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Sample records for alloy-x750 inconel

  1. Tensile behavior of Inconel alloy X-750 in air and vacuum at elevated temperatures

    SciTech Connect

    Taplin, D.M.R.; Mukherjee, A.K.; Pandey, M.C.

    1984-09-01

    The hot tensile properties of Inconel alloy X-750 have been investigated experimentally at 700 C in air and vacuum at strain rates varying from 10 to the -7th to 1.2 x 10 to the -6th per s. The strength and ductile characteristics of the specimens tested in vacuum are found to be better than those tested in air. In air, a ductility minimum is observed at 625 C, whereas in vacuum, significant improvements in creep ductility are observed at 575 and 625 C, with the ductility minimum shifting from 625 to 700 C. It is shown that the creep ductility of the specimens tested in air is largely determined by the following two competing processes: (1) deformation-assisted oxygen diffusion and (2) grain boundary migration. 20 references.

  2. Radiation-induced segregation in alloy X-750

    SciTech Connect

    Kenik, E.A.

    1996-12-31

    Microstructural and microchemical evolution of an Alloy X-750 heat under neutron irradiation was studied in order to understand the origin of irradiation-assisted stress corrosion cracking. Both clustering of point defects and radiation-induced segregation at interfaces were observed. Although no significant changes in the precipitate structure were observed, boundaries exhibited additional depletion of Cr and Fe and enrichment of Ni.

  3. Study of IGSCC in alloy X-750

    SciTech Connect

    Mason, T.; Pan, Y.

    1994-12-31

    Intergranular stress corrosion cracking (IGSCC) has a very costly and detrimental influence on the service life of steam generator tubes in nuclear power plants. Much research has been done to discover the mechanisms at work in IGSCC and develop effective measures to inhibit crack growth. Recently efforts have turned from controlling the service atmosphere and allow chemistry toward discovering microstructures that are more crack resistant and prescribing appropriate thermomechanical treatments. Palumbo and Aust and Crawford and Was have shown that grain boundaries that are characterized by low-angle misorientations or low coincident site lattice (CSL) relationships are more resistant to damage during exposure to environments promoting IGSCC. These researchers used the selected area channeling method in a secondary electron monitor (SEM) to measure the local lattice orientations on either side of damaged grain boundaries. More recently, the electron backscatter method, which requires less lattice interaction volume, has been combined with an automated SEM to collect large sets of lattice orientations at prescribed locations on a sample. This automated measurement technique, called orientation imaging microscopy (OIM), has been applied in this study to the correlation of IGSCC with the crystallographic misorientation of boundaries in Inconel X-750.

  4. A combined AEM/APFIM characterization of Alloy X-750

    SciTech Connect

    Burke, M.G.; Miller, M.K.

    1992-05-01

    In the development of advanced alloys for power system applications, the primary emphasis is placed on attaining specific mechanical properties with resistance to environmental attack. An important part of alloy development is the detailed characterization of the microstructure, because it is the composition, size and morphology of the microstructural features that define the mechanical properties of the material. The good mechanical properties of Ni-base superalloys are a result of the formation of fine coherent precipitates. Analytical electron microscopy (AEM) provides important information concerning the type and distribution of the phases in the alloys, but quantitative microchemical analysis for the ultra-fine precipitates is not readily obtainable with conventional AEM techniques. The high optical resolution of the atom probe field-ion microscope (APFIM) make this technique ideally suited to the analysis of the ultra-fine precipitates and surrounding matrix. In this paper, a combined AEM/APFIM study of precipitation in Alloy X-750 is presented.

  5. A combined AEM/APFIM characterization of Alloy X-750

    SciTech Connect

    Burke, M.G. ); Miller, M.K. )

    1992-01-01

    In the development of advanced alloys for power system applications, the primary emphasis is placed on attaining specific mechanical properties with resistance to environmental attack. An important part of alloy development is the detailed characterization of the microstructure, because it is the composition, size and morphology of the microstructural features that define the mechanical properties of the material. The good mechanical properties of Ni-base superalloys are a result of the formation of fine coherent precipitates. Analytical electron microscopy (AEM) provides important information concerning the type and distribution of the phases in the alloys, but quantitative microchemical analysis for the ultra-fine precipitates is not readily obtainable with conventional AEM techniques. The high optical resolution of the atom probe field-ion microscope (APFIM) make this technique ideally suited to the analysis of the ultra-fine precipitates and surrounding matrix. In this paper, a combined AEM/APFIM study of precipitation in Alloy X-750 is presented.

  6. Irradiation assisted stress corrosion cracking of HTH Alloy X-750 and Alloy 625

    SciTech Connect

    Mills, W.J.; Lebo, M.R.; Bajaj, R.; Kearns, J.J.; Hoffman, R.C.; Korinko, J.J.

    1994-06-01

    In-reactor testing of bolt-loaded precracked compact tension specimens was performed in 360{degree}C water to determine effect of irradiation on the SCC behavior of HTH Alloy X-750 and direct aged Alloy 625. Out-of-flux and autoclave control specimens provided baseline data. Primary test variables were stress intensity factor, fluence, chemistry, processing history, prestrain. Results for the first series of experiments were presented at a previous conference. Data from two more recent experiments are compared with previous results; they confirm that high irradiation levels significantly reduce SCC resistance in HTH Alloy X-750. Heat-to-heat differences in IASCC were related to differences in boron content, with low boron heats showing improved SCC resistance. The in-reactor SCC performance of Alloy 625 was superior to that for Alloy X-750, as no cracking was observed in any Alloy 625 specimens even though they were tested at very high K{sub 1} and fluence levels. A preliminary SCC usage model developed for Alloy X-750 indicates that in-reactor creep processes, which relax stresses but also increase crack tip strain rates, and radiolysis effects accelerate SCC. Hence, in-reactor SCC damage under high flux conditions may be more severe than that associated with postirradiation tests. In addition, preliminary mechanism studies were performed to determine the cause of IASCC In Alloy X-750.

  7. Irradiation-assisted stress corrosion cracking in HTH Alloy X-750 and Alloy 625

    SciTech Connect

    Bajaj, R.; Mills, W.J.; Lebo, M.R.; Hyatt, B.Z.; Burke, M.G.

    1995-12-31

    In-reactor testing of bolt-loaded compact tension specimens was performed in 360 C water to determine the irradiation-assisted stress corrosion cracking (IASCC) behavior of HTH Alloy X-750 and direct-aged Alloy 625. New data confirm previous results showing that high irradiation levels reduce SCC resistance in Alloy X-750. Heat-to-heat variability correlates with boron content, with low boron heats showing improved IASCC properties. Alloy 625 is resistant to IASCC, as no cracking was observed in any Alloy 625 specimens. Microstructural, microchemical and deformation studies were performed to characterize the mechanisms responsible for IASCC in Alloy X-750 and the lack of an effect in Alloy 625. The mechanisms under investigation are: boron transmutation effects, radiation-induced changes in microstructure and deformation characteristics, and radiation-induced segregation. Irradiation of Alloy X-750 caused significant strengthening and ductility loss that was associated with the formation of cavities and dislocation loops. High irradiation levels did not cause significant segregation of alloying or trace elements in Alloy X-750. Irradiation of Alloy 625 resulted in the formation of small dislocation loops and a fine body-centered-orthorhombic phase. The strengthening due to the loops and precipitates was apparently offset by a partial dissolution of {gamma}{double_prime} precipitates, as Alloy 625 showed no irradiation-induced strengthening or ductility loss. In the nonirradiated condition, an IASCC susceptible HTH heat containing 28 ppm B showed grain boundary segregation of boron, whereas a nonsusceptible HTH heat containing 2 ppm B and Alloy 625 with 20 ppm B did not show significant boron segregation. Transmutation of boron to helium at grain boundaries, coupled with matrix strengthening, is believed to be responsible for IASCC in Alloy X-750, and the absence of these two effects results in the superior IASCC resistance displayed by Alloy 625.

  8. Mechanisms of stress-corrosion cracking of alloy X-750 in high-purity water

    SciTech Connect

    Grove, C.A.; Petzold, L.D.

    1985-09-01

    The high-strength, nickel-base alloy X-750 is susceptible to stress-corrosion cracking (SCC) in high-purity, deaerated water. Crack initiation occurs at high temperatures (>400F (204C)). Crack propagation occurs in both high-temperature and lowtemperature (<300F(149C)) water. High-temperature crack growth rates are on the order of mils per day. Low-temperature cracking is extremely rapid (approx. =100 in. (250 cm) per day). Three heat treatments of Alloy X-750 are investigated: stress equalized1625F (885C)/24 hours + 1300F (704C)/20 hours, direct aged-1300F (704C)/24 hours, and solution annealed and direct aged-2000F (1093C)/ 1 hour + 1300F (704C)/20 hours. Stress-equalized Alloy X-750 is most susceptible to SCC; solution-annealed and direct-aged Alloy X-750 is least susceptible. A hydrogen embrittlement model of SCC is developed that predicts SCC performance on the basis of grain boundary chemistry and grain boundary carbides. Phosphorus segregates to the grain boundary in concentrations of up to approx. =100 times the bulk concentration during processing and heat treatment. Phosphorus at the grain boundaries increases susceptibility to high- and low-temperature SCC. The presence of M23C6-type carbides and/or the absence of MC-type carbides at the grain boundaries improves SCC performance in high-temperature water.

  9. Mechanism of stress-corrosion cracking of Alloy X-750 in high purity water

    SciTech Connect

    Grove, C.A.; Petzold, L.D.

    1985-11-01

    The high strength Ni-base Alloy X-750 is susceptible to stress-corrosion cracking (SCC) in high purity, deaerated water. Crack initiation occurs at high temperatures (>400F). Crack propagation occurs in both high-temperature and low-temperature (<300F) water. High-temperature crack growth rates are on the order of mils/day. Low-temperature cracking is extremely rapid (approx.100 in./day). Three heat treatments of Alloy X-750 are investigated: (1) Stress Equalized - 1625F/24 hr + 1300F/20 hr, (2) Direct Aged - 1300F/24 hr, and (3) Solution Annealed and Direct Aged - 2000F/1 hr + 1300F/20 hr. Stress-equalized Alloy X-750 is most susceptible to SCC; solution-annealed and direct-aged Alloy X-750 is least susceptible. A Hydrogen Embrittlement Model of SCC is developed that predicts SCC performance on the basis of grain boundary chemistry and grain boundary carbides. Phosphorus segregates to the grain boundary in concentrations of up to approx.100 times the bulk concentration during processing and heat treatment. Phosphorus at the grain boundaries increases susceptibility to high- and low-temperature SCC. The presence of M23C6-type carbides and/or the absence of MC-type carbides at the grain boundaries improves SCC performance in high-temperature water. 18 figs., 5 tabs.

  10. Baseline Fracture Toughness and CGR testing of alloys X-750 and XM-19 (EPRI Phase I)

    SciTech Connect

    J. H. Jackson; S. P. Teysseyre

    2012-10-01

    The Advanced Test Reactor National Scientific User Facility (ATR NSUF) and Electric Power Research Institute (EPRI) formed an agreement to test representative alloys used as reactor structural materials as a pilot program toward establishing guidelines for future ATR NSUF research programs. This report contains results from the portion of this program established as Phase I (of three phases) that entails baseline fracture toughness, stress corrosion cracking (SCC), and tensile testing of selected materials for comparison to similar tests conducted at GE Global Research. The intent of this Phase I research program is to determine baseline properties for the materials of interest prior to irradiation, and to ensure comparability between laboratories using similar testing techniques, prior to applying these techniques to the same materials after having been irradiated at the Advanced Test Reactor (ATR). The materials chosen for this research are the nickel based super alloy X-750, and nitrogen strengthened austenitic stainless steel XM-19. A spare core shroud upper support bracket of alloy X-750 was purchased by EPRI from Southern Co. and a section of XM-19 plate was purchased by EPRI from GE-Hitachi. These materials were sectioned at GE Global Research and provided to INL.

  11. Modelling of hydrogen assisted cracking of nickel-base Alloy X-750 in water

    SciTech Connect

    Oka, T.; Ballinger, R.G.; Hwang, I.S.

    1992-12-31

    A closed-form, semi-empirical, electrochemical model has been developed to rationalize the intergranular corrosion fatigue behavior of alloy X-750 in aqueous electrolytes. The model is based on the assumption that, in the electrolytes investigated and for the microstructures studied, that hydrogen assisted crack growth is the dominant mechanism. Further, it is assumed that the rate of hydrogen reduction is a controlling factor in the magnitude of the environmental component of crack growth. Electrolyte conductivity, dissolution and passivation kinetics of precipitates, grain boundary coverage of precipitates are identified as important environmental and microstructural variables governing the hydrogen reduction rate at the crack tip. The model is compared with experimental data for fatigue crack growth where hydrogen is supplied by external charging and with data where galvanically-generated local hydrogen is responsible for enhanced crack growth. It is shown that predicted results characterize the observed effects of frequency, microstructure, electrolyte conductivity, and stress intensity factor. The agreement between the hydrogen reduction model and measured crack growth rate is believed to support the proposed galvanic corrosion mechanism for the intergranular cracking of alloy X-750 in low temperature water.

  12. Baseline Fracture Toughness and CGR testing of alloys X-750 and XM-19 (EPRI Phase I)

    SciTech Connect

    J. H. Jackson; S. P. Teysseyre

    2012-02-01

    The Advanced Test Reactor National Scientific User Facility (ATR NSUF) and Electric Power Research Institute (EPRI) formed an agreement to test representative alloys used as reactor structural materials as a pilot program toward establishing guidelines for future ATR NSUF research programs. This report contains results from the portion of this program established as Phase I (of three phases) that entails baseline fracture toughness, stress corrosion cracking (SCC), and tensile testing of selected materials for comparison to similar tests conducted at GE Global Research. The intent of this Phase I research program is to determine baseline properties for the materials of interest prior to irradiation, and to ensure comparability between laboratories using similar testing techniques, prior to applying these techniques to the same materials after having been irradiated at the Advanced Test Reactor (ATR). The materials chosen for this research are the nickel based super alloy X-750, and nitrogen strengthened austenitic stainless steel XM-19. A spare core shroud upper support bracket of alloy X-750 was purchased by EPRI from Southern Co. and a section of XM-19 plate was purchased by EPRI from GE-Hitachi. These materials were sectioned at GE Global Research and provided to INL.

  13. Material specification for alloy X-750 for use in LWR (light water reactor) internal components (Revision 1)

    SciTech Connect

    Stein, A.A.; Gennaro, M.S. )

    1990-11-01

    This report presents a review of the stress corrosion cracking behavior of alloy X-750, the alloy chemistry, metallurgy, and mechanical properties as well as an interim material specification developed from these data. The material specification addresses requirements for heat treating, metallurgy, mechanical tests, microstructure, and quality assurance to optimize the stress corrosion resistance of alloy X-750 in light water reactor environments. The specification can be used to effectively identify and screen stress corrosion cracking resistant material. A justification for these specification requirements also is included. This information will enable the utility industry to purchase alloy X-750 in a manner which optimizes its corrosion performance with no degradation of its other properties. 26 refs.

  14. The effect of cooling rate on precipitate morphology in Alloy X-750

    SciTech Connect

    Burke, M.G.; Mager, T.R.; Wilson, I.L.W.

    1992-12-31

    Alloy X-750 bar stock was subjected to the following thermal treatment: 1 h at 1093{degrees}C + 24 h at 718{degrees}C. The effect of water-quenching vs. air-cooling from the solution treatment temperature on the subsequent grain boundary precipitation in the near-surface regions was examined and compared to the bulk microstructures using transmission electron microscopy. It was found that water-quenching produced a deformed austenitic structure which promoted cellular M{sub 23}C{sub 6} precipitation upon subsequent aging. Air-cooling resulted in the formation of very fine discrete M{sub 23}C{sub 6} at grain boundaries which continued to grow during additional aging. Both water-quenched and air-cooled materials passed the orthophosphoric acid etch SCC qualification test.

  15. Grain-boundary structure effects on intergranular stress corrosion cracking of Alloy X-750

    SciTech Connect

    Pan, Y.; Adams, B.L.; Olson, T.; Panayotou, N.

    1996-12-01

    It is well known that the properties and behavior of grain boundaries are strongly affected by local chemistry and atomic structure. This paper focuses on the mesoscale description of grain boundary structure (i.e., the five crystallographic degrees of freedom) and correlations with intergranular stress corrosion cracking observed in Alloy X-750. Orientation imaging microscopy, coupled with serial polishing, is used to reveal mesoscale structure and the connectivity of the grain boundary network. The propensity for cracking is correlated with the coincident site lattice (CSL) classification of grain boundary geometry, coupled with information about the orientation of the grain boundary plane. The data is interpreted to show that low-CSL boundaries (defined by the more restrictive Palumbo-Aust criterion), low-angle boundaries, and general boundaries with plane normals well off the principal stress axis, have low vulnerability to cracking.

  16. Irradiation-assisted stress corrosion cracking of HTH Alloy X-750 and Alloy 625

    SciTech Connect

    Bajaj, R.; Mills, W.J.; Lebo, M.R.; Hyatt, B.Z.; Burke, M.G.

    1995-07-01

    In-reactor testing of bolt-loaded compact tension specimens was performed in 360 C water. New data confirms previous results that high irradiation levels reduce SCC resistance in Alloy X-750. Low boron heats show improved IASCC (irradiation-assisted stress corrosion cracking). Alloy 625 is resistant to IASCC. Microstructural, microchemical, and deformation studies were carried out. Irradiation of X-750 caused significant strengthening and ductility loss associated with formation of cavities and dislocation loops. High irradiation did not cause segregation in X-750. Irradiation of 625 resulted in formation of small dislocation loops and a fine body-centered-orthorhombic phase. The strengthening due to loops and precipitates was apparently offset in 625 by partial dissolution of {gamma} precipitates. Transmutation of boron to helium at grain boundaries, coupled with matrix strengthening, is believed to be responsible for IASCC in X-750, and the absence of these two effects results in superior IASCC resistance in 625.

  17. Microstructural and Microchemical Characterization of Dual Step Aged Alloy X-750 and its Relationship to Environmentally Assisted Cracking

    SciTech Connect

    G.A. Young; N. Lewis; M. Hanson; W. Matuszyk; B. Wiersma; S. Gonzalez

    2001-05-08

    When exposed to deaerated high purity water, Alloy X-750 is susceptible to both high temperature (> 249 C) intergranular stress corrosion cracking (IGSCC) and intergranular low temperature (< 149 C) fracture (LTF). However, the microstructural and microchemical factors that govern environmentally assisted cracking (EAC) susceptibility are poorly understood. The present study seeks to characterize the grain boundary microstructure and microchemistry in order to gain a better mechanistic understanding of stress corrosion crack initiation, crack growth rate, and low temperature fracture. Light microscopy, scanning electron microscopy, transmission electron microscopy, orientation imaging microscopy, scanning Auger microscopy, and thermal desorption spectroscopy were performed on selected heats of Alloy X-750 AH. These data were correlated to EAC tests performed in 338 C deaerated water. Results show that grain boundary MC-type [(Ti,Nb)C] carbides and increased levels of grain boundary phosphorus correlate with an increase in LTF susceptibility but have little effect on the number of initiation sites or the SCC crack growth rate. Thermal desorption data show that multiple hydrogen trapping states exist in Alloy X-750 condition AH. Moreover, it appears that exposure to high temperature (> 249 C), hydrogen deaerated water increases the hydrogen concentration in strong hydrogen trap states and degrades the resistance of the material to low temperature fracture. These findings are consistent with a hydrogen embrittlement based mechanism of LTF where intergranular fracture occurs ahead of a crack tip and is exacerbated by phosphorus segregation to grain boundaries and grain boundary hydrogen trap states.

  18. Effect of irradiation on the stress corrosion cracking behavior of Alloy X-750 and Alloy 625

    SciTech Connect

    Mills, W.J.; Lebo, M.R.; Kearns, J.J.; Hoffman, R.C.; Korinko, J.J.; Luther, R.F.; Sykes, G.B.

    1993-10-01

    In-reactor testing of bolt-loaded precracked and as-notched compact tension specimens was performed in 360{degrees}C water to determine effect of irradiation on SCC of Condition HTH and Condition BH Alloy X-750 and age-hardened Alloy 625. Variables were stress intensity factor (K{sub I}) level, fluence, grade of HTH material, prestraining and material chemistry. Effects of irradiation on high temperature SCC and the rapid cracking that occurs during cooldown below 150{degrees}C were characterized. Significant degradation in the in-reactor SCC resistance of HTH material was observed at initial K{sub I} levels above 30 MPa{radical}m and fluences greater than 10{sup 19} n/cm{sup 2} (E > 1 MeV). A small degradation in SCC resistance of HTH material was observed at low fluences (<10{sup 16} n/cm{sup 2}). As-notched specimens displayed less degradation in SCC resistance than precracked specimens. Prestraining greatly improved in-flux and out-of-flux SCC resistance of HTH material, as little or no SCC was observed in precracked specimens prestrained 20 to 30%, whereas extensive cracking was observed in nonprestrained specimens. Condition HTH heats with low boron (10 ppM or less) had improved in-reactor SCC resistance compared to heats with high and intermediate boron (>20 ppM). Age-hardened Alloy 625 exhibited superior in-reactor SCC behavior compared to HTH material as no crack extension occurred in any of the precracked Alloy 625 specimens tested at initial K{sub I} levels up to 80 MPa{radical}m.

  19. Microstructure and stress corrosion resistance of alloys X-750, 718, and A-286 in LWR environments: Final report

    SciTech Connect

    Miglin, M.T.

    1989-06-01

    The results of microstructural characterization and stress corrosion cracking test are presented for several heat treatment conditions of age-hardenable alloys X-750, 718, and A-286 used for in-core components in light-water reactors. Resistance to intergranular stress corrosion cracking was evaluated using slow-strain-rate tests in pressurized-water-reactor primary water, and microstructural etch and rising-load quality assurance tests. Detailed microstructural characterization of these alloys was performed, and stress corrosion cracking susceptibility is related to microstructural features. Alloy X-750 microstructures with heavy grain boundary coverage by Cr/sub 23/C/sub 6/ show better resistance to stress corrosion cracking in primary water, despite grain boundary chromium depletion. Alloys 718 and A-286 have good resistance to cracking in the slow-strain-rate and quality assurance tests, although neither is immune to cracking in reactor service. Results are compared with those of a related program, including crack initiation and crack growth tests in pressurized-water and boiling-water reactor environments. Recommendations are made for improvements in the quality assurance tests and in heat treatment for alloy 718. 29 refs., 15 figs., 9 tabs.

  20. Hydrogen embrittlement, grain boundary segregation, and stress corrosion cracking of alloy X-750 in low- and high-temperature water

    SciTech Connect

    Mills, W. J.; Lebo, M. R.; Kearns, J. J.

    1997-04-01

    The nature of intergranular stress corrosion cracking (SCC) of alloy X-750 was characterized in low- and high-temperature water by testing as-notched and precracked fracture mechanics specimens. Materials given the AH, BH, and HTH heat treatments were studied. While all heat treatments were susceptible to rapid low-temperature crack propagation (LTCP) below 150 C, conditions AH and BH were particularly susceptible. Low-temperature tests under various loading conditions (e.g., constant displacement, constant load, and increasing load) revealed that the maximum stress intensity factors (K{sub P{sub max}}) from conventional rising load tests provide conservative estimates of the critical loading conditions in highly susceptible heats, regardless of the load path history. For resistant heats, K{sub P{sub max}} provides a reasonable, but not necessarily conservative, estimate of the critical stress intensity factor for LTCP. Testing of as-notched specimens showed that LTCP will not initiate at a smooth surface or notch, but will readily occur if a cracklike defect is present. Comparison of the cracking response in water with that for hydrogen-precharged specimens tested in air demonstrated that LTCP is associated with hydrogen embrittlement of grain boundaries. The stress corrosion crack initiation and growth does occur in high-temperature water (>250 C), but crack growth rates are orders of magnitude lower than LTCP rates. The SCC resistance of HTH heats is far superior to that of AH heats as crack initiation times are two to three orders of magnitude greater and growth rates are one to two orders of magnitude lower.

  1. Susceptibility of Inconel X-750 to stress corrosion cracking

    SciTech Connect

    Mishra, B.

    1986-01-01

    High strength, age hardenable Ni-base superalloy Inconel X-750 in susceptible to severe intergranular stress corrosion cracking (IGSCC) when used in the triple heat treated condition. In this research, constant strain rate technique was employed to evaluate the stress corrosion cracking susceptibility of alloy X-750 under simulated pressurized water reactor conditions in a nuclear power plant using an automated autoclave system at 8 x 10/sup 6/ N/m/sup 2/ pressure and 289/sup 0/C temperature. The alloy produced via ESR and VAR processing routes containing .004% and .011% sulfur, respectively, were solution annealed at 1075 and 1240/sup 0/C for 2 hours and water quenched followed by aging in the 704 to 871/sup 0/C temperature range up to 200 hours and cooled in air as well as the furnace. Complete grain boundary chemistry and precipitation morphology was studied, supported by observations made using Charpy impact and modified Huey tests. Results showed Inconel X-750 processed through electroslag refining, solution annealed at 1240/sup 0/C for 2 hours and water quenched followed by aging at 871/sup 0/C for 200 hours and furnace cooling, provides the best combination of strength, ductility, and resistance to SCC.

  2. Microfissuring of Inconel 718

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.

    1983-01-01

    A tentative mathematical computer model of the microfissuring process during electron beam welding of Inconel 718 has been constructed. Predictions of the model are compatible with microfissuring tests on eight 0.25-in. thick test plates. The model takes into account weld power and speed, weld loss (efficiency), parameters and material characteristics. Besides the usual material characteristics (thermal and strength properties), a temperature and grain size dependent critical fracture strain is required by the model. The model is based upon fundamental physical theory (i.e., it is not a mere data interpolation system), and can be extended to other metals by suitable parameter changes.

  3. Machinability studies on INCONEL 718

    NASA Astrophysics Data System (ADS)

    Xavior, M. Anthony; Patil, Mahesh; Maiti, Abheek; Raj, Mrinal; Lohia, Nitesh

    2016-09-01

    The main objective of proposed work is to determine the influence of controllable parameters on machining characteristics of Inconel-718 and to achieve the optimum parameters for sustainable and efficient turning. Understanding the consequences of advanced tool materials together with higher cutting speeds on the formation of residual stresses and therefore the underlying mechanisms of small structural alteration within the subterranean layer thereby becomes terribly crucial for predicting product quality and more optimizing the machining conditions. Controllable cutting parameters such as cutting velocity, feed rate and depth of cut were selected at different level for experimentations in accordance with the Taguchi L9 array method using Minimum Quantity Lubrication (MQL) cutting condition and three different tools namely PVD TiAlN carbide, Cubic boron nitride and ceramic. Extensive study is done on the resulting surface roughness, surface subsurface hardness, tool wear and chip morphology. The results obtained from each of the tool were thoroughly analyzed and finally the optimized parameters are obtained for efficient machining of Inconel 718.

  4. INCONEL 718: A solidification diagram

    NASA Astrophysics Data System (ADS)

    Knorovsky, G. A.; Cieslak, M. J.; Headley, T. J.; Romig, A. D.; Hammetter, W. F.

    1989-10-01

    As part of a program studying weldability of Ni-base superalloys, results of an integrated analytical approach are used to generate a constitution diagram for INCONEL 718* in the temperature range associated with solidification. Differential thermal analysis of wrought material and optical and scanning electron microscopy, electron probe microanalysis, and analytical electron microscopy of gas tungsten arc welds are used in conjunction with solidification theory to generate data points for this diagram. The important features of the diagram are an austenite (γ)/Laves phase eutectic which occurs at ≈19.1 wt pct Nb between austenite containing ≈9.3 wt pct Nb and a Laves phase which contains ≈22.4 wt pct Nb. The distribution coefficient for Nb was found to be ≈0.5. The solidification sequence of INCONEL 718 was found to be (1) proeutectic γ, followed by (2) a γ/NbC eutectic at ≈1250°C, followed by (3) continued γ solidification, followed by (4) a γ/Laves phase eutectic at ≈1200°C. An estimate of the volume fraction eutectic is made using the Scheil solidification model, and the fraction of each phase in the eutectic is calculated via the lever rule. These are compared with experimentally determined values and found to be in good agreement.

  5. Strain energy density: Distance criterion for the initiation of hydrogen-induced cracking of Alloy X-750

    SciTech Connect

    Hall, M.M. Jr.; Symons, D.M.; Kearns, J.J.

    1991-12-31

    A criterion for initiation of subcritical crack growth at blunt notches and sharp defects was developed and applied to hydrogen- induced cracking of the Ni-base superalloy X-750. Onset of crack growth is shown to occur when a critical strain energy density is attained at a distance from the notch and crack tips characteristic of the microstructure along the prospective crack path. Rising load crack growth initiation data were obtained using homogeneous hydrogen precharged notched and fatigue precracked bend specimens. Notch root radius, grain size and hydrogen concentration were varied. Crack growth initiation loads were dependent on both notch root radius and bulk precharged hydrogen concentration. These data were shown to be correlated using a critical strain energy at-a-distance (SEDAD) criterion. Furthermore, an elastic-plastic analysis of the strain energy distributions showed that the critical strain energy density value is attained at one grain diameter from the notch and fatigue precrack tips. Mechanical and microstructural aspects of crack growth process and relevance to hydrogen-induced cracking are discussed.

  6. Improved nickel plating of Inconel X-750

    NASA Technical Reports Server (NTRS)

    Farmer, M. E.; Feeney, J. E.; Kuster, C. A.

    1969-01-01

    Electroplating technique with acid pickling provides a method of applying nickel plating on Inconel X-750 tubing to serve as a wetting agent during brazing. Low-stress nickel-plating bath contains no organic wetting agents that cause the nickel to blister at high temperatures.

  7. Corrosion Performance of Inconel 625 in High Sulphate Content

    NASA Astrophysics Data System (ADS)

    Ismail, Azzura

    2016-05-01

    Inconel 625 (UNS N06625) is a type of nickel-chromium-molybdenum alloy with excellent corrosion resistance in a wide range of corrosive media, being especially resistant to pitting and crevice corrosion. However, in aggressive environment, Inconel 625 will suffer corrosion attack like other metals. This research compared the corrosion performance of Inconel 625 when exposed to higher sulphate content compared to real seawater. The results reveal that Inconel 625 is excellent in resist the corrosion attack in seawater. However, at increasing temperature, the corrosion resistance of this metal decrease. The performance is same in seawater with high sulphate content at increasing temperature. It can be concluded that sulphate promote perforation on Inconel 625 and become aggressive agents that accelerate the corrosion attack.

  8. Microstructural aspects in Inconel X-750

    SciTech Connect

    Sinha, A.K.

    1984-01-01

    The precipitation hardened Inconel X-750 is extensively used in both PWR and BWR as bolts, pins, spring components, etc., mainly because of this alloy's excellent high temperature strength and good oxidation and corrosion resistance. However, this alloy has experienced some intergranular stress corrosion cracking. It has been reported that the SCC resistance of Inconel X-750 can be improved by direct aging in the precipitation regime of 704 to 871/sup 0/C. Therefore, the microstructural changes that occur when Inconel X-750 is thermally treated between 704/sup 0/C and 871/sup 0/C for up to 200 hours following a 2-hour solution anneal at 1075/sup 0/C, or 1149/sup 0/C, or 1204/sup 0/C has been studied. Optical, transmission electron, and scanning and Auger electron microscopy were used in order to establish the most appropriate aging sequence for this alloy which will produce a suitable precipitation morphology and distribution of secondary carbides and intermetallics. The precipitation morphology and analysis of ..gamma..' (L1/sub 2/), secondary M/sub 23/C/sub 6/ and primary MC carbide phases for each heat treatment cycle were studied using TEM techniques. The coarsening kinetics of the ..gamma..' particle growth obeyed the time-law prediction of Lipshitz-Slazor-Wagner theory of diffusion controlled growth at all aging temperatures. The ..gamma..' precipitate lost coherency by the nucleation of dislocation loops within the precipitate, the interaction of dislocation at the interface and attraction of matrix dislocations to the particle/matrix interface.

  9. Hot tensile tests of Inconel 718

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The physical metallurgy of near-solidus integranular cracking in Inconel 718 welds was investigated. The data, although inconclusive, suggest at least two mechanisms which might explain intergranular cracking (microfissuring) in the heat-affected zone of several high temperature alloys. One theory is based on the separation of intergranular liquid while the other involves mechanical failure of solid ligaments surrounded by intergranular liquid. Both mechanisms concentrate strain in the grain boundaries resulting in low strain (1%) intergranular brittleness. The mechanisms reported might also pertain to the physical metallurgy of casting, powder metallurgy sintering and hot isostatic pressing.

  10. Cold Spray Forming of Inconel 718

    NASA Astrophysics Data System (ADS)

    Wong, W.; Irissou, E.; Vo, P.; Sone, M.; Bernier, F.; Legoux, J.-G.; Fukanuma, H.; Yue, S.

    2013-03-01

    Inconel 718 was cold spray formed to a 6-mm thickness on an 8-cm diameter aluminum alloy tube using Sulzer Amdry 1718 powder and the Plasma Giken PCS-1000 cold spray system. The effects of spray particle velocity and post-spray heat treatment were studied. Post-spray annealing was performed from 950 to 1250 °C for 1-2 h. The resulting microstructures as well as the corresponding mechanical properties were characterized. As-sprayed coatings exhibited very low ductility. The tensile strength and ductility of the heat-treated coatings were improved to varying levels depending on the heat-treatment and spray conditions. For coatings sprayed at higher particle velocity and heat treated at 1250 °C for 1 h, an elongation of 24% was obtained. SEM micrographs showed a higher fraction of interparticle metallurgical bonds due to some sintering effect. Corresponding fracture surfaces also revealed a higher fraction of dimple features, typically associated with ductile fracture, in the annealed coatings. The results demonstrate that cold spray forming of Inconel 718 is feasible, and with appropriate heat treatment, metallurgical bonding can be increased. The ductility of the spray-formed samples was comparable to that of the bulk material.

  11. Creep and relaxation behavior of Inconel-617

    SciTech Connect

    Osthoff, W.; Ennis, P.J.; Nickel, H.; Schuster, H.

    1984-08-01

    The static and dynamic creep behavior of Inconel alloy 617 has been determined in constant load creep tests, relaxation tests, and stress reduction tests in the temperature range 1023 to 1273 K. The results have been interpreted using the internal stress concept: The dependence of the internal stress on the applied stress and test temperature was determined. In a few experiments, the influence of cold deformation prior to the creep test on the magnitude of the internal stress was also investigated. It was found that the experimentally observed relaxation behavior could be more satisfactorily described using the Norton creep equation modified by incorporation of the internal stress than by the conventional Norton creep equation.

  12. Superplastic forming of INCONEL alloy 718SPF

    NASA Astrophysics Data System (ADS)

    Smith, Gaylord D.; Yates, Daniel H.

    The hot gas path temperatures of most aircraft turbine components exceed the temperature limits of aluminum- and titanium-based alloys presently used for superplastic forming (SPF). Because of the clear design and cost benefits associated with SPE the need for an alloy with a substantially higher temperature capability is evident. This paper demonstrates that INCONEL alloy 718SPF meets this challenge. The SPF parameters of temperature, flow stress, and strain rate are presented as well as the elongations to failure. Post-SPF tensile properties are compared to the original sheet values in both the as-processed and as-processed plus heat treated condition. The degree of cavitation is assessed as a function of percent engineering strain at typical commercial strain rates and the role of cavitation growth by diffusion is indicated.

  13. Supersolidus Liquid Phase Sintering Modeling of Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Levasseur, David; Brochu, Mathieu

    2016-02-01

    Powder metallurgy of Inconel 718 superalloy is advantageous as a near-net shape process for complex parts to reduce the buy-to-fly ratio and machining cost. However, sintering Inconel 718 requires the assistance of supersolidus liquid formation to achieve near full density and involves the risk of distortion at high temperatures. The present work is focused on modeling the onset of sintering and distortion as a function of temperature, grain size, and part geometry for Inconel 718. Using experimental sintering results and data available in the literature, the supersolidus liquid phase sintering of Inconel 718 was modeled. The model was used to define a processing window where part distortion would be avoided.

  14. Increasing the Useful Life of Quench Reliefs with Inconel Bellows

    SciTech Connect

    Soyars, W. M.

    1999-01-01

    Reliable quench relief valves are an important part of superconducting magnet systems. Fermilab developed bellows-actuated cryogenic quench reliefs which have been in use since the early l 980's. The original design uses a stainless steel bellows. A high frequency, low amplitude vibration during relieving events has resulted in fatigue failures in the original design. To take advantage of the improved resistance to fatigue of Inconel, a nickel-chromium alloy, reliefs using Inconel 625 bellows were made. Design, development, and testing of the new version reliefs will be discussed. Tests show that relief valve lifetimes using Inconel bellows are more than five times greater than when using the original stainless steel bellows. Inconel bellows show great promise in increasing the lifetime of quench relief valves, and thus the reliability of accelerator cryogenic systems.

  15. Stress relaxation in irradiated INCONEL X750 springs

    SciTech Connect

    Allen, T.R.; Cole, J.I.

    1999-09-01

    Because INCONEL X750 is used as a spring and bolting material in light water reactors, it is important to understand its stress relaxation behavior as a function of irradiation dose and aging temperature. This work reports the stress relaxation characteristics of INCONEL X750 irradiated at 375 to 415C to doses up to 20 dpa and thermally aged at 371 C for 6525 days. These measurements are an extension of stress relaxation measurements reported in Refs. 1 and 2.

  16. Magnetic susceptibility of Inconel alloys 718, 625, and 600 at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Goldberg, Ira B.; Mitchell, Michael R.; Murphy, Allan R.; Goldfarb, Ronald B.; Loughran, Robert J.

    1990-01-01

    After a hydrogen fuel bleed valve problem on the Discovery Space Shuttle was traced to the strong magnetization of Inconel 718 in the armature of the linear variable differential transformer near liquid hydrogen temperatures, the ac magnetic susceptibility of three samples of Inconel 718 of slightly different compositions, one sample of Inconel 625, and on sample of Inconel 600 were measured as a function of temperature. Inconel 718 alloys are found to exhibit a spin glass state below 16 K. Inconel 600 exhibits three different magnetic phases, the lowest-temperature state (below 6 K) being somewhat similar to that of Inconel 718. The magnetic states of the Inconel alloys and their magnetic susceptibilities appear to be strongly dependent on the exact composition of the alloy.

  17. Circular Vibration Planing of Inconel 718

    NASA Astrophysics Data System (ADS)

    Hettiarachchi, Nandita Kalyanakumara; Moriwaki, Toshimichi; Shibasaka, Toshiro; Nakamoto, Keiichi

    Circular vibration milling (CVM) is achieved by vibrating a milling cutter about the machine tool spindle axis in a circular path, in addition to its rotary motion. CVM has been proven capable of producing better surface finishes on difficult to cut materials. However, the CVM process is far slower than conventional milling process. In circular vibration planing (CVP) process, the cutting tool is clamped without rotation and fed at a speed comparable to the feed speed of conventional milling. By superimposing circular vibration motion, necessary cutting speed could be achieved keeping the feed speed at realistic values. Inconel 718 was machined by CVP and conventional milling at a similar feed rate. It was observed that CVP could reduce tool wear and hence produce better surface finishes than conventional milling. A geometric simulation showed a major difference between uncut chip shapes of the two processes. The difference of uncut chip shapes suggests that in CVP process, less rubbing occurs between tool flank face and work before the tool penetrates in to the work to form a chip. The reduced rubbing of the flank face is proposed as the reson for reduced tool wear in CVP when compared with conventional milling.

  18. Corrosion Test Results for Inconel 600 vs Inconel-Stainless UG Bellows

    SciTech Connect

    Osborne, P.E.

    2002-09-11

    The Conversion Project (CP) of the Molten Salt Reactor Experiment at Oak Ridge National Laboratory (ORNL) involves converting slightly less than 40 kg of {sup 233}U to a stable form for safe storage. The operation is performed within a few vessels interconnected by valves and 1/2-in. metal tubing. During this conversion, a particularly toxic and corrosive by-product is formed, namely aqueous hydrofluoric acid (HF). The production of HF is a result of the hydrolysis of UF{sub 6} and subsequent steam treatments of UO{sub 2}F{sub 2}. For each mole of UF{sub 6} converted, 6 mol of HF are produced. The HF that forms during conversion combines with water to produce approximately 1.5 L of 33 wt % HF. As this mixture is transferred within the process system, the tubing and valves are exposed to high concentrations of HF in liquid and vapor form. Of particular concern in the system are the almost 30 valves that have the potential for exposure to HF. For these valves, a vendor-supplied UG valve was installed. UG valves consist of an Alloy 400 (Monel) body and stem tip and Alloy 600 (Inconel) bellows. These valves have been used under experimental conditions that simulate the CP. It has been established that they have a finite life when exposed to a HF and air environment. Most failures were seen around the flange at the bottom of the bellows, and it was suspected that this flange and the weld material were not Inconel. In December 2001, the vendor confirmed that this flange was not Inconel but instead was stainless steel 316. After discussions between the vendor and ORNL staff involved with the CP effort, it was decided that the entire wetted area of the bellows would be fabricated from Alloy 600. In March 2002, four newly fabricated bellows assemblies were received from the vendor for the purposes of corrosion testing in HF. This report presents results from the corrosion tests conducted to determine if the new design of the bellows would enhance their corrosion resistance.

  19. Studies on Laser Generated Ultrasonic Waves in Inconel Super Alloy

    SciTech Connect

    Pramila, T.; Shukla, Anita; Raghuram, V.

    2010-05-28

    This paper deals with the generation, characterization and analysis of ultrasonic waves generated in a thick stepped sample of inconel super alloy using Laser Based Ultrasonic Technique. Nd-YAG pulsed laser is used for ultrasonic generation while He-Ne laser is used for heterodyne detection. Ultrasonic signals are analyzed using Fourier and wavelet transforms. Here the identification and estimation of velocity of pressure waves is presented. The mechanism of pressure wave generation is discussed in brief. Laser ultrasonics studies of inconel are being reported for the first time.

  20. Tensile and fatigue properties of Inconel 718 at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Malin, C. O.; Schmidt, E. H.

    1969-01-01

    Tests to determine the tensile and fatigue properties of Inconel 718 at cryogenic temperatures show that the alloy increases in strength at low temperatures, with very little change in toughness. The effect of surface finish and grain size on the fatigue properties was also determined.

  1. Asbestos and Inconel combined to form hot-gas seal

    NASA Technical Reports Server (NTRS)

    Wooster, C. W., Jr.

    1968-01-01

    Hot-gas seal prevents warpage tendencies in large flange joints exposed to high temperatures, such as those present in large space vehicle engine exhausts. Two Inconel wire mesh cores are held in place by an asbestos cloth cover that acts as a spacer to form the seal.

  2. Further Study of near Solidus Intergranular Cracking in Inconel 718

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.

    1981-01-01

    A series of tests, performed to determine the strain necessary to initiate intergranular cracking in Inconel 718 as a function of temperature, contained enough scatter near the melting temperature that questions remained as to the best curve of curves to fit to the data. Fracture surface analysis showed that the scatter was due to incipient melting in the grain boundary region. The melting contributed to low fracture strain but had only a small on the incipient cracking strain. Gleeble tests, which could be interrupted by water quenching, were used to study the incipient intergranular melting of Inconel 718. This modified weld simulation test provided a sufficiently rapid quench to preserve the intergranular microstructure created during incipient melting. This structure was studied both microscopically and with energy dispensive X-ray analysis. The implications of incipient melting and low-strain incipient cracking on the development of microfissuring envelopes are discussed.

  3. Nonlinear acoustics experimental characterization of microstructure evolution in Inconel 617

    SciTech Connect

    Yao, Xiaochu; Liu, Yang; Lissenden, Cliff J.

    2014-02-18

    Inconel 617 is a candidate material for the intermediate heat exchanger in a very high temperature reactor for the next generation nuclear power plant. This application will require the material to withstand fatigue-ratcheting interaction at temperatures up to 950°C. Therefore nondestructive evaluation and structural health monitoring are important capabilities. Acoustic nonlinearity (which is quantified in terms of a material parameter, the acoustic nonlinearity parameter, β) has been proven to be sensitive to microstructural changes in material. This research develops a robust experimental procedure to track the evolution of damage precursors in laboratory tested Inconel 617 specimens using ultrasonic bulk waves. The results from the acoustic non-linear tests are compared with stereoscope surface damage results. Therefore, the relationship between acoustic nonlinearity and microstructural evaluation can be clearly demonstrated for the specimens tested.

  4. Tritium Permeability of Incoloy 800H and Inconel 617

    SciTech Connect

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2011-09-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950 C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm) - three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  5. Tritium Permeability of Incoloy 800H and Inconel 617

    SciTech Connect

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2012-07-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950°C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm)—three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  6. Creep-rupture tests of internally pressurized Inconel 702 tubes

    NASA Technical Reports Server (NTRS)

    Gumto, K. H.

    1973-01-01

    Seamless Inconel 702 tubes with 0.375-in. outside diameter and 0.025-in. wall thickness were tested to failure at temperatures from 1390 to 1575 F and internal helium pressures from 700 to 1800 psi. Lifetimes ranged from 29 to 1561 hr. The creep-rupture strength of the tubes was about 70 percent lower than that of sheet specimens. Larson-Miller correlations and photomicrographs of some specimens are presented.

  7. Modeling the viscoplastic behavior of Inconel 718 at 1200 F

    NASA Technical Reports Server (NTRS)

    Abdel-Kader, M. S.; Eftis, J.; Jones, D. L.

    1988-01-01

    A large number of tests, including tensile, creep, fatigue, and creep-fatigue were performed to characterize the mechanical properties of Inconel 718 (a nickel based superalloy) at 1200 F, the operating temperature for turbine blades. In addition, a few attempts were made to model the behavior of Inconel 718 at 1200 F using viscoplastic theories. The Chaboche theory of viscoplasticity can model a wide variety of mechanical behavior, including monotonic, sustained, and cyclic responses of homogeneous, initially-isotropic, strain hardening (or softening) materials. It is shown how the Chaboche theory can be used to model the viscoplastic behavior of Inconel 718 at 1200 F. First, an algorithm was developed to systematically determine the material parameters of the Chaboche theory from uniaxial tensile, creep, and cyclic data. The algorithm is general and can be used in conjunction with similar high temperature materials. A sensitivity study was then performed and an optimal set of Chaboche's parameters were obtained. This study has also indicated the role of each parameter in modeling the response to different loading conditions.

  8. On Electro Discharge Machining of Inconel 718 with Hollow Tool

    NASA Astrophysics Data System (ADS)

    Rajesha, S.; Sharma, A. K.; Kumar, Pradeep

    2012-06-01

    Inconel 718 is a nickel-based alloy designed for high yield, tensile, and creep-rupture properties. This alloy has been widely used in jet engines and high-speed airframe parts in aeronautic application. In this study, electric discharge machining (EDM) process was used for machining commercially available Inconel 718. A copper electrode with 99.9% purity having tubular cross section was employed to machine holes of 20 mm height and 12 mm diameter on Inconel 718 workpieces. Experiments were planned using response surface methodology (RSM). Effects of five major process parameters—pulse current, duty factor, sensitivity control, gap control, and flushing pressure on the process responses—material removal rate (MRR) and surface roughness (SR) have been discussed. Mathematical models for MRR and SR have been developed using analysis of variance. Influences of process parameters on tool wear and tool geometry have been presented with the help of scanning electron microscope (SEM) micrographs. Analysis shows significant interaction effect of pulse current and duty factor on MRR yielding a wide range from 14.4 to 22.6 mm3/min, while pulse current remains the most contributing factor with approximate changes in the MRR and SR of 48 and 37%, respectively, corresponding to the extreme values considered. Interactions of duty factor and flushing pressure yield a minimum surface roughness of 6.2 μm. The thickness of the sputtered layer and the crack length were found to be functions of pulse current. The hollow tool gets worn out on both the outer and the inner edges owing to spark erosion as well as abrasion due to flow of debris.

  9. Characterization of Strain-Induced Precipitation in Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Calvo, Jessica; Penalva, Mariluz; Cabrera, José María

    2016-06-01

    Inconel 718 presents excellent mechanical properties at high temperatures, as well as good corrosion resistance and weldability. These properties, oriented to satisfy the design requirements of gas turbine components, depend on microstructural features such as grain size and precipitation. In this work, precipitation-temperature-time diagrams have been derived based on a stress relaxation technique and the characterization of precipitates by scanning electron microscopy. By using this methodology, the effect of strain accumulation during processing on the precipitation kinetics can be determined. The results show that the characteristics of precipitation are significantly modified when plastic deformation is applied, and the kinetics are slightly affected by the amount of total plastic deformation.

  10. Diffusion of Hydrogen and Helium in Inconel 625

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Gillies, D.; Lehoczky, S.

    2006-01-01

    Diffusion parameters for hydrogen and helium in Inconel 625 were investigated. The dependence of permeability of hydrogen in the temperature range 310 - 750 C is given. Solubility of hydrogen at 1 atm in the range 640 - 860 C was determined and diffusivity of the gas was calculated. Experiments with diffusion and solubility at 0.09 atm suggest a molecular mechanism of solution of hydrogen in the material. Diffusivity of helium was estimated at less than 10(exp -18) sq cm/s (at 1040 C).

  11. Characterization of Strain-Induced Precipitation in Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Calvo, Jessica; Penalva, Mariluz; Cabrera, José María

    2016-08-01

    Inconel 718 presents excellent mechanical properties at high temperatures, as well as good corrosion resistance and weldability. These properties, oriented to satisfy the design requirements of gas turbine components, depend on microstructural features such as grain size and precipitation. In this work, precipitation-temperature-time diagrams have been derived based on a stress relaxation technique and the characterization of precipitates by scanning electron microscopy. By using this methodology, the effect of strain accumulation during processing on the precipitation kinetics can be determined. The results show that the characteristics of precipitation are significantly modified when plastic deformation is applied, and the kinetics are slightly affected by the amount of total plastic deformation.

  12. Cold-Worked Inconel(R) 718 Bars

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1988-01-01

    Cold working and double aging yield high strength without sacrifice of resistance to corrosion. Report presents data on mechanical properties and stress-corrosion resistance of triple-melted, solution-treated, work-strengthened, direct-double-aged Inconel(R) 718 alloy. Triple melting consists of vacuum induction melting, electro-slag remelting, and vacuum arm remelting. Data indicate advance in processing of large-diameter bars. New process increases yield strength without reducing the elongation, reduction of area, and grain size.

  13. Surface Integrity of Inconel 718 by Ball Burnishing

    NASA Astrophysics Data System (ADS)

    Sequera, A.; Fu, C. H.; Guo, Y. B.; Wei, X. T.

    2014-09-01

    Inconel 718 has wide applications in manufacturing mechanical components such as turbine blades, turbocharger rotors, and nuclear reactors. Since these components are subject to harsh environments such as high temperature, pressure, and corrosion, it is critical to improve the functionality to prevent catastrophic failure due to fatigue or corrosion. Ball burnishing as a low plastic deformation process is a promising technique to enhance surface integrity for increasing component fatigue and corrosion resistance in service. This study focuses on the experimental study on surface integrity of burnished Inconel 718. The effects of burnishing ball size and pressure on surface integrity factors such as surface topography, roughness, and hardness are investigated. The burnished surfaces are smoother than the as-machined ones. Surface hardness after burnishing is higher than the as-machined surfaces, but become stable over a certain burnishing pressure. There exists an optimal process space of ball sized and burnishing pressure for surface finish. In addition, surface hardness after burnishing is higher than the as-machined surfaces, which is confirmed by statistical analysis.

  14. Structure-Property Correlations in Microwave Joining of Inconel 718

    NASA Astrophysics Data System (ADS)

    Bansal, Amit; Sharma, Apurbba Kumar; Kumar, Pradeep; Das, Shantanu

    2015-09-01

    The butt joining of Inconel 718 plates at 981°C solution treated and aged (981STA) condition was carried out using the microwave hybrid heating technique with Inconel 718 powder as a filler material. The developed joints were free from any microfissures (cracks) and were metallurgically bonded through complete melting of the powder particles. The as-welded joints were subjected to postweld heat treatments, including direct-aged, 981STA and 1080STA. The microstructural features of the welded joints were investigated using a field emission-scanning electron microscope equipped with x-ray elemental analysis. Microhardness and room-temperature tensile properties of the welded joints were evaluated. The postweld heat-treated specimens exhibited higher microhardness and tensile strength than the as-welded specimens due to the formation of strengthening precipitates in the microstructure after postweld heat treatments. The microhardness of the fusion zone of the joint in 1080STA condition was higher than all welded conditions due to the complete dissolution of Laves phase after 1080STA treatment. However, the tensile strength of the welded specimen in 981STA condition was higher than all welded conditions. The tensile strength in 1080STA condition was lower than that in 981STA condition because of the grain coarsening that took place after 1080STA condition. The fractography of the fractured surfaces was carried out to determine the structure-property-fracture correlation.

  15. Characterization of microstructures and mechanical properties of Inconel 617/310 stainless steel dissimilar welds

    SciTech Connect

    Shah Hosseini, H. Shamanian, M.; Kermanpur, A.

    2011-04-15

    The microstructure and mechanical properties of Inconel 617/310 austenitic stainless steel dissimilar welds were investigated in this work. Three types of filler materials, Inconel 617, Inconel 82 and 310 austenitic stainless steels were used to obtain dissimilar joint using the gas tungsten arc welding process. Microstructural observations showed that there was no evidence of any possible cracking in the weldments achieved by the nickel-base filler materials. The welds produced by 617 and 310 filler materials displayed the highest and the lowest ultimate tensile strength and total elongation, respectively. The impact test results indicated that all specimens exhibited ductile fracture. Among the fillers, Inconel 617 exhibited superlative fracture toughness (205 J). The mechanical properties of the Inconel 617 filler material were much better than those of other fillers. - Research Highlights: {yields} A fine dendritic structure was seen for the Inconel 617 weld metal. {yields} A number of cracks were initiated when the 310 SS filler metal was used. {yields} All welded samples showed ductile fracture. {yields} The Inconel 617 filler material presents the optimum mechanical properties.

  16. The effect of laser pulse tailored welding of Inconel 718

    NASA Technical Reports Server (NTRS)

    Mccay, T. Dwayne; Mccay, Mary Helen; Sharp, C. Michael; Womack, Michael G.

    1990-01-01

    Pulse tailored laser welding has been applied to wrought, wrought grain grown, and cast Inconel 718 using a CO2 laser. Prior to welding, the material was characterized metallographically and the solid state transformation regions were identified using Differential Scanning Calorimetry and high temperature x-ray diffraction. Bead on plate welds (restrained and unrestrained) were then produced using a matrix of pulse duty cycles and pulsed average power. Subsequent characterization included heat affected zone width, penetration and underbead width, the presence of cracks, microfissures and porosity, fusion zone curvature, and precipitation and liquated region width. Pedigree welding on three selected processing conditions was shown by microstructural and dye penetrant analysis to produce no microfissures, a result which strongly indicates the viability of pulse tailored welding for microfissure free IN 718.

  17. Thermal-mechanical fatigue crack growth in Inconel X-750

    NASA Technical Reports Server (NTRS)

    Marchand, N.; Pelloux, R. M.

    1984-01-01

    Thermal-mechanical fatigue crack growth (TMFCG) was studied in a gamma-gamma' nickel base superalloy Inconel X-750 under controlled load amplitude in the temperature range from 300 to 650 C. In-phase (T sub max at sigma sub max), out-of-phase (T sub min at sigma sub max), and isothermal tests at 650 C were performed on single-edge notch bars under fully reversed cyclic conditions. A dc electrical potential method was used to measure crack length. The electrical potential response obtained for each cycle of a given wave form and R value yields information on crack closure and crack extension per cycle. The macroscopic crack growth rates are reported as a function of delta k and the relative magnitude of the TMFCG are discussed in the light of the potential drop information and of the fractographic observations.

  18. Grain boundary segregation of boron in INCONEL 718

    NASA Astrophysics Data System (ADS)

    Chen, W.; Chaturvedi, M. C.; Richards, N. L.; McMahon, G.

    1998-07-01

    The segregation behavior of boron at grain boundaries in two INCONEL 718+ based alloys with different B concentrations was studied. The alloys, one containing 11 ppm of B and the other 43 ppm, were homogenized at 1200 °C for 2 hours followed by water quenching and air cooling. A strong segregation of boron at grain boundaries was observed using secondary ion mass spectrometry after the heat treatment in both the alloys. The segregation was found mainly to be of nonequilibrium type. The homogenized samples were also annealed at 1050 °C for various lengths of time. During annealing, boride particles were observed to first form at grain boundaries and then to dissolve on continued annealing at 1050 °C. The mechanisms of segregation and desegregation of B are discussed.

  19. Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740

    SciTech Connect

    Ludtka, G.M.; Smith, G.

    2007-11-19

    In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.

  20. Effects of Internal and External Hydrogen on Inconel 718

    NASA Technical Reports Server (NTRS)

    Walter, R. J.; Frandsen, J. D.

    1999-01-01

    Internal hydrogen embrittlement (IHE) and hydrogen environment embrittlement (HEE) tensile and bend crack growth tests were performed on Inconel 718. For the IHE tests, the specimens were precharged to approximately 90 ppm hydrogen by exposure to 34.5 MPa H2 at 650 C. The HEE tests were performed in 34.5 MPa H2. Parameters evaluated were test temperature, strain rate for smooth and notch specimen geometries. The strain rate effect was very significant at ambient temperature for both IHE and HEE and decreased with increasing temperatures. For IHE, the strain rate effect was neglible at 260'C, and for HEE the strain rate effect was neglible at 400 C. At low temperatures, IHE was more severe than HEE, and at high temperatures HEE was more severe than IHE with a cross over temperature about 350 C. At 350 C, the equilibrium hydrogen concentration in Inconel 718 is about 50% lower than the hydrogen content of the precharged IHE specimens. Dislocation hydrogen sweeping of surface absorbed hydrogen was the likely transport mechanism for increasing the hydrogen concentration in the HEE tests sufficiently to produce the same degree of embrittlement as that of the more highly hydrogen charged IHE specimens. The main IHE fracture characteristic was formation of large, brittle flat facets, which decreased with increasing test temperature. The IHE fracture matrix surrounding the large facets ranged between brittle fine faceted to microvoid ductility depending upon strain rate, specimen geometry as well as temperature. The HEE fractures were characteristically fine featured, transgranular and brittle with a significant portion forming a "saw tooth" crystallographic pattern. Both IHE and HEE fractures were predominantly along the {1 1 1) slip and twin boundaries. With respect to embrittlement mechanism, it was postulated that dislocation hydrogen sweeping and hydrogen enhanced localized plasticity were active in HEE and IHE for concentrating hydrogen along (1 1 1) slip and twin

  1. Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of

  2. Experimental Investigations during Dry EDM of Inconel - 718

    NASA Astrophysics Data System (ADS)

    BHANDARE, A. S.; DABADE, U. A.

    2016-02-01

    Dry EDM is a modification of the conventional EDM process in which the liquid dielectric is replaced by a gaseous medium. Tubular tool electrodes are used and as the tool rotates, high velocity gas is supplied through it into the discharge gap. The flow of high velocity gas into the gap facilitates removal of debris and prevents excessive heating of the tool and work piece at the discharge spots. It is now known that apart from being an environment- friendly process, other advantages of the dry EDM process are low tool wear, lower discharge gap, lower residual stresses, smaller white layer and smaller heat affected zone. Keeping literature review into consideration, in this paper, an attempt has been made by selecting compressed air as a dielectric medium, with Inconel - 718 as a work piece material and copper as a tool electrode. Experiments are performed using Taguchi DoE orthogonal array to observe and analyze the effects of different process parameters to optimize the response variables such as material removal rate (MRR), surface roughness (Ra) and tool wear rate (TWR). In the current work, a unit has been developed to implement dry EDM process on existing oil based EDM machine.

  3. Hydrostatic Stress Effect On the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2002-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has no effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of notched geometries. New experiments and nonlinear finite element analyses (FEA) of Inconel 100 (IN 100) equal-arm bend and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions was performed. In all test cases, the von Mises constitutive model, which is independent of hydrostatic pressure, overestimated the load for a given displacement or strain. Considering the failure displacements or strains, the Drucker-Prager FEMs predicted loads that were 3% to 5% lower than the von Mises values. For the failure loads, the Drucker Prager FEMs predicted strains that were 20% to 35% greater than the von Mises values. The Drucker-Prager yield function seems to more accurately predict the overall specimen response of geometries with significant internal hydrostatic stress influence.

  4. Mechanical Property of HVOF Inconel 718 Coating for Aeronautic Repair

    NASA Astrophysics Data System (ADS)

    Lyphout, Christophe; Fasth, Angelica; Nylen, Per

    2014-02-01

    The module of elasticity is one of the most important mechanical properties defining the strength of a material which is a prerequisite to design a component from its early stage of conception to its field of application. When a material is to be thermally sprayed, mechanical properties of the deposited layers differ from the bulk material, mainly due to the anisotropy of the highly textured coating microstructure. The mechanical response of the deposited layers significantly influences the overall performance of the coated component. It is, therefore, of importance to evaluate the effective module of elasticity of the coating. Conventional experimental methods such as microindentation, nanoindentation and four-point bending tests have been investigated and their results vary significantly, mainly due to inhomogeneous characteristics of the coating microstructure. Synchrotron radiation coupled with a tensile test rig has been proposed as an alternative method to determine the coating anisotropic elastic behavior dependence on crystallographic orientations. The investigation was performed on Inconel 718 (IN718) HVOF coatings sprayed on IN718 substrates. Combining these experimental techniques yield a deeper understanding of the nature of the HVOF coating Young's modulus and thus a tool for Design Practice for repair applications.

  5. Ultrasonic guided wave inspection of Inconel 625 brazed lap joints

    NASA Astrophysics Data System (ADS)

    Comot, Pierre; Bocher, Philippe; Belanger, Pierre

    2016-04-01

    The aerospace industry has been investigating the use of brazing for structural joints, as a mean of reducing cost and weight. There therefore is a need for a rapid, robust, and cost-effective non-destructive testing method for evaluating the structural integrity of the joints. The mechanical strength of brazed joints depends mainly on the amount of brittle phases in their microstructure. Ultrasonic guided waves offer the possibility of detecting brittle phases in joints using spatio-temporal measurements. Moreover, they offer the opportunity to inspect complex shape joints. This study focused on the development of a technique based on ultrasonic guided waves for the inspection of Inconel 625 lap joints brazed with BNi-2 filler metal. A finite element model of a lap joint was used to optimize the inspection parameters and assess the feasibility of detecting the amount of brittle phases in the joint. A finite element parametric study simulating the input signal shape, the center frequency, and the excitation direction was performed. The simulations showed that the ultrasonic guided wave energy transmitted through, and reflected from, the joints was proportional to the amount of brittle phases in the joint.

  6. Friction Freeform Fabrication of Superalloy Inconel 718: Prospects and Problems

    NASA Astrophysics Data System (ADS)

    Dilip, J. J. S.; Janaki Ram, G. D.

    2013-12-01

    Friction Freeform Fabrication is a new solid-state additive manufacturing process. The present investigation reports a detailed study on the prospects of this process for additive part fabrication in superalloy Inconel 718. Using a rotary friction welding machine and employing alloy 718 consumable rods in solution treated condition, cylindrical-shaped multi-layer friction deposits (10 mm diameter) were successfully produced. In the as-deposited condition, the deposits showed very fine grain size with no grain boundary δ phase. The deposits responded well to direct aging and showed satisfactory room-temperature tensile properties. However, their stress rupture performance was unsatisfactory because of their layered microstructure with very fine grain size and no grain boundary δ phase. The problem was overcome by heat treating the deposits first at 1353 K (1080 °C) (for increasing the grain size) and then at 1223 K (950 °C) (for precipitating the δ phase). Overall, the current study shows that Friction Freeform Fabrication is a very useful process for additive part fabrication in alloy 718.

  7. Barium silicate glass/Inconel X-750 interaction. [PWR

    SciTech Connect

    Kelsey, Jr., P. V.; Siegel, W. T.; Miley, D. V.

    1980-01-01

    Water reactor safety programs at the Idaho National Engineering Laboratory have required the development of specialized instrumentation. An example is the electrical conductivity-sensitive liquid level transducer developed for use in pressurized-water reactors (PWRs) in which the operation of the sensing probe relies upon the passage of current through the water between the center pin of the electrode and its shell such that when water is present the resulting voltage is low, and conversely, when water is absent the voltage is high. The transducer's ceramic seal is a hot-pressed glass ceramic; its metal housing is Inconel X-750. The ceramic material provides an essential dielectric barrier between the center pin and the outer housing. The operation of the probe as well as the integrity of the PWR environment requires a hermetically-bonded seal between the ceramic and the metal. However, during testing, an increasing number of probe assemblies failed owing to poor glass-to-metal seals as well as void formation within the ceramic. Therefore, a program was initiated to characterize the metallic surface with respect to pre-oxidation treatment and determine optimum conditions for wetting and bonding of the metal by the glass to obtain baseline data relevant to production of acceptable transducer seals.

  8. Work hardening in Inconel X-750: Study of Stage II

    SciTech Connect

    Valle, J.A. del |; Picasso, A.C.; Romero, R. |

    1998-03-23

    The effect of the precipitate structure on plastic behavior during the Stage II of work hardening in nickel-base superalloy Inconel X-750 has been studied. Tensile tests were carried out at room temperature. The measures were analyzed by the application of the generalized stress components superposition rule {sigma} = {sigma}{sub f} + {sigma}{sub ss} + ({sigma}{sub {gamma}{prime}}{sup q} + {sigma}{sub d}{sup q}){sup 1/q} for combining the stress components due to: lattice friction {sigma}{sub f}, solid solution {sigma}{sub ss}, {gamma}{prime}-precipitates {sigma}{sub {gamma}{prime}} and dislocation-dislocation interaction {sigma}{sub d}, with q as an adjustable parameter. By using this criterion, the stress component associated with the dislocation density was determined. The results are discussed in the framework of ``one parameter`` models by means of {sigma}{sub d}(d{sigma}{sub d}/d{var_epsilon}) vs {sigma}{sub d} graphs, the structural evolution during Stage II has been characterized along the transition from shearable to unshearable {gamma}{prime}-precipitates.

