在高焊接速度(3 000 mm·min^-1)下分别对3 mm和4 mm厚6061-T6铝合金板进行搅拌摩擦焊,研究了高旋转速度(4 000~6 000 r·min^-1)对接头组织与拉伸性能的影响。结果表明:旋转速度越小越容易产生孔洞缺陷,旋转速度越大越容易出现过热氧化现象,增大旋转速度有利于接头区域再结晶形成致密组织,4 mm厚铝合金板焊接接头的焊接缺陷较3 mm厚铝合金板焊接接头严重;3 mm厚铝合金板在5 000 r·min^-1旋转速度下的焊接接头质量最好,拉伸性能最佳,抗拉强度和断后伸长率分别为265.82 MPa,4.58%;4 mm厚铝合金板在6 000 r·min^-1旋转速度下的焊接接头质量最好,拉伸性能最佳,抗拉强度和断后伸长率分别为212.14 MPa,4.03%。

Friction stir welding was carried out on 3 mm and 4 mm thick 6061-T6 aluminum alloy plates at high welding speeds (3 000 mm·min^-1), respectively. The effect of high rotational speed (4 000-6 000 r·min^-1) on microstructure and tensile properties of the joints was studied. The results show that the smaller the rotation speed, the easier the formation of hole defects. The higher the rotation speed was, the easier the overheated oxidation appeared. Increasing rotation speed was conducive to the recrystallization of the joint area to form a dense structure. The welding defects of welded joints of 4 mm thick aluminum alloy plates were more serious than those of welded joints of 3 mm thick aluminum alloy plates. The welding joint quality and tensile properties of 3 mm thick aluminum alloy plate at a rotation speed of 5 000 r·min^-1 were the best, and the tensile strength and elongation after fracture were 265.82 MPa and 4.58%, respectively. The welding joint quality and tensile properties of 4 mm thick aluminum alloy plate at a rotation speed of 6 000 r·min^-1 were the best, and the tensile strength and elongation after fracture were 212.14 MPa and 4.03%, respectively.