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公开(公告)号：US20220267874A1
公开(公告)日：2022-08-25
申请号：US17601580
申请日：2020-06-26
发明人： Katsuya NAKANO , Kengo TAKEDA , Hiroyuki KAWATA , Akihiro UENISHI , Yuya SUZUKI
IPC分类号： C21D9/46 , B32B15/01 , C22C38/38 , C22C38/32 , C22C38/16 , C22C38/14 , C22C38/12 , C22C38/10 , C22C38/08 , C22C38/06 , C22C38/02 , C22C38/00 , C21D8/02 , C21D6/00
摘要： A steel sheet having a tensile strength of 1100 MPa or more and excellent in crash resistance, having a micro-structure containing tempered martensite: 95 vol. % or more, wherein in a cross section parallel to a sheet-thickness direction of the steel sheet, when a sheet thickness is denoted by t, in a 300-μm-square region centered about a t/2 point, a standard deviation of Vickers hardnesses that are measured under a load of 9.8 N at 30 points is 30 or less, wherein when a 100-μm-square region centered about a t/2 point is divided into 10×10, 100 subregions, and at a center of each of the subregions, a nano hardness is measured under a maximum load of 1 mN, out of the subregions, the number of subregions each of which makes a difference in nano hardness of 3 GPa or more from any one of eight surrounding subregions is 10 or less.
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公开(公告)号：US20210017622A1
公开(公告)日：2021-01-21
申请号：US17043267
申请日：2018-03-30
发明人： Jun HAGA , Kohichi SANO , Koutarou HAYASHI , Kunio HAYASHI , Masaharu KAMEDA , Akihiro UENISHI , Hiroyuki KAWATA
IPC分类号： C21D9/46 , B32B15/01 , C22C38/38 , C22C38/32 , C22C38/22 , C22C38/16 , C22C38/14 , C22C38/08 , C22C38/06 , C22C38/02 , C22C38/00 , C21D6/00 , C23C2/02 , C23C2/06 , C23C2/28 , C23C2/40
摘要： 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]γgb/[P]γgb of an amount of segregation of C (number of atoms/nm2): [C]γgb to an amount of segregation of P (number of atoms/nm2): [P]γgb at prior austenite grain boundaries of 4.0 or more.
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公开(公告)号：US20200071801A1
公开(公告)日：2020-03-05
申请号：US16490465
申请日：2018-04-27
发明人： Shohei YABU , Koutarou HAYASHI , Genki ABUKAWA , Akihiro UENISHI
摘要： A high strength steel sheet containing a large amount of Mn which has bendability suitable as a material for auto part use and a method of producing the same are provided. A high strength steel sheet comprising a center part in a sheet thickness and a softened surface layer part on one surface or both surfaces of the center part in the sheet thickness, characterized in that, the center part in the sheet thickness has an average Mn concentration of greater than 4.0 mass % and less than 10.0 mass %, each softened surface layer part has a thickness of 0.1% to 30% of the sheet thickness, and the softened surface layer part has an average Mn concentration of 2.5 mass % or less, a recrystallization rate of 90% or more, and recrystallized structures with an average crystal grain size of 0.1 μm or more and 40 μm or less.
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公开(公告)号：US20220145415A1
公开(公告)日：2022-05-12
申请号：US17434986
申请日：2020-03-31
发明人： Shohei YABU , Koutarou HAYASHI , Akihiro UENISHI
摘要： The present invention relates to a cold rolled steel sheet containing C: 0.15% or more and 0.40% or less, Si: 0.50% or more and 4.00% or less, Mn: 1.00% or more and 4.00% or less, and sol. Al: 0.001% or more and 2.000% or less, having a metallic structure consisting of 35 to 65 area % of ferrite phases, 35 to 65 area % of hard second phases, and 0 to 5 area % of remaining phases, wherein 60% or more of the ferrite phases are recrystallized ferrite phases, an average crystal grain size defined by 15° grain boundaries is 5.0 μm or less, a maximum connecting rate of the hard second phases is 10% or more, and a two-dimensional isoperimetric constant of the hard second phases is 0.20 or less.
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公开(公告)号：US20220025497A1
公开(公告)日：2022-01-27
申请号：US17277658
申请日：2019-10-04
发明人： Mai NAGANO , Koutarou HAYASHI , Akihiro UENISHI
IPC分类号： C22C38/58 , C22C38/02 , C22C38/42 , C22C38/44 , C22C38/50 , C22C38/54 , C22C38/46 , C22C38/00 , C23C2/40 , C21D9/46
摘要： A galvannealed steel sheet according to one aspect of the present invention has a hot-dip galvannealed layer on at least one surface of the steel sheet, and the steel sheet has a predetermined chemical composition, in which the steel sheet contains 10% or more and 90% or less of ferrite, and 10% or more of tempered martensite and tempered bainite in terms of an area ratio, a sum of the ferrite, the tempered martensite, and the tempered bainite is 90% or more, carbides having a major axis of 50 nm or more and 300 nm or less are contained in grains of the ferrite in a number density of 20/μm2 or more, and a two-dimensional homogeneous dispersion ratio S of Mn is 0.75 or more and 1.30 or less.
