Effect of thermal exposure on the room temperature tensile properties of Grade 2 titanium

During exposure to the atmosphere at elevated temperature an α stabilised region develops on the surface of titanium alloys, the thickness of which is dependent on the temperature and cumulative time of exposure. In this research, samples of ASTM Grade 2 titanium were treated at a range of temperatures and times to investigate the effects of surface oxygen contamination on tensile properties. The stabilised α region that developed during the heat treatment was brittle and cracked easily after small amounts of strain, however these cracks were mostly arrested at the boundary between the transformed region and the bulk metal. The tensile strength of the heat-treated samples was compared to predicted values that assumed the transformed α-region did not contribute to the load bearing area. The comparison is reasonable when predicting the strength of samples treated at temperatures below the bulk α–β transition temperature but has limitations when applied to higher temperatures.