| 摘要 |
PROBLEM TO BE SOLVED: To moreover reduce a core loss in a steel sheet by performing a nonoriented silicon steel hot rolled sheet in which the contents of C, Si, Mn and Al are specified and the intrusion of S, N and O is suppressed, to specified cold rolling holding specified intermediate annealing after annealing and thereafter executing specified final finish annealing. SOLUTION: A nonorentd silicon steel slab having a compsn. contg., by weight, <=0.005% C, 1.0 to 5.0% Si, 0.1 to 2.0% Mn and 0.1 to 2.0% Al and in which the content of S is suppressed to <=0.0030%, that of n to <=0.0030% and that of 0 to <=0.0020% is hot-rolled, is coiled around a coil and thereafter, performed to hot-rolled sheet annealing. As for the conditions of this hot-rolled sheet annealing, in continuous annealing, 900 to 1,100 deg.C×10 sec to 3 min are regulated and in box annealing, 750 to 900 deg.C×0.5 to 12 hr are regulated. Then the hot-rolled sheet is performed to first time cold rolling and is performed to intimediate annealing at 900 to 1,100 deg.C for 10 sec to 3 min to regulate the average crystal grain size to >=50 μm and then, final cold rolling is executed at a draft of 45 to 65. After that, the cold rolled sheet is performed to final finish annealing at 900 to 1,100 deg.C for 10 sec to 5 min. |
