公开(公告)号：US20240084412A1

公开(公告)日：2024-03-14

申请号：US18509476

申请日：2023-11-15

Applicant: JFE Steel Corporation

Inventor： Hidekazu Minami ,  Yoshimasa Funakawa ,  Shinjiro Kaneko

IPC: C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C23C2/02 ,  C23C2/28

CPC classification number: C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C23C2/02 ,  C23C2/0224 ,  C23C2/024 ,  C23C2/28 ,  C21D2211/005 ,  C21D2211/008

Abstract: Disclosed herein are a method for producing a hot-rolled steel sheet, a method for producing a cold-rolled full hard steel sheet, and methods for producing a heat-treated steel sheet that serve as the methods for producing intermediate products for obtaining a steel sheet having a tensile strength of 590 MPa or more, a particular composition and a particular steel structure.

公开(公告)号：US11578381B2

公开(公告)日：2023-02-14

申请号：US17447973

申请日：2021-09-17

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Shinjiro Kaneko

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C22C38/04 ,  C21D1/25 ,  C22C38/34 ,  C21D1/20 ,  C21D1/18 ,  C23C2/06 ,  B32B15/01 ,  C21D6/00 ,  C23C2/00

Abstract: A production method for a high-strength steel sheet having a tensile strength TS of 780 MPa or more is provided. The production method comprises: heating a steel slab having a predetermined chemical composition; hotrolling the steel slab; coiling the hot-rolled sheet; subjecting the hot-rolled sheet to pickling treatment; holding the hot-rolled sheet in a pre-determined temperature range for predetermined time; cold rolling the hot-rolled sheet to obtain a cold-rolled sheet; subjecting the cold-rolled sheet to first annealing treatment; cooling the cold-rolled sheet at a pre-determined average cooling rate; cooling the cold-rolled sheet to room temperature; reheating the clod-rolled sheet to perform second annealing treatment; cooling the cold-rolled sheet at a first average cooling rate; cooling the cold-rolled sheet at a second average cooling rate; reheating the cold-rolled sheet to a predetermined reheating temperature range; and holding the cold-rolled sheet in the reheating temperature range.

公开(公告)号：US11492677B2

公开(公告)日：2022-11-08

申请号：US16957739

申请日：2018-10-09

Applicant: JFE Steel Corporation

Inventor： Hiroshi Hasegawa ,  Hidekazu Minami ,  Tatsuya Nakagaito ,  Kana Sasaki ,  Shoji Tanaka

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/60 ,  C23C2/40

Abstract: A high-strength steel sheet has a specific composition and a microstructure. In the microstructure, the area fraction of elongated ferrite phase grains having an aspect ratio of 3 or more is 1% or less, the average crystal grain size of martensite included in a region extending 50 μm from a surface of the steel sheet is 20 μm or less, the content of oxide particles having a minor axis length of 0.8 μm or less in the region extending 50 μm from the surface of the steel sheet is 1.0×1010 particles/m2 or more, and the content of coarse oxide particles having a minor axis length of more than 1 μm in the region extending 50 μm from the surface of the steel sheet is 1.0×108 particles/m2 or less. The content of hydrogen trapped in the steel sheet is 0.05 ppm by mass or more.

公开(公告)号：US20220098687A1

公开(公告)日：2022-03-31

申请号：US17417865

申请日：2019-08-23

Applicant: JFE Steel Corporation

Inventor： Hiroshi Hasegawa ,  Hidekazu Minami ,  Tatsuya Nakagaito

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/00 ,  C21D8/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23G1/02 ,  C22C38/42 ,  C22C38/54 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/38 ,  C22C38/60

Abstract: A high-strength hot-dip galvanized steel sheet includes a hot-dip galvanized layer on a surface of the steel sheet and has a specific component composition and a steel microstructure containing, on an area percentage basis, 90% to 100% of martensite and carbide-containing bainite in total and 0% to 10% of retained austenite, and containing prior austenite grains having an aspect ratio of 2.0 or less, in a region extending from 300 μm to 400 μm from the surface layer, in which the ratio of the average amount of C at 5 μm from the surface layer to the average amount of C at 70 μm from the surface layer is 0.2 to 0.8, and the ratio of the standard deviation of the amount of C to the average amount of C in a region extending from 300 μm to 400 μm from the surface layer is 0.40 or less.

