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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Hydrogen environment embrittlement of astroloy and Udimet 700 (nickel-base) and V-57 (iron-base) superalloys

The sensitivity to hydrogen environment embrittlement of three superalloys was determined. Astroloy forgings were resistant to embrittlement during smooth tensile, notched tensile, and creep testing in 3.5-MN/sq m hydrogen over the range 23 to 760 C. The notched tensile strength of Udimet 700 bar stock in hydrogen at 23 C was only 50 percent of the baseline value in helium. Forgings of V-57 were not significantly embrittled by hydrogen during smooth tensile testing over the range 23 to 675 C; creep and rupture lives of V-57 were degraded by hydrogen. Postcreep tensile ductility of V-57 was reduced by 40 percent after creep exposure in hydrogen.

Gray, H. R.↗
NASA NTRS1990

Application of magnetoacoustic emission technique to temper embrittlement characterization of HY-80 steel

Magnetoacoustic phenomena associated with the use of the magnetoacoustic emission technique for the temper embrittlement characterization of HY-80 steel are investigated in an attempt to explain some peculiarities observed in highly embrittled HY-80 samples. In particular, attention is given to the effects of the ac magnetic field frequency and shape. The peak amplitude of the magnetoacoustic burst, which is directly related to the width of the pulse height distribution, is shown to be a critical parameter in the determination of the degree of temper embrittlement in the steel.

Denale, R.↗
NASA NTRS1992

Influence of hydrogen oxidation kinetics on hydrogen environment embrittlement

Results are presented from experiments performed to determine the roles of hydrogen absorption and hydrogen electron transfer on the susceptibility of Fe- and Ni-base alloys to ambient-temperature hydroen embrittlement. An apparent independence is noted between hydrogen environment embrittlement and internal hydrogen embrittlement. The experiments were performed on Inconel 718, Incoloy 903, and A286. The electrochemical results obtained indicate that Inconel 718 either adsorbs hydrogen more rapidly and/or the electrochemical oxidation of the adsorbed hydrogen occurred more rapidly than in the other two materials.

Walter, R. J.↗
NASA NTRS1929

Corrosion Embrittlement of Duralumin V : Results of Weather-Exposure Tests

In a series of weather exposure tests of sheet duralumin, upon which accelerated corrosion tests in the laboratory by the wet-and-dry corrosion method in a sodium chloride solution has already been carried out, a close parallelism between the results of the two kinds of tests was found to exist. The exposure tests showed that the lack of permanence of sheet duralumin is largely, if not entirely, due to corrosion. A corrosion attack of an intercrystalline nature is very largely responsible for the degree of embrittlement produced. The rate of embrittlement was greatly accelerated by a marine atmosphere and by the tropical climate. Variations in corrosion and embrittlement are noted in relation to heat treatment, cold working, and types of protective coatings.

Rawdon, Henry S↗
NASA NTRS2010

Empirical Method to Estimate Hydrogen Embrittlement of Metals as a Function of Hydrogen Gas Pressure at Constant Temperature

High pressure Hydrogen (H) gas has been known to have a deleterious effect on the mechanical properties of certain metals, particularly, the notched tensile strength, fracture toughness and ductility. The ratio of these properties in Hydrogen as compared to Helium or Air is called the Hydrogen Environment Embrittlement (HEE) Index, which is a useful method to classify the severity of H embrittlement and to aid in the material screening and selection for safety usage H gas environment. A comprehensive world-wide database compilation, in the past 50 years, has shown that the HEE index is mostly collected at two conveniently high H pressure points of 5 ksi and 10 ksi near room temperature. Since H embrittlement is directly related to pressure, the lack of HEE index at other pressure points has posed a technical problem for the designers to select appropriate materials at a specific H pressure for various applications in aerospace, alternate and renewable energy sectors for an emerging hydrogen economy. Based on the Power-Law mathematical relationship, an empirical method to accurately predict the HEE index, as a function of H pressure at constant temperature, is presented with a brief review on Sievert's law for gas-metal absorption.

