Texture Dependence of Elongation Anisotropy in an AZ61 Magnesium Alloy Sheet

Abstract

Extruded and subsequently rolled sheets of AZ61 (Mg-6Al-1Zn in mass%) were tensile tested at room temperature at an initial strain rate of 1×10-3s-1. The effects of extrusion ratio and tensile direction on fracture elongation were investigated. Extrusion ratios were 3.4/100 and 1.0/100 in area reduction. Tensile direction was chosen to be 0, 45 and 90° with respect to the rolling direction. Texture change with strain was also investigated in order to understand a major dislocation slip system.We found that the magnitude of basal-plane tilt with respect to the tensile axis was a controlling factor for a major slip system and for fracture elongation. When the basal planes were tilted by more than approximately 16° from the normal direction towards the tensile direction, a major slip system was basal a dislocation slip and poor ductility was obtained. In contrast, with less tilting than 16°, a major slip system changed to non-basal a dislocation slip, which leads to better ductility. The present results indicated an importance of texture control in tensile ductility of Mg alloys.