Influence of Nitrogen Atmosphere on Weld Nugget Morphology during Resistance Spot Welding of 304L Stainless Steel

摘要

The Resistance Spot Welding is most widely used as a joining process for stainless sheets. AISI 304L austenitic stainless steel offers the optimum combination of corrosion resistance and mechanical strength. Improving the microstructure of the spot-welded nugget has a great effect on the quality of sheet weld joints. The current research presents the influence of using nitrogen atmosphere on macro and microstructure morphologies of the spot-welded nugget of AISI 304L stainless steel. Results show that using nitrogen atmosphere as shielding gas improves the appearance and color matching of the welded nugget with base, but on the other hand, nitrogen atmosphere reduces the nugget size. In addition to the reduction of the total ferrite in the spot weld nugget, Skeletal 5-ferrite / total ferrite ratio increases by using nitrogen shielding gas due to nitrogen diffusion in fusion welded nugget zone.