▎ 摘　　要

Resistance spot welding of dissimilar materials (AISI-1008 steel and aluminium-1100 alloy) by adding an interlayer of graphene nanoplatelets (GNPs) is reported in this study. This GNP layer is incorporated in the steel plate by drop-coating technique and the coated steel and the aluminium plates were joined by the resistance spot-welding method. The peak loads of these dissimilar lap joints processed at different welding current/time conditions were obtained by lap-shear tests and a comparative study was carried out between the GNP coated and bare specimens. While the weld strength depends predominantly on the time/current used for the welding, a maximum enhancement of similar to 124 % is obtained for GNP coated samples in comparison to that of the bare ones. Fractography was performed by SEM and it was observed that a mixture of both brittle and ductile fractures was the major cause of failure. Interfacial failure and metal expulsion were also observed at lower and higher processing conditions respectively. Nugget size variation with different processing parameters was also studied. Dissimilar metal welding formed Al-Fe rich intermetallics (FeAl3, Fe2Al5, and Fe4Al13) which enhanced some of the properties of the nano-composites formed in the nugget zone. Detailed microstructural characterization was carried out by light microscopy, AFM, SEM, TEM, XRD and Raman spectroscopy. The enhancement of strength of the composite was done by numerous strengthening mechanisms as a result of the incorporation of GNPs. Microhardness investigation across the weld cross-section was carried out and it was found that an enhancement in hardness due to the formation of intermetallics and graphene entrapment was reported.