  9. Hydrostatic Stress Effect on the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2003-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has negligible effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of various geometries. Fatigue tests and nonlinear finite element analyses (FEA) of Inconel 100 (IN100) equal-arm bend specimens and new monotonic tests and nonlinear finite element analyses of IN100 smooth tension, smooth compression, and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions were performed. A new FEA constitutive model was developed that incorporates a pressure-dependent yield function with combined multilinear kinematic and multilinear isotropic hardening using the ABAQUS user subroutine (UMAT) utility. In all monotonic tensile test cases, the von Mises constitutive model, overestimated the load for a given displacement or strain. Considering the failure displacements or strains for the DENT specimen, the Drucker-Prager FEM s predicted loads that were approximately 3% lower than the von Mises values. For the failure loads, the Drucker Prager FEM s predicted strains that were up to 35% greater than the von Mises values. Both the Drucker-Prager model and the von Mises model performed equally-well in simulating the equal-arm bend fatigue test.

  10. Inhomogeneous deformation in INCONEL 718 during monotonic and cyclic loadings

    NASA Astrophysics Data System (ADS)

    Worthem, D. W.; Robertson, I. M.; Leckie, F. A.; Socie, D. F.; Altstetter, C. J.

    1990-12-01

    The deformation microstructures produced by room-temperature monotonie tensile and uniaxial low-cycle fatigue tests in aged (precipitate-hardened) INCONEL 718 were examined by transmission electron microscopy (TEM). Regularly spaced arrays of deformation bands on {111} slip planes were observed. Under monotonie loading, the dislocation structure within a deformation band formed an inverse pileup at a grain boundary, indicating that the boundary was the probable dislocation source. Under fatigue loading, the bands contained a high density of dislocations in a complex arrangement, which was attained after relatively few cycles. Samples of homogenized (precipitate-free) material were deformed monotonically in tension for comparison with the aged material. Early in the deformation, there was only one deformation band per grain and little evidence of work hardening; that is, there was a region of constant flow stress. With increased deformation, work hardening began, more bands nucleated, and their spacing became similar to that in the aged material. This result demonstrates that the degree of coarseness of inhomogeneous deformation in this material was not necessarily a result of a softening process within the bands because of precipitate shearing, but rather, it was primarily a function of the amount of work hardening within the bands. The regularity of the bands and the dislocation structure can be rationalized in terms of a periodic resistance to glide of the dislocations due to the presence of the precipitates and a distribution of dislocation sources along the grain boundaries.

  11. Mechanical properties of nanostructured nickel based superalloy Inconel 718

    NASA Astrophysics Data System (ADS)

    Mukhtarov, Sh; Ermachenko, A.

    2010-07-01

    This paper will describe the investigations of a nanostructured (NS) state of nickel based INCONEL® alloy 718. This structure was generated in bulk semiproducts by severe plastic deformation (SPD) via multiple isothermal forging (MIF) of a coarse-grained alloy. The initial structure consisted of γ-phase grains with disperse precipitations of γ"-phase in the forms of discs, 50-75 nm in diameter and 20 nm in thickness. The MIF generated structures possess a large quantity of non-coherent plates and rounded precipitations of δ-phase, primarily along grain boundaries. In the duplex (γ+δ) structure the grains have high dislocation density and a large number of nonequilibrium boundaries. Investigations to determine mechanical properties of the alloy in a nanostructured state were carried out. Nanocrystalline Inconel 718 (80 nm) possesses a very high room-temperature strength after SPD. Microcrystalline (MC) and NS states of the alloy were subjected to strengthening thermal treatment, and the obtained results were compared in order to determine their mechanical properties at room and elevated temperatures.

  12. Investigation of failure to separate an Inconel 718 frangible nut

    NASA Technical Reports Server (NTRS)

    Hoffman, William C., III; Hohmann, Carl

    1994-01-01

    The 2.5-inch frangible nut is used in two places to attach the Space Shuttle Orbiter to the External Tank. It must be capable of sustaining structural loads and must also separate into two pieces upon command. Structural load capability is verified by proof loading each flight nut, while ability to separate is verified on a sample of a production lot. Production lots of frangible nuts beginning in 1987 experienced an inability to reliably separate using one of two redundant explosive boosters. The problems were identified in lot acceptance tests, and the cause of failure has been attributed to differences in the response of the Inconel 718. Subsequent tests performed on the frangible nuts resulted in design modifications to the nuts along with redesign of the explosive booster to reliably separate the frangible nut. The problem history along with the design modifications to both the explosive booster and frangible nut are discussed in this paper. Implications of this failure experience impact any pyrotechnic separation system involving fracture of materials with respect to design margin control and lot acceptance testing.

  13. [INVITED] Laser treatment of Inconel 718 alloy and surface characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.; Al-Aqeeli, N.; Karatas, C.

    2016-04-01

    Laser surface texturing of Inconel 718 alloy is carried out under the high pressure nitrogen assisting gas. The combination of evaporation and melting at the irradiated surface is achieved by controlling the laser scanning speed and the laser output power. Morphological and metallurgical changes in the treated surface are analyzed using the analytical tools including optical, electron scanning, and atomic force microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardnes and friction coefficient of the laser treated surface are measured. Residual stress formed in the surface region is determined from the X-ray diffraction data. Surface hydrophobicity of the laser treated layer is assessed incorporating the sessile drop method. It is found that laser treated surface is free from large size asperities including cracks and the voids. Surface microhardness increases significantly after the laser treatment process, which is attributed to the dense layer formation at the surface under the high cooling rates, dissolution of Laves phase in the surface region, and formation of nitride species at the surface. Residual stress formed is compressive in the laser treated surface and friction coefficient reduces at the surface after the laser treatment process. The combination of evaporation and melting at the irradiated surface results in surface texture composes of micro/nano-poles and pillars, which enhance the surface hydrophobicity.

  14. Effects of Cations on Corrosion of Inconel 625 in Molten Chloride Salts

    NASA Astrophysics Data System (ADS)

    Zhu, Ming; Ma, Hongfang; Wang, Mingjing; Wang, Zhihua; Sharif, Adel

    2016-04-01

    Hot corrosion of Inconel 625 in sodium chloride, potassium chloride, magnesium chloride, calcium chloride and their mixtures with different compositions is conducted at 900°C to investigate the effects of cations in chloride salts on corrosion behavior of the alloy. XRD, SEM/EDS were used to analyze the compositions, phases, and morphologies of the corrosion products. The results showed that Inconel 625 suffers more severe corrosion in alkaline earth metal chloride molten salts than alkaline metal chloride molten salts. For corrosion in mixture salts, the corrosion rate increased with increasing alkaline earth metal chloride salt content in the mixture. Cations in the chloride molten salts mainly affect the thermal and chemical properties of the salts such as vapor pressure and hydroscopicities, which can affect the basicity of the molten salt. Corrosion of Inconel 625 in alkaline earth metal chloride salts is accelerated with increasing basicity.

  15. A joint computational and experimental study to evaluate Inconel-sheathed thermocouple performance in flames.

    SciTech Connect

    Brundage, Aaron L.; Nicolette, Vernon F.; Donaldson, A. Burl; Kearney, Sean Patrick; Gill, Walter

    2005-09-01

    A joint experimental and computational study was performed to evaluate the capability of the Sandia Fire Code VULCAN to predict thermocouple response temperature. Thermocouple temperatures recorded by an Inconel-sheathed thermocouple inserted into a near-adiabatic flat flame were predicted by companion VULCAN simulations. The predicted thermocouple temperatures were within 6% of the measured values, with the error primarily attributable to uncertainty in Inconel 600 emissivity and axial conduction losses along the length of the thermocouple assembly. Hence, it is recommended that future thermocouple models (for Inconel-sheathed designs) include a correction for axial conduction. Given the remarkable agreement between experiment and simulation, it is recommended that the analysis be repeated for thermocouples in flames with pollutants such as soot.

  16. Fabrication and Optimization of Ni Superalloy Inconel 600 Microtruss Materials

    NASA Astrophysics Data System (ADS)

    Devatha Venkatesh, Balaji

    Microtruss materials are multifunctional cellular hybrids composed of an interconnected arrangement of internal struts that can offer enhanced strength and stiffness at low densities. This study looks at the potential of Ni-based superalloys as microtruss materials. The potential of using the in-situ plastic strain imparted during stretch forming to grain boundary engineer the internal struts of Inconel 600 (IN600) cellular hybrids was also explored. In order to examine this question, a combination of experimental and finite element (FE) methods were employed. The non-uniform plastic deformation imparted to the microtruss struts during fabrication was modeled by FE and the local changes in grain boundary character in the fabricated trusses were mapped by electron backscattered diffraction. This study also examined the distribution of plastic strain over the microtruss architecture. A mechanical press with various pin geometries was employed to experimentally validate the FE models. Standard pin geometry results in substantially non-uniform plastic strain, which limits the maximum formability of the starting sheet material. Importantly, pins designed with tapers and spheres were shown to impart plastic strain along the entire length of the microtruss. This opened up possibility of new design strategies for facilitating grain boundary engineering over the entire truss. It may also present opportunities for enhancing the energy absorption performance of microtruss materials. Finally, this study examined the mechanical properties of IN600 microtrusses, in particular focusing on the significance of strut end constraints in determining the overall mechanical performance. While it is straightforward to analytically determine the inelastic buckling resistance of plastically deformed struts, there is no simple way to determine the rotational end constraint of the struts deformed to varying truss angles. It was seen that end constraint rigidity k could be determined using a

  17. Qualification Data for the Corrosion Behavior of Inconel and Steel Alloys in Nitric Acid

    SciTech Connect

    Mickalonis, J.I.

    2001-05-02

    During filling operations in the Defense Waste Processing Facility (DWPF), melter inserts made of Inconel 690 (I690) have fallen into the canisters which are made of 304L stainless steel (304L). The consequences of possible galvanic corrosion between these materials were evaluated using two electrochemical techniques. Materials for other items which might fall into the canisters were also evaluated including Inconel MA758 (MA758) and A537 carbon steel (A537). The test solutions were concentrated nitric acid, used for validating literature data, and a 10 M nitric acid solution for simulating a possible environment, which may develop due to radiolysis inside the sealed canister.

  18. Qualification Data for the Corrosion Behavior of Inconel and Steel Alloys in Nitric Acid

    SciTech Connect

    Mickalonis, J.I.

    2001-04-17

    During filling operations in the Defense Waste Processing Facility (DWPF), melter inserts made of Inconel 690 (I690) have fallen into the canisters which are made of 304L stainless steel (304L). The consequences of possible galvanic corrosion between these materials were evaluated using two electrochemical techniques. Materials for other items which might fall into the canisters were also evaluated including Inconel MA758 (MA758) and A537 carbon steel (A537). The test solutions were concentrated nitric acid, used for validating literature data, and a 10 M nitric acid solution for simulating a possible environment, which may develop due to radiolysis inside the sealed canister.

  19. Microstructural and tensile characterization of Inconel 718 laser coatings for aeronautic components

    NASA Astrophysics Data System (ADS)

    Lambarri, Jon; Leunda, Josu; García Navas, Virginia; Soriano, Carlos; Sanz, Carmen

    2013-07-01

    The suitability of the laser cladding technique for manufacturing and repairing aeronautic components of Inconel 718 was evaluated. Multilayer coatings were deposited on Inconel 718 plates, using a continuous wave Nd:YAG laser. The microstructure of the laser cladding samples was investigated using optical and scanning electron microscopy and microhardness profiles were measured after different heat treatment stages. Finally, tensile tests were carried out on fully aged samples extracted from a massive multilayer coating. It was proven that the resulting coatings satisfy the industrial requirements for aeronautic applications, with mechanical properties well above the minimum specified values and with no detrimental phases or precipitates left after the heat treatment.

  20. Stress Corrosion Cracking Behavior at Inconel and Low Alloy Steel Weld Interfaces

    NASA Astrophysics Data System (ADS)

    Tomota, Yo; Daikuhara, Shin; Nagayama, Shun; Sugawara, Masanori; Ozawa, Norihiko; Adachi, Yoshitaka; Harjo, Stefanus; Hattori, Shigeo

    2014-12-01

    Three-dimensional microstructure observations, macro- to micro-scopic residual stress measurements by three methods and creviced bent beam SCC tests were performed for Inconel/low alloy steel (LAS) weld samples. The possible reasons for the suppression of SCC crack propagation near the weld interface found at a nuclear power plant were estimated to include the crack branching at the grain boundary (GB) parallel to the interface, i.e., Type II GB, compressive residual stresses in the LAS region and crack tip oxidation in the LAS at the interface. The formation mechanism of Type II GB and stress gradient in individual grains in the Inconel are also discussed.

  1. Stress Corrosion Cracking Behavior at Inconel and Low Alloy Steel Weld Interfaces

    NASA Astrophysics Data System (ADS)

    Tomota, Yo; Daikuhara, Shin; Nagayama, Shun; Sugawara, Masanori; Ozawa, Norihiko; Adachi, Yoshitaka; Harjo, Stefanus; Hattori, Shigeo

    2014-09-01

    Three-dimensional microstructure observations, macro- to micro-scopic residual stress measurements by three methods and creviced bent beam SCC tests were performed for Inconel/low alloy steel (LAS) weld samples. The possible reasons for the suppression of SCC crack propagation near the weld interface found at a nuclear power plant were estimated to include the crack branching at the grain boundary (GB) parallel to the interface, i.e., Type II GB, compressive residual stresses in the LAS region and crack tip oxidation in the LAS at the interface. The formation mechanism of Type II GB and stress gradient in individual grains in the Inconel are also discussed.

  2. A comparison of the solidification behavior of INCOLOY 909 and INCONEL 718

    NASA Astrophysics Data System (ADS)

    Cieslak, M. J.; Headley, T. J.; Knorovsky, G. A.; Romig, A. D.; Kollie, T.

    1990-01-01

    The solidification behavior of two commercial aerospace superalloys, INCOLOY 909 and INCONEL 718, has been examined. Specifically, differential thermal analysis (DTA) revealed that INCOLOY 909 terminates solidification with the formation of a single minor constituent at ≈1198 °C. INCONEL 718 terminates solidification with the formation of two minor constituents, at ≈1257 °C and ~1185 °C, respectively. Metallography performed on the DTA samples confirmed that a single minor constituent was present in INCOLOY 909 while two minor constituents were present in INCONEL 718. Differential thermal analysis samples were also examined by electron probe microanalysis to reveal the patterns of elemental segregation. Arc welds of these alloys were examined by transmission and analytical electron microscopy (TEM and AEM). It was observed that the arc welds of INCOLOY 909 contained only a y/Laves eutectic-like constituent, while the arc welds of INCONEL 718 contained both y/Laves and γ/MC eutectic-like constituents. Compositional analyses of these minor phases revealed that all were enriched in Nb relative to the bulk alloy. The Laves phases were also enriched in Si relative to the bulk alloy concentration. Comparisons of the observed solidification sequences in these alloys with other Nb-bearing austenitic matrix alloys are made.

  3. Hydrogen Permeability of Incoloy 800H, Inconel 617, and Haynes 230 Alloys

    SciTech Connect

    Pattrick Calderoni

    2010-07-01

    A potential issue in the design of the NGNP reactor and high-temperature components is the permeation of fission generated tritium and hydrogen product from downstream hydrogen generation through high-temperature components. Such permeation can result in the loss of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system. The issue will be addressed in the engineering design phase, and requires knowledge of permeation characteristics of the candidate alloys. Of three potential candidates for high-temperature components of the NGNP reactor design, the hydrogen permeability has been documented well only for Incoloy 800H, but at relatively high partial pressures of hydrogen. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. The hydrogen permeability of Haynes 230 has not been published. To support engineering design of the NGNP reactor components, the hydrogen permeability of Inconel 617 and Haynes 230 were determined using a measurement system designed and fabricated at the Idaho National Laboratory. The performance of the system was validated using Incoloy 800H as reference material, for which the permeability has been published in several journal articles. The permeability of Incoloy 800H, Inconel 617 and Haynes 230 was measured in the temperature range 650 to 950 °C and at hydrogen partial pressures of 10-3 and 10-2 atm, substantially lower pressures than used in the published reports. The measured hydrogen permeability of Incoloy 800H and Inconel 617 were in good agreement with published values obtained at higher partial pressures of hydrogen. The hydrogen permeability of Inconel 617 and Haynes 230 were similar, about 50% greater than for Incoloy 800H and with similar temperature dependence.

  4. Corrosion resistance of inconel 690 to borax, boric acid, and boron nitride at 1100{degrees}C

    SciTech Connect

    Imrich, K.J.

    1996-12-12

    Significant general and localized corrosion was observed on Inconel 690 coupons following exposure to borax, boric acid and boron nitride at 1100{degrees}C. Severe localized attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack (IGA) of the Inconel 690 was also observed. Severe internal void formation and IGA (30 mils penetration after 3 days) was observed in the coupon exposed to boric acid. Both borax and boric acid remove the protective chromium oxide; however, this layer can be reestablished by heating the Inconel 690 to 975 {degrees}C in air for several hours. Inconel 690 in direct contact with boron nitride resulted in the formation of a thick chromium borate layer, a general corrosion rate of 50 to 90 mils per year, and internal void formation of 1 mil per day.

  5. Effect of Orientation on Tensile Properties of Inconel 718 Block Fabricated with Electron Beam Freeform Fabrication (EBF3)

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Atherton, Todd S.

    2010-01-01

    Electron beam freeform fabrication (EBF3) direct metal deposition processing was used to fabricate an Inconel 718 bulk block deposit. Room temperature tensile properties were measured as a function of orientation and location within the block build. This study is a follow-on activity to previous work on Inconel 718 EBF3 deposits that were too narrow to allow properties to be measured in more than one orientation

  6. Strength Differential Measured in Inconel 718: Effects of Hydrostatic Pressure Studied

    NASA Technical Reports Server (NTRS)

    Lewandowski, John J.; Wesseling, Paul; Prabhu, Nishad S.; Larose, Joel; Lissenden, Cliff J.; Lerch, Bradley A.

    2003-01-01

    Aeropropulsion components, such as disks, blades, and shafts, are commonly subjected to multiaxial stress states at elevated temperatures. Experimental results from loadings as complex as those experienced in service are needed to help guide the development of accurate viscoplastic, multiaxial deformation models that can be used to improve the design of these components. During a recent study on multiaxial deformation (ref. 1) on a common aerospace material, Inconel 718, it was shown that the material in the aged state exhibits a strength differential effect (SDE), whereby the uniaxial compressive yield and subsequent flow behavior are significantly higher than those in uniaxial tension. Thus, this material cannot be described by a standard von Mises yield formulation. There have been other formulations postulated (ref. 2) that involve other combinations of the stress invariants, including the effect of hydrostatic stress. The question remained as to which invariants are necessary in the flow model. To capture the physical mechanisms occurring during deformation and reflect them in the plasticity formulation, researchers examined the flow of Inconel 718 under various amounts of hydrostatic stress to determine whether or not hydrostatic stress is needed in the formulation. Under NASA Grant NCC3-464, monitored by the NASA Glenn Research Center, a series of tensile tests were conducted at Case Western Reserve University on aged (precipitation hardened) Inconel 718 at 650 C and with superimposed hydrostatic pressure. Dogbone shaped tensile specimens (3-mm-diameter gauge by 16-mm gauge length) and cylindrical compression specimens (3-mm-diameter gauge by 6-mm gauge length) were strain gauged and loaded in a high-pressure testing apparatus. Hydrostatic pressures were obtained with argon and ranged from 210 to 630 MPa. The aged Inconel 718 showed a pronounced difference in the tension and compression yield strength (i.e., an SDE), as previously observed. Also, there were

  7. Nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel and stainless steel alloys

    SciTech Connect

    Moore, D.G.; Sorensen, N.R.

    1998-02-01

    This report presents a nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning techniques to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each technique classifies a known exhaust material. Results indicate that either inspection technique can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into the Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.

  8. Enhanced field emission properties from CNT arrays synthesized on Inconel superalloy.

    PubMed

    Sridhar, S; Ge, L; Tiwary, C S; Hart, A C; Ozden, S; Kalaga, K; Lei, S; Sridhar, S V; Sinha, R K; Harsh, H; Kordas, K; Ajayan, P M; Vajtai, R

    2014-02-12

    One of the most promising materials for fabricating cold cathodes for next generation high-performance flat panel devices is carbon nanotubes (CNTs). For this purpose, CNTs grown on metallic substrates are used to minimize contact resistance. In this report, we compare properties and field emission performance of CNTs grown via water assisted chemical vapor deposition using Inconel vs silicon (Si) substrates. Carbon nanotube forests grown on Inconel substrates are superior to the ones grown on silicon; low turn-on fields (∼1.5 V/μm), high current operation (∼100 mA/cm(2)) and very high local field amplification factors (up to ∼7300) were demonstrated, and these parameters are most beneficial for use in vacuum microelectronic applications. PMID:24417432

  9. Influence Of The Laser Cladding Strategies On The Mechanical Properties Of Inconel 718

    SciTech Connect

    Lamikiz, A.; Tabernero, I.; Ukar, E.; Lopez de Lacalle, L. N.

    2011-01-17

    This work presents different experimental results of the mechanical properties of Inconel registered 718 test parts built-up by laser cladding. Recently, turbine manufacturers for aeronautical sector have presented high interest on laser cladding processes. This process allows building fully functional structures on superalloys, such as Inconel registered 718, with high flexibility on complex shapes. However, there is limited data on mechanical properties of the laser cladding structures. Moreover, the available data do not include the influence of process parameters and laser cladding strategies. Therefore, a complete study of the influence of the laser cladding parameters and mainly, the variation of the tensile strength with the laser cladding strategy is presented. The results show that there is a high directionality of mechanical properties, depending on the strategies of laser cladding process. In other words, the test parts show a fiber -like structure that should be considered on the laser cladding strategy selection.

  10. Rapid assessment of anisotropic surface processes: experiments on the corrosion of Inconel 600

    NASA Astrophysics Data System (ADS)

    Schuh, Christopher A.; Anderson, Kelly; Orme, Christine

    2003-10-01

    We present a general experimental method for rapid characterization of surface processes on crystals of many orientations. By correlating maps of crystallographic orientation (obtained by electron backscatter diffraction methods) with those of surface topography (obtained by atomic force microscopy), we illustrate how a surface property can be elucidated on many off-principle crystal surfaces from a single polycrystalline specimen. For the corrosion of Inconel 600 in a dilute aqueous solution of HCl, we find that corrosion rates scale with the deviation angle of the surface normal from an ideal <1 1 1> direction. The use of atomic force microscopy can also provide mechanistic details about the surface process in question. For Inconel 600, we correlate the surface oxide morphology directly to the orientation of the underlying crystal.

  11. Laser Additive Melting and Solidification of Inconel 718: Finite Element Simulation and Experiment

    NASA Astrophysics Data System (ADS)

    Romano, John; Ladani, Leila; Sadowski, Magda

    2016-03-01

    The field of powdered metal additive manufacturing is experiencing a surge in public interest finding uses in aerospace, defense, and biomedical industries. The relative youth of the technology coupled with public interest makes the field a vibrant research topic. The authors have expanded upon previously published finite element models used to analyze the processing of novel engineering materials through the use of laser- and electron beam-based additive manufacturing. In this work, the authors present a model for simulating fabrication of Inconel 718 using laser melting processes. Thermal transport phenomena and melt pool geometries are discussed and validation against experimental findings is presented. After comparing experimental and simulation results, the authors present two correction correlations to transform the modeling results into meaningful predictions of actual laser melting melt pool geometries in Inconel 718.

  12. High temperature environmental interactions of Inconel 617: A paper study for the TEF

    SciTech Connect

    Korinko, P.S.

    2000-06-16

    Inconel alloy 617 has been selected as the material of choice for the retort of the furnace for the Tritium Extraction Facility. To monitor retort performance and suitability for continued service, representative sample coupons should be suspended on the inside (process side) and outside (annulus side) of the retort for periodic metallographic analysis or hardness testing. Surface dealloying and hardness could be used to monitor the ``health'' of the retort in this surveillance program.

  13. Mechanical properties and corrosion resistance of Inconel alloy 617 for refinery service

    SciTech Connect

    Lipscomb, W.G.; Crum, J.R.; Ganesan, P. )

    1989-01-01

    Various factors affecting the performance of Inconel alloy 617 in refinery service are evaluated. The influence of long-term exposure at 1000-1400{degrees}F (538- 760{degrees}C) on mechanical properties and high-temperature low-cycle fatigue studies are reported. In addition the effects of various heat treatments and resulting microstructure on polythionic acid stress corrosion cracking resistance and intergranular attack resistance are determined.

  14. Fatigue Crack Growth Rate of Inconel 718 Sheet at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Wells, Douglas; Wright, Jonathan; Hastings, Keith

    2005-01-01

    Inconel 718 sheet material was tested to determine fatigue crack growth rate (FCGR) at cryogenic conditions representative of a liquid hydrogen (LH2) environment at -423 degree F. Tests utilized M(T) and ESE(T) specimen geometries and environments were either cold gaseous helium or submersion in LH2. The test results support a significant improvement in the fatigue crack growth threshold at -423 degree F compared to -320 degree F or 70 degree F.

  15. Preferential coarsening of γ″ precipitates in INCONEL 718 during creep

    NASA Astrophysics Data System (ADS)

    Gao, Ming; Harlow, D. Gary; Wei, Robert P.; Chen, Shuchun

    1996-11-01

    Preferential coarsening of the γ″ (Ni3Nb) precipitates was observed in polycrystalline INCONEL 718 during creep which involved principally the growth of one of three variants at the expense of the others. The tendency and extent of preferential coarsening are analyzed in terms of the interaction between the applied stress and the transformation strains and probabilistically in terms of the orientation of the γ″ precipitates with respect to the tensile stress axis.

  16. Microstructure Development in Electron Beam-Melted Inconel 718 and Associated Tensile Properties

    DOE PAGES

    Kirka, M. M.; Unocic, K. A.; Raghavan, N.; Medina, F.; Dehoff, R. R.; Babu, S. S.

    2016-02-12

    During the electron beam melting (EBM) process, builds occur at temperatures in excess of 800°C for nickel-base superalloys such as Inconel 718. When coupled with the temporal differences between the start and end of a build, a top-to-bottom microstructure gradient forms. Characterized in this study is the microstructure gradient and associated tensile property gradient that are common to all EBM Inconel 718 builds. From the characteristic microstructure elements observed in EBM Inconel 718 material, the microstructure gradient can be classified into three distinct regions. Region 1 (top of a build) and is comprised of a cored dendritic structure that includesmore » carbides and Laves phase within the interdendritic regions. Region 2 is an intermediate transition zone characterized by a diffuse dendritic structure, dissolution of the Laves phase, and precipitation of δ needle networks within the interdendritic regions. The bulk structure (Region 3) is comprised of a columnar grain structure lacking dendritic characteristics with δ networks having precipitated within the grain interiors. Mechanically at both 20°C and 650° C, the yield strength, ultimate tensile strength, and elongation at failure exhibit the general trend of increasing with increasing build height.« less

  17. Investigation of low stress rupture properties in Inconel-718 super alloy

    NASA Astrophysics Data System (ADS)

    Zaman, T.; Farooque, M.; Rizvi, S. A.; Salam, I.; Waseem, M.

    2016-08-01

    Inconel-718 is a Ni-Cr-Fe based super alloy. It is widely utilized in aircraft gas turbines, nuclear power systems, space vehicles and medical applications. Aim of the present study is to evaluate the effect of Ti and Nb content on high temperature stress rupture properties of Inconel718. OM, SEM and TEM were utilized for characterization of microstructure. Inconel718 is unique in that it forms large number of phases due to its composition and variety of heat treatments. γ"+ γ' precipitates and the effect of annealing on these precipitates have been studied using TEM. The main hardening phase was identified as metastable Ni3Nb (γ"). Other phases identified after annealing were secondary carbides (NbC) and stable acicular 5 phase. Effect of γ", 5, primary carbides and NbC on creep behavior was observed using OM and SEM. Higher Ti content(1.25 wt. %) resulted in poor creep properties due to large concentrations of primary carbides (TiC) at grain boundaries.

  18. Deformation and fracture characteristics of Inconel X-750 at room temperature and elevated temperatures

    SciTech Connect

    Mills, W.J.

    1980-06-01

    Electron fractographic and thin foil electron metallographic techniques were used to evaluate the deformation and fracture characteristics of Inconel X-750 at temperatures ranging from 24 to 816/sup 0/C. Operative dislocation mechanisms and fracture surface morphologies were related to the overall tensile response of this nickel-base superalloy. At room temperature, failure occurred primarily by an intergranular dimple rupture mechanism associated with microvoid coalescence along grain boundary denuded regions. A fairly high density of dislocations throughout the matrix resulted in relatively high ductility levels even though failure occurred by an intergranular mechanism. Under intermediate temperature conditions (316 to 427/sup 0/C), increased transgranular fracture coupled with extensive dislocation activity within the Inconel X-750 matrix caused a slight increase in ductility. At progressively higher temperatures, 538 to 704/sup 0/C, all dislocation activity was channeled through narrow slip bands which subsequently initiated localized separation and resulted in a very faceted fracture surface appearance. The absence of a homogeneous dislocation substructure in this temperature regime resulted in a severe degradation in ductility levels. At the highest test temperature (816/sup 0/C), a uniform dislocation network throughout the Inconel X-750 matrix coupled with intense dislocation activity in the grain boundary denuded zone resulted in a marked improvement in ductility. Furthermore, the extensive dislocation activity along grain boundary regions ultimately resulted in an intergranular fracture morphology.

  19. Surface Integrity of Inconel 718 by Wire-EDM at Different Energy Modes

    NASA Astrophysics Data System (ADS)

    Li, L.; Wei, X. T.; Guo, Y. B.; Li, W.; Liu, J. F.

    2014-08-01

    Inconel alloys including IN 718 alloy are widely used in turbomachinery industry due to their superior mechanical properties. Inconel alloys are very difficult to machine using cutting and grinding. Wire electrical discharge machining (W-EDM) is an alternative process to manufacture complex Inconel parts. However, little research has been done on surface integrity by W-EDMed IN 718. This study focuses on surface integrity of IN 718 by W-EDM at different modes of discharge energy. The results show that the EDMed surface topography shows dominant coral reef microstructures at high energy mode, while random microvoids are dominant at low energy modes. The average roughness can be significantly reduced at low energy mode. A thick white layer is predominantly discontinuous and non-uniform at relative high energy modes. Microvoids are confined within the thick white layers and no microcracks were found in the subsurface. A thin white layer by trim cut at low energy mode becomes continuous, uniform, and is free of voids. Compared to the bulk, white layers have dramatic reduction in microhardness. In addition, surface alloying from wire electrode and water dielectric is obvious in main cut, but it can be minimized in trim cuts.

  20. Effects of Flux Precoating and Process Parameter on Welding Performance of Inconel 718 Alloy TIG Welds

    NASA Astrophysics Data System (ADS)

    Lin, Hsuan-Liang; Wu, Tong-Min; Cheng, Ching-Min

    2014-01-01

    The purpose of this study is to investigate the effect of activating flux on the depth-to-width ratio (DWR) and hot cracking susceptibility of Inconel 718 alloy tungsten inert gas (TIG) welds. The Taguchi method is employed to investigate the welding parameters that affect the DWR of weld bead and to achieve optimal conditions in the TIG welds that are coated with activating flux in TIG (A-TIG) process. There are eight single-component fluxes used in the initial experiment to evaluate the penetration capability of A-TIG welds. The experimental results show that the Inconel 718 alloy welds precoated with 50% SiO2 and 50% MoO3 flux were provided with better welding performance such as DWR and hot cracking susceptibility. The experimental procedure of TIG welding process using mixed-component flux and optimal conditions not only produces a significant increase in DWR of weld bead, but also decreases the hot cracking susceptibility of Inconel 718 alloy welds.

  1. Additive manufacturing of Inconel 718 using electron beam melting: Processing, post-processing, & mechanical properties

    NASA Astrophysics Data System (ADS)

    Sames, William James, V.

    Additive Manufacturing (AM) process parameters were studied for production of the high temperature alloy Inconel 718 using Electron Beam Melting (EBM) to better understand the relationship between processing, microstructure, and mechanical properties. Processing parameters were analyzed for impact on process time, process temperature, and the amount of applied energy. The applied electron beam energy was shown to be integral to the formation of swelling defects. Standard features in the microstructure were identified, including previously unidentified solidification features such as shrinkage porosity and non-equilibrium phases. The as-solidified structure does not persist in the bulk of EBM parts due to a high process hold temperature (˜1000°C), which causes in situ homogenization. The most significant variability in as-fabricated microstructure is the formation of intragranular delta-phase needles, which can form in samples produced with lower process temperatures (< 960°C). A novel approach was developed and demonstrated for controlling the temperature of cool down, thus providing a technique for in situ heat treatment of material. This technique was used to produce material with hardness of 478+/-7 HV with no post-processing, which exceeds the hardness of peak-aged Inconel 718. Traditional post-processing methods of hot isostatic pressing (HIP) and solution treatment and aging (STA) were found to result in variability in grain growth and phase solution. Recrystallization and grain structure are identified as possible mechanisms to promote grain growth. These results led to the conclusion that the first step in thermal post-processing of EBM Inconel 718 should be an optimized solution treatment to reset phase variation in the as-fabricated microstructure without incurring significant grain growth. Such an optimized solution treatment was developed (1120°C, 2hr) for application prior to aging or HIP. The majority of as-fabricated tensile properties met ASTM

  2. OXIDATION OF INCONEL 718 IN AIR AT TEMPERATURES FROM 973K TO 1620K.

    SciTech Connect

    GREENE,G.A.; FINFROCK,C.C.

    2000-10-01

    As part of the APT project, it was necessary to quantify the release of tungsten from the APT spallation target during postulated accident conditions in order to develop accident source terms for accident consequence characterization. Experiments with tungsten rods at high temperatures in a flowing steam environment characteristic of postulated accidents revealed that considerable vaporization of the tungsten occurred as a result of reactions with the steam and that the aerosols which formed were readily transported away from the tungsten surfaces, thus exposing fresh tungsten to react with more steam. The resulting tungsten release fractions and source terms were undesirable and it was decided to clad the tungsten target with Inconel 718 in order to protect it from contact with steam during an accident and mitigate the accident source term and the consequences. As part of the material selection criteria, experiments were conducted with Inconel 718 at high temperatures to evaluate the rate of oxidation of the proposed clad material over as wide a temperature range as possible, as well as to determine the high-temperature failure limit of the material. Samples of Inconel 718 were inserted into a preheated furnace at temperatures ranging from 973 K to 1620 K and oxidized in air for varying periods of time. After oxidizing in air at a constant temperature for the prescribed time and then being allowed to cool, the samples would be reweighed to determine their weight gain due to the uptake of oxygen. From these weight gain measurements, it was possible to identify three regimes of oxidation for Inconel 718: a low-temperature regime in which the samples became passivated after the initial oxidation, an intermediate-temperature regime in which the rate of oxidation was limited by diffusion and exhibited a constant parabolic rate dependence, and a high-temperature regime in which material deformation and damage accompanied an accelerated oxidation rate above the parabolic

  3. Surface Roughness and Tool Wear on Cryogenic Treated CBN Insert on Titanium and Inconel 718 Alloy Steel

    NASA Astrophysics Data System (ADS)

    Thamizhmanii, S.; Mohideen, R.; Zaidi, A. M. A.; Hasan, S.

    2015-12-01

    Machining of materials by super hard tools like cubic boron nitride (cbn) and poly cubic boron nitride (pcbn) is to reduce tool wear to obtain dimensional accuracy, smooth surface and more number of parts per cutting edge. wear of tools is inevitable due to rubbing action between work material and tool edge. however, the tool wear can be minimized by using super hard tools by enhancing the strength of the cutting inserts. one such process is cryogenic process. this process is used in all materials and cutting inserts which requires wear resistance. the cryogenic process is executed under subzero temperature -186° celsius for longer period of time in a closed chamber which contains liquid nitrogen. in this research, cbn inserts with cryogenically treated was used to turn difficult to cut metals like titanium, inconel 718 etc. the turning parameters used is different cutting speeds, feed rates and depth of cut. in this research, titanium and inconel 718 material were used. the results obtained are surface roughness, flank wear and crater wear. the surface roughness obtained on titanium was lower at high cutting speed compared with inconel 718. the flank wear was low while turning titanium than inconel 718. crater wear is less on inconel 718 than titanium alloy. all the two materials produced saw tooth chips.

  4. Mechanical properties of Inconel 718 and Nickel 201 alloys after thermal histories simulating brazing and high temperature service

    NASA Technical Reports Server (NTRS)

    James, W. F.

    1985-01-01

    An experimental investigation was made to evaluate two nickel base alloys (Nickel-201 and Inconel-718) in three heat treated conditions. These conditions were: (1) annealed; (2) after thermal exposure simulating a braze cycle; and (3) after a thermal exposure simulating a braze cycle plus one operational lifetime of high temperature service. For the Nickel-201, two different braze cycle temperatures were evaluated. A braze cycle utilizing a lower braze temperature resulted in less grain growth for Nickel-201 than the standard braze cycle used for joining Nickel-201 to Inconel-718. It was determined, however, that Nickel-201, was marginal for temperatures investigated due to large grain growth. After the thermal exposures described above, the mechanical properties of Nickel-201 were degraded, whereas similar exposure on Inconel-718 actually strengthened the material compared with the annealed condition. The investigation included tensile tests at both room temperature and elevated temperatures, stress-rupture tests, and metallographic examination.

  5. Effect of Variation in Process Parameters on the Formation of Freckle in INCONEL 718 by Vacuum Arc Remelting

    NASA Astrophysics Data System (ADS)

    Wang, Xianhui; Ward, R. Mark; Jacobs, Mike H.; Barratt, Mark D.

    2008-12-01

    In order to study the effect of variation in process parameters on the final ingot of INCONEL 718 during vacuum arc remelting, a 508-mm-diameter vacuum arc remelting (VAR) ingot of INCONEL 718 was produced under conditions of variation in electrode diameter and arc gap. It was sectioned and analyzed in the as-cast state. Freckle was found in the midradius and center regions when the electrode diameter and arc gap changed. The experimental results were discussed in relation to composition, current distribution, and fluid flow. Freckle formation was found to be associated with large changes in melting conditions probably resulting in significant perturbation of the fluid flow in the melt pool and mushy zone. Instability in the solidification process may contribute to the initiation and formation of freckle defects in INCONEL 718 ingot.

  6. Reaction of Inconel 690 and 693 in Iron Phosphate Melts: Alternative Glasses for Waste Vitrification

    SciTech Connect

    Day, Delbert E. Kim, Cheol-Woon

    2005-09-13

    The corrosion resistance of candidate materials used for the electrodes (Inconel 690 & 693) and the melt contact refractory (Monofrax K-3) in a Joule Heated Melter (JHM) has been investigated at the University of Missouri-Rolla (UMR) during the period from June 1, 2004 to August 31, 2005. This work was supported by the U.S. Department of Energy (DOE) Office of Biological and Environmental Research (DE-FG02-04ER63831). The unusual properties and characteristics of iron phosphate glasses, as viewed from the standpoint of alternative glasses for vitrifying nuclear and hazardous wastes which contain components that make them poorly suited for vitrification in borosilicate glass, were recently discovered at UMR. The expanding national and international interest in iron phosphate glasses for waste vitrification stems from their rapid melting and chemical homogenization which results in higher furnace output, their high waste loading that varies from 32 wt% up to 75 wt% for the Hanford LAW and HLW, respectively, and the outstanding chemical durability of the iron phosphate wasteforms which meets all present DOE requirements (PCT and VHT). The higher waste loading in iron phosphate glasses, compared to the baseline borosilicate glass, can reduce the time and cost of vitrification considerably since a much smaller mass of glass will be produced, for example, about 43% less glass when the LAW at Hanford is vitrified in an iron phosphate glass according to PNNL estimates. In view of the promising performance of iron phosphate glasses, information is needed for how to best melt these glasses on the scale needed for practical use. Melting iron phosphate glasses in a JHM is considered the preferred method at this time because its design could be nearly identical to the JHM now used to melt borosilicate glasses at the Defense Waste Processing Facility (DWPF), Westinghouse Savannah River Co. Therefore, it is important to have information for the corrosion of candidate electrode

  7. Microstructures and microhardness at fusion boundary of 316 stainless steel/Inconel 182 dissimilar welding

    SciTech Connect

    Wang, Wei; Lu, Yonghao; Ding, Xianfei; Shoji, Tetsuo

    2015-09-15

    Microstructures and microhardness at fusion boundary of a weld joint were investigated in a 316 stainless steel/Inconel 182 dissimilar weldment. The results showed that there were two alternately distributed typical fusion boundaries, a narrow random boundary (possessed 15% in length) with a clear sharp interface and an epitaxial fusion one with (100){sub BM}//(100){sub WM} at the joint interface. The composition transition, microstructure and hardness across the fusion boundary strongly depended on the type of the fusion boundary. For the random boundary, there was a clear sharp interface and the composition transition with a width of 100 μm took place symmetrically across the grain boundary. For the epitaxial fusion one, however, there were Type-I and Type-II grain boundaries perpendicular and parallel to the epitaxial fusion boundary, respectively. The composition transition took place in the Inconel 182 weld side. Σ3 boundaries in the HAZ of 316SS side and Σ5 grain boundaries in weld metal were usually observed, despite the type of fusion boundary, however the former was much more in epitaxial fusion boundary. Microhardness was continuously decreased across the random fusion boundary from the side of Inconel 182 to 316SS, but a hardening phenomenon appeared in the epitaxial fusion boundary zone because of its fine cellular microstructure. - Highlights: • Two typical fusion boundaries alternately distributed in the fusion interface • The microstructure, composition and hardness across fusion boundary depended on its type. • Different regions in welded joint have different special CSL value boundaries. • Hardening phenomenon only appeared in the epitaxial fusion boundary.

  8. Pitting corrosion of inconel 600 in high-temperature water containing CuCl/sub 2/

    SciTech Connect

    Park, J.R.; Szklarska-Smialowska, Z.

    1985-11-01

    Pitting corrosion of Inconel 600 was studied in aqueous sodium and cupric chloride solutions at 60 and 280 C. The pit nucleation potential, E /SUB np/ was evaluated in two different concentrations of sodium chloride. E /SUB np/ decreased with increasing concentrations of the chloride ion and with temperature. On specimen surfaces exposed to cupric chloride solutions, pitting occurred at open circuit potentials nearly equal to or higher than the E /SUB np/ determined by anodic polarization in 0.01 M NaCl solution. The number and size of the pits increased with increasing concentrations of cupric chloride and dissolved oxygen. On specimens partly covered with polytetrafluorethylene (PTFE) tape (i.e., in the presence of artificial crevices), pitting occurre more easily at low concentrations of CuCl/sub 2/ (less than or equal to20 ppm CuCl/sub 2/ in deaerated solutions at 280 C). Tubes covered with oxide films that formed during the operation of model boilers exhibited greater pitting resistance than tubes with clean surfaces at 280 C, but less resistance at 60 C. Corrosion products contained in the pits were enriched in chromium with small amounts of copper, sulfur, and chlorine. The composition of corrosion products covering the pits was similar to that in the pits, but with the additional enrichment of iron. Presumably, sulfur present in Inconel 600 as an impurity was significant in the pitting process. The probable mechanism of the processes leading to pitting of Inconel 600 tubing in high-temperature water is discussed.

  9. Laser metal deposition of TiC/Inconel 718 composites with tailored interfacial microstructures

    NASA Astrophysics Data System (ADS)

    Hong, Chen; Gu, Dongdong; Dai, Donghua; Gasser, Andres; Weisheit, Andreas; Kelbassa, Ingomar; Zhong, Minlin; Poprawe, Reinhart

    2013-12-01

    Laser metal deposition (LMD) was applied to deposit Inconel 718 metal matrix composites reinforced with TiC particles. The influence of laser energy input per unit length on constitution phases, microstructures, hardness, and wear performance of LMD-processed TiC/Inconel 718 composites was studied. It revealed that the LMD-processed composites consisted of γ Ni-Cr solid solution matrix, the intermetallic precipitation phase γ‧, and the TiC reinforcing phase. For the laser energy input per unit length of 80-120 kJ/m, a coherent interfacial layer with the thickness of 0.8-1.4 μm was formed between TiC reinforcing particles and the matrix, which was identified as (Ti,M)C (M=Nb and Mo) layer. Its formation was due to the reaction of the strong carbide-forming elements Nb and Mo of the matrix with the dissolved Ti and C on the surface of TiC particles. The microstructures of the TiC reinforcing phase experienced a successive change as laser energy input per unit length increased: Relatively coarsened poly-angular particles (80 kJ/m) - surface melted, smoothened TiC particles (≥100 kJ/m) - fully melted/precipitated, significantly refined TiC dendrites/particles (160 kJ/m). Using the laser energy input per unit length ≥100 kJ/m produced the fully dense composites having the uniformly dispersed TiC reinforcing particles. Either the formation of reinforcement/matrix interfacial layer or the refinement in TiC dendrites/particles microstructures enhanced the microhardness and wear performance of TiC/Inconel 718 composites.

  10. Spectral Emittance of Uncoated and Ceramic-Coated Inconel and Type 321 Stainless Steel

    NASA Technical Reports Server (NTRS)

    Richmond, Joseph C.; Stewart, James E.

    1959-01-01

    The normal spectral emittance of Inconel and type 321 stainless steel with different surface treatments was measured at temperatures of 900, 1,200, 1,500, and 1,800 F over a wavelength range of 1.5 to 15 microns. The measurements involved comparison of the radiant energy emitted by the heated specimen with that emitted by a comparison standard at the same temperature by means of a recording double-beam infrared spectrophotometer. The silicon carbide comparison standard had previously been calibrated against a laboratory black-body furnace. Surface treatments included electropolishing, sandblasting, electro-polishing followed by oxidation in air for 1/2 hour at 1,800 F, sandblasting followed by oxidation in air for 1/2 hour at 1,800 F, application of National Bureau of Standards coating A-418, and application of NBS ceramic coating N-143. The normal spectral emittance of both alloys in the electropolished condition was low and decreased very slightly with increasing wavelength while in the sandblasted condition it was somewhat higher and did not vary appreciably with wavelength. The oxidation treatment greatly increased the normal spectral emittance of both the electropolished and sandblasted type 321 stainless steel specimens and of the electropolished Inconel specimens and introduced some spectral selectivity into the curves. The oxidation increased the normal spectral emittance of the sandblasted Inconel specimens only moderately. Of the specimens to which a coating about 0.002 inch thick was applied, those coated with A-418 had higher emittance at all wavelengths than did those coated with N-143, and the coated specimens of Inconel had higher spectral emittance at all wavelengths than did the corresponding specimens of type 321 stainless steel. Both coatings were found to be partially transparent to the emitted energy at this thickness but essentially opaque at a thickness of 0.005 inch. Coated specimens with 0.005 inch or more of coating did not show the effect

  11. Crack-growth behavior in thick welded plates of Inconel 718 at room and cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Forman, R. G.

    1974-01-01

    Results of mechanical-properties and axial-load fatigue and fracture tests performed on thick welded plates of Inconel 718 superalloy are presented. The test objectives were to determine the tensile strength properties and the crack-growth behavior in electron-beam, plasma-arc, and gas tungsten are welds for plates 1.90 cm (0.75 in) thick. Base-metal specimens were also tested to determine the flaw-growth behavior. The tests were performed in room-temperature-air and liquid nitrogen environments. The experimental crack-growth-rate data are correlated with theoretical crack-growth-rate predictions for semielliptical surface flaws.

  12. A Comparison of Weld-Repaired and Base Metal for Inconel 718 and CRES 321 at Cryogenic and Room Temperatures

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Smith, Stephen W.; Willard, Scott A.; Piascik, Robert S.

    2004-01-01

    Fatigue crack growth tests were conducted to characterize the performance of Inconel 718 and CRES 321 welds, weld heat-affect-zone and parent metal at room temperature laboratory air and liquid nitrogen (-196oC) environments. The results of this study were required to predict the damage tolerance behavior of proposed orbiter main engine hydrogen fuel liner weld repairs. Experimental results show that the room and cryogenic temperature fatigue crack growth characteristics of both alloys are not significantly degraded by the weld repair process. However, both Inconel 718 and CRES 321 exhibited lower apparent toughness within the weld repair region compared to the parent metal.

  13. Effect of Powder-Suspended Dielectric on the EDM Characteristics of Inconel 625

    NASA Astrophysics Data System (ADS)

    Talla, Gangadharudu; Gangopadhyay, S.; Biswas, C. K.

    2016-02-01

    The current work attempts to establish the criteria for powder material selection by investigating the influence of various powder-suspended dielectrics and machining parameters on various EDM characteristics of Inconel 625 (a nickel-based super alloy) which is nowadays regularly used in aerospace, chemical, and marine industries. The powders include aluminum (Al), graphite, and silicon (Si) that have significant variation in their thermo-physical characteristics. Results showed that powder properties like electrical conductivity, thermal conductivity, density, and hardness play a significant role in changing the machining performance and the quality of the machined surface. Among the three powders, highest material removal rate was observed for graphite powder due to its high electrical and thermal conductivities. Best surface finish and least radial overcut (ROC) were attained using Si powder. Maximum microhardness was found for Si due to its low thermal conductivity and high hardness. It is followed by graphite and aluminum powders. Addition of powder to the dielectric has increased the crater diameter due to expansion of plasma channel. Powder-mixed EDM (PMEDM) was also effective in lowering the density of surface cracks with least number of cracks obtained with graphite powder. X-ray diffraction analysis indicated possible formation of metal carbides along with grain growth phenomenon of Inconel 625 after PMEDM.

  14. Reduction of a thin chromium oxide film on Inconel surface upon treatment with hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Vesel, Alenka; Mozetic, Miran; Balat-Pichelin, Marianne

    2016-11-01

    Inconel samples with a surface oxide film composed of solely chromium oxide with a thickness of approximately 700 nm were exposed to low-pressure hydrogen plasma at elevated temperatures to determine the suitable parameters for reduction of the oxide film. The hydrogen pressure during treatment was set to 60 Pa. Plasma was created by a surfaguide microwave discharge in a quartz glass tube to allow for a high dissociation fraction of hydrogen molecules. Auger electron depth profiling (AES) was used to determine the decay of the oxygen in the surface film and X-ray diffraction (XRD) to measure structural modifications. During hydrogen plasma treatment, the oxidized Inconel samples were heated to elevated temperatures. The reduction of the oxide film started at temperatures of approximately 1300 K (considering the emissivity of 0.85) and the oxide was reduced in about 10 s of treatment as revealed by AES. The XRD showed sharper substrate peaks after the reduction. Samples treated in hydrogen atmosphere under the same conditions have not been reduced up to approximately 1500 K indicating usefulness of plasma treatment.

  15. Surface Integrity and Structural Stability of Broached Inconel 718 at High Temperatures

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Peng, R. Lin; Moverare, J.; Avdovic, P.; Zhou, J. M.; Johansson, S.

    2016-07-01

    The current study focused on the surface integrity issues associated with broaching of Inconel 718 and the structural stability of the broached specimen at high temperatures, mainly involving the microstructural changes and residual stress relaxation. The broaching operation was performed using similar cutting conditions as that used in turbo machinery industries for machining fir-tree root fixings on turbine disks. Thermal exposure was conducted at 723 K, 823 K, and 923 K (450 °C, 550 °C, and 650 °C) for 30, 300, and 3000 hours, respectively. Surface cavities and debris dragging, sub-surface cracks, high intensity of plastic deformation, as well as the generation of tensile residual stresses were identified to be the main issues in surface integrity for the broached Inconel 718. When a subsequent heating was applied, surface recrystallization and α-Cr precipitation occurred beneath the broached surface depending on the applied temperature and exposure time. The plastic deformation induced by the broaching is responsible for these microstructural changes. The surface tension was completely relaxed in a short time at the temperature where surface recrystallization occurred. The tensile layer on the sub-surface, however, exhibited a much higher resistance to the stress relief annealing. Oxidation is inevitable at high temperatures. The study found that the surface recrystallization could promote the local Cr diffusion on the broached surface.

  16. Oxidation Behaviors of Inconel 740H in Air and Dynamic Steam

    NASA Astrophysics Data System (ADS)

    Lu, Jintao; Yang, Zhen; Xu, Songqian; Zhao, Haiping; Gu, Y.

    2016-08-01

    Inconel 740H alloy is a candidate material for 700°C advanced ultra-supercritical (A-USC) coal-fired power plants application as superheater/reheater tube. In this work, oxidation behavior of Inconel 740H alloy was studied in static air at 750°C and 850°C, and in dynamic pure steam at 750°C, respectively. The alloy was oxidized approximately following a parabolic law in three test environment. In the static air, the oxidation rate at 850°C was about 50 times of that at the 750°C. More NiCrMn spinal and TiO2 were detected after oxidation at 850°C. Cr2O3, however, was the main oxidation product at 750°C. In the pure steam, Cr2O3 was still the main oxidation product. The oxidation rate was about 2.6 times of that in static air, but the surface roughness was much smaller and edges of oxide particles were more blurred. There was no evidence of cracks or spallation in three test environments.

  17. An experimental assessment on the performance of different lubrication techniques in grinding of Inconel 751.

    PubMed

    Balan, A S S; Vijayaraghavan, L; Krishnamurthy, R; Kuppan, P; Oyyaravelu, R

    2016-09-01

    The application of emulsion for combined heat extraction and lubrication requires continuous monitoring of the quality of emulsion to sustain a desired grinding environment; this is applicable to other grinding fluids as well. Thus to sustain a controlled grinding environment, it is necessary to adopt an effectively lubricated wheel-work interface. The current study was undertaken to assess experimentally the ​ effects of different grinding environments such as dry, minimum quantity lubrication (MQL) and Cryo-MQL on performance, such as grinding force, temperature, surface roughness and chip morphology on Inconel 751, a higher heat resistance material posing thermal problems and wheel loading. The results show that grinding with the combination of both liquid nitrogen (LN2) and MQL lowers temperature, cutting forces, and surface roughness as compared with MQL and dry grinding. Specific cutting energy is widely used as an inverse measure of process efficiency in machining. It is found from the results that specific cutting energy of Cryo-MQL assisted grinding is 50-65% lower than conventional dry grinding. The grindability of Inconel 751 superalloy can be enhanced with Cryo-MQL condition. PMID:27621941

  18. Laser post-processing of Inconel 625 made by selective laser melting

    NASA Astrophysics Data System (ADS)

    Witkin, David; Helvajian, Henry; Steffeney, Lee; Hansen, William

    2016-04-01

    The effect of laser remelting of surfaces of as-built Selective Laser Melted (SLM) Inconel 625 was evaluated for its potential to improve the surface roughness of SLM parts. Many alloys made by SLM have properties similar to their wrought counterparts, but surface roughness of SLM-made parts is much higher than found in standard machine shop operations. This has implications for mechanical properties of SLM materials, such as a large debit in fatigue properties, and in applications of SLM, where surface roughness can alter fluid flow characteristics. Because complexity and netshape fabrication are fundamental advantages of Additive Manufacturing (AM), post-processing by mechanical means to reduce surface roughness detracts from the potential utility of AM. Use of a laser to improve surface roughness by targeted remelting or annealing offers the possibility of in-situ surface polishing of AM surfaces- the same laser used to melt the powder could be amplitude modulated to smooth the part during the build. The effects of remelting the surfaces of SLM Inconel 625 were demonstrated using a CW fiber laser (IPG: 1064 nm, 2-50 W) that is amplitude modulated with a pulse profile to induce remelting without spallation or ablation. The process achieved uniform depth of melting and improved surface roughness. The results show that with an appropriate pulse profile that meters the heat-load, surface features such as partially sintered powder particles and surface connected porosity can be mitigated via a secondary remelting/annealing event.

  19. Control of the kerf size and microstructure in Inconel 738 superalloy by femtosecond laser beam cutting

    NASA Astrophysics Data System (ADS)

    Wei, J.; Ye, Y.; Sun, Z.; Liu, L.; Zou, G.

    2016-05-01

    Femtosecond laser beam cutting is becoming widely used to meet demands for increasing accuracy in micro-machining. In this paper, the effects of processing parameters in femtosecond laser beam cutting on the kerf size and microstructure in Inconel 738 have been investigated. The defocus, pulse width and scanning speed were selected to study the controllability of the cutting process. Adjusting and matching the processing parameters was a basic enhancement method to acquire well defined kerf size and the high-quality ablation of microstructures, which has contributed to the intensity clamping effect. The morphology and chemical compositions of these microstructures on the cut surface have been characterized by a scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Additionally, the material removal mechanism and oxidation mechanism on the Inconel 738 cut surface have also been discussed on the basis of the femtosecond laser induced normal vaporization or phase explosion, and trapping effect of the dangling bonds.

  20. Relationship between ferromagnetic properties and grain size of Inconel alloy 600

    NASA Astrophysics Data System (ADS)

    Kikuchi, H.; Takahashi, H.; Yanagiwara, H.; Murakami, T.

    2015-05-01

    Inconel alloy 600 is widely used in steam generator tubings where sensitization due to chromium depletion occurs at grain boundaries and the sensitization induces tubing failures. Though the alloy usually exhibits paramagnetic properties, it shows ferromagnetic properties along grain boundaries when chromium depletion occurs. This means that magnetic nondestructive evaluation of sensitization is possible. Therefore, as a fundamental study to develop magnetic nondestructive evaluation technique for sensitization, the relationship between ferromagnetic properties and grain size in Inconel 600 was investigated using isothermal heat treatment. The grain was controlled using solution annealing, and then, specimens were heat treated at 873, 923, and 973 K within 400 h. The saturation magnetization increases as heat treatment time increases and eventually peaks. The peak time depends on the heat treatment temperature. The coercivity increases during the initial heat treatment stage, and decreases as the duration of heat treatment increases. The maximum saturation magnetization decreases as the grain diameter increases and is inversely proportional to the grain diameter squared, which is consistent with the fact that the ferromagnetic phase only formed along grain boundaries.

  1. Analysis of Deformation in Inconel 718 When the Stress Anomaly and Dynamic Strain Aging Coexist

    NASA Astrophysics Data System (ADS)

    Follansbee, Paul S.

    2016-09-01

    Deformation in Inconel 718 in the presence of combined effects of the stress anomaly and dynamic strain aging is analyzed according to an internal state variable model formulation. The analysis relies on the availability of experimental data in regimes of behavior where both the stress anomaly and dynamic strain aging are absent. A model that introduces two internal state variables—one characterizing interactions of dislocations with solute atoms and one characterizing interaction of dislocations with precipitates—is shown to adequately describe the temperature and strain-rate dependence of the yield stress in several superalloy systems. Strain hardening is then added with a third internal state variable to enable description of the full stress-strain curve. These equations are extrapolated into regimes where the stress anomaly and dynamic strain aging are present to identify signatures of their effects and to compare to similar analyses in a variety of metal systems. Dynamic strain aging in Inconel 718 follows similar trends to those observed previously. The magnitude of the stress anomaly tracks measurements of stress vs test temperature in pure Ni3Al. Several trends in the strain-rate sensitivity of elevated temperature deformation in superalloys are identified based on limited availability of measurements over a wide range of strain rates or tests using strain-rate changes.

  2. Discontinuous Dynamic Recrystallization of Inconel 718 Superalloy During the Superplastic Deformation

    NASA Astrophysics Data System (ADS)

    Huang, Linjie; Qi, Feng; Hua, Peitao; Yu, Lianxu; Liu, Feng; Sun, Wenru; Hu, Zhuangqi

    2015-09-01

    The superplastic behavior of Inconel 718 superalloy with particular emphasis on the microstructural evolution has been systematically investigated through tensile tests at the strain rate of 10-3 s-1 and the temperatures ranging from 1223 K to 1253 K (950 °C to 980 °C). Its elongations exceeded 300 pct under all of the experimental conditions and peaked a maximum value of 520 pct at 1223 K (950 °C). Moreover, the stress reached the top value at the strain of 0.3, and then declined until the tensile failure. In addition, we have found that the grain size reduced after deformation while the δ phase precipitation increased. Microstructural evolution during the superplasticity was characterized via transmission electron microscope, and the randomly distributed dislocation, dislocation network, dislocation arrays, low-angled subgrains, and high-angled recrystallized new grains were observed in sequence. These new grains were found to nucleate at the triple junction, twin boundary, and near the δ phase. Based on these results, it is deemed that the discontinuous dynamic recrystallization occurred as the main mechanism for the superplastic deformation of Inconel 718 alloy.

  3. Laser brazing of inconel 718 alloy with a silver based filler metal

    NASA Astrophysics Data System (ADS)

    Khorram, A.; Ghoreishi, M.; Torkamany, M. J.; Bali, M. M.

    2014-03-01

    In the presented study laser brazing of an inconel 718 alloy with silver based filler metal using 400 W pulsed Nd:YAG laser is investigated. Laser brazing was performed with varying laser frequency, pulse width, process speed and gap distance. The effect of preheating on wetting and spreading also was studied. Brazing geometrical images were observed using an optical microscope. The composition analysis and microstructure of the filler metal and brazed joints were examined using X-ray diffraction analyzer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Micro-hardness and tensile test were performed for investigation of mechanical properties. The experimental observations show that filler metal consist of α-Ag solid solution, ά-Cu solid solution surround by the α-Ag solid solution and eutectic structure. Phases of the brazed joint are similar to the filler metal. The results indicate that the filler metal has adequate wetting and spreading on inconel 718 and the wetting angle depends on the heat input significantly. Interdiffusion occurs in laser brazing and the average thickness of reaction layer is approximately 2.5 μm. Whenever the gap is big, it is needed to use longer pulse width in order to have a better melting flow. Preheating has significant influence on wetting and spreading of the filler metal.

  4. Effect of service exposure on fatigue crack propagation of Inconel 718 turbine disc material at elevated temperatures

    SciTech Connect

    Jeong, Dae-Ho; Choi, Myung-Je; Goto, Masahiro; Lee, Hong-Chul; Kim, Sangshik

    2014-09-15

    In this study, the fatigue crack propagation behavior of Inconel 718 turbine disc with different service times from 0 to 4229 h was investigated at 738 and 823 K. No notable change in microstructural features, other than the increase in grain size, was observed with increasing service time. With increasing service time from 0 to 4229 h, the fatigue crack propagation rates tended to increase, while the ΔK{sub th} value decreased, in low ΔK regime and lower Paris' regime at both testing temperatures. The fractographic observation using a scanning electron microscope suggested that the elevated temperature fatigue crack propagation mechanism of Inconel 718 changed from crystallographic cleavage mechanism to striation mechanism in the low ΔK regime, depending on the grain size. The fatigue crack propagation mechanism is proposed for the crack propagating through small and large grains in the low ΔK regime, and the fatigue crack propagation behavior of Inconel 718 with different service times at elevated temperatures is discussed. - Highlights: • The specimens were prepared from the Inconel 718 turbine disc used for 0 to 4229 h. • FCP rates were measured at 738 and 823 K. • The ΔK{sub th} values decreased with increasing service time. • The FCP behavior showed a strong correlation with the grain size of used turbine disc.

  5. Microstructure and Properties of the Ti6Al4V/Inconel 625 Bimetal Obtained by Explosive Joining

    NASA Astrophysics Data System (ADS)

    Topolski, Krzysztof; Szulc, Zygmunt; Garbacz, Halina

    2016-08-01

    The study is concerned with the bimetallic plate composed of the Ti6Al4V and Inconel 625 alloys. The alloys were joined together using the explosive method with the aim to produce a bimetallic joint. The structure and the mechanical properties of the as-received raw Ti6Al4V and Inconel 625 alloys, the Ti6Al4V/Inconel 625 joint, and the joint after annealing (600 °C for 1 h) were examined. The samples observations were performed using a light microscope and a scanning electron microscope. The mechanical properties were estimated by microhardness measurements, tensile tests, and three-point bending tests. Moreover, the deformation strengthening of the metals and the strength of the joint were analyzed. The explosive process resulted in a good quality bimetallic joint. Both sheets were deformed plastically and the joint surface between the alloys had a wavy shape. In the area of the joint surface, the hardness was increased. For example, the annealing at 600 °C for 1 h resulted in changes of the microhardness in the entire volume of the samples and in changes of the morphology of the joint surface. In three-point bending tests, the samples were examined in two opposite positions (Ti6Al4V on the top or Inconel 625 on the top). The results indicated to depend on the position in which the sample was tested.

  6. Tensile Properties and Microstructure of Inconel 718 Fabricated with Electron Beam Freeform Fabrication (EBF(sup 3))

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Hibberd, Joshua

    2009-01-01

    Electron beam freeform fabrication (EBF3) direct metal deposition processing was used to fabricate two Inconel 718 single-bead-width wall builds and one multiple-bead-width block build. Specimens were machined to evaluate microstructure and room temperature tensile properties. The tensile strength and yield strength of the as-deposited material from the wall and block builds were greater than those for conventional Inconel 718 castings but were less than those for conventional cold-rolled sheet. Ductility levels for the EBF3 material were similar to those for conventionally-processed sheet and castings. An unexpected result was that the modulus of the EBF3-deposited Inconel 718 was significantly lower than that of the conventional material. This low modulus may be associated with a preferred crystallographic orientation resultant from the deposition and rapid solidification process. A heat treatment with a high solution treatment temperature resulted in a recrystallized microstructure and an increased modulus. However, the modulus was not increased to the level that is expected for Inconel 718.

  7. Microstructure and Properties of the Ti6Al4V/Inconel 625 Bimetal Obtained by Explosive Joining

    NASA Astrophysics Data System (ADS)

    Topolski, Krzysztof; Szulc, Zygmunt; Garbacz, Halina

    2016-04-01

    The study is concerned with the bimetallic plate composed of the Ti6Al4V and Inconel 625 alloys. The alloys were joined together using the explosive method with the aim to produce a bimetallic joint. The structure and the mechanical properties of the as-received raw Ti6Al4V and Inconel 625 alloys, the Ti6Al4V/Inconel 625 joint, and the joint after annealing (600 °C for 1 h) were examined. The samples observations were performed using a light microscope and a scanning electron microscope. The mechanical properties were estimated by microhardness measurements, tensile tests, and three-point bending tests. Moreover, the deformation strengthening of the metals and the strength of the joint were analyzed. The explosive process resulted in a good quality bimetallic joint. Both sheets were deformed plastically and the joint surface between the alloys had a wavy shape. In the area of the joint surface, the hardness was increased. For example, the annealing at 600 °C for 1 h resulted in changes of the microhardness in the entire volume of the samples and in changes of the morphology of the joint surface. In three-point bending tests, the samples were examined in two opposite positions (Ti6Al4V on the top or Inconel 625 on the top). The results indicated to depend on the position in which the sample was tested.

