Abstract
This paper presents a crystal-plasticity finite-element simulation of deformation behavior during unloading in a magnesium alloy sheet considering twinning and detwinning. A detwinning model proposed by the authors was employed. The detwinning model could be employed in the framework of a twinning model proposed by Van Houtte (1978), with which shear strain and lattice rotation due to detwinning could be taken into account in the crystal-plasticity finite-element simulation. The material parameters were determined so as to obtain reasonable fits with stress-strain curves obtained from experiments of a rolled AZ31 magnesium alloy sheet. A loading-unloading process under in-plane compression was simulated, focusing on the activities of twinning and detwinning. A pronounced inelastic deformation arose during unloading in the simulation, and this tendency was in good agreement with the experimental result. We found that the pronounced inelastic deformation arose because of not only the activation of detwinning during unloading but also the dispersion of crystal orientations owing to the activity of twinning during loading.
