Flow behavior and microstructural evolution during hot compression of TA15 titanium alloy

The samples of TA15 titanium alloy were hot compressed in the temperature range of 550-1000°C at constant strain rate from 0.01 s^-1 to 1.0 s^-1. The flow behavior and microstructural evolution during hot deformation of TA15 alloy were investigated, based on which the hot working parameters of TA15 alloy were selected. The results show that with the increase of deformation temperature and decrease of stain rate, the flow stress decreases gradually, but the magnitude of stress drop varies with the increase of temperature in different temperature intervals. According to the flow stress and deformation microstructure, the deformation behavior can be classified into three types as working hardening (550-600°C, α+β phase), dynamic recrystallization (650-900°C, α+β phase) and dynamic recovery (950-1000°C, β phase). The main softening mechanism is dynamic recrystallization (DRX) of α phase in α+β phase zone and dynamic recovery (DRV) of β phase in β phase zone. As the stain rate decreases dynamic recrystallization of α phase proceeds more adequately in α+β zone and the β subgrains of dynamic recovery have the tendency to grow in β zone. The reasonable temperature for warm forming of TA15 alloy is in the range of 600-700°C, which has been verified by warm spinning experiment of tube workpieces.