Effect of texture types on microstructure evolution and mechanical properties of AZ31 magnesium alloy undergoing uniaxial tension deformation at room temperature

摘要

Influence of texture type on mechanical properties and the evolution of microstructure and texture is thoroughly investigated via uniaxial tension experiment along rolling direction (RD) at room temperature on two different AZ31 alloy sheets. Electron backscattered diffraction (EBSD) measurements on deformed samples confirm that dislocation slip is the main deformation mechanism in as-received sheet with a typical basal texture, while dislocation slip and extension twinning (ET) both contribute to sustaining plastic strain in the sheet with a rare RD-split bimodal texture, which is fabricated by equal channel angular rolling and continuous bending process with subsequent annealing (ECAR-CB-A). Therefore, these two sheets demonstrate obviously different texture evolution during plastic deformation. As-received sheet maintains basal texture and further experience the concentration of basal poles towards normal direction (ND). However, ECAR-CB-A sheet not only undergoes the gradual diffusion and rotation of tilted basal poles to ND but also the development of a new TD-component texture. The activation of ET variants in ECAR-CB-A sheet is confirmed to play an important role in texture evolution, and the number of activated ET variants is increasing with the increase of angle between ND and c-axis. In addition, acquired mechanics data demonstrate that ECAR-CB-A sheet possesses higher fracture elongation (24%) and lower yield stress (73 MPa) as compared to as-received sample. This issue can be ascribed to the participation of ET to coordinate plastic deformation along c-axis and the easier activation of basal slip in ECAR-CB-A sheet.