公开(公告)号：US11326238B2

公开(公告)日：2022-05-10

申请号：US16074184

申请日：2017-01-30

Applicant: JFE Steel Corporation

Inventor： Yuki Toji ,  Akio Ohmori ,  Koichi Nakashima ,  Ryo Arao ,  Katsuyuki Ichimiya ,  Kazukuni Hase

IPC: C22C38/54 ,  B23K35/30 ,  C22C38/00 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  B23K103/04

Abstract: Provided is a steel material for high heat input welding having excellent welding heat affected zone low-temperature toughness at −55° C. in the case that the steel material is welded by high heat input welding with a heat input of more than 80 kJ/cm. The steel material may be used in low-temperature storage tanks, for example. The steel material for high heat input welding includes, in mass %, C: 0.04 to 0.09%, Si: 0.15 to 0.25%, Mn: 1.40 to 2.00%, P: 0.015% or less, S: 0.0005 to 0.0040%, Al: 0.030 to 0.080%, Ti: 0.005 to 0.025%, B: 0.0003 to 0.0020%, Ca: 0.0005 to 0.0030%, N: 0.0030 to 0.0060%, O: 0.0040% or less, Nb: 0.005% or less, and Mo: 0.005% or less, the balance being Fe and incidental impurities.

公开(公告)号：US10174396B2

公开(公告)日：2019-01-08

申请号：US15115138

申请日：2015-01-21

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Yuki Toji ,  Kohei Hasegawa

IPC: C21D1/20 ,  C21D1/22 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/58

Abstract: A high-strength cold-rolled steel sheet has a chemical composition containing, by mass %, C: 0.15% or more and 0.30% or less, Si: 0.8% or more and 2.4% or less, Mn: 2.4% or more and 3.5% or less, P: 0.08% or less, S: 0.005% or less, Al: 0.01% or more and 0.08% or less, N: 0.010% or less, Ti: 0.002% or more and 0.05% or less, B: 0.0002% or more and 0.0050% or less, and the balance being Fe and inevitable impurities, a microstructure including ferrite having an average grain diameter of 3 μm or less and a volume fraction of 5% or less (including 0%), retained austenite having a volume fraction of 10% or more and 20% or less, martensite having an average grain diameter of 4 atm or less and a volume fraction of 20% or less (including 0%), and the balance including bainite and/or tempered martensite.

公开(公告)号：US09994941B2

公开(公告)日：2018-06-12

申请号：US14363171

申请日：2012-12-03

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Yuki Toji ,  Kohei Hasegawa

IPC: C22C38/02 ,  C22C38/04 ,  C21D8/02 ,  C21D9/46 ,  C22C38/34 ,  C22C38/06 ,  C22C38/58 ,  C22C38/00 ,  C22C38/12 ,  C22C38/14 ,  C21D8/04 ,  C22C38/08 ,  C22C38/16

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.

公开(公告)号：US20160369369A1

公开(公告)日：2016-12-22

申请号：US15115138

申请日：2015-01-21

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Yuki Toji ,  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 ,  C21D1/20 ,  C21D1/22 ,  C21D8/0221 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0263 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/003 ,  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 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/58

Abstract: A high-strength cold-rolled steel sheet has a chemical composition containing, by mass %, C: 0.15% or more and 0.30% or less, Si: 0.8% or more and 2.4% or less, Mn: 2.4% or more and 3.5% or less, P: 0.08% or less, S: 0.005% or less, Al: 0.01% or more and 0.08% or less, N: 0.010% or less, Ti: 0.002% or more and 0.05% or less, B: 0.0002% or more and 0.0050% or less, and the balance being Fe and inevitable impurities, a microstructure including ferrite having an average grain diameter of 3 μm or less and a volume fraction of 5% or less (including 0%), retained austenite having a volume fraction of 10% or more and 20% or less, martensite having an average grain diameter of 4 μm or less and a volume fraction of 20% or less (including 0%), and the balance including bainite and/or tempered martensite.

