Dissimilar Spot Welds of AISI 304/AISI 1008: Metallurgical and Mechanical Characterization

This paper aims at investigating structure‐properties relationships in dissimilar resistance spot welding of AISI 304 austenitic stainless steel (SS) and AISI 1008 low carbon steel (CS). Microstructural characterization, microhardness test and the tensile‐ shear test were conducted. It was shown that the shape of the SS/CS fusion zone (FZ) is unsymmetrical and the final fusion line shifts from sheet/sheet interface into the higher resistivity side (i.e. AISI 304). FZ microstructure was ranged from ferrite‐austenite to full martensite depending on the dilution ratio of the base metals. The variation of SS/CS dissimilar welds failure mode was explained in terms of hardness/microstructure characteristics. It was concluded that to ensure pullout failure mode, welding parameters needed to adjust so that the FZ size is sufficiently large and dilution is sufficiently high to produce a martensite FZ. Fusion zone size at CS side proved to be the most important controlling factor of SS/CS peak load and energy absorption. Finally, the mechanical properties of SS/CS dissimilar welds were compared with SS/SS and CS/CS similar welds.