METHOD OF PRODUCTION OF COLD-ROLLED ELECTRICAL-SHEET NON-ORIENTED STEEL Russian patent published in 2003 - IPC

FIELD: ferrous metallurgy; particularly, production of cold-rolled electrical-sheet non-oriented steel. SUBSTANCE: method of production of cold-rolled electrical-sheet non-oriented steel incorporates steps of hot rolling steel strip, normalizing hot-rolled strip, pickling, cold rolling and thermal treatment of cold-rolled strip; in so doing temperature of holding within 90-270 sec during normalizing hot-rolled strip containing as follows, % by mass: silicon 0.9-2.8; carbon not more than 0.04; sulfur not more than 0.1; aluminum 0.1-1.5; phosphorus not more than 0.16; manganese 0.1-1.0; nitrogen not more than 0.009; the remains are iron and imminent impurities, is selected to be not lower than critical point AC₃, depending upon silicon and carbon content in accordance with the following relationship: where: t_h is holding temperature during normalizing hot-rolled strip, C; 911 is temperature of phase transformation of pearlite to austenite in pure iron, C; K = 3.55 C / (%)^1/2 is experimentally determined factor considering the influence of silicon and carbon content in steel on temperature of phase transformation of pearlite to austenite in steel; Si is silicon content in steel, % by mass; C is carbon content in steel, % by mass. Rare-earth elements, namely tin Sn or antimony Sb with content of 0.003-0.20 % by mass are introduced, if necessary, into chemical composition of steel. EFFECT: improved electromagnet properties of cold-rolled electrical-sheet non-oriented steel. 2 cl, 2 tbl, 1 ex