Patents by Inventor Kunio Hayashi
Kunio Hayashi 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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Publication number: 20200115771Abstract: A high-strength hot-dip galvanized steel sheet contains predetermined amounts of C, Si, Mn, P, S, N, O, sol. Al, Ti, and B, 0.1 to 1.5 mass % of Cr+2×Mo, and a balance in a form of Fe and inevitable impurities. A steel structure includes, in area %, ferrite: 1 to 50%, martensite: 20 to 70%, residual austenite: 0 to 5%, pearlite: 0 to 5%, MA and cementite having 0.2 ?m or more grain size: 0 to 5% in total, and a balance in a form of bainite. A number density of MA or cementite having 0.2 ?m or more grain size and isolated in ferrite or bainite grains is 100 pcs/1000 ?m2 or less, and an average hardness of martensite is in a range from 330 to 500 Hv.Type: ApplicationFiled: March 22, 2018Publication date: April 16, 2020Applicant: NIPPON STEEL CORPORATIONInventors: Takafumi YOKOYAMA, Yuji YAMAGUCHI, Masahiro NAKATA, Kunio HAYASHI, Satoshi UCHIDA, Takuma KAWANAKA
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Publication number: 20200094525Abstract: A steel sheet for hot stamping includes a steel structure represented by an area fraction of bainite, fresh martensite and tempered martensite: 80% or more in total, and a product of a number density (pieces/?m2) of carbides and a proportion of carbides precipitated into prior austenite grains in carbides: 0.50 or more.Type: ApplicationFiled: January 17, 2017Publication date: March 26, 2020Applicant: NIPPON STEEL CORPORATIONInventors: Genki ABUKAWA, Kunio HAYASHI, Kazuo HIKIDA, Kaoru KAWASAKI
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Publication number: 20200040435Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 50% to 95%, granular bainite: 5% to 48%, martensite: 2% to 30%, and upper bainite, lower bainite, tempered martensite, retained austenite, and pearlite: 5% or less in total.Type: ApplicationFiled: January 25, 2017Publication date: February 6, 2020Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Katsuya NAKANO, Kunio HAYASHI, Yuri TODA, Eisaku SAKURADA, Akihiro UENISHI
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Publication number: 20200024706Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 30% to 50%, granular bainite: 5% to 20%, martensite: 30% to 55%, bainite: less than 35%, and retained austenite and pearlite: 10% or less in total. Preferably, of the steel sheet, a tensile strength is 1180 MPa or more, elongation is 10% or more, and a hole expansion value is 20% or more. Further preferably, a VDA bending angle in the case where a thickness is set to t (mm) is “7.69t2?38.4t+109” or more.Type: ApplicationFiled: January 30, 2017Publication date: January 23, 2020Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Katsuya NAKANO, Kunio HAYASHI, Yuri TODA, Eisaku SAKURADA, Akihiro UENISHI
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Publication number: 20200010919Abstract: High strength steel sheet having a tensile strength of 800 MPa or more comprising a middle part in sheet thickness and a soft surface layer arranged at one side or both sides of the middle part in sheet thickness, wherein each soft surface layer has a thickness of more than 10 ?M and 30% or less of the sheet thickness, the soft surface layer has an average Vickers hardness of more than 0.60 time and 0.90 time or less the average Vickers hardness of the sheet thickness 1/2 position, and the soft surface layer has a nano-hardness standard deviation of 0.8 or less is provided.Type: ApplicationFiled: February 20, 2018Publication date: January 9, 2020Applicant: NIPPON STEEL CORPORATIONInventors: Yuya SUZUKI, Katsuya NAKANO, Genki ABUKAWA, Kunio HAYASHI
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Patent number: 10501832Abstract: A base material (13) included in a plated steel sheet (1) includes a structure, at a ¼ sheet thickness position, represented by, in volume fraction: tempered martensite: 3.0% or more; ferrite: 4.0% or more; and retained austenite: 5.0% or more. An average hardness of the tempered martensite in the base material (13) is 5 GPa to 10 GPa, and a part or all of the tempered martensite and the retained austenite in the base material form an M-A. A volume fraction of ferrite in a decarburized ferrite layer (12) included in the plated steel sheet (1) is 120% or more of the volume fraction of the ferrite in the base material (13) at the ¼ sheet thickness position, an average grain diameter of the ferrite in the decarburized ferrite layer (12) is 20 ?m or less, a thickness of the decarburized ferrite layer (12) is 5 ?m to 200 ?m, a volume fraction of tempered martensite in the decarburized ferrite layer (12) is 1.0 volume% or more, a number density of the tempered martensite in the decarburized ferrite layer (12) is 0.Type: GrantFiled: April 22, 2016Date of Patent: December 10, 2019Assignee: NIPPON STEEL CORPORATIONInventors: Koutarou Hayashi, Akihiro Uenishi, Masaharu Kameda, Jun Haga, Kunio Hayashi, Kohichi Sano, Hiroyuki Kawata
