To provide a method of stable production of a nonoriented silicon steel sheet having high magnetic flux density and used for an iron core material for electric equipment.
A slab, having a composition consisting of, by weight, 0.10-4.00% Si, 0.10-1.50% Mn, ≤0.0050% C, 0.0050% N, ≤0.0050% S, and the balance Fe with inevitable impurities, is hot-rolled, and the resultant hot rolled plate is cold-rolled once or is cold-rolled two or more times while process-annealed between cold rolling stages, followed by finish annealing. In this case, at respective stands of a finish hot rolling mill in the hot rolling stage consisting of n passes, the concentration of the lubricating oil mixed into roll cooling water is regulated so that is satisfies the following inequalities (1), (2), (3):(1) v1≤1.0%; (2) v1≤v2≤v3≤...≤vn; (3) 1.0%≤vn≤10.0%. In the above inequalities, vi (i=1, 2, 3,..., n) represents the volume fraction (%) of the lubricating oil mixed into the roll cooling water at the i-th stand.
KUBOTA TAKESHI
SENUMA TAKEHIDE
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