Patents by Inventor Shusaku Takagi

Shusaku Takagi 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).

  • Publication number: 20100132849
    Abstract: A high tensile-strength galvanized steel sheet includes C: at least 0.05% but less than 0.12%, Si: at least 0.01% but less than 0.35%, Mn: 2.0% to 3.5%, P: 0.001% to 0.020%, S: 0.0001% to 0.0030%, Al: 0.005% to 0.1%, N: 0.0001% to 0.0060%, Cr: more than 0.5% but not more than 2.0%, Mo: 0.01% to 0.50%, Ti: 0.010% to 0.080%, Nb: 0.010% to 0.080%, and B: 0.0001% to 0.0030%, the remainder being Fe and unavoidable impurities, wherein the high tensile-strength galvanized steel sheet has a microstructure that contains 20% to 70% by volume ferrite having an average grain size of 5 ?m or less. The high tensile-strength galvanized steel sheet has a tensile strength of at least 980 MPa, and excellent formability and weldability.
    Type: Application
    Filed: April 7, 2008
    Publication date: June 3, 2010
    Applicant: JFE STEEL CORPORATION
    Inventors: Shusaku Takagi, Hidetaka Kawabe, Kohei Hasegawa, Toshihiko Ooi, Yasuaki Okita, Michitaka Sakurai
  • Publication number: 20100104891
    Abstract: A high-strength galvanized steel sheet having excellent formability contains as a chemical component of steel on a mass percent basis: 0.05% to 0.3% of C; more than 0.60% to 2.0% of Si; 0.50% to 3.50% of Mn; 0.003% to 0.100% of P; 0.010% or less of S; 0.010% to 0.06% of Al; 0.007% or less of N; and the balance including Fe and inevitable impurities, and in the microstructure of the steel sheet, the standard deviation of nano-hardness is 1.50 GPa or less.
    Type: Application
    Filed: March 18, 2008
    Publication date: April 29, 2010
    Applicant: JFE STEEL CORPORATION
    Inventors: Tatsuya Nakagaito, Yoshitsugu Suzuki, Shusaku Takagi, Saiji Matsuoka, Takashi Kawano, Yoshiharu Sugimoto
  • Publication number: 20090214892
    Abstract: A high strength steel sheet and a method for manufacturing the same has superior phosphatability properties and hot-dip galvannealed properties besides a tensile strength of 950 MPa or more and a high ductility, and also having a small variation in mechanical properties with the change in annealing conditions.
    Type: Application
    Filed: February 18, 2009
    Publication date: August 27, 2009
    Applicants: JFE Steel Corporation, a corporation of Japan, ThyssenKrupp Steel AG, a corporation of Germany
    Inventors: Kenji Kawamura, Taro Kizu, Shusaku Takagi, Kohei Hasegawa, Hiroshi Matsuda, Akio Kobayashi, Yasunobu Nagataki, Yasuhi Tanaka, Thomas Heller, Brigitte Hammer, Jian Bian, Gunter Stich, Rolf Bode
  • Patent number: 7527700
    Abstract: The present invention relates to a high strength hot rolled steel sheet consisting of 0.04 to 0.15% C, 1.5% or less Si, 0.5 to 1.6% Mn, 0.04% or less P, 0.005% or less S, 0.04% or less Al, 0.03 to 0.15% Ti, 0.03 to 0.5% Mo, by mass, and balance of Fe and inevitable impurities, and having a microstructure consisting of ferrite containing precipitates, second phase of bainite and/or martensite, and other phase, wherein the percentage of the ferrite containing precipitates is 40 to 95%, and the percentage of the other phase is 5% or less. For example, the high strength hot rolled steel sheet having a thickness of 1.4 mm shows a tensile strength of 780 MPa or higher, an elongation of 22% or higher elongation, and a hole expansion ratio of 60% or higher, thus the steel sheet is suitable for reinforcing members automobile cabin and crash worthiness members of automobile.
