3448 摩擦攪拌スポット接合継手の強度特性に与える接合ツール形状の影響(G03-9 継手・溶接,G03 材料力学)

抄録

The effect of tool geometry on microstructure and static strength in friction stir spot welds of 6061 aluminium alloy sheets was studied. Tools with three different probe lengths were evaluated. The weld microstructures varied depending on probe length, tool rotational speed and tool holding time. Two particular aspects in the microstructures were identified: the thickness of the upper sheet under the shoulder indentation and the actual nugget size. The tensile shear strength increased with increasing probe length, while the cross tension strength was not affected significantly by probe length. Two fracture modes were observed in both tensile shear and cross tension tests. The dependence of static strength on probe length and the fracture mechanisms were discussed based on observation of the microstructures.