Suitable Materials for High Speed Bearings

Sep 08, 2021

The materials used for high-speed bearings have their own unique aspects. When the DMN value is small, the failure form of the bearing can be the fatigue spalling of the surface or subsurface layer, while when the DMN value exceeds 2.5 million, the fatigue layer cracks develop to the depth, and the inner ring will spalling into blocks when it is serious. In this regard, the surface hardening steel with high surface strength and high internal toughness can be used to manufacture rings. Typical steels of this type are AISI8620, CBS600, CBSl000M and vascox-2 etc Military grade steel and Electroslag remelting steel.

High-speed bearings sometimes work in high temperature or high temperature environment because of their high temperature, but there are different requirements than the general high temperature conditions. For example, For high-speed bearings working at 220℃, high-temperature materials are required to be selected according to 315℃, because high-speed bearings require higher high-temperature hardness to resist deformation trend caused by speed effect at high speed. The steels commonly used in high temperature high-speed bearings are M50, M2, WB49 and M315, among which M50 steel smelted by vacuum induction method and then remelted by vacuum arc method can improve the life of M50 steel by more than 5 times than that smelted by vacuum induction method alone, so it is widely used.　　

Although high-speed bearings do not seem to be directly involved in corrosion problems, a considerable proportion of high-speed bearings fail due to material corrosion. When encountering such problems, bearings made of corrosion-resistant alloys, M50 steel injected with chromium ions and silicon nitride ceramics and other materials can be used.　　

The cage of high-speed bearings requires high strength materials. AMS 4616 silicon bronze and S-Monel alloy can be used in high demand occasions. The most commonly used iron alloy AISl4340(AMS6415) requires heat treatment hardness in the range of HRC28 ~ 36. To further improve the friction characteristics of the cage, a silver film of 20-50μm is usually coated on the surface (e.g. AMS2412 and 2410).　

The application of ceramic materials in high-speed bearings is expected to have a great prospect, in which Si3N4 material has a longer life than M50 steel, and its proportion is only 40% of steel, has been used to manufacture rolling body and even ring, and proved to have excellent high-speed, high temperature adaptability and corrosion resistance, but the current manufacturing cost is very high.