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How To Make China's High-end Bearing Steel?
- Aug 16, 2018 -

On a dog's day in Jiangyin City and along the Yangtze River, the bearing steel is shipped from the wharf, first to the port of Shanghai, and then to Europe by sea. They are usually unloaded from the ports of Venice or Las Pezia, Italy, and then tossed to the bearings processing plants in France; and sometimes to Port Antwerp, Belgium, and then to the bearings manufacturer in Germany. At present, the world's top bearing manufacturers are using China's special steel enterprise - CITIC Taifute Steel Group's Jiangyin Xingcheng special steel bearing steel production.
Bearing steel is a steel used to make balls, rollers and bearing rings. It is called "the king of steel". It is used to manufacture the most core parts of machinery and equipment. Its service conditions are bad. Besides enduring long-term high-speed operation and various extrusion stresses, it also has to resist friction and ultra-high temperature. This requires the bearing steel to have high and uniform hardness and wear resistance, and high elastic limit. Good bearings can not be separated from good bearing steel, bearing manufacturing and bearing steel production capacity and quality, a direct impact on a country's manufacturing and industrial development level.
China has become a major producer of bearing steel. According to the statistics of 36 enterprises of the Special Steel Association, in 2017, the crude steel output of bearing steel in China's main special steel enterprises was 3.0146 million tons. Xingcheng Special Steel, Xinye Special Steel and Benxi Special Steel ranked the top three in the production of bearing steel, accounting for 51% of the total domestic production of bearing steel. Xu Xiaohong, chief engineer of Xingcheng Special Steel, told Sci-Tech Daily that China has not only made high-end bearing steel, but also made a name for itself in the international market. "Last year we produced 965,000 tons of bearing steel, 630,000 tons are supplied to Sweden SKF, Germany SCHAEFFLER, Japan NSK, NTN and other world-renowned bearing enterprises." He said that the bearing steel of Xingcheng Special Steel has been ranked first in world bearing steel production and sales for 8 consecutive years.
Good quality control "N Dao Guan"
Bearing steel is one of the most demanding steels in steel production. "The uniformity of chemical composition, the content and distribution of non-metallic inclusions, the distribution of carbides and other requirements are very high." Huang Zhen, Research Institute of Xingcheng Special Steel, introduced that the key indexes to evaluate the quality of bearing steel are the purity and uniformity of materials, which affect the fatigue life of bearings, and the uniformity affects the deformation and microstructure uniformity of bearings after heat treatment.
The lower the oxygen content, the fewer oxide inclusions, the higher the purity, the longer the fatigue life of bearing steel, so the oxygen content in steel should be reduced; harmful elements in steel form multi-edged inclusions, easy to cause local stress concentration, resulting in fatigue cracks, so the inclusions produced by harmful elements should be strictly controlled. At present, the oxygen content of Xingcheng bearing steel is controlled at the world advanced level of less than 5 ppm, and the core technology of internal quality control is mastered. "Quality is produced by process control, not checked and selected." Xingcheng Special Steel has always maintained this idea, and has done enough work in the production process control.
In casting process, Xingcheng uses a unique tundish induction heating system. "The molten steel in the tundish is poured at low temperature with little fluctuation, thus greatly avoiding the uneven distribution of the elements in the steel during crystallization. We have mastered the core technology of this kind of bearing steel casting. Huang Zhen said.
At the rolling stage, the surface of the billet can be cleaned by flame cleaning, just like a cucumber. This core technology to remove defects and ensure the surface quality of steel is also in the grasp of Xingcheng.