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Sample records for alloy-x750 inconel

  1. Prior deformation effects on creep and fracture in inconel alloy X-750

    NASA Astrophysics Data System (ADS)

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

    1984-07-01

    Creep fracture process in Inconel alloy X-750 can be modified by room-temperature prestraining. It has been observed that fracture in the prestrained specimens occurred due to growth and interlinkage of the prenucleated voids whereas failure occurred by plastic instability in the non-prestrained specimens. Creep ductility and the times-to-rupture are found to decrease progressively with room-temperature prestraining, but there is no marked influence on the minimum creep rate. This is explained in terms of two compcting processes: a weakening effect caused by prenucleation of grain boundary voids and a hardening effect due to generation of dislocations due to the prestraining.

  2. Tensile behavior of inconel alloy X-750 in air and vacuum at elevated temperatures

    NASA Astrophysics Data System (ADS)

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

    1984-09-01

    Investigations carried out on the hot tensile properties of Inconel alloy X-750 at 700 °C in air and vacuum at different strain rates, in the range of 1 × 10-7 to 1.2 × 10-6 s-1, have shown that testing in air had a weakening effect on properties. Creep ductility in vacuum ( p 02 = 2.7 × 10-5 Pa) did not change appreciably with strain rate, but ductility varied markedly when tested in the air. Further, the ductility minimum occurred at 625 °C in air whereas considerable improvements in the creep ductilities were observed at 575 °C and 625 °C in the vacuum. The results indicated that the environmental interaction during testing enhanced the rate of cavitation damage causing premature failure in the material.

  3. The effects of heat treatment and composition on the stress corrosion cracking resistance of inconel alloy X-750

    NASA Astrophysics Data System (ADS)

    Floreen, S.; Nelson, J. L.

    1983-01-01

    The stress corrosion cracking resistance of 24 heats of INCONEL* alloy X-750 was measured in high purity pH 10 water at 360 °C. An overaging heat treatment of 96 hours at 760 °C produced an improved combination of strength and cracking resistance because of the homogenization of slip in the matrix. Examination of residual elements showed that Zr additions further improved the cracking resistance by stabilizing theγ' precipitate in the grain boundary region. Combining the new heat treatment with the Zr addition produced approximately a 50 pct improvement in stress corrosion cracking resistance at a 10 pct lower yield strength.

  4. Oxide evolution on Alloy X-750 in simulated BWR environment

    NASA Astrophysics Data System (ADS)

    Tuzi, Silvia; Göransson, Kenneth; Rahman, Seikh M. H.; Eriksson, Sten G.; Liu, Fang; Thuvander, Mattias; Stiller, Krystyna

    2016-12-01

    In order to simulate the environment experienced by spacer grids in a boiling water reactor (BWR), specimens of the Ni-based Alloy X-750 were exposed to a water jet in an autoclave at a temperature of 286 °C and a pressure of 80 bar. The oxide microstructure of specimens exposed for 2 h, 24 h, 168 h and 840 h has been investigated mainly using electron microscopy. The specimens suffer mass loss due to dissolution during exposure. At the same time a complex layered oxide develops. After the longest exposure the oxide consists of two outer spinel layers consisting of blocky crystals, one intermediate layer of nickel oxide interspersed with Ti-rich oxide needles, and an inner layer of oxidized base metal. The evolution of the oxide leading up to this structure is discussed and a model is presented.

  5. 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.

  6. 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.

  7. An investigation into the effects of hydrogen on the fracture and deformation of Alloy X-750

    SciTech Connect

    Symons, Douglas M.

    1994-11-01

    this study investigated the effect of hydrogen on the fracture of a nickel-base superalloy, Alloy X-750 in the solution treated and aged (HTH) condition. The effect of hydrogen was examined through tensile testing and fracture toughness testing incorporating observations from scanning electron microscopy and light microscopy.

  8. The effect of thermal treatment on the fracture properties of alloy X-750 in aqueous environments

    SciTech Connect

    Ballinger, R.; Elliott, C.S.; Hwang, I.S.; Prybylowski, J.

    1993-05-01

    Alloy X-750 is a high strength, age hardenable nickel-base alloy used in light water nuclear reactors. The excellent corrosion resistance and high temperature strength of alloy X-750 make it suitable for use in a variety of structure components in both pressurized water reactors and boiling water reactors. These applications involve exposure of highly stressed material to aqueous media. Operational stresses are subject to low frequency thermally induced fluctuations and high frequency flow induced fluctuations. In general, alloy X-750 has performed well in light water reactors. However, an economically significant number of components have failed unexpectedly due to localized forms of attack such as corrosion fatigue and stress corrosion cracking. Thermal processing history is known to play a significant role in the fracture properties of alloy X-750 in aqueous environments. While thermal treatments have been developed recently to improve performance, in many cases the reason for improved performance remains unclear. Therefore, identification of the mechanisms responsible for the degradation of fracture properties in aqueous environments is necessary. As a corollary it is necessary to achieve an understanding of how thermal treatment influences microstructure and, in turn, how microstructure influences fracture properties in aqueous environments. This report discusses five thermal treatments which were studied: (1) SA-1 hr at 1093{degree}C, (2) AH - 24 hr at 885{degree}C + 20 hr at 704{degree}C, (3) HTH - 1 hr at 1093{degree}C + 20 hr at 704{degree}C, (4) AHTH - 1 hr at 1093{degree}C + 24 hr at 885{degree}C + 20 hr at 704{degree}C, and (5) HOA - 1 hr at 1093{degree}C + 100 hrs at 760{degree}C. Microstructural characterization of these materials was accomplished through the use of optical microscopy, transmission electron microscopy,scanning transmission electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffractometry.

  9. The effect of hydrogen on the fracture toughness of alloy X-750 at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Symons, Douglas M.

    Ni-Cr-Fe alloys are widely used in pressurized water nuclear reactors (PWR). These alloys are susceptible to stress corrosion cracking (SCC) in PWR environments. There have been numerous mechanisms of crack advance proposed to describe the SCC of the nickel-base alloys in a PWR environment including slip/film rupture/oxidation and hydrogen embrittlement. It has also been suggested that there is not sufficient evidence to implicate hydrogen in the PWR SCC of nickel-base alloys. This program evaluated the effect of hydrogen on the embrittlement of a nickel-base alloy, alloy X-750, at elevated temperatures with a hydrogen concentration typical of what may be developed from the corrosion reaction. Fracture toughness values and the tearing resistance of alloy X-750 were evaluated in hydrogen gas and in air 260°C and 338°C. It was shown that at 260°C and 338°C alloy X-750 was severely embrittled in high pressure hydrogen gas. Further, the fracture morphology changed from predominantly transgranular ductile dimple fracture in air to predominantly intergranular fracture in hydrogen. The fracture morphology in hydrogen was similar to that found for PWR SCC of this material. This work supports a hydrogen-enhanced fracture mechanism contributing to the SCC of nickel-base alloys at elevated temperatures.

  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

    2012-02-01

    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.

  11. 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.

  12. 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.

  13. The effect of hydrogen on the fracture of alloy x-750

    NASA Astrophysics Data System (ADS)

    Symons, Douglas M.; Thompson, Anthony W.

    1996-01-01

    The effect of hydrogen on the fracture of a nickel-base superalloy, alloy X-750, was investigated in the HTH condition. The effect of hydrogen was examined through tensile testing incorporating observations from scanning electron microscopy and light microscopy. The ductility at 25 °C, as measured by elongation to failure for tensile specimens, was reduced from 21 pct for noncharged specimens to 7.3 pct for 5.7 ppm hydrogen and to 3.5 pct for 65 ppm hydrogen. The elongation to failure was a function of the strain rate and test temperature. For hydrogen-charged specimens, the elongation decreased as the strain rate decreased at a constant temperature, while for a constant strain rate and varying temperature, there was a maximum in embrittlement near 25 °C and no embrittlement at -196 °C. For the noncharged specimens, the elongation monotonically increased as temperature increased, while there was no noticeable effect of strain rate. Prestraining prior to charging dramatically decreased elongation after hydrogen charging. When the strain rate was increased on the prestrained specimens, more plastic deformation was observed prior to failure. Failure did not occur until the flow stress was reached, supporting the proposition that plasticity is required for failure. The intergranular failure mechanism in alloy X-750 was a microvoid initiation process at grain boundary carbides followed by void growth and coalescence. The void initiation strain, as determined from tensile data and from sectioning unfractured specimens, was observed to be much lower in the hydrogen-charged specimens as compared to noncharged specimens. The reduced ductility may be explained by either a reduction of the interfacial strength of the carbide-matrix interface or a local hydrogen pressure at the carbide-matrix interface.

  14. The effect of hydrogen on the fracture toughness of alloy X-750

    NASA Astrophysics Data System (ADS)

    Symons, Douglas M.; Thompson, Anthony W.

    1997-03-01

    The effect of hydrogen on the fracture toughness behavior of a nickel-base superalloy, Alloy X-750, in the solutionized and aged condition was investigated. Notched bend specimens were tested to determine if the fracture process was stress or strain controlled. The fracture was observed to initiate at a distance between the location of maximum stress and maximum strain, suggesting that fracture required both a critical stress and strain. The effect of hydrogen was further investigated and modeled using fracture toughness testing and fractographic examination. The fracture toughness of the non-charged specimen was 147 MPasqrt m . Charging with hydrogen decreased the fracture toughness, K lc, to 52 MPasqrt m at a rapid loading rate and further decreased the toughness to 42 MPasqrt m for a slow loading rate. This is consistent with the rate-limiting step forthe embrittlement process being hydrogen diffusion. The fracture morphology for the hydrogen-charged specimens was intergranular ductile dimple, while the fracture morphology of noncharged specimens was a mixture of large transgranular dimples and fine intergranular dimples. The intergranular failure mechanism in Alloy X-750 was a microvoid initiation process at grain boundary carbides followed by void growth and coalescence. One role of hydrogen was to reduce the void initiation strain for the fine intergranular carbides. Hydrogen may have also increased the rate of void growth. The conditions ahead of a crack satisfy the critical stress criterion at a much lower applied stress intensity factor than for the critical fracture strain criterion. A model based on a critical fracture strain criterion is shown to predict the fracture behavior.

  15. Corrosion of pre-oxidized nickel alloy X-750 in simulated BWR environment

    NASA Astrophysics Data System (ADS)

    Tuzi, Silvia; Lai, Haiping; Göransson, Kenneth; Thuvander, Mattias; Stiller, Krystyna

    2017-04-01

    Samples of pre-oxidized Alloy X-750 were exposed to a simulated boiling water reactor environment in an autoclave at a temperature of 286 °C and a pressure of 80 bar for four weeks. The effect of alloy iron content on corrosion was investigated by comparing samples with 5 and 8 wt% Fe, respectively. In addition, the effect of two different surface pre-treatments was investigated. The microstructure of the formed oxide scales was studied using mainly electron microscopy. The results showed positive effects of an increased Fe content and of removing the deformed surface layer by pickling. After four weeks of exposure the oxide scale consists of oxides formed in three different ways. The oxide formed during pre-oxidization at 700 °C, mainly consisting of chromia, is partly still present. There is also an outer oxide consisting of NiFe2O4 crystals, reaching a maximum size of 3 μm, which has formed by precipitation of dissolved metal ions. Finally, there is an inner nanocrystalline and porous oxide, with a metallic content reflecting the alloy composition, which has formed by corrosion.

  16. 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.

  17. Inhibition of stress corrosion cracking of Alloy X-750 by prestrain

    SciTech Connect

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

    1997-03-01

    Tests of precracked and as-notched compact tension specimens were conducted in 3600C hydrogenated water to determine the effect of prestrain on the stress corrosion cracking (SCC) resistance of Alloy X-750 in the HTH, AH and HOA heat treated conditions. Prestraining is defined as the intentional application of an initial load (or strain) that is higher than the final test load. Prestrain was varied from 10% to 40% (i.e., the initial to final load ratios ranged from 1.1 to 1.4). Other variables included notch root radius, stress level and irradiation. Specimens were bolt-loaded to maintain essentially constant displacement conditions during the course of the test. The frequent heat up and cooldown cycles that were necessary for periodic inspections provided an opportunity to evaluate the effect of test variables on rapid low temperature crack propagation to which this alloy is subject. For Condition HTH, application of 20% to 40% prestrain either eliminates or significantly retards SCC initiation in as-notched specimens and the onset of crack growth in precracked specimens. In addition, this procedure reduces the propensity for low temperature crack growth during cooldown. Similar results were observed for precracked HOA specimens. Application of 20% prestrain also retards SCC in as-notched and precracked AH specimens, but the effects are not as great as in Condition HTH. Prestraining at the 10% level was found to produce an inconsistent benefit. In-reactor SCC testing shows that prestrain greatly improves the in-flux and out-of-flux SCC resistance of Condition HTH material. No SCC was observed in precracked specimens prestrained 30%, whereas extensive cracking was observed in their nonprestrain counterparts.

  18. 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.

  19. 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.

  20. Cryogenic fatigue data developed for Inconel 718

    NASA Technical Reports Server (NTRS)

    Schmidt, E. H.

    1967-01-01

    Data were obtained on the cryogenic fatigue properties of Inconel 718 bar using axial loading and rotating beam fatigue tests. Results also disclosed the fatigue properties of Inconel 718 sheet materials.

  1. Strength of Rewelded Inconel 718

    NASA Technical Reports Server (NTRS)

    Bayless, E.; Lovoy, C. V.; Mcllwain, M. C.; Munafo, P.

    1982-01-01

    Inconel 718, nickel-based alloy used extensively for high-temperature structural service, welded repeatedly without detriment to its strength. According to NASA report, tests show 12 repairs on same weld joint do not adversely affect ultimate tensile strenth, yield strength, fatigue strength, metallurgical grain structures, or ability of weld joint to respond to post weld heat treatments.

  2. Characterization of carbon deposits from jet fuel on Inconel 600 and Inconel X surfaces

    SciTech Connect

    Altin, O.; Eser, S.

    2000-03-01

    Flow reactor experiments were conducted to study carbon deposit formation from decomposition of a jet fuel (JP-8) at 500 C and 500 psig for 5 h on the surface of two superalloys, Inconel 600 and Inconel X. The deposits collected on superalloy surfaces were characterized by temperature-programmed oxidation, size exclusion microscopy, and energy-dispersive X-ray spectroscopy. Significantly lower deposition on Inconel X compared to that on Inconel 600 was attributed to the presence of minor elemental compounds, such as Al, T, Nb, and Ta in the Inconel X alloy.

  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. Materials data handbook, Inconel alloy 718

    NASA Technical Reports Server (NTRS)

    Sessler, J.; Weiss, V.

    1967-01-01

    Materials data handbook on Inconel alloy 718 includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures and other pertinent engineering information required for the design and fabrication of components and equipment utilizing this alloy.

  5. 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.

  6. Detection of Cracks in Aluminum Structure Beneath Inconel Repair Bushings

    DTIC Science & Technology

    2008-04-01

    conductivity (i.e. Inconel 718 ) – Primary challenge then becomes detecting the weak eddy current field in the structure beyond the bushing wall...was able to be selected with inspectability as a goal. – Inconel 718 • low permeability (~μ0) • low conductivity (< 2% IACS) • Combined with...Detection of Cracks in Aluminum Structure beneath Inconel Repair Bushings Mr. Kenneth J. LaCivita (USAF) AFRL/RXSA Air Force Research Laboratory

  7. Microstructural Evolution of Inconel 625 and Inconel 686CPT Weld Metal for Clad Carbon Steel Linepipe Joints: A Comparator Study

    NASA Astrophysics Data System (ADS)

    Maltin, Charles A.; Galloway, Alexander M.; Mweemba, Martin

    2014-07-01

    Microstructural evolution of Inconel 625 and Inconel 686CPT filler metals, used for the fusion welding of clad carbon steel linepipe, has been investigated and compared. The effects of iron dilution from the linepipe parent material on the elemental segregation potential of the filler metal chemistry have been considered. The results obtained provide significant evidence to support the view that, in Inconel 686CPT weld metal, the segregation of tungsten is a function of the level of iron dilution from the parent material. The data presented indicate that the incoherent phase precipitated in the Inconel 686CPT weld metal has a morphology that is dependent on tungsten enrichment and, therefore, iron dilution. Furthermore, in the same weld metal, a continuous network of finer precipitates was observed. The Charpy impact toughness of each filler metal was evaluated, and the results highlighted the superior impact toughness of the Inconel 625 weld metal over that of Inconel 686CPT.

  8. 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.

  9. Hot corrosion behavior of Ni based Inconel 617 and Inconel 738 superalloys

    NASA Astrophysics Data System (ADS)

    El-Awadi, G. A.; Abdel-Samad, S.; Elshazly, Ezzat S.

    2016-08-01

    Superalloys are extensively used at high temperature applications due to their good oxidation and corrosion resistance properties in addition to their high stability were made at high temperature. Experimental measurements of hot corrosion at high temperature of Inconel 617 and Inconel 738 superalloys. The experiments were carried out at temperatures 700 °C, 800 °C and 900 °C for different exposure times to up to 100 h. The corrosive media was NaCl and Na2SO4 sprayed on the specimens. Seven different specimens were used at each temperature. The corrosion process is endothermic and the spontaneity increased by increasing temperature. The activation energy was found to be Ea = 23.54 and Ea = 25.18 KJ/mol for Inconel 738 and Inconel 617 respectively. X-ray diffraction technique (XRD) was used to analyze the formed scale. The morphology of the specimen and scale were examined by scanning electron microscopy (SEM). The results show that the major corrosion products formed were NiCr2O4, and Co Cr2O4 spinles, in addition to Cr2O3.

  10. Influence of gaseous hydrogen on Inconel 718

    NASA Technical Reports Server (NTRS)

    Walter, R. J.; Chandler, W. T.

    1974-01-01

    The embrittlement of Inconel 718 by exposure to 34.5 MN/sq m hydrogen at ambient temperature was found to be a function of both forming operation and heat treatment. The embrittlement, as measured by reduction of notch strength in hydrogen as compared to helium, was decreased by a fine-grain size and was most severe for coarse-grained structures containing a continuous or nearly continuous precipitate tentatively identified as Ni3Cb. Tests performed on unnotched specimens showed that the strain at which surface cracks initiate in 34.5 MN/sq m hydrogen was approximately 3% and was independent of prior forming operation or heat treatment.

  11. 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.

  12. Mechanical properties of Inconel 617 and 618

    SciTech Connect

    McCoy, H E; King, J F

    1985-02-01

    Inconel 617 and 618 were evaluated for application in high-temperature gas-cooled reactors (HTGRs). Techniques were developed for making sound welds, and tests were performed on base and weld metals. Specimens of both materials were aged to 20,000 h to evaluate thermal stability. Short-term tensile tests on alloy 617 showed that aging severely reduced the strain at fracture at both ambient and elevated temperatures. The impact energy at ambient temperature was severely degraded by aging. Creep tests showed that fracture occurred at 593 through 704{sup 0}C after only 1 to 2% strain, and higher strains were noted at higher temperatures. There was no detectable difference between the creep behavior in air and that in HTGR helium environments. Inconel alloy 618 had excellent stability during aging. Fracture strains in short-term tensile tests and impact energies in impact tests remained high after aging. The creep properties of alloy 618 were equivalent in air and in HTGR helium. Both alloys were carburized during creep testing in HTGR helium, and the rate of carburization became rather high at 760{sup 0}C and higher temperatures. 49 figures, 20 tables.

  13. Fatigue Behavior of Inconel 718 TIG Welds

    NASA Astrophysics Data System (ADS)

    Alexopoulos, Nikolaos D.; Argyriou, Nikolaos; Stergiou, Vasillis; Kourkoulis, Stavros K.

    2014-08-01

    Mechanical behavior of reference and TIG-welded Inconel 718 specimens was examined in the present work. Tensile, constant amplitude fatigue, and fracture toughness tests were performed in ambient temperature for both, reference and welded specimens. Microstructure revealed the presence of coarse and fine-grained heat-affected zones. It has been shown that without any post-weld heat treatment, welded specimens maintained their tensile strength properties while their ductility decreased by more than 40%. It was found that the welded specimens had lower fatigue life and this decrease was a function of the applied fatigue maximum stress. A 30% fatigue life decrease was noticed in the high cycle fatigue regime for the welded specimens while this decrease exceeded 50% in the low cycle fatigue regime. Cyclic stress-strain curves showed that Inconel 718 experiences a short period of hardening followed by softening for all fatigue lives. Cyclic fatigue response of welded specimens' exhibited cyclically stable behavior. Finally, a marginal decrease was noticed in the Mode I fracture toughness of the welded specimens.

  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. 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.

  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. Brazing Inconel 625 Using the Copper Foil

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Shiang; Wang, Cheng-Yen; Shiue, Ren-Kae

    2013-12-01

    Brazing Inconel 625 (IN-625) using the copper foil has been investigated in this research. The brazed joint is composed of nanosized CrNi3 precipitates and Cr/Mo/Nb/Ni quaternary compound in the Cu/Ni-rich matrix. The copper filler 50 μm in thickness is enough for the joint filling. However, the application of Cu foil 100 μm in thickness has little effect on the shear strength of the brazed joint. The specimen brazed at 1433 K (1160 °C) for 1800 seconds demonstrates the best shear strength of 470 MPa, and its fractograph is dominated by ductile dimple fracture with sliding marks. Decreasing the brazing temperature slightly decreases the shear strength of the brazed joint due to the presence of a few isolated solidification shrinkage voids smaller than 15 μm. Increasing the brazing temperature, especially for the specimen brazed at 1473 K (1200 °C), significantly deteriorates the shear strength of the joint below 260 MPa because of coalescence of isothermal solidification shrinkage voids in the joint. The Cu foil demonstrates potential in brazing IN-625 for industrial application.

  18. Ion-irradiation-induced hardening in Inconel 718

    NASA Astrophysics Data System (ADS)

    Hunn, J. D.; Lee, E. H.; Byun, T. S.; Mansur, L. K.

    2001-07-01

    Inconel 718 is a material under consideration for areas in the target region of the spallation neutron source (SNS), now under construction at Oak Ridge National Laboratory (ORNL) in the US. In these positions, displacement damage from protons and neutrons will affect the mechanical properties. In addition, significant amounts of helium and hydrogen will build up in the material due to transmutation reactions. Nanoindentation measurements of solution-annealed (SA) Inconel 718 specimens, implanted with Fe-, He-, and H-ions to simulate SNS target radiation conditions, have shown that hardening occurs due to ion-induced displacement damage as well as due to the build-up of helium bubbles in the irradiated layer. Precipitation-hardened (PH) Inconel 718 also exhibited hardening by helium build-up but showed softening as a function of displacement damage due to dissolution of the γ ' and γ″ precipitates.

  19. Graphite to Inconel brazing using active filler metal

    SciTech Connect

    King, J.F.; Baity, F.W.; Walls, J.C.; Hoffman, D.J.

    1989-01-01

    Ion cyclotron resonant frequency (ICRF) antennas are designed to supply large amounts of auxiliary heating power to fusion-grade plasmas in the Toroidal Fusion Test Reactor (TFTR) and Tore Supra fusion energy experiments. A single Faraday shield structure protects a pair of resonant double loops which are designed to launch up to 2 MW of power per loop. The shield consists of two tiers of actively cooled Inconel alloy tubes with the front tier being covered with semicircular graphite tiles. Successful operation of the antenna requires the making of high integrity bonds between the Inconel tubes and graphite tiles by brazing. This paper discusses this process.

  20. 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.

  1. 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.

  2. 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.

  3. Microstructure And Weld Cracking In Inconel 718(R)

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.

    1988-01-01

    Theories on relationship between metallurgy and microfissuring confirmed. Report describes research on effects of microstructure on cracking of heat-affected zones of welds in Inconel 718(R) alloy. In experimental studies, specimens subjected to various combinations of time-varying thermal and mechanical stresses to simulate welding conditions and to identify physical and chemical effects causing microfissuring.

  4. 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.

  5. Weld microfissuring in Inconel 718 minimized by minor elements

    NASA Technical Reports Server (NTRS)

    Morrison, T. J.; Shira, C. S.; Weisenberg, L. A.

    1968-01-01

    Manganese, silicon, and magnesium markedly reduce the tendency of Inconel 718 to weld microfissuring. By combining a manganese, 0.20 percent by content, with silicon, greater than 0.25 percent content, or by adding 20 ppm of magnesium, the weld microfissuring decreased in the standard alloy.

  6. Stainless steel 301 and Inconel 718 hydrogen embrittlement

    NASA Technical Reports Server (NTRS)

    Allgeier, R. K.; Forman, R.

    1970-01-01

    Conditions and results of tensile tests of 26 Inconel 718 and four cryoformed stainless steel specimens are presented. Conclusions determine maximum safe hydrogen operating pressure for cryogenic pressure vessels and provide definitive information concerning flaw growth characteristics under the most severe temperature and pressure conditions

  7. 2500 KW Ship Service Turbine Generator Casing Welded Inconel Plug Failure and Repair Analysis

    DTIC Science & Technology

    2012-06-01

    2500 KW SHIP SERVICE TURBINE GENERATOR CASING WELDED INCONEL PLUG FAILURE AND REPAIR ANALYSIS John S. Shields, P.E. US Navy NSWCCD... Inconel X750) should have received post weld heat treatment (PWHT) to avoid embrittlement and the subsequent cracking of the HAZ. If PWHT was not...to be accomplished, an alloy such as Inconel 600 should have been selected. It is noted that PWHT risks warping the casing and cannot be performed

  8. Corrosion fatigue of Inconel 718 and Incoloy 903

    NASA Technical Reports Server (NTRS)

    Franklin, D. B.; Nelson, E. E.

    1981-01-01

    Corrosion fatigue tests were conducted on Inconel 718 and Incoloy 903 in distilled water, 500 ppm NaCl, and 3.5% NaCl. Results were compared to the endurance limit in air. For Inconel 718, the corrosion fatigue strength (CFS) IN 3.5% NaCl WAS 328 MPa or 75 percent of the endurance limit. For Incoloy 903, the CFS ranged from 234 MPa in distilled water (68 percent of the endurance limit) to 103 MPa in 3.5% NaCl (30 percent of the endurance limit). Results indicate that, for components which have limited fatigue life, an evaluation of the combined effects of fatigue and the corrosive atmosphere must be considered in projecting useful lifetimes.

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  12. Effect of pulse duty cycle on Inconel 718 laser welds

    NASA Technical Reports Server (NTRS)

    McCay, M. H.; McCay, T. D.; Dahotre, N. B.; Sharp, C. M.; Sedghinasab, A.; Gopinathan, S.

    1989-01-01

    Crack sensitive Inconel 718 was laser pulse welded using a 3.0 kW CO2 laser. Weld shape, structure, and porosity were recorded as a function of the pulse duty cycle. Within the matrix studied, the welds were found to be optimized at a high (17 ms on, 7 ms off) duty cycle. These welds were superior in appearance and lack of porosity to both low duty cycle and CW welds.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Analysis and Elimination of High Temperature Notch Induced Microcrack Initiation in Inconel 718 Nickel-Based Alloy

    DTIC Science & Technology

    1989-01-01

    10) the particle will be sheared. I . . 22 B-2 APPLICATION TO INCONEL 718 ALLOY Taking an actual case of Inconel 718 alloy tested at 10000 F, the...stress static test at 1000OF on unnotched tensile specimens of inconel 718 *, show a tensile yield point of 135 ksice. This is in direct agreement with...energy distribution of solution treated* and aged**. Inconel 718 specimens that were stress rupture tested below the yield stress, at elevated

  18. Mechanical properties and microstructure evaluation of powder bed fused inconel 625 nickel alloy

    SciTech Connect

    Brand, Michael J.

