Effect of grain size distribution and texture on the cold extrusion behavior and mechanical properties of AZ31 Mg alloy

An experimental investigation into the cold extrusion and the subsequent annealing processes of an Mg-2.8%Al-0.83%Zn (AZ31) Mg alloy was studied. Microstructures, grain size distribution and texture evolution of the as-extruded and as-annealed specimens were investigated by optical microscopy and electronic backscattered diffraction (EBSD). Tensile tests along the extrusion direction were carried out at room temperature. It is found that firstly, the uniform microstructure with log-normal grain size distribution led to homogeneous cold deformation and good appearance without cracks for the as-extruded rods; secondly, texture was able to soften the yield strength induced by grain refinement and even overcame the refined grain size effect; thirdly, well-distributed microstructure reduced the absolute difference of yield strength for the sub-micrometer-grain Mg alloys.