Investigation of Performance of Friction Stir Welded Al Cu Joint

Abstract

Aluminium and copper welding find various applications in the industry. However, owing to the differences in the physical properties of the two dissimilar metals, it is onerous to weld them by conventional welding methods. Friction stir welding (FSW)can join dissimilar metals. However, the Inter-metallic compounds (IMCs) formed during welding have a negative influence on the tensile strength and thermal conductivity of the joint. In the present study, a congenial inter-filler material has been used to reduce the formation of IMCs and thereby improve the tensile strength and thermal conductivity of the weld. The effect of process parameters and the inter-filler layer thickness on the mechanical and thermal properties of the weld is investigated using the design of experiment tools such as the Taguchi method and Central composite design. Using the Taguchi method and full factorial analysis, the most critical parameters affecting ultimate tensile strength and thermal conductivity, and their contribution was determined. Rotational speed, traverse speed, and zinc foil thickness contributed 8.1%, 36.7%, and 54.8% correspondingly to ultimate tensile strength. Rotational speed, traverse speed, and zinc foil thickness contributed 59.84%, 34.53 %, and 5.46% correspondingly to thermal conductivity. A three-level, three-factor central composite design (CCD) has been employed to find out the effect of different process parameters, namely tool rotational speed, tool traverse speed, and thickness of inter-filler zinc foil on ultimate tensile strength and thermal conductivity of the weld. Sixty experimental data comprised in the CCD. The experiments were conducted with tool rotational speeds of 1000, 1200, and 1400 rpm, each with tool traverse speeds of 5, 10, and 15 mm/min. A zinc inter-filler foil of 0.2 mm and 0.4 mm was also employed. The defects formed and the location of the failure is investigated from the weld macrographs. Curve fitting models to predict the response were developed.