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

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.