Annealing effects after various thermo-mechanical treatments on microstructure and mechanical properties of the wrought magnesium alloy AZ80

摘要

The magnesium alloy AZ80, received from Dead Sea magnesium in direct-chill cast condition was extruded at T= 350℃ using an extrusion ratio of ER = 12. The extruded bars were severe plastically deformed at 250℃ by utilizing thermo-mechanical treatments (TMT), either equal channel angular pressing (ECAP) or swaging. While swaging led to similar grain refinements as observed after ECAP, yield stress and tensile strength values were by far superior in the swaged alloy. This result is explained by the unfavourable 45° texture component of the (0002) pole figure that develops during the massive shear deformation in ECAP. Unlike ECAP, the grain orientation after swaging is similar to the as-extruded condition. Annealing at elevated temperatures indicates very low thermal stability of microstructure and mechanical properties in the ECAP-ed alloy while both properties in the swaged micro-structure are as stable as in the as-extruded reference.