Heavy duty railways have extremely strict requirements for the performance of heavy rails. Taking the Daqin Railway as an example, the axle load of a 20000 ton heavy-duty train exceeds 30 tons, which is twice that of a regular train, and the pressure on the track reaches 800 MPa. The specially designed 60NHE heavy rail reduces contact stress by 25% by thickening the rail web and optimizing the rail head profile, effectively avoiding plastic deformation. In terms of material, high carbon steel containing 0.72% C and 1.0% Mn is used, combined with online waste heat quenching process, to achieve a rail head hardness of 330HBW and a 40% increase in wear resistance.
To cope with the challenges of heavy-duty transportation, heavy rails need to meet three special requirements: first, ultra-high strength, with a yield strength of ≥ 880MPa to withstand long-term alternating loads; Secondly, it has excellent anti stripping performance. By controlling the morphology of inclusions, the crack initiation period inside the rail head can be extended to three times that of ordinary rails; The third is good low-temperature toughness, with an impact absorption energy of over 40J at -20 ℃ to prevent brittle fracture in winter. These performance indicators ensure the safe operation of heavy-duty trains exceeding 1 billion ton kilometers.