  8. Effect of Double Aging Heat Treatment on the Short-Term Creep Behavior of the Inconel 718

    NASA Astrophysics Data System (ADS)

    Caliari, Felipe Rocha; Candioto, Kátia Cristiane Gandolpho; Couto, Antônio Augusto; Nunes, Carlos Ângelo; Reis, Danieli Aparecida Pereira

    2016-06-01

    This research studies the effect of double aging heat treatment on the short-term creep behavior of the superalloy Inconel 718. The superalloy, received in the solution treated state, was subjected to an aging treatment which comprises a solid solution at 1095 °C for 1 h, a first aging step of 955 °C for 1 h, then aged at 720 and 620 °C, 8 h each step. Creep tests at constant load mode, under temperatures of 650, 675, 700 °C and stress of 510, 625 and 700 MPa, were performed before and after heat treatment. The results indicate that after the double aging heat treatment creep resistance is increased, influenced by the presence of precipitates γ' and γ″ and its interaction with the dislocations, by grain size growth (from 8.20 to 7.23 ASTM) and the increase of hardness by approximately 98%. Creep parameters of primary and secondary stages have been determined. There is a breakdown relationship between dot{\\upvarepsilon }_{{s}} and stress at 650 °C of Inconel 718 as received, around 600 MPa. By considering the internal stress values, effective stress exponent, effective activation energy, and TEM images of Inconel 718 double aged, it is suggested that the creep mechanism is controlled by the interaction of dislocations with precipitates. The fracture mechanism of Inconel 718 as received is transgranular (coalescence of dimples) and mixed (transgranular-intergranular), whereas the Inconel 718 double aged condition crept surfaces evidenced the intergranular fracture mechanism.

  9. Texture-Induced Anisotropy in an Inconel 718 Alloy Deposited Using Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Tayon, W.; Shenoy, R.; Bird, R.; Hafley, R.; Redding, M.

    2014-01-01

    A test block of Inconel (IN) 718 was fabricated using electron beam freeform fabrication (EBF(sup 3)) to examine how the EBF(sup 3) deposition process affects the microstructure, crystallographic texture, and mechanical properties of IN 718. Tests revealed significant anisotropy in the elastic modulus for the as-deposited IN 718. Subsequent tests were conducted on specimens subjected to a heat treatment designed to decrease the level of anisotropy. Electron backscatter diffraction (EBSD) was used to characterize crystallographic texture in the as-deposited and heat treated conditions. The anisotropy in the as-deposited condition was strongly affected by texture as evidenced by its dependence on orientation relative to the deposition direction. Heat treatment resulted in a significant improvement in modulus of the EBF(sup 3) product to a level nearly equivalent to that for wrought IN 718 with reduced anisotropy; reduction in texture through recrystallization; and production of a more homogeneous microstructure.

  10. Properties of Inconel 625 Mesh Structures Grown by Electron Beam Additive Manufacturing

    SciTech Connect

    List III, Frederick Alyious; Dehoff, Ryan R; Lowe, Larry E; Sames, William J

    2014-01-01

    Relationships between electron beam parameters (beam current, beam speed, and beam focus) and physical properties (mass, diameter, elastic modulus, and yield strength) have been investigated for Inconel 625 mesh cubes fabricated using an additive manufacturing technology based on electron beam melting. The elastic modulus and yield strength of the mesh cubes have been systematically varied by approximately a factor of ten by changing the electron beam parameters. Simple models have been used to understand better these relationships. Structural anisotropies of the mesh associated with the layered build architecture have been observed and may contribute, along with microstructural anisotropies, to the anisotropic mechanical properties of the mesh. Knowledge of this kind is likely applicable to other metal and alloy systems and is essential to rapidly realize the full potential of this burgeoning technology.

  11. Study of delta phase on static recrystallization behavior of Inconel 718 alloy.

    PubMed

    Lee, Hwa-Teng; Hou, Wen-Hsin

    2012-09-01

    The mechanical properties of Inconel 718 alloy depend on its microstructural features. Controlling the grain size during manufacturing is currently achieved through the use of a powerful hot forming process performed at a temperature sufficiently high to induce dynamic recrystallization. The present study proposes an alternative technique to achieve a uniform fine grain structure by using static recrystallization and a proper control of delta precipitation. The results show that a fine structure with an average grain size of ASTM No. 7 can be achieved. And in this study the finest grains yet achievable is ca. 200 nm. As a result, the proposed technique provides a feasible means of controlling the grain size without the need for an energy consumption and technically sophisticated hot forming process.

  12. Neutron Diffraction Characterization of Residual Strain in Welded Inconel 718 for NASA Space Shuttle Flow Liners

    SciTech Connect

    Rathod, C.R.; Vaidyanathan, R.; Livescu, V.; Clausen, B.; Bourke, M. A. M.; Notardonato, W.U.; Femminineo, M.

    2004-06-28

    This work quantitatively assesses residual strains and stresses associated with the weld repair process used to repair cracks on NASA's space shuttle flow liners. The coupons used in this investigation were made of the same INCONEL 718 alloy used for the flow liners. They were subjected to identical welding and certification procedures that were carried out on the space shuttle. Neutron diffraction measurements at Los Alamos National Laboratory determined residual strains at selected locations in a welded coupon at 293 K and 135 K. The weld repair process introduced Mises effective residual stresses of up to 555 MPa. On comparing the measurements at 293 K and 135 K, no significant change to the residual strain profile was noted at the low temperature. This indicated minimal mismatch in the coefficients of thermal expansion between the base metal and the weld.

  13. Crystallographic texture engineering through novel melt strategies via electron beam melting: Inconel 718

    SciTech Connect

    Dehoff, Ryan R.; Kirka, Michael M.; List, III, Frederick Alyious; Unocic, Kinga A.; Sames, William J.

    2014-01-01

    Preliminary research has demonstrated the ability to utilise novel scan strategies in the electron beam melting (EBM) process to establish control of crystallographic texture within Inconel 718 deposits. Conventional EBM scan strategies and process parameters yield coarse columnar grains aligned parallel to the build direction. Through varying process parameters such as beam power, beam velocity, beam focus and scan strategy, the behaviour of the electron beam can be manipulated from a line source to a point source. The net effect of these variations is that the resulting crystallographic texture is controlled in a manner to produce either epitaxial deposits or fully equiaxed deposits. Furthermore, this research demonstrates the ability to change the crystallographic texture on the macroscale indicating that EBM technology can be used to create complex geometric components with both site-specific microstructures and material properties.

  14. The effects of multiple repairs on Inconel 718 weld mechanical properties

    NASA Technical Reports Server (NTRS)

    Russell, C. K.; Nunes, A. C., Jr.; Moore, D.

    1991-01-01

    Inconel 718 weldments were repaired 3, 6, 9, and 13 times using the gas tungsten arc welding process. The welded panels were machined into mechanical test specimens, postweld heat treated, and nondestructively tested. Tensile properties and high cycle fatigue life were evaluated and the results compared to unrepaired weld properties. Mechanical property data were analyzed using the statistical methods of difference in means for tensile properties and difference in log means and Weibull analysis for high cycle fatigue properties. Statistical analysis performed on the data did not show a significant decrease in tensile or high cycle fatigue properties due to the repeated repairs. Some degradation was observed in all properties, however, it was minimal.

  15. Deformation characteristics of {delta} phase in the delta-processed Inconel 718 alloy

    SciTech Connect

    Zhang, H.Y.; Zhang, S.H.; Cheng, M.; Li, Z.X.

    2010-01-15

    The hot working characteristics of {delta} phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 deg. C and strain rate of 0.005 s{sup -1}, were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like {delta} phase and the precipitation of spherical {delta} phase particles coexisted during the deformation, and the content of {delta} phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like {delta} phase was spheroidized and transferred to spherical {delta} phase particles. In the center with largest strain, the plate-like {delta} phase disappeared and spherical {delta} phase appeared in the interior of grains and grain boundaries.

  16. High-rate laser metal deposition of Inconel 718 component using low heat-input approach

    NASA Astrophysics Data System (ADS)

    Kong, C. Y.; Scudamore, R. J.; Allen, J.

    Currently many aircraft and aero engine components are machined from billets or oversize forgings. This involves significant cost, material wastage, lead-times and environmental impacts. Methods to add complex features to another component or net-shape surface would offer a substantial cost benefit. Laser Metal Deposition (LMD), currently being applied to the repair of worn or damaged aero engine components, was attempted in this work as an alternative process route, to build features onto a base component, because of its low heat input capability. In this work, low heat input and high-rate deposition was developed to deposit Inconel 718 powder onto thin plates. Using the optimised process parameters, a number of demonstrator components were successfully fabricated.

  17. Neutron Diffraction Characterization of Residual Strain in Welded Inconel 718 for NASA Space Shuttle Flow Liners

    NASA Astrophysics Data System (ADS)

    Rathod, C. R.; Livescu, V.; Clausen, B.; Bourke, M. A. M.; Notardonato, W. U.; Femminineo, M.; Vaidyanathan, R.

    2004-06-01

    This work quantitatively assesses residual strains and stresses associated with the weld repair process used to repair cracks on NASA's space shuttle flow liners. The coupons used in this investigation were made of the same INCONEL 718 alloy used for the flow liners. They were subjected to identical welding and certification procedures that were carried out on the space shuttle. Neutron diffraction measurements at Los Alamos National Laboratory determined residual strains at selected locations in a welded coupon at 293 K and 135 K. The weld repair process introduced Mises effective residual stresses of up to 555 MPa. On comparing the measurements at 293 K and 135 K, no significant change to the residual strain profile was noted at the low temperature. This indicated minimal mismatch in the coefficients of thermal expansion between the base metal and the weld.

  18. Rationalization of Microstructure Heterogeneity in INCONEL 718 Builds Made by the Direct Laser Additive Manufacturing Process

    NASA Astrophysics Data System (ADS)

    Tian, Yuan; McAllister, Donald; Colijn, Hendrik; Mills, Michael; Farson, Dave; Nordin, Mark; Babu, Sudarsanam

    2014-09-01

    Simulative builds, typical of the tip-repair procedure, with matching compositions were deposited on an INCONEL 718 substrate using the laser additive manufacturing process. In the as-processed condition, these builds exhibit spatial heterogeneity in microstructure. Electron backscattering diffraction analyses showed highly misoriented grains in the top region of the builds compared to those of the lower region. Hardness maps indicated a 30 pct hardness increase in build regions close to the substrate over those of the top regions. Detailed multiscale characterizations, through scanning electron microscopy, electron backscattered diffraction imaging, high-resolution transmission electron microscopy, and ChemiSTEM, also showed microstructure heterogeneities within the builds in different length scales including interdendritic and interprecipitate regions. These multiscale heterogeneities were correlated to primary solidification, remelting, and solid-state precipitation kinetics of γ″ induced by solute segregation, as well as multiple heating and cooling cycles induced by the laser additive manufacturing process.

  19. Some aspects of the precipitation of metastable intermetallic phases in INCONEL 718

    NASA Astrophysics Data System (ADS)

    Sundararaman, M.; Mukhopadhyay, P.; Banerjee, S.

    1992-07-01

    Some aspects of the precipitation of the metastable intermetallic phases —γ″ and γ″—in the commercial nickel base superalloy, INCONEL 718, have been investigated over a wide range of aging temperatures. It has been confirmed that the spherical γ″ particles and the ellipsoidal γ″ particles evolve predominantly through homogeneous nucleation. Precipitation of the former does not appear to precede that of the latter in this alloy. The tetragonal distortion associated with the γ″ particles has been found to increase with increasing precipitate size. It has been observed that at certain temperatures, physical association between precipitates of the two types occurs frequently, leading to the development of different composite precipitate morphologies. During coarsening, the precipitate size has been found to depend linearly on the cube root of the aging time for γ' as well as γ″ particles.

  20. Effect of broaching on high-temperature fatigue behavior in notched specimens of INCONEL 718

    NASA Astrophysics Data System (ADS)

    Connolley, T.; Starink, M. J.; Reed, P. A. S.

    2004-03-01

    Notches were machined in specimens of INCONEL 718 by a broaching process, where differing broaching runs led to differing extents of subsurface deformation and surface roughness. Fatigue tests were carried out at 600 °C with a trapezoidal loading waveform at 0.25 Hz. The broaching process that led to the more severe subsurface deformation (but lower surface roughness) showed the worst fatigue performance. Analysis of total strain amplitude in the notch root with the aid of an elastoplastic finite-element (FE) model showed that the work hardening related to the subsurface deformation caused by the different broaching can account for the difference in fatigue lives. Differences in initiation and growth behavior were seen for the two broached finishes as well as for broached and subsequently polished samples. These differences are discussed in terms of a change in crack growth initiation and growth mechanisms due to the presence of the work-hardened layer.

  1. Crystallographic texture engineering through novel melt strategies via electron beam melting: Inconel 718

    DOE PAGES

    Dehoff, Ryan R.; Kirka, Michael M.; List, III, Frederick Alyious; Unocic, Kinga A.; Sames, William J.

    2014-01-01

    Preliminary research has demonstrated the ability to utilise novel scan strategies in the electron beam melting (EBM) process to establish control of crystallographic texture within Inconel 718 deposits. Conventional EBM scan strategies and process parameters yield coarse columnar grains aligned parallel to the build direction. Through varying process parameters such as beam power, beam velocity, beam focus and scan strategy, the behaviour of the electron beam can be manipulated from a line source to a point source. The net effect of these variations is that the resulting crystallographic texture is controlled in a manner to produce either epitaxial deposits ormore » fully equiaxed deposits. Furthermore, this research demonstrates the ability to change the crystallographic texture on the macroscale indicating that EBM technology can be used to create complex geometric components with both site-specific microstructures and material properties.« less

  2. Calorimetric and transport properties of Zircalloy 2, Zircalloy 4, and Inconel 625

    NASA Astrophysics Data System (ADS)

    Maglić, K. D.; Perović, N. Lj.; Stanimirović, A. M.

    1994-07-01

    This paper presents the measurements and the results on thermal and electrical transport properties of three nuclear reactor cladding materials: Zircalloy 2, Zircalloy 4, and Inconel 625. Study of these materials constituted a part of the IAEA coordinated research program aimed at the generation and establishment of a reliable and complete database of the thermal properties of reactor materials. Measured properties include thermal diffusivity, specific heat, and electrical resistivity. Thermal diffusivity was measured by the laser pulse technique. Specific heat and electrical resistivity were measured using a millisecond-resolution direct electrical pulse heating technique. Thermal conductivity was computed from the experimentally determined thermal difusivity and specific heat functions and the room temperature density values. Measurements were performed in the 20 to 1500°C temperature range, depending on the material and property concerned.

  3. Mechanical Properties of INCONEL 718 Parts Manufactured by Shaped Metal Deposition (SMD)

    NASA Astrophysics Data System (ADS)

    Baufeld, Bernd

    2012-07-01

    INCONEL 718 parts have been manufactured by shaped metal deposition (SMD), an additive layer manufacturing technique applying wire-based tungsten inert gas welding. This technique is aimed toward mass customization of parts, omitting time- and scrap-intensive, subtractive fabrication routes. SMD results in dense, "near net-shaped" parts without pores, cracks, or fissures. The microstructure of the SMD parts exhibit large, columnar grains with a fine dendritic microstructure. The interdendritic boundaries are decorated by small Laves phase precipitates and by MC carbides. Tensile tests were performed with different strain rates (10-4, 10-3, and 2 × 10-3 1/s), but no dependency on strength or strain at failure was observed. The ultimate tensile strength was 828 ± 8 MPa, the true plastic strain at failure 28 ± 2%, the micro Vickers hardness 266 ± 21 HV200, and the dynamically measured Young's module was 154 ± 1 GPa.

  4. Laser controlled melting of pre-prepared inconel 718 alloy surface

    NASA Astrophysics Data System (ADS)

    Abdul Aleem, B. J.; Hashmi, M. S. J.; Yilbas, B. S.

    2011-11-01

    Laser treatment of Inconel 718 alloy surface is carried out. The alloy surface is coated with a carbon layer containing 7% TiC particles prior to the laser treatment. The carbon coating provides increased absorption of the incident laser beam and holds TiC particles. The microstrutural and morphological changes in the laser treated region are examined using optical and scanning electron microscopes, energy dispersive spectroscopy, and X-ray diffraction. The microhardness of the surface is measured and the residual stress formed at the surface vicinity is determined from the XRD technique. It is found that partial dissolution of carbide particles takes place at the surface. The composition of fine grains at the surface vicinity, nitride compounds formed, and dissolution of Laves phase at the surface region enhances the hardness at the treated surface. In addition, laser treated surface is free from the micro-crack network and cavities.

  5. Segregation of B, P, and C in the Ni-Based Superalloy, Inconel 718

    NASA Astrophysics Data System (ADS)

    Alam, Talukder; Felfer, Peter J.; Chaturvedi, Mahesh; Stephenson, Leigh T.; Kilburn, Matthew R.; Cairney, Julie M.

    2012-07-01

    Small additions of B, P, and C can result in dramatic changes in the mechanical performance and welding behavior of Inconel 718. Although additions of B and P improve the mechanical properties, they have a detrimental effect on weldability. Adding C mitigates the negative effect on welding while retaining the improvements in mechanical performance. In this study, precise observations of the segregation of B, P, and C to the grain boundaries are made using site-specific atom probe tomography and NanoSIMS. Changes in the segregation behavior provide a quantitative explanation for the welding response, where hot cracking is attributed to the formation of a eutectic film. Calculations of the relative positions of the B, P, and C revealed that these atoms were less likely to cluster together in the presence of C, providing insight into the likely mechanisms behind the segregation behavior in this complex, multicomponent alloy.

  6. Performance of Silicon carbide whisker reinforced ceramic inserts on Inconel 718 in end milling process

    NASA Astrophysics Data System (ADS)

    Reddy, M. M.; Joshua, C. X. H.

    2016-03-01

    An experimental investigation is planned in order to study the machinability of Inconel 718 with silicon carbide whisker reinforced ceramic inserts in end milling process. The relationship between the cutting speed, feed rate, and depth of cut against the response factors are studied to show the level of significance of each parameter. The cutting parameters are optimized by using Taguchi method. Implementing analysis of variance, the parameter which influences the surface roughness the most is determined to be the cutting speed, followed by the feed rate and depth of cut. Meanwhile, the optimal cutting condition is determined to have high cutting speed, low feed rate, and high depth of cut in the range of selected parameters.

  7. Comparison of calculated and observed cyclic stress-strain relationships for Inconel Alloy 625 at 650 to 1100/sup 0/C

    SciTech Connect

    Purohit, A.; Ewing, T.F.; Thiele, U.

    1983-06-01

    It is concluded that both the bilinear stress-strain and creep laws used with the ANSYS spar element model and the stress relaxation method are able to describe and predict fatigue behavior of Inconel Alloy 625.

  8. The performance of Inconel 693 electrodes for processing an iron phosphate glass melt containing 26 wt.% of a simulated low activity waste

    NASA Astrophysics Data System (ADS)

    Hsu, Jen-Hsien; Newkirk, Joseph W.; Kim, Cheol-Woon; Brow, Richard K.; Schlesinger, Mark E.; Ray, Chandra S.; Day, Delbert E.

    2014-01-01

    Iron phosphate glass is a candidate fixation medium for storing radioactive waste. The Department of Energy supported a program to assess the viability of using Fe-phosphate glass for vitrifying low activity waste in a Joule Heated Melter (JHM). In this study, Inconel 693 electrodes were tested in a research-scale joule-heated melter (RSM) at Pacific Northwest National Laboratory. After a 10-day test at 1030 °C that yielded 124 kg of glass, the electrodes exhibited a dimensional loss rate of ∼1.6 mm/year, which is comparable to that of Inconel 690 electrodes used in a JHM for processing borosilicate melts. Microstructural changes occurred within the outermost 700 μm of the electrodes and are consistent with an earlier study of Inconel coupons in Fe-phosphate melts. The results indicate that Inconel 693 should have an acceptable corrosion resistance as the electrode for JHM processing of iron phosphate melts.

  9. Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

    NASA Astrophysics Data System (ADS)

    Vesel, Alenka; Drenik, Aleksander; Elersic, Kristina; Mozetic, Miran; Kovac, Janez; Gyergyek, Tomaz; Stockel, Jan; Varju, Jozef; Panek, Radomir; Balat-Pichelin, Marianne

    2014-06-01

    Initial stages of Inconel 625 superalloy (Ni60Cr30Mo10Ni4Nb1) oxidation upon short treatment with gaseous plasma at different temperatures up to about 1600 K were studied. Samples were treated for different periods up to a minute by oxygen or hydrogen plasma created with a microwave discharge in the standing-wave mode at a pressure of 40 Pa and a power 500 W. Simultaneous heating of the samples was realized by focusing concentrated solar radiation from a 5 kW solar furnace directly onto the samples. The morphological changes upon treatment were monitored using scanning electron microscopy, compositional depth profiling was performed using Auger electron spectroscopy, while structural changes were determined by X-ray diffraction. The treatment in oxygen plasma caused formation of metal oxide clusters of three dimensional crystallites initially rich in nickel oxide with the increasing chromium oxide content as the temperature was increasing. At about 1100 K iron and niobium oxides prevailed on the surface causing a drop of the material emissivity at 5 μm. Simultaneously the NiCr2O4 compound started growing at the interface between the oxide film and bulk alloy and the compound persisted up to temperatures close to the Inconel melting point. Intensive migration of minority alloying elements such as Fe and Ti was observed at 1600 K forming mixed surface oxides of sub-micrometer dimensions. The treatment in hydrogen plasma with small admixture of water vapor did not cause much modification unless the temperature was close to the melting point. At such conditions aluminum segregated on the surface and formed well-defined Al2O3 crystals.

  10. Microstructural evolution of CANDU spacer material Inconel X-750 under in situ ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, He Ken; Yao, Zhongwen; Judge, Colin; Griffiths, Malcolm

    2013-11-01

    Work on Inconel®Inconel® is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys.1 X-750 spacers removed from CANDU®CANDU® is a registered trademark of Atomic Energy of Canada Limited standing for ''CANada Deuterium Uranium''.2 reactors has shown that they become embrittled and there is development of many small cavities within the metal matrix and along grain boundaries. In order to emulate the neutron irradiation induced microstructural changes, heavy ion irradiations (1 MeV Kr2+ ions) were performed while observing the damage evolution using an intermediate voltage electron microscope (IVEM) operating at 200 kV. The irradiations were carried out at various temperatures 60-400 °C. The principal strengthening phase, γ‧, was disordered at low doses (˜0.06 dpa) during the irradiation. M23C6 carbides were found to be stable up to 5.4 dpa. Lattice defects consisted mostly of stacking fault tetrahedras (SFTs), 1/2<1 1 0> perfect loops and small 1/3<1 1 1> faulted Frank loops. The ratio of SFT number density to loop number density for each irradiation condition was found to be neither temperature nor dose dependent. Under the operation of the ion beam the SFT production was very rapid, with no evidence for further growth once formed, indicating that they probably formed as a result of cascade collapse in a single cascade. The number density of the defects was found to saturate at low dose (˜0.68 dpa). No cavities were observed regardless of the irradiation temperature between 60 °C and 400 °C for doses up to 5.4 dpa. In contrast, cavities have been observed after neutron irradiation in the same material at similar doses and temperatures indicating that helium, produce during neutron irradiation, may be essential for the nucleation and growth of cavities.

  11. Effect of cold drawing ratio on γ′ precipitation in Inconel X-750

    SciTech Connect

    Ha, Jeong Won; Seong, Baek Seok; Jeong, Hi Won; Yoo, Young Soo; Choi, Yoon Suk; Kang, Namhyun

    2014-10-15

    Inconel X-750 is a Ni-based precipitation-hardened superalloy having large tensile and fracture strengths. In the study, X-750 wires were cold drawn to different extents. Small angle neutron scattering was employed to quantitatively measure the size and volume fraction of the γ′ phase as a function of the cold drawing ratio (DR) and aging temperature. The presence and size of γ′ precipitates were confirmed by transmission electron microscopy. The drawing ratio had an important effect on the volume fraction of the γ′ precipitates. However, the size of the precipitates was independent on the drawing ratio. The specimen with the minimum drawing ratio (DR0) produced the largest volume fraction of γ′ as compared with large drawing ratio (DR) specimens such as DR17 and DR42. The small volume fraction of the γ′ phase for a sizeable drawing ratio was associated with the large amount of nucleation sites for secondary carbides, M{sub 23}C{sub 6}, and the fast diffusion path, i.e., dislocation, needed to form M{sub 23}C{sub 6}. A Cr depletion zone around the secondary carbides raised the solubility of γ′. Therefore, the significant drawing ratio contributing to the large volume fraction of the secondary carbides decreased the volume fraction of the γ′ precipitates in Inconel X-750. - Highlights: • The volume fraction of secondary carbides increased with the drawing ratio. • The volume fraction of γ′ decreased as the drawing ratio increased. • The drawing ratio affected the γ′ volume fraction with no variation of the γ' size. • The volume fraction of γ′ was affected by the secondary carbide volume fraction.

  12. Combination of Ultrasonic Vibration and Cryogenic Cooling for Cutting Performance Improvement of Inconel 718 Turning

    NASA Astrophysics Data System (ADS)

    Lin, S. Y.; Chung, C. T.; Cheng, Y. Y.

    2011-01-01

    The main objective of this study is to develop a thermo-elastic-plastic coupling model, based on a combination skill of ultrasonically assisted cutting and cryogenic cooling, under large deformation for Inconel 718 alloy machining process. The improvement extent on cutting performance and tool life promotion may be examined from this investigation. The critical value of the strain energy density of the workpiece will be utilized as the chip separation and the discontinuous chip segmentation criteria. The forced convection cooling and a hydrodynamic lubrication model will be considered and formulated in the model. Finite element method will be applied to create a complete numerical solution for this ultrasonic vibration cutting model. During the analysis, the cutting tool is incrementally advanced forward with superimposed ultrasonic vibration in a back and forth step-by-step manner, from an incipient stage of tool-workpiece engagement to a steady state of chip formation, a whole simulation of orthogonal cutting process under plane strain deformation is thus undertaken. High shear strength induces a fluctuation phenomenon of shear angle, high shear strain rate, variation of chip types and chip morphology, tool-chip contact length variation, the temperature distributions within the workpiece, chip and tool, periodic fluctuation in cutting forces can be determined from the developed model. A complete comparison of machining characteristics between some different combinations of ultrasonically assisted cutting and cryogenic cooling with conventional cutting operation can be acquired. Finally, the high-speed turning experiment for Inconel 718 alloy will be taken in the laboratory to validate the accuracy of the model, and the progressive flank wear, crater wear, notching and chipping of the tool edge can also be measured in the experiments.

  13. Cavitation formation and its minimization during superplastic forming of Inconel alloy 718SPF

    SciTech Connect

    Smith, G.D.; Flower, H.L.

    1995-12-31

    Superplastic forming of aluminum- and titanium-based alloys has become a significant manufacturing method for aerospace engine and fuselage components. Largely overlooked by design engineers is the applicability of fine-grained INCONEL{reg_sign} alloy 718SPF{trademark} to this process. This paper seeks to show the compatibility of this alloy to current superplastic forming practice and equipment. Processing parameters are presented based on laboratory data. INCONEL alloy 718SPF can be superplastically formed at 954 C (1,750 F) using flow stresses generally less than 72 MPa (10.4 psi) at an initial strain rate of 1.3 {times} 10{sup {minus}3} s{sup {minus}1} and < 28 MPa (4 psi) at 1.3 {times} 10{sup {minus}4} s{sup {minus}1}. The elongation to failure increases markedly with decreasing strain rate, exceeding 350% at an initial strain rate of 1.3 {times} 10{sup {minus}3} s{sup {minus}1}, 450% at 1.3 {times} 10{sup {minus}4} s{sup {minus}1} and 750% at 3.3 {times} 10{sup {minus}5} s{sup {minus}1}. Laboratory data are used to calculate m values (a measure of strain rate sensitivity) which increase from 0.28 at an initial strain rate of 1.3 {times} 10{sup {minus}3} s{sup {minus}1}, to 0.45 at 1.3 {times} 10{sup {minus}4} s{sup {minus}1} and to 0.83 at 3.3 {times} 10{sup {minus}5} s{sup {minus}1}.

  14. Low temperature magnetic transition and high temperature oxidation in INCONEL alloy 718

    SciTech Connect

    Seehra, M.S.; Babu, V.S.

    1996-05-01

    X-ray diffraction and temperature dependent (5 K{endash}380 K) magnetic measurements have been carried out in INCONEL 718 superalloy before and after high temperature aging treatments (INCONEL is a trademark of the INCO family of companies). The nominal composition of this alloy is Ni (52.5{percent}), Cr (19.0{percent}), Fe (18.5{percent}), Nb (5.1{percent}), Mo (3.0{percent}), Ti (0.9{percent}), Al (0.5{percent}), Cu (0.15{percent}) and C (0.08{percent}) and it yields an x-ray diffraction pattern consisting of a fcc phase with {ital a}=3.5987 (3) A and an orthorhombic phase associated with {delta}{minus}Ni{sub 3}Nb. It is concluded that the fcc pattern is due to both the {gamma} austenitic phase and {gamma}{prime} Ni{sub 3}(Al,Ti) phase of alloy 718. The standard annealing and aging treatment carried out in air at temperatures between 621 and 982{degree}C produces surface oxides (Cr,Fe){sub 2}O{sub 3} and FeNbO{sub 4} (which are easily removed by etching and polishing) and contracts the lattice. Magnetic measurements show a distinct phase transition at {ital T}{sub {ital c}}=14 K, which has been attributed to the {gamma}{prime}{minus}Ni{sub 3}(Al,Ti) phase by the process of elimination and by observing that it has most of the characteristics of the weak itinerant ferromagnet Ni{sub 74.5}Al{sub 25.5}. This transition may have some effects on the cryogenic applications of this alloy. {copyright} {ital 1996 Materials Research Society.}

  15. Recyclability study on Inconel 718 and Ti-6Al-4V powders for use in electron beam melting

    SciTech Connect

    Nandwana, Peeyush; Peter, William H.; Lowe, Larry E.; Dehoff, Ryan R.; Medina, Francisco; Babu, Sudarsanam Suresh; Kirka, Michael M.

    2015-10-20

    In this study, powder bed based additive manufacturing technologies offer a big advantage in terms of reusability of the powders over multiple cycles that result in cost savings. However, currently there are no standards to determine the factors that govern the powder reuse times. This work presents the results from a recyclability study conducted on Inconel 718 and Ti-6Al-4V powders. It has been found that the Inconel 718 powders are chemically stable over a large number of cycles and their reuse time is limited by physical characteristics of powders such as flowability. Ti-6Al-4V, on the other hand, finds its reuse time governed by the oxygen pick up that occurs during and in between build cycles. The detailed results have been presented.

  16. Experimental Study of Direct Laser Deposition of Ti-6Al-4V and Inconel 718 by Using Pulsed Parameters

    PubMed Central

    Shah, Kamran; Haq, Izhar Ul; Shah, Shaukat Ali; Khan, Farid Ullah; Khan, Sikander

    2014-01-01

    Laser direct metal deposition (LDMD) has developed from a prototyping to a single metal manufacturing tool. Its potential for creating multimaterial and functionally graded structures is now beginning to be explored. This work is a first part of a study in which a single layer of Inconel 718 is deposited on Ti-6Al-4V substrate. Single layer tracks were built at a range of powder mass flow rates using a coaxial nozzle and 1.5 kW diode laser operating in both continuous and pulsed beam modes. This part of the study focused on the experimental findings during the deposition of Inconel 718 powder on Ti-6Al-4V substrate. Scanning electron microscopy (SEM) and X-ray diffraction analysis were performed for characterization and phase identification. Residual stress measurement had been carried out to ascertain the effects of laser pulse parameters on the crack development during the deposition process. PMID:24592190

  17. Recyclability study on Inconel 718 and Ti-6Al-4V powders for use in electron beam melting

    DOE PAGES

    Nandwana, Peeyush; Peter, William H.; Lowe, Larry E.; Dehoff, Ryan R.; Medina, Francisco; Babu, Sudarsanam Suresh; Kirka, Michael M.

    2015-10-20

    In this study, powder bed based additive manufacturing technologies offer a big advantage in terms of reusability of the powders over multiple cycles that result in cost savings. However, currently there are no standards to determine the factors that govern the powder reuse times. This work presents the results from a recyclability study conducted on Inconel 718 and Ti-6Al-4V powders. It has been found that the Inconel 718 powders are chemically stable over a large number of cycles and their reuse time is limited by physical characteristics of powders such as flowability. Ti-6Al-4V, on the other hand, finds its reusemore » time governed by the oxygen pick up that occurs during and in between build cycles. The detailed results have been presented.« less

  18. Recyclability Study on Inconel 718 and Ti-6Al-4V Powders for Use in Electron Beam Melting

    NASA Astrophysics Data System (ADS)

    Nandwana, Peeyush; Peter, William H.; Dehoff, Ryan R.; Lowe, Larry E.; Kirka, Michael M.; Medina, Francisco; Babu, Sudarsanam S.

    2016-02-01

    Powder bed-based additive manufacturing technologies offer a big advantage in terms of reusability of the powders over multiple cycles that result in cost savings. However, currently there are no standards to determine the factors that govern the powder reuse times. This work presents the results from a recyclability study conducted on Inconel 718 and Ti-6Al-4V powders. It has been found that the Inconel 718 powders are chemically stable over a large number of cycles and their reuse time is limited by physical characteristics of powders such as flowability. Ti-6Al-4V, on the other hand, finds its reuse time governed by the oxygen pick up that occurs during and in between build cycles. The detailed results have been presented.

  19. Experimental study of direct laser deposition of Ti-6Al-4V and Inconel 718 by using pulsed parameters.

    PubMed

    Shah, Kamran; Izhar Ul Haq; Shah, Shaukat Ali; Khan, Farid Ullah; Khan, Muhammad Tahir; Khan, Sikander

    2014-01-01

    Laser direct metal deposition (LDMD) has developed from a prototyping to a single metal manufacturing tool. Its potential for creating multimaterial and functionally graded structures is now beginning to be explored. This work is a first part of a study in which a single layer of Inconel 718 is deposited on Ti-6Al-4V substrate. Single layer tracks were built at a range of powder mass flow rates using a coaxial nozzle and 1.5 kW diode laser operating in both continuous and pulsed beam modes. This part of the study focused on the experimental findings during the deposition of Inconel 718 powder on Ti-6Al-4V substrate. Scanning electron microscopy (SEM) and X-ray diffraction analysis were performed for characterization and phase identification. Residual stress measurement had been carried out to ascertain the effects of laser pulse parameters on the crack development during the deposition process.

  20. Determination of Constitutive Equation for Thermo-mechanical Processing of INCONEL 718 Through Double Multivariate Nonlinear Regression Analysis

    NASA Astrophysics Data System (ADS)

    Hussain, Mirza Zahid; Li, Fuguo; Wang, Jing; Yuan, Zhanwei; Li, Pan; Wu, Tao

    2015-07-01

    The present study comprises the determination of constitutive relationship for thermo-mechanical processing of INCONEL 718 through double multivariate nonlinear regression, a newly developed approach which not only considers the effect of strain, strain rate, and temperature on flow stress but also explains the interaction effect of these thermo-mechanical parameters on flow behavior of the alloy. Hot isothermal compression experiments were performed on Gleeble-3500 thermo-mechanical testing machine in the temperature range of 1153 to 1333 K within the strain rate range of 0.001 to 10 s-1. The deformation behavior of INCONEL 718 is analyzed and summarized by establishing the high temperature deformation constitutive equation. The calculated correlation coefficient ( R) and average absolute relative error ( AARE) underline the precision of proposed constitutive model.

  1. Verification of the stability lobes of Inconel 718 milling by recurrence plot applications and composite multiscale entropy analysis

    NASA Astrophysics Data System (ADS)

    Krzysztof, Kecik; Borowiec, Marek; Rafał, Rusinek

    2016-01-01

    Correctness verification of the stability lobe diagrams of milling process determined by commercial software CutPro 9 is the aim of this work. The analysis is performed for nickel superalloy Inconel 718 which is widely used in aviation industry. A methodology of stability analysis which bases on advanced nonlinear methods such as recurrence plot, recurrence quantifications analysis and composite multiscale entropy analysis are applied to the experimental data. Additionally, a new criterion for the determination of the unstable areas is proposed.

  2. Microstructural Changes in Inconel® 740 After Long-Term Aging in the Presence and Absence of Stress

    DOE PAGES

    Unocic, Kinga A.; Shingledecker, John Paul; Tortorelli, Peter F.

    2014-11-18

    The Ni-based alloy, Inconel® 740, is being extensively examined for use in advanced ultrasupercritical steam boilers because its precipitation-strengthened microstructure appears to offer the necessary creep strength under the high temperatures and pressures (up to 760°C and 35 MPa) needed for high efficiency power generation. However, because this application requires extremely long lifetimes under these conditions (up to 30 years), long-term microstructure stability is a major concern. In this study, results from microstructural analyses of Inconel 740 specimens aged at 700 and 750°C in the presence and absence of creep loading for times up to ~31,000 h are presented. Themore » primary focus was on the development of the eta η (Ni3Ti) phase and coarsening of coherent γ'-Ni3(Al,Ti) precipitates and its depletion near eta/matrix interfaces. Finally, however, despite these processes, Inconel 740 showed adequate long-term microstructural stability to assure adequate creep strength for the intended application.« less

  3. Selective laser melting additive manufactured Inconel 718 superalloy parts: High-temperature oxidation property and its mechanisms

    NASA Astrophysics Data System (ADS)

    Jia, Qingbo; Gu, Dongdong

    2014-10-01

    This work presented a comprehensive study of high-temperature oxidation behaviors and mechanisms of Selective laser melting (SLM) processed Inconel 718 superalloy parts using different methods including isothermal oxidation testing, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The experimental results revealed that the oxidation process of the tested parts processed at a lower volumetric laser energy density experienced the severe spallation. On reasonably increasing the applied volumetric laser energy density, the oxidation kinetics of the as-produced parts obeyed a parabolic law, exhibiting the significantly improved oxidation resistance performance. The constitutional phases within the oxidation film were identified and the corresponding formation mechanisms were elucidated in detail according to the thermodynamic principles. The cross-sectional morphologies of oxidized Inconel 718 parts indicated that the oxidation microstructure mainly consisted of an external oxidation layer and an internal oxidation zone. The oxidation process was controlled by the outward diffusion of oxide forming elements and inward penetration of oxygen, by which the interaction mechanisms between the microstructures and internal oxidation zones were clarified. On the basis of the experimental results and theoretical analyses, the physical oxidation mechanisms were accordingly established to illustrate the oxidation behaviors of SLM-processed Inconel 718 parts at elevated operative temperatures.

  4. Experimental and modeling results of creep fatigue life of Inconel 617 and Haynes 230 at 850 C

    SciTech Connect

    Chen, Xiang; Sokolov, Mikhail A; Sham, Sam; ERDMAN III, DONALD L; Busby, Jeremy T; Mo, Kun; Stubbins, James

    2013-01-01

    Creep fatigue testing of Ni-based superalloy Inconel 617 and Haynes 230 were conducted in the air at 850 C. Tests were performed with fully reversed axial strain control at a total strain range of 0.5%, 1.0% or 1.5% and hold time at maximum tensile strain for 3, 10 or 30 min. In addition, two creep fatigue life prediction methods, i.e. linear damage summation and frequency-modified tensile hysteresis energy modeling, were evaluated and compared with experimental results. Under all creep fatigue tests, Haynes 230 performed better than Inconel 617. Compared to the low cycle fatigue life, the cycles to failure for both materials decreased under creep fatigue test conditions. Longer hold time at maximum tensile strain would cause a further reduction in both material creep fatigue life. The linear damage summation could predict the creep fatigue life of Inconel 617 for limited test conditions, but considerably underestimated the creep fatigue life of Haynes 230. In contrast, frequency-modified tensile hysteresis energy modeling showed promising creep fatigue life prediction results for both materials.

  5. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, Mechanical Fatigue, Creep and Thermal Fatigue Effects

    NASA Technical Reports Server (NTRS)

    Bast, Callie Corinne Scheidt

    1994-01-01

    This thesis presents the on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes four effects that typically reduce lifetime strength: high temperature, mechanical fatigue, creep, and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model's empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for four variables, namely, high temperature, mechanical fatigue, creep, and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using the current version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of mechanical fatigue, creep, and thermal fatigue was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing a combination of mechanical fatigue and high temperature effects by model to the combination by experiment were conducted. Thus, for Inconel 718, the basic model assumption of independence between effects was evaluated. Results from this limited verification study strongly supported this assumption.

  6. Microstructural Changes in Inconel 740 After Long-Term Aging in the Presence and Absence of Stress

    NASA Astrophysics Data System (ADS)

    Unocic, K. A.; Shingledecker, J. P.; Tortorelli, P. F.

    2014-12-01

    The Ni-based alloy, Inconel® 740, is being extensively examined for use in advanced ultrasupercritical steam boilers because its precipitation-strengthened microstructure appears to offer the necessary creep strength under the high temperatures and pressures (up to 760°C and 35 MPa) needed for high efficiency power generation. However, because this application requires extremely long lifetimes under these conditions (up to 30 years), long-term microstructure stability is a major concern. In this paper, results from microstructural analyses of Inconel 740 specimens aged at 700 and 750°C in the presence and absence of creep loading for times up to ~31,000 h are presented. The primary focus was on the development of the eta η (Ni3Ti) phase and coarsening of coherent γ'-Ni3(Al,Ti) precipitates and its depletion near eta/matrix interfaces. However, despite these processes, Inconel 740 showed adequate long-term microstructural stability to assure adequate creep strength for the intended application.

  7. Macrotransport-solidification kinetics modeling of equiaxed dendritic growth: Part II. Computation problems and validation on INCONEL 718 superalloy castings

    NASA Astrophysics Data System (ADS)

    Nastac, L.; Stefanescu, D. M.

    1996-12-01

    In Part I of the article, a new analytical model that describes solidification of equiaxed dendrites was presented. In this part of the article, the model is used to simulate the solidification of INCONEL 718 superalloy castings. The model was incorporated into a commercial finite-element code, PROCAST. A special procedure called microlatent heat method (MLHM) was used for coupling between macroscopic heat flow and microscopic growth kinetics. A criterion for time-stepping selection in microscopic modeling has been derived in conjunction with MLHM. Reductions in computational (CPU) time up to 90 pct over the classic latent heat method were found by adopting this coupling. Validation of the model was performed against experimental data for an INCONEL 718 superalloy casting. In the present calculations, the model for globulitic dendrite was used. The evolution of fraction of solid calculated with the present model was compared with Scheil’s model and experiments. An important feature in solidification of INCONEL 718 is the detrimental Laves phase. Laves phase content is directly related to the intensity of microsegregation of niobium, which is very sensitive to the evolution of the fraction of solid. It was found that there is a critical cooling rate at which the amount of Laves phase is maximum. The critical cooling rate is not a function of material parameters (diffusivity, partition coefficient, etc.). It depends only on the grain size and solidification time. The predictions generated with the present model are shown to agree very well with experiments.

  8. Effect of cold rolling and first precipitates on the coarsening behavior of γ″-phases in Inconel 718 alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Jing-ling; Guo, Qian-ying; Liu, Yong-chang; Li, Chong; Yu, Li-ming; Li, Hui-jun

    2016-09-01

    The coarsening behaviors of γ″-phase particles in Inconel 718 alloy aged at 750, 800, and 850°C were investigated by scanning electron microscopy (SEM). Detailed observations and quantitative measurements were conducted to characterize the coarsening behavior of the γ?-phase under various aging conditions. The experimental results indicate that the existence of the δ-phase retards the formation and coarsening of the γ″-phase, without influencing its final particle size or amount. Moreover, when cold rolled with a reduction of 50%, the dimensions of the γ″ particles in Inconel 718 alloy decrease with increasing aging time. Furthermore, the coarsening behavior of the γ″-phase in the Inconel 718 alloy after a normal aging treatment (sample A) and that of the primary δ-phase (sample B) follow the Lifshitz-Slyozov-Wagner (LSW) diffusion-controlled growth theory; the thus-obtained activation energies for the γ″-phase are 292 kJ·mol-1 and 302 kJ·mol-1, respectively.

  9. Analytical methods to characterize heterogeneous raw material for thermal spray process: cored wire Inconel 625

    NASA Astrophysics Data System (ADS)

    Lindner, T.; Bonebeau, S.; Drehmann, R.; Grund, T.; Pawlowski, L.; Lampke, T.

    2016-03-01

    In wire arc spraying, the raw material needs to exhibit sufficient formability and ductility in order to be processed. By using an electrically conductive, metallic sheath, it is also possible to handle non-conductive and/or brittle materials such as ceramics. In comparison to massive wire, a cored wire has a heterogeneous material distribution. Due to this fact and the complex thermodynamic processes during wire arc spraying, it is very difficult to predict the resulting chemical composition in the coating with sufficient accuracy. An Inconel 625 cored wire was used to investigate this issue. In a comparative study, the analytical results of the raw material were compared to arc sprayed coatings and droplets, which were remelted in an arc furnace under argon atmosphere. Energy-dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF) analysis were used to determine the chemical composition. The phase determination was performed by X-ray diffraction (XRD). The results were related to the manufacturer specifications and evaluated in respect to differences in the chemical composition. The comparison between the feedstock powder, the remelted droplets and the thermally sprayed coatings allows to evaluate the influence of the processing methods on the resulting chemical and phase composition.

  10. Effect of electric discharge machining on the fatigue life of Inconel 718

    NASA Technical Reports Server (NTRS)

    Jeelani, S.; Collins, M. R.

    1988-01-01

    The effect of electric discharge machining on the fatigue life of Inconel 718 alloy at room temperature was investigated. Data were generated in the uniaxial tension fatigue mode at ambient temperature using flat 3.175 mm thick specimens. The specimens were machined on a wire-cut electric discharge machine at cutting speeds ranging from 0.5 to 2 mm per minute. The specimens were fatigued at a selected stress, and the resulting fatigue lives compared with that of the virgin material. The surfaces of the fatigued specimens were examined under optical and scanning electron microscopes, and the roughness of the surfaces was measured using a standard profilometer. From the results of the investigation, it was concluded that the fatigue life of the specimens machined using EDM decreased slightly as compared with that of the virgin material, but remained unchanged as the cutting speed was changed. The results are explained using data produced employing microhardness measurements, profilometry, and optical and scanning microscopy.

  11. Structure and Properties of the Aluminide Coatings on the Inconel 625 Superalloy

    NASA Astrophysics Data System (ADS)

    Adamiak, Stanisław; Bochnowski, Wojciech; Dziedzic, Andrzej; Filip, Ryszard; Szeregij, Eugeniusz

    2016-01-01

    The research samples used in this study were based on the Inconel 625 alloy; the examined samples were coated with aluminide films deposited in a low-activity chemical vapor deposition (CVD) process. The samples' microstructure was investigated with optical and electron microscopy and energy dispersive X-ray spectroscopy analysis. Hardness measurements were performed using Vickers and Berkovich test methods. The adhesion of the aluminide coating was determined by fractography. It was shown that the fracture mechanism was different for the respective zones of the aluminide coating and the substrate material. The outer zone of the aluminide coating is characterized by an intercrystalline fracture, with a small contribution of transcrystalline fracture within individual grains (large crystallites in the bottom of the zone, composed of smaller crystallites, also show an intercrystalline fracture). The substrate material exhibited a ductile intercrystalline fracture. Based on this investigation, an increase of the microhardness of the material occurring at loads below 0.2 N was observed. When determining microhardness of aluminide coating it is necessary to take into account the optimal choice of the indentation tip.

  12. Intergranular fracture in irradiated Inconel X-750 containing very high concentrations of helium and hydrogen

    SciTech Connect

    Judge, Colin D.; Gauquelin, Nicolas; Walters, Lori; Wright, Mike; Cole, James I.; Madden, James; Botton, Gianluigi A.; Griffiths, Malcolm

    2015-02-01

    In recent years, it has been determined that Inconel X-750 CANDU spacers have lost strength and material ductility following irradiation in reactor. The irradiated fracture behaviour of ex-service material was also found to be entirely intergranular. The heavily thermalized flux spectrum in a CANDU reactor results in transmutation of 58Ni to 59Ni. The 59Ni itself has unusually high thermal neutron reaction cross-sections of the type: (n, γ), (n, p), and (n,α). The latter two reactions, in particular, contribute to a significant enhancement of the atomic displacements in addition to creating high concentrations of hydrogen and helium within the material. Metallographic examinations by transmission electron microscopy (TEM) have confirmed the presence of helium bubbles in the matrix and aligned along grain boundaries and matrix-precipitate interfaces. He bubble size and density are found to be highly dependent on the irradiation temperature and material microstructure; the bubbles are larger within grain boundary precipitates. TEM specimens extracted from fracture surfaces and crack tips give direct evidence linking crack propagation with grain boundary He bubbles.

  13. Characterization of the atomic emission in inconel 718 alloy metal vapor arcs

    SciTech Connect

    Williamson, R.L.; Peebles, H.C.; Bertram, L.A.; Hareland, W.A.; Zanner, F.J.

    1986-01-01

    Visible and uv emission spectroscopy was used to identify and study various atomic species in the plasma of a vacuum arc furnace during a remelt of Inconel 718. The studies were carried out at a base pressure of 10 mtorr, and with the furnace backfilled with CO to a total pressure of 100 mtorr. Various emitting species were identified, and the internal energy distributions of a number of these species were mapped out using Boltzmann plots. Internal temperatures of 6000 to 7000/sup 0/K were measured for the neutral atomic species in the low pressure arc, while a value of 11,600/sup 0/K was obtained for the ion temperature. In addition, the density of the highly volatile element Mn in the interelectrode region was found to be greatly enhanced compared to its relative abundance in the bulk alloy, indicating the importance of vaporization in determining the atomic composition of the arc plasma. Increasing the furnace pressure resulted in an increase in the temperature of the neutral species of 1500 to 4000/sup 0/K, and an apparent suppression of the Mn vaporization rate.

  14. Experimental Investigation and Optimization of Response Variables in WEDM of Inconel - 718

    NASA Astrophysics Data System (ADS)

    Karidkar, S. S.; Dabade, U. A.

    2016-02-01

    Effective utilisation of Wire Electrical Discharge Machining (WEDM) technology is challenge for modern manufacturing industries. Day by day new materials with high strengths and capabilities are being developed to fulfil the customers need. Inconel - 718 is similar kind of material which is extensively used in aerospace applications, such as gas turbine, rocket motors, and spacecraft as well as in nuclear reactors and pumps etc. This paper deals with the experimental investigation of optimal machining parameters in WEDM for Surface Roughness, Kerf Width and Dimensional Deviation using DoE such as Taguchi methodology, L9 orthogonal array. By keeping peak current constant at 70 A, the effect of other process parameters on above response variables were analysed. Obtained experimental results were statistically analysed using Minitab-16 software. Analysis of Variance (ANOVA) shows pulse on time as the most influential parameter followed by wire tension whereas spark gap set voltage is observed to be non-influencing parameter. Multi-objective optimization technique, Grey Relational Analysis (GRA), shows optimal machining parameters such as pulse on time 108 Machine unit, spark gap set voltage 50 V and wire tension 12 gm for optimal response variables considered for the experimental analysis.

  15. Reactivity Studies of Inconel 625 with Sodium, and Lunar Regolith Stimulant

    NASA Technical Reports Server (NTRS)

    Gillies, Donald; Salvail, Pat; Reid, Bob; Colebaugh, James; Easterling, Greg

    2008-01-01

    In the event of the need for nuclear power in exploration, high flux heat pipes will be needed for heat transfer from space nuclear reactors to various energy conversion devices, and to safely dissipate excess heat. Successful habitation will necessitate continuous operation of alkali metal filled heat pipes for 10 or-more years in a hostile environment with little maintenance. They must be chemical and creep resistant in the high vacuum of space (lunar), and they must operate reliably in low gravity conditions with intermittent high radiation fluxes. One candidate material for the heat pipe shell, namely Inconel 625, has been tested to determine its compatibility with liquid sodium. Any reactivity could manifest itself as a problem over the long time periods anticipated. In addition, possible reactions with the lunar regolith will take place, as will evaporation of selected elements at the external surfaces of the heat pipes, and so there is a need for extensive long-term testing under simulated lunar conditions.

  16. Microstructure of AI2O3 fiber-reinforced superalloy (INCONEL 718) composites

    NASA Astrophysics Data System (ADS)

    Nourbakhsh, S.; Sahin, O.; Rhee, W. H.; Margolin, H.

    1996-02-01

    Composites of INCONEL 718 alloy reinforced with either single-crystal (SAPHIKON) or polycrys-talline (Du Pont's FP) A12O3 fiber were fabricated by pressure casting. Optical and transmission electron microscopy were used to characterize the microstructure of the composites and to determine the nature of the fiber/matrix reaction. The widely dispersed fibers in the SAPHIKON-fiber-reinforced composite had no influence on the solidification of the matrix. Six phases, γ-Ni3Al, γ'-Ni3Nb, δ-Ni3Nb, TiC, NbC, and Laves, were present in the matrix of the composite. The last three phases were formed during solidification and the others precipitated during subsequent cooling. The high density of fibers in the FP-fiber-reinforced composite led to a more uniform microstructure within the matrix. Only three phases, γ″-Ni3Nb, NbC, and Laves, were identified. Diffusion of Ti into the A12O3 fiber resulted in preferential grain growth in the FP fiber in areas adjacent to the fiber/matrix interface. The fiber/matrix bond strength in shear in the SAPHIKON-fiber-reinforced composite was in excess of 150 MPa.

  17. Investigation of microstructure in additive manufactured Inconel 625 by spatially resolved neutron transmission spectroscopy

    DOE PAGES

    Tremsin, Anton S.; Gao, Yan; Dial, Laura C.; Grazzi, Francesco; Shinohara, Takenao

    2016-07-08

    Non-destructive testing techniques based on neutron imaging and diffraction can provide information on the internal structure of relatively thick metal samples (up to several cm), which are opaque to other conventional non-destructive methods. Spatially resolved neutron transmission spectroscopy is an extension of traditional neutron radiography, where multiple images are acquired simultaneously, each corresponding to a narrow range of energy. The analysis of transmission spectra enables studies of bulk microstructures at the spatial resolution comparable to the detector pixel. In this study we demonstrate the possibility of imaging (with ~100 μm resolution) distribution of some microstructure properties, such as residual strain,more » texture, voids and impurities in Inconel 625 samples manufactured with an additive manufacturing method called direct metal laser melting (DMLM). Although this imaging technique can be implemented only in a few large-scale facilities, it can be a valuable tool for optimization of additive manufacturing techniques and materials and for correlating bulk microstructure properties to manufacturing process parameters. Additionally, the experimental strain distribution can help validate finite element models which many industries use to predict the residual stress distributions in additive manufactured components.« less

  18. TEM observation of the heat-affected zone in electron beam welded superalloy Inconel 713C

    SciTech Connect

    Lachowicz, Maciej Dudzinski, Wlodzimierz; Podrez-Radziszewska, Marzena

    2008-05-15

    The paper presents results of microstructural observations and phase analysis of electron-beam-welded fusion zones in superalloy Inconel 713C using transmission electron microscopy. In the fusion zone, a 90% fraction of fine-grained {gamma}' precipitates was found, with sizes up to 30 nm. No dislocations were observed in the precipitates or at the {gamma}-{gamma}' interface. Primary, undissolved inclusions of {gamma}' were found in the heat-affected zone (HAZ). In the HAZ, a very high concentration of dislocations was found at the {gamma}-{gamma}' boundaries, as well as inside the {gamma}' particles and in the {gamma} solid solution. The increased dislocation density indicates loss of coherence of that phase and the creation of a semi-coherent boundary, and is related to dissolution of the particles and intensified diffusion through the interphase {gamma}-{gamma}' boundary. The lattice misfit coefficient {delta}a/a between the {gamma}' particles and {gamma} solution in the HAZ indicates negative values from - 0.20% to - 0.06%. The presence of semi-coherent boundaries and the negative lattice misfit coefficient leads to dislocation locking and can result in cracking in the HAZ.

  19. Effect of titanium carbonitride (Ti(C,N)) decomposition on failure mechanisms in Inconel 617 alloy.

    PubMed

    Krishna, Ram; Hainsworth, Sarah V; Gill, Simon P A; Atkinson, Helen V

    2015-05-01

    Titanium Carbonitride (Ti(C,N)) decomposition in Inconel 617 alloy creep-exposed at 650°C for 574 hours is reported using analytical electron microscopy techniques. Cr-enriched M23C6-type carbides enveloped in fine gamma prime particles thought to be precipitated from the decomposition reaction are observed in the alloy. The morphology of the M23C6 carbides is irregular and blocky and the particle size up to 5 μm, whereas the morphology of gamma prime particles is mostly spherical and up to 30 nm in size. Intergranular carbides are mostly secondary precipitates of the M23Cc type (M predominantly Cr) and these respond to solution heat treatment and precipitate on the grain boundaries as a result of ageing. The ability of intragranular MX to decompose is sensitive to the N content, high N resists decomposition. Decomposed intragranular MX provides an excess source of C which can react locally with Cr to form heat treatable intragranular fine Cr23C6 precipitates. M6C can segregate in interdendritic locations during melting which may be the reason for high content of Mo in M23C6. These precipitates are generally very small and contribute to an additional hardening effect and are the reason for the onset of voiding and cracking along the grain boundaries that ultimately lead to a reduced creep rupture life.

  20. Characterization of the Microstructures and the Cryogenic Mechanical Properties of Electron Beam Welded Inconel 718

    NASA Astrophysics Data System (ADS)

    Kwon, Soon Il; Bae, Sang Hyun; Do, Jeong Hyeon; Jo, Chang Yong; Hong, Hyun Uk

    2016-02-01

    The microstructures and the cryogenic mechanical properties of electron beam (EB) welds between cast and forged Inconel 718 superalloys with a thickness of 10 mm were investigated in comparison with gas tungsten arc (GTA) welds. EB welding with a heat input lower than 250 J/mm caused the formation of liquation microfissuring in the cast-side heat-affected-zone (HAZ) of the EB welds. HAZ liquation microfissuring appeared to be associated with the constitutional liquation of primary NbC carbides at the grain boundaries. Compared with the GTA welding process, the EB welding produced welds with superior microstructure, exhibiting fine dendritic structure associated with the reduction in size and fraction of the Laves phase due to the rapid cooling rate. This result was responsible for the superior mechanical properties of the EB welds at 77 K (-196 °C). Laves particles in both welds were found to provide the preferential site for the crack initiation and propagation, leading to a significant decrease in the Charpy impact toughness at 77 K (-196 °C). Crack initiation and propagation induced by Charpy impact testing were discussed in terms of the dendrite arm spacing, the Laves size and the dislocation structure ahead of the crack arisen from the fractured Laves phase in the two welds.

  1. High-Cycle Fatigue Properties at Cryogenic Temperatures in INCONEL 718

    SciTech Connect

    Ono, Y.; Yuri, T.; Sumiyoshi, H.; Takeuchi, E.; Ogata, T.; Matsuoka, S.

    2006-03-31

    High-cycle fatigue properties at 4 K, 20 K, 77 K and 293 K were investigated in forged-INCONEL 718 nickel-based superalloy with a mean gamma ({gamma}) grain size of 25 {mu}m. In the present material, plate-like delta phase precipitated at {gamma} grain boundaries and niobium (Nb)-enriched MC type carbides precipitated coarsely throughout the specimens. The 0.2% proof stress and the tensile strength of this alloy increased with decreasing temperature, without decreasing elongation or reduction of area. High-cycle fatigue strengths also increased with decreasing temperature although the fatigue limit at each temperature didn't appear even around 107 cycles. Fatigue cracks initiated near the specimen surface and formed faceted structures around crack initiation sites. Fatigue cracks predominantly initiated from coarse Nb-enriched carbides and faceted structures mainly corresponded to these carbides. In lower stress amplitude tests, however, facets were formed through transgranular crack initiation and growth. These kinds of distinctive crack initiation behavior seem to lower the high-cycle fatigue strength below room temperature in the present material.

  2. Effect of Cooling Rate on the Microstructure of Laser-Remelted INCONEL 718 Coating

    NASA Astrophysics Data System (ADS)

    Zhang, Yaocheng; Li, Zhuguo; Nie, Pulin; Wu, Yixiong

    2013-12-01

    The rapid cooling rate was achieved during laser remelting with high scanning speed. The microstructure and precipitations in the INCONEL 718 remelted layer were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), and solid phase microextraction (SPME). The phase transition temperatures were carried out by differential thermal analysis (DTA). The results showed that columnar-dendritic and equiaxial structures appeared in different regions of the remelted layer. The dendritic spacing of the columnar dendrite and equiaxed grain size decreased with increasing scanning speed. The precipitations in the remelted layer consisted of Laves, granular phase, and a small quantity of quadrangular nitride (Ti, Nb)N. The granular phase Nb(Al, Ti) was precipitated at about 1272 K (999 °C) with the spontaneous decomposition of the supersaturation Laves during the cooling stage, and the small-size granule became coarsened to 0.2 to 0.9 μm during the cooling stage. The noncoherent relationship existed between the granular phase and austenite, and the coarsening of granule was related to the cube root of the diffusion coefficient, interfacial energy, and diffusion time. The microhardness of the remelted layer was increased by increasing the cooling rate due to the Nb atomic solid solution strengthening caused by the distorted elastic stress field and the short-range internal stress.

  3. High-Cycle Fatigue Properties at Cryogenic Temperatures in INCONEL 718

    NASA Astrophysics Data System (ADS)

    Ono, Y.; Yuri, T.; Sumiyoshi, H.; Takeuchi, E.; Matsuoka, S.; Ogata, T.

    2006-03-01

    High-cycle fatigue properties at 4 K, 20 K, 77 K and 293 K were investigated in forged-INCONEL 718 nickel-based superalloy with a mean gamma (γ) grain size of 25 μm. In the present material, plate-like delta phase precipitated at γ grain boundaries and niobium (Nb)-enriched MC type carbides precipitated coarsely throughout the specimens. The 0.2% proof stress and the tensile strength of this alloy increased with decreasing temperature, without decreasing elongation or reduction of area. High-cycle fatigue strengths also increased with decreasing temperature although the fatigue limit at each temperature didn't appear even around 107 cycles. Fatigue cracks initiated near the specimen surface and formed faceted structures around crack initiation sites. Fatigue cracks predominantly initiated from coarse Nb-enriched carbides and faceted structures mainly corresponded to these carbides. In lower stress amplitude tests, however, facets were formed through transgranular crack initiation and growth. These kinds of distinctive crack initiation behavior seem to lower the high-cycle fatigue strength below room temperature in the present material.

  4. Mechanical characterization of an additively manufactured Inconel 718 theta-shaped specimen

    SciTech Connect

    Cakmak, Ercan; Watkins, Thomas R.; Bunn, Jeffrey R.; Cornwell, Paris A.; Wang, Yanli; Dehoff, Ryan R.; Babu, Sudarsanam Suresh; Sochalski-Kolbus, Lindsay M.

    2015-11-20

    Two sets of “theta”-shaped specimens were additively manufactured with Inconel 718 powders using an electron beam melting technique with two distinct scan strategies. Light optical microscopy, mechanical testing coupled with a digital image correlation (DIC) technique, finite element modeling, and neutron diffraction with in situ loading characterizations were conducted. The cross-members of the specimens were the focus. Light optical micrographs revealed that different microstructures were formed with different scan strategies. Ex situ mechanical testing revealed each build to be stable under load until ductility was observed on the cross-members before failure. The elastic moduli were determined by forming a correlation between the elastic tensile stresses determined from FEM, and the elastic strains obtained from DIC. The lattice strains were mapped with neutron diffraction during in situ elastic loading; and a good correlation between the average axial lattice strains on the cross-member and those determined from the DIC analysis was found. Lastly, the spatially resolved stresses in the elastic deformation regime are derived from the lattice strains and increased with applied load, showing a consistent distribution along the cross-member.

  5. Mechanical characterization of an additively manufactured Inconel 718 theta-shaped specimen

    DOE PAGES

    Cakmak, Ercan; Watkins, Thomas R.; Bunn, Jeffrey R.; Cornwell, Paris A.; Wang, Yanli; Dehoff, Ryan R.; Babu, Sudarsanam Suresh; Sochalski-Kolbus, Lindsay M.

    2015-11-20

    Two sets of “theta”-shaped specimens were additively manufactured with Inconel 718 powders using an electron beam melting technique with two distinct scan strategies. Light optical microscopy, mechanical testing coupled with a digital image correlation (DIC) technique, finite element modeling, and neutron diffraction with in situ loading characterizations were conducted. The cross-members of the specimens were the focus. Light optical micrographs revealed that different microstructures were formed with different scan strategies. Ex situ mechanical testing revealed each build to be stable under load until ductility was observed on the cross-members before failure. The elastic moduli were determined by forming a correlationmore » between the elastic tensile stresses determined from FEM, and the elastic strains obtained from DIC. The lattice strains were mapped with neutron diffraction during in situ elastic loading; and a good correlation between the average axial lattice strains on the cross-member and those determined from the DIC analysis was found. Lastly, the spatially resolved stresses in the elastic deformation regime are derived from the lattice strains and increased with applied load, showing a consistent distribution along the cross-member.« less

  6. CO2 laser cut quality of Inconel 718 nickel - based superalloy

    NASA Astrophysics Data System (ADS)

    Hasçalık, Ahmet; Ay, Mustafa

    2013-06-01

    This paper experimentally investigates the cut quality of laser cutting for the age hardened Inconel 718 nickel based super alloy, with the use of a continuous CO2 4.0 kW laser cutting system. The quality of the cut has been monitored by measuring the kerf taper ratio, the recast layer thickness and the surface roughness of the cut specimens. The effects of processing parameters, such as the laser power, the cutting speed and the assisting gas pressure were evaluated. Scanning electron microscopy (SEM), Energy Dispersive Spectrography (EDS), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and Knoop hardness tests are carried out to examine the cutting defects, the kerf size variation and formed carbide on the surfaces. A statistical analysis of the results has been performed in order for the effect of each parameter on the cutting quality to be determined. The regression analysis has been used for the development of empirical models able to describe the effect of the process parameters on the quality of laser cutting.

