Dynamic globularization kinetics during hot working of TA15 titanium alloy with colony microstructure

The dynamic globularization kinetics of TA15 (Ti-6Al-2Zr-1Mo-1V) titanium alloy with a colony α microstructure during deformation at temperature range of 860-940 °C and strain rate range of 0.01-10 s −1 was quantitatively studied through isothermal compression tests. It is found that the dynamic globularization kinetics and the kinetics rate of TA15 are sensitive to deformation parameters. The dynamic globularized fraction increases with increasing strain, temperature but decreasing strain rate. The variation of globularized fraction with strain approximately follows an Avrami type equation. Using the Avrami type equation, the initiation and completion strains for dynamic globularization of TA15 were predicted to be 0.34-0.59 and 3.40-6.80. The kinetics rate of dynamic globularization increases with strain at first, then decreases. The peak value of kinetics rate, which corresponds to 20%-33% globularization fraction, increases with increasing temperature and decreasing strain rate.