The Forging and Heat Treatment Process of Bearing Steel
Bearing steel is a kind of special steel which is widely used in various mechanical fields. Bearing steel often needs to be forged or machined by heat treatment process. In this paper, the forging and heat treatment process of bearing steel is analyzed in detail.
In general, before forging bearing steel, it is necessary to make certain pre-treatments, such as normalizing or quenching, to reduce the internal stress of the material and reduce the possibility of cracks during the forging process. Then the correct forging temperature should be selected according to the quality of steel. Generally speaking, the heating temperature of finished steel is 1350-1150℃ and the heat preservation time should not be less than 30 minutes. Then put the bearing steel into the forging equipment and carry out the appropriate forging technique. The performance of the bearing steel becomes better after cold forging.
After forging, heat treatment should be done for the forged bearing steel to obtain the required microstructure. Bearing steel is usually treated by quenching and tempering process. Quenching should be done at high temperature in order to refine the crystal grains and obtain a better ferrite-martensite mixed structure. The quenching temperature should be slightly higher than the Ac1 transformation point, generally 850 - 890 ℃.
The quenching medium should be selected according to the specific performance requirements of bearing steel. Oil quenching is usually used. During quenching process, the distance between combustion chamber and furnace should be controlled properly in order to avoid oxidation of bearing steel. After quenching, tempering process should be conducted. Generally, tempering temperature is in the range of 160-200℃.
After tempering, bearing steel can be used to form some components in the later manufacturing process. During the manufacture of bearing steel components, the heat treatment process should be strictly controlled in order to avoid cracking or deformation of the bearing steel material. Thus, bearing steel components with certain performance and quality can be obtained.
In conclusion, the forging and heat treatment process of bearing steel requires a certain professional knowledge and skills. It is concluded that the heating temperature should not be too high, the quenching medium should be selected properly, the internal structure of bearing steel should be strictly controlled in order to ensure the performance and quality of the bearing steel components.