  7. Effect of Grain Size Distribution on Processing Maps for Isothermal Compression of Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Wang, Jianguo; Liu, Dong; Hu, Yang; Yang, Yanhui; Zhu, Xinglin

    2016-02-01

    Cylindrical specimens of Inconel 718 alloys with three types of grain size distribution were used in the compression tests and processing maps were developed in 940-1040 °C and 0.001-10 s-1. The equiaxed fine grain is more effective on the dynamic softening behavior. For partial recrystallized microstructure, the peak efficiency of power dissipation occurs at the strain rate of 0.001 s-1, and the temperature range of 1000-1020 °C. In order to obtain homogeneous microstructure with fine grains, the partial recrystallized microstructure should be deformed at the low temperature and slow strain rates. The area fraction of instability domains decreases with strain increasing. The peak efficiency of power dissipation increases with average grain size decreasing. The efficiency of power dissipation will be stimulated by the precipitation of δ phase at slow strain rate of 0.001-0.01 s-1, and the initial deformed substructure at the strain rate of 0.1-1 s-1. Equiaxed fine grain is the optimum state for forging process and dynamic recrystallization. The grain size distribution has slight influence on the microstructure evolution at high temperatures.

  8. Carbide and nitride precipitation during laser cladding of Inconel 718 alloy coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Yaocheng; Li, Zhuguo; Nie, Pulin; Wu, Yixiong

    2013-11-01

    The microstructure of the laser clad Inconel 718 alloy coating was observed by scanning electron microscope (SEM). The chemical composition of precipitation phases was investigated by energy dispersive spectrometer (EDS) and solid phase microextraction (SPME). The crystal structure and lattice constants of precipitation are determined by transmission electron microscope (TEM). Vickers hardness of the coatings and the nanohardness of the interstitial phases were measured. The insular carbide (MC) and the tetragonal nitride (MN) with face-centered cubic (FCC) structure are rich in Ti and Nb but depleted in Ni, Fe and Cr due to the interdiffusion and redistribution of alloying elements between MC and MN and supersaturated matrix. MC and MN were precipitated in the forms of (Nb0.12Ti0.88)C1.5 and (Nb0.88Ti0.12)N1.5, and the Gibbs free energies of formation can be expressed as Δ G [ (Nb0.12Ti0.88)C1.5 ] 0 = - 122.654 - 3.1332 T (kJ /mol) and Δ G [ (Nb0.88Ti0.12)N1.5 ] 0 = - 157.814 - 3.0251 T (kJ /mol). The nanohardness and Young's modulus of the MC and MN were much higher than the matrix, and the plastic deformation energy of interstitial phases was lower than the matrix. The precipitation of MC and MN is beneficial to the mechanical properties of coating.

  9. Microhardness and microstructure evolution of TiB2 reinforced Inconel 625/TiB2 composite produced by selective laser melting

    NASA Astrophysics Data System (ADS)

    Zhang, Baicheng; Bi, Guijun; Nai, Sharon; Sun, Chen-nan; Wei, Jun

    2016-06-01

    In this study, micron-size TiB2 particles were utilized to reinforce Inconel 625 produced by selective laser melting. Exceptional microhardness 600-700 HV0.3 of the composite was obtained. In further investigation, the microstructure and mechanical properties of Inconel 625/TiB2 composite can be significantly influenced by addition of TiB2 particles during SLM. It was found that the long directional columnar grains observed from SLM-processed Inconel 625 were totally changed to fine dendritic matrix due to the addition of TiB2 particles. Moreover, with laser energy density (LED) of 1200 J/m, a Ti, Mo rich interface around TiB2 particles with fine thickness can be observed by FESEM and EDS. The microstructure evolution can be determined by different laser energy density (LED): under 1200 J/m, γ phase in dendrite grains; under 600 J/m, γ phase in combination of dendritic and acicular grains; under 400 J/m, γ phase acicular grains. Under optimized LED 1200 J/m, the dynamic nanohardness (8.62 GPa) and elastic modulus (167 GPa) of SLM-processed Inconel 625/TiB2 composite are higher compared with those of SLM-processed Inconel 625 (3.97 GPa and 135 GPa, respectively).

  10. Investigation of the effect of process parameters on the formation and characteristics of recast layer in wire-EDM of Inconel 718

    SciTech Connect

    Newton, Thomas R; Melkote, Shreyes N; Watkins, Thomas R; Trejo, Rosa M; Riester, Laura

    2009-01-01

    Inconel 718 is a high nickel content superalloy possessing high strength at elevated temperatures and resistance to oxidation and corrosion. The non-traditional manufacturing process of wire-electrical discharge machining (EDM) possesses many advantages over traditional machining during the manufacture of Inconel 718 parts. However, certain detrimental effects are also present and are due in large part to the formation of the recast layer. An experimental investigation was conducted to determine the main EDM parameters which contribute to recast layer formation in Inconel 718. It was found that average recast layer thickness increased primarily with energy per spark, peak discharge current, and current pulse duration. Over the range of parameters tested, the recast layer was observed to be between 5 and 9 {micro}m in average thickness, although highly variable in nature. The recast material was found to possess in-plane tensile residual stresses, as well as lower hardness and elastic modulus than the bulk material.

  11. Liquid Oxygen Rotating Friction Ignition Testing of Aluminum and Titanium with Monel and Inconel for Rocket Engine Propulsion System Contamination Investigation

    NASA Technical Reports Server (NTRS)

    Peralta, S.; Rosales, Keisa R.; Stoltzfus, Joel M.

    2009-01-01

    Metallic contaminant was found in the liquid oxygen (LOX) pre-valve screen of the shuttle main engine propulsion system on two orbiter vehicles. To investigate the potential for an ignition, NASA Johnson Space Center White Sands Test Facility performed (modified) rotating friction ignition testing in LOX. This testing simulated a contaminant particle in the low-pressure oxygen turbo pump (LPOTP) and the high-pressure oxygen turbo pump (HPOTP) of the shuttle main propulsion system. Monel(R) K-500 and Inconel(R) 718 samples represented the LPOTP and HPOTP materials. Aluminum foil tape and titanium foil represented the contaminant particles. In both the Monel(R) and Inconel(R) material configurations, the aluminum foil tape samples did not ignite after 30 s of rubbing. In contrast, all of the titanium foil samples ignited regardless of the rubbing duration or material configuration. However, the titanium foil ignitions did not propagate to the Monel and Inconel materials.

  12. Neutron Imaging for Selective Laser Melting Inconel Hardware with Internal Passages

    NASA Technical Reports Server (NTRS)

    Tramel, Terri L.; Norwood, Joseph K.; Bilheux, Hassina

    2014-01-01

    Additive Manufacturing is showing great promise for the development of new innovative designs and large potential life cycle cost reduction for the Aerospace Industry. However, more development work is required to move this technology into space flight hardware production. With selective laser melting (SLM), hardware that once consisted of multiple, carefully machined and inspected pieces, joined together can be made in one part. However standard inspection techniques cannot be used to verify that the internal passages are within dimensional tolerances or surface finish requirements. NASA/MSFC traveled to Oak Ridge National Lab's (ORNL) Spallation Neutron Source to perform some non-destructive, proof of concept imaging measurements to assess the capabilities to understand internal dimensional tolerances and internal passages surface roughness. This presentation will describe 1) the goals of this proof of concept testing, 2) the lessons learned when designing and building these Inconel 718 test specimens to minimize beam time, 3) the neutron imaging test setup and test procedure to get the images, 4) the initial results in images, volume and a video, 4) the assessment of using this imaging technique to gather real data for designing internal flow passages in SLM manufacturing aerospace hardware, and lastly 5) how proper cleaning of the internal passages is critically important. In summary, the initial results are very promising and continued development of a technique to assist in SLM development for aerospace components is desired by both NASA and ORNL. A plan forward that benefits both ORNL and NASA will also be presented, based on the promising initial results. The initial images and volume reconstruction showed that clean, clear images of the internal passages geometry are obtainable. These clear images of the internal passages of simple geometries will be compared to the build model to determine any differences. One surprising result was that a new cleaning

  13. Parametric modeling and optimization of laser scanning parameters during laser assisted machining of Inconel 718

    NASA Astrophysics Data System (ADS)

    Venkatesan, K.; Ramanujam, R.; Kuppan, P.

    2016-04-01

    This paper presents a parametric effect, microstructure, micro-hardness and optimization of laser scanning parameters (LSP) on heating experiments during laser assisted machining of Inconel 718 alloy. The laser source used for experiments is a continuous wave Nd:YAG laser with maximum power of 2 kW. The experimental parameters in the present study are cutting speed in the range of 50-100 m/min, feed rate of 0.05-0.1 mm/rev, laser power of 1.25-1.75 kW and approach angle of 60-90°of laser beam axis to tool. The plan of experiments are based on central composite rotatable design L31 (43) orthogonal array. The surface temperature is measured via on-line measurement using infrared pyrometer. Parametric significance on surface temperature is analysed using response surface methodology (RSM), analysis of variance (ANOVA) and 3D surface graphs. The structural change of the material surface is observed using optical microscope and quantitative measurement of heat affected depth that are analysed by Vicker's hardness test. The results indicate that the laser power and approach angle are the most significant parameters to affect the surface temperature. The optimum ranges of laser power and approach angle was identified as 1.25-1.5 kW and 60-65° using overlaid contour plot. The developed second order regression model is found to be in good agreement with experimental values with R2 values of 0.96 and 0.94 respectively for surface temperature and heat affected depth.

  14. Identifying and Understanding Environment-Induced Crack propagation Behavior in Ni-based Superalloy INCONEL 617

    SciTech Connect

    Ma, Longzhou

    2012-11-30

    The nickel-based superalloy INCONEL 617 is a candidate material for heat exchanger applications in the next-generation nuclear plant (NGNP) system. This project will study the crack propagation process of alloy 617 at temperatures of 650°C-950°C in air under static/cyclic loading conditions. The goal is to identify the environmental and mechanical damage components and to understand in-depth the failure mechanism. Researchers will measure the fatigue crack propagation (FCP) rate (da/dn) under cyclic and hold-time fatigue conditions, and sustained crack growth rates (da/dt) at elevated temperatures. The independent FCP process will be identified and the rate-controlled sustained loading crack process will be correlated with the thermal activation equation to estimate the oxygen thermal activation energy. The FCP-dependent model indicates that if the sustained loading crack growth rate, da/dt, can be correlated with the FCP rate, da/dn, at the full time dependent stage, researchers can confirm stress-accelerated grain-boundary oxygen embrittlement (SAGBOE) as a predominate effect. Following the crack propagation tests, the research team will examine the fracture surface of materials in various cracking stages using a scanning electron microscope (SEM) and an optical microscope. In particular, the microstructure of the crack tip region will be analyzed in depth using high resolution transmission electron microscopy (TEM) and electron energy loss spectrum (EELS) mapping techniques to identify oxygen penetration along the grain boundary and to examine the diffused oxygen distribution profile around the crack tip. The cracked sample will be prepared by focused ion beam nanofabrication technology, allowing researchers to accurately fabricate the TEM samples from the crack tip while minimizing artifacts. Researchers will use these microscopic and spectroscopic results to interpret the crack propagation process, as well as distinguish and understand the environment or

  15. Liquid Metal Pool Behavior during the Vacuum Arc Remelting of INCONEL 718

    NASA Astrophysics Data System (ADS)

    Shevchenko, D. M.; Ward, R. M.

    2009-06-01

    Non-steady-state ensemble arc behavior has been observed during the Vacuum Arc Remelting (VAR) of 508-mm-diameter ingots of INCONEL 718. The liquid metal flow in the melt pool of a 508-mm ingot during VAR has been simulated under two alternative sets of conditions: (1) a steady-state axisymmetrical arc distribution, as has been typically used in modeling work previously; and (b) a transient asymmetrical arc distribution. Due to the computational requirements, neither mass flux nor solidification were modeled; instead, the pool shape was fixed from measurements from a 508-mm-diameter ingot, and a constant pool wall temperature of 1609 K was used. The transient simulation assumed a localized Gaussian arc whose effective center was located at a distance of 0.1 m from the ingot centerline; this simulation rotated clockwise around the centerline with a period of 36 seconds. The steady-state model was simulated with axisymmetrical distributions of current and power input to the pool top surface calculated by time averaging the transient current and power inputs. The standard k- ɛ solver of ANSYS CFX 5.6 software was used for both simulations. The transient model results suggest that 5 seconds of asymmetrical arc behavior is enough to change the pool from steady state to transient and that, after 30 seconds, the flow is almost fully developed (at least to the accuracy of the model) and dominated by the Lorentz force. Aspects of the model results agree with key features of the melt pool observed during VAR.

  16. Compatibility of aluminide-coated Hastelloy x and Inconel 617 in a simulated gas-cooled reactor environment

    SciTech Connect

    Chin, J.; Johnson, W. R.; Chen, K.

    1982-03-01

    Commercially prepared aluminide coatings on Hastelloy X and Inconel 617 substrates were exposed to controlled-impurity helium at 850/sup 0/ and 950/sup 0/C for 3000 h. Optical and scanning electron (SEM) microscopy, electron microprobe profiles, and SEM X-ray mapping were used to evaluate and compare exposed and unexposed control samples. Four coatings were evaluated: aluminide, aluminide with platinum, aluminide with chromium, and aluminide with rhodium. With extended time at elevated temperature, nickel diffused into the aluminide coatings to form epsilon-phase (Ni/sub 3/Al). This diffusion was the primary cause of porosity formation at the aluminide/alloy interface.

  17. Effect of Preweld Heat Treatment on the Microstructure of Heat-Affected Zone (HAZ) and Weldability of Inconel 939 Superalloy

    NASA Astrophysics Data System (ADS)

    González Albarrán, M. A.; Martínez, D. I.; Díaz, E.; Díaz, J. C.; Guzman, I.; Saucedo, E.; Guzman, A. Ma.

    2014-04-01

    The effect of two preweld heat treatments on the final microstructure of a heat-affected zone (HAZ) and its effect on the weldability of the superalloy Inconel 939 have been analyzed. The HAZ cracking related to the mechanical driving force criteria during the cooling cycle was directly influenced by the strain state at this zone. Heat treatments result in the formation of (1) irregular γ' precipitates (more negative misfits) which showed higher strain (high density of interfacial dislocations) and (2) spherical precipitates (near-zero misfits) which as a result of their structure improve weldability by reducing weld HAZ cracking considerably.

  18. In situ ESEM observation of melting silver and Inconel on an Al(2)O(3) powder bed.

    PubMed

    Fischer, Simon; Lemster, Katja; Kaegi, Ralf; Kuebler, Jakob; Grobéty, Bernard

    2004-01-01

    A hot stage in an environmental scanning electron microscope (ESEM) was used for in situ infiltration experiments. Pressureless infiltration of a porous Ti-activated Al(2)O(3) preform has been investigated at temperatures up to 1530 degrees C under two atmospheres (He and H(2)O((g))). A brief description of the operating and the experimental set-up is given. Silver and Inconel (Ni superalloy) infiltration experiments demonstrate the in situ potential of the ESEM at temperatures up to 1500 degrees C. PMID:15582937

  19. Reference Specimen for Nondestructive Evaluation: Characterization of the Oxide Layer of a Cold Shot in Inconel 600

    NASA Astrophysics Data System (ADS)

    Saletes, I.; Filleter, T.; Goldbaum, D.; Chromik, R. R.; Sinclair, A. N.

    2015-02-01

    The presence of a cold shot in an aircraft turbine blade can lead to the catastrophic failure of the blade and ultimately to the failure of the power plant. Currently, no nondestructive evaluation (NDE) method exists to detect this kind of defect. This deficiency is primarily due to the fact that the only known cold shot defects in existence are those found in failed blades. Therefore, in order to develop effective NDE methods, reference specimens are needed which mimic the embedded oxide layer that is a primary distinguishing feature of a cold shot. Here, we present a procedure to synthetically reproduce the features of a real cold shot in Inconel 600 and the precise characterization of this oxide layer as a reference specimen suitable for NDE evaluation. As a first step to develop a suitable NDE technique, high-frequency ultrasound simulations are considered. A theoretical 1-D model is developed in order to quantify the multiple reflection-transmission trajectory of the acoustic wave in the reference specimen. This paper also presents an experimental determination of the density and the Young's modulus of the Inconel 600 oxide, which are required as inputs to calculate the acoustic impedance used in the theoretical model.

  20. Effect of Wire Material on Productivity and Surface Integrity of WEDM-Processed Inconel 706 for Aircraft Application

    NASA Astrophysics Data System (ADS)

    Sharma, Priyaranjan; Chakradhar, D.; Narendranath, S.

    2016-07-01

    Inconel 706 is a recently developed superalloy for aircraft application, particularly in turbine disk which is among the most critical components in the gas turbine engines. Recently, wire electrical discharge machining (WEDM) attained success in machining of gas turbine components which require complex shape profiles with high precision. To achieve the feasibility in machining of these components, the research work has been conducted on Inconel 706 superalloy using WEDM process. And, the effect of different wire materials (i.e., hard brass wire, diffused wire, and zinc-coated wire) on WEDM performance characteristics such as cutting speed, surface topography, surface roughness, recast layer formation, residual stresses, and microstructural and metallurgical alterations have been investigated. Even though, zinc-coated wire exhibits improved productivity, hard brass wire was found to be beneficial in terms of improved surface quality of the machined parts. Additionally, lower tensile residual stresses were obtained with hard brass wire. However, diffused wire has a moderate effect on productivity and surface quality. Under high discharge energy, higher elemental changes were observed and also the white layer was detected.

  1. Ultrasonic sensor signals and optimum path forest classifier for the microstructural characterization of thermally-aged inconel 625 alloy.

    PubMed

    de Albuquerque, Victor Hugo C; Barbosa, Cleisson V; Silva, Cleiton C; Moura, Elineudo P; Filho, Pedro P Rebouças; Papa, João P; Tavares, João Manuel R S

    2015-05-27

    Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ'' and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF) classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 °C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms) and accurate (accuracy of 88.75%" and harmonic mean of 89.52) for the application proposed.

  2. Ultrasonic Sensor Signals and Optimum Path Forest Classifier for the Microstructural Characterization of Thermally-Aged Inconel 625 Alloy

    PubMed Central

    de Albuquerque, Victor Hugo C.; Barbosa, Cleisson V.; Silva, Cleiton C.; Moura, Elineudo P.; Rebouças Filho, Pedro P.; Papa, João P.; Tavares, João Manuel R. S.

    2015-01-01

    Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ” and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF) classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 °C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms) and accurate (accuracy of 88.75% and harmonic mean of 89.52) for the application proposed. PMID:26024416

  3. Ultrasonic sensor signals and optimum path forest classifier for the microstructural characterization of thermally-aged inconel 625 alloy.

    PubMed

    de Albuquerque, Victor Hugo C; Barbosa, Cleisson V; Silva, Cleiton C; Moura, Elineudo P; Filho, Pedro P Rebouças; Papa, João P; Tavares, João Manuel R S

    2015-01-01

    Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ'' and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF) classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 °C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms) and accurate (accuracy of 88.75%" and harmonic mean of 89.52) for the application proposed. PMID:26024416

  4. INCONEL{reg_sign} alloy 783: An oxidation-resistant, low expansion superalloy for gas turbine applications

    SciTech Connect

    Heck, K.A.; Smith, J.S.; Smith, R.

    1998-04-01

    INCONEL{reg_sign} alloy 783 is an oxidation-resistant low coefficient of thermal expansion (low CTE) superalloy developed for gas turbine applications. Turbine efficiency can be increased through the use of low-CTE shrouds and case components that maintain tight blade tip clearances at different turbine operating temperatures. To achieve low CTE, alloys based on Ni-Fe-Co compositions require Cr content be maintained at low levels. Added Cr lowers the Curie temperature and thereby increases thermal expansion rate over a wider temperature range. The necessary lack of Cr minimizes resistance to both general oxidation and stress-accelerated grain boundary oxygen enhanced cracking (SAGBO). Increased amounts of Al in alloys strengthened by {gamma}{prime} alone also promotes SAGBO. Alloy 783 is the culmination in the development of an alloy system with very high aluminum content that, in addition to forming {gamma}{prime}, causes {beta} aluminide phase precipitation in the austenitic matrix. It was discovered that this type of structure can be processed to resist both SAGBO and general oxidation, while providing low thermal expansion and useful mechanical properties up to 700 C. The high Al content also reduces density to 5% below that of superalloys such as INCONEL alloy 718. Key aspects of the alloy development are presented, including the assessment of SAGBO resistance by evaluating elevated temperature crack growth in air. The alloy, now commercially available, has been successfully fabricated and welded into gas turbine engine components.

  5. Studies of Standard Heat Treatment Effects on Microstructure and Mechanical Properties of Laser Net Shape Manufactured INCONEL 718

    NASA Astrophysics Data System (ADS)

    Qi, H.; Azer, M.; Ritter, A.

    2009-10-01

    Laser net shape manufacturing (LNSM) is a laser cladding/deposition based technology, which can fabricate and repair near-net-shape high-performance components directly from metal powders. Characterizing mechanical properties of the laser net shape manufactured components is prerequisite to the applications of LNSM in aircraft engine industrial productions. Nickel-based superalloys such as INCONEL 718 are the most commonly used metal materials in aircraft engine high-performance components. In this study, the laser deposition process is optimized through a set of designed experiments to reduce the porosity to less than 0.03 pct. It is found that the use of plasma rotating electrode processed (PREP) powder and a high energy input level greater than 80 J/mm are necessary conditions to minimize the porosity. Material microstructure and tensile properties of laser-deposited INCONEL 718 are studied and compared under heat treatment conditions of as deposited, direct aged, solution treatment and aging (STA), and full homogenization followed by STA. Tensile test results showed that the direct age heat treatment produces the highest tensile strength equivalent to the wrought material, which is followed by the STA-treated and the homogenization-treated tensile strengths, while the ductility exhibits the reverse trend. Finally, failure modes of the tensile specimens were analyzed with fractography.

  6. Effect of Wire Material on Productivity and Surface Integrity of WEDM-Processed Inconel 706 for Aircraft Application

    NASA Astrophysics Data System (ADS)

    Sharma, Priyaranjan; Chakradhar, D.; Narendranath, S.

    2016-09-01

    Inconel 706 is a recently developed superalloy for aircraft application, particularly in turbine disk which is among the most critical components in the gas turbine engines. Recently, wire electrical discharge machining (WEDM) attained success in machining of gas turbine components which require complex shape profiles with high precision. To achieve the feasibility in machining of these components, the research work has been conducted on Inconel 706 superalloy using WEDM process. And, the effect of different wire materials (i.e., hard brass wire, diffused wire, and zinc-coated wire) on WEDM performance characteristics such as cutting speed, surface topography, surface roughness, recast layer formation, residual stresses, and microstructural and metallurgical alterations have been investigated. Even though, zinc-coated wire exhibits improved productivity, hard brass wire was found to be beneficial in terms of improved surface quality of the machined parts. Additionally, lower tensile residual stresses were obtained with hard brass wire. However, diffused wire has a moderate effect on productivity and surface quality. Under high discharge energy, higher elemental changes were observed and also the white layer was detected.

  7. Electrical discharge machining (EDM) of Inconel 718 by using copper electrode at higher peak current and pulse duration

    NASA Astrophysics Data System (ADS)

    Ahmad, S.; Lajis, M. A.

    2013-12-01

    This experimental work is an attempt to investigate the performance of Copper electrode when EDM of Nickel Based Super Alloy, Inconel 718 is at higher peak current and pulse duration. Peak current, Ip and pulse duration (pulse on-time), ton are selected as the most important electrical pulse parameters. In addition, their influence on material removal rate (MRR), electrode wear rate (EWR), and surface roughness (Ra) are experimentally investigated. The ranges of 10 mm diameter of Copper electrode are used to EDM of Inconel 718. After the experiments, MRR, EWR, and Ra of the machined surfaces need to be measured in order to evaluate the performance of the EDM process. In order to obtain high MRR, higher peak current in range of 20A to 40A and pulse duration in range of 200μs to 400μs were used. Experimental results have shown that machining at a highest peak current used of 40A and the lowest pulse duration of 200μs used for the experiment yields the highest material removal rate (MRR) with value 34.94 mm3/min, whereas machining at a peak current of 20A and pulse duration of 400μs yields the lowest electrode wear rate (EWR) with value -0.0101 mm3/min. The lowest surface roughness (Ra) is 8.53 μm achieved at a lowest peak current used of 20A and pulse duration of 200μs.

  8. Study on the microstructure, mechanical property and residual stress of SLM Inconel-718 alloy manufactured by differing island scanning strategy

    NASA Astrophysics Data System (ADS)

    Lu, Yanjin; Wu, Songquan; Gan, Yiliang; Huang, Tingting; Yang, Chuanguang; Junjie, Lin; Lin, Jinxin

    2015-12-01

    Inconel-718 has received an extensive using in mold industry. The selective laser melting (SLM) is providing an ideal means for manufacturing mold insert with complex geometrical features and internal architecture. During the manufacturing of high quality mold inserts with conformal cooling channel, the parameters play a vital role in the SLM process. In the study, the Inconel-718 alloys were manufactured by SLM with 2×2 mm2, 3×3 mm2, 5×5 mm2, and 7×7 mm2 island scanning strategies. The microstructure, mechanical property, and residual stress were investigated by optical microscope, tensile test and Vickers micro-indentation, respectively. It can be found that the relative density increased with enlarging the island size; the results on the microstructure indicated that the cracks and more pores were detected in the 22-specimen; whilst the microstructures of all specimens were composed of fine dendritic grains, cellular, and columnar structures; the tensile testing suggested that the ultimate tensile strength and yield strength of all samples was similar; while the outcome of the residual stress showed that the value of residual stress was ranked in the following sequence: 22-specimen<55-specimen<77-specimen<33-specimen. Although the 22-specimen had lower residual stress compared with the other groups, the occurrence of cracks limited its processing application in SLM. Through integrated into account, the 55-scanning strategy is a promising candidate for manufacturing of mold inserts.

  9. Effects of Various Heat Treatments on the Ballistic Impact Properties of Inconel 718 Investigated

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Lerch, Bradley A.

    2000-01-01

    Uncontained failures of aircraft engine fan blades are serious events that can cause equipment damage and loss of life. Federal Aviation Administration (FAA) certification requires that all engines demonstrate the ability to contain a released fan blade with the engine running at full power. However, increased protection generally comes at the expense of weight. Proper choice of materials is therefore imperative to an optimized design. The process of choosing a good casing material is done primarily through trial and error. This costly procedure could be minimized if there was a better understanding of the relationships among static material properties, impact properties, and failure mechanisms. This work is part of a program being conducted at the NASA Glenn Research Center at Lewis Field to study these relationships. Ballistic impact tests were conducted on flat, square sheets of Inconel 718 that had been subjected to different heat treatments. Two heat treatments and the as-received condition were studied. In addition, results were compared with those from an earlier study involving a fourth heat treatment. The heat treatments were selected on the basis of their effects on the static tensile properties of the material. The impact specimens used in this study were 17.8-cm square panels that were centered and clamped over a 15.2-cm square hole in a 1.27-cm-thick steel plate. Three nominal plate thickness dimensions were studied, 1.0, 1.8, and 2.0 mm. For each thickness, all the specimens were taken from the same sheet of material. The projectile was a Ti-6Al-4V cylinder with a length of 25.4 mm, a diameter of 12.7 mm, and a mass ranging from 14.05 to 14.20 g. The projectiles were accelerated toward the specimens at normal incidence using a gas gun with a 2-m-long, 12.7-mm inner-diameter barrel. The ballistic limit for each heat treatment condition and thickness was determined by conducting a number of impact tests that bracketed as closely as possible the velocity

  10. The effect of sheet processing on the microstructure, tensile, and creep behavior of INCONEL alloy 718

    NASA Astrophysics Data System (ADS)

    Boehlert, C. J.; Dickmann, D. S.; Eisinger, Ny. N. C.

    2006-01-01

    The grain size, grain boundary character distribution (GBCD), creep, and tensile behavior of INCONEL alloy 718 (IN 718) were characterized to identify processing-microstructure-property relationships. The alloy was sequentially cold rolled (CR) to 0, 10, 20, 30, 40, 60, and 80 pct followed by annealing at temperatures between 954 °C and 1050 °C and the traditional aging schedule used for this alloy. In addition, this alloy can be superplastically formed (IN 718SPF) to a significantly finer grain size and the corresponding microstructure and mechanical behavior were evaluated. The creep behavior was evaluated in the applied stress (σ a ) range of 300 to 758 MPa and the temperature range of 638 °C to 670 °C. Constant-load tensile creep experiments were used to measure the values of the steady-state creep rate and the consecutive load reduction method was used to determine the values of backstress (σ0). The values for the effective stress exponent and activation energy suggested that the transition between the rate-controlling creep mechanisms was dependent on effective stresses (σ e =σ a σ0) and the transition occurred at σ e ≅ 135 MPa. The 10 to 40 pct CR samples exhibited the greatest 650 °C strength, while IN 718SPF exhibited the greatest room-temperature (RT) tensile strength (>1550 MPa) and ductility (ɛ f >16 pct). After the 954 °C annealing treatment, the 20 pct CR and 30 pct CR microstructures exhibited the most attractive combination of elevated-temperature tensile and creep strength, while the most severely cold-rolled materials exhibited the poorest elevated-temperature properties. After the 1050 °C annealing treatment, the IN 718SPF material exhibited the greatest backstress and best creep resistance. Electron backscattered diffraction was performed to identify the GBCD as a function of CR and annealing. The data indicated that annealing above 1010 °C increased the grain size and resulted in a greater fraction of twin boundaries, which in

  11. Measurement of desorption energies of H 2 and CO from SS-304 LN and inconel 625 surfaces by laser induced thermal desorption

    NASA Astrophysics Data System (ADS)

    Tagle, J. A.; Pospieszczyk, A.

    Stainless steel (AISI 304 LN) and Inconel 625 surfaces have been exposed to different pressures of H 2 and CO in the temperature range of 300-473 K. A laser heating technique for studying fast surface processes was applied to determine the desorption energies of these gasses from SS 304 LN and Inconel 625 surfaces. The Clausius-Clapeyron plots give a desorption energy value of 97 kJ mol -1 for H 2/SS 304 LN and 77.4 kJ mol -1 for H 2/Inconel 625. The adsorption of CO on these surfaces is drastically affected by the fast growing of a chromium oxide layer at the surface during the laser shots. In this case the desorption energy was determined by fitting both the experimental recoverage times and the equilibrium coverage curves. The oxide passivation layer produces a decrease of the desorption energy from 92.8 to 72.8 kJ mol -1 for CO/SS 304 LN and from 91.8 to 77.9 kJ mol -1 for CO/Inconel 625 when the oxygen surface concentration increases to 14%.

  12. INCONEL 690 CORROSION IN WTP (WASTE TREATMENT PLANT) HLW (HIGH LEVEL WASTE) GLASS MELTS RICH IN ALUMINUM & BISMUTH & CHROMIUM OR ALUMINUM/SODIUM

    SciTech Connect

    KRUGER AA; FENG Z; GAN H; PEGG IL

    2009-11-05

    Metal corrosion tests were conducted with four high waste loading non-Fe-limited HLW glass compositions. The results at 1150 C (the WTP nominal melter operating temperature) show corrosion performance for all four glasses that is comparable to that of other typical borosilicate waste glasses, including HLW glass compositions that have been developed for iron-limited WTP streams. Of the four glasses tested, the Bi-limited composition shows the greatest extent of corrosion, which may be related to its higher phosphorus content. Tests at higher suggest that a moderate elevation of the melter operating temperature (up to 1200 C) should not result in any significant increase in Inconel corrosion. However, corrosion rates did increase significantly at yet higher temperatures (1230 C). Very little difference was observed with and without the presence of an electric current density of 6 A/inch{sup 2}, which is the typical upper design limit for Inconel electrodes. The data show a roughly linear relationship between the thickness of the oxide scale on the coupon and the Cr-depletion depth, which is consistent with the chromium depletion providing the material source for scale growth. Analysis of the time dependence of the Cr depletion profiles measured at 1200 C suggests that diffusion of Cr in the Ni-based Inconel alloy controls the depletion depth of Cr inside the alloy. The diffusion coefficient derived from the experimental data agrees within one order of magnitude with the published diffusion coefficient data for Cr in Ni matrices; the difference is likely due to the contribution from faster grain boundary diffusion in the tested Inconel alloy. A simple diffusion model based on these data predicts that Inconel 690 alloy will suffer Cr depletion damage to a depth of about 1 cm over a five year service life at 1200 C in these glasses.

  13. Gamma Prime Precipitation, Dislocation Densities, and TiN in Creep-Exposed Inconel 617 Alloy

    NASA Astrophysics Data System (ADS)

    Krishna, Ram; Atkinson, Helen V.; Hainsworth, Sarah V.; Gill, Simon P.

    2016-01-01

    Inconel 617 is a solid-solution-strengthened Ni-based superalloy with a small amount of gamma prime (γ') present. Here, samples are examined in the as-received condition and after creep exposure at 923 K (650 °C) for 574 hours and 45,000 hours and at 973 K (700 °C) for 4000 hours. The stress levels are intermediate (estimated, respectively, as of the order of 350, 275, and 200 MPa) and at levels of interest for the future operation of power plant. The hardness of the specimens has been measured in the gage length and the head. TEM thin foils have been obtained to quantify dislocation densities (3.5 × 1013 for the as-received, 5.0 × 1014, 5.9 × 1014, and 3.5 × 1014 lines/m2 for the creep-exposed specimens, respectively). There are no previous data in the literature for dislocation densities in this alloy after creep exposure. There is some evidence from the dislocation densities that for the creep-exposed samples, the higher hardness in the gage length in comparison with the creep test specimen head is due to work hardening rather than any other effect. Carbon replicas have been used to extract gamma prime precipitates. The morphology of γ' precipitates in the `as-received' condition was spheroidal with an average diameter of 18 nm. The morphology of these particles does not change with creep exposure but the size increases to 30 nm after 574 hours at 923 K (650 °C) but with little coarsening in 45,000 hours. At 973 K (700 °C) 4000 hours, the average gamma prime size is 32 nm. In the TEM images of the replicas, the particles overlap, and therefore, a methodology has been developed to estimate the volume fraction of gamma prime in the alloy given the carbon replica film thickness. The results are 5.8 vol pct in the as-received and then 2.9, 3.2, and 3.4 vol pct, respectively, for the creep-exposed specimens. The results are compared with predictions from thermodynamic analysis given the alloy compositions. Thermodynamic prediction shows that nitrogen

  14. Comparison of residual stresses in Inconel 718 simple parts made by electron beam melting and direct laser metal sintering

    DOE PAGES

    Kolbus, Lindsay M.; Payzant, E. Andrew; Cornwell, Paris A.; Watkins, Thomas R.; Babu, Sudarsanam Suresh; Dehoff, Ryan R.; Duty, Chad E.; Lorenz, M.; Ovchinnikova, O. S.

    2015-01-10

    Residual stress profiles were mapped using neutron diffraction in two simple prism builds of Inconel 718: one fabricated with electron beam melting and the other with direct laser sintering. Spatially indexed stress-free cubes were obtained by EDM sectioning equivalent prisms of similar shape. The (311) interplanar spacing examined for the EDM sectioned sample was compared to the interplanar spacings calculated to fulfill force and moment balance. We have shown that Applying force and moment balance is a necessary supplement to the measurements for the stress-free cubes with respect to accurate stress calculations in additively manufactured components. Furthermore, our work hasmore » shown that residual stresses in electron beam melting parts are much smaller than that of direct laser metal sintering parts.« less

  15. Study of Radiographic Linear Indications and Subsequent Microstructural Features in Gas Tungsten Arc Welds of Inconel 718

    NASA Technical Reports Server (NTRS)

    Walley, J. L.; Nunes, A. C.; Clounch, J. L.; Russell, C. K.

    2007-01-01

    This study presents examples and considerations for differentiating linear radiographic indications produced by gas tungsten arc welds in a 0.05-in-thick sheet of Inconel 718. A series of welds with different structural features, including the enigma indications and other defect indications such as lack of fusion and penetration, were produced, radiographed, and examined metallographically. The enigma indications were produced by a large columnar grain running along the center of the weld nugget occurring when the weld speed was reduced sufficiently below nominal. Examples of respective indications, including the effect of changing the x-ray source location, are presented as an aid to differentiation. Enigma, nominal, and hot-weld specimens were tensile tested to demonstrate the harmlessness of the enigma indication. Statistical analysis showed that there is no difference between the strengths of these three weld conditions.

  16. Comparison of residual stresses in Inconel 718 simple parts made by electron beam melting and direct laser metal sintering

    SciTech Connect

    Kolbus, Lindsay M.; Payzant, E. Andrew; Cornwell, Paris A.; Watkins, Thomas R.; Babu, Sudarsanam Suresh; Dehoff, Ryan R.; Duty, Chad E.; Lorenz, M.; Ovchinnikova, O. S.

    2015-01-10

    Residual stress profiles were mapped using neutron diffraction in two simple prism builds of Inconel 718: one fabricated with electron beam melting and the other with direct laser sintering. Spatially indexed stress-free cubes were obtained by EDM sectioning equivalent prisms of similar shape. The (311) interplanar spacing examined for the EDM sectioned sample was compared to the interplanar spacings calculated to fulfill force and moment balance. We have shown that Applying force and moment balance is a necessary supplement to the measurements for the stress-free cubes with respect to accurate stress calculations in additively manufactured components. Furthermore, our work has shown that residual stresses in electron beam melting parts are much smaller than that of direct laser metal sintering parts.

  17. TEM, HRTEM, electron holography and electron tomography studies of gamma' and gamma'' nanoparticles in Inconel 718 superalloy.

    PubMed

    Dubiel, B; Kruk, A; Stepniowska, E; Cempura, G; Geiger, D; Formanek, P; Hernandez, J; Midgley, P; Czyrska-Filemonowicz, A

    2009-11-01

    The aim of the study was the identification of gamma' and gamma'' strengthening precipitates in a commercial nickel-base superalloy Inconel 718 (Ni-19Fe-18Cr-5Nb-3Mo-1Ti-0.5Al-0.04C, wt %) using TEM dark-field, HRTEM, electron holography and electron tomography imaging. To identify gamma' and gamma'' nanoparticles unambiguously, a systematic analysis of experimental and theoretical diffraction patterns were performed. Using HRTEM method it was possible to analyse small areas of precipitates appearance. Electron holography and electron tomography techniques show new possibilities of visualization of gamma' and gamma'' nanoparticles. The analysis by means of different complementary TEM methods showed that gamma'' particles exhibit a shape of thin plates, while gamma' phase precipitates are almost spherical. PMID:19903242

  18. The effect of varying AI, Ti,and Nb content on the phase stability of INCONEL 718

    NASA Astrophysics Data System (ADS)

    Collier, John P.; Wong, Song How; Tien, John K.; Phillips, James C.

    1988-07-01

    The effects of varying the strengthening alloying elements on the microstructural stability of the superalloy INCONEL 718 have been investigated using scanning electron microscopy, transmission electron microscopy, and X-ray and synchrotron diffractometry. Time-temperature-transformation curves were determined for the embrittling σ-phase using conventional and synchrotron X-ray diffractometry. Increasing the Al/Ti ratio and the Al + Ti concentration in the alloy decreases the driving force both to form σ phase and coarsen γ". Abbreviated mechanical tests also indicate that the alloys with the highest Al + Ti content and Al/Ti ratio are more stable than the commercial “SUPER” IN718 after long times at elevated temperatures.

  19. Effect of nanostructured composite powders on the structure and strength properties of the high-temperature inconel 718 alloy

    NASA Astrophysics Data System (ADS)

    Cherepanov, A. N.; Ovcharenko, V. E.

    2015-12-01

    The experimental results of the effect of powder nanomodifiers of refractory compounds on the strength properties, the macro- and microstructure of the high-temperature Inconel 718 alloy have been presented. It has been shown that the introduction of powder modifiers into the melt leads to a decrease in the average grain size by a factor of 1.5-2 in the alloy. The long-term tensile strength of the alloy at 650°C increases 1.5-2 times, and the number of cycles at 482°C before fracture grows by more than three times. The effect of nanoparticles on the grain structure and strength properties of the alloy is due to an increase in the number of generated crystallization centers and the formation of nanoparticle clusters of refractory compounds at boundaries and junctions in the formed grain structure, which hinder the development of recrystallization processes in the alloy.

  20. Sensitivity analysis of tool-chip contact parameters when predicting residual stresses in turning of Inconel 718

    NASA Astrophysics Data System (ADS)

    Torrano, I.; Barbero, O.; Kortabarria, A.; Arrazola, P. J.

    2012-04-01

    Heat-resistant alloys like Inconel 718 are used in critical components such as aircraft engine turbine discs. Due to the extreme thermo-mechanical solicitations that must suffer during their lifetime, reliability is essential, even more if its failure could lead to loss of human lives. Surface integrity is a critical issue in this kind of components and specially residual stresses are a key aspect. Currently, the development and optimization of the machining process with regards to the residual stresses is done through expensive experimental trial and error methods. This article shows the research work made on the simulation of a machining model in three dimensions with the Deform TM commercial program. The results obtained show the influence of contact parameters (friction coefficient, heat transfer coefficient) not only on the cutting forces and temperatures, but also in the generation of residual stresses.

  1. Oxidation products of Inconel alloys 600 and 690 in hydrogenated steam environments and their role in stress corrosion cracking

    NASA Astrophysics Data System (ADS)

    Ferguson, J. Bryce

    Inconel Alloys 600 and 690 are used extensively in components of Nuclear Pressurized Water Reactors (PWR) in the primary water loop which consists of H2 supersaturated steam. Alloy 600 has been found to crack intergranularly when exposed to primary water conditions. Alloy 690 was designed as a replacement and is generally regarded as immune to cracking. There is no consensus as to the mechanism which is responsible for cracking or the lack thereof in these alloys. In this work thermodynamic arguments for the stability of Ni and Cr compounds developed under pressurized water reactor environments ( PH2O and PH2 ) were experimentally tested. A mechanism is proposed to explain crack initiation and propagation alloy 600 along the grain boundaries where Cr2O3 has formed from the leaching of Cr from the matrix leaving behind a porous Ni-rich region. The mechanism is based on the thermodynamic potential for the transformation of a protective NiO surface layer into an amorphous non-protective Ni(OH)2 gel. This gel would also form along the grain boundaries and when hydrogenated steam reaches the porous Ni-rich regions. Crack initiation is then favored by tensile stressing of the grain boundary regions which can easily rupture the gelatinous film. The leaching of matrix Cr to form non-protective CrOOH gel at the crack tip followed by the exposure of fresh porous Ni to the environment also explains crack propagation in inconel alloy 600. The proposed crack initiation mechanism is not expected to occur in alloy 690 where a protective Cr2O 3 film covers the entire metal surface. However, crack propagation along the grain boundaries in alloy 600 and pre-cracked alloy 690 is expected to be active as hydroxide-forming reactions weaken the material at the grain boundaries.

  2. Time-Dependent Fatigue Crack Propagation Behavior of Two Solid-Solution-Strengthened Ni-Based Superalloys—INCONEL 617 and HAYNES 230

    NASA Astrophysics Data System (ADS)

    Ma, Longzhou; Roy, Shawoon K.; Hasan, Muhammad H.; Pal, Joydeep; Chatterjee, Sudin

    2012-02-01

    The fatigue crack propagation (FCP) as well as the sustained loading crack growth (SLCG) behavior of two solid-solution-strengthened Ni-based superalloys, INCONEL 617 (Special Metals Corporation Family of Companies) and HAYNES 230 (Haynes International, Inc., Kokomo, IN), were studied at increased temperatures in laboratory air under a constant stress-intensity-factor ( K) condition. The crack propagation tests were conducted using a baseline cyclic triangular waveform with a frequency of 1/3 Hz. Various hold times were imposed at the maximum load of a fatigue cycle to study the hold time effect. The results show that a linear elastic fracture mechanics (LEFM) parameter, stress intensity factor ( K), is sufficient to describe the FCP and SLCG behavior at the testing temperatures ranging from 873 K to 1073 K (600 °C to 800 °C). As observed in the precipitation-strengthened superalloys, both INCONEL 617 and HAYNES 230 exhibited the time-dependent FCP, steady SLCG behavior, and existence of a damage zone ahead of crack tip. A thermodynamic equation was adapted to correlate the SLCG rates to determine thermal activation energy. The fracture modes associated with crack propagation behavior were discussed, and the mechanism of time-dependent FCP as well as SLCG was identified. Compared with INCONEL 617, the lower crack propagation rates of HAYNES 230 under the time-dependent condition were ascribed to the different fracture mode and the presence of numerous W-rich M6C-type and Cr-rich M23C6-type carbides. Toward the end, a phenomenological model was employed to correlate the FCP rates at cycle/time-dependent FCP domain. All the results suggest that an environmental factor, the stress assisted grain boundary oxygen embrittlement (SAGBOE) mechanism, is mainly responsible for the accelerated time-dependent FCP rates of INCONEL 617 and HAYNES 230.

  3. Microstructural Changes in Inconel® 740 After Long-Term Aging in the Presence and Absence of Stress

    SciTech Connect

    Unocic, Kinga A.; Shingledecker, John Paul; Tortorelli, Peter F.

    2014-11-18

    The Ni-based alloy, Inconel® 740, is being extensively examined for use in advanced ultrasupercritical steam boilers because its precipitation-strengthened microstructure appears to offer the necessary creep strength under the high temperatures and pressures (up to 760°C and 35 MPa) needed for high efficiency power generation. However, because this application requires extremely long lifetimes under these conditions (up to 30 years), long-term microstructure stability is a major concern. In this study, results from microstructural analyses of Inconel 740 specimens aged at 700 and 750°C in the presence and absence of creep loading for times up to ~31,000 h are presented. The primary focus was on the development of the eta η (Ni3Ti) phase and coarsening of coherent γ'-Ni3(Al,Ti) precipitates and its depletion near eta/matrix interfaces. Finally, however, despite these processes, Inconel 740 showed adequate long-term microstructural stability to assure adequate creep strength for the intended application.

  4. Determination of Yield in Inconel 718 for Axial-Torsional Loading at Temperatures up to 649 C

    NASA Technical Reports Server (NTRS)

    Gil, Christopher M.; Lissenden, Cliff J.; Lerch, Bradley A.

    1998-01-01

    An experimental program has been implemented to determine small offset yield loci under axial-torsional loading at elevated temperatures. The nickel-base superalloy Inconel 718 (IN718) was chosen for study due to its common use in aeropropulsion applications. Initial and subsequent yield loci were determined for solutioned IN718 at 23, 371, and 454 C and for aged (precipitation hardened) IN718 at 23 and 649 C. The shape of the initial yield loci for solutioned and aged IN718 agreed well with the von Mises prediction. However, in general, the centers of initial yield loci were eccentric to the origin due to a strength-differential (S-D) effect that increased with temperature. Subsequent yield loci exhibited anisotropic hardening in the form of translation and distortion of the locus. This work shows that it is possible to determine yield surfaces for metallic materials at temperatures up to at least 649 C using multiple probes of a single specimen. The experimental data is first-of-its-kind for a superalloy at these very high temperatures and will facilitate a better understanding of multiaxial material response, eventually leading to improved design tools for engine designers.

  5. Long-Term Creep of a Thin-Walled Inconel 718 Stirling Power-Convertor Heater Head Assessed

    NASA Technical Reports Server (NTRS)

    Bowman, Randy R.

    2002-01-01

    The Department of Energy and NASA have identified Stirling power convertors as candidate power supply systems for long-duration, deep-space science missions. A key element for qualifying the flight hardware is a long-term durability assessment for critical hot section components of the power convertor. One such critical component is the power convertor heater head. The heater head is a high-temperature pressure vessel that transfers heat to the working gas medium of the convertor, which is typically helium. An efficient heater head design is the result of balancing the divergent requirements of thin walls for increased heat transfer versus thick walls to lower the wall stresses and thus improve creep resistance and durability. In the current design, the heater head is fabricated from the Ni-base superalloy Inconel 718 (IN 718, Inco Alloys International, Inc., Huntington, WV). Although IN 718 is a mature alloy system (patented in 1962), there is little long-term (>50,000-hr) creep data available for thin-specimen geometries. Since thin-section properties tend to be inferior to thicker samples, it is necessary to generate creep data using specimens with the same geometry as the actual flight hardware. Therefore, one facet of the overall durability assessment program involves generating relatively short-term creep data using thin specimens at the design temperature of 649 C (1200 F).

  6. Particle Size of Gamma Prime as a Result of Vacuum Heat Treatment of INCONEL 738 Super Alloy

    NASA Astrophysics Data System (ADS)

    Guzman, I.; Granda, E.; Mendez, R.; Lopez, G.; Acevedo, J.; Gonzalez, D.

    2013-04-01

    In this paper, the influence of the cooling rate and cooling media after a standard solution heat treatment on the size and distribution of the gamma prime phase (γ') in the nickel-based super alloy INCONEL 738 in over-aged conditions is described. The volume fraction of the gamma prime depends on the chemical composition of the alloy, the solution treatment temperature and the cooling rate; in over-aged alloys (i.e., with more than 25,000 h of service) the volume fraction of γ' is about 78.8%. However, it has been demonstrated that in order to maintain excellent creep strength a volume fraction of at least 60% or lower is required. In this work the volume fraction was optimized between 40 and 55% by means of a standard solution heat treatment at 1120 °C using different cooling gases. A γ' volume fraction of 54.8% was obtained by using argon as the cooling medium at a cooling rate of 87 °C/min, producing a precipitate of partial distribution of primary and secondary γ'. Better results were obtained in a nitrogen atmosphere at a cooling rate of 287 °C/min, leading to a volume fraction of 40% and obtaining a total re-precipitation of primary and secondary γ'.

  7. The Influence of Welding Parameters on the Nugget Formation of Resistance Spot Welding of Inconel 625 Sheets

    NASA Astrophysics Data System (ADS)

    Rezaei Ashtiani, Hamid Reza; Zarandooz, Roozbeh

    2015-09-01

    A 2D axisymmetric electro-thermo-mechanical finite element (FE) model is developed to investigate the effect of current intensity, welding time, and electrode tip diameter on temperature distributions and nugget size in resistance spot welding (RSW) process of Inconel 625 superalloy sheets using ABAQUS commercial software package. The coupled electro-thermal analysis and uncoupled thermal-mechanical analysis are used for modeling process. In order to improve accuracy of simulation, material properties including physical, thermal, and mechanical properties have been considered to be temperature dependent. The thickness and diameter of computed weld nuggets are compared with experimental results and good agreement is observed. So, FE model developed in this paper provides prediction of quality and shape of the weld nuggets and temperature distributions with variation of each process parameter, suitably. Utilizing this FE model assists in adjusting RSW parameters, so that expensive experimental process can be avoided. The results show that increasing welding time and current intensity lead to an increase in the nugget size and electrode indentation, whereas increasing electrode tip diameter decreases nugget size and electrode indentation.

  8. The Microstructural Evolution of Inconel Alloy 740 During Solution Treatment, Aging, and Exposure at 760 °C

    SciTech Connect

    Cowen, Christopher J.; Danielson, Paul E.; Jablonski, Paul D.

    2010-08-10

    In this study, the microstructural evolution of Inconel alloy 740 during solution treatment and aging was characterized using optical and scanning electron microscopy. During double solution heat treatment, carbon is liberated from the dissolution of MC carbides during the first solution treatment at 1150 °C, and fine MC carbides are precipitated on gamma grain boundaries during the second solution treatment at 1120 °C. Due to the concurrent decrease in carbon solubility and the increase in the contribution of grain boundary diffusion at lower temperatures, the MC carbides on the gamma grain boundaries provide a localized carbon reservoir that aids in M23C6 carbide precipitation on gamma grain boundaries during exposure at 760 °C. The γ' phase, which is the key strengthening phase in alloy 740, is incorporated into the alloy microstructure during aging at 850 °C. Finally, the main source of microstructural instability observed during exposure at 760 °C was the coarsening of the γ' phase.

  9. High-temperature-oxidation-induced ordered structure in Inconel 939 superalloy exposed to oxy-combustion environments

    SciTech Connect

    Zhu, Jingxi; Wise, Adam; Nuhfer, Thomas; Holcomb, Gordon R; Jablonski, Paul D; Sridhar, Seetharaman; Laughlin, David E

    2013-04-20

    In the integrated oxy-fuel combustion and turbine power generation system, turbine alloys are exposed to high temperature and an atmosphere comprised of steam, CO2 and O2. While surface and internal oxidation of the alloy takes place, the microstructure in the subsurface region also changes due to oxidation that results in the loss of the strengthening precipitates. In an earlier study of the oxidation of Inconel 939 Ni-based superalloy exposed to oxy-fuel combustion environment for up to 1000 hours, a high-temperature-oxidation-induced phase transformation in the sub-surface region was noticed and a two-phase region formed at the expense of strengthening γ' phase. While one of the two phases was identified as the Ni-matrix (γ solid solution, face-center-cubic) phase, the other product phase remained unidentified. In this study, the crystal structure of the unknown phase and its orientation relationship with the parent Ni-matrix phase was investigated through electron diffraction and high-resolution transmission electron microscopy. It was determined that the crystal structure of the unknown phase could be modeled as a ternary derivative of the ordered η-Ni3Ti phase (D024) structure with lattice parameters of a = 0.5092 nm and c = 0.8336 nm, α = 90º, β = 90º and γ = 120º.

  10. Control of interfacial reactions during liquid phase processing of aluminum matrix composites reinforced with INCONEL 601 fibers

    NASA Astrophysics Data System (ADS)

    Boland, F.; Colin, C.; Delannay, F.

    1998-06-01

    A comprehensive investigation is made of the parameters affecting the extent of interface reactions during squeeze casting of composites consisting of a matrix of either pure Al or alloy AS13 reinforced with fibers of INCONEL 601. The process parameters are the preform thickness and temperature, the fiber volume fraction, the temperature and mass of the liquid metal, and the temperature of the die. Adjustment of these process parameters made possible the full control of reactions. It is found that reactions proceed mainly in the solid state after decomposition of the oxide barrier layer covering the fibers. A simple kinetic model is developed that enlightens the role of this barrier layer. No trace of reaction could be detected in composites processed using preoxidized preforms. Alloying Al with Si also induces a drastic reduction of reactivity. The high ductility of the composites attests to the processing quality. An original procedure is proposed for measuring the activation energy for initiation of reactions by differential thermal analysis.

  11. Effect of prolonged isothermal exposure on elevated-temperature, time-dependent fatigue-crack propagation in INCONEL alloy 783

    NASA Astrophysics Data System (ADS)

    Ma, Longzhou; Chang, Keh-Minn; Mannan, Sarwan K.; Patel, Shailesh J.

    2002-11-01

    The effect of isothermal exposure on the elevated-temperature, time-dependent fatigue-crack propagation (FCP) in INCONEL Alloy 783 is investigated. Commercially produced Alloy 783 was annealed and aged following the standard heat-treatment procedure. One set of specimens was then isothermally exposed at 500 °C for 3000 hours. All specimens were subjected to FCP tests with various hold-time periods and sustained-loading crack-growth tests at 538 °C and 650 °C in a laboratory-air environment. Without a hold time, the as-produced and isothermally exposed materials had comparable FCP rates at both test temperatures. With hold times of 100 and 300 seconds, the as-produced and isothermally exposed specimens had comparable FCP rates at 538 °C. Hold-time testing of the as-produced material at 650 °C showed abnormal time-dependent FCP and sustained-loading crack-growth retardation. However, hold-time testing of isothermally exposed material at 650 °C showed the steady sustained-loading crack growth and fully time-dependent FCP typically observed in many superalloys. Comparison with Alloy 718 data from the literature shows that FCP rates of as-produced Alloy 718 and isothermally exposed Alloy 783 are comparable at 650 °C. A fully time-dependent FCP model based on the damage-zone concept and a thermal-activation equation is proposed to characterize the FCP behaviors.

  12. Effect of boron segregation at grain boundaries on heat-affected zone cracking in wrought INCONEL 718

    NASA Astrophysics Data System (ADS)

    Chen, W.; Chaturvedi, M. C.; Richards, N. L.

    2001-04-01

    Susceptibility to heat-affected zone (HAZ) cracking during electron-beam welding was studied in two INCONEL 718-based alloys doped with different levels of boron. By lowering the carbon, sulfur, and phosphorous concentrations to be “as low as possible,” the occurrence of HAZ cracking was related directly to the level of segregation of boron at grain boundaries, which occurred by nonequilibrium segregation during a preweld heat treatment. The study has demonstrated a direct correlation between the amount of boron segregated at grain boundaries and their susceptibility to HAZ cracking, in terms of the total crack length and number of cracks observed in the HAZ. The analysis of results suggests that both the melting and resolidification temperatures of the boron-segregated grain boundaries can be about 100 °C to 200 °C lower than those of the grain boundaries that were susceptible to constitutional liquation of Nb carbides on them, making boron more deleterious in causing HAZ cracking.

  13. Microstructural Features Controlling the Variability in Low-Cycle Fatigue Properties of Alloy Inconel 718DA at Intermediate Temperature

    NASA Astrophysics Data System (ADS)

    Texier, Damien; Gómez, Ana Casanova; Pierret, Stéphane; Franchet, Jean-Michel; Pollock, Tresa M.; Villechaise, Patrick; Cormier, Jonathan

    2016-03-01

    The low-cycle fatigue behavior of two direct-aged versions of the nickel-based superalloy Inconel 718 (IN718DA) was examined in the low-strain amplitude regime at intermediate temperature. High variability in fatigue life was observed, and abnormally short lifetimes were systematically observed to be due to crack initiation at (sub)-surface non-metallic inclusions. However, crack initiation within (sub)-surface non-metallic inclusions did not necessarily lead to short fatigue life. The macro- to micro-mechanical mechanisms of deformation and damage have been examined by means of detailed microstructural characterization, tensile and fatigue mechanical tests, and in situ tensile testing. The initial stages of crack micro-propagation from cracked non-metallic particles into the surrounding metallic matrix occupies a large fraction of the fatigue life and requires extensive local plastic straining in the matrix adjacent to the cracked inclusions. Differences in microstructure that influence local plastic straining, i.e., the δ-phase content and the grain size, coupled with the presence of non-metallic inclusions at the high end of the size distribution contribute strongly to the fatigue life variability.

  14. Swept frequency eddy current (SFEC) measurements of Inconel 718 as a function of microstructure and residual stress

    NASA Astrophysics Data System (ADS)

    Chandrasekar, Ramya

    The goal of this thesis was to determine the dependency of swept frequency eddy current (SFEC) measurements on the microstructure of the Ni-based alloy, Inconel 718 as a function of heat treatment and shot peening. This involved extensive characterization of the sample using SEM and TEM coupled with measurements and analysis of the eddy current response of the various sample conditions using SFEC data. Specific objectives included determining the eddy current response at varying depths within the sample, and this was accomplished by taking SFEC measurements in frequencies ranging from 100 kHz to 50 MHz. Conductivity profile fitting of the resulting SFEC signals was obtained by considering influencing factors (such as surface damage). The problems associated with surface roughness and near surface damage produced by shot peening were overcome by using an inversion model. Differences in signal were seen as a result of precipitation produced by heat treatment and by residual stresses induced due to the shot peening. Hardness of the material, which is related both to precipitation and shot peening, was seen to correlate with the measured SFEC signal. Surface stress measurement was carried out using XRD giving stress in the near surface regions, but not included in the calculations due to shallow depth information provided by the technique compared to SFEC. By comparing theoretical SFEC signal computed using the microstructural values (precipitate fraction) and experimental SFEC data, dependency of the SFEC signals on microstructure and residual stress was obtained.

  15. Understanding the Role of Hot Isostatic Pressing Parameters on the Microstructural Evolution of Ti-6Al-4V and Inconel 718 Fabricated by Electron Beam Melting

    SciTech Connect

    Peter, William H.; Nandwana, Peeyush; Kirka, Michael M.; Dehoff, Ryan R.; Sames, William; Erdman, III, Donald L.; Eklund, Anders; Howard, Ron

    2015-04-01

    In this project, Avure and ORNL evaluated the influence of hot isostatic pressing (HIP) and thermal cycling as standalone post processing techniques on the microstructure of electron beam powder bed deposited Ti-6Al-4V and Inconel 718 alloys. Electron beam powder bed deposition is an effective technology for fabricating complex net shape components that cannot be manufactured with conventional processes. However, material deposited by this technology results in columnar grain growth which is detrimental for many applications. For Ti-6Al-4V, it has been found that thermal cycling alone is not sufficient to breakdown the columnar microstructure that is typical of electron beam powder bed technology. HIP, on the other hand, has the potential to be an effective technique to break down the columnar microstructure of Ti-6Al-4V into a more equiaxed and refined β grain structure, and provide a more homogeneous microstructure compared to the thermally cycled samples. Overall, the project showed that hot isostatic pressing reduced/eliminated porosity in both Ti-6Al-4V and Inconel 718 However, based on the unique thermal cycle and the application of pressure in the HIP vessel, Ti-6Al-4V e-beam deposited microstructures were modified from columnar grain growth to equiaxed microstructures; a significant outcome to this collaboration. Inconel 718, on the other hand, shows no change in the macrostructure as a result of the current HIP cycle based on the thermal history, and would require further investigation. Though the results of HIP cycle were very good at changing the microstructure, further development in optimizing the post heat treatments and HIP cycles is required to improve mechanical properties.

  16. Effects of Heat Treatment on the Ballistic Impact Properties of Inconel 718 for Jet Engine Fan Containment Applications

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Lerch, Bradley A.

    2001-01-01

    The effects of heat treating Inconel 718 on the ballistic impact response and failure mechanisms were studied. Two different annealing conditions and an aged condition were considered. Large differences in the static properties were found between the annealed and the aged material, with the annealed condition having lower strength and hardness and greater elongation than the aged. High strain rate tests show similar results. Correspondingly large differences were found in the velocity required to penetrate material in the two conditions in impact tests involving 12.5 mm diameter, 25.4 mm long cylindrical Ti-6-4 projectiles impacting flat plates at velocities in the range of 150 to 300 m/sec. The annealed material was able to absorb over 25 percent more energy than the aged. This is contrary to results observed for ballistic impact response for higher velocity impacts typically encountered in military applications where it has been shown that there exists a correlation between target hardness and ballistic impact strength. Metallographic examination of impacted plates showed strong indication of failure due to adiabatic shear. In both materials localized bands of large shear deformation were apparent, and microhardness measurements indicated an increase in hardness in these bands compared to the surrounding material. These bands were more localized in the aged material than in the annealed material. In addition the annealed material underwent significantly greater overall deformation before failure. The results indicate that lower elongation and reduced strain hardening behavior lead to a transition from shear to adiabatic shear failure, while high elongation and better strain hardening capabilities reduce the tendency for shear to localize and result in an unstable adiabatic shear failure. This supports empirical containment design methods that relate containment thickness to the static toughness.

  17. Effects of Heat Treatment on the Ballistic Impact Properties of Inconel 718 for Jet Engine Fan Containment Applications

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Lerch, Bradley A.

    1999-01-01

    The effects of heat treating Inconel 718 on the ballistic impact response and failure mechanisms were studied. Two different annealing conditions and an aged condition were considered. Large differences in the static properties were found between the annealed and the aged material, with the annealed condition having lower strength and hardness and greater elongation than the aged. High strain rate tests show similar results. Correspondingly large differences were found in the velocity required to penetrate material in the two conditions in impact tests involving 12.5 mm diameter, 25.4 mm long cylindrical Ti-6-4 projectiles impacting flat plates at velocities in the range of 150 to 300 m/sec. The annealed material was able to absorb over 25 percent more energy than the aged. This is contrary to results observed for ballistic impact response for higher velocity impacts typically encountered in military applications where it has been shown that there exists a correlation between target hardness and ballistic impact strength. Metallographic examination of impacted plates showed strong indication of failure due to adiabatic shear. In both materials localized bands of large shear deformation were apparent, and microhardness measurements indicated an increase in hardness in these bands compared to the surrounding material. These bands were more localized in the aged material than in the annealed material. In addition the annealed material underwent significantly greater overall deformation before failure. The results indicate that lower elongation and reduced strain hardening behavior lead to a transition from shear to adiabatic shear failure, while high elongation and better strain hardening capabilities reduce the tendency for shear to localize and result in an unstable adiabatic shear failure. This supports empirical containment design methods that relate containment thickness to the static toughness.

  18. Effect of simultaneous helium implantation on the microstructure evolution of Inconel X-750 superalloy during dual-beam irradiation

    NASA Astrophysics Data System (ADS)

    Changizian, P.; Zhang, H. K.; Yao, Z.

    2015-12-01

    This study focuses on investigation into the effect of helium implantation on microstructure evolution in Inconel X-750 superalloy during dual-beam (Ni+/He+) irradiation. The 1 MeV Ni+ ions with the damage rate of 10-3 dpa/s as well as 15 keV He+ ions using rate of 200 appm/dpa were simultaneously employed to irradiate specimens at 400 °C to different doses. Microstructure characterization has been conducted using high-resolution analytical transmission electron microscopy (TEM). The TEM results show that simultaneous helium injection has significant influence on irradiation-induced microstructural changes. The disordering of γ‧ (Ni3 (Al, Ti)) precipitates shows noticeable delay in dose level compared to mono heavy ion irradiation, which is attributed to the effect of helium on promoting the dynamic reordering process. In contrast to previous studies on single-beam ion irradiation, in which no cavities were reported even at high doses, very small (2-5 nm) cavities were detected after irradiation to 5 dpa, which proved that helium plays crucial role in cavity formation. TEM characterization also indicates that the helium implantation affects the development of dislocation loops during irradiation. Large 1/3 <1 1 1> Frank loops in the size of 10-20 nm developed during irradiation at 400 °C, whereas similar big loops detected at higher irradiation temperature (500 °C) during sole ion irradiation. This implies that the effect of helium on trapping the vacancies can help to develop the interstitial Frank loops at lower irradiation temperatures.

