Increasing efficiency of plasma hardening by local cooling of surface by air with negative temperature
DOI:
https://doi.org/10.15587/1729-4061.2019.176825Keywords:
carbon content, martensitic interval, cooling temperature, hypoeutectoid steel, eutectoid steel, hypereutectoid steelAbstract
The martensitic transformation interval of some hypoeutectoid, all eutectoid and all hypereutectoid steels covers to a large extent the region of negative temperatures. Due to the fact that the plasma hardening operation is carried out in workshops where the minimum temperature is +20 °С, the surface temperature of the part after plasma heating cannot reach negative values. Because of this, the temperature range of the martensitic transformation is not fully used and in the hardened structure there is a certain amount of austenite, which has not undergone martensitic transformation. This circumstance reduces the hardness of the hardened layer and often low tempering is required to convert residual austenite to tempered martensite, which lengthens and makes the heat treatment more expensive. Complete or almost complete martensitic transformation is possible if the surface heated by the plasma beam is immediately cooled to a negative temperature.
It is shown that local cooling of the hardened surface to a temperature of –40 °C can be carried out by air using the Ranque-Hilsch tube, which significantly expands the possibilities of full hardening for eutectoid and hypereutectoid steels. The studies consisted in heating the surface with a plasma stream to a temperature of 750 °C and 900 °C. The temperature was changed by the plasma torch current and by changing the velocity of the plasma flow spot moving along the sample surface. The experiments were carried out on steels 45 (0.45 % C), U8 (0.8 % C) and U10 (1 % C). The study of the structures was carried out on a MIM-7 microscope with a video camera and with the image displayed on the screen. The approximate quantitative composition of austenite, martensite, and associated structures was determined by the areas on the screen.
During plasma hardening of steel 45 from a temperature of 900 °C using the Ranque-Hilsch tube, there is practically no residual austenite in the structure. When hardening U8 steel, residual austenite is detected in a small amount. When hardening U10 steel, the amount of residual austenite is approximately 15 %. Local surface cooling allows high-quality hardening of steels of most grades, regardless of the carbon content.References
- Lashchenko, G. I. (2003). Plazmennoe uprochnenie i napylenie. Kyiv: Ekotehnologiya, 64.
- Gulyaev, A. P. (2010). Materialovedenie. Moscow: Avangard.
- Yan, M. F., Chen, B. F., Li, B. (2018). Microstructure and mechanical properties from an attractive combination of plasma nitriding and secondary hardening of M50 steel. Applied Surface Science, 455, 1–7. doi: https://doi.org/10.1016/j.apsusc.2018.04.213
- Xiang, Y., Yu, D., Li, Q., Peng, H., Cao, X., Yao, J. (2015). Effects of thermal plasma jet heat flux characteristics on surface hardening. Journal of Materials Processing Technology, 226, 238–246. doi: https://doi.org/10.1016/j.jmatprotec.2015.07.022
- Martynov, V., Brzhozovsky, B., Zinina, E., Yankin, I., Susskiy, A. (2017). Fluctuations in the Process Plant as a Quality Assessment Criterion of Low-temperature Plasma Hardening Process. Procedia Engineering, 176, 451–460. doi: https://doi.org/10.1016/j.proeng.2017.02.344
- Semboshi, S., Iwase, A., Takasugi, T. (2015). Surface hardening of age-hardenable Cu–Ti alloy by plasma carburization. Surface and Coatings Technology, 283, 262–267. doi: https://doi.org/10.1016/j.surfcoat.2015.11.003
- Lebrun, J. P. (2015). Plasma-assisted processes for surface hardening of stainless steel. Thermochemical Surface Engineering of Steels, 615–632. doi: https://doi.org/10.1533/9780857096524.4.615
- Esfandiari, M., Dong, H. (2006). Plasma surface engineering of precipitation hardening stainless steels. Surface Engineering, 22 (2), 86–92. doi: https://doi.org/10.1179/174329406x98368
- Xiang, Y., Yu, D., Cao, X., Liu, Y., Yao, J. (2017). Effects of thermal plasma surface hardening on wear and damage properties of rail steel. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 232 (7), 787–796. doi: https://doi.org/10.1177/1350650117729073
- Safonov, E. N., Mironova, M. V. (2018). Plasma hardening hypereutectoid steel. IOP Conference Series: Materials Science and Engineering, 411, 012069. doi: https://doi.org/10.1088/1757-899x/411/1/012069
- Petrov, S. V., Saakov, A. G. (2002). Technology and equipment for plasma surface hardening of heavy-duty parts. Materials and Manufacturing Processes, 17 (3), 363–378. doi: https://doi.org/10.1081/amp-120005382
- Nechaev, V. P., Ryazantsev, A. A. (2012). Issledovanie, razrabotka, obosnovanie vozmozhnostey povysheniya nadezhnosti raboty krupnomodul'nyh shesteren putem plazmennogo uprochneniya ih poverhnostey. Prohresyvni tekhnolohiyi i systemy mashynobuduvannia, 43, 227–232.
- Horobryh, M. A., Klement'ev, V. A. (2012). Vihrevoy ehffekt Ranka-Hilsha. Vihrevaya truba. Molodoy ucheniy, 6, 54–55.
- Korkodinov, I. A., Khurmatullin, O. G. (2012). The Application of Ranque – Hilsh Effect. Vestnik permskogo natsional'nogo issledovatel'skogo politehnicheskogo universiteta. Mashinostroenie, materialovedenie, 14 (4), 42–54.
- Metodika prigotovleniya mikroshlifa. Available at: https://infourok.ru/laboratornaya-rabota-metodika-prigotovleniya-mikroshli-fa-852852.html
- Mikroskop MIM-7 metallograficheskiy. Available at: https://svetlovodsk.flagma.ua/mikroskop-mim-7-metallograficheskiy-o4107365.html
- Pribor dlya izmereniya tverdosti po metodu Rokvella TR 5006M. Available at: http://ukrsk.com.ua/pribor_tr_5006m.html
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Copyright (c) 2019 Alla Bespalova, Vladimir Lebedev, Olga Frolenkova, Alexey Knysh, Olga Dashkovskaya, Oksana Fayzulina
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