▎ 摘　　要

Resistance spot welding of steel (AISI:1008) plates by incorporating an interlayer of graphene nanoplatelets (GNPs) is discussed here. The inclusion of GNP interlayer coating was achieved by solution drop casting and the GNP coated steel plates were joined together by the spot welding process. It was found that the weld strength of the joined steel plates depends primarily on the current/time used for electrical resistance heating. Lap-shear tests were carried out to find the peak load bearing strengths of the steel plates processed at varying current/time conditions and comparison was made between the GNP coated and bare samples. The failure mode was analyzed post lap shear test by SEM and it was observed that shear dimple rupture was the primary cause of failure. Interfacial and button pull-out failure was also witnessed at lower and higher welding currents respectively. Variation of the nugget size with different welding current and time parameters were also studied. Microstructural characterization was done by optical microscopy, SEM, AFM, Raman spectroscopy, and XRD. GNPs were typically found along the grain boundaries which led to the enhancement of strength by grain boundary strengthening mechanisms. Micro-hardness studies across the cross-section and a thorough study of subsurface hardness were carried out and it was found that there is an increase in hardness due to graphene entrapment.