Use of helium/nitrogen gas mixtures for the laser welding of stainless steel pipes

摘要

Process for welding together the two longitudinal edges of a sheet of austenitic, ferritic or martensitic stainless steel so as to obtain a welded pipe, employing at least one laser beam having a power ranging up to 12 kW, and in which a gas mixture is used that consists of 30% to 80% nitrogen by volume and of helium for the remainder (up to 100%). The stainless steel sheet has a thickness of 0.5 to 4 mm and the pipe obtained has a diameter of 5 mm to 50 cm. The welding is full-penetration welding.