OBRABOTKAMETALLOV Vol. 27 No. 3 2025 218 MATERIAL SCIENCE Features of the structure of gradient layers «steel - Inconel - steel», obtained by laser direct metal deposition Svetlana Dolgova 1, a, Alexandr Malikov 2, b, Alexander Golyshev 2, c, Aelita Nikulina 3, d,* 1 Novosibirsk semiconductor device plant Vostok, 60 Dachnaya st., Novosibirsk, 630082, Russian Federation 2 Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, 4/1 Institutskaya str., Novosibirsk, 630090, Russian Federation 3 Novosibirsk State Technical University, 20 Prospekt K. Marksa, Novosibirsk, 630073, Russian Federation a https://orcid.org/0000-0003-3918-273X, svetlanadolgova99@gmail.com; b https://orcid.org/0000-0003-1268-8546, smalik707@yandex.ru; c https://orcid.org/0000-0002-4243-0602, alexgol@itam.nsc.ru; d https://orcid.org/0000-0001-9249-2273, a.nikulina@corp.nstu.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. 3 pp. 205–220 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2025-27.3-205-220 ART I CLE I NFO Article history: Received: 13 June 2025 Revised: 27 June 2025 Accepted: 22 July 2025 Available online: 15 September 2025 Keywords: Additive manufacturing Microstructure Gradient layers Phase composition Austenitic stainless steel 316L Nickel alloy Inconel 625 Funding The work was carried out within the framework of the state assignment of the S.A. Khristianovich Institute of Theoretical and Applied Mechanics SB RAS No. 124021500015-1. Acknowledgements Experiments on direct laser deposition were carried out at the Center of Collective Use “Mechanics” of ITAM SB RAS. Structural research was conducted at core facility “Structure, mechanical and physical properties of materials” NSTU and scientifi c and educational center in the fi eld of mechanical engineering of NSTU. ABSTRACT Introduction. Traditionally, the most common technology for producing parts from nickel alloys involves casting followed by heat treatment to achieve the required phase composition. Signifi cant disadvantages of this method include the segregation of chemical elements, the presence of large undesirable inclusions such as Laves phase and eutectic structures, and the non-uniform distribution of strengthening phases throughout the workpiece cross-section. At the same time, many complex-shaped parts are assembled into a single combined structure using welding. An analysis of the hardening characteristics of nickel alloys and the products derived from them suggests that additive manufacturing techniques are a promising approach for fabricating such workpieces. The structure and phase composition of the material volumes formed via layer-by-layer deposition will diff er signifi cantly from those obtained by conventional methods. In the case of producing combined structures using additive methods, identifying the patterns of structure and phase composition formation becomes an even more complex challenge. Therefore, the purpose of this work is to identify the structural features of “steel - nickel alloy – steel” gradient layers fabricated by direct metal deposition. The study examines dissimilar joints produced using the “Welding and Surfacing Complex based on a Multi-Coordinate Arm and a Fiber Laser” at the S.A. Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences, employing direct metal deposition technology. Research methods. A Carl Zeiss Axio Imager A1m light microscope and a Carl Zeiss EVO 50 XVP scanning electron microscope, equipped with an INCA X-Act energy-dispersive X-ray spectroscopy (EDS) attachment, were utilized for microstructural investigations of the fabricated layers. Phase composition analysis of the samples was performed using an ARL X’TRA X-ray diff ractometer. Microhardness testing was conducted using a Wolpert Group 402 MVD Vickers hardness tester. Results and discussion. It was observed that the maximum layer height (up to 7 mm) was achieved when implementing the following parameters: 1,000 W laser power with a scanning speed of 35 mm/s, and 1,500 W laser power with a scanning speed of 15 mm/s. In the fi rst case, minimal material mixing at the fusion boundary was noted. In all fabricated compositions, defects in the form of unmelted powder particles were observed, as well as cracks in the fi rst steel layers. During the deposition of Inconel 625 onto 316L stainless steel, the transition zone exhibited solidifi cation modes consistent with the formation of iron-based alloys, specifi cally FA (ferrite-austenite), AF (austenite-ferrite), and A (austenite) sequentially. When depositing 316L stainless steel onto Inconel 625, the transition zone exhibited a solidifi cation mode characterized by the formation of only the austenite phase. The microhardness values were found to be 230 ±15 HV for 316L stainless steel and 298 ± 20 HV for Inconel 625. For citation: Dolgova S.V., Malikov A.G., Golyshev A.A., Nikulina A.A. Features of the structure of gradient layers «steel - Inconel - steel», obtained by laser direct metal deposition. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2025, vol. 27, no. 3, pp. 205–220. DOI: 10.17212/1994-6309-2025-27.3-205-220. (In Russian). ______ * Corresponding author Nikulina Aelita A., D.Sc. (Engineering), Professor Novosibirsk State Technical University, 20 Prospekt K. Marksa, 630073, Novosibirsk, Russian Federation Tel.: +7 383 346-11-71, e-mail: a.nikulina@corp.nstu.ru
RkJQdWJsaXNoZXIy MTk0ODM1