Modeling the deformation behavior of a rolled Mg alloy with the EVPSC-TDT model

Magnesium and its alloys are characterized by a strong basal texture, resulting in severe anisotropy at low temperature. To investigate the deformation behavior of a rolled magnesium alloy AZ31 at room temperature, uniaxial compression and tension experiments along four directions were performed and modeled using both the EVPSC-TDT and the VPSC-TDT models. The required threshold stress parameters were determined by curve fitting. Similar parameters were found to fit relatively well for all the experimental flow curves for both models. The predictions of the two models are also very similar beyond the elastic strain. The simulations reveal only a very limited increase with strain of the threshold stress for basal slip, which is favorable for basal texture development, whereas the threshold stresses for other deformation modes increase significantly. A discrepancy between experiments and simulations suggests that depending on loading condition strain accommodation between grains by basal slip varies in ease. A deformation-path dependent discrepancy between the modeled stress and the experimental curves is also found for the threshold stress for {10-12} twinning. This discrepancy is assumed to be related to the larger number of twin variants activated in tension as compared to compression, due to twin boundary hardening. A {10-12} twin-associated hardening, primarily on pyramidal slip and prismatic slip systems, evaluated to be about 15 MPa for both through thickness tension and in-plane compression, is included in the model via the use of a higher latent hardening modulus these slip systems by twinning.