The full name of bearing steel is rolling bearing steel, which has high compressive strength and fatigue limit, high hardness, high wear resistance and certain toughness, good hardenability, and strict control of sulfur and phosphorus. It is a high-grade high-quality steel that can be used as a cold working tool steel, with a specific gravity of 7.81.

1. Forging temperature of bearing steel

(1) Initial forging temperature: 1150~1120 ℃, final satin temperature: 850~800 ℃.

(2) Before forging, remove surface defects and preheat as much as possible before rapid heating.

(3) During warm processing, the blue brittle zone of 200-400 ℃ should be avoided. During hot processing, it is necessary to avoid entering the high-temperature brittle zone (greater than 1250 ℃). Try to avoid entering the hot brittle zone (800~950 ℃) as much as possible.

2. Post forging heat treatment

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

(2) The purpose of spheroidizing annealing is to reduce hardness, facilitate processing, and prepare for quenching.

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

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

3. 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 should not exceed 40 degrees Celsius and there should be no impurities such as oil and soap.

B salt and alkali aqueous solution: Add 5-10% salt or alkali to water.

The cooling speed of the salt solution is ten times that of water, with high and uniform hardness, but high organizational stress, which has a certain degree of corrosion effect. The temperature is less than 60 degrees.

Alkali solution (caustic sodium water solution) has high corrosiveness and a small applicability.

C oil: including engine oil, spindle oil, transformer oil, diesel, etc. It can reduce deformation and cracking. Not suitable for carbon steel. Oil temperature: between 60 to 80 degrees Celsius, with a maximum of 100 to 120 degrees Celsius.

4. Tempering temperature

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