**Factors Affecting Bearing Life and Their Control** Home > Bearing Knowledge > Elements and Control That Affect Bearing Life *Created on 2018/5/16* var cpro_id = "u3440131";

Factors Affecting Bearing Life and Control

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/*250*250 was created on 2017/12/25*/ var cpro_id = 'u3171089';

Bearing life is influenced by a variety of factors, including material properties, heat treatment processes, and operational conditions. Understanding these elements is essential for improving the performance and longevity of bearings. ### 1. Early Failure Modes in Rolling Element Bearings The primary failure modes of rolling element bearings include cracking, plastic deformation, wear, corrosion, and fatigue. Under normal operating conditions, fatigue is the most common cause of failure. The mechanical behavior of bearing components depends on several key factors such as hardness, strength, wear resistance, corrosion resistance, and internal stress. #### 1.1 Martensite Carbon Content Martensite formed from high-carbon chromium steel (e.g., GCr15) plays a critical role in determining the mechanical properties of the bearing. When the carbon content of quenched martensite is around 0.5% to 0.56%, it provides optimal mechanical performance, including touch fatigue life and anti-crushing ability. However, the actual carbon distribution within the martensite is uneven, with higher concentrations near carbides. This leads to the formation of cryptocrystalline martensite, which enhances strength and prevents microcracks during quenching. #### 1.2 Residual Austenite After quenching, a certain amount of residual austenite (Ar) can remain in the steel, typically ranging from 8% to 20%. While Ar has both advantages and disadvantages, an appropriate amount improves hardness and fatigue life. However, excessive Ar may reduce the overall performance if it transforms into martensite during service, leading to embrittlement. #### 1.3 Undissolved Carbides Undissolved carbides in hardened steel significantly affect bearing performance. They are hard and brittle, and when not uniformly distributed, they can cause stress concentration and crack initiation. Proper control of carbide size, shape, and distribution is crucial. Small, round, and uniformly dispersed carbides enhance wear resistance and promote the formation of fine-grained martensite, which improves mechanical properties. #### 1.4 Residual Stress Residual stresses after quenching and tempering have a significant impact on bearing life. Compressive residual stresses on the surface increase fatigue strength, while tensile stresses decrease it. Controlling the level of residual stress through proper heat treatment ensures better performance and longer service life. #### 1.5 Impurity Content Impurities such as oxides, sulfides, and non-metallic inclusions negatively affect the mechanical properties of steel. High oxygen or sulfur content can lead to reduced fatigue life and strength. Therefore, maintaining high purity in bearing steel is essential for reliable performance. ### 2. Control of Key Factors To optimize bearing life, several control measures are necessary: - **Microstructure Control**: Achieving a fine and uniform pearlite structure before quenching helps in obtaining better mechanical properties. - **Quenching Parameters**: Adjusting quenching temperature and time ensures the right balance between retained austenite, undissolved carbides, and martensite carbon content. - **Surface Treatment**: Introducing carburizing or nitriding during quenching can create compressive residual stresses on the surface, enhancing fatigue resistance. - **Purity Management**: Reducing impurities like oxygen and sulfur through advanced melting techniques (e.g., electroslag remelting) improves material quality. ### 3. Conclusion In summary, the life of high-carbon chrome steel rolling bearings is primarily influenced by the original microstructure, carbon content, residual austenite, undissolved carbides, residual stress, and impurity levels. By carefully controlling these factors, manufacturers can significantly improve the performance and durability of bearing components. **Related Bearing Knowledge** - NTN bearing advantages in application - SKF: Pre-smooth sealed linear ball bearing function - "Thrust ball bearing" device stability protection problem solution - Detailed description of rolling bearing touch seal and sliding bearing experience This article is sourced from China Bearing Network. Please cite the source if you use this information. Previous: The bearing crack appears on the bearing ring Next: Loading and unloading of cylindrical bore radial bearing

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