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How does China overcome high end bearing steel problem -Chapter 1
2016-01-14
Bearings seem inconspicuous but ubiquitous.it is an important measure of a country's technological and industrial strength, and is regarded as the "joint of high-end equipment." Like many fields, China has long been the world's largest production and sales base in the field of low-end bearings, but it was not until recently that high-end bearings finally made a breakthrough.
In order to create high-end bearings that work in extreme environments, the problem of bearing steel must be solved at first.High-end equipment such as high-speed railways and large airplanes all have high-end bearings. To meet the requirements of high-end bearings in terms of accuracy, performance, life and reliability, the high quality and reliability of bearing materials are decisive factor.
The quality of bearing steel mainly depends on the following four factors: one is the content, shape, distribution and size of the inclusions in the steel; the second is the content, shape, distribution and size of the carbides in the steel; the third is the center porosity in the steel hole and center segregation; fourth is the consistency of bearing steel product performance. These four factors can be summarized as indicators of purity and uniformity.
Among them, the purity requires fewer inclusions the better, as this has a direct impact on the fatigue life of the bearing; and the uniformity requires the inclusion and carbide particles in the material to be fine and dispersed, which will affect the bearing deformation and uniformity of structure after heat treatment in manufacturing.
To improve the purity of bearing steel, the first thing to do is to control the oxygen content in the steel. In steel production, ppm is used as the unit of oxygen content. Generally speaking, 8 ppm means good Steel, and what high-end bearings need is 5 ppm top steel. In addition, harmful elements such as titanium stay in the steel can easily form multi-angular inclusions, which will cause local stress concentration and fatigue cracks, which should be avoided as much as possible.
