Optimization of electromagnetic steel lamination laser spot welding process parameters using response surface methodology

Abstract Electrical steel is a critical material for key components such as electric motors and transformers. Conventional continuous welding, characterized by high heat input and a wide heat-affected zone (HAZ), often leads to magnetic degradation. To address this issue, laser spot welding is adopted to achieve precise energy control and reduced thermal impact. Response surface methodology (RSM) based on a central composite design (CCD) is employed to investigate the effects of laser power, pulse width, and defocus distance on shear strength and weld spot cross-sectional area. Analysis of variance (ANOVA) confirms the significance of the selected factors, and regression models are developed, achieving R 2 values of 0.88 and 0.82, respectively. Optimal process parameters are determined through RSM optimization and confirmed by additional one-factor-at-a-time (OFAT) experiments. Simplified models are developed to improve predictive accuracy and practical applicability, and their validity is verified through experimental results. In addition, the influence of pulse shape is examined by comparing rectangular, ramp-up, ramp-down, and triangular profiles. The results indicate that the ramp-down pulse effectively suppresses thermal cracking and porosity by moderating solidification behavior, leading to improved weld stability and quality.