Effects of the height reduction and strain rate on microstructure in the high temperature deformation of Ti-6Al-4V alloy

In this paper, the microstructure has been investigated in high tempreture deformation of Ti-6Al-4V alloy. Isothermal compression was conducted at the deformation temperature of 980, height reductions of 30 and 60%, and strain rates of 0.001, 0.01, 0.1 and 1.0 s^-1. The results have shown that an interaction between the height reduction and strain rate has significant effect on microstructure when deformation temperature is close to the β transus. At 980 and 60%, the volume fraction and grain size of the primary α phase decrease sharply with increasing strain rate and most of the primary α phase dynamically recrystallized at all the involved strain rates. Whereas at 980, 30% and 0.001 s^-1, the extent of dynamic recrystallization of the primary α phase is particularly low and the prior β grains occurred obvious growth and increasing strain rate inhibited the dynamic recrystallization of the primary α phase and the growth of the prior β grains.