OPTIMIZATION OF GMAW AND GTAW PARAMETERS TO IMPROVE TENSILE STRENGTH OF WELDED JOINTS OF A36 STEEL PLATE

Abstract

Achieving high-quality welds is essential for structural integrity in the manufacturing and construction industries. This study investigates the optimization of Gas Metal Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW) parameters for A36 steel plates, using the Taguchi Method to assess the effects of different shielding gas compositions, including the unconventional use of Argon mixed with active gases in GTAW. Welding specifications provide safe parameter ranges, but these may not reflect optimal conditions for specific materials or processes. This highlights the need for optimization studies to identify the best parameter settings. Shielding gas composition, welding current, and root gap were evaluated as independent factors, with tensile strength as the response variable. An L9 orthogonal array was utilized to design the experiments, requiring 45 tensile test observations for robust statistical analysis. Specimens were welded using shielding gases of Ar with 10% CO₂, Ar with 5% O₂, 100% Ar, and 100% CO₂ and subjected to tensile strength tests. Signal-to-Noise (S/N) ratio analysis identified the optimal parameters as 100% CO₂, 140 A, and a 2.5 mm root gap for GMAW; and Ar with 10% CO₂, 120 A, and a 2.5 mm root gap for GTAW. Regression analysis confirmed that shielding gas and current significantly influence tensile strength, with ANOVA showing shielding gas as the most critical factor. The use of mixed shielding gases with active components in GTAW notably enhanced tensile strength, suggesting potential for both performance improvement and economic viability in industrial applications once it becomes more accessible.