公开(公告)号：US20250075285A1

公开(公告)日：2025-03-06

申请号：US18727157

申请日：2022-12-06

Applicant: JFE Steel Corporation

Inventor： Ryohei MORIMOTO ,  Lingling YANG ,  Yuki TOJI

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06

Abstract: A high-strength steel sheet having a tensile strength of 1320 MPa or more is disclosed. The above-described high-strength steel sheet includes a specific component composition, wherein a diffusible hydrogen in steel is 0.50 ppm by mass or less, tempered martensite and bainite are 70.0% or more, fresh martensite is 15.0% or less, iron-based carbides existing in the tempered martensite and the bainite have an average equivalent circular radius of 0.10 μm or less and an average aspect ratio of 4.5 or less, and a proportion p of tempered martensite and bainite including iron-based carbides, which have major axes facing the same direction within a range of 0 to 10°, at a number density of 7 to 35/μm2 among the tempered martensite and the bainite is 25 to 70%.

公开(公告)号：US20240360532A1

公开(公告)日：2024-10-31

申请号：US18681864

申请日：2022-06-21

Applicant: JFE STEEL CORPORATION

Inventor： Yuji TANAKA ,  Takeshi NISHIYAMA ,  Masanari TOMOZAWA ,  Kazuki ENDOH ,  Hidekazu MINAMI ,  Junya TOBATA ,  Yuki TOJI

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

CPC classification number: C21D9/46 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0268 ,  C21D8/0273 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12

Abstract: The steel sheet comprising a chemical composition containing C, Si, Mn, P, S, Al, N, Ti, Nb, and B, with the balance being Fe and inevitable impurities, and satisfying predetermined formula, in which the total area ratio of martensite and bainite is 95% or more, the average grain size of prior austenite grains is 10 μm or less, the B concentration at a prior austenite grain boundary is 0.10% or more in mass %, a C-concentrated region is provided along a martensitic grain boundary, and the C-concentrated region has a C concentration of 4.0 times or more than the C content in the steel, and the C-concentrated region has a concentration width of 3 nm or more and 100 nm or less in a direction perpendicular to the martensitic grain boundary and a length of 100 nm or more in a direction parallel to the martensitic grain boundary.

公开(公告)号：US20210115541A1

公开(公告)日：2021-04-22

申请号：US17042250

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki ENDO ,  Yoshiyasu KAWASAKI ,  Yuki TOJI ,  Yoshimasa FUNAKAWA ,  Mai AOYAMA

IPC: C22C38/04 ,  C22C33/02 ,  B21B27/10 ,  C21D6/00 ,  C21D8/02

Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80%, martensite being 5% to 35%, and tempered martensite being 0% to 5% in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 μm or less; and the retained austenite being 3 μm or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.

公开(公告)号：US20240368719A1

公开(公告)日：2024-11-07

申请号：US18565265

申请日：2022-03-28

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu MINAMI ,  Masayasu UENO ,  Yuki TOJI ,  Yuji TANAKA ,  Junya TOBATA ,  Kazuki ENDOH

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06

Abstract: Provided is a high strength steel sheet with high stretch flangeability and high YR in the rolling direction as well as in the direction orthogonal to the rolling direction with TS of 1180 MPa or more. The high strength steel sheet has a prescribed chemical composition and steel microstructure. In particular, an average grain size of the hard phase is 5.3 μm or less, the volume fraction-carbon concentration ratio of retained austenite (γ) is 0.10 or more and 0.45 or less, and the integration degree of {112} orientation is 1.0 or more.

