova, K.; Brtnik, T.; Dolejs, J.; Keltamaki, K.; Topilla, R.

    2015-11-01

    High Strength Steels became more popular as a construction material during last decade because of their increased availability and affordability. On the other hand, even though general use of Advanced High Strength Steels (AHSS) is expanding, the wide utilization is limited because of insufficient information about their behaviour in structures. The most widely used technique for joining steels is fusion welding. The welding process has an influence not only on the welded connection but on the area near this connection, the so-called heat affected zone, as well. For that reason it is very important to be able to determine the properties in the heat affected zone (HAZ). This area of investigation is being continuously developed in dependence on significant progress in material production, especially regarding new types of steels available. There are currently several types of AHSS on the world market. Two most widely used processes for AHSS production are Thermo-Mechanically Controlled Processing (TMCP) and Quenching in connection with Tempering. In the presented study, TMCP and QC steels grade S960 were investigated. The study is focused on the changes of strength, ductility, hardness and impact strength in heat affected zone based on the used amount of heat input.

  18. Microstructural Development in HSLA-100 Steel Weld Metals

    DTIC Science & Technology

    1990-01-01

    martensite or austenitic particles contribute to the "granular appearance" of the ferrite grains. Copper precipitates ... copper precipitation , which conclusively suggests that the polygonal ferrite formation is not fully suppressed in the alloy . For the HSLA- 100 steel with a...Ava’Iablity Codes Avdi rid 1 or Di ’t’CIiJl A1 2 1. INTRODUCTION Precipitation strengthening of steel by finely dispersed copper

  19. 14 CFR 91.1049 - Personnel.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) Program manager flight, duty, and rest time considerations, and in all cases within the limits set forth in §§ 91.1057 through 91.1061. (3) Vacations. (4) Operational efficiencies. (5) Training. (6) Single... flight, duty, and rest time limits in §§ 91.1057 through 91.1061 in program operations. (d) Unless...

  20. Hot Ductility Behavior of Boron Containing Microalloyed Steels with Varying Manganese Contents

    NASA Astrophysics Data System (ADS)

    Brune, Tobias; Senk, Dieter; Walpot, Raphael; Steenken, Bernhard

    2015-02-01

    The hot ductility is measured for six different steel grades with different microalloying elements and with varying manganese contents using the hot tensile test machine with melting/solidification unit at the Department of Ferrous Metallurgy RWTH Aachen University. To identify the influence of manganese on hot ductility, tests are performed with varying the manganese content from 0.7 to 18.2 wt pct, a high manganese steel. Additionally, the effect of different cooling and strain rates is analyzed by changing the particular rate for selected samples in the minima. To investigate and detect the cause of cracking during testing, the fracture surfaces in the ductility minima are considered with scanning electron microscope-energy dispersive X-ray spectroscopy. Thermodynamic modeling is conducted on basis of the commercial software ThermoCalc©. A sharp decrease of the hot ductility is recognizable at 1398 K (1125 °C), at only 0.7 wt pct manganese because of the low manganese to sulfur ratio. The grades with a Mn content up to 1.9 wt pct show a good ductility with minimal ductility loss. In comparison, the steel grade with 18.2 wt pct has a poor hot ductility. Because of the formation of complex precipitates, where several alloying elements are involved, the influence of boron on hot ductility is not fully clarified. By increasing the cooling rate, the reduction of area values are shifted to smaller values. For high test temperatures, these measured values are decreased for lower strain rates. Thereby, an early drop of the ductility is noticeable for the high temperatures around 1373 K (1100 °C).

  1. Tempering-Induced Microstructural Changes in the Weld Heat-Affected Zone of 9 to 12 Pct Cr Steels and Their Influence on Sliding Wear

    NASA Astrophysics Data System (ADS)

    Velkavrh, Igor; Kafexhiu, Fevzi; Klien, Stefan; Diem, Alexander; Podgornik, Bojan

    2017-01-01

    Increasing amount of tribological applications is working under alternating high/low temperature conditions where the material is subjected to temperature fatigue mechanisms such as creep, softening due to annealing, and at the same time must withstand mechanical wear due to sliding contact with pairing bodies. Steam turbine valves, gate valves, valve heads, stems, seats and bushings, and contacting surfaces of the carrier elements are some examples of such applications. The purpose of the present study is to evaluate the potential of X20 and P91 steels as materials for applications operating under combined effect of mechanical wear and alternating high/low temperature conditions. It was focused on how the microstructural changes occurring in the weld zone affect the wear properties of the selected materials. Generally, with longer tempering time and higher tempering temperature, the number of carbide precipitates decreased, while their relative spacing increased. Before tempering, the morphology of the steel matrix (grain size, microstructure homogeneity) governed the wear resistance of both steels, while after tempering wear response was determined by the combination of the number and the size of carbide particles. After tempering, in X20 steel larger number of stable M23C6 carbides was observed as compared with P91 steel, resulting in lower wear rates. It was observed that for both steels, a similar combination of number density and size distribution of carbide particles provided the highest wear resistance.

  2. Microstructure characterization and charpy toughness of P91 weldment for as-welded, post-weld heat treatment and normalizing & tempering heat treatment

    NASA Astrophysics Data System (ADS)

    Pandey, Chandan; Mahapatra, M. M.; Kumar, Pradeep; Giri, A.

    2017-09-01

    The effect of weld groove design and heat treatment on microstructure evolution and Charpy toughness of P91 pipe weldments was studied. The P91 pipe weldments were subjected to subcritical post weld heat treatment (760 °C-2 h) and normalizing/tempering conditions (normalized-1040 °C/40 min, air cooled; tempered 760 °C/2 h, air cooled) were employed. The influence of subsequent PWHT and N&T treatment on the microstructure of various zone of P91 pipe weldments were also investigated. The present investigation also described the effect of PWHT and N&T treatment on hardness, grain size, precipitate size, inter-particle spacing and fraction area of precipitates present in each zone of P91 pipe weldments. The result indicated great impact of heat treatment on the Charpy toughness and microstructure evolution of P91 weldments. The N&T treatment was found to be more effective heat treatment compared to subsequent PWHT. Charpy toughness value was found to be higher for narrow-groove design as compared to conventional V-groove design.

  3. The heat shock protein-CD91 pathway mediates tumor immunosurveillance

    PubMed Central

    Zhou, Yu Jerry; Binder, Robert Julian

    2014-01-01

    Tumor immunosurveillance can be readily observed in mice and humans. Here, we examine how T-cell responses are primed during tumorigenesis, a condition in which immunostimulatory antigens are extraordinarily scarce. We recently demonstrated that the HSP-CD91 pathway is indispensable for antigen cross-presentation, and thus immunosurveillance, in cancer. PMID:25050192

  4. Peculiar Features of Thermal Aging and Degradation of Rapidly Quenched Stainless Steels under High-Temperature Exposures

    NASA Astrophysics Data System (ADS)

    Shulga, A. V.

    2017-12-01

    This article presents the results of comparative studies of mechanical properties and microstructure of nuclear fuel tubes and semifinished stainless steel items fabricated by consolidation of rapidly quenched powders and by conventional technology after high-temperature exposures at 600 and 700°C. Tensile tests of nuclear fuel tube ring specimens of stainless austenitic steel of grade AISI 316 and ferritic-martensitic steel are performed at room temperature. The microstructure and distribution of carbon and boron are analyzed by metallography and autoradiography in nuclear fuel tubes and semifinished items. Rapidly quenched powders of the considered steels are obtained by the plasma rotating electrode process. Positive influence of consolidation of rapidly quenched powders on mechanical properties after high-temperature aging is confirmed. The correlation between homogeneous distribution of carbon and boron and mechanical properties of the considered steel is determined. The effects of thermal aging and degradation of the considered steels are determined at 600°C and 700°C, respectively.

