Dynamic recrystallization and mechanical properties of high-strain-rate hot rolled Mg–5Zn alloys with addition of Ca and Sr

Abstract

Abstract Effects of the sole and the combined addition of Ca and Sr on microstructure and mechanical properties of as-cast and as-rolled Mg–5Zn alloys were carefully investigated by OM, SEM, hot-compression testing and tensile testing. Ca is more effective than Sr in the microstructural refinement of as-cast alloys. High-strain-rate rolling (HSRR) produces more deformed twins and thus provides more nucleation sites for dynamic recrystallization (DRX). The addition of Ca and Sr can promote dynamic precipitation during HSRR, the precipitation process would consume the storage energy and thus increases the critical strain value of DRX, resulting in the retarded DRX effect by the addition of Ca and/or Sr. The as-rolled Mg–5Zn–0.4Ca–0.2Sr alloy exhibits a good combination of strength and ductility, with the ultimate tensile strength of 317 MPa, the yield strength of 235 MPa and the elongation to rupture of 24%.