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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. Strain energy density-distance criterion for the initiation of stress corrosion cracking of alloy X-750

    SciTech Connect

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

    1996-05-01

    A strain energy density-distance criterion was previously developed and used to correlate rising-load K{sub c} initiation data for notched and fatigue precracked specimens of hydrogen precharged Alloy X-750. This criterion, which was developed for hydrogen embrittlement (HE) cracking, is used here to correlate static-load stress corrosion cracking (SCC) initiation times obtained for smooth geometry, notched and fatigue precracked specimens. The onset of SCC crack growth is hypothesized to occur when a critical strain, which is due to environment-enhanced creep, is attained within the specimen interior. For notched and precracked specimens, initiation is shown by analysis to occur at a variable distance from notch and crack tips. The initiation site varies from very near the crack tip, for highly loaded sharp cracks, to a site that is one grain diameter from the notch, for lower loaded, blunt notches. The existence of hydrogen gradients, which are due to strain-induced hydrogen trapping in the strain fields of notch and crack tips, is argued to be controlling the site for initiation of cracking. By considering the sources of the hydrogen, these observations are shown to be consistent with those from the previous HE study, in which the characteristic distance for crack initiation was found to be one grain diameter from the notch tip, independent of notch radius, applied stress intensity factor and hydrogen level.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

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

    SciTech Connect

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

    1991-12-31

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

  4. Materials data handbook: Inconel alloy 718

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    A summary of the materials property information for Inconel alloy 718 is presented. The scope of the information includes physical and mechanical properties at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and joining techniques is developed.

  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. Some aspects of inelastic behavior of high temperature alloys -- Inconel 700 and Inconel 713

    SciTech Connect

    Anselmo, E.R.; French, M.; Jones, D.I.G.

    1995-12-31

    The Renewal Theory of Inelasticity is used to describe the behavior of high temperature alloys Inconel 700 and Inconel 713C. Renewal Creep Theory is used to model the primary and secondary behavior of these alloys. The numerical parameters extracted from the creep model are then used with the Renewal Theory of Inelasticity to predict stress-strain behaviors of the alloys. Comparisons between theory,and experimental results support the utility of the general form of Renewal Theory. This work also serves as a tutorial on applying renewal theory to an engineering material.

  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. Laser cladding of Inconel 690 on Inconel 600 superalloy for corrosion protection in nuclear applications

    NASA Astrophysics Data System (ADS)

    Baldridge, T.; Poling, G.; Foroozmehr, E.; Kovacevic, R.; Metz, T.; Kadekar, V.; Gupta, M. C.

    2013-02-01

    In the nuclear industry there is need for repair of heat exchanger tubes made of high-temperature corrosion-resistant Inconel metals. This work reports the results of applying a 3 mm thick cladding layer by laser melting Inconel 690 powder on top of a 10 mm thick plate of Inconel 600 alloy substrate. Successful multilayer cladding of 3 mm thickness was achieved by scanning the laser beam over the substrate using a powder feeder to control the powder feed rate. Experimental parameters such as laser power, scanning speed, beam overlap, powder feed rate, and preheating were investigated to reduce cracking upon cooling. SEM images show a smooth integral interface between the 600 and 690 materials, and EDS mapping reveals the dilution zone via the concentration gradient of chromium. Vickers tests show the 690 cladding surface to be up to 40% harder than the base 600 material. XRD and EDS analysis confirm that the Inconel 690 composition remains unchanged throughout processing when using argon as a shielding gas. The final laser melted cladding layer appears to be well-suited for surface protection.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Theory and Apparatus for Measurement of Emissivity for Radiative Cooling of Hypersonic Aircraft with Data for Inconel and Inconel X

    NASA Technical Reports Server (NTRS)

    O'Sullivan, William J , Jr; Wade, William R

    1957-01-01

    The importance of radiation as a means of cooling high-supersonic- and hypersonic-speed aircraft is discussed to show the need for measurements of the total hemispherical emissivity of surfaces. The theory underlying the measurement of the total hemispherical emissivity of surfaces is presented, readily duplicable apparatus for performing the measurements is described, and measurements for stably oxidized Inconel and Inconel X are given for the temperature range from 600 F to 2,000 F.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  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. 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.

  11. 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.

  12. 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.

  13. 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.

  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. Growth and characterization of nanocrystalline zirconium nitride-inconel structures

    NASA Astrophysics Data System (ADS)

    Aouadi, S. M.; Maeruf, T.; Sodergren, M.; Mihut, D. M.; Rohde, S. L.; Xu, J.; Mishra, S. R.

    2005-07-01

    This paper reports on the investigation of the physical, chemical, optical, mechanical, and tribological properties of reactively sputtered zirconium nitride-inconel composite nanocrystalline mixture films. These films were co-sputtered from a Zr and an inconel targets onto Si (111) substrates at room temperature using a fixed power to the Zr target (PZr) and a fixed flow of nitrogen and argon. Two sets of samples were produced by (1) varying the power to the inconel target (Pinc) and using a fixed bias voltage Vb and (2) by varying Vb and keeping Pinc fixed. The elemental composition was deduced from x-ray photoelectron spectroscopy, and was found to be influenced by Pinc and Vb. X-ray diffraction revealed the presence of nanocrystals of ZrN with a pattern typical of the NaCl structure. The grain size was found to decrease with the increase in ``inconel'' content in the film. The optical constants were measured using spectroscopic ellipsometry and were subsequently simulated using a Drude-Lorentz model. A correlation between film structure-composition and optical constants was established. The hardness and elastic modulus of each sample were measured by nanoindentation. The hardest films were produced using a Vb=-130 V bias voltage and Pinc=4 W. Microwear measurements were carried out using positive constant normal loads and the wear tracks were imaged and processed. The measured values for the friction coefficients, residual depth of tip indentations, wear volumes, and surface roughness were reported. The lowest recorded wear volume using a load of 4 mN was 10-3 μm. Finally, the coatings were worn against ball-bearing steel using a ball-on-disk tribotester. Characterization of the wear tracks were performed by profilometry. A low wear coefficient of 1.7×10-7 mm3/s was obtained for a load of 5 N.

  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. 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).

  1. 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).

  2. 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.

  3. 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.

  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. Selective laser melting of Inconel super alloy-a review

    NASA Astrophysics Data System (ADS)

    Karia, M. C.; Popat, M. A.; Sangani, K. B.

    2017-07-01

    Additive manufacturing is a relatively young technology that uses the principle of layer by layer addition of material in solid, liquid or powder form to develop a component or product. The quality of additive manufactured part is one of the challenges to be addressed. Researchers are continuously working at various levels of additive manufacturing technologies. One of the significant powder bed processes for met als is Selective Laser Melting (SLM). Laser based processes are finding more attention of researchers and industrial world. The potential of this technique is yet to be fully explored. Due to very high strength and creep resistance Inconel is extensively used nickel based super alloy for manufacturing components for aerospace, automobile and nuclear industries. Due to law content of Aluminum and Titanium, it exhibits good fabricability too. Therefore the alloy is ideally suitable for selective laser melting to manufacture intricate components with high strength requirements. The selection of suitable process for manufacturing for a specific component depends on geometrical complexity, production quantity, and cost and required strength. There are numerous researchers working on various aspects like metallurgical and micro structural investigations and mechanical properties, geometrical accuracy, effects of process parameters and its optimization and mathematical modeling etc. The present paper represents a comprehensive overview of selective laser melting process for Inconel group of alloys.

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Corrosion behavior of Inconel 690 and 693 in an iron phosphate melt

    NASA Astrophysics Data System (ADS)

    Zhu, Dongmei; Kim, Cheol-Woon; Day, Delbert E.

    2005-01-01

    The corrosion resistance of Inconel 690 and 693 coupons submerged in an iron phosphate melt has been investigated. After 155 days in an iron phosphate melt at 1050 °C, which contained 30 wt% of a simulated low activity waste (LAW at Hanford), the weight loss of Inconel 690 and 693 was 14% and 8%, respectively. The overall corrosion rate, calculated from the initial and final dimensions of each coupon, was 1.3 and 0.7 μm/day for the Inconel 690 and 693, respectively. Scanning electron microscopy and X-ray diffraction of the submerged Inconel coupons after 155 days in the iron phosphate melt showed that an altered surface layer had formed which was depleted in nickel and consisted of a (Fe, Cr) 2O 3 solid solution. This altered layer appears to be chemically protective as indicated by the gradual reduction in weight loss which occurred with time in the iron phosphate melt. Inconel 693 appears to be a better candidate to use as an electrode in iron phosphate melts since its corrosion rate and weight loss was only about one half that of Inconel 690.

  2. 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

  3. 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

  4. Galvanic Corrosion Behavior of Microwave Welded and Post-weld Heat-Treated Inconel-718 Joints

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

    In the present study, corrosion behavior of microwave welded Inconel-718 at various conditions was investigated. Welding of Inconel-718 in 980 °C solution-treated condition was performed using microwave hybrid heating technique. The microwave welds were subjected to post-heat treatment for improving its microstructure and mechanical properties by solubilizing the Nb-enriched Laves phase. The microstructural features of the fabricated welds at various conditions were investigated through scanning electron microscopy. The electrochemical testing results revealed that Inconel-718 welds were galvanic corroded when they were anodically polarized in 3.5 wt.% NaCl solution at 28 °C. The difference in the corrosion potentials between the base metal (BM) and fusion zone (FZ) in an Inconel-718 weld was the main factor for galvanic corrosion. The highest corrosion was occurred in the as-welded/aged weldments, followed by 980 °C solution-treated and aged weldments, as-welded specimen, and 1080 °C solution-treated and aged (1080STA) weldments. The least galvanic corrosion was occurred in the 1080STA specimens due to almost uniform microstructure developed in the weldment after the treatment. Thus, it was possible to minimize the galvanic corrosion in the microwave welded Inconel-718 by 1080STA treatment which resulted in reducing the difference in corrosion potentials between the BM and the FZ.

  5. Mechanical properties of nanostructured nickel based superalloy Inconel 718

    NASA Astrophysics Data System (ADS)

    Mukhtarov, Sh; Ermachenko, A.

    2010-07-01

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

  6. Temperature Measurement and Numerical Prediction in Machining Inconel 718

    PubMed Central

    Tapetado, Alberto; Vázquez, Carmen; Miguélez, Henar

    2017-01-01

    Thermal issues are critical when machining Ni-based superalloy components designed for high temperature applications. The low thermal conductivity and extreme strain hardening of this family of materials results in elevated temperatures around the cutting area. This elevated temperature could lead to machining-induced damage such as phase changes and residual stresses, resulting in reduced service life of the component. Measurement of temperature during machining is crucial in order to control the cutting process, avoiding workpiece damage. On the other hand, the development of predictive tools based on numerical models helps in the definition of machining processes and the obtainment of difficult to measure parameters such as the penetration of the heated layer. However, the validation of numerical models strongly depends on the accurate measurement of physical parameters such as temperature, ensuring the calibration of the model. This paper focuses on the measurement and prediction of temperature during the machining of Ni-based superalloys. The temperature sensor was based on a fiber-optic two-color pyrometer developed for localized temperature measurements in turning of Inconel 718. The sensor is capable of measuring temperature in the range of 250 to 1200 °C. Temperature evolution is recorded in a lathe at different feed rates and cutting speeds. Measurements were used to calibrate a simplified numerical model for prediction of temperature fields during turning. PMID:28665312

  7. Temperature Measurement and Numerical Prediction in Machining Inconel 718.

    PubMed

    Díaz-Álvarez, José; Tapetado, Alberto; Vázquez, Carmen; Miguélez, Henar

    2017-06-30

    Thermal issues are critical when machining Ni-based superalloy components designed for high temperature applications. The low thermal conductivity and extreme strain hardening of this family of materials results in elevated temperatures around the cutting area. This elevated temperature could lead to machining-induced damage such as phase changes and residual stresses, resulting in reduced service life of the component. Measurement of temperature during machining is crucial in order to control the cutting process, avoiding workpiece damage. On the other hand, the development of predictive tools based on numerical models helps in the definition of machining processes and the obtainment of difficult to measure parameters such as the penetration of the heated layer. However, the validation of numerical models strongly depends on the accurate measurement of physical parameters such as temperature, ensuring the calibration of the model. This paper focuses on the measurement and prediction of temperature during the machining of Ni-based superalloys. The temperature sensor was based on a fiber-optic two-color pyrometer developed for localized temperature measurements in turning of Inconel 718. The sensor is capable of measuring temperature in the range of 250 to 1200 °C. Temperature evolution is recorded in a lathe at different feed rates and cutting speeds. Measurements were used to calibrate a simplified numerical model for prediction of temperature fields during turning.

