Microstructure and Mechanical Prorerties of Friction Stir Welding Joints of 5083 Aluminium Alloy

5083-H321 aluminium alloy plate with thickness of 8 mm were successfully welded by friction stir welding (FSW) method, and the effect of welding parameters on microstructure and mechanical properties of FSW joints were studied. The results show that microstructure of the nugget zone was fine equiaxial grain, microstructure of thermo mechanically affected zone (TMAZ) was stretch bending deformation structure, and the heat affected zone was very narrow and the grain size was similar to the base metal. The optimal FSW parameters according to the surface morphology and the tensile test results was using three prismatic threaded stir pin and inner button type shoulder, and with the rotating speed of 300 r·min-1 and welding speed of 120 mm·min-1. Under these conditions, the FSW joint surface was good, and the tensile strength could reach 94.5% of that of the base metal.