The harm of fag bearing metamorphic layer is briefly described

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 rake angle of the cutting edge is negative. In addition to the cutting effect, the abrasive particles make the workpiece surface bear the extrusion effect (ploughing effect), leaving an obvious plastic deformation layer on the workpiece surface. The deformation degree of this deformation layer will increase with the blunt degree of grinding wheel and the increase of grinding feed.
2. Thermoplastic deformation layer: the instantaneous temperature formed by grinding heat on the working surface will sharply reduce the elastic limit of the workpiece surface layer at a certain depth, and even reach the degree of disappearance of elasticity. At this time, the free extension of the working surface layer caused by the grinding force, especially the compression force and friction force, is limited by the base metal, and the surface is compressed (more plough), resulting in plastic deformation in the surface layer. High temperature plastic deformation increases with the increase of workpiece surface temperature under the condition of unchanged grinding process.
3. Work hardening layer: sometimes it can be found that the hardness of the surface layer increases due to machining deformation by microhardness method and metallographic method.
In addition, in addition to grinding, if the decarburized layer on the surface caused by casting and heat treatment heating is not completely removed in the subsequent processing, it will also cause surface softening and deterioration and promote the premature failure of the bearing.