Abstract translation: 高强度冷轧钢板的化学成分以质量％计含有C：0.15％以上且0.30％以下，Si：0.8％以上且2.4％以下，Mn：2.4％以上， 3.5％以下，P：0.08％以下，S：0.005％以下，Al：0.01％以上且0.08％以下，N：0.010％以下，Ti：0.002％以上且0.05％以下， B：0.0002％以上且0.0050％以下，余量为Fe和不可避免的杂质，具有平均粒径为3μm以下，体积分率为5％以下（含0％）的铁素体的组织， 体积分数为10％以上且20％以下的残余奥氏体，平均粒径为4μm以下，体积分率为20％以下（包括0％）的马氏体，其余为贝氏体和/ 或回火马氏体。

公开(公告)号：US12188103B2

公开(公告)日：2025-01-07

申请号：US17770116

申请日：2020-10-08

Applicant: JFE Steel Corporation

Inventor： Kazuki Endoh ,  Yoshiyasu Kawasaki ,  Yuki Toji

IPC: C21D9/46 ,  B32B15/01 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: Provided is a high strength steel sheet that has a predetermined chemical composition and is manufactured under optimum conditions, the high strength steel sheet having a steel microstructure including, by area, ferrite: 30% or more and 80% or less, martensite: 5% or more and 35% or less, and retained austenite: 8% or more, wherein the quotient of the area fraction of grains of the retained austenite, the grains having an aspect ratio of 2.0 or more and a minor axis length of 1 μm or less, divided by the total area fraction of the retained austenite is 0.3 or more, wherein the quotient of the average Mn content (mass %) in the retained austenite divided by the average Mn content (mass %) in the ferrite is 1.5 or more.

公开(公告)号：US20240167128A1

公开(公告)日：2024-05-23

申请号：US18274778

申请日：2021-11-12

Applicant: JFE Steel Corporation

Inventor： Kazuki Endoh ,  Yoshiyasu Kawasaki ,  Yuki Toji

IPC: C22C38/04 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C23C2/06 ,  C23C2/28

CPC classification number: C22C38/04 ,  C21D6/005 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C22C38/02 ,  C22C38/06 ,  C23C2/06 ,  C23C2/28 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength steel sheet is disclosed having a specified chemical composition and a steel microstructure composed of, on an area fraction basis, ferrite: 1% to 40%, fresh martensite: less than 1.0%, bainite and tempered martensite in total: 40% to 90%, and retained austenite: 6% or more, wherein a value obtained by dividing an average Mn content (% by mass) of the retained austenite by an average Mn content (% by mass) of the ferrite is 1.1 or more, and a value obtained by dividing an average C content (% by mass) of retained austenite with an aspect ratio of 2.0 or more by an average C content (% by mass) of the ferrite is 3.0 or more, and a diffusible hydrogen content of steel is 0.3 ppm by mass or less.

公开(公告)号：US20240052449A1

公开(公告)日：2024-02-15

申请号：US17766398

申请日：2020-09-25

Applicant: JFE Steel Corporation

Inventor： Yoshiyasu Kawasaki ,  Yuki Toji ,  Muneka Iwasawa ,  Takayuki Futatsuka ,  Kentaro Sato

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/16 ,  C22C38/60 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C21D1/18 ,  C23C2/02 ,  C25D5/36 ,  C23C2/40 ,  C23C2/06 ,  C25D3/22 ,  C25D7/06

CPC classification number: C21D9/46 ,  C22C38/38 ,  C22C38/16 ,  C22C38/60 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/005 ,  C22C38/002 ,  C22C38/001 ,  C21D8/0205 ,  C21D8/021 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D1/18 ,  C23C2/0224 ,  C25D5/36 ,  C23C2/40 ,  C23C2/06 ,  C25D3/22 ,  C25D7/0614 ,  C21D2211/008 ,  C21D2211/005 ,  C21D2211/002 ,  C21D2211/001

