Tensile Deformation Characteristics of Commercial Mg Alloys Processed by Equal Channel Angular Pressing

The commercial AZ31 and AZ61 Mg alloys were subjected to equal channel angular pressing (ECAP) after hot rolling at 673 K. The hot-rolled AZ31 alloy could be ECA pressed at 493 K. The 4 ECA pressed AZ31 alloy revealed the microstructure of dynamically recrystallized grains with a grain size in range of 1 to 10μm. Despite the dynamic recrystallization during ECAP at higher temperatures ( > 1/2 Tm), the yield stress and tensile strength of AZ31 and AZ61 alloys drastically increased after 1 pressing. The yield stress gradually decreased with increasing the number of pressings, which contrasts with the behavior of the ECA pressed Al and Fe alloys, while the tensile strength increased slightly. In particular, the alloys showed nearly 3 times higher elongation than as-annealed one after 4 ECAPs, without sacrificing the tensile strength. These tensile deformation characteristics were explained based on the observation of the deformed microstructure in the vicinit of fracture surface.