Microstructures evolution and enhanced performance of ZK60 magnesium alloys manufactured by multi-path asynchronous warm rolling

Abstract

Magnesium (Mg) alloy is one of the most promising lightweight structural materials. Rolling is the main method of efficient mass production of Mg alloy sheets. However, the limited number of slip systems of Mg alloys with hexagonal close packed (HCP) crystal structure leads to poor deformation properties, strong basal texture formed during unidirectional rolling and severe anisotropy of the sheets. The new technology of Multi-Path Asynchronous Warm Rolling (MPAWR) is used in the manufacture of ZK60 Mg alloy sheets in order to solve these problems. The results show that under the same rolling path, the number of twins in the microstructures of ZK60 alloys decreases with the increase of roll speed ratio (RSR), the grain size decreases and the uniformity increases. At the same RSR, the number of twins in ZK60 alloys increases first and then decreases with the change of rolling path (A→B→C), and the grain size decreases and the uniformity increases. The dynamic recrystallization of ZK60 alloys during warm rolling can be promoted by the change of rolling path (A→B→C) and the increase of different RSR, resulting in the increase of grain refinement, uniformity and random orientation (the weakening of basal texture intensity). Compared with the synchronous unidirectional rolling and heat treatment process, MPAWR process can significantly improve the strength, plasticity and rolling deformation efficiency of the alloys at the same time, and effectively reduce the anisotropy of the alloy’s properties.