Study On Bonding-Friction Stir Spot Hybrid Welding Procedure Of AZ31Magnesium Alloy

Relative to the aluminum alloy has good specific strength, specific stiffness, goodmachinability and other characteristics, has become the material of choice for lightweight. Inwelding of magnesium alloys by traditional welding method is easy to produce stomatal,crack, plash, slag and other welding defects, and the thermal conductivity of magnesium alloywelding is relatively large, high temperature, after cooling deformed. Friction stir spotwelding (FSSW) is a recent invention of a new welding method, with a high joint strength,low energy consumption, and the advantages of simple equipment for the welding ofmagnesium alloy has good application prospects. The adhesive joints connecting the area,stress distribution; joint sealing, and using plastic-welding composite connections, canimprove the carrying capacity and sealing joints. Therefore, bonding-FSSW hybrid provides anew way of the connection of magnesium alloy.Made of shearing test specimens of FSSW, bonding, first FSSW after bonding, firstbonding after FSSW, and the shear strength of their value is used in the comparison. As aresult, compare with their shear-resisting force strength of their value, the quality andmechanical performance of AZ31magnesium alloy of first FSSW after bonding is the best.First FSSW after bonding has the worst quality and mechanical performance. The parametersis optimized after determining the process sequence. It studied the effect of the shaft shoulderpressure, different adhesives, rotational speed on the quality and mechanical performance.Then the SEM, EDX, Micro hardness testing and metallographic is made for the frictionstir bonding spot welding. And then the defect analysis is made. After analysis ofmetallographic, found the microstructure of joints of Specimen weld has three organizationchanging area, they are WNZ, TMAZ, HAZ, and quality of WNZ of two plate junction isgood, but quality of TMAZ, HAZ of two plate junction is not ideal, and crystallite sizedisparity of two plate junction is great. Hardness analysis found that hardness of two platejunction and TMAZ is the lowest.