Strength of AZ31 Alloys Subject to Severe Deformation by ECAP and DSR

By controlling texture and grain refinement using ECAP (equal channel angular pressing) process that induces severe shear deformation on materials without change their diameter, strength and ductility of the AZ31 alloy in the bulk form of rod could be enhanced. The original texture was completely replaced by a new texture rotated to have a high Schmid factor during ECAP. The decrease of yield stress after ECAP despite achievement of significant grain refinement was attributed to the strong effect of texture modification. The effect of differential speed rolling (DSR) on mechanical properties of the AZ31 alloy in the form of sheet was examined. Significant grain refinement took place during the rolling owing to introduction of large shear deformation by application of high speed ratio between the upper and lower rolls. Hall-Petch relations of the ECAPed and DSRed AZ31 alloys were compared and notable difference in strength between the two alloys at a given grain size was found and it was attributed to strong texture effect on strength of Mg alloys.