  5. Contribution to chromium and nickel enrichment during cooking of foods in stainless steel utensils.

    PubMed

    Accominotti, M; Bost, M; Haudrechy, P; Mantout, B; Cunat, P J; Comet, F; Mouterde, C; Plantard, F; Chambon, P; Vallon, J J

    1998-06-01

    Nickel ingestion can cause exacerbation of dermatitis in patients who are already nickel-sensitive; Chromium (Cr VI) is the 2nd allergen, after nickel. However, stainless steel is widely used in home cookware. In this study, we determined nickel and chromium levels by atomic absorption spectrometry in 11 habitual menus cooked in different grades of stainless steel utensils. We noted a great difference in nickel and chromium intake depending on the menu, and a significant difference between the glass and stainless steel saucepans, but this was very low compared with the levels of nickel and chromium contained in the menus; mean intakes of these elements were under the tolerable daily intake (TDI) recommended by the World Health Organization. Hence, there is no advantage for nickel-sensitive patients in switching to materials other than stainless steel, provided that this is of good quality.

  6. SU-E-T-548: Modeling of Breast IORT Using the Xoft 50 KV Brachytherapy Source and 316L Steel Rigid Shield

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burnside, W

    Purpose: Xoft provides a set of 316L Stainless Steel Rigid Shields to be used with their 50 kV X-ray source for Breast IORT treatments. Modeling the different shield sizes in MCNP provides information to help make clinical decisions for selecting the appropriate shield size. Methods: The Xoft Axxent 50 kV Electronic Brachytherapy System has several applications in radiation therapy, one of which is treating cancer of the breast intraoperatively by placing the miniaturized X-ray tube inside an applicator balloon that is expanded to fill the lumpectomy bed immediately following tumor removal. The ribs, lung, and muscular chest wall are allmore » regions at risk to receive undesired dose during the treatment. A Xoft 316L Stainless Steel Rigid Shield can be placed between the intracostal muscles of the chest wall and the remaining breast tissue near the balloon to attenuate the beam and protect these organs. These shields are provided in 5 different sizes, and the effects on dose to the surrounding tissues vary with shield size. MCNP was used to model this environment and tally dose rate to certain regions of interest. Results: The average rib dose rate calculated using 0cm (i.e., no shield), 3cm, and 5cm diameter shields were 26.89, 15.43, and 8.91 Gy/hr respectively. The maximum dose rates within the rib reached 94.74 Gy/hr, 53.56 Gy/hr, and 31.44 Gy/hr for the 0cm, 3cm, and 5cm cases respectively. The shadowing effect caused by the steel shields was seen in the 3-D meshes and line profiles. Conclusion: This model predicts a higher dose rate to the underlying rib region with the 3cm shield compared to the 5cm shield; it may be useful to select the largest possible diameter when choosing a shield size for a particular IORT patient. The ability to attenuate the beam to reduce rib dose was also confirmed. Research sponsored by Xoft Inc, a subsidiary of iCAD.« less

  7. Evaluation of epoxy coated reinforcing steel.

    DOT National Transportation Integrated Search

    1977-01-01

    Epoxy coated deck reinforcement was evaluated during the construction of two bridges on Rte. I-77 in Carroll County. The contractor was favorably impressed with the coated steel, which sustained no damage during shipping or deck construction. Among t...

  8. 40 CFR 91.801 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... EMISSIONS FROM MARINE SPARK-IGNITION ENGINES In-Use Testing and Recall Regulations § 91.801 Applicability... repairs. (f) The requirements of the Manufacturer In-use testing program set forth in §§ 91.803 through 91.805 are waived for existing technology OB/PWC as defined in § 91.3 through model year 2003. (1) The...

  9. Application of a Saddle-Type Eddy Current Sensor in Steel Ball Surface-Defect Inspection

    PubMed Central

    Zhong, Mingming; Xie, Fengqin; Cao, Maoyong

    2017-01-01

    Steel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball’s outer bracket in a semi-circumferential direction. Driven by a friction wheel, the test steel ball rotated in a one-dimensional direction, such that the steel ball surface was fully scanned by the SECS. There were two purposes for using the SECS in the steel ball inspection system: one was to reduce the complexity of the unfolding wheel of the surface deployment mechanism, and the other was to reduce the difficulty of sensor processing and installation. Experiments were carried out on bearing steel balls in diameter of 8 mm with three types of representative and typical defects by using the SECS, and the results showed that the inspection system can detect surface defects as small as 0.05 mm in width and 0.1 mm in depth with high-repetition detection accuracy, and the detection efficiency of 5 pcs/s, which meet the requirement for inspecting ISO grade 10 bearing steel balls. The feasibility of detecting steel ball surface defects by SECS was verified. PMID:29206154

  10. Application of a Saddle-Type Eddy Current Sensor in Steel Ball Surface-Defect Inspection.

    PubMed

    Zhang, Huayu; Zhong, Mingming; Xie, Fengqin; Cao, Maoyong

    2017-12-05

    Steel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball's outer bracket in a semi-circumferential direction. Driven by a friction wheel, the test steel ball rotated in a one-dimensional direction, such that the steel ball surface was fully scanned by the SECS. There were two purposes for using the SECS in the steel ball inspection system: one was to reduce the complexity of the unfolding wheel of the surface deployment mechanism, and the other was to reduce the difficulty of sensor processing and installation. Experiments were carried out on bearing steel balls in diameter of 8 mm with three types of representative and typical defects by using the SECS, and the results showed that the inspection system can detect surface defects as small as 0.05 mm in width and 0.1 mm in depth with high-repetition detection accuracy, and the detection efficiency of 5 pcs/s, which meet the requirement for inspecting ISO grade 10 bearing steel balls. The feasibility of detecting steel ball surface defects by SECS was verified.

  11. Extremely hard amorphous-crystalline hybrid steel surface produced by deformation induced cementite amorphization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Guo, Wei; Meng, Yifei; Zhang, Xie

    Amorphous and nanograined (NG) steels are two categories of strong steels. However, over the past decade, their application has been hindered by their limited plasticity, the addition of expensive alloying elements, and processing challenges associated with producing bulk materials. Here in this work, we report that the surface of a carburized Fe-Mn-Si martensitic steel with extremely low elemental alloying additions can be economically fabricated into an amorphous-nanocrystalline hybrid structure. Atom probe tomography and nanobeam diffraction of a hard turned steel surface together with molecular dynamics (MD) simulations reveal that the original cementite surface structure experiences a size-dependent amorphization and phasemore » transformation during heavy plastic deformation. MD simulations further show that the martensite-cementite interface serves as a nucleation site for cementite amorphization, and that cementite can become disordered if further strained when the cementite particles are relatively small. These graded structures exhibit a surface hardness of ~16.2 GPa, which exceeds the value of ~8.8 GPa for the original nanocrystalline martensitic steel and most nanocrystalline steels reported before. Finally, this practical and cost-efficient approach for producing a hard surface with retained bulk ductility and toughness can provide expanded opportunities for producing an amorphous-crystalline hybrid structure in steels and other alloy systems.« less

  12. Extremely hard amorphous-crystalline hybrid steel surface produced by deformation induced cementite amorphization

    DOE PAGES

    Guo, Wei; Meng, Yifei; Zhang, Xie; ...

