The effect of alumino-thermic addition on underwater wet welding process stability.

Real-time electric signal data, metal transfer images and weld appearances at different alumino-thermic additions in underwater wet flux-cored arc welding (FCAW) were obtained. The electric signal results showed that the thermite addition would improve the stability of the wet welding process while the weld appearances at larger content of thermite displayed numerous tiny spatters. The shock in weld pool due to metallurgical reaction was responsible for the tiny spatters. Two typical modes of metal transfer process, globular repelled transfer mode and surface tension transfer mode, were observed. The aluminum flux addition changed the droplet diameter, transfer time and relative proportion of metal transfer mode. When the thermite addition increased from 0 to 50%, the weld penetration depth increased from 2 mm to 4 mm, and the weld dilution rate increased from 22% to 37%. [ABSTRACT FROM AUTHOR]