Carbonitriding is a thermochemical heat treatment process used to increase the surface hardness and wear resistance of steel components. The process introduces both carbon and nitrogen into the surface layer of the metal, creating a hardened case while maintaining a tough, ductile core.

Carbonitriding is particularly effective for components that require improved fatigue strength, wear resistance, and dimensional stability without compromising the toughness of the base material. It is commonly used for small to medium-sized parts such as gears, fasteners, shafts, pins, and other precision components used in demanding industrial applications.

Carbonitriding Mechanism

During the carbonitriding process, components are heated in a controlled furnace atmosphere containing carbon-bearing gases and ammonia (NH₃). As the steel reaches the appropriate temperature, nitrogen from the ammonia gas reacts at the surface and diffuses into the metal together with carbon.

The introduction of nitrogen enhances the hardenability of the steel, allowing the desired hardness to be achieved with less severe quenching. This helps reduce quenching distortion while maintaining high surface hardness and wear resistance.

The result is a hardened case that provides improved durability, fatigue resistance, and long-term performance for parts operating under demanding conditions.