A novel continues multi-shear extrusion process on the microstructure and mechanical property evolution of AZ31 magnesium alloys

Abstract

This study presents a novel technology in the fabrication of AZ31 Mg alloy sheets using continuous shear extrusion (CSE) with multiple shear platforms at 340 °C. Compared with the conventional extrusion (CE), an asymmetric shear deformation was introduced so that the basal texture deflects towards to extrusion direction. Through finite element simulation, it was found that the differences in flow velocity and strain distributions along the thickness direction can be achieved by introducing the shear strain through CSE technology. Finer grains and more uniform microstructure were obtained in CSEed Mg samples compared to conventional extrusion. The average grain size decreased from 6.33 μm in CE samples to 3.94 μm in CSE samples, and 3.39 μm in CSE-II samples. The continuous asymmetric shear force also led to the basal plane inclining approximately 15° towards the extrusion direction, leading to a weakening of basal texture intensity. In terms of mechanical properties, the CSE Mg plates exhibited higher yield strength (YS), ultimate tensile strength (UTS), and fracture elongation (FE) along the extrusion direction. These improvements in mechanical performance can be attributed to enhanced work hardening ability, texture weakening, finer grains generation, and the dislocation strengthening induced by shear strain.