ROLE OF INTERNAL STRESSES IN THE HARDENING OF RAILS MADE OF HYPER-EUTECTOID STEEL DURING LONG-TERM OPERATION

10.25712/ASTU.1811-1416.2026.03.005

Abstract

The structure of 100-meter differentiated-tempered DT400IK rails made of E90KHAF eutectoid steel was studied using transmission electron diffraction microscopy after long-term operation on the Trans-Baikal Railway (243.7 million tons of traffic). The morphological components of the structure were classified, and it was noted that the strength of steel is determined by the combined action of several physical mechanisms, one of which is internal stress hardening. The level of internal stresses has been analyzed, and their role in strengthening the steel has been determined in two sections of the same rail head ("rolling surface" and "fillet") at equal distances from the wheel-rail contact surface. The use of formulas for estimating internal long-range stress fields for plastic, elastic, and elastic-plastic bending of the crystal lattice is substantiated. It is shown that as the structure approaches the surface of the head, it undergoes increasing plastic deformation, which is most noticeable in the radius of curvature of the fillet. It has been established that the strengthening mechanisms on the “rolling surface” and in the “fillet” are different: on the “rolling surface” the main strengthening mechanism is strengthening by internal long-range stresses, in the “fillet” it is substructural strengthening