Loading path dependent distortional hardening of Mg alloys: Experimental investigation and constitutive modeling

In this work, the loading path dependent distortional evolution of yield surfaces is probed experimentally on an extruded AZ31 Mg alloy. More explicitly, the initial yield surface, subsequent yield surfaces with pre-tension and with pre-tension-torsion are observed; the loading path effect on the anisotropy is discussed based on the underlying deformation mechanism in terms of microstructure evolution. In addition, experimental comparison between the yield surface and the Equivalent Plastic Work Contour (EPWC) is performed with a shared stress state. Next, a thermodynamically consistent directional distortional hardening model is employed to capture the anisotropic mechanical behavior. The directional distortional evolution of the normalized yield surfaces under non-proportional loading paths is predicted for extruded AZ31 Mg alloy.