Patents by Inventor Fusato Kitano
Fusato Kitano 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: 7252722Abstract: A steel sheet containing 0.004 to 0.02% C, 1.0% or less Si, 0.7 to 3.0% Mn, 0.02 to 0.15% P, 0.02% or less S, 0.01 to 0.1% Al, 0.004% or less N, 0.2% or less Nb, by mass %, optionally Ti, Bi or at least one element selected from the group consisting of Cr Mo, Ni and Cu, and the balance being Fe; the Nb content satisfying a formula of (12/93)×Nb*/C?1.0, wherein Nb*=Nb?(93/14)×N, and wherein C, N and Nb designate the content in mass % of carbon, nitrogen and niobium, respectively; and a yield strength and an average grain size of the ferritic grains which satisfy a formula of YP??120×d+1280, wherein YP designates yield strength in MPa, and d designates an average size of ferritic grains in ?m.Type: GrantFiled: March 2, 2004Date of Patent: August 7, 2007Assignee: NKK CorporationInventors: Katsumi Nakajima, Takeshi Fujita, Toshiaki Urabe, Yuji Yamasaki, Fusato Kitano
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Publication number: 20060037677Abstract: The present invention relates to a high strength cold rolled steel sheet consisting of 0.015% or less of C, 1.5% or less of Si, 0.4 to 3% of Mn, 0.15% or less of P, 0.02% or less of S, 0.1 to 1% of sol.Al, 0.01% or less of N, 0.2% or less of Ti, by mass %, and the balance of Fe and inevitable impurities. In this steel sheet, 1?([Ti]/48)/([C]/12+[N]/14) is satisfied, in which [M] represents the content of the element M. Since having the superior deep drawability and the TS of 340 to 590 MPa, the high strength cold rolled steel sheet of the present invention is preferably used for automobiles parts difficult to be press formed, such as a side outer panel and a door inner panel.Type: ApplicationFiled: February 3, 2005Publication date: February 23, 2006Applicant: JFE STEEL CORPORATIONInventors: Yoshihiko Ono, Fusato Kitano, Yasunobu Nagataki, Yasushi Tanaka, Hisanori Ando
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Patent number: 6869691Abstract: The invention relates to a high strength hot-dip galvanized steel sheet consisting essentially of 0.03 to 0.25% C, 0.7% or less Si, 1.4 to 3.5% Mn, 0.05% or less P, 0.01% or less S, 0.05 to 1% Cr, 0.005 to 0.1% Nb, by mass, and balance of Fe, and being made of a composite structure of ferrite and secondary phase, and having an average grain size of the composite structure of 10 ?m or smaller. Since the high strength hot-dip galvanized steel sheet of the present invention hardly induces softening at HAZ during welding, it is applicable to structural members of automobiles for “Tailor Welded Blanks” (TWB).Type: GrantFiled: October 17, 2002Date of Patent: March 22, 2005Assignee: NKK CorporationInventors: Yasunobu Nagataki, Fusato Kitano, Kentaro Sato, Masahiro Iwabuchi, Akira Gamou
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Publication number: 20040238082Abstract: The present invention provides a high strength cold-rolled steel sheet, consisting essentially of, by mass %, 0.04 to 0.10% C, 0.5 to 1.5% Si, 1.8 to 3% Mn, 0.02% or less P, 0.01% or less S, 0.01 to 0.1% Sol. Al, 0.005% or less N, and the balance being iron and inevitable impurities, and having a structure which substantially comprises ferrite phase and martensite phase. Since the high strength cold-rolled steel sheet of the invention has ductility in which an elongation is 18% or more, excellent stretch-flangeability in which a hole-expanding ratio is 60% or more and a tensile strength of 780 MPa or more, it is favorable for use in a structural member of automobile.Type: ApplicationFiled: March 29, 2004Publication date: December 2, 2004Applicant: JFE STEEL CORPORATIONInventors: Kohei Hasegawa, Hiroshi Matsuda, Fusato Kitano, Kenji Kawamura, Hideyuki Tsurumaru
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Publication number: 20040168753Abstract: A steel sheet containing 0.004 to 0.02% C, 1.0% or less Si, 0.7 to 3.0% Mn, 0.02 to 0.15% P, 0.02% or less S, 0.01 to 0.1% Al, 0.004% or less N, 0.2% or less Nb, by mass %, optionally Ti, Bi or at least one element selected from the group consisting of Cr Mo, Ni and Cu, and the balance being Fe; the Nb content satisfying a formula of (12/93)×Nb*/C≧1.0, wherein Nb*=Nb−(93/14)×N, and wherein C, N and Nb designate the content in mass % of carbon, nitrogen and niobium, respectively; and a yield strength and an average grain size of the ferritic grains which satisfy a formula of YP≦−120×d+1280, wherein YP designates yield strength in MPa, and d designates an average size of ferritic grains in &mgr;m.Type: ApplicationFiled: March 2, 2004Publication date: September 2, 2004Applicant: NKK CORPORATIONInventors: Katsumi Nakajima, Takeshi Fujita, Toshiaki Urabe, Yuji Yamasaki, Fusato Kitano
