The Effect of Lath Orientations on Oxygen Ingress in Titanium Alloys

Oxygen ingress is critical to the high-temperature behavior of alpha + beta titanium alloys. The current study investigated the impact of crystallographic orientation on the ingress of oxygen in Ti-6Al-2Sn-4Zr-2Mo+Si, for colony microstructures. The oxygen ingress depth was estimated using EDS, EPMA, microhardenss, and optical microscopy. Results indicate that the depth of oxygen ingress in colony microstructures is dependent on α-laths’ orientation relative to the ingress direction. A finite element model was developed to simulate the oxygen ingress in three different lath orientations. Results were used to calibrate the effective diffusivity for the colony microstructure. The relationships between the lath orientations, hardness, and ingress depth were discussed.