Mechanical Properties and Phase Transformations in Resistance Spot Welded Dissimilar Joints of AISI409M/AISI301 Steel

Objectives: In this study, the mechanical properties and phase transformations of resistance spot welded dissimilar joints between austenitic stainless steel AISI 301 and ferity stainless steel AISI 409M are investigated. Methods/Analysis: Mechanical properties such as tensile shear strength, failure energy, failure mode, nugget size and surface indentation were analysed at varying current ratings. Macrostructure was examined for size and shape. Microstructure at various locations such as, fusion zone and heat affected zones were investigated. Micro hardness measurement was done at various locations along the weld. Findings: Tensile shear strength increases with increase in welding current in expulsion free welds. Fusion zone hardness was found to be larger than that of both base metals and heat affected zones. Nugget size and energy absorbing capacity of the spot weld were found to be in correlation with weld current in expulsion free samples. Electrode indentation on the nugget surface increases with increase in welding current. Fusion zone microstructure consists of martensite and ferrite. Asymmetrical nugget shape was observed. Novelty/Improvement: Investigating the effects of resistance spot welding on the mechanical properties and phase transformations of ferritic-austenitic dissimilar metal weld joint.