Influence of extrusion parameters on microstructure and texture developments, and their effects on mechanical properties of the magnesium alloy AZ80

Extrusion of the DC-cast alloy AZ80 has been performed at three extrusion ratios (12, 22 and 44) in the temperature range 175 °C ≤ T ≤ 350 °C. Upon extrusion, the as-cast coarse grains undergo pronounced grain refinement and the β-phase constituents form stringers in the extrusion direction. The activation of twinning at low extrusion temperatures promotes nucleation of the recrystallized grains at the twin interfaces and refines the grains size. The higher extrusion ratio increases the extrusion velocity and therefore raises the die exit temperature, which results in a slightly coarsen grain size. The unidirectional deformation and DRX during extrusion leads to a fibrous type of crystallographic texture, which results in anisotropy of the yield stress under tension and compression, usually called “strength differential effect” (SDE). The impact of the SDE weakens by lowering the extrusion temperature and remains unaffected by the variations in the extrusion ratio.