Investigation into the Compatibility of Hydrogen and Titanium
This paper presents an investigation conducted into the compatibility of hydrogen and titanium, The Apollo Block 1 Cryogenic Hydrogen Storage Tanks utilize pure titanium tubing, Ti-55A, and 5Al-2.5Sn ELI titanium components. During the initial period of production and testing the phenomenon of titanium-hydrogen incompatibility under certain conditions was discovered, The investigation during the first series of tank malfunctions was concentrated on determining the cause of failure in the weld beads of the titanium tubing and the titanium alloy components and provide a corrective action to continue the tank fabrication. The original analysis revealed a problem with welding that was attributed to contamination, However, further investigation attributed the cause to titanium hydrides in the weld beads of the titanium alloy parts and the Ti-55A tubing. There are also indications that the hydride reaction observed may not be limited to weld joints, since surface hydrides have been observed in a section of tubing several inches away from a weld joint. In order to determine the cause of titanium hydriding formation, a series of test parts were devised to control pressure, temperature, cycles, and welding variables.
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