Patents by Inventor Hiroshi Akamizu
Hiroshi Akamizu 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: 9194015Abstract: A dual phase steel sheet with good bake-hardening properties is provided. The steel sheet is characterized in containing (in terms of percent by mass) C: no less than 0.06% and less than 0.25%; Si+Al: 0.5 to 3%; Mn: 0.5 to 3%; P: no more than 0.15%; and S: no more than 0.02%; and also meeting the following condition (in terms of space factor) that retained austenite is at least 3%, bainite is at least 30%, and ferrite is no more than 50%, and further characterized in differing in stress larger than 50 MPa before and after application of 2% pre-strain and ensuing heat treatment for paint baking at 170° C. for 20 minutes. The steel sheet has well-balanced strength and workability, exhibits good bake-hardening properties at the time of paint baking, and offers good resistance to natural aging.Type: GrantFiled: June 3, 2009Date of Patent: November 24, 2015Assignee: Kobe Steel, Ltd.Inventors: Shushi Ikeda, Koichi Makii, Hiroshi Akamizu
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Patent number: 9074272Abstract: A high-strength cold-rolled steel sheet excellent in uniform elongation, including in percent by mass: 0.10-0.28% of C; 1.0-2.0% of Si; and 1.0-3.0% of Mn, and the structures of the same having the space factors below to the entire structure: 30-65% of bainitic ferrite; 30-50% of polygonal ferrite; and 5-20% of residual austenite.Type: GrantFiled: March 28, 2006Date of Patent: July 7, 2015Assignee: Kobe Steel, Ltd.Inventors: Hiroshi Akamizu, Yoichi Mukai, Shushi Ikeda, Koichi Sugimoto
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Patent number: 8597439Abstract: A high-strength cold rolled steel sheet contains: 0.10 to 0.28% of C, 1.0 to 2.0% of Si, 1.0 to 3.0% of Mn, and 0.03 to 0.10% of Nb in terms of % by mass, Al is controlled to 0.5 or less, P is controlled to 0.15% or less, and S is controlled to 0.02% or less, and residual austenite accounts for 5 to 20%, bainitic ferrite accounts for 50% or more, and polygonal ferrite accounts for 30% or less (containing 0%), of the entire structure, and a mean number of residual austenite blocks is 20 or more as determined when the random area (15 ?m×15 ?m) is observed by EBSP (electron back scatter diffraction pattern).Type: GrantFiled: December 17, 2009Date of Patent: December 3, 2013Assignee: Kobe Steel, Ltd.Inventors: Shushi Ikeda, Yoichi Mukai, Hiroshi Akamizu, Koichi Makii, Koichi Sugimoto, Shunichi Hashimoto, Kenji Saito
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Patent number: 7887648Abstract: The invention relates to an ultrahigh-strength thin steel sheet excellent in the hydrogen embrittlement resistance, the steel sheet including, by weight %, 0.10 to 0.60% of C, 1.0 to 3.0% of Si, 1.0 to 3.5% of Mn, 0.15% or less of P, 0.02% or less of S, 1.5% or less of Al, 0.003 to 2.0% of Cr, and a balance including iron and inevitable impurities; in which grains of residual austenite have an average axis ratio (major axis/minor axis) of 5 or more, the grains of the residual austenite have an average minor axis length of 1 ?m or less, and the grains of the residual austenite have a nearest-neighbor distance between the grains of 1 ?m or less.Type: GrantFiled: December 28, 2006Date of Patent: February 15, 2011Assignee: Kobe Steel, Ltd.Inventors: Junichiro Kinugasa, Fumio Yuse, Yoichi Mukai, Shinji Kozuma, Hiroshi Akamizu, Kouji Kasuya, Muneaki Ikeda, Koichi Sugimoto
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Patent number: 7833363Abstract: A high-strength forged part is disclosed which comprises a base phase structure, comprising 30% or more of ferrite in terms of a space factor, and a second phase structure, comprising bainite and/or martensite, and retained austenite having an average gain diameter of 5 ?m or less and a content represented by 50X[C]<[V?R]<150x[C], wherein [V?R] represents a space factor of the retained austenite (?R) and [C] represents the mass % of C in the forged part. Furthermore, a high-strength forged part is disclosed which comprises a base phase structure, comprising 50% or more of tempered bainite or tempered martensite in terms of a space factor, and a second phase structure, comprising martensite and 3% to 30% retained austenite in terms of a space factor, wherein the portion of the retained austenite and martensite having an aspect ratio of 2 or less is 25% or less in terms of a space factor.Type: GrantFiled: October 18, 2007Date of Patent: November 16, 2010Assignee: Kobe Steel, Ltd.Inventors: Shushi Ikeda, Koichi Makii, Hiroshi Akamizu, Yoichi Mukai, Koh-ichi Sugimoto
