Texture Dependence of Elongation Anisotropy in an AZ61 Magnesium Alloy Sheet

Extruded and subsequently rolled sheets of AZ61 (Mg-6Al-1Zn in mass%) were tensile tested at room temperature at an initial strain rate of I X 10(-3) s(-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 90degrees 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 16degrees 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 16degrees, 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.