| 摘要 |
PROBLEM TO BE SOLVED: To stably produce a grain oriented silicon steel sheet having extremely high magnetic flux density. SOLUTION: A slab contg., by weight, 0.025 to 0.075% C, 2.5 to 4.5% Si, 0.050 to 0.45% Mn, <=0.015% S and 0.015 to 0.040% acid soluble Al is heated and hot-rolled at <=1280 deg.C, in two stage cycle annealing before final cold rolling, the temp. on the high temp. side is controlled to 1060 to 1170 deg.C, cooling is executed in such a manner that the residense time at 980 to 920 deg.C in the process in which the temp. shifts to that on the low temp. side satisfies the relation with AIR (acid-soluble Al-27/14×N) (ppm) obtd. from the components in the hot rolled sheet, thereafter, it is rapidly cooled from 920 to 700 deg.C to a room temp. at a rate of >=10 deg.C/sec, and, then, final cold rolling at a rolling ratio of >=80%, decarburizing annealing, nitriding treatment and finish annealing are executed. |
