Abstract:A 2024 aluminum alloy tube was prepared by friction stir welding and spinning. The bulging performance and circumferential thickness distribution of the welded tube with different strength matching coefficients were investigated by the hydro bulging experiment. The deformation behaviors and the stress and strain history of the welded tube during hydro-bulging were investigated by finite element analysis (FEA) and mechanics analysis. The results indicate that the welded tube with high strength matching coefficient shows higher bulge ratio and more uniform circumferential thickness distribution than that with low strength matching coefficient. The results of FEA and mechanics analysis show that the equivalent stress on the weld is higher than that of the base material and the strain state of the weld is biaxial tension for the welded tube with high strength matching coefficient. On the contrary, the equivalent stress on the weld is lower than that of the base material for the welded tube with low strength matching coefficient, and the tensile strain occurs in the circumferential of the weld, while the compressive strain firstly occurs in the axial direction of the weld and then gradually transforms to tensile strain. The welded tubes with high strength matching coefficient possess high formability during hydro bulging for that the welds with high strength promote the deformation of the base material