Thermal and metallographic study of nugget size development in resistance spot welding of 304L stainless steel

An investigation for the parametric characterization of the weld nugget development was studied in this work which comprises two principal parts; the first one consists of a metallographic technique study of the nugget during spot welding. One gauge of a 304L stainless steel (1.5 mm) was studied experimentally under various welding parameters like the weld time and welding current. Current range curves, from no weld to expulsion, were generated for this stainless steel at a different weld times. The second part presents an analytical approach developed to predict the weld thickness under the same welding parameters used in the experimental stage. This analytical model is two dimensional and takes into account the thermal properties, electrode geometry and contact resistances. The results obtained through this analytical approach are compared with the metallographic results.