Prediction of the plastic anisotropy of magnesium alloys with synthetic textures and implications for the effect of texture on formability

Abstract

Crystallographic texture is a well-known microstructural feature influencing the formability of magnesium alloys. However, the effects of individual texture characteristics common after thermomechanical processing have not been isolated due to the experimental challenge associated with varying them independently. Similarly, the effect of the propensity for twinning on formability, which both accommodates deformation and reorients the crystal, have not been systematically studied. This study uses synthetic sheet textures in conjunction with a viscoplastic self-consistent (VPSC) polycrystal plasticity model to predict deformation and formability behavior. The VPSC model was first parameterized based on experimental mechanical data and textures from fine-grained thixomolded and thermomechanically processed AZ61L. Subsequently, synthetic textures were generated to examine the effects of basal peak intensity, prismatic plane distribution, and asymmetry of the basal pole figure peak. Of these texture characteristics, basal peak strength is the most important predictor of forming behavior, with prismatic plane distribution and c-axis anisotropy resulting in comparatively weak effects. In the second part of the study, the effective critical resolved shear stress for twinning was varied, resulting in poorer forming behavior with easier twin activation. In both cases, increasing prismatic slip activity was deleterious to the predicted forming behavior.