Shear-Coupled Multiaxial Deformation Behavior of Rolled AZ31B Magnesium Alloy

The mechanical behavior of a rolled AZ31B magnesium alloy under uniaxial loading, combined axial torsion, and combined axial-transverse shear loading with different strain paths has been investigated, which intentionally generates uniaxial, biaxial, and triaxial stress states, respectively. Under multiaxial loading, one stress component is not only determined by the corresponding strain component, but also significantly affected by other strain components, due to strain accommodation. The underlying mechanisms associated with different loading paths are analyzed in terms of the activities of various deformation mechanisms, the slip deformation kinematics, and the general Schmid factor. Under all loading cases, basal slip is the primary deformation mode responsible for the axial-shear strain accommodation. In the cases where axial tension is presented, the extension twin starts to play a substantial role. Under combined axial-transverse shear, the prismatic slip participates more additionally since it aligns directly with the shear strain component. Pyramidal slip contributes to the deformation once axial compression strain is dominant. The yield surfaces under shear-coupled multiaxial loading paths are fully constructed by traversing all the strain paths. The yield surface evolves with a drastic change both in shape and magnitude, due to the different combinations of the active deformation mechanisms at various strain levels. The findings in the current work, especially the yield surface associated with the multiaxial stress state, are invaluable in enriching the plasticity theory of magnesium alloys.