USING CHEMICAL THERMAL TREATMENT OF STRENGTHENING PIPES FOR PRODUCTION STAINLESS PIPES

Keywords: needle-mandrel, matrix ring, rollers, support laths, pressing, cold rolling, heat treatment, carbonitrating, ionic nitriding, hardening , tempering, hardening

Abstract

Purpose. The aim of the research is to use modern types of chemical-heat treatment to strengthen the pipe tools for the production of stainless steel pipes - pipe press tool (needle-mandrels and die rings) and the tools for cold rolling of thin-walled pipes - supporting bars and rollers.
Methods. For the study were made: needles-mandrels of a pipe-profile press with a force of 16 MN in the amount of 3 (three) pieces of steel – 4KH5MF1S with a diameter of 50 mm and a length of 1300 mm and subjected to hardening heat treatment  (step hardening from 1050 – 1070°С and double tempering at 550 – 570° (1 tempering) and 530 – 550°С (2 temperings) in shop conditions;  matrix rings of a pipe-profile press with a force of 16 MN in number of 10 (ten) pieces: from steel 5KH3V3MFS (DI-23): 6 (six) pieces (1 piece with a diameter of 63.5 mm, 2 pieces with a diameter of 73.5 mm, 3 pieces with a diameter 71.5 mm); made of steel 4KH5MF1S 4 (four) pieces with a diameter of 71.5 mm and 73.5 mm and subjected to hardening heat treatment (step hardening from 1080 – 1100°С and double tempering at 550 – 570°С (1 tempering) and 530 – 550° C (2 temperings) in the shop;  rollers of the HPTR mill in the amount of 3 (three) pieces of steel 4KH5MF1S instead of steel 60S2KHFA 65 mm wide under the diameter of the pipe 16 mm and subjected to hardening heat treatment (step hardening with 1070 – 1080°С and double tempering at 550 – 570 °С(1 tempering) and 530 – 550°С (2 temperings) in shop conditions;  6 (six) support bars 210 mm long, 80 mm wide and 47.42 mm high and track widths 25 mm and 20 mm (under a pipe with a diameter of 15 – 22 mm and 23 – 30 mm, respectively) made of steel 4KH5MF1S instead of steel 60S2KHFA and subjected to hardening heat treatment (step hardening with 1080 – 1100°С and double tempering at 550 – 570 °С (1 tempering) and 530 – 550 °С (2 temperings) in shop conditions. For the study, also from forgings with a diameter of 250 mm were cut witness samples with a size of 20×20×20 mm and subjected to a similar heat treatment to experimental samples of the tool. The most reliable assessment of the results of saturation with nitrogen and carbonitrating give metallographic studies, which provide information about the thickness and structure of the layer of compounds and the diffusion layer. Electronic studies of metallographic sections (original sections were cut into thin samples of 5 mm), prepared and studied on a scanning electron microscope (SEM), high resolution (up to 60 A) and exceptional depth of field which make it almost indispensable for metallographic research. Measurement of the surface hardness of the samples after saturation with nitrogen and carbonitrating was performed using a microhardness tester (microscope) – type PMT-3 at a load of 100gs HV0,1.
Results. Diagrams of microhardness of samples are constructed and investigated, the optimum mode of ionic saturation with nitrogen and carbonitrating (that is confirmed by results of measurements of hardness) for reception of high operational properties of the pipe press and pipe-rolling tools and reception of necessary point of grain is investigated by studies of structure nitriding and carbonated layer (microstructural and electronic).
The result is the development of optimal modes of heat strengthening of the pipe tools, which increases the strength, wearing and heat resistance of steel by forming stable carbides, nitrides, carbonitrides, etc in the process of heating. As a result, steel acquires high surface hardness HV0,1 1100 – 1150, that does not change at heating to 600 – 650 °C, high resistance to wearing, high limits of endurance, corrosion resistance.
Originality. For the first time scientifically proven more efficient mode of thermal strengthening of pipe tools (with conducting microstructural studies, which allows it to be used in real conditions of the production stainless pipes at pipe plants «Centravis Production Ukraine Joint-Stock Company», «PA Oskar» etc.
Practical implications. Improving the technology of heat treatment of pipe tools (tempering with tempering and subsequent ionic nitriding or carbonitriding instead of the usual technology – tempering with tempering) will increase the stability of the tool by 25 – 30 % and reduce processing costs of stainless pipes, as well as improve the surface quality of pipes absence of films, cuts and other defects of corrosion-proof pipes).