  8. 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.

  9. 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.

  10. 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.

  11. [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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

    NASA Astrophysics Data System (ADS)

    Rodriguez, David; Merwin, Augustus; Karmiol, Zachary; Chidambaram, Dev

    2017-05-01

    Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325 °C and supercritical water at 425 °C and 527.5 °C for 2 h was studied. After exposure to 325 °C subcritical water, the CrO42- based film formed; however minor quantities of NiFexCr2-xO4 spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425 °C consisted of NiFexCr2-xO4 spinel. The surface films on both alloys were identified as NiFe2O4 when exposed to supercritical water at 527.5 °C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600 °C. Samples were exposed to these temperatures for 24, 96, and 200 h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

  6. Modeling of precipitation strengthening in Inconel 718 including non-spherical γ″ precipitates

    NASA Astrophysics Data System (ADS)

    Ahmadi, M. R.; Rath, M.; Povoden-Karadeniz, E.; Primig, S.; Wojcik, T.; Danninger, A.; Stockinger, M.; Kozeschnik, E.

    2017-07-01

    In this study, the classical strengthening equations for weak and strong particles are advanced to account for oblate-shaped γ″ precipitates in Inconel 718. The model is verified on quantitative stereology of size and distribution for both shearable and non-shearable mechanisms. The evolution of precipitation strengthening of aged superalloy Inconel 718 is simulated. In addition to precipitation strengthening, contributions of solid solution strengthening and the grain size effect are considered. Simulation results indicate a sound prediction of the final yield strength based on the presented model.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Experimental and numerical heat transfer studies on quenching of Inconel 600 probe

    NASA Astrophysics Data System (ADS)

    Ramesh, G.; Narayan Prabhu, K.

    2015-01-01

    The effect of heat transfer coefficient and quench start temperature on cooling behaviour of Inconel 600 quench probe was assessed by numerical experiments. A quantitative model that relates the mean cooling rate and quench start temperature of the probe with the boundary heat transfer coefficient was proposed. Computed aided cooling curve analysis was carried out by heating Inconel 600 probe to temperatures varying from 100 to 850 °C followed by quenching in water. The results of quenching experiments and the data available in the literature were used to validate the proposed model. A good agreement between the measured and estimated value was observed. The results showed that the film and transition boiling of cooling stages were significantly influenced by quench start temperature of the material while nucleate boiling and convective cooling stages were strongly dependent on the boundary heat transfer coefficient.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Process Capability of High Speed Micro End-Milling of Inconel 718 with Minimum Quantity Lubrication

    NASA Astrophysics Data System (ADS)

    Rahman, Mohamed Abd; Yeakub Ali, Mohammad; Rahman Shah Rosli, Abdul; Banu, Asfana

    2017-03-01

    The demand for micro-parts is expected to grow and micro-machining has been shown to be a viable manufacturing process to produce these products. These micro-products may be produced from hard-to-machine materials such as superalloys under little or no metal cutting fluids to reduce machining cost or drawbacks associated with health and environment. This project aims to investigate the capability of micro end-milling process of Inconel 718 with minimum quantity lubrication (MQL). Microtools DT-110 multi-process micro machine was used to machine 10 micro-channels with MQL and 10 more under dry condition while maintaining the same machining parameters. The width of the micro-channels was measured using digital microscope and used to determine the process capability indices, Cp and Cpk. QI Macros SPC for Excel was used to analyze the resultant machining data. The results indicated that micro end-milling process of Inconel 718 was not capable under both MQL and dry cutting conditions as indicated by the Cp values of less than 1.0. However, the use of MQL helped the process to be more stable and capable. Results obtained showed that the process variation was greatly reduced by using MQL in micro end-milling of Inconel 718.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  3. 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%.

  4. Laser cladding of Inconel 625-based composite coatings reinforced by porous chromium carbide particles

    NASA Astrophysics Data System (ADS)

    Janicki, Damian

    2017-09-01

    Inconel 625/Cr3C2 composite coatings were produced via a laser cladding process using Cr3C2 reinforcing particles presenting an open porosity of about 60%. A laser cladding system used consisted of a direct diode laser with a rectangular beam spot and the top-hat beam profile, and an off-axis powder injection nozzle. The microstructural characteristics of the coatings was investigated with the use of scanning electron microscopy and X-ray diffraction. A complete infiltration of the porous structure of Cr3C2 reinforcing particles and low degree of their dissolution have been achieved in a very narrow range of processing parameters. Crack-free composite coatings having a uniform distribution of the Cr3C2 particles and their fraction up to 36 vol% were produced. Comparative erosion tests between the Inconel 625/Cr3C2 composite coatings and the metallic Inconel 625 coatings were performed following the ASTM G 76 standard test method. It was found that the composite coatings have a significantly higher erosion resistance to that of metallic coatings for both 30° and 90° impingement angles. Additionally, the erosion performances of composite coatings were similar for both the normal and oblique impact conditions. The erosive wear behaviour of composite coatings is discussed and related to the unique microstructure of these coatings.

  5. 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

  6. 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.

  7. 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

  8. Microstructure and deformation behavior of nickel based superalloy Inconel 740 prepared by electron beam smelting

    SciTech Connect

    Tan, Yi You, Xiaogang; You, Qifan; Li, Jiayan; Shi, Shuang; Li, Pengting

    2016-04-15

    Electron beam smelting (EBS) has been used to fabricate the Inconel 740 superalloy. Microstructures, hardness, and deformation characteristics of the alloy are studied. It is observed that carbides and fine secondary phase nuclei are distributed in the hot worked EBS 740 superalloy. The Ostwald ripening occurs during solution treatment and leads to aggregation of the γ′ precipitates, the size of γ′ precipitates varies from several nanometers to more than one hundred nanometers as a result. The average size of the secondary phase is < 30 nm after aging treatment and the average Vickers hardness is measured to be about 370. The critical shear stress is calculated to be 0.627 GPa with governing mechanism of shearing, causing a stronger strengthening effect than the traditionally prepared Inconel 740 superalloy. The compression behavior indicates that the EBS 740 superalloy shows higher flow stress than 740H at low Zener-Hollomon parameter, which may arise from the undissolved γ′ precipitates and higher activation energy Q. The tensile results show that the fracture surface exhibits a ductile fracture pattern, in contrast to no obvious plastic deformation on the macroscopic fracture. Crack propagation proceeds in a transgranular fracture mode with facets and voids presented on the fracture surface. - Graphical abstract: Electron beam smelting (EBS) has been used to fabricate the Inconel 740 superalloy. Microstructures, hardness, and deformation characteristics of the alloy are studied. The average size of the secondary phase is < 30 nm after aging treatment and the average Vickers hardness is measured to be about 370. The critical shear stress is calculated to be 0.627 GPa with governing mechanism of shearing, causing a stronger strengthening effect than the traditionally prepared Inconel 740 superalloy. The EBS 740 superalloy shows higher flow stress than 740H at low Zener-Hollomon parameter, which may arise from the undissolved γ′ precipitates and higher

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. Creep-Fatigue Cracking Near the Welded Interface in Friction Welding Dissimilar Superalloys INCONEL 718 and MAR-M247

    NASA Astrophysics Data System (ADS)

    Tra, Tran Hung; Okazaki, Masakazu

    2017-08-01

    A forged INCONEL 718 and a cast MAR-M247 alloy were joined by a friction welding process. The creep-fatigue strength of this joint was investigated. The life of the joint was significantly shorter than that of the base alloys. The joint failed near the interface of the INCONEL 718 side, although the life of INCONEL 718 was longer than that of MAR-M247. To understand this behavior, the stress field in the welding was numerically analyzed using a visco-elastic model. The results suggested that triaxiality in the stress state could be promoted near the welded interface and lead to an acceleration of creep-fatigue crack nucleation.

  14. 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

  15. 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.

  16. 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

  17. Industrial Process Design for Manufacturing Inconel 718 Extremely Large Forged Rings

    NASA Astrophysics Data System (ADS)

    Ambielli, John F.

    2011-12-01

    Inconel 718 is a Ni-Fe-based superalloy that has been central to the gas turbine industry since its discovery in 1963. While much more difficult to process than carbon or stainless steels, among its superalloy peers Inconel 718 has relatively high forgeability and has been used to make discs, rings, shells, and structural components. A metal forming process design algorithm is presented to incorporate key criteria relevant to superalloy processing. This algorithm was applied to conceptual forging and heat treating extremely large rings of Inconel 718 of diameter 1956 mm (77in) and weight 3252 kg (7155 lb). A 3-stage standard thermomechanical (TMP) processing was used, where Stage 1 strain varied from 0.1190 to 0.2941, Stage 2 from 0.0208 to 0.0357 and Stage 3 from 0.0440 to 0.0940. This was followed by heat treatment of a solution anneal (954°C/1750°F for 4 hour hold), air cool, then a double aging (718°C/1325°F for 8 hour hold; furnace cool to 621°C/1150°F 56°C/100°F per hr; 18 hour total time for both steps). Preliminary mechanical testing was performed. Average yield strength of 951 MPa/138 ksi (longitudinal) and 979 MPa/142 ksi (axial) was achieved. Tensile strengths were 1276 MPa/185 ksi (longitudinal) and 1255 MPa/182 ksi (axial). Elongations and reduction of areas attained were, respectively, 18 (long) and 25 (axial) and 28 (long) and 27 (axial).

  18. 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.

  19. 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.

  20. 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.

  1. Corrosion Resistance of Laser Clads of Inconel 625 and Metco 41C

    NASA Astrophysics Data System (ADS)

    Němeček, Stanislav; Fidler, Lukáš; Fišerová, Pavla

    The present paper explores the impact of laser cladding parameters on the corrosion behaviour of the resulting surface. Powders of Inconel 625 and austenitic Metco 41C steel were deposited on steel substrate. It was confirmed that the level of dilution has profound impact on the corrosion resistance and that dilution has to be minimized. However, the chemical composition of the cladding is altered even in the course of the cladding process, a fact which is related to the increase in the substrate temperature. The cladding process was optimized to achieve maximum corrosion resistance. The results were verified and validated using microscopic observation, chemical analysis and corrosion testing.

  2. 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

  3. Development of an inconel self powered neutron detector for in-core reactor monitoring

    NASA Astrophysics Data System (ADS)

    Alex, M.; Ghodgaonkar, M. D.