    2018-04-11

    Amorphous and nanograined (NG) steels are two categories of strong steels. However, over the past decade, their application has been hindered by their limited plasticity, the addition of expensive alloying elements, and processing challenges associated with producing bulk materials. Here in this work, we report that the surface of a carburized Fe-Mn-Si martensitic steel with extremely low elemental alloying additions can be economically fabricated into an amorphous-nanocrystalline hybrid structure. Atom probe tomography and nanobeam diffraction of a hard turned steel surface together with molecular dynamics (MD) simulations reveal that the original cementite surface structure experiences a size-dependent amorphization and phasemore » transformation during heavy plastic deformation. MD simulations further show that the martensite-cementite interface serves as a nucleation site for cementite amorphization, and that cementite can become disordered if further strained when the cementite particles are relatively small. These graded structures exhibit a surface hardness of ~16.2 GPa, which exceeds the value of ~8.8 GPa for the original nanocrystalline martensitic steel and most nanocrystalline steels reported before. Finally, this practical and cost-efficient approach for producing a hard surface with retained bulk ductility and toughness can provide expanded opportunities for producing an amorphous-crystalline hybrid structure in steels and other alloy systems.« less

  13. Effect of Heat Treatment on Microstructure and Hot Impact Toughness of Various Zones of P91 Welded Pipes

    NASA Astrophysics Data System (ADS)

    Pandey, C.; Mahapatra, M. M.

    2016-06-01

    The new generation super critical thermal power plants are required to operate at enhanced thermal efficiency of over 50% to reduce the fuel consumption and environmental pollution. Creep strength-enhanced ferritic steels, commonly known as Cr-Mo alloys such as P91 (X10CrMoVNb 9-1) are such material of choice for the next generation power plants. The operating requirement of these next generation power plants is that steam temperature of around 650 °C is maintained. For such high-temperature application, creep strength of material is the primary consideration together with adequate weld heat-affected zone (HAZ) toughness. Present work deals with the effect of high service temperature on impact toughness of P91 (X10CrMoVNb 9-1) base material, weld fusion zone, and HAZ. The impact toughness of HAZ for conventional weld groove design and narrow weld groove design has been evaluated experimentally in as-welded and at different post-weld heat treatment conditions. Fractography of the impact toughness specimens of base metal, weld fusion zone, and HAZ was carried out using scanning electron microscope. The effects of heat treatment schemes on the percentage of element present at the fracture surface were also studied.

  14. Dependence of magnetic permeability on residual stresses in alloyed steels

    NASA Astrophysics Data System (ADS)

    Hristoforou, E.; Ktena, A.; Vourna, P.; Argiris, K.

    2018-04-01

    A method for the monitoring of residual stress distribution in steels has been developed based on non-destructive surface magnetic permeability measurements. In order to investigate the potential utilization of the magnetic method in evaluating residual stresses, the magnetic calibration curves of various ferromagnetic alloyed steels' grade (AISI 4140, TRIP and Duplex) were examined. X-Ray diffraction technique was used for determining surface residual stress values. The overall measurement results have shown that the residual stress determined by the magnetic method was in good agreement with the diffraction results. Further experimental investigations are required to validate the preliminary results and to verify the presence of a unique normalized magnetic stress calibration curve.

  15. Quenching and Partitioning Process Development to Replace Hot Stamping of High Strength Automotive Steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    De Moor, Emmanuel

    The present project investigated Quenching and Partitioning (Q&P) to process cold rolled steels to develop high strength sheet steels that exhibit superior ductility compared to available grades with the intent to allow forming of high strength parts at room temperature to provide an alternative to hot stamping of parts. Hot stamping of boron alloyed steel is the current technology to manufacture thinner gauge sections in automotive structures to guarantee anti-intrusion during collisions whilst improving fuel efficiency by decreasing vehicle weight. Hot stamping involves reheating steel to 900 °C or higher followed by deformation and quenching in the die to producemore » ultra-high strength materials. Hot stamping requires significant energy to reheat the steel and is less productive than traditional room temperature stamping operations. Stamping at elevated temperature was developed due to the lack of available steels with strength levels of interest possessing sufficient ductility enabling traditional room temperature forming. This process is seeing growing demand within the automotive industry and, given the reheating step in this operation, increased energy consumption during part manufacturing results. The present research program focused on the development of steel grades via Q&P processing that exhibit high strength and formability enabling room temperature forming to replace hot stamping. The main project objective consisted of developing sheet steels exhibiting minimum ultimate tensile strength levels of 1200 MPa in combination with minimum tensile elongation levels of 15 pct using Q&P processing through judicious alloy design and heat treating parameter definition. In addition, detailed microstructural characterization and study of properties, processing and microstructure interrelationships were pursued to develop strategies to further enhance tensile properties. In order to accomplish these objectives, alloy design was conducted towards achieving

  16. Characterization of Tensile Deformation in AZ91D Mg Alloy Castings

    NASA Astrophysics Data System (ADS)

    Űnal, Ogün; Tiryakioǧlu, Murat

    AZ91 cast Mg alloy specimens in T4 and T6 tempers have been tested in tension. True stress — true plastic strain relationship has been characterized by evaluating the fits to four constitutive equations. Moreover, work hardening behavior in both tempers has been investigated and how well the four constitutive equation can model this behavior has been tested. The effects of temper and structural quality on tensile properties and work hardening are discussed in the paper.

  17. Advanced and amplified BOLD fluctuations in high-grade gliomas.

    PubMed

    Gupta, Lalit; Gupta, Rakesh K; Postma, Alida A; Sahoo, Prativa; Gupta, Pradeep K; Patir, Rana; Ahlawat, Sunita; Saha, Indrajit; Backes, Walter H

    2018-06-01

    Glioma grade along with patient's age and general health are used for treatment planning and prognosis. To characterize and quantify the spontaneous blood oxygen level-dependent (BOLD) fluctuations in gliomas using measures based on T2*-weighted signal time-series and to distinguish between high- and low-grade gliomas. Retrospective. Twenty-one patients with high-grade and 13 patients with low-grade gliomas confirmed on histology were investigated. Dynamic T2*-weighted (multislice single-shot echo-planar-imaging) magnetic resonance imaging (MRI) was performed on a 3T system with an 8-element receive-only head coil to measure the BOLD fluctuations. In addition, a dynamic T 1 -weighted (3D fast field echo) dynamic contrast-enhanced (DCE) perfusion scan was performed. Three BOLD measures were determined: the temporal shift (TS), amplitude of low frequency fluctuations (ALFF), and regional homogeneity (ReHo). DCE perfusion-based cerebral blood volume (CBV) and time-to-peak (TTP) maps were concurrently evaluated for comparison. An analysis-of-variance test was first used. When the test appeared significant, post-hoc analysis was performed using analysis-of-covariance with age as covariate. Logistic regression and receiver-operator characteristic curve analysis were also performed. TS was significantly advanced in high-grade gliomas compared to the contralateral cortex (P = 0.01) and low-grade gliomas (P = 0.009). In high-grade gliomas, ALFF and CBV were significantly higher than the contralateral cortex (P = 0.041 and P = 0.008, respectively) and low-grade gliomas (P = 0.036 and P = 0.01, respectively). ReHo and TTP did not show significant differences between high- and low-grade gliomas (P = 0.46 and P = 0.42, respectively). The area-under-curve was above 0.7 only for the TS, ALFF, and CBV measures. Advanced and amplified hemodynamic fluctuations manifest in high-grade gliomas, but not in low-grade gliomas, and can be assessed using BOLD

  18. Researches upon the cavitation erosion behaviour of austenite steels

    NASA Astrophysics Data System (ADS)

    Bordeasu, I.; Popoviciu, M. O.; Mitelea, I.; Salcianu, L. C.; Bordeasu, D.; Duma, S. T.; Iosif, A.

