Effects of nitrogen content and welding current on microstructure and properties of the weld of high nitrogen austenite steel

In order to tackle the problems of porosity and resultant depression of mechanical properties induced by the escape of nitrogen gas during welding process of the high nitrogen stainless steel, two kinds of austenitic steel welding wire with nitrogen content of 0.35% and 0.85% were designed and prepared based on the results calculated by Thermo-Calc software. The effects of nitrogen content and welding processes on porosity, microstructure and mechanical properties of high nitrogen austenite steel weld were investigated. The results showed that the porosity and mechanical properties of high nitrogen austenitic stainless steel weld were strongly dependent on the welding current and the nitrogen content of welding wire. When the nitrogen content of wire was 0.35%, tensile strength and elongation increased as welding current increasing, and no porosity could be observed in the weld. When the nitrogen content of wire was 0.85%, the changes in tensile strength and elongation were negligible, and there were more porosities in the weld, the number of porosity in the weld was diminished sharply after the welding current increased to a critical value.