公开(公告)号：US12098439B2

公开(公告)日：2024-09-24

申请号：US17915739

申请日：2021-03-25

Applicant: JFE STEEL CORPORATION

Inventor： Lingling Yang ,  Yoshiyasu Kawasaki ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Shunsuke Yamamoto ,  Katsuya Hoshino ,  Yuki Takeda

IPC: C22C38/60 ,  B21C47/02 ,  B32B15/01 ,  B32B15/04 ,  B32B15/18 ,  C21D1/18 ,  C21D1/25 ,  C21D1/76 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/30 ,  C22C38/32 ,  C22C38/34 ,  C22C38/38 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/58 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23C28/00 ,  C23C28/02 ,  C23C30/00

CPC classification number: C21D9/46 ,  B21C47/02 ,  B32B15/013 ,  B32B15/015 ,  B32B15/04 ,  B32B15/043 ,  B32B15/18 ,  C21D1/185 ,  C21D1/25 ,  C21D1/76 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0242 ,  C21D8/0263 ,  C21D8/0273 ,  C21D8/0278 ,  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 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/30 ,  C22C38/32 ,  C22C38/34 ,  C22C38/38 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/285 ,  C23C2/29 ,  C23C2/40 ,  C23C28/021 ,  C23C28/025 ,  C23C28/3225 ,  C23C30/00 ,  C23C30/005 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  Y10T428/12458 ,  Y10T428/12792 ,  Y10T428/12958 ,  Y10T428/12965 ,  Y10T428/12972 ,  Y10T428/24942 ,  Y10T428/2495 ,  Y10T428/24967 ,  Y10T428/24983 ,  Y10T428/26 ,  Y10T428/263 ,  Y10T428/264 ,  Y10T428/265

Abstract: A steel sheet having a tensile strength (TS) of 1180 MPa or more, high LME resistance, and good weld fatigue properties. The steel sheet has a specific chemical composition and a specific steel microstructure. Crystal grains containing an oxide of Si and/or Mn in a region within 4.9 μm in a thickness direction from a surface of the steel sheet have an average grain size in the range of 3 to 10 μm, the lowest Si concentration LSi and the lowest Mn concentration LMn in the region within 4.9 μm in the thickness direction from the surface of the steel sheet and a Si concentration TSi and a Mn concentration TMn at a quarter thickness position of the steel sheet satisfy a specified formula.

公开(公告)号：US20230072557A1

公开(公告)日：2023-03-09

申请号：US17800957

申请日：2021-02-24

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Lingling Yang ,  Takeshi Yokota

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

Abstract: A steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, in terms of area fraction, ferrite: 20% or more and 60% or less, a total of bainite and tempered martensite: 25% or more and 60% or less, retained austenite: 7% or more and 20% or less, fresh martensite: 8% or more and 40% or less, and the remainder: 5% or less. Cementite particles are present in the retained austenite, a ratio of an area fraction of the cementite particles in the retained austenite to an area fraction of the retained austenite is 5% or more and 25% or less, and the steel sheet has a tensile strength of 980 MPa or more.

公开(公告)号：US12276006B2

公开(公告)日：2025-04-15

申请号：US17760362

申请日：2020-11-19

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke Yamamoto ,  Shotaro Terashima ,  Yuki Takeda ,  Michitaka Sakurai ,  Katsuya Hoshino ,  Yoshiyasu Kawasaki

IPC: C21D9/46 ,  C21D1/26 ,  C21D6/00 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C23C2/02 ,  C23C2/28 ,  C23C2/40

Abstract: To obtain a high-strength hot-dip galvanized steel sheet having excellent surface appearance even in the case where a steel strip containing Mn at a predetermined ratio or more to Si is subjected to hot-dip galvanizing treatment, a method of producing a hot-dip galvanized steel sheet using a continuous hot-dip galvanizing apparatus comprises: subjecting a steel strip to annealing, by conveying it in an annealing furnace; and subjecting the steel strip discharged from a cooling zone to hot-dip galvanizing using a hot-dip galvanizing line, to obtain a hot-dip galvanized steel sheet. The steel strip has a chemical composition containing, in mass %, Mn: 1.7% or more and 3.5% or less and Si: 0.2% or more and 1.05% or less and satisfying [Si]/[Mn]≤0.30. The chemical composition, a dew point of an atmosphere in the soaking zone, and a delivery temperature of the heating zone satisfy Formula (1).

