A New Approach to Study the Effect of Microstructure Evolution on the Mechanical Response of AZ31 Magnesium

At room temperature, magnesium and its alloys display a strong tension-compression asymmetry and anisotropy peculiar to plastic deformation that arise from the activation of basal and non basal slip and extension, contraction and double twinning which in turn induce evolution of the crystallographic structure, ultimately leading to poor formability. In this paper, a novel step-by-step procedure for determination of the material parameters of a viscoplastic self-consistent (VPSC) crystal plasticity model is presented. It is based on an in depth analysis of the deformation systems potentially active and mechanical data. Using the proposed calibration procedure, it is demonstrated for the first time that the VPSC model can predict both the macroscopic stress-strain curves and the evolution of the microstructure. Comparison between observed and predicted textures as well as twin volume fractions are provided (including strain paths that were not used for the calibration of the model). Furthermore, for the first time, it is shown that the model can predict the response in simple shear.