Titanium Hydrogen Embrittlement
Impairment of mechanical toughness through the diffusion of atomic hydrogen into the titanium lattice and the formation of brittle hydride phases.
Hydrogen is a real problem with titanium. If it diffuses into the material during welding, hard, brittle hydrides form. This makes the weld and the heat-affected zone brittle, cracks develop, and the part fails under load. The main source of hydrogen is almost always moisture – in the shielding gas, on the workpiece, or in the filler material. That's why you have to be meticulous about cleanliness when welding and use absolutely dry gas. The shielding must also be correct until the material has cooled down, otherwise it will pick up hydrogen from the ambient air. If you follow this, you usually have the issue under control. A subsequent heat treatment for degassing is rarely necessary in practice if the boundary conditions were kept clean beforehand.