    2007-04-01

    The paper describes the development and testing of an Inconel600 (2 mm diameter×21 cm long) self-powered neutron detector for in-core neutron monitoring. The detector has 3.5 mm overall diameter and 22 cm length and is integrally coupled to a 12 m long mineral insulated cable. The performance of the detector was compared with cobalt and platinum detectors of similar dimensions. Gamma sensitivity measurements performed at the 60Co irradiation facility in 14 MR/h gamma field showed values of -4.4×10 -18 A/R/h/cm (-9.3×10 -24 A/ γ/cm 2-s/cm), -5.2×10 -18 A/R/h/cm (-1.133×10 -23 A/ γ/cm 2-s/cm) and 34×10 -18 A/R/h/cm (7.14×10 -23 A/ γ/cm 2-s/cm) for the Inconel, Co and Pt detectors, respectively. The detectors together with a miniature gamma ion chamber and fission chamber were tested in the in-core Apsara Swimming Pool type reactor. The ion chambers were used to estimate the neutron and gamma fields. With an effective neutron cross-section of 4b, the Inconel detector has a total sensitivity of 6×10 -23 A/nv/cm while the corresponding sensitivities for the platinum and cobalt detectors were 1.69×10 -22 and 2.64×10 -22 A/nv/cm. The linearity of the detector responses at power levels ranging from 100 to 200 kW was within ±5%. The response of the detectors to reactor scram showed that the prompt response of the Inconel detector was 0.95 while it was 0.7 and 0.95 for the platinum and cobalt self-powered detectors, respectively. The detector was also installed in the horizontal flux unit of 540 MW Pressurised Heavy Water Reactor (PHWR). The neutron flux at the detector location was calculated by Triveni code. The detector response was measured from 0.02% to 0.07% of full power and showed good correlation between power level and detector signals. Long-term tests and the dynamic response of the detector to shut down in PHWR are in progress.

  4. 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.

  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 micro-texture evolution during large strain deformation of Inconel alloy IN718

    SciTech Connect

    Nayan, Niraj; Gurao, N.P.; Narayana Murty, S.V.S.; Jha, Abhay K.; Pant, Bhanu; George, Koshy M.

    2015-12-15

    The hot deformation behaviour of Inconel alloy IN718 was studied in the temperature range of 950–1100 °C and at strain rates of 0.01 and 1 s{sup −1} with a view to understand the microstructural evolution as a function of strain rate and temperature. For this purpose, a single hit, hot isothermal plane strain compression (PSC) technique was used. The flow curves obtained during PSC exhibited weak flow softening at higher temperatures. Electron backscattered diffraction analysis (EBSD) of the PSC tested samples at the location of maximum strain revealed dynamic recrystallisation occurring at higher temperatures. Based on detailed microstructure and microtexture analyses, it was concluded that single step, large strain deformation has a distinct advantage in the thermo-mechanical processing of Inconel alloy IN718. - Highlights: • Plane strain compression (PSC) on IN718 was conducted. • Evolution of microstructure during large strain deformation was studied. • Flow curves exhibited weak softening at higher temperatures and dipping of the flow curve at a strain rate of 1 s{sup −1}. • Optimization of microstructure and process parameter for hot rolling possible by plane strain compression testing • Dynamic recrystallisation occurs in specimens deformed at higher temperatures and lower strain rates.

  7. Experimental Investigation Nano Particles Influence in NPMEDM to Machine Inconel 800 with Electrolyte Copper Electrode

    NASA Astrophysics Data System (ADS)

    Karunakaran, K.; Chandrasekaran, M.

    2017-05-01

    The recent technology of machining hard materials is Powder mix dielectric electrical Discharge Machining (PMEDM). This research investigates nano sized (about 5Nm) powders influence in machining Inconel 800 nickel based super alloy. This work is motivated for a practical need for a manufacturing industry, which processes various kinds of jobs of Inconel 800 material. The conventional EDM machining also considered for investigation for the measure of Nano powders performances. The aluminum, silicon and multi walled Carbon Nano tubes powders were considered in this investigation along with pulse on time, pulse of time and input current to analyze and optimize the responses of Material Removal Rate, Tool Wear Rate and surface roughness. The Taguchi general Full Factorial Design was used to design the experiments. The most advance equipments employed in conducting experiments and measuring equipments to improve the accuracy of the result. The MWCNT powder mix was out performs than other powders which reduce 22% to 50% of the tool wear rate, gives the surface roughness reduction from 29.62% to 41.64% and improved MRR 42.91% to 53.51% than conventional EDM.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  9. Effect of Thermal Annealing on Machining-Induced Residual Stresses in Inconel 718

    NASA Astrophysics Data System (ADS)

    Madariaga, A.; Aperribay, J.; Arrazola, P. J.; Esnaola, J. A.; Hormaetxe, E.; Garay, A.; Ostolaza, K.

    2017-08-01

    Nickel-based alloys are widely employed in the manufacturing of aero-engines. These alloys are difficult to machine, and tensile residual stresses are generated during machining. These tensile residual stresses can negatively affect the performance of aero-engine components. Nevertheless, residual stresses can vary due to thermal or mechanical loading. These variations must be considered to evaluate the real influence of residual stresses on component behavior. This paper studies the effect of thermal loads on machining-induced residual stresses in the alloy Inconel 718. A ring-shaped Inconel 718 part was face-turned, and specimens were extracted from it. Specimens were exposed at 550 and 650 °C for 10 min, 1 and 10 h. Residual stresses were measured, and microstructure was observed before and after thermal exposure. Residual stress variations found after thermal exposure were the consequence of two factors: relaxation of strain bands during the early stage of exposure and diffusion-controlled creep. In addition, a modified Zener-Wert-Avrami model is proposed to predict residual stress relaxation caused by the diffusion-controlled creep. Once having fitted the modified Zener-Wert-Avrami model, the study was extended for a wider range of temperatures (400-650 °C). This analysis showed that surface residual stresses do not relax significantly at temperatures below 500 °C.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Preliminary investigation of heat transfer to water flowing in an electrically heated Inconel tube

    NASA Technical Reports Server (NTRS)

    Kaufman, Samuel J; Isely, Francis D

    1950-01-01

    A heat-transfer investigation was conducted with water flowing in an electrically heated Inconel tube with an inside diameter of 0.204 inch and a length-diameter ratio of 50 for ranges of Reynolds number up to 100,000 and of entrance pressure up to 200 inches of mercury gage. Correlation of average heat-transfer coefficients was obtained by use of the familiar Nusselt relation, wherein the physical properties of water were evaluated at an average bulk temperature. For conditions in which no boiling occurred, the data gave a good correlation. Runs made in the nucleate-boiling region, however, gave higher values of heat-transfer coefficient than would be predicted by the Nusselt relation.

  8. 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.

  9. 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.

  10. Investigation on edge joints of Inconel 625 sheets processed with laser welding

    NASA Astrophysics Data System (ADS)

    Caiazzo, F.; Alfieri, V.; Cardaropoli, F.; Sergi, V.

    2017-08-01

    Laser welding of Inconel 625 edge joint beads in square groove configuration was investigated. The use of different weld geometries in new aerospace solutions explains research on edge joints. A structured plan was carried out in order to characterize the process defining the influence of laser power and welding speed and to study possible interactions among the governing factors. As weld pool protection is crucial in order to obtain sound joints when processing superalloys, a special glove box for gas supply was designed to upgrade the welding head. Welded joints were characterized referring to bead profile, microstructure and X-rays. It was found that heat input plays an important role as it affects welding stability, porosity content and bead shape. Results suggest operating with low values of heat input to reduce porosity and guarantee stable bead conformation. Furthermore, a decrease in the grain size has been observed as a consequence of decreasing heat input.

  11. 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.

  12. 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.

  13. Thermal Effects on Microstructural Heterogeneity of Inconel 718 Materials Fabricated by Electron Beam Melting

    SciTech Connect

    Sames, William J.; Unocic, Kinga A.; Dehoff, Ryan R.; Lolla, Tapasvi; Babu, Sudarsanam Suresh

    2014-07-28

    Additive manufacturing (AM) technologies, also known as 3D printing, have demonstrated the potential to fabricate complex geometrical components, but the resulting microstructures and mechanical properties of these materials are not well understood due to unique and complex thermal cycles observed during processing. The electron beam melting (EBM) process is unique because the powder bed temperature can be elevated and maintained at temperatures over 1000 °C for the duration of the process. This results in three specific stages of microstructural phase evolution: (a) rapid cool down from the melting temperature to the process temperature, (b) extended hold at the process temperature, and (c) slow cool down to the room temperature. In this work, the mechanisms for reported microstructural differences in EBM are rationalized for Inconel 718 based on measured thermal cycles, preliminary thermal modeling, and computational thermodynamics models. The relationship between processing parameters, solidification microstructure, interdendritic segregation, and phase precipitation (δ, γ´, and γ´´) are discussed.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  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. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Microstructure and mechanical behavior of direct metal laser sintered Inconel alloy 718

    SciTech Connect

    Smith, Derek H.; Bicknell, Jonathan; Jorgensen, Luke; Patterson, Brian M.; Cordes, Nikolaus L.; Tsukrov, Igor; Knezevic, Marko

    2016-03-15

    In this paper, we investigate microstructure and quasi-static mechanical behavior of the direct metal laser sintered Inconel 718 superalloy as a function of build direction (BD). The printed material was further processed by annealing and double-aging, hot isostatic pressing (HIP), and machining. We characterize porosity fraction and distribution using micro X-ray computed tomography (μXCT), grain structure and crystallographic texture using electron backscattered diffraction (EBSD), and mechanical response in quasi-static tension and compression using standard mechanical testing at room temperature. Analysis of the μXCT imaging shows that majority of porosity develops in the outer layer of the printed material. However, porosity inside the material is also present. The EBSD measurements reveal formation of columnar grains, which favor < 001 > fiber texture components along the BD. These measurements also show evidence of coarse-grained microstructure present in the samples treated by HIP. Finally, analysis of grain boundaries reveal that HIP results in a large number of annealing twins compared to that in samples that underwent annealing and double-aging. The yield strength varies with the testing direction by approximately 7%, which is governed by a combination of grain morphology and crystallographic texture. In particular, we determine tension–compression asymmetry in the yield stress as well as anisotropy of the material flow during compression. We find that HIP lowers yield stress but improves ductility relative to the annealed and aged material. These results are discussed and critically compared with the data reported for wrought material in the same condition. - Highlights: • Microstructure and mechanical properties of DMLS Inconel 718 are studied in function of build direction. • Inhomogeneity of microstructure in the material in several conditions is quantified by μXCT and EBSD. • Anisotropy and asymmetry in the mechanical response are

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

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

    DOE PAGES

    Nandwana, Peeyush; Peter, William H.; Lowe, Larry E.; ...

    2015-10-20

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

  18. 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.

  19. 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.

  20. Optimization of Cutting Parameters for Surface Roughness under MQL, using Al2O3 Nanolubricant, during Turning of Inconel 718

    NASA Astrophysics Data System (ADS)

    Ali, M. A. M.; Khalil, A. N. M.; Azmi, A. I.; Salleh, H. M.

    2017-08-01

    Inconel 718 is a nickel-based alloy commonly used due to its excellent mechanical properties at high temperatures and its elevated corrosion resistance. This material however is difficult to machine due to the high temperature generated during machining, which requires efficient lubrication system. Minimum quantity lubrication (MQL) technique is a more efficient and a more environmentally friendly alternative to conventional flooding lubrication technique. The efficiency and efficacy of this lubrication technique can be further enhanced by adding nano particles and surfactant into the base lubricant. There are currently limited number of studies on the application of minimum quantity lubrication (MQL) technique using nanolubricant with added surfactant in the machining of hard-to-machine materials such as Inconel 718. Consequently, this paper aims to optimize the cutting parameters for surface roughness under minimum quantity lubrication (MQL) condition using surfactant-added Al2O3 nanolubricant during the turning of Inconel 718. The effects of cutting speed, depth of cut and feed rate and their two-way interactions on surface roughness are investigated on the basis of the standard Taguchi’s L9 orthogonal array (OA) design of experiment and the results are assessed using analysis of variance (ANOVA) and signal to noise (S/N) ratio methods to determine the optimal cutting parameter settings as well as the level of significance of the cutting parameters. The optimal surface finish can be observed at the cutting speed of 70 m/min, depth of cut of 0.05 mm and feed rate of 0.05 mm/rev with feed rate being the most significant factor to affect surface finish. Through this study, the application of minimum quantity lubrication (MQL) technique using surfactant-added Al2O3 nanolubricant, has been shown to produce desirable surface finish quality on Inconel 718 with additional economic and ecological benefits.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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. 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.

