Common Defects in Heat Treatment of Bearing Parts
Heat treatment of bearing parts is a relatively complex and difficult process. As an important part in bearing production and processing, and an important part of most parts performance, heat treatment of bearing parts must be a quality that is closely watched. Heat treatment has an important impact on bearing parts, and the heat treatment conditions must be strictly controlled in order to ensure the stability of bearing performance.
In the process of heat treatment of bearing parts, although professional engineers do their best to ensure the quality of heat treatment, it is still difficult to prevent some common defects, so those common defects should be paid more attention.
Generally speaking, there are several most common defects for heat treatment of bearing parts, such as quenching cracks, hardening cracks, over-hardening and tempering cracks.
Quenching cracks refer to the cracks on the surface or inside of the parts generated during the high temperature quenching of bearing parts, due to uneven tendency of bearing parts’ surface, heat source, and stress. Quenching cracks can easily cause bearing breakage and affect the stability of bearing parts performance and increase of the bearing failure rate.
Hardening cracks refer to the cracks on the surface or inside of the parts generated during the cryogenic treatment or metallurgical structure transformation of bearing parts. This defect can be caused by the high temperature during the quenching of bearing parts, or due to inappropriate temperature control and heating environment.
Over-hardening will cause a great harm to the hardness and strength of bearing materials, and easy leads to embrittlement or cracking. Therefore, in the quenching of bearing parts, it is necessary to ensure the correct quenching temperature, quenching speed and quenching environment, so that it can ensure the suitable hardness, strength and ductility of bearing parts.
Tempering cracks refer to the cracks generated due to the improper tempering temperature and time of bearing parts. Compared to the other two cracks, tempering cracks are easier to be found in Visual examination, which applies to both surface and internal bearing parts, leaving corresponding cracks on parts surface.
In the heat treatment of bearing parts, professional technicians should do their best to prevent those common defects, which cannot be completely avoided.
In order to prevent the occurrence of common defects, heat treatment process is needed to be strictly controlled. The heat source should be stable and appropriately adjusted, avoid producing too great temperature difference when dealing with bear parts. High temperature or cryogenic treatment should be taken seriously, better choose quenching mediums with suitable activity to bear parts, and ensure correct value of heating temperature.
In addition, metallographic structure of bearing parts should also be checked after heat treatment. Besides, after quenching, tempering should also be done correctly, choose suitable tempering temperature and time to ensure the suitable hardness, strength and ductility of the bearing parts.
In conclusion, while doing heat treatment to bearing parts, professional technicians should do their best to prevent those common defects, and strive for an optimal heat treatment process to bear parts.
