Behavior of hot deformation and its effect factors for TC4 titanium alloy

True stress-true strain curves of Ti-6Al-4V titanium alloy were measured by Gleeble-1500 Formaster Press Simulator at different temperatures and different strain rates. The microstructures of the alloy before and after deformation were observed using optical microscope. The effect of deformation temperature, strain rate, original microstructure and heat treatment processing on hot deformation behavior of Ti-6Al-4V alloy were analyzed. The results show that at 8.3 × 10^-3/s strain rate, the dynamic recovery is the main softening mechanism in the alloy deformed at 600°C, and the dynamic recrystallization is the main softening mechanism in the alloy deformed at 800°C-900°C. However, the dynamic recovery and the dynamic recrystallization may occur simultaneously. The hot deformation resistance of the alloy is improved by quenching or aging, and less sensitive to the strain rate in the range of 8.3 × 10^-2/s-8.3 × 10⁰/s, but the hot deformation resistance decreases greatly at 8.3 × 10^-3/s strain rate when the alloy is deformed at 600°C. The flow stress of widmanstätten structure is generally higher than that of equiaxed grain structure.