“…Optical micrographs of DER in martensitic 100Cr6 steel bearing inner ring can be seen in Figure 13 where DER is parallel to the surface in the circumferential section but appear as a sickle shape in the axial section corresponding to the size of Hertzian contact area. DER is a consequence of martensite decay under RCF due to stress-induced phase transformations [2,3,6,8,13,24,86,90,143,147,[149][150][151][152]. The altered microstructure consists of a ferritic phase with inhomogeneously distributed excess carbon corresponding to the parent martensite [13,143,153,154].…”