Evolution of microstructure and mechanical properties of AZ31 Mg alloy sheets processed by accumulated extrusion bonding with different relative orientation

Abstract In this study, rolled AZ31 Mg alloy sheets were subjected to accumulated extrusion bonding (AEB) process at 473 K with transvers direction (TD) parallel (0°), at 45° inclined and perpendicular (90°) to the sizing band. Deformation and dynamic recrystallization (DRX) mechanisms of AZ31 Mg alloy sheets were investigated from start to end of AEB process. Mechanical properties of as-received and AEBed sheets were then evaluated by tensile tests based on the concurrent microstructure and texture evolution. The results indicated that {10–12} tensile twinning dominated the early stage deformation, and subsequently DRX occurred and dominated the further deformation. The effects of relative orientation on microstructure and texture evolution mainly occurred in the cone die and sizing band. 0° and 90° samples exhibited an ED-tilt double peak texture, and 45° sample showed a more disperse texture components in TD. After the extruded sheets exited from extrusion die, grain growth was observed with the orientations preserved from sizing band, and the interfaces of various samples were bonded successfully with different angles to TD. Mechanical properties tests indicated that three AEBed samples exhibited similar strength and ductility with higher yield strength (145 MPa vs. 169 MPa), ultimate tensile strength (336 MPa vs. 392 MPa), and fracture elongation (24.9% vs. 28.8%) comparing to that of as-received sample along RD.