Superplastic Deformation Behaviors and Power Dissipation Rate for Fine-Grained Ti-6Al-4V Titanium Alloy Processed by Direct Rolling

Abstract

Fine-grained Ti-6Al-4V titanium alloy plates were manufactured using a direct rolling approach, and a series of superplastic tensile tests were conducted at varying temperatures and strain rates. The maximum tensile elongation of 816% was obtained at 810 °C and 5 × 10−4 s−1, and the superplastic flow behavior was dominated by a strain-induced grain boundary slip. In addition, the superplastic behaviors of the alloy were investigated, and the α-and β-phase Gibbs free energy was calculated. The vital role of phase β in the transformation was discussed from a thermodynamical perspective. A power dissipation rate model of Ti-6Al-4V during the superplastic deformation was built and used to predict the energy changing laws in the dynamic recrystallization and grain boundary sliding during the superplastic deformation.