Efeito da polaridade, profundidade e corrente no desempenho operacional da soldagem subaquática com eletrodos revestidos de aço inoxidável

Abstract

Wet underwater welding with coated electrodes is the most versatile and practical option for assembly and maintenance of components in the offshore and marine industry. In this environment, some optimizations of process variables can cause a decrease in discontinuities, defects and the presence of resistance-reducing elements such as diffusible hydrogen. Using a statistical study with two-level factorial analysis and four variables, the responses to changes in welding depth, polarity, current and alternation of two electrodes parameters were evaluated. Stainless steel electrodes with rutilic coating, specifications E309L-17 (E309) and E312L-17 (E312) were used, widely used in high resistance dissimilar joints. The responses collected were diffusible hydrogen value, short circuit values, average voltages, electrode melting rate and welding speed, and weld metal cross-section geometry dimensions. It was possible to verify the welds with lower values of diffusible hydrogen performed at greater welding depths, lower currents and reverse polarities. The depth as the parameter with the greatest impact, in the amount of diffusible hydrogen, in the amounts of transfer by short circuits, in the average voltage and in the welding penetration. The E312 electrode presented lower values of diffusible hydrogen and average voltage and higher values of short circuits in relation to E309. The welding speed and melting rate show different behaviors in each polarity when going from the water depth to 30 meters deep.