Briefly describe the hazards of FAG bearing metamorphic layer

1. Cold plastic deformation layer: In the grinding process, each moment of abrasive grain is equivalent to a cutting edge. However, in many cases, the front angle of the cutting edge is negative, and the abrasive grain in addition to the cutting effect is to make the surface of the workpiece bear the extrusion action (ploughing effect), so that the surface of the workpiece leaves an obvious plastic deformation layer. The degree of deformation of this deformation layer will increase with the degree of bluntness of the grinding wheel and the increase of grinding feed.
2. Thermoplastic deformation layer: the instantaneous temperature of grinding heat formed on the working surface makes the elastic limit of the workpiece surface layer at a certain depth drop sharply, and even reaches the degree of elasticity disappearance. At this time, the free stretching caused by the grinding force, especially the compression force and friction force, is limited by the base metal, and the surface is compressed (more plowed), causing plastic deformation in the surface layer. The high-temperature plastic deformation increases with the increase of the surface temperature of the workpiece under the condition that the grinding process remains unchanged.
3. Work hardening layer: Sometimes it can be found that the hardness of the surface layer caused by processing deformation is increased by microhardness method and metallographic method.
In addition, in addition to the grinding process, the surface decarburization layer caused by casting and heat treatment heating, if not completely removed in the subsequent processing, will remain on the surface of the workpiece and cause surface softening and deterioration, resulting in premature bearing failure.