公开(公告)号：US20250084501A1

公开(公告)日：2025-03-13

申请号：US18727874

申请日：2022-10-12

Applicant: JFE STEEL CORPORATION

Inventor： Sho HIGUCHI ,  Yoshiyasu KAWASAKI ,  Tatsuya NAKAGAITO ,  Takako YAMASHITA

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28

Abstract: Provided is a galvanized steel sheet having high strength, excellent ductility, excellent strain hardenability in a low strain range, and excellent strain hardenability in a high strain range. A base steel sheet has a defined chemical composition and a steel microstructure as follows: area fraction of ferrite: 20.0% or more and 90.0% or less, area fraction of bainitic ferrite: 4.0 % or more and 60.0% or less, area fraction of tempered martensite: 20.0% or less (including 0%), area fraction of retained austenite: 3.0% or more, area fraction of fresh martensite: 20.0% or less (including 0%), SF+SBF: 55.0% or more and 95.0% or less, SMA1: 4.0% or more, and SMA2: 1.5% or more.

公开(公告)号：US20240117517A1

公开(公告)日：2024-04-11

申请号：US18250978

申请日：2021-11-05

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke YAMAMOTO ,  Katsutoshi TAKASHIMA ,  Yusuke OKUMURA ,  Tomomi KANAZAWA ,  Katsuya HOSHINO ,  Takashi KAWANO ,  Takako YAMASHITA ,  Hiroshi MATSUDA ,  Yoichi MAKIMIZU

IPC: C25D3/20 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C25D7/06

CPC classification number: C25D3/20 ,  C21D8/0236 ,  C21D8/0257 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C25D7/0614

Abstract: Disclosed is an Fe-based electroplated steel sheet including: a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; and an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of 5.0 g/m2 or more, in which in an intensity profile measured by glow discharge optical emission spectrometry, a peak of emission intensity at wavelengths indicating Si is detected within a range from a surface of the Fe-based electroplating layer to more than 0.2 μm in a thickness direction and not more than a thickness of the Fe-based electroplating layer, and an average value of C concentration in a region ranging from 10 μm to 20 μm in the thickness direction from the surface of the Fe-based electroplating layer is 0.10 mass % or less.

公开(公告)号：US20220340989A1

公开(公告)日：2022-10-27

申请号：US17636714

申请日：2020-06-19

Applicant: JFE STEEL CORPORATION

Inventor： Yuji TANAKA ,  Hidekazu MINAMI ,  Naoki TAKAYAMA ,  Takako YAMASHITA

IPC: C21D9/46 ,  B32B15/01 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/16 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23C2/40 ,  C23C2/28

Abstract: A high-strength cold-rolled steel sheet having a high yield ratio and excellent stretch flangeability and a method for manufacturing the steel sheet. The high-strength cold-rolled steel sheet has a chemical composition including, by mass %, C: 0.10 to 0.30%, Si: 0.50 to 2.00%, Mn: 2.5 to 4.0%, P: 0.050% or less, S: 0.020% or less, Al: 0.10% or less, N: 0.01% or less, Ti: 0.100% or less, and B: 0.0003 to 0.0030%, with the balance being Fe and incidental impurities. N and Ti satisfy a specified formula, and the total area fraction of martensite and bainite is 95% or more. The number density of bainite grains having an area of 3 μm2 or more and a carbon concentration of less than 0.7C is 1200 grains/mm2 or less.

公开(公告)号：US20190284656A1

公开(公告)日：2019-09-19

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 ,  C23C2/02 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C22C38/38 ,  C22C38/08

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：US20190271051A1

公开(公告)日：2019-09-05

申请号：US16349443

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 ,  C23C2/12 ,  C23C2/40 ,  C23C2/02 ,  C22C38/00 ,  C22C38/06 ,  C22C38/02 ,  C22C38/14 ,  C22C38/60 ,  C22C38/38 ,  C22C38/12 ,  C22C38/16 ,  C22C38/08 ,  C21D9/46

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 590 MPa or more, by having a predetermined chemical composition and a microstructure where ferrite is 35% or more and 80% or less and martensite is 5% or more and 25% or less in area ratio, retained austenite is 8% or more in volume fraction, the average grain size of ferrite, martensite and retained austenite is 6.0 μm or less, 3.0 μm or less and 3.0 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：US20230407484A1

公开(公告)日：2023-12-21

申请号：US18251242

申请日：2021-11-05

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke YAMAMOTO ,  Katsutoshi TAKASHIMA ,  Yusuke OKUMURA ,  Tomomi KANAZAWA ,  Katsuya HOSHINO ,  Takashi KAWANO ,  Takako YAMASHITA ,  Hiroshi MATSUDA ,  Yoichi MAKIMIZU

IPC: C23C28/02 ,  C23C2/28 ,  C23C2/06 ,  C22C38/02 ,  C25D3/20 ,  C23C2/02 ,  C22C38/06 ,  C22C38/04 ,  C21D8/02

CPC classification number: C23C28/021 ,  C23C2/28 ,  C23C2/06 ,  C22C38/02 ,  C25D3/20 ,  C23C2/022 ,  C22C38/06 ,  C22C38/04 ,  C21D8/0236

Abstract: Disclosed is a galvannealed steel sheet including: a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet; and a galvannealed layer formed on the Fe-based electroplating layer, in which in an intensity profile measured by glow discharge optical emission spectrometry, ISi,Fe/ISi,bulk is 0.30 or more, and an average value of C concentration in a region ranging from 10 μm to 20 μm in the thickness direction from the interface between the galvannealed layer and the Fe-based electroplating layer towards the Fe-based electroplating layer is 0.10 mass % or less.