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Publication number: 20190330721Abstract: A steel sheet includes a predetermined chemical composition, and includes a steel structure represented by, in a volume fraction, tempered martensite and bainite: 70% or more and less than 92% in total, retained austenite: 8% or more and less than 30%, ferrite: less than 10%, fresh martensite: less than 10%, and pearlite: less than 10%. A number density of iron-base carbides in tempered martensite and lower bainite is 1.0×106 (pieces/mm2) or more, and an effective crystal grain diameter of tempered martensite and bainite is 5 ?m or less.Type: ApplicationFiled: September 21, 2016Publication date: October 31, 2019Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kunio HAYASHI, Masafumi AZUMA
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Publication number: 20190330711Abstract: A blank material is formed from a steel sheet, a first quenching of the blank material is performed, and a second quenching of the blank material is performed after the first quenching. When the first quenching is performed, the blank material is heated to a first temperature of not lower than (Ac3 point—50)° C. nor higher than 1200° C. at an average heating rate of 2° C./sec or more, and the blank material is cooled from the first temperature to a second temperature of 250° C. or lower. When the second quenching is performed, the blank material is heated from the second temperature to a third temperature of not lower than (Ac3 point—50)° C. nor higher than 1200° C. at an average heating rate of 2° C./sec or more, and the blank material is cooled from the third temperature to a fourth temperature of 250° C. or lower. Forming of the blank material is performed in the first quenching or the second quenching or both of the above.Type: ApplicationFiled: January 17, 2017Publication date: October 31, 2019Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Genki ABUKAWA, Kunio HAYASHI, Kazuo HIKIDA, Kaoru KAWASAKI
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Publication number: 20190249282Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 50% to 95%, granular bainite: 5% to 48%, tempered martensite: 2% to 30%, upper bainite, lower bainite, fresh martensite, retained austenite, and pearlite: 5% or less in total, and the product of the area fraction of the tempered martensite and a Vickers hardness of the tempered martensite: 800 to 10500.Type: ApplicationFiled: January 31, 2017Publication date: August 15, 2019Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Katsuya NAKANO, Kunio HAYASHI, Yuri TODA, Eisaku SAKURADA, Akihiro UENISHI
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Publication number: 20190226046Abstract: A steel sheet according to an aspect of the present invention has a chemical composition within a predetermined range; in which a metallographic structure at a thickness ¼ portion includes, by unit area %, ferrite: 10% or more and less than 50%, granular bainite: 5% or more and less than 50%, and martensite: 20% or more and less than 60%; in the metallographic structure at the thickness ¼ portion, a total of upper bainite, lower bainite, residual austenite, and pearlite is 0% or more and less than 15% by unit area %; at the thickness ¼ portion, a product of an area ratio Vm of the martensite and an average hardness Hv of the martensite is 12,000 to 34,000; and a tensile strength is 980 MPa or higher.Type: ApplicationFiled: September 13, 2016Publication date: July 25, 2019Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yuri TODA, Kunio HAYASHI, Katsuya NAKANO, Hiroyuki KAWATA, Akihiro UENISHI
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Publication number: 20190218652Abstract: In a metal coated steel sheet, a chemical composition contains, in mass %, at least C: 0.03% to 0.70%, Si: 0.25% to 2.50%, Mn: 1.00% to 5.00%, P: 0.100% or less, S: 0.010% or less, sol. Al: 0.001% to 2.500, N: 0.020% or less, and a balance composed of iron and impurities, a metal structure contains greater than 5.0 vol % of retained austenite and greater than 5.0 vol % of tempered martensite, and satisfies a C content in the retained austenite being 0.85 mass % or more.Type: ApplicationFiled: October 19, 2016Publication date: July 18, 2019Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Jun HAGA, Kohichi SANO, Koutarou HAYASHI, Kunio HAYASHI, Masaharu KAMEDA, Akihiro UENISHI, Hiroyuki KAWATA