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Patent number: 6743306Abstract: The steel sheet comprises: a ferritic phase having ferritic grains of 10 or more grain size number and ferritic grain boundaries; and at least one kind of Nb precipitates and Ti precipitates. The ferritic grain has a low density region with a low precipitate density in the vicinity of grain boundary. The low density region has a precipitate density of 60% or less to the precipitate density at center part of the ferritic grain. The steel sheet consists essentially of 0.002 to 0.02% C, 1% or less Si, 3% or less Mn, 0.1% or less P, 0.02% or less S, 0.01 to 0.1% sol.Al, 0.007% or less N, at least one element of 0.01 to 0.4% Nb and 0.005 to 0.3% Ti, by mass %, and the balance being Fe.Type: GrantFiled: January 11, 2002Date of Patent: June 1, 2004Assignee: NKK CorporationInventors: Katsumi Nakajima, Takeshi Fujita, Toshiaki Urabe, Yuji Yamasaki, Fusato Kitano
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Patent number: 6689229Abstract: A high strength cold rolled steel sheet consists essentially of 0.0040 to 0.01% C, not more than 0.05% Si, 0.1 to 1.0% Mn, 0.01 to 0.05% P, not more than 0.02% S, 0.01 to 0.1% sol.Al, not more than 0.004% N, 0.01 to 0.14% Nb, by weight, and a balance of substantially Fe and inevitable impurities, and having an n value of not less than 0.21 calculated from two points (1% and 10%) of nominal strain determined by the uniaxial tensile test, and a method for manufacturing the cold rolled steel sheet. The high strength cold rolled steel sheet has excellent combined formability, resistance to embrittlement during secondary operation, formability at welded portions, and anti-burring performance, and has a desirable surface appearance and uniformity of material in a coil, and thus can be desirably used for automobile exterior panels.Type: GrantFiled: April 15, 2002Date of Patent: February 10, 2004Assignee: NKK CorporationInventors: Takeshi Fujita, Fusato Kitano, Yoshihiro Hosoya, Toru Inazumi, Yuji Yamasaki, Masaya Morita, Yasunobu Nagataki, Kohei Hasegawa, Hiroshi Matsuda, Moriaki Ono
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Publication number: 20040020570Abstract: A high strength cold rolled steel sheet consists essentially of 0.0040 to 0.01% C, 0.05% or less Si, 0.1 to 1.0% Mn, 0.01 to 0.05% P, 0.02% or less S, 0.01 to 0.1% sol.Al, 0.004% or less N, 0.01 to 0.14% Nb, optionally 0.05% or less Ti, optionally 0.Type: ApplicationFiled: July 29, 2003Publication date: February 5, 2004Applicant: NKK CORPORATIONInventors: Takeshi Fujita, Fusato Kitano, Yoshihiro Hosoya, Toru Inazumi, Yuji Yamasaki, Masaya Morita, Yasunobu Nagataki, Kohei Hasegawa, Hiroshi Matsuda, Moriaki Ono
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Publication number: 20030106620Abstract: The invention relates to a high strength hot-dip galvanized steel sheet consisting essentially of 0.03 to 0.25% C, 0.7% or less Si, 1.4 to 3.5% Mn, 0.05% or less P, 0.01% or less S, 0.05 to 1% Cr, 0.005 to 0.1% Nb, by mass, and balance of Fe, and being made of a composite structure of ferrite and secondary phase, and having an average grain size of the composite structure of 10 &mgr;m or smaller. Since the high strength hot-dip galvanized steel sheet of the present invention hardly induces softening at HAZ during welding, it is applicable to structural members of automobiles for “Tailor Welded Blanks” (TWB).Type: ApplicationFiled: October 17, 2002Publication date: June 12, 2003Inventors: Yasunobu Nagataki, Fusato Kitano, Kentaro Sato, Masahiro Iwabuchi, Akira Gamou
