The surface oxide film on titanium acts as an effective barrier to penetration by hydrogen, but disruption of the oxide film allows easy penetration by hydrogen. Absorption of several hundred ppm of hydrogen results in embrittlement and the possibility of cracking under conditions of stress.
Titanium can absorb hydrogen from environments containing hydrogen gas.
In the presence of pure hydrogen gas under anhydrous conditions, severe hybriding can be expected at elevated temperatures and pressures. Titanium is not recommended for use in pure hydrogen because of the possibility of hydriding should the oxide film be broken. This probably accounts for the fact that titanium is being used successfully in many process streams containing hydrogen with very few instances of hydriding being reported. A more serious situation exists when cathodically impressed or galvanically induced currents generate nascent hydrogen directly on the surface of titanium. The presence of moisture does not inhibit hydrogen absorption of this type.