PURPOSE: To stably produce a grain-oriented silicon steel sheet in which the occurrence of the defect of blisters in a slab is prevented and excellent in magnetic properties by subjecting a silicon steel continuously cast slab produced under specified solidifying conditions to hot and cold rolling, decarburizing annealing and final finish annealing under specified temp. conditions.
CONSTITUTION: The molten metal of high silicon steel contg. >0.0025wt.% N is subjected to continuous casting into a continuously cast slab, and at the point of time in which the unsolidified part in the central part of the slab is left by ≥1/3 of the slab thickness, the residual unsolidified part is solidified by electromagnetic stirring. Next, the slab is heated in a nonoxidizing atmosphere, is subjected to hot rolling and is subjected to cold rolling for one time or ≥ two times including process annealing to regulate its sheet thickness into a final one, which is subjected to decarburizing annealing, is thereafter applied with a separation agent for annealing and is subjected to final finish annealing. At that time, the slab is heated under temp. conditions is which TSL-50≤TSR≤TSL is satisfied between the heating temp. TSR and the solidus temp. TSL in the position of the maximum segregation in the thickness direction of the slab to prevent the occurrence of the defect of blisters at the time of the slab heating, by which the grain oriented silicon steel sheet excellent in magnetic properties can be produced.
MURAKI MINEO
TAKAMIYA TOSHITO