  19. The Role of Side Arcing in the Global Energy Partition during Vacuum Arc Remelting of INCONEL 718

    NASA Astrophysics Data System (ADS)

    Shevchenko, D. M.; Ward, R. M.

    2009-06-01

    The energy flows during vacuum arc remelting (VAR) of a 20-in.-diameter ingot of INCONEL 718 have been investigated experimentally, numerically, and theoretically, and the results are compared and discussed. The temperatures at a number of points on the outer surface of a VAR crucible were measured during a melt. A forward heat-flow model was constructed and the (initially unknown) interior heat flux distribution refined iteratively until the predicted crucible temperatures matched the measurements. The model included radial and vertical heat flow within the crucible and the development of a heated cooling water layer near the outer surface of the crucible. Significantly, it is shown that the temperature difference between the crucible outer surface and the bulk cooling water was not a linear function of the heat flux at the crucible inner surface. It is shown that results from the literature of plasma physics can be used to place bounds upon the partition of energy during VAR. These bounds are combined with the numerically-inferred power distribution within the crucible to estimate the position of the ingot top during the experiment and, hence, the overall energy partition. Side-arcing from the electrode to the crucible is shown to be predicted to transfer more energy to the crucible than has previously been expected. Time variation in the measured crucible outer surface temperature was also investigated as a means to estimate the ingot top position, and the results are compared with those from numerical modeling and plasma physics arguments. It is shown that the two methods are in fairly good agreement, but that they are in contrast with some aspects of results reported previously.

  20. Effects of Heat Treatment on the Ballistic Impact Properties of Inconel 718 for Jet Engine Fan Containment Applications

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Lerch, Bradley A.

    2000-01-01

    The effects of heat treating Inconel 718 on the ballistic impact response and failure mechanisms were studied. Two different annealing conditions and an aged condition were considered. Large differences in the static properties were found between the annealed and the aged material, with the annealed condition having lower strength and hardness and greater elongation than the aged. Correspondingly large differences were found in the velocity required to penetrate material in the two conditions in impact tests involving 12.5 mm diameter, 25.4 mm long cylindrical Ti-6-4 projectiles impacting flat plates at velocities in the range of 150 to 300 m/sec. The annealed material was able to absorb over 25 percent more energy than the aged. This is contrary to results observed for ballistic impact response for higher velocity impacts typically encountered in military applications where it has been shown that there exists a correlation between target hardness and ballistic impact strength. Metallographic examination of impacted plates showed strong indication of failure due to adiabatic shear. In both materials localized bands of large shear deformation were apparent, and microhardness measurements indicated an increase in hardness in these bands compared to the surrounding material. These bands were more localized in the aged material than in the annealed material. In addition the annealed material underwent significantly greater overall deformation before failure. The results indicate that high elongation and better strain hardening capabilities reduce the tendency for shear to localize and result in an unstable adiabatic shear failure. This supports empirical containment design methods that relate containment thickness to the static toughness.

  1. Chemistry of glass-ceramic to metal bonding for header applications. I. Effect of treatments on Inconel 718 and Hastelloy C-276 metallic surfaces

    SciTech Connect

    Kramer, D P; Craven, S M; Schneider, R E; Moddeman, W E; Brohard, D W

    1984-02-02

    Auger electron spectroscopy and depth Auger profiling were used to study the surfaces of Inconel 718 and Hastelloy C-276. The metal surfaces were processed in the same manner as is presently being used in the manufacturing of glass-ceramic headers. At each step in the process, samples were studied with Auger spectroscopy to determine their resultant elemental surface composition and film thickness. In addition, the effect of a final plasma cleaning operation on the metal surface was examined. The results show that the type and concentration of surface species and the thickness of the surface oxides are dependent on the processing technique.

  2. Influence of tube-entrance configuration on average heat-transfer coefficients and friction factors for air flowing in an Inconel tube

    NASA Technical Reports Server (NTRS)

    Lowdermilk, Warren H; Grele, Milton D

    1950-01-01

    A heat-transfer investigation was conducted with air flowing through an electrically heated Inconel tube having either a long-approach or a right-angle-edge entrance, an inside diameter of 0.402 inch, and a length of 24 inches over a range of Reynolds numbers up to 375,000 and average inside-tube-wall temperatures up to 2000 degrees R. Good correlation of heat-transfer data was obtained for both entrances, which substantiates work previously reported. A fair correlation of friction data was obtained for both entrances. The entrance configuration had little effect on the average heat-transfer and friction coefficients.

  3. Corrosion resistance of inconel 690 to sodium carbonate, calcium carbonate, and sodium meta silicate at 900 and 1100{degrees}C

    SciTech Connect

    Imrich, K.J.

    1997-01-29

    Corrosive attack of Inconel 690 coupons was not observed following 3 day exposure tests to calcium carbonate, sodium carbonate, and sodium meta silicate at 900 {degrees}C. However, melt line attack was evident on coupons exposed to sodium meta silicate and sodium carbonate tested for 3 days at 1100 {degrees}C. In addition, intergranular attack (IGA), approximately 0.67 mils/day, was observed on the Inconel 690 coupon exposed to calcium carbonate at 1100 {degrees}C. Calcium carbonate did not completely remove the glass coating at 950 {degrees}C. In fact, it was comparable to the results obtained by exposing a glass coated coupon at 950 {degrees}C in air. Therefore, calcium carbonate is not recommended for cleaning the DWPF melter pour spout. Both sodium carbonate and sodium meta silicate appear to remove most of the glass. However, these cleaning agents will remain on the metal surface following exposure at 950 {degrees}C resulting in very rough surface and a potential for corrosive attack when heated to 1100 {degrees}C.

  4. Effects of a range of machined and ground surface finishes on the simulated reactor helium corrosion of several candidate structural materials. [Inconel MA 754

    SciTech Connect

    Thompson, L.D.

    1981-02-01

    This report discusses the corrosion behavior of several candidate reactor structural alloys in a simulated advanced high-temperature gas-cooled reactor (HTGR) environment over a range of lathe-machined and centerless-ground surface finishes. The helium environment contained 50 Pa H/sub 2//5 Pa CO/5 Pa CH/sub 4//<0.05 Pa H/sub 2/O (500 ..mu..atm H/sub 2//50 ..mu..atm CO/50 ..mu..atm CH/sub 4//<0.5 ..mu..atm H/sub 2/O) at 900/sup 0/C for a total exposure of 3000 h. The test alloys included two vacuum-cast superalloys (IN 100 and IN 713LC); a centrifugally cast austenitic alloy (HK 40); three wrought high-temperature alloys (Alloy 800H, Hastelloy X, and Inconel 617); and a nickel-base oxide-dispersion-strengthened alloy (Inconel MA 754). Surface finish variations did not affect the simulated advanced-HTGR corrosion behavior of these materials. Under these conditions, the availability of reactant gaseous impurities controls the kinetics of the observed gas-metal interactions. Variations in the near-surface activities and mobilities of reactive solute elements, such as chromium, which might be expected to be affected by changes in surface finish, do not seem to greatly influence corrosion in this simulated advanced HTGR environment. 18 figures, 4 tables.

  5. The Role of Eta Phase Formation on the Creep Strength and Ductility of INCONEL Alloy 740 t 1023 k (750 Degrees C)

    SciTech Connect

    Shingledecker, John P; Pharr, George Mathews

    2012-01-01

    INCONEL alloy 740 is an age-hardenable nickel-based superalloy proposed for advanced ultrasupercritical steam boiler applications operating at high stress and long times above 973 K (700 C), where creep will be the dominate deformation mode. During high-temperature exposure, the alloy can form eta phase platelets that many have suggested may be detrimental to creep strength and ductility. In this study, creep-rupture tests were conducted on smooth and notched bars of INCONEL alloy 740 at 1023 K (750 C) for times up to 20,000 hours. Examination of the creep-rupture life, creep ductility, failure modes, and microstructure by quantitative electron microscopy shows that a small amount of eta phase does not diminish the creep performance. Applied stress appears to have a minor effect on the precipitation of the eta phase but not its growth rate. Based on the observation that the microstructure after 20,000 hours of creep exposure has reached equilibrium in comparison to thermodynamic calculations, it is concluded that 20,000 hour creep tests are adequate for prediction of long-term creep performance.

  6. 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.

  7. The Role of Eta Phase Formation on the Creep Strength and Ductility of INCONEL Alloy 740 at 1023 K (750 °C)

    NASA Astrophysics Data System (ADS)

    Shingledecker, J. P.; Pharr, G. M.

    2012-06-01

    INCONEL alloy 740 is an age-hardenable nickel-based superalloy proposed for advanced ultrasupercritical steam boiler applications operating at high stress and long times above 973 K (700 °C), where creep will be the dominate deformation mode. During high-temperature exposure, the alloy can form eta phase platelets that many have suggested may be detrimental to creep strength and ductility. In this study, creep-rupture tests were conducted on smooth and notched bars of INCONEL alloy 740 at 1023 K (750 °C) for times up to 20,000 hours. Examination of the creep-rupture life, creep ductility, failure modes, and microstructure by quantitative electron microscopy shows that a small amount of eta phase does not diminish the creep performance. Applied stress appears to have a minor effect on the precipitation of the eta phase but not its growth rate. Based on the observation that the microstructure after 20,000 hours of creep exposure has reached equilibrium in comparison to thermodynamic calculations, it is concluded that 20,000 hour creep tests are adequate for prediction of long-term creep performance.

  8. Viscoplastic Model Development to Account for Strength Differential: Application to Aged Inconel 718 at Elevated Temperature. Degree awarded by Pennsylvania State Univ., 2000

    NASA Technical Reports Server (NTRS)

    Iyer, Saiganesh; Lerch, Brad (Technical Monitor)

    2001-01-01

    The magnitude of yield and flow stresses in aged Inconel 718 are observed to be different in tension and compression. This phenomenon, called the Strength differential (SD), contradicts the metal plasticity axiom that the second deviatoric stress invariant alone is sufficient for representing yield and flow. Apparently, at least one of the other two stress invariants is also significant. A unified viscoplastic model was developed that is able to account for the SD effect in aged Inconel 718. Building this model involved both theory and experiments. First, a general threshold function was proposed that depends on all three stress invariants and then the flow and evolution laws were developed using a potential-based thermodynamic framework. Judiciously chosen shear and axial tests were conducted to characterize the material. Shear tests involved monotonic loading, relaxation, and creep tests with different loading rates and load levels. The axial tests were tension and compression tests that resulted in sufficiently large inelastic strains. All tests were performed at 650 C. The viscoplastic material parameters were determined by optimizing the fit to the shear tests, during which the first and the third stress invariants remained zero. The threshold surface parameters were then fit to the tension and compression test data. An experimental procedure was established to quantify the effect of each stress invariant on inelastic deformation. This requires conducting tests with nonproportional three-dimensional load paths. Validation of the model was done using biaxial tests on tubular specimens of aged Inconel 718 using proportional and nonproportional axial-torsion loading. These biaxial tests also helped to determine the most appropriate form of the threshold function; that is, how to combine the stress invariants. Of the set of trial threshold functions, the ones that incorporated the third stress invariant give the best predictions. However, inclusion of the first

  9. Probabilistic material strength degradation model for Inconel 718 components subjected to high temperature, high-cycle and low-cycle mechanical fatigue, creep and thermal fatigue effects

    NASA Technical Reports Server (NTRS)

    Bast, Callie C.; Boyce, Lola

    1995-01-01

    This report presents the results of both the fifth and sixth year effort of a research program conducted for NASA-LeRC by The University of Texas at San Antonio (UTSA). The research included on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes five effects that typically reduce lifetime strength: high temperature, high-cycle mechanical fatigue, low-cycle mechanical fatigue, creep and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model's empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for five variables, namely, high temperature, high-cycle and low-cycle mechanical fatigue, creep and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using an updated version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of high-cycle mechanical fatigue, creep and thermal fatigue was performed. Then using the current version of PROMISS, entitled PROMISS94, a second sensitivity study including the effect of low-cycle mechanical fatigue, as well as, the three previous effects was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing a combination of high-cycle mechanical

  10. A preliminary mechanical property and stress corrosion evaluation of VIM-VAR work strengthened and direct aged Inconel 718 bar material

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1987-01-01

    This report presents a preliminary mechanical property and stress corrosion evaluation of double melted (vacuum induction melted (VIM), and vacuum arc remelted (VAR)), solution treated, work strengthened and direct aged Inconel 718 alloy bar (5.50 in. (13.97 cm) diameter). Two sets of tensile specimens, one direct single aged and the other direct double aged, were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 200 ksi (1378.96 MPa) and 168 ksi (1158.33 MPa), respectively, were realized at ambient temperature, for the direct double aged specimen. No failures occurred in the single or double edged longitudinal and transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test showed no mechanical property degradation.

  11. Faster methods for estimating arc centre position during VAR and results from Ti-6Al-4V and INCONEL 718 alloys

    NASA Astrophysics Data System (ADS)

    Nair, B. G.; Winter, N.; Daniel, B.; Ward, R. M.

    2016-07-01

    Direct measurement of the flow of electric current during VAR is extremely difficult due to the aggressive environment as the arc process itself controls the distribution of current. In previous studies the technique of “magnetic source tomography” was presented; this was shown to be effective but it used a computationally intensive iterative method to analyse the distribution of arc centre position. In this paper we present faster computational methods requiring less numerical optimisation to determine the centre position of a single distributed arc both numerically and experimentally. Numerical validation of the algorithms were done on models and experimental validation on measurements based on titanium and nickel alloys (Ti6Al4V and INCONEL 718). The results are used to comment on the effects of process parameters on arc behaviour during VAR.

  12. Effect of the Fine-Grained Structure on the Fatigue Properties of the Heat-Resistant Nickel-Iron Alloy Inconel 718

    NASA Astrophysics Data System (ADS)

    Mukhtarov, Sh. Kh.; Shakhov, R. V.

    2015-10-01

    It is well known that ultrafine-grained nickel alloys with average grain sizes d = 0.1-1 μm possess improved hot workability and can be used for superplastic forming or rolling. However, microstructure refinement can worsen some performance characteristics of the alloy, for example, heat-resistant or fatigue properties. In the present work, fatigue characteristics of the fine-grained alloy Inconel 718 are investigated. Ultrafine-grained alloys with average grain sizes d = 0.1-1 μm were manufactured by multiple forging with stage-by-stage deformation temperature decrease. During standard heat treatment of the alloy performed to obtain the desired properties, the γ-grain size was controlled by precipitations of δ-phase particles along the boundaries. Results of low-cycle fatigue tests of the fine-grained alloy at room and elevated temperatures are compared with the properties of the coarse-grained alloy.

  13. Effects of laser processing parameters on thermal behavior and melting/solidification mechanism during selective laser melting of TiC/Inconel 718 composites

    NASA Astrophysics Data System (ADS)

    Shi, Qimin; Gu, Dongdong; Xia, Mujian; Cao, Sainan; Rong, Ting

    2016-10-01

    A three-dimensional finite element model is proposed to study the effects of laser power and scan speed on the thermal behavior and melting/solidification mechanism during selective laser melting (SLM) of TiC/Inconel 718 powder system. The cooling time during powder delivery is taken into account to simulate the actual production process well. It shows obviously the existence of heat accumulation effect in SLM process and, the tailored set of cooling time of 10 ms during powder delivery alleviates that effectively. The maximum temperature gradient in the molten pool slightly increases from 1.30×104 °C/mm to 2.60×104 °C/mm as the laser power is increased from 75 W to 150 W. However, it is negligibly sensitive to the variation of scan speed. There is a positive corresponding relationship between the maximum rate of temperature change and processing parameters. A low laser power (75 W) or a high scan speed (300 mm/s) is more energy efficient in Z-direction of the molten pool, giving rise to a deep-narrow cross section of the pool. Whereas, a high laser power (150 W) or a low scan speed (50 mm/s) causes a shallow-wide cross section of the molten pool, meaning it is more energy efficient in the Y-direction of the melt. The combination of a laser power of 125 W and a scan speed of 100 mm/s contributes to achieve a sound metallurgical bonding between the neighbor layers and tracks, due to the proper molten pool size (width: 109.3 μm; length: 120.7 μm; depth: 67.8 μm). The SLM experiments on TiC/Inconel 718 powder system are performed to verify the reliability and accuracy of the physical model and, simulation results are proved to be correct.

  14. An in-situ investigation of the passive film on stainless steel and Inconel 600 in high temperature, pressurized, impurity containing water

    NASA Astrophysics Data System (ADS)

    Mintz, Todd Samuel

    2003-08-01

    An in situ investigation of the films that formed on stainless steel and Inconel 600 at 288°C and 1500psi were performed using Surface Enhanced Raman Spectroscopy (SERS). By examining the changes in the films that formed on these materials, information was obtained about how these films affect the Intergranular Stress Corrosion Cracking (IGSCC) of these two metals. Stainless steel was examined in water with dilute amounts of sulfate added, which is known to enhance IGSCC. It was observed that the addition of sulfates in no way affected the films that formed on the stainless steel. The enhanced susceptibility for IGSCC of stainless steel is due to an increase in the conductivity of the water. The increased conductivity, due to the added sulfate, reduced the potential drop down a crack, so the minimum concentration of oxygen required to cause IGSCC is less than in high purity water. Thus, the sulfate additions led to an enhancement in the IGSCC. Incone1 600 was studied in boron and lithium containing solution at 288°C. The results showed that in the corrosion potential region where IGSCC occurs, an M3O4 oxide enriched in chromium was stable. This suggested that the M3O4 was the deleterious film that enhanced SCC in the Inconel 600. Once the potential was increased above the SCC region, NiO formed, which must counteract the effects of the chromium enriched M3O4. The results from this study suggested that there is a correlation between film formation and SCC susceptibility.

  15. Heat transfer from high-temperature surfaces to fluids II : correlation of heat-transfer and friction data for air flowing in inconel tube with rounded entrance

    NASA Technical Reports Server (NTRS)

    Lowdermilk, Warren H; Grele, Milton D

    1949-01-01

    A heat transfer investigation, which was an extension of a previously reported NACA investigation, was conducted with air flowing through an electrically heated inconel tube with a rounded entrance,an inside diameter of 0.402 inch, and a length of 24 inches over a range of conditions, which included Reynolds numbers up to 500,000, average surface temperatures up to 2050 degrees R, and heat-flux densities up to 150,000 Btu per hour per square foot. Conventional methods of correlating heat-transfer data wherein properties of the air were evaluated at the average bulk, film, and surface temperatures resulted in reductions of Nusselt number of about 38, 46, and 53 percent, respectively, for an increase in surface temperature from 605 degrees to 2050 degrees R at constant Reynolds number. A modified correlation method in which the properties of air were based on the surface temperature and the Reynolds number was modified by substituting the product of the density at the inside tube wall and the bulk velocity for the conventional mass flow per unit cross-sectional area, resulted in a satisfactory correlation of the data for the extended ranges of conditions investigated.

  16. Effect of boron on the low-cycle fatigue behavior and deformation structure of INCONEL 718 at 650 °C

    NASA Astrophysics Data System (ADS)

    Xiao, L.; Chaturvedi, M. C.; Chen, D. L.

    2004-11-01

    Symmetrical push-pull low-cycle fatigue (LCF) tests were performed on INCONEL 718 (IN718) containing 12, 29, 60, and 100 ppm B at 650 °C. The results showed that all the alloys experienced a relatively short period of initial cyclic hardening at low strain amplitudes, followed by a regime of saturation or slightly continuous cyclic softening. The initial cyclic hardening phase decreased with increasing strain amplitudes, and disappeared at the high strain amplitudes. A serrated flow was observed in the plastic regions of cyclic stress-strain hysteresis loops. The saturated cyclic stress amplitude at a given strain amplitude was highest for the alloy with 60 ppm B, and lowest for the alloy with 12 ppm B. The LCF lifetime increased with increasing B concentration up to 60 ppm, and then decreased as the B content increased from 60 to 100 ppm. Fractographic analysis suggested that the fracture mode changed from intergranular to transgranular cracking as the B concentration increased. The characteristic deformation microstructures produced by LCF tests at 650 °C, examined via transmission electron microscopy, were regularly spaced arrays of planar deformation bands on {111} slip planes in all four alloys. A ladderlike structure was observed in some local regions in the alloy with 12 ppm B. Heavily deformed planar deformation bands were observed in the fatigued specimens with 100 ppm B. The mechanism of improvement in the LCF life of IN718 due to B addition is discussed.

  17. A mechanical property and stress corrosion evaluation of VIM-ESR-VAR work strengthened and direct double aged Inconel 718 bar material

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1986-01-01

    Presented are the mechanical properties and the stress corrosion resistance of triple melted vacuum induction melted (VIM), electro-slag remelted (ESR), and vacuum arc remelted (VAR), solution treated, work strengthened and direct double aged Inconel 718 alloy bars 4.00 in. (10.16) and 5.75 in. (14.60 cm) diameter. Tensile, charpy v-notched impact, and compact tension specimens were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 220 ksi (1516.85 MPa) and 200 ksi (1378.00 MPa) respectively, were realized at ambient temperature. Additional charpy impact and compact tension tests were performed at -100 F (-73 C). Longitudinal charpy impact strength equalled or exceeded 12.0 ft-lbs (16.3 Joules) at ambient and at -100 F(-73 C) while longitudinal compact (LC) tension fracture toughness strength remained above 79 ksi (86.80 MPa) at ambient and at -100 F(-73 C) temperatures. No failures occurred in the longitudinal or transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test indicated no mechanical property degradation.

  18. 2012 eddy current benchmark modeling of impedance variation in coil due to a thin longitudinal through-wall notch in an inconel 600 tube

    NASA Astrophysics Data System (ADS)

    Rebello, João Marcos; Camerini, Cesar; Rocha, João Vicente; Areiza, Maria Cristina

    2013-01-01

    The 2012 Eddy Current Benchmark Problem involves the inspection of an inconel pipe using an internal pancake coil situated with its axis perpendicular to the axis of the pipe. The experimental data were supported by the Benchmark Eddy Current 2012, as released by the World Federation of Non Destructive Evaluation Centers (WFNDEC). The software OPERA 3D and COMSOL were used by the authors to solve the proposed simulation problem. The simulated results were in good agreement with the experimental ones. However some simulated results exhibited a small variation in the impedance and electrical resistance between the base material and the region around the notch. The values of these changes were plotted as a function of the displacement of the sensor over the notch region. The calculations were made for frequencies of 25kHz to 200kHz. A good agreement was obtained at low frequency. However, the simulation at high frequencies presented differences, which can be attributed to the mesh refinement. The finite elements in both software should be adjusted to two regions: the change of the small notch region and its neighborhood. It is important to adjust the mesh size parameter to compensate the low skin depth inherent to eddy current testing at high frequencies.

  19. Studies of Microtexture and Its Effect on Tensile and High-Cycle Fatigue Properties of Laser-Powder-Deposited INCONEL 718

    NASA Astrophysics Data System (ADS)

    Qi, Huan; Azer, Magdi; Deal, Andrew

    2012-11-01

    The current work studies the microstructure, texture, and mechanical properties of INCONEL 718 alloy (IN718) produced by laser direct metal deposition. The grain microstructure exhibits an alternative distribution of banded fine and coarse grain zones as a result of the rastering scanning pattern. The effects of the anisotropic crystallographic texture on the tensile and high-cycle fatigue (HCF) properties at room temperature are investigated. Tensile test results showed that the tensile strength of laser-deposited IN718 after direct aging or solution heat treatment is equivalent to the minimum-forged IN718 properties. The transverse direction (relative to the laser scanning direction) produces >10 pct stiffer modulus of elasticity but 3 to 6 pct less tensile strength compared to the longitudinal direction due to the preferential alignment of grains having <111> and <100> directions parallel to the tensile loading direction. Laser-deposited IN718 with good metallurgical integrity showed equivalent HCF properties compared to the direct-aged wrought IN718, which can be attributed to the banded grain size variation and cyclic change of inclining grain orientations resulted from alternating rastering deposition path.

  20. Imaging and characterization of γ′ and γ″ nanoparticles in Inconel 718 by EDX elemental mapping and FIB–SEM tomography

    SciTech Connect

    Kulawik, K.; Buffat, P.A.; Kruk, A.; Wusatowska-Sarnek, A.M.; Czyrska-Filemonowicz, A.

    2015-02-15

    Microstructural characterization of Inconel 718 superalloy after three different heat treatment variants was performed by electron microscopy and electron tomography techniques, taking advantage of recent development in quantitative electron microscopy. Distribution maps of the chemical elements, collected by ChemiSTEM™ EDX system, offer a clear contrast between γ′, γ″, and the γ matrix. It was found that the γ′ phase contains mainly Ni, Al, and Ti, while the γ″ phase contains Ni, Nb, and Ti. Thus application of the Al and Nb STEM–EDX elemental maps enables identification and size measurements of γ′ and γ″ nanoparticles. 3D morphology of γ′ and γ″ precipitates was examined by electron microscopy and FIB–SEM tomography. Employed methods revealed that in all three heat treatment variants the γ′ particles are almost spheroidal while the γ″ precipitates are mainly elongated-disc shaped. However, the precipitate sizes differed for each variant contributing to differences in the yield strength. Tomographic images were used for estimation of the volume fraction of the both strengthening phases. - Highlights: • ChemiSTEM™ EDX elemental maps bring a fast mean to differentiate γ′ and γ″ particles. • Such maps enable for the explicit size measurements of γ′ and γ″ nanoparticles. • Explicit γ′ and γ″ phases total volume fraction was measured employing FIB–SEM. • γ′/γ″ co-precipitates and sandwich-like γ′/γ″/γ′ particles were present. • HRSTEM-HAADF imaging revealed atomic columns of the γ′/γ″ co-precipitates.

  1. Glass ceramic seals to inconel

    DOEpatents

    McCollister, Howard L.; Reed, Scott T.

    1983-11-08

    A glass ceramic composition prepared by subjecting a glass composition comprising, by weight, 65-80% SiO.sub.2, 8-16%, Li.sub.2 O, 2-8% , Al.sub.2 O.sub.3, 1-8% K.sub.2 O, 1-5% P.sub.2 O.sub.5 and 1.5-7% B.sub.2 O.sub.3, to the following processing steps of heating the glass composition to a temperature sufficient to crystallize lithium metasilicate therein, holding the glass composition at a temperature and for a time period sufficient to dissolve the lithium metasilicate therein thereby creating cristobalite nucleii, cooling the glass composition and maintaining the composition at a temperature and for a time period sufficient to recrystallize lithium metasilicate therein, and thermally treating the glass composition at a temperature and for a time period sufficient to cause growth of cristobalite and further crystallization of lithium metasilicate producing a glass ceramic composition having a specific thermal expansion coefficient and products containing said composition.

  2. Materials corrosion and mitigation strategies for APT, end of FY `97 report: Inconel 718 in-beam corrosion rates from the `97 A6 irradiation

    SciTech Connect

    Lillard, R.S.; Pile, D.L.; Butt, D.P.

    1998-08-01

    This report summarizes the results from the 1997 irradiation of the corrosion insert at the LANSCE A6 Target Station. It addresses the corrosion measurements made on the in-beam Inconel 718 probe only. To simulate the environment that materials may be exposed to in a spallation neutron target/blanket cooling loops, samples were irradiated by the proton beam at the A6 Target Station of the Los Alamos Neutron Scattering Center (LANSCE). EIS measurements have demonstrated that the polarization resistance of IN718 decreases from approximately 3 x 10{sup 5} ohms prior to irradiation to approximately 1,000 ohms during irradiation at a proton beam current of 400 {micro}A. From the polarization resistance measurements, corrosion rate as a function of beam current was calculated for several different scenarios of beam/sample interaction. As the beam spot was small relative to the size of the IN718 corrosion probe (2{sigma} = 3 cm vs. 1.3 cm diam. x 15.9 cm length respectively), The first method for calculating corrosion rate used beam profile as a criterion for the area of highest damage. The beam spot intensity profile at LANSCE has been characterized and found to be a Gaussian distribution rotated about a central axis. From this relationship, and R{sub p} as a function of beam current, corrosion rate as a function of radial distance from the center of the beam was calculated for each beam current. Physical evidence from change in thickness measurements made on tungsten rods irradiated at 1 mA during the FY 96 irradiation period suggest that this Gaussian damage profile is an accurate depiction of beam/sample interaction. From this method the corrosion rate of IN718 during irradiation at a beam current of 1.0 mA is calculated to be approximately 0.002 inches per yr (2 mpy). The second method assumed that the predominant contributor to the corrosion current comes from an area defined by 2{sigma}. Further, the method assumed that the corrosion rate was uniform over this area

  3. Probabilistic material strength degradation model for Inconel 718 components subjected to high temperature, high-cycle and low-cycle mechanical fatigue, creep and thermal fatigue effects. Final technical report, June 1992-January 1995

    SciTech Connect

    Bast, C.C.; Boyce, L.

    1995-01-01

    This report presents the results of both the fifth and sixth year effort of a research program conducted for NASA-LeRC by The University of Texas at San Antonio (UTSA). The research included on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes five effects that typically reduce lifetime strength: high temperature, high-cycle mechanical fatigue, low-cycle mechanical fatigue, creep and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model`s empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for five variables, namely, high temperature, high-cycle and low-cycle mechanical fatigue, creep and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using an updated version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of high-cycle mechanical fatigue, creep and thermal fatigue was performed. Then using the current version of PROMISS, entitled PROMISS94, a second sensitivity study including the effect of low-cycle mechanical fatigue, as well as, the three previous effects was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect.

  4. Prediction of rupture lifetime in thin sections of a nickel base superalloy

    SciTech Connect

    Pandey, M.C. ); Taplin, D.M.R. . School of Manufacturing, Materials and Mechanical Engineering)

    1994-09-15

    The prediction of rupture lifetime of a component can be based on the data generated from round, flat and tubular specimens. An investigation on the influence of specimen geometry on the creep behavior of Inconel alloy X-750 showed that the tubular specimen exhibited better creep performance when rupture lifetime data were compared on the basis of section size. However, the time to rupture data of all three specimen geometries merged together when compared on the basis of the volume to surface area ratio (V/S) indicating that there is a definite relationship between V/S and the rupture lifetime. This analysis is now extended in another gamma prime strengthened nickel base superalloy. The chemical composition of the alloy in wt%, is as follows: 0.07C-0.66Si-0.07Cu-0.79Fe-19.1Cr-2.35Ti-1.52Al and remainder nickel. Analysis of the rupture lifetime data of a gamma prime strengthened nickel base superalloy shows that time-to-rupture is controlled by the volume to surface area ratio. Furthermore, the normalization of the volume to surface area ratio with the grain size shows that the time-to-rupture data of two grain sizes, 55 and 250 [mu]m, can be represented by a single curve.

  5. Experience at the Los Alamos Meson Physics Facility with the use of alloy Inconel 718 as an enclosure for a beam degrader and as a proton beam entry window

    NASA Astrophysics Data System (ADS)

    Sommer, W. F.; Ferguson, P. D.; Brown, R. D.; Cedillo, C. M.; Zimmerman, E.

    Operation of the Los Alamos Meson Physics Facility (LAMPF) began in 1972 and continues at present. An injector delivers protons to a 0.8 km long line ar accelerator which produces a particle energy of 800 MeV; the protons are then transported to a variety of experimental areas. The proton beam is transported in a vacuum tube, controlled and bent by electromagnets. The highest intensity beam, at a maximum level of 1 mA, is delivered to the experimental area designated as Area A. At the end of the experimental area, the beam is transported through an interface between beamline vacuum and one atmosphere air pressure. This interface is made of metal and is generally referred to as a beam entry window. At LAMPF, after the beam has exited the vacuum tube, it becomes incident on a number of experiments or 'targets.' These include capsules for radiation damage studies, a beam 'degrader' for the long-term neutrino experiment, and as many nine targets in the Isotope Production (IP) stringer system used to produce medically significant isotopes. Following the IP system is a beam stop used for the purpose its name implies. The beam stop also contains a beam entry window, whose purpose is to separate the 250 psig water cooling environment from 1 atmosphere of air. The beam entry window, the beam degrader, and the beam stop window are made of alloy Inconel 718, have endured a lengthy irradiation service time at LAMPF, and are the subject of this report.

  6. Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

    SciTech Connect

    Bajaj, R.; Mills, W.J.; Kammenzind, B.F.; Burke, M.G.

    1999-07-01

    This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x10{sup 20} n/cm{sup 2} at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranular failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed.

  7. Microstructure and stability of melt spun INCONEL 713 LC

    NASA Technical Reports Server (NTRS)

    Antolovich, S. D.; Bowman, R. R.

    1986-01-01

    The alloy IN-714LC was used in an investigation of the effect of process parameters on the microstructure of a rapidly solidified melt-spun material. The resultant ribbon microstructure consisted of several distinct regions, each of which corresponds to a different thermal history during processing. A chill zone of equiaxed randomly-oriented grains exists in a region of the foil which was in contact with the wheel during casting. This zone develops into a dendritic growth morphology with distance away from the lower ribbon surface. Dendrites inclined in the direction of wheel rotation result from growth into a flowing stream. TEM studies showed that a cell structure formed, the cell size decreasing with increasing wheel speed. Aging studies indicated that the cell structure plays an important role in gamma prime precipitation. Results relating to heat treatments (as would be encountered in compaction and use) and the stability of the melt-spun structure are considered.

  8. Deformation and fracture characteristics for irradiated Inconel X-750

    SciTech Connect

    Mills, W.J.; Mastel, B.

    1986-04-01

    Fast neutron irradiation to total fluences ranging from 7.7 x 10/sup 21/ to 5.7 x 10/sup 22/ n/cm/sup 2/ (3 to 16 dpa) resulted in a 65% increase in yield strength and a four-fold reduction in ductility. Intergranular fracture was the dominant failure mode for the irradiated material, whereas equal amounts of intergranular and transgranular cracking were found in the unirradiated condition. This fracture mechanism transition resulted from intense heterogeneous deformation in a matrix strengthened by an irradiation-produced dislocation substructure. Planar slip bands impinged on the grain boundaries causing very high local stresses. Intergranular cracking resulted because the hardened matrix prevented relaxation of the stress concentrations.

  9. Analysis of laser beam weldability of Inconel 738 superalloy

    SciTech Connect

    Egbewande, A.T.; Buckson, R.A.; Ojo, O.A.

    2010-05-15

    The susceptibility of pre-weld heat treated laser beam welded IN 738 superalloy to heat affected zone (HAZ) cracking was studied. A pre-weld heat treatment that produced the minimal grain boundary liquation resulted in a higher level of cracking compared to those with more intergranular liquation. This deviation from the general expectation of influence of intergranular liquation extent on HAZ microfissuring is attributable to the reduction in the ability of the base alloy to accommodate welding tensile stress that accompanied a pre-weld heat treatment condition designed to minimize intergranular liquation. Furthermore, in contrast to what has been generally reported in other nickel-based superalloys, a decrease in laser welding speed resulted in increased HAZ cracking in the IN 738, which can be attributed to exacerbated process instability at lower welding speeds.

  10. Hot Corrosion of Inconel 625 Overlay Weld Cladding in Smelting Off-Gas Environment

    NASA Astrophysics Data System (ADS)

    Mohammadi Zahrani, E.; Alfantazi, A. M.

    2013-10-01

    Degradation mechanisms and hot corrosion behavior of weld overlay alloy 625 were studied. Phase structure, morphology, thermal behavior, and chemical composition of deposited salt mixture on the weld overlay were characterized utilizing XRD, SEM/EDX, DTA, and ICP/OES, respectively. Dilution level of Fe in the weldment, dendritic structure, and degradation mechanisms of the weld were investigated. A molten phase formed on the weld layer at the operating temperature range of the boiler, which led to the hot corrosion attack in the water wall and the ultimate failure. Open circuit potential and weight-loss measurements and potentiodynamic polarization were carried out to study the hot corrosion behavior of the weld in the simulated molten salt medium at 873 K, 973 K, and 1073 K (600 °C, 700 °C, and 800 °C). Internal oxidation and sulfidation plus pitting corrosion were identified as the main hot corrosion mechanisms in the weld and boiler tubes. The presence of a significant amount of Fe made the dendritic structure of the weld susceptible to preferential corrosion. Preferentially corroded (Mo, Nb)-depleted dendrite cores acted as potential sites for crack initiation from the surface layer. The penetration of the molten phase into the cracks accelerated the cracks' propagation mainly through the dendrite cores and further crack branching/widening.

  11. Improvement in Laser Weldability of INCONEL 738 Superalloy through Microstructural Modification

    NASA Astrophysics Data System (ADS)

    Egbewande, A. T.; Zhang, H. R.; Sidhu, R. K.; Ojo, O. A.

    2009-11-01

    Microstructural study of laser-beam-welded IN 738 superalloy was carefully performed to better understand the causes of heat-affected zone (HAZ) cracking and to determine an improved approach of alleviating the weldability problem. The HAZ cracks in the alloy were intergranular liquation cracks that resulted from the liquation reaction of both secondary solidification products (MC carbides and γ- γ' eutectic) and solid-state reaction products ( γ' particles) present in the preweld material. In contrast to the expectation based on Chadwick’s equation, a reduction of grain boundary liquid film thickness did not produce a decrease in HAZ cracking owing to increased base alloy hardness that accompanied a preweld heat treatment designed to reduce the intergranular liquation. Moreover, a major factor limiting the effectiveness of an existing preweld heat treatment with low base alloy hardness in reducing HAZ cracking was found to be the formation of intergranular M5B3 boride particles during the heat treatment. These borides can widen the HAZ brittle temperature range (BTR) during weld cooling and increase the propensity for cracking. Based on the results, a new preweld heat treatment that induces a moderate hardness and precludes grain boundary boride formation was found and was shown to produce a significant reduction in HAZ cracking in the welded alloy compared to the most effective pre-existing preweld heat treatment.

  12. Extremely short impulse eddy current system for titanium and inconel samples testing

    SciTech Connect

    Chady, T.; Frankowski, P.

    2011-06-23

    This paper presents a new system for eddy current testing. The system enables tests with very short current impulses. Therefore, the frequency spectrum of the excitation signal is very wide. In this paper, a study of eddy current differential transducer for testing titanium element is also presented.

  13. Influence of composition on precipitation behavior and stress rupture properties in INCONEL RTM740 series superalloys

    NASA Astrophysics Data System (ADS)

    Casias, Andrea M.

    Increasing demands for energy efficiency and reduction in CO2 emissions have led to the development of advanced ultra-supercritical (AUSC) boilers. These boilers operate at temperatures of 760 °C and pressures of 35 MPa, providing efficiencies close to 50 pct. However, austenitic stainless steels typically used in boiler applications do not have sufficient creep or oxidation resistance. For this reason, nickel (Ni)-based superalloys, such as IN740, have been identified as potential materials for AUSC boiler tube components. However, IN740 is susceptible to heat-affected-zone liquation cracking in the base metal of heavy section weldments. To improve weldability, IN740H was developed. However, IN740H has lower stress rupture ductility compared to IN740. For this reason, two IN740H modifications have been produced by lowering carbon content and increasing boron content. In this study, IN740, IN740H, and the two modified IN740H alloys (modified 1 and 2) were produced with equiaxed grain sizes of 90 ìm (alloys IN740, IN740H, and IN740H modified 1 alloys) and 112 µm (IN740H modified 2 alloy). An aging study was performed at 800 °C on all alloys for 1, 3, 10, and 30 hours to assess precipitation behavior. Stress rupture tests were performed at 760 °C with the goal of attaining stress levels that would yield rupture at 1000 hours. The percent reduction in area was measured after failure as a measure of creep ductility. Light optical, scanning electron, and transmission electron microscopy were used in conjunction with X-ray diffraction to examine precipitation behavior of annealed, aged, and stress rupture tested samples. The amount and type of precipitation that occurred during aging prior to stress rupture testing or in-situ during stress rupture testing influenced damage development, stress rupture life, and ductility. In terms of stress rupture life, IN740H modified 2 performed the best followed by IN740H modified 1 and IN740, which performed similarly, and IN740H. In terms of stress rupture ductility, IN740H modified 1 performed the best, followed by IN740H modified 2, IN740, and IN740H. G-phase, η, M23C 6, and MX precipitated in IN740 during stress rupture testing. IN740H and the two modified alloys displayed M23C6 precipitates that were often in lamellar form and blocky MX precipitates. However, IN740H displayed more extensive formation of lamellar precipitates along grain boundaries after both aging and during stress rupture testing, which negatively influenced stress rupture life and ductility. Grain size was also shown to influence stress rupture life and ductility; a larger grain size increased stress rupture life, but decreased ductility as shown by the IN740H modified 1 and 2 alloy results. Transmission electron microscopy analysis was performed to assess the lamellar precipitation in IN740H. These precipitates were identified to be Cr-rich M23C6 that form by discontinuous cellular precipitation (DCP). The M23C6 precipitates were found to adopt different {111} habit planes based on the conditions of DCP boundary migration. Discontinuous precipitation of lamellar M23C6 is harmful to stress rupture life and ductility.

  14. Creep and stress rupture of oxide dispersion strengthened mechanically alloyed Inconel alloy MA 754

    NASA Technical Reports Server (NTRS)

    Howson, T. E.; Tien, J. K.; Stulga, J. E.

    1980-01-01

    The creep and stress rupture behavior of the mechanically alloyed oxide dispersion strengthened nickel-base alloy MA 754 was studied at 760, 982 and 1093 C. Tensile specimens with a fine, highly elongated grain structure, oriented parallel and perpendicular to the longitudinal grain direction were tested at various stresses in air under constant load. It was found that the apparent stress dependence was large, with power law exponents ranging from 19 to 33 over the temperature range studied. The creep activation energy, after correction for the temperature dependence of the elastic modulus, was close to but slightly larger than the activation energy for self diffusion. Rupture was intergranular and the rupture ductility as measured by percentage elongation was generally low, with values ranging from 0.5 to 16 pct. The creep properties are rationalized by describing the creep rates in terms of an effective stress which is the applied stress minus a resisting stress consistent with the alloy microstructure. Values of the resisting stress obtained through a curve fitting procedure are found to be close to the values of the particle by-pass stress for this oxide dispersion strengthened alloy, as calculated from the measured oxide particle distribution.

  15. Microstructural evolution during transient liquid phase bonding of Inconel 738LC using AMS 4777 filler alloy

    SciTech Connect

    Jalilvand, V.; Omidvar, H.; Shakeri, H.R.; Rahimipour, M.R.

    2013-01-15

    IN-738LC nickel-based superalloy was joined by transient liquid phase diffusion bonding using AMS 4777 filler alloy. The bonding process was carried out at 1050 Degree-Sign C under vacuum atmosphere for various hold times. Microstructures of the joints were studied by optical and scanning electron microscopy. Continuous centerline eutectic phases, characterized as nickel-rich boride, chromium-rich boride and nickel-rich silicide were observed at the bonds with incomplete isothermal solidification. In addition to the centerline eutectic products, precipitation of boron-rich particles was observed in the diffusion affected zone. The results showed that, as the bonding time was increased to 75 min, the width of the eutectic zone was completely removed and the joint was isothermally solidified. Homogenization of isothermally solidified joints at 1120 Degree-Sign C for 300 min resulted in the elimination of intermetallic phases formed at the diffusion affected zone and the formation of significant {gamma} Prime precipitates in the joint region. - Highlights: Black-Right-Pointing-Pointer TLP bonding of IN-738LC superalloy was performed using AMS 4777 filler alloy. Black-Right-Pointing-Pointer Insufficient diffusion time resulted in the formation of eutectic product. Black-Right-Pointing-Pointer Precipitation of B-rich particles was observed within the DAZ. Black-Right-Pointing-Pointer The extent of isothermal solidification increased with increasing holding time. Black-Right-Pointing-Pointer Homogenizing of joints resulted in the dissolution of DAZ intermetallics.

  16. Microstructural response to heat affected zone cracking of prewelding heat-treated Inconel 939 superalloy

    SciTech Connect

    Gonzalez, M.A.; Garza, A.

    2011-12-15

    The microstructural response to cracking in the heat-affected zone (HAZ) of a nickel-based IN 939 superalloy after prewelding heat treatments (PWHT) was investigated. The PWHT specimens showed two different microstructures: 1) spherical ordered {gamma} Prime precipitates (357-442 nm), with blocky MC and discreet M{sub 23}C{sub 6} carbides dispersed within the coarse dendrites and in the interdendritic regions; and 2) ordered {gamma} Prime precipitates in 'ogdoadically' diced cube shapes and coarse MC carbides within the dendrites and in the interdendritic regions. After being tungsten inert gas welded (TIG) applying low heat input, welding speed and using a more ductile filler alloy, specimens with microstructures consisting of spherical {gamma} Prime precipitate particles and dispersed discreet MC carbides along the grain boundaries, displayed a considerably improved weldability due to a strong reduction of the intergranular HAZ cracking associated with the liquation microfissuring phenomena. - Highlights: Black-Right-Pointing-Pointer Homogeneous microstructures of {gamma} Prime spheroids and discreet MC carbides of Ni base superalloys through preweld heat treatments. Black-Right-Pointing-Pointer {gamma} Prime spheroids and discreet MC carbides reduce the intergranular HAZ liquation and microfissuring of Nickel base superalloys. Black-Right-Pointing-Pointer Microstructure {gamma} Prime spheroids and discreet blocky type MC carbides, capable to relax the stress generated during weld cooling. Black-Right-Pointing-Pointer Low welding heat input welding speeds and ductile filler alloys reduce the HAZ cracking susceptibility.

  17. Comparison of the very high cycle fatigue behaviors of INCONEL 718 with different loading frequencies

    NASA Astrophysics Data System (ADS)

    Zhang, YangYang; Duan, Zheng; Shi, HuiJi

    2013-03-01

    In order to clarify the differences of very high cycle fatigue (VHCF) behavior of nickel based superalloy IN718 with different loading frequencies, stress-controlled fatigue tests were carried out by using ultrasonic testing method (20 KHz) and rotary bending testing method (52.5 Hz), both at room temperatures, to establish stress versus cycles to failure (S-N) relationships. Results disclosed that cycles to failure at a given stress level increased with an increase of the applied frequency, i.e., the higher frequency produced an upper shift of the S-N curves. Fractographic analysis suggested that crack initiation and propagation behaviors had large differences: cracks in low-frequency tests preferentially initiated from multiple sources on the specimen surface, while in high-frequency tests, cracks mostly originated from a unique source of subsurface inclusions. Subsequently, frequency-involved modeling was proposed, based on the damage accumulation theory, which could well illustrate qualitatively those comparisons due to different loading frequencies.

  18. Characterization of Machine Variability and Progressive Heat Treatment in Selective Laser Melting of Inconel 718

    NASA Technical Reports Server (NTRS)

    Prater, Tracie; Tilson, Will; Jones, Zack

    2015-01-01

    The absence of an economy of scale in spaceflight hardware makes additive manufacturing an immensely attractive option for propulsion components. As additive manufacturing techniques are increasingly adopted by government and industry to produce propulsion hardware in human-rated systems, significant development efforts are needed to establish these methods as reliable alternatives to conventional subtractive manufacturing. One of the critical challenges facing powder bed fusion techniques in this application is variability between machines used to perform builds. Even with implementation of robust process controls, it is possible for two machines operating at identical parameters with equivalent base materials to produce specimens with slightly different material properties. The machine variability study presented here evaluates 60 specimens of identical geometry built using the same parameters. 30 samples were produced on machine 1 (M1) and the other 30 samples were built on machine 2 (M2). Each of the 30-sample sets were further subdivided into three subsets (with 10 specimens in each subset) to assess the effect of progressive heat treatment on machine variability. The three categories for post-processing were: stress relief, stress relief followed by hot isostatic press (HIP), and stress relief followed by HIP followed by heat treatment per AMS 5664. Each specimen (a round, smooth tensile) was mechanically tested per ASTM E8. Two formal statistical techniques, hypothesis testing for equivalency of means and one-way analysis of variance (ANOVA), were applied to characterize the impact of machine variability and heat treatment on six material properties: tensile stress, yield stress, modulus of elasticity, fracture elongation, and reduction of area. This work represents the type of development effort that is critical as NASA, academia, and the industrial base work collaboratively to establish a path to certification for additively manufactured parts. For future flight programs, NASA and its commercial partners will procure parts from vendors who will use a diverse range of machines to produce parts and, as such, it is essential that the AM community develop a sound understanding of the degree to which machine variability impacts material properties.

  19. Study of Material Consolidation at Higher Throughput Parameters in Selective Laser Melting of Inconel 718

    NASA Technical Reports Server (NTRS)

    Prater, Tracie

    2016-01-01

    Selective Laser Melting (SLM) is a powder bed fusion additive manufacturing process used increasingly in the aerospace industry to reduce the cost, weight, and fabrication time for complex propulsion components. SLM stands poised to revolutionize propulsion manufacturing, but there are a number of technical questions that must be addressed in order to achieve rapid, efficient fabrication and ensure adequate performance of parts manufactured using this process in safety-critical flight applications. Previous optimization studies for SLM using the Concept Laser M1 and M2 machines at NASA Marshall Space Flight Center have centered on machine default parameters. The objective of this work is to characterize the impact of higher throughput parameters (a previously unexplored region of the manufacturing operating envelope for this application) on material consolidation. In phase I of this work, density blocks were analyzed to explore the relationship between build parameters (laser power, scan speed, hatch spacing, and layer thickness) and material consolidation (assessed in terms of as-built density and porosity). Phase II additionally considers the impact of post-processing, specifically hot isostatic pressing and heat treatment, as well as deposition pattern on material consolidation in the same higher energy parameter regime considered in the phase I work. Density and microstructure represent the "first-gate" metrics for determining the adequacy of the SLM process in this parameter range and, as a critical initial indicator of material quality, will factor into a follow-on DOE that assesses the impact of these parameters on mechanical properties. This work will contribute to creating a knowledge base (understanding material behavior in all ranges of the AM equipment operating envelope) that is critical to transitioning AM from the custom low rate production sphere it currently occupies to the world of mass high rate production, where parts are fabricated at a rapid rate with confidence that they will meet or exceed all stringent functional requirements for spaceflight hardware. These studies will also provide important data on the sensitivity of material consolidation to process parameters that will inform the design and development of future flight articles using SLM.

  20. Effect of Saline Environment on LCF Behavior of Inconel 718 at 550 °C

    NASA Astrophysics Data System (ADS)

    Mahobia, G. S.; Paulose, Neeta; Sreekanth, K.; Mannan, S. L.; Sudhakar Rao, G.; Singh, Vakil

    2015-01-01

    Low-cycle fatigue behavior of alloy IN718 was studied with NaCl salt coating at 550 °C in total strain-controlled mode. Fatigue life of the salt-coated specimens was found to be drastically reduced at the lowest total strain amplitude of ±0.40%; however, fatigue life was not affected at higher strain amplitudes. In general, there was cyclic softening in both the uncoated as well as salt-coated specimens. Variation of fatigue life with plastic strain amplitude followed Coffin-Manson relationship. Reduction in fatigue life from salt coating was found to be associated with early crack initiation from the roots of corrosion pits.

  1. Reduction of tritium permeation through Inconel 718 and Incoloy 800 HT by means of natural oxides

    NASA Astrophysics Data System (ADS)

    Aiello, A.; Utili, M.; Ciampichetti, A.

    2011-10-01

    Chronical releases of tritium from the helium primary coolant into the water secondary coolant is a fundamental safety issue in the design of a fusion reactor steam generator. It is well known that the steam/water circuit of a fusion reactor would be considered not relevant from a radiological point of view, while if a strong permeation of tritium will be present it will be released together with incondensable gases in the condenser. The permeation of hydrogen isotopes through candidate steam generator materials in different conditions was studied in the past. Further experiments demonstrated that nickel alloys of nuclear interest are always covered by a thin and adherent oxide layer able to reduce permeation of orders of magnitude. The major objective of this work is the evaluation of the permeated flux through nickel alloys, when exposed to pure hydrogen and to an oxidant gas stream, to verify the real permeability of these materials in conditions close to those foreseen in the helium side of the steam generator.

  2. The influence of microstructure on environmentally assisted cracking of alloy 718. Final report

    SciTech Connect

    Ballinger, R.

    1996-03-01

    The goal of this project was to understand the effects of microstructure on the behavior of alloy 718 in aqueous environments. To achieve this goal the microstructure and resultant environmental properties of modified heat treatments were characterized. The role of grain boundary microstructure was emphasized. The performance of alloy 718, in both conventional and modified heat treatments, is also compared to existing data for the behavior of alloy X-750 in light water reactor environments. These comparisons were made with the goal of understanding the effects of alloy microstructure on performance. Four thermal treatments were investigated. Each condition was given an identical aging treatment (720 C/8h, furnace cool, 620 C/8h) to maintain equivalent precipitation of the strengthening precipitate, {gamma}{prime}. Annealing treatments were varied to control grain boundary precipitation. Stress corrosion cracking (SCC) resistance was determined using fatigue pre-cracked, bolt loaded specimens in high purity, deaerated water at 288 C. Reduced grain boundary precipitation substantially increases resistance to SCC for both grain sizes. The ADA condition showed no evidence of SCC for the environmental conditions studied. Alloy 718 direct aged (DA) also has superior SCC resistance relative to alloy X-750, an alloy more commonly used in light water reactor applications today. In corrosion fatigue crack growth experiments in high purity, deaerated water it was found that under all conditions studied the crack path was transgranular. Alloy 718 is not susceptible to accelerated, intergranular, corrosion fatigue crack growth at temperatures near 100 C as is alloy X-750 in some thermal treatments. This is most likely due to superior resistance to hydrogen embrittlement.

  3. Quantitative analytical electron microscopy of multiphase alloys.

    PubMed

    Prybylowski, J; Ballinger, R; Elliott, C

    1989-02-01

    In this paper, we present a technique for analysis of composition gradients, using an analytical electron microscope, within the primary phase of a two-phase alloy for the case where the second-phase particle size is similar to the size of the irradiated volume. If the composition difference between the two phases is large, the detected compositional fluctuations associated with varying phase fractions may mask any underlying composition gradient of the primary phase. The analysis technique was used to determine grain boundary chromium concentration gradients in a nickel-base superalloy, alloy X-750. The technique may also be of use in other alloy systems. PMID:2709131

  4. Effect of Post Weld Heat Treatment on Cryogenic Mechanical Properties of Electron Beam Welded Cast Inconel 718

    NASA Astrophysics Data System (ADS)

    Bae, Sang-Hyun; Kwon, Soon-Il; Yoon, Joong-Geun; Lee, Je-Hyun; Do, Jeong-Hyeon; Kim, In-Soo; Choi, Baig-Gyu; Jo, Chang-Yong; Hong, Hyun-Uk

    2014-02-01

    Electron beam welding of pre-aged cast 718 produced a slender Laves phase, while welds from solutionized cast 718 exhibited a blocky Laves phase with an initial stage of δ precipitation and formation of γ'+γ″ strengtheners after post weld heat treatment (PWHT). The presence of primary strengthener and coarse Laves particles in PWHT weld may cause reduction of the micro-plastic zone ahead of a crack, leading to a significant decrease in Charpy impact toughness at 77 K (-196 °C).

  5. Determination of Yield and Flow Surfaces for Inconel 718 Under Axial-Torsional Loading at Temperatures Up to 649 C

    NASA Technical Reports Server (NTRS)

    Gil, Christopher M.

    1998-01-01

    An experimental program to determine flow surfaces has been established and implemented for solution annealed and aged IN718. The procedure involved subjecting tubular specimens to various ratios of axial-torsional stress at temperatures between 23 and 649 C and measuring strain with a biaxial extensometer. Each stress probe corresponds to a different direction in stress space, and unloading occurs when a 30 microstrain (1 micro eplison = 10(exp -6) mm/mm) offset is detected. This technique was used to map out yield loci in axial-torsional stress space. Flow surfaces were determined by post-processing the experimental data to determine the inelastic strain rate components. Surfaces of constant inelastic strain rate (SCISRS) and surfaces of constant inelastic power (SCIPS) were mapped out in the axial-shear stress plane. The von Mises yield criterion appeared to closely fit the initial loci for solutioned IN718 at 23 C. However, the initial loci for solutioned IN718 at 371 and 454 C, and all of the initial loci for aged IN718 were offset in the compression direction. Subsequent loci showed translation, distortion, and for the case of solutioned IN718, a slight cross effect. Aged IN718 showed significantly more hardening behavior than solutioned IN718.

  6. Improved corrosion resistance of Hastelloy G-30 in nitric/hydrofluoric acid solutions by welding with Inconel 72 weld wire

    SciTech Connect

    Norby, B.C.

    1992-03-03

    When welding Hastelloy G-30, secondary phases form in the weld metal. These phases cause the weld metal to be preferentially attacked in nitric acid (HN0{sub 3}) solutions contaminated with minor amounts of hydrofluoric acid (HF). A post weld solution anneal and water quench is necessary to assure that these phases redissolve into the solid. When a post weld solution anneal and water quench is not feasible, improved corrosion resistance can be obtained by welding with INCO 72 weld wire. When welding Hastelloy G-30 with INCO 72, there can be a region at the weldmetal/base-metal interface that does not benefit from the INCO 72 weld wire. This region consists of melted and resolidified Hastelloy G-30. This unmixed zone can be preferentially attacked in HN03 solutions contaminated with minor amounts of HF. Long term corrosion immersion tests have shown that the rate of attack at the weld-metal/base-metal interface can be as high as 50 mpy. Welding techniques that increase the mixing of the melted Hastelloy G-30 with the INCO 72 weld wire can reduce the interface corrosion rate.

  7. Pitting and Repair of the Space Shuttle's Inconel(Registered TradeMark) Honeycomb Conical Seal Panel

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank R.; Gentz, Steven J.; Miller, James B.; MacKay, Rebecca A.; Bright, Mark L.

    2006-01-01

    During return to flight servicing of the rudder speed brake (RSB) for each Space Shuttle Orbiter, inspectors discovered numerous small pits on the surface of the #4 right hand side honeycomb panel that covers the rudder speed brake actuators. Shortly after detection of the problem, concurrent investigations were initiated to determine the extent of damage, the root cause, and to develop a repair plan, since fabrication of a replacement panel is impractical for cost, schedule, and sourcing considerations. This paper describes the approach, findings, conclusions and recommendations associated with the investigation of the conical seal pitting. It documents the cause and contributing factors of the pitting, the means used to isolate each contributor, and the supporting evidence for the primary cause of the pitting. Finally, the selection, development and verification of the repair procedure used to restore the conical seal panel is described with supporting process and metallurgical rationale for selection.

  8. Laser cladding of Ni-Cr-Al-Hf on inconel 718 for improved high-temperature oxidation resistance

    SciTech Connect

    Singh, J.; Nagarathnam, K.; Mazumder, J.

    1987-08-03

    In-situ Ni-Cr-Al-Hf alloy was developed by laser surface cladding with a mixed-powder feed for improved high-temperature oxidation resistance. Oxidation-resistant materials for operation at elevated temperatures must satisfy two requirements: diffusion through the oxide scale must occur at the lowest possible rate, and the oxide scale must resist spallation. Formation of an Al/sub 2/O/sub 3/ protective scale fulfills the former requirement but its adherence is poor. A reactive metal such as Hf is added to improve adhesion. A 10-kW CO/sub 2/ laser was used for laser cladding. Optical, SEM and STEM microanalysis techniques were employed to characterize the different phases produced during the cladding process. Microstructural studies showed a high degree of grain refinement, increased solid solubility of Hf in the matrix and the formation of Hf-rich precipitates. A thermogravimetric analysis was carried out to determine the oxidation properties of these clad alloys with an extended solid solution of Hf. Considerable improvement over the base metal was observed. This paper discusses microstructural development in this laser-clad alloy and its effect on oxidation.

  9. An empirical-statistical model for coaxial laser cladding of NiCrAlY powder on Inconel 738 superalloy

    NASA Astrophysics Data System (ADS)

    Ansari, M.; Shoja Razavi, R.; Barekat, M.

    2016-12-01

    In this study, coaxial laser cladding of NiCrAlY powder on a nickel-based superalloy is investigated from an experimental point of view so as to propose an empirical-statistical model for the process. The correlations between main processing parameters (i.e. scanning speed, powder feeding rate, and laser power) and geometrical characteristics (i.e. width, height, penetration depth, dilution and wetting angle) of single clad tracks have been predicted and are discussed using regression analysis (RA). The validity of the predictions is confirmed by providing correlation coefficient and analysis of the residuals. The correlations are established as a combined parameter (PαVβFγ) for each studied characteristic of single clad tracks. These correlations finally lead to the design of a processing map that can be practically used to select proper processing parameters for laser cladding of the particular material.

  10. Effect of heat treatment on stress corrosion of Alloy 718 in pressurized-water-reactor primary water

    SciTech Connect

    Miglin, M.T.; Monter, J.V.; Wade, C.S.; Nelson, J.L.

    1992-12-31

    Stress corrosion cracking (SCC) tests were conducted in 360{degrees}C pressurized-water-reactor (PWR) primary water using alloy 718 in various heat treatment conditions. Alloy X-750 in the HTH condition and an experimental heat of an alloy 718 variation, Hicoroy, were also tested for comparison. Fatigue-precracked, 12.5-mm-thick compact fracture specimens were subjected to a constant extension rate of 1.3 x 10{sup {minus}9} m/s. Crack growth rate was measured during testing using a reversing DC potential drop technique. Results in the form of SCC crack growth rate versus applied stress intensity demonstrate that the SCC resistance of alloy 718 in the PWR primary-side environment can be improved by changes in heat treatment.

  11. High spatial resolution, high energy synchrotron x-ray diffraction characterization of residual strains and stresses in laser shock peened Inconel 718SPF alloy

    NASA Astrophysics Data System (ADS)

    Gill, Amrinder S.; Zhou, Zhong; Lienert, Ulrich; Almer, Jonathan; Lahrman, David F.; Mannava, S. R.; Qian, Dong; Vasudevan, Vijay K.

    2012-04-01

    Laser shock peening (LSP) is an advanced surface enhancement technique used to enhance the fatigue strength of metal parts by imparting deep compressive residual stresses. In the present study, LSP was performed on IN718 SPF alloy, a fine grained nickel-based superalloy, with three different power densities and depth resolved residual strain and stress characterization was conducted using high energy synchrotron x-ray diffraction in beam line 1-ID-C at the Advanced Photon Source at the Argonne National laboratory. A fine probe size and conical slits were used to non-destructively obtain data from specific gauge volumes in the samples, allowing for high-resolution strain measurements. The results show that LSP introduces deep compressive residual stresses and the magnitude and depth of these stresses depend on the energy density of the laser. The LSP induced residual stresses were also simulated using three-dimensional nonlinear finite element analysis, with employment of the Johnson-Cook model for describing the nonlinear materials constitutive behavior. Good agreement between the experimental and simulated data was obtained. These various results are presented and discussed.

  12. Effect of Al-Si Pack Cementation Diffusion Coating on High-Temperature Low-Cycle Fatigue Behavior of Inconel 713LC

    NASA Astrophysics Data System (ADS)

    Mansuri, Mohammadreza; Hadavi, Seyed Mohammad Mehdi; Zare, Esmail

    2016-01-01

    In this research, an Al-Si protective coating was applied on the surface of an IN713LC specimen using pack cementation method. Surface-treated and untreated specimens were exposed to low-cycle fatigue by tension-tension loading under total strain control at 1173 K (900 °C) in air. Based on the obtained results, the hardening/softening, cyclic stress-strain, and fatigue life curves were plotted and analyzed. The results showed that both the single-stage and two-stage coatings improved the fatigue life of the substrate. However, owing to more silicon content of single-stage coating compared to that of two-stage coating, the effect of single-stage coating was superior. The stress response of the treated material was lower compared with the untreated one. Observations of the specimen section and fracture surface examinations were used to analyze fatigue behavior of both coated and uncoated materials.

  13. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, High-Cycle and Low-Cycle Mechanical Fatigue, Creep and Thermal Fatigue Effects

    NASA Technical Reports Server (NTRS)

    Bast, Callie C.; Boyce, Lola

    1995-01-01

    The development of methodology for a probabilistic material strength degradation is described. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes five effects that typically reduce lifetime strength: high temperature, high-cycle mechanical fatigue, low-cycle mechanical fatigue, creep and thermal fatigue. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing predictions of high-cycle mechanical fatigue and high temperature effects with experiments are presented. Results from this limited verification study strongly supported that material degradation can be represented by randomized multifactor interaction models.

  14. A Study on the Effect of Process Parameters on the Properties of Joint in TLP-Bonded Inconel 738LC Superalloy

    NASA Astrophysics Data System (ADS)

    Jalilvand, V.; Omidvar, H.; Shakeri, H. R.; Rahimipour, M. R.

    2013-10-01

    Optimization of transient liquid phase (TLP)-bonding variables is essential to achieve a joint free from deleterious intermetallic constituents and with appropriate mechanical properties. In this study, TLP bonding of IN-738LC superalloy was performed using AMS 4777 filler metal. The influence of gap size and bonding parameters (temperature and time) was investigated on the joint microstructure and its properties. In cases where the holding time was insufficient for complete isothermal solidification, the residual liquid transformed to non-equilibrium eutectic microconstituents consisting of nickel-rich boride, chromium-rich boride, and γ solid solution phases. The eutectic width decreased with the increase of holding time and the increase in initial gap size resulted in thicker eutectic width in the samples bonded at the same temperature and for equivalent holding times. The time of complete isothermal solidification decreased with the increase in bonding temperature to 1100°C, which was consistent with the models based on the diffusion-induced solid/liquid interface motion. Microhardness and shear strength tests were used to investigate the mechanical properties of the bonds. In the bonding condition in which isothermal solidification was not accomplished completely, the eutectic constituent with the highest hardness in the bond region was the preferential failure source. The results showed that homogenized joints had the highest shear strength.

