PURPOSE: To produce a nonoriented silicon steel sheet having low iron loss and reduced in the plane anisotropy of magnetic flux density by successively subjecting a slab of steel containing specific percentages of C, Si, Mn, P, S, and Al to hot rolling, cold rolling, and finish annealing under respectively specified conditions.
CONSTITUTION: A slab of a steel having a composition consisting of, by weight, ≤0.01% C, ≤1.0% Si, 0.1-0.7% Mn, ≤0.1% P, ≤0.010% S, ≤0.50% Al, and the balance Fe with inevitable impurities is rolled at a hot finishing temp. of 650-800°C and coiled at ≤600°C, and the resulting hot rolled steel sheet is annealed under the conditions of 700°C-Ac1 for ≥2hr at the time of box annealing and also of 800°C-Ac1 for ≥2min at the time of continuous annealing. Subsequently, the above plate is cold-rolled twice, while process-annealed between the cold rolling stages, under the conditions of 75-90% recrystallization ratio after process annealing and 3-10% secondary cold rolling rate to the final product thickness and then subjected to finish annealing.
OKANO YOICHIRO
TSUKATANI ICHIRO
KASE TOMOHIRO
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