Strength differential effect and anisotropy of Mg–1.9Mn–0.3Ce (wt-%) alloy subjected to high-rate loadings

Abstract

Tension and compression tests for a rare-earth-containing alloy sheet, Mg–1.9Mn–0.3Ce (wt-%), are performed under quasi-static and high-rate loadings along the rolling, transverse and normal direction, and stress – strain responses exhibit positive strain-rate dependence. Empirically based Johnson-Cook constitutive model is modified to describe the rate-dependent plastic deformation in multiple loading directions. A strong strength differential effect persists, and such effect is shown to be stronger at high strain rates. A weak in-plane anisotropy exists in the initial yielding and subsequent strain hardening behaviour as well as strength differential effect. In contrast, the out-of-plane anisotropy in compression is apparent and is approximately rate insensitive. Microstructural observations indicate that twinning plays the key role for the enhancement of strain-hardening rate under high strain-rate deformation.