OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 4 2022 The effect of heat treatment on the formation of MnS compound in low-carbon structural steel 09Mn2Si Roman Sokolov a, *, Vitaly Novikov b, Ilja Kovenskij c, Kamil Muratov d, Anatolii Venediktov e, Larisa Chaugarova f Tyumen Industrial University, 38 Volodarskogo, Tyumen, 625000, Russian Federation a https://orcid.org/0000-0001-5867-8170, falcon.rs@mail.ru, b https://orcid.org/0000-0002-1987-351X, vitaly.nowikov2017@yandex.ru, c https://orcid.org/0000-0003-3241-8084, kovenskijim@tyuiu.ru, d https://orcid.org/0000-0002-8079-2022, muratows@mail.ru, e https://orcid.org/0000-0002-6899-4297, annattoliy@gmail.com, f https://orcid.org/0000-0002-6376-2868, chaugarovalz@tyuiu.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. 2022 vol. 24 no. 4 pp. 113–126 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2022-24.4-113-126 ART I CLE I NFO Article history: Received: 20 June 2022 Revised: 11 July 2022 Accepted: 08 September 2022 Available online: 15 December 2022 Keywords: SEM Microstructure MnS compound Structural steel Nonmetallic inclusions Grain size Acknowledgements Research were partially conducted at core facility “Structure, mechanical and physical properties of materials”. ABSTRACT Introduction. The properties of steels are determined by many factors, including the manufacturing process and subsequent treatment. Some features of these processes lead to the fact that in steel, apart from alloying elements added to obtain a certain level of physical and mechanical properties, there are also foreign impurities that enter it at various stages. Foreign elements can not only dissolve in the matrix, but also participate in the formation of particles of nonmetallic inclusions acting as defects. Its presence significantly affects the performance characteristics of the material. That is why it is necessary to understand the processes that lead to the appearance of nonmetallic inclusions and affect its shape. Purpose: to consider the effect of heat treatment, leading to the appearance of a ferrite-martensitic structure, on the shape and size of nonmetallic inclusions; to determine its influence on the physical and mechanical properties of the material. In the work, samples of rolled steel 09Mn2Si after heat treatment are studied. Research methods. To study the properties and structure of steel 09Mn2Si, the following methods were used: scanning electron microscopy – to study the structure of the material, chemical composition in the local area and the site under study and to determine the accumulation of impurities; SIAMS 800 software and hardware complex – to compare the structure of the material with the atlas of microstructures, to determine the score of the grain structure, differences in the structural and phase composition occurring during heat treatment; portable X-ray fluorescence analyzer of metals and alloys X-MET 7000 - to determine the chemical composition of the samples under study in percentage terms; Vickers hardness tester with a preload of 20 kg – to measure the hardness of the samples under study. Results and discussions. It is found that in the low-alloy low-carbon structural steel 09Mn2Si in most cases there are nonmetallic inclusions of the type of manganese sulfide formed during its manufacture. When this steel is heated to the temperatures of the intercritical transition, this compound is formed in the area of grain boundaries in the form of spherical inclusions. The presence of these inclusions significantly affects the strength and corrosion properties. Manganese sulfide acts as the point of the corrosion process initiation. For citation: Sokolov R.A., Novikov V.F., Kovenskij I.M., Muratov K.R., Venediktov A.N., Chaugarova L.Z. The effect of heat treatment on the formation of MnS compound in low-carbon structural steel 09Mn2Si. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2022, vol. 24, no. 4, pp. 113–126. DOI: 10.17212/1994-6309-2022-24.4-113-126. (In Russian). ______ * Corresponding author Sokolov Roman A., Post-graduate Student, Assistant Tyumen Industrial University, 38 Volodarskogo str., 625000, Tyumen, Russian Federation Tel.: 8 (919) 925-88-47, e-mail: falcon.rs@mail.ru Introduction Heat treatment processes largely determine the final properties of steels. It is known that for certain steel grades, generally, the use of certain heat treatment processes is not typical due to its small effect on the properties of the steel. For example, the quenching process is not used in everyday practice for low-carbon steels. However, the studies [1-5] show that the application of the quenching process with a temperature range corresponding to the intercritical interval, leads to the formation of two-phase ferrite-
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