A theoretical prediction of twin variants in extruded AZ31 Mg alloys using the microstructure based crystal plasticity finite element method

A resolved shear stress (RSS) criterion and the microstructure-based-crystal plasticity finite element method (MB-CPFEM) were used to analyze the activation of twin variants in extruded AZ31 Mg alloys during ex situ uniaxial compression. The RSS criterion, which is simply based on the Schmid factor, failed to predict the activation of twin variants consisting of the second-highest RSS and the third-highest RSS. In contrast to the RSS criterion, the MB-CPFEM based on a quasi-3D finite element mesh successfully predicted the activation of twin variants consisting of the highest RSS and the second-highest RSS. The MB-CPFEM demonstrated that local fluctuation of the stress field induces the activation of twin variants with the second-highest RSS during uniaxial compression.