carburering

Carburering, or carburizing, is a heat treatment used to introduce carbon into the surface layer of iron- and steel-based alloys. The process creates a hard, wear-resistant case on the exterior while keeping a tougher, more ductile core.

The carburizing cycle typically involves heating parts to high temperatures in a carbon-rich environment. Common temperatures are about 900–950°C for gas or solid/carbon-pack methods. Carbon diffuses from the environment into the surface, increasing the carbon content of the case. The depth of the carburized layer depends on time, temperature, and the method used. After carburizing, the parts are rapidly quenched to transform the surface to martensite, then tempered to achieve the desired hardness and toughness.

Carburering methods include gas carburizing, pack carburizing, and liquid (salt bath) carburizing. Gas carburizing uses hydrocarbon-containing atmospheres; pack carburizing places the parts in a carbon-rich solid medium; liquid carburizing employs a molten salt bath. Post-treatment steps may also involve washing, tempering, and stress-relief operations.

Applications are typical for components that require a hard, wear-resistant surface and a tough core, such as gears, shafts, camshafts, crankshafts, bearing sleeves, and other transmission or heavy-duty parts. Typical case depths range from about 0.5 to 3 millimeters, with deeper cases possible for high-load applications.

Advantages of carburering include enhanced surface hardness and wear resistance, improved fatigue strength, and the ability to tailor surface properties without sacrificing core toughness. Drawbacks include process complexity, equipment and energy costs, risk of distortion or decarbonization if not properly controlled, and the need for precise process parameters. Related processes include carbonitriding, which introduces nitrogen to modify case properties.