Nippon Steel Corporation

Hiromu Fujii

Yozo Suga

Eiichi Takeuchi

Morio Shiozaki

Osamu Kitamura

Masafumi Okamoto

Kohichi Fujiwara

Seizo Mineyuki

Tetsuro Ohashi

Tetsro Ohashi

Improvements of a process for producing a non-directional electrical steel sheet free from ridging, which comprises making a molten steel into slabs by continuous casting, hot rolling the slab, cold rolling the hot rolled product into a final thickness by a single step, and subjecting the cold rolled product to decarburization annealing, said molten steel consisting essentially of not more than 0.02% C, 1.5 to 4.0% Si, not more than 1.0% Al, with the balance being Fe and unavoidable impurities, said hot rolling being done at a temperature in a range of from 900.degree. to 1100.degree. C. before a finishing rolling of the hot rolling, said improvements comprising stirring electromagnetically unsolidified molten steel in a zone where the molten steel is at a temperature not higher than the liquidus line and remains in thickness not less than 50% to whole cast thickness, so as to allow not less than 50% of the slab central zone corresponding to a central zone of the hot rolled product which does not recrystallize during the hot rolling to transit into an equi-axed structure.

Process for producing non-directional electrical steel sheets free from

In the continuous casting of steel, it has been possible to produce killed steel industrially, but semikilled and rimmed steel have not been successfully produced due to rimming action occurring in the oscillating mold. The present invention involves a concept of suppressing the nuclei of bubbles which will later grow into CO bubbles. In order to suppress the nuclei of bubbles and to form a non-defective solidification layer of a continuously cast strand, the present invention provides a combination of: a free oxygen concentration of from 50 to 200 ppm in the molten steel; a concave shape at the short sides of the mold; a propulsion forces of the molten steel directed along the long sides of the mold in directions opposite to one another; subjecting a solidification interface to an electromagnetic flow having a speed of from 0.1 to 1.0 m/sec, and; solidifying the molten steel at the solidification interface under the influence of the electromagnetic flow, until a non-defective solidification layer without blow holes is obtained.

Process for continuous casting of a slightly deoxidized steel slab

A continuously cast steel slab for production of a grain-oriented electrical steel sheet having excellent magnetic properties in which at least 95% of the total number of grains constituting an equi-axed crystal zone in said slab has a cross sectional dimension less than 9 mm.sup.2 per one grain.

Continuously cast slabs for producing grain-oriented electrical steel

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Himeji, Japan

Hiromu Fujii