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: 20220064771Abstract: Provided are a hot dip galvanized steel sheet comprising a base steel sheet and a hot dip galvanized layer on at least one surface of the base metal steel sheet, wherein the base steel sheet has a predetermined chemical composition and contains, by volume fraction, ferrite: 0% to 50%, retained austenite: 6% to 30%, bainite: 5% or more, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, a number density of tempered martensite with a circle equivalent diameter of 5.0 ?m or more is 20/1000 ?m2 or less, and an area ratio of fresh martensite with a circle equivalent diameter of 2.0 ?m or more after imparting 5% plastic strain is 10% or less, and a method for producing the same.Type: ApplicationFiled: February 6, 2020Publication date: March 3, 2022Applicant: NIPPON STEEL CORPORATIONInventors: Takafumi YOKOYAMA, Hiroyuki KAWATA, Kunio HAYASHI, Yuji YAMAGUCHI, Satoshi UCHIDA
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Patent number: 11261505Abstract: 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 0.60 time or less the average Vickers hardness of the sheet thickness ½ position, and the soft surface layer has a nano-hardness standard deviation of 0.8 or less is provided.Type: GrantFiled: February 20, 2018Date of Patent: March 1, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Katsuya Nakano, Yuya Suzuki, Genki Abukawa, Kunio Hayashi
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Patent number: 11225701Abstract: A hot dip galvanized steel sheet and hot dip galvannealed steel sheet improved in uniform ductility and local ductility, yield strength and tensile strength, and low temperature impact property, characterized by having a predetermined chemical composition, having a metal structure containing, by volume %, retained austenite: over 5.0% and tempered martensite: over 5.0%, having retained austenite containing C: 0.85 mass % or more, and having a ratio [C]?gb/[P]?gb of an amount of segregation of C (number of atoms/nm2): [C]?gb to an amount of segregation of P (number of atoms/nm2): [P]?gb at prior austenite grain boundaries of 4.0 or more.Type: GrantFiled: March 30, 2018Date of Patent: January 18, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Jun Haga, Kohichi Sano, Koutarou Hayashi, Kunio Hayashi, Masaharu Kameda, Akihiro Uenishi, Hiroyuki Kawata
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Patent number: 11208705Abstract: A high-strength cold-rolled steel sheet which is a steel sheet having a tensile strength of 980 MPa or more has a predetermined chemical component composition, a metallographic microstructure of the steel sheet contains, by area ratio, ferrite and granular bainite: 10% or more and 50% or less in total, one or both of upper bainite and lower bainite: 10% or more and 50% or less in total, tempered martensite: more than 0% and 30% or less, retained austenite: 5% or more, and one or more of pearlite, cementite, and martensite: 0% to 10% in total, and an area ratio of the ferrite with respect to a total area ratio of the ferrite and the granular bainite is 25% or less.Type: GrantFiled: November 15, 2017Date of Patent: December 28, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Yuri Toda, Kunio Hayashi, Katsuya Nakano, Eisaku Sakurada, Akihiro Uenishi, Kengo Takeda
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Publication number: 20210230712Abstract: A zinc-plated steel sheet of an aspect of the present invention includes a steel sheet having a predetermined chemical composition and a zinc-plated layer. In the steel sheet, steel microstructures in a range of ? thickness to ? thickness, having the center at ¼ thickness from a steel sheet surface, include, by vol %, ferrite: 0% to 10%, bainite: 0% to 20%, tempered martensite: 70% or more, fresh martensite: 0% to 10%, retained austenite: 0% to 10%, and pearlite: 0% to 5%. In the zinc-plated steel sheet, the amount of hydrogen emitted when the steel sheet is heated to 200° C. from a room temperature after removal of the zinc-plated layer is 0.40 ppm or less per mass of the steel sheet, the tensile strength is 1470 MPa or more, and no cracking occurs in a U-shape bending test where a stress equivalent to 1000 MPa is applied for 24 hours.Type: ApplicationFiled: April 26, 2019Publication date: July 29, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Takafumi YOKOYAMA, Kunio HAYASHI, Masahiro NAKATA, Yuji YAMAGUCHI, Satoshi UCHIDA
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Patent number: 11028469Abstract: A hot press-formed part according to an aspect of the present invention contains a predetermined chemical composition; in which a microstructure in a thickness ¼ portion includes, by unit vol %, tempered martensite: 20% to 90%, bainite: 5% to 75%, and residual austenite: 5% to 25%, and ferrite is limited to 10% or less; and a pole density of an orientation {211}<011> in the thickness ¼ portion is 3.0 or higher.Type: GrantFiled: August 16, 2016Date of Patent: June 8, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Mutsumi Sakakibara, Natsuko Sugiura, Kunio Hayashi, Kaoru Kawasaki
