Influence of heat treatment processes on microstructure evolution, tensile and tribological properties of Ti6Al4V alloy

The influence of heat treatment processes on microstructure, tensile and tribological properties of Ti6Al4V alloy was investigated. The specimens were heated for 30 min at 925 °C and then cooled at various rates by water quenching, air cooling, and furnace cooling. After that, the samples were aged for four hours at 600 °C. Three phases make up the microstructure: primary α-phase (α(p)), secondary α-phase (α(s)), and retained β-phase (β(r)). Cooling in the air and water followed by aging (AC + Aging and WQ + Aging) resulted, α(s)-phase precipitating inside β(r)-phase. The highest hardness of 35 HRC was recorded for WQ + Aging specimen due to existence of a high amount of β(r)-phase and precipitation of α(s)-phase. On the other hand, the lowest hardness of 26 HRC was obtained for the FC specimen. AC specimen achieved the highest elongation value of 14%. However, WQ + Aging specimen exhibited the highest ultimate tensile strength of 1028 MPa. For WQ + Aging and AC + Aging specimens, the ideal balance of strength and elongation was discovered. The wear resistance of solution-treated specimens was significantly improved by the aging process and 125% improvement could be achieved in WQ compared to WQ + Aging specimens.