METHOD FOR DYNAMIC CONTROL OF THERMALLY TREATED STEEL SHEET PRODUCTION PROCESS Russian patent published in 2020 - IPC C21D11/00 C21D9/573 C21D1/55 G01N33/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy. To ensure uniform mechanical properties of the steel sheet and to improve the quality, a steel sheet is obtained with a given chemical composition and a microstructure m_target containing at least one phase of ferrite, martensite, bainite, perlite, cementite and austenite. First, heat treatment of HT sheet is performed by heating, maintenance and cooling on heat treatment line, having heating, holding and cooling sections with cooling system. Heat treatment process is controlled: A. control stage, at which at least one sensor detects a deviation occurring in the heat treatment process of the CT, stage of calculation, which is carried out when detecting deviation in the process of current transformers, is used to determine a new TP_target thermal mode and to obtain a microstructure m_target taking into account the detected deviation. At that, calculation stage of B includes: 1) a calculation sub-stage, on which, by varying the cooling capacity, new cooling modes CP_x are calculated based on the heat treatment process of the CT, the initial microstructure m_i of the sheet steel to obtain m_target, the heating mode and the holding mode, which includes T_soaking and T_cooling, wherein cooling at TT stage is recalculated using said CP_x to establish new thermal modes TP_x, in which cooling stage is replaced by one of CP_x cooling modes to obtain thermal conditions TP_x, each of which corresponds to microstructure m_x. Thermal mode TP_x includes time, heat treatment temperature and at least one speed selected from cooling rate, heating rate or rate of isothermal holding, 2) a selection step, at which selecting one thermal TP_target mode to obtain a microstructure m_target, wherein TP_target is selected from the design thermal modes TP_x such that the difference between fractions of phases present in microstructures m_target and m_x is ± 3 %, C. new stage of heat treatment, on which thermal mode TP_target is realized for steel sheet located in thermal treatment line.

EFFECT: providing uniform mechanical properties and higher quality of steel sheet.

34 cl, 4 dwg, 6 tbl, 2 ex