Process and function of precision bearing cold treatment

Gsnk Bearing is committed to producing high level precision bearing for the market. Let's talk about the process and function of precision bearing cold treatment.

Cold treatment process

Stay at room temperature after quenching: after quenching, the inside and outside of the ring must be evenly cooled to room temperature before cold treatment, otherwise it is easy to crack, cold treatment immediately after cold to room temperature (generally not more than 30min, otherwise it will stop the transformation of austenite to martensite.

Cold treatment temperature: the temperature of cold treatment is mainly based on the end temperature of steel martensitic transformation Mf. In addition, the influence of cold treatment on mechanical properties and technology and other factors should be considered.

For GCr15 steel, cold treatment of -70; When the precision requirements are not very high, the cold treatment temperature can be selected as -40-70; Ultra-precision bearings can be cold treated between -70 and -80. The supercooling temperature affects bearing impact fatigue and contact life.

Cold treatment insulation: Although the transformation of a large number of martensite is completed between the cold and a certain temperature, in order to make the outer surface and the heart of a batch of rings uniformly reach the cold treatment temperature, a certain insulation time is required, generally 11.5h.

Otherwise easy to crack; Temper in time, otherwise the larger residual stress inside the ring will lead to ring cracking, generally not more than 2 hours after cold treatment of tempering: cold treatment of the ring placed in the air, the temperature slowly rises to room temperature after timely tempering. The temperature rise should not be too fast.

The role of cold treatment

Precision bearings have higher dimensional stability requirements; After quenching (especially grading quenching) of the ring, there is still a lot of residual austenite in the internal organization. This residual austenite is an unstable organization. During the storage and use of bearings, it will change from time to time, thus changing the accuracy of bearings. To this end, the cold treatment process can reduce the residual austenite in the tissue and slightly improve the hardness of the parts.