What are the Reasons and Hazards of Surface Cracks in Bearing Steel Materials?

The main reasons for surface cracks in bearing steel materials are as follows:

1. Due to the microscopic pores in the steel, subcutaneous bubbles, serious non-metallic inclusions, too high heating temperature and forging, rolling after cooling too fast, as well as the steel terminal, the final rolling temperature is too low, etc. will lead to the surface of the steel cracks.

2. As a result of the mill guide plate with metal particles, improper installation of the exit guide plate, sharp corners and rolling contact and other parts of the mill sharp corners or protruding parts and rolling contact, so the surface of the steel carved out of the depth, width, length of grooves, that is, scrapes or scratches.

3. For cold-drawn bearing steel materials sometimes also appear transverse cracks, the reason is that bearing steel materials in the cold-drawing process, due to the presence of shrinkage residue in the material, more serious sparse or a large number of brittle non-metallic inclusions and other defects resulting in reduced strength of the material, plasticity is poor, not easy to deform and produce transverse cracks.

Bearing material surface cracks and scratches are characterized by a linear distribution along the rolling and drawing direction of the steel, sometimes one, more than several. It is easily observed from the outer diameter of the steel, transverse fracture or low times of hot pickled specimens.

The danger of material surface cracks:

Bearings with material cracks have a very low service life and often lead to sudden shattering during operation. For rolling element parts, in the process of use, either due to cracks resulting in a reduction in the load-bearing capacity of the parts and crushed, or along the material cracks fatigue peeling and failure.

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