Bearing steels are steels used to manufacture balls, rollers and bearing rings. Bearing steels have a high and uniform hardness and wear resistance, as well as high elastic limits. The requirements for the uniformity of the chemical composition of bearing steel, the content and distribution of non-metallic inclusions, and the distribution of carbides are very strict, and are among the most demanding steels in all steel production. 1976 International Organization for Standardization ISO incorporated some common bearing steel numbers into international standards, and divided bearing steel into: full hardening bearing steel, surface hardening bearing steel, stainless bearing steel, high temperature bearing steel, etc. A total of 17 steel grades in four categories.
Bearing steel is a high purity iron-carbon alloy steel!
Bearing steel is mainly used in the manufacture of rolling bearing rolling bodies and rings. As bearings should have long life, high precision, low heat generation, high speed, high rigidity, low noise, high wear resistance and other characteristics, so the bearing steel should have: high hardness, uniform hardness, high elastic limit, high contact fatigue strength, must toughness, certain hardenability, corrosion resistance in the atmosphere of the lubricant. In order to achieve the above performance requirements, the chemical composition of bearing steel uniformity, non-metallic inclusions content and type, carbide particle size and distribution, decarburisation and other strict requirements. Bearing steels are generally developed in the direction of high quality, high performance and multi-species. Steel for bearings is divided into: high-carbon chromium bearing steel, carburized bearing steel, high-temperature bearing steel, stainless bearing steel and special bearing materials according to characteristics and application environment.
Bearing steel is mainly used to manufacture bearings and their main components, such as bearing balls, rollers and bearing rings of steel. Due to the ever-changing working conditions of bearings, especially the rapid development of science and technology, resulting in more and more complex working environment of machinery, such as shaft rotation speed is getting faster and faster, bearing heavier and heavier load, working temperature is getting higher and higher, bearing force environment is getting more and more complex (in addition to gravity, there are multi-directional thrust) where such, require bearings are competent, support shaft according to the requirements of stable operation. Therefore bearing steel must be in the strength, stiffness, wear resistance, hardness, physical and mechanical properties of uniformity, contact fatigue strength function and so on can keep up with the development of the times and technology, and constantly improve.
Through research, people have mastered, to improve the performance of bearing steel, to meet all the above requirements, must smelt a very high purity of iron-carbon alloy steel (oxygen-free), and then participate in a certain amount of carbon, chromium, silicon, manganese, vanadium and other alloys, and for the corresponding heat treatment, you can get the bearing steel to meet the requirements. China’s bearing steel can be broadly divided into four categories, and their grades are listed below.
1, high-carbon chromium bearing steel, grade: GCr6; GCr9; GCr95siMn
2, carburized chromium bearing steel, grades: G20CrMo; G20CrNiMo; G20CrNi2Mo.
3, high-carbon chromium stainless steel bearing steel, grades: Cr4Mo4F; 9Cr18Mo.
4、High temperature bearing steel, grade: Cr14Mo; 16Cr14Mo
Bearing steel without chromium, grades: GSiMnV; GSMVRE; GSiMnMoV, can replace bearing steel containing chromium.
The hardness of bearing steel after heat treatment is generally between 30 and 50.
Bearing steel, also known as high-carbon chromium steel, has a carbon content of ωc of around 1% and a chromium content of ωcr of 0.5%-1.65%. Bearing steel is also divided into six categories: high-carbon chromium bearing steel, chromium-free bearing steel, carburized bearing steel, stainless bearing steel, medium and high temperature bearing steel and anti-magnetic bearing steel.
High-carbon chromium bearing steel GCr15 is the world’s largest production of bearing steel, containing carbon Wc for about 1%, chromium Wcr for about 1.5%, from 1901 to the birth of more than 100 years, the main components have not changed, with the progress of science and technology, research work any continue, product quality continues to improve, accounting for more than 80% of the world’s total production of bearing steel. So much so that bearing steel, if there is no special instructions, that means GCr15.
China has produced high-carbon chromium stainless bearing steel, the main steel number 9Cr18; carburized bearing steel, the main steel number G20CrMo; chromium bearing steel, the main steel number GCr15.
The physical properties of bearing steel are mainly based on checking the microstructure, decarburisation layer, non-metallic inclusions and low times of organisation. In general they are delivered hot rolled and annealed, cold drawn and annealed. The delivery condition should be specified in the contract. The low-frequency organisation of the steel must be free of shrinkage, subcutaneous bubbles, white spots and microscopic porosity. The central laxity and general laxity shall not exceed 1.5 levels and the segregation shall not exceed 2 levels. The annealed organisation of the steel shall be a uniformly distributed fine-grained pearlite. The depth of the decarburised layer, non-metallic inclusions and carbide inhomogeneity shall conform to the provisions of the relevant national standards accordingly.
Classification: There are 5 main categories of bearing steel used in the world at present, namely high-carbon chromium bearing steel, carburized bearing steel, stainless bearing steel, high-temperature bearing steel and medium-carbon bearing steel.
(1) 50 tons and above UHP electric furnace smelting → 60 tons and above LF furnace refining → 60 tons and above VD furnace vacuum treatment → alloy steel billet or rectangular billet continuous casting (260mm×300mm, 180mm×220mm) → slow cooling or hot feeding → rolling → finishing → inspection into storage.
(2) 90 tons and above converter smelting → 100 tons and above LF furnace refining → 100 tons and above RH furnace vacuum treatment → alloy steel billet or rectangular billet continuous casting → (e.g. 320mm×340mm, 240mm×240mm) slow cooling or hot feeding → rolling → finishing → inspection into storage.
单击 “编辑” 按钮更改此文本。这是测试文本。Bearing steel is used to manufacture rolling bearing balls, columns and sleeves, etc. It can also be used to make precision gauges, cold punching dies, machine tool screws, such as punching dies, gauges, taps and precision couplings for diesel engine oil pumps. Bearing steel is the steel used to make balls, rollers and bearing rings.
The production of bearing steel mainly implements GB/T18254-2002 standard and the quality agreement of GCr15JD of Laigang, which is adapted to the requirements of users of precision forging bearings. All of them are stricter than GB/T18254-2002 standard.
Bearings are subjected to great pressure and friction during operation, so bearing steel is required to have high and uniform hardness and wear resistance, as well as high elastic limit. In 1976, the International Organization for Standardization (ISO) incorporated some common bearing steels into the international standard and divided the bearing steels into: full hardening bearing steels, surface hardening bearing steels, stainless bearing steels, high temperature bearing steels and so on. Four categories of a total of 17 steel numbers.
Some countries add a category for special purposes of bearing steel or alloy. China has been included in the standard bearing steel classification method and ISO similar, respectively, corresponding to high-carbon chromium bearing steel, carburized bearing steel, stainless corrosion-resistant bearing steel, high temperature bearing steel four categories.