    2016-04-19

    The objectives of this report were to optimize and fabricate full density Inconel 625 samples using direct metal laser fusion, an additive manufacturing process; and to compare and evaluate precipitation and solid solution strengthening of Inconel 625 produced by PBF to conventional processed material.

  19. 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.

  20. Mean stress effects in biaxial fatigue of Inconel 718

    SciTech Connect

    Socie, D.F.; Shield, T.W.

    1984-07-01

    Biaxial fatigue tests were conducted on Inconel 718 thin-walled tubular specimens to quantify the effect of mean stress. The specimens were loaded in combined tension and torsion in strain control at room temperature. Fatigue lives ranged from 3000 to 15,000 cycles depending on the mean stress. These data were correlated with a parameter based on the maximum plastic shear strain amplitude, normal strain amplitude and mean normal stress on the plane of maximum shear strain amplitude. This parameter was combined with the Coffin-Manson equation for estimating fatigue lives. Observations of the cracking behavior show that mean stress affects the rate of crack growth and distribution of cracks.

  1. 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.

  2. 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).

  3. 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.

  4. Thermal Decomposition of Some Linear Perfluoroalkanes in an Inconel Tube

    NASA Technical Reports Server (NTRS)

    Fielder, W. L.

    1961-01-01

    The products of the pyrolysis reactions of perfluoropropane, perfluoroethane, and carbon tetrafluoride in an Inconel bomb are described. The values for the energy of activation and frequency factor for the first-order pyrolysis reactions are respectively: (1) 80 kcal. per mole and 2x10(exp14) sec.(exp-1) for perfluoropropane; (2) 53 kcal. per mole and 3x10(exp7) sec.(exp-1) for perfluoroethane; and (3) 96 kcal. per mole and 4x10(exp13) sec.(exp-1) for carbon tetrafluoride.

  5. 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.

  6. Structural Performance of Inconel 625 Superalloy Brazed Joints

    NASA Astrophysics Data System (ADS)

    Chen, Jianqiang; Demers, Vincent; Cadotte, Eve-Line; Turner, Daniel; Bocher, Philippe

    2016-12-01

    The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints under various lap distance-to-thickness ratios. The fatigue crack initiation and crack growth modes were examined via metallographic analysis, and the effect of local stress on fatigue life was assessed by finite element simulations. The fatigue results show that fatigue strength and endurance limit increase with overlap distance, leading to a relatively large scatter of results. Fatigue cracks nucleated in the high-stressed region of the weld fillets from brittle eutectic phases or from internal brazing cavities. The present work proposes to rationalize the results by using the local stress at the brazing fillet. When using this local stress, all fatigue-obtained results find themselves on a single S-N curve, providing a design curve for any joint configuration in fatigue solicitation.

  7. 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.

  8. 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.

  9. Structural Performance of Inconel 625 Superalloy Brazed Joints

    NASA Astrophysics Data System (ADS)

    Chen, Jianqiang; Demers, Vincent; Cadotte, Eve-Line; Turner, Daniel; Bocher, Philippe

    2017-02-01

    The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints under various lap distance-to-thickness ratios. The fatigue crack initiation and crack growth modes were examined via metallographic analysis, and the effect of local stress on fatigue life was assessed by finite element simulations. The fatigue results show that fatigue strength and endurance limit increase with overlap distance, leading to a relatively large scatter of results. Fatigue cracks nucleated in the high-stressed region of the weld fillets from brittle eutectic phases or from internal brazing cavities. The present work proposes to rationalize the results by using the local stress at the brazing fillet. When using this local stress, all fatigue-obtained results find themselves on a single S- N curve, providing a design curve for any joint configuration in fatigue solicitation.

  10. Influence of hydrogen environments on crack growth in Inconel 718

    NASA Technical Reports Server (NTRS)

    Walter, R. J.; Chandler, W. T.

    1978-01-01

    The effect of hydrogen environments on sustained-load and cyclic-load crack growth in Inconel 718 was investigated using fracture-mechanics-type specimens. The sustained-load crack growth was determined to be a function of heat-treatment condition, temperature, and hydrogen pressure. The threshold stress intensity for subcritical crack growth was independent of hydrogen pressure at pressures greater than 21 MN/sq m (3000 psi). The cyclic-load crack growth rate in Inconel 718 at low and moderate stress intensity ranges increased with increasing hydrogen pressure. Decreasing the cyclic frequency from 1.0 to 0.1 Hz considerably increased the cyclic crack growth rate at 0.069 MN/sq m (10 psi) and at 68.9 MN/sq m (10,000 psi) hydrogen pressure. A series of measurements performed between 1.0 and 0.1 Hz showed that the crack growth rate increased as a complex function of the time per cycle.

  11. Considerations on repeated repairing of weldments in Inconel 718 alloy

    NASA Technical Reports Server (NTRS)

    Bayless, E. O.; Lovoy, C. V.; Mcilwain, M. C.; Munafo, P.

    1981-01-01

    The effects of repeated weld repairs on the metallurgical characteristics, high cycle fatigue (HCF), and tensile properties of Inconel 718 butt weld joints were determined. A 1/4 in thick plate and a 1/2 in thick plate were used as well as tungsten inert gas welding, and Inconel 718 filler wire. Weld panels were subjected to 2, 6, and 12 repeated repairs and were made in a highly restrained condition. Post weld heat treatments were also conducted with the welded panel in the highly restrained condition. Results indicate that no significant metallurgical anomaly is evident as a result of up to twelve repeated weld repairs. No degradation in fatigue life is noted for up to twelve repeated repairs. Tensile results from specimens which contained up to twelve repeated weld repairs revealed no significant degradation in UTS and YS. However, a significant decrease in elongation is evident with specimens (solution treated and age hardened after welding) which contained twelve repeated repairs. The elongation loss is attributed to the presence of a severe notch on each side (fusion line) of the repair weld bead reinforcement.

  12. Field assisted hot pressing of sintering Inconel 718 MIM samples

    NASA Astrophysics Data System (ADS)

    Dugauguez, Olivier; Torralba, Jose Manuel; Barriere, Thierry; Gelin, Jean-Claude

    2016-10-01

    In this investigation on samples obtained by Metal Injection Molding (MIM), the conventional way of sintering in a furnace will be compared to Field Assisted Hot pressing (FAHP) sintering. The difficulty of this method is to be able to control the shrinkage of the sample and so its shape. It has yet not been investigated with a super alloy powder and so, the effects of a high sintering rate. By accelerating the sintering kinetics, the thermal behavior may be modified. Hence, the behavior of the Inconel 718 sintered by FAHP has been investigated. The sintered samples were all injected from a feedstock composed of a fine particle Inconel powder and a binder principally composed of Cellulose Acetate Butyrate CAB and Poly-Ethylene Glycol PEG. The effects of the two methods on the microstructure and the mechanical properties are then compared. There was no difference in distribution of pores between the conventional sintering and the FAHP sintering but a finer grain size showed better hardness.

  13. Ultra-high temperature mechanical performance of INCONEL 690

    NASA Astrophysics Data System (ADS)

    Venkatesh, Vasisht

    The elevated temperature mechanical performance of INCONEL 690 at ultra-high temperatures (0.6-0.9 of alloy melting temperature, Tsb{m}) has been investigated to assess the underlying deformation mechanisms and develop a new life prediction methodology. In the first part of the investigation the hardening response of INCONEL 690 during tensile deformation between 200{-}1200sp°C was examined. Analysis of these results suggests that, dependent on deformation temperature, the hardening behavior of INCONEL 690 can be described by the Bodner-Partom (B-P) or Kocks-Mecking (K-M) dislocation-dislocation interaction and/or by a modified K-M dislocation-periodic barrier interaction model. Transmission electron microscopy (TEM) confirmed the presence of this hardening transition from one associated with dislocation tangle formation at low temperatures, i.e., 200{-}600sp°C, to periodically spaced dislocation walls forming parallelogram cell structures at intermediate temperatures and high stresses, i.e., 650{-}700sp°C, and at higher temperatures 750{-}1200sp°C. The elevated temperature creep behavior of INCONEL 690 has been examined from 900 to 1200sp°C\\ (0.7{-}0.9\\ Tsb{m}) at constant stresses between 6 to 33 MPa (sigma/mu = 1.5 × 10sp{-4} to 9.5 × 10sp{-4}). Two complimentary strain-time responses were observed. A normal strain-time response, characterized by decreasing creep rate with increasing time until steady state, was observed under all normalized stresses at 900sp°C. Under these conditions creep deformation was associated with intragranular dislocation climb and glide. A second periodic oscillatory strain-time response was observed at higher temperatures, 1050{-}1200sp°C, and intermediate to low stresses, sigma/mu = 1.65 × 10sp{-4}{-}4.5 × 10sp{-4}. Under these conditions repetitive grain boundary sliding and migration controlled creep deformation. The last part of the study involved the development of a design methodology for life prediction at ultra

  14. Effect of Frequency on Fatigue Crack Growth Rate of Inconel 718 at High Temperature

    DTIC Science & Technology

    1987-06-01

    Potential 6 and Displacement Measurements. 2 Fractured Specimens of Inconel 718 Showing 13 Different Cracking*Regions Corresponding to Test Under Different...Conditions. 3 Typical a vs N Experimental Data with the 16 Fitted Linear Regression Line. 4 Fatigue Crack Growth Rate (da/dN) for 17 Inconel 718 as a...Temperature Air Data are Given. 5 Time Rate of Crack Growth, (da/dt) for 18 Inconel 718 as a Function of Frequency at Kmax = 40 MPa-ml/ 2 , R = 0.1

  15. Sustained Load Crack Growth in Inconel 718 Under Non-Isothermal Conditions.

    DTIC Science & Technology

    1983-12-01

    Center-cracked specimens of Inconel 718 are used. The isothermal baseline data are used to predict crack growth rates for the non-isothermal tests using...Non-isothermal creep crack growth testing was conducted using centercracked specimens of Inconel 718 . Specimens were subjected to low frequency thermal...temperature change rates are used. \\-* ->he predicted creep crack growth rates were within a factor of two of the actual test data . The time-to-failure

  16. 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.

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

    NASA Technical Reports Server (NTRS)

    Marchand, N.; Pelloux, R. M.

    1985-01-01

    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. 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.

  19. 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.

  20. 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.

  1. Pulsed laser-assisted machining of Inconel 718 superalloy

    NASA Astrophysics Data System (ADS)

    Azhdari Tadavani, Soheila; Shoja Razavi, Reza; Vafaei, Reza

    2017-01-01

    Nickel-based superalloys including Inconel 718(IN718) are widely used in aerospace industries due to their superior high temperature strength, toughness, and corrosion resistance. These alloys are difficult to machine mainly because of their low thermal conductivity and high work hardening rate, which cause steep temperature gradient and high cutting forces at the tool edge. The application of laser assisted machining is the subject of many new researches since shear forces; surface coarsening and tool wear are reduced. The aim of this investigation was to evaluate laser assisted machining behavior of a 718 Inconel superalloy from the view point of machining specific energy, surface roughness, tool wear and chip appearance. Experimental apparatuses used included optical and scanning electron microscopy, spark emission spectroscopy, and EDS analysis. The results indicated that increasing the temperature to about 540 °C just ahead of primary shear zone, can result in 35% reduction of machining specific energy, in comparison with conventional machining. Furthermore, surface coarsening and tool wear were reduced by 22% and 23% respectively. Flank wear was the main deteriorating factor on cutting tools during laser assisted machining. SEM micrographs indicated that increase in temperature has no noticeable effect on finished workpiece surface. Analysis of variance obtained from regression analysis indicated that frequency of laser beam has the most influential effect on temperature. The optimum conditions for laser assisted machining of 718 superalloy is suggested as follows: 80 Hz frequency, 400 W power, 24 m/min cutting speed, and 0.052 mm/rev feed rate along with 540 °C temperature, 2.51 J/mm2 machining specific energy and 130 N cutting force.

  2. 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

  3. Microstructure and properties of laser-borided Inconel 600-alloy

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Dziarski, P.; Makuch, N.; Piasecki, A.; Miklaszewski, A.

    2013-11-01

    Nickel-based superalloys are used extensively for a variety of industrial applications involving high temperatures and aggressive environments. However, under conditions of appreciable mechanical wear (adhesive or abrasive), these materials have to be distinguished by suitable wear protection. The diffusion boronizing is the thermo-chemical treatment, which improves the tribological properties of nickel and its alloys. Nevertheless, the long duration of this process is necessary in order to obtain the layers of the thickness up to about 100 μm. Instead of the diffusion process, in this study the laser boriding is used for producing boride layer on Inconel 600-alloy. During the laser alloying, the external cylindrical surface of base material is coated by paste, including amorphous boron. Then the surface is re-melted by a laser beam. The high overlapping of multiple laser tracks (86%) causes the formation of uniform laser-alloyed layer in respect of the thickness. Laser re-melted zone, heat-affected zone and the substrate characterize the microstructure. In the re-melted zone, the three areas are observed: compact borides zone consisting of nickel, chromium and iron borides (close to the surface), zone of increased percentage of Ni-Cr-Fe-matrix (appearing in the greater distance from the surface) and zone of dominant Ni-Cr-Fe-matrix percentage (at the end of the layer). The hardness obtained is comparable to that-obtained in case of diffusion boriding. Simultaneously, the laser-borided layers are significantly thicker (about 346 or 467 μm depending on the laser power used). The significant increase in their abrasive wear resistance is observed. The wear intensity factors, as well as the relative mass loss of the laser-borided samples, are ten times smaller in comparison with untreated Inconel 600-alloy.

  4. 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

  5. Powder bed binder jet 3D printing of Inconel 718: Densification, microstructural evolution and challenges

    DOE PAGES

    Nandwana, Peeyush; Elliott, Amy M.; Siddel, Derek; ...

    2017-01-03

    Traditional manufacturing of Inconel 718 components from castings and thermomechanical processing routes involve extensive post processing and machining to attain the desired geometry. Additive manufacturing (AM) technologies including direct energy deposition (DED), selective laser melting (SLM), electron beam melting (EBM) and binder jet 3D printing (BJ3DP) can minimize scrap generation and reduce lead times. While there is extensive literature on the use of melting and solidification based AM technologies, there has been limited research on the use of binder jet 3D printing. In this paper, a brief review on binder jet additive manufacturing of Inconel 718 is presented. In addition,more » existing knowledge on sintering of Inconel 718 has been extended to binder jet 3D printing. We found that supersolidus liquid phase sintering (SLPS) is necessary to achieve full densification of Inconel 718. SLPS is sensitive to the feedstock chemistry that has a strong influence on the liquid volume fraction at the processing temperature. Based on these results, we discuss an empirical framework to determine the role of powder particle size and liquid volume fraction on sintering kinetics. In conclusion, the role of powder packing factor and binder saturation on microstructural evolution is discussed. The current challenges in the use of BJ3DP for fabrication of Inconel 718, as well as, extension to other metal systems, are presented.« less

  6. Low-temperature embrittlement of Ti-6Al-4V and Inconel-718 by high pressure hydrogen

    NASA Technical Reports Server (NTRS)

    Chandler, W. T.; Walter, R. J.

    1970-01-01

    Notched specimens of titanium alloy and Inconel-718 exhibit little reduction of notch strength at certain low temperatures under 2000 lb/sq in. hydrogen, unnotched specimens are not embrittled at these temperatures. The degree of Inconel-718 embrittlement is lower than earlier observations under 1000 lb/sq in. hydrogen.

  7. [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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Oxidation of Inconel alloy MA754 at low oxidation potential

    SciTech Connect

    Braski, D.N.; Goodell, P.D.; Cathcart, J.V.; Kane, R.H.

    1983-01-01

    It has been known for some time that the addition of small oxide particles to an 80 Ni-20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance was studied. Initial experiments were performed using inconel alloy MA754, which is nominally: 78 Ni, 20 Cr, 0.05 C, 0.3 Al, 0.5 Ti, 1.0 Fe, and 0.6 Y/sub 2/O/sub 3/ (wt %). Small disks (3 mm diam x 0.38 mm thick) were cut from MA754 plate stock and prepared with two different surface conditions. The first was prepared by mechanically polishing one side of a disk through 0.5 ..mu..m diamond on a syntron polisher while the second used an additional sulfuric acid-methanol electropolishing treatment to remove the cold-worked surface layer. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000/sup 0/C. Three different environments were investigated: hydrogen with nominal dew points of 0/sup 0/C, -25/sup 0/C, and -55/sup 0/C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by backpolishing to the oxide/metal interface. The particles were analyzed by EDS and SAD. Preliminary results are given.

  13. 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.

  14. 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.

  15. 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.

  16. Weldability testing of Inconel{trademark} filler metals

    SciTech Connect

    Hood, B.B.; Lin, W.

    1995-12-31

    This paper presents the findings of a research program aimed at quantifying the weld solidification cracking susceptibility and weld metal liquation cracking susceptibility of Inconel{trademark} filler materials 52, 82, 152 and 182 deposited on a variety of materials intended for pressurized water reactor applications. A cursory investigation on the repair weldability of Filler Metal 52 using the Gleeble{trademark} thermo-mechanical simulation technique is also included. The brittle temperature range (BTR) in the fusion zone and HAZ was determined using the longitudinal-Varestraint test and spot-Varestraint test, respectively, and used as a weldability index for quantification of susceptibility to weld solidification cracking and HAZ liquation cracking. Results from this study showed that Filler Metals 52 exhibited the best resistance to both weld solidification cracking and weld metal liquation cracking followed by 82, 152 and 182 for the base metal combinations tested in this study. Repair weldability study suggested that the resistance to weld metal liquation cracking of 52 all weld metal would not be significantly reduced after ten times of weld simulation at peak temperatures of 900 C and 1,300 C.

  17. 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.

  18. 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.

  19. Effects of tin on microstructure and mechanical behavior of Inconel 718

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Johnson, W. A.; Maurer, G. A.

    1984-01-01

    Columbium, for which the United States is 100 percent import reliant, is of strategic importance to the U.S. aerospace industry. A major amount of the Cb is used in Inconel 718. Should Cb sources be disrupted, it may be desired to use a grade of Cb melting stock having greater Sn content then the preferred vacuum rade. Additions of Sn to Inconel 718 were varied from none added to 1 wt %. The Sn additions below 800 ppm had no detrimental effects on 650 C stress rupture behavior; however, 1-wt % Sn severely degraded both life and ductility. Additions of Sn in excess of 200 ppm were slightly detrimental to the 425 C tensile yield strength and ductility. The Sn additions had no effect on the microstructure of Inconel 718 even after stress rupture testing for over 6000 hr at 650 C.

  20. On relationship between microfissuring and microstructure in the HAZ of Inconel 718

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.

    1982-01-01

    Inconel 718, as well as many other metals, is susceptible to intergranular hot cracking in the weld heat-affected-zone (HAZ). These cracks form near the solidus temperature of the metal during the welding process. This problem is of particular concern to NASA/MSFC because the SSME is primarily constructed of welded Inconel 718. The present program studied microfissuring in the weld HAZ of Inconel 718 by simulating HAZ thermal cycles with the Gleeble machine. Previous researchers have studied the instantaneous mechanical properties of the HAZ using the Gleeble. The present study examines the instantaneous microstructure of the HAZ. This approach showed that second phase structures, high in niobium, melt and wet the grain boundaries in the HAZ during welding. It is postulated that the resultant HAZ grain boundaries, enriched in niobium, act as preferred sites for microfissure nucleation as the weld zone cools.

  1. Response of Inconel 617 superalloy to combined ground-based and STS reentry exposure

    NASA Technical Reports Server (NTRS)

    Clark, R. K.; Unnam, J.

    1984-01-01

    Inconel 617 is a nickel-based superalloy which is being considered for heat-shield applications because of its high-temperature strength, good oxidation resistance and high emittance of oxidized surfaces. While the effects of simulated reentry conditions on emittance and oxidation of Inconel 617 have been studied, the combined effects of the ground-based environment with sea salt exposure and the reentry environment have not been evaluated. Experimental results are presented to show the effects of environmental simulation including ground-based and reentry exposure on the emittance and oxidation of Inconel 617. Specimens were exposed to simulated reentry at a surface temperature of 2000 F in the Langley Research Center Hypersonic Materials Environmental Test System (HYMETS) Facility with and without alternate exposures to an atmospheric seashore environment or a laboratory sea salt environment. This paper presents emittance, mass loss, oxide chemistry, and alloy composition data for the specimens.

  2. Effects on stress rupture life and tensile strength of tin additions to Inconel 718

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Johnson, W.

    1982-01-01

    Because Inconel 718 represents a major use of columbium and a large potential source of columbium for aerospace alloys could be that of columbium derived from tin slags, the effects of tin additions to Inconel 718 at levels which might be typical of or exceed those anticipated if tin slag derived columbium were used as a melting stock were investigated. Tin was added to 15 pound Inconel 718 heats at levels varying from none added to approximately 10,000 ppm (1 wt%). Limited 1200 F stress rupture testing was performed at stresses from 68,000 to 115,000 psi and a few tensile tests were performed at room temperature, 800 and 1200 F. Additions of tin in excess of 800 ppm were detrimental to ductility and stress rupture life.

  3. 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.

  4. 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.

  5. 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.

  6. Proton irradiation creep of Inconel 718 at 300°C

    NASA Astrophysics Data System (ADS)

    Scholz, R.; Matera, R.

    2000-12-01

    Torsional creep tests were conducted on Inconel 718 in the precipitation hardened condition under 17 MeV proton irradiation at 300°C upto a maximum dose of 0.35 dpa. The stress dependence of the irradiation creep rate was linear for the applied shear stresses which ranged from 150 to 450 MPa. The results are discussed in relation to the operating conditions of an ITER-like machine, where Inconel 718 bolts are used to mechanically attach the shielding blanket to the backplate. The irradiation creep induced stress relaxation amounted to about 30% after a dose of 0.35 dpa.

  7. Tensile properties of Inconel 718 after low temperature neutron irradiation

    NASA Astrophysics Data System (ADS)

    Byun, T. S.; Farrell, K.

    2003-05-01

    Tensile properties of Inconel 718 (IN718) have been investigated after neutron irradiation to 0.0006-1.2 dpa at 60-100 °C in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The alloy was exposed in solution-annealed (SA) and precipitation-hardened (PH) conditions. Before irradiation, the yield strength of PH IN718 was about 1170 MPa, which was 3.7 times higher than that of SA IN718. In the SA condition, an almost threefold increase in yield strength was found at 1.2 dpa, but the alloy retained a positive strain-hardening capability and a uniform ductility of more than 20%. Comparisons showed that the strain-hardening behavior of the SA IN718 is similar to that of a SA 316LN austenitic stainless steel. In the PH condition, the IN718 displayed no radiation-induced hardening in yield strength and significant softening in ultimate tensile strength. The strain-hardening capability of the PH IN718 decreased with dose as the radiation-induced dissolution of precipitates occurred, which resulted in the onset of plastic instability at strains less than 1% after irradiation to 0.16 or 1.2 dpa. An analysis on plastic instability indicated that the loss of uniform ductility in PH IN718 was largely due to the reduction in strain-hardening rate, while in SA IN718 and SA 316LN stainless steel it resulted primarily from the increase of yield stress.

  8. 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

  9. Microstructure, Fatigue Behavior, and Failure Mechanisms of Direct Laser-Deposited Inconel 718

    NASA Astrophysics Data System (ADS)

    Johnson, Alex S.; Shao, Shuai; Shamsaei, Nima; Thompson, Scott M.; Bian, Linkan

    2017-03-01

    Inconel 718 is considered to be a superalloy with a series of superior properties such as high strength, creep resistance, and corrosion resistance at room and elevated temperatures. Additive manufacturing (AM) is particularly appealing to Inconel 718 because of its near-net-shape production capability for circumventing the poor machinability of this superalloy. Nevertheless, AM parts are prone to porosity, which is detrimental to their fatigue resistance. Thus, further understanding of their fatigue behavior is required before their widespread use in load-bearing applications. In this work, the microstructure and fatigue properties of AM Inconel 718, produced in a Laser Engineered Net Shaping (LENS™) system and heat treated with a standard heat treatment schedule, are evaluated at room temperature. Fully reversed strain controlled fatigue tests were performed on cylindrical specimens with straight gage sections at strain amplitudes ranging from 0.001 mm/mm to 0.01 mm/mm. The fracture surfaces of fatigue specimens were inspected with a scanning electron microscope. The results indicate that the employed heat treatment allowed the large, elongated grains and dendritic structure of the as-built material to break down into smaller, equiaxed grains, with some dendritic structures remaining between layers. The AM specimens were found to possess lower fatigue resistance than wrought Inconel 718, and this is primarily attributed to the presence of brittle metal-carbide/oxide inclusions or pores near their surface.

  10. Hot-cracking studies of Inconel 718 weld- heat-affected zones

    NASA Technical Reports Server (NTRS)

    Thompson, E. G.

    1969-01-01

    Hot ductility tests, gas-tungsten-arc fillerless fusion tests, and circle patch-weld-restraint tests were conducted on Inconel 718 to better understand and correlate the weldability /resistance to hot cracking/ of the alloy. A correlation of the test results with composition, heat-treat condition, grain size, and microstructure was made.

  11. Microstructure, Fatigue Behavior, and Failure Mechanisms of Direct Laser-Deposited Inconel 718

    NASA Astrophysics Data System (ADS)

    Johnson, Alex S.; Shao, Shuai; Shamsaei, Nima; Thompson, Scott M.; Bian, Linkan

    2016-12-01

    Inconel 718 is considered to be a superalloy with a series of superior properties such as high strength, creep resistance, and corrosion resistance at room and elevated temperatures. Additive manufacturing (AM) is particularly appealing to Inconel 718 because of its near-net-shape production capability for circumventing the poor machinability of this superalloy. Nevertheless, AM parts are prone to porosity, which is detrimental to their fatigue resistance. Thus, further understanding of their fatigue behavior is required before their widespread use in load-bearing applications. In this work, the microstructure and fatigue properties of AM Inconel 718, produced in a Laser Engineered Net Shaping (LENS™) system and heat treated with a standard heat treatment schedule, are evaluated at room temperature. Fully reversed strain controlled fatigue tests were performed on cylindrical specimens with straight gage sections at strain amplitudes ranging from 0.001 mm/mm to 0.01 mm/mm. The fracture surfaces of fatigue specimens were inspected with a scanning electron microscope. The results indicate that the employed heat treatment allowed the large, elongated grains and dendritic structure of the as-built material to break down into smaller, equiaxed grains, with some dendritic structures remaining between layers. The AM specimens were found to possess lower fatigue resistance than wrought Inconel 718, and this is primarily attributed to the presence of brittle metal-carbide/oxide inclusions or pores near their surface.

  12. Effect of reduction of strategic columbium additions in Inconel 718 alloy on the structure and properties

    NASA Technical Reports Server (NTRS)

    Ziegler, K.; Wallace, J. F.

    1982-01-01

    The amount of columbium which can be removed from Inconel alloy 718 without degrading its high temperature properties was determined. The elements that are substituted are: vanadium and tungsten together and separately; increasing the molybdenum level from 3.0% to 5.8% and increasing the boron to 0.04%.

  13. Stress-corrosion cracking of Inconel alloy 600 in high-temperature water: an update. [PWR

    SciTech Connect

    Bandy, R.; van Rooyen, D.

    1983-01-01

    Inconel 600 has been tested in high-temperature aqueous media (without oxygen) in several tests. Data are presented to relate failure times to periods of crack initiation and propagation. Quantitative relationships have been developed from tests in which variations were made in temperature, applied load, strain rate, water chemistry, and the condition of the test alloy.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. Fatigue behavior of two alloys for Space Shuttle applications. [Inconel 903 and 718 for main engine

    NASA Technical Reports Server (NTRS)

    Adsit, N. R.; Block, S. J.

