The Influence of Nitrogen from Welding on Stainless Steel Weld Metal Microstructures Soluble nitrogen is found to exert a major influence—particularly on the quantity and distribution of weld metal delta ferrite

Small amounts of nitrogen were injected into Type 304L austenitic stainless steel weld metal. This was accomplished by using an argon-nitroge n shielding gas mixture on autogenous gas tungsten arc welds. Weld metal nitrogen as a function of nitrogen shielding gas content and applied pressure was exam­ ined. Nitrogen shielding gas contents below 5% were found to have a major effect on the weld metal microstructure. The base metal nitrogen did not influence the nitro­ gen solubility reaction and solidification behavior during welding. For Type 304L austenitic stainless steel, a nitrogen coeffi­ cient was determined for the nickel equivalent expression.