Crystallographic Orientation, Recrystallization, and Texture Development in AZ91 Magnesium Alloy Rods Fabricated by Continuous Rotary Extrusion (CRE)

Abstract

The magnesium alloy AZ91 is widely used in the aviation and automotive industries, where high mechanical properties combined with low density are required. Searching for new, advanced deformation methods in these industries is also essential. Therefore, the presented fundamental research is applied to the continuous rotary extrusion (CRE) process of AZ91 alloy, which is being introduced to industrial applications as a wrought alloy. In this process, magnesium alloy rods were continuously extruded using two types of dies, and their physical properties were examined and compared to rods extruded using the traditional direct extrusion (DE) method. The results indicate changes in the crystallographic orientation, texture, and degree of recrystallization of rods extruded in the CRE process to rods directly extruded from the AZ91 alloy. Significant changes in crystallographic orientation, surface texture, and crystallographic texture asymmetry for rods extruded with both types of CRE dies have been observed compared to the DE rods. The share of the recrystallized grain fraction for the CRE rods obtained using two kinds of dies was relatively uniform on the rod’s cross-section. In contrast, in the case of DE rods, the differences between the surface and the center of the rod were more visible. The obtained results indicate different local deformation conditions within the processed material.