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Bearing steel ball bearing steel with full name, the compressive strength and the fatigue limit, high hardness, high wear resistance and toughness, good hardenability, very strict control of sulfur and phosphorus, is a kind of high quality steel, can be cold touch of steel. Proportion: 7.81
(a) forging temperature bearing steel
(1) initial forging temperature: 1150 (1120) end Satin temperature: 850 (800) of.
(2) to remove the surface defects of forging before, as far as possible after preheating in rapid heating.
(3) the temperature processing, should avoid blue brittle zone of 200~400 degree. The thermal processing, should avoid entering the high temperature brittle zone (more than 1250). Should avoid as far as possible into the hot shortness of area (800~~950 degrees). Today the focus:
(two) the heat treatment after forging
(1) -- -- pre heat treatment after forging (spheroidizing annealing) -- -- the final heat treatment (quenching and low temperature tempering)
(2) the spheroidal annealing Objective: to reduce the hardness, easy processing, preparing for the quenching.
The spheroidizing annealing process: the heat to 750~~770 degrees, heat preservation time, under slow cooling to 600 degrees below the air cooling.
(3) all kinds of bearing steel is quenched and tempered at low temperature and hardness scale
Steel quenching temperature and quenching medium low temperature tempering hardness of HRC
GCr6 800~820 water or oil 150~170 62~64
GCr9 800~830 water or oil 150~170 62~64
GCr9SiMn 810~820 water or oil 150~160 62~64
GCr15 820~846 oil 150~160 62~64
GCr15SiMn 800~840 oil 150~170 62~64
(three) in quenching and quenching medium
(1) quenching color (experience) the most hard and brittle yellow white, hard and tough, blue soft and tough.
(2) the quenching medium
A: general water temperature not exceeding 40 degrees, there is no oil, soap and other impurities.
Aqueous solution of B salt and alkali: water plus 5~10 percent of salt or alkali.
Salt solution cooling speed is ten times of water, high hardness and uniform, but the organization shall force, have a certain role in corrosion. The temperature is less than 60 degrees.
Alkali solution (caustic soda solution) to corrosion, small accommodation.
C oil: including oil, spindle oil, transformer oil, diesel oil etc.. Can reduce the deformation and cracking. Not applicable to carbon steel. Oil temperature: 60~~80 degrees in the highest degree, not more than 100~120.
(four) the tempering temperature
Bearing steel by low temperature tempering. Temperature: 150~250 degrees. But while maintaining a high hardness and wear resistance, reduce stress and brittleness, lest when using open or premature damage. The hardness of HRC:58~~64.