Lee, Jonathan A.↗
NASA NTRS2012

Embrittlement of MISSE 5 Polymers After 13 Months of Space Exposure

Understanding space environment induced degradation of spacecraft materials is essential when designing durable and stable spacecraft components. As a result of space radiation, debris impacts, atomic oxygen interaction, and thermal cycling, the outer surfaces of space materials degrade when exposed to low Earth orbit (LEO). The objective of this study was to measure the embrittlement of 37 thin film polymers after LEO space exposure. The polymers were flown aboard the International Space Station and exposed to the LEO space environment as part of the Materials International Space Station Experiment 5 (MISSE 5). The samples were flown in a nadir-facing position for 13 months and were exposed to thermal cycling along with low doses of atomic oxygen, direct solar radiation and omnidirectional charged particle radiation. The samples were analyzed for space-induced embrittlement using a bend-test procedure in which the strain necessary to induce surface cracking was determined. Bend-testing was conducted using successively smaller mandrels to apply a surface strain to samples placed on a semi-suspended pliable platform. A pristine sample was also tested for each flight sample. Eighteen of the 37 flight samples experienced some degree of surface cracking during bend-testing, while none of the pristine samples experienced any degree of cracking. The results indicate that 49 percent of the MISSE 5 thin film polymers became embrittled in the space environment even though they were exposed to low doses (approx.2.75 krad (Si) dose through 127 mm Kapton) of ionizing radiation.

Guo, Aobo↗
DOE OSTI2022

Impact of Gold Thickness on Interfacial Evolution and Subsequent Embrittlement of Tin–Lead Solder Joints

Although gold remains a preferred surface finish for components used in high-reliability electronics, rapid developments in this area have left a gap in the fundamental understanding of solder joint gold (Au) embrittlement. Furthermore, as electronic designs scale down in size, the effect of Au content is not well understood on increasingly smaller solder interconnections. As a result, previous findings may have limited applicability. The current study focused on addressing these gaps by investigating the interfacial microstructure that evolves in 63Sn-37Pb solder joints as a function of Au layer thickness. Those findings were correlated to the mechanical performance of the solder joints. Increasing the initial Au concentration decreased the mechanical strength of a joint, but only to a limited degree. Kirkendall voids were the primary contributor to low-strength joints, while brittle fracture within the intermetallic compounds (IMC) layers is less of a factor. The Au embrittlement mechanism appears to be self-limiting, but only once mechanical integrity is degraded. Sufficient void evolution prevents continued diffusion from the remaining Au.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Evaluation of liquid metal embrittlement of F82H and 4340 steels in liquid lithium

Here, to evaluate the liquid metal embrittlement (LME) susceptibility of F82H, a reduced activation ferritic-martensitic (RAFM) steel, a testing procedure using hollow cylindrical tensile specimens was used. Tensile tests are compared between specimens filled with argon and lithium at 200 °C. To validate the procedure, initial testing was performed on type 4340 steel, which is well-known to exhibit LME. Compared to 4340 steel, F82H only showed minor effects of Li exposure, including pre-testing exposures with Li at 400 °C for 1 h and 500 °C for 500 h. Furthermore, changing the strain rate or tensile test temperature also did not show significant embrittlement.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Hydrogen embrittlement and mechanical response of 304L steel with ZrC additions

While stainless steels are widely used for hydrogen storage infrastructure, they can still be vulnerable to hydrogen embrittlement justifying the need to further improve their hydrogen resiliency. Here, we investigate the potential for transition metal carbide additions to improve the hydrogen compatibility of austenitic stainless steels. ZrC nanoparticles were dispersed in contents of 0.01–10 wt% in 304 L stainless steel powder, mixed via high energy ball milling, and subsequently consolidated using direct current sintering. To assess hydrogen compatibility, the tensile properties of similarly processed 304 L without ZrC nanoparticles were compared to 304 L with the ZrC additions; both materials were evaluated prior to and after hydrogen exposure (non-charged and H-precharged, respectively). Depending upon the ZrC phase fraction, the yield strengths varied from ∼325 to 560 MPa in the non-charged condition and from ∼375 to 550 MPa in the H-precharged condition. Strain at failure varied from ∼5 to 90 % and from ∼5 to 35 % in the non-charged and hydrogen-precharged conditions, respectively. Results from stress-strain profiles demonstrate limited efficacy of ZrC as a method to mitigate hydrogen embrittlement entirely but does demonstrate the potency of ZrC inclusions as strengthening addition to 304 L alloys without a loss of ductility.