  10. 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).

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    SciTech Connect

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

    2015-11-20

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

  5. 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.

  6. 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.

  7. Effect of Heat Treatment Parameters on the Microstructure and Properties of Inconel-625 Superalloy

    NASA Astrophysics Data System (ADS)

    Sukumaran, Arjun; Gupta, R. K.; Anil Kumar, V.

    2017-07-01

    Inconel-625 is a solid solution-strengthened alloy used for long-duration applications at high temperatures and moderate stresses. Different heat treatment cycles (temperatures of 625-1025 °C and time of 2-6 h) have been studied to obtain optimum mechanical properties suitable for a specific application. It has been observed that room temperature strength and, hardness decreased and ductility increased with increase in heat treatment temperature. The rate of change of these properties is found to be moderate for the samples heat-treated up to 850 °C, and thereafter, it increases rapidly. It is attributed to the microstructural changes like dissolution of carbides, recrystallization and grain growth. Microstructures are found to be predominantly single-phase austenitic with the presence of fine alloy carbides. The presence of twins is observed in samples heat-treated at lower temperature, which act as nucleation sites for recrystallization at 775 °C. Beyond 850 °C, the role of carbides present in the matrix is subsided by the coarsening of recrystallized grains and finally at 1025 °C, significant dissolution of carbide results in substantial reduction in strength and increase in ductility. Elongation to an extent of >71% has been obtained in sample heat-treated at 1025 °C indicating excellent tendency for cold workability. Failure of heat-treated specimens is found to be mainly due to carbide particle-matrix decohesion which acts as locations for crack initiation.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.%.

  14. 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.

  15. 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.

  16. 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

    2017-04-01

    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.

  17. 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.

  18. 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.

  19. Computational modeling of residual stress formation during the electron beam melting process for Inconel 718

    SciTech Connect

    Prabhakar, P.; Sames, William J.; Dehoff, Ryan R.; Babu, Sudarsanam Suresh

    2015-03-28

    Here, a computational modeling approach to simulate residual stress formation during the electron beam melting (EBM) process within the additive manufacturing (AM) technologies for Inconel 718 is presented in this paper. The EBM process has demonstrated a high potential to fabricate components with complex geometries, but the resulting components are influenced by the thermal cycles observed during the manufacturing process. When processing nickel based superalloys, very high temperatures (approx. 1000 °C) are observed in the powder bed, base plate, and build. These high temperatures, when combined with substrate adherence, can result in warping of the base plate and affect the final component by causing defects. It is important to have an understanding of the thermo-mechanical response of the entire system, that is, its mechanical behavior towards thermal loading occurring during the EBM process prior to manufacturing a component. Therefore, computational models to predict the response of the system during the EBM process will aid in eliminating the undesired process conditions, a priori, in order to fabricate the optimum component. Such a comprehensive computational modeling approach is demonstrated to analyze warping of the base plate, stress and plastic strain accumulation within the material, and thermal cycles in the system during different stages of the EBM process.

  20. Computational modeling of residual stress formation during the electron beam melting process for Inconel 718

    DOE PAGES

    Prabhakar, P.; Sames, William J.; Dehoff, Ryan R.; ...

    2015-03-28

    Here, a computational modeling approach to simulate residual stress formation during the electron beam melting (EBM) process within the additive manufacturing (AM) technologies for Inconel 718 is presented in this paper. The EBM process has demonstrated a high potential to fabricate components with complex geometries, but the resulting components are influenced by the thermal cycles observed during the manufacturing process. When processing nickel based superalloys, very high temperatures (approx. 1000 °C) are observed in the powder bed, base plate, and build. These high temperatures, when combined with substrate adherence, can result in warping of the base plate and affect themore » final component by causing defects. It is important to have an understanding of the thermo-mechanical response of the entire system, that is, its mechanical behavior towards thermal loading occurring during the EBM process prior to manufacturing a component. Therefore, computational models to predict the response of the system during the EBM process will aid in eliminating the undesired process conditions, a priori, in order to fabricate the optimum component. Such a comprehensive computational modeling approach is demonstrated to analyze warping of the base plate, stress and plastic strain accumulation within the material, and thermal cycles in the system during different stages of the EBM process.« less

  1. 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.

  2. 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.

  3. Cold Spray Deposition of Freestanding Inconel Samples and Comparative Analysis with Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Bagherifard, Sara; Roscioli, Gianluca; Zuccoli, Maria Vittoria; Hadi, Mehdi; D'Elia, Gaetano; Demir, Ali Gökhan; Previtali, Barbara; Kondás, Ján; Guagliano, Mario

    2017-10-01

    Cold spray offers the possibility of obtaining almost zero-porosity buildups with no theoretical limit to the thickness. Moreover, cold spray can eliminate particle melting, evaporation, crystallization, grain growth, unwanted oxidation, undesirable phases and thermally induced tensile residual stresses. Such characteristics can boost its potential to be used as an additive manufacturing technique. Indeed, deposition via cold spray is recently finding its path toward fabrication of freeform components since it can address the common challenges of powder-bed additive manufacturing techniques including major size constraints, deposition rate limitations and high process temperature. Herein, we prepared nickel-based superalloy Inconel 718 samples with cold spray technique and compared them with similar samples fabricated by selective laser melting method. The samples fabricated using both methods were characterized in terms of mechanical strength, microstructural and porosity characteristics, Vickers microhardness and residual stresses distribution. Different heat treatment cycles were applied to the cold-sprayed samples in order to enhance their mechanical characteristics. The obtained data confirm that cold spray technique can be used as a complementary additive manufacturing method for fabrication of high-quality freestanding components where higher deposition rate, larger final size and lower fabrication temperatures are desired.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. The Effects of Borides on the Mechanical Properties of TLPB Repaired Inconel 738 Superalloy

    NASA Astrophysics Data System (ADS)

    Wei, J.; Ye, Y.; Sun, Z.; Zou, G.; Bai, H.; Wu, A.; Liu, L.

    2017-10-01

    The transient liquid phase diffusion bonding (TLPB) method was used to repair an artificial crack in Inconel 738, which was notched by a femtosecond laser. Mixed ratios of BNi-1a:DF-4B were investigated at the bonding temperature of 1373 K (1100 °C) for 2 to 36 hours. The effect of borides on the mechanical properties of TLPB repaired joints was studied through analysis of the microstructure, fracture path, and morphology observations. The borides formation, morphology, distribution, and joints strength were studied in detail. The results showed that the diffusion of B can either increase or decrease the joint strength, depending on its distribution and morphology. The amount of large blocky Ni-B compounds in the precipitate zone were reduced with increasing holding time, which resulted in an increase in joint strength. Nevertheless, further increasing the holding time led to a decrease in joint strength because of the formation of continuous acicular borides in the diffusion-affected zone. The fracture modes of TLPB joints were also discussed on the basis of the microstructure and fractography.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

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

    PubMed

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

    2004-01-01

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

  19. 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.

  20. Control of Inconel 738LC superalloy microstructure with the aid of a precipitate dissolution semi-analytical modeling

    NASA Astrophysics Data System (ADS)

    Danis, Yann; Arvieu, Corinne; Lacoste, Eric; Quenisset, Jean-Michel

    2010-12-01

    After experimental identification of the main factors influencing Inconel 738LC superalloy microstructures, a semi-analytical modeling of precipitate dissolution during thermal cycle has been proposed. It was based on an isokinetic model of phase transformation adapted to the presence of high-precipitate density as observed in γ' precipitate hardened IN738LC. Some data required as input for the semi-analytical modeling could be determined by an inverse method applied to isothermal treatments. Finally the semi-analytical modeling was validated through non-isothermal treatments and used to predict the occurrence of hot cracking depending on welding conditions.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    SciTech Connect

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

    1998-04-01

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

  10. 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

  11. 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.

  12. A study on blank optimization for blow forming of Inconel 718 to secure formability at high temperature

    NASA Astrophysics Data System (ADS)

    Yoo, Joon-Tae; Yoon, Jong-Hoon; Lee, Ho-Sung; Youn, Sung-Kie

    2013-12-01

    In this study, thickness profiled blank is designed using optimization technique to get high formability in blow forming of Inconel 718 by equivalent static loads method for non-linear static response structural optimization (ESLSO). When ESLSO is applied, optimization with wide design range is difficult because the effectiveness of equivalent static loads is not valid if there are wide changes in design values. To maximize the design range in ESLSO, move limit scheme is applied during non-linear iteration considering the effectiveness of equivalent static loads. Optimization results show increased formability within limited strain range and possibility of gas forming using non-SPF grade Inconel 718. Free bulging test using blank which has optimized profile is conducted to verify the optimization process. Result is compared with that of numerical analysis in bulged height, deformed shape and thickness and they show good agreement. Verified optimization process is applied to obtain profile of blank thickness for hemi-sphere forming and sandwich structure forming. In hemi-sphere forming, the maximum strain after forming is minimized. Flat blank could not be applied for hemi-sphere forming because of failure caused from local thinning. As a result of optimization, hemi-sphere could be formed without failure. In sandwich structure forming, blank is designed to minimize un-deformed area without failure. Its result shows that sandwich structure can be formed successfully using NON-SPF grade material.

  13. 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.

  14. X-ray photoelectron spectroscopy study of the passive films formed on thermally sprayed and wrought Inconel 625

    NASA Astrophysics Data System (ADS)

    Bakare, M. S.; Voisey, K. T.; Roe, M. J.; McCartney, D. G.

    2010-11-01

    There is a well known performance gap in corrosion resistance between thermally sprayed corrosion resistant coatings and the equivalent bulk materials. Interconnected porosity has an important and well known effect, however there are additional relevant microstructural effects. Previous work has shown that a compositional difference exists between the regions of resolidified and non-melted material that exist in the as-sprayed coatings. The resolidified regions are depleted in oxide forming elements due to formation of oxides during coating deposition. Formation of galvanic cells between these different regions is believed to decrease the corrosion resistance of the coating. In order to increase understanding of the details of this effect, this work uses X-ray photoelectron spectroscopy (XPS) to study the passive films formed on thermally sprayed coatings (HVOF) and bulk Inconel 625, a commercially available corrosion resistant Ni-Cr-Mo-Nb alloy. Passive films produced by potentiodynamic scanning to 400 mV in 0.5 M sulphuric acid were compared with air-formed films. The poorer corrosion performance of the thermally sprayed coatings was attributed to Ni(OH) 2, which forms a loose, non-adherent and therefore non-protective film. The good corrosion resistance of wrought Inconel 625 is due to formation of Cr, Mo and Nb oxides.

  15. Interdependence of character of grain boundaries, intergranular segregation of boron and grain boundary liquation in simulated weld heat-affected zone in Inconel 718

    SciTech Connect

    Guo, H.; Chaturvedi, M.C.; Richards, N.L.; McMahon, G.S.

