Microstructures and Mechanical Properties of Microalloyed and Equal Channel angular Pressed AZ91 Mg Alloy

Abstract

Commercial AZ91 Mg alloys were equal channel angular pressed (ECAP) for up to 6 passes at temperature as low as 473K. Microstructures and mechanical properties of as-received and as-pressed samples were investigated. It is shown that ECAP applied successfully to these materials at elevated temperatures leads to grain refinement due to the occurrence of recrystallization during the pressing process and to significant improvements in the strength and ductility of these materials. The microstructure was obviously refined and the average grain size was considerably reduced from over 28μm to below 1μm. From tensile testing at room temperature (RT), the ultimate tensile strength (UTS) increases obviously from 318MPa to 365MPa, in contrast, the uniform elongation increased from 12% of the as-received to 26% of the pressed up to 4 passes. These observations may be attributed to the effects combined grain refinement and texture development.