The task of rolling bearings is to guide moving parts and to absorb and transmit the forces acting on them. Rolling bearings must operate with low friction, reliably and with a long service life at changing speeds and high loads, sometimes also at higher temperatures.
Rolling bearing steels are characterised by high hardness and wear resistance as well as high fatigue strength. In addition, they must have sufficient toughness. The requirements are achieved by coordinated composition and precise adjustment of the microstructure. Here, the microstructure must also be homogeneous, without blowholes and harmful inclusions. For applications that require the highest purity and homogeneity and thus the highest resistance to rolling contact fatigue, special metallurgical manufacturing processes are used, e.g. special ladle metallurgical treatments, vacuum melting, electroslag remelting and vacuum arc remelting.
Classic rolling bearing steels are special steels that contain various alloying elements such as chromium, manganese or nickel in addition to carbon. Rolling bearings such as ball bearings or roller bearings are usually made of hardened chromium steel, which contains about 1% carbon and up to 1.5% chromium. For highly stressed bearings, e.g. in the aerospace industry, modified through-hardening high-speed steels (M50) and special case-hardened steel alloys (M50NIL) are also used.
Rolling bearing steels are used for rolling elements such as balls, rollers, needles and axles and spindles mainly in the automotive industry, aviation and mechanical engineering.
