Nippon Steel Corporation

Tetsuo Kimoto

Kiyoshi Orita

Katsuro Kuroki

Hiromichi Koshiishi

Yasuhiro Shinkai

Hisao Takahashi

Toshimi Kawabata

The watt loss of a grain-oriented electromagnetic steel sheet can be decreased by known methods in which serrations or scratches are locally formed on said steel sheet or a small ball or disc is rolled or rotated over said steel sheet. The known methods are disadvantageous in that the rate of production is low and in that said steel sheet has a marked unevenness. In the present invention, particles, e.g., steel shots, are projected onto substantially linear selected portions of a grain-oriented electromagnetic steel sheet, thereby producing strain on spot-formed regions. Spotlike indentations are formed in the steel sheet by the projection of steel shots onto the steel sheet.

Method and apparatus for reducing the watt loss of a grain-oriented

The watt loss of a grain-oriented electromagnetic steel sheet can be reduced by known methods in which serrations or scratches are locally formed on the steel sheet or a small ball or disc is rolled or rotated over the steel sheet. The known methods are disadvantageous in that the rate of production is low and in that the steel sheet has a marked unevenness. In the present invention, particles, e.g., steel shots, are projected onto substantially linear selected portions of a grain-oriented electromagnetic steel sheet, thereby producing strain in spot-formed regions. An apparatus according to the present invention comprises an endless conveyor and a means for projecting particles. Slits are formed in the endless conveyor, and particles are projected through these slits onto the substantially linear selected portions.

Apparatus for reducing the watt loss of a grain-oriented electromagnetic

In finish annealing process for a grain-oriented electrical steel strip or sheet, an improvement is disclosed which comprises coating the grain-oriented electrical steel strip or sheet with an annealing separator having a water content adjusted to not more than 10%, drying the coated strip or sheet, forming it into a strip coil, and finish annealing the strip coil within the inner cover of an annealing furnace while controlling the pressure of the gas atmosphere within the inner cover.

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Kitakyushu, Japan

Tetsuo Kimoto