公开(公告)号：US20180044751A1

公开(公告)日：2018-02-15

申请号：US15553753

申请日：2015-12-21

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Yoshimasa Funakawa

IPC: C21D9/46 ,  C22C38/28 ,  C22C38/16 ,  C22C38/12 ,  C21D6/00 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C22C38/38 ,  C22C38/08

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0263 ,  C21D8/0273 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/34 ,  C22C38/38

Abstract: A high-strength cold-rolled steel sheet having a tensile strength (TS) of 1150 MPa or more and excellent elongation and delayed fracturing resistance, as well as a method for manufacturing the steel sheet. The steel sheet has a chemical composition containing, by mass %, C: 0.16% to 0.30%, Si: 1.20% to 2.20%, Mn: 1.50% to 2.50%, P: 0.05% or less, S: 0.005% or less, Al: 0.10% or less, N: 0.007% or less, at least one of Ti and Nb, and the balance being Fe and inevitable impurities, wherein the combined mass % of Ti and Nb is 0.04% to 0.15%, and a multi-phase microstructure including ferrite having an average crystal grain diameter of 3 μm or less in an amount of 45% to 65% in terms of volume fraction, tempered martensite having an average crystal grain diameter of 2 μm or less in an amount of 35% to 55% in terms of volume fraction, and optionally non-recrystallized ferrite having an average crystal grain diameter of 5 μm or less in an amount of 5% or less.

公开(公告)号：US20180037969A1

公开(公告)日：2018-02-08

申请号：US15556448

申请日：2016-02-16

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Katsutoshi Takashima ,  Kohei Hasegawa ,  Yoshimasa Funakawa

IPC: C21D9/46 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C23G1/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C22C38/38 ,  C22C38/08

CPC classification number: C21D9/46 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0273 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/38 ,  C22C38/60 ,  C23G1/00 ,  C23G1/08 ,  C23G1/081

Abstract: A steel sheet contains C: 0.15% to 0.22%, Si: 1.0% to 2.0%, Mn: 1.7% to 2.5%, P: 0.05% or less, S: 0.02% or less, Al: 0.01% to 0.05%, N: 0.005% or less, O: 0.01% or less, and the balance being iron and unavoidable impurities while satisfying [Si]/[Mn]≧0.5 ([Si] and [Mn] represent Si and Mn contents, wherein the steel sheet has a structure including, in terms of area fraction, 60% to less than 100% of tempered martensite, 5% or less including 0% of untransformed austenite, and the balance being ferrite, and the ferrite has an average crystal grain size of less than 3.5 μm, wherein less than 10 particles/100 μm2 of Si—Mn compound oxide particles having a circle equivalent diameter of 5 μm or less are present on a surface of the steel sheet, and the surface is covered with Si-based oxide at a coverage of 1% or less.

公开(公告)号：US20170145534A1

公开(公告)日：2017-05-25

申请号：US15129938

申请日：2015-03-13

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Yoshihiko Ono ,  Kohei Hasegawa

IPC: C21D9/46 ,  C22C38/32 ,  C22C38/28 ,  C22C38/16 ,  C22C38/14 ,  C21D8/02 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/38 ,  C22C38/12

CPC classification number: C21D9/46 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0273 ,  C21D8/0278 ,  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 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38

Abstract: A high-strength cold-rolled steel sheet has a composite structure containing 0.15 to 0.25% by mass of C, 1.8 to 3.0% by mass of Mn, and 0.0003 to 0.0050% by mass of B, and having a ferrite volume fraction of 20% to 50%, a retained austenite volume fraction of 7% to 20%, a martensite volume fraction of 1% to 8%, and the balance containing bainite and tempered martensite, and in the composite structure, ferrite has an average crystal grain diameter of 5 μm or less, retained austenite has an average crystal grain diameter of 0.3 to 2.0 μm and an aspect ratio of 4 or more, martensite has an average crystal grain diameter of 2 μm or less, a metal phase containing both bainite and tempered martensite has an average crystal grain diameter of 7 μm or less, the ratio of the volume fraction of tempered martensite to the volume fraction of a metal structure other than ferrite is 0.60 to 0.85, and the average C concentration in retained austenite is 0.65% by mass or more.

公开(公告)号：US09574254B2

公开(公告)日：2017-02-21

申请号：US14346786

申请日：2012-09-27

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Yuki Toji ,  Kohei Hasegawa ,  Shinya Yamaguchi

IPC: C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/26 ,  C23C2/06 ,  C21D9/46 ,  C22C38/12 ,  B32B15/01 ,  C22C38/00 ,  C21D8/02 ,  C22C18/00 ,  C22C18/02

CPC classification number: C22C38/26 ,  B32B15/013 ,  C21D8/0263 ,  C21D9/46 ,  C21D2211/005 ,  C22C18/00 ,  C22C18/02 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C23C2/06

Abstract: A hot rolled steel sheet has a chemical composition including, by mass %, C: 0.060% to 0.120%; Si: 0.10% to 0.70%; Mn: 1.00% to 1.80%; P: 0.10% or less; S: 0.010% or less; Al: 0.01% to 0.10%; N: 0.010% or less; Nb: 0.010% to 0.100%, wherein Nb is contained so that content of solute Nb is 5% or more relative to the total Nb content; the balance being Fe and incidental impurities. The hot rolled steel sheet has a microstructure containing ferrite of not more than 15 μm in average crystal grain diameter by a volume fraction of not less than 75%, the balance being low-temperature-induced phases. The hot rolled steel sheet can be suitably utilized for manufacturing a cold rolled steel sheet or hot-dip galvanized steel sheet having a tensile strength of 590 MPa or more, excellent in material homogeneity and capable of giving excellent cold rolling property.