    1999-01-08

    Intergranular microfissuring is frequently observed in the weld heat-affected zones (HAZ) in Inconel 718. Extensive studies of this phenomenon have established that the HAZ microfissuring in Inconel 718 is associated with the constitutional liquation of grain boundary (GB) precipitates of carbides, Laves and {delta} phases. In addition, HAZ microfissuring has been also attributed to the GB segregation of B and S. To differentiate between the influence of B from other factors, studies were initiated on Inconel 718 that was almost free of C, P, and S, and contained different concentrations of B. These studies have shown that B in Inconel 718 can segregate to the grain boundaries by a non-equilibrium mechanism during cooling from the pre-weld solution heat treatment temperature, which would lower the melting temperature of the GB material. If the segregation of B is sufficiently high, the GBs are likely to liquate in the HAZ during the heating component of the welding thermal cycle. The inability of the liquated GBs to support tensile stresses that develop during cooling of the welds would result in microfissuring in the HAZs. It was also observed that the GB liquation in the HAZs was heterogeneously distributed. That is, while a GB liquated others connected to it did not. Therefore, an investigation was initiated to determine the interdependence of segregation of B on GBs, their crystallographic character and liquation. The results are presented in this communication.

  16. 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

  17. Modification of wetting property of Inconel 718 surface by nanosecond laser texturing

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Tian, Y. L.; Yang, C. J.; Wang, F. J.; Liu, X. P.

    2017-08-01

    Topographic and wetting properties of Inconel 718 (IN718) surfaces were modified via nanosecond laser treatment. In order to investigate surface wetting behavior without additional post treatment, three kinds of microstructures were created on IN718 surfaces, including line pattern, grid pattern and spot pattern. From the viewpoint of surface morphology, the results show that laser ablated grooves and debris significantly altered the surface topography as well as surface roughness compared with the non-treated surfaces. The effects of laser parameters, such as laser scanning speed and laser power, on surface features were also discussed. We have observed the laser treated surfaces of IN718 showed very high hydrophilicity just after laser ablation under ambient air condition. And this hydrophilic property has changed rapidly to the other state, very high hydrophobicity over about 20 days. Further experiments and analysis have been carried out so as to investigate this phenomenon. Based on the XPS analysis, the results indicate that the change of wetting property from hydrophilic to hydrophobic over time may be due to the surface chemistry modifications, especially carbon content. After the contact angles reached steady state, the maximum water contact angle (WCA) for line-patterned and grid-patterned surfaces increased to 152.3 ± 1.2° and 156.8 ± 1.1° with the corresponding rolling angle (RA) of 8.8 ± 1.1° and 6.5 ± 0.8°, respectively. These treated IN718 surfaces exhibited superhydrophobic property. However, the maximum WCA for the spot-patterned surfaces just increased to 140.8 ± 2.8° with RA above 10°. Therefore, it is deduced that laser-inscribed modification of surface wettability has high sensitivity to surface morphology and surface chemical compositions. This work can be utilized to optimize the laser processing parameters so as to fabricate desired IN718 surfaces with hydrophobic or even superhydrophobic property and thus extend the applications

  18. 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.

  19. (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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Characterization and heat flux testing of beryllium coatings on Inconel for JET ITER-like wall project

    NASA Astrophysics Data System (ADS)

    Hirai, T.; Linke, J.; Sundelin, P.; Rubel, M.; Kühnlein, W.; Wessel, E.; Coad, J. P.; Lungu, C. P.; Matthews, G. F.; Pedrick, L.; Piazza, G.

    2007-03-01

    In order to perform a fully integrated material test, JET has launched the ITER-like wall project with the aim of installing a full metal wall during the next major shutdown. The material foreseen for the main chamber wall is bulk Be at the limiters and Be coatings on inconel tiles elsewhere. R&D process comprises global characterization (structure, purity etc) of the evaporated films and testing of their performance under heat loads. The major results are (i) the layers have survived energy loads of 20 MJ m-2 which is significantly above the required level of 5-10 MJ m-2, (ii) melting limit of beryllium coating would be at the energy level of 30 MJ m-2, (iii) cyclic thermal load of 10 MJ m-2 for up to 50 cycles have not induced any noticeable damage such as flaking or detachment.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Effects of γ' Precipitation, Dislocation Density, and Grain Size on Stress-Relaxation Properties of INCONEL X-750 Helical Springs

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

    INCONEL X-750 specimens were manufactured into helical springs by drawing and coiling followed by aging. They were subsequently subjected to stress-relaxation tests. Stress relaxation is the important property of springs that are compressed at elevated temperatures. To understand stress relaxation, this study investigated the effect of the drawing ratio (DR) on the γ' size and volume fraction, grain size, carbide volume fraction, and dislocation density. Small-angle neutron scattering was used to measure the size and volume fraction of γ' phase, and X-ray diffraction was employed to analyze the dislocation density in the springs as a function of the DR. The smallest DR specimen (DR0) had a longer free length than the larger DR specimens (DR17 and DR42) after the stress-relaxation test was completed at 773 K (500 °C) for 300 hours. However, the size and volume fraction of γ', along with the dislocation density, had no influence on the stress relaxation of the INCONEL X-750 springs. The decreased grain size ( d) due to an increase in the DR was the main factor in the increase in the stress relaxation of the springs. The decrease in grain size displayed a nonlinear relationship with the increase in stress relaxation. The stress-relaxation behavior relationship was d -3. Grain boundaries were determined to play a role in dislocation sink via transmission electron microscopy (TEM) observations. Grain boundary diffusion accommodated by slip was responsible for the stress-relaxation properties of the spring at an elevated temperature (773 K = 500 °C).

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  14. Structure-Property Relationships of Solid State Additive Manufactured Aluminum Alloy 2219 and Inconel 625

    NASA Astrophysics Data System (ADS)

    Rivera Almeyda, Oscar G.

    In this investigation, the processing-structure-property relations are correlated for solid state additively manufactured (SSAM) Inconel 625 (IN 625) and a SSAM aluminum alloy 2219 (AA2219). This is the first research of these materials processed by a new SSAM method called additive friction stir (AFS). The AFS process results in a refined grain structure by extruding solid rod through a rotating tool generating heat and severe plastic deformation. In the case of the AFS IN625, the IN625 alloy is known for exhibiting oxidation resistance and temperature mechanical stability, including strength and ductility. This study is the first to investigate the beneficial grain refinement and densification produced by AFS in IN625 that results in advantageous mechanical properties (YS, UTS, epsilonf) at both quasi-static and high strain rate. Electron Backscatter Diffraction (EBSD) observed dynamic recrystallization and grain refinement during the layer deposition in the AFS specimens, where the results identified fine equiaxed grain structures formed by dynamic recrystallization (DRX) with even finer grain structures forming at the layer interfaces. The EBSD quantified grains as fine as 0.27 microns in these interface regions while the average grain size was approximately 1 micron. Additionally, this is the first study to report on the strain rate dependence of AFS IN625 through quasi-static (QS) (0.001/s) and high strain rate (HR) (1500/s) tensile experiments using a servo hydraulic frame and a direct tension-Kolsky bar, respectively, which captured both yield and ultimate tensile strengths increasing as strain rate increased. Fractography performed on specimens showed a ductile fracture surface on both QS, and HR. Alternatively, the other AFS material system investigated in this study, AA2219, is mostly used for aerospace applications, specifically for rocket fuel tanks. EBSD was performed in the cross-section of the AA2219, also exhibiting DRX with equiaxed microstructure

  15. 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.

  16. 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.

  17. 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.

  18. TEM Observation of Martensite Layer at the Weld Interface of an A508III to Inconel 82 Dissimilar Metal Weld Joint

    NASA Astrophysics Data System (ADS)

    Chen, Z. R.; Lu, Y. H.

    2015-12-01

    A lenticular martensite layer at the weld interface in an A508III/Inconel 82 dissimilar metal weld (DMW) joint was studied by TEM. The martensite/weld metal boundary was observed as the fusion boundary. There was a K-S orientation relationship between martensite and weld metal. The formation of the martensite was mainly determined by the distribution of alloy elements. The martensite was responsible for the hardness peak in the DMW.

  19. Spatial Dependence of Heat Flux Transients and Wetting Behavior During Immersion Quenching of Inconel 600 Probe in Brine and Polymer Media

    NASA Astrophysics Data System (ADS)

    Ramesh, G.; Narayan Prabhu, K.

    2014-08-01

    Cooling curve analysis of Inconel 600 probe during immersion quenching in brine and polymer quench media was carried out. Thermal histories at various axial and radial locations were recorded using a high-speed data acquisition system and were input to an inverse heat-conduction model for estimating the metal/quenchant heat flux transients. A high performance smart camera was used for online video imaging of the immersion quenching process. Solution to two-dimensional inverse heat-conduction problem clearly brings out the spatial dependence of boundary heat flux transients for a Inconel 600 probe with a simple cylindrical geometry. The estimated heat flux transients show large variation on axial as well as radial directions of quench probe surface for brine quenching. Polymer quenching showed less variation in metal/quenchant heat flux transients. Shorter durations of vapor film, higher rewetting temperatures, and faster movement of wetting front on quench probe surface were observed with brine quenching. Measurement of dynamic contact angle showed better spreading and good wettability for polymer medium as compared to brine quenchant. The solid-liquid interfacial tension between polymer medium and Inconel substrate was lower compared with that of solution. Rewetting and boiling processes were nonuniform and faster on quench probe surface during immersion quenching in brine solution. For the polymer quench medium, slow rewetting, uniform boiling and repeated wetting were observed.

  20. Formation of the Ni3Nb δ-Phase in Stress-Relieved Inconel 625 Produced via Laser Powder-Bed Fusion Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Lass, Eric A.; Stoudt, Mark R.; Williams, Maureen E.; Katz, Michael B.; Levine, Lyle E.; Phan, Thien Q.; Gnaeupel-Herold, Thomas H.; Ng, Daniel S.

    2017-08-01

    The microstructural evolution of laser powder-bed additively manufactured Inconel 625 during a post-build stress-relief anneal of 1 hour at 1143 K (870 °C) is investigated. It is found that this industry-recommended heat treatment promotes the formation of a significant fraction of the orthorhombic D0a Ni3Nb δ-phase. This phase is known to have a deleterious influence on fracture toughness, ductility, and other mechanical properties in conventional, wrought Inconel 625; and is generally considered detrimental to materials' performance in service. The δ-phase platelets are found to precipitate within the inter-dendritic regions of the as-built solidification microstructure. These regions are enriched in solute elements, particularly Nb and Mo, due to the micro-segregation that occurs during solidification. The precipitation of δ-phase at 1073 K (800 °C) is found to require up to 4 hours. This indicates a potential alternative stress-relief processing window that mitigates δ-phase formation in this alloy. Ultimately, a homogenization heat treatment is recommended for additively manufactured Inconel 625 because the increased susceptibility to δ-phase precipitation increases the possibility for significant degradation of materials' properties in service.

  1. 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.

  2. 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.

  3. 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).

  4. 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.

  5. 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'.

  6. 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

  7. 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.

  8. 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.

  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. 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.

  13. Comparison between experimental and 2-D numerical studies of multiple scattering in Inconel600 by means of array probes.

    PubMed

    Shahjahan, S; Rupin, F; Aubry, A; Chassignole, B; Fouquet, T; Derode, A

    2014-01-01

    Ultrasonic non-destructive testing of polycrystalline structures can be disturbed by scattering at grain boundaries. Understanding and modeling this so-called "structural noise" is crucial for characterization as well as detection purposes. Structural noise can be considered as a fingerprint of the material under investigation, since it contains information about its microstructure. The interpretation of experimental data necessitates an accurate comprehension of complex phenomena that occur in multiple scattering media and thus robust scattering models. In particular, numerical models can offer the opportunity to realize parametrical studies on controlled microstructures. However, the ability of the model to simulate wave propagation in complex media must be validated. In that perspective, the main objective of the present work is to evaluate the ability of the finite-element code ATHENA 2D to reproduce typical features of multiple wave scattering in the context of ultrasonic non-destructive evaluation, with an array of sources and receivers. Experiments were carried out with a 64-element array, around 2 MHz. The sample was a mock-up of Inconel600 exhibiting a coarse grain structure with a known grain size distribution. The numerical model of this microstructure is based on Voronoi diagrams. Two physical parameters were used to compare numerical and experimental data: the coherent backscattering peak, and the singular value distribution of the array response matrix. Though the simulations are 2-D, a good agreement was found between simulated and experimental data. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. 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.