    Type: Grant
    Filed: April 21, 2004
    Date of Patent: May 5, 2009
    Assignee: JFE Steel Corporation
    Inventors: Nobusuke Kariya, Shusaku Takagi, Tetsuo Shimizu, Tetsuya Mega, Kei Sakata, Hiroshi Takahashi
  • Publication number: 20090050244
    Abstract: The present invention provides a hot-rolled high strength steel sheet in which, without using expensive Mo, by effectively using Ti which is an inexpensive element and the amount of precipitation hardening of which is large, both ductility and stretch-flangeability are improved at a tensile strength of 780 MPa or higher, and excellent tensile fatigue properties are exhibited; and a method for producing the hot-rolled high strength steel sheet. A hot-rolled high strength steel sheet having a composition including, in percent by mass, C: 0.06% to 0.15%, Si: 1.2% or less, Mn: 0.5% to 1.6%, P: 0.04% or less, S: 0.005% or less, Al: 0.05% or less, and Ti: 0.03% to 0.
    Type: Application
    Filed: December 27, 2006
    Publication date: February 26, 2009
    Applicant: JFE STEEL CORPORATION
    Inventors: Koichi Nakagawa, Reiko Sugihara, Tetsuo Shimizu, Shusaku Takagi
  • Publication number: 20090014098
    Abstract: There is provided a high-strength hot-dip galvanized steel sheet having excellent formability, the steel sheet eliminating special pre-structure control and capable of being produced by using a hot-dip galvanized steel-sheet production line that is not capable of sufficiently ensuring an austempering time after annealing. A high-strength hot-dip galvanized steel sheet includes, on the basis of mass percent, 0.05-0.3% C, 1.4% or less (including 0%) Si, 0.08%-3% Mn, 0.003-0.1% P, 0.07% or less S, 0.1-2.5% Al, 0.1-0.5% Cr, and 0.007% or less N, Si+Al?0.5%, and the balance being Fe and incidental impurities, wherein the steel sheet has a retained austenite content of 3% or more by volume fraction, and wherein the average aspect ratio of retained austenite grains is 2.5 or less.
    Type: Application
    Filed: April 6, 2006
    Publication date: January 15, 2009
    Applicant: JFE Steel Corporation
    Inventors: Hiroshi Matsuda, Tatsuya Nakagaito, Takayuki Futatsuka, Shusaku Takagi, Yasunobu Nagataki
  • Publication number: 20060231176
    Abstract: The high tensile cold-rolled steel sheet consists essentially of 0.04 to 0.13% C, 0.3 to 1.2% Si, 1.0 to 3.5% Mn, 0.04% or less P, 0.01% or less S, 0.07% or less Al, by mass, and balance of Fe and inevitable impurities, has a microstructure containing 50% or larger area percentage of ferrite and 10% or larger area percentage of martensite, has 0.85 to 1.5 of ratio of intervals of the martensite in the rolling direction to those in the sheet thickness direction, and has 8 GPa or larger nano strength of the martensite. The high tensile cold-rolled steel sheet has a good strength-elongation balance, and shows excellent crashworthiness at about 10 s?1 of strain rate. Therefore, the high tensile cold-rolled steel sheet is suitable for reinforcing members for pillar and dashboard of automobile.
    Type: Application
    Filed: August 18, 2004
    Publication date: October 19, 2006
    Inventors: Shusaku Takagi, Tetsuo Shimizu, Naoki Nishiyama
  • Patent number: 6523416
    Abstract: A delayed fracture is effectively prevented by appropriately setting a shape and working stress, and working environment of a high strength member having more than 1,000 MPa of tensile strength. For this end, the relationship between a maximum value of diffusible hydrogen contents of unfailed specimens (Hc) and Weibull stress are found and the content of diffusible hydrogen entered into steel from the environment due to corrosion during the use of the steel member (He) is also found. Then, Weibull stress in the Hc that is equal to the He is found, thus determining the shape and working stress of the steel member so as to provide stress below the Weibull stress.
