Effect of Process Variables for Reducing Assist Gas Pressure in 50 mm-Thick Stainless Steel Underwater Laser Cutting

While dismantling nuclear power plants, the reactor vessel internal is cut underwater using mechanical and thermal cutting. In laser cutting, assist gas must be used to remove melted metal; consequently, a large number of radioactive aerosols can generated. To reduce generation aerosols, pressure should lowered. However, below limit, molten metal not well-removed from surface fails cut. this study, an visualization experiment was performed find condition for flow well inside surface, even at low pressures. The top kerf width, nozzle type, distance between specimen, were selected as process parameters, in case width condition, able penetrate deeply. actual laser-cutting experiment, beam focus position set −20 mm −30 mm. mm, widened due characteristics profile, cutting successful though lowered by 20%.