Spectroscopic analysis of the arc plasma of underwater wet flux-cored arc welding

Abstract Experiments in air and under water (0.4 m depth) were conducted and the spectrum signals collected. The width of the weld under water was about two-thirds of the width in air, suggesting that the arc plasma was compressed by the water environment. The two sets of spectrum signals were largely similar except for the ultraviolet spectrum, from where the environmental effects were inferred. The analysis identified a unique peak at 656.2793 nm in the underwater spectrum, consistent with H atomic transitions, suggesting that H atoms become involved, although without affecting the overall spectral similarity of the two environments. In either environment the arc plasma was mainly composed of self-shielding gas and evaporated metals, with only minor effects stemming from the interaction with water.