Investigation of the Features of the Formation of Diffusion Layers During Nitrocementation of High-Chromium Steels in a Carbon Black Medium

The purpose of the work is to establish the regularities of the formation of the structure and phase composition of surface (modified) layers on 20X13 chromium stainless steel under intense saturation with carbon and nitrogen and, on this basis, to substantiate the possibility of surface hardening of parts made of high-chromium steels by nitrocementation.

Methods. The studies were carried out on samples made of high–chromium steel 20X13, which were subjected to high-temperature nitrocementation in a paste-like medium including fine soot, sodium carbonate and potassium ferruginous oxide (paste-forming agent is an aqueous solution of carbomethylcellulose). The microstructure was studied using an optical metallographic microscope OLIMPUS OX 51 and a scanning electron microscope Qanta FEG-650 with an X-ray microanalysis system EDAX. The microhardness was determined on the Duramit-5 microhardometer, the phase composition on the XRD-7000S X-ray diffractometer.

Results. Nitrocementation of high chromium steel 20X13 in the temperature range of 820–950°C provides the formation of diffusion layers on the surface, the structure of which is represented by three zones: a crust of solid carbonitrides on the surface, an eutectoid zone with a solid matrix and inclusions of carbonitrides under the crust and a transition zone including a solid solution enriched in carbon and nitrogen with grains of the base metal. The microhardness of the nitrocemented layers on 20X13 steel after quenching from 1050°C in oil and tempering at 600°C reaches Nm 750–800 on the surface and decreases smoothly enough in depth of the nitrocemented layer. The depth of nitrocemented layers with increased microhardness (more than 400 Nm), depending on the duration of treatment, can reach ~ 0.5 (860°C, 6 hours).

Conclusion. Nitrocementation of high-chromium steel 20X13 at 820–880°C in an active carbon black paste with the addition of potassium ferrocarbon leads to an increase in the hardness of the surface layers by about 4 times the hardness of the base, which, combined with the high mechanical properties of the base, will significantly increase the service life of parts made of high-chromium stainless steels of type X13 operating under high contact conditions loads.

1. Brigov A. M., Igumnov L. A., Kaidalov V. B., Konstantinov A. Yu., Lapshin D. A., Lomunov A. K., Mitenkov F. I. Eksperimental'noe issledovanie i matematicheskoe modelirovanie povedeniya stalei marok St3, 20Kh13 i 08Kh18N10T v shirokikh diapazonakh skorostei diformatsii i temperaturakh [Experimental research and mathematical modeling of the behavior of steels of grades St3, 20X13 and 08X18H10T in wide ranges of deformation rates and temperatures]. Prikladnaya mekhanika i tekhnicheskaya fizika = Applied Mechanics and technical physics, 2015, vol. 56, no. 6, pp. 51–57.

2. Ivashko V. V. Issledovanie vliyaniya rezhimov nagreva na strukturu i svoistva nerzhaveyushchei stali 20Kh13 [Investigation of the influence of heating modes on the structure and properties of stainless steel 20X13]. Vestnik BarGU. Seriya: Tekhnicheskie nauki = BARSU Herald. Series Enginering, 2015, no. 3, pp. 45–48.

3. Metallovedenie. T. 2. Termicheskaya obrabotka. Splavy [Metal science. Vol. 2. Heat treatment. Alloys]; ed. by V. S. Zolotorevsky. Moscow, MISiS Publ., 2014. 528 p.

4. Kostin N. A., Trusova E. V. Protsess karbonitrirovaniya instrumental'noi stali v aktivnoi pastoobraznoi srede [The process of carbonitrization of tool steel in an active paste-like medium]. Metallurgiya mashinostroeniya = Metallurgy of mechanical engineering, 2014, no. 2, pp. 43–45.

5. Kapsalamova F. R., Krasikov S. A., Terlikbaeva A. J., Zhilina E. M., Alimzhanova A. M. Termokhimicheskoe issledovanie obrazovaniya silitsidov, boridov, karbidov v splave Fe-Ni-Cr-Cu-Si-B-C [Thermochemical study of the formation of silicides, borides, carbides in Fe-Ni-Cr-Cu alloy-Si-B-C]. Rasplavy = Melts, 2023, no. 4, pp. 414–425.

6. Volkhonsky A. O., Blinkov I. V., Levinsky Yu. V., Skryleva E. A. Otsenka termicheskoi stabil'nosti mnogosloinykh nanostrukturnykh pokrytii na osnove analiza diffuzionnoi podvizhnosti komponentov sloev [Assessment of the thermal stability of multilayer nanostructured coatings based on the analysis of the diffusion mobility of layer components]. Izvestiya vysshikh uchebnykh zavedenii. Poroshkovaya metallurgiya i funktsional'nye pokrytiya = Proceedings of higher educational institutions. Powder metallurgy and functional coatings, 2016, no. 4, pp. 86–93.

7. Steel and its heat treatment; ed. by T. Holm, P. Olsson, E. Troell. Molndal, Swerea IVF, 2012. 712 p.

8. Steel Heat Treatment Handbook; ed. by G. E. Totten, M. A. H. Howes. Second ed. CRC Press, 2006. 1208 р.

9. Metallovedenie. T. 1. Osnovy metallovedeniya [Metal science. Vol. 1. Fundamentals of Metal Science]; ed. by V. S. Zolotarevsky. Moscow, MISIS Publ., 2014. 496 p.