    Type: Grant
    Filed: August 29, 2001
    Date of Patent: February 25, 2003
    Assignees: Kawasaki Steel Corporation, National Institute For Material Science
    Inventors: Shusaku Takagi, Kaneaki Tsuzaki, Tadanobu Inoue
  • Publication number: 20020043111
    Abstract: A delayed fracture is effectively prevented by appropriately setting a shape and working stress, and working environment of a high strength member having more than 1,000 MPa of tensile strength. For this end, the relationship between a maximum value of diffusible hydrogen contents of unfailed specimens (Hc) and Weibull stress are found and the content of diffusible hydrogen entered into steel from the environment due to corrosion during the use of the steel member (He) is also found. Then, Weibull stress in the Hc that is equal to the He is found, thus determining the shape and working stress of the steel member so as to provide stress below the Weibull stress.
    Type: Application
    Filed: August 29, 2001
    Publication date: April 18, 2002
    Inventors: Shusaku Takagi, Kaneaki Tsuzaki, Tadanobu Inoue
  • Patent number: 6172446
    Abstract: A piezoelectric oscillator element (100) constituting a piezoelectric transformer is supported by lead frames (32, 34, 36). One of the ends of the lead frame (32) is welded to a primary side electrode (22) at a connection portion (31), and the other end is welded to a land (42). One of the ends of the lead frame (34) is welded to a primary side electrode (24) at a connection portion (33) and the other end is welded to a land (44). One of the ends of the lead frame (36) is welded to a secondary side electrode (26) at a connection portion (35) and the other end is welded to a land (46). The connection portions (31 and 33) are positioned at a node A of oscillation. Since the electrical and mechanical connection is achieved by the lead frames (32, 34, 36), the structure is simple, the thickness of the oscillator is easily reduced, and the oscillator is easily assembled.
    Type: Grant
    Filed: February 25, 1998
    Date of Patent: January 9, 2001
    Assignee: Mitsui Chemicals, Inc.
    Inventors: Kouichi Kanayama, Shusaku Takagi, Mitsunobu Yoshida, Yasushi Iwata
  • Patent number: 6147439
    Abstract: A piezoelectric substrate supporting structure for piezoelectric transformer is provided which, in the supporting and fixing of a piezoelectric substrate on a base plate or in an outer trim case, does not inhibit the vibration of the piezoelectric substrate, exhibits high impact resistance and enables stable supporting, is free from performance deterioration and enables simultaneously and easily performing an electrode takeoff from the piezoelectric substrate. Further, a piezoelectric transformer including the above piezoelectric substrate supporting structure is provided.
    Type: Grant
    Filed: June 23, 1998
    Date of Patent: November 14, 2000
    Assignee: Mitsui Chemicals, Inc.
    Inventors: Shusaku Takagi, Masamitsu Tanaka, Sigeru Bando, Tadao Sunahara, Katsuo Kono, Mitsunobu Yoshida, Yasushi Iwata
  • Patent number: 5558727
    Abstract: A high strength steel sheet for automobiles which exhibits excellent press-formability strength against impact resistance at a high strain rate is hot rolled under specific conditions, or is cold rolled from hot rolled sheet which is prepared under conventional conditions, with the cold rolled steel being annealed under specific conditions. The steel sheet comprises 0.010-0.10 wt % of C, not greater than 1.50 wt % of Si, 0.50-3.00 wt % of Mn, not greater than 0.010 wt % of S and 0.01-0.1 wt % of Al, and one kind or two kinds selected from 0.05-0.15 wt % of P and 0.5-1.5 wt % of Cr, and the balance being Fe and inevitable impurities and having a structure mainly composed of 2-30 vol % of martensite phase and a ferrite phase containing a solution C not greater than 0.0010 wt %.
    Type: Grant
    Filed: February 23, 1995
    Date of Patent: September 24, 1996
    Assignee: Kawasaki Steel Corporation
    Inventors: Kazuya Miura, Shusaku Takagi, Takaaki Hira, Toshiyuki Kato, Nobutaka Kurosawa