Optimization of fiber laser welding parameters for high strength aluminium alloy AA7075-T6

High strength aluminium alloy sheets are widely used in automobile industry for manufacturing super lightweight vehicles. The high strength to weight ratio possessed by these Al alloys helps in reducing the total weight of the vehicle without affecting the overall performance, thereby increasing the fuel economy and reducing the carbon emission levels. However, joining these high strength aluminium alloy sheets for mass production in automobile industry is a challenging task and is not feasible by using conventional welding processes. In the present study fibre laser welding of high strength aluminium Alloy AA 7075-T6 sheets of 1.5 mm thickness has been carried out with a capacity of 2 kW. The welding parameters namely welding power, transverse speed & frequency have been optimized with output parameters of tensile strength, micro-hardness at fusion zone and micro-hardness at heat affected zone. VIKORs optimization technique has also been applied to the experimental results to obtain the optimal solution. Taguchi method in MINITAB Software has been used for validating the results obtained.