OBRABOTKAMETALLOV Vol. 27 No. 4 2025 113 TECHNOLOGY Evaluation of the melting ability of oxide fl uxes in A-TIG welding of carbon and low-alloy steels Antonina Karlina 1, a* , Viktor Kondratiev 2, 3, b, Vitaly Gladkikh 1, c, Galina Vitkina 3, d, Roman Kononenko 4, e 1 National Research Moscow State University of Civil Engineering, 26 Yaroslavskoe Shosse, Moscow, 129337, Russian Federation 2 A.P. Vinogradov Institute of Geochemistry of the Siberian Branch of the Russian Academy of Sciences, 1A Favorsky str., Irkutsk, 664033, Russian Federation 3 Cherepovets State University, 5 Lunacharsky pr., Cherepovets, 162600, Russian Federation 4 Irkutsk National Research Technical University, 83 Lermontova str., Irkutsk, 664074, Russian Federation a https://orcid.org/0000-0003-3287-3298, karlinat@mail.com; b https://orcid.org/0000-0002-7437-2291, imz@mail.ru; c https://orcid.org/0000-0003-1953-1584, gladkich_87@mail.ru; d https://orcid.org/0000-0002-1076-2709, 20procents@mail.ru; e https://orcid.org/0009-0001-5900-065X, istu_politeh@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. 2025 vol. 27 no. 4 pp. 96–115 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2025-27.4-96-115 ART I CLE I NFO Article history: Received: 14 September 2025 Revised: 07 October 2025 Accepted: 23 October 2025 Available online: 15 December 2025 Keywords: Welding Activating fl uxes Penetration depth Coating thickness ABSTRACT Introduction. Tungsten inert gas (TIG) welding has gained widespread popularity due to its advantages, including eff ective shielding, a stable arc, easy heat input adjustment, reduced metal spatter, and an attractive weld appearance. However, relatively shallow penetration and low effi ciency limit its application. To improve welding effi ciency and expand its scope of application, researchers both domestically and internationally have conducted signifi cant studies aimed at increasing the energy density of the traditional TIG arc. This includes activating TIG (A-TIG) arc welding, which utilizes a fl ux applied to the weld surface. Further investigation of the mechanism for increasing arc energy density in A-TIG welding will allow us to propose new ideas and methods for highly effi cient TIG welding technology. The purpose of this study is to evaluate the technological potential of using oxide activators TiO2 and SiO2 to improve penetration effi ciency and weld quality of carbon and low-alloy steels. Methods. This work involved comparative A-TIG welding tests. The tests included the use of 3.5 mm and 8 mm thick plates (300 mm × 300 mm) made of unalloyed (carbon) steel St3 and lowalloy steel 0.09 C-2Mn-Si. Welding tests included the use of single-component fl uxes in the form of oxides (TiO2, SiO2). All experimental welds were performed under the same conditions, without the use of fi ller metal (TIG welding), with a current in the range of 10–200 A and a welding speed of 150 mm/min. Arc voltage was maintained in the range of 10.4 V to 12.8 V; heat input was in the range of 0.499 kJ/mm to 0.614 kJ/mm. All welds were subjected to visual inspection of the surface condition and macrostructural studies to determine their dimensions. Results and discussion. Most tests observed signifi cant diff erences in arc shape compared to traditional TIG and A-TIG processes. Results of A-TIG welding tests on unalloyed and low-alloy steels showed that penetration depth increased slightly in steels characterized by a higher degree of deoxidation and metallurgical purity. Evidently, not every activator was responsible for the increased penetration depth, but the use of TiO2 and SiO2 oxides was undoubtedly benefi cial. An arc constriction mechanism is proposed, which is widely applicable to A-TIG welding of steel with various types of fl uxes studied. Arc constriction occurs due to the formation of negative ions in the outer region of the arc or due to the fl ux coating on the surface. Thus, arc constriction increases the current density and heat intensity at the root of the anode. This increases the force and pressure of magnetic constriction, resulting in a strong downward convection fl ow. The use of silicon and titanium oxides (TiO2 and SiO2) increases penetration depth during A-TIG welding, regardless of steel type and grade. The degree of penetration increase was limited to a range of 40% to 200%. For citation: Karlina A.I., Kondratiev V.V., Gladkikh V., Vitkina G., Kononenko R.V. Evaluation of the melting ability of oxide fl uxes in A-TIG welding of carbon and low-alloy steels. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2025, vol. 27, no. 4, pp. 96–115. DOI: 10.17212/1994-6309-2025-27.4-96-115. (In Russian). ______ * Corresponding author Karlina Antonina I., Ph.D. (Engineering), Research Associate National Research Moscow State University of Civil Engineering, 26 Yaroslavskoe Shosse, 129337, Moscow, Russian Federation Tel: +7 950 120-19-50, e-mail: karlinat@mail.ru References 1. Paton B.E., Zamkov V.N., Prilutsky V.P., Poritsky P.V. Kontraktsiya dugi fl yusom pri svarke vol’framovym elektrodom v argone [Arc contraction by fl ux during tungsten electrode welding in argon]. Avtomaticheskaya svarka = Automatic Welding, 2000, no. 1, pp. 3–9.
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