OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 1 2023 Diffusion coatings formation features, obtained by complex chemical-thermal treatment on the structural steels Aleksandr Sokolov a, Eduard Bobylyov b, *, Roman Popov c Kuban State Technological University, 2 Moskovskaya st., Krasnodar, 350072, Russian Federation a https://orcid.org/0000-0002-8105-1429, sag51@bk.ru; b https://orcid.org/0000-0001-7754-1807, ebobylev@mail.ru; с https://orcid.org/0000-0003-4875-5018, popov-romanya@yandex.ru Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2023 vol. 25 no. 1 pp. 98–109 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2023-25.1-98-109 ART I CLE I NFO Article history: Received: 03 October 2022 Revised: 03 November 2022 Accepted: 19 December 2022 Available online: 15 March 2023 Keywords: Diffusion Coating Chromium Thermal-chemical treatment Steel Acknowledgements Research were partially conducted at core facility “Structure, mechanical and physical properties of materials”. ABSTRACT Introduction. The main methods of increasing the efficiency of products made from structural steels are considered. A description of diffusion saturation from liquid metal media solutions (DSLMMS) is given. Also, complex diffusion saturation technology (CDS), including DSLMMS and carburization is shown. The purpose of the work is to reveal the effect of steel composition on the process of formation and elemental composition of diffusion-saturated surface layers (coatings) based on chromium, as well as to establish differences and regularities in the processes of formation of diffusion-saturated coatings after DSLMMS and CDS. The methods of investigation. Cylindrical specimens 20 mm in diameter and 30 mm long were subjected to DSLMMS. The specimens were made of carbon and alloyed steels: St3, 20-Cr13, 40-Cr, 40-Cr13, 12-Cr18-Ni10-Ti. At the same time, some of the specimens were previously subjected to vacuum cementation. An eutectic Pb-Bi with the specified content of Cr was used as a transport medium when executing DSLMMS. Metallographic studies were carried out on microsection prepared according to the standard method. Studies to determine the thickness of coatings and its structure were carried out on the Dura Scan Falcon 500 Microhardness Tester. The elemental composition of the coatings was determined by the method of electron microprobe analysis on a Tescan Lyra 3 scanning electron microscope with the Oxford Ultim MAX PCMA system. Results and discussion. As a result of the research, it was revealed that the formation of saturated coatings occurs with DSLMMS and CDS. At the same time, the thickness of the coatings and its elemental composition depend on the steel grade and the technology used. After DSLMMS concentration of Cr varies from 96.9% to 91.1%. At the same time, the maximum concentration of 96.9% is observed on steel St3. After CDS, on the surfaces of all steel samples, the concentration of Cr decreases in comparison with the coatings obtained by the DSLMMS technology on steels: St3 from 96.9% to 66.8%; 40-Cr from 91.1% to 63.18%; 20-Cr13 from 93.18% to 62.54%; 12-Cr18-Ni10-Ti from 92.92% to 64.77%. The total thickness of diffusion-saturated coatings formed on all the alloys studied ranges from 17 to 17.5 µm. For citation: Sokolov A.G., Bobylyov E.E., Popov R.A. Diffusion coatings formation features, obtained by complex chemical-thermal treatment on the structural steels. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2023, vol. 25, no. 1, pp. 98–109. DOI: 10.17212/1994-6309-2023-25.1-98-109. (In Russian). ______ * Corresponding author Bobylyov Eduard Ed., Ph.D. (Engineering), Associate Professor Kuban State Technological University, 2 Moskovskaya st., 350072, Krasnodar, Russian Federation Tel.: +7-918-975-8933; e-mail: ebobylev@mail.ru Introduction One of the quite significant reasons of machine parts performance losing is its mechanochemical wear. In this case, the surface layers of parts are subjected to the main destructive effect. In this regard, the use of hardening technologies is one of the most common ways to improve the performance properties of parts [1–4]. Coatings are created on the surface of parts by surface hardening technologies. Usually, coatings base is Cr, Ti, W, Al, Mo, Ni and its chemical compounds with C and N. Such coatings have a crystalline structure. Coatings make it possible to vary such properties of structural steels surface layers as hardness, corrosion resistance, wear resistance, etc. At the same time, chromium-based coatings should be highlighted
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