Influence of calcium fluoride on underwater wet welding process stability

To explore the influence of calcium fluoride on underwater wet welding process stability, the relevance of calcium fluoride in the flux to metal transfer mode and arc stability was discussed in the process of underwater wet welding using a set of wires with various calcium fluoride contents. The metal transfer images were obtained using X-ray imaging system and the electric signal detection system was used to collect arc voltage and welding current signals synchronized with the film frames. Three metal transfer modes, i.e., repelled globular transfer, surface tension transfer, and spatter-like metal droplet transfer, were observed during the underwater wet welding process. The spatter-like metal droplet transfer mode was put forward firstly. Increasing the contents of calcium fluoride in the wire from 0 to 65%, the proportion of surface tension transfer mode steadily climbed from approximately 15 to 40% while that of spatter-like metal droplet mode declined from 53 to 35%. The arc stability of the welding process firstly deteriorated and then ameliorated with the increasing calcium fluoride content.