  15. Influence of humidity on high temperature oxidation of Inconel 600 alloy: Oxide layers and residual stress study

    NASA Astrophysics Data System (ADS)

    Xiao, J.; Prud'homme, N.; Li, N.; Ji, V.

    2013-11-01

    In order to understand the influence of humidity on high temperature oxidation of Inconel 600 alloy, in this work, water vapour (absolute humidity varying from 0% to 19%) was introduced in the thermal gravimetric analysis (TGA) system under artificial air between 600 °C and 900 °C. The oxides identification and the residual stress in the oxide layers have been studied by X-ray diffraction method in each of two oxide phases, simultaneously. The oxide surface morphology, cross-section microstructure and the chemical composition of the oxide layers were determined by FEG-SEM (Field Emission Gun Scanning Electron Microscope) observation and FEG-SEM EDS (Energy-dispersive X-ray spectroscopy) analysis. Depending on the oxidation temperature, the humidity and the oxidation duration, the oxide layer differed significantly. The residual stress levels in the different oxide layers (NiO-type layer and Cr2O3-type layer) have also been affected by the introduction of the water vapour. According to the analysis results, the residual stresses on oxide mainly came from the growth stress and thermomechanical stress; and the oxide growth stress was especially affected by humidity at high temperature.

  16. 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.

  17. The study on force, surface integrity, tool life and chip on laser assisted machining of inconel 718 using Nd:YAG laser source.

    PubMed

    Venkatesan, K

    2017-07-01

    Inconel 718, a high-temperature alloy, is a promising material for high-performance aerospace gas turbine engines components. However, the machining of the alloy is difficult owing to immense shear strength, rapid work hardening rate during turning, and less thermal conductivity. Hence, like ceramics and composites, the machining of this alloy is considered as difficult-to-turn materials. Laser assisted turning method has become a promising solution in recent years to lessen cutting stress when materials that are considered difficult-to-turn, such as Inconel 718 is employed. This study investigated the influence of input variables of laser assisted machining on the machinability aspect of the Inconel 718. The comparison of machining characteristics has been carried out to analyze the process benefits with the variation of laser machining variables. The laser assisted machining variables are cutting speeds of 60-150 m/min, feed rates of 0.05-0.125 mm/rev with a laser power between 1200 W and 1300 W. The various output characteristics such as force, roughness, tool life and geometrical characteristic of chip are investigated and compared with conventional machining without application of laser power. From experimental results, at a laser power of 1200 W, laser assisted turning outperforms conventional machining by 2.10 times lessening in cutting force, 46% reduction in surface roughness as well as 66% improvement in tool life when compared that of conventional machining. Compared to conventional machining, with the application of laser, the cutting speed of carbide tool has increased to a cutting condition of 150 m/min, 0.125 mm/rev. Microstructural analysis shows that no damage of the subsurface of the workpiece.

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

    NASA Technical Reports Server (NTRS)

    Lowdermilk, Warren H; Grele, Milton D

    1950-01-01

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

  2. 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.

  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.

    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.

  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.

    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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Effect of Foreign Object Damage on Fatigue of Inconel 718 at Elevated Temperature (1050°C)

    NASA Astrophysics Data System (ADS)

    Shenoy, Sneha

    The use of solar energy to produce power has increased substantially in the past few decades. In an attempt to provide uninterrupted solar power, production plants may find themselves having to operate the systems at temperatures higher than the operational capacity of the materials used in many of their components, which affects the microstructural and mechanical properties of those materials. Failures in components that have been exposed to these excessive temperatures have been observed during operations in the turbine used by AORA Solar Ltd. A particular component of interest was made of a material similar to the Ni-based superalloy Inconel 718 (IN 718), which was observed to have damage that is believed to have been initiated by Foreign Object Damage (FOD) and worsened by the high temperatures in the turbine. The potential links among the observed failure, FOD and the high temperatures of operation are investigated in this study. IN718 is a precipitation hardened nickel superalloy with resistance to oxidation and ability to withstand high stresses over a wide range of temperatures. Several studies have been conducted to understand IN 718 tensile and fatigue properties at elevated temperatures (600- 950°C). However, this study focuses on understanding the behavior of IN718 with FOD induced by a stream of 50 mum Alumina particles at a velocity of 200 m/s. under high cycle fatigue at an elevated temperature of 1050 °C. Tensile tests were conducted for both as-received and heat treated (1050 °C in air for 8hrs) samples at room and high temperature. Fatigue tests were performed at heat treated samples at 1050 °C for samples with and without ablation. The test conditions were as similar as possible to the conditions in the AORA turbine. The results of the study provide an insight into tensile properties, fatigue properties and FOD. The results indicated a reduction in fatigue life for the samples with ablation damage, where crack nucleation occurred either at

  12. 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

  13. 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

  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. 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.

  16. 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.

  17. The effects of proton irradiation on the microstructural and mechanical property evolution of inconel X-750 with high concentrations of helium

    NASA Astrophysics Data System (ADS)

    Judge, C. D.; Bhakhri, V.; Jiao, Z.; Klassen, R. J.; Was, G.; Botton, G. A.; Griffiths, M.

    2017-08-01

    Ni-based alloys, which are used in nuclear applications with a high thermal flux, are shown to contain a high density of helium bubbles within the matrix and aligned along grain boundaries, resulting in lost strength and ductility. In the current investigation, material with and without helium is irradiated with protons up to approximately 60 dpa and 18 000 appm helium. With the use of advanced microscopy and nano-indentation, the microstructural evolution and mechanical hardening has been characterized. The addition of helium decreases the rate of disordering of the gamma prime phase, and suppresses void swelling by forming a region with a high density of helium bubbles, and thereby inhibiting the mobility of freely-migrating point defects. Mechanical hardening from proton-irradiation is consistent with neutron-irradiated Inconel X-750 and Alloy 718.

  18. Hydrogen embrittlement of ultra-pure alloys of the inconel 600 type: Influence of the additions of elements (C, P, Sn, Sb)

    NASA Astrophysics Data System (ADS)

    Cornet, M.; Bertrand, C.; Belo, M. Da Cunha

    1982-01-01

    The mechanical behavior of very high purity nickel base alloys of the Inconel 600 type that were simultaneously charged with hydrogen and deformed in tension was investigated. Experimental results show that this procedure decreases markedly the fracture strain of the pure 76 pct Ni-16 pct Cr-8 pct Fe alloy; cracks are observed after two to four pct elongation, and the fracture is completely intercrystalline. Hydrogen embrittlement appears as an intrinsic property of the Ni-Cr-Fe system in the sense that the grain boundary cohesion decreases when the purity of the alloy increases. The presence of carbon or phosphorus in the alloys increases grain boundary cohesion. The addition of metallic elements such as antimony or tin has relatively little effect on intergranular embrittlement.

  19. 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.

  20. Adhesion measurements and chemical and microstructural characterization at interfaces of titanium nitride and titanium aluminum nitride coatings on stainless steel, inconel and titanium alloys

    NASA Astrophysics Data System (ADS)

    James, Robert Dallas

    To assess the adhesion of nitride coatings on metal alloys, Ti 6Al-4V, 17-4 PH stainless steel and Inconel 718 alloy substrates were coated with titanium nitride (TiN) using both cathodic arc and electron beam evaporation. Titanium aluminum nitride ((Ti,Al)N) was also deposited using cathodic arc evaporation. X-ray photoelectron, Auger electron, and energy dispersive x-ray spectroscopies were used in tandem with cross-sectional transmission electron microscopy to analyze the coatings and the coating-substrate interfaces. The interfaces were found to be abrupt with a thin layer of W contamination located between the substrate and the Ti interlayer, deposited to improve adhesion, on electron beam evaporated samples. Metallic macroparticles up to two microns in diameter were observed in cathodic arc evaporated coatings. Residual stress analysis of the coatings revealed the presence of biaxial compressive residual stresses in all coatings. Residual stresses increased for coating-substrate systems with a larger mismatch between the coefficients of thermal expansion for the coating and the substrate. Scratch tests of the coatings revealed lower critical load values for coatings on Ti 6Al-4V due to the lower hardness of the substrate alloy relative to the stainless steel and Inconel alloys. The scratch test is a common method for evaluating adhesion of a coating to its substrate; however, this technique is not well understood due to complex loading of specimen as coating is removed. Plate impact spallation, is a more uncommon method for evaluating adhesion, but the advantage of this technique is that the interface is subjected to purely tensile loading. During plate impact spallation, the interfaces of the coated samples were loaded in tension using a high speed shock wave which caused spallation either at the interface, in the coating or in the metal. Failure in cathodic arc deposited coatings occurred in the form of isolated spallation craters located within the

  1. Laser Engineered Net Shaping of Nickel-Based Superalloy Inconel 718 Powders onto AISI 4140 Alloy Steel Substrates: Interface Bond and Fracture Failure Mechanism

    PubMed Central

    Kim, Hoyeol; Cong, Weilong; Zhang, Hong-Chao; Liu, Zhichao

    2017-01-01

    As a prospective candidate material for surface coating and repair applications, nickel-based superalloy Inconel 718 (IN718) was deposited on American Iron and Steel Institute (AISI) 4140 alloy steel substrate by laser engineered net shaping (LENS) to investigate the compatibility between two dissimilar materials with a focus on interface bonding and fracture behavior of the hybrid specimens. The results show that the interface between the two dissimilar materials exhibits good metallurgical bonding. Through the tensile test, all the fractures occurred in the as-deposited IN718 section rather than the interface or the substrate, implying that the as-deposited interlayer bond strength is weaker than the interfacial bond strength. From the fractography using scanning electron microscopy (SEM) and energy disperse X-ray spectrometry (EDS), three major factors affecting the tensile fracture failure of the as-deposited part are (i) metallurgical defects such as incompletely melted powder particles, lack-of-fusion porosity, and micropores; (ii) elemental segregation and Laves phase, and (iii) oxide formation. The fracture failure mechanism is a combination of all these factors which are detrimental to the mechanical properties and structural integrity by causing premature fracture failure of the as-deposited IN718. PMID:28772702

  2. 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.

  3. A crystal plasticity model incorporating the effects of precipitates in superalloys: Application to tensile, compressive, and cyclic deformation of Inconel 718

    DOE PAGES

    Ghorbanpour, Saeede; Zecevic, Milovan; Kumar, Anil; ...

    2017-09-14

    An elasto-plastic polycrystal plasticity model is developed and applied to an Inconel 718 (IN718) superalloy that was produced by additive manufacturing (AM). The model takes into account the contributions of solid solution, precipitates shearing, and grain size and shape effects into the initial slip resistance. Non-Schmid effects and backstress are also included in the crystal plasticity model for activating slip. The hardening law for the critical resolved shear stress is based on the evolution of dislocation density. In using the same set of material and physical parameters, the model is compared against a suite of compression, tension, and large-strain cyclicmore » mechanical test data applied in different AM build directions. We demonstrate that the model is capable of predicting the particularities of both monotonic and cyclic deformation to large strains of the alloy, including decreasing hardening rate during monotonic loading, the non-linear unloading upon the load reversal, the Bauschinger effect, the hardening rate change during loading in the reverse direction as well as plastic anisotropy and the concomitant microstructure evolution. It is anticipated that the general model developed here can be applied to other multiphase alloys containing precipitates.« less

  4. 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.