公开(公告)号：US20230357883A1

公开(公告)日：2023-11-09

申请号：US18004880

申请日：2021-05-07

Applicant: JFE STEEL CORPORATION

Inventor： Yuki TOJI ,  Kazuki ENDOH ,  Hidekazu MINAMI

IPC: C21D10/00 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/60 ,  C22C38/40 ,  C22C38/38 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/20 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

CPC classification number: C21D10/00 ,  C21D9/46 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D6/001 ,  C21D6/002 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C22C38/60 ,  C22C38/40 ,  C22C38/38 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/20 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/005 ,  C22C38/002 ,  C22C38/001 ,  C23C2/40

Abstract: Provided are a steel sheet dehydrogenation apparatus, a steel sheet production system, and a steel sheet production method capable of producing a steel sheet excellent in hydrogen embrittlement resistance without changing the mechanical properties of the steel sheet. A dehydrogenation apparatus comprises: a housing configured to house a steel sheet coil obtained by coiling a steel strip; and a sound wave irradiator configured to irradiate the steel sheet coil housed in the housing with sound waves to obtain a product coil.

公开(公告)号：US20230265539A1

公开(公告)日：2023-08-24

申请号：US18005186

申请日：2021-05-11

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu MINAMI ,  Kazuki ENDOH ,  Yuki TOJI

IPC: C21D9/56 ,  C21D9/46 ,  C21D3/06 ,  C21D1/26 ,  C21D1/04 ,  C21D6/00 ,  C23C2/40 ,  C23C2/26 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

CPC classification number: C21D9/562 ,  C21D9/561 ,  C21D9/46 ,  C21D3/06 ,  C21D1/26 ,  C21D1/04 ,  C21D6/008 ,  C21D6/005 ,  C23C2/40 ,  C23C2/26 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/002 ,  C22C38/001 ,  C21D2241/00 ,  C22C2202/04

Abstract: Provided is a continuous annealing line capable of producing a steel sheet excellent in hydrogen embrittlement resistance. A continuous annealing line 100 comprises: a payoff reel 10 configured to uncoil a cold-rolled coil C to feed a cold-rolled steel sheet S; an annealing furnace 20 configured to continuously anneal the cold-rolled steel sheet S and including a heating zone 22, a soaking zone 24, and a cooling zone 26 that are arranged from an upstream side in a sheet passing direction; a downstream line 30 configured to continuously pass the cold-rolled steel sheet S discharged from the annealing furnace 20 therethrough; a tension reel 50 configured to coil the cold-rolled steel sheet S; and a sound wave irradiator 60 configured to irradiate the cold-rolled steel sheet S being passed from the cooling zone 26 to the tension reel 50 with sound waves.

公开(公告)号：US20240150876A1

公开(公告)日：2024-05-09

申请号：US18549921

申请日：2022-02-28

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Yuki TOJI ,  Tatsuya NAKAGAITO ,  Shinya YAMAGUCHI ,  Masayasu UENO ,  Katsutoshi TAKASHIMA ,  Tomohiro ONO

IPC: C22C38/04 ,  C21D3/06 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/02 ,  C22C38/06 ,  C23C2/06 ,  C23C2/28

CPC classification number: C22C38/04 ,  C21D3/06 ,  C21D6/005 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C21D9/46 ,  C22C38/02 ,  C22C38/06 ,  C23C2/06 ,  C23C2/28 ,  C21D2211/005

Abstract: A clad steel plate having tensile strength (TS) of 780 MPa or more, excellent bendability, collision resistance, and LME resistance. The clad steel plate having a base metal and a cladding metal on front and back surfaces of the base metal, and the chemical composition and microstructure of the base metal and the cladding metal being appropriately controlled so that the average Vickers hardness (HVL) of the cladding metal is 260 or less, the average Vickers hardness (HVL) of the cladding metal divided by the average Vickers hardness (HVB) of the base metal is 0.80 or less, the boundary roughness between the base metal and the cladding metal is 50 μm or less at the maximum height Ry, and the number of voids at the boundary between the base metal and the cladding metal is controlled to 20 or fewer per 10 mm length of the boundary.

公开(公告)号：US20210010101A1

公开(公告)日：2021-01-14

申请号：US17042291

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki ENDO ,  Yoshiyasu KAWASAKI ,  Yuki TOJI ,  Yoshimasa FUNAKAWA ,  Mai AOYAMA

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

Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80% and tempered martensite being greater than 5% and 20% or less in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 μm or less; and the retained austenite being 3 μm or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.

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.