Strengthening and toughening of extruded magnesium alloy rods by combining pre-torsion deformation with subsequent annealing

In this study, it is found that microstructure and mechanical properties of extruded magnesium alloy rods can be tailored by the combined use of pre-torsion and annealing. For extruded magnesium alloy rods, torsion deformation can introduce a mass of dislocations to significantly enhance tensile yield strength via dislocation hardening effect. Moreover, torsion deformation can also rotate the basal pole of extrusion texture toward extrusion direction. Annealing treatment reduces dislocation density however remains the torsion deformation texture. Combined use of pre-torsion and annealing can remarkably improve the toughness of magnesium alloy rod resulting from the change of texture. These strengthening and toughening mechanisms are discussed.