Weldability Study of Aluminium Alloy AA6063 by Tungsten Inert Gas Welding and Optimization of Weld Conditions by Analytical Hierarchy Process

Welding of aluminium alloys and composites is interesting research subject due to the many challenges encountered during the process. As aluminium finds several applications due to its lightness and high strength-to-weight ratio, thus welding of the same with improved weldability has remained an important area of research. Among the several welding processes, Tungsten Inert Gas (TIG) welding is widely used for welding of aluminium. In this work, AA6063 aluminium alloy samples were TIG welded using ER4043 filler material of diameter 2 mm. Central Composite Design (CCD) of Response Surface Methodology (RSM) was the design of experiment. Heat Input (kJ/mm) and Gas flow rate (l/min) were input factors of two levels each. Responses were measured as bead geometry (depth of penetration, bead width and height of reinforcement), hardness and visual impressions (cracks, blowholes and pinholes). Heat input values of 0.355kJ/mm,0.408kJ/mm, 0.48kJ/mm and gas flow rates of 8l/min, 12l/min and 16l/min were considered. In this research work, Analytical Hierarchy Process (AHP) was utilised to optimize the TIG welding process parameters to obtain the best combination for sound weldability. It was observed that optimal weld condition was obtained at heat input of 0.702 kJ/mm and gas flow rate, 14 l/min.