STRUCTURE AND PROPERTIES OF PLASMA COATINGS FROM HIGH-SPEED STEEL AFTER HIGH-TEMPERATURE TEMPERING

In this article, metallographic studies of the structure of multilayer coatings of high-speed steel R19Yu, formed in a nitrogen atmosphere during a multilayer plasma transfer arc with flux-cored wire, were carried out using the methods of light and scanning electron microscopy on transverse sections. The coatings have a disoriented dendritic structure with a characteristic dimension of the first-order axes of 100 μm, which changes little with depth. A carbide network of eutectic carbides of the Me₆C type is revealed in detail at high magnifications along the boundaries of solid solution grains with cell sizes in the range of 5–100 µm. The grid is bordered by a light layer of a homogeneous metal, apparently representing a low-alloyed ferrite. Small cells with characteristic dimensions of 5–10 µm have a homogeneous ferrite structure, while larger cells form an inner dark region that has an austenitic-martensitic structure with inclusions of finely acicular martensite. In larger cells, an inner dark region forms, which has an austenitic-martensitic structure with inclusions of equiaxed isolated carbides. Since the surfacing was carried out in a nitrogen atmosphere, the formation of nitrogen-containing carbides or carbonitrides in it should also be assumed. Under such crystallization conditions, complex carbides of the Fe3(W-Mo-N-V)3С type are also formed. The formation of nitrides Fe₄N is also possible. The characteristic size of martensitic needles in it is 1–3 μm. After four high-temperature temperings at 560 °C, as a result of the decay of residual austenite, the formation of tempered martensite, and the precipitation of dispersed carbides, the total microhardness increases from 472 to 528 HV and its distribution becomes more homogenous. In this case, the growth of martensitic needles is observed in the range of 2 to 6 μm.

1. Gladkii P.V., Perepletchikov E.F., Ryabtsev I.A. Plasma transfer arc. Kiev: Ekotekhnologiya, 2007, 292 p. (In Russ.).

2. Ryabtsev I.A., Senchenkov I.K. Theory and practice of surfacing works. Kiev: Ekotekhnologiya, 2013, 400 p. (In Russ.).

3. Sosnin N.A., Ermakov S.A., Topolyanskii P.A. Plasma technologies. Welding, coating, hardening. Moscow: Mashinostroenie, 2008, 406 p. (In Russ.).

4. Pokhodnya I.K., Shlepakov V.N., Maksimov S.Yu., Ryabtsev I.A. Research and development of the E.O. Research and development of the STC Paton in the field of electric arc welding and surfacing with powder wire (Review). Avtomaticheskaya svarka. 2010, no. 12 (692), pp. 34–42. (In Russ.).

5. Sahoo A., Tripathy S. Development in plasma arc welding process: A review. Materials. Today: Proceedings. 2021, vol. 41, no. 2, pp. 363–368. https://doi.org/10.1016/j.matpr. 2020.09.562

6. Ramkumar P., Karthikeyan M.K., Gupta R.K., Anil Kumar V., Magadum Ch., Muthupandi V. Plasma arc welding of high strength 0.3 % C–CrMoV (ESR) Steel. Transactions of the Indian Institute of Metals. 2017, vol. 70, no. 5, pp. 1317–1322. https://doi.org/10.1007/s12666-016-0927-3

7. Fatima S., Khan M., Jaffery S.H.I., Ali L., Butt S.I., Mujahid M. Optimization of process parameters for plasma arc welding of austenitic stainless steel (304 L) with low carbon steel (A-36) // Proceedings of the Institution of Mechanical Engineers, Part L. Journal of Materials: Design and Applications. 2016, vol. 230, no. 2, pp. 640–653. https://doi.org/ 10.1177/1464420715584392

8. Wu C.S., Wang L., Ren W.J., Zhang X.Y. Plasma arc welding: Process, sensing, control and modeling. Journal of Manufacturing Processes. 2014, vol. 16, no. 1, pp. 74–85. https://doi.org/10.1016/j.jmapro.2013.06.004

9. Wang Yu., Mao B., Chu Sh., Chen S., Xing H., Zhao H., Wang Sh., Wang Yu., Zhang J., Sun B. Advanced manufacturing of high-speed steels: A critical review of the process design, microstructural evolution, and engineering performance. Journal of Materials Research and Technology. 2023, vol. 24, pp. 8198–8240. https://doi.org/10.1016/j.jmrt.2023.04.269

10. Wang H., Hong D., Hou L., Ou P., Wang Z., Shen L., Zhao H. Influence of tempering temperatures on the microstructure, secondary carbides and mechanical properties of spray-deposited AISI M3:2 high-speed steel. Materials Chemistry and Physics. 2020, vol. 255, article 123554. https://doi.org/10.1016/j. matchemphys.2020.123554