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Patent number: 7767036Abstract: A high-strength cold-rolled steel sheet exhibiting an excellent strength-workability balance, including in percent by mass: 0.10-0.25% of C; 1.0-2.0% of Si; 1.5-3.0% of Mn; 0.01% or less (not including 0%) of P; 0.005% or less (not including 0%) of S; 0.01-3.0% of Al; and remaining part consisting of iron and inevitable impurities, wherein the space factor of bainitic ferrite to the entire structure is 70% or more, the space factor of residual austenite to the entire structure is 5-20%, the hardness (HV) is 270 or greater, and the half-value width of an X-ray diffraction peak on a (200)-surface of ?-iron is 0.220 degrees or smaller.Type: GrantFiled: March 29, 2006Date of Patent: August 3, 2010Assignee: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Takahiro Kashima, Yoichi Mukai, Hiroshi Akamizu, Koichi Sugimoto
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Publication number: 20100092332Abstract: To provide a high-strength cold rolled steel sheet that has well-balanced tensile strength and elongation as well as well-balanced tensile strength and stretch-flangeability, and a plated steel sheet manufactured by plating the steel sheet. The high-strength cold rolled steel sheet contains: 0.10 to 0.28% of C, 1.0 to 2.0% of Si, 1.0 to 3.0% of Mn, and 0.03 to 0.10% of Nb in terms of % by mass, wherein the content of Al is controlled to 0.5 or less, the content of P is controlled to 0.15% or less, and the content of S is controlled to 0.02% or less, and wherein residual austenite accounts for 5 to 20%, bainitic ferrite accounts for 50% or more, and polygonal ferrite accounts for 30% or less (containing 0%), of the entire structure, and wherein a mean number of residual austenite blocks is 20 or more as determined when the random area (15 ?m×15 ?m) is observed by EBSP (electron back scatter diffraction pattern).Type: ApplicationFiled: December 17, 2009Publication date: April 15, 2010Applicant: Kabushiki Kaisha Kobe Seiko Sho(Kobe Steel, Ltd.)Inventors: Shushi IKEDA, Yoichi Mukai, Hiroshi Akamizu, Koichi Makii, Koichi Sugimoto, Shunichi Hashimoto, Kenji Saito
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Patent number: 7637137Abstract: A press forming method which can prevent a stretch-flange crack while using conventional press forming equipment at a time of press forming a formed member with flange includes steps of constructing a blank for press forming with a base body blank portion corresponding to flat base body of the formed member, and a concave flange blank portion formed by bending on a concave outer peripheral edge of the base body blank portion. The concave blank portion is constituted by a convex flange blank portion in which a stretch-flange deformation is generated, and an adjacent flange blank portion which is adjacent thereto. An outer peripheral edge of the convex flange blank portion is formed such that one end exists between two points on a profile line corresponding to an outer peripheral edge of the adjacent flange blank portion, the other end exists between two other points, and the one end and the other end are smoothly connected between the straight lines.Type: GrantFiled: December 9, 2008Date of Patent: December 29, 2009Assignee: Kobe Steel, Ltd.Inventors: Hiroshi Akamizu, Jiro Iwaya
