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Rolling and other metal forming processes
ArticleName Determination of mechanical properties of steel thin-walled vessels by hardness after hot screw rolling with subsequent stamping and quenching
ArticleAuthor R. L. Shatalov, V. A. Medvedev, E. E. Zagoskin
ArticleAuthorData

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

Abstract

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: σ0.2 — 652 MPa, σв — 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% (σ0.2 — 496 MPa, σв — 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.

keywords Rolling-pressing line, hot screw rolling, die forging, oil hardening, mechanical properties, hardness, thin-walled vessel, steel 50
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