OBRABOTKAMETALLOV Vol. 28 No. 3 2026 310 MATERIAL SCIENCE Evaluation of the possibility of reducing residual austenite during laser carburization of low-carbon steel by additional cryogenic treatment Antonina Karlina1, a, *, Vitaly Gladkikh 1, b, Galina Vitkina 2, c, Roman Kononenko 2, 3, d, Viktor Kondratiev 2, 4, e 1 National Research Moscow State University of Civil Engineering, 26 Yaroslavskoe Shosse, Moscow, 129337, Russian Federation 2 Cherepovets State University, 5 Lunacharsky pr., Cherepovets, 162600, Russian Federation 3 Irkutsk National Research Technical University, 83 Lermontova str., Irkutsk, 664074, Russian Federation 4 A.P. Vinogradov Institute of Geochemistry SB RAS, 1A Favorskiy St., Irkutsk, 664033, Russian Federation a https://orcid.org/0000-0003-3287-3298, karlinat@mail.com; b https://orcid.org/0000-0003-1953-1584, gladkich_87@mail.ru; c https://orcid.org/0000-0002-1076-2709, 20procents@mail.ru; d https://orcid.org/0009-0001-5900-065X, istu_politeh@mail.ru; e https://orcid.org/0000-0002-7437-2291, imz@mail.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. 2026 vol. 28 no. 3 pp. 286–314 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2026-28.3-286-314 ART I CLE I NFO Article history: Received: 08 June 2026 Revised: 16 July 2026 Accepted: 29 July 2026 Available online: 15 September 2026 Keywords: Carburizing Paste Martensite Ledeburite Austenite ABSTRACT Introduction. Residual austenite is an austenitic phase that persists in steel after its incomplete transformation into martensite/bainite/ferrite. The presence of residual austenite in steel can cause positive or negative changes depending on its proportion. Therefore, the fi nished products must have an appropriate range of residual austenite content. In the process of traditional chemical and thermal treatment of metals by carburizing, residual austenite is an unacceptable defect in the process. Very few papers have been devoted to this issue in the processes of surface treatment of metals with concentrated energy sources. The purpose of this work is to reduce the residual austenite in the carburized layer after laser hardening using additional cryogenic treatment. Materials and methods. Laser carburizing of 0.2% C steel was performed with a continuous-wave ytterbium fi ber laser (LS-16, 1.5 kW, IPG Photonics, Oxford, MA, USA) emitting at a wavelength of 1.07 μm. The carbon content in the carburized layer was determined by glow discharge optical emission spectrometry (GD-Profi ler 2TM). Hardness was measured using a semi-automatic Vickers hardness tester with a load of 500 g and an indentation pitch of 0.25 mm. X-ray diff raction patterns were recorded using a SmartLab 9KW diff ractometer with a Cu–Kα target (λ = 1.5406 Å). The scanning angle range of 2θ ranged from 40 to 100°, and the scanning speed was 2°/min. Quantitative analysis of the volume fraction of residual austenite was carried out in accordance with the recommendations specifi ed in ASTM E97513. Cryogenic treatment was carried out at a temperature of –196 °C. Results and discussion. Diff erent graphite contents in the laser carburizing pastes lead to the formation of diff erent structures and phases (cementite, ledeburite, martensite, residual austenite) in the surface layer. Microstructural examination of the surface layer showed that the structure of the original material (0.2% C steel) consists of soft and ductile ferrite with hard pearlite. The thermal gradient on the surface of the molten carbon-containing mixture, created by the laser beam, transformed the original microstructure into martensite by dissolving the carbonaceous mixture and solidifying the austenitic phase into martensite through rapid cooling. At the same time, residual austenite is formed in the surface layer due to rapid cooling. It was shown that laser carburizing leads to the formation of a modifi ed surface layer consisting of carbonsaturated martensite, residual austenite and carbides. Cryogenic and tempering treatments additionally transform residual austenite in the carburized layer into martensite, which increases the hardness of the carburized layer. For citation: Karlina A.I., Gladkikh V.A., Vitkina G.Y., Kononenko R.V., Kondratiev V.V. Evaluation of the possibility of reducing residual austenite during laser carburization of low-carbon steel by additional cryogenic treatment. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2026, vol. 28, no. 3, pp. 286–314. DOI: 10.17212/1994-6309-2026-28.3-286-314. (In Russian). ______ * Corresponding author Karlina Antonina I., Ph.D. (Engineering), Research Associate National Research Moscow State Construction University, 26 Yaroslavskoe shosse, 129337, Moscow, Russian Federation Tel: +7 950 120-19-50, e-mail: karlinat@mail.ru
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