Influences of tool shoulder diameter to plate thickness ratio (D/T) on stir zone formation and tensile properties of friction stir welded dissimilar joints of AA6061 aluminum–AZ31B magnesium alloys

Friction stir welding (FSW) is capable of joining dissimilar materials. In FSW, a rotating shoulder with a profiled pin moves between sheets of the pieces to be joined. As the rotating tool travels along the weld line, frictional heat is generated between the base material and tool shoulder. This heat is however lower than in fusion welding methods. In this work the influences of the tool shoulder diameter (one of the heat generation source) on the macrostructure, microstructure and tensile properties of the dissimilar AA6061 Aluminum and AZ31 Magnesium alloys were experimented. From this investigation, it was found that the joints fabricated using a shoulder diameter of 21 mm (3.5 times the plate thickness) exhibited superior tensile properties compared to its counterparts.

► Friction stir welding of dissimilar aluminum–magnesium alloys is reported.
► The effect of shoulder diameter to plate thickness on the properties were studied.
► Microstructure, microhardness and tensile properties were evaluated.
► Shoulder diameter to plate thickness ratio of 3.5 yielded superior properties compared to other joints.