Research on the mechanism of friction based welding using single crystal aluminum

从材料学的角度对搅拌摩擦点焊和摩擦焊的金属流动进行了研究。采用单晶纯铝薄板进行的FSSW实验表明，FSSW存在压缩和剪切两种不同的变形模式。此外，变形模式根据试样中的位置而变化。FSSW过程中金属流动的可视化发现了类似形状的流动区域，并且对录像图像的PIV分析揭示了工具周围的复杂应变场，例如剪切、拉伸和压缩。铝合金FW表现出压缩变形和剪切变形，这影响了接头的微观组织。温度场的数值模拟结果表明，接头界面附近温度分布不均匀，导致焊接过程中变形模式的多样性。

Friction Stir Spot Welding (FSSW) and Friction Welding (FW) have been investigated in terms of metal flow based on materials science. FSSW experiments adopted single crystal pure aluminum sheets clearly showed there were two distinct deformation modes such as compression and shear. Additionally, the deformation modes varied depending on the locations in the specimen. Visualization of metal flow during FSSW found a similar shape of flowing regions and the PIV analysis on the video-taped images revealed complex strain fields around the tool, such as shear, tension and compression. FW of aluminum alloy revealed both compression and shear deformation, which affected the resulting joint microstructure. The numerical simulation of temperature distribution yielded a heterogeneous distribution of temperature around the joint interface, which was concluded to cause the diversity of deformation mode in the welding process based on the friction phenomenon.