Forging of bearing steel

The full name of bearing steel is called rolling bearing steel, which has high compressive strength and fatigue limit, high hardness, high wear resistance and certain toughness, good hardenability, strict control of sulfur and phosphorus, and is a kind of high-quality steel. Do cold to touch the steel. Specific gravity: 7.81
(1) Bearing steel forging temperature

(1) Initial forging temperature: 1150 (1120) final satin temperature: 850 (800) degrees.

(2) Remove surface defects before forging, and heat them as soon as possible after preheating.

(3) When temperature processing, the blue-brittle area of ​​200~400 degrees should be avoided. When hot working, avoid entering high temperature brittle areas (greater than 1250). Try to avoid entering the hot and brittle zone (800~~950 degrees). {TodayHot}

(2) Post-forging heat treatment

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

(2) Spheroidizing annealing purpose: to reduce hardness, facilitate processing, and prepare for quenching.

Spheroidizing annealing process: heating to 750~~770 degrees, keeping warm for a certain period of time, and slowly cooling to 600 degrees below air cooling.

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

Steel No. Quenching temperature and quenching medium Low temperature tempering Hardness 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

(3) Quenching and quenching media

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

(2) Quenching medium

A water: the general temperature does not exceed 40 degrees, there must be no oil, soap and other impurities.

B Aqueous solution of salt and alkali: add 5~10% salt or alkali in water.

The cooling rate of the salt solution is ten times that of water, and the hardness is high and uniform, but the tissue stress is large and there is a certain rusting effect. The temperature is less than 60 degrees. {HotTag}

The alkali solution (caustic aqueous solution) has high corrosivity and a small adaptability range.

C oil: including engine oil, spindle oil, transformer oil, diesel oil, etc. It can reduce deformation and cracking. Carbon steel is not applicable. Oil temperature: 60~~80 degrees, the highest does not exceed 100~120 degrees.

(four) tempering temperature

Bearing steel is tempered at low temperature. Temperature: 150~250 degrees. It can reduce internal stress and brittleness while maintaining high hardness and high wear resistance to avoid cracking or premature failure during use. Hardness HRC: 58~~64.