Research on the hot tensile deformation mechanism of Ti-6Al-4 V alloy sheet based on the α + β dual phase crystal plasticity modeling

Abstract

In order to predict the microstructure evolution of α + β dual phase Ti-6Al-4 V alloy during high temperature tensile deformation and reveal its deformation mechanism, a dual phase crystal plasticity simulation model based on dislocation density was established. The uniaxial hot tensile test of Ti-6Al-4 V alloy sheets was carried out at different temperatures with the same strain rate, and the stress-strain curves were obtained. The initial microstructure of the undeformed Ti-6Al-4 V alloy sheet was obtained by electron backscatter diffraction (EBSD). Based on the obtained microstructure information, a representative volume element (RVE) containing α + β phase was constructed. The validity of the model was verified by comparing the stress-strain curves obtained from experiments and full field crystal plasticity simulations. According to the crystal plasticity simulation model, the deformation inhomogeneity and dislocation density evolution of Ti-6Al-4 V alloy at high temperature were studied. For α phase, the growth rate of dislocation density in basal slip system and prismatic slip system decreases with the increase of temperature. For β phase, the dislocation density growth rate of all slip systems increases with the increase of temperature. Dislocation density concentration occurs at the phase boundary of the two phases and decreases with the increase in temperature.