| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a grain-oriented silicon steel sheet high in magnetic flux density and, e.g. used for the iron core of an electric equipment. SOLUTION: In the method for producing a grain-oriented silicon steel sheet in which a silicon steel slab contg., by weight, 0.020 to 0.075% C, 2.5 to 5.0% Si, 0.05 to 0.45% Mn, <=0.015% S and/or Se, 0.01 to 0.05% acid soluble Al, and the balance N, Sn, Cr, Cu or the like by prescribed amounts is heated to <=1,280 deg.C and is thereafter hot-rolled, the hot rolled sheet is annealed, is subsequently subjected to cold rolling for one time or >= two times including process annealing in such a manner that the final cold rolling ratio is controlled to >=80% and is then subjected to decarburizing annealing, nitriding treatment and final annealing, the average grain diameter D in the steel sheet after the decarburizing annealing is controlled to the range of 23 to 40 μm, the content (ppm) of nitrogen in the steel sheet after the nitriding is controlled so as to satisfy N (ppm) >=11D-40 and 280-4R<=N (ppm)<=480-13R, and moreover, the temp. rising rate R at least in the range of 1,000 to 1,150 deg.C in the temp. rising stage in the finish annealing is controlled to the range of 3 to 10 deg.C/h. |
