Experimental investigation and optimization of mechanical properties on combination of higher and lower strength of aluminum alloys

Friction stir welding is a high potential technology for joining similar and dissimilar aluminum materials, utilized extensively in aerospace and automotive industrial applications to eradicate the problems like hot cracking, porosity, element loss, etc. due to the fusion welding process. This Research addresses the joining of two dissimilar materials of AA 5754 – H32 and AA 8090T6511 – Al-Li and their mechanical properties analysis with the effects of friction stir welding process parameters like tool rotational speed, welding speed and axial load on weld nugget zone formation quality. The significant roles of different tool pin profiles are also emphasized. A mathematical modeling equation was formed by using regression analysis to optimize the process parameter and found the best tool pin profile for defect-free weld nugget zone and higher tensile and hardness properties. This research also portrays the contribution of various pin profiles and each process parameter on the ultimate tensile strength by response surface methodology. The results indicate that the defect-free weld joints are observed with 1800 r/min of rotational speed, welding speed of 15 mm min −1 and 8.5 kN of axial load with hexagonal pin profile.