Abstract: A high strength steel sheet has a yield-point elongation of 1% or greater and a tensile strength of 980 MPa or greater. The high strength steel sheet has a specific chemical composition and microstructure. A ratio of retained austenite grains adjoining a retained austenite grain having a different crystal orientation to total retained austenite grains is 0.60 or greater, the ferrite has an average grain size of 5.0 μm or less, and the retained austenite has an average grain size of 2.0 μm or less. A value obtained by dividing a volume fraction Vγa by a volume fraction Vγb is 0.40 or greater, where the volume fraction Vγa is a volume fraction of retained austenite in a fractured portion of a tensile test specimen after a warm tensile test at 150° C., and the volume fraction Vγb is a volume fraction of retained austenite before the warm tensile test at 150° C.

公开(公告)号：US20220396855A1

公开(公告)日：2022-12-15

申请号：US17770328

申请日：2020-10-08

Applicant: JFE Steel Corporation

Inventor： Kazuki Endoh ,  Yoshiyasu Kawasaki ,  Yuki Toji

IPC: C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/60 ,  C21D8/02 ,  C21D9/46 ,  C22C38/04 ,  C23C2/06 ,  C23C2/40

Abstract: Provided is a high strength steel sheet that has a predetermined chemical composition and is manufactured under optimum conditions, the high strength steel sheet having a steel microstructure including, by area, ferrite: 30% or more and 80% or less, martensite: 5% or more and 35% or less, and retained austenite: 8% or more, wherein the quotient of the area fraction of grains of the retained austenite, the grains having an aspect ratio of 2.0 or more and a minor axis length of 1 μm or less, divided by the total area fraction of the retained austenite is 0.3 or more, wherein the quotient of the average Mn content (mass %) in the retained austenite divided by the average Mn content (mass %) in the ferrite is 1.5 or more.

公开(公告)号：US11447840B2

公开(公告)日：2022-09-20

申请号：US16349422

申请日：2017-11-15

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Takako Yamashita ,  Masayasu Ueno ,  Yuki Toji ,  Takashi Kobayashi ,  Yoshimasa Funakawa

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

Abstract: To provide a high-strength steel sheet with excellent ductility and hole expansion formability, a yield ratio of less than 68%, and a tensile strength of 980 MPa or more, by having a predetermined chemical composition and a microstructure where ferrite is 15% or more and 55% or less and martensite is 15% or more and 30% or less in area ratio, retained austenite is 12% or more in volume fraction, the average grain size of ferrite, martensite and retained austenite is 4.0 μm or less, 2.0 μm or less and 2.0 μm or less respectively, the average aspect ratio of crystal grain of ferrite, martensite and retained austenite is each more than 2.0 and 15.0 or less, and the value obtained by dividing the Mn content (mass %) in retained austenite by the Mn content (mass %) in ferrite is 2.0 or more.

公开(公告)号：US11365459B2

公开(公告)日：2022-06-21

申请号：US16499592

申请日：2018-04-02

Applicant: JFE Steel Corporation

Inventor： Takaaki Tanaka ,  Yuki Toji

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38

Abstract: A high strength cold rolled steel sheet has a composition which contains, in terms of mass %, more than 0.15% and not more than 0.45% of C, 0.50-2.50% of Si, 1.50-3.00% of Mn, not more than 0.050% of P, not more than 0.0100% of S, 0.010-0.100% of Al and not more than 0.0100% of N, with the remainder including Fe and unavoidable impurities, has a total content of ferrite and bainitic ferrite of 20-80%, has a retained austenite content of more than 10% and not more than 40%, has a martensite content of more than 0% and not more than 50%, and is such that the proportion of retained austenite that has an aspect ratio of not more than 0.5 is not less than 75%, and the proportion of retained austenite having an aspect ratio of not more than 0.5 that is present at Bain group boundaries is not less than 50%.