The bearing steel forging and heat treatment process

Bearing steel full name is rolling bearing steel, high compressive strength and the fatigue limit, high hardness, high wear resistance and certain tenacity, good hardenability, control of sulfur and phosphorus is extremely strict, is a kind of high quality steel, can do touch with cold steel. Weight: 7. 81 ( A) Bearing steel forging temperature ( 1) Initial forging temperature: 1150 ( 1120). Satin temperature: 850 ( 800). Degrees. ( 2) Remove surface defects before forging, as far as possible after preheating in rapid heating. ( 3) Temperature processing, should avoid to 200 ~ 400 degrees of blue brittle zone. Hot working, should avoid to enter the high temperature brittle area ( More than 1250) 。 Should avoid as far as possible into the heat brittle zone ( 800 ~ ~ 950 degrees) 。 Today, the focus of: 2) Heat treatment after forging ( 1) After forging - — — — Heat treatment (in advance Spheroidizing annealing) — — — — The final heat treatment ( Quenching and low temperature tempering) ( 2) Spheroidizing annealing purpose: to reduce the hardness, easy to machining, preparing for quenching. The spheroidizing annealing process: heating to 750 ~ 770 degrees, heat preservation time, air cooling below the slowly cooled to 600 degrees. ( 3) All kinds of bearing steel quenching + tempering at low temperature and hardness scale steel grade quenching temperature and quenching medium low temperature tempering hardness HRCGCr6800 ~ 820 water or oil 150 ~ 17062 ~ 64 gcr9800 ~ 830 water or oil 150 ~ 17062 ~ 64 gcr9simn810 ~ 820 the water or oil 150 ~ 16062 ~ 64 gcr15820 ~ 846 oil 150 ~ 16062 ~ 64 gcr15simn800 ~ 840 ~ 64 (150 ~ 17062 3) Quenching and quenching medium ( 1) Quenching color ( Experience) White is the most hard and brittle, yellow hard and tough, blue soft and tough. ( 2) A water quenching medium: general temperature not to exceed 40 degrees, can not have oil, soap and other impurities. B of salt and alkali aqueous solution: add 10 ~ five percent salt water or alkali. Salt solution cooling rate is ten times of water, high hardness and uniformity, but the organization stress is big, has certain corrosion effect. Temperature is less than 60 degrees. Alkali solution, Caustic soda solution) Corrosive, adapt to the small scope. C: oil including engine oil, spindle oil, transformer oil, diesel oil, etc. Can reduce the deformation and cracking. Does not apply to carbon steel. Oil temperature: in 60 ~ 80 degrees, is highest do not exceed 100 ~ 120 degrees. ( 4) Using low temperature tempering tempering temperature bearing steel. Temperature: 150 ~ 250 degrees. Can be kept under the premise of high hardness and high wear resistance, reduce internal stress and brittleness, lest when using split or premature failure. Hardness HRC: 58 ~ ~ 64.