Friction stir welding of copper: Processing and multi-objective optimization

Abstract

Non-ferrous metals are difficult to weld as compared to the ferrous metals. Copper is one of the non-ferrous metals using worldwide in different manufacturing and other metal processing industries. This paper focuses on the processing of copper under friction stir welding (FSW) and the study of mechanical properties of friction stir welded (FSWed) copper joints. Different parameters of FSW have been studied with the help of L9 orthogonal array (OA). Rotational speed and traverse speed of the tool with three different tool materials have undergone for the parametric optimization. Tensile strength and impact strength have been optimized using the grey relational method. Results show a significant effect of parameters on responses. Finally, it has been concluded that the grey relational method is a robust method to optimize the combined set of responses in a single attempt. From results, it has been observed that the higher rotational speed and lower traverse speed with H13 tool material give better results for mechanical properties. Analysis of variance (ANOVA) has been used to find the percentage contribution of each parameter on mechanical properties. P-value has been found less than 0.05 which shows that the effect of each selected parameter on the result is significant. Microstructure study has been performed on scanning electron microscopy (SEM) and the change in grain size within the weld zone has been observed.