Optimization of Friction Stir Welding Parameters to Improve Corrosion Resistance and Hardness of AA2219 Aluminum Alloy Welds

Abstract

Abstract The aluminium alloy AA2219 (Al-Cu-Mg alloy) is widely used in the fabrication of lightweight structures with high strength-to-weight ratio and good corrosion resistance. Welding is main fabrication method of AA2219 alloy for manufacturing various engineering components. Friction stir welding (FSW) is a recently developed solid state welding process to overcome the problems encountered in fusion welding. This process uses a non-consumable tool to generate frictional heat on the abutting surfaces. The welding parameters, such as tool pin profile, rotational speed, welding speed and axial force, play major role in determining the microstructure, corrosion resistance and hardness of welded joint. The main objective of this work is to develop a mathematical model to predict the welding parameters for improved of corrosion resistance and hardness of friction stir welded AA2219 aluminium alloy. In this work a central composite design with four factors and five levels has been used to minimize the experimental conditions. Dynamic polarization testing was carried out to determine critical pitting potential, which is a criteria for measuring pitting corrosion resistance. Further the response surface method (RSM) was used to develop the model. The analysis of variance (ANOVA) result shows that tool pin profile is the most influencing parameter for both corrosion resistance and hardness. Response optimization shows that the improved corrosion resistance and hardness were achieved with hexagon tool pin profile and welding parameters of rotational speed 1363 rpm, welding speed 715 mm/min and axial force 8 KN.