Heat Treatment Process
Raw materials of bearings: bearing steel:
Bearing steel refers to steel used to make balls, rollers, and bearing rings (inner and outer rings). Bearing steel has high and uniform hardness and wear resistance, as well as high elastic limit. The uniformity of the chemical composition of bearing steel, the content and distribution of non-metallic inclusions, and the distribution of carbides are very strict. It is one of the most stringent steel types in all steel production. Bearing steel is divided into six categories: high carbon rubbing bearing steel, non-rubbing bearing steel, carburized bearing steel, stainless bearing steel, medium and high temperature bearing steel, and anti-magnetic bearing steel.
The significance of bearing heat treatment:
The purpose of heat treatment of bearings is to change the microstructure and properties of steel so that it has better mechanical properties, physical properties, chemical properties and other characteristics. Specifically, the purpose of heat treatment of bearing steel after it is made into bearing accessories mainly includes the following aspects:
1. Improve the hardness of bearings
During the use of rolling bearings, they need to withstand extremely high axial loads and radial loads, so the hardness of steel are required to be high. Because the bearing material is quenched or tempered at high temperature during heat treatment, the grain size of the material is refined, the primary ecology disappears, and the lattice changes, thereby achieving the purpose of strengthening the material. Generally, the hardness of the bearing after quenching treatment is more than 20% higher than that of the untreated one.
2.Enhance the strength of the bearing
The bearing needs to withstand various impacts, vibrations and loads during use. The strength of the bearing after heat treatment is significantly improved. Compared with untreated bearings, heat-treated bearings have higher tensile strength and impact toughness, are not easy to deform or damage during use, and have stronger durability.
3. Improve the wear resistance of the bearing
The wear resistance of the bearing is one of its key properties. Heat treatment can improve the wear resistance of the bearing, reduce the wear rate, better maintain the shape and size during friction, and reduce wear and fatigue. Therefore, the bearing life after heat treatment is longer and the service life is more stable.
4. Enhance corrosion resistance
During use, the bearing will be corroded and oxidized due to factors such as lubricating oil and environment, which greatly shortens the life of the bearing. After heat treatment, the oxides and other harmful compounds on the surface of the bearing are eliminated, and the corrosion resistance of the bearing is improved. At the same time, some defects and cracks on the bearing surface have also been improved, with higher surface finish and density.
Heat treatment steps:
The heating temperature of normalizing is 860-880℃, the holding time is 150-180 minutes, and the cooling method is air cooling;
The heating temperature of quenching is 820-840℃, the holding time is 90-120 minutes, and the cooling method is water cooling;
The heating temperature of tempering is 560-590℃, the holding time is 120-150 minutes, and the cooling method is air cooling.
Strict control of these process parameters is the key to ensuring the effect of heat treatment
In summary, heat treatment is crucial for bearings. Through appropriate heat treatment processes, the mechanical properties of bearings such as hardness, strength, and toughness can be improved, their wear resistance, fatigue resistance, and corrosion resistance can be improved, the service life of bearings can be extended, and their stable and reliable operation under various complex working conditions can be ensured. At the same time, heat treatment can also optimize the organizational structure of the bearing, giving it better dimensional stability and thermal stability, providing strong guarantees for the efficient operation of mechanical equipment.
