What is the Effect of Banded Carbide on the Various Properties of Bearing Steels?

Banded carbide has the following adverse effects on the various properties of bearing steel:

1. Lead to serious deviations in the chemical composition of the bearing steel material. In the carbide band carbon content can be as high as 1.3% to 1.4%, chromium content is greater than 2.0%; while in the carbide band between the carbon content is low, generally only 0.6% to 0.7%, chromium content is less than 1%.

2. Due to carbide banding caused by the uneven chemical composition of the bearing steel material, resulting in uneven distribution of carbide in the bearing parts after annealing organization, and incomplete spheroidization between the two carbide bands.

3. Because the carbide band of carbon, chromium content is low, easy to form a coarse needle martensite organization. If the organization exceeds the standard level requirements, the whole batch of bearing parts must be reheated; if the finished bearing inspection found due to carbide banding caused by heat treatment organization exceeds the standard, the whole batch of bearing parts will all be scrapped, which will cause great economic losses to the bearing manufacturer.

Due to the characteristics of the bearing, in the standard of rolling bearing parts heat treatment on the bearing parts heat treatment quenched and tempered hardness and uniformity of hardness has very strict provisions. If there is a more serious carbide banding in the bearing steel, it is easy to cause the bearing parts in the heat treatment of hardness or hardness unevenness can not meet the relevant provisions of the standard.

4. Heat treatment quenching process is difficult to adjust. Easy to carbide banding in the vicinity of the region

Needle martensite, while some areas of the quench organization.

5. Quenching and heating superheat sensitivity increases, the heat treatment process is prone to quenching cracks.

6. Due to differences in chemical composition, the mechanical properties of the carbide zone and between the zone are not consistent.

7. Bearing parts turning surface finish is poor, the tool is easy to wear.

8. Reduce the service life of the bearing. Carbide band rating up to grade 3~4 can reduce the contact fatigue life of bearing steel by about 30%.

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