On the modeling of deformation mechanisms in a Mg-3Al-1Zn alloy under biaxial tension

Although the {10-12} twinning behavior of Mg alloys under uniaxial tension and compression has been extensively investigated, the simulations of {10-12} twinning behavior under biaxial tension have rarely been reported. In this work, the EVPSC-TDT model is first employed to systematically investigate the deformation behavior of a Mg alloy AZ31 plate under biaxial tension in the RD-TD and ND-TD planes. The RD, TD and ND refer to the rolling direction, transverse direction, and normal direction of the hot rolled plate. The measured stress-strain curves and texture evolutions are well predicted and the con-tours of plastic work under biaxial tension are also constructed for comparison with experiments. The plastic response has been interpreted in terms of relative activities of various deformation modes. For bi-axial tension in the RD-TD plane, basal and pyramidal slips mainly contribute to the plastic deformation for stress ratios of Sigma RD:Sigma TD = 1:2 to 2:1. Prismatic slip becomes more active for Sigma RD:Sigma TD = 1 : 4 and 4:1. Compression twinning could be activated and so cause texture reorientation at large strains, especially for Sigma RD:Sigma TD = 1 : 1 . The six-fold feature of {10-10} pole figure could still be observed for Sigma RD:Sigma TD = 1 : 4 and 4:1 at large strain. For biaxial tension in the ND-TD plane, tensile twinning plays an important role for Sigma ND:Sigma TD > 1 : 2 , while prismatic slip contributes to plastic deformation for the other cases. With the in-crease of stress ratio from Sigma ND:Sigma TD > 1 : 1 to 1:0, the predicted twin volume fractions (VFs) at a specific strain along the ND, epsilon ND, almost linearly decrease, however, it is seen that the experimental ones at given strains along the ND do not follow such a trend with the measured twin VFs within the range of stress ratios, 2 : 1 < Sigma ND:Sigma TD < 6 : 1 , clearly being overestimated, and the difference between experiments and simulations becomes most obvious at the relatively small strain of epsilon ND = 0 . 015 . The possible reasons for the observed difference are discussed.(c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, the deformation behavior of a Mg alloy AZ31 plate under biaxial tension in the RD-TD and ND-TD planes was systematically investigated using the EVPSC-TDT model. The predicted stress-strain curves, texture evolutions, and plastic work contours were in good agreement with the experimental results. The relative activities of different deformation modes were discussed to interpret the plastic response.