Primarily, high carbon chromium bearing steel is used for the bearing rings and rolling elements. Most NSKF bearings are made of SUJ2 among the JIS steel types, while the larger bearings generally use SUJ3. The chemical composition of SUJ2 is approximately the same as AISI 52100 specified in the USA, DIN 100 Cr6 in Germany, and BS 535A99 in England.
For bearings that are subjected to very severe shock loads, carburized low-carbon alloy steels such as chrome steel, chrome molybdenum steel and nickel chrome molybdenum steel , are often used. Such steels, when they are carburized to the proper depth and have sufficient surface hardness, are more shock-resistant than normal, through-hardened bearing steels because of the softer energy-absorbing core.
NSKF uses highly pure vacuum-degassed bearing steel containing a minimum of oxygen, nitrogen, and hydrogen compound impurities. The rolling fatigue life of bearings has been remarkably improved using these materials combined with the appropriate heat treatment.
For special-purpose bearings, high-temperature bearing steel , which has superior heat resistance, and stainless steel , which has good corrosion resistance, may be used. |
