Bead geometry optimization in GMAW-based WAAM using 1.36Cr–0.5Mo steel metal-cored wires

This study focuses on optimizing bead geometry in GMAW-based WAAM using 1.36Cr–0.5Mo steel metal-cored wire to enhance build quality and consistency. The effects of input parameters—namely travel speed, shielding gas composition, and voltage—were assessed with regard to bead geometry, specifically Bead Width (BW), Bead Height (BH), and Depth of Penetration (DOP). To identify the optimal set of variables for experimentation, a Box–Behnken Design within the Response Surface Methodology (RSM) was utilized. Analysis of Variance (ANOVA) was also employed to validate the effectiveness and relevance of the correlations developed from the experimental results.The findings revealed that travel speed had a stronger influence on DOP and BH, whereas voltage primarily affected BW. Main effect and residual plots were used to determine the most significant independent factors and to evaluate the accuracy of the developed models for DOP, BH, and BW. Grey Relational Analysis (GRA) was further applied to determine the optimal combination of input parameters required to achieve the best overall performance. The most favorable parameters obtained through GRA were: voltage = 26 V, travel speed = 6 mm/s, and 5 percent CO₂ in the shielding gas mixture. Experimental validation conducted under these optimized parameters showed an average deviation of less than 6 percent between the actual and predicted values. Additionally, the multilayer structures synthesized under these conditions exhibited no indications of disbondment.