| 摘要 |
PROBLEM TO BE SOLVED: To make excellent the magnetic shielding properties and demagnetizability in low magnetic fields and blackening treatability of a steel sheet by specifying the chemical compsn. of a steel and controlling each condition in hot rolling, finish rolling, cooling, coiling, cold rolling and continuous annealing. SOLUTION: The chemical compsn. of a steel is composed of the one contg., by weight, <=0.0050% C, 0.05 to 0.20% Si, 0.05 to 0.35% Mn, <0.020% P, <=0.020% S, <0.002% solAl, <=0.0050% N, <=0.0100% B and <=0.0200% O, satisfying >=1.4 B/N, and the balance Fe. This steel slab is heated at 1,000 to 1,200 deg.C, is subjected to hot rolling and is subjected to finish rolling at >=880 deg.C. It is cooled at a cooling rate of <=20 deg.C/sec to 800±30 deg.C and is furthermore subjected to slow cooling of <=10 deg.C/sec for >=3 sec. This is coiled in the range of >680 to 750 deg.C, is pickled and is successively subjected to cold rolling at 45 to <65% rolling reduction. Then, it is subjected to continuous annealing at 750 to 850 deg.C maximum arrival temp. In this way, the steel sheet high in permeability and small in coercive force in low magnetic fields can be obtd.
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