    1978-01-01

    Two superalloys used extensively in the Space Shuttle main engine are Incoloy 903 and Inconel 718. The fatigue behavior of the two alloys under varying conditions is considered. Three heats of Incoloy 903 and two of Inconel 718 were used in the study. Material was tested in several conditions, including mill polish, longitudinal mill polish, transverse mill polish, chemically milled, chemically milled plus shotpeened on one side and on both sides, gas tungsten arc welded, and electron beam welded. Both round and flat tensile specimens were tested in universal test machines. It was found that surface condition influences test results. Transverse scratches resulting from polishing and rougher surfaces lower the stress at runout in relation to that obtained on longitudinally polished and/or smooth-surfaced specimens.

  19. 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.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Lamikiz, A.; Tabernero, I.; Ukar, E.; López de Lacalle, L. N.; Delgado, J.

    2011-01-01

    This work presents different experimental results of the mechanical properties of Inconel® 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® 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.

  3. Investigation of Machine-ability of Inconel 800 in EDM with Coated Electrode

    NASA Astrophysics Data System (ADS)

    Karunakaran, K.; Chandrasekaran, M.

    2017-03-01

    The Inconel 800 is a high temperature application alloy which is classified as a nickel based super alloy. It has wide scope in aerospace engineering, gas Turbine etc. The machine-ability studies were found limited on this material. Hence This research focuses on machine-ability studies on EDM of Inconel 800 with Silver Coated Electrolyte Copper Electrode. The purpose of coating on electrode is to reduce tool wear. The factors pulse on Time, Pulse off Time and Peck Current were considered to observe the responses of surface roughness, material removal rate, tool wear rate. Taguchi Full Factorial Design is employed for Design the experiment. Some specific findings were reported and the percentage of contribution of each parameter was furnished

  4. Diffusion bonding of a superplastic Inconel 718SPF superalloy by electroless nickel plating

    SciTech Connect

    Yeh, M.S.; Chang, C.B.; Chuang, T.H.

    2000-02-01

    Although intimate contact can be obtained for diffusion bonding of a superplastic Inconel 718SPF superalloy under a low pressure of 7 MPa, the precipitates formed at the interface retarded achievement of a sound joint. The shear strength was only 41.5 MPa for an overlap length of 12 T (T = 1.3 mm, sheet thickness). The diffusion bondability of t his Inconel 718SPF superalloy was enhanced by electroless nickel plating. In this situation, the bonding shear strength increased to 70.4 MPa for the same overlap length of 12 T under the same bonding condition, regardless of the roughness of the surface to be bonded. Upon decreasing the overlap length from 12 to 6T, the bonding strength remained constant.

  5. Effects of heat input on the pitting resistance of Inconel 625 welds by overlay welding

    NASA Astrophysics Data System (ADS)

    Kim, Jun Seok; Park, Young IL; Lee, Hae Woo

    2015-03-01

    The objective of this study was to establish the relationship between the dilution ratio of the weld zone and pitting resistance depending on the heat input to welding of the Inconel alloy. Each specimen was produced by electroslag welding using Inconel 625 as the filler metal. In the weld zone of each specimen, dendrite grains were observed near the fusion line and equiaxed grains were observed on the surface. It was also observed that a melted zone with a high Fe content was formed around the fusion line, which became wider as the welding heat input increased. In order to evaluate the pitting resistance, potentiodynamic polarization tests and CPT tests were conducted. The results of these tests confirmed that there is no difference between the pitting resistances of each specimen, as the structures of the surfaces were identical despite the effect of the differences in the welding heat input for each specimen and the minor dilution effect on the surface.

  6. 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.

  7. New technique for installing screen wicking into Inconel 718 heat pipe

    NASA Astrophysics Data System (ADS)

    Giriunas, Julius A.; Watson, Gordon K.; Tower, Leonard K.

    1993-01-01

    The creep behavior of superalloys, including Inconel 718, in the presence of liquid sodium is not yet known. To study this problem, the NASA Lewis Research Center has initiated a program with the Energy Technology Engineering Center (ETEC) of Rockwell International Corporation to fill with sodium and creep-test three small cylindrical heat pipes of Inconel 718 for a period of 1000 hours each. This report documents the design and the construction methods that were used at NASA Lewis to fabricate these heat pipes. Of particular importance in the heat pipe construction was the installation of the screen wicking by using an expandable mandrel and differential thermal expansion. This installation technique differs from anything known to have been reported in the heat pipe literature and may be of interest to other workers in the heat pipe field.

  8. New technique for installing screen wicking into Inconel 718 heat pipe

    SciTech Connect

    Giriunas, J.A.; Watson, G.K. ); Tower, L.K. )

    1993-01-10

    The creep behavior of superalloys, including Inconel 718, in the presence of liquid sodium is not yet known. To study this problem, the NASA Lewis Research Center has initiated a program with the Energy Technology Engineering Center (ETEC) of Rockwell International Corporation to fill with sodium and creep-test three small cylindrical heat pipes of Inconel 718 for a period of 1000 hours each. This report documents the design and the construction methods that were used at NASA Lewis to fabricate these heat pipes. Of particular importance in the heat pipe construction was the installation of the screen wicking by using an expandable mandrel and differential thermal expansion. This installation technique differs from anything known to have been reported in the heat pipe literature and may be of interest to other workers in the heat pipe field.

  9. 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.

  10. 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.

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

    DOE PAGES

    Kirka, M. M.; Unocic, K. A.; Raghavan, N.; ...

    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

  12. The deformation and fracture characteristics of inconel X-750 at room temperature and elevated temperatures

    NASA Astrophysics Data System (ADS)

    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 °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 °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 °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 °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.

  13. High temperature joint properties with palladium alloys for SUS316L and Inconel 600

    SciTech Connect

    Izui, Hiroshi; Suezawa, Yoshifumi

    1995-12-31

    Newly developed Pd-Ag-Mn system braze alloys were considered for use in brazing stainless steel SUS316L or Ni-based alloy Inconel 600 for engine applications. Palladium braze alloys were selected because of their oxidation resistance, ductility, relatively high melting points, and lower cost than gold-based braze alloys. The reactions and microstructures were studied in experimental brazed joints between these base metals and the braze alloys. Tensile tests of the joints were carried out at room temperature, 473K, 673K, 873K, and 1,073K. The maximum tensile strengths of the joints brazed with 30Pd-60Ag-10Co at room temperature were 445MPa in the SUS316L joints and 456MPa in the Inconel 600 brazed joints. The SUS316L joints brazed with the braze alloys had tensile strengths of 320MPa to 200MPa from 473K to 1,73K. The Inconel 600 joints brazed with the 30Pd-50Ag-10Mn-10Co alloy had tensile strengths of 289MPa to 162MPa from 473K to 1,073K.

  14. 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.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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 a microstructure gradient and associated tensile property gradient common to all EBM Inconel 718 builds, the extent of which is dependent on build geometry and the specifics of a build's processing history. 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) is comprised of a cored dendritic structure that includes 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.

  17. FLiNaK Compatability Studies with Inconel 600 and Silicon Carbide

    DOE PAGES

    Yoder, Jr, Graydon L.; Heatherly, Dennis Wayne; Wilson, Dane F.; ...

    2016-07-26

    A small liquid fluoride salt test apparatus has been constructed and testing conducted to examine the compatibility of SiC, Inconel 600, and a spiral wound gasket material in FLiNaK salt. These tests were conducted to test materials and sealing systems that would be used in a FLiNaK salt test loop. Three months of testing at 700oC was used to assure that these materials and seals would be acceptable operating under expected test loop conditions. The SiC specimens showed little or no change over the test period while the spiral wound gasket material showed no degradation, except for the possibility ofmore » salt seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 m in depth. Analysis indicated that the salt had leached chrome from the Inconel surface as was expected for this material. Because the test loop will have a limited working lifetime, it was concluded that these materials would be satisfactory for loop construction.« less

  18. FLiNaK Compatability Studies with Inconel 600 and Silicon Carbide

    SciTech Connect

    Yoder, Jr, Graydon L.; Heatherly, Dennis Wayne; Wilson, Dane F.; Caja, Mario

    2016-07-26

    A small liquid fluoride salt test apparatus has been constructed and testing conducted to examine the compatibility of SiC, Inconel 600, and a spiral wound gasket material in FLiNaK salt. These tests were conducted to test materials and sealing systems that would be used in a FLiNaK salt test loop. Three months of testing at 700oC was used to assure that these materials and seals would be acceptable operating under expected test loop conditions. The SiC specimens showed little or no change over the test period while the spiral wound gasket material showed no degradation, except for the possibility of salt seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 m in depth. Analysis indicated that the salt had leached chrome from the Inconel surface as was expected for this material. Because the test loop will have a limited working lifetime, it was concluded that these materials would be satisfactory for loop construction.

  19. Experimental Investigation of process parameters influence on machining Inconel 800 in the Electrical Spark Eroding Machine

    NASA Astrophysics Data System (ADS)

    Karunakaran, K.; Chandrasekaran, M.

    2016-11-01

    The Electrical Spark Eroding Machining is an entrenched sophisticated machining process for producing complex geometry with close tolerances in hard materials like super alloy which are extremely difficult-to-machine by using conventional machining processes. It is sometimes offered as a better alternative or sometimes as an only alternative for generating accurate 3D complex shapes of macro, micro and nano-features in such difficult-to-machine materials among other advanced machining processes. The accomplishment of such challenging task by use of Electrical Spark Eroding Machining or Electrical Discharge Machining (EDM) is depending upon selection of apt process parameters. This paper is about analyzing the influencing of parameter in electrical eroding machining for Inconel 800 with electrolytic copper as a tool. The experimental runs were performed with various input conditions to process Inconel 800 nickel based super alloy for analyzing the response of material removal rate, surface roughness and tool wear rate. These are the measures of performance of individual experimental value of parameters such as pulse on time, Pulse off time, peak current. Taguchi full factorial Design by using Minitab release 14 software was employed to meet the manufacture requirements of preparing process parameter selection card for Inconel 800 jobs. The individual parameter's contribution towards surface roughness was observed from 13.68% to 64.66%.

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

    SciTech Connect

    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 includes 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.

  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. 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

  6. 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.

  7. 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.

  8. 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.

  9. Mechanical behavior of post-processed Inconel 718 manufactured through the electron beam melting process

    DOE PAGES

    Kirka, Michael M.; Medina, Frank; Dehoff, Ryan R.; ...

    2016-10-21

    Here, the electron beam melting (EBM) process was used to fabricate Inconel 718. The microstructure and tensile properties were characterized in both the as-fabricated and post-processed state transverse (T-orientation) and longitudinal (L-orientation) to the build direction. Post-processing involved both a hot isostatic pressing (HIP) and solution treatment and aging (STA) to homogenize the microstructure. In the as-fabricated state, EBM Inconel 718 exhibits a spatially dependent microstructure that is a function of build height. Spanning the last few layers is a cored dendritic structure comprised of the products (carbides and Laves phase) predicted under equilibrium solidification conditions. With increasing distance frommore » the build's top surface, the cored dendritic structure becomes increasingly homogeneous with complete dissolution of the secondary dendrite arms. Further, temporal phase kinetics are observed to lead to the dissolution of the strengthening γ"γ" and precipitation of networks of fine δ needles that span the grains. Microstructurally, post-processing resulted in dissolution of the δ networks and homogeneous precipitation of γ'"γ'" throughout the height of the build. In the as-fabricated state, the monotonic tensile behavior exhibits a height sensitivity within the T-orientation at both 20 and 650 °C. Along the L-orientation, the tensile behavior exhibits strength values comparable to the reference wrought material in the fully heat-treated state. After post-processing, the yield strength, ultimate strength, and elongation at failure for the EBM Inconel 718 were observed to have beneficially increased compared to the as-fabricated material. Further, as a result of post-processing the spatial variance of the ultimate yield strength and elongation at failure within the transverse direction decreased by 4 and 3× respectively.« less

  10. Mechanical behavior of post-processed Inconel 718 manufactured through the electron beam melting process

    SciTech Connect

    Kirka, Michael M.; Medina, Frank; Dehoff, Ryan R.; Okello, Alfred O.

    2016-10-21

    Here, the electron beam melting (EBM) process was used to fabricate Inconel 718. The microstructure and tensile properties were characterized in both the as-fabricated and post-processed state transverse (T-orientation) and longitudinal (L-orientation) to the build direction. Post-processing involved both a hot isostatic pressing (HIP) and solution treatment and aging (STA) to homogenize the microstructure. In the as-fabricated state, EBM Inconel 718 exhibits a spatially dependent microstructure that is a function of build height. Spanning the last few layers is a cored dendritic structure comprised of the products (carbides and Laves phase) predicted under equilibrium solidification conditions. With increasing distance from the build's top surface, the cored dendritic structure becomes increasingly homogeneous with complete dissolution of the secondary dendrite arms. Further, temporal phase kinetics are observed to lead to the dissolution of the strengthening γ"γ" and precipitation of networks of fine δ needles that span the grains. Microstructurally, post-processing resulted in dissolution of the δ networks and homogeneous precipitation of γ'"γ'" throughout the height of the build. In the as-fabricated state, the monotonic tensile behavior exhibits a height sensitivity within the T-orientation at both 20 and 650 °C. Along the L-orientation, the tensile behavior exhibits strength values comparable to the reference wrought material in the fully heat-treated state. After post-processing, the yield strength, ultimate strength, and elongation at failure for the EBM Inconel 718 were observed to have beneficially increased compared to the as-fabricated material. Further, as a result of post-processing the spatial variance of the ultimate yield strength and elongation at failure within the transverse direction decreased by 4 and 3× respectively.

  11. 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

  12. Effect of Plasma Nitriding Parameters on the Wear Resistance of Alloy Inconel 718

    NASA Astrophysics Data System (ADS)

    Kovací, Halim; Ghahramanzadeh ASL, Hojjat; Albayrak, Çigdem; Alsaran, Akgün; Çelik, Ayhan

    2016-11-01

    The effect of the temperature and duration of plasma nitriding on the microstructure and friction and wear parameters of Inconel 718 nickel alloy is investigated. The process of plasma nitriding is conducted in a nitrogen-hydrogen gaseous mixture at a temperature of 400, 500 and 600°C for 1 and 4 h. The modulus of elasticity of the nitrided layer, the micro- and nanohardness, the surface roughness, the friction factor and the wear resistance of the alloy are determined prior to and after the nitriding. The optimum nitriding regime providing the best tribological characteristics is determined.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Experimental Investigation into the Effect of Ball End Milling Parameters on Surface Integrity of Inconel 718

    NASA Astrophysics Data System (ADS)

    Bhopale, Nandkumar N.; Joshi, Suhas S.; Pawade, Raju S.

    2015-02-01

    In machining of Inconel 718, various difficulties such as increased tool wear and poor machined surface quality are frequently encountered due to its high temperature strength and poor thermal properties. This work considers the effect of number of passes and the machining environment on the machined surface quality in ball end milling of Inconel 718, which hitherto has not been adequately understood. To this effect, extensive experimentation has been carried out to analyze machined surface quality and integrity in terms of surface roughness, surface damage, and microhardness variation in the machined surfaces. The machined surfaces show formation of distinct bands as a function of instantaneous machining parameters along the periphery of cutting tool edge. A distinct variation is also observed in the measured values of surface roughness and microhardness in these regions. The minimum surface roughness is obtained in the stable cutting zone and it increases toward the periphery of the cutter on band #2 and band #3. Microhardness of depth beneath the machined surface shows that the machining affected zone varies from 60 to 100 µm in ball end milling under various machining conditions.

  3. 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.

  4. Microstructural analysis of ion-irradiation-induced hardening in inconel 718

    NASA Astrophysics Data System (ADS)

    Hashimoto, N.; Hunn, J. D.; Byun, T. S.; Mansur, L. K.

    2003-05-01

    As an assessment for a possible accelerator beam line window material for the US Spallation Neutron Source (SNS) target, performance, radiation-induced hardening and microstructural evolution in Inconel 718 were investigated in both solution annealed (SA) and precipitation hardened (PH) conditions. Irradiations were carried out using 3.5 MeV Fe +, 370 keV He + and 180 keV H + either singly or simultaneously at 200 °C to simulate the damage and He/H production in the SNS target vessel wall. This resulted in systematic hardening in SA Inconel and gradual net softening in the PH material. TEM microstructural analysis showed the hardening was associated with the formation of small loop and faulted loop structures. Helium-irradiated specimens included more loops and cavities than Fe + ion-irradiated specimens. Softening of the PH material was due to dissolution of the γ '/γ ″ precipitates. High doses of helium were implanted in order to study the effect of high retention of gaseous transmutation products. Simultaneous with the hardening and/or softening due to the displacement damage cascade, helium filled cavities produced additional hardening at high concentrations.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Effect of single aging on stress corrosion cracking susceptibility of INCONEL X-750 under PWR conditions

    NASA Astrophysics Data System (ADS)

    Mishra, B.; Moore, J. J.

    1988-05-01

    Unfavorable morphology of precipitates and inclusions has been thought to be the cause of severe intergranular stress corrosion cracking (IGSCC) in double aged INCONEL* X-750 alloy used in reactor water environments. A single step aging treatment of 200 hours at 811 °C followed by furnace cooling after solution treating for 2 hours at 1075 °C has been found to provide an improved combination of strength, ductility, and resistance to SCC under simulated PWR test conditions. In this single aged condition a reprecipitated secondary carbide, together with γ' was produced at the grain boundary which resulted in a mixed fracture mode comprising dimple rupture and microvoid coalescence compared with a predominantly intergranular mode for the fully age hardened specimens. This improvement has been explained in terms of the morphology of the second phase precipitates which are produced in these heat treatment regimes.

  11. Dislocation development and void formation during electron irradiation in inconel X-750 with γ' precipitates

    NASA Astrophysics Data System (ADS)

    Kato, Takahiko; Nakata, Kiyotomo; Takahashi, Heishichiro; Ohnuki, Soumei; Masaoka, Isao; Takeyama, Taro

    1985-08-01

    Swelling behaviour and dislocation development in aged Inconel X-750 containing γ' precipitates during electron irradiation at temperatures of 673 to 823 K were continuously observed with a high voltage electron microscope. In the specimens with large γ', aged above 1073 K for 24 h, the void formation is drastically suppressed at temperatures of 710 to 760 K. The dislocation density in the matrix away from the large γ' is fairly low, although the dislocations tangle around the γ'. In the specimens with fine γ', aged for about 24 h at temperatures below 1023 K, fairly large swelling of 1-1.5% occurs after 20 dpa irradiation at 735 K. The dislocations climb through the fine γ ' and the dislocation density in the matrix increases rapidly with irradiation dose.

  12. Effect of Environment on Fatigue and Creep Crack Growth in Inconel X-750 at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Gabrielli, F.; Pelloux, R. M.

    1982-06-01

    The fatigue crack growth rates (FCGR) of Inconel X-750 were measured in air and in vacuum at 25 °C and 650 °C as a function of test frequency. The wave shape was triangular and the frequency varied from 10 Hz to 0.01 Hz. The creep crack growth rates (CCGR) were also measured on single edge notch specimens at 650 °C in air and in purified argon. For a given AK, the FCGR increases when temperature increases and frequency decreases. At low frequency the FCGR approach the creep crack growth rates. The mode of fracture changes from transgranular at 10 Hz to intergranular at 0.01 Hz. The effect of air environment is to accelerate the transition from transgranular to intergranular fracture modes with decreasing frequency. The role of oxidation in accelerating crack growth rate in fatigue and in creep is discussed in detail.

  13. Preliminary study on pressure brazing and diffusion welding of Nb-1Zr to Inconel 718

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1990-01-01

    Future space power systems may include Nb-1Zr/Inconel 718 dissimilar metal joints for operation at 1000 K for 60,000 h. The serviceability of pressure-brazed and diffusion-welded joints was investigated. Ni-based metallic glass foil filler metals were used for brazing. Ni and Fe foils were used as diffusion welding inter-layers. Joint soundness was determined by metallographic examination in the as-brazed and as-welded condition, after aging at 1000 K, and after thermal cycling. Brazed joints thermally cycled in the as-brazed condition and diffusion-welded joints were unsatisfactory because of cracking problems. Brazed joints may meet the service requirements if the joints are aged at 1000 K prior to thermal cycling.

  14. Elevated Temperature Strength of Fine-Grained INCONEL Alloy MA754

    SciTech Connect

    T.C. Totemeier; T.M. Lillo; J.A. Simpson

    2005-09-01

    Elevated temperature tensile and creep-rupture tests were performed on INCONEL alloy MA754 in an as-rolled, fine-grained condition. Tensile tests were performed at 25, 800, 900, and 1000°C; creep-rupture tests were performed at 800, 900, and 1000°C. The elevated temperature strength in the fine-grained condition was approximately 25% of the standard, coarse-grained annealed condition. While good ductility was observed in tensile tests at a nominal strain rate of 1×10-3 sec-1, ductility in creep-rupture tests was very low, with failure elongations less than 5% and no reduction in area. Creep deformation appeared to occur solely by cavity formation and growth.

  15. 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.

  16. 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.

  17. Microstructural and chemical characterization of the inconel/ti(n) thin film and multilayer system.

    PubMed

    Diehl, P E; Pew, H K; Madsen, D W; Leavitt, J A; Smith, D J

    1995-01-01

    Single layer and multilayer films of titanium and Inconel 600 (76 at.% Ni, 16 at.% Cr, 8 at.% Fe) have been prepared by sputtering in argon/nitrogen atmospheres, with nitrogen partial pressures ranging from 0% to 40%. The microstructure and chemistry of the sputtered films were characterized using transmission/high-resolution electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, electron probe microanalysis, and ion beam analysis with MeV helium beams. The microstructure depended on deposition power and individual layer thickness, as well as the sputtering atmosphere composition. Metal nitrides were formed in single layers of both materials whereas, for multilayers, nitrogen was preferentially incorporated into the titanium layer.

  18. 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.

  19. Inter- and intragranular delta phase quantitative characterization in Inconel 718 by means of image analysis.

    PubMed

    Vanderesse, N; Anderson, M; Bridier, F; Bocher, P

    2015-01-01

    This paper describes an image processing method for discriminating the inter- and intragranular delta phase precipitates in Inconel 718 (IN 718). The successive practical operations and the motivations of their choices are presented in detail. The method was applied to IN 718 specimens heat treated with different parameters to produce microstructures containing various amounts of both types of precipitates. They were characterized by electron microscopy in backscattered electron imaging. The main difficulty arose from the fact that the brightness distributions of inter- and intragranular precipitates partially overlap. Additional information on their morphology and their spatial distribution had to be exploited in order to differentiate them. The shape and the orientation of the precipitates were evaluated using the structure tensor, an operator that quantifies the directionality of the intensity distribution in an image. The distance between parallel precipitates was also used as an additional property to identify clusters of intragranular precipitates.

  20. 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.

  1. 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.

  2. Processing and Characterization of Sub-delta Solvus Forged Hemispherical Forgings of Inconel 718

    NASA Astrophysics Data System (ADS)

    Chenna Krishna, S.; Rao, G. Sudarasana; Singh, Satish Kumar; Narayana Murty, S. V. S.; Venkatanarayana, G.; Jha, Abhay K.; Pant, Bhanu; Venkitakrishnan, P. V.

    2016-12-01

    In this paper, microstructure and mechanical properties of 200 mm diameter Inconel 718 hemispherical domes processed at 1025 °C through closed die hammer forging have been investigated. Microstructure and mechanical properties of the forgings in radial and tangential directions were characterized using optical microscopy, scanning electron microscopy, impact testing, and tensile testing. Grain size of the forgings at three different locations was fine with an average grain size of ASTM No. 8-9. The typical tensile properties of the forgings in solution-treated and aged condition were ultimate tensile strength-1450 MPa, yield strength-1240 MPa, and ductility-25%. The fine grain size achieved in forgings has been attributed to delta phase present at grain boundaries which pinned the grains during forging and prevented grain coarsening.

  3. 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.

  4. Electron Backscatter Diffraction Analysis of Inconel 718 Parts Fabricated by Selective Laser Melting Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoqing; Chou, Kevin

    2016-11-01

    In this study, the crystallographic texture of an Inconel 718 part fabricated by selective laser melting was investigated. The front surface (X-Z plane) microstructure is characterized by the columnar grains growing along the build direction, and the width of columnar grains is in the range of about 75-150 µm, with the bottom layers having narrower grains as a result of a higher cooling rate. In addition to equiaxed grains, the top surface (X-Y plane) has a feature of patch patterns resulting from the laser scanning strategy. Based on the electron backscatter diffraction results, there appears only weak crystallographic texture in both the X-Z plane and the X-Y plane of the part. From the grain boundary map, the microstructures are composed of high-angle boundaries with a larger fraction of subgrain boundaries.

  5. Electron Backscatter Diffraction Analysis of Inconel 718 Parts Fabricated by Selective Laser Melting Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoqing; Chou, Kevin

    2017-02-01

    In this study, the crystallographic texture of an Inconel 718 part fabricated by selective laser melting was investigated. The front surface (X-Z plane) microstructure is characterized by the columnar grains growing along the build direction, and the width of columnar grains is in the range of about 75-150 µm, with the bottom layers having narrower grains as a result of a higher cooling rate. In addition to equiaxed grains, the top surface (X-Y plane) has a feature of patch patterns resulting from the laser scanning strategy. Based on the electron backscatter diffraction results, there appears only weak crystallographic texture in both the X-Z plane and the X-Y plane of the part. From the grain boundary map, the microstructures are composed of high-angle boundaries with a larger fraction of subgrain boundaries.

  6. 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.

  7. 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.

  8. 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.

  9. 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; ...

    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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.; ...

    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

  20. Stress corrosion cracking susceptibility and some electrochemical characteristics of Inconel X-750 in lithiated water at 350°C

    NASA Astrophysics Data System (ADS)

    Sharkawy, S. W.; Xia, Z.; Szklarska-Smialowska, Z.

    1993-03-01

    The stress corrosion cracking (SCC) susceptibility of Inconel X-750 in the as-received (AR) and double aged (DA) conditions was investigated by the slow strain rate test (SSRT) in lithiated hydrogenated water at 350°C. The results showed that the DA condition was more susceptible to SCC than the AR one. Potentiodynamic polarization and AC impedance tests showed that the DA condition was characterized by higher dissolution rate and a lower tendency to passivation than the AR one.

  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. 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.

  3. 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

  4. 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.

  5. Macrotransport-solidification kinetics modeling of equiaxed dendritic growth. Part 2: Computation problems and validation on INCONEL 718 superalloy castings

    SciTech Connect

    Nastac, L.; Stefanescu, D.M.

    1996-12-01

    In Part 1 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 thee 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.

  6. Novel microstructural growth in the surface of Inconel 625 by the addition of SiC under electron beam melting

    NASA Astrophysics Data System (ADS)

    Ahmad, M.; Ali, G.; Ahmed, Ejaz; Haq, M. A.; Akhter, J. I.

    2011-06-01

    Electron beam melting is being used to modify the microstructure of the surfaces of materials due to its ability to cause localized melting and supercooling of the melt. This article presents an experimental study on the surface modification of Ni-based superalloy (Inconel 625) reinforced with SiC ceramic particles under electron beam melting. Scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction techniques have been applied to characterize the resulted microstructure. The results revealed growth of novel structures like wire, rod, tubular, pyramid, bamboo and tweezers type morphologies in the modified surface. In addition to that fibrous like structure was also observed. Formation of thin carbon sheet has been found at the regions of decomposed SiC. Electron beam modified surface of Inconel 625 alloy has been hardened twice as compared to the as-received samples. Surface hardening effect may be attributed to both the formation of the novel structures as well as the introduction of Si and C atom in the lattice of Inconel 625 alloy.

  7. 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.

  8. 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.

  9. 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.

