Influence of Welding Variables on Resistance Welding of Dissimilar Metals Quality

The investigation explains the influence of important variables of resistance joining process on the characteristics of spot welded joint between low carbon steel LCS with 0.6 mm thickness and stainless steel type 430, FSS with 0.5 mm thickness sheets. Variables investigated are electrode pressure, current, and time of welding. Mechanical and metallurgy l properties are measured through microstructure, shear tensile and hardness determination. It is shown that the effective electrode pressure in this combination of FSS and CS was 2 bar (0.2MPa). It is noted that the current of welding is the effective variable on weld properties. The highest strength of weld is achieved at 3.4 KA. Rising welding time and welding current up to certain limit raises the strength of spot welded joint, after this limit, the strength of welded joint reduces. The microstructure of nugget obtained is martensitic structure. The fracture of spot welded joint is characterized by intergranular fracture in side of ferritic stainless steel sheet and the fracture mode is button pullout. The highest values of micro hardness distribution are observed at locations where carbides precipitated beside nugget martensitic structure.