Effect On The Joint Quality By The Structure Of The Stir Welding Pin

FSW is a new solid-state welding technology. The welding tool technology is one of the most important factors to the FSW processes. The structure and dimension of welding pin are the main factors which affects the flow direction of the plastic metal in FSW zone and the quality of the FSW seam.In this research, four kinds of welding pin, columnar, platform, columnar with screw and platform with screw pin were designed and machined. The materials of welding pins are 45~#, high speed and T10 steel .FSW processes were carried out on four materials, L2Y2, LY12, Cu, and Cu-Zn alloy with different parameters. How the joint quality was affected by the material, structure and dimension of the welding pin, and the main reason for the tunnel defects were analyzed in detail. The result showed that good appearance and joint quality without any defects were obtained for L2Y2 if the columnar welding pin was used with proper parameters. Contrary to L2Y2, LY12 and copper can not get a perfect result used the columnar ones. The reasons are described as follows: It is easy for L2Y2 to be at super-plastic state. But for LY12, the perfect joint without any defects can not be formed used the simple columnar pin with appropriate procedure, because its plastic property is poorer than L2Y2. Test result indicated that using the welding pin with screw can increase the friction zone , improve the welding heat input, and make more metal in muddle. The plastic and flow properties of the metal can be strengthened. At the same time, the screw can produce a force, which made the metal towards underside so that the small holes were filled with metal in time, the appearance of imperfections and defects can be avoided.