Evaluating the stress intensity factor for R350HT rail steel in relation to microstructure parameters

The study highlights the advancement of rail transport, focusing on the distinct requirements of high-speed passenger transit and robust freight operations. Passenger rails emphasize geometric precision, such as straightness and minimal dimensional deviation, to reduce vibrations and improve safety and comfort. Freight rails, in contrast, require exceptional durability to withstand high axial loads, plastic deformation, and abrasive wear due to heavy tonnage. A key parameter for all rail types is the stress intensity factor (KIc), which ensures rail integrity by preventing crack propagation. The study confirmed that tested rail types (60E2, 54E4, and 49E1) meet the EN 13674-1 standard for mechanical properties, indicating effective heat treatment. Residual stress levels were found to be low, particularly in lighter rails, enhancing resistance to brittle fracture. All rails exhibited a fine, fully pearlitic microstructure with cementite lamellae spacing between 92 and 106 nm, contributing to mechanical strength and durability. The low residual stress and high KIc support extended rail life and safety, as larger critical crack sizes minimize fracture risk. These findings underline the reliability and safety of rail materials under operational conditions, with consistent pearlitic structures and optimized stress properties ensuring robust performance.

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Opracowanie rekordu ze środków MNiSW, umowa nr POPUL/SP/0154/2024/02 w ramach programu "Społeczna odpowiedzialność nauki II" - moduł: Popularyzacja nauki (2025).