  10. Chemistry of glass-ceramic to metal bonding for header applications: III. Treatment of Inconel 718 to eliminate hot cracking during laser welding

    SciTech Connect

    Moddeman, W.E.; Jones, W.H.; Koeller, T.L.; Craven, S.M.; Kramer, D.P.

    1987-04-24

    A study was conducted to determine the weldability of Inconel 718 shells. Two pieces of Inconel 718 were welded together with a Hastelloy B-2 filler. The Inconel surface condition was varied by heat-treating and by using several different cleaning processes. The surface chemistry following each modification was determined by Auger spectroscopy. Each conditioned Inconel hollow cylinder (shell) was also checked for pulsed laser weldability by looking for hot cracking. Abraded and solvent-cleaned Inconel shells were found to have thin surface oxides and were also found to be weldable. Heat-treated shells were shown to have a thick complex oxide layer consisting primarily of chromium, titanium, aluminum, and niobium, and were not found to be weldable. Variations of an ''oxide removal'' treatment were used and found to be ineffective in removing all of the heat-treated surface oxides. The predominant oxide left after the various removal treatments was a thick aluminum oxide laced with alkali, alkaline earth and nickel oxides, sulfides (or sulfates), and/or chlorides. Inconel shells after being treated by these oxide removal steps and variations were also found not be be laser weldable. This oxide was finally removed by electropolishing, and the resulting surface was found to be crack-free after welding. Auger analysis of fractured surfaces in hot-cracked regions revealed that the surfaces consisted of an oxide similar to that left after the removal steps, but without the aluminum oxide. Thus, it was concluded that hot cracking in heat-treated, oxide-removed Inconel 718 is due to one or all of the following: alkali, alkaline earth and nickel oxides, sulfides (or sulfates), and/or chlorides that accumulate in the cracked area.

  11. Étude du comportement structural de l'alliage NC 19 Fe Nb (Inconel 718)

    NASA Astrophysics Data System (ADS)

    Slama, C.; Cizeron, G.

    1997-03-01

    In the as-received state (following a double treatment at 720 and 620 °C), the structure of INC 718 consists of a γ matrix, intergranular β precipitates and (Nb,Ti)C carbides; moreover, γ{'} and γ{''} phases have precipitated in the matrix. Using different methods, the structural behaviour was analyzed which led to distinguish the temperature ranges in which occurs precipitation or dissolution of β, γ{'} and γ{''} phases on heating and to define the optimum conditions of homogeneization. Furthermore a CCT diagram for INC 718 has been drawn showing the respective precipitation of γ{'}, γ{''} and β phases as a function of the cooling rate applied from 990 °C. L'étude de l'alliage Inconel 718 (NC 19 Fe Nb) a permis de montrer que sa structure, dans l'état de livraison (après double revenu à 720 puis 620 °C), consiste en une matrice γ avec des précipités β intergranulaires et des carbures du type (Nb,Ti) C ; en outre, la matrice contient des précipités des phases γ{''} et γ{'}. L'analyse du comportement structural de l'alliage à l'aide de différentes méthodes physiques a conduit à délimiter les domaines de température dans lesquels interviennent, au chauffage, la précipitation ou la dissolution des phases β, γ{'}, γ{''} et de définir les conditions optimales d'homogénéisation. Le diagramme T.R.C. de l'Inconel 718 a ensuite été tracé : les intervalles de température dans lesquels interviennent les précipitations respectives des phases γ{'}, γ{''} et β en fonction de la vitesse de refroidissement imposée depuis 990 °C, ont ainsi pu être précisés.

  12. 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).

  13. Microstructures, Forming Limit and Failure Analyses of Inconel 718 Sheets for Fabrication of Aerospace Components

    NASA Astrophysics Data System (ADS)

    Sajun Prasad, K.; Panda, Sushanta Kumar; Kar, Sujoy Kumar; Sen, Mainak; Murty, S. V. S. Naryana; Sharma, Sharad Chandra

    2017-02-01

    Recently, aerospace industries have shown increasing interest in forming limits of Inconel 718 sheet metals, which can be utilised in designing tools and selection of process parameters for successful fabrication of components. In the present work, stress-strain response with failure strains was evaluated by uniaxial tensile tests in different orientations, and two-stage work-hardening behavior was observed. In spite of highly preferred texture, tensile properties showed minor variations in different orientations due to the random distribution of nanoprecipitates. The forming limit strains were evaluated by deforming specimens in seven different strain paths using limiting dome height (LDH) test facility. Mostly, the specimens failed without prior indication of localized necking. Thus, fracture forming limit diagram (FFLD) was evaluated, and bending correction was imposed due to the use of sub-size hemispherical punch. The failure strains of FFLD were converted into major-minor stress space (σ-FFLD) and effective plastic strain-stress triaxiality space (ηEPS-FFLD) as failure criteria to avoid the strain path dependence. Moreover, FE model was developed, and the LDH, strain distribution and failure location were predicted successfully using above-mentioned failure criteria with two stages of work hardening. Fractographs were correlated with the fracture behavior and formability of sheet metal.

  14. 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.

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

    SciTech Connect

    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, 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.

  16. 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.

  17. A Comparative Study on the Hot Working Behavior of Inconel 718 and ALLVAC 718 Plus

    NASA Astrophysics Data System (ADS)

    Momeni, Amir; Abbasi, Seyed Mehdi; Morakabati, Maryam; Badri, Hasan

    2017-01-01

    Hot compression tests were performed on Inconel 718 and ALLVAC 718 PLUS (718+) at temperatures and strain rates in ranges of 1223 K to 1373 K (950 °C to 1100 °C) and 0.001-1 s-1, respectively. Discontinuous yield behavior was observed in the flow curves of both alloys. For both alloys, the drop in stress at the yield point (yield drop) was maximized at 0.01 to 1 s-1. The alloy 718+ showed larger yield drop than 718 over the studied deformation conditions. The different yield behaviors were attributed to the various chemical compositions. The peak strain for both alloys increased in temperature range of 1223 K to 1273 K (950 to 1000 °C) and strain rates of 0.01 to 1 s-1. This uncommon behavior was ascribed to the change in the mechanism of microstructural evolution from continuous to discontinuous dynamic recrystallization (DRX). The kinetics of DRX was described by the Avrami equation and the exponent was determined at different deformation conditions. The Avrami exponent increased in the middle values of Zener-Hollomon (Z) parameters, i.e., 29.3 < lnZ < 32.9 for 718 and 31.4 < lnZ < 34.5 for 718+. The unusual variation of the Avrami exponent was attributed to the change in the mechanism of DRX.

  18. Laser Metal Deposition as Repair Technology for a Gas Turbine Burner Made of Inconel 718

    NASA Astrophysics Data System (ADS)

    Petrat, Torsten; Graf, Benjamin; Gumenyuk, Andrey; Rethmeier, Michael

    Maintenance, repair and overhaul of components are of increasing interest for parts of high complexity and expensive manufacturing costs. In this paper a production process for laser metal deposition is presented, and used to repair a gas turbine burner of Inconel 718. Different parameters for defined track geometries were determined to attain a near net shape deposition with consistent build-up rate for changing wall thicknesses over the manufacturing process. Spot diameter, powder feed rate, welding velocity and laser power were changed as main parameters for a different track size. An optimal overlap rate for a constant layer height was used to calculate the best track size for a fitting layer width similar to the part dimension. Deviations in width and height over the whole build-up process were detected and customized build-up strategies for the 3D sequences were designed. The results show the possibility of a near net shape repair by using different track geometries with laser metal deposition.

  19. Elevated temperature irradiation damage in CANDU spacer material Inconel X-750

    NASA Astrophysics Data System (ADS)

    Zhang, He K.; Yao, Zhongwen; Daymond, Mark R.; Kirk, Marquis A.

    2014-02-01

    Heavy ion irradiation induced damage in Inconel X-750 at low temperatures (60-400 °C) has been reported in our previous study. In the current investigation, the microstructure evolution and phase change during heavy (1 MeV Kr2+) irradiation at elevated temperatures (500 °C and 600 °C) were characterized under in situ observation of intermediate voltage electron microscope (IVEM) at Argonne National Laboratory. For each temperature, defect analyses using the weak beam dark field method were carried out at several doses, up to 5.4 dpa. Small defects (<5 nm) yielded from high temperature irradiation comprise mainly stacking fault tetrahedras (SFTs), small ⅓ <1 1 1> and ½ <1 1 0> type dislocation loops. Large interstitial Frank loops were observed and a clear characteristic for growth of loops was video-captured. Unfaulting of interstitial Frank loops was observed. The number density of the defects saturated at a relatively low dose of 0.68 dpa. No obvious change of defect fraction was found with increasing dose, but more complex dislocation structures formed at higher doses. In contrast to low temperature irradiation, the primary strengthening phase γ‧ was found to be stable during irradiation at temperatures >500 °C and was not disordered up to 5.4 dpa. No cavities were observed after the irradiation even at 600 °C.

  20. TEM characterization of in-reactor neutron irradiated CANDU spacer material Inconel X-750

    NASA Astrophysics Data System (ADS)

    Zhang, He Ken; Yao, Zhongwen; Morin, Gregory; Griffiths, Malcolm

    2014-08-01

    The irradiation induced defects in CANDU Inconel X-750 spacers, which were removed from reactors after about 14 effective full power years, were examined by transmission electron microscopy (TEM). The spacers in the form of garter springs were reported to operate at various temperatures depending on locations. Two samples from different locations with different estimated irradiation temperatures were tested: (1) ∼180 °C at 6 o’clock position and (2) ⩾300 °C at 12 o’clock position. Obvious temperature effects were observed. In the ∼180 °C irradiated sample, a high density of small lattice defects (1-3 nm) developed during irradiation, including stacking fault tetrahedra and both 1/3 <1 1 1> and ½ <1 1 0> type dislocation loops. A uniform distribution of small cavities (∼1-3 nm) was observed. In >300 °C irradiated sample, apart from small point defect clusters, large Frank type interstitial loops presented. The sizes of the cavities were also greater than those in the ∼180 °C irradiated sample. The distribution of cavities was more heterogeneous and an obvious agglomeration of cavities to grain boundaries and phase boundaries were observed. In both samples, dissolution of the primary strengthening phase γ‧ was noted.

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

    NASA Astrophysics Data System (ADS)

    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 observed that Inconel X-750 spacers in CANDU reactors exhibits lower ductility with reduced load carrying capacity following irradiation in a reactor environment. The fracture behaviour of ex-service material was also found to be entirely intergranular at high doses. The thermalized flux spectrum in a CANDU reactor leads to 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. Microstructural 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. Helium 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 provide information that is consistent with crack propagation along grain boundaries due to the presence of He bubbles.

  2. Effect of single aging on microstructure and impact property of INCONEL X-750

    NASA Astrophysics Data System (ADS)

    Mishra, B.; Sinha, A. K.; Moore, J. J.

    1985-05-01

    The microstructural changes and grain boundary chemistry of high strength, age hardenable Ni-Cr-Fe alloy, INCONEL * X-750, have been studied using electron and Auger microscopy following a sequence of thermal treatments in the carbide precipitation temperature zone of 704 ‡C to 871 ‡C. The thermal treatment consisted of a solution anneal and quench from 1075 ‡C followed by aging up to 200 hours in this temperature region. An attempt has been made to correlate the microstructural data with Charpy impact test results, hardness values, and modified Huey Corrosion Test results (ASTM G28-72). Aging was conducted in a vacuum and in air from which the specimens were cooled at different rates. Aging at 871 ‡C for 50 to 100 hours under both air and vacuum furnace cooling conditions resulted in increased mechanical strength and corrosion resistance compared with aging at 704 ‡C or 760 ‡C, in which temperature range both apparent fracture toughness and corrosion rate deteriorate. The reprecipitation of secondary carbides along with a possible 17 phase precipitation upon aging at 871 ‡C for 200 hours under vacuum furnace cooling resulted in poor corrosion resistance and inferior impact properties.

  3. 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.

  4. 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.

  5. 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.

  6. Mechanical Characterization of an Additively Manufactured Inconel 718 Theta-Shaped Specimen

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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. 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.

  7. Dissolution kinetics of {delta} phase and its influence on the notch sensitivity of Inconel 718

    SciTech Connect

    Cai Dayong . E-mail: dayongcai@sina.com.cn; Zhang Weihong; Nie Pulin; Liu Wenchang; Yao Mei

    2007-03-15

    The dissolution kinetics of {delta} phase in Inconel 718 at 980 deg. C, 1000 deg. C and 1020 deg. C and its influence on high temperature notch sensitivity have been studied using a quantitative X-ray diffraction (XRD) method and high temperature stress rupture life tests of notched specimens. The amount of {delta} phase decreases gradually during holding time at 980 deg. C, 1000 deg. C and 1020 deg. C. The {delta} phase will be fully dissolved in the austenitic matrix at 1020 deg. C for more than 2 h. A certain amount of {delta} phase still exists after holding at 980 deg. C and 1000 deg. C for times up to 6 h; the amount remaining are 3 wt.% and 0.6 wt.%, respectively. The dissolution rate remains at a high level at the beginning, and then decreases gradually with an increase of holding time. A dynamic equilibrium state can be approached after holding at 980 deg. C for more than 30 min and at 1000 deg. C for more than 2 h. The alloy with {delta} phase amounts higher than 0.62 wt.% does not exhibit notch sensitivity, whereas serious notch sensitivity exists if the concentration is below 0.43 wt.%.

  8. Grain Size Effect on Fracture Behavior of the Axis-Tensile Test of Inconel 718 Sheet

    NASA Astrophysics Data System (ADS)

    Liu, B. B.; Han, J. Q.; Zhao, R.; Liu, W.; Wan, M.

    2016-11-01

    Change in mechanical parts from macro-size to micro-size has become a trend in the metal- and alloy-forming process, with an increasing demand on micro-parts in the last decades. The material mechanical behaviors of micro-size parts are quite different from the conventional ones of macro-size parts due to size effect. It is necessary to further investigate the effects of grain size on material mechanisms in micro-scales, especially fracture behaviors. The fracture behaviors of Inconel 718 sheet with the thickness of 300 μm are studied by uniaxial tensile tests in different grain sizes ranging from 18 to 130 μm. The results show that fracture stress and strain decrease with the increase of grain size. A critical value in the specimen thickness (t) to grain size (d) ratio divides the strength levels into separate stages on the basis of an increase of the inverse of grain size. In addition, the grain size-dependent fracture morphology is changed in the number of dimples and micro-voids decreasing on the fracture surfaces and the sizes of micro-voids changing larger with the increase of grain size.

  9. 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.

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

    PubMed

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

    2016-01-01

    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, 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. In addition, the experimental strain distribution can help validate finite element models which many industries use to predict the residual stress distributions in additive manufactured components.

  11. A Comparative Study on the Hot Working Behavior of Inconel 718 and ALLVAC 718 Plus

    NASA Astrophysics Data System (ADS)

    Momeni, Amir; Abbasi, Seyed Mehdi; Morakabati, Maryam; Badri, Hasan

    2017-03-01

    Hot compression tests were performed on Inconel 718 and ALLVAC 718 PLUS (718+) at temperatures and strain rates in ranges of 1223 K to 1373 K (950 °C to 1100 °C) and 0.001-1 s-1, respectively. Discontinuous yield behavior was observed in the flow curves of both alloys. For both alloys, the drop in stress at the yield point (yield drop) was maximized at 0.01 to 1 s-1. The alloy 718+ showed larger yield drop than 718 over the studied deformation conditions. The different yield behaviors were attributed to the various chemical compositions. The peak strain for both alloys increased in temperature range of 1223 K to 1273 K (950 to 1000 °C) and strain rates of 0.01 to 1 s-1. This uncommon behavior was ascribed to the change in the mechanism of microstructural evolution from continuous to discontinuous dynamic recrystallization (DRX). The kinetics of DRX was described by the Avrami equation and the exponent was determined at different deformation conditions. The Avrami exponent increased in the middle values of Zener-Hollomon ( Z) parameters, i. e., 29.3 < ln Z < 32.9 for 718 and 31.4 < ln Z < 34.5 for 718+. The unusual variation of the Avrami exponent was attributed to the change in the mechanism of DRX.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Effect of Reheat Treatment on Microstructural Refurbishment and Hardness of the As-cast Inconel 738

    NASA Astrophysics Data System (ADS)

    Wongbunyakul, Piyanut; Visuttipitukkul, Patama; Wangyao, Panyawat; Lothongkum, Gobboon; Sricharoenchai, Prasonk

    2014-09-01

    This work investigates the effect of rejuvenation heat treatment conditions for refurbishment of the long-term serviced gas turbine blades, which were made of as-cast nickel base superalloy grade, Inconel 738. The reheat treatment conditions consist of solutionizing treatments at temperatures of 1,438, 1,458 and 1,478 K for 14.4 ks and aging treatments at temperatures of 1,133, 1,148 and 1,163 K for 43.2, 86.4, 129.6 and 172.8 ks. The results show that increase in aging times results in continuous increase of size and area fraction of gamma prime (γ') particles. The higher solutionizing temperature leads to the lower area fraction and smaller size of gamma prime particles. Regarding the microstructure characteristics, the most proper reheat treatment condition should be solutionizing at temperature of 1,438 K for 14.4 ks and aging at temperature of 1,133 K for 172.8 ks, which provides the highest area fraction of gamma prime particles in proper size.

  18. High productivity machining of holes in Inconel 718 with SiAlON tools

    NASA Astrophysics Data System (ADS)

    Agirreurreta, Aitor Arruti; Pelegay, Jose Angel; Arrazola, Pedro Jose; Ørskov, Klaus Bonde

    2016-10-01

    Inconel 718 is often employed in aerospace engines and power generation turbines. Numerous researches have proven the enhanced productivity when turning with ceramic tools compared to carbide ones, however there is considerably less information with regard to milling. Moreover, no knowledge has been published about machining holes with this type of tools. Additional research on different machining techniques, like for instance circular ramping, is critical to expand the productivity improvements that ceramics can offer. In this a 3D model of the machining and a number of experiments with SiAlON round inserts have been carried out in order to evaluate the effect of the cutting speed and pitch on the tool wear and chip generation. The results of this analysis show that three different types of chips are generated and also that there are three potential wear zones. Top slice wear is identified as the most critical wear type followed by the notch wear as a secondary wear mechanism. Flank wear and adhesion are also found in most of the tests.

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

    DOE PAGES

    Cakmak, Ercan; Watkins, Thomas R.; Bunn, Jeffrey R.; ...

    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

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

    DOE PAGES

    Tremsin, Anton S.; Gao, Yan; Dial, Laura C.; ...

    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

  1. 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.

  2. Laser surface annealing technique of aged Inconel 718 by laser beam irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Liufa; Hirose, Akio; Kobayashi, Kojiro F.

    2003-03-01

    Laser was employed to anneal a thin surface layer of aged Inconel 718 by dissolving the strengthening phase, γ". The HE (Hydrogen Embrittlement) resistance of the alloy was improved via such laser surface annealing (LSA) processes. To establish a general LSA technique for engineer applications, experimental LSA processes were conducted to study the effects of the laser process parameters on the formation of the annealed surface layers, and applicable process parameter ranges were obtained. Next, a numerical method was developed for predicting the formation of the laser annealed surface layers in the following steps. Because only the γ" phase was dissolved in the LSA process, the dissolution kinetics of this phase was studied via thermal cycling experiments, and it was proved to follow an Avrami equation. FEM (Finite Element Method) simulations were conducted to calculate the thermal distribution in each laser annealed surface layer, and thermal history data were extracted every certain depth. The volume fractions of the γ" phase at these depths were calculated using these thermal history data based on the deduced Avrami equation. Using a developed relationship between the hardness variation of the alloy and the volume fraction variation of the γ" phase, the hardness distribution in the annealed surface layer and this layer's thickness were calculated. The predicted applicable laser process parameter ranges were obtained. These calculated results were compared with their corresponding experimental results. The good agreements between the calculated and measured results suggested that this numerical prediction approach is feasible for engineer applications.

  3. The Effect of δ Phase on the Mechanical Properties of an Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Valle, L. C. M.; Araújo, L. S.; Gabriel, S. B.; Dille, J.; de Almeida, L. H.

    2013-05-01

    The relationship between the δ phase content and the mechanical properties of Inconel 718 superalloy is still uncertain in the scientific literature. This study investigated the effects of the amount of δ phase and of the grain size on the mechanical properties of an aged γ-matrix with γ' and γ″ precipitates. The material in as-received condition in the form of a forged bar was solution-treated in different conditions and aged according to UNS7718 standard. The microstructures were characterized using optical, scanning, and transmission electron microscopy. Hardness and tensile tests were also conducted. After solution treatment, γ' and γ″ phases are dissolved and δ phase volume fraction is reduced to a minimum amount only observed by TEM, resulting in an increase of the grain size and a decrease of hardness and strength. After aging, the precipitation of γ' and γ″ occurs and the amount of δ phase increases. The volume fraction of δ phase varying from 0.30 to 1.38% and the grain size varying from ASTM 7 to 5 do not have a significant effect on the tensile properties and hardness.

  4. 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.

  5. Effect of sulfur and magnesium on hot ductility and pitting corrosion for Inconel 690 alloy

    SciTech Connect

    Liu, K.; Zhang, B.; Zhang, S.; Zhu, Z.

    1995-12-31

    A series of hot tensile tests has been performed to study the effect of sulfur and magnesium on hot ductility of Inconel 690 alloy. The hot ductility has been evaluated from the reduction of area in hot tensile tests using a Gleeble testing machine. The value of reduction in area decreased with increasing sulfur content in the temperature range from 900 C to 1,200 C. When sulfur content was larger than 0.0025%, a ductility dip appeared, and the greater the sulfur content, the deeper and wider the ductility dip. The Scanning Electron Microscope (SEM) analyses showed that the fracture appearances changed gradually from transgranular to intergranular with increasing sulfur content, meanwhile sulfur and titanium segregation were observed at grain boundaries. The ductility dip of 690 alloy with relatively higher sulfur content could be inhibited by adding appropriate amount of magnesium. However, excessive addition led to magnesium precipitation, which was detrimental to hot ductility. The pitting test has also been conducted and the results showed that pitting rate obviously increased with increasing sulfur content.

  6. Microstructural characterization and some mechanical properties of gas-borided Inconel 600-alloy

    NASA Astrophysics Data System (ADS)

    Makuch, N.; Kulka, M.

    2014-09-01

    The excellent resistance of Ni-based alloys to corrosion and oxidation is well-known. Boriding can be applied to these alloys in order to obtain suitable wear protection. In this paper, two-stage gas boronizing in N2-H2-BCl3 atmosphere is proposed for the producing the boride layer on Inconel®600-alloy. This process consists in two stages alternately repeated: saturation by boron and diffusion annealing. Such a gas boriding is applied in order to accelerate the saturation by boron and its diffusion. It turns out to be more effective because of eliminating the excess of boron, diffusing into the substrate, during the second stage. Microstructure and some mechanical properties of the produced layer are presented. Microstructural characterization is studied with using an optical microscope, scanning electron microscope, energy-dispersive x-ray microanalysis and x-ray diffraction. The diffusion zone consists of the mixture of nickel and chromium borides, occurring in the compact boride zone and in the area located beneath, at grain boundaries. The improved hardness and wear resistance characterize the layer. The formed boride layer is significantly thicker than those-obtained by the pack-boronizing or paste process at comparable temperature and time. Simultaneously, the measured depth of layer is slightly smaller than that-reported for electrolytic boriding.

  7. A ROTATING INCONEL BAND TARGET FOR PION PRODUCTION AT A NEUTRINO FACTORY, USING STUDY II PARAMETERS.

    SciTech Connect

    KING,B.J.; SIMOS,N.P.; WEGGEL,R.V.; MOKHOV,N.V.

    2001-05-04

    A conceptual design is presented for a high power pion production target, based on a rotating band of inconel alloy 718, that is intended to provide a back-up targetry option for the Neutrino Factory Study II. The target band has a 2.5 m radius and has an I-beam cross section that is 6 cm high and with a 0.6 cm thick webbing. The pion capture scenario and proton beam parameters are as specified for the Study II base-line targetry option, i.e. capture into a 20 Tesla tapered solenoidal channel with proton beam fills at 2.5 Hz containing 6 short bunches, each spaced by 20 milliseconds, of 1.67 x 10{sup 13} 24 GeV protons. The target is continuously rotated at 1 m/s to Carey heat away from the production region and through a water cooling tank. The mechanical layout and cooling setup are described and results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target and from ANSYS finite element calculations for the corresponding shock heating stresses.

  8. 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.

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

    PubMed Central

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

    2016-01-01

    Abstract 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, 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. In addition, the experimental strain distribution can help validate finite element models which many industries use to predict the residual stress distributions in additive manufactured components. PMID:27877885

  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. Infrared Brazing of Ti50Ni50 Shape Memory Alloy and Inconel 600 Alloy with Two Ag-Cu-Ti Active Braze Alloys

    NASA Astrophysics Data System (ADS)

    Shiue, Ren-Kae; Wu, Shyi-Kaan; Yang, Sheng-Hao

    2017-02-01

    Infrared brazing of Ti50Ni50 SMA and Inconel 600 alloy using Cusil-ABA and Ticusil filler metals has been investigated. The joints were dominated by Ag-Cu eutectic with proeutectic Cu in the Cusil-ABA brazed joint and with proeutectic Ag in the Ticusil one. A continuous curved belt composed of a Ni3Ti layer and a (Cu x Ni1- x )2Ti layer formed in the brazed Ti50Ni50/Ticusil/Inconel 600 joint. On the Ti50Ni50 SMA side, an intermetallic layer of (Cu x Ni1- x )2Ti formed in all joints, with x values around 0.81 and 0.47. Layers of (Cu x Ni1- x )2Ti, Ni3Ti, and mixed Ni3Ti and Ni2Cr intermetallics were observed next to the Inconel 600 substrate in the brazed Ti50Ni50/Cusil-ABA/Inconel 600 joint. The maximum shear strengths of the joints using the Cusil-ABA filler metal and the Ticusil filler metal were 324 and 300 MPa, respectively. In the Cusil-ABA brazed joint, cracks with cleavage-dominated fracture propagated along the (Cu x Ni1- x )2Ti interfacial layer next to the Ti50Ni50 SMA substrate. In the Ticusil brazed joint, ductile dimple fracture occurred in the Ag-rich matrix near the Inconel 600 alloy substrate. The absence of a detrimental Ti-Fe-(Cu) layer on the Inconel 600 substrate side can effectively improve the shear strength of the joint.

  13. 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.

  14. 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.

  15. Relationship of mechanical characteristics and microstructural features to the time-dependent edge notch sensitivity of inconel 718 sheet

    NASA Technical Reports Server (NTRS)

    Wilson, D. J.

    1971-01-01

    Time-dependent notch sensitivity of Inconel 718 sheet was observed at 900 F to 1200 F (482 - 649 C). It occurred when edge-notched specimens were loaded below the yield strength and smooth specimen tests showed that small amounts of creep consumed large rupture life fractions. The severity of the notch sensitivity was reduced by decreasing the solution temperature, increasing the time and/or temperature of aging and increasing the test temperature to 1400 F (760 C). Elimination of time-dependent notch sensitivity correlated with a change in dislocation motion mechanism from shearing to by-passing precipitate particles.

  16. 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

  17. 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.

