COLD ROLLING METHOD FOR OBTAINING GRAIN ORIENTED SILICON STEEL SHEET SMALL IN VARIATION OF MAGNETIC PROPERTY IN COLD ROLLING DIRECTION

摘要

PROBLEM TO BE SOLVED: To provide a cold rolling method for uniformizing the magnetic properties in the longitudinal direction of a coil in a gain oriented silicon steel sheet using AlN as an inhibitor. SOLUTION: In the method for producing a grain oriented silicon steel sheet in which a silicon steel slab containing, by mass, 0.025 to 0.100% C, 2.5 to 4.5% Si, 0.03 to 0.45% Mn and 0.015 to 0.040% Al is subjected to hot rolling and is thereafter subjected to cold rolling for one time or for two or more times including process annealing to form a steel sheet having a final sheet thickness, and then, this steel sheet is subjected to primary recrystallization annealing, is coated with a separation agent for annealing to form into a coiled shape and is subjected to secondary recrystallization annealing, the final cold rolling is performed at a draft of 81% or more by a tandem cold rolling mill, also, the variation of the rolling rate in the cold rolling in one coil is controlled to 800 m/min or less, and moreover, the rolling rate is controlled to 1,000 m/min or more.