A COMPARISON OF MICROSTRUCTURE AND MECHANICAL PROPERTIES OF TIG AND MIG WELDED DISSIMILAR AA7075 / AA6061 ALUMINIUM ALLOYS SUBJECTED TO FRICTION STIR PROCESSING

The present work investigates the microstructure and mechanical characteristics of TIG and MIG welded dissimilar AA7075 / AA6061 aluminum alloys subjected to Friction Stir Processing (FSP). Initially, aluminum plates were welded using TIG and MIG processes along the rolling direction. Next, FSP was performed on the TIG and MIG welded plates using a rotating tool with a welding speed of 40 mm/min and a tool rotating speed of 940 rpm. The microstructures of the welded joints have been quantified using optical microscopy, Field Emission-Scanning Electron Microscopy, and Electron Back Scattered Diffraction. Vickers hardness and tensile tests were carryout out to assess the mechanical properties. The findings revealed that the application of FSP on TIG-welded joints resulted in smaller grain sizes. TIG+FSP joint possessed the highest yield strength, ultimate tensile strength, and stir zone hardness compared to the MIG+FSP joint. Lower hardness was found on the heat-affected zone of the AA6061 side for the MIG+FSP joint.