公开(公告)号：US10570476B2

公开(公告)日：2020-02-25

申请号：US15561224

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Kenji Kawamura ,  Noriaki Kohsaka ,  Yasuhiro Nishimura

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C23C2/06 ,  C23C2/28

Abstract: A high-strength steel sheet having excellent punchability and a tensile strength of at least 780 MPa has a steel structure containing, by area ratio, 70%-90% ferrite phase and 10%-30% martensite phase. The non-recrystallized ferrite content in the ferrite phase is 30%-50% and the ratio of crystal grains having an aspect ratio of 1.0-1.5 in the martensite phase is 40%-100%, by area ratio.

公开(公告)号：US11739392B2

公开(公告)日：2023-08-29

申请号：US16076374

申请日：2017-02-07

Applicant: JFE STEEL CORPORATION

Inventor： Yusuke Kimata ,  Yoshihiko Ono ,  Kenji Kawamura

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/06 ,  C22C38/16 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C21D6/00 ,  C22C38/12 ,  C22C38/14

CPC classification number: C21D8/0247 ,  C21D6/002 ,  C21D6/005 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength steel sheet having a tensile strength TS of 1320 MPa or more and excellent workability. The high-strength steel sheet has a chemical composition containing, by mass %, C: 0.20% or more and 0.40% or less, Si: 0.5% or more and 2.5% or less, Mn: more than 2.4% and 5.0% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.01% or more and 0.5% or less, N: 0.010% or less, and Fe and inevitable impurities. A microstructure of the steel sheet includes, in terms of area fraction with respect to the whole steel sheet microstructure, lower bainite in an amount of 40% or more and less than 85%, martensite including tempered martensite in an amount of 5% or more and less than 40%, retained austenite in an amount of 10% or more and 30% or less, and polygonal ferrite in an amount of 10% or less (including 0%).

公开(公告)号：US10760142B2

公开(公告)日：2020-09-01

申请号：US15542203

申请日：2015-08-28

Applicant: JFE STEEL CORPORATION

Inventor： Nobusuke Kariya ,  Yoshihiko Ono ,  Yoshimasa Funakawa ,  Kazuma Mori ,  Reiko Sugihara ,  Kenji Kawamura

IPC: C21D9/46 ,  C22C38/14 ,  C22C38/60 ,  C22C38/00 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38

Abstract: Provided are a high-strength steel sheet and a method for manufacturing the steel sheet. The high-strength steel sheet has a specified chemical composition with the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 30% or more of a ferrite phase, 40% to 65% of a bainite phase and/or a martensite phase, and 5% or less of cementite, in which, in a surface layer that is a region within 50 μm from the surface in the thickness direction, the area ratio of a ferrite phase is 40% to 55% and the total area ratio of a bainite phase having a grain diameter of more than 5 μm and/or a martensite phase having a grain diameter of more than 5 μm is 20% or less, and a tensile strength is 980 MPa or more.

公开(公告)号：US20190017156A1

公开(公告)日：2019-01-17

申请号：US16065867

申请日：2016-12-26

Applicant: JFE Steel Corporation

Inventor： Kenji Kawamura ,  Yoshihiko Ono ,  Nobusuke Kariya ,  Shinichi Furuya ,  Kohei Hasegawa

IPC: C22C38/60 ,  C22C38/00 ,  C22C38/08 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/06 ,  C22C38/04 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/02 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40 ,  C21C7/10 ,  C21D9/46 ,  C21D8/02

Abstract: Provided are a high-strength steel sheet having a specified chemical composition, in which a Mn-segregation degree in a region within 100 μm from a surface thereof in a thickness direction is 1.5 or less, in a plane parallel to the surface of the steel sheet in a region within 100 μm from the surface of the steel sheet in the thickness direction, the number of oxide-based inclusion grains having a grain long diameter of 5 μm or more is 1000 or less/100 mm2, a proportion of the number of oxide-based inclusion grains having a chemical composition containing alumina of 50 mass % or more, silica of 20 mass % or less, and calcia of 40 mass % or less to the total number of oxide-based inclusions having a grain long diameter of 5 μm or more is 80% or more, a specified metallographic structure, and a TS of 980 MPa or more, a high-strength galvanized steel sheet, and a manufacturing method thereof.

