Futatsuka
Takayuki Futatsuka, Fukuyama JP
Patent application number | Description | Published |
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20090139611 | Galvanized Steel Sheet and Method for Producing the Same - A galvanized steel sheet excellent in strength-ductility balance and bake-hardenability as well as a method for producing the same are provided. The chemical components thereof include C, Si, Mn, P, S, Al, N and Cr at content ratios of 0.005 to 0.04%, 1.5% or lower, 1.0 to 2.0%, 0.10% or lower, 0.03% or lower, 0.01 to 0.1%, less than 0.008% and 0.2 to 1.0%, respectively, with Mn (mass %)+1.29Cr (mass %) being in the range of 2.1 to 2.8, and further include iron and unavoidable impurities as the balance. The structure thereof consists of a ferrite phase and a martensite phase with a volume fraction being at least 3.0% and less than 10%, the average particle diameter of the ferrite is larger than 6 μm and not more than 15 μm, and 90% or more of the martensite phase exists in a ferrite grain boundary. In addition, in the production process of such a galvanized steel sheet, a steel sheet obtained in a cold rolling step is annealed at a temperature being at least the Ac1 point and not more than the Ac3 point. | 06-04-2009 |
20110192504 | Method for producing a galvanized steel sheet - A method for producing a galvanized steel sheet including (a) melting a steel having a steel composition comprising 0.005 to 0.04 mass % C, 1.5 mass % or lower Si, 1.0 to 2.0 mass % Mn, 0.10 mass % or lower P, 0.03 mass % or lower S, 0.01 to 0.1 mass % Al, less than 0.008 mass % N and 0.2 to 1.0 mass % Cr, wherein Mn (mass %)+1.29 Cr (mass %) is 2.1 to 2.8, and the balance being iron and unavoidable impurities, (b) hot rolling and cold rolling the steel from step (a) to provide a steel sheet, and (c) annealing the steel sheet from step (c) at an annealing temperature of at least the Ac1 point and not more than the Ac3 point, wherein the galvanized steel sheet has a structure which includes a ferrite phase and a martensite phase with a volume fraction being at least 3.0% and less than 10%, the average particle diameter of the ferrite is larger than 6 μm and not more than 15 μm, and 90% or more of the martensite phase exists in a ferrite grain boundary. | 08-11-2011 |
Takayuki Futatsuka, Hiroshima JP
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20090014098 | High-Strength Hot-Dip Galvanized Steel Sheet Excellent in Formability and Method for Producing Same - 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. | 01-15-2009 |
20120204993 | CURVILINEAL CLOSED STRUCTURE PARTS AND METHOD FOR MANUFACTURING THE SAME - A method for manufacturing includes a polygonal shape closed structure part with a bent shape in the longitudinal direction only by press forming. The method uses two metal plates for manufacturing a curvilineal closed structure part and includes a press forming process of forming straight or bent folding lines in the longitudinal direction of the two metal plates at positions corresponding to a polygonal bent shape with a flange formed at least at one of the ends of the width direction of each plate, a process of forming a closed structure by laying the two metal plates to overlap each other flange to flange and end to end for ends without flanges and by welding the portions laid to overlap each other in the longitudinal direction of the metal plates, and a process of forming a polygonal shape closed structure having a bent shape in the longitudinal direction by holding both ends of the closed structure and by compressing it toward its central axis. | 08-16-2012 |
Takayuki Futatsuka, Tokyo JP
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20120171506 | CURVED PARTS AND METHOD FOR MANUFACTURING THE SAME - A curved-part forming method for obtaining a curved part by performing forming on a blank formed of a single metal plate, the method including a bending process in which the blank having a curved outline corresponding to a curve of the curved part in a longitudinal direction is bent into a sectional shape corresponding to a division portion of a sectional shape of the curved part; and a joining process in which two or more portions obtained by the bending process are joined together. | 07-05-2012 |