What is the process of gas nitriding

What is the process of gas nitriding

        Gas nitriding includes three processes: exhaust, heating, heat preservation and cooling. The nitriding operation should be exhausted first and then the temperature rising, and the exhausting and heating can also be performed at the same time. Above 450℃, the heating rate should be reduced to avoid over-temperature. The nitrogen flow rate, temperature, ammonia decomposition rate and furnace pressure should be strictly controlled during the holding stage to ensure the quality of nitriding. After the nitriding and heat preservation, the power is cut off and the temperature is reduced, but the ammonia gas should be continuously passed to maintain a positive pressure to prevent air from entering and causing oxidation on the surface of the workpiece. When the temperature drops below 200℃, the supply of ammonia can be stopped and the workpiece can be released. Some workpieces that are not strictly required for distortion can be immediately lifted out of the furnace for oil cooling after heat preservation.