Nippon Steel Corporation

Yozo Suga

Yoshiyuki Ushigami

Nobuyuki Takahashi

Tadashi Nakayama

Katsuro Kuroki

Yasunari Yoshitomi

Toyohiko Konno

Takehide Senuma

Motoharu Nakamura

Satoshi Arai

Takeo Nagashima

Fumio Matsumoto

Kiyoshi Ueno

Hajime Komatsu

Kikuo Takashina

Takeshi Kubota

Hiroyasu Fujii

Shuichi Yamazaki

Osamu Tanaka

Tohru Iuchi

Shigehiro Yamaguchi

Hiromi Matsumoto

Minoru Kitayama

Hotaka Honma

Tadao Nozawa

Tadashi Ichiyama

Morio Shiozaki

Takaaki Yamamoto

Kiyoshi Tanaka

Hiromu Fujii

Syuji Kitahara

Kohichi Fujiwara

Yakichiro Kawamo

Mikio Itoh

Kensuke Mori

Toshio Nishiyama

Kenichi Takimoto

Hodaka Honma

Yosuke Kurosaki

Mitsuro Tanino

Masahiro Fukumoto

Grain oriented electrical steel sheet having specular surface

The present invention provides a thin sheet product having a combination of excellent magnetic properties inherent in the steel having a silicon content of 6.5% or near 6.5% with a further lowered iron loss property, particularly in a high frequency region, through the production of a magnetic thin steel sheet having a thickness of 0.23 mm or less by cold-rolling a steel sheet comprising by weight not more than that 0.006% of carbon, 5.0 to 7.1% of silicon, 0.07 to 0.30% of manganese, not more than 0.007% of sulfur, 0.006 to 0.038% of acid soluble aluminum and 8 to 30 ppm of total nitrogen with the balance consisting of iron and unavoidable impurities at a sheet temperature in the range of from 120.degree. to 350.degree. C. optionally after annealing the sheet at a temperature in the range of from 750.degree. to 1020.degree. C., and annealing the cold-rolled sheet at a temperature in the range of from 800.degree. to 1020.degree. C. for recrystallization and grain growth, to thereby prepare a magnetic steel sheet having a small thickness of 0.23 mm or less.

Process for producing ultrahigh silicon electrical thin steel sheet by

In the present invention, a slab of a silicon steel comprising usual components is hot-rolled while adjusting the hot rolling-finish temperature at 750.degree. to 1150.degree. C. and the cumulative reduction ratio of final three passes to at least 40%, or the above-mentioned silicon steel slab is hot-rolled at the above-mentioned hot rolling-finish temperature, the hot-rolled steel sheet is held at a temperature not lower than 35.degree. C. lower than the finish temperature for at least 1 second, and the steel sheet is wound at a winding temperature lower than 700.degree. C. Successively, the hot-rolled steel sheet is subjected, without annealing of the hot-rolled steel sheet, to cold rolling at a reduction ratio of at least 80%, decarburization annealing, and final finish annealing. According to this process, a grain oriented electrical steel sheet having superior magnetic properties can be prepared.

Process for production of grain oriented electrical steel sheet having

A process for producing a grain-oriented electrical steel sheet having a low watt loss, in which a steel strip consisting, in wt %, of 0.8 to 4.8 Si, 0.012 to 0.050 acid-soluble Al, 0.01 or less N, and the balance consisting of Fe and unavoidable impurities is cold-rolled to a final thickness of 0.15 mm or less, primary-recrystallization annealed, applied with a annealing separator containing magnesia as a major component by electrostatic spray painting, and then final-texture annealed.

Process for producing grain-oriented electrical steel sheet having low

The present invention is a process for manufacturing a double oriented electrical steel sheet having a high magnetic flux density by carrying out a low temperature annealing for the secondary recrystallization by the use of AlN as inhibitor, characterized by hot-rolling a silicon steel slab comprising 1.8-4.8% by weight of Si, 0.008-0.048% by weight of acid soluble Al, 0.0028-0.0100% by weight of acid soluble Al, 0.0028-0.0100% by weight of total N, not more than 0.016% by weight of S and the balance being Fe and unavoidable impurities into a hot-rolled sheet, subjecting the sheet to cold-rolling at a reduction rate of 40-80%, subsequently subjecting the sheet to another cold-rolling at a reduction rate of 30-70% in the direction crossing the cold-rolled direction, annealing at 750.degree.-950.degree. C. in a wet hydrogen atmosphere for decarburization, and carrying out the final finishing annealing which comprises a stage for completing the secondary recrystallizing at a temperature of 920.degree.-1100.degree. C., followed by a stage for purification.