  18. Inconel crucibles - an alternative to quartz glass crucibles when analysing problematic samples by EA-IRMS

    NASA Astrophysics Data System (ADS)

    Meier-Augenstein, Wolfram; Kemp, Helen; Neal, Ken

    2013-04-01

    Anecdotal evidence as well as observations made in our own stable isotope laboratory suggest for samples with either a high halogen content (such as marine samples) or a high carbon and oxygen content (such as carbohydrates) to result in flash combustion temperatures exceeding temperature or burn time or both of flash combustion under typical conditions. Whatever the exact circumstances during combustion of such samples, they weaken the wall of the quartz glass reactors in the combustion zone and ultimately lead to pin-prick holes being formed through which carrier gas escapes thus resulting in a dramatic loss of carrier gas flow. Occasionally these pin-prick holes get plugged or "sealed" by molten tin thus restoring carrier gas flow but at the other end of the spectrum these pin-prick holes can become so wide for molten tin being able to pass through and to run down the outside of the reactor tube. In the latter event, a catastrophic failure of the reactor tube is inevitable with carrier gas flow downstream of the holes dropping to almost zero. While pin-prick holes (going unnoticed during an autosampler run of a large batch of samples) typically result in the loss of 3 or 4 samples until the hole/s "self-sealed" with molten tin, in a worst case scenario a catastrophic failure of the reactor tube can result in the loss of 40 or more samples (depending on number of samples in a batch run and when the failure occurred). Here we present examples of combustion reactor failure as well as observations made with crucibles made of quartz glass, stainless steel or inconel alloy during experiments to see if crucible design can mitigate against the effects of problematic samples.

  19. Mechanical Properties Anisotropy of Isothermally Forged and Precipitation Hardened Inconel 718 Disk

    NASA Astrophysics Data System (ADS)

    Khaja, Shaik; Mehta, K. K.; Veera Babu, R.; Sri Rama Devi, R.; Singh, A. K.

    2015-03-01

    The present work describes the tensile and cyclic flow behavior of the as-received disk of Inconel 718 in solution treated and precipitation hardened condition at different locations and orientations. The disk shows moderately high values of anisotropy index indicating significant difference in uniform true strain along radial and tangential orientations. The tensile true stress-plastic strain curves exhibit two slopes defined by Ludwigson relation []. The low-strain regime during tensile test is associated with low-strain localization between broad annealing twins and slips, while high-strain regime is related to the presence of large volume fraction of deformation twins and high-strain localization between narrow deformation twins. It appears that both the γ' and γ″ play a critical role during low deformation regime while the role of γ″ precipitates becomes significant in high-strain regime. The stabilized cyclic true stress-plastic strain curves follow Ludwik relationship ( σ = Kɛ n ) similar to that of high-strain regime of two-slope tensile curves. The true stress-strain curves show softening during cyclic test in comparison to that of monotonic condition and are independent of sample orientations and locations. The lower degree of cyclic softening associated with radial-oriented sample can be attributed to the alignment of δ-phase precipitates normal to the loading direction. The low ductility and low work-hardening exponent of radial-oriented sample in web region have been explained based on the dislocation storage capacity and dynamic recovery coefficient using Kock-Mecking-Estrin analysis.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. (Al, Ti) Gamma Prime Precipitates in a Nickel-Based Superalloy Inconel X-750 Under Heavy Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, He K.; Yao, Zhongwen; Kirk, Marquis A.; Daymond, Mark R.

    2014-07-01

    Phase stability of Ni3(Al, Ti) precipitates in Inconel X-750 under cascade damage was studied using heavy ion irradiation with transmission electron microscope (TEM) in situ observations. From 333 K to 673 K (60 °C to 400 °C), ordered Ni3(Al, Ti) precipitates became completely disordered at low irradiation dose of 0.06 displacement per atom (dpa). At higher dose, a trend of precipitate dissolution occurring under disordered state was observed, which is due to the ballistic mixing effect by irradiation. However, at temperatures greater than 773 K (500 °C), the precipitates stayed ordered up to 5.4 dpa, supporting the view that irradiation-induced disordering/dissolution and thermal recovery reach a balance between 673 K and 773 K (400 °C and 500 °C). Effects of Ti/Al ratio and irradiation dose rate are also discussed.

  10. 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.; ...

    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

  11. 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.

  12. Heat transfer coefficient distribution over the inconel plate cooled from high temperature by the array of water jets

    NASA Astrophysics Data System (ADS)

    Malinowski, Z.; Telejko, T.; Cebo-Rudnicka, A.; Szajding, A.; Rywotycki, M.; Hadała, B.

    2016-09-01

    The industrial rolling mills are equipped with systems for controlled water cooling of hot steel products. A cooling rate affects the final mechanical properties of steel which are strongly dependent on microstructure evolution processes. In case of water jets cooling the heat transfer boundary condition can be defined by the heat transfer coefficient. In the present study one and three dimensional heat conduction models have been employed in the inverse solution to heat transfer coefficient. The inconel plate has been heated to about 900oC and then cooled by one, two and six water jets. The plate temperature has been measured by 30 thermocouples. The heat transfer coefficient distributions at plate surface have been determined in time of cooling.

  13. 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.

  14. Comparison of different sample preparation techniques in TEM observation of microstructure of INCONEL alloy 783 subjected to prolonged isothermal exposure.

    PubMed

    Ma, Longzhou

    2004-01-01

    INCONEL alloy 783 was annealed and aged following the standard heat treatment procedure. One set of specimens was then isothermally exposed at 500 degrees C for 3000 h. Mechanical properties were measured at room temperature and 650 degrees C, and the results showed the prolonged exposure increased the strength and decreased elongation of alloy 783. The microstructures of as-produced and exposed material were examined using optical microscope, SEM and TEM, respectively. Three techniques, jet electro-polishing, ion milling, and focused ion beam, were employed to prepare the TEM samples to observe the variation of microstructure of alloy 783 due to isothermal exposure. TEM images of samples prepared by different methods were analyzed and compared. The results indicate that the jet electro-polishing technique allows the detail microstructure of alloy 783 subjected to different treatments to be well revealed, and thereby the TEM images can be used to explain the enhancement of strength of alloy 783 caused by isothermal exposure.

  15. Comparison of Residual Stresses in Inconel 718 Simple Parts Made by Electron Beam Melting and Direct Laser Metal Sintering

    NASA Astrophysics Data System (ADS)

    Sochalski-Kolbus, L. M.; Payzant, E. A.; Cornwell, P. A.; Watkins, T. R.; Babu, S. S.; Dehoff, R. R.; Lorenz, M.; Ovchinnikova, O.; Duty, C.

    2015-03-01

    Residual stress profiles were mapped using neutron diffraction in two simple prism builds of Inconel 718: one fabricated with electron beam melting (EBM) and the other with direct laser metal sintering. Spatially indexed stress-free cubes were obtained by electrical discharge machining (EDM) equivalent prisms of similar shape. The (311) interplanar spacings from the EDM sectioned sample were compared to the interplanar spacings calculated to fulfill stress and moment balance. We have shown that applying stress 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. In addition, our work has shown that residual stresses in electron beam melted parts are much smaller than that of direct laser metal sintered parts most likely due to the powder preheating step in the EBM process.

  16. 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.

  17. Influence of temperature, environment, and thermal aging on the continuous cycle fatigue behavior of Hastelloy X and Inconel 617

    SciTech Connect

    Strizak, J.P.; Brinkman, C.R.; Booker, M.K.; Rittenhouse, P.L.

    1982-04-01

    Results are presented for strain-controlled fatigue and tensile tests for two nickel-base, solution-hardened reference structural alloys for use in several High-Temperature Gas-Cooled Reactor (HTGR) concepts. These alloys, Hastelloy X and Inconel 617, were tested from room temperature to 871/sup 0/C in air and impure helium. Materials were tested in both the solution-annealed and the preaged conditios, in which aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are given between the strain-controlled fatigue lives of these and several other commonly used alloys, all tested at 538/sup 0/C. An analysis is also presented of the continuous cycle fatigue data obtained from room temperature to 427/sup 0/C for Hastelloy G, Hastelloy X, Hastelloy C-276, and Hastelloy C-4, an effort undertaken in support of ASME code development.

  18. 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.

  19. Effects of the aging temperature and stress relaxation conditions on γ‧ precipitation in Inconel X-750

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    Inconel X-750 is a Ni-based precipitation-hardened superalloy typically used in springs designed for high-temperature applications such as the hold-down springs in nuclear power plants. γ‧ is a major precipitate in X-750 alloys which affects the strength, creep resistance, and stress relaxation properties of the spring. In this study, a solution-treated X-750 wire coiled into a spring was used that was aged at various temperatures and submitted to stress relaxation tests with and without loading. Small angle neutron scattering was employed to quantify the size and volume fraction of γ‧ phase in the springs as a function of the aging temperature and the application of a load during stress relaxation. The volume fraction of γ‧ precipitates increased in the specimen aged at 732 °C following stress relaxation at 500 °C for 300 h. However, the mean size of the precipitates in the samples was not affected by stress relaxation. The specimen aged at the lower temperature (620 °C) contained a smaller γ‧ volume fraction and gained a smaller fraction of γ‧ during stress relaxation compared with the sample aged at the higher temperature (732 °C). The smaller increase in the γ‧ volume fraction for the sample aged at 620 °C was associated with a larger increase in the M23C6 secondary carbide content during relaxation. The Cr depletion zone around the secondary carbides raises the solubility of γ‧ thereby decreasing the volume fraction of γ‧ precipitates in Inconel X-750. In terms of stress relaxation, a larger increase in the γ‧ volume fraction was measured with loading rather than without. This is probably associated with the dislocation accumulation generated under loading that facilitate the nucleation and growth of heterogeneous γ‧ phase due to enhanced diffusion.

  20. 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.

  1. 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

  2. J-resistance curves for Inconel 690 and Incoloy 800 nuclear steam generators tubes at room temperature and at 300 °C

    NASA Astrophysics Data System (ADS)

    Bergant, Marcos A.; Yawny, Alejandro A.; Perez Ipiña, Juan E.

    2017-04-01

    The structural integrity of steam generator tubes is a relevant issue concerning nuclear plant safety. In the present work, J-resistance curves of Inconel 690 and Incoloy 800 nuclear steam generator tubes with circumferential and longitudinal through wall cracks were obtained at room temperature and 300 °C using recently developed non-standard specimens' geometries. It was found that Incoloy 800 tubes exhibited higher J-resistance curves than Inconel 690 for both crack orientations. For both materials, circumferential cracks resulted into higher fracture resistance than longitudinal cracks, indicating a certain degree of texture anisotropy introduced by the tube fabrication process. From a practical point of view, temperature effects have found to be negligible in all cases. The results obtained in the present work provide a general framework for further application to structural integrity assessments of cracked tubes in a variety of nuclear steam generator designs.

  3. Determination of ultrasonic wave velocities and phase velocity dispersion curves of an Inconel 600 plate using resonant ultrasound spectroscopy and leaky Lamb waves.

    PubMed

    Kim, Young H; Song, Sung-Jin; Kwon, Sung-Duk; Cheong, Yong-Moo; Jung, Hyun-Kyu

    2004-04-01

    A plate of Inconel 600 was interrogated using the resonant ultrasound spectroscopy (RUS) and the reflected leaky Lamb waves (LLW). It was found that the plate used in the present work has anisotropy in its material properties by the RUS. The longitudinal and the transverse wave velocities of the Inconel 600 plate were determined by the RUS, ultrasonic pulse-echo method and cut-off frequencies of the LLWs. The wave velocities in the direction of thickness determined by the RUS under the assumption of the orthotropic symmetry were quite similar to those obtained by other methods, the pulse-echo method and from cut-off frequencies. The reflected LLW from the plate was measured with varying the incident angle. The dispersion curves obtained from the reflected LLWs show good agreement with the theoretical calculation in general. The mismatches may be caused by anisotropy of the plate.

  4. 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.

  5. 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.

  6. 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.

  7. Characterization and Evaluation of Cyclic Hot Corrosion Resistance of Detonation-Gun Sprayed Ni-5Al Coatings on Inconel-718

    NASA Astrophysics Data System (ADS)

    Saladi, Sekar; Menghani, Jyoti V.; Prakash, Satya

    2015-06-01

    The high temperature hot corrosion behavior of bare and detonation-gun-sprayed Ni-5Al coatings on Ni-based superalloy Inconel-718 is comparatively discussed in the present study. Hot corrosion studies were carried out at 900 °C for 100 cycles in Na2SO4-60% V2O5 molten salt environment under cyclic heating and cooling conditions. The thermo-gravimetric technique was used to establish the kinetics of hot corrosion. X-ray diffraction, SEM/EDAX, and X-ray mapping techniques were used to analyze the hot corrosion products of bare and coated superalloys. The results indicate that Ni-5Al-coated superalloy showed very good hot corrosion resistance. The overall weight gain and parabolic rate constant of Ni-5Al-coated superalloy were less in comparison with the bare superalloy. The D-gun-sprayed Ni-5Al coating was found to be uniform, adherent, and dense in hot corrosion environment. The formation of nickel- and aluminum-rich oxide scale might have contributed for the better hot corrosion resistance of the coated superalloy.

  8. 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).

  9. 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.

  10. 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.

  11. Effect of Orientation on the Tensile and Creep Properties of Coarse-Grained INCONEL Alloy MA754

    SciTech Connect

    Terry C. Totemeier; Thomas M. Lillo

    2005-03-01

    Elevated temperature tensile and creep-rupture tests were performed on INCONEL MA754 in longitudinal and transverse orientations at temperatures from 700 to 1000°C. The transverse orientation was weaker and less ductile than the longitudinal orientation due to a higher grain boundary density perpendicular to the applied stress axis. This effect was especially pronounced in creep tests at 900 and 1000°C. Threshold creep behavior was observed for the longitudinal orientation, with stress exponents ranging from 29 to 40. Stress exponents in the long transverse orientation ranged from 24 at 800°C to 5 at 1000°C, indicating a temperature-varying deformation mechanism. Creep ductility in the transverse orientation was extremely low, less than 1 pct for higher temperature, lower stress conditions. Failure in all transverse specimens was controlled by grain boundary separation. Even in the relatively weak transverse direction, the strength of MA754 compares favorably with other alloys being considered for advanced power plant applications.

  12. Microstructure and strain-stress analysis of the dynamic strain aging in inconel 625 at high temperature

    NASA Astrophysics Data System (ADS)

    Maj, P.; Zdunek, J.; Mizera, J.; Kurzydlowski, K. J.; Sakowicz, B.; Kaminski, M.

    2017-01-01

    Serrated flow is a result of unstable plastic flow, which occurs during tensile and compression tests on some dilute alloys. This phenomenon is referred as the Portevin Le-Chatelier effect (PLC effect). The aim of this research was to investigate and analyze this phenomenon in Inconel 625 solution strengthened superalloy. The tested material was subjected to tensile tests carried out within the temperature range 200-700 °C, with three different strain rates: 0.002 1/s, 0.01/s, and 0.05 1/s and additional compression tests with high deformation speeds of 0.1, 1, and 10 1/s. The tensile strain curves were analyzed in terms of intensity and the observed patterns of serrations Using a modified stress drop method proposed by the authors, the activation energy was calculated with the assumption that the stress drops' distribution is a direct representation of an average solute atom's interaction with dislocations. Subsequently, two models, the standard vacancy diffusion Bilby-Cottrell model and the realistic cross-core diffusion mechanism proposed by Zhang and Curtin, were compared. The results obtained show that the second one agrees with the experimental data. Additional microstructure analysis was performed to identify microstructure elements that may be responsible for the PLC effect. Based on the results, the relationship between the intensity of the phenomenon and the conditions of the tests were determined.

  13. 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.

  14. The wear of the carbide cutting tools coated with TiN during the milling of Inconel 738

    NASA Astrophysics Data System (ADS)

    Sebhi, A.; Douib, N.

    2017-02-01

    The machining of superalloy parts still an area not very clear in mechanical manufacturing. It is found to be used in particular areas such as gas turbine, rocket engine, space ships, nuclear reactors, and pumps. The machining of Inconel 738 superalloy has been studied in this context, with the aim to understand the wear behavior with carbide inserts coated with TiN and in order to optimize the cutting parameters before starting the production. The wear behavior of the inserts during the machining process of a very tough austenitic superalloy is unclear, and requires a series of well determined tests. The life of the insert under high stress such as pressure, cutting speed, high temperature, in a hostile zone and in contact with a very tough and harder material is determined. The generated process of wear is very complex, because it is followed by physico-chemical phenomenon appearing on the contact surfaces between the active part of the tool and workpiece.The lifetime of machine tools often depends on the tribological characteristics of the material couples (cutting tool / material to be machined). It has been shown that the most influential parameter is the coating, then comes the sliding speed. A relationship between the wear VB and the roughness Ra is proposed to collect information on the cutting edge and the quality of the tool by measuring the roughness. For wear measurement, an indirect method is used in coupling a Touptek photonics camera to capture and Ttoupview analysis software.

  15. 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'.

  16. Feasibility of in situ controlled heat treatment (ISHT) of Inconel 718 during electron beam melting additive manufacturing

    DOE PAGES

    Sames, William J.; Unocic, Kinga A.; Helmreich, Grant W.; ...

    2016-10-07

    A novel technique was developed to control the microstructure evolution in Alloy 718 processed using Electron Beam Melting (EBM). In situ solution treatment and aging of Alloy 718 was performed by heating the top surface of the build after build completion scanning an electron beam to act as a planar heat source during the cool down process. Results demonstrate that the measured hardness (478 ± 7 HV) of the material processed using in situ heat treatment similar to that of peak-aged Inconel 718. Large solidification grains and cracks formed, which are identified as the likely mechanism leading to failure ofmore » tensile tests of the in situ heat treatment material under loading. Despite poor tensile performance, the technique proposed was shown to successively age Alloy 718 (increase precipitate size and hardness) without removing the sample from the process chamber, which can reduce the number of process steps in producing a part. Lastly, tighter controls on processing temperature during layer melting to lower process temperature and selective heating during in situ heat treatment to reduce over-sintering are proposed as methods for improving the process.« less

  17. Feasibility of in situ controlled heat treatment (ISHT) of Inconel 718 during electron beam melting additive manufacturing

    SciTech Connect

    Sames, William J.; Unocic, Kinga A.; Helmreich, Grant W.; Kirka, Michael M.; Medina, Frank; Dehoff, Ryan R.; Babu, Sudarsanam Suresh

    2016-10-07

    A novel technique was developed to control the microstructure evolution in Alloy 718 processed using Electron Beam Melting (EBM). In situ solution treatment and aging of Alloy 718 was performed by heating the top surface of the build after build completion scanning an electron beam to act as a planar heat source during the cool down process. Results demonstrate that the measured hardness (478 ± 7 HV) of the material processed using in situ heat treatment similar to that of peak-aged Inconel 718. Large solidification grains and cracks formed, which are identified as the likely mechanism leading to failure of tensile tests of the in situ heat treatment material under loading. Despite poor tensile performance, the technique proposed was shown to successively age Alloy 718 (increase precipitate size and hardness) without removing the sample from the process chamber, which can reduce the number of process steps in producing a part. Lastly, tighter controls on processing temperature during layer melting to lower process temperature and selective heating during in situ heat treatment to reduce over-sintering are proposed as methods for improving the process.

  18. 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.

  19. Time-dependent edge notch sensitivity of Inconel 718 sheet in the temperature range 900 to 1400 F (482 to 760 C)

    NASA Technical Reports Server (NTRS)

    Wilson, D. J.

    1972-01-01

    Time-dependent notch sensitivity of Inconel 718 sheet occurred at 900 to 1200 F when notched specimens were loaded below the yield strength, and tests on smooth specimens showed that small amounts of creep consumed large fractions of creep-rupture life. The severity of the notch sensitivity decreased with decreasing solution treatment temperature and increasing time and/or temperature of the aging treatment. Elimination of the notch sensitivity was correlated with a change in the dislocation mechanism from shearing to by-passing precipitate particles.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  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. Investigation into the Impact of Hold Time, Thermal Mechanical Fatigue, Shotpeen, and Retardation on Fatigue Crack Growth in Inconel Dovetail Slots in Jet Engines

    NASA Astrophysics Data System (ADS)

    Joiner, Josiah W.

    2011-12-01

    Current jet engine industry studies are ongoing to develop a generic Inconel dovetail slot test case that will be used for calibrating a manufacturing-induced surface damage anomaly distribution curve for future probabilistic life assessments. The stress and temperature profile during the mission have been defined. This analysis will consist of a design of experiments on the Inconel dovetail slot test data. The test case includes thermal and mechanical stresses, as well as variations in hold time, stress and temperature regimes. Several DOEs will be created and run to help assess the impact of four crack growth mechanisms on the damage tolerance life for the different mission profiles: hold time, thermal mechanical fatigue, shotpeen, and retardation. For the sake of this study a parametric study is considered to be a DOE. Calculations will be completed for both surface and corner cracks. For surface cracks, a 2:1 aspect ratio semicircular initial flaw size of 15 x 30 mils will be used. For corner cracks, a 1:1 aspect ratio semicircular initial flaw size of 15 x 15 mils will be used. The calculations will be completed using a proprietary crack propagation code. The results of this study will reveal the mission profile at which each of the aforementioned effects begins to have a significant impact on the damage tolerance life. These studies are critical to ensuring the final test case adequately addresses each of these critical crack propagation drivers.

  7. 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.

  8. Microstructure-Based Strength Distribution Across the Welds of Nickel-Based Superalloy Inconel 751 and Austenite Steel 21-4N Joined by Inertia Friction Welding

    NASA Astrophysics Data System (ADS)

    Zhu, Yuanzhi; Guo, Yingying; Yang, Libin

    2013-04-01

    Welding dissimilar metals is always a challenge for their different physical property and microstructures. In this study, the two dissimilar metals 21-4N and Inconel 751 are welded together by inertia friction welding. Microstructure observation shows that the weld can be divided into three regions in 21-4N: the chemical composition mixture zone, shear zone, and base metal. The width of the chemical composition mixture zone (CMZ) is about 80 μm, with relatively larger grains and lower dislocation density distributed in this zone. Shear banding occurs in the shear zone, and carbides are found to have precipitated strongly along these shear bands noncontinuously. The base metal contains an austenite microstructure with carbides distributed in the matrix. In Inconel 751, only two typical zones can be observed: the CMZ and the base metal. The heat-affected zone is too small to be observed in the whole weld. Finally, a strength model based on microstructural evolution is proposed. The strength distribution along the axial direction of the welds is calculated. The results are in good agreement with the measurements.

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. A Study on the Cyclic Oxidation Behavior of Detonation-Gun-Sprayed Ni-5Al Coatings on Inconel-718 at 900 °C

    NASA Astrophysics Data System (ADS)

    Saladi, Sekar; Menghani, Jyoti; Prakash, Satya

    2014-12-01

    Cyclic oxidation behavior of detonation-gun-sprayed Ni-5Al coating on Inconel-718 is discussed in the present study. Oxidation studies were carried out on both bare and coated superalloy substrates in air at 900 °C for 100 cycles. The thermogravimetric technique was used to establish kinetics of oxidation. X-ray diffraction, FESEM/EDAX, and x-ray mapping techniques were used to analyze the oxidation products of bare and coated samples. The weight gain of bare superalloy was higher than the Ni-5Al-coated superalloy. Both bare and Ni-5Al-coated superalloys followed nearly parabolic oxidation behavior. The Ni-5Al coating was able to reduce the overall weight gain by 26.2% in comparison with bare superalloy in the given environment. The better oxidation resistance of Ni-5Al coating may be due the formation of protective oxides phases such as NiO, Al2O3, and NiAl2O4 on the oxidized coating and Cr2O3 at the coating-substrate interface. The Ni-5Al coatings obtained from detonation-gun-spraying process showed very little porosity and low surface roughness values.

  17. RETRACTED ARTICLE: 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.

  18. Assessing the kinetics of high temperature oxidation of Inconel 617 in a dedicated HTR impure helium facility coupling thermogravimetry and gas phase chromatography

    NASA Astrophysics Data System (ADS)

    Chapovaloff, J.; Rouillard, F.; Combrade, P.; Pijolat, M.; Wolski, K.

    2013-10-01

    A new facility coupling thermogravimetric analysis (TGA) with gas phase chromatography (GPC) has been developed. This facility is dedicated for studying high temperature oxidation of Inconel 617 in impure helium environment containing H2O, H2 and CO at very low partial pressures (in the Pa range), which is representative of the high temperature reactor (HTR) concept developed within the Generation IV Forum. Simultaneous acquisition of mass gain and gas composition has allowed the influence of carbon monoxide and water vapour on the kinetics of oxidation to be studied. GPC measurements of gas consumption have allowed the plotting of individual mass gain curves for oxidation by H2O and CO. During isothermal exposure at 1123 K for 20 h, the oxidation was mainly due to water vapour with a minor contribution of carbon monoxide during the first hours. The contribution of water vapour to the oxidation kinetics was extracted. It was shown to obey a complete parabolic law and to be limited by an interfacial reaction during the first few hours of oxidation and to be controlled by a mixed interfacial and diffusion process, diffusion becoming the rate-determining step for long term oxidation. There was very good agreement between GPC measurements and the experimental TGA results.

  19. 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.

  20. Selective Growth of Low Stored Energy Grains During δ Sub-solvus Annealing in the Inconel 718 Nickel-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Agnoli, Andrea; Bernacki, Marc; Logé, Roland; Franchet, Jean-Michel; Laigo, Johanne; Bozzolo, Nathalie

    2015-09-01

    The microstructure stability during δ sub-solvus annealing in Inconel 718 was investigated, focusing on the conditions that may lead to the development of very large grains (about 100 μm) in a recrystallized fine grained matrix (4 to 5 μm) despite the presence of second-phase particles. Microstructure evolution was analyzed by EBSD (grain size, intragranular misorientation) and SEM ( δ phase particles). Results confirm that, in the absence of stored energy, the grain structure is controlled by the δ phase particles, as predicted by the Smith-Zener equation. If the initial microstructure is strained ( ɛ < 0.1) before annealing, then low stored energy grains grow to a large extent, despite the Zener pinning forces exerted by the second-phase particles on the grain boundaries. Those selectively growing grains could be those of the initial microstructure that were the least deformed, or they could result from a nucleation process. The balance of three forces acting on boundary migration controls the growth process: if the sum of capillarity and stored energy driving forces exceeds the Zener pinning force, then selective grain growth occurs. Such phenomenon could be simulated, using a level set approach in a finite element context, by taking into account the three forces acting on boundary migration and by considering a realistic strain energy distribution (estimated from EBSD measurements).

  1. 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.

  2. 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.

  3. Mechanism-Based Modeling of Hydrogen Environment Assisted Cracking (HEAC) in High Strength Alloys for Marine Applications: Prediction of Monel K-500 HEAC for Select Environmental and Mechanical Conditions

    DTIC Science & Technology

    2012-10-15

    uncertain. Aged alloy X-750 (Ni- Cr -Fe-Al-Ti) shows a drop in effective hydrogen diffusivity of about a factor of nine from pure Ni, which is... alloy . This is consistent with previous results for a y’ strengthened Ni- Cr -Fe-AI-Ti alloy (X-750) where Ni3(Al,Ti) was found to be an intermediate...confidence associated with predictions of long - term component performance based on short term accelerated laboratory experimentation. CONCLUSIONS • The

  4. Corrosion Behaviour Inconel 617 in VHTR Environment

    SciTech Connect

    Kaczorowski, Damien; Chaovaloff, J.

    2006-07-01

    As it was observed in the past Gas Cooled Reactors, it is expected that the VHTR's cooling gas will be polluted by air ingresses, in-leakages or the degassing of adsorbed species out of the large amount of graphite. These impurities are reactive and may interact with the core graphite and with the metallic materials and may cause some loss or damage of their properties. (authors)

  5. Materials data handbook on Inconel Alloy 718

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1973-01-01

    Handbook is divided into twelve chapters. Scope of information presented includes physical- and mechanical-property data at cryogenic, ambient, and elevated temperatures. This is supplemented with useful information in such areas as material procurement, metallurgy of alloy, corrosion, environmental effect, fabrication, and joining techniques. Design data are presented, as available.