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Patent number: 6524726Abstract: Disclosed is a cold-rolled steel sheet excellent in formability, panel shapeability and dent-resistance, comprising 0.005 to 0.015% by weight of C, 0.01 to 0.2% by weight of Si, 0.2 to 1.5% by weight of Mn, 0.01 to 0.07% by weight of P, 0.006 to 0.015% by weight of S, 0.01 to 0.08% by weight of sol. Al, not higher than 0.004% by weight of N (N≦0.004%), not higher than 0.003% by weight of O (O≦0.003%), 0.04 to 0.23% by weight of Nb, 1.0≦(Nb %×12)/(C %×93)≦3.0, and a balance of Fe and unavoidable impurities, said cold-rolled steel sheet meeting the relationship given below: exp(&egr;)×(5.29×exp(&egr;)−4.19)≦&sgr;/&sgr;0.2≦exp(&egr;)×(5.64×exp(&egr;)−4.49) where 0.002<&egr;≧0.096, &egr; represents a true strain, &sgr;0.2 represents a 0.2% proof stress, and &sgr; represents a true stress relative to &egr;.Type: GrantFiled: December 23, 1999Date of Patent: February 25, 2003Assignee: NKK CorporationInventors: Fusato Kitano, Masaya Morita, Yoshihiro Hosoya, Takeshi Fujita, Tadashi Inoue, Masahiro Iwabuchi, Takeo Ishii
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Patent number: 6494969Abstract: The present invention relates to a very low C—Nb cold rolled steel sheet giving 340 to 440 MPa of tensile strength. For example, the cold rolled steel sheet consists essentially of 0.0040 to 0.01% C, not more than 0.05% Si, 0.1 to 1.0% Mn, 0.01 to 0.05% P, not more than 0.02% S, 0.01 to 0.1% sol.Al, not more than 0.004% N, 0.01 to 0.14% Nb, by weight, and balance of substantially Fe and inevitable impurities, and has not less than 0.21 of n value calculated from two points (1% and 10%) of nominal strain determined by the uniaxial tensile test, and relates to a method for manufacturing the cold rolled steel sheet. The present invention provides a high strength cold rolled steel sheet for automobile exterior panels having excellent combined formability, resistance to embrittlement during secondary operation, formability at welded portions, anti-burring performance, good surface appearance, and uniformity of material in a coil.Type: GrantFiled: August 3, 2000Date of Patent: December 17, 2002Assignee: NKK CorporationInventors: Takeshi Fujita, Fusato Kitano, Yoshihiro Hosoya, Toru Inazumi, Yuji Yamasaki, Masaya Morita, Yasunobu Nagataki, Kohei Hasegawa, Hiroshi Matsuda, Moriaki Ono
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Publication number: 20020179206Abstract: The present invention relates to a very low C-Nb cold rolled steel sheet giving 340 to 440 MPa of tensile strength. For example, the cold rolled steel sheet consists essentially of 0.0040 to 0.01% C, not more than 0.05% Si, 0.1 to 1.0% Mn, 0.01 to 0.05% P, not more than 0.02% S, 0.01 to 0.1% sol.Al, not more than 0.004% N, 0.01 to 0.14% Nb, by weight, and balance of substantially Fe and inevitable impurities, and has not less than 0.21 of n value calculated from two points (1% and 10%) of nominal strain determined by the uniaxial tensile test, and relates to a method for manufacturing the cold rolled steel sheet. The present invention provides a high strength cold rolled steel sheet for automobile exterior panels having excellent combined formability, resistance to embrittlement during secondary operation, formability at welded portions, anti-burring performance, good surface appearance, and uniformity of material in a coil.Type: ApplicationFiled: April 15, 2002Publication date: December 5, 2002Applicant: NKK CORPORATIONInventors: Takeshi Fujita, Fusato Kitano, Yoshihiro Hosoya, Toru Inazumi, Yuji Yamasaki, Masaya Morita, Yasunobu Nagataki, Kohei Hasegawa, Hiroshi Matsuda, Moriaki Ono
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Publication number: 20020148536Abstract: The steel sheet comprises: a ferritic phase having ferritic grains of 10 or more grain size number and ferritic grain boundaries; and at least one kind of Nb precipitates and Ti precipitates. The ferritic grain has a low density region with a low precipitate density in the vicinity of grain boundary. The low density region has a precipitate density of 60% or less to the precipitate density at center part of the ferritic grain. The steel sheet consists essentially of 0.002 to 0.02% C, 1% or less Si, 3% or less Mn, 0.1% or less P, 0.02% or less S, 0.01 to o.1% sol.Al, 0.007% or less N, at least one element of 0.01 mass %, and the balance being Fe.Type: ApplicationFiled: January 11, 2002Publication date: October 17, 2002Applicant: NKK CORPORATIONInventors: Katsumi Nakajima, Takeshi Fujita, Toshiaki Urabe, Yuji Yamasaki, Fusato Kitano
