White-type Microstructural Change in Rolling Contact Fatigue from the Viewpoint of Severe Plastic Deformation

It is well known that three types of white-colored microstructural changes occure in rolling contact fatigue (RCF). Those are called WB (White band), Butterfly and WEA (White etching area) respectively. As the conditions of bearing use have become severer, recently these phenomena are observed more frequently. However, their formation mechanisms and countermeasures have not been clarified, because very complicated factors are involved in these phenomena. Authors remark the fact that white-colored microstructural changes consist of ultrafine grains. Although the formation of such ultrafine grains are generally found in SPD (Severe Plastic Deformation), it is expected that the knowledge in this field would be useful in the field of RCF, as well.From this point of view, microstructural changes in RCF were reviewed in this report, referring previous studies and recent authors studies.