  6. Ductility dip cracking susceptibility of Inconel Filler Metal 52 and Inconel Alloy 690

    SciTech Connect

    Kikel, J.M.; Parker, D.M.

    1998-06-01

    Alloy 690 and Filler Metal 52 have become the materials of choice for commercial nuclear steam generator applications in recent years. Filler Metal 52 exhibits improved resistance to weld solidification and weld-metal liquation cracking as compared to other nickel-based filler metals. However, recently published work indicates that Filler Metal 52 is susceptible to ductility dip cracking (DDC) in highly restrained applications. Susceptibility to fusion zone DDC was evaluated using the transverse varestraint test method, while heat affected zone (HAZ) DDC susceptibility was evaluated using a newly developed spot-on-spot varestraint test method. Alloy 690 and Filler Metal 52 cracking susceptibility was compared to the DDC susceptibility of Alloy 600, Filler Metal 52, and Filler Metal 625. In addition, the effect of grain size and orientation on cracking susceptibility was also included in this study. Alloy 690, Filler Metal 82, Filler Metal 52, and Filler Metal 625 were found more susceptible to fusion zone DDC than Alloy 600. Filler Metal 52 and Alloy 690 were found more susceptible to HAZ DDC when compared to wrought Alloy 600, Filler Metal 82 and Filler Metal 625. Filler Metal 52 exhibited the greatest susceptibility to HAZ DDC of all the weld metals evaluated. The base materials were found much more resistant to HAZ DDC in the wrought condition than when autogenously welded. A smaller grain size was found to offer greater resistance to DDC. For weld metal where grain size is difficult to control, a change in grain orientation was found to improve resistance to DDC.

  7. 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.

  8. 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.

  9. Creep-Fatigue -- Environment Interactions in INCONEL 617

    SciTech Connect

    Terry C. Totemeier; Hongbo Tian

    2007-11-01

    Creep-fatigue testing of alloy 617 was performed in air, vacuum, and purified Ar environments at 1000 °C. Tests were performed in axial strain control at total strain ranges of 0.3% and 1.0% (fully reversed) with hold times at maximum tensile strain ranging from 0 to 1800 s. Introduction of a tensile hold period led to reduced creep-fatigue life at both strain ranges in all environments; the effect was greater at 0.3% than 1.0%. The hold time effect clearly saturated for tests at 1.0% strain range; the behavior at 0.3% was not clear. Decarburization occurred in specimens tested in vacuum and purified Ar, but not in air. Although fatigue lives were longer in the inert environments than in air for most test conditions, quantitative assessment of the differences was not possible because cracking frequently did not occur before test termination due to load drop for tests in inert environment. Cavitation damage was observed for tests with tensile hold periods in all environments.

  10. Pitting of Space Shuttle's Inconel Honeycomb Conical Seal Panel

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank; Gentz, Steven J.; Miller, James B.

    2006-01-01

    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.

  11. Arc termination cracks in Inconel 718 and Incoloy 903

    NASA Technical Reports Server (NTRS)

    Bayless, E.; Mccaig, J.; Poorman, R.

    1978-01-01

    The welding of the nickel base, heat resistant alloys that are used extensively for welded Shuttle engine components revealed solidification cracking characteristics at weld termination points. If not detected and removed, these crater cracks may cause costly component failure. To better understand this characteristic, welding termination techniques were studied and methods developed to eliminate crater cracks. It was determined that weld termination solidification cracking can be eliminated by controlled decrease of welding current, welding voltage, wire feed, and travel speed.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    The paper concentrates on the relation between microstructural observations of the dislocation structures and the macroscopic deformation responses of both aged and homogenized precipitate-hardened alloys at room temperature. The deformation responses are compared to the cyclic deformation response of an aged precipitate-hardened alloy. Early in the deformation, one deformation band per grain and little evidence of work hardening are observed; with increased deformation, work hardening begins, more bands nucleate, and their spacing becomes similar to that in the aged material. It is pointed out that the degree of coarseness of inhomogeneous deformation is not a result of a softening process within the bands due to precipitate shearing, but it is a function of the amount of work hardening within the bands.

  13. 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.

  14. The Effect of Li, He and Ca on Grain Boundary Cohesive Strength in Ni

    SciTech Connect

    Smith, Richard W.; Geng, W. T.; Geller, Clint B.; Wu, R.; Freeman, A. J.

    2000-04-01

    Boron is added to nickel-base superalloys such as Alloy X-750 in order to enhance high temperature strength and ductility so that the alloy may be more easily hot worked[1]. Boron additions also have been shown to ameliorate intergranular hydrogen embrittlement in nickel[2], and to improve the high temperature resistance of Alloy X-750 to aqueous stress corrosion cracking (SCC) in the absence of irradiation[3]. Recent quantum mechanical calculations demonstrate that boron strengthens grain boundaries in pure nickel[4], and may contribute to the observed benefits of boron on workability and fracture resistance of nickel alloys. Alloy X-750 exhibits greater susceptibility to intergranular stress corrosion cracking (IGSCC) when irradiated[5], and it has been proposed that the presence of grain boundary helium and/or lithium is responsible. Arguments have been advanced that helium embrittlement of the grain boundaries is primarily responsible for the greater observed susceptibility to IGSCC in irradiated X-750[1]. Alternatively, it has been proposed that lithium promotes IGSCC either by entering the water at the crack tip and lowering the local pH, or by inducing a restructuring of the grain boundary itself[1]. Direct embrittlement of grain boundaries by lithium also has been investigated by ion bombardment in Nimonic PE16, illustrating that under certain conditions lithium can produce degrees of embrittlement in nickel comparable to that produced by helium[6]. It is important to understand the relative roles of these species in grain boundary embrittlement in nickel alloys so that better predictive abilities and mitigation strategies can be developed. Toward that end, quantum mechanical calculations have been performed to investigate the influence of isolated lithium and helium atoms on the cohesive strength of an ideal grain boundary in pure nickel.

  15. Hydrogen transport in nickel-base alloys

    NASA Astrophysics Data System (ADS)

    Turnbull, A.; Ballinger, R. G.; Hwang, I. S.; Morra, M. M.; Psaila-Dombrowski, M.; Gates, R. M.

    1992-12-01

    The electrochemical permeation technique has been used to characterize hydrogen transport and trapping in pure nickel and in alloys 600, X-750, and 718 at a temperature of 80 °C. The “effective diffusivity ” of hydrogen atoms in alloy 600 is reduced by a factor of about 5 compared to pure nickel. This is attributed to both compositional changes and the presence of [(Ti, Nb)C] carbides. Aging of alloy 600, with subsequent M23C6 carbide precipitation, does not significantly influence the measured “effective diffusivity,” which is explained by the dominant effect of preexisting [(Ti, Nb)C] carbides. The “effective diffusivity” of hydrogen atoms in solution-annealed alloy X-750 is reduced by a factor of about 9 compared to that of pure nickel. This is also attributed to compositional changes and [(Ti,Nb)C] carbides. Aging of alloy X-750, which causes precipitation of γ'[Ni3(Al, Ti)], reduces the “effective diffusivity” by an additional factor of 5 or more. Double aging at 885 °C/24 hours, 704 °C/20 hours following hot working yields the greatest reduction in “effective diffusivity.” Analysis of permeation transients using a diffusion- trapping model indicates a binding energy associated with trapping due to the γ phase of be- tween -31 and -37 kJ/mol. The “effective diffusivity” of hydrogen in alloy 718 is about 40 pct greater than for alloy X-750 for the same double and direct aging treatments. The average “effective diffusivities” of the double-aged and direct-aged alloy 718 are comparable, but the permeation transients for the double-aged treatment are significantly steeper. The double-aged treatment with predominantly δ phase (orthorhombic Ni3Nb) yields a binding energy of about -30 kJ/mol. Analysis of the direct aged-treated 718, which contains predominantly γ″ phase (body-centered tetragonal Ni3Nb) gave a binding energy between -23 and -27 kJ/mol. Seg- regation of hydrogen atoms to the γ matrix interface, combined with a

  16. 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.

  17. Mechanical, Corrosion, and Fatigue Properties of 15-5 PH, Inconel 718, and Rene 41 Weldments

    DTIC Science & Technology

    1975-05-01

    etched for a minimum of 30 seconds with aqua regia ; 800•,’ iCl, 20* HNO3. The stainless-steel spc-iercns werc etched for about 10 seconds in Fry’s...AdOO 318V1IVAV IS38 WO81A 33OflGO8d3H 19. KEY WORDS (Continue on reverse aide it necessary aid Identity by block number) We idments Propdrties

  18. Microstructural evolution in the HAZ of Inconel 718 and correlation with the hot ductility test

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.; Genculu, S.

    1983-01-01

    The nickel-base alloy 718 was evaluated to study the role of preweld heat treatment in reducing or eliminating heat-affected zone hot cracking. Three heat treatments were studied using the Gleeble hot ductility test. A modified hot ductility test was also used to follow the evolution of microstructure during simulated welding thermal cycles. The microstructural evolution was correlated with the hot ductility data in order to evaluate the mechanism of hot cracking in alloy 718. The correlation of hot ductility with microstructure showed that recrystallization, grain growth, and dissolution of precipitates did not in themselves cause any loss of ductility during cooling. Ductility loss during cooling was not initiated until the constitutional liquation of NbC particles was observed in the microstructure. Laves-type phases were found precipitated in the solidified grain boundaries but were not found to correlate with any ductility loss parameter. Mechanisms are reviewed which help to explain how heat treatment controls the hot crack susceptibility of alloy 718 as measured in the hot ductility test.

  19. 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.

  20. 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.

  1. 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.

  2. Joining of superalloy Inconel 600 by diffusion induced isothermal solidification of a liquated insert metal

    SciTech Connect

    Egbewande, A.T.; Chukwukaeme, C.; Ojo, O.A.

    2008-08-15

    The effect of process variables on the microstructure of transient liquid phase bonded IN 600 using a commercial filler alloy was studied. Microstructural examination of bonded specimens showed that isothermal solidification of the liquated insert occurred during holding at the joining temperatures. In cases where the holding time was insufficient for complete isothermal solidification, the residual liquid transformed on cooling into a centerline eutectic product. The width of the eutectic decreased with increased holding time and an increase in initial gap width resulted in thicker eutectic width in specimens bonded at the same temperature and for equivalent holding times. In addition to the centerline eutectic microconstituent, precipitation of boron-rich particles was observed within the base metal region adjacent to the substrate-joint interface. Formation of these particles appeared to have influenced the rate of solidification of the liquated interlayer during bonding. In contrast to the conventional expectation of an increase in the rate of isothermal solidification with an increase in temperature, a decrease in the rate was observed with an increase in temperatures above 1160 deg. C. This could be related to a decrease in solubility of boron in nickel above the Ni-B eutectic temperature.

  3. 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.

  4. Investigation on the Interface Morphologies of Explosive Welding of Inconel 625 to Steel A516 Plates

    SciTech Connect

    Mousavi, S. A. A. Akbari; Zareie, H. R.

    2011-01-17

    The purpose of this study is to produce composite plates by explosive cladding process. This is a process in which the controlled energy of explosives is used to create a metallic bond between two similar or dissimilar materials. The welding conditions were tailored through parallel geometry route with different operational parameters. In this investigation, a two-pronged study was adopted to establish the conditions required for producing successful solid state welding: (a) Analytical calculations to determine the weldability domain or welding window; (b) Metallurgical investigations of explosive welding experiments carried out under different explosive ratios to produce both wavy and straight interfaces. The analytical calculations confirm the experimental results. Optical microscopy studies show that a transition from a smooth to wavy interface occurs with an increase in explosive ratio. SEM studies show that the interface was outlined by characteristic sharp transition between two materials.

  5. Surface modification of cast inconel 740 superalloy by heat-assisted friction stir processing

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Yeon; Jung, Woo-Sang; Lee, Won-Sik; Byeon, Jai-Won

    2016-07-01

    Cast In740 Ni-based alloy with large grains generally show remarkable high temperature strength. However, this alloy is still have insufficient surface microstructure-dependent properties. In this study, for improvement of surface properties, surface modification of a cast In740 Ni-based superalloy was successfully performed by friction stir processing using a conventional two-horsepower milling machine and by additional heating to facilitate plastic flow of the hard alloy. Without using a high-power heavy stirring machine, a notable reduction in grain size of 2.9 μm was achieved and a corresponding 30% increase in Vickers hardness was observed. The microstructure in the stir zone was analyzed in terms of the grain size and precipitate distribution. The result of the potential dynamic polarization test and in-situ acoustic emission monitoring show that electrochemical corrosion resistance was improved by this surface modification process.

  6. Time and temperature dependence of multi-walled carbon nanotube growth on Inconel 600.

    PubMed

    Pal, S K; Talapatra, S; Kar, S; Ci, L; Vajtai, R; Borca-Tasciuc, T; Schadler, L S; Ajayan, P M

    2008-01-30

    The growth kinetics of vertically aligned multi-walled carbon nanotubes (MWNTs) on conductive substrates is investigated by synthesizing MWNTs at different growth temperatures and measuring ex situ the length of the nanotubes as a function of growth duration. A typical 'root growth' mechanism (saturation of MWNT lengths with increasing growth duration) was observed. The value of the activation energy (E(a)≈136 ± 5 kJ mol(-1)) of the MWNT growth reaction is suggestive of carbon diffusion through the bulk of the iron catalyst particle versus diffusion on its surface. These findings will help in optimizing MWNT growth on conductive substrates for various applications.

  7. Relationship of Grain Boundary Structure and Mechanical Properties of Inconel 690

    DTIC Science & Technology

    2009-05-08

    left. (A) 4 of 6 indentation rows showed an increased hardness near the grain boundary relative to the bulk region of ~13.8% (4.43 GPa to 5.04 GPa...Chapter 4 . A discussion of the experimental procedure follows in Chapter 5. Finally, in Chapters 6 and 7, the results and corresponding conclusions... 4 5 6 0 2000 4000 6000 8000 10000 12000 Indentation Depth (nm) H ar dn es s (G Pa ) Figure 5.8 – Hardness as a function of indentation depth

  8. Microscopic Observations on the Origin of Defects During Machining of Direct Aged (DA) Inconel 718 Superalloy

    NASA Astrophysics Data System (ADS)

    Dosbaeva, G. K.; Veldhuis, S. C.; Elfizy, A.; Fox-Rabinovich, G.; Wagg, T.

    2010-11-01

    Surface quality of advanced superalloys after machining is one of the major issues in the aerospace industry because it directly affects service characteristics of the machined part. Tool life of cemented carbide inserts with the TiAlN coating during machining of direct aged DA 718 alloys under roughing and finishing conditions has been under study. The defect origin on the surface of the machined part was investigated. Metallographic observations of the DA 718 were made using optical metallography and SEM/EDS. To find out the origins of surface defect formation, the morphology of machined parts and cross sections of the machined surfaces have been investigated. Two major categories of defects were detected on the surface of the machined part: cracks and tears. The origin of the cracks on the machined surface is related to shearing of the primary complex TiC/NbC carbide revealed in a structure of DA 718 alloy. At the same time, Nb-rich regions of the primary complex carbide interact with the environment (oxygen from air) during machining with further formation of low strength oxide layer on the surface, forming tears.

  9. Brazing Inconel 625 Using Two Ni/(Fe)-Based Amorphous Filler Foils

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Shiang; Shiue, Ren-Kae

    2012-07-01

    For MBF-51 filler, the brazed joint consists of interfacial grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr-rich matrix. In contrast, the VZ-2106 brazed joint is composed of interfacial Nb6Ni16Si7 precipitates as well as grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr/Fe-rich matrix. The maximum tensile strength of 443 MPa is obtained from the MBF-51 brazed specimen. The tensile strengths of VZ-2106 brazed joints are approximately 300 MPa. Both amorphous filler foils demonstrate potential in brazing IN-625 substrate.

  10. Computational modeling of NbC/Laves formation in INCONEL 718 equiaxed castings

    SciTech Connect

    Nastac, L.; Stefanescu, D.M.

    1997-07-01

    The goal of this work is to develop a solidification kinetics model for prediction of NbC and Laves phase evolution during casting solidification. Previous studies on alloy 718 showed that both NbC and Laves produce intergranular liquid films due to the intergranular distribution of Nb and C. Also, the ability of Laves to promote intergranular liquation cracking (microfissuring and hot cracking) during heat treatment is much higher than that of NbC. This is because the temperature of Laves phase formation is usually lower than that of NbC, i.e., liquation initiates at the eutectic-Laves temperature. Experimental evidence demonstrates that the amount of NbC and Laves in cast alloy 718 is different from that predicted by phase equilibrium. The reason for this difference is that while in equilibrium processes mass diffusion transport is very fast compared with solidification kinetics (V {much_lt} D/L), in casting processes, solidification kinetics is much closer to diffusivity (V {le} D/L). Thus, solidification kinetics cannot be ignored.

  11. 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.

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

    NASA Technical Reports Server (NTRS)

    Prater, T.; Tilson, W.; Jones, Z.

    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.

  13. 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.

  14. 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.

  15. 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.

  16. Grit Blasting for Removal of Recast Layer from EDM Process on Inconel 718 Shaft: An Evaluation of Surface Integrity

    NASA Astrophysics Data System (ADS)

    Holmberg, Jonas; Wretland, Anders; Berglund, Johan

    2016-12-01

    The heat generated during EDM melts the work material and thereby allows large amounts to be removed, but an unfavorable surface of a recast layer (RCL) will also be created. This layer has entirely different properties compared to the bulk. Hence, it is of great interest to efficiently remove this layer and to verify that it has been removed. The main objective of this work has been to study the efficiency of grit blasting for removal of RCL on an EDM aero space shaft. Additionally, x-ray fluorescence (XRF) has been evaluated as a nondestructive measurement to determine RCL presence. The results show that the grit-blasting processing parameters have strong influence on the ability to remove RCL and at the same time introduce beneficial compressive stresses even after short exposure time. Longer exposure will remove the RCL from the surface but also increase the risk that a larger amount of the blasting medium will get stuck into the surface. This investigation shows that a short exposure time in combination with a short grit-blasting nozzle distance is the most preferable process setting. It was further found that handheld XRF equipment can be used as a nondestructive measurement in order to evaluate the amount of RCL present on an EDM surface. This was realized by analyzing the residual elements from the EDM wire.

  17. Model of the Frictional Heating of Inconel 718 and Titanium (ti-6al-4v) in Helium

    NASA Technical Reports Server (NTRS)

    Skowlund, Christopher T.

    1991-01-01

    A computer model of the frictional heating of metals in an inert environment has been developed. The model incorporates the effects of the heat loss from the samples due to conduction, radiation, and convection to the surroundings. This model allows the measured temperatures to be used to determine the amount of heat produced at the interface during the experiment by the sliding contact of two different metallic samples. The results of the simulation for an experiment run at the NASA White Sands Test Facility (WSTF) show that for the same heat production at the interface the heat losses have a significant effect on the temperatures in the samples. But, the heat losses do not significantly affect the different calculated heat flows (or friction coefficients), at the interface, that are necessary to correlate the measured temperatures.

  18. 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.

  19. 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.

  20. Toughness testing and high-temperature oxidation evaluations of advanced alloys for core internals

    SciTech Connect

    Tan, Lizhen; Pint, Bruce A.; Chen, Xiang

    2016-09-16

    Alloy X-750 was procured from Carpenter Technology and Bodycote in this year. An appropriate TMT was developed on Alloy 439 to obtain materials with refined grain size for property screening tests. Charpy V-notch impact tests were completed for the three ferritic steels Grade 92, Alloy 439, and 14YWT. Fracture toughness tests at elevated temperatures were completed for 14YWT. The tests will be completed for the other alloys in next fiscal year. Steam oxidation tests of the three ferritic steels, 316L, and Zr–2.5Nb have been completed. The steam tests of the Ni-based superalloys and the other austenitic stainless steels will be continued and finished in next fiscal year. Performance ranking in terms of steam oxidation resistance and impact/fracture toughness of the alloys will be deduced.

  1. Effect of Manufacturing Processes on Structural Allowables Phase 2

    DTIC Science & Technology

    1986-11-01

    test ran 10,000,000 cycles and stopped. 22 TABLE 4. NOTCHED K = 3, FATIGUE DATA FOR INCONEL 718 STA BAR--EONGITUDINAL DIRECTION Specimen Maximum...3 TEST PROGRAM ......................................................... 3 Inconel 718 Bar (Solution Treated and Aged...PROPERTIES OF INCONEL 718 STA BAR ............. 14 2(a). MECHANICAL PROPERTIES OF INCONEL 718 STA BAR ............. 17 3. UNNOTCHED FATIGUE DATA FOR

  2. Strain gage attachment by spot welding reduces the fatigue strength of Ti-6Al-4V, Rene 41, and Inconel X

    NASA Technical Reports Server (NTRS)

    Imig, L. A.

    1972-01-01

    Fatigue tests were conducted with constant-amplitude axial stresses in the ratio of minimum to maximum stress of 0.05 (R=0.05). Specimens with and without strain gages were tested at 21 C, and superalloy specimens with and without strain gages were tested at 21 C and 815 C.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Effect of Welding Heat Input on Microstructure and Texture of Inconel 625 Weld Overlay Studied Using the Electron Backscatter Diffraction Method

    NASA Astrophysics Data System (ADS)

    Kim, Joon-Suk; Lee, Hae-Woo

    2016-12-01

    The grain size and the texture of three specimens prepared at different heat inputs were determined using optical microscopy and the electron backscatter diffraction method of scanning electron microscopy. Each specimen was equally divided into fusion line zone (FLZ), columnar dendrite zone (CDZ), and surface zone (SZ), according to the location of the weld. Fine dendrites were observed in the FLZ, coarse dendrites in the CDZ, and dendrites grew perpendicular to the FLZ and CDZ. As the heat input increased, the melted zone in the vicinity of the FLZ widened due to the higher Fe content. A lower image quality value was observed for the FLZ compared to the other zones. The results of grain size measurement in each zone showed that the grain size of the SZ became larger as the heat input increased. From the inverse pole figure (IPF) map in the normal direction (ND) and the rolling direction (RD), as the heat input increased, a specific orientation was formed. However, a dominant [001] direction was observed in the RD IPF map.

  8. The Friction and Wear of Copper in High-Load, Low-Speed, Small-Amplitude Reciprocating Sliding

    DTIC Science & Technology

    1982-08-01

    carbon, medium chromium and nickel steel Inconel 718 Nickel-chromium based alloy k Wear constant, commonly called Archard wear coefficient n Wear...nickel-chromium based alloy ( Inconel 718 ) and (c) high-purity copper. These metals hereafter are identified as (a) steel, (b) Inconel , and (c) copper. I...22 WEAR RESULTS ........... . ............................. 23 Stages of Wear for Copper Sliding on Steel or Inconel .......... . 26

  9. Orbital Transfer Vehicle Engine Technology

    DTIC Science & Technology

    1991-11-01

    similar materials. For lighter weight engines, use of a zirconium copper face plate would best accommodate Inconel 718 oxygen manifolds and Incoloy 909...well with most nickel and cobalt base alloys, particularly Haynes 188, Hastelloy X, Monel K-500, Inconel 625, and Inconel 718 . Diffusion bonding is... Inconel 718 show that it is possible to overcome the aluminum and titanium constituents for high quality diffusion bond joints. The most common solution to

  10. Micro-Flow Studies in the 1 to 50 Micron Domain

    DTIC Science & Technology

    2001-08-01

    and Cross-sectional View of Nickel Plated Inconel Substrate 16 2-7 Typical Stainless Steel Substrates 17 2-8 Improved Microchannel Fabrication...i .. lrl Figure 2-6. Plan View and Cross-sectional View of Nickel-Plated Inconel Substrate the substrate prior to plating (or bonding), so... Inconel 625 systems. Nickel is easily etched in FeCl, while Inconel 625 is extremely resistant to FeCl, and is a stiff, strong material. An initial

  11. High Frequency Fatigue of Turbine Blade Material.

    DTIC Science & Technology

    1982-10-01

    TESTS 83 APPENDIX II - S-N DATA FOR INCONEL - 718 99...amplitude tests were run on sheet Inconel - 718 at 650*C. The data is presented as da/dM vs AK o plots and in tabular maj or form. These tests are included in...Kip 98 APPENDIX II S-N DATA FOR INCONEL - 718 During the early stages of this program, several fatigue life tests , (S-N tests ), were run on Inconel - 718

  12. Development of Advanced Carbide for Nickel-Based Alloy Machining for Turbine Engines

    DTIC Science & Technology

    2006-06-20

    based alloys such as Inconel 718 with 40% higher machining productivity. 15. SUBJECT TERMS NCDMM; Success Stories; Kennametal, Inc.; Inconel 718 ...Inc. involved developing an advanced coated carbide cutting tool for turning nickel-based alloys such as Inconel 718 with 40% higher machining...nd DOC constant for the ng of six (6) cutting tools t 180 and 250 SFM led to l performance goal. It was r resulting from premature e in Inconel

  13. Sputtering Studies of Multi-Component Materials by Weight Loss and Cavity Ring-Down Spectroscopy (Postprint)

    DTIC Science & Technology

    2006-06-26

    demonstrate measurements of multi-component materials by measuring the sputtering of chromium, iron, and molybdenum from inconel 718 . 15. SUBJECT...by measuring the sputtering of chromium, iron, and molybdenum from inconel 718 . Nomenclature A(ν) = Absorption lineshape Aki = Einstein A...materials. We from inconel 718 . The major constituents of inconel , Mo~3%, Cb+Ta~5%. We could readily measure Cr, the measured spectra we determine

  14. The Effect of Stress and Hot Corrosion on Nickel-Base Superalloys

    DTIC Science & Technology

    1985-03-01

    Inconel 718 round bar tensile specimen. 19 ’I.. FIC. . Experimental test apparatus. 20 The creep ...the corrosion attack. 3 33 77. -. IV. EXPERIMENTAL RESULTS AND DISCUSSION A. INCONEL 718 1. CREEP BEHAVIOR Sustained-load creep tests were conducted at...of Inconel 718 were prepared for metrllographic examination after creep testing . Figure 18 shows dramatically the hot corrosion attack by a

  15. 77 FR 29212 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-17

    ... retention bolts, replacement of existing titanium bolts with new Inconel bolts, and related investigative... fractured or missing latch pin retention bolts, replacement of existing titanium bolts with new Inconel... Inspections Replacing latch pin retention bolts made of titanium with new Inconel bolts, in accordance...

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

    NASA Astrophysics Data System (ADS)

    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 338 C included 157 small and 40 large 60 degree 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 315 C 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 (427 C) 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.

  17. 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.

  18. 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.

  19. 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.

