Influence of Stick Electrode Coating’s Moisture Content on the Diffusible Hydrogen in Underwater Wet Shielded Metal Arc Welding

In shielded metal arc welding, the major factors influencing hydrogen uptake into the weld metal are (i) the hydrogen content of the base metal, (ii) hydrogen input by the welding consumable, and (iii) the hydrogen introduced by the atmosphere surrounding the arc process. In this study, the relative contribution of these factors is investigated and compared to each other for the case of underwater wet shielded metal arc welding. To assess the influence of the stick electrode’s moisture (capillary introduced water during handling operations) on the diffusible hydrogen in wet welded samples, wet and dry electrodes were welded at four different water depths. The moisture was absorbed through the sharpened electrode tip only, to ensure close to service conditions. The results show that the moist stick electrode coatings lead to 22.6% higher average diffusible hydrogen content in the weld metal (0.5 m water depth an average). However, the effect disappears with increasing water depths (no difference in 60 m water depth).