    2016-02-01

    Paper analyzes the cavitation erosion behavior of two stainless steels with 100% austenitic structure but differing by the chemical composition and the values of mechanical properties. The research is based on the MDE(t) and MDER(t) characteristic curves. We studied supplementary the aspect of the eroded areas by other to different means: observations with performing optical microscopes and roughness measurements. The tests were done in the T2 vibratory facility in the Cavitation Laboratory of the Timisoara Polytechnic University. The principal purpose of the study is the identification of the elements influencing significantly the cavitation erosion resistance. It was established the effect of the principal chemical components (determining the proportion of the structural components in conformity the Schaffler diagram) upon the cavitation erosion resistance. The results of the researches present the influence of the proportion of unstable austenite upon cavitation erosion resistance. The stainless steel with the great proportion of unstable austenite has the best behavior. The obtained conclusion are important for the metallurgists which realizes the stainless steels used for manufacturing the runners of hydraulic machineries (turbines and pumps) with increased resistance to cavitation attack.

  19. Corrosion study of bare and coated stainless steel

    NASA Technical Reports Server (NTRS)

    Morrison, J. D.

    1972-01-01

    A program was conducted at Kennedy Space Center from February 1968 to February 1971 to evaluate the performance of austenitic stainless steel alloys used in fluid systems lines. For several years, there had been numerous failures of stainless steel hardware caused by pitting and stress corrosion cracking. Several alloys were evaluated for effectiveness of certain sacrificial-type protective coverings in preventing corrosion failures. Samples were tested in specially designed racks placed 91 meters (100 yards) above high-tide line at Cape Kennedy. It is concluded that: (1) unprotected tubing samples showed evidence of pitting initiation after 2 weeks; (2) although some alloys develop larger pits than others, it is probable that the actual pitting rate is independent of alloy type; (3) the deepest pitting occurred in the sheltered part of the samples; and (4) zinc-rich coatings and an aluminum-filled coating have afforded sacrificial protection against pitting for at least 28 months. It is believed that a much longer effective coating life can be expected.

  20. Models of grades and tonnages of some lode tin deposits

    USGS Publications Warehouse

    Menzie, W.D.; Reed, B.L.; Singer, Donald A.

    1988-01-01

    Descriptive and grade/tonnage models have recently been built for many types of deposits. Such models consist of descriptions of mineralogy, host rocks, ore textures, controls, alteration, geochemical signatures, age, and tectonic settings, together with statistical models of grades, tonnages, and contained metal of deposits of each type. The models are used to identify areas that may contain undiscovered deposits of given types, to convey to non-geologists an idea of the importance of such deposits, and to test and refine classifications of mineral deposits.Descriptive and grade/tonnage models have recently been built for five types of primary tin deposits: rhyolite-hosted such as in Mexico; hydrothermal lodes such as in Cornwall, England, and the Herberton district, Queensland; replacement (or exhalative?) such as Renison Bell, Tasmania; skarn such as at Lost River, Alaska; and greisen such as in the Erzgebirge. Analyses of frequency distributions of tonnage, contained metal, tin grades and the relationships between these variables show that the deposits fall into four well-defined domains that have definite geological characteristics. Rhyolite-hosted, or Mexican, deposits contain a median of 4 t of tin and have a median grade of 0.4% Sn. Hydrothermal lode deposits have the highest grades. Half of such deposits have grades over 1.0% Sn, and the majority contain more than 1,000 t Sn. Large hydrothermal vein deposits contain more than 50,000 t Sn. Replacement (or exhalative?) deposits contain the largest amount of tin (median = 40,000 t). They are only of slightly lower grade (median = 0.80% Sn) than the hydrothermal lodes. Greisen or stockwork deposits have larger tonnages than replacement deposits, but contain less tin (median = 25,000 t).They are also of much lower grade (median = 0.3% Sn). Though grades and tonnages are available for only four skarn deposits, they appear to be more like greisen deposits than replacement deposits when compared using grades

  1. STS-91 Commander Precourt talks to Cosmonauts Kondakova and Ryumin at SLF

    NASA Technical Reports Server (NTRS)

    1998-01-01

    STS-91 Mission Commander Charles Precourt (left) talks to Elena V. Kondakova and her husband, Valery Ryumin, a cosmonaut with the Russian Space Agency (RSA) and STS-91 mission specialist, at Kennedy Space Center's Shuttle Landing Facility (SLF). The STS-91 crew had just arrived at the SLF aboard T-38 jets in preparation for launch. Kondakova, also a cosmonaut with the RSA, flew with Commander Precourt as a mission specialist on STS-84 which launched on May 15, 1997. STS-91 is scheduled to be launched on June 2 on Space Shuttle Discovery with a launch window opening around 6:10 p.m. EDT. The mission will feature the ninth Shuttle docking with the Russian Space Station Mir, the first Mir docking for Discovery, the conclusion of Phase I of the joint U.S.- Russian International Space Station Program, and the first flight of the new Space Shuttle super lightweight external tank. The STS-91 flight crew also includes Pilot Dominic Gorie and Mission Specialists Wendy B. Lawrence; Franklin Chang-Diaz, Ph.D.; and Janet Kavandi, Ph.D. Andrew Thomas, Ph.D., will be returning to Earth with the crew after living more than four months aboard Mir.

  2. Effect of microstructure on transformation-induced plasticity of silicon-containing low-alloy steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tomita, Yoshiyuki; Morioka, Kojiro

    1997-04-01

    Fe-0.6C-1.5Si-0.8Mn steel was studied to determine the effect of the microstructure on transformation-induced plasticity (TRIP) of silicon-containing low-alloy steel. A remarkable increase in elongation through TRIP can develop in the steel subjected to the following heat treatments: (1) austemper combined with subcritical annealing (SA Aus-T): subcritical annealing at 993K followed by austempering at 673K and then light tempering (after austenitization at 1173K); (2) austemper coupled with interrupted quenching (IQ Aus-T): interrupted quenching at 533K followed by austempering at 673K and light tempering (after austenization at 1,173K). The SA Aus-T treatment produced the triple structures of carbide-free upper bainite, retained austenitemore » ({gamma}R), and free ferrite. As a result of the IQ Aus-T treatment, the triple structures of carbide-free upper bainite, {gamma}R, and tempered martensite appeared. The results are described and microstructural factors in TRIP are discussed.« less

  3. Fatigue testing of weldable high strength steels under simulated service conditions

    NASA Astrophysics Data System (ADS)

    Tantbirojn, Natee

    There have been concerns over the effect of Cathodic Protection (CP) on weldable high strength steels employed in Jack-up production platform. The guidance provided by the Department of Energy HSE on higher strength steels, based on previous work, was to avoid overprotection as this could cause hydrogen embrittlement. However, the tests conducted so far at UCL for the SE702 type high strength steels (yields strength around 690 MPa) have shown that the effect of over protection on high strength steels may not be as severe as previously thought. For this thesis, SE702 high strength steels have been investigated in more detail. Thick (85mm) parent and ground welded plates were tested under constant amplitude in air and seawater with CP. Tests were also conducted on Thick (40mm) T-butt welded plates under variable amplitude loading in air and seawater with two CP levels (-800mV and -1050mV). Different backing materials (ceramic and metallic) for the welding process of the T-butt plates were also investigated. The variable amplitude sequences employed were generated using the Jack-up Offshore Standard load History (JOSH). The fatigue results are presented as crack growth and S/N curves. They were compared to the conventional offshore steel (BS 4360 50D). The results suggested that the fatigue life of the high strength steels was comparable to the BS 4360 50D steels. The effect of increasing the CP was found to be detrimental to the fatigue life but the effect was not large. The effect of CP was less noticeable in T-butt welded plates. However, in general, the effect of overprotection is not as detrimental to the Jack-up steels as previously thought. The load histories generated by JOSH were found to have some unfavourable characteristics. The framework is based on Markov Chain method and pseudo-random number generator for selecting sea-states. A study was carried out on the sequence generated by JOSH. The generated sequences were analysed for their validity for fatigue

  4. Foreign Object Damage in Disks of Two Gas-turbine-grade Silicon Nitrides by Steel Ball Projectiles at Ambient Temperature

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Pereira, J. Michael; Janosik, Lesley A.; Bhatt, Ramakrishna T.

