Shear stress induced homogeneous shear band deformation during the electropulsing assisted asymmetric rolling of Mg1Gd alloy: Experiment and VPSC simulation

Abstract

Fabrication of Mg alloy thin sheet/strip is generally a tough job due to the basal texture induced severe plastic anisotropy and subsequent edge crack. In this study, Mg1Gd (G1) alloy thin strips were fabricated by electropulsing assisted asymmetric rolling (ASR), and conventional symmetric rolling (SR) for comparison. It has been found that edge crack of G1 alloy strip during ASR was substantially suppressed by the additional shear stress, which had close connections with the enhanced activities of prismatic <a> slip system, twinning and the formation of densely and homogenously distributed shear bands, according to the results of electron back scatter diffraction (EBSD), finite element (FE) and visco-plastic self-consistent (VPSC) simulation. More importantly, compared with the SR sample, the ASR sample showed not only increased tensile strength (246 MPa) and elongation-to-failure (21.9 %) but also improved plastic anisotropy in terms of Lankford value (r-value). The enhanced mechanical properties of ASR sample were mainly resulted from its more significant grain refinement and texture randomization after recrystallization.