Study of underwater wet welding stability using an X-ray transmission method

The effects of arc voltage on the stability of the underwater wet flux-cored arc welding (FCAW-S 114) process are explained based on studying the droplet transfer process using the X-ray transmission method. The mode of metal transfer and the protective bubble effect, which vary with voltage, affect the stability of the welding process. The results indicate that there is a critical arc voltage (32 V). When the arc voltage is less than 32 V, an unstable welding process occurs because of the high proportion of short-circuit transfer and limited bubble size. Increase in the arc burning zone must be protected, and the proportion of repelled metal transfer caused by the high arc voltage decreases the stability of the welding process. In this study, stable welding process is acquired when the proportion of repelled metal transfer is less than 20%, the short circuit frequency is lower than 1 Hz and the bubble diameter is larger than 24 mm.