Influence of single and tandem-submerged Arc Welding on ASTM A572 Gr.50 steels

Abstract Square butt joints were prepared using two different materials, Niobium (Type 1) and Vanadium (Type 2) micro-alloyed ASTM A 572 Gr.50 steels, employing both single wire submerged arc welding (SAW) and two-wire tandem submerged arc welding (SAW-T) processes, with a constant heat input per unit length of 2.5 kJ/mm maintained throughout the study. The weld profile, microstructure, and mechanical properties were analyzed for SAW and SAW-T processes. It was observed that the weld width, hardness, yield strength, ultimate tensile strength, and impact toughness of the welds increased with SAW-T compared to SAW. Furthermore, a comparison was made between the two types of steel weld joints. Type 1 steel weld exhibited higher acicular ferrite, yield strength, and ultimate tensile strength due to the intra-granular nucleation of Niobium carbonitrides in austenite. In contrast, Type 2 steels displayed a higher percentage of elongation, hardness, and impact toughness at 25°C. At -20°C temperature, SAW-T welds show higher HAZ toughness than SAW welds. Also, Type 2 welds showed enhanced toughness in comparison to Type 1 welds by mitigating the pinning effect of precipitates.