Failure forms of GCr15 Bearing Steel

Bearing steel is damaged after running for a long time under the comprehensive action of complex factors. There are two main forms of damage: one is contact fatigue damage. Under the action of high contact stress, after several stress cycles, the local area of the working face produces pits, which increases the noise, vibration, temperature and wear of the bearing, resulting in the abnormal operation of the bearing. The other is the wear failure caused by relative movement. The normal failure mode of rolling bearings is usually fatigue spalling.

The fatigue failure of bearing steel includes the generation and development of fatigue crack. The initial fatigue crack occurs at a certain depth from the surface, which is just consistent with the depth of the maximum shear stress. For general size bearings, with different loads, the maximum shear stress should appear at a depth of 0.35-0.55mm below the contact surface. Under the action of the maximum shear stress, the metal in this region first undergoes plastic deformation. If the contact stress is greater than the contact fatigue limit of the material, with the increase of the number of stress cycles, the plastic deformation occurs continuously at the place where the plastic deformation has occurred, and the fatigue crack occurs here because the plastic deformation cannot be carried out.

Under normal conditions, the microcracks are approximately 45 ° Angle. The fatigue spalling crack on the contact path of rolling bearing propagates gradually under the action of repeated stress, and usually develops along the area of uneven distribution of internal structure, composition and stress of the material, and then extends to the surface, breaking from the crack root, forming fatigue spalling.