Abstract translation: 热轧钢板具有质量％C：0.060〜0.120％的化学成分， Si：0.10〜0.70％ Mn：1.00〜1.80％ P：0.10％以下; S：0.010％以下; Al：0.01〜0.10％ N：0.010％以下; Nb：0.010〜0.100％，其中Nb含量相对于总Nb含量为5％以上; 余量为Fe和杂质。 该热轧钢板的平均结晶粒径为15μm以下的铁素体，其体积分数为75％以上，余量为低温诱导相。 热轧钢板可以适用于制造拉伸强度为590MPa以上的冷轧钢板或热浸镀锌钢板，材料均匀性优异，能够得到优异的冷轧性。

公开(公告)号：US20160177427A1

公开(公告)日：2016-06-23

申请号：US14911088

申请日：2014-07-18

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Yoshihiko Ono ,  Kohei Hasegawa

IPC: C22C38/38 ,  C22C38/28 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C21D1/84 ,  C22C38/32

CPC classification number: C22C38/38 ,  C21D1/25 ,  C21D1/84 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0221 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D8/0463 ,  C21D8/0473 ,  C21D9/46 ,  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 ,  C22C38/28 ,  C22C38/32

Abstract: A steel sheet includes a microstructure containing a volume fraction of 20% to 55% of ferrite having an average grain size of 7 μm or less, a volume fraction of 5% to 15% of retained austenite, a volume fraction of 0.5% to 7% of martensite having an average grain size of 4 μm or less, and a structure composed of bainite and/or tempered martensite and having an average grain size of 6 μm or less, and a difference in nano-hardness between ferrite and the structure composed of bainite and/or tempered martensite being 3.5 GPa or less and a difference in nano-hardness between the structure composed of bainite and/or tempered martensite and martensite being 2.5 GPa or less.

Abstract translation: 钢板包括含有平均粒径为7μm以下的铁素体的体积分率为20〜55％，残留奥氏体的5〜15％的体积分数，0.5〜7的体积分数的微结构 平均粒径为4μm以下的马氏体的％，由贝氏体和/或回火马氏体组成的平均粒径为6μm以下的结构，以及铁素体与构成的结构之间的纳米硬度差 的贝氏体和/或回火马氏体为3.5GPa以下，并且由贝氏体和/或回火马氏体组成的结构和马氏体之间的纳米硬度差为2.5GPa以下。

公开(公告)号：US20140332119A1

公开(公告)日：2014-11-13

申请号：US14363171

申请日：2012-12-03

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Yuki Toji ,  Kohei Hasegawa

IPC: C22C38/34 ,  C22C38/16 ,  C22C38/14 ,  C22C38/00 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C21D8/02 ,  C22C38/12

CPC classification number: C22C38/34 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0273 ,  C21D8/0436 ,  C21D9/46 ,  C21D2211/005 ,  C21D2211/009 ,  C22C38/001 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/58

Abstract: A high strength cold rolled steel sheet has a chemical composition including, by mass %, C: 0.06 to 0.13%, Si: 1.2 to 2.3%, Mn: 0.6 to 1.6%, P: not more than 0.10%, S: not more than 0.010%, Al: 0.01 to 0.10% and N: not more than 0.010%, the balance comprising Fe and inevitable impurities. The steel sheet includes a microstructure containing not less than 90% in terms of volume fraction of ferrite with an average grain diameter of less than 20 μm and 1.0 to 10% in terms of volume fraction of pearlite with an average grain diameter of less than 5 μm. The ferrite has an average Vickers hardness of not less than 130. The steel sheet has a yield ratio of not less than 65% and a tensile strength of not less than 590 MPa.

Abstract translation: 高强度冷轧钢板具有以质量％计含有C：0.06〜0.13％，Si：1.2〜2.3％，Mn：0.6〜1.6％，P：0.10％以下，S：以上的化学成分 0.010％以下，Al：0.01〜0.10％，N：不大于0.010％，余量由Fe和不可避免的杂质构成。 该钢板包括平均粒径小于20μm的铁素体的体积分率为90％以上且平均粒径小于5的珠光体的体积分率为1.0〜10％的微结构 μm。 该铁素体的平均维氏硬度为130以上。钢板的屈服比为65％以上，拉伸强度为590MPa以上。