| Abstract Scope |
Underwater wet welding (UWW), particularly flux-cored arc welding (FCAW), is widely reported to produce welds with degraded mechanical properties due to elevated cooling rates and reduced arc stability. These deficiencies arise primarily from bubble dynamics at the arc/weld pool interface, which extract heat rapidly and destabilize the process. Prior work in this research program demonstrated that incorporating submerged arc welding (SAW)-style fluxes into the underwater FCAW process can mitigate these effects. Using a Lincoln Power Wave 455/STT system with CORESHIELD 8 (1/16") wire, over 150 bead-on-plate welds were performed across multiple flux formulations, including commercial fluxes (Lincoln P2000, Sandvik 35WF/15W), crushed electrode coatings, and custom flux-to-epoxy resin blends (35/65 ratio) containing varying CaF₂ content. Results showed that the optimized flux formulation (Data 2) improved voltage stability, reduced cooling rate by 11%, and improved reinforcement-to-penetration width ratio by 36% relative to the unfluxed baseline.
Building on these findings, current work investigates electroslag welding (ESW) as a further evolution of this process pathway. ESW eliminates the arc entirely, relying on resistive heating through a molten slag bath rather than direct arc/water contact. This research examines the transition from gas-shielded (FCAW) to slag-shielded (flux-assisted FCAW) to fully resistive (ESW) heat generation as a strategy to progressively suppress bubble-driven heat extraction and arc instability in underwater conditions. By removing the arc as the primary heat source, ESW is hypothesized to further reduce cooling rates and improve weld bead geometry and mechanical performance beyond what flux addition alone can achieve. This work aims to establish ESW as a viable underwater welding process for applications requiring improved metallurgical quality in submerged repair and construction environments. |