This process involves the carbon saturation of a steel surface if a high level of component hardness is required while maintaining a relatively soft and tenacious core (pins, shafts, gearwheels, etc.). For carburization low-carbon steels with carbon content between 0.1 and 0.25 % are used. Examples of cementing steels: 12 010, 12 020, 14 220 a 16 220. The most frequently used steel is 14 220, which contains about 1% Mn and 1% Cr.
The surface of the components is usually enriched by carbon to an eutectoid concentration, i.e. 0.8 % C. Carburization occurs at an approximate temperature of 50°C above AC3 temperature (with the presence of austenite, usually in temperature intervals of 880 to 950°C). The depth of the carburized layer is 0.5 to 2 mm. Carburization is followed by the hardening of components. The final heat treatment operation after carburization and hardening is tempering at temperatures between 140 and 200°C (or up to 250°C). The surface hardness of these components may reach 58 to 62 HRC.