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
⁢


(
%
)


=


[

%
⁢

Ti

]

-


(

47.9
/
14.

)

×

[

%
⁢

N

]


-


(

47.9
/
32.1

)

×

[

%
⁢

S

]







(
1
)

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：US20250115982A1

公开(公告)日：2025-04-10

申请号：US18729167

申请日：2023-01-23

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiaki ZAIZEN ,  Takeshi NISHIYAMA ,  Nobuko NAKAGAWA ,  Tomoyuki OKUBO

IPC: C22C38/02 ,  C21D6/00 ,  C21D8/12 ,  C22C38/00 ,  C22C38/04 ,  C22C38/06 ,  C22C38/10

Abstract: Provided is a non-oriented electrical steel sheet with low high-frequency iron loss without addition of a large amount of alloying elements such as Cr, which causes a decrease in magnetic flux density, and without reduction of the sheet thickness, which causes a decrease in productivity. A non-oriented electrical steel sheet comprises a certain chemical composition containing 0.0005 mass % to 0.0050 mass % of Co, wherein an amount of N existing as AlN in a range from a surface of the non-oriented electrical steel sheet to a depth of 1/20 of a sheet thickness is 0.003 mass % or less, the surface has an oxide layer containing Fe and one or both of Al and Si, and an interface between the oxide layer and a steel substrate has an oxide film consisting of one or both of Al oxide and Si oxide.

公开(公告)号：US20250101542A1

公开(公告)日：2025-03-27

申请号：US18728222

申请日：2023-01-20

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiaki ZAIZEN ,  Takeshi NISHIYAMA ,  Nobuko NAKAGAWA ,  Tomoyuki OKUBO ,  Tomohiro AOYAMA

IPC: C21D9/46 ,  C21D6/00 ,  C21D8/12 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/26 ,  C22C38/30 ,  C22C38/34 ,  C22C38/42 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  H01F1/147

Abstract: Provided is a non-oriented electrical steel sheet with low high-frequency iron loss without addition of a large amount of alloying elements such as Cr, which causes a decrease in magnetic flux density, and without reduction of the sheet thickness, which causes a decrease in productivity. A non-oriented electrical steel sheet comprises a certain chemical composition containing 0.0005 mass % to 0.0050 mass % of Co, wherein at at least one surface of the non-oriented electrical steel sheet, an amount of N existing as AlN in a range from the surface to a depth of 1/20 of a thickness of the non-oriented electrical steel sheet is 0.003 mass % or less, and the surface has an oxide layer containing one or both of Al and Si and having a thickness of 80 nm to 200 nm.