Nippon Steel Corporation

Kunisuke Miyoshi

Yoshiaki Shimoyama

Takeshi Kubota

Yoshitaka Hiromae

Hiroyuki Kimura

In a conventional process for producing a semi-processed non-oriented electrical steel sheet, the silicon or aluminum content of a hot-rolled steel strip is high, especially in the case of producing a high-grade electrical sheet which has a low watt loss. However, a high silicon or aluminum content disadvantageously results in a decrease in the magnetic flux density. A decrease in the watt loss and an increase in the magnetic flux density in semi-processed non-oriented electrical steel sheets as compared with conventional high-grade semi-processed non-oriented electrical steel sheets can be achieved by making the silicon content, which increases resistivity, low, i.e. from 0.1 to 1.0%, and the manganese content, which is effective for improving the texture, high i.e. from 0.75 to 1.5% and by subjecting the starting material, having a low silicon content, and a high manganese content to an appropriate production process for controlling texture.

Process for producing a semi-processed non-oriented electrical steel

In the production of non-oriented electrical steel sheets, it has been attempted to decrease the watt loss, e.g., by adding Sn to silicon steels, but in such a case the relationship between the watt loss and the magnetic flux density falls within the curves 1 and 1' in FIG. 1. The addition of boron is therefore unsatisfactory for meeting the recent demand for improving the magnetic properties of a non-oriented electrical steel sheet over those indicated by the curve 3. In the present invention, the combined addition of Sn and B and/or sol. Al results in the development of (110) and (100) textures, which are desirable for the magnetic properties. A non-oriented electrical steel sheet according to the present invention consists of:

Non-oriented electrical steel sheet having a low watt loss and a high

Process for producing a non-oriented electromagnetic steel sheet having

Process for producing non-directional electric steel sheets free from ridging, comprising preparing slabs by continuous casting from molten steel comprising not more than 0.04% C, 1.5 to 4.0% Si, not more than 1.0% Al, the balance being Fe and unavoidable impurities, hot rolling, cold rolling and annealing the slabs, characterized in that the slab is subjected to breaking-down with a reduction rate between 10 to 70% in the sheet thickness direction at a temperature between 1000.degree. and 1300.degree. C, and subsequently the required treatments are done.

Process for producing non-directional electric steel sheets free from

A method for manufacturing non-oriented electrical steel sheet and strip having no ridging characterized in that, non-oriented electrical steel sheet and strip is manufactured by casting molten silicon steel into a slab, hot-rolling, cold-rolling and annealing, said molten silicon steel, being controlled so as to give a composition, at the time of hot-rolling, comprising C &lt;0.06%, Si 1.5 - 4.0% and Al &lt; 1.0%, with the relation Si + Al &gt; 2.0% and also C .gtoreq. 1/100 [(Si + Al) - 0.75]% with the remainder being iron and unavoidable impurities.

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Kitakyushu, Japan

Kunisuke Miyoshi