Microstructure evolution of AZ31 Mg alloy during equal channel angular extrusion

Microstructure evolution of AZ31 Mg alloy during equal-channel angular extrusion (ECAE) was investigated. The grains of AZ31 Mg alloy were refined significantly after extruded one to eight passes at 498 K. Dislocations were induced at the initial stage of extrusion and they rearranged themselves to form dislocation boundaries and sub-grain boundaries during deformation. As strain increased, the newly created dislocations in sub-grains were absorbed by the sub-boundaries and the misorientation between sub-boundaries increased and evolved to low angle grain boundaries (LAGBs) and high angle grain boundaries (HAGBs). The process of grain refinement can be described as continuous dynamic recovery and recrystallization (CDRR).