Case-hardening steels are produced using the process of case-hardening. This is divided into three steps. Carburisation, hardening and tempering. During carburisation, carbon is added to the material.
To achieve this, the material is placed in a carbon-containing medium and heated to between 880°C and 1050°C. The carbon diffuses through the high temperatures. The carbon diffuses into the surface layer due to the high temperatures, so that the carbon content increases to 0.8%.
This is followed by hardening and quenching. Here the steel is strongly heated and then rapidly cooled. In the third and final step, tempering, heating takes place at lower temperatures than in hardening.
Case hardening is used to obtain a hard surface layer and a tough core.
This makes case-hardening steel wear-resistant. The processing of the material can be divided into two areas. Case hardening steels can be machined before and after surface hardening. Before surface hardening, machining (milling, turning or drilling) and non-cutting machining can take place. After surface hardening, machining steps such as grinding,
eroding or polishing take place.

As mentioned before, case-hardened steels are difficult to weld, so this machining is done before case-hardening. After machining, case-hardened steels are used in mechanical engineering as bolts, joints, gears or as components in the automotive industry.