    2003-01-01

    Foreign object damage (FOD) behavior of two commercial gas-turbine-grade silicon nitrides, AS800 and SN282, was determined at ambient temperature through postimpact strength testing of disks impacted by steel ball projectiles with a diameter of 1.59 mm in a velocity range from 115 to 440 m/s. AS800 silicon nitride exhibited a greater FOD resistance than SN282, primarily due to its greater value of fracture toughness (k(sub Ic)). The critical impact velocity V(sub c) for which the corresponding postimpact strength was the lowest was V(sub c) approximately equal to 440 and 300 m/s AS800 and SN282, respectively. A unique lower strength regime was typified for both silicon nitrides depending on impact velocity and was attributed to significant radial cracking. The damage generated by projectile impact was typically in the form of ring, radial, and cone cracks with their severity and combination being dependent on impact velocity. Unlike the thick (4 millimeters) flexure bar specimens used in our previous studies, the thin (2 millimeter) disk target specimen exhibited a unique back-side radial cracking on the reverse side just beneath the impact sites at and above impact velocities of 160 meters per second for SN282 and 220 meters per second AS800.

  5. Friction Stir Spot Welding (FSSW) of Advanced High Strength Steel (AHSS)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Santella, M. L.; Hovanski, Yuri; Pan, Tsung-Yu

    Friction stir spot welding (FSSW) is applied to join advanced high strength steels (AHSS): galvannealed dual phase 780 MPa steel (DP780GA), transformation induced plasticity 780 MPa steel (TRIP780), and hot-stamped boron steel (HSBS). A low-cost Si3N4 ceramic tool was developed and used for making welds in this study instead of polycrystalline cubic boron nitride (PCBN) material used in earlier studies. FSSW has the advantages of solid-state, low-temperature process, and the ability of joining dissimilar grade of steels and thicknesses. Two different tool shoulder geometries, concave with smooth surface and convex with spiral pattern, were used in the study. Welds weremore » made by a 2-step displacement control process with weld time of 4, 6, and 10 seconds. Static tensile lap-shear strength achieved 16.4 kN for DP780GA-HSBS and 13.2kN for TRIP780-HSBS, above the spot weld strength requirements by AWS. Nugget pull-out was the failure mode of the joint. The joining mechanism was illustrated from the cross-section micrographs. Microhardness measurement showed hardening in the upper sheet steel (DP780GA or TRIP780) in the weld, but softening of HSBS in the heat-affect zone (HAZ). The study demonstrated the feasibility of making high-strength AHSS spot welds with low-cost tools.« less

  6. NLC-91

    NASA Technical Reports Server (NTRS)

    Kopp, E.; Witt, G.; Goldberg, R. A.

    1991-01-01

    Noctilucent Clouds (NLC)-91 is a multinational rocket and radar program which will take place in Jul. - Aug. 1991 in northern Scandinavia and the Barents Sea. The main objective of the campaign is to determine with in situ experiments the dynamical, electrodynamical, physical, and chemical parameters of an NLC layer combined with ground based visible radar, lidar, and microwave experiments. The altitude resolution of ground based and in situ measurements in the cold mesopause region should be improved in NLC-91 compared to the previous campaigns below 100 m.

  7. Copper modified austenitic stainless steel alloys with improved high temperature creep resistance

    DOEpatents

    Swindeman, R.W.; Maziasz, P.J.

    1987-04-28

    An improved austenitic stainless steel that incorporates copper into a base Fe-Ni-Cr alloy having minor alloying substituents of Mo, Mn, Si, T, Nb, V, C, N, P, B which exhibits significant improvement in high temperature creep resistance over previous steels. 3 figs.

  8. Ginger extract as green corrosion inhibitor of mild steel in hydrochloric acid solution

    NASA Astrophysics Data System (ADS)

    Fidrusli, A.; Suryanto; Mahmood, M.

    2018-01-01

    Ginger extract as corrosion inhibitor from natural resources was studied to prevent corrosion of mild steel in acid media. Ginger rhizome was extracted to produce green corrosion inhibitor (G-1) while ginger powder bought at supermarket was also extract to form green corrosion inhibitor (G-2). Effectiveness of inhibitor in preventing corrosion process of mild steel was studied in 1.0 M of hydrochloric acid. The experiment of weight loss method and polarization technique were conducted to measure corrosion rate and inhibition efficiency of mild steel in solution containing 1.0 M of hydrochloric acid with various concentration of inhibitor at room temperature. The results showed that, the rate of corrosion dropped from 8.09 mmpy in solution containing no inhibitor to 0.72 mmpy in solution containing 150g/l inhibitor while inhibition efficiency up to 91% was obtained. The polarization curve in polarization experiments shows that the inhibition efficiency is 86% with high concentration of inhibitor. The adsorption of ginger extract on the surface of mild steel was observed by using optical microscope and the characterization analysis was done by using pH measurement method. When high concentration of green inhibitor in the acid solution is used, the pH at the surface of steel is increasing.

  9. Cause-specific mortality in Finnish ferrochromium and stainless steel production workers.

    PubMed

    Huvinen, M; Pukkala, E

    2016-04-01

    Although stainless steel has been produced for more than a hundred years, exposure-related mortality data for production workers are limited. To describe cause-specific mortality in Finnish ferrochromium and stainless steel workers. We studied Finnish stainless steel production chain workers employed between 1967 and 2004, from chromite mining to cold rolling of stainless steel, divided into sub-cohorts by production units with specific exposure patterns. We obtained causes of death for the years 1971-2012 from Statistics Finland. We calculated standardized mortality ratios (SMRs) as ratios of observed and expected numbers of deaths based on population mortality rates of the same region. Among 8088 workers studied, overall mortality was significantly decreased (SMR 0.77; 95% confidence interval [CI] 0.70-0.84), largely due to low mortality from diseases of the circulatory system (SMR 0.71; 95% CI 0.61-0.81). In chromite mine, stainless steel melting shop and metallurgical laboratory workers, the SMR for circulatory disease was below 0.4 (SMR 0.33; 95% CI 0.07-0.95, SMR 0.22; 95% CI 0.05-0.65 and SMR 0.16; 95% CI 0.00-0.90, respectively). Mortality from accidents (SMR 0.84; 95% CI 0.67-1.04) and suicides (SMR 0.72; 95% CI 0.56-0.91) was also lower than in the reference population. Working in the Finnish ferrochromium and stainless steel industry appears not to be associated with increased mortality. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine.

  10. Professors Cede Grading Power to Outsiders--Even Computers

    ERIC Educational Resources Information Center

    Young, Jeffrey R.

