Patents by Inventor Yasunari Yoshitomi
Yasunari Yoshitomi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6858095Abstract: A grain-oriented electrical steel sheet comprising 2.5-4.5% Si by weight and measuring 0.36-1.00 mm in thickness is imparted with a good core loss value for its thickness by controlling its C content, flux density, grain boundary configuration, and deviation degree of crystal orientation in the grains.Type: GrantFiled: February 14, 2001Date of Patent: February 22, 2005Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Hiroaki Masui, Nobuyuki Takahashi
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Publication number: 20010042576Abstract: A grain-oriented electrical steel sheet comprising 2.5-4.5% Si by weight and measuring 0.36-1.00 mm in thickness is imparted with a good core loss value for its thickness by controlling its C content, flux density, grain boundary configuration, and deviation degree of crystal orientation in the grains.Type: ApplicationFiled: February 14, 2001Publication date: November 22, 2001Inventors: Yasunari Yoshitomi, Hiroaki Masui, Nobuyuki Takahashi
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Patent number: 5759293Abstract: A decarburization-annealed steel strip as an intermediate material for grain-oriented electrical steel strip having good secondary recrystallization and excellent electrical properties is provided by causing a steel strip to possess a micro-structure in which the primary recrystallization grains have an average diameter d of not less than 15 .mu.m and a coefficient of diameter deviation .sigma.* of not more than 0.6.Type: GrantFiled: November 6, 1995Date of Patent: June 2, 1998Assignee: Nippon Steel CorporationInventors: Nobuyuki Takahashi, Yasunari Yoshitomi, Tadashi Nakayama, Yoshiyuki Ushigami
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Patent number: 5597424Abstract: The present invention relates to the provision of a process for producing a grain oriented electrical steel sheet having excellent magnetic properties, and comprises heating a slab comprising by weight 0.021 to 0.075% of C, 2.5 to 4.5% of Si, 0.010 to 0.060% of acid sol. Al, 0.0030 to 0.0130% of N, 0.014% or less of (S and 0.405 Se) and 0.05 to 0.8% of Mn with the balance being Fe and unavoidable impurities to a temperature below 1280.degree. C. to hot-roll the slab, subjecting the hot rolled sheet to cold rolling with a draft of 80% or more and subjecting decarburization annealing and then finish annealing, characterized in that, after the hot rolling, the hot strip is taken up at a temperature of 600.degree. C. or below and subjected to nitriding at any stage from after the hot rolling to the completion of the secondary recrystallization in the finish annealing without annealing of the hot rolled sheet.Type: GrantFiled: July 13, 1995Date of Patent: January 28, 1997Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Takehide Senuma
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Patent number: 5545263Abstract: 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.Type: GrantFiled: May 20, 1994Date of Patent: August 13, 1996Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Takehide Senuma, Yozo Suga, Nobuyuki Takahashi
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Process for production of grain oriented electrical steel sheet having excellent magnetic properties
Patent number: 5512110Abstract: In the present invention, grain oriented electrical steel sheets provided by heating a slab comprising, by weight percent, 0.025 to 0.075% of C, 3.4 to 5.0% of Si, 0.015 to 0.080% of sol. Al, 0.0030 to 0.013% of N, 0.014% or less of (S+0.405 Se) and 0.05 to 0.8% of Mn, sol. Al (%)/Si (%) being 0.0080 or more, the balance consisting of Fe and unavoidable impurities at a temperature below 1280.degree. C., hot-rolling the heated slab, subjecting the hot-rolled steel sheet to cold rolling, subjecting the cold-rolled steel sheet to decarbonization annealing with regulating the average diameter of primary recrystallized grains of the steel sheet subjected to decarbonization annealing to 18 to 35 .mu.Type: GrantFiled: June 6, 1995Date of Patent: April 30, 1996Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Katsuro Kuroki, Yukio Matsuo, Hiroaki Masui, Yoshio Nakamura, Maremizu Ishibashi, Tsuyoshi Kawano, Tsutomu Haratani, Yoshiyuki Ushigami -
Production method of grain oriented electrical steel sheet having excellent magnetic characteristics