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Patent number: 11027522Abstract: 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: GrantFiled: January 17, 2017Date of Patent: June 8, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Genki Abukawa, Kunio Hayashi, Kazuo Hikida, Kaoru Kawasaki
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Publication number: 20210155999Abstract: A zinc-plated steel sheet of an aspect of the present invention includes a steel sheet having a predetermined chemical composition and a zinc-plated layer. In the steel sheet, steel microstructures in a range of ? thickness to ? thickness, having the center at ¼ thickness from a steel sheet surface, include, by vol %, ferrite: 0% to 10%, bainite: 0% to 30%, tempered martensite: 50% or more, fresh martensite: 0% to 10%, retained austenite: more than 10% and 30% or less, and pearlite: 0% to 5%. In the zinc-plated steel sheet, the amount of hydrogen emitted when the steel sheet is heated to 200° C. from room temperature after removal of the zinc-plated layer is 0.40 ppm or less per mass of the steel sheet, the tensile strength is 1470 MPa or more, and no cracking occurs in a U-shape bending test where a stress equivalent to 1000 MPa is applied for 24 hours.Type: ApplicationFiled: April 26, 2019Publication date: May 27, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Takafumi YOKOYAMA, Kunio HAYASHI, Masahiro NAKATA, Yuji YAMAGUCHI, Satoshi UCHIDA
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Patent number: 11007598Abstract: 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: GrantFiled: September 2, 2016Date of Patent: May 18, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Chisato Yoshinaga, Yasunobu Miyazaki, Kunio Hayashi, Hiroyuki Kawata, Masanori Yasuyama
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Publication number: 20210040588Abstract: A steel sheet has a predetermined chemical composition and a metal structure represented by, in area fraction, polygonal ferrite: 40% or less, martensite: 20% or less, bainitic ferrite: 50% to 95%, and retained austenite: 5% to 50%. In area fraction, 80% or more of the bainitic ferrite is composed of bainitic ferrite grains that have an aspect ratio of 0.1 to 1.0 and have a dislocation density of 8×102 (cm/cm3) or less in a region surrounded by a grain boundary with a misorientation angle of 15° or more. In area fraction, 80% or more of the retained austenite is composed of retained austenite grains that have an aspect ratio of 0.1 to 1.0, have a major axis length of 1.0 ?m to 28.0 ?m, and have a minor axis length of 0.1 ?m to 2.8 ?m.Type: ApplicationFiled: March 30, 2018Publication date: February 11, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Yuri TODA, Eisaku SAKURADA, Kunio HAYASHI, Akihiro UENISHI
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Patent number: 10907235Abstract: 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: GrantFiled: September 13, 2016Date of Patent: February 2, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Yuri Toda, Kunio Hayashi, Katsuya Nakano, Hiroyuki Kawata, Akihiro Uenishi
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Publication number: 20210017622Abstract: A hot dip galvanized steel sheet and hot dip galvannealed steel sheet improved in uniform ductility and local ductility, yield strength and tensile strength, and low temperature impact property, characterized by having a predetermined chemical composition, having a metal structure containing, by volume %, retained austenite: over 5.0% and tempered martensite: over 5.0%, having retained austenite containing C: 0.85 mass % or more, and having a ratio [C]?gb/[P]?gb of an amount of segregation of C (number of atoms/nm2): [C]?gb to an amount of segregation of P (number of atoms/nm2): [P]?gb at prior austenite grain boundaries of 4.0 or more.Type: ApplicationFiled: March 30, 2018Publication date: January 21, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Jun HAGA, Kohichi SANO, Koutarou HAYASHI, Kunio HAYASHI, Masaharu KAMEDA, Akihiro UENISHI, Hiroyuki KAWATA
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Patent number: 10895002Abstract: 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: GrantFiled: January 30, 2017Date of Patent: January 19, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Katsuya Nakano, Kunio Hayashi, Yuri Toda, Eisaku Sakurada, Akihiro Uenishi
