Ray Ohyama, Junichi Koike, Mayumi Suzuki and Kouichi Maruyama
Graduate School of Environmental Studies, Tohoku University, Sendai 980-8579
Extruded and subsequently rolled sheets of AZ61 (Mg--6Al--1Zn in mass%) were tensile tested at room temperature at an initial strain rate of 1×10-3 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 90°ree 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°ree 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°ree, 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.
magnesium, AZ61, elongation anisotropy, deformation texture
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