  15. Calibrating IR Cameras for In-Situ Temperature Measurement During the Electron Beam Melting Process using Inconel 718 and Ti-Al6-V4

    SciTech Connect

    Dinwiddie, Ralph Barton; Lloyd, Peter D; Dehoff, Ryan R; Lowe, Larry E

    2016-01-01

    The Department of Energy s (DOE) Manufacturing Demonstration Facility (MDF) at Oak Ridge National Laboratory (ORNL) provides world-leading capabilities in advanced manufacturing (AM) facilities which leverage previous, on-going government investments in materials science research and characterization. MDF contains systems for fabricating components with complex geometries using AM techniques (i.e. 3D-Printing). Various metal alloy printers, for example, use electron beam melting (EBM) systems for creating these components which are otherwise extremely difficult- if not impossible- to machine. ORNL has partnered with manufacturers on improving the final part quality of components and developing new materials for further advancing these devices. One method being used to study (AM) processes in more depth relies on the advanced imaging capabilities at ORNL. High performance mid-wave infrared (IR) cameras are used for in-situ process monitoring and temperature measurements. However, standard factory calibrations are insufficient due to very low transmissions of the leaded glass window required for X-ray absorption. Two techniques for temperature calibrations will be presented and compared. In-situ measurement of emittance will also be discussed. Ample information can be learned from in-situ IR process monitoring of the EBM process. Ultimately, these imaging systems have the potential for routine use for online quality assurance and feedback control.

  16. Calibrating IR cameras for in-situ temperature measurement during the electron beam melt processing of Inconel 718 and Ti-Al6-V4

    NASA Astrophysics Data System (ADS)

    Dinwiddie, R. B.; Kirka, M. M.; Lloyd, P. D.; Dehoff, R. R.; Lowe, L. E.; Marlow, G. S.

    2016-05-01

    High performance mid-wave infrared (IR) cameras are used for in-situ electron beam melt process monitoring and temperature measurements. Since standard factory calibrations are insufficient due to very low transmissions of the leaded glass window required for X-ray absorption, two techniques for temperature calibrations are compared. In-situ measurement of emittance will also be discussed. Ultimately, these imaging systems have the potential for routine use for online quality assurance and feedback control.

  17. Benefits of thread rolling process to the stress corrosion cracking and fatigue resistance of high strength fasteners

    SciTech Connect

    Kephart, A.R.; Hayden, S.Z.

    1993-05-01

    Stress corrosion cracking (SCC) behavior of cut (machined) vice thread rolled Alloy X-750 and Alloy 625 fasteners in a simulated high temperature primary water environment has been evaluated. SCC testing at 360 and 338C included 157 small and 40 large 60{degree} Vee thread studs. Thread rolled fasteners had improved resistance relative to cut fasteners. Tests of fatigue resistance in air at room temperature and both air and primary water at 315C were conducted on smaller studs with both cut and rolled threads. Results showed rolled threads can have significantly improved fatigue lives over those of cut threads in both air and primary water. Fasteners produced by two different thread rolling methods, in-feed (radial) and through-feed (axial), revealed similar SCC initiation test results. Testing of thread rolled fasteners revealed no significant SCC or fatigue growth of rolling induced thread crest laps typical of the thread rolling process. While fatigue resistance differed between the two rolled thread supplier`s studs, neither of the suppliers studs showed SCC initiation at exposure times beyond that of cut threads with SCC. In contrast to rolling at room temperature, warm rolled (427C) threads showed no improvement over cut threads in terms of fatigue resistance. The observed improved SCC and fatigue performance of rolled threads is postulated to be due to interactive factors, including beneficial residual stresses in critically stressed thread root region, reduction of plastic strains during loading and formation of favorable microstructure.

  18. Thermally activated low temperature creep and primary water stress corrosion cracking of NiCrFe alloys

    SciTech Connect

    Hall, M.M. Jr.

    1993-10-01

    A phenomenological SCC-CGR model is developed based on an apriori assumption that the SCC-CGR is controlled by low temperature creep (LTC). This mode of low temperature time dependent deformation occurs at stress levels above the athermal flow stress by a dislocation glide mechanism that is thermally activated and may be environmentally assisted. The SCC-CGR model equations developed contain thermal activation parameters descriptive of the dislocation creep mechanism. Thermal activation parameters are obtained by fitting the CGR model to SCC-CGR data obtained on Alloy 600 and Alloy X-750. These SCC-CGR activation parameters are compared to LTC activation parameters obtained from stress relaxation tests. When the high concentration of hydrogen at the tip of an SCC crack is considered, the SCC-CGR activation energies and rate sensitivities are shown to be quantitatively consistent with hydrogen reducing the activation energy and increasing the strain rate sensitivity in LTC stress relaxation tests. Stress dependence of SCC-CGR activation energy consistent with that found for the LTC activation energy. Comparisons between temperature dependence of the SCC-CGR stress sensitivity and LTC stress sensitivity provide a basis for speculation on effects of hydrogen and solute carbon on SCC crack growth rates.

  19. The Effect of Load-Line Displacement Rate on the SCC Growth Rate of Nickel Alloys and Mechanistic Implications

    SciTech Connect

    D Morton

    2005-10-19

    A key set of SCC growth experiments was designed to test the hypothesis that deformation/creep is the rate controlling step in LPSCC. These tests were performed on Alloy X-750 AH compact tension specimens at a various constant displacement rates. The deformation/creep rate within the crack tip zone is proportional to the test displacement rate. If crack growth rates were observed to increase with the load-line displacement rate, then this would indicate that deformation/creep is a critical SCC mechanism process. However, results obtained from the load-line displacement tests did not find X-750 AH SCC growth rate to be dependent on the position rate and therefore do not support the assumption that deformation/creep is the rate controlling process in LPSCC. The similarities between the SCC response of X-750, Alloy 600 and EN82H suggests that it is likely that the same SCC process is occurring for all these alloys (i.e., the same rate controlling step) and that deformation based models are also inappropriate for Alloy 600 and EN82H. The strong temperature and coolant hydrogen dependencies exhibited by these alloys make it more likely that nickel alloy LPSCC is controlled by an environmental or corrosion driven process.

  20. The Effect of pH on Nickel Alloy SCC and Corrosion Performance

    SciTech Connect

    D.S. Morton; M. Hansen

    2002-10-10

    Alloy X-750 condition HTH stress corrosion crack growth rate (SCCGR) tests have been conducted at 360 C (680 F) with 50 cc/kg hydrogen as a function of coolant pH. Results indicate no appreciable influence of pH on crack growth in the pH (at 360 C) range of {approx} 6.2 to 8.7, consistent with previous alloy 600 findings. These intermediate pH results suggest that pH is not a key variable which must be accounted for when modeling pressurized water reactor (PWR) primary water SCC. In this study, however, a nearly three fold reduction in X-750 crack growth rate was observed in reduced pH environments (pH 3.8 through HCl addition and pH 4-5.3 through H{sub 2}SO{sub 4} addition). Crack growth rates did not directly correlate with corrosion film thickness. In fact, 10x thicker corrosion films were observed in the reduced pH environments.

  1. A comparison of internal hydrogen embrittlement and hydrogen environment embrittlement of X-750

    SciTech Connect

    Symons, D.M.

    1999-12-01

    Hydrogen has been shown to degrade the mechanical properties of nickel-base alloys. This degradation occurs whether the material is in a hydrogen producing environment or if the material has dissolved hydrogen in the metal due to prior exposure to hydrogen. Materials behave differently under these two conditions. Therefore, the degradation due to hydrogen has been split into two categories, internal hydrogen embrittlement (IHE) and hydrogen environment embrittlement (HEE). IHE may be defined as the embrittlement of a material that has been charged with hydrogen prior to testing or service while HEE may be defined by the embrittlement of a material in a hydrogen environment where the hydrogen may come from gaseous hydrogen or generated from a corrosion reaction. This work will compare IHE and HEE of fracture mechanics specimens. Different fugacities of hydrogen for HEE and hydrogen concentrations for IHE were examined for Alloy X-750, a nickel-base super alloy. The test results were analyzed and the role of hydrogen in IHE and HEE was evaluated. A model based on a critical grain boundary hydrogen concentration will be proposed to describe the behavior in both HEE and IHE conditions.

  2. Relation of Engine Turbine-blade Life to Stress-rupture Properties of the Alloys, Stellite 21, Hastelloy B, Cast S-816, Forged S-816, X-40, Nimonic 80, Refractaloy 26, N-155, and Inconel X

    NASA Technical Reports Server (NTRS)

    Garrett, F B; Yaker, C

    1951-01-01

    An investigation was conducted to relate the engine performance of the heat-resistant alloys, Stellite 21, Hastelloy B, cast S-816, forged S-816, X-40, Nimonic 80, Refractory 26, N-155, and Iconel X to their stress-rupture properties. The engine test consisted of the repetition of a 20-minute cycle, 15 minutes at rated speed and approximately 5 minutes at idle. The results of the investigation indicated a direct correlation between stress-rupture life and blade life for the relatively low-strength alloys. The stress-rupture life and blade life for the relatively high-strength alloys did not correlate because of the effects of the vibratory stresses and the corrosive-gas atmosphere.

  3. Improving the Surface Properties of Inconel 718 BY Applying a CO2 Laser Heat Treatment to a High-Velocity Oxy-Fuel Coating of WC-CrCo Powder

    NASA Astrophysics Data System (ADS)

    Cho, T. Y.; Yoon, J. H.; Joo, Y. K.; Zhang, S. H.; Cho, J. Y.; Kang, J. H.; Chun, H. G.; Kwon, S. C.; Li, Ming-Xi

    A micron-sized WC-CrCo powder was coated onto an IN718 substrate using high-velocity oxy-fuel (HVOF) thermal spraying. To further improve the surface properties, the HVOF coating was heat-treated by a CO2 laser. The surface properties of both the coating and the laser-heated coating were then compared. The HVOF optimal coating process (OCP) for a coating with the highest surface hardness was determined with the Taguchi program. The friction and wear behaviors of the coating, an electrolytic hard chrome (EHC)-plated coating and IN718, were comparatively investigated via a reciprocating sliding wear test at both 25 and 450°C. The friction coefficient (FC) for all three samples decreased when the sliding surface temperature increased from 25 to 450°C. The FC of the coating decreased with increasing surface temperature: 0.33 ± 0.02 at 25°C to 0.26 ± 0.02 at 450°C the coating had the lowest FC among the three samples. At both temperatures, the coating wear depth (WD) was smaller than those of the EHC sample and IN718. At room temperature, WC-CrCo and the EHC coatings had good wear resistance and had only a shallow WD. IN718, however, had poor wear resistance with 50 μm deep grooves created from fretting corrosion that arose during the 1500 reciprocating slides (2.5 Hz, 10 min sliding wear test). At 450°C, the coating WDs were much shallower than those for the EHC coating and IN718: 0.5-μm deep grooves compared to 60-70-μm deep grooves. These results proved that the coating provided a protective coating for IN718 and other metal components. With the OCP coating fabricated from the powders on the IN718 surface, the surface hardness increased 316% from 399 Hv to 1260 Hv. Furthermore, by laser heating the coating surface for 0.6 s, the hardness increased 44% from 1260 ±30 Hv to 1820 ±100 Hv, porosity decreased more than five times from 2.2 ± 0.3% to 0.4 ± 0.1%, and the coating thickness decreased 17% from 300 to 250 μm. These results showed that both the WC-CrCo powder coating and the laser-heating improved the surface properties of IN718.

  4. Effect of fast neutron irradiation on fatigue-crack growth behavior of three nickel-base alloys

    SciTech Connect

    James, L.A.

    1981-04-01

    Nickel-base alloys are often employed in reactor structural applications where high strength, resistance to corrosion, or swelling resistance are important considerations. In this study, fatigue-crack growth rate tests were conducted at 427/degree/C on Inconel 600, Inconel X-750, and Incoloy 800 irradiated in the Experimental Breeder Reactor II to total fluences ranging between 2.5 and 6.0*10/sup 22/ n/cm/sup 2/. Following irradiation, minor increases were noted in the crack growth rates of Inconel 600, minor decreases in the growth rates of Inconel X-750, and no irradiation effect in the cracking behavior of Incoloy 800. 14 refs.

  5. Thermally activated dislocation creep model for primary water stress corrosion cracking of NiCrFe alloys

    SciTech Connect

    Hall, M.M., Jr

    1995-12-31

    There is a growing awareness that awareness that environmentally assisted creep plays an important role in integranular stress corrosion cracking (IGSCC) of NiCrFe alloys in the primary coolant water environment of a pressurized water reactor (PWR). The expected creep mechanism is the thermally activated glide of dislocations. This mode of deformation is favored by the relatively low temperature of PWR operation combined with the large residual stresses that are most often identified as responsible for the SCC failure of plant components. Stress corrosion crack growth rate (CGR) equations that properly reflect the influence of this mechanism of crack tip deformation are required for accurate component life predictions. A phenomenological IGSCC-CGR model, which is based on an apriori assumption that the IGSCC-CGR is controlled by a low temperature dislocation creep mechanism, is developed in this report. Obstacles to dislocation creep include solute atoms such as carbon, which increase the lattice friction force, and forest dislocations, which can be introduced by cold prestrain. Dislocation creep also may be environmentally assisted due to hydrogen absorption at the crack tip. The IGSCC-CGR model developed here is based on an assumption that crack growth occurs by repeated fracture events occurring within an advancing crack-tip creep-fracture zone. Thermal activation parameters for stress corrosion cracking are obtained by fitting the CGR model to IGSCC-CGR data obtained on NiCrFe alloys, Alloy X-750 and Alloy 600. These IGSCC-CGR activation parameters are compared to activation parameters obtained from creep and stress relaxation tests. Recently reported CGR data, which exhibit an activation energy that depends on yield stress and the applied stress intensity factor, are used to benchmark the model. Finally, the effects of matrix carbon concentration, grain boundary carbides and absorbed hydrogen concentration are discussed within context of the model.

  6. Aqueous electrochemistry of precipitation-hardened nickel base alloys

    SciTech Connect

    Hosoya, K.; Ballinger, R.; Prybylowski, J.; Hwang, I.S. )

    1990-11-01

    An investigation has been conducted to explore the importance of local crack tip electrochemical processes in precipitation-hardened Ni-Cr-Fe alloys driven by galvanic couples between grain boundary precipitates and the local matrix. The electrochemical behavior of {gamma}{prime} (Ni{sub 3}(Al,Ti)) has been determined as a function of titanium concentration, temperature, and solution pH. The electrochemical behavior of Ni-Cr-Fe solid solution alloys has been investigated as a function of chromium content for a series of 10 Fe-variable Cr (6--18%)-balance Ni alloys, temperature, and pH. The investigation was conducted in neutral and pH3 solutions over the temperature range 25--300{degree}C. The results of the investigation show that the electrochemical behavior of these systems is a strong function of temperature and composition. This is especially true for the {gamma}{prime} (Ni{sub 3}(Al,Ti)) system where a transition from active/passive behavior to purely active behavior and back again occurs over a narrow temperature range near 100{degree}C. Behavior of this system was also found to be a strong function of titanium concentration. In all cases, the Ni{sub 3}(Al,Ti) phase was active with respect to the matrix. The peak in activity near 100{degree}C correlates well with accelerated crack growth in this temperature range, observed in nickel-base alloy X-750 heat treated to precipitate {gamma}{prime} on the grain boundaries. 20 refs., 23 figs., 3 tabs.

  7. Prediction of PWSCC in nickel base alloys using crack growth rate models

    SciTech Connect

    Thompson, C.D.; Krasodomski, H.T.; Lewis, N.; Makar, G.L.

    1995-12-31

    The Ford/Andresen slip-dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material conditions. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip-dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip-dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxide which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.

  8. Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models

    SciTech Connect

    Thompson, C.D.; Krasodomski, H.T.; Lewis, N.; Makar, G.L.

    1995-02-22

    The Ford/Andresen slip dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material condition. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxide which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.

  9. Fatigue acceptance test limit criterion for larger diameter rolled thread fasteners

    SciTech Connect

    Kephart, A.R.

    1997-05-01

    This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process. This criterion is derived from a stress dependent, room temperature air fatigue database for test studs having a 0.625 inch diameter threads of Alloys X-750 HTH and direct aged 625. Anticipated fatigue lives of larger threads are based on thread root elastic stress concentration factors which increase with increasing thread diameters. Over the thread size range of interest, a 30% increase in notch stress is equivalent to a factor of five (5X) reduction in fatigue life. The resulting diameter dependent fatigue acceptance criterion is normalized to the aerospace rolled thread acceptance standards for a 1.0 inch diameter, 0.125 inch pitch, Unified National thread with a controlled Root radius (UNR). Testing was conducted at a stress of 50% of the minimum specified material ultimate strength, 80 Ksi, and at a stress ratio (R) of 0.10. Limited test data for fastener diameters of 1.00 to 2.25 inches are compared to the acceptance criterion. Sensitivity of fatigue life of threads to test nut geometry variables was also shown to be dependent on notch stress conditions. Bearing surface concavity of the compression nuts and thread flank contact mismatch conditions can significantly affect the fastener fatigue life. Without improved controls these conditions could potentially provide misleading acceptance data. Alternate test nut geometry features are described and implemented in the rolled thread stud specification, MIL-DTL-24789(SH), to mitigate the potential effects on fatigue acceptance data.

  10. Method for removing surface-damaged layers from nickel alloys

    NASA Technical Reports Server (NTRS)

    Fawley, R. W.

    1968-01-01

    Electrical discharge machining /EDM/ damaged layer can be effectively removed from Rene 41, Inconel 625, Inconel 718, and Monel K-500 by abrasive-grit blasting or electropolishing /at room temperature/ at a current density of 5A/inches squared in a water solution of phosphoric and sulfuric acids.

  11. Review of the data bases for making decisions regarding Trojan steam generator replacement options

    SciTech Connect

    Johnson, A.B. Jr.; Gilbert, E.R.

    1992-03-01

    The central focus for this assessment has been to compare the corrosion behavior of two steam generator (SG) tube materials: Inconel 600 TT and Inconel 690 TT from (a) SG operating experience, and (b) laboratory data. The scope and results of the comparisons are summarized in this section. They provide the basis for projecting SG longevity.

  12. Rupture Strength of Several Nickel-base Alloys in Sheet Form

    NASA Technical Reports Server (NTRS)

    Dance, James H; Clauss, Francis J

    1957-01-01

    The 100-hour rupture strengths of Inconel X, Inconel 700, Incoloy 901, Refractaloy 26, and R-235 at 1200 and 1350 F. in both the annealed and heat-treated conditions were determined. Inconel 700 had the highest rupture strength at both temperatures; Incoloy 901 was second strongest at 1200 F, and R-235 second strongest at 1350 F. With the exception of Incoloy 901, ductility was low. Photomicrographs show that fractures are through the grain boundaries. Results are compared with published data for other sheet alloys and bar stock.

  13. Undercoat prevents blistering of silver plating at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Kuster, C. A.

    1967-01-01

    Gold undercoat prevents blistering in the silver plating of Inconel 718 seals from steam at high temperatures. The undercoat is diffused into the surface of the parent metal by baking prior to silver plating.

  14. Failure Analysis of a Pilot Scale Melter

    SciTech Connect

    Imrich, K J

    2001-09-14

    Failure of the pilot-scale test melter resulted from severe overheating of the Inconel 690 jacketed molybdenum electrode. Extreme temperatures were required to melt the glass during this campaign because the feed material contained a very high waste loading.

  15. Measurement of the Nickel/Nickel Oxide Phase Transition in High Temperature Hydrogenated Water Using the Contact Electric Resistance (CER) Technique

    SciTech Connect

    S.A. Attanasio; D.S. Morton; M.A. Ando; N.F. Panayotou; C.D. Thompson

    2001-05-08

    Prior studies of Alloy 600 and Alloy X-750 have shown the existence of a maximum in stress corrosion cracking (SCC) susceptibility in high temperature water (e.g., at 360 C), when testing is conducted over a range of dissolved (i.e., aqueous) hydrogen (H{sub 2}) concentrations. It has also been shown that this maximum in SCC susceptibility tends to occur in proximity to the nickel/nickel oxide (Ni/NiO) phase transition, suggesting that oxide phase stability may affect primary water SCC (PWSCC) resistance. Previous studies have estimated the Ni/NiO transition using thermodynamic calculations based on free energies of formation for NiO and H{sub 2}O. The present study reports experimental measurements of the Ni/NiO transition performed using a contact electric resistance (CER) instrument. The CER is capable of measuring the surface resistance of a metal to determine whether it is oxide-covered or oxide-free at a given condition. The transition aqueous hydrogen (H{sub 2}) concentration corresponding to the Ni/NiO equilibrium was measured at 288, 316, 338 and 360 C using high purity Ni specimens. The results showed an appreciable deviation (i.e., 7 to 58 scc H{sub 2}/kg H{sub 2}O) between the measured Ni/NiO transition and the theoretical Ni/NiO transition previously calculated using free energy data from the Journal of Solution Chemistry. The CER-measured position of the Ni/NiO transition is in good agreement with the maxima in PWSCC susceptibility at 338 and 360 C. The measured Ni/NiO transition provides a reasonable basis for estimating the aqueous H{sub 2} level at which the maximum in SCC susceptibility is likely to be observed at temperatures lower than 338 to 360 C, at which SCC tests are time-consuming to perform. Limited SCC data are presented which are consistent with the observation that SCC susceptibility is maximized near the Ni/NiO transition at 288 C.

  16. Materials compatibility with the volcanic environment. Final report

    SciTech Connect

    Htun, K.M.

    1984-03-08

    Attempts were made to run materials compatibility, volcanic gas collection, and heat transfer experiments during the 1977 Kilauea eruption. Preliminary results from the recovered samples showed that Fe, Ni, and Fe-Ni alloys were the most heavily oxidized. The Mo and W alloys showed some attack and only neglible reaction was seen on 310 stainless, Hastelloy C, Inconel 600, Inconel 718, Rene 41, and Nichrome. Results are qualitative only. (DLC)

  17. Effect of magnesium oxide content on oxidation behavior of some superalloy-base cermets

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1975-01-01

    The effect of increasing magnesium oxide (MgO) content on the cyclic oxidation resistance of hot-pressed cermets of MgO in NiCrAlY, MgO in Hoskins-875, MgO in Inconel-702, and MgO in Hastelloy-X was investigated. The cermets with magnesium oxide levels of 5, 10, 20, and 40 vol percent were examined. The cyclic oxidation behavior of these cermets at 1100 and 1200 C in still air was determined by a thermogravimetric method supplemented by X-ray diffraction analysis and light and electron microscopy. In all instances, MgO prevented grain growth in the metallic phase. No evidence of oxidation along interphase boundaries was detected. Cermets of MgO in NiCrAlY and MgO in Hoskins-875 were superior to cermets of MgO in Inconel-702 and MgO in Hastelloy-X. Their oxidation resistance was degraded only when the MgO content was 40 vol percent. The oxidation behavior of MgO-in-Inconel-702 powder cermets containing 5- and 10-vol percent MgO was approximately similar to that of pure Inconel-702 compacts. The 20- and 40-vol percent MgO content reduced the oxidation resistance of MgO-in-Inconel-702 powder cermets relative to that of pure Inconel-702.

  18. Friction and Wear Characteristics of Candidate Foil Bearing Materials from 25 C to 800 C

    NASA Technical Reports Server (NTRS)

    DellaCorte, C.; Laskowski, J. A.

    1996-01-01

    The friction and wear behavior of unlubricated metal/metal sliding couples was investigated to screen potential candidates for high temperature foil bearings. The tribo-tests were run in an induction-heated high temperature pin-on-disk tribometer in an air atmosphere at a load of 4.9 N and at a sliding velocity of 1 m/s. The friction and wear properties of several nickel based alloys (Rene'41, Inconel X-750, Inconel 713C), iron based alloys (MA956 and Inconel 909) and a ceramic (Al2O3) were tested at 25, 500, and 800 C. In general, at elevated temperatures the alloys oxidized and formed a tenacious and lubricous oxide surface film or layer. At 800 C, Inconel X-750 versus Rene'41 had the lowest friction coefficient (0.27) and at 500 C, Inconel X-750 versus Inconel 909 the lowest pin wear (2.84 x 10(exp -6)cu mm/N-m). Gouging and severe wear of the softer material occurred whenever a significant difference in hardness existed between the pin and disk specimens.

  19. Microstructural and Mechanical Evaluation of a Cu-Based Active Braze Alloy to Join Silicon Nitride Ceramics

    NASA Technical Reports Server (NTRS)

    Singh, M.; Asthana, Rajiv; Varela, F. M.; Martinez-Fernandez, J.

    2010-01-01

    Self-joining of St. Gobain Si3N4 (NT-154) using a ductile Cu-Al-Si-Ti active braze (Cu-ABA) was demonstrated. A reaction zone approx.2.5-3.5 microns thick) developed at the interface after 30 min brazing at 1317 K. The interface was enriched in Ti and Si. The room temperature compressive shear strengths of Si3N4/Si3N4 and Inconel/Inconel joints (the latter created to access baseline data for use with the proposed Si3N4/Inconel joints) were 140+/-49MPa and 207+/-12MPa, respectively. High-temperature shear tests were performed at 1023K and 1073 K, and the strength of the Si3N4/Si3N4 and Inconel/Inconel joints were determined. The joints were metallurgically well-bonded for temperatures above 2/3 of the braze solidus. Scanning and transmission electron microscopy studies revealed a fine grain microstructure in the reaction layer, and large grains in the inner part of the joint with interfaces being crack-free. The observed formation of Ti5Si3 and AlN at the joint interface during brazing is discussed.

  20. Advanced fabrication techniques for cooled engine structures

    NASA Technical Reports Server (NTRS)

    Buchmann, O. A.

    1978-01-01

    An improved design for regeneratively cooled engine structures was identified. This design uses photochemically machined (PCM) coolant passages. It permits the braze joint to be placed in a relatively cool area, remote from the critical hot face sheet. The geometry of the passages at the face sheet also minimizes stress concentration and, therefore, enhances the low cycle fatigue performance. The two most promising alloys identified for this application are Inconel 617 and Nickel 201. Inconel 617 was selected because it has excellent creep rupture properties, while Nickel 201 was selected because of its predicted good performance under low cycle fatigue loading. The fabrication of the PCM coolant passages in both Inconel 617 and Nickel 201 was successfully developed. During fabrication of Inconel 617, undesirable characteristics were observed in the braze joints. A development program to resolve this condition was undertaken and led to definition of an isothermal solidification process for joining Inconel 617 panels. This process produced joints which approach parent metal strength and homogeneity.

  1. Electron emission from nickel-alloy surfaces in cesium vapor

    NASA Technical Reports Server (NTRS)

    Manda, M.; Jacobson, D.

    1978-01-01

    The cesiated electron emission was measured for three candidate electrodes for use as collectors in thermionic converters. Nickel, Inconel 600 and Hastelloy were tested with a 412 K cesium reservoir. Peak emission from the alloys was found to be comparable to that from pure nickel. Both the Inconel and the Hastelloy samples had work functions of 1.64 eV at peak emission. The minimum work functions were estimated to be 1.37 eV at a probe temperature of 750 K for Inconel and 1.40 eV for Hastelloy at 665 K. The bare work function for both alloys is estimated to be approximately the same as for pure nickel, 4.8 eV.

  2. Ceramic-to-metal bonding for pressure transducers

    NASA Technical Reports Server (NTRS)

    Mackenzie, J. D.

    1984-01-01

    A solid-state diffusion technique involving the placement of a gold foil between INCONEL X-750 and a machinable glass-ceramic "MACOR" was shown to be successful in bonding these two materials. This technique was selected after an exhaustive literature search on ceramic-metal bonding methods. Small expansion mismatch between the Inconel and the MACOR resulted in fracture of the MACOR when the bonded body was subjected to tensile stress of 535 psi. The bonded parts were submitted to a cyclic loading test in an air atmosphere at 1 Hz from 0 to 60 KPa. Failure was observed after 700,000 cycles at 650 C. Ceramic-Inconel bonding was not achieved with this method for boron nitride and silica glass.

  3. Influence of strain aging on the strain-rate sensitivity of the flow stress

    SciTech Connect

    Schwarz, R.B.

    1982-01-01

    Previously published studies on the deformation kinetics of several fcc alloys, i.e. single crystals of Al-0.7% Mg, polycrystals of AlMg, Inconel 600, Inconel X750, NiCo, AuCu, and FeC, are cited, and two models are proposed to explain the reported observations. The calculations suggest that excess vacancies play an important role in the dynamic strain aging of the alloys and that an intermediate thermal annealing process should remove the vacancies. (BLM)

  4. Evaluation of candidate Stirling engine heater tube alloys after 3500 hours exposure to high pressure doped hydrogen or helium. Final report

    SciTech Connect

    Misencik, J.A.; Titran, R.H.

    1984-10-01

    Sixteen commercial tubing alloys were endurance tested at 820/sup 0/ C, 15 MPa in a diesel-fuel fired Stirling engine simulator materials test rig: iron-base N-155, A-286, Incoloy 800, 19-9DL, CG-27, W-545, 12RN72, 253MA, Sanicro 31H and Sanicro 32; nickel-base Inconel 601, Inconel 625, Inconel 718, Inconel 750 and Pyromet 901; and cobalt-base HS-188. The iron-nickel alloys CG-27 and Pyromet 901 exhibited superior oxidation/corrosion resistance to the diesel-fuel combustion products and surpassed the design criterias' 3500 h creep-rupture endurance life. Three other alloys, Inconel 625, W-545, and 12RN72, had creep-rupture failures after 2856, 2777, and 1598 h, respectively. Hydrogen permeability coefficients determined after 250 h of rig exposure show that Pyromet 901 had the lowest Phi value, 0.064x10/sup -6/ cm/sup 2//s MPa/sup 1///sup 2/. The next five hairpin tubes, CG-27, Inconel 601, Inconel 718(wd), Inconel 750, and 12RN72(cw) all had Phi values below 0.2x10/sup -6/ more than a decade lower than the design criteria. Based upon its measured high strength and low hydrogen permeation, CG-27 was selected for 3500 h endurance testing at 21 MPa gas pressure and 820/sup 0/C. Results of the high pressure, 21 MPa, CG-27 endurance test demonstrated that the 1.0 vol % C0/sub 2/ dopant is an effective deterrent to hydrogen permeation. The 21 MPa hydrogen gas pressure apparent permeability coefficient at 820/sup 0/C approached 0.1x10/sup -6/ cm/sup 2/sec MPa/sup 1///sup 2/ after 500 hr, the same as the 15 MPa test. Even at this higher gas pressure and comparable permeation rate, CG-27 passed the 3500 hr endurance test without creep-rupture failures. It is concluded that the CG-27 alloy, in the form of thin wall tubing is suitable for Stirling engine applications at 820/sup 0/C and gas pressures up to 21 MPa.

  5. Precipitation of the δ-Ni3Nb phase in two nickel base superalloys

    NASA Astrophysics Data System (ADS)

    Sundararaman, M.; Mukhopadhyay, P.; Banerjee, S.

    1988-03-01

    The precipitation of the equilibrium δ-Ni3Nb phase has been studied in two niobium bearing nickel base superalloys—INCONEL 718 and INCONEL* 625—both of which are hardenable by the precipitation of the metastable γ″-Ni3Nb phase. The morphology and the distribution of precipitates have been examined and the crystallographic orientation relationship between the austenite and the δ phases has been determined. The nucleation of the δ phase at stacking faults within pre-existing δ" precipitates has been discussed.

  6. Hydrogen gas embrittlement and the disc pressure test

    NASA Technical Reports Server (NTRS)

    Bachelet, E. J.; Troiano, A. R.

    1973-01-01

    A disc pressure test has been used to study the influenced of a hydrogen gas environment on the mechanical properties of three high strength superalloys, Inconel 718, L-605 and A-286, in static and dynamic conditions. The influence of the hydrogen pressure, loading rate, temperature, mechanical and thermal fatigue has investigated. The permeation characteristics of Inconel 718 have been determined in collaboration with the French AEC. The results complemented by a fractographic study are consistent either with a stress-sorption or with an internal embrittlement type of mechanism.

  7. Determination of the relative resistance to ignition of selected turbopump materials in high-pressure, high-temperature, oxygen environments, volume 2

    NASA Technical Reports Server (NTRS)

    Stoltzfus, Joel M.; Benz, Frank J.

    1986-01-01

    Data from the particle impact tests are presented. Results are provided for the frictional heating tests of pairs of like materials. The materials tested include: Hastelloy X, Inconel 600, Invar 36, Monel K-500, Monel 400, nickel 200, silicon carbide, stainless steel 316, and zironium copper.

  8. Experiences on IGSCC crack manufacturing

    SciTech Connect

    Veron, P.

    1997-02-01

    The author presents his experience in manufacturing IGSCC realistic defects, mainly in INCONEL 600 MA Steam Generator Tubes. From that experience he extracts some knowledge about this cracking (influence of chemistry in the environment, stress state, crack growth rate, and occurrence in laboratory condition of break before leak).

  9. Galvanic Corrosion In (Graphite/Epoxy)/Alloy Couples

    NASA Technical Reports Server (NTRS)

    Danford, Merlin D.; Higgins, Ralph H.

    1988-01-01

    Effects of galvanic coupling between graphite/epoxy composite material, G/E, and D6AC steel, 6061-T6 aluminum, and Inconel(R) 718 nickel alloy in salt water described in report. Introductory section summarizes previous corrosion studies of G/E with other alloys. Details of sample preparation presented along with photographs of samples before and after immersion.

  10. Analytical chemistry methods for metallic core components: Revision March 1985

    SciTech Connect

    Not Available

    1985-03-01

    This standard provides analytical chemistry methods for the analysis of alloys used to fabricate core components. These alloys are 302, 308, 316, 316-Ti, and 321 stainless steels and 600 and 718 Inconels and they may include other 300-series stainless steels.

  11. Microstructural Development and Mechanical Properties for Reactive Air Brazing of ZTA to Ni Alloys using Ag-CuO Braze Alloys

    SciTech Connect

    Prevost, Erica; DeMarco, A.Joseph; MacMichael, Beth; Joshi, Vineet V.; Meier, Alan; Hoffman, John W.; Walker, William J.

    2014-12-01

    Reactive air brazing (RAB) is a potential joining technique to join metal alloys to ceramics for a variety of applications. In the current study, nickel (Ni) alloys were heat treated to form an oxide layer prior to RAB joining to zirconia toughened alumina (ZTA). The Ni alloys evaluated were Nicrofer 6025 HT, Inconel 600, Inconel 693, Haynes 214 and Inconel 601. The ZTA studied had compositions of 0 to 15 wt% zirconia and 0 to 14 wt% glass. Four point-bend tests were performed to evaluate the joint strength of ZTA/ZTA and ZTA/nickel alloys brazed with Ag-2wt% CuO braze alloys. It was determined that the joint strength is not a function of the ZTA composition, but that the strength is a strong function of the chemistry and microstructure of the oxide layer formed on the nickel alloy. It was determined that an increase in the aluminum content of the Ni alloy resulted in an increase of the thickness of alumina in the oxide layer and was directly proportional to the bond strength with the exception of Inconel 601 which exhibited relatively high joint strengths even though it had a relatively low aluminum content.

  12. Integrated research in constitutive modelling at elevated temperatures, part 2

    NASA Technical Reports Server (NTRS)

    Haisler, W. E.; Allen, D. H.

    1986-01-01

    Four current viscoplastic models are compared experimentally with Inconel 718 at 1100 F. A series of tests were performed to create a sufficient data base from which to evaluate material constants. The models used include Bodner's anisotropic model; Krieg, Swearengen, and Rhode's model; Schmidt and Miller's model; and Walker's exponential model.

  13. Improved Seals for High Temperature Airframe Applications

    NASA Technical Reports Server (NTRS)

    DeMange, Jeffrey J.; Dunlap, Patrick H.; Steinetz, Bruce M.

    2006-01-01

    Current thermal barrier seals, such as those used on the Space Shuttle, are insufficient to fully meet the demands of future hypersonic vehicles and reentry spacecraft. Previous investigations have demonstrated limited usage temperatures, as evidenced by a decreased ability to maintain sealing effectiveness at high temperatures (i.e., inadequate resiliency). In order to improve resiliency at elevated temperatures, Rene 41 (Allvac) was substituted for Inconel X-750 (Special Metals Corp.) as the spring tube material in the existing seal design. A seal construction incorporating the Rene 41 spring tube was fabricated and tested against the baseline Inconel X-750 spring tube seal. Although resiliency improvements were not as dramatic as in previous tests with the spring tubes alone, seals incorporating the Rene 41 spring tube exhibited an average 20 percent resiliency enhancement up to 1750 F when compared to seals containing the Inconel spring tube. In addition, the seals with the Rene 41 spring tubes showed less reduction in resiliency as temperatures increased above 1200 F. Results also indicated the Saffil (Saffil Ltd.) insulation in the core of the seal contributed more to resiliency than previously thought. Leakage data did not demonstrate an improvement with the seal containing the Rene 41 spring tube. However, based upon resiliency results, one could reasonably expect the Rene 41 version of the seal to track gap openings over a wider range. Therefore it would exhibit lower leakage than the Inconel X-750 version as the seal gap opens during a typical mission.

  14. Characterization of the Micro-Welding Process for Repair of Nickel Base Superalloys

    NASA Astrophysics Data System (ADS)

    Durocher, J.; Richards, N. L.

    2007-12-01

    Micro-welding is a low-heat input process whereby a metal or cermet, is deposited by the generation of a low-power arc between a consumable electrode and a substrate. The low-heat input of this process offers unique advantages over more common welding processes such as gas tungsten arc, plasma arc, laser, and electron beam welding. At present, the repair of turbine blades and vanes commonly involves gas tungsten arc welding and these components are susceptible to heat affected zone cracking during the weld repair process; vacuum brazing is also used but mainly on low-stress components such as stators. In this study, the low-heat input characteristic of micro-welding has been utilized to simulate repair of Inconel (Trade Mark of Special Metals) 625, Inconel 718, and Inconel 722 filler alloys to a cast Inconel 738 substrate. The effect of micro-welding process parameters on the deposition rate, coating quality, and substrate has been investigated.

  15. Evaluation of the Low Heat Input Process for Weld Repair of Nickel-Base Superalloys

    NASA Astrophysics Data System (ADS)

    Durocher, J.; Richards, N. L.

    2011-10-01

    The repair of turbine blades and vanes commonly involves gas tungsten arc welding or an equivalent process, but unfortunately these components are often susceptible to heat-affected zone (HAZ) cracking during the weld repair process. This is a major problem especially in cast alloys due to their coarse-grain size and where the (Al + Ti) contents is in excess of 3-4%; vacuum brazing is also used but mainly on low stress non-rotating components such as vanes. Micro-welding has the potential to deposit small amounts of filler at low heat input levels with minimum HAZ and thus is an attractive process for depositing a quality weld. As with conventional fusion processes, the filler alloy is deposited by the generation of a low power arc between a consumable electrode and the substrate. The low heat input of this process offers unique advantages over more common welding processes such as gas tungsten arc, plasma arc, laser, and electron beam welding. In this study, the low heat input characteristic of micro-welding has been used to simulate weld repair using Inconel (IN) (Inconel and IN are trademarks of INCO Alloys International) 625, Rene (Rene is a trademark of General Electric Company) 41, Nimonic (Nimonic is a trademark of INCO Alloys International) 105 and Inconel 738LC filler alloys, to a cast Inconel 738LC substrate. The effect of micro-welding process parameters on the deposition rate, coating quality, and substrate has been investigated.

  16. The effect of hot salt on the mechanical properties of several superalloys

    NASA Technical Reports Server (NTRS)

    Nelson, E. E.

    1972-01-01

    The effect of sodium chloride on unstressed, transverse, tensile, metal specimens at elevated temperatures was determined. Results indicate that the mechanical properties of Inconel 718, Rene 41, titanium base alloy 13V-11Cr-3Al, Hastelloy X, HS25 (L605), HS188, and TDNiCr suffer degradation in tensile strength and ductility due to hot salt exposure.

  17. Behaviour of tritium in the vacuum vessel of JT-60U

    SciTech Connect

    Kobayashi, K.; Miya, N.; Ikeda, Y.; Torikai, Y.; Saito, M.; Alimov, V.

    2015-03-15

    The disassembly of the JT-60U torus started in 2010 after 18 years of deuterium plasma operations. The vessel is made of Inconel 625. Therefore, it was very important to study the hydrogen isotope (particularly tritium) behavior in Inconel 625 from the viewpoint of the clearance procedure. Inconel 625 specimen was exposed to the D{sub 2} (92.8 %) - T{sub 2} (7.2 %) gas mixture at 573 K for 5 hours. The tritium release from the specimen at 298 K was controlled for about 1 year. After that a part of tritium remaining in the specimen was released by heating up to 1073 K. Other part of tritium trapped in the specimen was measured by chemical etching method. Most of the chemical form of the released tritium was HTO. The contaminated specimen by tritium was released continuously the diffusible tritium under the ambient condition. In the tritium release experiment, the amount of desorbed tritium was about 99% during 1 year. It was considered that the tritium in Inconel 625 was released easily.

  18. Tungsten wire-reinforced superalloys for 1093 C (2000 F) turbine blade applications

    NASA Technical Reports Server (NTRS)

    Friedman, G. I.; Fleck, J. N.

    1979-01-01

    Various combinations of fiber and matrix materials were fabricated and evaluated for the purpose of selecting a specific combination that exhibited the best overall properties for a turbine blade application. A total of seven matrix alloys, including Hastelloy X, Nimonic 80A, Inconel 600, Inconel 625, IN-102, FeCrA1Y, were investigated reinforced with either 218CS tungsten, or W-Hf-C fibers. Based on preliminary screening studies, FeCrA1Y, Inconel 600 and Inconel 625 matrix composites systems were selected for extended thermal cycle tests and for property evaluations which included stress rupture, impact, and oxidation resistance. Of those investigated, the FeCrA1Y matrix composite system exhibited the best overall properties required for a turbine blade application. The W-Hf-C/FeCrA1Y system was selected for further property evaluation. Tensile strength values of up to 724 MPa (105,000 psi) were obtained for this material at 982 C and 607 MPa at 1093 C.

  19. 77 FR 6522 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-08

    ... 12866, (2) Is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034... inspections for fractured or missing latch pin retention bolts, replacement of existing titanium bolts with... titanium with new Inconel bolts; replacing the latch pin fitting assembly; repairing the lower sill of...

  20. End-of-life examinations of Light Water Breeder Reactor grids and other module structural components (LWBR Development Program)

    SciTech Connect

    Smith, B.C.; Clayton, J.C.; Pitcairn, T.N.; Richardson, K.D.; Smith, B.C.; Wargo, J.E.

    1987-10-01

    End-of-Life examinations were performed on LWBR core structural components which had important influence on mechanical stability of fuel elements duing core performance. These components included: (1) AM-350 stainless steel grid sections to assess corrosion, stress relaxation, braze performance, and dimensional stability; (2) a 348 stainless steel flux thimble tube which failed in service; (3) various Inconel X-750, Inconel-600, 17-4 PH, and AM-350 bolts; (4) Zircaloy-4 module shells and screws; (5) Inconel-600 module cover plates and baseplates; (6) 304 stainless steel Bypass Inlet Flow Supply Tube; (7) 17-4 PH shear keys and Inconel-600 struts; (8) Zircaloy-4 module support posts; (9) seed module support shaft and balance piston. Examinations included visual inspection and, in some cases, dye penetrant and metallography. Threaded fasteners remained uncracked to end-of-life (EOL). Grid dimensions showed minor changes at EOL. Grid springs exhibited good stress relaxation characteristics. Corrosion resistance of core components was adequate, and components were relatively free from crud buildup.

  1. Multihole Arc-Welding Orifice

    NASA Technical Reports Server (NTRS)

    Swaim, Benji D.

    1989-01-01

    Modified orifice for variable-polarity plasma-arc welding directs welding plume so it creates clean, even welds on both Inconel(R) and aluminum alloys. Includes eight holes to relieve back pressure in plasma. Quality of welds on ferrous and nonferrous alloys improved as result.

  2. Effect of high-pressure oxygen on the mechanical properties of alloys

    NASA Technical Reports Server (NTRS)

    Schwartzberg, F. R.; Shepic, J. A.

    1977-01-01

    Unnotched and notched tensile properties of stressed and unstressed specimens of wrought 316 stainless steel, Incology 903, Monel K-500, and cast specimens of Inconel 718 were examined. Environmental tests were performed in atmospheric pressure air, high pressure nitrogen, and high pressure oxygen. Results show that oxygen did not alter the tensile properties of any of the alloys studied.

  3. Microstructural characterization of dissimilar welds between Incoloy 800H and 321 Austenitic Stainless Steel

    SciTech Connect

    Sayiram, G. Arivazhagan, N.

    2015-04-15

    In this work, the microstructural character of dissimilar welds between Incoloy 800H and 321 Stainless Steel has been discussed. The microscopic examination of the base metals, fusion zones and interfaces was characterized using an optical microscope and scanning electron microscopy. The results revealed precipitates of Ti (C, N) in the austenitic matrix along the grain boundaries of the base metals. Migration of grain boundaries in the Inconel 82 weld metal was very extensive when compared to Inconel 617 weldment. Epitaxial growth was observed in the 617 weldment which increases the strength and ductility of the weld metal. Unmixed zone near the fusion line between 321 Stainless Steel and Inconel 82 weld metal was identified. From the results, it has been concluded that Inconel 617 filler metal is a preferable choice for the joint between Incoloy 800H and 321 Stainless Steel. - Highlights: • Failure mechanisms produced by dissimilar welding of Incoloy 800H to AISI 321SS • Influence of filler wire on microstructure properties • Contemplative comparisons of metallurgical aspects of these weldments • Microstructure and chemical studies including metallography, SEM–EDS • EDS-line scan study at interface.

  4. Post-test examination of a pool boiler receiver

    NASA Technical Reports Server (NTRS)

    Dreshfield, Robert L.; Moore, Thomas J.; Bartolotta, Paul A.

    1992-01-01

    A subscale pool boiler test apparatus to evaluate boiling stability developed a leak after being operated with boiling NaK for 791.4 hr at temperatures from 700 to 750 C. The boiler was constructed using Inconel 625 with a type 304L stainless steel wick for the boiler and type 316 stainless steel for the condenser. The boiler assembly was metallurgically evaluated to determine the cause of the leak and to assess the effects of the NaK on the materials. It was found that the leak was caused by insufficient (about 30 pct.) joint penetration in a butt joint. There was no general corrosion of the construction materials, but the room temperature ductility of the Inconel 625 was only about 6.5 pct. A crack in the heat affected zone of the Inconel 625 near the Inconel 625 to type 316 stainless steel butt joint was probably caused by excessive heat input. The crack was observed to have a zone depleted of iron at the crack surface and porosity below that zone. The mechanism of the iron depletion was not conclusively determined.

  5. Materials problems in fluidized bed combustion systems. Appendix 4: evaluation of boiler alloy specimens at General Electric Company. Final report

    SciTech Connect

    Not Available

    1980-05-01

    The results of post-test evaluations of certain boiler alloy specimens from corrosion tests conducted in the fluidized-bed combustion system at the Coal Research Establishment, Stoke Orchard, England are presented. Two tests, each of 1000 hours duration were conducted. Alloys included were Inconel 601, Inconel 617, Inconel 671, Hastelloy X, Haynes Alloy 188, and GE-2541 alloy. Specimen temperatures ranged from 649/sup 0/C (1200/sup 0/F) to 899/sup 0/C (1650/sup 0/F). Calcium sulfate deposits occurred on all specimens, regardless of whether they were situated in the combustion bed or in the free-board above it. In general, corrosion attack as measured by the thickness of affected metal below the deposit/scale, was greater in specimens located in the bed than in similar specimens tested at the same temperature above the bed. A dramatic example of this is the 160 to 225 microns average attack in specimens of Inconel 671 tested at 899/sup 0/C (1650/sup 0/F) in the bed compared to 18 microns in a specimen tested at the same temperature above the bed. In most instances the differences were much smaller, and in a few cases no difference was apparent. Inconel 601 showed greater attack at 760/sup 0/C (1400/sup 0/F) in the bed than at 843/sup 0/C (1550/sup 0/F). To a lesser extent, Inconel 617 specimens showed the same general trend. Hastelloy X and Haynes Alloy 188 specimens exhibited moderate attack (10 to 50 microns) at the temperatures at which they were tested. Specimens of the iron-chrome-aluminum-yttrium alloy, GE-2541, showed the least attack at 899/sup 0/C (1650/sup 0/F) of these alloys, both for specimens tested in and above the combustion bed. Inconel 671 specimens which were situated in the combustion bed showed very severe localized attack (pits) while many other areas of the same specimens exhibited no greater attack than specimens of other alloys.

  6. High strength kiloampere Bi2Sr2CaCu2Ox cables for high-field magnet applications

    NASA Astrophysics Data System (ADS)

    Shen, Tengming; Li, Pei; Jiang, Jianyi; Cooley, Lance; Tompkins, John; McRae, Dustin; Walsh, Robert

    2015-06-01

    Multifilamentary Ag-sheathed Bi2Sr2CaCu2Ox (Bi-2212) wire can carry sufficient critical current density Jc for the development of powerful superconducting magnets. However, the range of its applications is limited by the low mechanical strength of the Ag/Bi-2212 strand. A potential solution is to cable Ag/Bi-2212 wire with high-strength materials that are compatible with the Bi-2212 heat treatment in an oxygen atmosphere. Past attempts have not always been successful, because the high-strength materials reacted with Bi-2212 wires, significantly reducing their Jc. We examined the nature of reactions occurring when Ag/Bi-2212 wires are heat-treated in direct contact with several commonly used high-strength alloys and a new Fe-Cr-Al alloy. INCONEL X750 and INCONEL 600 resulted in significant Jc loss, whereas Ni80-Cr caused little or no Jc loss; however, all of them formed chromium oxide that subsequently reacted with silver, creating cracks in the silver sheath. We found that Fe-Cr-Al did not show significant reactions with Ag/Bi-2212 strands. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDS) examinations revealed that the Fe-Cr-Al alloy benefits from the formation of a uniform, crack-free, continuous alumina layer on its surface that does not react with Ag and that helps minimize the Cu loss found with INCONEL X750 and INCONEL 600. We fabricated prototype 6-around-1 cables with six Bi-2212 strands twisted and transposed around an Fe-Cr-Al alloy core coated with TiO2. After standard 1 bar melt processing, the cable retained 100% of the total current-carrying capability of its strands, and, after a 10 bar overpressure processing, the cable reached a total current of 1025 A at 4.2 K and 10 T. Tensile tests showed that Fe-Cr-Al becomes brittle after being cooled to 4.2 K, whereas INCONEL X750 remains ductile and retains a modulus of 183 GPa. We proposed new cable designs that take advantage of the chemical compatibility of Fe-Cr-Al and high strength of

  7. Bipropellant shut-off valve

    NASA Technical Reports Server (NTRS)

    Smith, J. V.

    1971-01-01

    An advanced design of an all metal, fast response, bipropellant, shut-off valve for use on long duration space missions is reported. The valve provides the flow control capability for a 1,000 lb thrust, bipropellant engine using oxygen difluoride and diborane as propellants. The shutoff seal selection is a soft-on-hard metal concept. The soft seal is a spherical shell that seats against a hard conical seat. Beryllium copper and beryllium nickel seals were selected to seal against an electrolyzed Inconel 718 seat. Poppet shaft sealing is achieved by use of hydroformed, Inconel 718 bellows. Two valve assemblies were fabricated and subjected to a series of tests including leak, response time, flow capacity, dry cycles, water cycles, liquid nitrogen cycles, liquid fluorine cycles, and lead-lag operation cycles. These tests demonstrated the ability of the valve to meet design goals.

  8. Wear studies of materials for tubes and anti-vibration bars in nuclear steam generators

    SciTech Connect

    Ko, P.L.; Taponat, M.C.; Zbinden, M.

    1995-12-01

    Wear occurs as a result of relative motion at the interface of two contacting bodies. In nuclear power steam generators, high flow rates can induce vibration of the tubes resulting in wear damage due to impact and sliding contacts between the tubes and their supports. A research project aiming to gain better understanding of the mechanisms and mechanics involved in vibratory wear and to develop a more versatile predictive wear model was carried out. Combinations of Inconel tubes against flat anti-vibration bars of 403 s.s. and electrolytic chrome plated Inconel 600 were tested under conditions of reciprocating sliding and impacting in water at room temperature and at 250 C. The results show that depending on the material combinations and the loading conditions distinctively different wear mechanisms and often drastically different wear rates can occur.

  9. The development and characterisation of carbon nanotubes grown on conductive substrate for field emission application

    NASA Astrophysics Data System (ADS)

    Venugopalan, Ramani; Prakash, Jyoti; Ghatak, Shreya; Mittal, K. C.; Sathiyamoorthy, D.

    2013-06-01

    The CNT-inconel interface exhibhits good electrical contact as well as strong adhesion to be used directly as electrodes for super capacitors and field emitters without any post growth processing with respect to other metal substrate. Carbon nano tubes were synthesized on inconel substrate over the 10*10 mm2 area by catalytic decomposition of ferrocene - Xylene mixture at 800°C. The growth process involved injecting a solution of particular concentration of ferrocene in xylene at a particular flow rate into a preheating zone of reactor. A mixture of argon and hydrogen was used to carry the xylene containing catalyst vapors upto substrate. Scanning electron microscopy (SEM) and Raman Spectroscopy investigations reveal that the nanotubes are multi-wall CNTs having about 40-70 nm diameter. The possibility of growing CNTs on the metal substrates other than silicon has been confirmed from the above results.

  10. Corrosion behavior of silicon nitride, magnesium oxide, and several metals in molten calcium chloride with chlorine

    SciTech Connect

    McLaughlin, D. . Research and Development Center); Sesions, C.E.; Marra, J.E. )

    1992-08-01

    In this paper corrosion studies are described in a molten calcium chloride environment sparged with chlorine gas at 850{degrees}C, both in the melt and in the gas phase above the salt, in support of efforts at Westinghouse Savannah River Company to develop more resistant materials of construction for molten salt processing of plutonium. Corrosion rates and electron microscope analyses are reported for Inconel alloys 601 and 617, tantalum, tungsten, magnesium oxide, and silicon nitride. Silicon nitride exhibited the greatest resistance, showing {lt}0.1 mg/cm{sup 2} {center dot} h loss in both melt and vapor None of the metallic coupons withstood the chlorine vapor environment, although Inconel indicated resistance immersed in the melt if protected from chlorine gas.

  11. Preselection of Ni-Cr(-Mo) alloys as potential canister materials for vitrified high active nuclear waste by electrochemical testing

    NASA Astrophysics Data System (ADS)

    Bort, H.; Wolf, I.; Leistikow, S.

    1987-07-01

    Several Ni-Cr(-Mo) alloys (Hastelloy C4, Inconel 625, Sanicro 28, Incoloy 825, Inconel 690) were tested by electrochemical methods to characterize their corrosion behavior in chloride containing solutions at various temperatures and pH-values in respect to their application as canister materials for final radioactive waste storage. Especially, Hastelloy C4 was tested by potentiodynamic, potentiostatic and galvanostic measurements. As electrolytes H 2SO 4 solutions were used, as parameters temperature, chloride content and pH-value were varied. All tested alloys showed a clearly limited resistance against pitting corrosion phenomena; under severe conditions even crevice corrosion phenomena were observed. The best corrosion behavior, however, is shown by Hastelloy C4, which has the lowest passivation current density of all tested alloys and the largest potential region with protection against local corrosion phenomena.

  12. High temperature seal for joining ceramics and metal alloys

    DOEpatents

    Maiya, P. Subraya; Picciolo, John J.; Emerson, James E.; Dusek, Joseph T.; Balachandran, Uthamalingam

    1998-01-01

    For a combination of a membrane of SrFeCo.sub.0.5 O.sub.x and an Inconel alloy, a high-temperature seal is formed between the membrane and the alloy. The seal is interposed between the alloy and the membrane, and is a fritted compound of Sr oxide and boric oxide and a fritted compound of Sr, Fe and Co oxides. The fritted compound of SrFeCo.sub.0.50 O.sub.x is present in the range of from about 30 to 70 percent by weight of the total sealant material and the fritted compound of Sr oxide and boric oxide has a mole ratio of 2 moles of the Sr oxide for each mole of boric oxide. A method of sealing a ceramic to an Inconel metal alloy is also disclosed.

  13. High temperature seal for joining ceramics and metal alloys

    DOEpatents

    Maiya, P.S.; Picciolo, J.J.; Emerson, J.E.; Dusek, J.T.; Balachandran, U.

    1998-03-10

    For a combination of a membrane of SrFeCo{sub 0.5}O{sub x} and an Inconel alloy, a high-temperature seal is formed between the membrane and the alloy. The seal is interposed between the alloy and the membrane, and is a fritted compound of Sr oxide and boric oxide and a fritted compound of Sr, Fe and Co oxides. The fritted compound of SrFeCo{sub 0.50}O{sub x} is present in the range of from about 30 to 70 percent by weight of the total sealant material and the fritted compound of Sr oxide and boric oxide has a mole ratio of 2 moles of the Sr oxide for each mole of boric oxide. A method of sealing a ceramic to an Inconel metal alloy is also disclosed. 3 figs.

  14. Power plant VII - Air-air /tube boiler/

    NASA Astrophysics Data System (ADS)

    Roche, M.

    An attempt to design a solar thermal electric central receiver power plant in the multi-MW size with acceptable efficiencies using air in the power loop is described. The turbine and generator are placed in the tower to reduce heat losses in the superheated gas, and the depleted gas loop is coupled to a low temperature generator powered by boiling water. The receiver cavity is configured to retain a maximum amount of flux and has brick walls. Nickel alloys are indicated for the air tubes in the receiver, with Inconel 601, Incoloy 800, and Inconel 600 considered acceptable. The gas leaving the chamber will be at 950 C to power a high pressure turbine, followed by entrance into a heat exchanger to boil the water for the low-pressure turbine, and is then discharged. Thermodynamic efficiencies between 13.9-20.3 percent for a 4700 kW plant are considered feasible with the design.

  15. Sliding wear behaviors of steam generator tube materials in high temperature water environment

    NASA Astrophysics Data System (ADS)

    Park, Gi Sung; Kim, Gyung Guk; Kim, Seon Jin

    2006-06-01

    Wear damage of steam generator tubes for nuclear power plants can cause the leakage of radioactive substances. Therefore, the evaluation of the tube integrity is very important in the view point of nuclear safety. In the present study, to investigate the effects of the applied normal load and sliding distance on wear volume in 575 K water environment, sliding wear tests were performed with Inconel 600 and 690 steam generator tube materials mated with 409 stainless steel commonly used as support plate. Based on the accumulated data, the newly modified Archard equation was proposed and then the wear coefficients of tube materials were estimated with both Archard equation and the modified Archard equation. The reliabilities, which are parameters to assess how well a model fits a set of data, for prediction of wear behaviors of Inconel 600 and 690 improved from 20.5% to 65.5% and from 38.5 to 65.3%, respectively.

  16. Metal cation inhibitors for controlling denting corrosion in steam generators. Final report. [PWR

    SciTech Connect

    Leidheiser, H. Jr.; Granata, R.D.; Simmons, G.W.; Music, S.; Vedage, H.L.

    1982-12-01

    Metal cations of arsenic, antimony, tin, manganese, zinc, cadmium, indium, and thallium have been evaluated in a preliminary way as possible3 inhibitors for controlling denting corrision observed in steam generators used with pressurized water reactors (PWR). The rationale for this approach was based upon the well-known inhibition effects of metal cations on corrosion rates in electrolyte/metal systems. A review of corrosion inhibition by metal cations (H. Leidheiser, Jr., Corrosion 36, 339 (1982)) has identified eleven inhibition mechanisms. The major test methods used for this evaluation were: (1) Isothermal capsule tests of carbon/steel/Inconel 600 tube bulging rates at temperatures up to 288/sup 0/C in seawater/copper-nickel chloride bulge-accelerating solutions. (2) Immersion weight-loss tests of steel coupled to Inconel 600 in boiling (102/sup 0/C) 3% sodium chloride solutions. In addition, electrochemical measuremens and surface analyses were performed. The major findings of this investigation are presented.

  17. Initiation and propagation of stress-corrosion cracking of Alloy 600 in high-temperature water. [PWR

    SciTech Connect

    Bandy, R.; van Rooyen, D.

    1983-01-01

    Results of stress-corrosion cracking data are presented for Inconel 600 steam-generator tubing. U-bend, constant-load, and slow extension-rate tests are included. Arrhenius plots are presented for failure times vs inverse temperature for crack initiation and propagation. Effect of applied load is expressed in terms of log-log curves for failure times vs stress, and variations in environment and cold work are included. Microstructure and composition of oxide films on Inconel 600 surfaces were examined after exposure to pure water at 365/sup 0/C, and stripping with the bromine-methanol method. Results are discussed in terms of transient creep, film rupture and a mass-transport-limited anodic process.

  18. Effect of glass-ceramic-processing cycle on the metallurgical properties of candidate alloys for actuator housings

    SciTech Connect

    Weirick, L.J.

    1982-01-01

    This report summarizes the results from an investigation on the effect of a glass ceramic processing cycle on the metallurgical properties of metal candidates for actuator housings. The cycle consists of a 980/sup 0/C sealing step, a 650/sup 0/C crystallization step and a 475/sup 0/C annealing step. These temperatue excursions are within the same temperature regime as annealing and heat treating processes normally employed for metals. Therefore, the effect of the processing cycle on metallurgical properties of microstructure, strength, hardness and ductility were examined. It was found that metal candidates which are single phase or solid solution alloys (such as 21-6-9, Hastelloy C-276 and Inconel 625) were not affected whereas multiphase or precipitation hardened alloys (such as Inconel 718 and Titanium ..beta..-C) were changed by the processing cycle for the glass ceramic.

  19. Measurement of surface temperature and emissivity of different materials by two-colour pyrometry.

    PubMed

    Raj, Vinay C; Prabhu, S V

    2013-12-01

    An experimental investigation is performed to substantiate the capability of a charge coupled device camera to measure local temperature and emissivity of different materials heated to temperatures above 500 °C by two-colour pyrometric technique using colorimetric method. Materials investigated are Inconel 718 with pyromark (high temperature paint), Inconel 718, stainless steel SS 304 and SS 316. Centerline temperature and emissivity distribution is obtained for target plates maintained at constant temperature by AC heating while complete temperature and emissivity distribution is provided for plates heated by flame impingement. The obtained results are compared with a calibrated infrared camera and thermocouples and the temperature distribution is found to be in close agreement. These results pertain to partially oxidized metal alloys covered in this study. Deviation in the measurement of emissivity can be attributed to its dependence on wavelength range, oxidation, and sensitivity of the image detector. PMID:24387454

  20. Influence of cubic boron nitride grinding on the fatigue strengths of carbon steels and a nickel-base superalloy

    SciTech Connect

    Kawagoishi, N.; Chen, Q.; Kondo, E.; Goto, M.; Nisitani, H.

    1999-04-01

    The influence of cubic boron nitride (CBN) grinding on fatigue strength was investigated on an annealed carbon steel, a quenched and tempered carbon steel at room temperature, and a nickel-base superalloy, Inconel 718, at room temperature and 500 C. The results were discussed from several viewpoints, including surface roughness, residual stress, and work hardening or softening due to CBN grinding. The fatigue strength increased upon CBN grinding at room temperature, primarily because of the generation of compressive residual stress in the surface region. However, in the case of Inconel 718, this marked increase in the fatigue strength tended to disappear at the elevated temperature due to the release of compressive residual stress and the decrease of crack growth resistance at an elevated temperature.

  1. Lid heater for glass melter

    DOEpatents

    Phillips, Terrance D.

    1993-01-01

    A glass melter having a lid electrode for heating the glass melt radiantly. The electrode comprises a series of INCONEL 690 tubes running above the melt across the melter interior and through the melter walls and having nickel cores inside the tubes beginning where the tubes leave the melter interior and nickel connectors to connect the tubes electrically in series. An applied voltage causes the tubes to generate heat of electrical resistance for melting frit injected onto the melt. The cores limit heat generated as the current passes through the walls of the melter. Nickel bus connection to the electrical power supply minimizes heat transfer away from the melter that would occur if standard copper or water-cooled copper connections were used between the supply and the INCONEL 690 heating tubes.

  2. Lid heater for glass melter

    DOEpatents

    Phillips, T.D.

    1993-12-14

    A glass melter having a lid electrode for heating the glass melt radiantly. The electrode comprises a series of INCONEL 690 tubes running above the melt across the melter interior and through the melter walls and having nickel cores inside the tubes beginning where the tubes leave the melter interior and nickel connectors to connect the tubes electrically in series. An applied voltage causes the tubes to generate heat of electrical resistance for melting frit injected onto the melt. The cores limit heat generated as the current passes through the walls of the melter. Nickel bus connection to the electrical power supply minimizes heat transfer away from the melter that would occur if standard copper or water-cooled copper connections were used between the supply and the INCONEL 690 heating tubes. 3 figures.

  3. Swelling of several commercial alloys following high fluence neutron irradiation

    SciTech Connect

    Powell, R.W.; Peterson, D.T.; Zimmerschied, M.K.; Bates, J.F.

    1981-01-01

    Swelling values have been determined for a set of commercial alloys irradiated to a peak fluence of 17.8 x 10/sup 22/ n/cm/sup 2/ (E > 0.1 MeV) over the temperature range of 400 to 650/sup 0/C. The alloys studied fall into three classes: the ferritic alloys AISI 430F, AISI 416, EM-12, H-11 and 2 1/4 Cr-1 Mo; the superalloys Inconel 718 and Inconel X-750; and the refractory alloys TZM and Nb-1 Zr. After irradiation to a peak fluence approaching goal exposures envisioned for advanced fusion reactor first walls, all of the alloys display swelling resistance far superior to cold worked AISI 316. Of the three alloy classes examined the swelling resistance of the ferritics is the least sensitive to composition.

  4. Optimization of a microbial fuel cell for wastewater treatment using recycled scrap metals as a cost-effective cathode material.

    PubMed

    Lefebvre, Olivier; Tan, Zi; Shen, Yujia; Ng, How Y

    2013-01-01

    Microbial fuel cell (MFC) for wastewater treatment is still hindered by the prohibitive cost of cathode material, especially when platinum is used to catalyze oxygen reduction. In this study, recycled scrap metals could be used efficiently as cathode material in a specially-designed MFC. In terms of raw power, the scrap metals ranked as follows: W/Co > Cu/Ni > Inconel 718 > carpenter alloy; however, in terms of cost and long term stability, Inconel 718 was the preferred choice. Treatment performance--assessed on real and synthetic wastewater--was considerably improved either by filling the anode compartment with carbon granules or by operating the MFC in full-loop mode. The latter option allowed reaching 99.7% acetate removal while generating a maximum power of 36 W m(-3) at an acetate concentration of 2535 mg L(-1). Under these conditions, the energy produced by the system averaged 0.1 kWh m(-3) of wastewater treated.

