Influence of GMAW Parameters and Joint Configuration on the Metallurgical and Mechanical Characteristics of Dissimilar AISI 316/AISI 304 Welded Joints

This work presents an integrated study of gas metal arc welding (GMAW) for dissimilar 3mm AISI 316/AISI 304 stainless steel joints, addressing the critical interplay between joint geometry and heat input (Welding parameters). Three configurations, single-side butt, double-side butt, and V-joint, were welded under three distinct heat-input regimes. Schaeffler–Espy analysis (Cr eq/Ni eq = 1. 87) predicted 10 wt.% δ-ferrite in the 308L filler, a result confirmed by microscopy. Low heat input yielded fine equiaxed dendrites; moderate input produced coarser equiaxed grains enriched with lathy δ-ferrite (hardness 180-190 HV); and high input created mixed columnar + equiaxed structures. The V-joint consistently achieved defect-free penetration and optimal bead geometry, while the double-side butt joint exhibited central porosity at low input. The V-joint weld at 90 A, 20 V, and 12 L/m yielded the best balance of bead geometry, tensile strength exceeding 600 MPa, and superior Charpy toughness in the 304 heat-affected zone (HAZ). These results highlight the importance of selecting a V-joint configuration and appropriate welding conditions to enhance mechanical integrity and service life in numerous industrial applications, especially in oil and gas, desalination, and aerospace.