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采用搅拌摩擦焊对异种铝合金6061-T6(上板)和A356-T6(下板)进行搭接焊,用体式和光学显微镜观察搭接接头的组织形貌,并测试其显微硬度。结果表明:在适当的工艺参数条件下,可以获得表面成形良好、内部无明显缺陷的搭接接头。在焊核区,两板间存在明显的界面,且位置较原位置整体上移,前进侧界面处呈锯齿状,界面由两种铝合金组织交替镶嵌而成,而后退侧界面则呈曲线状。两板均呈现典型的搅拌摩擦焊接头组织:焊核区由细小的等轴晶组成,而热影响区组织与母材相似,晶粒有细微粗化,热机影响区晶粒被拉长、弯曲,有明显的塑性流动。两板焊缝区显微硬度比各自母材均有不同程度的降低,且上板6061-T6降低幅度较大,焊后最大硬度约为母材的65%。
The friction stir welding was used to lap-weld the dissimilar aluminum alloy 6061-T6 (upper plate) and A356-T6 (lower plate). The microstructure of the lap joint was observed by optical microscopy and the microhardness was tested. The results show that lap joints with good surface finish and no obvious internal defects can be obtained under the proper process parameters. In the nugget area, there is a clear interface between the two plates, and the position is shifted upwards from the original position. The advancing side interface is jagged. The interface is alternately inlaid with two kinds of aluminum alloy structures, while the back side interface is curved . Both plates show the typical structure of friction stir welded joints: the weld nugget zone is composed of fine equiaxed grains, while the heat-affected zone is similar to the base metal, the grains are slightly roughened, the grains in the heat-affected zone are elongated and bent , There is a clear plastic flow. The microhardness of the weld zone of the two plates is lower than that of the respective base metal, and the 6061-T6 plate is greatly reduced, and the maximum hardness after welding is about 65% of the base metal.