Patent number: 5472521Abstract: This invention is directed to improve magnetic properties and to stabilize the magnetic properties of a grain oriented electrical steel sheet used as a core of electric appliances. When producing a grain oriented electrical steel sheet by heating a slab containing C, Si, acid-soluble Al, N, not more than 0.014% of S+0.405 Se and 0.05 to 0.8% of Mn and the balance consisting of Fe and unavoidable impurities at a temperature of less than 1,280.degree. C.Type: GrantFiled: October 13, 1994Date of Patent: December 5, 1995Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Maremizu Ishibashi, Yoichi Mishima, Koji Yamasaki -
Patent number: 5346559Abstract: 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} <uvw> 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.Type: GrantFiled: March 19, 1993Date of Patent: September 13, 1994Assignee: Nippon Steel CorporationInventors: Yoshiyuki Ushigami, Satoshi Arai, Yozo Suga, Yasunari Yoshitomi, Nobuyuki Takahashi, Takehide Senuma
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Process for preparation of grain-oriented electrical steel sheet having superior magnetic properties
Patent number: 5261971Abstract: 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.Type: GrantFiled: April 16, 1992Date of Patent: November 16, 1993Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Takehide Senuma, Yozo Suga, Nobuyuki Takahashi -
Patent number: 5261972Abstract: The present invention discloses a process for producing a grain-oriented electrical steel strip having a high magnetic flux density. The process comprises hot-rolling a steel ingot comprising basic ingredients and, added thereto, 0.02 to 0.15% of Sn at a temperature of 1200.degree. C. or below, annealing the hot-rolled strip, cold-rolling the annealed strip with a final rolling reduction of 80% or more and subjecting the cold-rolled strip to decarburization annealing, a nitriding treatment and finish annealing, wherein the temperature, T.degree.C., of annealing of the hot-rolled strip is set so as to fall within the range 1240-2.1.times.Al.sub.R <T<1310-1.8.times.Al.sub.R (wherein Al.sub.R =acid soluble [Al]-27/14.times.[N]) and the strip is soaked for 180 sec or less, maintained at a temperature in the range of from 800.degree. to 950.degree. C. for 30 to 300 sec and then quenched.The grain-oriented electrical steel strip thus produced is not influenced by the variation in the [Al] and [N].Type: GrantFiled: October 22, 1992Date of Patent: November 16, 1993Assignee: Nippon Steel CorporationInventors: Katsuro Kuroki, Yasunari Yoshitomi, Hiroaki Masui, Tsutomu Haratani
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Patent number: 5215603Abstract: A method of primary recrystallization annealing grain-oriented electrical steel strip comprises the steps of conducting online measurement of the primary recrystallization grain diameter of the steel after primary recrystallization annealing and, based on the result of this measurement, controlling the primary recrystallization grain diameter of the steel after primary recrystallization annealing by varying either or both of the annealing temperature and the pass velocity during the primary recrystallization annealing. The method enables stable production of grain-oriented electrical steel strip exhibiting good secondary recrystallization and excellent electrical properties.Type: GrantFiled: July 17, 1991Date of Patent: June 1, 1993Assignee: Nippon Steel CorporationInventors: Tadashi Nakayama, Yasunari Yoshitomi
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Process for producing grain-oriented electrical steel sheet having excellent magnetic characteristic
Patent number: 5145533Abstract: 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.Type: GrantFiled: October 2, 1991Date of Patent: September 8, 1992Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Yozo Suga, Nobuyuki Takahashi, Yoshiyuki Ushigami, Tadashi Nakayama -
