The effect of initial texture on micromechanical deformation behaviors in Mg alloys under a mini-V-bending test

Abstract

Micromechanical deformation behaviors of E-form fine grain (EFG), E-form coarse grain (ECG), and AZ31 magnesium (Mg) alloys were investigated and compared using a mini-V-bending test. EFG and ECG Mg alloys with a weaker texture showed better bendability compared with AZ31 alloy that has a stronger texture. The evolution of the microstructure and microtexture during the mini-V-bending process was experimentally analyzed via an electron back-scattered diffraction (EBSD) technique. This study was focused on the effect that deformation twinning exerts on the strain localization and crack initiation. The twin bands (TBs) developed in the tension zone of bent specimens found to be closely related to the strain localization and crack initiation during the mini-V-bending process. A resolved shear stress (RSS) criterion and microstructure based crystal plasticity finite element method (CPFEM) were used to theoretically predict the activation of {101¯2} tension (TTW) and {101¯1} compression (CTW) twins in Mg alloys under a mini-V-bending process. RSS analysis indicated that EFG and ECG Mg alloys are more favorable for the activity of TTW and less favorable for the activity of CTW when compared with AZ31 Mg alloy during a mini-V-bending process. However, RSS analysis was not effective in quantitatively predicting twin development. The relative activities of six deformation modes, accumulated twin fractions, and accumulated plastic strains were simulated via microstructure-based CPFEM modeling. Compared with RSS analysis, CPFEM precisely explained the twin behavior that has been experimentally observed in ECG and AZ31 Mg alloys.