Effect of shear deformation on plasticity, recrystallization mechanism and texture evolution of Mg–3Al–1Zn alloy sheet: Experiment and coupled finite element-VPSC simulation

Abstract

Microstructure characterization and texture evolution of multi-passes isothermal symmetry and asymmetry rolling, or namely differential speed rolling (DSR), of Mg–3Al–1Zn alloy sheets were systematically investigated at different temperatures and strain levels. Also, two scale model coupling finite element and a visco-plastic self-consistent model (FE-VPSC) was employed. Results indicate that the predominant dynamic recrystallization (DRX) mechanism transits from twinning DRX at 150 °C to continuous DRX at 250 °C attributed to the distinctively activated deformation modes. It was found that shear deformation induced in DSR plays a crucial role on the activation of deformation modes and related DRX mechanisms. Based on the calculation of effective Schmid factor (ESF), shear deformation is believed to promote the activation of contraction twinning and pyramidal <c+a> slip by increasing their ESFs. Furthermore, the concentration of grain orientations caused by profuse operation of basal <a> slip can facilitate the activation of twinning and pyramidal <c+a> slip during DSR. As a result, twinning DRX dominated region was obviously enlarged owing to a larger fraction of twinning at low temperature (<200 °C). Meanwhile, profuse activation of pyramidal <c+a> slip at high temperature (>200 °C) can accelerate the continuous DRX. After annealing at 250 °C for 1 h, fine grains with an average size of 3.36 μm and a large basal titled angle (∼26°) were attained for the twinning DRX controlled sheet at 150 °C.