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Publication number: 20090242085Abstract: A dual phase steel sheet with good bake-hardening properties is provided. The steel sheet is characterized in containing (in terms of percent by mass) C: no less than 0.06% and less than 0.25%; Si+Al: 0.5 to 3%; Mn: 0.5 to 3%; P: no more than 0.15%; and S: no more than 0.02%; and also meeting the following condition (in terms of space factor) that retained austenite is at least 3%, bainite is at least 30%, and ferrite is no more than 50%, and further characterized in differing in stress larger than 50 MPa before and after application of 2% pre-strain and ensuing heat treatment for paint baking at 170° C. for 20 minutes. The steel sheet has well-balanced strength and workability, exhibits good bake-hardening properties at the time of paint baking, and offers good resistance to natural aging.Type: ApplicationFiled: June 3, 2009Publication date: October 1, 2009Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd)Inventors: Shushi IKEDA, Koichi Makii, Hiroshi Akamizu
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Publication number: 20090238713Abstract: The invention relates to an ultrahigh-strength thin steel sheet excellent in the hydrogen embrittlement resistance, the steel sheet including, by weight %, 0.10 to 0.60% of C, 1.0 to 3.0% of Si, 1.0 to 3.5% of Mn, 0.15% or less of P, 0.02% or less of S, 1.5% or less of Al, 0.003 to 2.0% of Cr, and a balance including iron and inevitable impurities; in which grains of residual austenite have an average axis ratio (major axis/minor axis) of 5 or more, the grains of the residual austenite have an average minor axis length of 1 ?m or less, and the grains of the residual austenite have a nearest-neighbor distance between the grains of 1 ?m or less.Type: ApplicationFiled: December 28, 2006Publication date: September 24, 2009Applicants: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.), Shinshu TLO Co., Ltd.Inventors: Junichiro Kinugasa, Fumio Yuse, Yoichi Mukai, Shinji Kozuma, Hiroshi Akamizu, Kouji Kasuya, Muneaki Ikeda, Koichi Sugimoto
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Patent number: 7591977Abstract: To provide a high strength and low yield ratio cold rolled steel sheet having high elongation property and high flange drawing property, or a plated steel sheet made by plating the same. The high strength and low yield ratio cold rolled steel sheet or the plated steel sheet made by plating the same has such a constitution as 0.10 to 0.25% of C, 1.0 to 2.0% of Si and 1.5 to 3.0% of Mn, are contained in terms of weight percentage, while other elements are controlled such as Al within 0.2%, P within 0.15% and S within 0.02%, with residual austenite occupying at least 5%, bainitic ferrite occupying at least 60% (preferably 80% or more), and polygonal ferrite within 20% (containing 0%), so that a tensile strength is 980 MPa or higher, while an elongation (El in %), a flange drawing property (?in %), a tensile strength (TS in MPa) and a yield strength (YP in MPa) satisfy the following inequality (1): [(El ×?×TS)/YP]?645.Type: GrantFiled: January 28, 2005Date of Patent: September 22, 2009Assignee: Kabuhsiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Shushi Ikeda, Hiroshi Akamizu, Koichi Makii, Yoichi Mukai, Koichi Sugimoto
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Patent number: 7553380Abstract: Disclosed is a dual-phase steel sheet having low yield ratio, excellent in the balance for strength-elongation and for strength-stretch flange formability, and also excellent in bake hardening property containing (on the mass % basis). C: 0.01-0.20%, Si: 0.5% or less, Mn: 0.5-3%, sol.Al: 0.06% or less (inclusive 0%), P: 0.15% or less (exclusive 0%), and S: 0.02% or less (inclusive 0?), and in which the matrix phase contains tempered martensite; tempered martensite and ferrite; tempered bainite; or tempered bainite and ferrite, and the second phase comprises 1 to 30% of martensite at an area ratio based on the entire structure.Type: GrantFiled: October 3, 2006Date of Patent: June 30, 2009Assignee: Kobe Steel, Ltd.Inventors: Shushi Ikeda, Hiroshi Akamizu, Shunichi Hashimoto, Takahiro Kashima, Tatsuya Asai
