Developing Empirical Relationship to Predict the Strength of Friction Stir Spot Welded Dissimilar Joints of Aluminum and Magnesium Alloys

Friction Stir Spot Welding (FSSW) is a variant of Friction Stir Welding (FSW) process, in which a non-consumable rotating tool is plunged into a material under high forging force to create a bond. It is employed to join dissimilar materials like aluminum and magnesium as it is a solid state welding processes, and helps to avoid defects found in fusion welding processes. In this investigation, an attempt is made to join Aluminum Alloy (AA6061) with Magnesium Alloy (AZ31B) by FSSW process. An empirical relationship was developed to predict the Tensile Shear Fracture Load (TSFL) incorporating the four most important FSSW parameters, i.e., tool rotational speed, plunge rate, dwell time and tool diameter ratio, using Response Surface Methodology (RSM). The maximum TSFL obtained was 3.61 kN, with the tool rotation speed of 1000 rpm, plunge rate of 16 mm/ min, dwell time of 5 sec and tool diameter ratio of 2.5.