Akademik Veri Yönetim Sistemi
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 2025 (SCI-Expanded, Scopus)
The increasingly demanding loading conditions in railway networks necessitate steels with superior wear and fatigue resistance. Field studies on decommissioned rails and switches reveal that while wear occurs gradually, fatigue failure often develops much faster. During operation, railway crossings experience combined rolling, impact, and sliding stresses, with the most severe contact occurring as the wheel moves from the wing rail to the crossing nose. This transition imposes extremely high contact forces, leading to significant damage on both components. This study aims to develop a technological solution to extend the service life of crossing noses made from R260 rail steel. Wear experiments were conducted using an inclined impact-sliding wear test machine to simulate the complex loading conditions of crossings. R260 pearlitic rail steel was plasma nitrided at 500°C for 12 h in a gas mixture of 80 vol. % N2and 20 vol. % H2. The process produced a 15 ± 4 μm thick compound layer composed of ε-Fe2-3N and γˈ-Fe4N phases. Impact-sliding wear tests demonstrated that the plasma-nitrided R260 steel exhibited significantly lower wear loss than the untreated steel at room temperature. Under a contact pressure of 1.59/2.89 GPa, the biphasic compound layer (∼15 μm) adhered firmly to the substrate, effectively resisting wear. Unlike most nitriding studies focusing on tool or stainless steels under rolling or sliding conditions, this work examines plasma nitriding applied to pearlitic rail steel under combined impact-sliding loads representative of real crossing service. The novelty lies in correlating the microstructural and phase evolution (ε-Fe2-3N + γˈ-Fe4N) of the nitrided layer with its impact-sliding wear resistance. This research extends plasma nitriding applications to high-carbon rail steels and provides new insights into the tribo-dynamic behavior of nitrided layers under severe cyclic impact-sliding stresses typical of railway crossings.