Anisotropy, tension-compression asymmetry and texture evolution of a rare-earth-containing magnesium alloy sheet, ZEK100, at different strain rates and temperatures: Experiments and modeling

Abstract

The mechanical response and texture evolution of rare-earth-containing magnesium alloy sheet, ZEK100, are measured under uniaxial (tension and compression) loading along the rolling direction (RD), 45° to rolling direction (DD), transverse direction (TD) and normal direction (ND), at the strain rate of 10−4 to 3 × 103 s−1, and temperatures of 22 °C & 150 °C. Texture evolution is measured at strain increments between 2 and 10% in compression and tension at both 10−4 and 3 × 103 s−1, and at 22 °C and 150 °C. Measured pole figures reveal relatively weak basal pole intensity with a spread of basal poles from ND toward TD. Consequently, the yield stress in both tension and compression is the largest in RD and decreases with change in orientation from RD to TD. The material exhibits positive strain rate sensitivity as well as tension-compression asymmetry and anisotropy that are a function of temperature and strain rate. Strain hardening behavior in both tension and compression represents the characteristics of twinning dominated deformation even at elevated temperatures. Crystal reorientation due to extension twinning was observed both in compression along all directions, and in tension along the TD. While the flow stress in compression increases with the increase of strain rate from 10−4 to 3 × 103 s−1, differences in measured textures between the two strain rates are negligible. A reduced-order crystal plasticity model that defines extension twinning, basal <a> slip, and non-basal slip as the deformation mechanisms, is used to model the experimental results and to give an insight in the active deformation mechanism. The model captures the work hardening, anisotropy and tension-compression asymmetry behavior of the material at different strain rates and temperatures.