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Publication number: 20090145310Abstract: The invention provides a press forming method which can prevent a stretch-flange crack while using conventional press forming equipment, at a time of press forming a formed member with flange. The method of the invention is characterized by a shape of a blank for press forming, and a blank in accordance with the invention is constructed by a base body blank portion corresponding to a flat base body of the formed member, and a concave flange blank portion formed by bending on a concave outer peripheral edge of the base body blank portion. The concave blank portion is constituted by a convex flange blank portion in which a stretch-flange deformation is generated, and an adjacent flange blank portion which is adjacent thereto.Type: ApplicationFiled: December 9, 2008Publication date: June 11, 2009Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Hiroshi AKAMIZU, Jiro Iwaya
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Publication number: 20080251161Abstract: A high-strength cold-rolled steel sheet exhibiting an excellent strength-workability balance, including in percent by mass: 0.10-0.25% of C; 1.0-2.0% of Si; 1.5-3.0% of Mn; 0.01% or less (not including 0%) of P; 0.005% or less (not including 0%) of S; 0.01-3.0% of Al; and remaining part consisting of iron and inevitable impurities, wherein the space factor of bainitic ferrite to the entire structure is 70% or more, the space factor of residual austenite to the entire structure is 5-20%, the hardness (HV) is 270 or greater, and the half-value width of an X-ray diffraction peak on a (200)-surface of ?-iron is 0.220 degrees or smaller.Type: ApplicationFiled: March 29, 2006Publication date: October 16, 2008Applicants: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.), Shinshu TLO Co., Ltd.Inventors: Takahiro Kashima, Yoichi Mukai, Hiroshi Akamizu, Koichi Sugimoto
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Publication number: 20080251160Abstract: A high-strength cold-rolled steel sheet excellent in uniform elongation, including in percent by mass: 0.10-0.28% of C; 1.0-2.0% of Si; and 1.0-3.0% of Mn, and the structures of the same having the space factors below to the entire structure: 30-65% of bainitic ferrite; 30-50% of polygonal ferrite; and 5-20% of residual austenite.Type: ApplicationFiled: March 28, 2006Publication date: October 16, 2008Applicants: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd), Shinshu Tlo Co., Ltd.Inventors: Hiroshi Akamizu, Yoichi Mukai, Shushi Ikeda, Koichi Sugimoto
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Patent number: 7413617Abstract: The present invention provide a TRIP-type composite structure steel plate of the TPF steel type in which elongation and stretch flange formability at room temperature are improved by controlling the morphology of the second-phase structure. In a composite structure sheet steel comprising 0.02 to 0.12% C, 0.5 to 2.0% Si+Al and 1.0 to 2.0% Mn, with the remainder being Fe and unavoidable impurities, and comprising 80% or more polygonal ferrite (steel structure space factor) and 1 to 7% retained austenite, with the remainder being bainite and/or martensite, wherein the elongation and stretch flange formability of the composite sheet steel are improved by reducing the number of bulky, massive second phases with an aspect ratio of 1:3 or less and a mean grain size of 0.5 ?m or more in the second phase of this composite structure, which comprises retained austenite and martensite.Type: GrantFiled: December 1, 2005Date of Patent: August 19, 2008Assignees: Kabushiki Kaisha Kobe Seiko Sho, Shinshu TLO Co., Ltd.Inventors: Shushi Ikeda, Koichi Sugimoto, Yoichi Mukai, Hiroshi Akamizu