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公开(公告)号：US20200332397A1
公开(公告)日：2020-10-22
申请号：US16761724
申请日：2018-11-08
发明人： Mai NAGANO , Koutarou HAYASHI , Akihiro UENISHI
IPC分类号： C22C38/04 , C21D9/46 , C22C38/00 , C22C38/02 , C22C38/06 , C22C38/08 , C22C38/12 , C22C38/14 , C22C38/16 , C22C38/32
摘要： A steel sheet includes, as a chemical composition, by mass %: C: 0.05% to 0.30%; Si: 0.2% to 2.0%; Mn: 2.0% to 4.0%; Al: 0.001% to 2.000%; P: 0.100% or less; S: 0.010% or less; N: 0.010% or less; Ti: 0% to 0.100%; Nb: 0% to 0.100%; V: 0% to 0.100%; Cu: 0% to 1.00%; Ni: 0% to 1.00%; Mo: 0% to 1.00%; Cr: 0% to 1.00%; W: 0% to 0.005%; Ca: 0% to 0.005%; Mg: 0% to 0.005%; a rare earth element (REM): 0% to 0.010%; B: 0% to 0.0030%; and a remainder of Fe and impurities, in which a metallographic structure contains, by area ratio, 95% or more of a hard structure and 0% to 5% of residual austenite, by mass % in a cross section in a thickness direction, C1/C2 which is a ratio of an upper limit C1 of a Mn content to a lower limit C2 of the Mn content is 1.5 or less, and a bake-hardening amount BH is 150 MPa or less.
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公开(公告)号：US20210269903A1
公开(公告)日：2021-09-02
申请号：US17258704
申请日：2019-07-26
发明人： Mai NAGANO , Koutarou HAYASHI , Akihiro UENISHI
IPC分类号： C22C38/38 , C22C38/16 , C22C38/14 , C22C38/12 , C22C38/08 , C22C38/06 , C22C38/04 , C22C38/02 , C22C38/00 , C21D9/46 , C21D8/02 , C21D6/00
摘要： What is provided is a high-strength steel sheet including, by mass %: C: 0.05% to 0.15%; Si: 1.5% or less; Mn: 2.00% to 5.00%; P: 0.100% or less; S: 0.010% or less; Al: 0.001% to 2.000%; N: 0.010% or less; and a remainder of Fe and impurities, in which Ceq defined by Ceq=C+Si/90+Mn/100+1.5P+3S is less than 0.21, the high-strength steel sheet contains martensite in an area ratio of 98% or more, and a residual structure is in an area ratio of 2% or less, a two-dimensional homogeneous dispersion ratio S defined by S=Sy2/Sx2 (Sx2 is a dispersion value of Mn concentration profile data in a sheet width direction, and Sy2 is a dispersion value of the Mn concentration profile data in a sheet thickness direction) is 0.85 or more and 1.20 or less, and a tensile strength is 1200 MPa or more.
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公开(公告)号：US20210164082A1
公开(公告)日：2021-06-03
申请号：US17054467
申请日：2019-07-26
发明人： Mai NAGANO , Koutarou HAYASHI , Akihiro UENISHI
摘要： What is provided is a high-strength steel sheet having a large bake hardening amount and a uniform bake hardenability is provided according to the present invention, the high-strength steel sheet comprising, by mass %: C: 0.13% to 0.40%; Si: 0.500% to 3.000%; Mn: 2.50% to 5.00%; P: 0.100% or less; S: 0.010% or less; Al: 0.001% to 2.000%; N: 0.010% or less; and a remainder consisting of Fe and impurities, wherein martensite is 95% or more in an area ratio, and residual structure is 5% or less in an area ratio, a ratio C1/C2 of an upper limit C1 (mass %) of Si concentrations to a lower limit C2 (mass %) of the Si concentrations in a cross section in a thickness direction is 1.25 or less, precipitates having a major axis of 0.05 μm or more and 1.00 μm or less and an aspect ratio of 1:3 or more are included in a number density of 30/μm2 or more, and a tensile strength is 1300 MPa or more.
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公开(公告)号：US20210040588A1
公开(公告)日：2021-02-11
申请号：US16975985
申请日：2018-03-30
发明人： Yuri TODA , Eisaku SAKURADA , Kunio HAYASHI , Akihiro UENISHI
IPC分类号： C22C38/32 , C22C38/28 , C22C38/26 , C22C38/24 , C22C38/22 , C22C38/04 , C22C38/02 , C22C38/00 , C22C38/60 , C23C2/06 , C23C2/12 , C23C2/40 , C21D9/46
摘要： 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 μm to 28.0 μm, and have a minor axis length of 0.1 μm to 2.8 μm.
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公开(公告)号：US20200325554A1
公开(公告)日：2020-10-15
申请号：US16772692
申请日：2017-12-15
发明人： Kengo TAKEDA , Kunio HAYASHI , Akihiro UENISHI , Hiroyuki KAWATA , Chisato YOSHINAGA , Yasunobu MIYAZAKI , Toyomitsu NAKAMURA
IPC分类号： C21D9/46 , B32B15/01 , C22C38/38 , C22C38/16 , C22C38/14 , C22C38/12 , C22C38/08 , C22C38/06 , C22C38/02 , C22C38/00 , C21D8/02 , C21D6/00
摘要： 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 μm.
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