Moscow Polytechnic University (Moscow, Russia)

R. L. Shatalov, Dr. Eng., Prof., Dept. of Metal Forming and Additive Technologies, e-mail: mmomd@mail.ru

“Pribor” scientific and production union, Bogorodsky affiliate (Noginsk, Russia):
V. A. Medvedev, Technologist, e-mail: 10-bmt@mail.ru
E. E. Zagoskin, Head of Thermal Section, e-mail: ee286@yandex.ru

The basic mechanical properties of deformed thin-walled smallsized vessels of steel 50 in the rolling-pressing line (RPL) of the Scientific-Production Association Pribor have been studied. The quality indicators, hardness, microstructure and chemical composition of steel 50 of initial workpieces from hot-rolled rods that influence the accuracy of the experiment were determined and evaluated. Analysis of the processing modes of the workpieces in the production line consisting of a heating furnace, helical rolling mill, press and quenching unit made it possible to establish a significant effect of temperature on formation of mechanical properties. It was established that quenching from a temperature of 840 °C from the single-phase region of austenite results in the following average values: σ_0.2 — 652 MPa, σ_в — 975 MPa, δ — 18%, 287 НВ. With decreasing in temperature by 100 °C, when quenching is carried out from a temperature of 740 °C from the two-phase region of austenite and ferrite, the ductility of the metal δ increases to 22%, and the remaining indicators of properties decrease by 25–30% (σ_0.2 — 496 MPa, σ_в — 728 MPa, 215 HB). Dependencies between yield strength, temporary tensile strength, elongation and hardness were determined. Regression equations with a fairly high correlation coefficient (R₂ ≈ 0.9) were constructed to determine the mechanical properties of finishing steel vessels according to their hardness at the exit of the rolling-press line. The dependencies obtained allow using non-destructive hardness control methods to determine the main indicators of the mechanical properties of thin-walled vessels made of steel 50.

1. Romantsev B. А., Goncharuk А. V., Aleshenko А. S.et. al. Improvement of hot rolling modes at the 70-270 tube rolling mini-mill. Metallurg. 2015. No. 5. pp. 41–43.
2. Merkulov D. V., Toporov V. А., Chepurin М. V. Features of piercing conditions for continuously cast billets. Chernye Metally. 2013. No. 1. pp. 18–24.
3. Vydrin А. V. Development of the technologies of hot rolling of seamless tubes. Chernye Metally. 2012. No. 9. pp. 16–20.
4. Gorlova А. А., Rodinkov S. V. 280 small-section rolling mill of VNIIMETMASh design. Chernye Metally. 2008. No. 1. pp. 14–18.
5. Galkin S. P., Romantsev B. А., Dinh Xuan Та, Gamin Yu. V. Resourcesaving technology for production of round bars from used shafts of rolling railroad stock. Chernye Metally. 2018. No. 4. pp. 2–6.
6. GOST 1050-2013. Metal products from non-alloyed structural quality and special steels. General specification.
7. Filippov А. А., Pachurin G. V., Kuzmin N. А., Matveev Yu. I. The method of forming the structural and mechanical properties of rolled steel for heading of core products. Chernye Metally. 2018. No. 4. pp. 36–40.
8. Brovman M. Ya. On the resistance of plastic deformation in the processes of rolling and continuous casting of metals. Metally. 2004. No. 3. pp. 24–33.
9. Goli-Ogly Е. А., Efron L. I., Morozov Yu. D. Effect of deformation modes at the main stages of controlled rolling on the microstructure of tubular steel. Metallovedenie i termicheskaya obrabotka metallov. 2013. No. 6. pp. 9–13.
10. Tretyakov А. V., Zyuzin V. I. Mechanical properties of metals and alloys during forming. Moscow: Metallurgiya, 1973. 224 p.
11. Mochalov N. А., Galkin А. М., Mochalov S. N., Parfenov D. Yu. Plastometric studies of metals. Moscow: Intermet inzhiniring, 2003. 318 p.
12. Markovets М. P. Determination of mechanical properties of metals by hardness. Moscow: Mashinostroenie, 1979. 192 p.
13. Shatalov R. L., Lukash А. S., Ziselman V. L. Defi nition of mechanical properties of copper and brass strips on indices of hardness factors in the time of cold rolling. Tsvetnye Metally. 2014. No. 5. pp. 61–65.
14. GOST 9012–59. Metals. Method of Brinell hardness measurement. Introduced: 01.01.1960.
15. GOST 18895–97. Steel. Method of photoelectric spectral analysis. Introduced: 01.01.1998.
16. Kobzar А. I. Applied Mathematical Statistics: for engineers and scientists. Moscow: Fizmatlit, 2012. 816 p.