Modelling of plastic deformation in magnesium

Abstract

In the present contribution, a viscoplastic rate-dependent constitutive model based on Schmid's law has been used to designate the activity level of pure magnesium deformation systems. A crystal plasticity model in the framework of finite elements was used to investigate the deformation systems on the scale of single-and polycrystals. Twinning has been modelled by coupling between finite shear and subsequent lattice rotation. It is shown for pure magnesium, that twinning can affect the slip systems activities and therefore changes the hardening mode within the crystal as a result of crystal reorientation. Furthermore, the twinning evolution during in plane and through-thickness deformation of pure Mg polycrystal rolled plate reveals that tensile {10-12} and compression {10-11} twinning have different effects on the mechanical response.

Finite element simulations of notch tip fields in magnesium single crystals

“…This modified crystal plasticity theory, implemented in finite element solution procedures, has been widely used to analyze the deformation behavior, stress distributions, texture evolution and formability in HCP metals (Salem et al 2005;Brown et al 2005;Graff et al 2007;Knezevic et al 2010;Izadbakhsh et al 2011;Fernandez et al 2011;Choi et al 2011). Several hardening models have been proposed to represent slip and twin interactions in Mg for incorporation in the above crystal plasticity formulation (Graff et al 2007;Homayonifar et al 2009;Zhang and Joshi 2012). Among these models, the one suggested by Zhang and Joshi (2012) accounts for both compression and tensile twinning.…”

“…But such simulations have their limitations from the standpoint of spatial and temporal scales, choice of interatomic potential (in case of atomistic modeling), representation of plastic slip through dislocation motion, modeling of all twin variants and application of boundary and load conditions (in case of phase field method). Further none of these techniques have been quantitatively benchmarked with experimental data unlike crystal plasticity simulations (Salem et al 2005;Homayonifar et al 2009;Zhang and Joshi 2012). Also, as noted below, a recent atomistic simulation of fracture in Mg single crystals predicts the occurrence of a TT variant that is not observed in experiments (Tang et al 2011a).…”