Friction stir welding (FSW) is the most popular and efficient method for solid-state joining of similar or dissimilar metals and alloys. This technology is mostly applied in aerospace, rail, automotive, and marine industries. In order to reduce the weight of special auto parts, friction stir spot welding (FSSW) was proposed by some researchers for the connection of steel-aluminium dissimilar metals. However, the steel-aluminium joints welded by FSSW are prone to brittle fracture and have lower shear load although they have high mechanical connection strength. The friction stir spot welding brazing process integrates the brazing effects with the friction welding effects by the addition of solder. A study of FSSW of DP590 and 6061 with the filler metal added was carried out in this paper. The orthogonal test was performed to optimize the process parameters in order to achieve the best shear load of the joint. The shear strength of the joint was studied by the shear test. The fracture morphology was investigated by optical microscopy (OM), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The results showed that the shear load of the joint could reach 13.239 kN when the rotating speed, depth, and residence time of the mixing head were 1000 r/min, 0.2 mm, and 90 s, respectively. The aluminium-zinc solder added could well wet the interface between aluminium and steel and promote the metallurgical bonding, thereby improving the shear load of the joint. The temperature field of DP590/6061 FSSW process was simulated by ANSYS software to verify the rationality of the optimal process parameters. The simulation results were confirmed to be basically consistent with the data measured by the thermocouple.

中文翻译：

---

摩擦搅拌点焊钎焊工艺及异种金属DP590和6061的性能研究

搅拌摩擦焊（FSW）是将相似或相似金属和合金进行固态连接的最流行和最有效的方法。该技术主要应用于航空航天，铁路，汽车和海洋工业。为了减轻特殊汽车零件的重量，一些研究人员提出了搅拌摩擦点焊（FSSW）用于钢-铝异种金属的连接。然而，尽管FSSW焊接的钢-铝接头具有较高的机械连接强度，但它们容易发生脆性断裂并且剪切负荷较低。搅拌摩擦点焊钎焊工艺通过添加焊料将钎焊效果与摩擦焊效果结合在一起。本文对添加了填充金属的DP590和6061的FSSW进行了研究。进行正交试验以优化工艺参数，以实现接头的最佳剪切载荷。通过剪切试验研究了接头的剪切强度。通过光学显微镜（OM），扫描电子显微镜（SEM）和能量色散谱仪（EDS）研究了断裂形态。结果表明，当搅拌头的转速，深度和停留时间分别为1000 r / min，0.2 mm和90 s时，接头的剪切载荷可达到13.239 kN。添加的铝锌焊料可以很好地润湿铝和钢之间的界面并促进冶金结合，从而提高接头的剪切负荷。通过ANSYS软件对DP590 / 6061 FSSW工艺的温度场进行了仿真，验证了最佳工艺参数的合理性。