The weld formation of self-support friction stir welds for aluminum hollow extrusion

Friction stir welding has made significant strides to weld aluminum hollow extrusion thanks to the advancement of tool design. Research has concentrated on weld defect in aluminum hollow extrusion self-support friction stir welds and the mechanism of weld formation. Three distinct material flow zones are involved in weld formation. The formation of inner material-loss defects depends on migration ability of plastic material which corresponds to the effectiveness of lower shoulder and welding parameters. The size of defect decreases and formation position shifts downward with increasing welding speed and lower shoulder diameter. Materials flow characterization left around the tunnel and pore defect is used to study plastic material flow patterns. The formation quality can be improved by increasing welding speed and lower shoulder diameter, which affects deformation ability and flow of plastic material around the tool.