  20. Growth Optimization of YBa2NbO6 Buffer Layers (Postprint)

    DTIC Science & Technology

    2012-02-01

    single crystals, and IBAD MgO buffered Inconel substrates has been investigated. X-ray diffraction confirms the epitaxial growth of highly h00 oriented...YBNO thin films on single crystal substrates and IBAD MgO buffered Inconel substrates. The best average surface roughness of the YBNO films...diffraction, crystal, buffered, inconel , epitaxial, films, substrates, layers, growth, investigated, sufficient, preliminary, critical 16. SECURITY

  1. Performance and Thrust-to-Weight Optimization of the Dual-Expander Aerospike Nozzle Upper Stage Rocket Engine

    DTIC Science & Technology

    2012-06-01

    Copper (C17000 TH04) Oxygen-Free Copper (C10100 1180 Temper) Cobalt (Forged Electrolytic) INCONEL ® 718 (Annealed & Aged) Compatible with O2 / Useable...for chamber cooling jacket, structural jacket, and O2 plumbing INCONEL ® 625 (Annealed) Aluminum 7075 T6 Not compatible with O2 or H2 / Useable for... INCONEL 718 Copper Table 9 Impact of material strength on T/W Worst Material Selection Best Material Selection Yield Strength Ultimate

  2. Nondestructive Evaluation (NDE) Exploratory Development for Air Force Systems. Delivery Order 0001: Quick Reaction NDE and Characterization--Effects of Chemical Effects of Chemical Etching after Pre-Inspection Mechanical Cleaning on Fluorescent Penetrant Indications of Fatigue Cracks

    DTIC Science & Technology

    2011-08-01

    FPI crack indications degraded by mechanically cleaning cracked specimens made of Ti-6Al-4V and Inconel 718. The data showed that minimal etching...3.3 Etchant Solution (High Chromium Super Alloy – Class G) for Inconel 718 .......................... 3 3.4 Etch Rate Test Tabs...Media ...................... 16 Figure 9. SEM Images of Inconel Specimen 626-52 Cleaned with Dry Plastic Media ........................ 17 Figure 10

  3. Predicting the Effects of Overloads on Sustained-Load Crack Growth in a High-Temperature Superalloy.

    DTIC Science & Technology

    1985-12-01

    test data *.... ’ .. generated on specimens of Inconel 718 at 650 C with periodic overloads of...generated test data (131 for Inconel 718 at 650 C, with an R ratio of 0.1 and frequency of 0.01 Hz. This frequency is approximately that of the single...retardation due to overloads. Predictions were compared with experimental test data generated on specimens of Inconel 718 at 650 C with

  4. 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.

  5. Development of an Advanced Carbide Cutting Tool for Nickel-based Alloy Machining

    DTIC Science & Technology

    2006-08-28

    Inconel 718 utilizing state-of-the-market and state-of-the-art methods. The goal of increasing machining productivity by 40% was achieved with the...project is turning of Inconel 718 alloy. 1.3 Funding The total NCDMM funding for the project was $150,000 ($120,000 for labor and $30,000 for workpiece...tasks Task 1: Review current Inconel machining practice Task 2: Establish the current state of the art in Inconel 718 turning  Establish baseline data

  6. 78 FR 42584 - Bureau of International Security and Nonproliferation: Report to Congress Pursuant to Section...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-16

    ..., military, or ballistic missile programs of Iran: aluminum; beryllium; boron; cobalt; copper; copper infiltrated tungsten; copper- beryllium; graphite; hastelloy; inconel; magnesium; molybdenum; nickel;...

  7. 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.

  8. Optimum Thread Rolling Process That Improves SCC Resistance

    SciTech Connect

    A.R. Kephart

    2001-10-29

    Accelerated testing in environments aggressive for the specific material have shown that fastener threads that are rolled after strengthening heat treatments have improved resistance to SCC initiation. For example, intergranular SCC was produced in one day when machined (cut) threads of high strength steel (ASTM A193 B-7 and A354 Grade 8) were exposed to an aggressive aqueous environment containing 8 weight % boiling ammonium nitrate and stressed to about 40% of the steel's yield strength (120 ksi, 827 MPa). In similar testing conditions, fasteners that had threads rolled before heat-treatment (quench and temper) had similar susceptibility to SCC. However, threads rolled after strengthening, exhibited no SCC after a week of exposure, even when stressed to 100% of the B-7 alloy yield strength. Similarly, intergranular SCC was produced in less than one day when machined (cut) threads of nickel-base alloys (X-750 and aged 625) were exposed to an aggressive 750 F doped steam environment (containing 100 ppm of chloride, fluoride, sulfate, nitrate and a controlled hydrogen overpressure) and stressed to about 80% of the alloy yield strength (117 ksi, 807 MPa). In similar testing conditions, threads rolled after strengthening exhibited no SCC after 50 days of exposure. This beneficial effect of the optimum thread rolling process (i.e., threads rolled after strengthening) is due to the retention of large residual compressive stresses in the thread roots (notches) which mitigate the applied notch tensile stresses resulting from joint design pre-loads. use of these material specific aggressive environments can provide an accelerated test to verify that threads were produced by the optimum thread rolling process. These tests could support fastener acceptance criteria or failure analysis of fasteners with unknown or uncertain manufacturing processes. The optimum process effects may not always be detected by more conventional methods (e.g., metallography or hardness testing).

  9. 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.

  10. Characterization of a Hall Effect Thruster Using Thermal Imaging

    DTIC Science & Technology

    2007-03-01

    Stainless Inconel X Polished 0.19 to 0.20 -183 to 486 Stainless Inconel X Polished 0.19 to 0.22 -183 to 486 Stainless 301 Polished 0.16 26...0.51 718 11 0.53 707 NA 70 Table 15: Alumina Plasma Spray Temperature Error Due to Emissivity Alumina Plasma Spray Spot Location in

  11. 77 FR 6522 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-08

    ... 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 the... necessary. Replacing latch pin retention bolts made of titanium with new Inconel bolts, if...

  12. Thermal and structural tests of a hydrogen cooled panel

    NASA Technical Reports Server (NTRS)

    Richard, C. E.; Duncan, J. D.; Gellersen, E. W.; Demogenes, C.

    1972-01-01

    An experimental evaluation of the thermal and structural performance of a hydrogen-cooled panel is presented. The panel, which was of brazed Inconel 625 and Inconel 718 construction, was designed for a heat flux of 100 BTU per second-foot squared and an external surface pressure of 100 psi.

  13. Mechanical Properties of Nb25Mo25Ta25W25 and V20Nb20Mo20Ta20W20 Refractory High Entropy Alloys (Postprint)

    DTIC Science & Technology

    2011-05-01

    temper ature from 548 MPa at 1000 C to 405 MPa at 1600 C (Table 2).ublic release; distribution unlimited. Table 4 Composition (in wt.%) of Inconel 718 ...values of the refractory HEAs are much higher than those of Haynes 230 at all studied temperatures and higher than those of Inconel 718 at...than twice (for the Nb25Mo25 Ta25W25 alloy) or four times (for the V20Nb20Mo20Ta20W20 alloy) higher than for Inconel 718 or Haynes 230 at 1000 C. The

  14. Nondestructive Evaluation Technology Initiatives II. Delivery Order 0002: Whole Field Turbine Disk Inspection

    DTIC Science & Technology

    2007-04-01

    5.2 FPI PoD samples A set of Inconel 718 samples with artificial fatigue cracks that was used as a fluorescent penetrant inspection (FPI) PoD...No None N/A 11N E 0.029 Yes No Yes Anti-gallant No 12N E 0.028 Yes No Yes Lubricant No Notes: A = Aluminum 7075-T6 N = Inconel 718 S...contaminants on the performance of Sonic IR testing of engine components. The specimens were comprised of nine Inconel 718 and six 7075-T6 aluminum plates

  15. Crack Growth-Based Predictive Methodology for the Maintenance of the Structural Integrity of Repaired and Nonrepaired Aging Engine Stationary Components

    DTIC Science & Technology

    1999-04-01

    by its reduction in area. Inconel 718 -(IN718) Kb Specimen-A rectangular cross section test specimen used for crack growth testing which best represents...GEAE contract to look at weldability of wrought and cast Inconel 718 (IN718) material after exposure to the aforementioned 15 and 30 simulated repair...COMPOSITION WROUGHT PROGRAM MATERIAL AFTER 40 HEAT TREATMENT CYCLES 100 90 - Inconel 718 C995HD40 Tpeak= 1260 °C S70 NDT=1105 ’C60 NST=1304 0C ឬ- DRT=1050 °C

  16. Thermal Residual Stress Relaxation and Distortion in Surface Enhanced Gas Turbine Engine Components

    DTIC Science & Technology

    1998-01-01

    peening, gravity peening and laser shocking in Ti-6Al-4V and Inconel 718 at engine temperatures is summarized. Both the magnitude and rate of relaxation...compressive layer produced by different SE techniques in Ti-6Al-4V and Inconel 718 has revealed significant differences in the stability of the...peening, and LSP in Ti-6Al-4V and Inconel 718 used in this study are shown in Figures 1 and 2. Thermal Relaxation. Both magnitude and rate of thermal

  17. Aircraft Material Fire Test Handbook

    DTIC Science & Technology

    1990-09-01

    or inconel tubes, or equivalent shall be provided. The thermocou- pies shall be aligned in a row 1.0 ± 0.1 in (25 ± 3 mm) apart. 11.3.3 Heat Flux...152 mm) m 1. l2 3 4 5 Material: 0.031 in inconel - -sA - - -111 2 3 A = Burner extension tube O D (127 mm) Figure 11-1. Burner Extension Funnel 11-10...or inconel tubes or equivalent shall be provided.3 The thermocou- ples shall be aligned in a row 1.0 +/0.1 in (25 +/2 mm) apart. 12.3.3 Heating Rate

  18. 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.

  19. 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.

  20. EROSION PROPERTIES OF SELECTED TURBINE MATERIALS IN WATER AND POTASSIUM.

    DTIC Science & Technology

    COBALT ALLOY HAYNES STELLITE 6B, MOLYBDENUM ALLOY TZM, MOLYBDENUM ALLOY TZC, MOLYBDENUM ALLOY 0.5TI, NICKEL ALLOY INCONEL, NICKEL ALLOY RENE 41, NICKEL ALLOY WASPALOY, SNAP, SNAP 50/SPUR, SPUR, STEEL 1050, STEEL 410 .

  1. 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.

  2. Corrosion response of downhole steam generator assembly and instrumentation and supply line tubings at Long Beach field test

    SciTech Connect

    Weirick, L.J.

    1983-07-01

    Three families of metals were used to make the non-combustor components for Sandia's downhole steam generator assembly and supply and instrumentation lines. These three families were: first, plain carbon steel (API Grade J 55); second, austenitic stainless steels (316 and 310); and third, a nickel-base superalloy (Inconel 600). The metals in all three of these families were found to be deficient in their corrosion response. J 55 exhibited minimal to severe general corrosion (rusting). The austenitic stainless steels pitted and cracked. Inconel 600 showed both severe pitting and some intergranular attack. For the most part, these materials were found to be unsuitable for extended life in a downhole steam generator. It is recommended that Inconel 625 be used in future systems where a moderate strength material is specified and Inconel 718 be considered where a high strength material is necessary. 11 references, 45 figures, 5 tables.

  3. Treating Nickel Alloy For Sonic Quality

    NASA Technical Reports Server (NTRS)

    Stuck, Donald E.; Kramer, David; Lam, Dan Q.

    1990-01-01

    Treatment makes bars of Inconel(R) 718 alloy homogeneous so acoustic waves pass through material at constant velocity. Makes possible accurate acoustic monitoring of preloads in fasteners made from bars. Eliminates longitudinal inhomogeneous regions by recrystallizing bars.

  4. Performance Specification for the Battery Monitoring System of the Program Executive Office Ground Combat Systems (PEO GCS)

    DTIC Science & Technology

    2009-10-26

    network (CAN) OSHA 29 CFR 1910 Occupational Safety and Health Standards Non-Government standards and other publications are normally available... Inconel , or other alloys. Electroplated and electroless plating for electrical components or other applications requiring corrosion and wear

  5. Effect of several surface treatments on the strength of a glass ceramic-to-metal seal

    SciTech Connect

    Kramer, D P; Salerno, R F; Egleston, E E

    1982-02-10

    Test shells of Inconel 625, Inconel 718, 21-6-9 stainless steel, and Hastelloy, C-276 were plasma and/or chemically cleaned before sealing with a multi-component glass-ceramic-to-metal seal was evaluated using a hydrostatic burst test. The results show that plasma cleaning can be used to increase the hydrostatic burst strength and hermeticity of a glass ceramic-to-metal seal.

  6. A Critical Review of the State of Finite Plasticity

    DTIC Science & Technology

    1990-05-01

    model and the Bodner-Partom constitutive equations, as well as with available experimental results for the uniaxial behavior of’ INCONEL 718 at 1200’F...superalloy. For a more detailed description. see Eftis et ad 1 1989. Sec. IV). where onginal references for the experimental data in cyclic tests for...determunation of the mechanical properties of INCONEL 718 at 1200F can be found. 368 P. M. Nagbdi ZAMP The existing literature in the theory of elastic

  7. A Critical Review of the State of Finite Plasticity

    DTIC Science & Technology

    1990-05-01

    experimental data in cyclic tests for determunation of the mechanical ,roperues of INCONEL 718 at 1200 F can be found. 368 P. M. Nqbdi ZAMP The existing...behavior of’ INCONEL 718 at 1200’F for cyclic loading. While such a comparison may be interesting, it does not provide a crucial basis for distinguishtng...pertaining to softening of rock. Wawersik and Fairhurst (1970) and Hudson. Brown and Fairhurst (1972) have reported their test data in small deformation

  8. U.S. Navy Halon 1211 Replacement Program: Assessment of Aircraft Collateral Damage From Dry Chemical Fire Extinguishing Agents.

    DTIC Science & Technology

    1999-11-15

    evaluating the high temperature corrosion of Inconel 690 caused by sodium carbonate, calcium carbonate and sodium meta silicate [55]. Inconel 690 is...exposures. In particular was the lack of studies and data on the potential high temperature corrosion problems for turbine engines. In order to perform ...4 4.2 High Temperature Corrosion - Oxidation and Mixed Gas Attack ............ 5 4.3 High Temperature Corrosion - Hot

  9. Analytical and Experimental Investigations of Sodium Heat Pipes and Thermal Energy Storage Systems.

    DTIC Science & Technology

    1982-01-01

    evaporator length was 1.25 in. in length with the condenser 5 in. in length. The heat pipe wick consisted of a double wrap of 60 mesh nickel screen spot welded ...the heat pipes . Four Inconel sheathed Chromel-Alumel thermocouples were attached by resistance spot welding Inconel tabs to the heat pipe outside...accumulated. After this processing the heat pipes were closed using an electrode fusion weld to crimp and weld the filled tubes. The cleaning procedures

  10. 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)

  11. Metal Injection Moulding: A Near Net Shape Fabrication Method for the Manufacture of Turbine Engine Component

    DTIC Science & Technology

    2006-05-01

    Mechanical Properties of Inconel 625 and 718 Alloys Processed by Powder Injection Molding, Superalloys 718 , 625, 706 and Various Derivatives, ed...on the processing and characterization of Inconel 625 LPIM material are presented. In depth microstructural characterization was performed on the... dissolution of second phase particles in the microstructure can be achieved and needs to be optimized with secondary heat treatment such as solution

  12. Electrochemical Study of Corrosion Phenomena in Zirconium Alloys

    DTIC Science & Technology

    2005-06-01

    determined that there are large ECP differences associated with Inconel and zirconium alloys that correlate to increased galvanic current density when the...Pt-Pt, Zircaloy 2 (Zr-2)-Pt, Inconel (X-750)-Pt, and Zr- 2-X-750. To determine the changes in the coolant water conductivity due to the presence of...of fuel cladding integrity during accident scenarios. The limitation on acceptance criteria, in accordance with 10 CFR 50.46(b) is that the maximum

  13. Corrosion behavior of Ni-Base alloys in a hot lithium molten salt under an oxidizing atmosphere

    NASA Astrophysics Data System (ADS)

    Cho, Soo-Haeng; Cho, Il-Je; You, Gil-Sung; Yoon, Ji-Sup; Park, Seong-Won

    2007-08-01

    The electrolytic reduction of a spent oxide fuel involves the liberation of the oxygen in molten LiCl electrolyte, which is a chemically aggressive environment that is excessively corrosive for typical structural materials. Accordingly, it is essential to choose the optimum material for the processing equipment that handles the molten salt. In this study, the corrosion behaviors of Haynes 263, Haynes 75, Inconel 718 and Inconel X-750 in a molten LiCl-Li2O salt under an oxidizing atmosphere were investigated at 650°C for 72 to 216 hrs. The Haynes 263 alloy showed the best corrosion resistance among the examined alloys. The corrosion products of Haynes 263 were Li(Ni,Co)O2 and LiTiO2; those of Haynes 75 were Cr2O3, NiFe2O4, LiNiO2 and Li2FiFe2O4; while Cr2O3, NiFe2O4 and CrNbO4 were identified as the corrosion products of Inconel 718. Inconel X-750 produced Cr2O3, NiFe2O4 and (Cr, Nb, Ti)O2 as its corrosion products. Haynes 263 showed a localized corrosion behavior while Haynes 75, Inconel 718 and Inconel X-750 showed a uniform corrosion behavior.

  14. 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.

  15. 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.

  16. Creep crack growth behavior of several structural alloys

    NASA Astrophysics Data System (ADS)

    Sadananda, K.; Shahinian, P.

    1983-07-01

    Creep crack growth behavior of several high temperature alloys, Inconel 600, Inconel 625, Inconel X-750, Hastelloy X, Nimonic PE-16, Incoloy 800, and Haynes 25 (HS-25) was examined at 540, 650, 760, and 870 °C. Crack growth rates were analyzed in terms of both linear elastic stress intensity factor and J*-integral parameter. Among the alloys Inconel 600 and Hastelloy X did not show any observable crack growth. Instead, they deformed at a rapid rate resulting in severe blunting of the crack tip. The other alloys, Inconel 625, Inconel X-750, Incoloy 800, HS-25, and PE-16 showed crack growth at one or two temperatures and deformed continuously at other temperatures. Crack growth rates of the above alloys in terms ofJ* parameter were compared with the growth rates of other alloys published in the literature. Alloys such as Inconel X-750, Alloy 718, and IN-100 show very high growth rates as a result of their sensitivity to an air environment. Based on detailed fracture surface analysis, it is proposed that creep crack growth occurs by the nucleation and growth of wedge-type cracks at triple point junctions due to grain boundary sliding or by the formation and growth of cavities at the boundaries. Crack growth in the above alloys occurs only in some critical range of strain rates or temperatures. Since the service conditions for these alloys usually fall within this critical range, knowledge and understanding of creep crack growth behavior of the structural alloys are important.

  17. Effect of Stress Relief Annealing on Microstructure & Mechanical Properties of Welded Joints Between Low Alloy Carbon Steel and Stainless Steel

    NASA Astrophysics Data System (ADS)

    Nivas, R.; Das, G.; Das, S. K.; Mahato, B.; Kumar, S.; Sivaprasad, K.; Singh, P. K.; Ghosh, M.

    2017-01-01

    Two types of welded joints were prepared using low alloy carbon steel and austenitic stainless steel as base materials. In one variety, buttering material and weld metal were Inconel 82. In another type, buttering material and weld metal were Inconel 182. In case of Inconel 82, method of welding was GTAW. For Inconel 182, welding was done by SMAW technique. For one set of each joints after buttering, stress relief annealing was done at 923 K (650 °C) for 90 minutes before further joining with weld metal. Microstructural investigation and sub-size in situ tensile testing in scanning electron microscope were carried out for buttered-welded and buttered-stress relieved-welded specimens. Adjacent to fusion boundary, heat-affected zone of low alloy steel consisted of ferrite-pearlite phase combination. Immediately after fusion boundary in low alloy steel side, there was increase in matrix grain size. Same trend was observed in the region of austenitic stainless steel that was close to fusion boundary between weld metal-stainless steel. Close to interface between low alloy steel-buttering material, the region contained martensite, Type-I boundary and Type-II boundary. Peak hardness was obtained close to fusion boundary between low alloy steel and buttering material. In this respect, a minimum hardness was observed within buttering material. The peak hardness was shifted toward buttering material after stress relief annealing. During tensile testing no deformation occurred within low alloy steel and failure was completely through buttering material. Crack initiated near fusion boundary between low alloy steel-buttering material for welded specimens and the same shifted away from fusion boundary for stress relieved annealed specimens. This observation was at par with the characteristics of microhardness profile. In as welded condition, joints fabricated with Inconel 82 exhibited superior bond strength than the weld produced with Inconel 182. Stress relief annealing

  18. 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.

  19. Microstructural characterization of dissimilar welds between alloy 800 and HP heat-resistant steel

    SciTech Connect

    Dehmolaei, R.; Shamanian, M. Kermanpur, A.

    2008-10-15

    In this study, dissimilar welds between HP heat-resistant steel and Incoloy 800 were made with four different filler materials including: 309 stainless steel and nickel-based Inconel 82, 182 and 617. The microstructure of the base metals, weld metals and their interfaces were characterized by utilizing optical and scanning electron microscopy. Grain boundaries migration in the weld metals was studied. It was found that the migration of grain boundaries in the Inconel 82 weld metal was very extensive. Precipitates of TiC and M{sub 23}C{sub 6} (M = Cr and Mo) in the Inconel 617 weld metal are identified. The necessary conditions for the formation of cracks close to the fusion line of the 309-HP joints are described. Furthermore unmixed zone near the fusion line between HP steel base metal and Inconel 82 weld metal is discussed. An epitaxial growth is characterized at the fusion line of the 309-Alloy 800 and Inconel 617-Alloy 800 joints.

  20. Nonlinear effects in new magnetic pickup coils for JET

    SciTech Connect

    Quercia, A.; Pomaro, N.; Visone, C.

    2006-10-15

    In the framework of the JET magnetic diagnostic enhancement, a set of pickup coils (UC subsystem) wound on metallic Inconel registered 600 former was manufactured. For cross-validation purposes, two different calibration methods were used. A discrepancy in the range of 3% was observed, which can be explained when considering the dependence of the calibration coefficients on the field strength, which in turn is mostly due to the nonlinear behavior of the Inconel former. For this reason a specimen of Inconel was analyzed by means of a magnetometer, which showed a nonlinear and hysteretic behavior occurring at low field level (below 5 mT). The calibration coefficients are also measured at low field (0.1-2 mT) and so are affected by such peculiar ferromagnetic behavior. Moreover, the ferromagnetic behavior might be sensitive to mechanical and thermal treatments performed during probe manufacturing and testing. Therefore the achievable accuracy for the calibration of coils wound on Inconel formers is limited by the following effects: (i) the field level in operation can be completely different from the field used in the calibration procedure; (ii) measurements of the magnetic properties on Inconel specimens cannot be extrapolated to the former, because of unpredictable effects of mechanical and thermal treatments made on the coil; (iii) residual magnetization; and (iv) temperature variations during operation.

  1. 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.

  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. Direct growth of aligned carbon nanotubes on bulk metals.

    PubMed

    Talapatra, S; Kar, S; Pal, S K; Vajtai, R; Ci, L; Victor, P; Shaijumon, M M; Kaur, S; Nalamasu, O; Ajayan, P M

    2006-11-01

    There are several advantages of growing carbon nanotubes (CNTs) directly on bulk metals, for example in the formation of robust CNT-metal contacts during growth. Usually, aligned CNTs are grown either by using thin catalyst layers predeposited on substrates or through vapour-phase catalyst delivery. The latter method, although flexible, is unsuitable for growing CNTs directly on metallic substrates. Here we report on the growth of aligned multiwalled CNTs on a metallic alloy, Inconel 600 (Inconel), using vapour-phase catalyst delivery. The CNTs are well anchored to the substrate and show excellent electrical contact with it. These CNT-metal structures were then used to fabricate double-layer capacitors and field-emitter devices, which demonstrated improved performance over previously designed CNT structures. Inconel coatings can also be used to grow CNTs on other metallic substrates. This finding overcomes the substrate limitation for nanotube growth which should assist the development of future CNT-related technologies.

  4. Passivation oxide controlled selective carbon nanotube growth on metal substrates.

    PubMed

    Bult, J B; Sawyer, W G; Ajayan, P M; Schadler, L S

    2009-02-25

    Vertically aligned arrays of multi-wall carbon nanotubes (MWNT) are grown on Inconel 600, a nickel-based super-alloy. Using x-ray photoelectron spectroscopy (XPS) and chemical vapor deposition (CVD) growth of the MWNTs it is shown that a stable oxidation barrier is required for the stabilization of iron on the substrate and subsequent nanotube growth. This evidence for passivation oxide supported growth of MWNTs was then used to grow MWNTs on patterned oxidized substrates in a selective growth furnace. The unique advantage of this patterned growth on Inconel 600 is found to be the chromia passivation layer's electrical conductivity (measured value of 1.08 micro Omega m), creating the opportunity for low resistivity electrodes made from nanotubes. Inconel substrates with 100 microm long aligned MWNTs are demonstrated to exhibit an average resistance value of 2 Omega.

  5. Diffusion between glass and metals for optical fiber preform extrusion

    NASA Astrophysics Data System (ADS)

    Yeo, Felicia Yan Xin; Zhang, Zhifeng; Kumar Chakkathara Janardhanan Nair, Dileep; Zhang, Yilei

    2015-07-01

    When silica is extruded, diffusion of metal atoms into silica results contamination to the silica being heated, and thus is a serious concern for the glass extrusion process, such as extrusion of glass fiber preform. This paper examines diffusion between fused silica and two high strength metals, the stainless steel SS410 and the superalloy Inconel 718, at 1000 °C and under the normal atmosphere condition by SEM and Electron Dispersion Spectrum. It is found that diffusion occurs between silica and SS410, and at the same time, SS410 is severely oxidized during diffusion experiment. On the contrary, the diffusion between Inconel 718 and silica is unnoticeable, suggesting excellent high temperature performance of Inconel 718 for glass extrusion.

  6. 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.

  7. Detector response in a CANDU low void reactivity core

    SciTech Connect

    Tsang, K. T.

    2006-07-01

    The response of the in-core flux detectors to the CANFLEX Low-Void-Reactivity Fuel (LVRF) [1] bundles for use in the CANDU reactor at Bruce nuclear generation station has been studied. The study was based on 2 detector types - platinum (Pt)-clad Inconel and pure Inconel detectors, and 2 fuel types - LVRF bundles and natural-uranium (NU) bundles. Both detectors show a decrease of thermal-neutron-flux to total-photon-flux ratio when NU fuel bundles are replaced by LVRF bundles in the reactor core (7% for Inconel and 9% for Pt-clad detectors). The ratio of the prompt component of the net electron current to the total net electron current (PFe) of the detectors however shows a different response. The use of LVRF bundles in place of NU fuel bundles in the reactor core did not change the PFe of the Pt-clad Inconel detector but increased the PFe of the pure Inconel detector by less than 2%. The study shows that the Inconel detector has a larger prompt-detector response than that of the platinum-clad detector; it reacts to the change of fluxes in the reactor core more readily. On the other hand, the Pt-clad detector is less sensitive to perturbations of the neutron-to-gamma ratio. Nevertheless the changes in an absolute sense are minimal; one does not anticipate a change of the flux-monitoring system if the NU fuel bundles are replaced with the CANFLEX LVRF bundles in the core of the Bruce nuclear generating station. (authors)

  8. 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.

  9. Energy Analysis of n-Dodecane Combustion in a Hetero/Homogeneous Heat-Recirculating Microreactor for Portable Power Applications

    NASA Astrophysics Data System (ADS)

    Waits, C. M.; Tolmachoff, E. D.; Allmon, W. R.; Zecher-Freeman, N. E.

    2016-11-01

    An energy analysis is presented for n-dodecane/air combustion in a heat recirculating Inconel microreactor under vacuum conditions. Microreactor channels are partially coated with platinum enabling operating with coupled heterogeneous and homogeneous reactions. The radiant efficiency, important for thermophotovoltaic energy conversion, was found to decrease from 57% to 52% over 5 different runs covering 377 min of operation. A similar decrease in combustion efficiency was observed with 6%-8% energy lost to incomplete combustion and 5%- 6% lost through sensible heat in the exhaust. The remaining thermal loss is from unusable radiation and conduction through inlet and outlet tubing. Changes in the Inconel microreactor geometry and emissivity properties were observed.

  10. Sonic Infrared (IR) Imaging and Fluorescent Penetrant Inspection Probability of Detection (POD) Comparison

    SciTech Connect

    DiMambro, J.; Ashbaugh, D. M.; Nelson, C. L.; Spencer, F. W.

