6061-T6/7075-T6异种铝合金搅拌摩擦焊接头组织与性能

利用搅拌摩擦焊实现了2 mm厚7075-T6/6061-T6异种铝合金连接，并对材料放置位置和转速对接头成形与组织性能的影响进行了分析. 结果表明，7075-T6铝合金置于前进侧时更有利于焊接过程中材料的迁移行为，焊缝成形及接头性能更优.当焊接速度为150 mm/min、转速为1 000 r/min时，可获得内部无明显缺陷、外观良好的异种铝合金接头；相较于母材，热力影响区的小角度晶界含量增加，焊核区发生动态再结晶，小角度晶界转化为大角度晶界；接头拉伸性能随转速的增加，呈现先增加后减小的趋势.接头的平均抗拉强度和断后伸长率分别达到231 MPa和4.0%. 接头的断裂位置位于6061侧焊核区，与接头硬度最小位置相吻合.

Microstructure and properties of friction stir welded joints for 6061-T6/7075-T6 dissimilar aluminum alloy

Friction stir welding technique was applied to 2 mm thick 7075-T6/6061-T6 dissimilar aluminum alloys. The influence of rotating speed and material placement on the joint formation, microstructure and properties were studied. The results indicated that when the 7075-T6 aluminum alloy was placed on the advancing side, it is more conducive to material migration. The plates were joined successfully without welding defects and good surface formation when the welding speed is 150 mm/min and the rotating speed is 1000 r/min. Compared with the base metal, the thermo-mechanically affected zone had an increased content of low-angle boundaries. In the nugget zone, the low-angle boundaries converted to curve high-angle boundaries because of dynamic recrystallization. With the increase of rotating speed, the tensile properties of the joint firstly increased and then decreased. The ultimate tensile strength of the joint reached 231 MPa, and the elongation reached 4.0%. the fracture locations of the joints all located in the nugget zone at the 6061-T6 side, which coincided with the position with the minimum hardness.