A crystal plasticity model for describing the anisotropic hardening behavior of steel sheets during strain-path changes

Abstract

Various macro-mechanical constitutive descriptions were developed for the analysis of hardening under strain path changes, but these models are not directly related to microstructural features such as crystallographic texture, slip/twin systems and dislocation evolution. As an alternative method, micro-mechanical constitutive models based on crystal plasticity have been proposed to model strain path changes. Particularly, the present study focuses on a viscoplastic self-consistent crystal plasticity model (i.e., VPSC-RGBV), which accounts for the various microstructural features including the accumulation and the annihilation of dislocations due to slip activities; and the latent hardening due to interactions between dislocations gliding pertaining to different slip planes. The simulation results of the VPSC-RGBV model are compared with those of a Homogeneous Anisotropic Hardening model (HAH), which is a macro-mechanical constitutive model developed to describe the flow stress evolution of metals undergoing complex loading histories. The differences between simulated and experimental results under non-proportional loading are demonstrated in terms of 1) flow stress-strain curve, 2) instantaneous r-value after strain-path change and 3) yield surface evolution. Finally, potential improvements for VPSC-RGBV model are suggested.