Experimental and Numerical Studies of Material Flow during Welding by Friction Stirring

Friction stir welding (FSW) is an energy efficient and environmentally benign welding process. The FSW is welded as a solid-state joining process under a combination of extruding and forging. The weld joint property strongly depends on the heat input and material flow during welding. The region of weld defects of butt weld was investigated by material flow around tool. The material flow direction during welding was investigated using a high speed video camera between transparent Poly-vinyl chloride (PVC) materials as simulation experiments of aluminum alloys. Additionally, the material flow velocity was measured by particle image velocimetry (PIV) method. Also, the material flow was numerically simulated which is finite element method (FEM) by plastic forming software DEFORM-3D. From PIV and FEM analysis, material flow directions were observed different type of flow direction at advancing side (AS) and retreating side (RS). One is that the material flow direction was corresponded to the tool rotation at RS. Other is that the flow direction was in the reverse direction of the tool rotation at AS. On the other hand, the material flow velocities of PIV analysis ranges from about 2 to 20 mm/s at AS. The material flow velocities of PIV analysis ranges from 1 to 5 mm/s at RS.