公开(公告)号：US20230082367A1

公开(公告)日：2023-03-16

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 ,  C22C38/02 ,  C22C38/38 ,  C21D1/26 ,  C22C38/12 ,  C22C38/06 ,  C22C38/00 ,  C22C38/28 ,  C22C38/32 ,  C22C38/16 ,  C21D6/00 ,  C22C38/08 ,  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：US20230129828A1

公开(公告)日：2023-04-27

申请号：US17914895

申请日：2021-03-25

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Lingling YANG ,  Shotaro TERASHIMA ,  Hidekazu MINAMI ,  Tatsuya NAKAGAITO ,  Shunsuke YAMAMOTO ,  Katsuya HOSHINO ,  Yuki TAKEDA

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

Abstract: A steel sheet with a tensile strength (TS) of 780 MPa or more and less than 1180 MPa, 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 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：US20250003021A1

公开(公告)日：2025-01-02

申请号：US18709028

申请日：2022-10-14

Applicant: JFE STEEL CORPORATION

Inventor： Katsuya HATA ,  Shotaro TERASHIMA ,  Tatsuya NAKAGAITO ,  Seisuke TSUDA

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 ,  C22C38/22 ,  C22C38/24 ,  C22C38/28 ,  C22C38/38 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40

Abstract: A steel sheet having high strength, excellent ductility, high YR, and excellent bendability is provided. The steel sheet includes a defined chemical composition, the steel microstructure includes: area ratio of ferrite: 5% or more and 65% or less, area ratio of martensite: 10% or more and 60% or less, area ratio of bainite: 10% or more and 60% or less, and area ratio of retained austenite: 5% or more. The relationship in the following Formula (1) is satisfied. Average solute C concentration of the retained austenite [C]γ is 0.5 mass % or more, and standard deviation of C concentration distribution in the retained austenite is 0.250 mass % or less. [ Mn ] γ ⁢ / [ Mn ] ≤ 1.2 ( 1 )

公开(公告)号：US20240026481A1

公开(公告)日：2024-01-25

申请号：US18257151

申请日：2021-12-15

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Tatsuya NAKAGAITO ,  Masaki KOBA ,  Kyoko NAITO ,  Seisuke TSUDA ,  Katsuya HATA ,  Shotaro TERASHIMA

IPC: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C21D1/18

CPC classification number: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/002 ,  C22C38/001 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D1/18 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: Provided is a steel sheet having excellent workability while ensuring excellent strength. The steel sheet comprises: a predetermined chemical composition; and a steel microstructure that contains ferrite: 45% to 90%, martensite: 5% to 30%, bainite: 1% to 25%, and retained austenite: 3% or more and in which [Mn]M/[Mn] is 1.00 to 1.15 and [Mn]M/[Mn]F is 1.00 to 1.30, wherein TS×El is 16000 MPa·% or more.

公开(公告)号：US20230127243A1

公开(公告)日：2023-04-27

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

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：US20220251676A1

公开(公告)日：2022-08-11

申请号：US17630504

申请日：2020-06-19

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu MINAMI ,  Takeshi YOKOTA ,  Yoshiyasu KAWASAKI ,  Shotaro TERASHIMA

IPC: C21D9/46 ,  B32B15/01 ,  C22C38/58 ,  C22C38/44 ,  C22C38/32 ,  C22C38/30 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/20 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00

Abstract: Provided are a high-strength hot-dip galvanized steel sheet that has a tensile strength of 1180 MPa or more and excellent ductility, stretch flangeability, bendability and LME resistance and can manufacture parts with high dimensional accuracy, and its manufacturing method. The high-strength steel sheet with a tensile strength of 1180 MPa or more has a chemical composition containing C, Si, Mn, P, S, Al and N, with [% Si], [% Mn], [% P], [% Mo] and [% Cr] satisfying a predetermined relationship and the balance being Fe and inevitable impurities, and a steel microstructure including ferrite, tempered martensite and bainite, and retained austenite, where the diffusible hydrogen amount in the steel sheet is 0.60 mass ppm or less, a thickness of softened surface layer is 5 μm or more and 150 μm or less, and a frequency of coincidence boundary in the steel sheet surface layer after a high-temperature tensile test is 0.45 or less.

公开(公告)号：US20240035105A1

公开(公告)日：2024-02-01

申请号：US18257178

申请日：2021-12-15

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Tatsuya NAKAGAITO ,  Masaki KOBA ,  Yoichi MAKIMIZU ,  Katsuya HATA ,  Shotaro TERASHIMA

IPC: C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/38 ,  C22C38/06 ,  C23C2/06 ,  C23C2/40

CPC classification number: C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C22C38/001 ,  C22C38/02 ,  C22C38/38 ,  C22C38/06 ,  C22C38/002 ,  C23C2/06 ,  C23C2/40 ,  C21D2211/005 ,  C21D2211/002 ,  C21D2211/008

Abstract: Provided is a hot-dip galvanized steel sheet having both high strength and good workability, as well as excellent coating quality. The chemical composition of the base steel sheet is set within a specified range, the steel microstructure of the base steel sheet is a complex structure of ferrite, martensite and bainite, oxygen is present as oxides in the surface layer of the base steel sheet in an amount of 0.05 g/m2 or more and 0.50 g/m2 or less per surface, and the hot-dip galvanized layer contains Fe in an amount of 0.40 mass % or more.

公开(公告)号：US20230160032A1

公开(公告)日：2023-05-25

申请号：US17915696

申请日：2021-03-25

Applicant: JFE STEEL CORPORATION

Inventor： Lingling YANG ,  Yoshiyasu KAWASAKI ,  Hidekazu MINAMI ,  Tatsuya NAKAGAITO ,  Shotaro TERASHIMA ,  Shunsuke YAMAMOTO ,  Katsuya HOSHINO ,  Yuki TAKEDA

IPC: C21D9/46 ,  C23C2/40 ,  C23C2/06 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  B21C47/02

CPC classification number: C21D9/46 ,  C23C2/40 ,  C23C2/06 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  B21C47/02 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C21D2211/001

Abstract: A steel sheet having a tensile strength (TS) of 780 MPa or more and less than 1180 MPa, 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：US20230151451A1

公开(公告)日：2023-05-18

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

CPC classification number: C21D9/46 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C22C38/38 ,  C22C38/60 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/005 ,  C22C38/002 ,  C22C38/001 ,  B32B15/013 ,  C21D2211/001 ,  C21D2211/005

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).