Although the weld seam obtained by fusion welding of aluminum alloy is as-cast structure, and the welded joint is subjected to thermal cycling, the mechanical properties of the joint are degraded. Therefore, the process of friction stir welding was proposed. The utility model utilizes a high-speed rotating stirring head and a shoulder to frictionally generate heat with the metal to make the metal in a plastic state. As the stirring head moves forward, the metal flows toward the back of the stirring head, fills and forms a dense weld seam, which is a solid phase welding method. . Advantages of aluminum alloy friction stir welding:
(1) The quality of the welded joint is good. FSW is a solid phase welding. The welded joint is not easy to produce cracks, pores and other defects during solidification during welding; the welding temperature is lower than the melting point of the aluminum alloy, so the joint close tothe base metal structure can be obtained and the workpiece deformation is small; The color changes.
(2) Low cost. No filling material and protective gas are needed; assembly accuracy is not high, pre-weld preparation process is simple; thick plate welding does not require opening; joint mechanism is simple, easy to manage, and energy-saving.
(3) No spatter or unpleasant smoke is generated, and no harmful light such as ultraviolet rays or infrared rays is generated.
The disadvantage is that the tooling equipment is complicated due to the need of applying a large upsetting pressure and a forward driving force during welding; the welding defects require a solid phase welding method to repair the welding.