公开(公告)号：US20230349020A1

公开(公告)日：2023-11-02

申请号：US17800669

申请日：2021-02-24

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Lingling Yang ,  Takeshi Yokota

IPC: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/34 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C21D1/18 ,  C23C2/06

CPC classification number: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/34 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/005 ,  C22C38/002 ,  C22C38/001 ,  C21D8/0205 ,  C21D8/0278 ,  C21D8/0263 ,  C21D8/0226 ,  C21D8/0236 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D1/18 ,  C23C2/06

Abstract: A steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, in terms of area fraction, ferrite: 40% or more and 70% or less, a total of bainite and tempered martensite: 5% or more and 30% or less, retained austenite: 4% or more and 18% or less, fresh martensite: 8% or more and 35% or less, and the remainder: 5% or less. Cementite particles are present in the retained austenite, a ratio of an area fraction of the cementite particles in the retained austenite to an area fraction of the retained austenite is 5% or more and 25% or less, and the steel sheet has a tensile strength of 780 MPa or more and less than 980 MPa.

公开(公告)号：US12297515B2

公开(公告)日：2025-05-13

申请号：US17915020

申请日：2021-03-25

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Lingling Yang ,  Shotaro Terashima ,  Tatsuya Nakagaito ,  Shunsuke Yamamoto ,  Katsuya Hoshino ,  Yuki Takeda

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

Abstract: A steel sheet with a tensile strength (TS) of 1180 MPa or more, a member, and a method for producing them. In a region of the steel sheet within 4.9 μm in the thickness direction, a region with a Si concentration not more than one-third of the Si concentration in the chemical composition of the steel sheet and with a Mn concentration not more than one-third of the Mn concentration in the chemical composition of the steel sheet has a thickness of 1.0 μm or more. The lowest Si concentration LSi and the lowest Mn concentration LMn in the region within 4.9 μm in the thickness direction from the surface of the steel sheet and a Si concentration TSi and a Mn concentration TMn at a quarter thickness position of the steel sheet satisfy the following formula (1): LSi+LMn≤(TSi+TMn)/4  (1).

公开(公告)号：US12258647B2

公开(公告)日：2025-03-25

申请号：US17800669

申请日：2021-02-24

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Lingling Yang ,  Takeshi Yokota

IPC: C21D9/46 ,  C21D1/18 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/34 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06

Abstract: A steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, in terms of area fraction, ferrite: 40% or more and 70% or less, a total of bainite and tempered martensite: 5% or more and 30% or less, retained austenite: 4% or more and 18% or less, fresh martensite: 8% or more and 35% or less, and the remainder: 5% or less. Cementite particles are present in the retained austenite, a ratio of an area fraction of the cementite particles in the retained austenite to an area fraction of the retained austenite is 5% or more and 25% or less, and the steel sheet has a tensile strength of 780 MPa or more and less than 980 MPa.

公开(公告)号：US20230349019A1

公开(公告)日：2023-11-02

申请号：US17800650

申请日：2021-02-24

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Lingling Yang ,  Takeshi Yokota ,  Shunsuke Yamamoto ,  Yuki Takeda

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

CPC classification number: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/001 ,  C22C38/002 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C23C2/40 ,  C21D2211/005 ,  C21D2211/002 ,  C21D2211/001 ,  C21D2211/008 ,  C21D2211/003

Abstract: A steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, in terms of area fraction, ferrite: 60% or more and 85% or less, bainite: 3% or more and 15% or less, retained austenite: 3% or more and 15% or less, fresh martensite: 3% or more and 15% or less, and the remainder: 5% or less. Cementite particles are present in the retained austenite, a ratio of an area fraction of the cementite particles in the retained austenite to an area fraction of the retained austenite is 5% or more and 25% or less, and the steel sheet has a tensile strength of 590 MPa or more and less than 780 MPa.

公开(公告)号：US11248277B2

公开(公告)日：2022-02-15

申请号：US16615004

申请日：2018-04-24

Applicant: JFE STEEL CORPORATION

Inventor： Shotaro Terashima ,  Yusuke Fushiwaki ,  Yoichi Makimizu ,  Hiroyuki Masuoka ,  Hiroshi Hasegawa

IPC: C21D9/46 ,  C23C2/02 ,  C23C2/06 ,  C23G1/08 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/20 ,  C22C38/32

Abstract: A method for manufacturing a high-strength galvanized steel sheet having excellent strength-elongation balance, coating adhesiveness, and surface appearance. The method includes: (i) a first heating process of heating a steel sheet having a predetermined chemical composition, (ii) a first pickling process of pickling the steel sheet which was subjected to the first heating process in an oxidizing acidic aqueous solution, (iii) a second pickling process of pickling the steel sheet which was subjected to the first pickling process in a non-oxidizing acidic aqueous solution, (iv) a second heating process of holding the steel sheet, which was subjected to the second pickling process, at a temperature range of 700° C. or higher and 900° C. or lower in a hydrogen-containing atmosphere for 20 seconds or more and 300 seconds or less, and (v) performing a galvanizing treatment on the steel sheet which was subjected to the second heating process.