Bearing steel performance requirements, common materials of bearing steel

Bearing steel is mainly used to manufacture rolling elements and rings of rolling bearings. Because the bearing should have the characteristics of long life, high precision, low heat generation, high speed, high rigidity, low noise, high wear resistance, etc., the bearing steel is required to have: high hardness, uniform hardness, high elastic limit, and high contact fatigue Strength, necessary toughness, certain hardenability, corrosion resistance in atmospheric lubricants. In order to meet the above performance requirements, strict requirements are imposed on the uniformity of the chemical composition of the bearing steel, the content and type of non-metallic inclusions, the size and distribution of carbides, and the decarburization. Bearing steel generally develops in the direction of high quality, high performance and multiple varieties. Bearing steels are classified according to their characteristics and application environment: high-carbon chromium bearing steel, carburized bearing steel, high-temperature bearing steel, stainless bearing steel and special special bearing materials.

In order to meet the requirements of high temperature, high speed, high load, corrosion resistance and radiation resistance, it is necessary to develop a series of new bearing steels with special properties. In order to reduce the oxygen content of bearing steel, smelting technologies for bearing steel such as vacuum smelting, electroslag remelting, and electron beam remelting have been developed. The smelting of large quantities of bearing steel is developed by electric arc furnace smelting to various types of primary smelting furnaces plus out-of-furnace refining. At present, the bearing steel is produced by a primary furnace with a capacity of more than 60 tons + LF/VD or RH + continuous casting + continuous rolling to achieve high quality, high efficiency, and low energy consumption. In terms of heat treatment process, it has developed from car hearth furnace and bell furnace to continuous controllable atmosphere annealing furnace for heat treatment. At present, the maximum length of the continuous heat treatment furnace is 150m. The spheroidization structure of the bearing steel processed and produced is stable and uniform, the decarburization layer is small, and the energy consumption is low.
Bearing steel should have the following properties:
1. High contact fatigue strength.
2. High wear resistance.
3. High elastic limit and yield strength.
4. High and uniform hardness.
5. Certain impact toughness.
6. Good dimensional stability.
7. Good corrosion inhibition performance.
8. Good process performance.
Common materials of bearing steel:
The selection of bearing steel material also requires specific requirements for purchase. For bearing materials that work under special conditions, they should also have special properties that are compatible with their conditions, such as: high temperature resistance, low temperature resistance, corrosion resistance, Anti-radiation, anti-magnetic and other characteristics.
Fully hardened bearing steel is mainly high-carbon chromium steel, such as GCr15, with a carbon content of about 1% and a chromium content of about 1.5%. In order to improve the hardness, wear resistance and hardenability, some silicon, manganese, molybdenum, etc., such as GCr15SiMn, are appropriately added. This type of bearing steel has the largest output, accounting for more than 95% of all bearing steel output.
Carburized bearing steel is a chromium, nickel, and molybdenum alloy structural steel with a carbon content of 0.08 to 0.23%. The rear surface of the bearing part is made of carbonitriding to improve its hardness and wear resistance. This kind of steel is used for manufacturing Large bearings that can withstand strong impact loads, such as large rolling mill bearings, automotive bearings, mining machinery bearings and railway vehicle bearings, etc.
Stainless bearing steels include high-carbon chromium stainless bearing steels, such as 9Cr18, 9Cr18MoV, etc., and medium-carbon chromium stainless bearing steels, such as 4Cr13, etc., which are used to make stainless and corrosion-resistant bearings.
High-temperature bearing steel is used at high temperature (300~500℃), which requires steel to have certain red hardness and wear resistance at the service temperature. Most high-speed tool steels are used instead, such as W18Cr4V, W9Cr4V, W6Mo5Cr4V2, Cr14Mo4, and Cr4Mo4V.


Post time: Nov-30-2021