Effect of holding time between cryogenic treatment and tempering process on microstructural and mechanical properties of Ti-6Al-4V alloy

This study investigated the effects of cryogenic treatment (CT) and tempering process on the mechanical properties of Ti-6Al-4V alloy. CT samples were exposed to atmosphere for various time intervals (0 h, 6 h, 24 h, 72 h) before tempering to explore the implication of temperature recovery time on overall mechanical performance. Results revealed a significant improvement in the hardness of CT samples compared to un-treated (UT). Interestingly, the hardness showed dependency on atmospheric exposure times of CT samples. The variation of Ti-6Al-4V phases generated during the cryogenic treatment was recovered as it was exposed to the atmosphere, and the degree of recovery was rather different depending on the exposure time. However, no notable differences in cross-sectional hardness and room temperature tensile properties were observed between the UT and CT samples. Hence, it was concluded that the CT only affected the surface hardness of Ti-6Al-4V alloy.