The Influence And Role Of Helium And Nitrogen As Shielding Gases In 2KW CO2 Laser Welding Of Austenitic Stainless Steels : Physical, Geometrical And Technological Characterization

Abstract

Laser welding processes require nozzles with a " large " outlet in order both to avoid turbulent gas flow which can cause removal of the melt and to ensure an adequate protection of the melt against atmospheric oxidation. The gas can be supplied in a variety of ways but in this work the coaxial gas-laser beam geometry was used. CO2, He and N2 have been tested as covering gases with flows between 30+100 Nl/min. It has been observed that, once the gas and the steel have been set, the penetration depth and the width of the melted zone are, in the majority of cases, virtually constant when the flow rate increases from 30 to 100 Nl/min.