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Patent number: 10350701Abstract: A spot welding method able to simply prevent liquid metal embrittlement cracks in spot welding of plated steel sheets, comprising, before spot welding, removing the plating at least in a zone including the inside of a circle centered at a scheduled location where the center of the nugget is formed and having an outer circumference of the inside of the outer edge of a weld affected zone or a zone at the mated surfaces of the steel sheets to be welded at the inside of a circle sharing a center of a scheduled location becoming the center of the nugget formed at the mated surfaces of the steel sheets and having an outer circumference of the inside of the outer edge of a weld affected zone.Type: GrantFiled: March 30, 2016Date of Patent: July 16, 2019Assignee: NIPPON STEEL CORPORATIONInventors: Yasunobu Miyazaki, Fuminori Watanabe, Chisato Wakabayashi, Kunio Hayashi, Hiroyuki Kawata, Seiji Furusako, Sho Matsui
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Publication number: 20190177810Abstract: A cold-rolled steel sheet includes, by mass %: C: 0.020% or more and 0.080% or less; Si: 0.20% or more and 1.00% or less; Mn: 0.80% or more and 2.30% or less; and Al: 0.010% or more and 0.100% or less; and further includes: one or more of Nb and Ti which satisfy a requirement of 0.005%?Nb+Ti<0.030%, in which a structure consists of, ferrite, bainite, and other phases, an area ratio of the ferrite is 80% or more and less than 95%, an area ratio of a non-recrystallization ferrite in the ferrite is 1% or more and less than 10%, an area ratio of the bainite is 5% or more and 20% or less, a total amount of the other phases is less than 8%, an equivalent circle diameter of a carbonitride including one or both of Nb and Ti is 1 nm or more and 10 nm or less, and a tensile strength is 590 MPa or more.Type: ApplicationFiled: February 19, 2019Publication date: June 13, 2019Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yusuke KONDO, Kunio HAYASHI, Toshio OGAWA, Naoki MATSUTANI, Koichi GOTO
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Publication number: 20190169729Abstract: A hot-dip galvanized steel sheet includes: a predetermined chemical composition; and a steel structure represented by: in terms of area ratio, polygonal ferrite: 10% or less; upper bainite: 20% or less; retained austenite: 5% or less; and martensite: 70% or more, in which: martensite having Fe carbides at a number density of 1×106/mm2 or more is contained by 50% or more, in terms of area ratio, with respect to the entire amount of martensite; and the steel structure has an average effective crystal grain diameter of 5.0 ?m or less.Type: ApplicationFiled: July 15, 2016Publication date: June 6, 2019Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Takafumi YOKOYAMA, Kunio HAYASHI, Masafumi AZUMA, Eisaku SAKURADA, Hiroyuki KAWATA, Genki ABUKAWA
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Patent number: 10266928Abstract: A cold-rolled steel sheet satisfies that an average pole density of an orientation group of {100}<011> to {223}<110> is 1.0 to 5.0, a pole density of a crystal orientation {332}<113> is 1.0 to 4.0, a Lankford-value rC in a direction perpendicular to a rolling direction is 0.70 to 1.50, and a Lankford-value r30 in a direction making an angle of 30° with the rolling direction is 0.70 to 1.50. Moreover, the cold-rolled steel sheet includes, as a metallographic structure, by area %, a ferrite and a bainite of 30% to 99% in total and a martensite of 1% to 70%.Type: GrantFiled: January 4, 2017Date of Patent: April 23, 2019Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yuri Toda, Riki Okamoto, Nobuhiro Fujita, Kohichi Sano, Hiroshi Yoshida, Toshio Ogawa, Kunio Hayashi, Kazuaki Nakano
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Patent number: 10253384Abstract: A cold-rolled steel sheet includes, by mass %: C: 0.020% or more and 0.080% or less; Si: 0.20% or more and 1.00% or less; Mn: 0.80% or more and 2.30% or less; and Al: 0.010% or more and 0.100% or less; and further includes: one or more of Nb and Ti which satisfy a requirement of 0.005%?Nb+Ti<0.030%, in which a structure consists of, ferrite, bainite, and other phases, an area ratio of the ferrite is 80% or more and less than 95%, an area ratio of a non-recrystallization ferrite in the ferrite is 1% or more and less than 10%, an area ratio of the bainite is 5% or more and 20% or less, a total amount of the other phases is less than 8%, an equivalent circle diameter of a carbonitride including one or both of Nb and Ti is 1 nm or more and 10 nm or less, and a tensile strength is 590 MPa or more.Type: GrantFiled: February 6, 2013Date of Patent: April 9, 2019Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yusuke Kondo, Kunio Hayashi, Toshio Ogawa, Naoki Matsutani, Koichi Goto
