OPTIMIZATION OF DISSIMILAR ASS-DSS SPOT WELDED JOINTS ON TENSILE SHEAR FRACTURE LOAD

Abstract

Austenitic Stainless Steel (ASS) and Duplex Stainless Steel (DSS) are joined to optimize the Resistance Spot Welding (RSW) process parameters and to predict the parametric influence on the response of Tensile Shear Fracture Load (TSFL). The Response Surface Methodology (RSM) is an optimization technique is used in this research to develop the satisfactory quadratic mathematical model and 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 TSFL 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 TSFL. The macroscopic examination confirmed that the larger nugget is observed during the maximum welding current due to the high heat generation. Also, the variation in TSFL against the process parameters are observed as same as nugget length, because, TSFL and nugget length are perfectly correlated.