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Publication number: 20080092996Abstract: A high-strength forged part is disclosed which comprises a base phase structure, comprising 30% or more of ferrite in terms of a space factor, and a second phase structure, comprising bainite and/or martensite, and retained austenite having an average grain diameter of 5 ?m or less and a content represented by 50X[C]<[V?R]<150x[C], wherein [V?R] represents a space factor of the retained austenite (?R) and [C] represents the mass % of C in the forged part. Furthermore, a high-strength forged part is disclosed which comprises a base phase structure, comprising 50% or more of tempered bainite or tempered martensite in terms of a space factor, and a second phase structure, comprising martensite and 3% to 30% retained austenite in terms of a space factor, wherein the portion of the retained austenite and martensite having an aspect ratio of 2 or less is 25% or less in terms of a space factor.Type: ApplicationFiled: October 18, 2007Publication date: April 24, 2008Applicant: KABUSHIKI KAISHA KOBE SEIKO SHOInventors: Shushi Ikeda, Koichi Makii, Hiroshi Akamizu, Yoichi Mukai, Koh-ichi Sugimoto
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Patent number: 7314532Abstract: A high-strength forged part is disclosed which comprises a base phase structure, comprising 30% or more of ferrite in terms of a space factor, and a second phase structure, comprising bainite and/or martensite, and retained austenite having an average grain diameter of 5 ?m or less and a content represented by 50×[C]<[V?R]<150×[C], wherein [V?R] represents a space factor of the retained austenite (?R) and [C] represents the mass % of C in the forged part. Furthermore, a high-strength forged part is disclosed which comprises a base phase structure, comprising 50% or more of tempered bainite or tempered martensite in terms of a space factor, and a second phase structure, comprising martensite and 3% to 30% retained austenite in terms of a space factor, wherein the portion of the retained austenite and martensite having an aspect ratio of 2 or less is 25% or less in terms of a space factor.Type: GrantFiled: February 25, 2004Date of Patent: January 1, 2008Assignee: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Shushi Ikeda, Koichi Makii, Hiroshi Akamizu, Yoichi Mukai, Koh-ichi Sugimoto
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Publication number: 20070023113Abstract: Disclosed is a dual-phase steel sheet having low yield ratio, excellent in the balance for strength-elongation and for strength-stretch flange formability, and also excellent in bake hardening property containing (on the mass % basis). C: 0.01-0.20%, Si: 0.5% or less, Mn: 0.5-3%, sol.Al: 0.06% or less (inclusive 0%), P: 0.15% or less (exclusive 0%), and S: 0.02% or less (inclusive 0?), and in which the matrix phase contains tempered martensite; tempered martensite and ferrite; tempered bainite; or tempered bainite and ferrite, and the second phase comprises 1 to 30% of martensite at an area ratio based on the entire structure.Type: ApplicationFiled: October 3, 2006Publication date: February 1, 2007Applicant: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd)Inventors: Shushi Ikeda, Hiroshi Akamizu, Shunichi Hashimoto, Takahiro Kashima, Tatsuya Asai
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Patent number: 7090731Abstract: A high strength steel sheet having (2-1) a base phase structure, the base phase structure being tempered martensite or tempered bainite and accounting for 50% or more in terms of a space factor relative to the whole structure, or the base phase structure comprising tempered martensite or tempered bainite which accounts for 15% or more in terms of a space factor relative to the whole structure and further comprising ferrite, the tempered martensite or the tempered bainite having a hardness which satisfies the relation of Vickers hardness (Hv)?500[C]+30[Si]+3[Mn]+50 where [ ] represents the content (mass %) of each element, and (2-2) a second phase structure comprising retained austenite which accounts for 3 to 30% in terms of a space factor relative to the whole structure and optionally further comprising bainite and/or martensite, the retained austenite having a C concentration (C?R) of 0.8% or more.Type: GrantFiled: January 31, 2002Date of Patent: August 15, 2006Assignee: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)Inventors: Takahiro Kashima, Shunichi Hashimoto, Shushi Ikeda, Hiroshi Akamizu, Koh-ichi Sugimoto, Akihiko Nagasaka, Akinobu Kanda, Ryo Kikuchi