公开(公告)号：US11193180B2

公开(公告)日：2021-12-07

申请号：US16092323

申请日：2017-03-22

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Yoshimasa Funakawa ,  Takashi Kobayashi

IPC: C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54

Abstract: A high-strength steel sheet having a chemical composition containing, by mass %, C: 0.15% to 0.25%, Si: 1.00% to 2.20%, Mn: 2.00% to 3.50%, P: 0.05% or less, S: 0.005% or less, Al: 0.01% to 0.50%, N: 0.010% or less, B: 0.0003% to 0.0050%, one, two, or more selected from Ti: 0.005% to 0.05%, Cu: 0.003% to 0.50%, Ni: 0.003% to 0.50%, Sn: 0.003% to 0.50%, Co: 0.003% to 0.05%, and Mo: 0.003% to 0.50%, and the balance being Fe and inevitable impurities and a microstructure including, in terms of volume fraction, 15% or less (including 0%) of ferrite, 2% to 15% of retained austenite, 10% or less (including 0%) of martensite, and the balance being bainite and tempered martensite, in which the average number of cementite grains having a grain diameter of 0.04 μm or more existing in the bainite and tempered martensite grains is 10 or more.

公开(公告)号：US11136643B2

公开(公告)日：2021-10-05

申请号：US16320864

申请日：2017-08-10

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Koichi Taniguchi ,  Takashi Kobayashi ,  Hiroshi Matsuda ,  Rinsei Ikeda

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/38 ,  C22C38/12 ,  C22C38/08 ,  C22C38/22 ,  C22C38/00 ,  C22C38/26 ,  C22C38/24 ,  C22C38/28 ,  C22C38/14 ,  C22C38/32 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C21D6/00 ,  C21D1/30 ,  C22C38/20 ,  C22C38/58

Abstract: A high-strength steel sheet having a specified chemical composition and a method for producing the same. The steel sheet including a multi-phase structure including, by volume fraction, ferrite of 35% to 65%, residual austenite of 7% or less (including 0%), martensite of 20% to 60%, bainite of 20% or less (including 0%), the ferrite having an average crystal grain size of 8 μm or less and an average aspect ratio of 3.5 or less, the martensite having an average crystal grain size of 3 μm or less, and the bainite having an average crystal grain size of 3 μm or less when contained. A standard deviation of Vickers hardness of the steel sheet being 30 or less when measured at 200 μm intervals from a position of 100 μm from a surface to a central portion in a thickness direction of the sheet.

公开(公告)号：US11085101B2

公开(公告)日：2021-08-10

申请号：US16618887

申请日：2018-03-30

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Takashi Kobayashi ,  Yoshimasa Funakawa ,  Seiji Nakajima

IPC: B32B15/01 ,  C21D9/46 ,  B21D22/02 ,  C21D1/18 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C23C2/06 ,  C23C2/12 ,  C23C2/40

Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more and excellent delayed fracture resistance after projection welding by properly adjusting its chemical composition and its microstructure such that at least 5 Ti-based precipitates having a grain size of 0.10 μm or less are present on average per 100 μm2 of a cross section parallel to a thickness direction of the member within a range of 100 μm in a thickness direction from a surface of the member, a volume fraction of martensite is 95% to 100% within a depth range of 20 μm to 100 μm in the thickness direction from the surface of the member, and at least 10 cementite grains having a grain size of less than 0.20 μm are present on average in a prior austenite grain.

公开(公告)号：US10961600B2

公开(公告)日：2021-03-30

申请号：US16086426

申请日：2017-03-21

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Yoshimasa Funakawa

IPC: C22C38/58 ,  C22C38/50 ,  C22C38/32 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/20 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  B32B15/01 ,  C23C2/28 ,  C23C2/40 ,  C23C2/06 ,  C21D8/02 ,  C21D9/46 ,  C21D6/00 ,  C22C38/38 ,  C22C38/14 ,  C22C38/12 ,  C22C38/04 ,  C22C38/16 ,  C22C38/46 ,  C22C38/40 ,  C22C38/44 ,  C22C38/42 ,  C22C38/28 ,  C22C38/48 ,  C22C38/18 ,  C22C38/54 ,  C22C38/08 ,  C23C2/12 ,  B32B15/04 ,  C23C28/02 ,  C23C2/02 ,  C23C30/00 ,  B32B15/18 ,  C23C2/04 ,  C23G1/08 ,  C23G1/00

