Abstract
CO2 arc welding which is employed in the wet underwater welding has the following advantages.
(1) The process is simple to operate.
(2) In the safety aspects, the lower open voltage characteristics of arc welder is particulary helpful to avoid electric shock.
(3) Welds can be made in all positions.
But, in conventional wet underwater CO2 arc welding, nozzle-base metal distance was not more than 4 mm, therefore the welding operation was very difficult.
We studied the following system that was called curtain water type underwater CO2 arc welding aimed to improve this problem. In the dual flow system which we used, curtain water was introduced from the outer nozzle. By this system we could take nozzle-base metal distance about two times longer than that for conventional shielding system. As the results of radiographic examination, no difficulty was found to obtain the welds without blowholes. At the first step to develop this process, we report experimental results of down hand position butt welding for mild steel.
