Influence of Polarity On the Stability of Underwater Wet Welding Process with Coated Electrode

Abstract

Due to of its great versatility and low cost, SMAW is considered the most used process in the naval and offshore industry. However, as a result of having the electric arc in direct contact with the aqueous medium, the use of the technique is affected by the hydrostatic pressure acting on both the arc column and melting pool, as well as the dynamics of bubble generation and water decomposition. The combination of the above factors influences the process stability, resulting in weld beads with large amounts of defects. In this particular point, it is emphasized that the definition of stability in UWW is poorly understood, a fact by which there are diverse opinions in industry and literature, without explanation of the phenomenon. Thus, this study characterizes the stability in function of one of the electric characteristics of the arc: the polarity. The configuration of this last factor defines the resulting characteristics in the joint; thus, the cathode and anode phenomena that govern the generation of heat influence the shape of the bead or the fusion rate of the consumable. In this research, it was used a commercial rutile electrode and a consumable that shows promising results in terms of mechanical properties and Diffusible Hydrogen content: WW70.

Key-words:
Polarity; Stability; Coated electrode; Underwater wet welding