Optimization of Underwater Friction Stir Welding Parameters for AA5128 and AA 7075 Aluminum Alloy using Response Surface Methodology

Abstract

The lower melting points and inherent welding difficulties of aluminium alloys make the process of joining them a formidable obstacle. This is why FSW solid-state friction stir welding (FSW) has become so popular in the industrial sector. To improve ultimate tensile strength, yield tensile strength and microhardness, this study uses the FSW process to combine two different aluminium alloys of AA7075 and AA5128. The experimental plans were developed utilizing a central composite design based on response surface methodology. The four input factors that were considered were tool pin profile (TPP), tool rotational speed (TRS), tool traverse speed (TTS) and axial force (AF). The experimental results demonstrate that all of the outputs are significantly affected by the input variables that were taken into account. The optimal conditions, which include a TRS of 1007 rpm, a TTS of 32 mm/min and an AF of 7.7 kN with a triangular pin profile, were derived from a multi-objective optimization technique utilizing the desirability approach. The outputs of the confirmation experiment show a max variance of 9.13% with investigative results under ideal conditions and the second-order regression model predicted values for these responses with reduced residuals. There are no holes, oxides, or fractures visible in the micrographs taken from the heat-affected zone area. Base metals and other components appear in the nugget zone.