DOI: 10.18503/1995-2732-2023-21-4-70-80
Abstract
Relevance and Objectives. Until recently, in Russia there were several regulatory documents (GOST) specifying the chemical composition, geometric parameters and technical requirements for reinforcing steel in bars and coils, as well as the production method (hot rolling, hot rolling with subsequent thermal hardening in the line of section mills using heat of pre-rolling heating, cold rolling and/or drawing of hot rolled rods) of such products of different strength classes, special technological properties (weldability, resistance to fatigue loads, seismic resistance, etc.). Therefore, given the experience of advanced industrial countries, for example, European Standard EN 10138, since 2018, GOST 34028-2016, a developed standard of a similar class, has been implemented in Russia. According to the requirements of these standards, the production method of reinforcing steel is determined by manufacturers. It is necessary to comply with customer requirements for the parameters and properties of reinforcing steel and ensure a high level of service and operational characteristics of steel products. This research is aimed at solving the currently relevant issue of providing contradictory sets of properties at minimal costs. Objectives. Formation of a microstructure and mechanical properties of dual- and multi-phase reinforcing steel in coils. Results. This paper examines controlled rolling modes on a wire line of an industrial bar and wire rolling mill aimed at producing deformed reinforcing steel bars with a nominal diameter of 6 mm in coils with a dual- (ferrite-martensite(bainite)) and multi-phase (ferrite- martensite (bainite)-pearlite) structure from manganese-silicon low-alloy steel grade 18G2S, microalloyed with vanadium. It has been established that the indicators of high strength and ductility of reinforcing bars with a diameter of 6 mm in coils from steel under study (σт = 530-550 MPa; σв = 785-885 MPa; δ5 = 15.0-29.0%), fully meeting the requirements of the standards for high-strength reinforcing steel, are achieved at coil formation temperatures Тво in the range of 1020-1060ºС, providing the formation of a special multi-phase (ferrite-martensite(bainite)-pearlite) steel structure. Conclusions. The authors determined modes of controlled rolling on the wire line of an industrial bar rolling mill, ensuring the production of deformed reinforcing steel bars with a diameter of 6 mm (No. 6) in coils with a dual- and multi-phase structure from manganese-silicon low-alloy steel grade 18G2S, microalloyed with vanadium. It has been established that indicators of high strength and ductility of reinforcing bars No. 6 are achieved at temperatures Тво in the range of 1020-1060ºС, entailing a formation of a multi-phase structure.
Keywords
reinforcing steel in coils, chemical composition of steel, thermomechanical hardening, microalloying, vanadium, controlled rolling, dual- and multi-phase structure, Stelmore line, ferrite, pearlite, bainite, martensite, technological parameters-modes
For citation
Sychkov A.B., Nesterenko A.M., Zavalishchin A.N., Moller A.B., Kulakov B.A., Shubin I.G. Formation of a Microstructure and Mechanicalproperties of Dual- and Multi-Phase Reinforcing Steel in Coils. Vestnik Magnitogorskogo Gosudarstvennogo Tekhnicheskogo Universiteta im. G.I. Nosova [Vestnik of Nosov Magnitogorsk State Technical University]. 2023, vol. 21, no. 4, pp. 70-80. https://doi.org/10.18503/1995-2732-2023-21-4-70-80
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