Materials Science and Engineering A-structural Materials Properties Microstructure and Processing | 2019
Numerical investigation of the influence of twinning/detwinning on fatigue crack initiation in AZ31 magnesium alloy
Abstract
Abstract An analysis of the fatigue behavior of rolled AZ31 magnesium alloy through numerical simulations of polycrystalline aggregates using the crystal plasticity finite element method is presented. A phenomenological pseudo-slip model including twinning, detwinning and subsequent slip in the twinned region was considered in this study. It was calibrated against uniaxial monotonic and cyclic experiments on rolled AZ31 Mg alloy. Multiple periodic two-dimensional synthetic microstructures were generated based on morphological and crystallographic data obtained from electron backscattering diffraction (EBSD) measurements. Fatigue simulations were conducted at different stress amplitudes and mesoscopic non-local fatigue criteria for slip-induced and twin-induced crack initiation were investigated. It was observed that basal slip and twinning-detwinning are the main deformation mechanisms taking place during cyclic loading but that these deformation modes generally occur in different grains. The comparison of the investigated criteria with experimental data also revealed that the twin-induced criterion exhibit better trends in terms of mean behavior, relative dispersion and stress amplitude sensitivity compared with the slip-induced criterion. Finally, the predictive capabilities and limitations of the current modeling approach are discussed.