Bearing steel is hot-rolled or cold-rolled (cold drawn) of seamless steel tubes for the manufacture of bearing rings with the general. Pipe diameter 25-180 mm, wall thickness of 3.5-20 mm, sub-normal accuracy and high precision two. Ball bearing steel is used to manufacture, steel rollers and bearing rings. Bearing in work is under great pressure and friction with, so they requested bearing steel with a high and uniform hardness and wear resistance, and high elastic limit. The chemical composition of bearing steel uniformity, non-metallic inclusions content and distribution, carbide distribution and other requirements are very strict, all steel production in the most demanding steel one.
The physical properties of bearing steel mainly to check the microstructure, decarburization, non-metallic inclusions, mainly low magnification. Under normal circumstances are hot-rolled annealed, cold-drawn annealed delivery. Delivery status should be indicated in the contract. The macrostructure of steel must be free of shrinkage, skin bubbles, white spots and micro-pores. Center porosity, generally loose no more than 1.5, not more than two segregation. Steel annealing should be uniformly distributed fine granular pearlite. Decarburization depth, non-metallic inclusions and carbides uniformity shall conform to the relevant national standards.
Package delivery to a diameter less than 20mm, 20mm more than the delivery can be bare. Of cold drawn steel should be coated anti-rust oil. Quality of goods before delivery guarantee should be attached, indicate the steel, heat number, weight, size, chemical composition, test and test results.
Production of bearing steel bearings for steel are the following (marked with that "roll" of G): chrome bearing steel such as GCr6, GCr9 (SiMn), GCrl5 (SiMn); chrome bearing steel such as GSiMnV (Re), GSiMnMoV (Re), GMnMoV (Re); carburizing bearing steel such as G20CrMo, G20Cr2Mn2Mo; high carbon chrome bearing steel such as stainless 9Cr18 (Mo) and so on.
Bearing steel smelting high quality requirements, the need for strict control of sulfur, phosphorus, hydrogen content and non-metallic inclusions and carbide quantity, size and distribution, as non-metallic inclusions and carbide quantity, size and distribution of impact on the life of a great bearing steel, bearing failure is often in large inclusions or carbide produced around the micro-crack formed. Inclusion of content and oxygen content in steel is closely related to the higher oxygen content, the more the number of inclusions, the shorter life expectancy. The greater the size of inclusions and carbides, the more uneven the distribution, life is also shorter, and their size, distribution and use of smelting and refining process is closely related to the quality, now the main production of bearing steel and continuous casting process is EAF + ESR smelting process, there is a small vacuum induction + vacuum consumable double vacuum or + repeatedly vacuum consumable and other technology to improve the quality of bearing steel.
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