公开(公告)号：US20240287637A1

公开(公告)日：2024-08-29

申请号：US18572182

申请日：2022-05-31

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu MINAMI ,  Yusuke WADA ,  Yuki TOJI ,  Takeshi NISHIYAMA ,  Michitoshi SAEKI

IPC: C21D9/46 ,  C21D1/18 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high strength steel sheet with a chemical composition containing C, Si, Mn, P, S, Al, N, Nb, Ti, and B, where [% Si]/[% Mn] is 0.10 or more and 0.60 or less, and free Ti content determined from Formula (1), below, is 0.001 mass % or more, with the balance being Fe and inevitable impurity. In a steel sheet surface layer, a total amount of Nb solute and 100 nm or smaller precipitate is 0.002 mass % or more.








free
⁢

Ti
⁢

content
⁢


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%
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=


[

%
⁢

Ti

]

-


(

47.9
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14.

)

×

[

%
⁢

N

]


-


(

47.9
/
32.1

)

×

[

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(
1
)

公开(公告)号：US20240263287A1

公开(公告)日：2024-08-08

申请号：US18565655

申请日：2022-03-16

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu MINAMI ,  Yusuke WADA ,  Yuki TOJI ,  Yoichi MAKIMIZU

IPC: C22C38/04 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/02 ,  C22C38/06 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

CPC classification number: C22C38/04 ,  C21D6/005 ,  C21D8/0226 ,  C21D8/0263 ,  C21D8/0268 ,  C21D8/0273 ,  C21D9/46 ,  C22C38/02 ,  C22C38/06 ,  C23C2/024 ,  C23C2/06 ,  C23C2/29 ,  C23C2/40

Abstract: Provided is a hot-dip galvanized steel sheet that has a high YR, as well as high ductility, stretch flangeability, and bendability, improved shear workability, and a TS of 1,180 MPa or more. The base steel sheet of the hot-dip galvanized steel sheet has a defined chemical composition and steel microstructure. In particular, a number ratio of retained austenite (y) having an aspect ratio of 2.0 or less is more than 50%, a number of bins of hardness frequency: 0.25 or more is 1, the area ratio of quenched martensite in a surface layer is 80% or less, a surface layer softening thickness is 10 μm or more and 100 μm or less, and the amount of low temperature range diffusible hydrogen is 0.015 mass ppm or less.

公开(公告)号：US20230243006A1

公开(公告)日：2023-08-03

申请号：US18004881

申请日：2021-05-26

Applicant: JFE STEEL CORPORATION

Inventor： Junya TOBATA ,  Kazuki ENDOH ,  Yuki TOJI

IPC: C21D3/06 ,  C21D7/13 ,  C21D10/00 ,  C21D7/02 ,  C21D9/46 ,  C21D9/08 ,  C21D9/52

CPC classification number: C21D3/06 ,  C21D7/13 ,  C21D10/00 ,  C21D7/02 ,  C21D9/46 ,  C21D9/08 ,  C21D9/52

Abstract: Provided is a dehydrogenation method capable of efficiently reducing hydrogen content in steel for thick or complexly-shaped steel materials and steel products in general. In a dehydrogenation method for a steel material, in a series of steel material production process including: a process of supplying a steel raw material; a process of subjecting the steel raw material to hot working; a process of inspecting a steel material obtained from the steel raw material; and a process of shipping the steel material, at least one of the steel raw material and the steel material at any stage from the supply process to the shipment process is subjected to, at least once, a sound wave irradiation treatment so that a sound pressure level at a surface of the at least one of the steel raw material and the steel material will be 30 dB or more.

公开(公告)号：US20230235421A1

公开(公告)日：2023-07-27

申请号：US18247073

申请日：2021-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yuji TANAKA ,  Masaki TADA ,  Yuki TOJI ,  Shinsuke KOMINE ,  Yoshie OBATA ,  Yusuke KIMATA

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C23C2/20

CPC classification number: C21D8/0268 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C21D8/0226 ,  C21D8/0263 ,  C23C2/20 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength cold-rolled steel sheet comprises: a chemical composition that contains C, Si, Mn, P, S, N, Al, Ti, Nb, and B with a balance consisting of Fe and inevitable impurities, and satisfies [mol % N]/[mol % Ti]

公开(公告)号：US20220186334A1

公开(公告)日：2022-06-16

申请号：US17433875

申请日：2019-12-10

Applicant: JFE STEEL CORPORATION

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

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

Abstract: An object is to provide a high strength steel sheet having a TS (tensile strength) of 980 MPa or more and excellent formability and a method for manufacturing the steel sheet.
A high strength steel sheet which is excellent in terms of formability, which is manufactured under optimized manufacturing conditions, and which has a predetermined chemical composition and a steel microstructure including, in terms of area fraction, 35% or more and 80% or less of ferrite, 5% or more and 35% or less of as-quenched martensite, 0.1% or more and less than 3.0% of tempered martensite, and 8% or more of retained austenite, in which the average grain size of the ferrite is 6 μm or less, in which the average grain size of the retained austenite is 3 μm or less, in which a value calculated by dividing the average Mn content in the retained austenite by the average Mn content in the ferrite is 1.5 or more, in which a value calculated by dividing the sum of the area fraction of as-quenched martensite having a circle-equivalent grain size of 3 μm or more and the area fraction of retained austenite having a circle-equivalent grain size of 3 μm or more by the sum of the area fraction of all the as-quenched martensite and the area fraction of all the retained austenite is less than 0.4, and in which a value calculated by dividing the area fraction of retained austenite grains adjacent to three or more ferrite grains having different crystal orientations by the area fraction of all the retained austenite is less than 0.6.