10. Gerasimov S. A., Lapteva V. G., Kuksenova L. I., Gerasimov S. A. Struktura i iznosostoikost' azotirovannykh konstruktsionnykh stalei i splavov [Structure and wear resistance of nitrided structural steels and alloys]. Moscow, Bauman Moscow State Technical University, 2014. 520 p.

11. Kostin N. A., Kolmykov V. I., Trusova E. V., Kostin N. N. Naplavka shtampovykh instrumentov s posleduyushchei nitrotsementatsiei dlya ikh effektivnoi restavratsii [Surfacing of die tools with subsequent nitrocementation for their effective restoration]. Chernye metally = Ferrous metals, 2022, no. 2, pp. 56–61.

12. Tsai K. V., Maksimkin O. P., Gusev M. N., eds. Osobennosti formirovaniya mikrostruktury pri plasticheskoi deformatsii v obluchennoi neitronami nerzhaveyushchei stali 12Kh18N10T [Features of microstructure formation during plastic deformation in neutron-irradiated stainless steel 12X18H10T]. Vestnik NYaTs RK = NNC RK Bulletin, 2009, is. 4, pp. 77–85.

13. Kolomiytsev E. V. Korrozionno-ustalostnaya prochnost' tavrovykh soedinenii stali 12Kh18N10T i metody ee povysheniya [Corrosion and fatigue strength of 12X18H10T steel T-bar joints and methods of its improvement]. Avtomaticheskaya svarka = Automatic welding, 2012, no. 12, pp. 41–43.

14. Abdul Kareem F. Hassan, Qahtan Adnan Jawad. Estimation of austenitizing and multiple tempering temperatures from the mechanical properties of AISI 410 using artificial neural network. International Journal of Engineering & Technology, 2018, vol. 7(4.19), pp. 778–787. https://doi.org/10.14419/ijet.v7i4.19.27997

15. Grinberg E. M., Goncharov S. S., Mova D. A., Kondaurova E. Yu., Surovtseva E. A. Vliyanie skorosti okhlazhdeniya pri zakalke na strukturu i tverdost' stalei tipa X13 s razlichnym soderzhaniem ugleroda [The effect of the cooling rate during quenching on the structure and hardness of X13 type steels with different carbon content]. Izvestiya Tul'skogo gosudarstvennogo universiteta. Tekhnicheskie nauki = Isvestiya Tula State University, 2009, no. 3, pp. 296–306.

16. Smirnov A. E. Optimizatsiya tekhnologicheskikh faktorov vakuumnoi nitrotsementatsii kompleksno-legirovannykh stalei martensitnogo klassa [Optimization of technological factors of vacuum nitrocarburization of complex alloyed martensitic steels]. Problemy chernoi metallurgii i materialovedeniya = Problems of ferrous metallurgy and materials science, 2019, no. 2, pp. 13–19. EDN THICRG

17. Vrzhasch E. E. Matematicheskaya optimizatsiya eksperimenta pri poluchenii kachestvennogo diffuzionnogo sloya pri nitrotsementatsii stali v elektrostaticheskom pole [Mathematical optimization of the experiment in obtaining a high-quality diffusion layer during nitrocarburization of steel in an electrostatic field]. Pridneprovskii nauchnyi vestnik = Pridneprovsky Scientific Bulletin, 2019, vol. 9, no. 3, pp. 60–64. EDN ADUWTF

18. Popova N. A., Nikonenko E. L., Erbolatova G. U., Nikonenko A. V. Vliyanie elektrolitnoplazmennoi nitrotsementatsii na fazovyi sostav splava 40KhNYu [Influence of electrolyte-plasma nitrocarburization on the phase composition of alloy 40ХНУУ]. Vestnik Permskogo natsional'nogo issledovatel'skogo politekhnicheskogo universiteta. Mashinostroenie, materialovedenie = Bulletin of the Perm National Research Polytechnic University . Mechanical engineering, materials science, 2019, vol. 21, no. 3, pp. 24–32. https://doi.org/10.15593/2224-9877/2019.3.03. EDN HWJPHC

19. Grashkov S. A., Kolmykov V. I. Povyshenie iznosostoikosti stali KhVG dlya detalei toplivnoi apparatury dizelei metodom nitrotsementatsii [Increasing the wear resistance of HVG steel for parts of diesel fuel equipment using the method of nitrocarburization]. Izvestiya Yugo-Zapadnogo gosudarstvennogo universiteta. Seriya: Tekhnika i tekhnologii = Proceedings of the Southwest State University. Series: Engineering and Technology, 2020, vol. 10, no. 1, pp. 43–56. EDN TNHSOE

20. Popova N. A., Nikonenko E. L., Nikonenko A. V., eds. Vliyanie elektrolitno-plazmennoi nitrotsementatsii na strukturno-fazovoe sostoyanie stalei ferrito-perlitnogo klassa [The influence of electrolyte-plasma nitrocarburization on the structural-phase state of steels of the ferrite-pearlite class]. Izvestiya vysshikh uchebnykh zavedenii. Chernaya metallurgiya = News of higher educational institutions. Ferrous metallurgy, 2019, vol. 62, no. 10, pp. 782–789. https://doi.org/10.17073/0368-0797-2019-10-782-789. EDN IOXGNG.