OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 24 No. 1 2022 Effect of the deformation degree at low temperatures on the phase transformations and properties of metastable austenitic steels Svetlana Vologzhanina 1, a,*, Alexey Igolkin 2, b , Alexey Peregudov 3, c, Igor Baranov 2, d, Nikita Martyushev 4, e 1 Saint Petersburg Mining University, 2, 21st Line, St Petersburg, 199106, Russian Federation 2 ITMO University, 49 Kronverksky Pr., St. Petersburg, 197101, Russian Federation 3 SUE “Petersburg Metro”, 28 Moskovskiy Prospekt, St. Petersburg, 190013, Russian Federation 4 National Research Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk, 634050, Russian Federation a https://orcid.org/0000-0001-7675-865X, svet_spb@mail.ru , b https://orcid.org/0000-0001-8287-1851, igolkin47@mail.ru, с https://orcid.org/0000-0002-1273-0743, mikki435@gmail.com, d https://orcid.org/0000-0003-0595-368X, ivbaranov@itmo.ru, e https://orcid.org/0000-0003-0620-9561, martjushev@tpu.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2022 vol. 24 no. 1 pp. 73–86 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2022-24.1-73-86 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov ART I CLE I NFO Article history: Received: 30 December 2021 Revised: 21 January 2022 Accepted: 15 February 2022 Available online: 15 March 2022 Keywords: Metastable austenitic steel Low temperatures Phase-structural transformations Strain rate Martensite Mechanical properties ABSTRACT Introduction. For reliable operation of low-temperature equipment, it is necessary to use materials capable of ensuring operability in a wide temperature range under conditions of alternating loads, exposure to corrosive media, etc. Most often, in such cases, metastable austenitic steels (MAS) of various alloying systems are used. Despite suffi cient experience in the use of such materials, not enough information is collected on the behavior of such materials at low temperatures, including phase-structural transformations, the features of such transformations in different temperature zones, including when a load is applied, both static and dynamic. The subject of the study in this work is selected MAS 10Cr14NMn20 and 10Cr14Mn14Ni4Ti grades. The purpose of the study is to evaluate the performance of industrially used metastable austenitic steels for its possible use instead of steel 12Cr18Ni10Ti. Research methodology. The phase composition of the samples was studied on a DRON-3.0 X-ray diffractometer. Mechanical tests were carried out in the temperature range from +20 to –196 °C. Static uniaxial tensile tests were carried out on a R-20 tensile testing machine; cylindrical specimens with threaded heads were prepared according to GOST 11150–75, as well as samples with a circumferential notches. Dynamic bending tests were carried out on a pendulum impact tester, using samples according to GOST 9454–78. Results and Discussion. Based on the data obtained, it is found that an increase in the strain rate at low temperatures contributes to a decrease in the number of martensitic phases in the steels under study. It is found that the hardenability during elastic-plastic deformation decreases and completely disappears at the temperature of the material transition to a brittle state. It is shown that an increase in the rate of low-temperature deformation of samples prevents the development of phase martensitic transformations in steels. The results obtained can be recommended for use in the selection of materials for the manufacture of equipment operating at temperatures down to –196 °C. Conclusions. It is shown that the obtained values of the characteristics of mechanical properties make it possible to recommend the studied MAS as a substitute for steel 12Cr18Ni10Ti, down to a temperature of –196 °C. For citation: Vologzanina S.A., Igolkin A.F., Peregudov A.A., Baranov I.V., Martyushev N.V. Effect of the deformation degree at low temperatures on the phase transformations and properties of metastable austenitic steels. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2022, vol. 24, no. 1, pp. 73–86. DOI: 10.17212/1994-6309-2022-24.1-73-86. (In Russian). ______ * Corresponding author Vologzhanina Svetlana A., D.Sc. (Engineering), Professor Saint Petersburg Mining University 2, 21st Line, St Petersburg, 199106, Russian Federation Tel.: +79213491682, e-mail: svet_spb@mail.ru Introduction Low-temperature equipment is widely used in various industries such as metallurgy, chemistry, rocket science, energy and many others. In recent years, such industries as cryobiology, cryomedicine, cryoenergetics have been actively developing, in which it is necessary to use equipment capable of ensuring operability up to temperatures close to absolute zero [1–9].
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