Predicting Parametric Influence of Resistance Spot Welding Process Parameters on Tensile Shear Load Using Optimization Technique

Abstract

The stainless steels such as Austenitic Stainless Steel (ASS) and Duplex Stainless Steel (DSS) are joined to optimize the Resistance Spot Welding (RSW) process parameters and predict the parametric influence on the response of Tensile Shear Load (TSL). The Response Surface Methodology (RSM) is an optimization technique which is used for optimizing the process parameters on TSL and with the help of these results a satisfactory quadratic mathematical model has been developed to predict the response. The optimal parameters and their levels are found and reported as follows: welding current = 9 kA, welding time = 0.18 seconds and electrode tip radius = 3 mm. The actual and predicted values of TSL for the optimized parameters are 17.6 kN and 17.9 kN respectively. The developed quadratic model is efficiently predicted the response with an average error percentage of 2.18. The significant and insignificant terms in the models has been identified by 95% confidence level using ‘p’ test. The insignificant terms are removed from the model and the ANOVA table is formulated only with the significant terms. Significance or effect of each term in the ANOVA table is identified by calculating the percentage of contribution and noticed that welding current has the highest significance (46%) on TSL. The macroscopic examination confirmed that the nugget is initially formed in DSS side due to its higher thermal conductivity and resistivity. The tensile shear-strain graphs are observed with the percentage of elongation varies from the minimum of 5.18 to the maximum of 8.57 which confirm the ductile failure.