Optimization of resistance spot welding process parameters for cold rolled mild steel lap joint based on tensile shear strength
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Date
2022-10
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G. B. Pant University of Agriculture and Technology, Pantnagar
Abstract
Owing to its numerous applications weld characteristics of cold rolled mild steel grade IS 513 CR 1 was investigated. Resistance spot welding, one of the most versatile welding technology was used for the purpose. The three most important parameters of the RSW namely welding current, welding time and electrode pressure were varied and the influence on the Tensile Shear Strength (TSS) was evaluated. The experiments were carried out according to Taguchi's L9 orthogonal array and Taguchi analysis was used in optimization. A lap joint of dimensions 120mm x 30 mm x 1.5mm was welded using a 100 kVA timer, current-controlled CSP-100PR Spot Welder, to create an overlap of 3 mm thickness. According to Taguchi’s L9 OA welding current cycles of 5, 10 and 15 were selected. During the welding process, the welding current was changed by adding 2 kA from 10 to 14 kA and the electrode pressure were taken to be 4, 5 and 6 bar. The Main effects plots revealed the optimal setting for the process parameters as welding current of 14 kA (Level 3), welding time of 15 cycles (Level 3), and electrode pressure of 4 bar (Level 1). The optimized process parameters showed the maximum TSS of the spot weld joint. ANOVA was carried out to identify the significant process parameters affecting the weld strength. Furthermore, the contribution of welding current was found to be 67.38% which had the maximum influence on the TSS of the welded joint. The contour plots showed that on increasing welding current and welding time with decreasing electrode pressure the Tensile Shear Strength of lap joint was increased by 55.78%, 26.27% and 33.65% respectively