Problems of Tribology = Проблеми трибології - 2025 рік

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Перегляд Problems of Tribology = Проблеми трибології - 2025 рік за Ключові слова "medium pressure"

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    Wear resistance of structural steels carbonitrated by the separate method
    (Хмельницький національний університет, 2025) Stechyshyn , M.S.; Dykha, O.V.; Zdorenko, D.V.; Oleksandrenko, E.G.
    The article investigates the influence of technological modes of separate carbonitriding of carbon steels on the thickness and microhardness of the hardened layer. Two hardening variants were investigated: first, carburizing of surfaces was carried out in argon-propane, and then nitriding in argon-nitrogen mixtures and vice versa. As the conducted studies have shown, the variant of the hardening technological process significantly affects the physical and mechanical characteristics of the hardened layer. In all two variants of the technological process, the hardened layer consists of a surface carbonitride zone and a diffusion zone of internal nitriding, but the properties of these zones are different in different variants of the technological process. Thus, when hardening steels according to the first mode, the thickness of the carbonitride zone is maximum, and the internal nitriding zone has a small thickness. This is explained by the fact that the carbonitride layer created on the steel surface at the first stage of processing performs the function of shielding the surface from the penetration of nitrogen ions into the surface layer of the metal. When hardening according to the second mode, the carbonitride zone has a slightly smaller thickness, but a more developed internal nitriding zone. In addition, carbonitriding according to the first mode leads to the formation of carbonitride inclusions in the diffusion zone in the form of a mesh, which significantly reduce the plasticity of the layer and under dynamic loads are centers of microcrack nucleation. It has also been established that a carbonitride ε − phase is formed on the surface of steels, which consists of carbonitrides of the type Fe2(N,C), Fe3(N,C), Fe4(N,C). The carbonitride zone has high hardness, high corrosion resistance, and increased wear resistance. The thickness of the carbonitride zone reaches a thickness of up to 25 microns. Under the carbonitride zone is the internal nitriding zone, which has a large thickness and is the main part of the carbonitrided layer. The internal nitriding zone consists of a nitrogenous solid solution of the base metal, its nitrides and nitrides of alloying elements. The dependences of thickness and microhardness on the technological parameters of carbonitriding of carbon steels obtained in the work: temperature, saturation time, composition of the gas medium, its pressure allow them to be optimized depending on the requirements of further operation