Experimental investigation of the friction stir welding process of AA5059 and AA7079 and prediction using fuzzy approach

Aluminum alloys AA 5059 and AA7079 have high strength, excellent weldability, and corrosion resistance, widely used in train and truck bodies, armored vehicles, and defense applications. Recent materials engineering tasks call for minimizing material weight and to achieve this objective, the solid-state joining approach of Friction stir welding (FSW) is utilized for material joining. FSW has produced sound welds with high joint strength and good ductility. This research investigates the weldability of AA5059 and AA7079 dissimilar aluminum alloys. In this FSW process, a threaded tapered cylindrical tool pin profile was selected, and welding trials were conducted at three different speeds of 500, 750, and 1000 rpm, with the 75 mm/min constant feed rate. The Taguchi L 9 orthogonal array was selected to design the process parameters, that is, tool traversing speed, rotational speed, axial force, feed rate, and effect on dissimilar aluminum weld joints. The Mamdani-type fuzzy logic model predicted welded specimens’ ultimate tensile strength and yield strength. Microstructural analysis revealed that the grains in the stirring zone had undergone a full transformation into homogenous, evenly distributed, refined grains, which had a positive impact on the remarkable mechanical properties.