  5. Wear studies of materials for tubes and antivibration bars in nuclear steam generators

    SciTech Connect

    Ko, P.L.; Taponat, M.C.; Zbinden, M.

    1996-08-01

    Wear occurs as a result of relative motion at the interface of two contacting bodies. In nuclear power steam generators, high flow rates can induce vibration of the tubes resulting in wear damage due to impact and sliding contacts between the tubes and their supports. A research project aiming to gain better understanding of the mechanisms and mechanics involved in vibratory wear and to develop a more versatile predictive wear model was carried out. Combinations of Inconel tubes against flat antivibration bars of 403 SS and electrolytic-chrome plated Inconel 600 were tested under conditions of reciprocating sliding and impacting in water at room temperature and at 250 C. The results show that, depending on the material combinations and the loading conditions, distinctively different wear mechanisms and often drastically different wear rates can occur.

  6. High-Temperature Oxidation Behavior of Two Nickel-Based Superalloys Produced by Metal Injection Molding for Aero Engine Applications

    NASA Astrophysics Data System (ADS)

    Albert, Benedikt; Völkl, Rainer; Glatzel, Uwe

    2014-09-01

    For different high-temperature applications like aero engines or turbochargers, metal injection molding (MIM) of superalloys is an interesting processing alternative. For operation at high temperatures, oxidation behavior of superalloys produced by MIM needs to match the standard of cast or forged material. The oxidation behavior of nickel-based superalloys Inconel 713 and MAR-M247 in the temperature interval from 1073 K to 1373 K (800 °C to 1100 °C) is investigated and compared to cast material. Weight gain is measured discontinuously at different oxidation temperatures and times. Analysis of oxidized samples is done via SEM and EDX-measurements. MIM samples exhibit homogeneous oxide layers with a thickness up to 4 µm. After processing by MIM, Inconel 713 exhibits lower weight gain and thinner oxide layers than MAR-M247.

  7. Tensile flow properties of Al-based matrix composites reinforced with a random planar network of continuous metallic fibers

    SciTech Connect

    Boland, F.; Salmon, C.; Delannay, F.; Colin, C.

    1998-11-20

    Squeeze casting was used for processing two new types of composites: pure Al matrix composites reinforced with fibers of Inconel 601, and AS13 (Al-12% Si) matrix composites reinforced with fibers of Inconel 601 or stainless steel 316L. The fibers are continuous with a diameter of 12 {micro}m and their volume fraction in the composites varied from 20 to 80%. The processing conditions were such that no trace of interfacial reaction compound or of matrix precipitate resulting from the dissolution of elements of the fibers could be detected. The quality of the process was attested by Young`s modulus and electrical conductivity measurements. Tensile tests were carried out from room temperature up to 300 C. The composites with the pure Al matrix present a remarkable tensile ductility. They thus constitute convenient materials for assessing continuum plasticity models for composites. Properties of composites with the AS13 matrix are much affected by interface adhesion strength.

  8. High temperature materials for radioactive waste incineration and vitrification. Revision 1

    SciTech Connect

    Bickford, D F; Ondrejcin, R S; Salley, L

    1986-01-01

    Incineration or vitrification of radioactive waste subjects equipment to alkaline or acidic fluxing, oxidation, sulfidation, carburization, and thermal shock. It is necessary to select appropriate materials of construction and control operating conditions to avoid rapid equipment failure. Nickel- and cobalt-based alloys with high chromium or aluminum content and aluminum oxide/chromium oxide refractories with high chromium oxide content have provided the best service in pilot-scale melter tests. Inconel 690 and Monofrax K-3 are being used for waste vitrification. Haynes 188 and high alumina refractory are undergoing pilot scale tests for incineration equipment. Laboratory tests indicate that alloys and refractories containing still higher concentrations of chromium or chromium oxide, such as Inconel 671 and Monofrax E, may provide superior resistance to attack in glass melter environments.

  9. Evaluation of Cyclic Behavior of Aircraft Turbine Disk Alloys

    NASA Technical Reports Server (NTRS)

    Shahani, V.; Popp, H. G.

    1978-01-01

    An evaluation of the cyclic behavior of three aircraft engine turbine disk materials was conducted to compare their relative crack initiation and crack propagation resistance. The disk alloys investigated were Inconel 718, hot isostatically pressed and forged powder metallurgy Rene '95, and as-hot-isostatically pressed Rene '95. The objective was to compare the hot isostatically pressed powder metallurgy alloy forms with conventionally processed superalloys as represented by Inconel 718. Cyclic behavior was evaluated at 650 C both under continuously cycling and a fifteen minute tensile hold time cycle to simulate engine conditions. Analysis of the test data were made to evaluate the strain range partitioning and energy exhaustion concepts for predicting hold time effects on low cycle fatigue.

  10. Effects of surface condition on the corrosion of candidate structural materials in a simulated HTGR-GT environment

    SciTech Connect

    Thompson, L.D.

    1980-02-01

    A simulated high-temperature gas-cooled reactor (HTGR) helium environment was used to study the effects of surface finish conditions on the subsequent elevated-temperature corrosion behavior of key candidate structural materials. The environment contained helium with 500 ..mu..atm H/sub 2//50 ..mu..atm CO/50 ..mu..atm CH/sub 4//<0.5 ..mu..atm H/sub 2/O at 900/sup 0/C with total test exposure durations of 3000 hours. Specimens with lapped, grit-blasted, pickled, and preoxidized surface conditions were studied. Materials tested included two cast superalloys, IN 100 and IN 713LC; one centrifugally cast high-temperature alloy, HK 40 one oxice-dispersion-strengthened alloy, Inconel MA 754; and three wrought high-temperature alloys, Hastelloy Alloy X, Inconel Alloy 617, and Alloy 800H.

  11. Magnetic imaging of superconducting tapes to determine current flow

    SciTech Connect

    Brown, G. W.; Hawley, M. E.; Foltyn, S. R.; Mueller, F. M.

    2001-01-01

    We have developed a magnetic imaging system that uses magnetoresistive read heads from computer hard disk drives to map the transport-current-induced magnetic field at the surface of superconducting tapes at liquid nitrogen temperature. Transport current pathways are determined from the 2-dimensional magnetic field maps using established inversion schemes. We examined the current flow in pulsed-laser-deposited YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} a films patterned on single crystal SrTiO{sub 3} substrates and on a textured yttria-stabilized-zirconia layer deposited on an Inconel ribbon by ion beam assisted deposition. The transport current densities in all cases were consistent with the Critical State Model. For the Inconel-based sample, the transport current density maps have allowed us to observe defects and determine the region that limits the current carrying capacity of the structure.

  12. Measurement of surface temperature and emissivity of different materials by two-colour pyrometry.

    PubMed

    Raj, Vinay C; Prabhu, S V

    2013-12-01

    An experimental investigation is performed to substantiate the capability of a charge coupled device camera to measure local temperature and emissivity of different materials heated to temperatures above 500 °C by two-colour pyrometric technique using colorimetric method. Materials investigated are Inconel 718 with pyromark (high temperature paint), Inconel 718, stainless steel SS 304 and SS 316. Centerline temperature and emissivity distribution is obtained for target plates maintained at constant temperature by AC heating while complete temperature and emissivity distribution is provided for plates heated by flame impingement. The obtained results are compared with a calibrated infrared camera and thermocouples and the temperature distribution is found to be in close agreement. These results pertain to partially oxidized metal alloys covered in this study. Deviation in the measurement of emissivity can be attributed to its dependence on wavelength range, oxidation, and sensitivity of the image detector.

  13. Measurement of surface temperature and emissivity of different materials by two-colour pyrometry

    NASA Astrophysics Data System (ADS)

    Raj, Vinay C.; Prabhu, S. V.

    2013-12-01

    An experimental investigation is performed to substantiate the capability of a charge coupled device camera to measure local temperature and emissivity of different materials heated to temperatures above 500 °C by two-colour pyrometric technique using colorimetric method. Materials investigated are Inconel 718 with pyromark (high temperature paint), Inconel 718, stainless steel SS 304 and SS 316. Centerline temperature and emissivity distribution is obtained for target plates maintained at constant temperature by AC heating while complete temperature and emissivity distribution is provided for plates heated by flame impingement. The obtained results are compared with a calibrated infrared camera and thermocouples and the temperature distribution is found to be in close agreement. These results pertain to partially oxidized metal alloys covered in this study. Deviation in the measurement of emissivity can be attributed to its dependence on wavelength range, oxidation, and sensitivity of the image detector.

  14. Experimental analysis of the pressure drop and heat transfer through metal foams used as volumetric receivers under concentrated solar radiation

    SciTech Connect

    Albanakis, C.; Missirlis, D.; Yakinthos, K.; Goulas, A.; Michailidis, N.; Omar, H.; Tsipas, D.; Granier, B.

    2009-01-15

    The main objective of this work was to evaluate the behavior of porous materials, when treated as volumetric receivers under concentrated solar radiation. For this reason various porous metallic and ceramic materials have been tested as potential receivers for concentrated solar radiation. The experimental investigation showed that their efficiency was depending on both materials parameters and flow conditions. In this work, a variety of foam materials such as Ni and Ni alloy, inconel, copper, aluminum and SiC with different open cell porosity were tested as potential media to be used as volumetric receivers and heat exchangers. However, since the results were similar, for space economy, only the results of two of them, nickel and inconel were presented in detail and compared with each other. (author)

  15. Spot weld attachment of thermocouples to a fuel rod cladding interior surface

    SciTech Connect

    Page, R.E.; Bates, S.O.; Pilger, J.P.

    1984-08-01

    Research was conducted by Pacific Northwest Laboratory to weld 0.020-inch-diameter thermocouples to the interior surface of Zircaloy 4 light-water reactor fuel cladding. Inconel sheathed Type K thermocouples were attached to fuel cladding to register cladding temperatures during loss-of-coolant accident testing. This report describes the development of welding parameters and the effects of thermocouple attachment on the burst strength and integrity of the cladding at temperatures up to 1550/sup 0/F.

  16. Deformation characteristics and time-dependent notch sensitivity of Udimet 700 at intermediate temperatures

    NASA Technical Reports Server (NTRS)

    Wilson, D. J.

    1974-01-01

    Time dependent notch sensitivity was observed in Udimet 700 sheet, bar, and investment castings between 1000 and 1400 F (538 -760 C), but not at 1600 F (871 C). As was the case for modified Waspaloy, Waspaloy and Inconel 718, it occurred in notched specimens loaded below the yield strength when the creep deformation was localized. For each alloy and notched specimen geometry, a stress-average particle size zone can be defined that characterizes the notch sensitive behavior.

  17. Advanced Manufacturing Technologies (AMT): Additive Manufactured Hot Fire Planning and Testing in GRC Cell 32 Project

    NASA Technical Reports Server (NTRS)

    Fikes, John C.

    2014-01-01

    The objective of this project is to hot fire test an additively manufactured thrust chamber assembly TCA (injector and thrust chamber). GRC will install the additively manufactured Inconel 625 injector, two additively manufactured (SLM) water cooled Cu-Cr thrust chamber barrels and one additively manufactured (SLM) water cooled Cu-Cr thrust chamber nozzle on the test stand in Cell 32 and perform hot fire testing of the integrated TCA.

  18. Laser-initiated combustion studies of selected aluminum, copper, iron, and nickel alloys

    NASA Technical Reports Server (NTRS)

    Bransford, J. W.; Clark, A. F.

    1981-01-01

    The results of combustion studies at atmospheric pressure on ten metal alloys are presented. The alloys studied were aluminum alloys 1100, 2219, 6061, and tensile-50; 304, 347 and 21-6-9 stainless steel; inconel 600; beryllium copper and a bronze. It was found that once ignition was achieved all alloys would generally burn to completion. The overall combustion process appears to obey a first order rate process. Preliminary conclusions are presented along with recommendations for future work.

  19. Failure analysis of a Stirling engine heat pipe

    NASA Technical Reports Server (NTRS)

    Moore, Thomas J.; Cairelli, James E.; Khalili, Kaveh

    1989-01-01

    Failure analysis was conducted on a heat pipe from a Stirling Engine test rig which was designed to operate at 1073 K. Premature failure had occurred due to localized overheating at the leading edge of the evaporator fin. It was found that a crack had allowed air to enter the fin and react with the sodium coolant. The origin of the crack was found to be located at the inner surface of the Inconel 600 fin where severe intergranular corrosion had taken place.

  20. Stress corrosion cracking of several high strength ferrous and nickel alloys

    NASA Technical Reports Server (NTRS)

    Nelson, E. E.

    1971-01-01

    The stress corrosion cracking resistance of several high strength ferrous and nickel base alloys has been determined in a sodium chloride solution. Results indicate that under these test conditions Multiphase MP35N, Unitemp L605, Inconel 718, Carpenter 20Cb and 20Cb-3 are highly resistant to stress corrosion cracking. AISI 410 and 431 stainless steels, 18 Ni maraging steel (250 grade) and AISI 4130 steel are susceptible to stress corrosion cracking under some conditions.

  1. Alloys For Corrosive, Hydrogen-Rich Environments

    NASA Technical Reports Server (NTRS)

    Mcpherson, William B.; Bhat, Biliyar N.; Chen, Po-Shou; Kuruvilla, A. K.; Panda, Binayak

    1993-01-01

    "NASA-23" denotes class of alloys resisting both embrittlement by hydrogen and corrosion. Weldable and castable and formed by such standard processes as rolling, forging, and wire drawing. Heat-treated to obtain desired combinations of strength and ductility in ranges of 100 to 180 kpsi yield strength, 120 to 200 kpsi ultimate tensile strength, and 10 to 30 percent elongation at break. Used in place of most common aerospace structural alloy, Inconel(R) 718.

  2. Volatilization of oxides during oxidation of some superalloys at 1200 C

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1977-01-01

    Volatilization of oxides during cyclic oxidation of commercial Nichrome, Inconel 750, Rene 41, Stellite 6B, and GE-1541 was studied at 1200 C in static air. Quantitative analysis of oxide vapor deposits revealed that oxides of tungsten, molybdenum, niobium, manganese, and chromium volatilized preferentially from the oxide scales. Aluminum and silicon were not detected in vapor deposits. For all the alloys except GE-1541, chromium was found to be the main metallic element in the oxide scales.

  3. Economic use of CBN grinding tools in the production of jet turbine components

    NASA Astrophysics Data System (ADS)

    Geisler, R.; Hallen, D.

    The use of cubical boron nitride (CBN) grinding wheels in the production of jet turbine components of superalloys such as Inconel 100, Nimonic 90 or Rene 120 with the aid of an example of guide vane machining for low pressure turbines is described. Cost savings achieved by the use of CBN wheels as compared with conventional grinding wheels and spark erosion are presented in tabular form.

  4. Phased Array Ultrasonic Examination of Space Shuttle Main Engine Nozzle Weld

    NASA Technical Reports Server (NTRS)

    James, S.; Engel, J.; Kimbrough, D.; Suits, M.; McCool, Alex (Technical Monitor)

    2001-01-01

    This paper describes a Phased Array Ultrasonic Examination that was developed for the examination of a limited access circumferential Inconel 718 fusion weld of a Space Shuttle Main Engine Nozzle - Cone. The paper discusses the selection and formation criteria used for the phased array focal laws, the reference standard that simulated hardware conditions, the examination concept, and results. Several unique constraints present during this examination included limited probe movement to a single axis and one-sided access to the weld.

  5. Fatigue, fracture, and life prediction criteria for composite materials in magnets

    SciTech Connect

    Wong, F.M.G.

    1990-06-01

    An explosively-bonded copper/Inconel 718/copper laminate conductor was proposed to withstand the severe face compression stresses in the central core of the Alcator C-MOD tokamak toroidal field (TF) magnet. Due to the severe duty of the TF magnet, it is critical that an accurate estimate of useful life be determined. As part of the effort to formulate an appropriate life prediction, fatigue crack growth experiments were performed on the laminate as well as its components. Metallographic evaluation of the laminate interface revealed many shear bands in the Inconel 718. Shear bands and shear band cracks were produced in the Inconel 718 as a result of the explosion bonding process. These shear bands were shown to have a detrimental effect on the crack growth behavior of the laminate, by significantly reducing the load carrying capability of the reinforcement layer and providing for easy crack propagation paths. Fatigue crack growth rate was found not only to be dependent on temperature but also on orientation. Fatigue cracks grew faster in directions which contained shear bands in the plane of the propagating crack. Fractography showed crack advancement by fatigue cracking in the Inconel 718 and ductile tearing of the copper at the interface. However, further away from the interfaces, the copper exhibited fatigue striations indicating that cracks were now propagating by fatigue. Laminate life prediction results showed a strong dependence on shear band orientation, and exhibited little variation between room temperature and 77{degree}K. Predicted life of this laminate was lower when the crack propagation was along a shear band than when crack propagation was across the shear bands. Shear bands appear to have a dominating effect on crack growth behavior.

  6. Superplastic forming of alloy 718

    SciTech Connect

    Smith, G.D.; Flower, H.L. )

    1994-04-01

    Inconel Alloy 718 (UNS N07718) is now available in a fine-grained, controlled composition modification that can be super-plastically formed. The new superplastic forming (SPF) capability allows the manufacture of large, complex, and detailed parts, which improves integrity by reducing the need for joining. Furthermore, it allows designers to fabricate components having higher strength, fatigue resistance, and temperature capability than parts made of aluminum or titanium alloys.

  7. Feasibility of using a high-level waste canister as an engineered barrier in disposal

    SciTech Connect

    Slate, S.C.; Pitman, S.G.; Nesbitt, J.F.; Partain, W.L.

    1982-08-01

    The objective of this report is to evaluate the feasibility of designing a process canister that could also serve as a barrier canister. To do this a general set of performance criteria is assumed and several metal alloys having a high probability of demonstrating high corrosion resistance under repository conditions are evaluated in a qualitative design assessment. This assessment encompasses canister manufacture, the glass-filling process, interim storage, transportation, and to a limited extent, disposal in a repository. A series of scoping tests were carried out on two titanium alloys and Inconel 625 to determine if the high temperature inherent in the glass-fill processing would seriously affect either the strength or corrosion resistance of these metals. This is a process-related concern unique to the barrier canister concept. The material properties were affected by the heat treatments which simulated both the joule-heated glass melter process (titanium alloys and Inconel 625) and the in-can melter (ICM) process (Inconel 625). However, changes in the material properties were generally within 20% of the original specimens. Accelerated corrosion testing of the heat treated coupons in a highly oxygenated brine showed basic corrosion resistance of titanium grade 12 and Inconel 625 to compare favorably with that of the untreated coupons. The titanium grade 2 coupons experienced severe corrosion pitting. These corrosion tests were of a scoping nature and suitable primarily for the detection of gross sensitivity to the heat treatment inherent in the glass-fill process. They are only suggstive of repository performance since the tests do not adequately model the wide range of repository conditions that could conceivably occur.

  8. Simulation of gas particle flow in a HVOF torch

    SciTech Connect

    Chang, C.H.; Moore, R.L.

    1995-12-31

    A transient two-dimensional numerical simulation of Inconel spraying in an HVOF torch barrel has been performed. The gas flow is treated as a continuum multicomponent chemically reacting flow, while particles are modeled using a stochastic particle spray model, fully coupled to the gas flow. The calculated results agree well with experimental data, and show important statistical aspects of particle flow in the torch.

  9. Fabrication of prepackaged superalloy honeycomb Thermal Protection System (TPS) panels

    NASA Technical Reports Server (NTRS)

    Blair, W.; Meaney, J. E.; Rosenthal, H. A.

    1985-01-01

    High temperature materials were surveyed, and Inconel 617 and titanium were selected for application to a honeycomb TPS configuration designed to withstand 2000 F. The configuration was analyzed both thermally and structurally. Component and full-sized panels were fabricated and tested to obtain data for comparison with analysis. Results verified the panel design. Twenty five panels were delivered to NASA Langley Research Center for additional evaluation.

  10. Vacuum plasma spray applications on liquid fuel rocket engines

    NASA Astrophysics Data System (ADS)

    McKechnie, T. N.; Zimmerman, F. R.; Bryant, M. A.

    1992-07-01

    The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z, combustion chamber liners, and structural nickel base material, Inconel 718, for nozzle and combustion chamber support jackets.

  11. Production of Gas-Solid Structures in Aluminum and Nickel Alloys by Gasar Processing

    SciTech Connect

    Apprill, J.M.; Baldwin, M.D.; Maguire, M.C.; Miszkiel, M.E.; Shapovalov, V.I.

    1999-01-06

    Experimental data on directional and bulk solidification of hydrogen-charged samples of aluminum alloy A356 and nickel alloy Inconel 718 are discussed. The solidification structure of the porous zone is shown to be dependent on many process variables. Of these variables, hydrogen content in the melt prior to solidification, and furnace atmospheric pressure during solidification play the decisive role. Also important are the furnace atmosphere composition, the solidification velocity, and the temperature distribution of the liquid metal inside the mold.

  12. Determination of the relative resistance to ignition of selected turbopump materials in high-pressure, high-temperature, oxygen environments, volume 3

    NASA Technical Reports Server (NTRS)

    Stoltzfus, Joel M.; Benz, Frank J.

    1986-01-01

    Data is presented from frictional heating tests on pairs of different materials. Materials tested include: Hastelloy X, Inconel 600, Invar 36, Monel K-500, Monel 400, nickel 200, silicon carbide, stainless steels 316, and zirconium copper. In tests where pairs of different materials were rubbed together, the material rated less resistant to ignition in previous tests appeared to control the resistance to ignition of the pair.

  13. Characteristics comparison of weld metal zones welded to cast and forged steels for piston crown material

    NASA Astrophysics Data System (ADS)

    Moon, Kyung-Man; Kim, Yun-Hae; Lee, Myeong-Hoon; Baek, Tae-Sil

    2015-03-01

    An optimum repair welding for the piston crown which is one of the engine parts exposed to the combustion chamber is considered to be very important to prolong the engine lifetime from an economical point of view. In this study, two types of filler metals such as 1.25Cr-0.5Mo, 0.5Mo were welded with SMAW method and the other two types of filler metals such as Inconel 625 and 718 were welded with GTAW method, respectively, and the used base metals were the cast and forged steels of the piston crown material. The weld metal zones welded with Inconel 625 and 718 filler metals exhibited higher corrosion resistance compared to 1.25Cr-0.5Mo and 0.5Mo filler metals. In particular, the weld metal zone welded with Inconel 718 and 0.5Mo, filler metals indicated the best and worst corrosion resistance, respectively. Consequently, it is suggested that the corrosion resistance of the weld metal zone surely depends on the chemical components of each filler metal and welding method irrespective of the types of piston crown material.

  14. Stress corrosion cracking of alloy 600 using the constant strain rate test

    SciTech Connect

    Bulischeck, T. S.; van Rooyen, D.

    1980-01-01

    The most recent corrosion problems experienced in nuclear steam generators tubed with Inconel alloy 600 is a phenomenon labeled ''denting''. Denting has been found in various degrees of severity in many operating pressurized water reactors. Laboratory investigations have shown that Inconel 600 exhibits intergranular SCC when subjected to high stresses and exposed to deoxygenated water at elevated temperatures. A research project was initiated at Brookhaven National Laboratory in an attempt to improve the qualitative and quantitative understanding of factors influencing SCC in high temperature service-related environments. An effort is also being made to develop an accelerated test method which could be used to predict the service life of tubes which have been deformed or are actively denting. Several heats of commercial Inconel 600 tubing were procured for testing in deaerated pure and primary water at temperatures from 290 to 365/sup 0/C. U-bend type specimens were used to determine crack initiation times which may be expected for tubes where denting has occurred but is arrested and provide baseline data for judging the accelerating effects of the slow strain rate method. Constant extension rate tests were employed to determine the crack velocities experienced in the crack propagation stage and predict failure times of tubes which are actively denting. 8 refs., 17 figs., 5 tabs.

  15. Electron emission from nickel-alloy surfaces in cesium vapor

    NASA Technical Reports Server (NTRS)

    Manda, M.; Jacobson, D.

    1978-01-01

    An experimental apparatus and measurement techniques are described for measuring the thermionic emission from cesium-activated materials having adequate high-temperature properties such as creep strength and corrosion resistance, which might ultimately reduce the cost of thermionic converters. The electron emission characteristics are measured for nickel, Inconel 600, and Hastelloy X probes with a 412 K cesium reservoir. It is found that the nickel alloys exhibit a peak electron emission 1.4 to 2.1 times greater than pure nickel. Both the Inconel and the Hastelloy samples have work functions of 1.64 eV at peak emission. The minimum cesiated work functions are estimated to be 1.37 eV for Inconel at a probe temperature of 750 K and 1.4 eV for Hastelloy at a probe temperature of 665 K. The bare work functions for both alloys is estimated to be about the same as for pure nickel, 4.8 eV.

  16. Effect of Heating Rate on the Pressureless Sintering Densification of a Nickel-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Levasseur, David; Brochu, Mathieu

    2016-05-01

    Pressureless sintering of Inconel 718 has important technological applications for the densification of metal injection molding or additive manufacturing of parts with powder/binder systems. The effect of heating rates ranging from 15 to 200 K/minute on the sintering behavior of fine (-325 mesh) Inconel 718 powders was studied using the master sintering curve (MSC) concept. A pressureless pulsed electric current sintering setup was used to heat samples. The temperature at the onset of sintering increased as the heating rate increased. The formation of a supersolidus liquid fraction was shifted toward higher temperatures for increased heating rates. The apparent activation energy of sintering was obtained by least squares fitting of the sintering data to the MSC and was in good agreement with the lattice diffusion activation energy of the alloying elements present in Inconel 718. The MSC followed different kinetics for low heating rates (≤50 K/minute) and high heating rates (≥75 K/minute), and these differences were related to liquation kinetics.

  17. Spray automated balancing of rotors: Methods and materials

    NASA Technical Reports Server (NTRS)

    Smalley, Anthony J.; Baldwin, Richard M.; Schick, Wilbur R.

    1988-01-01

    The work described consists of two parts. In the first part, a survey is performed to assess the state of the art in rotor balancing technology as it applies to Army gas turbine engines and associated power transmission hardware. The second part evaluates thermal spray processes for balancing weight addition in an automated balancing procedure. The industry survey reveals that: (1) computerized balancing equipment is valuable to reduce errors, improve balance quality, and provide documentation; (2) slow-speed balancing is used exclusively, with no forseeable need for production high-speed balancing; (3) automated procedures are desired; and (4) thermal spray balancing is viewed with cautious optimism whereas laser balancing is viewed with concern for flight propulsion hardware. The FARE method (Fuel/Air Repetitive Explosion) was selected for experimental evaluation of bond strength and fatigue strength. Material combinations tested were tungsten carbide on stainless steel (17-4), Inconel 718 on Inconel 718, and Triballoy 800 on Inconel 718. Bond strengths were entirely adequate for use in balancing. Material combinations have been identified for use in hot and cold sections of an engine, with fatigue strengths equivalent to those for hand-ground materials.

  18. Robotic weld overlay coatings for erosion control

    NASA Astrophysics Data System (ADS)

    Levin, B. F.; Dupont, J. N.; Marder, A. R.

    1994-01-01

    Research is being conducted to develop criteria for selecting weld overlay coatings for erosion mitigation in circulated fluidized beds. Twelve weld overlay alloys were deposited on 1018 steel substrates using plasma arc welding. Ten samples from each coating were prepared for erosion testing. All selected coatings were erosion tested at 400C and their erosion resistance and microstructure evaluated. Steady state erosion rates were similar for several weld overlay coatings (Ultimet, Inconel-625, Iron-Aluminide, 316L SS, and High Chromium Cast Iron) and were considerably lower than the remaining coating evaluated. These coatings had different base (Co, Fe, Ni-base). No correlations were found between room temperature microhardness of the weld overlay coatings and their erosion resistance at elevated temperature, although this criteria is often thought to be an indicator of erosion resistance. It was suggested that the coatings that showed similar erosion rates may have similar mechanical properties such as fracture strength, toughness and work hardening rates at this temperature. During the past quarter, Iron-Aluminide, Inconel-625, and 316L SS coatings were selected for more detailed investigations based upon the preliminary erosion test results. Microhardness tests were performed on eroded samples to determine the size of the work hardened zone and change in coatings hardness due to erosion. The work hardened zone was correlated with erosion resistance of the coatings. Additional Iron-Aluminide, Inconel-625, and 316L SS coatings were deposited on 1018 steel substrates.

  19. Robotic weld overlay coatings for erosion control. Quarterly progress report, October 1993--December 1993

    SciTech Connect

    Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1994-01-20

    Research is being conducted to develop criteria for selecting weld overlay coatings for erosion mitigation in Circulated Fluidized Beds. Twelve weld overlay alloys were deposited on 1018 steel substrates using plasma arc welding. Ten samples from each coating were prepared for erosion testing. All selected coatings were erosion tested at 400C and their erosion resistance and microstructure evaluated. Steady state erosion rates were similar for several weld overlay coatings (Ultimet, Inconel-625, Iron-Aluminide, 316L SS, and High Chromium Cast Iron) and were considerably lower than the remaining coating evaluated. These coatings had different base (Co, Fe, Ni-base). No correlations were found between room temperature microhardness of the weld overlay coatings and their erosion resistance at elevated temperature, although this criteria is often thought to be an indicator of erosion resistance. It was suggested that the coatings that showed similar erosion rates may have similar mechanical properties such as fracture strength, toughness and work hardening rates at this temperature. During the past quarter, Iron-Aluminide, Inconel-625, and 316L SS coatings were selected for more detailed investigations based upon the preliminary erosion test results. Microhardness tests were performed on eroded samples to determine the size of the work hardened zone and change in coatings hardness due to erosion. The work hardened zone was to correlated with erosion resistance of the coatings. Additional Iron-Aluminide, Inconel-625, and 316L SS coatings were deposited on 1018 steel substrates.

  20. Studies of impurity behavior in TFTR

    SciTech Connect

    Hill, K.W.; Bitter, M.; Bretz, N.L.; Diesso, M.; Efthimion, P.C.; Von Goeler, S.; Kiraly, J.; Ramsey, A.T.; Sauthoff, N.R.; Schivell, J.

    1986-03-01

    Central medium- and low-Z impurity concentrations and Z/sub eff/ have been measured by x-ray spectrometry in Tokamak Fusion Test Reactor discharges during three periods of operation. These were the (1) start-up period, (2) ohmic heating, and (3) ohmic heating portion of the two neutral beam periods, distinguished mainly by different vacuum vessel internal hardware and increasing plasma current and toroidal field capability. Plasma parameters spanned minor radius a = 0.41 - 0.83 m, major radius R = 2.1 - 3.1 m, current I/sub p = 0.25 - 2.0 MA, line-averaged electron density n-bar/sub e/ = 0.9 - 4.0 x 10/sup 19/ m/sup -3/, and toroidal magnetic field B/sub T/ = 1.8 - 4.0 T. The metal impurities came mostly from the limiter. At low densities titanium or nickel approached 1% of n/sub e/ during operation on a TiC-coated graphite or Inconel limiter, respectively. Lower levels of Cr, Fe, and Ni (less than or equal to0.1%) were observed with a graphite limiter at similarly low densities; these elements were removed mainly from stainless steel or Inconel hardware within the vacuum vessel during pulse discharge cleaning or plasma operation on an Inconel limiter and then deposited on the graphite limiter. Hardware closest to the graphite limiter contributed most to the deposits.

  1. The effects of low dose rate irradiation and thermal aging on reactor structural alloys

    NASA Astrophysics Data System (ADS)

    Allen, T. R.; Trybus, C. L.; Cole, J. I.

    As part of the EBR-II reactor materials surveillance program, test samples of fifteen different alloys were placed into EBR-II in 1965. The surveillance (SURV) program was intended to determine property changes in reactor structural materials caused by irradiation and thermal aging. In this work, the effect of low dose rate (approximately 2 × 10 -8 dpa/s) irradiation at 380-410°C and long term thermal aging at 371°C on the properties of 20% cold worked 304 stainless steel, 420 stainless steel, Inconel X750, 304/308 stainless weld material, and 17-4 PH steel are evaluated. Doses of up to 6.8 dpa and thermal aging to 2994 days did not significantly affect the density of these alloys. The strength of 304 SS, X750, 17-4 PH, and 304/308 weld material increased with irradiation. In contrast, the strength of 420 stainless steel decreased with irradiation. Irradiation decreased the impact energy in both Inconel X750 and 17-4 PH steel. Thermal aging decreased the impact energy in 17-4 PH steel and increased the impact energy in Inconel X750. Tensile property comparisons of 304 SURV samples with 304 samples irradiated in EBR-II at a higher dose rate show that the higher dose rate samples had greater increases in strength and greater losses in ductility.

  2. Permeability of hydrogen isotopes through nickel-based alloys

    SciTech Connect

    Edge, E.M.; Mitchell, D.J.

    1983-04-01

    Permeabilities and diffusivities of deuterium in several nickel-based alloys were measured in this investigation. Measurements were made by the gas-phase breakthrough technique in the temperature range 200 to 450/sup 0/C with applied pressures ranging from 1 to 100 kPa. The results were extrapolated to predict the permeabilities (K) of the alloys at room temperature. The alloy with the smallest deuterium permeability is Carpenter 49, for which K = 4.3 x 10/sup -18/ mol s/sup -1/ m/sup -1/ Pa/sup -//sup 1/2/ at 22/sup 0/C. The permeability of deuterium in Kovar or Ceramvar is about 80% greater than that for Carpenter 49. Premeabilities of Inconel 625, Inconel 718, Inconel 750 and Monel K-500 are all equal to about 5 x 10/sup -17/ mol m/sup -1/ s/sup -1/ Pa/sup -//sup 1/2/ at 22/sup 0/C. The validity (from a statistical standpoint) of the extrapolation of the permeabilities to room temperature is considered in detail. Published permeabilities of stainless steels and nickel-iron alloys are also reviewed. The greatest differences in permeabilities among the nickel-based alloys appear to be associated with the tendency for some alloys to form protective oxide layers. Permeabilities of deuterium through laminates containing copper are smaller than for any of the iron-nickel alloys.

  3. High temperature erosion of nickel alloys

    SciTech Connect

    Zhou, J.

    1995-12-31

    High temperature erosion behavior was studied on three commercial nickel alloys, Inconel 718, Inconel 601 and Inconel X-750, using a vertical sand-blast type of erosion test rig. Effect of temperature on erosion was investigated by varying test temperature in six steps from ambient up to 800 C. Other erosion variables investigated included impingement angle, changed from 10{degree} to 90{degree}, and impingement velocity, covered a range of 40 to 90 m/s. Extensive studies on erosion surface morphological features were done on eroded or eroded-corroded specimen surfaces using scanning electron microscopy. Thermogravimetric analysis and scratch test revealed corrosion rate, characteristics of oxide scale formed at high temperature, and some effects of corrosion on erosion. It was found that variation of erosion rate with temperature was directly related to temperature-dependent mechanical property changes of the materials. The mechanisms of the high-temperature erosion were analyzed based on test results. It was observed that erosion was dominant in temperature range up to 800 C, while corrosion played increased roles in upper portion of the temperature range tested.

  4. Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNO/sub 3/-HF

    SciTech Connect

    Ondrejcin, R.S.; McLaughlin, B.D.

    1980-04-01

    Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNO/sub 3/-HF for dissolution, the best alloy for service at 130/sup 0/C when complexing agents for fluoride are used is Inconel 690; with no complexing agents at 130/sup 0/C, Inconel 671 is best. At 95/sup 0/C, six other alloys tested would be adequate: Haynes 25, Ferralium, Inconel 625, Type 304L stainless steel, Incoloy 825, and Haynes 20 (in order of decreasing preference); based on composition, six untested alloys would also be adequate. The ions most effective in reducing fluoride corrosion were the complexing agents Zr/sup 4 +/ and Th/sup 4 +/; Al/sup 3 +/ was less effective. With uranium fuel, modestly priced Type 304L stainless steel is adequate. Corrosion will be most severe in HNO/sub 3/-HF used occasionally for flushing and in solutions of HNO/sub 3/ and corrosion products (ferric and dichromate ions). HF corrosion can be minimized by complexing the fluoride ion and by passivation of the steel with strong nitric acid. Corrosion caused by corrosion products can be minimized by operating at lower temperatures.

  5. Attack of high-strength, oxidation-resistant alloys during in-can melting of simulated waste glasses

    SciTech Connect

    Rankin, W.N.

    1980-01-01

    The restistance of candidate canister alloys to penetration under the most severe conditions expected during in-can melting was directly proportional to the chromium content of the alloy, and inversely proportional to the Na/sub 2/O content of the glass melt. Specimens were exposed for 24 hours, which is the time required for in-can melting full-size waste-glass forms based on tests carried out at Pacific Northwest Laboratories (PNL) and at SRL. The penetration resistance to Frit 211 at 1150/sup 0/C for 24 hours of most alloys tested was satisfactory. The amount of penetration would not affect the integrity of the waste form. Inconel 625, Hastelloy X, and Inconel 601 were penetrated < 20 mils. This was considered excellent. Incoloy 801, Type 310 stainless steel, Type 304L stainless steel, Inconel 600, and Type 347 stainless steel were penetrated < 40 mils. This was considered good. Hastelloy C-4 was penetrated > 100 mils by a glass composed of 65 wt % Frit 21 and 35 wt % composite sludge (with uranium) at 1150/sup 0/C for only 7 hours. This amount of penetration of an in-can melting canister would not be satisfactory. 12 figures.

  6. Compositionally Graded Thermal Barrier Coating by Hybrid Thermal Spraying Route and its Non-isothermal Oxidation Behavior

    NASA Astrophysics Data System (ADS)

    Nath, Subhasisa; Manna, Indranil; Dutta Majumdar, Jyotsna

    2013-08-01

    The present study concerns a detailed investigation of the characteristics and oxidation resistance property of a duplex and compositionally graded thermal barrier coating on Inconel 718. The duplex coating consists of a CoNiCrAlY bond coat layer sprayed on to sand-blasted Inconel 718 substrate (by high velocity oxy-fuel spraying) followed by deposition of a yttria-stabilized zirconia (YSZ) top coat by plasma spraying. The compositionally graded coating consists of several layers deposited by plasma spraying of pre-mixed CoNiCrAlY and YSZ powders in the weight ratios of 70:30, 50:50, 30:70, and 0:100 varying from the bond coat to the top surface, respectively. A detailed investigation of the microstructure, composition, and phases in the coating and its non-isothermal oxidation behavior from room temperature to 1250°C was performed. Oxidation proceeds by three stages in the as-received Inconel 718 and the compositionally graded coating, but by two stages in the duplex coating with a maximum activation energy for oxidation in the compositionally graded coating at high temperature (stage III). The kinetics and mechanism of oxidation were established.

  7. Study of metal corrosion using ac impedance techniques in the STS launch environment

    NASA Technical Reports Server (NTRS)

    Calle, Luz M.

    1989-01-01

    AC impedance measurements were performed to investigate the corrosion resistance of 19 alloys under conditions similar to the STS launch environment. The alloys were: Zirconium 702, Hastelloy C-22, Inconel 625, Hastelloy C-276, Hastelloy C-4, Inconel 600, 7Mo + N, Ferralium 255, Inco Alloy G-3, 20Cb-3, SS 904L, Inconel 825, SS 304LN, SS 316L, SS 317L, ES 2205, SS 304L, Hastelloy B-2, and Monel 400. AC impedance data were gathered for each alloy after one hour immersion time in each of the following three electrolyte solutions: 3.55 percent NaCl, 3.55 percent NaCl-0.1N HCl, and 3.55 percent NaCl-1.0N HCl. The data were analyzed qualitatively using the Nyquist plot and quantitatively using the Bode plot. Polarization resistance, Rp, values were obtained using the Bode plot. Zirconium 702 was the most corrosion resistant alloy in the three electrolytes. The ordering of the other alloys according the their resistance to corrosion varied as the concentration of hydrochloric acid in the electrolyte increased. The corrosion resistance of Zirconium 702 and Ferralium 255 increased as the concentration of hydrochloric acid in the electrolyte increased. The corrosion resistance of the other 17 alloys decreased as the concentration of the hyrdochloric acid in the electrolyte increased.

  8. The influence of laser alloying on the structure and mechanical properties of AlMg5Si2Mn surface layers

    NASA Astrophysics Data System (ADS)

    Pakieła, W.; Tański, T.; Brytan, Z.; Labisz, K.

    2016-04-01

    The goal of this paper was focused on investigation of microstructure and properties of surface layer produced during laser surface treatment of aluminium alloy by high-power fibre laser. The performed laser treatment involves remelting and feeding of Inconel 625 powder into the aluminium surface. As a base metal was used aluminium alloy AlMg5Si2Mn. The Inconel powder was injected into the melt pool and delivered by a vacuum feeder at a constant rate of 4.5 g/min. The size of Inconel alloying powder was in the range 60-130 µm. In order to remelt the aluminium alloy surface, the fibre laser of 3 kW laser beam power has been used. The linear laser scan rate of the beam was set 0.5 m/min. Based on performed investigations, it was possible to obtain the layer consisting of heat-affected zone, transition zone and remelted zone, without cracks and defects having much higher hardness value compared to the non-alloyed material.

  9. Hydrogen Induced Stress Cracking of Materials Under Cathodic Protection

    NASA Astrophysics Data System (ADS)

    LaCoursiere, Marissa P.

    Hydrogen embrittlement of AISI 4340, InconelRTM 718, Alloy 686 and Alloy 59 was studied using slow strain rate tests of both smooth and notched cylindrical specimens. Two heat treatments of the AISI 4340 material were used as a standard for two levels of yield strength: 1479 MPa, and 1140 MPa. A subset of the 1140 MPa AISI 4340 material also underwent plasma nitriding. The InconelRTM 718 material was hardened following AMS 5663M to obtain a yield strength of 1091 MPa. The Alloy 686 material was obtained in the Grade 3 condition with a minimum yield strength of 1034 MPa. The Alloy 59 material was obtained with a cold worked condition similar to the Alloy 686 and with a minimum yield strength of 1034 MPa. Ninety-nine specimens were tested, including smooth cylindrical tensile test specimens and smooth and notched cylindrical slow strain rate tensile tests specimens. Testing included specimens that had been precharged with hydrogen in 3.5% NaCl at 50°C for 2 weeks (AISI 4340), 4 weeks (InconelRTM 718, Alloy 686, Alloy 59) and 16 weeks (InconelRTM 718, Alloy 686, Alloy 59) using a potentiostat to deliver a cathodic potential of -1100 mV vs. SCE. The strain rate over the gauge section for the smooth specimens and in the notch root for the notched specimens was 1 x 10-6 /s. It was found that the AISI 4340 was highly embrittled in simulated ocean water when compared to the nickel based superalloys. The higher strength AISI 4340 showed much more embrittlement, as expected. Testing of the AISI 4340 at both 20°C and 4°C showed that the temperature had no effect on the hydrogen embrittlement response. The InconelRTM 718 was highly embrittled when precharged, although it only showed low levels of embrittlement when unprecharged. Both the Alloy 686 and Alloy 59 showed minimal embrittlement in all conditions. Therefore, for the materials examined, the use of Alloy 686 and Alloy 59 for components in salt water environments when under a cathodic potential of -1100 mV vs. SCE is

  10. FINAL REPORT TESTING OF IRON PHOSPHATE LAW GLASS (VSL-11R2340-1) 04/25/2011 REV 0 06/10/2011

    SciTech Connect

    KRUGER AA; GAN H ET AL; JOSEPH I; BEUCHELE AC; FENG Z; WANG C; VIRAGHC; PEGG IL

    2011-08-31

    About 50 million gallons of high-level mixed waste is currently stored in underground tanks at The United States Department of Energy's (DOE's) Hanford site in the State of Washington. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) will provide DOE's Office of River Protection (ORP) with a means of treating this waste by vitrification for subsequent disposal. The tank waste will be separated into low- and high-activity waste fractions, which will then be vitrified respectively into Immobilized Low Activity Waste (ILAW) and Immobilized High Level Waste (IHLW) products. The ILAW product will be disposed in an engineered facility on the Hanford site while the IHLW product will likely be directed to a national deep geological disposal facility for high-level nuclear waste. The ILA W and IHLW products must meet a variety of requirements with respect to protection of the environment before they can be accepted for disposal. The objectives of the work reported herein were to assess the corrosion of Inconel 690 and 693 in the FeP glass developed by MS&T and to measure key high temperature properties of the LAW iron phosphate glass. Specific objectives of these tests were the following: (1) Determination of the extent of corrosion of Inconel 690 and 693 in LAW FeP glass at 1050, 1l00, and 1150 C; (2) Determination of the extent of corrosion of Inconel 690 and 693 in LAW FeP glass in the presence of an electric field; (3) Measurement of the high temperature specific heat of the LAW FeP glass; (4) Measurement of the high temperature density of the LAW FeP glass; (5) Measurement of the high temperature thermal diffusivity of the LAW FeP glass; and (6) Calculation of the high temperature thermal conductivity of the LAW FeP glass from the above three measured properties.

  11. Through bulkhead initiator studies

    SciTech Connect

    Begeal, D.R.

    1997-03-01

    This report describes recent work done to demonstrate feasibility of a fail-safe Through Bulkhead Initiator with minimum dimensions and suitable for use in cyclical thermal environments. Much of the ground work for a fail-safe TBI was previously done by A.C. Schwartz. This study is an expansion of Schwartz`s work to evaluate devices with bulkheads of 304 stainless steel and Inconel 718; explosive donors of PETN, BNCP, and a 0.005 inch thick steel flying plate donor traveling at 2.6 mm/{micro}s; and explosive acceptors of PETN and BNCP. Bulkhead thickness were evaluated in the range of 0.040 to 0.180 inch. The explosive acceptors initiated a small HMX pellet to drive a 0.005 inch thick steel flying plate, and VISAR histories of the HMX-driven flying plates were the measure of acceptable performance. A companion set of samples used a PMMA acceptor to measure the particle velocities at the bulkhead/PMMA interface with VISAR. These data were used to compute the input pressure to the acceptor explosives in an attempt to measure initiation threshold. Unfortunately, the range of bulkhead thicknesses tested did not give any failures, thus the threshold was not determined. It was found that either explosive or the flying plate would perform as a TBI in the bulkhead thickness range tested. The optimum TBI is about 0.060 inches thick, and steel bulkheads seem to be more structurally sound than those made of Inconel. That is, cross section views of the Inconel bulkheads showed it to be more prone to stress cracking than was the 304 stainless steel. Both PETN and BNCP showed good performance when tested at {minus}65 F following thermal cycling of {minus}65 F to +165 F. Analysis of the TBI function times showed that BNCP acceptor explosives were undergoing the classical deflagration to detonation process. The PETN acceptors were undergoing prompt detonation.

  12. Development of a Forced-Convection Liquid-Fluoride-Salt Test Loop

    SciTech Connect

    Yoder Jr, Graydon L; Wilson, Dane F; Peretz, Fred J; Wilgen, John B; Romanoski, Glenn R; Kisner, Roger A; Holcomb, David Eugene; Heatherly, Dennis Wayne; Aaron, Adam M

    2010-01-01

    A small forced-convection molten-fluoride-salt loop is being constructed at Oak Ridge National Laboratory to examine the heat transfer behavior of FLiNaK salt in a heated pebble bed. Objectives of the experiment include reestablishing infrastructure needed for fluoride-salt loop testing, developing a unique inductive heating technique for performing heat transfer (or other) experiments, measuring heat transfer characteristics in a liquid-fluoride-salt-cooled pebble bed, and demonstrating the use of silicon carbide (SiC) as a structural component for salt systems. The salt loop will consist of an Inconel 600 piping system, a sump-type pump, a SiC test section, and an air-cooled heat exchanger, as well as auxiliary systems needed to pre-heat the loop, transport salt into and out of the loop, and maintain an inert cover gas over the salt. A 30,000 Hz inductive heating system will be used to provide up to 250 kW of power to a 15 cm diameter SiC test section containing a packed bed of 3 cm graphite spheres. A SiC-to-Inconel 600 joint will use a conventional nickel/grafoil spiral wound gasket sandwiched between SiC and Inconel flanges. The loop system can provide up to 4.5 kg/s of salt flow at a head of 0.125 MPa and operate at a pressure just above atmospheric. Pebble Reynolds numbers of up to 2600 are possible with this configuration. A sump system is provided to drain and store the salt when not in use. Instrumentation on the loop will include pressure, temperature, and flow measurements, while the test section will be instrumented to provide pebble and FLiNaK temperatures.

  13. Lubricating Properties of Ceramic-Bonded Calcium Fluoride Coatings on Nickel-Base Alloys from 75 to 1900 deg F

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1962-01-01

    The endurance life and the friction coefficient of ceramic-bonded calcium fluoride (CaF2) coatings on nickel-base alloys were determined at temperatures from 75 F to 1900 F. The specimen configuration consisted of a hemispherical rider (3/16-in. rad.) sliding against the flat surface of a rotating disk. Increasing the ambient temperature (up to 1500 F) or the sliding velocity generally reduced the friction coefficient and improved coating life. Base-metal selection was critical above 1500 F. For instance, cast Inconel sliding against coated Inconel X was lubricated effectively to 1500 F, but at 1600 F severe blistering of the coatings occurred. However, good lubrication and adherence were obtained for Rene 41 sliding against coated Rene 41 at temperatures up to 1900 F; no blisters developed, coating wear life was fairly good, and the rider wear rate was significantly lower than for the unlubricated metals. Friction coefficients were 0.12 at 1500 F, 0.15 at 1700 F, and 0.17 at 1800 F and 1900 F. Because of its ready availability, Inconel X appears to be the preferred substrate alloy for applications in which the temperature does not exceed 1500 F. Rene 41 would have to be used in applications involving higher temperatures. Improved coating life was derived by either preoxidizing the substrate metals prior to the coating application or by applying a very thin (less than 0.0002 in.) burnished and sintered overlay to the surface of the coating. Preoxidation did not affect the friction coefficient. The overlay generally resulted in a higher friction coefficient than that obtained without the overlay. The combination of both modifications resulted in longer coating life and in friction coefficients intermediate between those obtained with either modification alone.

  14. Redox control of electric melters with complex feed compositions. Part II: preliminary limits for radioactive waste melters

    SciTech Connect

    Bickford, D F; Diemer, Jr, R B; Iverson, D C

    1985-01-01

    Melter redox control is necessary for safe and continued melter operation. A combination of feed composition control, melter operational controls and monitors, and periodic determination of product glass redox state is sufficient to meet operating and safety requirements. Mossbauer spectroscopy, or other methods which determine the Fe(II)/Fe(III) ratio of the glass product, can be used to determine the oxidation state of the glass and thereby assess operating conditions. Slightly reducing conditions can eliminate radio-Ru volatility by suppressing the formation of RuO4. Reducing conditions also limit foaming resulting from the release of oxygen as transition metal oxides are dissolved in the melt. The calcination and partial combustion of organic compounds in the melter feed generates combustible mixtures of CO, H2 and benzene. The organics must be essentially completely incinerated to avoid the accumulation of combustible offgas mixtures, and prevent fouling of the equipment by soot and tars. Operation of the melter plenum above the autoignition temperature, metering in of purge air in excess of that required for complete combustion, and dilution by water vapor from reacted feed all preclude this occurrence in the melter. Prevention of dangerous offgas compositions after water vapor removal is assured by combustion in the melter, the addition of dilution air, and by continuous monitoring by % Lower Explosive Limit meters. Melter reducing power must be restricted to prevent formation of molten sulfides or selenides in the melter, and to prevent carburization and sulfidation attack of Inconel-690 melter components. Control of average oxygen partial pressure in the melter plenum is insufficient to assure prevention of localized attack of Inconel-690. An additional requirement is therefore necessary, that no soot or tarry substances be deposited on the Inconel-690.

  15. Permeability of Candidate Stirling Heater Head Materials Measured

    NASA Technical Reports Server (NTRS)

    Freedman, Marc R.; Singh, Mrityunjay

    2005-01-01

    Researchers at the NASA Glenn Research Center are evaluating high-temperature materials for Stirling heater heads for second- and third-generation Stirling radioisotope power systems that would help to increase the system efficiency to 30 to 35 percent and the system specific power to 8 to 10+ W/kg. Ceramic materials could make it possible for the convertor hot-end temperature to be increased to 1050 to 1200 C, in comparison to the current 650 C with an Inconel 718 heater head. A hermetically sealed Stirling heater head must retain a constant internal pressure of nearly 400-psi helium (He) throughout its useful life (120,000 hr) at the design operating temperature. Therefore, He permeability was measured for eight potential materials and compared with the permeability of the current heater head material, Inconel 718. The eight materials included silicon nitride (Si3N4), silicon dioxide (SiO2), both sintered and chemical vapor deposited (CVD) silicon carbide (SiC), alumina (Al2O3), two types of melt-infiltrated (MI) SiC/SiC composites, and a carbon/SiC composite (C/SiC). Glenn submitted samples of each material to Porous Materials, Inc., Ithaca, New York, for permeability analysis. At room temperature and 30-psi He, four materials--Si3N4, Al2O3, SiO2, and sintered SiC--demonstrated lower permeability than Inconel 718. The CVD SiC and all the composite materials were significantly more permeable to He than the baseline material.

  16. The corrosion of some superalloys in contact with coal chars in coal gasifier atmospheres

    SciTech Connect

    Douglas, D.L.; Bhide, V.S.; Vineberg, E.

    1981-08-01

    Six alloys, 310 stainless steel, Hastelloy X, Inconel 671, Incoloy 800, Haynes 188, and FeCrAlY (GE1541 and MA956), were corroded in two chars at 160/sup 0/C and 1800/sup 0/C. The chars, FMC and Husky, contained 2.7% and 0.9% sulfur, respectively. Various parameters were investigated, including char size, cover gas, char quantity, char replenishment period, gas composition, and the use of coatings. The corrosion process was strictly sulfidation when the char was replenished every 24 hr or less. The kinetics of reaction were nearly linear with time. The reaction resulted in thick external sulfide scales with extensive internal sulfidation in the substrate. The kinetics and reaction-product morphologies suggested that diffusion through the sulfide scale played a minor role, and that an interfacial reaction was the rate-controlling step. A mathematical model was developed which supported this hypothesis. The reaction rates showed a relatively minor role on alloy composition, depending upon whether the alloys were tested singularly or in combination with others. Inconel 671, the best alloy in CGA environments, consistently corroded the most rapidly of the chromia-former types regardless of char sulfur content or of the temperature. Type 310 stainless was marginally better than Inconel 671. Incoloy 800 was intermediate, wheras, Haynes 188 and Hastelloy X exhibited the best corrosion resistance. The FeCrAlY alloys reacted very rapidly in the absence of preoxidation treatments. All alloys corroded in char at least 1000 times more rapidly than in the CGA (MPC-ITTRI) environment. None of the alloys will be acceptable for use in contact with char unless coatings are applied.

  17. Mechanism of corrosion of structural materials in contact with coal chars in coal gasifier atmospheres. Final report

    SciTech Connect

    Douglass, D.L.; Bhide, V.S.; Vineberg, E.

    1980-05-01

    Six alloys, 310 stainless steel, Hastelloy X, Inconel 671, Incoloy 800, Haynes 188, and FeCrAlY (GE1541 and MA956), were corroded in two chars at 1600 and 1800/sup 0/F. The chars, FMC and Husky, contained 2.7 and 0.9% sulfur, respectively. Various parameters were investigated, including char size, cover gas, char quantity, char replenishment period, gas composition, and the use of coatings. The corrosion process was strictly sulfidation when the char was replenished every 24 hours or less. The kinetics of reaction were nearly linear with time. The reaction resulted in thick external sulfide scales with extensive internal sulfidation in the substrate. The kinetics and reaction-product morphologies suggested that diffusion through the sulfide scale played a minor role and that an interfacial reaction was the rate-controlling step. A mathematical model was developed which supported this hypothesis. The reaction rates showed a relatively minor role on alloy composition, depending upon whether the alloys were tested singularly or in combination with others. Inconel 671, the best alloy in CGA environments, consistently corroded the most rapidly of the chromia-former types regardless of char sulfur content or of the temperature. Type 310 stainless was marginally better than Inconel 671. Incoloy 800 was intermediate, whereas, Haynes 188 and Hastelloy X exhibited the best corrosion resistance. The FeCrAlY alloys reacted very rapidly in the absence of preoxidation treatments. All alloys corroded in char at least 1000 times more rapidly than in the CGA (MPC-ITTRI) environment. None of the alloys will be acceptable for use in contact with char unless coatings are applied.

  18. SCDAP/RELAP5/MOD2 code manual

    SciTech Connect

    Hohorst, J.K. )

    1990-02-01

    This report describes the materials properties correlations and computer subcodes (MATPRO) developed for use with various light water reactor (LWR) accident analysis computer programs. Formulation of the materials properties are generally semiempirical in nature. The materials properties subcodes contained in this document are for uranium, uranium dioxide, mixed uranium-plutonium dioxide fuel, zircaloy cladding, zirconium dioxide, stainless steel, stainless steel oxide, silver-indium-cadmium alloy, boron carbide, Inconel 718, zirconium-uranium-oxygen melts, and fill gas mixtures. 452 refs., 230 figs., 139 tabs.

  19. Accelerated Alpha-s deterioration in a geostationary orbit

    NASA Technical Reports Server (NTRS)

    Husmann, O. K.

    1980-01-01

    Between the Teflon substrate and the interference filter a 2 micron varnish layer was sandwiched in. The bending radius of the SSM, measured on a cone, decreased from about 13 mm to 6 mm prior to interference filter fracture, due to increased tensile strength of its substrate. These samples, and for comparison samples of the same make but without varnish and a conductive layer were included in the test. Additionally 2 Teflon FEP samples without the protective interference filter, one of them with a conductive layer, were tested. The sample substrate was 125 micron Teflon FEP, with vapor deposited silver reflector and a thin Inconel film for corrosion protection.

  20. Brazing of ceramic and graphite to metal in the fabrication of ICRF (ion cyclotron range of frequencies) antenna and feedthrough components

    SciTech Connect

    Schechter, D.E.; Sluss, F.; Hoffman, D.J.

    1987-01-01

    Fabrication of some of the more critical components of ion cyclotron range of frequencies (ICRF) antenna and feedthrough assemblies has involved the brazing of alumina ceramic and graphite to various metals. Copper end pieces have been successfully brazed to alumina cylinders for use in feedthroughs for TEXTOR and in feedthroughs and capacitors for a Tokamak Fusion Test Reactor (TFTR) antenna. Copper-plated Inconel rods and tubes have been armored with graphite for construction of Faraday shields on antennas for Doublet III-D and TFTR. Details of brazing procedures and test results, including rf performance, mechanical strength, and thermal capabilities, are presented. 14 figs.

  1. Space nuclear system expansion joints

    NASA Technical Reports Server (NTRS)

    Whitaker, W. D.; Shimazki, T. T.

    1973-01-01

    The engineering, design, and fabrication status of the expansion joint unit (EJU) to be employed in the NaK primary coolant piping loop of the 5-kwe Reactor thermoelectric system are described. Four EJU's are needed in the NaK primary coolant piping loop. The four EJU's which will be identical, utilize bellows as the flexing member, are hermetically sealed, and provide double containment. The bellows are of a nested-formed design, and are to be constructed of 1-ply thickness of 0.010-in. Inconel 718. The EJU's provide a minimum piping load margin of safety of +0.22.

  2. Chemical compatibility of cartridge materials

    NASA Technical Reports Server (NTRS)

    Ambrose, Bryan; Wilcox, R. C.; Zee, R. H.

    1992-01-01

    The objectives were to determine the chemical compatibility of titanium-zirconium-molybdenum (TZM) with GaAs and CdZnTe, and Inconel with HgCdTe and HgZnTe. At the present time, no other studies regarding the compatibility of these crystal components and their respective cartridge materials have been performed. This study was to identify any possible problems between these materials to insure proper containment of possibly hazardous fumes during crystal growth experiments. In this study, the reaction zone between the materials was studied and the amount of degradation to the system was measured. Detailed results are presented.

  3. Near-Threshold Fatigue Crack Growth Behavior of Fine-Grain Nickel-Based Alloys

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Piascik, Robert S.

    2003-01-01

    Constant-Kmax fatigue crack growth tests were performed on two finegrain nickel-base alloys Inconel 718 (DA) and Ren 95 to determine if these alloys exhibit near-threshold time-dependent crack growth behavior observed for fine-grain aluminum alloys in room-temperature laboratory air. Test results showed that increases in K(sub max) values resulted in increased crack growth rates, but no evidence of time-dependent crack growth was observed for either nickel-base alloy at room temperature.

  4. An evaluation of an overlay coated ODS superalloy in high temperature oxidation and burner rig environments

    SciTech Connect

    Ganesan, P.; Smith, G.D. )

    1989-01-01

    Inconel alloy MA 6000 is a precipitation hardenable, oxide dispersion strengthened nickel base superalloy produced by mechanical alloying. The alloy was developed as an airfoil section material for advanced gas turbines. The desire for maximum service life prompted a study to evaluate the coatability of alloy MA 6000 and its performance in the coated condition. This paper presents preliminary results of this study and compares the oxidation and burner-rig test results of coated alloy MA 6000, with and without the interlayer, with the performance of uncoated alloy MA 6000.

  5. REAL-TIME IN-SITU MEASUREMENT OF MATERIAL ELASTIC PROPERTIES IN A HIGH GAMMA IRRADIATION ENVIRONMENT

    SciTech Connect

    Ken Telschow; Rob Schley; Dave Cottle

    2006-05-01

    The first measurements of elastic vibrations of an object in-situ to a high gamma irradiation field using a laser coupled resonant ultrasound method are described. A vibration mode of an Inconel hollow capped cylinder was measured throughout a period of 170 hours as the gamma radiation field was increased to 104 Gray/hour. The vibration mode frequency was observed to change in a manner consistent with the temperature dependence of the elastic stiffness coefficients of the material. These results illustrate the efficacy of the laser approach for real-time resonant ultrasound measurements in this severely hostile nuclear environment.

  6. Reactance simulation for the defects in steam generator tube with outside ferrite sludge

    SciTech Connect

    Ryu, Kwon-sang; Kima, Yong-il; Son, Derac; Park, Duck-gun; Jung, Jae-kap

    2009-04-01

    A magnetic sludge is partly produced around the tube sheet outside a steam generator due to stress and heat. The sludge with magnetite is one of the important factors affecting eddy current signals. It causes trouble for the safety of the steam generator tubes and is difficult to detect by conventional eddy current methods. A new type of probe is needed to detect the signals for the magnetic sludge. We designed a new U-type yoke which has two kinds of coils--a magnetizing coil and the other a detecting coil--and we simulated the signal induced by the ferromagnetic sludge in the Inconel 600 tube.

  7. SRB Materials and Processes Assessment from Laboratory and Ocean Environmental Tests

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The Materials and Processes Laboratory evaluation of Solid Rocket Boosters (SRB) and Solid Rocket Motors (SRM) candidate material, both in-house and with ocean exposure tests at Panama City and Kennedy Space Center (KSC), Florida is presented. Early sample tests showed excellent seawater corrosion resistance for inconel 718 and titanium 6A1-4V alloys. Considerable corrosion and biofouling occurred with bare 2219-T87 aluminum. Subsequent tests conclusively demonstrated that epoxy coatings prevented corrosion of 2219-T87 aluminum as long as the coatings stays intact. The results and assessment of the series of ocean environmental tests that were conducted are also presented.

  8. Deformation characteristics and time-dependent notch sensitivity of Udimet 700 at intermediate temperatures

    NASA Technical Reports Server (NTRS)

    Wilson, D. J.

    1975-01-01

    Time-dependent notch sensitivity of Udimet 700 sheet, bar, and investment castings was observed between 1000 and 1400 F (538-760 C) but not at 1600 F (871 C). As was the case for Modified Waspaloy, Waspaloy, Rene 41, Inconel 718, and TD-NiCr, it occurred when notched specimens were loaded below the yield strength and when creep deformation was localized. For each gamma-prime strengthened alloy and notched specimen geometry, a stress-average particle size zone can be defined to characterize the notch-sensitive behavior.

  9. Environmental crack-growth behavior of high strength pressure vessel alloys

    NASA Technical Reports Server (NTRS)

    Forman, R. G.

    1975-01-01

    Results of sustained-load environmental crack growth threshold tests performed on six spacecraft pressure vessel alloys are presented. The alloys were Inconel 718, 6Al-4V titanium, A-286 steel, AM-350 stainless steel, cryoformed AISI 301 stainless steel; and cryoformed AISI 304L steel. The test environments for the program were air, pressurized gases of hydrogen, oxygen, nitrogen, and carbon dioxide, and liquid environments of distilled water, sea water, nitrogen tetroxide, hydrazine, aerozine 50, monomethyl hydrazine, and hydrogen peroxide. Surface flaw type specimens were used with flaws located in both base metal and weld metal.

  10. Band-limited image plane masks for the Terrestrial Planet Finder coronagraph: materials and designs for broadband performance

    NASA Astrophysics Data System (ADS)

    Balasubramanian, Kunjithapatham

    2008-01-01

    Coronagraphs for detection and characterization of exosolar earthlike planets require accurate masks with broadband performance in the visible and near infrared spectrum. Design and fabrication of image plane masks capable of suppressing broadband starlight to 10-10 level contrast presents technical challenges. We discuss basic approaches, material choices, designs, and fabrication options for image plane masks with particular focus on material properties to obtain adequate spectral performance. Based on theoretical analysis, we show that metals such as Pt and Ni, and alloys such as Inconel, may be employed as promising mask materials that can meet broadband performance requirements.

  11. Performance characteristics of the DIII-D advanced divertor cryopump

    SciTech Connect

    Menon, M.M.; Maingi, R.; Wade, M.R.; Baxi, C.B.; Campbell, G.L.; Holtrop, K.L.; Hyatt, A.W.; Laughon, G.J.; Makariou, C.C.; Mahdavi, M.A.; Reis, E.E.; Schaffer, M.J.; Schaubel, K.M.; Scoville, J.T.; Smith, J.P.; Stambaugh, R.D.

