Karburiseerimist

Karburiseerimist, also known as carburizing, is a heat‑treating process used in the manufacturing of high‑strength steels. During the process, the steel workpiece is exposed to a carburant atmosphere—typically a mixture of gases containing carbon or a carbon‑rich material—at temperatures between 900 °C and 950 °C. The carbon diffuses into the steel surface, increasing its carbon content. After the carburization step, the part is quenched, which hardens the surface while leaving the core relatively soft and ductile.

The main purpose of carburizing is to improve wear resistance, fatigue life and impact strength of steel components. Tubes, gears, bearings, camshafts, crankshafts and other high‑wear parts often undergo this treatment to achieve a high‑surface hardness with a tough interior. By allowing controlled diffusion, carburizing creates a graded hardness profile that reduces the risk of cracking, which would be more likely with a hard surface applied to a brittle material.

There are several variations of the carburizing technique. Strip carburizing involves heating a steel strip in a carburant furnace; surface carburizing uses a molten salt bath; and gas carburizing employs a controlled gas mixture to provide a uniform carbon concentration. Each method offers different control over the depth and uniformity of the carburized layer.

Advantages of carburizing include improved durability, better resistance to abrasion and corrosion, and the ability to tailor hardness gradients. However, the process requires precise temperature control and can induce residual stresses, sometimes necessitating tempering or stress‑relief steps. Additionally, thinner gauge materials may be difficult to carburize effectively because carbon diffusion can be too rapid, leading to uneven layers.