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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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Tensile and fatigue properties and liquid oxygen compatibility of bilaminate stainless steel-clad titanium prepared by vacuum deposition and explosive welding
Elevated temperature effects on fatigue life of tensile stressed titanium alloys, aluminum alloys, and stainless steels
Fracture and crack growth for welded joints of 5Al-2.5Sn titanium in environment of low pressure, high purity hydrogen
Ceramic stresscoat burst and performance test of shrouded, diffusion welded titanium pump impellers for liquid hydrogen pump applications
Drilling tests for evaluating coring potential of Apollo lunar surface drill titanium core stems
Design, fabrication, and testing of improved titanium impeller for high pressure liquid hydrogen pumps
Developing thermally stable adhesives for bonding titanium alloy and boron composite substrates
Qualitative comparison of oxidation resistance of nickel-aluminum alloys with additions of chromium, silicon, and titanium at high temperatures
Chemical and metallurgical analyses of 6Al-4V titanium test specimens exposed to hydrazine /N2H2/ liquid propellant
Aluminum concentration effects on stress corrosion cracking of titanium alloys at ambient temperatures in aqueous solutions of salt
Hydrogen embrittlement of titanium alloy surface in hot salt corrosion cracking
Stress corrosion cracking of titanium alloys, velocity of cracking in aqueous and methanol solutions and halogenated organic solvents, concentration of TiCl3 in cracks
Metal composition effects on stress corrosion cracking of titanium alloys in nitrogen tetroxide, water, and salt
Stress wave emission from subcritical crack growth in thin walled Al-V titanium alloy
Stress effect on hydrogen distribution at high temperatures in titanium and Ti-Al-Mo-V alloy
Susceptibility of titanium alloys to hot-salt stress-corrosion cracking increased as follows: Ti-2Al-11Sn-5Zr-0.2Si(679), Ti-6Al-2Sn-4Zr-2Mo(6242), Ti-6Al-4V(64), Ti-6Al-4V-3Co(643), Ti-8Al-1Mo-1V(811), and Ti-13V-11Cr-3A1(13-11-3). The Ti-5Al-6Sn-2Zr-1Mo-0.25Si(5621S) alloy was both the least and most susceptible depending on heat treatment. Such rankings can be drastically altered by heat-to-heat and processing variations. Residual compressive stresses and cyclic exposures also reduce susceptibility to stress-corrosion. Simulated turbine-engine compressor environmental variables such as air velocity, pressure, dewpoint, salt concentration, and salt deposition temperature have only minor effects. Detection of substantial concentrations of hydrogen in all corroded alloys confirmed the existence of a hydrogen embrittlement mechanism.
Damage scar volume measurements taken from like metal fretting pairs combined with scanning electron microscopy observations showed that three sequentially operating mechanisms result in the fretting of titanium, Monel-400, and cobalt - 25-percent molybdenum. Initially, adhesion and plastic deformation of the surface played an important role. This was followed after a few hundred cycles by a fatigue mechanism which produced spall-like pits in the damage scar. Finally, a combination of oxidation and abrasion by debris particles became most significant. Damage scar measurements made on several elemental metals after 600,000 fretting cycles suggested that the ratio of oxide hardness to metal hardness was a measure of the susceptibility of a metal to progressive damage by fretting.
Hot-spot and puncture ignition of fuel vapors by simulated lightning discharges was studied experimentally. The influences of skin coating, skin structure, discharge polarity, skin thickness, discharge current level, and current duration were measured and interpreted. Ignition thresholds are reported for titanium alloy constructed as sheets, sheets coated with sealants, and sandwich skins. Results indicated that the ignition threshold charge transfer for coated sheets, honeycomb, and truss skins is respectively about 200%, 400%, 800% that of bare alloy sheet of .102 cm (.040 in.)-thickness. It was found that hot-spot ignition can occur well after termination of the arc, and that sandwich materials allow ignition only if punctured.