DOI: 10.52150/2522-9117-2025-39-11
O. I. Babachenko1, D. Sc. (Tech.), Cor.-Mem. NAS of Ukraine, ORCID 0000-0003-4710-0343
R. V. Podolskyi1,2,Ph. D. (Tech.), Senior Researcher, ORCID 0000-0002-0288-0641
G. A. Kononenko1,3,*, D. Sc. (Tech.), Senior Researcher, ORCID 0000-0001-7446-4105
O. A. Safronova1, PhD -student, Researcher, ORCID 0000-0002-4032-4275
O. L. Safronov1, Junior Researcher, ORCID 0009-0007-1308-5380
Zh. A. Dementeva1,Researcher, ORCID 0009-0002-3194-9975
1Iron and Steel Institute of Z. I. Nekrasov National Academy of Sciences of Ukraine, Academican Starodubova Square, 1, Dnipro, 49107, Ukraine
2Institute of Applied Control Systems National Academy of Sciences of Ukraine, Akademika Glushkova Ave., 42, Kyiv, 03187, Ukraine
3Dnipro University of Technology, Dmytra Yavornytskoho Avenue, 19, Dnipro, Ukraine, 49005, Ukraine.
* Corresponding author: perlit@ua.fm
COMPARATIVE ANALYSIS OF CHANGES IN MICROHARDNESS OF CAST AND ROLLED RAILWAY WHEELS OF DIFFERENT CLASSES AFTER EMERGENCY BRAKING
Abstract. Actuality. The development of railway transport in Ukraine acquires special strategic importance in conditions of martial law and in the period of post-war reconstruction. One of the key factors of reliability and safety of rolling stock is the condition of the rolling surface of railway wheels, which during operation is subjected to complex thermomechanical loads. The occurrence of defects of thermal origin, such as white etching layer (WEL), sliders, thermal cracks and others, significantly reduces the resource of the wheel and causes additional costs for maintenance and repair. Purpose. Laboratory study of the influence of the chemical composition of steel and the method of production of railway wheels on the formation of WEL and BEL under conditions of extreme braking. Methodology. As materials for the study, samples from the rims of railway wheels of different manufacturing methods (solid-rolled and cast), classes C and B and grade 2 with different carbon content (0.61-0.76%) and hardness (293-333 HB) were selected. The experiments were performed on a special test stand that simulated the conditions of emergency braking by a wheel at a speed of 100 km/h. The determination of mechanical properties was carried out on Instron and PSV-30 testing machines; hardness was estimated by Brinell and microhardness. Metallographic studies were carried out using Carl Zeiss optical microscopes after etching the samples with nital. Results. It was established that in all samples after the tests a WEL zone with a martensitic structure and increased hardness (up to 8000 N/mm²) is formed. Cast wheels are characterized by a greater thickness of WEL (4– 4.3 mm) than solid-rolled wheels (2–3 mm), which is due to more pronounced chemical heterogeneity and dendritic liquation. The presence of a BEL transition zone with a hardness of 3000–7200 N/mm² was revealed, which is a highly dispersed pearlite with increased etching ability. With increasing carbon content, the WEL thickness increases: for steel with 0.76% C – about 3 mm, while for steel with 0.61% C – about 2 mm. Conclusions. It was confirmed that the chemical composition and the method of manufacturing the wheel are determining factors of the sensitivity of steel to the formation of WEL and BEL. Cast wheels demonstrate a greater tendency to the development of thermal defects, while solid-rolled wheels are more stable due to a more homogeneous structure. The results obtained can be used to optimize the chemical composition and manufacturing technology of railway wheels with increased resistance to deformation and thermal loading.
Key words: chemical composition, operational defects, microhardness, railway transport, microstructure, thermal load.
For citation:Babachenko, O. I., Podolsky, R. V., Kononenko, G. A., Safronova, O. A., Safronov, O. L., & Dementieva, Zh. A. (2025). Comparative analysis of changes in microhardness of cast and rolled railway wheels of different classes after emergency braking. Fundamental and applied problems of ferrous metallurgy, 39, 195-209. https://doi.org/10.52150/2522-9117-2025-39-11
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Received 04.08.2025
Accepted 21.10.2025
Published online 01.12.2025