References

Kargin, V. R., Kargin, B. V. (2014). Theory and technology of pressing, rolling and drawing. Samara: SSAU Publis.hing House

Sherba, V. N., Reitberg, L. H. (1995) Metal pressing technology. Moskva: Metallurgiia

Lezinskaya, E. Ya., Bildin, K. M. et al. (2019). Collection of lectures on the technology of production of stainless steel pipes. Centravis

Alexandrov, V. A., Bogdanov, K. V.(2005) Nitriding of tools from high-chromium and high-speed steels. Strengthening technologies and coatings, (5), 14-20

Arzamasov, B. N., Bratukhin, A. G., Eliseev, Y. S., Panayoti, T. A. (1999) Ionic chemical-thermal treatment of alloys in gaseous media. M.: Izd. MGTU im. N.E. Bauman

Chechulin, Yu. B. (2017). Cold rolling of pipes. Moskva: Metallurgiia

Andreev, A. A., Sablev, L. P., Shulaev, V. M., Grigorev, S. N. (2005). Vacuum arc devices and coatings. Kharkiv: NSC KIPT

Sablev, L. P., Lomino, N. S., Stupa, R. I., Andreev, A. A., Chikryzhov, A. M. (2005). Two-stage vacuum-arc discharge: characteristics and methods of creation. Kharkiv

Oborudovanie i tekhnologii termicheskoi obrabotki metallov i splavov. (2007). Patent 79773 Ukraine. MPK S23S.

Lomino, N. S., Ovcharenko, V. D., Poliakova, G. N., Andreev, А. А., Shulaev, B. M. (2002). The interelectrode plasma of a vacuum arc in a nitrogen atmosphere. Kharkiv

Budilov, V. V., Kireev, R. M., Ramazanov, K. N., Vafin, R. K. (2009). U.S. Patent No. 2418095, IPC - 8 С23С8/36, С21D9 The method of vacuum ion-plasma nitriding of steel products

Lakhtin, Yu. M. (1993). The current state of the nitriding process. Metallurgy and heat treatment of metals

Chatterjee-Fisher, R. (1990). Nitriding and carbonitriding: Moskva: Metallurgiia

Mogilenets, M. V. (2018). Karnonitratsiya v rasplavesoley (Carbonitration in salt melt), International information and technical journal “Equipment and tools for professionals”

Prokoshkin, D. A., Supov, A. V., Koshenkov, V. N., Bogomolov, A. M. (1981). Metallurgy and heat treatment, (4)

Smolnikov, E. A. (1989). Thermal and chemical-thermal treatment of tools in salt baths: Moskva: Mashinostoroenie

Koshenkov, V. N. (2015). Complex Chemical-term. Processing Features Steels: Science Rise

Orlov, G. A. (2011). Cold rolling and drawing of pipes: uch.pos. Ekaterinburg: URFU

Tselikov, N. A. (2010). Cold rolling mills of VNIIMETMASH pipes. Heavy engineering

Penkov, N. S. et al. (2009). U.S. Patent No. 2397033 RF. Cold rolling mill pipes

Kosmatsky, Ya. I. (2017). Research of the process of wear of the pipe press tool and development of the technical decisions directed not increase of its operational resource. Chelyabinsk

Bolshakov, V. I. (2010). Equipment of thermal shops, technologies of heat treatment of metal products: Dnepropetrovsk

Vyshinsky, V. T. (2011). Directions and tasks of improvement of cold rolling mills by rollers : Bulletin of SevNTU

Verdenevsky, V. A. (1992.) Roller mills of cold rolling of pipes: Moskva: Metallurgiia

Published
2020-12-30
How to Cite
Stolbovoy, V., Mogilenets, M., Dumenko, K., Krivchik, L., Khokhlova, T., & Pinchuk, V. (2020). USING CHEMICAL THERMAL TREATMENT OF STRENGTHENING PIPES FOR PRODUCTION STAINLESS PIPES. Metallurgical and Ore Mining Industry, (4), 52-71. https://doi.org/10.34185/0543-5749.2020-4-52-71