Introduction of bearing steel
Bearing steel is the steel used to make balls, rollers, and bearing rings. Bearing steel has high and uniform hardness and wear resistance, as well as high elastic limit. 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 it is one of the most stringent steel grades in all steel production.
In 1976, the International Organization for Standardization ISO included some general bearing steel grades into international standards, and divided bearing steel into four categories: fully hardened bearing steel, surface hardened bearing steel, stainless bearing steel, and high temperature bearing steel. A total of 17 Steel No.
Bearing steel is high-purity iron-carbon alloy steel
Bearing steel is mainly used to manufacture rolling elements and rings of rolling bearings. Since the bearing should have the characteristics of long life, high precision, low calorific value, high speed, high rigidity, low noise and high wear resistance, it is required that the bearing steel should have: high hardness, uniform hardness, high elastic limit, high contact fatigue Strength, necessary toughness, certain hardenability, corrosion resistance in atmospheric lubricants. In order to achieve the above performance requirements, the chemical composition uniformity, content and type of non-gold inclusions, carbide particle size and distribution, and decarburization of bearing steel are strictly required. Bearing steel generally develops in the direction of high quality, high performance and variety. Bearing steel is divided into: high carbon chromium bearing steel, carburized bearing steel, high temperature bearing steel, stainless bearing steel and special bearing materials according to the characteristics and application environment.
Through research, people have mastered that in order to improve the performance of bearing steel and meet the above requirements, it is necessary to smelt very high purity iron-carbon alloy steel (oxygen-free), and then participate in a certain amount of carbon, chromium, silicon, manganese, vanadium, etc. Alloy, and make corresponding heat treatment, you can get the bearing steel that meets the requirements. Bearing steel in my country can be roughly divided into four categories, and their grades are listed as follows:
1. High carbon chromium bearing steel, grades: 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
Chromium-free bearing steel, grades: GSiMnV; GSMVRE; GSiMnMoV, can replace chromium-containing bearing steel.
What is the hardness of bearing steel
The hardness of bearing steel after heat treatment is generally between 30 and 50.
Bearing steel structure
Bearing steel, also known as high carbon chromium steel, has a carbon content wc of about 1% and a chromium content wcr of 0.5%-1.65%. Bearing steel is 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 antimagnetic bearing steel.
High-carbon chromium bearing steel GCr15 is the bearing steel with the largest production volume in the world. The carbon content Wc is about 1%, and the chromium content Wcr is about 1.5%. Since its birth in 1901, the main components have basically remained unchanged for more than 100 years. With the advancement of science and technology, research work continues, and product quality continues to improve, accounting for more than 80% of the world's total production of bearing steel. So that if there is no special description for bearing steel, it refers to GCr15.
my country has produced high carbon chromium stainless bearing steel, the main steel grade is 9Cr18; carburized bearing steel, the main steel grade is G20CrMo; chromium bearing steel, the main steel grade is GCr15.
Physical properties of bearing steel
The physical properties of bearing steel are mainly based on the inspection of microstructure, decarburized layer, non-metallic inclusions, and low magnification structure. - Under normal circumstances, they are delivered by hot-rolled annealing and cold-drawn annealing. The delivery status should be stated in the contract. The low-magnification structure of the steel must be free of shrinkage cavities, subcutaneous bubbles, and microscopic pores. Central looseness and general looseness shall not exceed grade 1.5, and segregation shall not exceed grade 2. The annealed structure of the steel should be uniformly distributed fine-grained pearlite. The depth of the decarburized layer, the non-metallic inclusions and the unevenness of carbides shall comply with the relevant national standards.
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