A Review on Microstructure and Mechanical Properties of Dissimilar Welding Between SS 316 and S 202

The dissimilar welding of Stainless Steel 316 and Stainless Steel 202 presents a practical engineering solution for achieving a balance between cost effectiveness and corrosion resistance. However, the significant differences in chemical composition, particularly in nickel and molybdenum content, lead to complex microstructural evolution and variations in mechanical performance across the weld joint. The review shows that the fusion zone typically consists of an austenitic matrix with δ-ferrite, which helps reduce hot cracking but must be controlled to maintain toughness. The heat affected zones on both sides exhibit distinct behaviour, with SS 316 being more prone to sensitization and SS 202 showing comparatively lower stability and mechanical performance. These variations result in non-uniform hardness distribution, reduced toughness in certain regions, and residual stress development due to thermal mismatch. Mechanical properties of the joint are largely governed by the weaker SS 202 base metal or its heat affected zone, making it the critical region for failure under loading conditions. Additionally, challenges such as elemental dilution, corrosion mismatch, grain coarsening, and hot cracking significantly influence weld integrity. Recent studies indicate that proper selection of filler materials (such as ER309L), optimized welding parameters, and controlled heat input can significantly improve weld quality by stabilizing microstructure and minimizing defects. Advanced welding techniques further offer potential improvements in joint performance. In conclusion, while SS 316–SS 202 dissimilar welding is feasible and widely applicable, achieving a sound and reliable joint requires careful control of metallurgical and processing parameters. Future research should focus on advanced welding methods, post-weld treatments, and computational modelling to further enhance weld performance and long-term service reliability.

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