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Patent number: 10167539Abstract: A hot-rolled steel sheet wherein an average pole density of orientation group of {100}<011> to {223}<110> is 1.0 to 5.0 and pole density of crystal orientation {332}<113> is 1.0 to 4.0. The hot-rolled steel sheet includes, as a metallographic structure, by area %, 30% to 99% ferrite and bainite in total, and 1% to 70% martensite. The hot-rolled steel sheet satisfies Expression 1: dia?13 ?m, and also satisfies Expression 2: TS/fM×dis/dia?500, wherein an area fraction of the martensite is defined as fM in unit of area %, an average size of the martensite is defined as dia in unit of ?m, an average distance between the martensite is defined as dis in unit of ?m, and tensile strength of the steel sheet is defined as TS in unit of MPa.Type: GrantFiled: March 15, 2017Date of Patent: January 1, 2019Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kohichi Sano, Kunio Hayashi, Kazuaki Nakano, Riki Okamoto, Nobuhiro Fujita
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Patent number: 10106873Abstract: A hot-rolled steel sheet including, in terms of % by mass, 0.030% to 0.120% of C, 1.20% or less of Si, 1.00% to 3.00% of Mn, 0.01% to 0.70% of Al, 0.05% to 0.20% of Ti, 0.01% to 0.10% of Nb, 0.020% or less of P, 0.010% or less of S, and 0.005% or less of N, and a balance consisting of Fe and impurities, in which 0.106?(C %-Ti %*12/48-Nb %*12/93)?0.012 is satisfied; a pole density of {112}(110) at a position of ¼ plate thickness is 5.7 or less; an aspect ratio (long axis/short axis) of prior austenite grains is 5.3 or less; a density of (Ti, Nb)C precipitates having a size of 20 nm or less is 109 pieces/mm3 or more; a yield ratio YR, which is the ratio of a tensile strength to a yield stress, is 0.80 or more; and a tensile strength is 590 MPa or more.Type: GrantFiled: January 8, 2013Date of Patent: October 23, 2018Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Eisaku Sakurada, Kunio Hayashi, Koichi Sato, Shunji Hiwatashi
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Publication number: 20180243853Abstract: The present invention provides a spot welding method for a member to be welded constituted of a plurality of steel sheets that are overlapped with each other at at least a welding zone, in which at least an overlapped face of at least one of the plurality of steel sheets at the welding zone is coated with zinc plating, a total sheet thickness t (mm) of the plurality of steel sheets is 1.35 mm or more, a squeeze time St (seconds) from the time when welding electrodes are brought into contact with the member to be welded to the time when electric current flow for welding starts satisfies “0.020?St”, and a hold time Ht( seconds) after welding from the time when electric current flow for welding between the welding electrodes ends to the time when the welding electrodes and the member to be welded are brought out of contact satisfies “0.015t2+0.020?Ht”.Type: ApplicationFiled: September 2, 2016Publication date: August 30, 2018Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Chisato YOSHINAGA, Yasunobu MIYAZAKI, Kunio HAYASHI, Hiroyuki KAWATA, Masanori YASUYAMA
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Patent number: 10060006Abstract: This high-strength cold-rolled steel sheet contains, in mass %, C: 0.02% to 0.20%; Si: 0.001% to 2.5%; Mn: 0.01% to 4.0%; P: 0.001% to 0.15%; S: 0.0005% to 0.03%; Al: 0.001% to 2.0%; N: 0.0005% to 0.01%; and O: 0.0005% to 0.01%; in which Si+Al is limited to less than 1.0%, and a balance being composed of iron and inevitable impurities, in which an area ratio of bainite in a metal structure is 95% or more, at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet, an average value of pole densities of the {100}<011> to {223}<110> orientation group is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 5.0 or less, and a mean volume diameter of crystal grains in the metal structure is 7 ?m or less.Type: GrantFiled: April 20, 2016Date of Patent: August 28, 2018Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yoshihiro Suwa, Kazuaki Nakano, Kunio Hayashi, Riki Okamoto, Nobuhiro Fujita, Kohichi Sano