    2011-01-01

    The best way to eliminate grade inflation is to take professors out of the grading process: Replace them with professional evaluators who never meet students and don't worry that students will punish harsh grades with poor reviews. That's the argument made by leaders of Western Governors University, which has hired 300 adjunct professors who do…

  11. Microstructure and mechanical properties of 2024-T3 and 7075-T6 aluminum alloys and austenitic stainless steel 304 after being exposed to hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Sofyan, Nofrijon Bin Imam

    The effect of hydrogen peroxide used as a decontaminant agent on selected aircraft metallic materials has been investigated. The work is divided into three sections; bacterial attachment behavior onto an austenitic stainless steel 304 surface; effect of decontamination process on the microstructure and mechanical properties of aircraft metallic structural materials of two aluminum alloys, i.e. 2024-T3 and 7075-T6, and an austenitic stainless steel 304 as used in galley and lavatory surfaces; and copper dissolution rate into hydrogen peroxide. With respect to bacterial attachment, the results show that surface roughness plays a role in the attachment of bacteria onto metallic surfaces at certain extent. However, when the contact angle of the liquid on a surface increased to a certain degree, detachment of bacteria on that surface became more difficult. In its relation to the decontamination process, the results show that a corrosion site, especially on the austenitic stainless steel 304 weld and its surrounding HAZ area, needs more attention because it could become a source or a harborage of bio-contaminant agent after either incidental or intentional bio-contaminant delivery. On the effect of the decontamination process on the microstructure and mechanical properties of aircraft metallic structural materials, the results show that microstructural effects are both relatively small in magnitude and confined to a region immediately adjacent to the exposed surface. No systematic effect is found on the tensile properties of the three alloys under the conditions examined. The results of this investigation are promising with respect to the application of vapor phase hydrogen peroxide as a decontaminant agent to civilian aircraft, in that even under the most severe circumstances that could occur; only very limited damage was observed. The results from the dissolution of copper by concentrated liquid hydrogen peroxide showed that the rate of copper dissolution increased for

  12. Characterization of Coatings on Steel Self-Piercing Rivets for Use with Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    McCune, Robert C.; Forsmark, Joy H.; Upadhyay, Vinod; Battocchi, Dante

    Incorporation of magnesium alloys in self-pierce rivet (SPR) joints poses several unique challenges among which are the creation of spurious galvanic cells and aggravated corrosion of adjacent magnesium when coated steel rivets are employed. This work firstly reviews efforts on development of coatings to steel fasteners for the diminution of galvanic corrosion when used with magnesium alloys. Secondly, approaches, based on several electrochemical methods, for the measurement of the galvanic-limiting effect of a number of commercially-available coatings to hardened 10B37 steel self-piercing rivets inserted into alloy couples incorporating several grades of magnesium are reported. Electrochemical impedance spectroscopy (EIS), zero-resistance ammeter (ZRA), corrosion potential and potential-mapping visualization methods (e.g. scanning vibrating electrode technique — SVET) are illustrated for the several rivet coatings considered.

  13. Development of High Heat Input Welding Offshore Steel as Normalized Condition

    NASA Astrophysics Data System (ADS)

    Deng, Wei; Qin, Xiaomei

    The heavy plate used for offshore structure is one of the important strategic products. In recent years, there is an increasing demand for heavy shipbuilding steel plate with excellent weldability in high heat input welding. During the thermal cycle, the microstructure of the heat affected zone (HAZ) of plates was damaged, and this markedly reduced toughness of HAZ. So, how to improve the toughness of HAZ has been a key subject in the fields of steel research. Oxide metallurgy is considered as an effective way to improve toughness of HAZ, because it could be used to retard grain growth by fine particles, which are stable at the high temperature.The high strength steel plate, which satisfies the low temperature specification, has been applied to offshore structure. Excellent properties of the plates and welded joints were obtained by oxide metallurgy technology, latest controlled rolling and accelerated cooling technology using Ultra-Fast Cooling (an on-line accelerated cooling system). The 355MPa-grade high strength steel plates with normalizing condition were obtained, and the steels have excellent weldability with heat input energy of 79 287kJ/cm, and the nil ductility transition (NDT) temperature was -70°C, which can satisfy the construction of offshore structure in cold regions.

  14. Novel chitosan/diclofenac coatings on medical grade stainless steel for hip replacement applications

    NASA Astrophysics Data System (ADS)

    Finšgar, Matjaž; Uzunalić, Amra Perva; Stergar, Janja; Gradišnik, Lidija; Maver, Uroš

    2016-05-01

    Corrosion resistance, biocompatibility, improved osteointegration, as well the prevention of inflammation and pain are the most desired characteristics of hip replacement implants. In this study we introduce a novel multi-layered coating on AISI 316LVM stainless steel that shows promise with regard to all mentioned characteristics. The coating is prepared from alternating layers of the biocompatible polysaccharide chitosan and the non-steroid anti-inflammatory drug (NSAID), diclofenac. Electrochemical methods were employed to characterize the corrosion behavior of coated and uncoated samples in physiological solution. It is shown that these coatings improve corrosion resistance. It was also found that these coatings release the incorporated drug in controlled, multi-mechanism manner. Adding additional layers on top of the as-prepared samples, has potential for further tailoring of the release profile and increasing the drug dose. Biocompatibility was proven on human-derived osteoblasts in several experiments. Only viable cells were found on the sample surface after incubation of the samples with the same cell line. This novel coating could prove important for prolongation of the application potential of steel-based hip replacements, which are these days often replaced by more expensive ceramic or other metal alloys.

  15. Novel chitosan/diclofenac coatings on medical grade stainless steel for hip replacement applications

    PubMed Central

    Finšgar, Matjaž; Uzunalić, Amra Perva; Stergar, Janja; Gradišnik, Lidija; Maver, Uroš

    2016-01-01

    Corrosion resistance, biocompatibility, improved osteointegration, as well the prevention of inflammation and pain are the most desired characteristics of hip replacement implants. In this study we introduce a novel multi-layered coating on AISI 316LVM stainless steel that shows promise with regard to all mentioned characteristics. The coating is prepared from alternating layers of the biocompatible polysaccharide chitosan and the non-steroid anti-inflammatory drug (NSAID), diclofenac. Electrochemical methods were employed to characterize the corrosion behavior of coated and uncoated samples in physiological solution. It is shown that these coatings improve corrosion resistance. It was also found that these coatings release the incorporated drug in controlled, multi-mechanism manner. Adding additional layers on top of the as-prepared samples, has potential for further tailoring of the release profile and increasing the drug dose. Biocompatibility was proven on human-derived osteoblasts in several experiments. Only viable cells were found on the sample surface after incubation of the samples with the same cell line. This novel coating could prove important for prolongation of the application potential of steel-based hip replacements, which are these days often replaced by more expensive ceramic or other metal alloys. PMID:27215333

  16. Effect of Temperature on the Fracture Toughness of Hot Isostatically Pressed 304L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Cooper, A. J.; Brayshaw, W. J.; Sherry, A. H.

    2018-03-01

    Herein, we have performed J- Resistance multi-specimen fracture toughness testing of hot isostatically pressed (HIP'd) and forged 304L austenitic stainless steel, tested at elevated (300 °C) and cryogenic (- 140 °C) temperatures. The work highlights that although both materials fail in a pure ductile fashion, stainless steel manufactured by HIP displays a marked reduction in fracture toughness, defined using J 0.2BL, when compared to equivalently graded forged 304L, which is relatively constant across the tested temperature range.

  17. Corrosion of austenitic steels and their components in vanadium-containing chloride melts

    NASA Astrophysics Data System (ADS)

    Abramov, A. V.; Polovov, I. B.; Rebrin, O. I.; Lisienko, D. G.

    2014-08-01

    The corrosion of austenitic 12Kh18N10T, 10Kh17N13M2T, and 03Kh17N14M3 steels and their components (Cr, Fe, Ni, Mo) in NaCl-KCl-VCl2 melts with 5 wt % V at 750°C is studied. The rates and mechanisms of corrosion of the materials under these conditions are determined. The processes that occur during contact of the metals and steels with vanadium-containing chloride electrolytes are investigated.

