Fabrication of MgAlZnMn alloy sheets with homogeneous fine-grained structures using high strain-rate rolling in a wide temperature range

Abstract

It has been difficult to produce magnesium alloy sheets using conventional rolling due to the poor formability of magnesium alloys. Here we report that high strain-rate rolling (HSRR) has been successfully used to fabricate magnesium alloy sheets in a wide temperature range of 250–400°C. The microstructure, texture and mechanical properties of the HSRR sheets were compared with a conventionally rolled sheet. The HSRR sheets are all of much finer and more homogeneous microstructures than the conventionally rolled sheet, which is attributed to the specific deformation mechanisms operating consecutively during HSRR that include the formation of a high density of deformation twins, subsequent continuous dynamic recrystallization (DRX), as well as discontinuous DRX at the grain boundaries of the previous DRX grains. Compared with the conventionally rolled sheet, the HSRR sheets have a weaker basal texture because of the complete DRX. The HSRR sheets demonstrate both excellent strength and good ductility, resulted from the combined effects of grain refinement and homogeneity, low dislocation density and weakened basal texture.