Patent number: 5039359Abstract: A process for producing a grain-oriented electrical steel sheet having a superior magnetic characteristic, comprising the steps of: hot-rolling a silicon steel slab comprising 0.021 to 0.100 wt % C, 2.5 to 4.5 wt % Si, one or more elements for forming inhibitors, and the balance consisting of Fe and unavoidable impurities, to form a hot-rolled sheet; coiling the hot-rolled sheet at a coiling temperature lower than 700.degree. C.; subsequently cold-rolling the hot-rolled sheet at a reduction of 80% or more, effected by a plurality of rolling passes, to a final product sheet thickness; holding the steel sheet at a temperature of from 50.degree. to 500.degree. C. for 1 minute or longer at least once at the stage between the rolling passes of the cold rolling; decarburization-annealing the cold-rolled sheet; and final-annealing the decarburization-annealed sheet.Type: GrantFiled: April 16, 1990Date of Patent: August 13, 1991Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Satoshi Arai
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Patent number: 4990779Abstract: The strains in crystals are evaluated by quantifying the sharpness of an electron channeling pattern and determining changes in the quantified sharpness of the electron channeling pattern. There is such a close correlation between the sharpness of the electron channeling pattern and the strains in crystals that the latter can be evaluated in terms of changes in the former. An apparatus for evaluating strains in crystals comprises a scanning electron microscope having a function to form an electron channeling pattern and an image analyzer having a function to quantify the sharpness of an electron channeling pattern.Type: GrantFiled: June 6, 1989Date of Patent: February 5, 1991Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Kuniteru Ohta, Shuichi Funaki
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Patent number: 4888066Abstract: A method of producing grain-oriented electrical steel sheet with a very high magnetic flux density, is characterized by increasing the partial pressure of the N.sub.2 in the annealing atmosphere at the intermediate stage between the start and the finish of the secondary recrystallization, and by ensuring the temperature differential in the coil does not exceed 100.degree. C. during changes to the annealing atmosphere. In addition, the rate of temperature increase at the hottest part of the coil is kept to a maximum of 13.degree. C./hr at least part of the time the coolest part of the coil is between 850.degree. C. and 1100.degree. C.Type: GrantFiled: September 16, 1988Date of Patent: December 19, 1989Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Kenzo Iwayama, Takeo Nagashima, Kenichi Yakashiro
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Patent number: 4824493Abstract: In the production of a grain-oriented electrical steel sheet by utilizing an AIN main inhibitor and at least twice cold-rolling with a heavy final reduction, improved magnetic properties are stably obtained by controlling the cooling speed (R) in the cooling process of a hot-rolled sheet annealing (R.gtoreq.5.degree.C./sec from 600.degree.-200.degree. C.) and by inter-pass aging (50.degree.-500.degree. C. for 1 minute or more) during the first cold-rolling.Type: GrantFiled: February 12, 1987Date of Patent: April 25, 1989Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Kenzo Iwayama
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Patent number: 4692193Abstract: A thin-gauge (0.10-0.23 mm thick) grain-oriented electrical steel sheet is produced by a process characterized by a decarburization which is carried out after the hot-rolling and before the final cold-rolling, after which the known, decarburization annealing and finishing annealing are carried out. The steel composition is adjusted to induce the secondary recrystallization by the AlN inhibitor. The reduction at the final cold-rolling is determined to be high to obtain a high magnetic flux density but tends to instabilize the secondary recrystallization unless the inventive decarburization is carried out.Type: GrantFiled: October 25, 1985Date of Patent: September 8, 1987Assignee: Nippon Steel CorporationInventors: Yasunari Yoshitomi, Katsuro Kuroki, Kenzo Iwayama
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Patent number: 4595426Abstract: Extremely low watt-loss of W.sub.17/50 .ltoreq.0.88 w/kg is provided by the combination of extremely low carbon, silicon and nitrogen contents; a thin sheet thickness of 0.15 to 0.23 mm; a high magnetic flux density B.sub.10 .gtoreq.1.89 T; and copresence of coarse and fine (2 mm or less) grains, the distance (ND) between the fine grains controlled to 2.0 to 8.0 mm.Type: GrantFiled: March 7, 1985Date of Patent: June 17, 1986Assignee: Nippon Steel CorporationInventors: Kenzo Iwayama, Yasunari Yoshitomi, Katsuro Kuroki