  18. 40 CFR 440.91 - [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false [Reserved] 440.91 Section 440.91 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Antimony Ore Subcategory § 440.91 [Reserved] ...

  19. 40 CFR 440.91 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false [Reserved] 440.91 Section 440.91 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Antimony Ore Subcategory § 440.91 [Reserved] ...

  20. 40 CFR 91.601 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Applicability. 91.601 Section 91.601 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES Selective Enforcement Auditing Regulations § 91.601...

  1. Carburizing treatment of low alloy steels: Effect of technological parameters

    NASA Astrophysics Data System (ADS)

    Benarioua, Younes

    2018-05-01

    The surface areas of the parts subjected to mechanical loads influence to a great extent the resistance to wear and fatigue. In majority of cases, producing of a hard superficial layer on a tough substrate is conducive to an increased resistance to mechanical wear and fatigue. Cementation treatment of low alloy steels which bonds superficial martensitic layer of high hardness and lateral compressive to a core of lower hardness and greater toughness is an example of a good solution of the problem. The high hardness of the martensitic layer is due to an increased concentration of interstitial carbon atoms in the austenite before quenching. The lower hardness of the core after quenching is due to the presence of ferrite and pearlite components which appear if the cooling rate after austenitization becomes lower than the critical on. The objective of the present study was to obtain a cemented surface layer on low alloy steel by means of pack carburizing treatment. Different steel grades, austenitization temperatures as well as different soaking times were used as parameters of the pack carburizing treatment. During this treatment, carbon atoms from the pack powder diffuse toward the steels surface and form compounds of iron carbides. The effect of carburizing parameters on the transformation rate of low carbon surface layer of the low alloy steel to the cemented one was investigated by several analytical techniques.

  2. Prediction of Continuous Cooling Transformation Diagrams for Dual-Phase Steels from the Intercritical Region

    NASA Astrophysics Data System (ADS)

    Colla, V.; Desanctis, M.; Dimatteo, A.; Lovicu, G.; Valentini, R.

    2011-09-01

    The purpose of the present work is the implementation and validation of a model able to predict the microstructure changes and the mechanical properties in the modern high-strength dual-phase steels after the continuous annealing process line (CAPL) and galvanizing (Galv) process. Experimental continuous cooling transformation (CCT) diagrams for 13 differently alloying dual-phase steels were measured by dilatometry from the intercritical range and were used to tune the parameters of the microstructural prediction module of the model. Mechanical properties and microstructural features were measured for more than 400 dual-phase steels simulating the CAPL and Galv industrial process, and the results were used to construct the mechanical model that predicts mechanical properties from microstructural features, chemistry, and process parameters. The model was validated and proved its efficiency in reproducing the transformation kinetic and mechanical properties of dual-phase steels produced by typical industrial process. Although it is limited to the dual-phase grades and chemical compositions explored, this model will constitute a useful tool for the steel industry.

  3. Pilot-scale steam aging of steel slags.

    PubMed

    Kumar, Praveen; Satish Kumar, D; Marutiram, K; Prasad, Smr

    2017-06-01

    Solid waste management has gained importance in the steel industry in view of rising environmental concerns and scarcity of raw materials. In spite of significant developments in reducing waste generation and development of recycling technologies, steel slag is still a concern for the industry as most of it is dumped. Steel slag is similar to stone aggregates in strength, but its volumetric instability in contact with water hinders its application as aggregates in construction. A part of steel slag is normally exposed to rain and sun for natural aging and stabilization for months before use. The natural aging process is slow and time-consuming, and thus restricts its usage. The steelmaking slag can be put to effective use as coarse aggregates if quickly aged and stabilized by pre-reacting the free expansive phases. In the present work, a new process has been developed to accelerate the steel slag aging process using steam in a 30 T pilot scale facility. The setup has controlled steam injection, distribution, and process control system for steam, temperature, flow, and pressure. Steam percolates through the minute pores in the slag lumps and hydrates the expansive free lime and MgO phases, making it stable. The aged slag expansion properties were tested using an in-house developed expansion testing apparatus. The process is capable of reducing the expansion of steel slag from 3.5% to <1.5% (standard requirement) in 7 days. The aged steel slag is currently being used in roads at JSW Steel, Vijayanagar Works.

  4. Threshold oxygen levels in Na(I) for the formation of NaCrO 2(s) on 18-8 stainless steels from accurate thermodynamic measurements

    NASA Astrophysics Data System (ADS)

    Sreedharan, O. M.; Madan, B. S.; Gnanamoorthy, J. B.

    1983-12-01

    The compound NaCrO 2(s) is an important corrosion product in sodium-cooled LMFBRs. The standard Gibbs energy of formation of NaCrO 2(s) is required for the computation of threshold oxygen levels in Na(1) for the formation of NaCrO 2(s) on 18-8 stainless steels. For this purpose the emf of the galvanic cell: Pt, NaCrO 2, Cr 2O 3, Na 2CrO 4/15 YSZ/O 2 ( P O 2 = 0.21 atm, air), Pt was measured over 784-1012 K to be: (E±4.4)(mV) = 483.67-0.34155 T(K). From this, the standard Gibbs energy of formation of NaCrO 2(s) from the elements ( ΔG f,T0) and from the oxides ( ΔG f,OX,T0) was calculated to be: [ΔG f,T0(NaCrO 2, s)±1.86] (kJ/mol) =-869.98 + 0.18575 T(K) , [ΔG f,OX,T0(NaCr0 2, s)±4.8] (kJ/mol) = -104.25-0.00856 T(K) . The molar heat capacity, C P0, of NaCrO 2(s) was measured by DSC to be (350-600 K): C P0(NaCrO 2, s) (J/K mol) = 27.15 + 0.1247 T (K) , From these data, values of -99.3 kJ/mol and 91.6 J/K mol were computed for ΔH f,2980 and S 2980 of NaCrO 2(s). The internal consistency was checked with the use of enthalpy data on Na 2CrO 4(s). From the standard Gibbs energy of formation of NaCrO 2(s) the equation logC 0(wppm) = 3.9905-3147.6 T(K) was derived, where C 0 is the threshold oxygen level for the formation of NaCrO 2(s) on 18-8 stainless steels.

  5. Introduction of High Throughput Magnetic Resonance T2-Weighted Image Texture Analysis for WHO Grade 2 and 3 Gliomas.

    PubMed

    Kinoshita, Manabu; Sakai, Mio; Arita, Hideyuki; Shofuda, Tomoko; Chiba, Yasuyoshi; Kagawa, Naoki; Watanabe, Yoshiyuki; Hashimoto, Naoya; Fujimoto, Yasunori; Yoshimine, Toshiki; Nakanishi, Katsuyuki; Kanemura, Yonehiro

    2016-01-01

    Reports have suggested that tumor textures presented on T2-weighted images correlate with the genetic status of glioma. Therefore, development of an image analyzing framework that is capable of objective and high throughput image texture analysis for large scale image data collection is needed. The current study aimed to address the development of such a framework by introducing two novel parameters for image textures on T2-weighted images, i.e., Shannon entropy and Prewitt filtering. Twenty-two WHO grade 2 and 28 grade 3 glioma patients were collected whose pre-surgical MRI and IDH1 mutation status were available. Heterogeneous lesions showed statistically higher Shannon entropy than homogenous lesions (p = 0.006) and ROC curve analysis proved that Shannon entropy on T2WI was a reliable indicator for discrimination of homogenous and heterogeneous lesions (p = 0.015, AUC = 0.73). Lesions with well-defined borders exhibited statistically higher Edge mean and Edge median values using Prewitt filtering than those with vague lesion borders (p = 0.0003 and p = 0.0005 respectively). ROC curve analysis also proved that both Edge mean and median values were promising indicators for discrimination of lesions with vague and well defined borders and both Edge mean and median values performed in a comparable manner (p = 0.0002, AUC = 0.81 and p < 0.0001, AUC = 0.83, respectively). Finally, IDH1 wild type gliomas showed statistically lower Shannon entropy on T2WI than IDH1 mutated gliomas (p = 0.007) but no difference was observed between IDH1 wild type and mutated gliomas in Edge median values using Prewitt filtering. The current study introduced two image metrics that reflect lesion texture described on T2WI. These two metrics were validated by readings of a neuro-radiologist who was blinded to the results. This observation will facilitate further use of this technique in future large scale image analysis of glioma.