    2007-03-21

    Sandia National Laboratories Airworthiness Assurance Nondestructive Inspection Validation Center (AANC) implemented two crack probability of detection (POD) experiments to compare in a quantitative manner the ability of Sonic Infrared (IR) Imaging and fluorescent penetrant inspection (FPI) to reliably detect cracks. Blind Sonic IR and FPI inspections were performed on titanium and Inconel registered specimens having statistically relevant flaw profiles. Inspector hit/miss data was collected and POD curves for each technique were generated and compared. In addition, the crack lengths for a number of titanium and Inconel registered reference standards were measured before and after repeated Sonic IR inspections to determine if crack growth occurred.

  11. Determination of emissivity coefficient of heat-resistant super alloys and cemented carbide

    NASA Astrophysics Data System (ADS)

    Kieruj, Piotr; Przestacki, Damian; Chwalczuk, Tadeusz

    2016-12-01

    This paper presents the analysis of emissivity engineering materials according to temperature. Experiment is concerned on difficult to machine materials, which may be turned with laser assisting. Cylindrical samples made of nickel-based alloys Inconel 625, Inconel 718, Waspaloy and tungsten-carbides based on cobalt matrix were analyzed. The samples' temperature in contact method was compared to the temperature measured by non-contact pyrometers. Based on this relative, the value of the emissivity coefficient was adjusted to the right indication of pyrometers.

  12. Introducer needles of peripheral intravenous catheters: assessment of magnetic field interactions with 1.5T and 3T MR systems.

    PubMed

    Sakai, Mio; Aoki, Shigeki; Watanabe, Yasushi; Tanabe, Daisaku; Taga, Takashi; Inoue, Yusuke; Ohtomo, Kuni; Nakamura, Hironobu

    2009-01-01

    We developed a peripheral intravenous catheter introducer that can be used safely in the magnetic resonance (MR) environment, including that at 3.0-tesla. We evaluated introducers with stainless steel (SUS 316L) and nickel-chromium-based (inconel 600) needles as well as a 20-gauge peripheral intravenous catheter introducer with SUS 304 needle for MR safety. From an MR safety standpoint, the SUS 304 should not be selected, and though inconel 600 is the preferred material, the SUS 316L introducer may be more practical with some modifications.

  13. Metal elution from Ni- and Fe-based alloy reactors under hydrothermal conditions.

    PubMed

    Faisal, Muhammad; Quitain, Armando T; Urano, Shin-Ya; Daimon, Hiroyuki; Fujie, Koichi

    2004-05-20

    Elution of metals from Ni- and Fe-based alloy (i.e. Inconel 625 and SUS 316) under hydrothermal conditions was investigated. Results showed that metals could be eluted even in a short contact time. At subcritical conditions, a significant amount of Cr was extracted from SUS 316, while only traces of Ni, Fe, Mo, and Mn were eluted. In contrast, Ni was removed in significant amounts compared to Cr when Inconel 625 was tested. Several factors including temperature and contact time were found to affect elution behavior. The presence of air in the fluid even promoted elution under subcritical conditions.

  14. Thin micropatterned multi-walled carbon nanotube films for electrodes

    NASA Astrophysics Data System (ADS)

    Halonen, Niina; Mäklin, Jani; Rautio, Anne-Riikka; Kukkola, Jarmo; Uusimäki, Antti; Toth, Geza; Reddy, Leela Mohana; Vajtai, Robert; Ajayan, Pulickel M.; Kordas, Krisztian

    2013-09-01

    Micropatterned electrodes based on thin multi-walled carbon nanotube films are grown by catalytic chemical vapour deposition on lithographically defined quartz and Inconel alloy substrates. The electrical contact at the interface between the root of the nanotube arrays and the thin Ti hardmask layer on the quartz surface is found to be poor disabling proper capacitive characteristics. On the other hand, nanotube-Inconel electrodes show low series resistance and good electric double layer capacitor operation close to that of ideal devices. Patterning of the electrodes enhances both specific capacitance and power in reference to non-patterned bulk carbon nanotube film electrodes.

  15. Hydrogen embrittlement of cathodically protected subsea bolting alloys

    SciTech Connect

    Wolfe, L.H.; Burnette, C.C.; Joosten, M.W. )

    1993-07-01

    Normal operations of cathodic protection (CP) systems caused hydrogen embrittlement failures of subsea bolts made of Monel K-500 alloy (UNS N05500) on offshore platforms. Subsequent testing showed that the embrittlement could be predicted from cathodically protected slow strain rate tensile tests. Additional slow strain rate tests have shown that CP caused embrittlement of Ferralium 255 (S32550), Inconel X-750 (N07750), Inconel 718 (N07718), high strength steel, and 13% chromium alloys. Beryllium copper (C17200), A-286 steel (S66286), Beta-C titanium (R58640), and steel at a yield strength of 793 MPa (115 ksi) were not embrittled under the same conditions.

  16. 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.

  17. Replacement for Cadmium Plating and Hexavalent Chromium on Fasteners and Electrical Connectors

    DTIC Science & Technology

    2010-02-10

    hexavalent chromium] where they can perform adequately for the intended application and operating environment.” • 29 CFR 1910.1200 – Asbestos, beryllium...Chromium stainless steel 11–30% Cr (passive) • Inconel (passive) (80Ni-13Cr-7Fe) • Nickel (passive) • Silver solder • Monel (70Ni-30Cu) • Cupronickels...60–90Cu, 40-10Ni) • Bronzes (Cu-Sn) • Copper • Brasses (Cu-Zn) • Inconel (active) • Nickel (active) • Tin • Lead • Lead-tin solders • 18-8Mo stainless

  18. Promoted combustion of nine structural metals in high-pressure gaseous oxygen - A comparison of ranking methods

    NASA Technical Reports Server (NTRS)

    Steinberg, Theodore A.; Rucker, Michelle A.; Beeson, Harold D.

    1989-01-01

    The 316, 321, 440C, and 17-4 PH stainless steels, as well as Inconel 600, Inconel 718, Waspaloy, Monel 400, and Al 2219, have been evaluated for relative nonflammability in a high-pressure oxygen environment with a view to the comparative advantages of four different flammability-ranking methods. The effects of changes in test pressure, sample diameter, promoter type, and sample configuration on ranking method results are evaluated; ranking methods employing velocity as the primary ranking criterion are limited by diameter effects, while those which use extinguishing pressure are nonselective for metals with similar flammabilities.

  19. Some Quantitative Aspects of Fatigue of Materials

    DTIC Science & Technology

    1960-07-01

    189 72 S-N Curves for Inconel X-550 Alloy . ........... & • &90 73 17000F S-N Curves for Inconel 713C at Zero Steady Stress and at Zero...0. . . . . 9 III Heat Resistant Alloys .. . . . . . . . . , , . . . . . . . . . 0 3,1 General . .. 3.2 Discussion of Data’ inable V 0...0 0 . 1 . . . . . .10 IV Alunminum Alloys * . o & v e . 0 0 0 . 0 e 0 . 14 *.. 4.2 Discussion ofiaaianýTiablesoVlto*Xi . . . 14 4.2.1 Aluminum Alloy

  20. The Use of Austenitic Stainless Steel versus Monel (Ni-Cu) Alloy in Pressurized Gaseous Oxygen (GOX) Life Support Systems.

    DTIC Science & Technology

    1985-03-01

    micron 2219 Aluminum particles as the projectiles. Monel proved superior as Porter was unable to ignite Monel, but was able to icnite AISI 304L CRES with...800 micron 2219 Aluminum particles in the high velocity test appratus (see Figure 3.10). 2. Friction Tribology has been studied as a method of...Monel 400 Copper 102 Aluminum 6061- T6 1015 Carbon Steel Inconel 600 Hastelloy X Inconel718 440C Stainless Steel 17-4 PH Stainless Steel Invar 36 Brass 360

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. LINER FOR EXTRUSION BILLET CONTAINERS

    DTIC Science & Technology

    Rokide-process alumina and zirconia coatings and a Udimet 700 superalloy liner were evaluated by extrusion of 3 1/2-in. billets of Inconel 713C...One coating did with stand extrusion at 3450 F without apparent wear. The Udimet 700 liner did not show wear at 2000 F, but did react with the TZM

  7. The Influence of Temperature and Composition on the Activation Energy for Creep in Binary Aluminum Lithium Alloys

    DTIC Science & Technology

    1990-12-01

    thermocouples. Special self aligning grips, manufactured with Inconel Alloy 625, were designed to hold the creep specimens (Figure 4). These grips were made...manually ground to 600 grit and polished with 1 Am diamond paste. The samples were subsequently electropolished and etched using a 20 modified Barker’s

  8. Electron Channeling: A Problem for X-Ray Microanalysis in Materials Science

    DTIC Science & Technology

    2008-05-01

    polish or electropolish – it is expected that little or no plastic deformation will remain resident near the specimen surface to fowl the electron...mentioning that the authors have observed results of the same magnitude in Cu and Inconel 600, though the data has been omitted here (< 5 % variation in x

  9. Electropolishing qualification program for PWR steam generator divider plates

    SciTech Connect

    Spalaris, C.N. )

    1990-09-01

    A program was conducted to establish electropolishing parameters for Inconel 600 plate and Inco 182 weld metal. Test parameters were chosen so as to define margins in the principal process variables, as a prerequisite for applying electropolishing to reactor components. The test program and evaluation of the results obtained are included in this report. 12 refs., 35 figs., 5 tabs.

  10. An Experimental Investigation of Chemically-Reacting, Gas-Phase Turbulent Jets

    DTIC Science & Technology

    1991-04-12

    57.8 cm (22.75 in.) length of Pt-10%Rh wire welded to a pair of 356 pm (0.014 in.) diameter by 5cm (2 in.) long inconel prongs. Platinum was chosen...tank was nitric acid pickled, the F 2 mixing vessels were electropolished , and the NO mixing vessels were clear anodized prior to installation. Before

  11. A comparative evaluation of welding consumables for dissimilar weids between 316LN austenitic stainless steel and Alloy 800

    NASA Astrophysics Data System (ADS)

    Sireesha, M.; Albert, Shaju K.; Shankar, V.; Sundaresan, S.

    2000-03-01

    Transition joints in power plants between ferritic steels and austenitic stainless steels suffer from a mismatch in coefficients of thermal expansion (CTE) and the migration of carbon during service from the ferritic to the austenitic steel. To overcome these, nickel-based consumables are commonly used. The use of a trimetallic combination with an insert piece of intermediate CTE provides for a more effective lowering of thermal stresses. The current work envisages a trimetallic joint involving modified 9Cr-1Mo steel and 316LN austenitic stainless steel as the base materials and Alloy 800 as the intermediate piece. Of the two joints involved, this paper describes the choice of welding consumables for the joint between Alloy 800 and 316LN. Four consumables were examined: 316, 16-8-2, Inconel 82 and Inconel 182. The comparative evaluation was based on hot cracking tests and estimation of mechanical properties and coefficient of thermal expansion. While 16-8-2 exhibited highest resistance to solidification cracking, the Inconel filler materials also showed adequate resistance; additionally, the latter were superior from the mechanical property and coefficient of thermal expansion view-points. It is therefore concluded that for the joint between Alloy 800 and 316LN the Inconel filler materials offer the best compromise.

  12. 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.

  13. Development of Forced Pulse Water Strip of HVOF Coatings and Chrome Plating on Aircraft, Landing Gear, Engine and Propeller Components

    DTIC Science & Technology

    2009-09-01

    FRC-East and Southeast: Focus is Engine Inconel 718 substrates HVOF coatings are Cr-C and T-800 Agenda & Project Overview Objective Benefits...Status Boeing Test Booth Design Contact Information Questions Initial Parameter Development has been started for Cr-C and T-800 coated INC 718 flat

  14. 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.

  15. Welding And Cutting A Nickel Alloy By Laser

    NASA Technical Reports Server (NTRS)

    Banas, C. M.

    1990-01-01

    Technique effective and energy-efficient. Report describes evaluation of laser welding and cutting of Inconel(R) 718. Notes that electron-beam welding processes developed for In-718, but difficult to use on large or complex structures. Cutting of In-718 by laser fast and produces only narrow kerf. Cut edge requires dressing, to endure fatigue.

  16. Heat-barrier coatings for combustion chambers

    NASA Technical Reports Server (NTRS)

    Carpenter, H. W.

    1970-01-01

    Arc-plasma-sprayed layered coating of graded Inconel and zirconia protects film-coolant ring below injector plate of rocket engine combustion chamber. Interfacial temperature is designed for minimum buildup of stress and to avoid melting of the metal phase in the graded layers.

  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. Test and Evaluation of Four Fire Resistant Booms at OHMSETT

    DTIC Science & Technology

    1999-08-01

    steel Proprietary Stainless steel Resistant Material information (SS) woven blend of Inconel® and Fiberfrax ® Tension Member 3/8" Galvanized Stainless...material ( Fiberfrax ) which was severely damaged during the bum tests. In terms of percentages, and relative to baseline loss speeds, The first wave

  19. Thermal Analysis System (DSC, TGA, TMA) for Oxidation and Phase Transformation Studies of Alloys with Mestable Phase

    DTIC Science & Technology

    1988-06-01

    Hf on Inconel 718 for Improved High Temperature Oxidation Resistance," High Temp. Technology Vol. 5, No. 3, pp. 131-136, August, 1987. 2. S. Sircar, C...and (b)). (c) The shift in the Nb-Ti (Nb rich end) phase diagram is being determined now via DTA techniques. (Fig. 2). (d) The y’ dissolution

  20. Dynamic, Hot Surface Ignition of Aircraft Fuels and Hydraulic Fluids

    DTIC Science & Technology

    1980-10-01

    alloys involved the formation of surface catalysts in the form of oxides of the parent metal, iron, nickel, and chromium , on the heated surfaces. Some...stainless steels and inconel X, the formed oxides or spinels (e.g. (FeO) 0 . 2 5 (Cr 2 03 ) 1 . 7 5 ) were quite stable and while protecting the heated

  1. 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.

  2. 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.

  3. Environmental Considerations for Municipal Waste Combustors

    DTIC Science & Technology

    1994-07-01

    Existing MWC Regulations The USEPA has promulgated regulations that affect both new and existing MWCs with a capac over 250 tons per day (40 CFR 60). The...Scrubbing media Water Caustic Solution pH < 1-2 6.5-9 Materials of Construction High-ailoy steel (e.g., Inconel , Fiberglass reinforced plastic. Lined

  4. Kerosene Base Fuels in Small Gasoline Engines

    DTIC Science & Technology

    1991-01-01

    DIA. 4330 .354IA GAG 4. .235 DIA. INCONEL 601 SHEATHED ELEMENT DW 3AwL CTCCKYPE NO. !2 GWk I / 5-12- 82 CHAMPION SPARK PLUG COMPANY ’ 2-20-84 T OLEDO...1982) that emissions and specific fuel consumption certain piston designs in a CFR (Cooperative Fuel at part-load; 3600 RI, 3.5 bar SEP. Research

  5. 75 FR 9580 - Marine Mammals and Endangered Species; File Nos. 13544 and 14586

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-03

    ..., importing, and exporting of endangered and threatened species (50 CFR 222-226).Permit No. 13544 authorizes..., weighed, and tagged with Inconel and passive integrated transponder tags. Tissue samples are collected for....), the regulations governing the taking and importing of marine mammals (50 CFR part 216), the...

  6. Low Noise Catalytic Ignition I.C. Engine.

    DTIC Science & Technology

    1987-01-01

    prototype was built using Inconel fasteners. These have proven durable at the engine’s operating temperatures. However, fastener clearance problems in the... CFR engine in which the piston crown had been coated with platinum. The durability of this coating was low but it was reported that the presence of

  7. 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).

  8. 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.

  9. In-Space Rapid Manufacturing

    NASA Technical Reports Server (NTRS)

    Cooper, Kenneth G.

    1998-01-01

    In-space manufacturing objectives are: (1) Develop and demonstrate capability to directly fabricate components in space using rapid prototyping technology - ceramics (alumina, silicon nitride, zirconia), metallics (stainless, inconel, etc.), high strength/temperature plastics (PEEK). and ABS plastics (starting point). (2) Perform material science experiments on rapid prototyping candidate materials in microgravity.

  10. IRON PHOSPHATE GLASSES: AN ALTERNATIVE FOR VITRIFYING CERTAIN NUCLEAR WASTES

    SciTech Connect

    Day, Delbert E.; Kim, Cheol-Woon

    2004-06-28

    The unusual properties and beneficial 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), have been investigated by the University of Missouri-Rolla with support from the Environmental Management Science Program (EMSP), DOE [DEFG07- 96ER45618]. During the past year, the corrosion resistance of Inconel 690 and 693 coupons submerged in an iron phosphate melt at 1050 C for up to 155 days has been investigated to determine whether iron phosphate glasses could be melted in a Joule Heated Melter (JHM) equipped with such electrodes in the same manner as now being used to melt borosilicate glass. Substituting iron phosphate glasses for borosilicate glasses could significantly reduce the time and cost for clean up due to the higher waste loading possible in iron phosphate glass. The iron phosphate melt, which contained 30 wt% of the Hanford Low Activity Waste (LAW), did not corrode the Inconel 690 to any greater extent than what has been reported for Inconel 690 electrodes in the borosilicate melt in the JHM at the Defense Waste Processing Facility. Furthermore, Inconel 693 appeared to be an even better candidate for use in iron phosphate melts since its corrosion rate (0.7 {micro}m/day) was only about one half that (1.3 {micro}m/day) of Inconel 690. In the past year, the results of the research on iron phosphate glasses have been described in nine technical papers and one report and have been presented at four international and national meetings.

  11. 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.

  12. Swelling of several commercial alloys following high fluence neutron irradiation

    NASA Astrophysics Data System (ADS)

    Powell, R. W.; Peterson, D. T.; Zimmerschied, M. K.; Bates, J. F.

    Swelling values have been determined for a set of commercial alloys irradiated to a peak fluence of 1.8 × 10 23 n/cm 2 (E >0.1 MeV) over the temperature range of 400 to 650°C. The alloys studied fall into three classes: the ferritic alloys AISI 430F, AISI 416, EM-12, H-11 and 2 {1}/{4}Cr-1Mo; the superalloys Inconel 718 and Inconel X-750; and the refractory alloys TZM and Nb-1Zr. All of these 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.

  13. 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.

  14. Fracture Mechanics Evaluation of B-1 Materials. Volume I. Text

    DTIC Science & Technology

    1976-10-01

    8.2.14 Weldments In Ti-6AI-4V, 9-4,.20 and PH13 -8Mo 8 -314 8.2.15 Comparison of All Aluminum Alloys 8 -359 8.2.16 Comparison of Steels and Inconel 718 8 ...Inconel 718 8 -299 tbru 8.2.13.7-3 8 -313 8.2.14.1.1-1 t•nru Comparison FCGR Curves on Weldments in 8 -319 thru 8.2.14.3.9-1 Ti-6A1-4V, PH13 -8Mo and 9-4...investigated. In addition, the fracture properties of welds in Ti-6A1-4V, PH13 -8Mo, and 9-4-.20 alloys and of diffusion bonds in Ti-6AI-hV were determined

  15. Examination of DWPF Melter Materials After 8 Years of Service

    SciTech Connect

    Imrich, K.

    2003-04-29

    The first Defense Waste Processing Facility high level radioactive waste glass melter was successfully operated for eight years. Recent failure of melter heaters and decrease in glass production necessitated its removal. Prior to removing the melter from the facility, a remote in situ visual inspection of the refractory and Inconel(TM) 690 components was performed. The vapor space and glass contact refractory blocks were in excellent condition, showing little evidence of spalling or corrosion. Inconel 690 top head components and lid heaters in the vapor space were also in good condition, considering the service. Upper electrodes experienced significant deflection, which probably resulted from extended operation in excess of 1150 degrees C. Condition of the melter components examined during the remote visual inspection is summarized in this paper.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  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. 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.

  3. 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.

  4. 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)

  5. Milliwatt generator heat source. Progress report, July-December 1981

    SciTech Connect

    Mershad, E.A.

    1982-04-08

    As part of the Milliwatt Generator (MWG) Program, a second series of pressure burst capsules welded offsite was tested; the resulting data indicate that the welds are very similar to those in the first series of capsules. Sufficient hardware was fabricated to meet all scheduled commitments. To provide a unit for feasibility testing, a heat source clad with Hastelloy C was reclad with Inconel 600. Forming development tests on Inconel 600 were conducted with favorable results. A QAS-3 survey was conducted and a satisfactory rating was received. Lot 11 qualification began on T-111 materials. The production period ended with an overall process yield of 99.6%, and a dollar percent defective rate of 0.60%.

  6. 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.

  7. Vapor deposited emittance/catalysis coatings for superalloys in heatshield applications

    NASA Technical Reports Server (NTRS)

    Clark, R. K.; Cunnington, G. R., Jr.; Robinson, J. C.

    1985-01-01

    Statically oxidized Inconel 617 and MA 956 superalloys were prepared with vapor deposited aluminosilicate layers and exposed to temperatures which simulated reentry conditions. The aluminosilicate layers were 1-2 microns thick. The trials consisted of exposures to 1500-2300 F heat while surface temperatures were monitored with pyrometers. Analyses were then performed of the catalytic activity, oxidation phenomena, and radiative properties after thermal cycling the specimens for 8 hr. Both alloys were found to be catalytic to the recombination processes of dissociated species in the reentry environment. The coatings reduced the catalytic activity by 40 percent for both alloys but did not change the emittance. An enhanced Cr depletion zone was detected in the Inconel samples, implying that the coating did not prevent diffusion loss of Cr. The coated MA 956, on the other hand, gained weight over the course of the trials.

  8. Development of a high temperature ceramic-to-metal seal for Air Force Weapons Laboratory Laser

    NASA Astrophysics Data System (ADS)

    Honnell, R. E.; Stoddard, S. D.

    1987-03-01

    Procedures were developed for fabricating vacuum tight metal-to-ceramic ring seals between Inconel 625 and MgO-3 wt % Y2O3 tubes metallized with a calcia-alumina-silica glass (CaO-29 wt % Al2O3-35 wt % SiO2) containing 50 vol % molybdenum filler. Palniro No. 1 (Au-25 wt % Pd-25 wt % Ni) was found to be the most reliable braze for joining Inconel to metallized MgO-3 wt % Y2O3 bodies. The reliabilities of the processing procedures and the material systems were demonstrated. A prototype electrical feedthrough was fabricated for 1173 K operation in air or vacuum.

  9. 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.

  10. 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.

  11. A dislocation density based constitutive model for cyclic deformation

    SciTech Connect

    Estrin, Y.; Braasch, H.; Brechet, Y.

    1996-10-01

    A new constitutive model describing material response to cyclic loading is presented. The model includes dislocation densities as internal variables characterizing the microstructural state of the material. In the formulation of the constitutive equations, the dislocation density evolution resulting from interactions between dislocations in channel-like dislocation patterns is considered. The capabilities of the model are demonstrated for INCONEL 738 LC and Alloy 800H.

  12. The role of grain boundaries in hydrogen diffusion in metals at 25 C

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1993-01-01

    The effect of grain size on hydrogen diffusion at 25 C was examined for 4340 steel (body-centered cubic) and for Inconel 718 (face-centered cubic). It was found that the effect of grain size is important for body-centered cubic structures, but plays a much less important role in face centered cubic structures. Accurate measurements of hydrogen desorption coefficients during hydrogen desorption show that these are not greatly different for both types of structures.

  13. 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.

  14. Fabrication and installation of the DIII-D radiative divertor structures

    SciTech Connect

    Hollerbach, M.A.; Smith, J.P.

    1997-11-01

    Phase 1A of the Radiative Divertor Program (RDP) is now installed in the DIII-D tokamak located at General Atomics. This hardware was added to enhance both the Divertor and Advanced Tokamak research elements of the DIII-D program. This installation consists of a divertor baffle enveloping a cryocondensation pump at the upper outer divertor target of DIII-D. The divertor baffle consists of two toroidally continuous Inconel 625 water-cooled rings and a toroidal array of discontinuous radiatively-cooled plates. The water-cooled rings are each comprised of four quadrants, mechanically formed, chem.-milled, and resistance and TIG welded Inconel 625 panels. The supports attaching the panels to the vessel wall are designed to accommodate the differential thermal expansion between the rings and vessel during bake and to react the electromagnetic loads induced during disruptions. They are made from either Inconel 625 or Inconel 718 depending on the stress levels predicted in Finite Element Analysis. Gas seals are designed to limit the leakage from the baffle chamber back to the core plasma to 2,500 {ell}/s and incorporate plasma sprayed alumina to minimize currents flowing through them. The bulk of the water-cooled ring fabrication was performed by a vendor, however, the final machining of penetrations in the conical ring for diagnostic access was performed in-house using a unique machining configuration. This configuration, and the machining of the diagnostic cutouts is described. Graphite tiles were machined from ATJ graphite to form a smooth plasma-facing surface. The installation of all divertor components required only four weeks.

  15. 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.

  16. Fabrication and Prototype Testing of a Strain-Tolerant Bi-2212 Cable

    NASA Astrophysics Data System (ADS)

    McIntyre, Peter; Soika, Rainer; Yavuz, Mustafa; Liang, Gan; Motowidlo, Leshek

    2000-10-01

    We have successfully manufactured and tested prototypes of a mechanically stabilized Bi2Sr2Ca1Cu2Ox (Bi-2212) 6-on-1 cable-in-conduit (CIC). The superconducting wire in the cable is reinforced with Inconel X-750 tubes to provide improved strain tolerance and greater ease of handling. We are providing a detailed description of the manufacturing process. We have wound test coils from the cable, and we are reporting on the preliminary testing of the coils.

  17. 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.

  18. Surface passivity largely governs the bioaccessibility of nickel-based powder particles at human exposure conditions.

    PubMed

    Hedberg, Yolanda S; Herting, Gunilla; Latvala, Siiri; Elihn, Karine; Karlsson, Hanna L; Odnevall Wallinder, Inger

    2016-11-01

    The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, are identified and proven safe for humans and the environment. Therefore, differences in bioaccessibility in terms of released metals in synthetic biological fluids (different pH (1.5-7.4) and composition) that are relevant for different human exposure routes (inhalation, ingestion, and dermal contact) have been assessed for powder particles of an alloy containing high levels of nickel (Inconel 718, 57 wt% nickel). This powder is compared with the bioaccessibility of two nickel-containing stainless steel powders (AISI 316L, 10-12% nickel) and with powders representing their main pure alloy constituents: two nickel metal powders (100% nickel), two iron metal powders and two chromium metal powders. X-ray photoelectron spectroscopy, microscopy, light scattering, and nitrogen absorption were employed for the particle and surface oxide characterization. Atomic absorption spectroscopy was used to quantify released amounts of metals in solution. Cytotoxicity (Alamar blue assay) and DNA damage (comet assay) of the Inconel powder were assessed following exposure of the human lung cell line A549, as well as its ability to generate reactive oxygen species (DCFH-DA assay). Despite its high nickel content, the Inconel alloy powder did not release any significant amounts of metals and did not induce any toxic response. It is concluded, that this is related to the high surface passivity of the Inconel powder governed by its chromium-rich surface oxide. Read-across from the pure metal constituents is hence not recommended either for this or any other passive alloy.

  19. 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.

  20. The Effects of Yttrium Additions on Void Swelling in Liquid Metal Fast Breeder Reactor Candidate Cladding Alloys.

    DTIC Science & Technology

    1981-04-28

    This is in close agreement with helium production rates found in like alloys (i.e., 316SS, PE-16, INCONEL -600) exposed to the EBR-II environment for...slight electropolish to remove the last little bit of cold work left by the Linde B compound, thus providing a smoother surface. This suggestion was...tried on these alloys and resulted in unsatisfactory surfaces. The electropolishing consisted of removing 2-3 Pm of surface material by a 10 sec polish