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

Abstract

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.