Rolling bearing materials include rolling bearing parts and cage materials, rivets and other auxiliary materials. The vast majority of rolling bearings and parts made of steel, rolling bearing steel is usually high-carbon chromium steel and carburized steel. With the development of science and technology in modern times and the increasing use of rolling bearings, bearing requirements are getting higher and higher, such as high precision, long life and high reliability. For some special purpose bearings, but also requires bearing materials with high temperature, corrosion resistance, non-magnetic, ultra-low temperature, radiation resistance and other properties. In addition, the bearing material also includes alloy materials, non-ferrous metals and non-metallic materials. In addition, the bearings made of ceramic materials are now used in locomotives, automobiles, subway, aviation, aerospace, chemical and other fields. The basic requirements of the material of the rolling bearing depend largely on the working performance of the bearing. The choice of materials to make rolling bearings is appropriate and will have a significant impact on their serviceability and longevity. Under normal circumstances, the main form of failure of rolling bearings are fatigue spalling under the effect of alternating stress, as well as the loss of bearing accuracy due to friction and wear. In addition, there are cracks, indentation, rust and other causes of abnormal bearing damage. Therefore, the rolling bearing should have high resistance to plastic deformation, less friction and wear, good rotation accuracy, good dimensional accuracy and stability, and long contact fatigue life. And many of these properties are determined by both the material and the heat treatment process. As the basic requirements of rolling bearing material is determined by the form of damage to the bearing, so the requirements for the manufacture of rolling bearing material after a certain heat treatment after the process should have the following properties: A high contact fatigue strength Contact fatigue damage is the main form of normal bearing damage . Rolling bearing operation, the rolling element in the bearing, the outer race rolling between the raceway, the contact part of the cyclical alternating load to bear, many of them up to hundreds of thousands of times per minute, alternating periodic alternating stress, the contact surface Fatigue spalling appears. Rolling bearing began to appear after peeling will cause bearing vibration, noise, the working temperature rose sharply, resulting in the final bearing damage, this form of damage known as contact fatigue damage. Therefore, the requirements of rolling bearing steel should have high contact fatigue strength. Two high wear resistance Rolling normal work, in addition to rolling friction, but also with sliding friction. The main parts of the sliding friction occurs are: the contact surface between the rolling element and the raceway, the contact surface between the rolling element and the cage pockets, the guide between the cage and the ferrule and between the roller end surface and the ferrule Between the ribs and so on. The presence of sliding friction in a rolling bearing inevitably causes wear on the bearing components. If the wear resistance of the bearing steel is poor, the rolling bearing will lose its accuracy prematurely due to wear or the vibration of the bearing will increase due to the decrease of the rotation precision and the life will be reduced. Therefore, the requirements of bearing steel should have high wear resistance. Three high limit of elasticity of the rolling bearing work, the contact area between the rolling element and the raceway is very small, the bearing load, especially in the case of large loads, the contact surface of the contact pressure is large. In order to prevent the occurrence of excessive plastic deformation under high contact stress, loss of bearing accuracy or surface cracks, therefore, the requirements of bearing steel should have high elastic limit. Four suitable hardness Hardness is one of the important indexes of the rolling bearing. It is closely related to the fatigue strength, wear resistance and elastic limit of the material, which directly affects the life of the rolling bearing. The hardness of the bearing usually depends on the way and size of the bearing under load, the bearing size and the overall thickness of the bearing. Rolling bearing steel hardness to be appropriate, too large or too small will affect the bearing life. As we all know, the main failure of rolling bearing contact fatigue damage, and due to poor wear resistance or dimensional instability and the loss of bearing accuracy; bearing parts if the lack of a certain toughness, under greater impact load will be due to the occurrence of brittle fracture Bearing damage. Therefore, we must be based on the specific circumstances of the bearing and the way to determine the destruction of the bearing hardness. Bearing due to fatigue spalling or poor wear resistance to the loss of the case, the bearing parts should be used higher hardness; bearing greater impact load bearing (such as rolling mill: bearings, railway bearings and some automotive bearings, etc.) should be appropriately reduced Hardness to improve bearing toughness is very necessary. A certain amount of impact toughness A lot of rolling bearings in the course of the application will be set by the impact load, so the bearing steel requires a certain degree of toughness to ensure that the bearing is not damaged due to impact. For bearing a greater impact load bearings such as rolling bearings, railway bearings and other materials required has a relatively high impact toughness and fracture toughness, some of these bearings with bainitic quenching heat treatment process, and some with carburized steel, that is Ensure that these bearings have good impact toughness. Six good dimensional stability Rolling is a precision mechanical parts, the accuracy is calculated in microns. In the long-term custody and use of the process, due to internal organizational changes or stress changes will cause the bearing size changes, leading to loss of bearing accuracy. Therefore, to ensure the dimensional accuracy of bearings, bearing steel should have good dimensional stability. Seven good anti-rust performance Rolling production process a wide range of production cycle longer, and some semi-finished or finished parts in the assembly also need a long time before storage, therefore, bearing parts in the production process or in the finished product are very easy to save Some rust occurs, especially in humid air. Therefore, the requirements of bearing steel to have good anti-rust properties. Eight good technical performance Rolling bearings in the production process, the parts to go through multiple cold and hot processing processes. This requires bearing steel should have good process performance, such as cold, thermoforming performance, cutting, grinding performance and heat treatment performance, etc., to meet the high-volume, high-efficiency, low-cost and high-quality production needs. In addition, the bearings used under special operating conditions, in addition to the above several basic requirements, the steel must also be made to the corresponding special performance requirements, such as high temperature performance, high speed performance, corrosion resistance and anti-magnetic properties.
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