Effect of boric acid concentration on the arc stability in underwater wet welding

To determine the arc stability during underwater wet welding in boric acid solutions with various concentrations, a real-time electrical signal acquisition system is established. Four methods for determining the arc stability, i.e., dynamic characteristics, probability distribution of voltage and current, current and voltage cyclograms, and coefficients of variation of voltage and current, were adopted. There were two short-circuited modes, which referred to the long-periodic short-circuits model and the short-periodic short-circuits model. Metal transfer images of the two modes were obtained, and the proportion of the long-periodic model increased with the concentration of boric acid in aqueous solution. The arc stability during underwater wet welding deteriorated with increasing the boric acid concentration.