Nitriding of steel (gas nitriding)

Nitriding is a process of infiltrating nitrogen atoms into the surface layer of steel. Its purpose is to improve the surface hardness, wear resistance, fatigue strength and corrosion resistance. It uses ammonia to decompose active nitrogen atoms during heating, and forms nitriding layer on the surface after being absorbed by steel, and diffuses to the center at the same time.
Nitriding is usually carried out by special equipment or well type carburizing furnace, which is suitable for various high-speed transmission precision gears, machine tool spindles (such as boring bar, grinder Master), high-speed diesel engine crankshafts, valves, etc.
Process route of nitriding workpiece: forging annealing rough machining quenching and tempering finish machining stress relief rough grinding nitriding finish grinding or grinding. Because the nitrided layer is thin and brittle, it requires a high strength core structure. Therefore, quenching and tempering heat treatment should be carried out first to obtain tempered sorbite, so as to improve the mechanical properties of the core and the quality of the nitrided layer. After nitriding, the steel has high surface hardness (higher than HV850) and wear resistance without quenching. Nitriding treatment temperature is low, deformation is very small, compared with carburizing, induction surface quenching, deformation is much smaller, steel carbonitriding: carbonitriding is the process of infiltrating carbon and nitrogen into the surface of steel at the same time, conventionally carbonitriding is also called cyaniding. At present, medium temperature gas carbonitriding and low temperature gas carbonitriding (gas soft nitriding) are widely used. The main purpose of medium temperature gas carbonitriding is to improve the hardness, wear resistance and fatigue strength of steel, while the main purpose of low temperature gas carbonitriding is to improve the wear resistance and anti bite property of steel.