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Patent number: 6440584Abstract: A hot-dip galvanized steel sheet is produced by rough rolling a steel, finish rolling the rough rolled steel at a temperature of Ar3 point or more, coiling the finish rolled steel at a temperature of 700° C. or less, and hot-dip galvanizing the coiled steel at a pre-plating heating temperature of Ac1 to Ac3. A continuous hot-dip galvanizing operation is performed by soaking a pickled strip at a temperature of 750 to 850° C., cooling the soaked strip to a temperature range of 600° C. or less at a cooling rate of 1 to 50° C. per second, hot-dip galvanizing the cooled strip, and cooling the galvanized strip so that the residence time at 400 to 600° C. is within 200 seconds. The steel sheet has a structure consisting essentially of ferrite and martensite.Type: GrantFiled: September 17, 2001Date of Patent: August 27, 2002Assignee: NKK CorporationInventors: Yasunobu Nagataki, Toshiaki Urabe, Fusato Kitano, Akio Kobayashi, Kunikazu Tomita, Shunsaku Node, Kozo Harada, Shogo Sato, Toru Inazumi
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Publication number: 20020088510Abstract: A hot-dip galvanized steel sheet is produced by rough rolling a steel, finish rolling the rough rolled steel at a temperature of Ar3 point or more, coiling the finish rolled steel at a temperature of 700° C. or less, and hot-dip galvanizing the coiled steel at a pre-plating heating temperature of Ac1 to Ac3. A continuous hot-dip galvanizing operation is performed by soaking a pickled strip at a temperature of 750 to 850° C., cooling the soaked strip to a temperature range of 600° C. or less at a cooling rate of 1 to 50° C. per second, hot-dip galvanizing the cooled strip, and cooling the galvanized strip so that the residence time at 400 to 600° C. is within 200 seconds. The steel sheet has a structure consisting essentially of ferrite and martensite.Type: ApplicationFiled: September 17, 2001Publication date: July 11, 2002Applicant: NKK CORPORATIONInventors: Yasunobu Nagataki, Toshiaki Urabe, Fusato Kitano, Akio Kobayashi, Kunikazu Tomita, Shunsaku Node, Kozo Harada, Shogo Sato, Toru Inazumi
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Patent number: 6273971Abstract: The present invention provides a method of manufacturing a cold rolled steel sheet and a hot-dip zinc-coated steel sheet having excellent surface properties, an excellent resistance to natural aging and an excellent dent resistance of panel and, thus, adapted to the manufacture of steel sheet for outer panels of vehicles. The method comprises the steps of preparing steel consisting of 0.005 to 0.012% by weight of C, 0.01 to 0.4% by weight of Si, 0.15 to 1.0% by weight of Mn, 0.01 to 0.08% by weight of P, at most 0.02% by weight of S, 0.01 to 0.1% by weight of sol. Al, at most 0.004% by weight of N, and at least one element selected from the group consisting of 0.01 to 0.2% by weight of Nb and 0.04 to 0.1% by weight of Ti, and satisfying the condition 1.2≦(12/93) (Nb%/C%)+(12/48) (Ti*%/C%)≦2.5, applying a hot rolling and a cold rolling to the steel, soaking the cold rolled steel sheet at T(° C.) meeting a formula Ac3≧T(° C.Type: GrantFiled: April 10, 2000Date of Patent: August 14, 2001Assignee: NKK CorporationInventors: Fusato Kitano, Takeshi Fujita, Tadashi Inoue, Michihiro Hiasa, Takeo Ishii
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Patent number: 5853903Abstract: A cold-rolled steel sheet or a zinc or zinc alloy layer coated steel sheet containing 0.0010 to 0.01 wt % of C and having a steel composition containing one or two kinds of 0.005 to 0.08 wt % of Nb and 0.01 to 0.07 wt % of Ti in the ranges given by {(12/93)Nb+(12/48)Ti*} .gtoreq.0.0005, 0.ltoreq.C-{(12/93)Nb+(12/48)Ti*}.ltoreq.0.0015, and Ti*=Ti-{(48/32)S+(48/14)N } , in which a bake hardenability BH f the steel sheet at 170.degree. C..times.20 min after 2% tensile prestrain is 10 to 35 MPa and the BH (MPa) and a yield strength YP (MPa) of the steel sheet satisfy the ranges given by BH.gtoreq.exp(-0.115.multidot.YP+23.0) and 0.67.multidot.BH+160.ltoreq.YP.ltoreq.-0.8.multidot.BH+280.Type: GrantFiled: April 28, 1997Date of Patent: December 29, 1998Assignee: NKK CorporationInventors: Yoshihiro Hosoya, Fusato Kitano, Yasunobu Nagataki