公开(公告)号：US11001906B2

公开(公告)日：2021-05-11

申请号：US15561786

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Kenji Kawamura ,  Noriaki Kohsaka ,  Yasuhiro Nishimura

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C23C2/06 ,  C22C38/60 ,  C22C38/14 ,  C22C38/42 ,  C22C38/22 ,  C22C38/44 ,  C22C38/12

Abstract: A high-strength steel sheet having a tensile strength of at least 780 MPa and excellent punchability comprises a ferrite phase, a martensite phase, and a bainite phase. The area ratio of the martensite phase is 20%-50%; the area ratio of crystal grains having an average crystal grain diameter of less than 1.0 μm in the martensite phase is 5%-30%; the area ratio of crystal grains having an average crystal grain diameter of 1.0-4.0 μm is 70%-95%; and the area ratio of crystal grains having an average crystal grain diameter of more than 4.0 μm is less than 5%.

公开(公告)号：US20180002778A1

公开(公告)日：2018-01-04

申请号：US15542272

申请日：2015-08-28

Applicant: JFE STEEL CORPORATION

Inventor： Nobusuke Kariya ,  Yoshihiko Ono ,  Yoshimasa Funakawa ,  Kazuma Mori ,  Reiko Sugihara ,  Kenji Kawamura

IPC: C21D9/46 ,  B21B1/22 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/16 ,  C22C38/08 ,  C22C38/02 ,  C22C38/00 ,  C22C38/38 ,  B21B3/02 ,  C21D6/00 ,  C21D8/02 ,  C23G1/00

Abstract: Provided are a high-strength steel sheet and a method for manufacturing the steel sheet. The high-strength steel sheet has a specified chemical composition with the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 25% or less of a ferrite phase, 75% or more of a bainite phase and/or a martensite phase, and 5% or less of cementite, in which, in a surface layer that is a region within 50 μm from the surface in the thickness direction, the area ratio of a ferrite phase is 5% to 20%, and a tensile strength is 1180 MPa or more.

公开(公告)号：US20150027594A1

公开(公告)日：2015-01-29

申请号：US14355756

申请日：2012-11-07

Applicant: JFE Steel Corporation

Inventor： Kenji Kawamura ,  Takeshi Yokota

IPC: C21D8/02 ,  C22C38/28 ,  C22C38/16 ,  C22C38/14 ,  C22C38/00 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/38 ,  C22C38/12

CPC classification number: C21D8/0263 ,  C21D8/0436 ,  C21D8/0463 ,  C21D8/0473 ,  C21D9/46 ,  C21D2211/004 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/38

Abstract: A thin steel sheet having sheet thickness ≦1.6 mm, but tensile strength ≧780 MPa and Young's modulus ≧240 GPa in transverse direction is provided, where the steel sheet has composition including, in mass %, C: 0.06-0.12%, Si: 0.5-1.5%, Mn: 1.0-3.0%, P: 0.05% or less, S: 0.01% or less, Al: 0.5% or less, N: 0.01% or less, Ti: 0.02-0.20%, and the balance being Fe and incidental impurities, where the composition satisfies relations of Formula (1) and (2), and microstructure such that ferrite phase has area ratio ≧60% and martensite phase has area ratio of 15-35%, ferrite and martensite phases are 95% or more in total, average grain size of ferrite is ≦4.0 μm and that of martensite is ≦1.5 μm, 0.05≦[% C]−(12/47.9)×[% Ti*]≦0.10   (1), where Ti*=[% Ti]−(47.9/14)×[% N]−(47.9/32.1)×[% S]  (2).

