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Metallology and metallography
ArticleName Investigation of the formation of service properties of parts made from forgings of microalloyed steels after controlled cooling from stamping temperatures
DOI 10.17580/chm.2022.07.11
ArticleAuthor V. G. Shibakov, D. L. Pankratov, A. M. Valiev, R. V. Shibakov

Naberezhnye Chelny Institute (branch) of Kazan Federal University, Naberezhnye Chelny, Russia:

V. G. Shibakov, Dr. Eng., Prof., Head of the Dept. of Mechanical Engineering, e-mail:
D. L. Pankratov, Dr. Eng., Director of the Higher Engineering School, e-mail:
A. M. Valiev, Cand. Eng., Associate Prof., Dept. of Mechanical Engineering, e-mail:
R. V. Shibakov, Cand. Eng., Associate Prof., Dept. of Mechanical Engineering


The use of microalloyed dispersion-hardening steels allows not only to save expensive alloying elements, but also leads to significant energy savings due to the possibility of using controlled cooling of steel semi-finished products directly after hot forming. The purpose of the research carried out in this work was to determine the rational modes of controlled cooling of forgings made of dispersion-hardening steels that provide the properties and microstructure required by the standard. For this purpose, a simulation simulation of the cooling of the forgings of the connecting rod of the KAMAZ car engine with the temperatures of the stamping end in various media (compressed air, water-air mixture, water, oil) was carried out, which made it possible to determine the composition of the medium (ratio) of water and air in the water-air environment and its supply modes providing cooling of forgings with speeds above critical, that is, without the formation of a ferritic mesh along grain boundaries during the decay of austenite. Subsequently, these modes were reproduced in laboratory and experimental-industrial conditions with the determination of the mechanical properties and microstructure of the steel of the connecting rod forgings. For 38MnVS6 steel, it has been established that controlled cooling from the stamping end temperatures not lower than 950 °C and the cooling rate not lower than 10 °C/sec, the properties and microstructure of forgings meet the requirements of the standard for connecting rods. This makes it possible to abandon the energy-intensive heat treatment (thermal improvement) of forgings provided for by the production technology.

keywords Economically microalloyed steels, controlled cooling of forgings, connecting rod, modeling, temperature fields, mechanical properties, microstructure

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