Research on friction stir welding of 5754 aluminum alloy with unequal thickness

A new structure of 1+2 was designed in friction stir welding(FSW) of Al alloy sheet with unequal thickness: a specific sheet with similar composition of base metals(BMs) was placed under the thinner sheet as the supporting sheet so that the BM surfaces could be on a plane. The BMs can also be fully penetrated weld with a stirring pin longer than the thickness of the thin sheet. 2 mm and 1.5 mm thick Al alloy sheets were welded by FSW, and parameters were optimized. The highest welding strength reached 96.07% of the thin base metal.Although a slight thinning phenomenon occurred at the edge of the nugget on the retreating side, the specimen still fractured in the heat-affected zone.