| 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 hot-rolling a slab or cast slab of a low alloy steel with the prescribed composition at high rolling shape ratio, further hot-rolling the resulting plate at the prescribed draft, and then applying dehydrogenation heat treatment and further annealing or normalizing to the above plate according to plate thickness. CONSTITUTION:A slab or cast slab of a steel which has a composition containing, by weight, <=0.01% C, 0.1-4.0% 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 also containing <=0.01% Al or 0.01% Ca together with Si 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 carried out 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, e.g., of >=50mm plate 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 desired thick nonoriented silicon steel plate mentioned above. |
