Development of technology for production of new materials on traditional wide-strip hot rolling mills using modern methods of numerical and physical modeling. Part 2

Abstract

The first part of the article presents a modern approach to the technology development for the manufacture of hot-rolled steel with characteristics that exceed the passport values of the equipment of traditional hot strip mills using based on the widespread use of mathematical and simulation methods. The stages of the laboratory experiment and the carried-out investigations are described. In the second part, the results of industrial implementation and their comparison with the results of a laboratory experiment are considered. According to the developed modes of hot rolling on the hot strip mill 2000, industrial batches of rolled products were produced using the technology of direct quenching from rolling heating. The resulting microstructure is a matrix of lower bainite with a share of upper bainite, retained austenite, and Fe3Mo3C carbide phase in total no more than 10 %. The formed structure provides in rolled products a strength of 1075 MPa and a relative elongation of at least 10 %. Due to the formation of a dispersed bainitic microstructure, the tension diagram is characterized by a degenerate yield plateau. The developed deformation rolling mode in the roughing and finishing groups of stands makes it possible to form elongated “fritter-like” grains with a grain length to thickness ratio of 2.5–3.0 before accelerated cooling, due to which the KCV–40 impact strength values significantly exceed the consumer requirements (170>27 J/cm2). Using modern numerical simulation methods, the parameters of accelerated cooling on the run out table and the downcoiler settings of the hot strip mill were determined, which made it possible to achieve the desired temperature state of the strip and defect-free coiling from the first piece. The convergence of the results of laboratory and industrial experiments is shown.The research was carried out within the framework of the program of strategic academic leadership of the Russian Federation "Priority-2030", aimed at supporting the development programs of educational institutions of higher education, the scientific project PRIOR/SN/NU/22/SP5/26 "Creation of innovative digital tools for the use of applied artificial intelligence and advanced statistical analysis of big data in technological processes for the production of metallurgical products.