Resistance spot welding of AISI 430 ferritic stainless steel: Phase transformations and mechanical properties

•Phase transformations during RSW of AISI430 are detailed.•Grain growth, martensite formation and carbide precipitation are dominant phase transformations.•Failure mode of AISI430 resistance spot welded joints are analyzed.•Larger FZ size provided improved load bearing capacity and energy absorption capability.

The paper aims at investigating the process–microstructure–performance relationship in resistance spot welding of AISI 430 ferritic stainless steel. The phase transformations which occur during weld thermal cycle were analyzed in details, based on the physical metallurgy of welding of the ferritic stainless steels. It was found that the microstructure of the fusion zone and the heat affected zone is influenced by different phenomena including grain growth, martensite formation and carbide precipitation. The effects of welding cycle on the mechanical properties of the spot welds in terms of peak load, energy absorption and failure mode are discussed.