11. Lyu C., Zhou J., Zhang X., Yao Y., Zhang Y. Effect of heat treatment on microstructure and impact toughness of a Tungsten-Molybdenum powder metallurgical high-speed steel. Materials Science and Engineering: A. 2021, vol. 815, article 141268. https://doi.org/ 10.1016/j.msea.2021.141268

12. Wang Y., Chu S., Mao B., Xing H., Zhang J., Sun B. Microstructure, residual stress, and mechanical property evolution of a spray-formed vanadium-modified high-speed steel processed by post-heat treatment. Journal of Materials Research and Technology. 2022, vol. 18, pp. 1521–1533. https://doi.org/10.1016/j. jmrt.2022.03.053

13. Chaus A.S., Sahul M. On origin of delta eutectoid carbide in M2 high-speed steel and its behaviour at high temperature. Materials Letters. 2019, vol. 256, article 126605. https://doi.org/10.1016/j.matlet.2019.126605

14. Chaus A.S., Braeík M., Sahul M., Do-mankova M. Microstructure and properties of M2 high-speed steel cast by the gravity and vacuum investment casting. Vacuum. 2019, vol. 162, pp. 183–198 https://doi.org/10.1016/ j.vacuum.2019.01.041

15. Chen N., Luo R., Xiong H., Li Z. Dense M2 high speed steel containing core-shell MC carbonitrides using high-energy ball milled M2/VN composite powders. Materials Science and Engineering: A. 2020, vol. 771, article 138628. https://doi.org/10.1016/j.msea. 2019.138628

16. Yu P., Ziqiang P., Bowen L., Wei X., Ce Zh., Xuanhui Q., Xin L. Influence of heat treatment on the microstructural evolution and mechanical properties of W6Mo5Cr4V2Co5Nb (825 K) high speed steel. Materials Science and Engineering: A. 2020, vol. 787, article 139480. https://doi.org/10.1016/j.msea.2020.139480

17. Hu Q., Wang M., Chen Yu., Liu H., Si Z. The Effect of MC-type carbides on the microstructure and wear behavior of s390 high-speed steel produced via spark plasma sintering. Metals. 2022, vol. 12, no. 12, article 2168. https://doi.org/10.3390/met12122168

18. Wang J., Chen C., Zhang C. Effect of Mo and tempering treatment on the microstructural evolution and mechanical properties of M2 high-speed steel prepared by laser directed energy deposition. Steel research international. 2021, vol. 92, article 2100225. https://doi.org/10.1002/srin.202100225

19. Ureña A., Otero E., Utrilla M.V., Múnez C.J. Weldability of a 2205 duplex stainless steel using plasma arc welding. Journal of Materials Processing Technology. 2007, vol. 182, no. 1-3, pp. 624 – 631. https://doi.org/10.1016 /j.jmatprotec.2006.08.030

20. Korshunov L.G., Goykhenberg Yu.N., Cher-nenko N.L. Effect of silicon on the structure, tribological and mechanical properties of nitrogen-containing chromium-manganese austenitic steels. Physics of metals and metal science. 2003, vol. 96, no. 5, pp. 100–110.

21. Vdovin K.N., Nikitenko O.A., Feoktistov N.A., Gorlenko D.A. Research of the effect of nitrided ferrovanadium on the microstructure parameters of Gadfield steel cast products. Liteishchik Rossii. 2018, no. 3, pp. 23–27. (In Russ.).

22. Emelyushin A.N., Petrochenko E. V., Nefed'ev S. P. Research of structure and impact-abrasive wear resistance of coatings of Fe-C-Cr-Mn-Si system, additionally doped with nitrogen. Svarochnoe proizvodstvo. 2011, no. 10, pp. 18–22. (In Russ.).

23. Nefed'ev S.P., Emelyushin A.N. The in-fluence of nitrogen on the formation of the structure and properties of plasma coatings of type 10Р6М5. Bulletin of the Yugra State University. 2021, no. 3(62), pp. 33–45. https://doi.org/10.17816/byusu20210333-45 (In Russ.).

24. Emelyushin A.N., Petrochenko E. V., Nefed'ev S. P. Comparison of structure and properties of cast and deposited wear-resistant materials. Liteinye protsessy. 2012, no. 11, pp. 141–145. (In Russ.).

25. Malushin N.N., Gromov V.E., Romanov D.A., Bashchenko L.P., Peregudov O.A. Strengthening heat-resistant alloys with plasma in nitrogen medium. Novokuznetsk: OOO Poligrafist, 2022, 232 p. (In Russ.).

26. Malushin N.N., Romanov D.A., Osetkovskii V.L., Kovalev A.P., Budovskikh E.A., Valuev D.V. Method of multilayer weld deposition with heat-resistant steels of high hardness in nitrogen-containing medium. Pat.RF2699488. Byulleten' izobretenii. 2019, no. 25. (In Russ.).

27. Geller Yu.A. Instrumental steels. Moscow: Metallurgiya. 1983, 527 p. (In Russ.).