Role of unusual double-peak texture in significantly enhancing cold rolling formability of AZ31 magnesium alloy sheet
(1. Beijing Institute of Spacecraft System Engineering, Beijing 100094, China;
2. College of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054, China;
3. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China)
2. College of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054, China;
3. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China)
Abstract: Multi-pass cold rolling experiments were performed on AZ31 magnesium alloy sheet with unusual double-peak texture, where basal poles tilt about ±40° away from normal direction to rolling direction. This adopted sheet was fabricated by a novel technology of equal channel angular rolling and continuous bending process with subsequent annealing. Experimental results confirm that such an unusual double-peak texture contributes to a huge improvement of accumulated reduction up to 39.2%, which is over twice as much as that (18.3%) in sheet with strong basal texture. Optical microscopy and electron backscatter diffraction measurements demonstrate that the evolution of microstructure and texture in sheet with unusual double-peak texture is quite different from that in sheet with strong basal texture. Schmid factor (SF) analysis confirms that sheet with unusual double-peak texture possesses obviously large SF values for basal áa？ slip and extension twin (ET) and remarkably small SF values for prismatic áa？ slip and pyramidal ác+a？ slip during cold rolling process. Therefore, basal áa？ slip and ET will be activated more frequently in sheet with unusual double-peak texture to sustain plastic strain, leading to significant enhancement in cold rolling formability.
Key words: AZ31 magnesium alloy; non-basal texture; cold rolling process; microstructure evolution; deformation mechanism