Multi-layer deposition technique to join dissimilar thick sections using GMAW-Pulse

Joining dissimilar thick-section metals presents significant challenges due to differences in chemical composition, thermal conductivity, and expansion behavior often leads to development of residual stresses, microstructural incompatibilities, and intermetallic phase formation. This study explores a multi-layer (layer-by-layer) deposition technique using Pulsed Gas Metal Arc Welding (GMAW-Pulse) to achieve high-quality welds between dissimilar thick-section materials with reduced four number of weld pass to almost (57 ± 5)% reduced groove volume compares to conventional gap weld of 25 mm thick sections. The process involves gradual multi-pass deposition with controlled heat input at each layer to manage thermal gradients and reduce distortion. A specially designed modified water-cooled weld torch nozzle with a substantially narrow nozzle head was developed, allowing the weld groove to be minimized to the extent that it can just accommodate the nozzle itself. In this configuration, the groove walls of the thick base metal section effectively serve as extensions of the nozzle’s side walls, enabling the production of the narrowest possible butt weld. ER308L ASS (Filler wire) and argon shielding gas are utilized to enhance fusion characteristics and prevent contamination. This study offers a cost-effective approach for fabricating dissimilar thick-section joints, particularly demanding for high-temperature performance in power generation industries.