Process for manufacturing double oriented electrical steel sheet having

The present invention provides a process for manufacturing a double oriented electrical steel sheet having a high flux density by suppressing the growth of the secondary recrystallization of {110} &lt;uvw&gt; oriented grains from the surface of the steel sheet in the hot-rolling stage or cold-rolling stage, which process comprises subjecting a hot rolled sheet comprised of 0.8-6.7% by weight of Si, 0.008-0.048% by weight of acid soluble Al, 0.010% by weight or less of N, and the balance being Fe and unavoidable impurities to a cold-rolling at a reduction rate of 40-80%, and then subjecting the resulting sheet to another cold-rolling in the direction vertical to the above cold-rolled direction at the reduction rate of 30-70% in the final thickness, followed by the steps of annealing for the primary recrystallization, applying an annealing separator, and applying finishing annealing for the secondary recrystallization and purification of steel, wherein the rolling in the finishing hot-rolling stage is carried out at the accumulated reduction rate of 20% or more under the condition that the friction coefficient between the rolls and the steel sheet is not more than 0.25; and wherein the accumulated reduction rate in the last three passes in the hot-rolling is not more than 80%; and further, wherein material of more than 1/10 of the total thickness is removed from both surfaces of the hot-rolled sheet; or wherein the cold-rolling is carried out using a work roll having a diameter of not less than 150 mm.

Ultrahigh silicon, grain-oriented electrical steel sheet and process for

A silicon steel slab comprising 0.05 to 0.8% by weight of Mn and up to 0.014% by weight of S+0.405Se is heated at a temperature lower than 1280.degree. C. and hot-rolled under such conditions that the hot rolling-finish temperature is 700.degree. to 1150.degree. C., the cumulative reduction ratio at the final three passes is at least 40%, and the reduction ratio at the final pass is at least 20%, or this silicon steel slab is hot-rolled at a hot rolling-finish temperature of 750.degree. to 1150.degree. C. while adopting the above-mentioned reduction ratio according to need, is maintained at a temperature not lower than 700.degree. C. for at least 1 second, and wound at a winding temperature lower than 700.degree. C. The hot-rolled sheet is subjected to the hot-rolled sheet annealing, finally cold-rolled at a reduction ratio of at least 80%, subjected to the decarburization annealing, and then subjected to the final finish annealing. According to this process, a grain-oriented electrical steel sheet having superior magnetic properties is obtained.

Process for preparation of grain-oriented electrical steel sheet having

Process for producing non-oriented electromagnetic steel sheet having

A process for producing a grain-oriented electrical steel sheet having an excellent magnetic characteristic, comprising the steps of: heating to a temperature lower than 1280.degree. C. a steel slab comprising 0.025 to 0.075 wt % C, 2.5 to 4.5 wt % Si, 0.010 to 0.060 wt % acid-soluble Al, 0.0030 to 0.0130 wt % N, 0.014 wt % or less (S+0.405 Se), 0.05 to 0.8 wt % Mn, and the balance consisting of Fe and unavoidable impurities; hot-rolling the thus heated slab to form a hot-rolled strip; cold-rolling the hot-rolled strip to form a cold-rolled strip; decarburization-annealing the cold-rolled strip; applying an annealing separator on the strip; final-annealing the strip; measuring a primary-recrystallized grain size in the stage after completion of a primary recrystallization during the decarburization annealing and before completion of a secondary recrystallization during the final annealing; and controlling in that stage the subsequent grain growth of primary-recrystallized grains by an absorption of nitrogen into the steel strip in accordance with the measured grain size.

Process for producing grain-oriented electrical steel sheet having

A method of producing an oriented electrical steel sheet having superior magnetic properties comprises the steps of, hot rolling a slab containing 0.8 to 6.8% of Si, 0.008% of Al acid soluble, the balance being Fe and accompanying impurities, by weight to form a strip, cold rolling the strip, primary-recrystallization annealing, coating the strip with an annealing separator, and finishing annealing, a nitriding treatment being effected after the primary recrystallization annealing but before the start of the secondary recrystallization of the finishing annealing. According to the present invention, with an atmosphere oxidizing degree (PH.sub.2 O/PH.sub.2): x in a soaking process in said primary recrystallization annealing an annealing is effected in an atmosphere which has an oxidizing degree (PH.sub.2 O/PH.sub.2): y in a range defined by the following inequality, at a temperature ranging from 650.degree. to 800.degree. C. in the heating process, for at least 5 secs. ##EQU1##

