Microstructure evolution during hot deformation of Ti-6Al-4V double cone specimens

Double cone specimens of Ti-6Al-4V alloy with a bimodal starting structure have been heat treated and then compressed at temperatures near to the beta transus (Tβ + 70 K) with strain rates between 0.1 and 5 s-1. The deformed specimens were immediately quenched to conserve the phase distribution. Alpha grains maintain their morphology during deformation in the alpha + beta region up to 0.2 of strain. Dynamic recrystallization of the alpha grains is observed using EBSD technique at strains of 1 for all the strain rates. Dynamic recrystallization of beta phase takes place in samples deformed above the beta transus temperature. There, the beta grains’ shape does not change up to 0.3 of strain. The grade of recrystallization depends on the previous heat treatment, and the recrystallized grain size on the strain rate and the temperature of deformation.