Characterization of the hot deformation behavior and microstructural evolution of Ti-6Al-4V sintered preforms using materials modeling techniques

The hot deformation behavior of Ti-6Al-4V sintered preforms was investigated by hot compression tests over temperatures from 800 to 1100 °C and strain rates from 0.001 to 10.0 s−1. The flow curves for the α + β regimes exhibited continuous flow softening and broad oscillation after the peak stress under all of the processing conditions. Otherwise, for the β field, steady-state flow stress was obtained or stress oscillation appeared after the peak stress. In the α + β field, the dynamic globularization and platelet buckling/kinking were observed at lower and higher strain rates, respectively. Unlike in the α + β regions, dynamic recrystallization was found at higher strain rates in the β ones. The apparent activation energies for hot deformation in the α + β and β regimes from kinetic modeling technique were estimated to 147.35 and 233.95 kJ mol−1, respectively. The efficiency of power dissipation over all of the deformation conditions was also calculated by using dynamic material models and schematized into a processing map. The highest value was predicted to 46% at a temperature of 945 °C and at a strain rate of 0.001 s−1, and the processing condition seemed to be optimal for hot deformation of the Ti-6Al-4V sintered preforms.