  6. High Thermal Conductivity and High Wear Resistance Tool Steels for cost-effective Hot Stamping Tools

    NASA Astrophysics Data System (ADS)

    Valls, I.; Hamasaiid, A.; Padré, A.

    2017-09-01

    In hot stamping/press hardening, in addition to its shaping function, the tool controls the cycle time, the quality of the stamped components through determining the cooling rate of the stamped blank, the production costs and the feasibility frontier for stamping a given component. During the stamping, heat is extracted from the stamped blank and transported through the tool to the cooling medium in the cooling lines. Hence, the tools’ thermal properties determine the cooling rate of the blank, the heat transport mechanism, stamping times and temperature distribution. The tool’s surface resistance to adhesive and abrasive wear is also an important cost factor, as it determines the tool durability and maintenance costs. Wear is influenced by many tool material parameters, such as the microstructure, composition, hardness level and distribution of strengthening phases, as well as the tool’s working temperature. A decade ago, Rovalma developed a hot work tool steel for hot stamping that features a thermal conductivity of more than double that of any conventional hot work tool steel. Since that time, many complimentary grades have been developed in order to provide tailored material solutions as a function of the production volume, degree of blank cooling and wear resistance requirements, tool geometries, tool manufacturing method, type and thickness of the blank material, etc. Recently, Rovalma has developed a new generation of high thermal conductivity, high wear resistance tool steel grades that enable the manufacture of cost effective tools for hot stamping to increase process productivity and reduce tool manufacturing costs and lead times. Both of these novel grades feature high wear resistance and high thermal conductivity to enhance tool durability and cut cycle times in the production process of hot stamped components. Furthermore, one of these new grades reduces tool manufacturing costs through low tool material cost and hardening through readily

  7. 47 CFR 9.1 - Purposes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Purposes. 9.1 Section 9.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INTERCONNECTED VOICE OVER INTERNET PROTOCOL SERVICES § 9.1... applicable to interconnected Voice over Internet Protocol service providers, and to ensure that those...

  8. 47 CFR 9.1 - Purposes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Purposes. 9.1 Section 9.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INTERCONNECTED VOICE OVER INTERNET PROTOCOL SERVICES § 9.1... applicable to interconnected Voice over Internet Protocol service providers, and to ensure that those...

  9. 47 CFR 9.1 - Purposes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Purposes. 9.1 Section 9.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INTERCONNECTED VOICE OVER INTERNET PROTOCOL SERVICES § 9.1... applicable to interconnected Voice over Internet Protocol service providers, and to ensure that those...

  10. 47 CFR 9.1 - Purposes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Purposes. 9.1 Section 9.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INTERCONNECTED VOICE OVER INTERNET PROTOCOL SERVICES § 9.1... applicable to interconnected Voice over Internet Protocol service providers, and to ensure that those...

  11. 47 CFR 9.1 - Purposes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Purposes. 9.1 Section 9.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INTERCONNECTED VOICE OVER INTERNET PROTOCOL SERVICES § 9.1... applicable to interconnected Voice over Internet Protocol service providers, and to ensure that those...

  12. 40 CFR 440.91 - [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false [Reserved] 440.91 Section 440.91 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Antimony Ore Subcategory § 440.91 [Reserved] ...

  13. 40 CFR 440.91 - [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 31 2013-07-01 2013-07-01 false [Reserved] 440.91 Section 440.91 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Antimony Ore Subcategory § 440.91 [Reserved] ...

  14. 40 CFR 440.91 - [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false [Reserved] 440.91 Section 440.91 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Antimony Ore Subcategory § 440.91 [Reserved] ...

  15. 7 CFR 91.3 - Authority.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Authority. 91.3 Section 91.3 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections... AND GENERAL INFORMATION Administration § 91.3 Authority. The Deputy Administrator is charged with the...

  16. 40 CFR 91.602 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Definitions. 91.602 Section 91.602 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES Selective Enforcement Auditing Regulations § 91.602 Definitions...

  17. 29 CFR 1915.91 - Housekeeping.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Housekeeping. 1915.91 Section 1915.91 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT General Working Conditions § 1915.91...

  18. Effect of implanted helium on tensile properties and hardness of 9% Cr martensitic stainless steels

    NASA Astrophysics Data System (ADS)

    Jung, P.; Henry, J.; Chen, J.; Brachet, J.-C.

    2003-05-01

    Hundred micrometer thick specimens of 9% Cr martensitic steels EM10 and T91 were homogeneously implanted with He 4 to concentrations up to 0.5 at.% at temperatures from 150 to 550 °C. The specimens were tensile tested at room temperature and at the respective implantation temperatures. Subsequently the fracture surfaces were analysed by scanning electron microscopy and some of the specimens were examined in an instrumented hardness tester. The implanted helium caused hardening and embrittlement which both increased with increasing helium content and with decreasing implantation temperature. Fracture surfaces showed intergranular brittle appearance with virtually no necking at the highest implantation doses, when implanted below 250 °C. The present tensile results can be scaled to tensile data after irradiation in spallation sources on the basis of helium content but not on displacement damage. An interpretation of this finding by microstructural examination is given in a companion paper [J. Nucl. Mater., these Proceedings].

  19. Fracture Characteristics of Structural Steels and Weldments

    DTIC Science & Technology

    1975-11-01

    CARACTERISTICS 0F.$ýTRUCTURAL TEL/ - "AD E NTSA .INAL 1 A7 sk S. CONTRACT OR GRANT NUMBER(&) Y.2G. im 9. PERFORMING ORGANIZATION NAME AND ADDRESS -017...36, T- 1,and HY-Y130 Steel and AX. Il 30 15 I Tensile F~racture Surface of A-36 Steel, 12x 31 16 Dimple Rupture in A-6Sel 0X 31 17 Plastic ...sites and the relative plasticity of thle The objective of this study was to use a scanning metal. If many fracture icleation sites initiate mticro

  20. Investigations on the Behavior of HVOF and Cold Sprayed Ni-20Cr Coating on T22 Boiler Steel in Actual Boiler Environment

    NASA Astrophysics Data System (ADS)

    Bala, Niraj; Singh, Harpreet; Prakash, Satya; Karthikeyan, J.

    2012-01-01

    High temperature corrosion accompanied by erosion is a severe problem, which may result in premature failure of the boiler tubes. One countermeasure to overcome this problem is the use of thermal spray protective coatings. In the current investigation high velocity oxy-fuel (HVOF) and cold spray processes have been used to deposit commercial Ni-20Cr powder on T22 boiler steel. To evaluate the performance of the coatings in actual conditions the bare as well as the coated steels were subjected to cyclic exposures, in the superheater zone of a coal fired boiler for 15 cycles. The weight change and thickness loss data were used to establish kinetics of the erosion-corrosion. X-ray diffraction, surface and cross-sectional field emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) and x-ray mapping techniques were used to analyse the as-sprayed and corroded specimens. The HVOF sprayed coating performed better than its cold sprayed counterpart in actual boiler environment.