OBRABOTKAMETALLOV Vol. 25 No. 1 2023 13 TECHNOLOGY References 1. Urban D. Novye khromistye stali dlya ispol’zovaniya v usloviyakh vysokikh temperatur [New chromium steels for high temperature applications]. Chernye metally, 2018, no. 7, pp. 67–68. (In Russian). 2. Sizyakov V.M., Bazhin V.Yu., Patrin R.K., Feshchenko R.Yu., Saitov A.V. Features of high-amperage electrolyzer hearth breakdown. Refractories and Industrial Ceramics, 2013, vol. 54, pp. 151–154. 3. Gomes A., Navas M., Uranga N., Paiva T., Figueira I., Diamantino T.C. High-temperature corrosion performance of austenitic stainless steels type AISI 316L and AISI 321H, in molten Solar salt. Solar Energy, 2019, vol. 177, pp. 408–419. Analysis of the reasons for the formation of defects in the 12-Cr18-Ni10-Ti steel billets and development of recommendations for its elimination Sergey Ryaboshuk a, *, Pavel Kovalev b Peter the Great St.Petersburg Polytechnic University, 29 Polytechnicheskaya st., St. Petersburg, 195251, Russian Federation a https://orcid.org/0000-0002-1183-8445, ryaboshuk_sv@spbstu.ru, b https://orcid.org/0000-0003-1066-3812, kovalev_pv@spbstu.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. 6–15 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2023-25.1-6-15 ART I CLE I NFO Article history: Received: 01 October 2022 Revised: 01 November 2022 Accepted: 19 December 2022 Available online: 15 March 2023 Keywords: Austenitic steel 12-Cr18-Ni10-Ti Integranular corrosion δ-ferrite Martensitic orientation of the α-phase Acknowledgements Research were partially conducted at core facility “Structure, mechanical and physical properties of materials”. ABSTRACT Introdution. Austenitic steel (e.g., AISI 304, AISI 321, AISI 316, AISI 403, 12-Cr18-Ni10-Ti, etc.) is widespread, which is caused by high corrosion resistance and the corresponding possibility of use in aggressive media. The following most common types of 12-Cr18-Ni10-Ti steel defects can be distinguished: integranular corrosion, martensitic orientation of the α-phase and ferrite δ-phase. The purpose of work: to analyze the defects formation reasons of the 12-Cr18-Ni10-Ti steel grade billets and to develop recommendations for their elimination. The methods of investigation. Tests of 12-Cr18-Ni10-Ti steel samples for resistance to integranular corrosion, metallographic analysis of defects were carried out in this work. Hardness measurements were carried out for various degrees of billets reduction. Thermodynamic calculations of phase equilibrium in multicomponent steel for different temperatures were performed by the Thermo-Calc software. Results and Discussion. It is determined that in order to prevent integranular corrosion, it is necessary to reduce the nitrogen and carbon content in steel at the stage of ladle refi ning to 0.05%, and also to ensure the concentration of titanium in steel is not less than the permissible value — 0.3%. These measures contribute to the reduction of Cr23C6 chromium carbides responsible for integranular corrosion. It is necessary to reduce the degree of compression of the billets to a level of no more than 50% to prevent the appearance of a ferromagnetic martensitic α-phase, since the formation of this defect is associated with a high degree of compression during drawing. The high-temperature phase of δ-ferrite exists in the metal structure in a wide temperature range. Reducing this range to 100 degrees or less by optimizing the composition of the carbon and chromium alloy in accordance with GOST 5632-2014 leads to a signifi cant reduction of the amount of ferrite. However, it is not possible to completely eliminate it from the structure of steel. For all cases, it is necessary to assign austenization of billets in the temperature range of 1,050…1,100 °C. For citation: Ryaboshuk S.V., Kovalev P.V. Analysis of the reasons for the formation of defects in the 12-Cr18-Ni10-Ti steel billets and development of recommendations for its elimination. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty)= Metal Working and Material Science, 2023, vol. 25, no. 1, pp. 6–15. DOI: 10.17212/1994-6309-2023-25.1-6-15. (In Russian). ______ * Corresponding author Ryaboshuk Sergey V., Senior Lecturer Peter the Great St.Petersburg Polytechnic University 29 Polytechnicheskaya st., 195251, St. Petersburg, Russian Federation e-mail: ryaboshuk_sv@spbstu.ru
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