PROCESS OF PRODUCTION OF COLD-ROLLED SEMI-PROCESSED ELECTRICAL-SHEET STEEL Russian patent published in 2002 - IPC

FIELD: ferrous metallurgy, production of cold-rolled semi-processed electrical-sheet steel. SUBSTANCE: technical effect of utilization of proposed invention consists in improvement of electromagnetic properties of cold-rolled semi-processed electrical-sheet steel. Process of production of cold-rolled semiprocessed electrical-sheet steel includes hot rolling of steel slabs, annealing of hot-rolled strip, cold rolling and annealing of cold-rolled strip. Steel slab contains, per cent by mass: silicon 0.2-2.6; aluminum 0.01-0.5; carbon under 0.05; manganese 0.1-1.5; phosphorus 0.01-0.16; sulfur under 0.01. Holding temperature during annealing of hot-rolled strip is set by dependence: Th = 911+Kx(Si-Mn),^°C, where Th is holding temperature in process of annealing of hot-rolled strip, ^oC; 911 is temperature of phase transformation of pearlite to austenite in pure iron, ^°C Si is content of silicon in steel, per cent by mass; Mn is content of manganese in steel, per cent by mass; K is empirical coefficient taking into account effect of presence of silicon and manganese in steel on temperature of phase transformation of pearlite to austenite equal to 10-20 ^oC/mass%. Holding time in process of annealing of hot-rolled strip is set within limits of 80-200 s. Cold-rolled strip is annealed at temperature 780-850 ^oC with decarburization of metal to carbon content ^°C; 0.010%. If necessary, dressing with reduction of 1.0-7.0% is conducted after decarburizing annealing of cold- rolled strip. EFFECT: improved electromagnetic properties of cold-rolled electrical-sheet steel. 1 cl, 1 tbl