Effects of Pre-Strain on the Evolution of Microstructure and Strain Hardening of Extruded Az31 Magnesium Alloy

Abstract

Pre-compression 3% and pre-stretch 3% subsequent annealing at 200ºC for 2h are conducted on AZ31 magnesium alloys, then inverse tensile and compressive deformation are carried out at room temperature, respectively. During inverse tension 3% deformation on 1 st pre-compression samples, detwinning behavior happens; after 2 nd pre-compression 3%, the volume fraction of {10-12} extension twins decreases comparing with 1 st pre-compression. Due to the interaction of dislocation and induced twinning lamellas, strain hardening rate (θ) increases on 1 st and 2 nd pre-compression samples. {10-12} tensile twinning is restrained during inverse compressive deformation by pre-stretch process. Owing to the decreasing amount of twins, the texture strengthening in compressive deformation weakens. So the slop of stage III in strain hardening rate sustaining reduces after 1 st pre-stretch 3% and 2 nd prestretch 3% deformation during inverse compression deformation.