The increasement of the properties of structural low–carbon steel 10G2FB after deformation in the intercritical temperature interval and the accelerated cooling
Problem definition. With an increase of construction rate the necessity of mechanical properties of structural steel improvement has arised. The development of new modes of rolling can solve the problem of increasement the properties of structural low–carbon steels.
Purpose: to increase the properties of sheet metal by determining the effect of deformation in the intercritical interval (ICI) temperatures and subsequent cooling on the structure and properties of structural low–carbon low alloy steel.
Analysis of recent research: a lot of scientific works of the previous years were dedicated to the increasement the properties of structural steel. Application of thermomechanical or controlled rolling enhances the strength characteristics of steel, but the lowers toughness. Thus, it is necessary to increase not only the strength, but also toughness of structural steel.
Results: Deformation at different temperatures of the intercritical interval was carried out followed by cooling in oil. As a result it was established that, such treatment at, the top and bottom of the intercritical interval increases the strength, but the toughness is reduced.
The embrittlement of the steel after accelerated cooling from 885–860 °C can be exlained by the large content of martensite and bainite in the structure, and from 735ºC by enlargement of ferrite grains.Toughness and strength increased simultaneously only in a narrow range of temperatures (810–770 °С).
Conclusion. The structure and mechanical properties of steel 10G2FB after deformation at various temperatures of the intercritical interval and the accelerated cooling were determined. As a result it was established that the microstructure of the steel after cooling is a mixture of ferrite, bainite, martensite, and small amounts of residual austenite. Depending on the selected end temperature of deformation in the intercritical interval and subsequent cooling of these components the ratio of the structure is different, which affects the properties of the steel.
On the basis of the received results further study of the structure of steel produced in the temperature interval 810–770 °С with accelerated cooling is promising, as strength and toughness are increased and the ductility is not reduced significantly.
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