Bearing steel composition
Bearing steel, as one of the most stringent steel grades in all steel production, has a carbon content of about 1% ωc and a chromium content of 0.5-1.65% ωcr. According to international standards, 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 anti-magnetic bearing steel. Among them, the production of high-carbon chromium bearing steel GCr15 has accounted for more than 80% of the total production of bearing steel in the world. The high-carbon chromium bearing steel GCr15 is the world's largest production of bearing steel, with carbon Wc of about 1% and chromium Wcr of about 1.5%. Since its birth in 1901, more than 100 years ago, the main composition of high-carbon chromium bearing steel GCr15 has basically not changed. So that if there is no special description of bearing steel, it refers to GCr15.
Bearing steel quality
Bearing steel material is high purity iron carbon alloy steel! Because bearing steel is mainly used to manufacture rolling bearings and rings. Since the bearing should have the characteristics of long life, high precision, low caloric value, high speed, high rigidity, low noise, high wear resistance, the bearing steel is required to 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 bearing steel chemical composition uniformity, non-metallic inclusion content and type, carbide particle size and distribution, decarbonization and other requirements are strict. Bearing steel is generally developing in the direction of high quality, high performance and multiple varieties. Bearing steel according to the characteristics and application environment is divided into: high-carbon chromium bearing steel, carburized bearing steel, high temperature bearing steel, stainless bearing steel and special bearing materials.
Bearing steel hardness
In order to ensure the hardness of bearing steel, the blue brittleness zone of 200 to 400 degrees should be avoided when temperature processing is carried out. During hot processing, avoid entering the high-temperature and brittle zone (greater than 1250). Try to avoid entering the hot and brittle zone (800~ 950 degrees). Annealing purpose: to reduce the hardness, easy to process, to prepare for quenching. Spheroidizing annealing process: heating to 750~ 770 degrees, holding heat for a certain time, slowly cooling to 600 degrees below air cooling. (3) All kinds of bearing steel quenching + low temperature tempering and hardness meter steel number quenching temperature and quenching medium low temperature tempering hardness HRCGCr6800~820 Water or oil 150~17062~64GCr9800~830 water or oil 150~17062~64GCr9SiMn810~820 Water oil 150~16062~64 GCr15820~846 oil 150~16062~64GCr15SiMn800~840 oil 150~17062~64.
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