Nippon Steel Corporation

Norito Abe

Yoshiyuki Ushigami

Tadao Nozawa

Masaki Tanaka

Tadashi Nakayama

Yousuke Kurosaki

Kunihide Takashima

Nobuo Tachibana

Isao Iwanaga

Masao Yabumoto

Yoshio Nakamura

Kentaro Chikuma

Kiyokazu Ichimura

Osamu Honjo

Sadanobu Hirokami

Masayuki Yamashita

Sadami Kousaka

Ryutarou Kawamata

Grain-oriented electrical steel sheet and method for producing same

Very high magnetic flux density grain-oriented electrical steel slab containing 2.5 to 4.0 weight percent silicon as an essential component and having a very high magnetic flux density B.sub.8 of not less than 1.92 tesla, in which by area not less than 80 percent is accounted for by matrix secondary recrystallization grains having a diameter not larger than 100 mm and not smaller than 10 mm in a direction of cold rolling and not larger than 50 mm and not smaller than 5 mm in a direction perpendicular to the cold rolling direction, and in which, moreover, of the grains in said matrix, not fewer than 50 percent by ratio of number are fine secondary recrystallization grains having an average diameter not larger than 5 mm.

Grain-oriented electrical steel sheet and material having very high

A very thin electrical steel strip having a thickness not exceeding 150 microns, an average grain diameter not exceeding 1.0 mm, a high degree of {110} &lt;001&gt; grain orientation, a high normalized magnetic flux density as expressed by a B.sub.8 /B.sub.s value which is greater than 0.9, and a low core loss not exceeding 50% of the core loss of any conventional product. It is produced from a starting material consisting of a grain-oriented electrical steel strip containing not more than 8% silicon, the balance thereof substantially being iron, and having a high degree of {110} &lt;001&gt; grain orientation, a normalized magnetic flux density as expressed by a B.sub.8 /B.sub.s value which is greater than 0.9, an average grain diameter of at least 20 mm in the rolling direction and an average grain diameter of at least 40 mm in the direction perpendicular to the rolling direction. The material is cold rolled with a reduction of 60 to 80% to a final thickness not exceeding 150 microns, and the cold rolled material is annealed for primary recrystallization. The use of a starting material further containing 0.005 to 0.30% of one or both of tin and antimony yields a product of still improved properties.

Very thin electrical steel strip having low core loss and high magnetic

The present invention provides a wound core having a low core loss and not susceptible to a disappearance of the core loss lowering effect due to a magnetic domain refining even when stress-relief annealing is conducted after fabrication of a steel strip into a wound core, through a process which comprises, fabricating a very thin silicon steel strip comprising by 6.5% weight or less of silicon with the balance consisting essentially of iron and having a sheet thickness of 100 .mu.m or less and a magnetic flux density (B.sub.8 value) of 1.80T or more into a wound core, subjecting the wound core to stress-relief annealing, unwinding the very thin silicon steel strip from the core, introducing into the very thin silicon steel strip a linear or dotted local strain in a direction at an angle of 45.degree. to 90.degree. to the rolling direction of the thin strip, and rewinding the thin strip onto the core.

Process for preparing wound core having low core loss

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Himeji, Japan

Norito Abe