DEVELOPMENTS IN A-TIG WELDING

Experiments with fluxes for TIG welding which increase the penetrating capability of the process were conducted in order that the mechanism may be better understood. Various theories proposed to account for the increased penetration were discussed and used to determine an experimental programme of work with welds made by the TIG, laser and electron beam processes. It is concluded that the increased penetration is related to arc constriction rather than a change in the thermal coefficient of surface tension (TCST) or any other mechanism. Productivity benefits associated with the increased penetration are noted. It is also proposed that as the mechanism is related to arc constriction rather than TCST the A-TIG process will not be susceptible to problems with inconsistent penetration due to cast to cast variation in stainless steels. Recent developments for the fluxes have concentrated on developing procedures with filler wire giving increased penetration and developing fluxes for other materials such as titanium and nickel alloys.