Eco-friendly frictional joining of AA6063 and AISI304L dissimilar metals and characterisation of bimetal joints

Abstract

This study discusses the dissimilar joining between AA6063 aluminium and AISI304L stainless steel of flat faying surfaces through a rotary friction welding process at different welding conditions as per L9 orthogonal array and the characterization of bimetal joints. The effect of welding parameters on the mechanical properties and the minimum level of welding conditions required for the metals joining were discussed. Bonding between the metals and the narrow heat-affected zone were observed from microscopy study. Energy dispersive x-ray analysis revealed the elements present at the weld interface and molybdenum formation. Fractography result on the tested specimens showed the dimple rupture during the fracture. The tensile test showed the plastic deformation near the weld joint for friction pressure 15 MPa and above. The maximum peak load and elongation of joint were around 12 kN and 12% respectively. 18 MPa friction pressure, 24 MPa upset pressure and 5 sec. friction time showed good bond strength and the maximum tensile strength of 189 MPa with 92 % of joint efficiency. Axial shortening was obtained in the range of 13-27 mm and a maximum of 26.9 mm during experiments. In joints, microhardness was decreasing towards AISI304L base metal from weld interface and conversely increasing towards AA6063 base metal. Impact tests showed the conversion of brittle into ductile fractures when increasing friction pressure and maximum impact energy observed was 38 Joule.