Many a time the assist gas used for laser cutting applications needs to be non-reactive because stainless steels and its alloys react to oxygen leaving burn marks. Nitrogen is one non-reactive gas often used as a clean cutting gas.
When a metal is cut with nitrogen the molten shear is actively removed and because the gas does not react with the metal, no additional heat is generated. Also, since the molten steel has high viscosity higher gas pressure and laser power are required during the process.
When using nitrogen for cutting, increasing the pressure will result in faster cutting speeds. A pressure of 10 to 15 bar is ideal for mild stainless steel.