Microstructure evolution and mechanical properties of an AZ61 alloy processed with TS-ECAP and EPT

The microstructure evolution and mechanical properties of an AZ61 alloy that was processed with a combination of two-step equal-channel angular pressing (TS-ECAP) and electropulsing treatment (EPT) processing were investigated herein. After the second-step ECAP (SS-ECAP) for 4 passes, the dislocation densities and stored deformation energy of the AZ61 alloy continuously accumulated to reach maximum values of 3.03 x 10(14) m(-2) and 41.2 J/g, respectively. The results were attributed to a decrease in the extrusion temperature, accumulated deformation and grain refinement. Compared with the properties of the as-received AZ61 alloy, the best comprehensive mechanical properties were obtained by the TS-ECAP and EPT method. First, the grain size of the samples after the EPT was refined from 30 mu m to 1 mu m. Second, the yield strength and tensile strength significantly increased from the initial values of 250 MPa and 350 MPa-305 MPa and 426 MPa, respectively. Additionally, the elongation was greatly improved from 6.8% to 18.3%, which is an increase of three times over that of the as-received AZ61 alloy. In conclusion, a uniform and ultrafine-grained structure was obtained in the samples after an EPT, where static recrystallization was completed at a relatively low temperatures and in a short time.