Abstract: Provided herein is a plated steel sheet having a yield ratio, strength (tensile strength), elongation, hole expansibility, and CTS. A method for producing the plated steel sheet is also provided, among others. A steel sheet of a specific composition is provided that has a micro structure containing 70 to 90% of ferrite, 5 to 20% of martensite, 5% or less of retained austenite, 10% or less of bainite, and 5% or less of perlite by volume. The ferrite has an average crystal grain diameter of 20 μm or less. The martensite has an average crystal grain diameter of 5 μm or less. The retained austenite has an average crystal grain diameter of 5 μm or less. The bainite has an average crystal grain diameter of 7 μm or less. The steel sheet has a tensile strength of 590 MPa or more.

公开(公告)号：US10253389B2

公开(公告)日：2019-04-09

申请号：US15128516

申请日：2015-03-17

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Kohei Hasegawa

IPC: C21D9/46 ,  C21D1/25 ,  C21D8/02 ,  C21D8/04 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/38 ,  C22C38/58 ,  C22C38/00 ,  C23G1/00

Abstract: A high-yield-ratio, high-strength cold-rolled steel sheet has a composition containing, in terms of % by mass, C: 0.13% to 0.25%, Si: 1.2% to 2.2%, Mn: 2.0% to 3.2%, P: 0.08% or less, S: 0.005% or less, Al: 0.01% to 0.08%, N: 0.008% or less, Ti: 0.055% to 0.130%, and the balance being Fe and unavoidable impurities. The steel sheet has a microstructure that contains 2% to 15% of ferrite having an average crystal grain diameter of 2 μm or less in terms of volume fraction, 5 to 20% of retained austenite having an average crystal grain diameter of 0.3 to 2.0 μm in terms of volume fraction, 10% or less (including 0%) of martensite having an average grain diameter of 2 μm or less in terms of volume fraction, and the balance being bainite and tempered martensite, and the bainite and the tempered martensite having an average crystal grain diameter of 5 μm or less.

公开(公告)号：US10144996B2

公开(公告)日：2018-12-04

申请号：US14648778

申请日：2013-12-04

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Yuki Toji ,  Hideyuki Kimura ,  Kohei Hasegawa

IPC: C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C22C38/18

Abstract: A high strength cold rolled steel sheet with a low yield ratio has a chemical composition containing C: 0.05% to 0.10%, Si: 0.6% to 1.3%, Mn: 1.4% to 2.2%, P: 0.08% or less, S: 0.010% or less, Al: 0.01% to 0.08%, N: 0.010% or less, and the remainder being Fe and incidental impurities, on a percent by mass basis, and a microstructure in which the average grain size of ferrite is 15 μm or less, the volume fraction of ferrite is 70% or more, the volume fraction of bainite is 3% or more, the volume fraction of retained austenite is 4% to 7%, the average grain size of martensite is 5 μm or less, and the volume fraction of martensite is 1% to 6%, wherein the average C concentration (percent by mass) in the retained austenite is 0.30% to 0.70%, yield ratio is 64% or less, and the tensile strength is 590 MPa or more.

公开(公告)号：US10077486B2

公开(公告)日：2018-09-18

申请号：US14911059

申请日：2014-07-18

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Yoshihiko Ono ,  Kohei Hasegawa

IPC: C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/00 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C21D1/84 ,  C21D8/04 ,  C21D1/25

CPC classification number: C21D9/46 ,  C21D1/25 ,  C21D1/84 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D8/0473 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38

Abstract: A high-strength cold-rolled steel sheet has a composition and a microstructure. The microstructure comprises: ferrite having an average grain size of 5 μm or less and a volume fraction of 3% to 20%, retained austenite having a volume fraction of 5% to 20%, and martensite having a volume fraction of 5% to 20%, the remainder being bainite and/or tempered martensite. The total number of retained austenite with a grain size of 2 μm or less, martensite with a grain size of 2 μm or less, or a mixed phase thereof is 150 or more per 2,000 μm2 of a thickness cross section parallel to the rolling direction of the steel sheet.

