Assimilation of production in an MMK 5000 mill of thick rolled sheet from low-alloy steels with improved strength and cold resistance properties

Results are presented for development and introduction into production in a new MMK 5000 mill for thick rolled sheet from low-alloy steels with increased strength properties (σ y ≥ 500 N/mm 2 and σ y ≥ 570 N/mm 2 ), impact strength ( KCV −40 ≥ 200–270 J/cm 2 ), and cold resistance. Features of structure formation are studied in sheet of considerable thickness in the course of controlled rolling with accelerated cooling. The effect of the amount of reduction in subsequent passes of the roughing stage for sheet on cold resistance during the FWT is revealed. Transmission electron microscopy is used to show that the optimum set of properties for high-strength sheet is achieved with formation of a fine steel ferrite-bainite microstructure whose main structural components are quasipolygonal and acicular ferrite.