The steel used for bearings is called bearing steel. As a bearing powerhouse, bearing steel is essential.
Bearing steel is also known as high-carbon chromium steel, with a carbon content of about 1% Wc and a chromium content of 0.5% – 1.65% Wcr. Bearing steel is also divided into six categories: high-carbon chromium bearing steel, chromium-free bearing steel, carburised bearing steel, stainless bearing steel, medium and high temperature bearing steel and anti-magnetic bearing steel.
Bearing steel is used to manufacture balls, rollers and bearing rings. Bearing steel has a high and uniform hardness and wear resistance, as well as a high elastic limit. In 1976, the 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.
In order to meet the above requirements for the performance of dynamic bearings, bearing steel materials put forward some basic performance requirements as follows.
1, high contact fatigue strength, the
2, after heat treatment should have a high hardness or can meet the bearing performance requirements of hardness.
3, high wear resistance, low friction coefficient.
4、High elastic limit
5、Good impact toughness and fracture toughness
6、Good dimensional stability
7、Good rust resistance
8、Good cold and hot working properties.
Inclusion content and steel oxygen content is closely related, the higher the oxygen content, the higher the number of inclusions, the shorter the life.
Inclusions and carbide particle size, the larger the distribution of the more uneven, the shorter the service life, and their size, distribution and the use of the smelting process and smelting quality is closely related to the production of bearing steel is the main process of continuous casting and electric furnace smelting + electroslag remelting process smelting, there are a small number of vacuum induction + vacuum self-consumption of double vacuum or + multiple vacuum self-consumption and other processes to improve the quality of bearing steel.
Bearing steel smelting quality requirements are very high, need to strictly control the content of sulphur, phosphorus, hydrogen and other non-metallic inclusions and carbide number, size and distribution, because the number of non-metallic inclusions and carbide, size and distribution of the bearing steel life is very influential, often bearing failure is in the large inclusions or carbide around the micro-crack expansion and become.
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.