Maximizing Strength of Friction Stir Spot Welded Bimetallic Joints of AA6061 Aluminum Alloy and Copper Alloy by Response Surface Methodology

ABSTRACT Friction Stir Spot Welding (FSSW) is a variant of friction stir welding (FSW) process, in which the rotating tool is plunged into a material under high forging force to create a bond. It is employed to join dissimilar alloys like aluminum and copper. As it is a solid state welding process, it helps to eliminate defects found in fusion welding processes. FSSW finds extensive application in the automobile and aerospace industries. In this investigation, an attempt was made to join aluminum alloy (AA6061) with copper alloy (commercial grade) by FSSW process. The effects of the four major parameters of FSSW process, namely Tool rotational speed (N), Plunge rate (R), Dwell time (T) and Tool diameter ratio (D) were explored in this investigation. An empirical relationship was developed by response surface methodology (RSM) to predict strength of the welded joints incorporating these parameters. Response graphs and contour plots were constructed to identify the optimized FSSW parameters, so as to attain maximum strength in bimetallic joints of AA6061 aluminum and copper alloys.