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：US20220010414A1

公开(公告)日：2022-01-13

申请号：US17289951

申请日：2019-09-25

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Shimpei YOSHIOKA ,  Shinjiro KANEKO

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

Abstract: A high-strength member having excellent delayed fracture resistance, a method for manufacturing the high-strength member, and a method for manufacturing a steel sheet for the high-strength member. The high-strength member has a bent ridge portion obtained by using a steel sheet having a tensile strength of 1470 MPa or more, an edge surface of the bent ridge portion has a residual stress of 800 MPa or less, and a longest crack among cracks that extend from the edge surface of the bent ridge portion in a bent ridge direction D1 has a length of 10 μm or less.

公开(公告)号：US20210054478A1

公开(公告)日：2021-02-25

申请号：US16964651

申请日：2019-01-24

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Yoshihiko ONO

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

Abstract: A high-ductility, high-strength steel sheet having excellent close-contact bendability and a method for producing the same. The steel sheet has a specified chemical composition and a microstructure comprising, by area percentage, 50% or more of a ferrite phase, 5% to 30% of a pearlite phase, and 15% or less in total of bainite, martensite, and retained austenite, in which the area percentage of ferrite grains each containing three or more cementite grains having an aspect ratio of 1.5 or less is 30% or less, and the number of inclusions having a particle size of 10 μm or more present in a portion extending from a surface to a ¼ thickness position is 2.0 particles/mm2 or less.

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：US20220098698A1

公开(公告)日：2022-03-31

申请号：US17426897

申请日：2019-12-19

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Yuma HONDA ,  Akinori NAKAMURA ,  Shinjiro KANEKO

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/00 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/42 ,  C21D8/02 ,  C23C2/06 ,  C23C2/40

Abstract: A high-strength steel sheet having a low yield ratio and a method for producing the same. The high-strength steel sheet has a specified chemical composition and a microstructure in which ferrite is present as a major phase, and martensite is present in an area fraction of 10% or greater and less than 50% relative to an entire area of the microstructure. The martensite has an average grain diameter of 3.0 μm or less, in an entirety of the martensite, a proportion of martensite having an aspect ratio of 3 or less is 60% or greater, and the martensite having an aspect ratio of 3 or less has a carbon concentration of 0.30% or greater and 0.90% or less in mass %.

公开(公告)号：US20220298594A1

公开(公告)日：2022-09-22

申请号：US17639086

申请日：2020-08-25

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Shimpei YOSHIOKA ,  Shinjiro KANEKO ,  Soshi YOSHIMOTO ,  Tomohiro HASHIMUKAI ,  Yoshihiko ONO

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

Abstract: A steel sheet having a steel microstructure including, by area %, martensite in a range of 20% or more and 100% or less, ferrite in a range of 0% or more and 80% or less, and the balance being 5% or less. A residual stress generated at the transverse center of the steel sheet when the steel sheet is subjected to a V-bending process is 800 MPa or less. A residual stress generated at the transverse end of the steel sheet when the steel sheet is subjected to a V-bending process is 90% or more and 110% or less of the residual stress generated at the transverse center of the steel sheet. The maximum amount of warpage of the steel sheet sheared to a length of 1 m in the longitudinal direction is 15 mm or less.

公开(公告)号：US20220002827A1

公开(公告)日：2022-01-06

申请号：US17290155

申请日：2019-09-25

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Shimpei YOSHIOKA ,  Shinjiro KANEKO

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/60 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/20

Abstract: A high-strength steel sheet having high delayed fracture resistance and a method for manufacturing the high-strength steel sheet. The high-strength steel sheet has a specified chemical composition. Relative to the whole microstructure of the steel sheet, the total area fraction of at least one of (i) bainite containing carbide grains having an average grain size of 50 nm or less and (ii) martensite containing carbide grains having an average grain size of 50 nm or less is 90% or more. The average number of inclusions having an average grain size of 5 μm or more that are present in a section of the steel sheet perpendicular to a rolling direction is 5.0/mm2 or less.