Titanium Grade 23 | Ti6Al4V ELI | 3.7165 „Alpha case“ after heat treatment in air

α titanium can solve a few percent oxygen. Therefore, when oxygen diffuses in under elevated temperature, the α-phase (“Alpha case”) forms along the surface, here also seen on the inner seam of a wormhole (weld seam bond lack of fusion). This brittle and crack-prone phase can only be avoided by heat treatment in a vacuum.