Effects of post-aging cooling condition on structure and tensile properties of aged Ti

Effects of post-aging cooling condition on structure and tensile properties of aged Ti–7.5Mo alloy

Chen, Yen-Chun / Lin, Jiin-Huey Chern / Ju, Chien-Ping

Abstract The present study investigated the effects of post-aging cooling condition on tensile properties of an aged Ti–7.5 wt% Mo alloy. Experimental results indicated that the solution-treated (ST) Ti–7.5Mo samples were comprised substantially of α″ phase, while all aged samples demonstrated the co-existence of α′ and β phases therein. The relative amount of β phase retained in the aged alloy was found sensitive to post-aging cooling condition. Water-quenched (WQ) alloy had the highest β phase content, while furnace-cooled (FC) alloy had the lowest β phase content. The Mo concentration in β phase was also sensitive to post-aging cooling condition. The average Mo concentration in β phase was found highest in FC samples and lowest in WQ samples. Compared to ST samples, all aged samples demonstrated significant increases in yield strength and modulus values, along with decreases in elongation. The effect of post-aging cooling condition on microhardness was similar to that on strength.

Highlights • Cooling condition on tensile properties of aged Ti–7.5Mo alloy was investigated. • Aged samples under all cooling conditions comprised both α′ and β phases. • Alloy properties were sensitive to both β phase content and Mo content therein. • β phase content was highest in WQ samples and lowest in FC samples. • Mo content in β phase was highest in FC samples and lowest in WQ samples.