08 HYDROGEN↗
DOE OSTI2020

Fast Neutron Irradiation Embrittlement-ductilitization of an Iron-based Amorphous Alloy using In Situ Synchrotron X-ray Diffraction

Amorphous Fe-based nanostructured alloy coatings thermally sprayed on bcc steel substrate, were subjected to neutron irradiation doses up to 2 × 10 19 n/cm 2 . It is shown that the interplay between embrittlement and recovery of ductility is governed by amorphous to crystallization transition and phase decomposition in which temperature and irradiation dose have reciprocal effects. Microscopic (X-ray diffraction) observations on the behavior of the amorphous Fe-based alloy are correlated with relevant macroscopically observed mechanical behavior. It is shown that amorphous Fe-based alloy coatings maintain and even enhance their amorphous structure with irradiation, exhibit radiation-induced restoration of thermally-induced embrittlement and finally exhibit resistance to ductility loss up to the fluence of 2 × 10 18 n/cm 2 and good thermal stability up to 350 °C. The latter is deduced from X-ray diffraction experiments of in-situ tensile strain application on the irradiated coating.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electrochemical pumping: An alternative solution for hydrogen embrittlement

Hydrogen embrittlement is a form of chemo-mechanical damage that is special in that it can be partially reversible. Here, in this paper, we propose a method for recovering structural alloys from hydrogen embrittlement at room temperature by electrochemically biased desorption of hydrogen. We demonstrate that the method can enable the reversion of hydrogen-induced degradation of mechanical properties, by comparing the mechanical behavior of commercial stainless steel specimens at different hydrogen charging and desorption states. These case studies also reveal the influence of electrochemical potential, H content and the characteristics of H trapping sites, on the effectiveness of this recovery approach. The limitations arising from the presence of unhealable forms of hydrogen damage, and the generic applicability of this electrochemically-assisted recovery method are also discussed.

36 MATERIALS SCIENCE↗
NASA NTRS1967

Study to minimize hydrogen embrittlement of ultrahigh-strength steels

Hydrogen-stress cracking in high-strength steels is influenced by hydrogen content of the material and its hydrogen absorption tendency. Non-embrittling cleaning, pickling, and electroplating processes are being studied. Protection from this hydrogen embrittlement is important to the aerospace and aircraft industries.

Elsea, S. T.↗
NASA NTRS1968

Susceptibility of irradiated steels to hydrogen embrittlement

Investigation determined whether irradiated pressure-vessel steels 4340 and 212-B are susceptible to hydrogen embrittlement and to catastrophic failure. Hydrogen-charging conditions which completely embrittled 4340 steel had negligible effect on 212-B steel in tensile and delayed-failure tests.

Rossin, A. D.↗
NASA NTRS1970

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

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

Chandler, W. T.↗
NASA NTRS1974

Evaluation of test procedures for hydrogen environment embrittlement

Report presents discussion of three common and primary influences on embrittlement process. Application of theoretical considerations to design of test coupons and methods is illustrated for both internal and external hydrogen embrittlement. Acceptable designs and methods are indicated.

Nelson, H. G.↗
NASA NTRS1976

Hydrogen environment embrittlement of turbine disk alloys

Astroloy and V-57, two candidate turbine disk alloys for the auxiliary power unit (APU) of the space shuttle propulsion and power system were tested for their resistance to embrittlement in hydrogen environments. Samples of both these nickel-base alloys were subjected to notch and smooth tensile testing and to creep testing in hydrogen. The high resistance exhibited by Astroloy forgings to embrittlement by hydrogen is attributed to the microstructure produced by forging and also to the special heat treatment schedule. V-57 turbine disks successfully completed short-time performance testing in the experimental APU. The use of the Astroloy, however, would permit increasing turbine inlet temperature and the rotational speed beyond those possible with V-57.

Gray, H. R.↗
NASA NTRS1977

Mercury embrittlement of Cu-Al alloys under cyclic loading

The effect of mercury on the room temperature, high cycle fatigue properties of three alloys: Cu-5.5 pct Al, Cu-7.3 pct Al, and Cu-6.3 pct Al-2.5 pct Fe has been determined. Severe embrittlement under cyclic loading in mercury is associated with rapid crack propagation in the presence of the liquid metal. A pronounced grain size effect is noted under mercury, while fatigue properties in air are insensitive to grain size. The fatigue results are discussed in relation to theories of adsorption-induced liquid metal embrittlement.

Regan, T. M.↗
NASA NTRS1978

The effect of microstructure on hydrogen embrittlement of the nickel-base superalloy, Udimet 700

Material from a single heat of cast and wrought Udimet 700 was processed and/or heat treated to produce five material conditions with identical chemical compositions but with distinct microstructural variations, and then evaluated for susceptibility to hydrogen embrittlement. Two prealloyed powder conditions exhibited significantly improved resistance to hydrogen embrittlement, as compared to wrought material. No degradation in notch or smooth tensile strengths occurred, and average ductilities of 25 percent reduction of area were determined for 2 hydrogen evaluation procedures. For the most severe hydrogenation procedure, ductility levels were reduced to 15 percent. These improvements were attributed to cleaner grain boundaries and decreases grain size.

Gray, H. R.↗