| 摘要 |
PURPOSE:To obtain a thick nonoriented silicon steel plate having uniform magnetic properties in a plate-thickness direction and high magnetic flux density in a low magnetic field by subjecting a slab or cast slab of a low alloy steel with the prescribed composition to hot rolling at high rolling shape ratio and further to hot rolling at the prescribed draft and then applying dehydrogenation heat treatment and further annealing or normalizing to the resulting plate according to plate thickness. CONSTITUTION:A slab or cast slab of a steel containing, by weight, <=0.01% C, <=0.02% Si, <=0.20% Mn, <=0.010% S, <=0.05% Cr, <=0.01% Mo, <=0.01% Cu, <=0.004% N, <=0.005% O, and <=0.0002% H and deoxidized with 0.005-0.040% Al or 0.005-0.01% Ca is heated up to 950-1,150 deg.C and subjected to high rolling shape ratio rolling in which rolling pass of >=0.6 rolling shape ratio A (right-hand equation) is performed once or more at >=800 deg.C. Successively, the resulting rolled steel plate is rolled at <=800 deg.C at 10-35% draft, and then, in the case of a thick plate, for example, of >=50mm thickness, the plate is subjected to dehydrogenation treatment at 600-750 deg.C and, if necessary, to annealing at 750-950 deg.C or normalizing at 910-1,000 deg.C so as to be formed into the above thick silicon steel plate. |
