Bearing steel tube refers to hot-rolled or cold-rolled (cold-drawn) seamless steel tubes, which are used to manufacture common rolling bearing rings. The steel pipe has an outer diameter of 25- 180mm and a wall thickness of 3.5-20mm, which can be divided into ordinary precision and high precision. Bearing steel is used to manufacture balls, rollers and bearing rings. Bearing bears great pressure and friction in work, so bearing steel is required to have high and uniform hardness, wear resistance and high elastic limit. Bearing steel has strict requirements on the uniformity of chemical composition, the content and distribution of nonmetallic inclusions and the distribution of carbides, and is one of the most stringent steel grades in all steel production.

The smelting quality of bearing steel is very high, so it is necessary to strictly control the contents of sulfur, phosphorus and hydrogen, and the number, size and distribution of nonmetallic inclusions and carbides, because the number, size and distribution of nonmetallic inclusions and carbides have great influence on the service life of bearing steel, and the failure of bearings is often caused by the expansion of microcracks around large inclusions or carbides. The content of inclusions is closely related to the oxygen content in steel. The higher the oxygen content, the more inclusions and the shorter the service life. The larger the particle size and uneven distribution of inclusions and carbides, the shorter the service life, and their size and distribution are closely related to smelting process and quality. At present, the main processes for producing bearing steel are continuous casting and electric furnace smelting+electroslag remelting, and a few processes such as vacuum induction+vacuum self-consumption or+multiple vacuum self-consumption are used to improve the quality of bearing steel.