Effect of Welding Speed on Mechanical Properties of Dissimilar Friction Stir Welded AA5083-H321 and AA6061-T6 Aluminum Alloys

Fusion welding of aluminum and its alloys tends to degrade the mechanical strength at the weld joint area due to high thermal diffusivity and high melting point. Friction Stir Welding (FSW) is the best alternative for joining of these materials against fusion joining. FSW is an emerging solid state joining process in which the material that is being welded does not melt and recast. The main objective of this research is to use FSW for joining of 5 mm thick AA5083-H321 and AA6061 T6 aluminum alloys using taper cylindrical threaded tool pin profile and scrolling on shoulder surface. The microstructure and mechanical characterization of dissimilar friction stir welded AA5083-H321 and AA6061-T6 aluminum alloys were studied. Four different welding speeds (40, 63, 80 and 100 mm/min) were used to weld the dissimilar alloys at constant tool rotational speed of 1120 rpm, tilt angle 2.50. The effect of welding speed on metallurgical and mechanical properties was analyzed. It is found that the welding speed of 80 mm/min produces good mechanical and metallurgical properties than other welding speeds. The observed results were correlated with the fracture features and microstructure. The fracture mode was observed to be a ductile fibrous fracture.