The method of flat friction stir spot welding (FFSSW) was used to investigate the tensile behavior of three thin dissimilar aluminium alloys (Two sheets of AA6082-T6 and one sheet of AA6061-T6). Tool with probe and a probe less tool is used in this two-step process of joining. Experiments were conducted at various tool tilt angles (TTA), tool rotational speeds (TRS), dwell time (DT) and Tool plunge depths (TPD). The quality welds were produced at optimized process parameters (TTA 2⁰, TRS 2125 rpm, DT 15 s and TPD 0.1 mm). Elimination of protuberance and reduction of keyhole in the joint is achieved for improving bonding length. Micrographs of joints were examined using optical microscopy and scanning electron microscopy (SEM). The complete bonding with finer grains at stir zone (SZ) improved the strength of FFSSW joint. Energy-dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis of specimen indicates the presence of Mg₂Si precipitates in SZ. The fracture behavior of upper and lower interfaces was examined. The finer dimples are observed in fractograph, which confirm the ductile behaviour of fracture. The morphology at tool surfaces was also studied. The mechanical properties of three-sheet FFSSW joints were compared with other similar techniques of joining. Better understanding of mechanical properties and weld behavior of three sheets FFSSW is done with the help of fractography and SEM.

采用平面摩擦搅拌点焊（FFSSW）方法研究了三种薄的异种铝合金（两张AA6082-T6和一张AA6061-T6）的拉伸性能。在连接的两步过程中，使用了带探针的工具和无探针工具。实验是在各种刀具倾斜角（TTA），刀具转速（TRS），停留时间（DT）和刀具切入深度（TPD）下进行的。在优化的工艺参数（TTA 2 ⁰，TRS 2125 rpm，DT 15 s和TPD 0.1毫米）。消除了突起中的突起并减少了接合处的键孔，从而提高了粘结长度。使用光学显微镜和扫描电子显微镜（SEM）检查关节的显微照片。在搅拌区（SZ）处与较细晶粒的完全粘结提高了FFSSW接头的强度。样品的能量色散X射线（EDX）和X射线衍射（XRD）分析表明存在Mg ₂Si在SZ中沉淀。检查上下界面的断裂行为。在分形仪中观察到更细的凹痕，这证实了断裂的延性。还研究了工具表面的形态。将三片式FFSSW接头的机械性能与其他类似的连接技术进行了比较。借助断层扫描和SEM可以更好地了解三片FFSSW的机械性能和焊接行为。