Enhancing impact-sliding wear resistance of R260 rail steel via γ′-dominant plasma nitriding
Wear, cilt.600, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 600
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.wear.2026.206804
- Dergi Adı: Wear
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, Index Islamicus, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Impact-sliding wear, Plasma nitriding, R260 rail steel, Railway switches and crossings, Surface engineering
- Bilecik Şeyh Edebali Üniversitesi Adresli: Evet
Özet
Impact-sliding wear is a critical degradation mechanism in railway switches and crossings, where rail steels are subjected to extremely high contact stresses and repeated dynamic loading. In this study, the influence of plasma nitriding on the impact-sliding wear behavior of pearlitic R260 rail steel was systematically investigated under service-representative contact conditions. Plasma nitriding was performed at 500 °C for 12 h using a low nitrogen potential gas mixture (20 vol% N2/80 vol% H2) to promote the formation of a mechanically stable compound layer. Microstructural characterization revealed the development of a ∼5.4 μm biphasic compound layer composed predominantly of γ′-Fe4N with a reduced fraction of ε-Fe2-3N, supported by a nitrogen-enriched diffusion zone with an effective case depth of approximately 110 μm. X-ray diffraction analysis confirmed the presence of nitride phases together with significant lattice distortion and compressive residual stresses induced by nitrogen supersaturation. Impact-sliding wear tests conducted under Hertzian contact pressures up to ∼2.9 GPa demonstrated that plasma nitriding significantly improved the wear performance of R260 steel. The nitrided steel exhibited a reduction in wear of approximately 57 % in the impact-dominated zone, 25 % in the sliding-dominated zone, and 33 % overall compared with the untreated condition. Microstructural and subsurface analyses revealed that the improved wear resistance is associated with increased surface hardness (∼880 HV), compressive residual stresses, and the enhanced load-bearing capacity provided by the γ′-rich nitrided layer. These findings demonstrate that controlled low-potential plasma nitriding is an effective surface engineering approach for improving the resistance of rail steels to severe impact-sliding wear conditions encountered in railway crossings.