| 摘要 |
For enabling to make the non-oriented magnetic steel strips, by the direct rolling, the invention is to decrease the amounts of AlN and MnS which precipitate on the way of the direct rolling to such a level that they do not affect the magnetic properties by regulating the Al and S amounts, and further to have unavoidable precipitating nitrides precipitate coarsely as BN. In the invention, in regard to the steel composition, the amount of C, Si and P are not only regulated, but also the amounts of Mn, Al, S and N are regulated from the above standpoint, and a proper amount of B is added if required. In addition, in regard to treatment conditions, in order to secure necessary finishing and coiling temperatures, the lower limit of the slab temperature at the starting time of the direct rolling is specified. Moreover, to promote refining of ferrite, the upper limit of the finishing temperature is specified, and also to prevent non-uniform recrystallization after coiling, the upper limit of the coiling temperature is specified. Furthermore, to secure satisfied magnetic properties, the annealing of the hot rolled strip is performed under specific conditions determined by a soaking temperature and a soaking time. In addition, to secure the magnetic properties of the cold rolled strip, the strip is finally continuously annealed at determined temperatures.
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