Effect of dislocation structure on hardening of hypereutectoid rail steel

The fine structure of DT400IK rails made of E90KhAF steel (Russian name) was studied after long-term operation on an experimental ring and on the Trans-Baikal Railway. A comparative assessment of the quantitative parameters of the structure at different distances from the rolling surface along the central axis was performed. It is shown that the main difference between the steels of these two batches is the presence of a subgrain structure. The main mechanisms of strengthening of steel of both the batches have been established: strengthening by internal long-range stress fields and substructural strengthening.