EVALUATION OF TENSILE SHEAR STRENGTH AND NUGGET CHARACTERISTICS IN RESISTANCE SPOT WELDED SS316L JOINTS USING TAGUCHI METHOD

This investigation systematically analyzes resistance spot welding parameters optimization for AISI 316L austenitic stainless steel sheet joints utilizing an L9 orthogonal array-based Taguchi design methodology. The experimental matrix encompassed three critical process variables: welding current (6-10 kA), electrode pressure (2-6 Bar), and weld time (4-8 cycles). Metallurgical characterization was conducted through optical microscopy, facilitating comprehensive analysis of fusion zone morphology, heat-affected zone (HAZ) characteristics, and base material transformation. Signal-to-noise (S/N) ratio analysis revealed that welding current exhibited the highest statistical significance in determining joint shear strength, followed by weld time and electrode pressure. The main effects analysis revealed that the optimal parameter combination, which had a maximum tensile shear strength of 306.22 MPa, was 10 kA welding current, 2 Bar electrode pressure, and 4 cycles of weld time. In the fusion zone, microstructural analysis showed characteristic dendritic solidification patterns with secondary dendritic arm spacing that correlated negatively with mechanical characteristics and cooling rate. The study provides a strong basis for process optimization in RSW of AISI 316L stainless steel by establishing quantifiable correlations between process parameters and joint tensile shear strength.