Effect of Welding Parameters on the Mechanical and Metallurgical Properties of Friction Stir Spot Welding of Copper Lap Joint

In this work, 2-mm-thick pure copper plates are joined using friction stir spot welding (FSSW) at different rotational speeds, plunging rates and dwell times. Effects of these process parameters on the quality of the weldments, bonding region and shear–tensile failure load of the joints are studied. A maximum shear–tensile failure load of 5.5 kN was obtained at 1200 rpm rotational speed, 20 mm/min plunging rate and 2-s dwell time. Interestingly, this set of welding conditions also resulted in end of partial metallurgical bonded region along the interface that is free of voids and cracks which indicates strong weldments. Fracture surface morphology was also investigated, and ductile fracture mode was observed for 1200 rpm, 20 mm/min and 2 s which showed high elongation before complete fracture. Moreover, mechanical energy consumed during welding was estimated for each set of welding conditions under study and was found significantly affecting shear tensile failure load of the welds.