公开(公告)号：US11085100B2

公开(公告)日：2021-08-10

申请号：US16453194

申请日：2019-06-26

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/12 ,  C21D8/02 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C22C38/14 ,  C22C38/00 ,  C22C38/08 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C22C18/00 ,  B32B15/01 ,  C22C38/18 ,  C22C38/06 ,  C22C38/34 ,  C21D6/00 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C23C2/40

Abstract: A high strength steel sheet having a high Young's modulus, the steel sheet having a chemical composition including, by mass %, C: 0.060% or more and 0.150% or less, Si: 0.50% or more and 2.20% or less, Mn: 1.00% or more and 3.00% or less, and one or both of Ti: 0.001% or more and 0.200% or less and Nb: 0.001% or more and 0.200% or less, in which the contents of C, N, S, Ti, and Nb satisfy the equation 500≤C*≤1300. The steel sheet has a microstructure including ferrite in an amount of 20% or more and martensite in an amount of 5% or more, in terms of area ratio, such that the average grain size of the ferrite is 20.0 μm or less and the inverse intensity ratio of γ-fiber for α-fiber is 1.00 or more in the ferrite and the martensite.

公开(公告)号：US11035019B2

公开(公告)日：2021-06-15

申请号：US15547876

申请日：2016-01-27

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C23C2/06 ,  C23C2/28 ,  C22C38/12 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/02 ,  C22C38/60 ,  C21D1/25 ,  B32B15/01 ,  C21D6/00

Abstract: A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 μm or less. An inverse intensity ratio of γ-fiber to α-fiber in the ferrite is 1.00 or more and an inverse intensity ratio of γ-fiber to α-fiber in the martensite and the tempered martensite is 1.00 or more.

公开(公告)号：US20210062282A1

公开(公告)日：2021-03-04

申请号：US16957739

申请日：2018-10-09

Applicant: JFE Steel Corporation

Inventor： Hiroshi Hasegawa ,  Hidekazu Minami ,  Tatsuya Nakagaito ,  Kana Sasaki ,  Shoji Tanaka

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/00 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/60 ,  C23C2/40

Abstract: A high-strength steel sheet has a specific composition and a microstructure. In the microstructure, the area fraction of elongated ferrite phase grains having an aspect ratio of 3 or more is 1% or less, the average crystal grain size of martensite included in a region extending 50 μm from a surface of the steel sheet is 20 μm or less, the content of oxide particles having a minor axis length of 0.8 μm or less in the region extending 50 μm from the surface of the steel sheet is 1.0×1010 particles/m2 or more, and the content of coarse oxide particles having a minor axis length of more than 1 μm in the region extending 50 μm from the surface of the steel sheet is 1.0×108 particles/m2 or less. The content of hydrogen trapped in the steel sheet is 0.05 ppm by mass or more.

公开(公告)号：US10934600B2

公开(公告)日：2021-03-02

申请号：US15547100

申请日：2016-01-27

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C23C2/06 ,  C22C38/14 ,  C22C38/60 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C23C2/02 ,  C21D6/00 ,  C21D8/04 ,  C23C2/28 ,  C21D8/00 ,  C21D1/25 ,  C22C38/04 ,  C22C38/22 ,  C22C38/24 ,  C22C38/28 ,  C22C38/38 ,  C23C2/40 ,  C23F17/00 ,  C22C38/18

Abstract: A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 μm or less. An inverse intensity ratio of γ-fiber to α-fiber in the ferrite is 1.00 or more and an inverse intensity ratio of γ-fiber to α-fiber in the martensite and the tempered martensite is 1.00 or more.