公开(公告)号：US20180127856A1

公开(公告)日：2018-05-10

申请号：US15553408

申请日：2015-12-21

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Yoshimasa Funakawa

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

CPC classification number: C22C38/14 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0263 ,  C21D9/46 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/18

Abstract: A high-strength cold-rolled steel sheet excellent in terms of elongation (EL) and hole expansion ratio (A) having a low yield ratio (YR), as well as a method for manufacturing the steel sheet. The steel sheet has a chemical composition containing, by mass %, C: 0.15% to 0.25%, Si: 1.0% to 2.0%, Mn: 1.8% to 2.5%, P: 0.10% or less, S: 0.010% or less, Al: 0.10% or less, N: 0.010% or less, and the balance being Fe and inevitable impurities, and a multi-phase microstructure including ferrite having an average crystal grain diameter of 5 μm or less in an amount of 30% to 55% in terms of volume fraction, retained austenite having an average crystal grain diameter of 2 μm or less in an amount of 5% to 15% in terms of volume fraction, and tempered martensite having an average crystal grain diameter of 2 μm or less in an amount of 30% to 60% in terms of volume fraction, in which the number of grains of the retained austenite existing in an area of 1000 μm2 is 10 or more.

公开(公告)号：US20160177414A1

公开(公告)日：2016-06-23

申请号：US14911059

申请日：2014-07-18

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Yoshihiko Ono ,  Kohei Hasegawa

IPC: C21D9/46 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C21D1/84 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C22C38/38 ,  C22C38/06

CPC classification number: C21D9/46 ,  C21D1/25 ,  C21D1/84 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D8/0473 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38

Abstract: A high-strength cold-rolled steel sheet has a composition and a microstructure. The microstructure comprises: ferrite having an average grain size of 5 um or less and a volume fraction of 3% to 20%, retained austenite having a volume fraction of 5% to 20%, and martensite having a volume fraction of 5% to 20%, the remainder being bainite and/or tempered martensite. The total number of retained austenite with a grain size of 2 μm or less, martensite with a grain size of 2 μm or less, or a mixed phase thereof is 150 or more per 2,000 μm2 of a thickness cross section parallel to the rolling direction of the steel sheet.

Abstract translation: 高强度冷轧钢板具有组成和微观结构。 微结构包括：体积分数为5〜20％的平均粒径为5μm以下，体积分率为3〜20％的铁素体，体积分数为5〜20的马氏体 ％，其余为贝氏体和/或回火马氏体。 晶粒尺寸为2μm以下的残留奥氏体的总数，粒径为2μm以下的马氏体或其混合相的总数为平均于轧制方向的厚度方向的厚度横截面为每2000平方米的150μm以上 钢板。

公开(公告)号：US20150322552A1

公开(公告)日：2015-11-12

申请号：US14648778

申请日：2013-12-04

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Yuki Toji ,  Hideyuki Kimura ,  Kohei Hasegawa

IPC: C22C38/38 ,  C21D9/46 ,  C21D6/00 ,  C22C38/16 ,  C22C38/00 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C21D8/02 ,  C22C38/14

CPC classification number: C22C38/38 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0263 ,  C21D9/46 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18

Abstract: A high strength cold rolled steel sheet with a low yield ratio has a chemical composition containing C: 0.05% to 0.10%, Si: 0.6% to 1.3%, Mn: 1.4% to 2.2%, P: 0.08% or less, S: 0.010% or less, Al: 0.01% to 0.08%, N: 0.010% or less, and the remainder being Fe and incidental impurities, on a percent by mass basis, and a microstructure in which the average grain size of ferrite is 15 μm or less, the volume fraction of ferrite is 70% or more, the volume fraction of bainite is 3% or more, the volume fraction of retained austenite is 4% to 7%, the average grain size of martensite is 5 μm or less, and the volume fraction of martensite is 1% to 6%, wherein the average C concentration (percent by mass) in the retained austenite is 0.30% to 0.70%, yield ratio is 64% or less, and the tensile strength is 590 MPa or more.

Abstract translation: 具有低屈服比的高强度冷轧钢板具有C：0.05〜0.10％，Si：0.6〜1.3％，Mn：1.4〜2.2％，P：0.08％以下的化学成分，S： 0.010％以下，Al：0.01〜0.08％，N：0.010％以下，剩余部分为Fe及杂质，以质量计为基准，铁素体的平均粒径为15μm的组织 以下，铁素体的体积分率为70％以上，贝氏体的体积分率为3％以上，残留奥氏体的体积分数为4％〜7％，马氏体的平均粒径为5μm以下， 马氏体的体积分率为1〜6％，残留奥氏体中的平均C浓度（质量％）为0.30〜0.70％，屈服比为64％以下，拉伸强度为590MPa， 更多。