Method of producing oriented electrical steel sheet having superior

The present invention relates to a process for preparing a unidirectional silicon steel sheet having a high magnetic flux density which comprises heating a silicon steel slab comprising by weight 0.025 to 0.075% of carbon, 2.5 to 4.5% of silicon, 0.015% or less of sulfur, 0.010 to 0.050% of acid-soluble aluminum, 0.0010 to 0.012% of nitrogen, 0.050 to 0.45% of manganese and 0.01 to 0.10% of tin and optionally 0.0005 to 0.0080% of boron with the balance being iron and unavoidable impurities, at 1200.degree. C. or below; hot-rolling the slab; subjecting the slab to rolling once or two or more times wherein intermediate annealing is provided, thereby attaining a percentage final rolling of 80% or more; subjecting the resultant steel sheet to decarburizing annealing in a wet hydrogen atmosphere; coating the steel sheet with an annealing separator; conducting finishing annealing for secondary recrystallization and purification of the steel; and subjecting the steel sheet to a nitriding treatment between after the ignition for decarburizing annealing and before the initiation of the secondary recrystallization in the finishing annealing.

Process for preparing unidirectional silicon steel sheet having high

In the conventional process for the production of a double-oriented electrical steel sheet, the preparation steps are complicated and the manufacturing cost is very high. Nevertheless, the magnetization characteristic B.sub.10 is lower than 1.85 Tesla and the final sheet thickness cannot be reduced below 0.30 mm. According to the present invention, by strictly controlling the secondary recrystallization temperature and performing a third cold rolling in the same direction as the rolling direction of the first cold rolling, the magnetization characteristic B.sub.10 can be increased above 1.88 Tesla and the final sheet thickness can be reduced to 0.20 mm. Moreover, a double-oriented electrical steel sheet having an excellent shape (flatness) and a much smaller thickness deviation in the longitudinal direction of the product can be produced on an industrial scale. Therefore, this product can be effectively used as a core material of a large-size rotary machine or in a small-size static magneto-electronic device.

Process for production of double-oriented electrical steel sheet having

Disclosed is a process for the preparation of a grain oriented electrical steel sheet having a high flux desnity, which comprises hot-rolling a slab comprising 1.5 to 4.8% by weight of Si, 0.012 to 0.050 by weight of acid-soluble Al, up to 0.012% by weight of at least one member selected from S and Se, 0.0010 to 0.0120% by weight of N, Mn in an amount of up to 0.45% by weight which satisfies the requirement of Mn/(S+Se).gtoreq.4.0 and 0.005 to 0.0080% by weight of B, with the balance comprising Fe and unavoidable impurities, and optionally, further comprising 0.0020 to 0.0120% by weight of Ti, performing cold rolling once or at least twice with intermediate annealing to obtain a final thickness, performing decarburization annealing in a wet hydrogen atomsphere, coating an annealing separator on the steel sheet surface, performing finish annealing for a secondary recrystallization and purification of the steel, and performing a nitriding treatment during the period of from the point of termination of final cold rolling to the point of initiation of secondary recrystallization at the finish annealing step. Furthermore, the above-mentioned slab is heated at a temperature lower than 1200.degree. C. before the hot rolling step, and even in the production of a thin product having a thickness of 0.10 to 0.23 mm, a high flux density can be realized.

Disclosed is a process for the preparation of a grain oriented silicon steel about sheet having a high flux density, which comprises hot-rolling a slab comprising 1.5 to 4.8% by weight of Si, 0.012 to 0.050% by weight of Al, 0.0010 to 0.0120% by weight of N, 0.0020 to 0.0150% by weight of Ti, up to 0.45% by weight of Mn and up to 0.012% by weight of at least one member selected S and Se, which satisfies the requirement 0.06 to 0.6 of Ti/N (at % ratio) and Mn/(S+Se).gtoreq.4.0 (weight ratio) with the balance comprising Fe and unavoidable impurities, to cold-rolling, performing decarburization annealing, coating an annealing separator on the steel sheet surface, then performing finish annealing, and performing a nitriding treatment of the steel sheet during the period of from the point of termination of final cold rolling to the point of initiation of secondary recrystallization at the finish annealing step.

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Kitakyushu, Japan

Yozo Suga