Reasons influencing the fatigue life of steel ball of linear bearing
author: Changzhou Feige Steel Ball Co., Ltd
2024-02-29
The comprehensive symbol of the internal quality of the linear bearing steel ball is the fatigue life. Some scholars have proposed that reducing oxygen content does not significantly increase the fatigue life of linear bearing steel balls. The reason for reducing oxygen content cannot increase the fatigue life of linear bearing steel balls is that after the number of oxides mixed, excessive sulfide becomes a unfavorable factor affecting the fatigue life of steel fatigue. Only at the same time reduce the content of oxides and sulfides can the potential of excavating materials be sufficient, and the fatigue life of linear bearing steel balls is greatly increased.
The reason for affecting the fatigue life of linear bearing steel ball can be roughly divided into the following points:
1. Nitride
As the nitrogen content in steel increases, the volume score of nitride is reduced, which is due to the decrease in the average size of the debris in the steel. Due to technical reasons, a large number of small -volume miscellaneous particles are not included. The presence of these micro -nitride particles directly affects the fatigue life of linear bearing steel balls. TI is one of the strong elements of nitride. Its proportion is small and easy to float. Some titanium will remain in the steel to form a multi -angled debris. This kind of miscellaneous objects can easily cause local stress concentration and fatigue cracks, and should control the production of this miscellaneous object.
2. oxide
The oxygen content in steel is an important factor affecting the performance of the material. The lower the oxygen content, the higher the purity, and the longer the corresponding rated life. The oxygen content in steel is closely related to oxides. In the process of steel solidification, oxides dissolved in aluminum, calcium, silicon and other elements. The content of oxide mixed is the function of oxygen. With the decrease in oxygen content, the oxide miscellaneous material is reduced; the nitrogen content and oxygen content are the same, and it has a functional relationship with nitride. However, because the distribution of oxides in steel is relatively decentralized, it plays the same role as carbides, so it will not damage the fatigue life of steel.
The existence of oxides destroys the continuity of the metal matrix. Because the expansion coefficient of oxides is less than the expansion coefficient of the straight -line bearing steel ball matrix, it is easy to produce stress concentration when being transformed and stress, becoming the birthplace of metal fatigue. Most stress concentrated between oxides, point defects and matrix. When the stress is large enough, the crack will appear and quickly expand and be destroyed. The lower the plasticity, the sharp the shape of the mixed object, the greater the stress concentration.
3. sulfide
Almost all sulfur in the steel exists in the form of sulfides. When the sulfur content in the steel increases, the sulfide in the steel also increases accordingly. However, because sulfides can surround oxides well, the impact of oxides on fatigue life is reduced. Therefore, the impact of the number of mixed objects on fatigue life is not certain, but is related to the nature, size, and distribution of mixed objects. The more miscellaneous things, the lower the fatigue life. Other influencing factors require comprehensive consideration. In linear bearing balls, sulfides are mixed in oxides mixed with small shapes, and it is difficult to identify even with gold phase methods.
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