The reaction of titanium with hydrogen gas at ambient temperatures

A study of factors affecting the reaction between titanium and hydrogen gas at ambient temperature has been conducted. Under certain conditions, extensive surface hydriding or absorption of hydrogen can occur at temperatures between 75 ° and 130 °F. A reaction is favored by ultra-high purity hydrogen, galling or abrasion of the titanium surface, especially if done under oil, vacuum annealing to dissolve surface oxides, and increased hydrogen pressure. Alpha-beta or beta titanium alloys appear to react more rapidly than alpha alloys and absorb large quantities of hydrogen before hydriding occurs. Alpha alloys form a reasonably adherent surface hydride layer. Stress applied to the titanium material during exposure to hydrogen gas appeared to have little effect on the reaction behavior. Reaction could be retarded, and in some cases prevented entirely, by acid pickling the titanium material to remove surface contamination, by aging the titanium material in air for a period of about 150 h to allow any surface film damage accompanying processing to heal, and by decreasing the purity of the hydrogen gas. Based upon the present studies, the use of titanium alloys to contain hydrogen gas at ambient temperatures must be approached with caution.