Microstructure and Mechanical Properties of Ultra-fine Grained Al Alloy Processed by Combined SPD Technology

The annealed 6061Al alloy was subjected to four pass combined extrusion deformation at room temperature using the procedure of cyclic channel die compression and equal channel angular pressing, equixed ultra-fine grained (UFG) 6061 Al alloy was successfully obtained. The evolution of the microstructure during deformation was investigated by means of transmission electron microscopy analysis. The grain refinement was discussed during combined extrusion deformation. The hardness and tensile tests were conducted, respectively. The average hardness value doubled on the three orthogonal planes. The tensile strength increases from 165 MPa to 402.7 MPa after four pass, meanwhile the elongation reduces from 26.8% to 9.7%. These results demonstrate the influence of the combined extrusion deformation on the mechanical properties of the samples is more severe in comparison to equal channel angular pressing.