The structural-phase state of the rolling surface and head fillet of differentially hardened 100-meter rails after ultra-long operation (passed tonnage 1770 million gross tons) has been studied. It was found out that the transformation of the pearlite structure on the rolling surface occurred more slowly as compared with the one of the working fillet surface. The distribution of carbon atoms in the rail structure was estimated.
Громов et al. (Sat,) studied this question.