Numerical analysis of molten pool behavior during underwater wet FCAW process

Underwater wet flux-cored arc welding is a candidate method for onsite fabrication and maintenance of underwater structures. For a systematic understanding of physical mechanisms of this welding process, transient three-dimensional CFD models encompassing the effects of slag and underwater environment on heat and mass transfer within the weld pool are developed. The roles of droplet impingement, gravity, electromagnetic force, surface tension and interface tension on weld pool evolution under wet environment are discussed and compared with those in conventional flux-cored arc welding. Results show that in the underwater process, there exists a considerable vortex flow on the longitudinal section of weld pool, which transfers a large amount of heat to the bottom of weld pool. The region of fluid flow on molten pool surface is more restrained in the underwater process because of the rapid water cooling effect as compared with the conventional process. Good agreement is found between the predicted and the experimental weld beads under different welding parameters. The presented models can be used for further study of the underwater process.