| 摘要 |
PURPOSE: To provide a method of manufacturing a nonoriented flat rolled magnetic steel sheet whose iron loss is low especially in a high-frequency use and whose workability is good. CONSTITUTION: A slab as steel in which C in 0.010% or lower, Si in 2.0 to 3.25%, Mn in 0.1 to 2.5%, P in 0.02% or lower, N in 0.006% or lower, Al in 1.5 to 2.5% and B in 0 to 0.0050% are contained, in which Si (in %)+Al(in %)>=4.5 and Si (in %)+0.5A (in %)<4.0 are satisfied and whose remaining part is composed of Fe and of unavoidable impurities is hot-rolled. After that, in the method of manufacturing a nonoriented flat rolled magnetic steel sheet, a hot-rolled plate is annealed, a cold-rolling operation at a rolling rate of 40 to 80%, an intermediate annealing operation at 650 to 1000 deg.C and a cold-rolling operation at a rolling rate of 40 to 80% are performed, and, after that, a finish annealing operation is performed so as to lower an iron loss. Without using a special production installation, it is possible to manufacture the nonoriented flat rolled magnetic steel sheet whose cold workability and stamping workability are excellent and whose iron loss in a high-frequency region is low. |
