Titanium Biocompatibility Oxide Layer

Titanium always has a thin, hard oxide layer on its surface in air. This provides corrosion protection and makes the material biocompatible. When welding, you absolutely must protect the molten pool from air, otherwise the material absorbs oxygen and nitrogen and becomes brittle and porous. If you see the weld seam turning blue or discolored after welding, the shielding was not tight and the oxide layer has burned. In that case, you must grind off the color before the part is allowed in the body.