Biaxial deformation behaviour of AZ31 magnesium alloy: crystal-plasticity- based prediction and experimental validation

Plastic deformation of the commercial magnesium sheet alloy AZ31 under monotonic loadings was investigated by means of mechanical tests and numerical simulations. In addition to the commonly used uniaxial test two complementary mechanical tests were performed: a biaxial test using cruciform specimens and a hydraulic bulge test. Both tests lead to consistent results and provided evidence for the differential strain hardening character of the considered material. A polycrystalline aggregate was generated from the measured texture data. Simulations using the visco-plastic self-consistent (VPSC) scheme indicated the primary role of pyramidal slip in equibiaxial tension. Contours of equal plastic work have been generated using a methodology based on probing the aggregate in the space of principal strains. The contours were compared with the respective tests. Hardening parameters were fitted in order to capture the initial yield and evolution of iso-work contours. The limitations of the numerical framework's predictive capability as well as the directions for parameter identification of phenomenological yield surfaces were formulated.