OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 3 2025 microhardness for the steel regions in both cases is approximately 230 ± 15 HV, while for Inconel 625 it is around 298 ± 20 HV. Under the second and third processing modes, a slight decrease in the microhardness of the nickel alloy was observed, which can be attributed to higher heat input compared to mode 1. These results are in good agreement with previously published data, regardless of the specific deposition method used [10, 11, 19]. Conclusoin This study analyzed the structural features of gradient «316L steel – Inconel 625 – 316L steel» compositions fabricated via direct laser deposition. Results revealed that, during layer-by-layer fabrication of gradient structures comprising 12 layers, a maximum build height (up to 7 mm) was achieved under two distinct processing conditions: 1,000 W with a scanning speed of 35 mm/s, and 1,500 W with a scanning speed of 15 mm/s. Specifically, the former condition (1,000 W, 35 mm/s) resulted in minimal material mixing at the fusion boundary. All compositions exhibited a low density of defects, primarily in the form of unmelted powder particles located at the edges of the deposited structures. Cracking was most prevalent in the initial steel layers when employing higher laser power processing modes. The chromium-to-nickel equivalent ratio correlated with the formation of mixing zones exhibiting distinct solidification modes and phase compositions. Specifically, deposition of Inconel 625 onto 316L steel resulted in a transition zone, characteristic of iron-based alloy compositions, exhibiting successive solidification modes: FA (ferrite–austenite), AF (austenite–ferrite), and A (austenite). Conversely, deposition of 316L steel onto Inconel 625 yielded a transition zone with exclusively austenite solidification. These phase identification results were confirmed by X-ray diffraction analysis. Scanning electron microscopy further confirmed the presence of ferrite in the interdendritic regions on the steel side. Microhardness testing revealed minimal impact of deposition parameters on the average hardness of the materials. The microhardness of 316L steel was consistently measured at 230 ± 15 HV, while that of Inconel 625 averaged 298 ± 20 HV. References 1. Zhang Y., Hu M., Cai Z., Han C., Li X., Huo X., Fan M., Rui S., Li K., Pan J. Effect of nickel-based filler metal types on creep properties of dissimilar metal welds between Inconel 617B and 10 % Cr martensitic steel. Journal of Materials Research and Technology, 2021, vol. 14, pp. 2289–2301. DOI: 10.1016/j.jmrt.2021.07.131. 2. Meng W., Zhang W., Zhang W., Yin X., Cui B. Fabrication of steel-Inconel functionally graded materials by laser melting deposition integrating with laser synchronous preheating. Optics & Laser Technology, 2020, vol. 131, р. 106451. DOI: 10.1016/j.optlastec.2020.106451. 3. Naffakh H., Shamanian M., Ashrafzadeh F. Dissimilar welding of AISI 310 austenitic stainless steel to nickel-based alloy Inconel 657. Journal of materials processing technology, 2009, vol. 209 (7), pp. 3628–3639. DOI: 10.1016/j.jmatprotec.2008.08.019. 4. Reed R.C. The superalloys: fundamentals and applications. Cambridge, Cambridge university press, 2008. 363 p. ISBN 9780511541285. DOI: 10.1017/CBO9780511541285. 5. Knorovsky G.A., Cieslak M.J., Headley T.J., Romig A.D., Hammetter W.F. Inconel 718: A solidification diagram. Metallurgical transactions A, 1989, vol. 20 (10), pp. 2149–2158. DOI: 10.1007/BF02650300. 6. Xie H., Yang K., Li F., Sun C., Yu Z. Investigation on the Laves phase formation during laser cladding of IN718 alloy by CA-FE. Journal of Manufacturing Processes, 2020, vol. 52, pp. 132–144. DOI: 10.1016/j. jmapro.2020.01.050. 7. Yang J., Zheng Q., Zhang H., Sun X., Guan H., Hu Z. Effects of heat treatments on the microstructure of IN792 alloy. Materials Science and Engineering: A, 2010, vol. 527 (4–5), pp. 1016–1021. DOI: 10.1016/j. msea.2009.10.026. 8. Rashkovets M.V. Struktura i svoistva nikelevykh splavov, poluchennykh po additivnoi tekhnologii s ispol’zovaniem metoda pryamogo lazernogo vyrashchivaniya. Diss. kand. tekhn. nauk [Structure and properties of nickel alloys obtained by additive technology using the direct laser deposition method. PhD, eng. sc. diss.]. Novosibirsk, 2022. 164 p.
RkJQdWJsaXNoZXIy MTk0ODM1