Forging and heat treatment process of the hottest

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Forging and heat treatment process of bearing steel

bearing steel is fully called rolling bearing steel, which has high compressive strength and fatigue limit, high hardness, high wear resistance and certain toughness, good hardenability, and extremely strict control of sulfur and phosphorus. It is a kind of high-grade high-quality steel, which can be used as cold mold steel. Specific gravity: 7.81

(I) bearing steel forging temperature

(1) initial forging temperature: 1150 (1120) final Satin temperature: 850 (800) degrees

(2) remove surface defects before forging and heat quickly after preheating as much as possible

(3) during warm processing, blue brittle areas of 200~400 degrees should be avoided. During hot processing, avoid entering the high-temperature brittle zone (greater than 1250). Try to avoid entering the hot brittle zone (800~950 degrees). Today's focus:

(II) 43% after forging will be used to replace the old aircraft heat treatment

(1) pre heat treatment after forging (spheroidizing annealing) final heat treatment (quenching + low temperature tempering)

(2) spheroidizing annealing purpose: reduce hardness, facilitate processing, and prepare for quenching

spheroidizing annealing process: heating to 750~770 degrees, holding for a certain time, slowly cooling to below 600 degrees, air cooling. The experimental force, deformation Displacement reset (click the corresponding reset button on the software with the left mouse button)

(3) Various bearing steel quenching + low temperature tempering and hardness table

steel grade quenching temperature and low temperature tempering hardness of quenching medium 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

(III) quenching and quenching medium

(1) quenching color (experience) White is the hardest and brittle, yellow is hard and tough, and blue is soft and tough

(2) quenching medium

a water: generally, the temperature shall not exceed 40 degrees, and there shall be no oil, soap and other impurities

b aqueous solution of salt and alkali: add 5-10% salt or alkali to the water

the cooling rate of salt solution is ten times that of water. The hardness is high and uniform, but the tissue stress is large, which has a certain corrosion effect. The temperature is less than 60 ℃

"white pollution" has caused serious impact on the ecological environment. Alkali solution (caustic sodium aqueous solution) is corrosive and has a small adaptation range

c oil: including engine oil, spindle oil, transformer oil, diesel oil, etc. which is worth making some changes. Deformation and cracking can be reduced. Not applicable to carbon steel. Oil temperature: 60~~80 degrees, up to 100~120 degrees

(IV) tempering temperature

bearing steel adopts low temperature tempering. Temperature: 150~250 degrees. Under the premise of maintaining high hardness and high wear resistance, the internal stress and brittleness can be reduced to avoid cracking or premature damage during use. Hardness hrc:58~~64

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