Microstructure and texture evolution of AZ31 Mg alloy after uniaxial compression and annealing

Abstract

The effect of initial texture on the microstructure and texture evolution of as extruded AZ31 alloy after hot uniaxial compression at 430 °C and subsequent annealing at 450 °C for 72h has been investigated using electron backscatter diffraction. Samples were machined from the extruded block in such orientations that the compression axis, CD, was parallel (CD0ED) or perpendicular (CD90ED) to the initial extrusion direction, ED, respectively. Results show that the deformation microstructure for both samples was characterized by equiaxed grains that resulted from dynamic recrystallization. Annealing at 450 °C for 72 h led to the increase of grains size to 28 and 25 µm for CD0ED and CD90ED samples, respectively. A random deformation texture was developed in CD0ED sample while the deformation of CD90ED developed typical (0002) basal texture. The deformation textures of both samples were retained after subsequent annealing at 450 °C for 72 h. The flow behavior was affected by the initial texture. The CD0ED sample showed the highest work hardening. These evolutions were explained in term of the activation and suppression of basal, non-basal slip and mechanical twinning.