  5. 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.

  6. Laser Engineered Net Shaping of Nickel-Based Superalloy Inconel 718 Powders onto AISI 4140 Alloy Steel Substrates: Interface Bond and Fracture Failure Mechanism.

    PubMed

    Kim, Hoyeol; Cong, Weilong; Zhang, Hong-Chao; Liu, Zhichao

    2017-03-25

    As a prospective candidate material for surface coating and repair applications, nickel-based superalloy Inconel 718 (IN718) was deposited on American Iron and Steel Institute (AISI) 4140 alloy steel substrate by laser engineered net shaping (LENS) to investigate the compatibility between two dissimilar materials with a focus on interface bonding and fracture behavior of the hybrid specimens. The results show that the interface between the two dissimilar materials exhibits good metallurgical bonding. Through the tensile test, all the fractures occurred in the as-deposited IN718 section rather than the interface or the substrate, implying that the as-deposited interlayer bond strength is weaker than the interfacial bond strength. From the fractography using scanning electron microscopy (SEM) and energy disperse X-ray spectrometry (EDS), three major factors affecting the tensile fracture failure of the as-deposited part are (i) metallurgical defects such as incompletely melted powder particles, lack-of-fusion porosity, and micropores; (ii) elemental segregation and Laves phase, and (iii) oxide formation. The fracture failure mechanism is a combination of all these factors which are detrimental to the mechanical properties and structural integrity by causing premature fracture failure of the as-deposited IN718.

  7. 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.

  8. Observations of melt rate as a function of arc power, CO pressure, and electrode gap during vacuum consumable arc remelting of Inconel 718

    NASA Astrophysics Data System (ADS)

    Zanner, F. J.; Bertram, L. A.; Adasczik, C.; O'Brien, T.

    1984-01-01

    Statistically designed experiments were conducted at two different production melt shops to evaluate the influence of arc power, CO pressure, and electrode gap on melt rate. Approximately 11,000 kg of Inconel 718 alloy 0.4 m diameter electrodes were vacuum consumable arc remelted into 0.5 m diameter ingots. Analysis of the experimental results revealed that melting efficiency (melting rate/kW) was maximized when CO pressure and electrode gap were held at low levels. Under these conditions, the heat distribution (created by the vacuum arc) on the electrode tip and the molten pool exhibited macro uniformity. Increased CO pressure and/or electrode gap depressed the melt rate, and at 13.3 Pa (100 microns) and a 0.050 m electrode gap, this depression exceeds 46 pct. Increasing these parameters also changed the arc behavior to that of a constricted arc with a highly localized heat input. It is hypothesized that the change from the usual diffuse arc to this constricted arc results in intense Lorentz pumping in a localized region of the molten pool atop the ingot causing fluid flow transients. These transients could, in turn, create solidification defects.

  9. 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).

  10. Corrosion of Inconel 690 in N2-0.1%H2S gas at 700-800 °C

    NASA Astrophysics Data System (ADS)

    Yadav, Poonam; Lee, Dong Bok

    2017-09-01

    Inconel 690 superalloy was corroded at 700 °C and 800 °C for up to 70 h in N2-0.1% H2S gas. It corroded almost linearly with large weight gains, displaying little protectiveness. Its corrosion rates were quite fast when compared with its corrosion in air or Ar-1%SO2 gas. The formed scales were thick, fragile, and nonadherent. They consisted primarily of Cr2O3 with some NiCr2O4, Ni3S2, CrS, and Cr2S3. The H2S gas accelerated the corrosion significantly by forming nonprotective sulfides and dissolving hydrogen in the scale and in the internal corrosion zone that consisted of discrete chromium-sulfides and some oxide particles. The marker test indicated that the scales grew by the outward diffusion of metallic ions such as Ni, Cr, Fe, and Mn, whilst the internal corrosion zone thickened by the inward migration of oxygen and sulfur through the lattice, grain boundaries, and microcracks.

  11. The defects and microstructure in the fusion zone of multipass laser welded joints with Inconel 52M filler wire for nuclear power plants

    NASA Astrophysics Data System (ADS)

    Li, Gang; Lu, Xiaofeng; Zhu, Xiaolei; Huang, Jian; Liu, Luwei; Wu, Yixiong

    2017-09-01

    The defects and microstructure in the fusion zone of multipass laser welded joints with Inconel 52M filler wire are investigated for nuclear power plants. Experimental results indicate that the incomplete fusion forms as the deposited metals do not completely cover the groove during multipass laser welding. The dendritic morphologies are observed on the inner surface of the porosity in the fusion zone. Many small cellular are found in the zones near the fusion boundary. With solidification preceding, cellular gradually turn into columnar dendrites and symmetrical columnar dendrites are exhibited in the weld center of the fusion zone. The fine equiaxed grains form and columnar dendrites disappear in the remelted zone of two passes. The dendrite arm spacing in the fusion zone becomes widened with increasing welding heat input. Nb-rich carbides/carbonitrides are preferentially precipitated in the fusion zone of multipass laser welded joints. In respect to high cooling rate during multipass laser welding, element segregation could be insufficient to achieve the component of Laves phase.

  12. 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.

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

    SciTech Connect

    Bast, C.C.; Boyce, L.

    1995-01-01

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

  14. 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.

  15. Aeronautical requirements for Inconel 718 alloy

    NASA Astrophysics Data System (ADS)

    Elefterie, C. F.; Guragata, C.; Bran, D.; Ghiban, B.

    2017-06-01

    The project goal is to present the requirements imposed by aviation components made from super alloys based on Nickel. A significant portion of fasteners, locking lugs, blade retainers and inserts are manufactured from Alloy 718. The thesis describes environmental factors (corrosion), conditions of external aggression (salt air, intense heat, heavy industrial pollution, high condensation, high pressure), mechanical characteristics (tensile strength, yield strength and fatigue resistance) and loadings (tensions, compression loads) that must be satisfied simultaneously by Ni-based super alloy, compared to other classes of aviation alloys (as egg. Titanium alloys, Aluminum alloys). For this alloy the requirements are strength durability, damage tolerance, fail safety and so on. The corrosion can be an issue, but the fatigue under high-magnitude cyclic tensile loading it’s what limits the lifetime of the airframe. Also, the excellent malleability and weldability characteristics of the 718 system make the material physical properties tolerant of manufacturing processes. These characteristics additionally continue to provide new opportunities for advanced manufacturing methods.

  16. 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)

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Advances in Neutron Radiography: Application to Additive Manufacturing Inconel 718

    DOE PAGES

    Bilheux, Hassina Z; Song, Gian; An, Ke; ...

    2016-01-01

    Reactor-based neutron radiography is a non-destructive, non-invasive characterization technique that has been extensively used for engineering materials such as inspection of components, evaluation of porosity, and in-operando observations of engineering parts. Neutron radiography has flourished at reactor facilities for more than four decades and is relatively new to accelerator-based neutron sources. Recent advances in neutron source and detector technologies, such as the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN, and the microchannel plate (MCP) detector, respectively, enable new contrast mechanisms using the neutron scattering Bragg features for crystalline information such as averagemore » lattice strain, crystalline plane orientation, and identification of phases in a neutron radiograph. Additive manufacturing (AM) processes or 3D printing have recently become very popular and have a significant potential to revolutionize the manufacturing of materials by enabling new designs with complex geometries that are not feasible using conventional manufacturing processes. However, the technique lacks standards for process optimization and control compared to conventional processes. Residual stresses are a common occurrence in materials that are machined, rolled, heat treated, welded, etc., and have a significant impact on a component s mechanical behavior and durability. They may also arise during the 3D printing process, and defects such as internal cracks can propagate over time as the component relaxes after being removed from its build plate (the base plate utilized to print materials on). Moreover, since access to the AM material is possible only after the component has been fully manufactured, it is difficult to characterize the material for defects a priori to minimize expensive re-runs. Currently, validation of the AM process and materials is mainly through expensive trial-and-error experiments at the component level, whereas in conventional processes the level of confidence in predictive computational modeling is high enough to allow process and materials optimization through computational approaches. Thus, there is a clear need for non-destructive characterization techniques and for the establishment of processing- microstructure databases that can be used for developing and validating predictive modeling tools for AM.« less

  3. Advances in Neutron Radiography: Application to Additive Manufacturing Inconel 718

    SciTech Connect

    Bilheux, Hassina Z; Song, Gian; An, Ke; Bilheux, Jean-Christophe; Kirka, Michael M; Dehoff, Ryan R; Santodonato, Louis J; Gorti, Sarma B; Radhakrishnan, Balasubramaniam; Xie, Qingge

    2016-01-01

    Reactor-based neutron radiography is a non-destructive, non-invasive characterization technique that has been extensively used for engineering materials such as inspection of components, evaluation of porosity, and in-operando observations of engineering parts. Neutron radiography has flourished at reactor facilities for more than four decades and is relatively new to accelerator-based neutron sources. Recent advances in neutron source and detector technologies, such as the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN, and the microchannel plate (MCP) detector, respectively, enable new contrast mechanisms using the neutron scattering Bragg features for crystalline information such as average lattice strain, crystalline plane orientation, and identification of phases in a neutron radiograph. Additive manufacturing (AM) processes or 3D printing have recently become very popular and have a significant potential to revolutionize the manufacturing of materials by enabling new designs with complex geometries that are not feasible using conventional manufacturing processes. However, the technique lacks standards for process optimization and control compared to conventional processes. Residual stresses are a common occurrence in materials that are machined, rolled, heat treated, welded, etc., and have a significant impact on a component s mechanical behavior and durability. They may also arise during the 3D printing process, and defects such as internal cracks can propagate over time as the component relaxes after being removed from its build plate (the base plate utilized to print materials on). Moreover, since access to the AM material is possible only after the component has been fully manufactured, it is difficult to characterize the material for defects a priori to minimize expensive re-runs. Currently, validation of the AM process and materials is mainly through expensive trial-and-error experiments at the component level, whereas in conventional processes the level of confidence in predictive computational modeling is high enough to allow process and materials optimization through computational approaches. Thus, there is a clear need for non-destructive characterization techniques and for the establishment of processing- microstructure databases that can be used for developing and validating predictive modeling tools for AM.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Prediction of the crack initiation time of the alloys used in high temperature water

    SciTech Connect

    Tsubota, M.; Kanazawa, Y.

    1994-12-31

    Correlations between applied stress ({sigma}) and SCC initiation time (t) of sensitized 304 stainless steel, alloy 600 and alloy X-750 were studied. A general expression t = m {times} {sigma}{sup {minus}n} was obtained from both the analysis of the uni-axial constant load test data and the theoretical considerations of the crack initiation process. The n-value was determined from the process of crack initiation, and the m-value was a constant determined from material and environmental conditions.

  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. 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.

  14. 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.

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

    DTIC Science & Technology

    1983-12-01

    been used successfully to predict the fatigue lifetime of components under low temperature iso - thermal conditions. More recently, LEFM has been...the temperature was changed. The transition times were obtained by comparing the raw data and the crack growth rate curves of the iso - thermal...Recommendations Conclusions Within the scope of this investigation, linear cumulative damage modeling accurately predicts creep crack growth rates under non- iso

  16. 2500 KW Ship Service Turbine Generator Casing Welded Inconel Plug Failure and Repair Analysis

    DTIC Science & Technology

    2012-06-01

    Engineering Operating Procedure (EOP) only specifies lube oil temperature requirements prior to turbine operation. Turbine casing warm up and thermal...the model parts into many small elements. The elements can be refined in the area of interest to give a more accurate result. Overly refined mesh...components required mesh refinements around the plug, inlay, and filler. With all the refinements , the model contained approximately 174,000 nodes. The

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

    DTIC Science & Technology

    1975-05-01

    8217 GENERAL, CREVICE, STRESS ri *ARGON ATMOSPHERE F igure 5 Welding and Heat Treaments Pene 4’ 4528 Arc Voltage - 13 Cas, cu ft/hr Arc Current, amperes - 250...Candidate materials Welding Hydrofoils Machining Postweld heat treatments Nicke]1-base alloys 20. ABSTRACT ’ContInue on reveree olde If necessary and...were ,rcp.Irec. Mechanical, faLi[gue, corlos’osion fatigue, and corrosion tests were performed on thOse material.s wil h ’tar ins post.we1d heat t

  18. 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.