    1993-10-01

    A cryocondensation pump, cooled by forced flow of two-phase helium, has been installed for particle exhaust from the divertor region of the DIII-D tokamak. The Inconel pumping surface is of coaxial geometry, 25.4 mm in outer diameter and 11.65 m in length. Because of the tokamak environment, the pump is designed to perform under relatively high pulsed heat loads (300 Wm{sup {minus}2}). Results of measurements made on the pumping characteristics for D{sub 2}, H{sub 2}, and Ar are discussed.

  12. Influence of gaseous hydrogen on the mechanical properties of incoloy 903. [gas-metal interactions/iron alloys

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Solid specimens of the alloy Inconel 903 (iron based alloy) were exposed to four gaseous environments and high temperatures. Air, pure helium, pure hydrogen, and hydrogen and water vapor combined were the gaseous environments employed, and the temperature was 1400 F. Various mechanical property tests (low cycle fatigue, creep-rupture, tensile properties) were performed on the alloy. Results indicate that the hydrogen and water vapor environment cause a sharp reduction in the mechanical properties of the alloy. Photographs of the test equipment used and the microstructure of the tested alloy are included.

  13. Space nuclear system volume accumulator development (SNAP program)

    NASA Technical Reports Server (NTRS)

    Whitaker, W. D.; Shimazaki, T. T.

    1973-01-01

    The engineering, design, and fabrication status of the volume accumulator units to be employed in the NaK primary and secondary coolant loops of the 5-kwe reactor thermoelectric system are described. Three identical VAU's are required - two for the primary coolant loop, and one for the secondary coolant loop. The VAU's utilize nested-formed bellows as the flexing member, are hermetically sealed, provide double containment and utilize a combination of gas pressure force and bellows spring force to obtain the desired pressure regulation of the coolant loops. All parts of the VAU, except the NaK inlet tube, are to be fabricated from Inconel 718.

  14. Determination of the relative resistance to ignition of selected turbopump materials in high-pressure, high-temperature, oxygen environments, volume 1

    NASA Technical Reports Server (NTRS)

    Stoltzfus, Joel M.; Benz, Frank J.

    1986-01-01

    Advances in the design of the liquid oxygen, liquid hydrogen engines for the Space Transportation System call for the use of warm, high-pressure oxygen as the driving gas in the liquid oxygen turbopump. The NASA Lewis Research Center requested the NASA White Sands Test Facility (WSTF) to design a test program to determine the relative resistance to ignition of nine selected turbopump materials: Hastelloy X, Inconel 600, Invar 36, Monel K-500, nickel 200, silicon carbide, stainless steel 316, and zirconium copper. The materials were subjected to particle impact and to frictional heating in high-pressure oxygen.

  15. Corrosion and Microstructure Correlation in Molten LiCl-KCl Medium

    NASA Astrophysics Data System (ADS)

    Ravi Shankar, A.; Mathiya, S.; Thyagarajan, K.; Kamachi Mudali, U.

    2010-07-01

    Pyrochemical reprocessing in molten chloride salt medium has been considered as one of the best options for the reprocessing of spent metallic fuels of future fast breeder reactors. The unit operations such as salt preparation, electrorefining, and cathode processing involve the presence of molten LiCl-KCl eutectic salt from 673 to 1373 K (400 to 1100 °C). The present work discusses the corrosion behavior of electroformed nickel (EF Ni) without and with nickel-tungsten (Ni-W) coating, 316L SS, and INCONEL 625 alloy in molten LiCl-KCl eutectic salt at 673 K, 773 K, and 873 K (400 °C, 500 °C, and 600 °C) in the presence of air. The weight percent loss of the exposed samples was determined by the weight loss method and surface morphology of the salt exposed, and product layers were examined by scanning electron microscopy (SEM). X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analysis were also carried out on the exposed and corrosion product layers to understand the phases present and the corrosion mechanism involved. The results of the present study indicated that INCONEL 625 alloy showed superior corrosion resistance compared to electroformed nickel (EF Ni), EF Ni with nickel-tungsten (Ni-W) coating (EF Ni-W), and 316L SS. The EF Ni with Ni-W coating exhibits better corrosion resistance than EF Ni without tungsten coating. Based on the surface morphology, XRD, and EDX analysis of corrosion product layers, the mechanism of corrosion of INCONEL 625 and 316L involves formation of chromium-rich compound at the surface and subsequent spallation. For the EF Ni, the porous thick NiO corrosion product allows the penetration of salt, thus accelerating the corrosion. Improved corrosion resistance of EF Ni-W was attributed to the W-rich NiO layer, while for INCONEL 625, the adherent and protective NiO layer improved the corrosion resistance. The article highlights the results of the present investigation.

  16. ECLSS Sustaining Metal Materials Compatibility Final Report, Electrochemical and Crevice Corrosion Test Results

    NASA Technical Reports Server (NTRS)

    Lee, R. E.

    2015-01-01

    Electrochemical test results are presented for six noble metals evaluated in two acidic test solutions which are representative of waste liquids processed in the Environmental Control and Life Support System (ECLSS) aboard the International Space Station (ISS). The two test solutions consisted of fresh waste liquid which had been modified with a proposed or alternate pretreatment formulation and its associated brine concentrate. The six test metals included three titanium grades, (Commercially Pure, 6Al-4V alloy and 6Al-4V Low Interstitial alloy), two nickel-chromium alloys (Inconel® 625 and Hastelloy® C276), and one high tier stainless steel (Cronidur® 30).

  17. Structural Analyses of Stirling Power Convertor Heater Head for Long-Term Reliability, Durability, and Performance

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Shah, Ashwin; Arya, Vinod K.; Krause, David L.; Bartolotta, Paul A.

    2002-01-01

    Deep-space missions require onboard electric power systems with reliable design lifetimes of up to 10 yr and beyond. A high-efficiency Stirling radioisotope power system is a likely candidate for future deep-space missions and Mars rover applications. To ensure ample durability, the structurally critical heater head of the Stirling power convertor has undergone extensive computational analyses of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Durability predictions are presented in terms of the probability of survival. A benchmark structural testing program has commenced to support the analyses. This report presents the current status of durability assessments.

  18. Heat transfer in serpentine passages with turbulence promoters

    NASA Technical Reports Server (NTRS)

    Boyle, R. J.

    1984-01-01

    Local heat transfer rates and overall pressure losses were determined for serpentine passages of square cross section. The flow entered an inlet leg, turned 180 deg and then passed through an outlet leg. Results were obtained for a passage with smooth walls for three different bend geometries and the effect of turbulence promoters was investigated. Turbulence promoters between 0.6 and 15% of the passage height were tested. Local heat transfer rates are determined from thermocouple measurements on a thin electrically heated Inconel foil and pressure drop is measured along the flow path.

  19. Stress Corrosion Evaluation of Various Metallic Materials for the International Space Station Water Recycling System

    NASA Technical Reports Server (NTRS)

    Torres, P. D.

    2015-01-01

    A stress corrosion evaluation was performed on Inconel 625, Hastelloy C276, titanium commercially pure (TiCP), Ti-6Al-4V, Ti-6Al-4V extra low interstitial, and Cronidur 30 steel as a consequence of a change in formulation of the pretreatment for processing the urine in the International Space Station Environmental Control and Life Support System Urine Processing Assembly from a sulfuric acid-based to a phosphoric acid-based solution. The first five listed were found resistant to stress corrosion in the pretreatment and brine. However, some of the Cronidur 30 specimens experienced reduction in load-carrying ability.

  20. Calculations of radiation damage in target, container and window materials for spallation neutron sources

    SciTech Connect

    Wechsler, M.S.; Ferguson, P.D.; Sommer, W.F.; Mansur, L.K.

    1996-07-01

    Radiation damage in target, container, and window materials for spallation neutron sources is am important factor in the design of target stations for accelerator-driver transmutation technologies. Calculations are described that use the LAHET and SPECTER codes to obtain displacement and helium production rates in tungsten, 316 stainless steel, and Inconel 718, which are major target, container, and window materials, respectively. Results are compared for the three materials, based on neutron spectra for NSNS and ATW spallation neutron sources, where the neutron fluxes are normalized to give the same flux of neutrons of all energies.

  1. Resistance heater for use in a glass melter

    DOEpatents

    Routt, K.R.; Porter, M.A.

    1984-01-01

    A resistance heating element that includes: a resistance heating medium of a mixture of electrically conductive and insulative particles in powdered form mixed together in predetermined proportions to achieve a given resistivity; a hollow outer electrode surrounding the resistance heating medium; and an inner electrode coaxially disposed within said outer electrode. In its preferred embodiments, the electrically conductive powder is selected from the group consisting essentially of graphite, Inconel alloy, molybdenum, nichrome alloy and stainless steel, while the insulator powder is silicon dioxide or alumina. The resistance heating element, being resistant to damage from mechanical shock and corrosion at elevated temperatures, is used in a glass melter.

  2. Applying Additive Manufacturing to a New Liquid Oxygen Turbopump Design

    NASA Technical Reports Server (NTRS)

    O'Neal, Derek

    2016-01-01

    A liquid oxygen turbopump has been designed at Marshall Space Flight Center as part of the in-house, Advanced Manufacturing Demonstrator Engine (AMDE) project. Additive manufacturing, specifically direct metal laser sintering (DMLS) of Inconel 718, is used for 77% of the parts by mass. These parts include the impeller, turbine components, and housings. The near-net shape DMLS parts have been delivered and final machining is underway. Fabrication of the traditionally manufactured hardware is also proceeding. Testing in liquid oxygen is planned for Q2 of FY2017. This topic explores the design of the turbopump along with fabrication and material testing of the DMLS hardware.

  3. Evaluation Of Electrochemical Machining Technology For Surface Improvements In Additive Manufactured Components

    SciTech Connect

    Dehoff, Ryan R.; List, III, Frederick Alyious; Carver, Keith

    2015-09-23

    ORNL Manufacturing Demonstration Facility worked with ECM Technologies LLC to investigate the use of precision electro-chemical machining technology to polish the surface of parts created by Arcam electron beam melting. The goals for phase one of this project have been met. The project goal was to determine whether electro-chemical machining is a viable method to improve the surface finish of Inconel 718 parts fabricated using the Arcam EBM method. The project partner (ECM) demonstrated viability for parts of both simple and complex geometry. During the course of the project, detailed process knowledge was generated. This project has resulted in the expansion of United States operations for ECM Technologies.

  4. Evaluation of cobalt sources in Westinghouse-designed three- and four-loop plants. Final report

    SciTech Connect

    Bergmann, C.A.

    1982-10-01

    Sources of cobalt input in two typical Westinghouse-designed three- and four-loop plants are identified. Quantification of the sources was based on a detailed analysis of the construction materials. The best available information was used to establish the corrosion and wear release rates. This analysis concludes that approximately 70% of the cobalt input arises from corrosion release of Inconel steam generator tubing. Corrosion and wear of high-cobalt alloys account for about 25%. Recommendations are made concerning cobalt reduction options based on a cost-benefit analysis.

  5. Using fast reactor component evaluation to pressurized water reactor life extension.

    SciTech Connect

    Allen, T. R.; Cole, J. I.; Kenik, E. A.; Tsai, H.; Ukai, S.; Mizuta, S.; Yoshitake, T.

    1999-10-01

    An understanding of the effects of long-term, low-dose-rate radiation on core components is critical to light-water reactor plant life extension. Following reactor shutdown, materials that had experienced long exposures to low-dose-rate irradiation were retrieved from the EBR-II research reactor for analysis. These components are being analyzed to provide insight into pressurized water reactor life extension. In this work, three examples of EBR-II materials analyses are highlighted: radiation-induced segregation in 304 stainless steel, stress relaxation in Inconel X750, and swelling in 316 stainless steel.;EVALUATION;FAST REACTORS;PWR TYPE REACTORS;

  6. Using fast reactor component evaluation for pressurized water reactor life extension

    NASA Astrophysics Data System (ADS)

    Allen, T. R.; Cole, J. I.; Kenik, E. A.; Tsai, H.; Ukai, S.; Mizuta, S.; Yoshitake, T.

    1999-10-01

    An understanding of the effects of long-term, low-dose-rate radiation on core components is critical to light-water reactor plant life extension. Following reactor shutdown, materials that had experienced long exposures to low-dose-rate irradiation were retrieved from the EBR-II research reactor for analysis. These components are being analyzed to provide insight into pressurized water reactor life extension. In this work, three examples of EBR-II materials analyses are highlighted: radiation-induced segregation in 304 stainless steel, stress relaxation in Inconel X750, and swelling in 316 stainless steel.

  7. Changes in near-surface microstructure of metallic limiters following one year of service in Doublet III

    SciTech Connect

    Trester, P.W.; Sevier, D.L.; Sabado, M.M.

    1981-08-01

    The structural alloys Ta-10W, Mo, and Inconel X-750 were used for plasma limiters during the 3-MW ohmic heating experiments of the Doublet III tokamak. Post-service examinations of these limiters are reviewed. Near-surface melting, cracking, and microstructural changes are shown and discussed. During III service, elements from other metallic components were transported by the plasma and deposited on the limiter surface; significantly, high concentrations of Ni, Fe, Mo, and C were detected in the regions found to be microcracked in the Ta-10W. Observations and analyses are made that are relevant to the design of limiter and armor components for larger tokamaks.

  8. Galvanic corrosion of an aluminum O-ring

    SciTech Connect

    Truhan, J.J.; Chen, C.

    1984-03-30

    The purpose of this study was to estimate the extent of galvanic corrosion occurring between the components of a metal O-ring. The O-ring consists of a split toroid composed of 1050 Al and the internal component, which is a 750X Inconel spring that provides the elasticity. The galvanic measurements were made in deionized water to simulate humid conditions and in a 1% NaCl aqueous solution to simulate the acceleration in corrosion that may occur if surface contamination due to handling or inadequate cleaning is present on the surface.

  9. Weldability of thermally grain-refined Fe-12Ni-0. 25Ti for cryogenic structural applications

    SciTech Connect

    Williams, D.E.

    1980-02-01

    The weldability of a research alloy designed for structural use in liquid helium temperature, cryogenic environments was investigated. Plates of iron-12 weight percent nickel-0.25 weight percent titanium were grain refined by the four-step, grain refining thermal treatment developed for this alloy and welded with Inconel Number 92 weld wire using the Gas Metal Arc (GMA) welding process with argon-15% helium gas shielding. Both a single pass and a double-sided, 2 pass electron beam (EB) weld were also made without filler metal addition. Weldments were radiographed and sectioned and the charpy V-notch specimens removed were tested at liquid nitrogen and helium temperatures.

  10. Evaluation of alloys and coatings for use in automobile thermal reactors

    NASA Technical Reports Server (NTRS)

    Blankenship, C. P.; Oldrieve, R. E.

    1974-01-01

    Several candidate alloys and coatings were evaluated for use in automobile thermal reactors. Full-size reactors of the candidate materials were evaluated in cyclic engine dynamometer tests with a peak temperature of 1040 C (1900 F). Two developmental ferritic-iron alloys, GE-1541 and NASA-18T, exhibited the best overall performance by lasting at least 60 percent of the life of test engine. Four of the alloys evaluated warrant consideration for reactor use. They are GE-1541, Armco 18 SR, NASA-18T, and Inconel 601. None of the commercial coating substrate combinations evaluated warrant consideration for reactor use.

  11. An evaluation of alloys and coatings for use in automobile thermal reactors

    NASA Technical Reports Server (NTRS)

    Blankenship, C. P.; Oldrieve, R. E.

    1974-01-01

    Several candidate alloys and coatings were evaluated for use in automobile thermal reactors. Full-size reactors of the candidate materials were analyzed in cyclic engine dynamometer tests with peak temperature of 1900 F (1040 C). Two developmental ferritic iron alloys GE1541 and NASA-18T - exhibited the best overall performance lasting at least 60% of the life of the test engine. Four of the alloys evaluated warrant consideration for reactor use. They include GE1541, Armco 18 SR, NASA-18T, and Inconel 601. None of the commercial coating substrate combinations evaluated warrant consideration for reactor use.-

  12. Metal-Coated Optical Fibers for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

    1996-01-01

    A DC magnetron sputtering system has been used to actively coat optical fibers with hermetic metal coatings during the fiber draw process. Thin films of Inconel 625 have been deposited on optical fibers and annealed in air at 2000 F. Scanning electron microscopy and Auger electron microscopy have been used to investigate the morphology and composition of the films prior to and following thermal cycling. Issues to be addressed include film adhesion, other coating materials, and a discussion of additional applications for this novel technology.

  13. Modeling aluminum-lithium alloy welding characteristics

    NASA Technical Reports Server (NTRS)

    Bernstein, Edward L.

    1996-01-01

    The purpose of this project was to develop a finite element model of the heat-affected zone in the vicinity of a weld line on a plate in order to determine an accurate plastic strain history. The resulting plastic strain increments calculated by the finite element program were then to be used to calculate the measure of damage D. It was hoped to determine the effects of varying welding parameters, such as beam power, efficiency, and weld speed, and the effect of different material properties on the occurrence of microfissuring. The results were to be compared first to the previous analysis of Inconel 718, and then extended to aluminum 2195.

  14. Alloys For Flexible Hoses In A Corrosive Environment

    NASA Technical Reports Server (NTRS)

    Macdowell, Louis G., III; Ontiveros, Cordelia

    1992-01-01

    High-nickel alloy resists pitting corrosion. Report evaluates metal alloys for flexible hoses in corrosive environment. Tested to find alternatives to 304L stainless steel. Nineteen alloys selected for testing on basis of reputation for resistance to corrosion. Top five, in order of decreasing resistance to corrosion: Hastelloy(R) C-22, Inconel(R) 625, Hastelloy(R) C-276, Hastelloy(R) C-4, and Inco(R) alloy G-3. Of these, Hastelloy(R) C-22 found best for flexible-hose application.

  15. Application of a quadrupole mass filter to laser ionization mass spectrometry: synchronization between the laser pulse and the mass scan

    NASA Astrophysics Data System (ADS)

    Kuzuya, M.; Ohoka, Y.; Katoh, H.; Sakanashi, H.

    1998-01-01

    A quadrupole-based laser ionization mass spectrometry system was developed by combining a commercial quadrupole mass filter with a laser microprobe instrument, which employs a pulse generator that synchronizes the laser pulse with the quadrupole mass scan to detect the pulsed ion signals generated by laser induced ionization. Mass spectra were measured for several solid samples of pure metals (Al,Cu), metal alloys (Inconel 601, brass), and ceramics (BN). Reproducible spectra, with relative standard deviations of the ion signals less than 1%, were obtained with this system. Moreover, isotope abundance ratios were measured and compared with the natural abundance ratios.

  16. NASA Glenn's Seals Group Inaugurated a New State-of-the-Art High-Temperature Test Rig

    NASA Technical Reports Server (NTRS)

    DeMange, Jeffrey J.; Dunlap, Patrick H., Jr.; Steinetz, Bruce M.

    2004-01-01

    The NASA Glenn Research Center is developing advanced control surface seals and propulsion system seals for future space and launch vehicles. To evaluate new seal designs, the Glenn Seals Team recently inaugurated a new state-of-the-art high temperature seal test facility. The Hot Compression/Hot Scrub Rig can perform either high-temperature seal-compression tests or scrub tests at temperatures of up to 3000 F by using different combinations of test fixtures made of monolithic silicon carbide (Hexoloy alpha-SiC), as shown in the following figures. For lower temperature tests (up to 1500 F), Inconel X-750 test fixturing can be used.

  17. Bolting applications

    SciTech Connect

    Czajkowski, C J

    1984-05-01

    An investigation of bolting practices specific to the nuclear industry was performed. The report covered a large spectrum of topics e.g. bolts embedded in concrete, specifications, inspection of bolting, both at receipt and inservice. Plots of preload versus yield strength for different bolting materials in different environments are presented as well as information relative to the stress corrosion cracking resistance of the more recent reactor internals bolting materials A286 and Inconel X-750. Part of the report contains input by Standard Pressed Steel Inc. (a bolting consultant) relative to bolting standards, cottering methods and potential areas for bolting improvement.

  18. SAFT nickel hydrogen cell cycling status

    NASA Technical Reports Server (NTRS)

    Borthomieu, Yannick; Duquesne, Didier

    1994-01-01

    An overview of the NiH2 cell development is given. The NiH2 SAFT system is an electrochemical (single or dual) stack (IPV). The stack is mounted in an hydroformed Inconel 718 vessel operating at high pressure, equipped with 'rabbit ears' ceramic brazed electrical feedthroughs. The cell design is described: positive electrode, negative electrode, and stack configuration. Overviews of low earth orbit and geostationary earth orbit cyclings are provided. DPA results are also provided. The cycling and DPA results demonstrate that SAFT NiH2 is characterized by high reliability and very stable performances.

  19. A technique for making clean holes in metallic piping and components

    NASA Technical Reports Server (NTRS)

    Hecker, T. P.

    1972-01-01

    Testing was conducted to develop a technique of providing clean holes in process piping or in a metal surface accessible from one side only without disassembling the system. The method was performed on sample pieces of piping and worked successfully with no contaminants being found on the inside of the pipe. The materials tested were Inconel 600, 304 stainless steel, Hastelloy X, and ASTM-A53 black steel. The technique was developed such that it could be done in the field with hand-held power tools and a portable tungsten inert gas welding machine.

  20. In Situ Measurements of Spectral Emissivity of Materials for Very High Temperature Reactors

    SciTech Connect

    G. Cao; S. J. Weber; S. O. Martin; T. L. Malaney; S. R. Slattery; M. H. Anderson; K. Sridharan; T. R. Allen

    2011-08-01

    An experimental facility for in situ measurements of high-temperature spectral emissivity of materials in environments of interest to the gas-cooled very high temperature reactor (VHTR) has been developed. The facility is capable of measuring emissivities of seven materials in a single experiment, thereby enhancing the accuracy in measurements due to even minor systemic variations in temperatures and environments. The system consists of a cylindrical silicon carbide (SiC) block with seven sample cavities and a deep blackbody cavity, a detailed optical system, and a Fourier transform infrared spectrometer. The reliability of the facility has been confirmed by comparing measured spectral emissivities of SiC, boron nitride, and alumina (Al2O3) at 600 C against those reported in literature. The spectral emissivities of two candidate alloys for VHTR, INCONEL{reg_sign} alloy 617 (INCONEL is a registered trademark of the Special Metals Corporation group of companies) and SA508 steel, in air environment at 700 C were measured.

  1. Monte Carlo boundary source approach in MOX fuel test capsule design

    SciTech Connect

    Chang, G.S.; Ryskamp, J.M.

    1999-09-01

    To demonstrate that the differences between weapons-grade (WG) mixed oxide (MOX) and reactor-grade MOX fuel are minimal, and therefore the commercial MOX experience base is applicable, an average power test (6 to 10 kW/ft) of WG MOX fuel was inserted into the Advanced Test Reactor (ATR) in January 1998. A high-power test (10 to 15 kW/ft) of WG MOX fuel in ATR is being fabricated as a follow-on to the average-power test. Two MOX capsules with 8.9 GWd/t burnup were removed from ATR on September 13, 1998, and replaced by two fresh WG MOX fuel capsules in regions with less thermal neutron flux (top-1 and bottom-1, which are away from the core center). To compensate for {sup 239}Pu depletion, which causes the linear heat generation rates (LHGRs) to decrease, the INCONEL shield was replaced by an aluminum shield in the phase-II irradiation. The authors describe and compare the results of the detailed MCNP ATR quarter core model (QCM) and isolated box model with boundary source (IBMBS). Physics analysis were performed with these two different models to provide the neutron/fission heat rate distribution data in the WG MOX fuel test assembly, with INCONEL and aluminum shrouds, located in the small I-24 hole of ATR.

  2. Wetting Behavior and Heat Transfer of Aqueous Graphene Nanofluids

    NASA Astrophysics Data System (ADS)

    Nayak, Vignesh U.; Prabhu, Narayan K.

    2016-04-01

    Aqueous graphene nanofluids having concentrations 0.01, 0.1, and 0.3 vol.% were used as heat transfer media during quenching of ISO 9950 inconel alloy probe. Contact angle measurements were carried out to assess the wettability of graphene nanofluids. Nanofluids showed better wettability compared to base water with over 16% reduction in their contact angles. The cooling performance of the quench media was assessed by cooling curve analysis during quenching of an instrumented inconel probe from 860 °C into the quench medium. Recorded temperature readings showed longer vapor phase stage during quenching with nanofluids. The severity of nanofluids was found to be lower relative to water. During quenching with nanofluids, the estimated spatiotemporal heat flux transients at the metal/quenchant interface showed that more heat was removed during the vapor phase stage of cooling. The present study brings out the possibility of using stable water-graphene nanoplatelet suspensions for quench heat treatment of steel components requiring cooling severity between water and oil/polymer quenchants.

  3. Optimization of Laser Keyhole Welding Strategies of Dissimilar Metals by FEM Simulation

    NASA Astrophysics Data System (ADS)

    Garcia Navas, Virginia; Leunda, Josu; Lambarri, Jon; Sanz, Carmen

    2015-07-01

    Laser keyhole welding of dissimilar metals has been simulated to study the effect of welding strategies (laser beam displacements and tilts) and combination of metals to be welded on final quality of the joints. Molten pool geometry and welding penetration have been studied but special attention has been paid to final joint material properties, such as microstructure/phases and hardness, and especially to the residual stress state because it greatly conditions the service life of laser-welded components. For a fixed strategy (laser beam perpendicular to the joint) austenitic to carbon steel laser welding leads to residual stresses at the joint area very similar to those obtained in austenitic to martensitic steel welding, but welding of steel to Inconel 718 results in steeper residual stress gradients and higher area at the joint with detrimental tensile stresses. Therefore, when the difference in thermo-mechanical properties of the metals to be welded is higher, the stress state generated is more detrimental for the service life of the component, and consequently more relevant is the optimization of welding strategy. In laser keyhole welding of austenitic to martensitic stainless steel and austenitic to carbon steel, the optimum welding strategy is displacing the laser beam 1 mm toward the austenitic steel. In the case of austenitic steel to Inconel welding, the optimum welding strategy consists in setting the heat source tilted 45 deg and moved 2 mm toward the austenitic steel.

  4. Exploring Alternative Non-contact temperature measurements for 99Mo production facility NorthStar FY14 Activity 5, Deliverable 2

    SciTech Connect

    Holloway, Michael Andrew; Dalmas, Dale

    2015-03-04

    We have conducted an experiment to explore an alternative non-contact method of measuring the Inconel target window temperature. This experiment involves using a standard color camera to observe the visible light emitted from the Inconel target window at high heat in order to estimate the window temperature. The safety limit to prevent target window failure is 700 °C and therefore we need a reliable and accurate method of measuring temperature especially in the range of 600 °C to 700 °C if it is to replace the IR camera. In this temperature range the window will emit a significant amount of black body radiation within the visible range and hence the idea of using a color camera. The goal is to see if the shift in window color (determined by the RBG pixel values of the camera) as the target window is heated to 700 °C can be calibrated to the temperature.The reasons for exploring this as an alternative to an IR are camera are: significant cost reduction and potentially less complicated to calibrate.

  5. Tensile and Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.; Gayda, John

    2006-01-01

    This paper represents a status report documenting the work on creep of superalloys performed under Project Prometheus. Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, are being screened to compare their respective capabilities for impeller applications. Several wrought superalloys including Hastelloy X, (Haynes International, Inc., Kokomo, IN), Inconel 617, Inconel 740, Nimonic 263, and Incoloy MA956 (Special Metals Corporation, Huntington, WV) are also being screened to compare their capabilities for duct applications. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Conventional tensile and creep tests were performed at temperatures up to 1200 K on specimens extracted from the materials. Initial microstructure evaluations were also undertaken.

  6. Electrochemical impedance spectroscopy of metal alloys in the space transportation system launch environment

    NASA Technical Reports Server (NTRS)

    Calle, Luz

    1990-01-01

    AC impedance measurements were performed to investigate the corrosion resistance of 18 alloys under conditions similar to the Space Transportation System (STS) launch environment. The alloys were: (1) zirconium 702; (2) Hastelloy C-22, C-276, C-4, and B-2; (3) Inconel 600 and 825; (4) Ferralium 255; (5) Inco Alloy G-3; (6) 20Cb-3; (7) SS 904L, 304LN, 316L, 317L, and 304L; (8) ES 2205; and (9) Monel 400. AC impedance data were gathered for each alloy at various immersion times in 3.55 percent NaCl-0.1N HCl. Polarization resistance values were obtained for the Nyguist plots at each immersion time using the EQUIVALENT CIRCUIT software package available with the 388 electrochemical impedance software. Hastelloy C-22 showed the highest overall values for polarization resistance while Monel 400 and Inconel 600 had the lowest overall values. There was good general correlation between the corrosion performance of the alloys at the beach corrosion testing site, and the expected rate of corrosion as predicted based on the polarization resistance values obtained. The data indicate that electrochemical impedance spectroscopy can be used to predict the corrosion performance of metal alloys.

  7. Further Investigations of High Temperature Knitted Spring Tubes for Advanced Control Surface Seal Applications

    NASA Technical Reports Server (NTRS)

    Taylor, Shawn C.; DeMange, Jeffrey J.; Dunlap, Patrick H., Jr.; Steinetz, Bruce M.

    2006-01-01

    Knitted metallic spring tubes are the structural backbones that provide resiliency in control surface seals for use on current and future reusable space launch vehicles. Control surface seals fill the space between movable control surfaces such as body flaps, rudders and elevons, and the static body structures to which they are attached. These seals must remain in continuous contact with opposing surfaces to prevent the ingestion of damaging hot gases encountered during atmospheric re-entry. The Inconel X-750 (Special Metals Corporation) spring tube utilized in the baseline control surface seal shows significant resiliency loss when compressed at temperatures as low as 1200 F. High temperature compression testing and microstructural analysis show that creep is the dominant deformation mechanism leading to permanent set and resiliency loss in tested spring tube samples. Additional evaluation using a structured design of experiments approach shows that spring tube performance, primarily high temperature resiliency, can be enhanced through material substitution of Rene 41 (Allvac) alloy (for the baseline Inconel X-750 material) when coupled with specialized thermal processing.

  8. Cyclic creep and anelastic relaxation analysis of an ODS superalloy

    NASA Astrophysics Data System (ADS)

    Nardone, Vincent C.; Kimmerle, William L.; Tien, John K.

    1986-09-01

    This paper documents the effect of stress and temperature on the cyclic minimum strain rate at two different loading frequencies for the oxide dispersion strengthened (ODS) superalloy, INCONEL* MA 6000. The apparent stress exponent and activation energy for cyclic creep at both frequencies studied are shown to be greater than values observed for static creep. The large values of the stress exponent and activation energy for cyclic creep are proposed to result from anelastic strain storage delaying nonrecoverable creep during the on-load portion of the cyclic creep loading, such that the “effective stress” driving nonrecoverable creep is only a small fraction of the applied stress. In addition, the temperature dependence of the anelastic relaxation that occurs during the off-load portion of the cyclic creep loading is determined. The activation energy found for the relaxation process is equal to about one-half that for self-diffusion in nickel. A mechanism of localized climb of dislocations over the oxide dispersoids present in INCONEL MA 6000 is postulated to account for the observed activation energy of the relaxation process.

  9. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D

    SciTech Connect

    Johnson, W.R.; Smith, J.P.

    1997-08-01

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy, and processing into final sheet and rod product forms suitable for components of the DIII-D Radiative Divertor Program (RDP), has been completed by Wah Chang (formerly Teledyne Wah Chang) of Albany, Oregon (WCA). CVN impact tests on sheet material indicate that the material has properties comparable to other previously-processed V-4Cr-4Ti and V-5Cr-5Ti alloys. Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RDP, and research into several joining methods for fabrication of the RDP components, including resistance seam, friction, and electron beam welding, and explosive bonding is being pursued. Preliminary trials have been successful in the joining of V-alloy to itself by resistance, friction, and electron beam welding processes, and to Inconel 625 by friction welding. In addition, an effort to investigate the explosive bonding of V-4Cr-4Ti alloy to Inconel 625, in both tube-to-bar and sheet-to-sheet configurations, has been initiated, and results have been encouraging.

  10. Autofrettage to Counteract Coefficient of Thermal Expansion Mismatch in Cryogenic Pressurized Pipes with Metallic Liners

    NASA Technical Reports Server (NTRS)

    Wen, Ed; Barbero, Ever; Tygielski, Phlip; Turner, James E. (Technical Monitor)

    2001-01-01

    Composite feedlines with metal liners have the potential to reduce weight/cost while providing the same level of permeation resistance and material compatibility of all-metal feedlines carrying cryogenic propellants in spacecraft. The major technical challenges are the large difference in Coefficient of Thermal Expansion between the liner and the composite, and the manufacturing method required to make a very thin liner with the required strength and dimensional tolerance. This study investigates the use of autofrettage (compressive preload) to counteract Coefficient of Thermal Expansion when pre-pressurization procedures cannot be used to solve this problem. Promising materials (aluminum 2219, Inconel 718, nickel, nickel alloy) and manufacturing techniques (chemical milling, electroplating) are evaluated to determine the best liner candidates. Robust, autofrettaged feedlines with a low Coefficient of Thermal Expansion liner (Inconel 718 or nickel alloy) are shown to successfully counteract mismatch at LOX temperature. A new concept, autofrettage by temperature, is introduced for high Coefficient of Thermal Expansion materials (aluminum and pure nickel) where pressure cannot be used to add compressive preload.

  11. Disposition of salt-waste from pyrochemical nuclear fuel processing

    SciTech Connect

    Vance, E.R.

    2007-07-01

    Waste salts from pyrochemical processing of nuclear fuel can be immobilised in sodalite if consolidated by hot isostatic pressing (HIP) at {approx}750 deg. C/100 MPa in thick stainless steel 316 cans. Other canning materials for this purpose also look possible. Spodiosite-based waste forms do not look promising in terms of leach resistance and their incorporation of alkali ions and compatibility with other phases which could potentially accommodate fission products, such as NaZr{sub 2}(PO{sub 4}){sub 3} or alumino-phosphate glass. Chloro- or fluor-apatite-based waste forms however have been reported to successfully accommodate fission products and alkalis which would be derived from either chloride- or fluoride-based waste pyro-processing salts. The presence of 10 or 20 wt% of additional Whitlockite, Ca{sub 3}(PO{sub 4}){sub 2}, should allow chemical flexibility to maintain the same qualitative phase assemblage when there are variations in the waste feed and in the waste/precursor ratios. Experimental verification of incorporation of the full complement of waste salts and fission products is not yet complete however. Apatite-rich samples could likely be HIPed in Inconel 600 cans. Other candidate HIP canning materials such as Alloy 22 or Inconel 625 are under study by encapsulating them in the candidate waste form and studying their interaction or otherwise with the waste form. (author)

  12. Effects of silver and group II fluoride solid lubricant additions to plasma-sprayed chromium carbide coatings for foil gas bearings to 650 C

    NASA Technical Reports Server (NTRS)

    Wagner, R. C.; Sliney, Harold E.

    1986-01-01

    A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start-stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 748. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The additional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-Psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rPm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

  13. Effects of silver and group 2 fluorides addition to plasma sprayed chromium carbide high temperature solid lubricant for foil gas bearing to 650 deg C

    NASA Technical Reports Server (NTRS)

    Wagner, R. C.; Sliney, H. E.

    1984-01-01

    A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start/stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 718. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The addtitional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rpm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

  14. Study of the HVOF Ni-Based Coatings' Corrosion Resistance Applied on Municipal Solid-Waste Incinerators

    NASA Astrophysics Data System (ADS)

    Guilemany, J. M.; Torrell, M.; Miguel, J. R.

    2008-06-01

    Oxidation of exchanger steel tubes causes important problems in Municipal Solid-Waste Incinerator (MSWI) plants. The present paper shows a possible solution for this problem through High-Velocity Oxygen Fuel (HVOF) thermal spray coatings. A comparative study was carried out between powder and wire Ni-based thermal spray coatings (with the same composition). These optimized coatings were compared based on their microstructure, wear properties (ASTM G99-90, ASTM G65-91), and erosion-corrosion (E-C) resistance. An E-C test designed in the Thermal Spray Centre was performed to reproduce the mechanisms that take place in a boiler. Studying the results of this test, the wire HVT Inconel coating sprayed by propylene appears to be the best alternative. A commercial bulk material with a composition similar to Ni-based coatings was tested to find the products of the oxidation reactions. The protective mechanisms of these materials were assessed after studying the results obtained for HVOF coatings and the bulk material where the presence of nickel and chromium oxides as a corrosion product can be seen. Kinetic evolution of the Ni-based coatings can be studied by thermogravimetric analysis. The protection that Inconel coatings give to the tube through the difference of the gain mass can be seen. Ni-based HVOF coatings by both spray conditions are a promising alternative to MSWI protection against chlorine environments, and their structures have a very important role.

  15. High-temperature corrosion of metallic alloys in an oxidizing atmosphere containing NaCl

    SciTech Connect

    Federer, J.I.

    1989-02-01

    A particular heat-exchanger application involved metallic alloys exposed to flue gases of an aluminum remelt furnace. Because the flue gases might contain NaCl and other halides, the corrosion behavior of the alloys was to be investigated. Planned direct exposure of candidate alloys to the flue gases, however, was not conducted because of premature termination of the project. Complementary laboratory testing was conducted on seven commercially available alloys and two nickel aluminides. These materials were exposed to an oxidizing atmosphere containing 0.06 wt % NaCl for 1100 h at 1000/degree/C. Most of the alloy exhibited grain-boundary attack, which resulted in complete oxidation of enveloped grains. The alloys Incoloy MA-956, Incoloy 800, Inconel 625, Inconel 601, Hastelloy X, Haynes 188, and nickel aluminide IC-50 were substantially more corroded than Alloy 214 and nickel aluminide IC-221. The latter two alloys, therefore, would probably be superior to the others in application involving flue gases containing NaCl. Strength fabricability, and weldability, which are briefly discussed, would also affect selection of materials. 8 refs., 12 figs., 5 tabs.

  16. Hybrid Co-Cr/W-WC and Ni-W-Cr-B/W-WC Coating Systems

    NASA Astrophysics Data System (ADS)

    Vernhes, L.; Azzi, M.; Bousser, E.; Schmitt, T.; Lamarre, J. M.; Klemberg-Sapieha, J. E.

    2016-01-01

    The aim of this study was to investigate the effects of subsurface materials on the performance of a wear-resistant thin film. The mechanical, tribological, and corrosion properties were assessed for two hybrid coating systems: (1) W-WC thin film and a laser cladded Co-Cr interlayer applied to a 316 stainless steel substrate and (2) the same W-WC thin film and a spray-and-fused Ni-W-Cr-B interlayer applied to an Inconel® 718 substrate. They were then compared to the same systems without an interlayer. The microstructures were analyzed by XRD, EDS, and SEM. The hardness and surface load-carrying capacity of the coating systems were determined by micro- and macrohardness testing. Rockwell indentation was used to assess coating adhesion (CEN/TS 1071-8). Tribological properties were assessed with a reciprocating tribometer, and corrosion resistance was determined by potentiodynamic polarization and electrochemical impedance spectroscopy. The originality of this work lies in the finding that, except for the Inconel 718/Ni-W-Cr-B/W-WC system, the wear rate decreases with decreasing hardness of the subsurface materials carrying the thin film due to the decreasing contact pressure for a given load. Another novel finding is the stress-induced phase transformation of the Co-Cr interlayer, which occurs beneath the thin film under high load.

  17. Composition optimization of chromium carbide based solid lubricant coatings for foil gas bearings at temperatures to 650 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher

    1987-01-01

    A test program to determine the optimum composition of chromium carbide based solid lubricant coatings for compliant gas bearings is described. The friction and wear properties of the coatings are evaluated using a foil gas bearing test apparatus. The various coatings were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized nickel-chromium alloy foils. The test bearings were subjected to repeated start/stop cycles under a 14 kPa (2 psi) bearing unit load. The bearings were tested for 9000 start/stop cycles or until the specimen wear reached a predetermined failure level. In general, the addition of silver and eutectic to the chromium carbide base stock significantly reduced foil wear and increased journal coating wear. The optimum coating composition, PS212 (70 wt% metal bonded Cr3C2, 15 wt% Ag, 15% BaF2/CaF2 eutectic), reduced foil wear by a factor of two and displayed coating wear well within acceptable limits. The load capacity of the bearing using the plasma-sprayed coating prior to and after a run-in period was ascertained and compared to polished Inconel 718 specimens.

  18. Analysis of a failed hot-gas sampler coupling from the IGT HYGAS pilot plant

    SciTech Connect

    Diercks, D.R.; Dragel, G.M.

    1980-10-01

    A coupling from a hot-gas sampling line in the HYGAS coal-gasification pilot plant failed after about 8470 hours in service. The coupling was made of RA 330, and was welded to 1.27- and 1.91-cm-OD lines at either end using Inconel 182 weld metal. Failure occurred in the form of intergranular corrosive attack and highly branched cracking from the inner surface of the base metal and interdendritic attack and cracking of the weld metal. The attacked intergranular and interdendritic regions were found to be high in sulfur, which was present both as CrS and Ni/sub 3/S/sub 2/. It was concluded that the coupling failed owing to high-temperature sulfidation, particularly of the high-nickel Inconel 182 weld filler metal, and the consequent formation of the liquid Ni/sub 3/S/sub 2/-nickel eutectic. Continuous water cooling of the coupling to maintain temperatures below those at which significant sulfidation can occur was recommended. Alternatively, the possible use of lower-nickel weld filler metals was suggested.

  19. MS212--A Homogeneous Sputtered Solid Lubricant Coating for Use to 800 C

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.; Waters, William J.; Soltis, Richard

    1997-01-01

    Composite coatings containing chromium carbide, stable fluorides and silver were prepared by magnetron sputtering. The microstructure of the coatings is very homogeneous compared to that of plasma sprayed and sintered versions of the same chemical composition. Friction and wear of MS212-coated and baseline uncoated aluminum and Inconel X-750 are compared. At room temperature, the friction and wear of coated aluminum is dramatically better compared to the baseline. The acceptable load is limited by deformation of the soft aluminum substrate. In the case of the nickel alloy, lower friction is observed for the coated alloy at all temperatures up to the maximum test temperature of 800 C. Pin wear factors for sliding against the coated alloy are lower than the baseline at room temperature and 350 C, and comparable to baseline wear at higher test temperatures. Low baseline wear at high temperatures is due to the lubricious nature of the natural oxides formed on nickel-chromium alloys in a hot, oxidizing atmosphere. No load limit was found for coated Inconel X-750 at loads up to five times the load limit for coated aluminum.

  20. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D

    SciTech Connect

    Johnson, W.R.; Smith, J.P.; Trester, P.W.

    1997-04-01

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy, and processing into final sheet and rod product forms suitable for components of the DIII-D Radiative Divertor structure, has been completed at Wah Chang (formerly Teledyne Wah Chang) of Albany, Oregon (WCA). Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RD Program, and research into several joining methods for fabrication of the RD components, including resistance seam, friction, and electron beam welding, is continuing. Preliminary trials have been successful in the joining of V-alloy to itself by electron beam, resistance, and friction welding processes, and to Inconel 625 by friction welding. An effort to investigate the explosive bonding of V-4Cr-4Ti alloy to Inconel 625 has also been initiated, and results have been encouraging. In addition, preliminary tests have been completed to evaluate the susceptibility of V-4Cr-4Ti alloy to stress corrosion cracking in DIII-D cooling water, and the effects of exposure to DIII-D bakeout conditions on the tensile and fracture behavior of V-4Cr-4Ti alloy.

  1. Compatibility studies of metallic materials with lithium-based oxides

    NASA Astrophysics Data System (ADS)

    Hofmann, P.; Dienst, W.

    1988-07-01

    The compatibility of Li 2O, Li 4SiO 4 and Li 2SiO 3 with the cladding materials AISI 316, 1.4914, Hastelloy X and Inconel 625 was investigated at 800-1000°C for annealing times up to 1000 h. A controlled oxygen reactivity was established by adding 1 mol% NiO per mole Li 2O to the Li-based oxides. In addition, some compatibility tests were performed at 600-900°C on Be, which is of interest as a neutron multiplier material, with Li 2SiO 3 as well as AISI 316. Li 2O accounted for the strongest cladding attack, followed by Li 4SiO 4 and Li 2SiO 3. In the absence of NiO, Li 2SiO 3 caused no chemical interactions at all. With respect to the cladding materials, there was no considerable difference in the reaction rates of AISI 316, Hastelloy X and Inconel 625. However, the steel 1.4914 was clearly more heavily attacked at and above 800°C. The compatibility of Be with Li 2SiO 3 or AISI 316 seems to be tolerable up to about 650°C. At higher temperatures a liquid Li suicide phase is formed which results in strong local attack and penetration into Li 2SiO 3.

  2. Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.; Gayda, john; Garg, Anita

    2007-01-01

    Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, have been screened to compare their respective capabilities for impeller applications. Mar-M247LC has been selected for additional long term evaluations. Initial tests in helium indicate this inert environment may debit long term creep resistance of this alloy. Several wrought superalloys including Hastelloy(Registered TradeMark) X, Inconel(Registered TradeMark) 617, Inconel(Registered TradeMark) 740, Nimonic(Registered TradeMark) 263, Incoloy(Registered TradeMark) MA956, and Haynes 230 are also being screened to compare their capabilities for duct applications. Haynes 230 has been selected for additional long term evaluations. Initial tests in helium are just underway for this alloy. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Therefore, long term microstructural stability is also being screened.

  3. A Compendium of Brazed Microstructures For Fission Power Systems Applications

    NASA Technical Reports Server (NTRS)

    Locci, Ivan E.; Bowman, Cheryl L.

    2012-01-01

    NASA has been supporting design studies and technology development for fission-based power systems that could provide power to an outpost on the Moon, Mars, or an asteroid. Technology development efforts have included fabrication and evaluation of components used in a Stirling engine power conversion system. This investigation is part of the development of several braze joints crucial for the heat exchanger transfer path from a hot-side heat exchanger to a Stirling engine heat acceptor. Dissimilar metal joints are required to impart both mechanical strength and thermal path integrity for a heater head of interest. Preliminary design work for the heat exchanger involved joints between low carbon stainless steel to Inconel 718, where the 316L stainless steel would contain flowing liquid metal NaK while Inconel 718, a stronger alloy, would be used as structural reinforcement. This paper addressed the long-term microstructural stability of various braze alloys used to join 316L stainless steel heater head to the high conductivity oxygen-free copper acceptor to ensure the endurance of the critical metallic components of this sophisticated heat exchanger. The bonding of the 316L stainless steel heater head material to a copper heat acceptor is required to increase the heat-transfer surface area in contact with flowing He, which is the Stirling engine working fluid.

  4. Corrosion studies in molten calcium chloride with chlorine

    SciTech Connect

    McLaughlin, D.F. . Science and Technology Center); Sessions, C.E.; Marra, J.E. )

    1990-01-01

    This study is aimed at testing new materials for use in molten salt processing of plutonium. Because of the high corrosiveness of chlorine, present materials have a high rate of failure. Materials less subject to corrosion are needed to minimize costs resulting from rapid failure of sparge tubes, stirring apparatus, and crucibles; to reduce the quantity of plutonium-contaminated scrap; and to improve the purity of the plutonium product. The processing environment of molten CaCl{sub 2}--CaO salts, molten plutonium, and chlorine-oxygen gas at temperatures from 750{degree} to 900{degree} is extremely severe. Materials with resistance to both corrosion and mechanical failure are desired. Also, the incorporation of corrosion products into the final plutonium product cannot exceed the allowable impurity limits. We require materials for crucibles, sparge tubes, stirrers, and containment and pull cans. Four metallic and two ceramics materials were tested. The metallic materials were Inconel-601, Inconel-617, tantalum, and tungsten. Silicon nitride and magnesium oxide were the ceramics tested.

  5. Optimization of a microbial fuel cell for wastewater treatment using recycled scrap metals as a cost-effective cathode material.

    PubMed

    Lefebvre, Olivier; Tan, Zi; Shen, Yujia; Ng, How Y

    2013-01-01

    Microbial fuel cell (MFC) for wastewater treatment is still hindered by the prohibitive cost of cathode material, especially when platinum is used to catalyze oxygen reduction. In this study, recycled scrap metals could be used efficiently as cathode material in a specially-designed MFC. In terms of raw power, the scrap metals ranked as follows: W/Co > Cu/Ni > Inconel 718 > carpenter alloy; however, in terms of cost and long term stability, Inconel 718 was the preferred choice. Treatment performance--assessed on real and synthetic wastewater--was considerably improved either by filling the anode compartment with carbon granules or by operating the MFC in full-loop mode. The latter option allowed reaching 99.7% acetate removal while generating a maximum power of 36 W m(-3) at an acetate concentration of 2535 mg L(-1). Under these conditions, the energy produced by the system averaged 0.1 kWh m(-3) of wastewater treated. PMID:23138054

  6. Fabrication of High-Temperature Heat Exchangers by Plasma Spraying Exterior Skins on Nickel Foams

    NASA Astrophysics Data System (ADS)

    Hafeez, P.; Yugeswaran, S.; Chandra, S.; Mostaghimi, J.; Coyle, T. W.

    2016-06-01

    Thermal-sprayed heat exchangers were tested at high temperatures (750 °C), and their performances were compared to the foam heat exchangers made by brazing Inconel sheets to their surface. Nickel foil was brazed to the exterior surface of 10-mm-thick layers of 10 and 40 PPI nickel foam. A plasma torch was used to spray an Inconel coating on the surface of the foil. A burner test rig was built to produce hot combustion gases that flowed over exposed face of the heat exchanger. Cooling air flowed through the foam heat exchanger at rates of up to 200 SLPM. Surface temperature and air inlet/exit temperature were measured. Heat transfer to air flowing through the foam was significantly higher for the thermally sprayed heat exchangers than for the brazed heat exchangers. On an average, thermally sprayed heat exchangers show 36% higher heat transfer than conventionally brazed foam heat exchangers. At low flow rates, the convective resistance is large (~4 × 10-2 m2 K/W), and the effect of thermal contact resistance is negligible. At higher flow rates, the convective resistance decreases (~2 × 10-3 m2 K/W), and the lower contact resistance of the thermally sprayed heat exchanger provides better performance than the brazed heat exchangers.

  7. Ion beam studies of hydrogen in metals

    SciTech Connect

    Myers, S.M.; Wampler, W.R.; Besenbacher, F.; Robinson, S.L.; Moody, N.R.

    1984-01-01

    Methods based on ion implantation and nuclear reaction analysis were used to investigate the behavior of hydrogen isotopes in metals. The binding enthalpy of deuterium (D) at irradiation effects, He bubbles, D/sub 2/ bubbles, and metal-oxide interfaces was measured for Al, Fe, Ni, Cu, Pd, austenitic stainless steel, Inconel, and amorphous Fe/sub 40/Ni/sub 40/P/sub 14/B/sub 6/. The binding enthalpies determined for the pure metals are in excellent agreement with mechanistic calculations based on effective-medium theory and other information. Surface-limited release of D from Fe, stainless steel, and Inconel was measured as a function of temperature and the state of surface oxidation. The release rate was accurately proportional to the square of the D concentration in solution, permitting the results to be expressed in terms of a surface recombination coefficient. This quantity was up to four orders of magnitude greater for an ion-sputtered surface than for a surface with electropolish oxide. The diffusion coefficient and solid solubility of tritium in stainless steel were measured for the first time at the ice point, thereby extending downward by three orders of magnitude the diffusivities available from conventional permeation experiments. Deuterium concentration profiles resulting from electrochemical charging of Incoloy 903 were measured as a function of charging current, thereby providing a direct, systematic calibration of such charging in an austenitic material where conventional permeation measurements are precluded by the small hydrogen diffusion rate.

  8. Free form fabrication using the laser engineered net shaping (LENS{trademark}) process

    SciTech Connect

    Keicher, D.M.; Romero, J.A.; Atwood, C.L.; Griffith, M.L.; Jeantette, F.P.; Harwell, L.D.; Greene, D.L.; Smugeresky, J.E.

    1996-12-31

    Sandia National Laboratories is developing a technology called Laser Engineered Net Shaping{trademark} (LENS{trademark}). This process allows complex 3-dimensional solid metallic objects to be directly fabricated for a CAD solid model. Experiments performed demonstrate that complex alloys such as Inconel{trademark} 625 and ANSI stainless steel alloy 316 can be used in the LENS{trademark} process to produce solid metallic-shapes. In fact, the fabricated structures exhibit grain growth across the deposition layer boundaries. Mechanical testing data of deposited 316 stainless steel material indicates that the deposited material strength and elongation are greater than that reported for annealed 316 stainless steel. Electron microprobe analysis of the deposited Inconel{trademark} 625 material shows no compositional degradation of the 625 alloy and that 100% dense structures can be obtained using this technique. High speed imaging used to acquire process data during experimentation shows that the powder particle size range can significantly affect the stability, and subsequently, the performance of the powder deposition process. Finally, dimensional studies suggest that dimensional accuracy to {+-} 0.002 inches (in the horizontal direction) can be maintained.

  9. Effects of silver and Group II fluorides addition to plasma sprayed chromium carbide high temperature solid lubricant for foil gas bearings to 650/sup 0/C

    SciTech Connect

    Wagner, R.C.; Sliney, H.E.

    1985-01-01

    A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide fromulated with silver and Group II fluorides was developed. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for compliant foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start/stop apparatus at temperatures from 25 to 650/sup 0/C. The journals were Inconel 718. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The additional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized inconel X-750 foil bearing were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rpm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

  10. The effect of counterface on the tribological performance of a high temperature solid lubricant composite from 25 to 650{degree}C

    SciTech Connect

    DellaCorte, C.

    1996-05-01

    The effect of counterface selection on the tribological performance of a Ag/BaF{sub 2}-CaF{sub 2} containing composite coating is studied. Ceramic (Al{sub 2}O{sub 3}) and metal (Inconel X-750) pins are slid against PS300 (a metal bonded chrome oxide coating with Ag and BaF{sub 2}/CaF{sub 2} lubricant additives) in a pin-on-disk tribometer at 25, 500 and 650 C. Compared to the ceramic counterface, the metal counterface generally exhibited lower friction and wear at 25 C but higher friction and wear at 650 C. Friction coefficients, for example, for the Al{sub 2}O{sub 3}/PS300 combination at 25 C were 0.64 compared to 0.23 for the Inconel/PS300 sliding couple. At 650 C the ranking was reversed. The Al{sub 2}O{sub 3}/PS300 combination gave a friction coefficient of 0.19 while the friction for the metal counterface increased slightly to about 0.3. Based upon these tribological results and other information found in the literature, it appears that the performance of each counterface/PS300 combination is affected by the ability of the solid lubricant additives to form an adequate transfer film. The effects of surface wettability and tribological compatibility are discussed in relation to the observed tribological results.

  11. Pilot-scale ceramic melter 1985-1986 rebuild: Nuclear Waste Treatment Program

    SciTech Connect

    Koegler, S.S.

    1987-07-01

    The pilot-scale ceramic melter (PSCM) was subsequently dismantled, and the damaged and corroded components were repaired or replaced. The PSCM rebuild ensures that the melter will be available for an additional three to five years of planned testing. An analysis of the corrosion products and the failed electrodes indicated that the electrode bus connection welds may have failed due to a combination of chemical and mechanical effects. The electrodes were replaced with a design similar to the original electrodes, but with improved electrical bus connections. The implications of the PSCM electrode corrosion evaluation are that, although Inconel 690 has excellent corrosion resistance to molten glass, corrosion at the melt line in stagnant regions is a significant concern. Functional changes made during the rebuild included increases in wall and floor insulation to better simulate well-insulated melters, a decrease in the lid height for more prototypical plenum and off-gas conditions, and installation of an Inconel 690 trough and dam to improve glass pouring and prevent glass seepage. 9 refs., 33 figs., 5 tabs.

  12. Compatibility of ITER candidate structural materials with static gallium

    SciTech Connect

    Luebbers, P.R.; Michaud, W.F.; Chopra, O.K.

    1993-12-01

    Tests were conducted on the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor, e.g., Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy, as well as Armco iron, Nickel 270, and pure chromium. Type 316 stainless steel is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400{degrees}C, corrosion rates are {approx}4.0, 0.5, and 0.03 mm/yr for type 316 SS, Inconel 625, and Nb-5 Mo- 1 Zr alloy, respectively. The pure metals react rapidly with gallium. In contrast to findings in earlier studies, pure iron shows greater corrosion than nickel. The corrosion rates at 400{degrees}C are {ge}88 and 18 mm/yr, respectively, for Armco iron and Nickel 270. The results indicate that at temperatures up to 400{degrees}C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The solubility data for pure metals and oxygen in gallium are reviewed. The physical, chemical, and radioactive properties of gallium are also presented. The supply and availability of gallium, as well as price predictions through the year 2020, are summarized.

  13. Internal hydrogen effects on tensile properties of iron- and nickel-base superalloys

    NASA Astrophysics Data System (ADS)

    Hicks, P. D.; Altstetter, C. J.

    1990-01-01

    Two nickel-base alloys [superalloys INCONEL 718 (IN718) and INCONEL 625 (IN625)] and one iron-base superalloy (A286) were chosen to study the effects of internal H charging on their room-temperature slow strain rate mechanical behavior. Uniform internal H contents ranged from 0 to 50 wt ppm H (0 to 3000 at. ppm H), and a strain rate of 8.5 X 10-7 m/s was used with notched strip specimens. The three alloys showed varying losses in strength and ductility, and the strongest alloy, IN718, showed a decrease of 67 pet in ductility for a dissolved H content of 40 wt ppm. Superalloy A286 showed a corresponding 50 pet decrease in ductility, and IN625 showed a 29 pet loss in ductility. Fractographic evidence and the marked decrease in strength of the alloys lead the authors to conclude that the enhanced localized plasticity mechanism for H embrittlement is possibly operative in these face-centered cubic (fcc) alloys.

  14. Effect of homogenization heat treatment on the microstructure and heat- affected zone microfissuring in welded cast alloy 718

    NASA Astrophysics Data System (ADS)

    Huang, Xiao; Chaturvedi, M. C.; Richards, N. L.

    1996-03-01

    The effect of homogenization temperature on microfissuring in the heat-affected zones of electronwelded cast INCONEL 718 has been studied. The material was homogenized at various temperatures in the range of 1037 ° to 1163 ° and air-cooled. The homogenized material was then electron-beam welded by the bead-on-plate welding technique. The microstructures and microfissuring in the heat-affected zone (HAZ) were evaluated by analytical scanning electron microscopy (SEM). The grain boundary segregation of various elements was evaluated by secondary ion mass spectroscopy (SIMS). It was observed that the total crack length (TCL) of microfissures first decreases with homogenization temperature and then increases, with a minimum occurring in the specimen heat treated at 1163 °. This trend coincides with the variation in segregation of B at grain boundaries with homogenization temperature and has been explained by equilibrium and nonequilibrium segregation of B to grain boundaries during the homogenization heat treatment. No other element was observed to segregate at the grain boundaries. The variation in volume fraction of phases like δ-Ni3Nb, MC carbide, and Laves phases does not follow the same trend as that observed for TCL and B segregation at the grain boundaries. Therefore, microfissuring in HAZ of welded cast INCONEL 718 is attributed to the segregation of B at the grain boundaries.

  15. Defense waste vitrification studies during FY-1981. Summary report

    SciTech Connect

    Bjorklund, W.J.

    1982-09-01

    Both simulated alkaline defense wastes and simulated acidic defense wastes (formed by treating alkaline waste with formic acid) were successfully vitrified in direct liquid-fed melter experiments. The vitrification process was improved while using the formate-treated waste. Leach resistance was essentially the same. Off-gas entrainment was the primary mechanism for material exiting the melter. When formate waste was vitrified, the flow behavior of the off gas from the melter changed dramatically from an erratic surging behavior to a more quiet, even flow. Hydrogen and CO were detectable while processing formate feed; however, levels exceeding the flamability limits in air were never approached. Two types of melter operation were tested during the year, one involving boost power. Several boosting methods located within the melter plenum were tested. When lid heating was being used, water spray cooling in the off gas was required. Countercurrent spray cooling was more effective than cocurrent spray cooling. Materials of construction for the off-gas system were examined. Inconel-690 is preferred in the plenum area. Inspection of the pilot-scale melter found that corrosion of the K-3 refractory and Inconel-690 electrodes was minimal. An overheating incident occurred with the LFCM in which glass temperatures up to 1480/sup 0/C were experienced. Lab-scale vitrification tests to study mercury behavior were also completed this year. 53 figures, 63 tables.

  16. Solidification and weldability of thermo-span{trademark} alloy

    SciTech Connect

    Robino, C.V.; Michael, J.R.

    1994-12-31

    Thermo-Span is a low coefficient of thermal expansion precipitation hardenable superalloy with high tensile and rupture strengths. The alloy is based on the Fe-Co-Ni system and utilizes chromium additions for improved environmental resistance. The solidification behavior and fusion zone hot cracking tendency of this alloy has been evaluated using differential thermal analysis, Varestraint testing, and through comparison with Inconel 718 and Incoloy 909. Solidification microstructures were characterized by optical and electron microscopy, and the solidification phases identified. Differential thermal analysis (DTA) at heating and cooling rates of 20{degrees}C/min indicated that melting of the wrought allow initiates at temperatures near 1280{degrees}C and continues to approximately 1441{degrees}C. During cooling, the alloy solidifies with two solidification events. These events are the formation of primary austenite and the formation of a terminal eutectic-like constituent at approximately 1220{degrees}C. The implications of the electron microscopy results, in terms of the hot cracking behavior, will be discussed. In summary, the weldability of Thermo-Span was found to be similar to Inconel 718 and Incoloy 909 and therefore, the alloy is likely to be amenable to similar weld processing. This was work performed at Sandia National Laboratories supported by the U.S. Department of Energy under Contract Number DE-AC04-76DP00789.

  17. Spent Nuclear Fuel (SNF) Storage Project Fuel Basket Handling Grapple Design Development Test Report

    SciTech Connect

    CHENAULT, D.M.

    2000-01-06

    Acceptance testing of the SNF Fuel Basket Lift Grapple was accomplished to verify the design adequacy. This report shows the results affirming the design. The test was successful in demonstrating the adequacy of the grapple assembly's inconel actuator shaft and engagement balls for in loads excess of design basis loads (3200 pounds), 3X design basis loads (9600 pounds), and 5X design basis loads (16,000 pounds). The test data showed that no appreciable yielding for the inconel actuator shaft and engagement balls at loads in excess of 5X Design Basis loads. The test data also showed the grapple assembly and components to be fully functional after loads in excess of 5X Design Basis were applied and maintained for over 10 minutes. Following testing, each actuator shaft (Item 7) was liquid penetrant inspected per ASME Section 111, Division 1 1989 and accepted per requirements of NF-5350. This examination was performed to insure that no cracking had occurred. The test indicated that no cracking had occurred. The examination reports are included as Appendix C to this document. From this test, it is concluded that the design configuration meets or exceeds the requirements specified in ANSI N 14 6 for Special Lifting Devices for Shipping Containers Weighing 10,000 Pounds (4500 kg) or More.

  18. Benchmark notch test for life prediction

    NASA Technical Reports Server (NTRS)

    Domas, P. A.; Sharpe, W. N.; Ward, M.; Yau, J. F.

    1982-01-01

    The laser Interferometric Strain Displacement Gage (ISDG) was used to measure local strains in notched Inconel 718 test bars subjected to six different load histories at 649 C (1200 F) and including effects of tensile and compressive hold periods. The measurements were compared to simplified Neuber notch analysis predictions of notch root stress and strain. The actual strains incurred at the root of a discontinuity in cyclically loaded test samples subjected to inelastic deformation at high temperature where creep deformations readily occur were determined. The steady state cyclic, stress-strain response at the root of the discontinuity was analyzed. Flat, double notched uniaxially loaded fatigue specimens manufactured from the nickel base, superalloy Inconel 718 were used. The ISDG was used to obtain cycle by cycle recordings of notch root strain during continuous and hold time cycling at 649 C. Comparisons to Neuber and finite element model analyses were made. The results obtained provide a benchmark data set in high technology design where notch fatigue life is the predominant component service life limitation.

  19. Quantification of precipitates and their effects on the response of nickel-base superalloy to shot peening

    NASA Astrophysics Data System (ADS)

    Chandrasekar, R.; Lo, C. C. H.; Frishman, A. M.; Larson, B. F.; Nakagawa, N.

    2012-05-01

    This paper reports on a microstructural study of a nickel-base superalloy, Inconel 718, with a focus on quantifying precipitate density and their effects on conductivity variations. The study is motivated by eddy current (EC) characterization of residual stresses, where observed EC signals are attempted to correlate with stress profiles of shot peened superalloy surfaces. It has been observed that the correlation is less universal than anticipated, and in fact strongly influenced by the material hardness, or the aging conditions. For example, the soft sample surface exhibits significantly stronger EC signals than the fully hardened sample when both are shot peened at the same Almen intensity. Thus, the objective of the present study is to examine this complex material response against aging and shot peening treatments at the microstructure scale, by the use of techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM). We will describe preparations of a series of Inconel 718 samples that was aged and shot peened at various conditions, and present microstructural data obtained from SEM and TEM images such as precipitate densities, correlated with bulk properties such as the hardness and conductivity.

  20. Modifying structure and properties of nickel alloys by nanostructured composite powders

    NASA Astrophysics Data System (ADS)

    Cherepanov, A. N.; Ovcharenko, V. E.; Liu, G.; Cao, L.

    2015-01-01

    The article presents the results of an experimental study of the influence of powder nanomodifiers of refractory compounds on the mechanical properties, macro- and microstructure of heat-resistant alloys ZhS-6K and Inconel 718. It is shown that the introduction of nanomodifiers into the melt leads to the refinement of the alloy structure: the average grain size decreases 1.5-2 times, and their morphology becomes similar to equiaxial at significant reduction of the particle size in the carbide phase. The service life of ZhS-6K alloy under cyclic loading at 600°C increases 2.7 times, and at 975 °C by 40 %, and relative elongation increases more than twice. The mechanical properties of Inconel 718 significantly increase: long-term strength at 650 °C increases 1.5-2 times, and the number of cycles before the collapse at 482 °C grows more than three times. It has been found out that addition of nanomodifiers to the melt, in alloys, forms clusters of particles of refractory compounds at borders and joints of the formed grain structure that may help slowing down the processes of recrystallization (prevents the increase in the size of the contacting grains by their associations) and stabilizes the strength properties of the alloys at higher temperatures.