In antifriction bearings the coupling is achieved by means of bodies which roll with respect to both the pin and the fixed part. There are also the following types of bearings: friction bearings, thrust bearings, axial bearings, journal bearings, sliding bearings, step bearings etc.

Bearing steels must have low inclusion content since their continuous rolling and sliding causes significant compressive and shear stresses. These stresses, which are concentrated under the surface, often give rise to inclusion-generated cracks. In other mechanical structures, such as shafts subject to twisting, fatigue failures almost always have an external origin.

102Cr6
This category, which claims a long tradition in this sector, is marked by its high carbon and chromium content. They are commonly known as “fully hardening steels”.
This steel is genarally used for small bearings, balls, rollers and rings, in which hardening reaches their entire mass (thickness 20-30 mm).Furthermore, in some applications, induction hardening is added in order to further increase surface hardening. Deformations after hardening are relatively few, even with a hardness of about 62-63 HRC. Isothermal annealing goves these steels good workability and an excellent attitude for cold plastic deformation.

100CrMo7
When the sections become medium or large, this type of steel is recommended, for the above listed uses, as it has a better hardenability. Its chemical composition allows for a higher hardness (64 HRC), which is useful in terms of wear resistance and operational deformations. Quenching is carried out in oil in order to avoid cracks and excessive shape modifications, decreasing the subsequent grinding operations.
Main applications: straightening rolls, forming rolls, crushing rolls, cylindrical rolls, piling rolls for cold-rolled strip.

The most common bearing steels are:

102Cr6 – 100CrMo7 – X82WMoCrV6-5-4