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：US20240158884A1

公开(公告)日：2024-05-16

申请号：US18550459

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: 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 ,  C22C38/24 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06 ,  C23C2/28 ,  C25D3/22 ,  C25D5/50

CPC classification number: C21D9/46 ,  B32B15/011 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0257 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/004 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/24 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06 ,  C23C2/285 ,  C25D3/22 ,  C25D5/50

Abstract: A clad steel plate having tensile strength (TS) of 780 MPa or more, excellent ductility, 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：US20210108282A1

公开(公告)日：2021-04-15

申请号：US17043514

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

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

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  B32B15/01 ,  C23C2/02 ,  C23C2/28 ,  C23C2/40 ,  C23C2/06

Abstract: A high-strength steel includes a steel structure with: in area fraction, 60.0% to less than 90.0% of ferrite, 0% to less than 5.0% of unrecrystallized ferrite, 2.0% to 25.0% of martensite, 0% to 5.0% of carbide, and 0% to 3.0% of bainite; in volume fraction, more than 7.0% of retained austenite; in a cross-sectional view of 100 μm×100 μm, a value obtained by dividing number of retained austenite that are not adjacent to retained austenite whose crystal orientations are different by a total number of retained austenite being less than 0.80, an average crystal grain size of the ferrite being 6.0 μm or less, an average crystal grain size of the retained austenite being 3.0 μm or less, and a value obtained by dividing, by mass %, an average content of Mn in the retained austenite by an average content of Mn in steel being 1.50 or more.

公开(公告)号：US20180195143A1

公开(公告)日：2018-07-12

申请号：US15742116

申请日：2016-08-26

Applicant: JFE STEEL CORPORATION

Inventor： Fusae SHIIMORI ,  Yoshiyasu KAWASAKI ,  Shinjiro KANEKO ,  Takeshi YOKOTA ,  Kazuhiro SETO ,  Takaaki TANAKA ,  Yuki TOJI

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

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D1/32 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C22C18/04 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/38 ,  C23C2/06

Abstract: This disclosure provides a high-strength thin steel sheet excellent in both tensile strength and elongation with small elongation anisotropy. The high-strength thin steel sheet has a specific chemical composition and a microstructure where a total area ratio of ferrite, tempered bainitic ferrite and bainitic ferrite is 40% or more and 70% or less, an area ratio of martensite is 5% or more and 30% or less, an area ratio of retained austenite is 10% or more and 35% or less, an average equivalent circular diameter of martensite and retained austenite (secondary phase) grains is 2.0 μm or less, an area ratio of secondary phase grains having an equivalent circular diameter of 2.0 μm or more is 10% or less, and an average minor axis length of secondary phase grains is 0.40 μm or less.

公开(公告)号：US20170211163A1

公开(公告)日：2017-07-27

申请号：US15326811

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Hiroshi MATSUDA ,  Kazunori TAHARA ,  Takeshi YOKOTA ,  Kaneharu OKUDA ,  Kazuhiro SETO

IPC: C21D9/46 ,  C21D6/00 ,  C22C38/60 ,  C22C38/38 ,  C22C38/16 ,  C23F17/00 ,  C22C38/12 ,  C22C38/06 ,  C22C38/00 ,  C22C38/04 ,  C22C38/02 ,  C23C2/06 ,  C21D8/02 ,  C22C38/14

CPC classification number: C21D9/46 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D2211/001 ,  C21D2211/005 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06 ,  C23F17/00

Abstract: Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, balance between high strength and ductility, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, and 5-20% of martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, and the retained austenite has a mean free path of 1.2 μm or less.

公开(公告)号：US20240124964A1

公开(公告)日：2024-04-18

申请号：US18546428

申请日：2022-03-18

Applicant: JFE STEEL CORPORATION

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

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

CPC classification number: C23C2/06 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/06 ,  C23C2/40 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: Provided is a galvanized steel sheet having a TS of 980 MPa or more, high YS, excellent ductility, strain hardenability, and hole expansion formability. A base steel sheet has a defined chemical composition and a steel microstructure as follows: area ratio of ferrite: 65.0% or less (including 0%), area ratio of bainitic ferrite: 5.0% or more and 40.0% or less, area ratio of tempered martensite: 0.5% or more and 80.0% or less, area ratio of retained austenite: 3.0% or more, area ratio of fresh martensite: 20.0% or less (including 0%), SBF+STM+2×SMA: 65.0% or more, SMA1/SMA: 0.80 or less, and SMA2/SMA: 0.20 or more.

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：US20220018747A1

公开(公告)日：2022-01-20

申请号：US17311236

申请日：2019-12-16

Applicant: JFE STEEL CORPORATION

Inventor： Kentaro SATO ,  Takayuki FUTATSUKA ,  Tomohiro SAKAIDANI ,  Shinsuke KOMINE ,  Yoshiyasu KAWASAKI

IPC: G01N3/20 ,  G01N3/24 ,  G01N3/307

Abstract: A collision performance evaluation test with few variations in test results with high accuracy in which a complicated phenomenon that actually occurs can be reproduced in a simple manner by considering the history of deformation in both the press forming and a collision. A collision performance evaluation test method for a metal sheet material for an automobile body is characterized in that a press working apparatus first forms a flat test specimen made of a metal sheet material to be tested into a V shape by primary bending, a bending test apparatus then deforms, by secondary bending, the test specimen formed by the primary bending in a direction intersecting with the primary bending direction, and a bending load and a bending stroke for the test specimen during the secondary bending deformation are recorded and evaluated.

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：US20170175219A1

公开(公告)日：2017-06-22

申请号：US15327126

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Hiroshi MATSUDA ,  Yoshie OBATA ,  Shinjiro KANEKO ,  Takeshi YOKOTA ,  Kazuhiro SETO

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/60 ,  C22C38/32 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/14 ,  C22C38/12 ,  C21D8/02 ,  C22C38/28

Abstract: Disclosed is a high-strength steel sheet having a predetermined chemical composition, satisfying the condition that Mn content divided by B content equals 2100 or less, and a steel microstructure that contains, by area, 25-80% of ferrite and bainitic ferrite in total, 3-20% of martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, and an aggregate of retained austenite formed by seven or more identically-oriented retained austenite grains accounts for 60% or more by area of the entire retained austenite.