Abstract translation: 提供具有片材厚度为1.6mm，拉伸强度≥780MPa，横向杨氏模量≥240GPa的薄钢板，其中钢板的组成以质量％计含有C：0.06〜0.12％，Si ：0.5-1.5％，Mn：1.0-3.0％，P：0.05％以下，S：0.01％以下，Al：0.5％以下，N：0.01％以下，Ti：0.02〜0.20％ 余量为Fe和偶然杂质，其中组成满足式（1）和（2）的关系，并且组织使得铁素体相的面积比≥60％，马氏体相的面积比为15-35％，铁素体和马氏体相 总共为95％以上，铁素体的平均粒径为nlE;4.0μm，马氏体的平均粒径为n1E;1.5μm，0.05＆nlE; [％C] - （12 / 47.9）×[％Ti *]＆ （1），其中Ti * = [％Ti] - （47.9 / 14）×[％N] - （47.9 / 32.1）×[％S]（2）。

公开(公告)号：US11111553B2

公开(公告)日：2021-09-07

申请号：US16076381

申请日：2017-02-07

Applicant: JFE STEEL CORPORATION

Inventor： Yusuke Kimata ,  Yoshihiko Ono ,  Kenji Kawamura

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/06 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/58 ,  C21D6/00 ,  C22C38/54

Abstract: A high-strength steel sheet having a tensile strength (TS) of 1,320 MPa or more and good workability. The high-strength steel sheet has a specific component composition and a steel microstructure containing, on an area-percentage basis with respect to the entire steel microstructure, 40% or more and less than 85% of a lower bainite, 5% or more and less than 40% martensite including tempered martensite, 10% or more and 30% or less retained austenite, and 10% or less (including 0%) polygonal ferrite, the retained austenite having an average C content of 0.60% by mass or more. Additionally, a Mn segregation value at a surface of the steel sheet is 0.8% or less, the ratio R/t of a limit bending radius (R) to a thickness (t) of the steel sheet is 2.0 or less, and tensile strength×total elongation of the steel sheet is 15,000 MPa % or more.

公开(公告)号：US10704117B2

公开(公告)日：2020-07-07

申请号：US15746203

申请日：2016-07-28

Applicant: JFE STEEL CORPORATION

Inventor： Kenji Kawamura ,  Noriaki Kohsaka ,  Yoshimasa Funakawa ,  Mai Aoyama ,  Yoshitsugu Suzuki

IPC: C21D9/46 ,  C22C38/06 ,  C22C38/60 ,  C21D8/02 ,  C23C2/06 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C21D6/00 ,  C23C2/02 ,  C22C38/38 ,  C23C8/14 ,  C23C2/28 ,  C23C2/40 ,  C23F17/00

Abstract: Provided are a cold-rolled steel sheet which can preferably be used for manufacturing a high-strength galvanized steel sheet and methods for manufacturing the steel sheets. The cold-rolled steel sheet has a specified chemical composition, in which the Mn concentration in a surface layer of the steel sheet satisfies relational expression (1) and relational expression (2) below. 8≤(Cp/Cc)×Mn . . . (1) (Cmin/Cc)×Mn≤2.5 . . . (2) where Cp: maximum Mn concentration in a region within 0.5 μm of the surface of a steel sheet in the thickness direction; Cc: average Mn concentration in a region from a position located 5 μm from a surface of a steel sheet in the thickness direction to a position located 5 μm from an opposite surface in the thickness direction; Cmin: minimum Mn concentration in a region from 0.5 μm to 5 μm from the surface of a steel sheet in the thickness direction; and Mn: Mn content (mass %).

公开(公告)号：US20180057907A1

公开(公告)日：2018-03-01

申请号：US15561224

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Kenji Kawamura ,  Noriaki Kohsaka ,  Yasuhiro Nishimura

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/26 ,  C22C38/16 ,  C22C38/28 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23C2/28 ,  C23C2/06 ,  B32B15/01

Abstract: A high-strength steel sheet having excellent punchability and a tensile strength of at least 780 MPa has a steel structure containing, by area ratio, 70%-90% ferrite phase and 10%-30% martensite phase. The non-recrystallized ferrite content in the ferrite phase is 30%-50% and the ratio of crystal grains having an aspect ratio of 1.0-1.5 in the martensite phase is 40%-100%, by area ratio.