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Patent number: 10876181Abstract: In a cold-rolled steel sheet having a predetermined chemical composition, a metallographic structure contains 40.0% or more and less than 60.0% of a polygonal ferrite, 30.0% or more of a bainitic ferrite, 10.0% to 25.0% of a residual austenite, and 15.0% or less of a martensite, by an area ratio, in the residual austenite, a proportion of the residual austenite in which an aspect ratio is 2.0 or less, a length of a long axis is 1.0 ?m or less, and a length of a short axis is 1.0 ?m or less, is 80.0% or more, in the bainitic ferrite, a proportion of the bainitic ferrite in which an aspect ratio is 1.7 or less and an average value of a crystal orientation difference in a region surrounded by a boundary in which a crystal orientation difference is 15° or more is 0.5° or more and less than 3.0°, is 80.0% or more, and a connection index D value of the martensite, the bainitic ferrite, and the residual austenite is 0.70 or less.Type: GrantFiled: February 24, 2016Date of Patent: December 29, 2020Assignee: NIPPON STEEL CORPORATIONInventors: Kengo Takeda, Kunio Hayashi, Akihiro Uenishi, Masafumi Azuma, Takayuki Nozaki, Yuri Toda
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Publication number: 20200325554Abstract: A steel sheet having a chemical composition of the base metal including, in mass %, C: 0.17 to 0.40%, Si: 0.10 to 2.50%, Mn: 1.00 to 10.00%, P: 0.001 to 0.03%, S: 0.0001 to 0.02%, Al: 0.001 to 2.50%, N: 0.0001 to 0.010%, O: 0.0001 to 0.010%, Ti: 0 to 0.10%, Nb: 0 to 0.10%, V: 0 to 0.10%, B: 0 to 0.010%, Cr: 0 to 2.00%, Ni: 0 to 2.00%, Cu: 0 to 2.00%, Mo: 0 to 2.00%, Ca: 0 to 0.50%, Mg: 0 to 0.50%, REM: 0 to 0.50%, the balance: Fe and impurities, wherein the steel sheet has an internal oxidized layer in which at least one part of a crystal grain boundary is covered by oxides, and in which a grain boundary coverage ratio of oxides is 60% or more in a region from the surface of the base metal to a depth of 5.0 ?m.Type: ApplicationFiled: December 15, 2017Publication date: October 15, 2020Applicant: NIPPON STEEL CORPORATIONInventors: Kengo TAKEDA, Kunio HAYASHI, Akihiro UENISHI, Hiroyuki KAWATA, Chisato YOSHINAGA, Yasunobu MIYAZAKI, Toyomitsu NAKAMURA
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Patent number: 10787727Abstract: 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: GrantFiled: September 21, 2016Date of Patent: September 29, 2020Assignee: NIPPON STEEL CORPORATIONInventors: Kunio Hayashi, Masafumi Azuma
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Publication number: 20200283869Abstract: A high-strength cold-rolled steel sheet which is a steel sheet having a tensile strength of 980 MPa or more has a predetermined chemical component composition, a metallographic microstructure of the steel sheet contains, by area ratio, ferrite and granular bainite: 10% or more and 50% or less in total, one or both of upper bainite and lower bainite: 10% or more and 50% or less in total, tempered martensite: more than 0% and 30% or less, retained austenite: 5% or more, and one or more of pearlite, cementite, and martensite: 0% to 10% in total, and an area ratio of the ferrite with respect to a total area ratio of the ferrite and the granular bainite is 25% or less.Type: ApplicationFiled: November 15, 2017Publication date: September 10, 2020Applicant: NIPPON STEEL CORPORATIONInventors: Yuri TODA, Kunio HAYASHI, Katsuya NAKANO, Eisaku SAKURADA, Akihiro UENISHI, Kengo TAKEDA
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Publication number: 20200232060Abstract: 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 0.60 time or less the average Vickers hardness of the sheet thickness ½ 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: July 23, 2020Applicant: NIPPON STEEL CORPORATIONInventors: Katsuya NAKANO, Yuya SUZUKI, Genki ABUKAWA, Kunio HAYASHI
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Patent number: 10718044Abstract: 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: GrantFiled: July 15, 2016Date of Patent: July 21, 2020Assignee: NIPPON STEEL CORPORATIONInventors: Takafumi Yokoyama, Kunio Hayashi, Masafumi Azuma, Eisaku Sakurada, Hiroyuki Kawata, Genki Abukawa
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Publication number: 20200157666Abstract: A hot press-formed part according to an aspect of the present invention contains a predetermined chemical composition; in which a microstructure in a thickness ¼ portion includes, by unit vol %, tempered martensite: 20% to 90%, bainite: 5% to 75%, and residual austenite: 5% to 25%, and ferrite is limited to 10% or less; and a pole density of an orientation {211}<011> in the thickness ¼ portion is 3.0 or higher.Type: ApplicationFiled: August 16, 2016Publication date: May 21, 2020Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Mutsumi SAKAKIBARA, Natsuko SUGIURA, Kunio HAYASHI, Kaoru KAWASAKI