Optimization of welding parameters in electric resistance spot welding

Electric resistance spot welding is one of the main joining methods in many sectors, especially in the automotive sector. The important point in the application of electric resistance spot welding is the welding parameters that affect the welding quality during the welded joint. In this thesis, DP180 1.2 mm steel sheets were used for welded joining. After joining with electrical resistance spot welding, the welding parameters were optimized using Gray Relational Analysis method and at the same time, the most suitable test combinations values were determined for maximum tensile strength and minimum indentation rate using genetic algorithm method. Values of welding parameters such as welding current, welding time and electrode pressure force were determined according to L9 Taguchi orthogonal index with random approximation. In order to determine the mechanical properties of the welded samples, a tensile test was performed on the welded joints. After the welding process, the penetration rate of the welded samples was calculated. The highest-best and lowest-best quality control characteristics were applied with the Taguchi method and the results were given graphically. Optimum welding current, welding time and electrode force were found to be 8000 A 0.25 s and 2000 N, respectively. As a result of the ANOVA test, it was seen that the most effective parameter was the electric current with 65.98%. The predicted breaking strength as a result of the genetic algorithm was determined as 17,84 kN, and the penetration rate was determined as 34.15%. As a result of the study, it was observed that the results obtained in the Genetic algorithm, Taguchi Method and Gray Relational analysis method were consistent with each other.