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Information × Registration Number 0226U003068, (0123U100374) , R & D reports Title Increasing the mechanical properties of rolled steel for structural purposes by the formation of non-equilibrium structural states by heat treatment and thermo-mechanical treatment popup.stage_title Підвищення механічних властивостей сталевого прокату конструкційного призначення формуванням нерівновісних структурних станів термічною та термодеформаційною обробками Head Zurnadzhy Vadym I., Кандидат технічних наук Registration Date 16-03-2026 Organization State Higher Educational Institution "Azov State Technical University" popup.description1 Development of technological proposals for the production of structural rolled steel of increased strength categories (S450...S690) by optimizing the chemical composition (reducing the content of alloying elements) of steel and applying energy-saving modes of heat treatment and thermo-mechanical treatment popup.description2 Research Objective: development of technological solutions to increase the efficiency of heavy plate production from structural steels through the implementation of resource-saving thermal and thermodeformational processing modes. Research Methods: optical and electron (scanning, transmission) microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, EBSD and EPMA methods, mechanical testing, nanoindentation, and computer thermodynamic modeling. Main Results: The study examines the influence of manufacturing process parameters on the properties of flat products. It was established that using 300 mm thick slabs for 25-40 mm plates (API 5L X70) ensures a high reduction ratio, grain refinement, and stabilization of properties across the cross-section: plasticity increases to 26-28%, low-temperature toughness — by 1.5-1.8 times, and the DWTT index — by 1.6-2.1 times. The modes of thermomechanical controlled processing (TMCP) with accelerated cooling (AcC) for low-carbon microalloyed steels were optimized. This forms a fine-grained ferrite-bainite structure with martensite-austenite complexes, meeting X70 requirements (YTS=540-580 MPa, UTS=630-660 MPa, DWTT - 80%). The application of TMCP + AcC allows upgrading S355N category steels to the S500QL1 level with improved toughness at –40…–60 °C and replacing traditional furnace quenching of S690QL high-strength steels with a combined treatment and tempering. This ensures stable performance (YTS=740 MPa, UTS= 830 MPa) while saving up to 300 m3/ton of natural gas. Optimized normalizing rolling with inter-pass pauses stabilizes the properties of plates up to 100 mm thick (235-355 MPa) without additional furnace normalization. For TRIP-assisted steels, the advantage of the Quenching and Partitioning (Q&P) process over isothermal quenching was proven: strength is ~50 MPa higher, and toughness increases by 1.4-2 times due to a higher volume fraction of retained austenite and microstructure refinement. Product Description popup.authors Taras M. Kovbasiuk Efremenko Bogdan V Vadim I. Zurnadzhi Yuliia H. Chabak Holynskyi Mykhailo A. Kolosok Eduard V. Kostiantyn I. Dobriakov Daria I. Pytlovska popup.nrat_date 2026-03-16 Close