Optimization of bead geometry for duplex stainless steel GTA welds using the Taguchi approach

Abstract Single pass, autogenous flat butt welds were made on 6 mm thick duplex stainless steel (2205) plates using gas tungsten arc welding (GTAW) process. Four of the welding process parameters, i. e., arc current, welding speed, shielding gas flow rate and arc gap, were varied each at four levels and welding trials were conducted as per an L 16 orthogonal array derived using the Taguchi methodology. Bead geometry parameters, depth of penetration and aspect ratio (width-to-depth ratio) were measured on polished and etched samples using microstructural image analysis. Tabulated results were subjected to analysis of variance and effects of each parameter on bead geometry were calculated. It has been found that welding current and welding speed are the dominant parameters determining the bead geometry. Gas flow rate also plays a key role in influencing the aspect ratio of the welds. Equations have been presented to predict depth of penetration and aspect ratio of the weld.