公开(公告)号：US20190276907A1

公开(公告)日：2019-09-12

申请号：US16090883

申请日：2017-03-08

Applicant: JFE STEEL CORPORATION

Inventor： Takako YAMASHITA ,  Yoshiyasu KAWASAKI ,  Takashi KOBAYASHI ,  Masayasu UENO ,  Yasunobu NAGATAKI

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

Abstract: A steel sheet having TS of 590 MPa or more and YR of 68% or more is obtained by providing a predetermined chemical composition and a predetermined steel microstructure, where an average aspect ratio of crystal grains of each phase (polygonal ferrite, martensite, and retained austenite) is 2.0 or more and 15.0 or less, wherein the polygonal ferrite has an average grain size of 6 μm or less, the martensite has an average grain size of 3 μm or less, the retained austenite has an average grain size of 3 μm or less, and a value obtained by dividing a Mn content in the retained austenite in mass % by a Mn content in the polygonal ferrite in mass % equals 2.0 or more.

公开(公告)号：US20190106760A1

公开(公告)日：2019-04-11

申请号：US16090892

申请日：2017-03-08

Applicant: JFE STEEL CORPORATION

Inventor： Takako YAMASHITA ,  Yoshiyasu KAWASAKI ,  Takashi KOBAYASHI ,  Masayasu UENO ,  Yasunobu NAGATAKI

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

Abstract: A steel sheet having TS of 980 MPa or more and YR of 68% or more is obtained by providing a predetermined chemical composition and a predetermined steel microstructure, where an average aspect ratio of crystal grains of each phase (polygonal ferrite, martensite, and retained austenite) is 2.0 or more and 20.0 or less, wherein the polygonal ferrite has an average grain size of 4 μm or less, the martensite has an average grain size of 2 μm or less, the retained austenite has an average grain size of 2 μm or less, and a value obtained by dividing a Mn content in the retained austenite in mass % by a Mn content in the polygonal ferrite in mass % equals 2.0 or more.

公开(公告)号：US20170298482A1

公开(公告)日：2017-10-19

申请号：US15516698

申请日：2015-10-29

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Hiroshi MATSUDA ,  Takeshi YOKOTA ,  Takako YAMASHITA ,  Kazuhiro SETO

IPC: C22C38/14 ,  B32B15/01 ,  C23C2/40 ,  C23C2/12 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C21D1/26 ,  C23F17/00 ,  B32B15/18 ,  B32B15/20 ,  C25D3/22

Abstract: Disclosed is a steel sheet having a predetermined chemical composition and a steel microstructure that contains, in area ratio, 15% or more and 55% or less of polygonal ferrite and 15% or more and 30% or less of martensite, and that contains, in volume fraction, 12% or more of retained austenite, in which the polygonal ferrite, the martensite, and the retained austenite have a mean grain size of 4 μm or less, 2 μm or less, and 2 μm or less, respectively, and each have a mean grain aspect ratio of 2.0 or less, and in which a value obtained by dividing an Mn content in the retained austenite in mass % by an Mn content in the polygonal ferrite in mass % equals 2.0 or more.

公开(公告)号：US20240318287A1

公开(公告)日：2024-09-26

申请号：US18579575

申请日：2022-03-18

Applicant: JFE STEEL CORPORATION

Inventor： Sho HIGUCHI ,  Yoshiyasu KAWASAKI ,  Tatsuya NAKAGAITO ,  Takako YAMASHITA ,  Tomomi KANAZAWA ,  Shunsuke YAMAMOTO

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 ,  C23C2/29 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A galvanized steel sheet combining high strength with excellent formability, specifically, excellent ductility, hole expansion formability, local ductility, strain hardenability, and dimensional accuracy when forming a member. The base steel sheet has a defined chemical composition and a steel microstructure as follows: ferrite area ratio: 35.0% or more and 95.0% or less, bainitic ferrite area ratio: 1.0% or more and 40.0% or less, tempered martensite area ratio: 50.0% or less (including 0%), retained austenite area ratio: 1.5% or more, fresh martensite area ratio: 20.0% or less (including 0 %), SBF+STM+2×SMA: 10.0% or more and less than 65.0%, SBF+STM: 3.0 % or more and 60.0% or less, SMA1/SMA: 0.40 or less, IDR [% Cγ]: 0.16% or more, and tensile strength: 590 MPa or more and less than 980 MPa.