The most common material for bearings is bearing steel. The internal structure of the bearing, the uniformity of chemical composition, the non-metallic inclusions contained, the size and distribution of carbide particles, and the degree of decarburization are very strict. Otherwise, these defects will significantly shorten the life of the bearing. The service life and applicability of materials.

The purity of bearing steel The fatigue spalling of bearing parts is related to non-metallic inclusions in steel, especially oxides. This is because when the rolling bearing rotates, the contact surface of the bearing parts is under the action of pulse load, and the non-metallic inclusions cause local damage to the continuity of the matrix structure of the steel, causing internal stress concentration, plastic deformation around the non-metallic inclusions, and the formation of microcracks .

In addition, the content of gas (oxygen, nitrogen, hydrogen) in bearing steel is also an important indicator of purity. Oxygen dissolved in steel precipitates as the temperature decreases and forms oxide inclusions with aluminum, calcium, silicon, manganese and other elements, nitrogen forms very diffuse aluminum nitride inclusions and coarser titanium nitride and titanium carbonitride in steel Inclusions, when the aggregated hydrogen atoms combine to form hydrogen molecules, great pressure will be generated. Once the strength limit of steel is exceeded, internal cracks will occur and white spots will be formed. Reducing gas content is an important part of improving the purity of bearing steel.

The life and reliability of the bearing are related to the structural design of the bearing, the materials used, the cold and hot processing technology and equipment, installation and service conditions and other factors. Among them, the material and heat treatment are one of the main factors affecting the life and feasibility of the bearing. Due to the influence of materials and heat treatment processes, factors such as low material strength, poor purity, unreasonable fiber structure orientation of metal materials, low hardness, unsuitable forging ratio, and large residual stress can easily damage the bearing. The impact of foreign steel quality on bearing life accounted for about 50% in the 1950s and 1960s, and reduced to 1/3 in the 1980s. my country is currently affected by technology and equipment, and the quality of bearing steel accounts for about 60% of the bearing life. Therefore, for bearing manufacturers, the selection of qualified and high-quality bearing materials is also one of the key factors to improve bearing life.