  19. Heat-affected zone thermal cycles in Inconel[reg sign] 718

    SciTech Connect

    Bowers, R.J. CANMET-MTL, Ottawa, Ontario ); Nippes, E.F. . Materials Engineering Dept.)

    1993-12-01

    Thermal cycles adjacent to autogenous welds in 1-cm (0.39-in.) IN718 plate were obtained using a computer data-acquisition system. Data from gas tungsten arc welds (GTAW) of various energy inputs were regression analyzed and tabulated for various times and distances from the centerline. The observation of grain-boundary precipitates in simulated and actual weld microstructures were used as a method of thermal-cycle verification. Application of the thermal-cycle data to the simulation of a fracture-toughness specimen was investigated. Thermal gradients across the specimen and high cooling rates were limiting factors in the microstructural simulation of a large cross-sectional-area specimen.

  20. 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.

  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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Casias, Andrea M.

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

  9. Performance of the ZT-40M reversed-field pinch with an Inconel liner

    SciTech Connect

    Baker, D.A.; Bausman, M.D.; Buchenauer, C.J.

    1982-01-01

    Modifications made to ZT-40 have substantially improved plasma parameters: pinch resistance has decreased by more than an order of magnitude, T/sub e/ has exceeded 300 eV, and with power crowbar operation > 20 ms steady-state discharges have been obtained. With a ..beta.. of approx. 0.1, and the assumptions of modified Bessel function magnetic-field profiles and classical ohmic heating the energy confinement time, approx. 0.2 ms, is close to that expected for the measured temperatures and discharge currents. A relaxation process (dynamo) sustains RFP profiles extending discharge lifetimes beyond the limit predicted by classical resistive diffusion. If the process continues to operate, a steady-state RFP is possible. Extension of the toroidal current risetime to the experiment's design limit (1.5 ms) indicates that RFPs can be formed at still longer risetimes with reasonable voltsecond and energy inputs facilitating the design of future experiments. These results represent a significant advance for the RFP concept toward a viable ohmic-heated magnetic-fusion system.

  10. Microstructural Evolution and Creep Rupture Behavior of INCONEL RTM Alloy 740H Fusion Welds

    NASA Astrophysics Data System (ADS)

    Bechetti, Daniel H., Jr.

    Electron microscopy techniques were used to investigate the causes of reduced creep-rupture life in INCONEL® alloy 740H ® fusion welds with a specific focus on understanding the formation and evolution of γ'-free zones along grain boundaries. Investigation of creep-rupture specimens revealed four operational factors that influence the formation of these precipitate-free zones, and the identity of large second phase particles typically found within them has been determined. A stress-free aging has demonstrated the influence of stress on the formation of the precipitate-free regions and has illustrated what appear to be the initial stages of their development. It is concluded that the mechanism of precipitate-free zone formation in alloy 740H is moderate discontinuous precipitation accompanied by significant discontinuous growth of the γ' phase. These discontinuous reactions are likely exacerbated by microsegregation within the welded microstructure and by the mechanical deformation associated with grain boundary sliding during creep. Thermodynamic and kinetic modeling were used to determine appropriate heat treatment schedules for homogenization and second phase dissolution of welds in alloy 740H. Following these simulations, a two-step heat treatment process was applied to specimens from a single pass gas tungsten arc weld (GTAW). Scanning electron microscopy (SEM) has been used to assess the changes in the distribution of alloying elements as well as changes in the fraction of second phase particles within the fusion zone. Experimental results demonstrate that homogenization of alloy 740H weld metal can be achieved by an 1100°C/4hr treatment. Complete dissolution of second phase particles could not be completely achieved, even at exposure to temperatures near the alloy's solidus temperature. These results are in good agreement with thermodynamic and kinetic predictions.

  11. Real-time monitoring of laser hot-wire cladding of Inconel 625

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Liu, Wei; Harooni, Masoud; Ma, Junjie; Kovacevic, Radovan

    2014-10-01

    Laser hot-wire cladding (LHWC), characterized by resistance heating of the wire, largely increases the productivity and saves the laser energy. However, the main issue of applying this method is the occurrence of arcing which causes spatters and affects the stability of the process. In this study, an optical spectrometer was used for real-time monitoring of the LHWC process. The corresponding plasma intensity was analyzed under various operating conditions. The electron temperature of the plasma was calculated for elements of nickel and chromium that mainly comprised the plasma plume. There was a correlation between the electron temperature and the stability of the process. The characteristics of the resulted clad were also investigated by measuring the dilution, hardness and microstructure.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  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. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. Performance and Reliability of Exhaust Gas Waste Heat Recovery Units

    DTIC Science & Technology

    2014-09-01

    materials (steel, copper , Inconel, and ceramic) on heat recovery performance, exhaust side pressure drop, and temperature profile in the exhaust gas...diameter (D/d) ratio, coolant inlet and outlet placements, exhaust gas swirling conditions, and tube materials (steel, copper , Inconel, and ceramic...Temperature Profile ..................................80 a. Inconel 625 Tube ....................................................................80 b. Copper

  16. 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...

  17. 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

  18. 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.

  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. 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.

  1. 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.

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

    SciTech Connect

    Symons, D.M.

    1999-12-01

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

  3. 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.

  4. Electrospark Deposition for the Repair of Army Main Battle Tank Components

    DTIC Science & Technology

    2006-07-01

    approval. 6.1 Training Initial ESD training was completed at ARL and was attended by repair personnel, technicians, engineers, and first-line...supervisors representing ARL, ANAD, and representatives from several major aerospace companies. ARL was chosen as the site for the initial training because...Stellite 21, Inconel 718, and Inconel 625 were deposited onto low-alloy carbon steel and Inconel 718 substrates. 6.2 ESD Procedure Development (M1A1

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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).

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

    SciTech Connect

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

    1995-02-22

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

  11. 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.

  12. Influence of high pressure hydrogen on cyclic load crack growth in metals

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    The effect of high pressure hydrogen on the crack growth rate of various nickel-base alloys was studied at ambient temperature. Considerable enhancement of the cyclic flaw growth rate was observed for Inconel 718, wrought and cast, and Waspaloy, a nickel-base alloy similar to Inconel 718. Only slight enhancement of the flaw growth rate for Alloy 903 was observed.

  13. 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...

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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 .

  5. 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.

  6. 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

  7. 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)

  8. Summary of the Proceedings of the National Symposium on Fracture Mechanics (17th) Held on 7-9 Aug 84 in Albany, New York.

    DTIC Science & Technology

    1986-12-01

    is that brittle fracture should be initiated at the center of a wide plate to eliminate the effects of high compressive residual stresses that exist...FCPR at elevated temperatures. Using Inconel 718 and studying the constant K behav- ior at 650*C, they were able to show that the hold times at...eval- uating Inconel 718 at 650 0 C, A. Petrovich, W. Bessler, and W. Zieglhr were able to detail the interactive effects of low and high frequency

  9. Analysis of normal and transparent silver Teflon

    NASA Technical Reports Server (NTRS)

    Stuckey, W. K.; Galuska, A. A.; Uht, J.

    1985-01-01

    Samples of Inconel/silver/Teflon exposed to solar radiation, and atomic oxygen on Solar Max were microcharacterized. Those samples exposed to atomic oxygen from the metallic side had become transparent while those exposed from the Teflon side remained reflective. The difference between the transparent and non-transparent material was determined. Microcharacterization of these Inconel/silver/Teflon samples was performed using scanning electron microscopy with windowless energy dispersive X ray analysis, secondary ion mass spectrometry, and X ray photoelectron spectroscopy.

  10. 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

  11. 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.

  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. 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.

  15. 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.

  16. Microstructure-dependent fracture toughness (JIC) variations in dissimilar pipe welds for pressure vessel system of nuclear plants

    NASA Astrophysics Data System (ADS)

    Rathod, Dinesh W.; Pandey, Sunil; Singh, P. K.; Kumar, Suranjit

    2017-09-01

    In present study, dissimilar metal weld (DMW) joints between SA508Gr.3cl.1 ferritic steel and SS304LN pipes were prepared using Inconel 82/182, and Inconel 52/152 consumables. Metallurgical properties and their influence on fracture toughness of weldment regions and interfacial regions could play a significant role in integrity assessment of these joints. Ni-based consumables exhibit complex metallurgical properties at interfacial regions. The metallurgical characterization and fracture toughness studies of Inconel 82/182 and Inconel 52/152 joints have been carried out for determining the optimum consumable for DMW joint requirements and the effect of microstructure on fracture toughness in weldment regions. The present codes and procedures for integrity assessment of DMW joints have not given due considerations of metallurgical properties. The requirements for metallurgical properties by considering their effect on fracture toughness properties in integrity assessment have been discussed for reliable analysis. Inconel 82/182 is preferred over Inconel 52/152 joints owing to favorable metallurgical and fracture toughness properties across the interfacial and weldment regions.

  17. 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.

  18. 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

  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. 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.

  2. 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.

  3. 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.

  4. The Segregation and Liquation Crackings in the HAZ of Multipass Laser-Welded Joints for Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Li, Gang; Lu, Xiaofeng; Zhu, Xiaolei; Huang, Jian; Liu, Luwei; Wu, Yixiong

    2017-07-01

    The segregation and liquation crackings in the heat-affected zone (HAZ) beside Inconel 52M overlays of multipass laser-welded joints are investigated for nuclear power plants. The results indicate that Nb-rich precipitates are distributed in chains and some aggregate together as coarse particles in the local regions at the interface. With increasing heat input, the transition width becomes widened and the fraction of the precipitates at the interface significantly increases. Closely associated to Nb segregation, liquation crackings occur along columnar dendrites in the HAZ beside Inconel 52M overlays. Due to no deformation coordination of the columnar dendrites with Nb-rich segregates in Inconel 52M overlays, liquation crackings occur in thermal cycle of multipass laser welding. The enrichment of Nb element in the interdendritic regions increases favorable factors of liquation crackings at grain boundaries.

  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. 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.

  8. 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.

  9. The Segregation and Liquation Crackings in the HAZ of Multipass Laser-Welded Joints for Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Li, Gang; Lu, Xiaofeng; Zhu, Xiaolei; Huang, Jian; Liu, Luwei; Wu, Yixiong

    2017-08-01

    The segregation and liquation crackings in the heat-affected zone (HAZ) beside Inconel 52M overlays of multipass laser-welded joints are investigated for nuclear power plants. The results indicate that Nb-rich precipitates are distributed in chains and some aggregate together as coarse particles in the local regions at the interface. With increasing heat input, the transition width becomes widened and the fraction of the precipitates at the interface significantly increases. Closely associated to Nb segregation, liquation crackings occur along columnar dendrites in the HAZ beside Inconel 52M overlays. Due to no deformation coordination of the columnar dendrites with Nb-rich segregates in Inconel 52M overlays, liquation crackings occur in thermal cycle of multipass laser welding. The enrichment of Nb element in the interdendritic regions increases favorable factors of liquation crackings at grain boundaries.

  10. 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.

  11. 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)

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.