公开(公告)号：US20220056549A1

公开(公告)日：2022-02-24

申请号：US17415532

申请日：2019-10-25

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei YOSHIOKA ,  Yoshihiko ONO ,  Yuma HONDA ,  Nobuyuki NAKAMURA

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C23C2/06 ,  B22D11/18

Abstract: A steel sheet having a specified chemical composition and a tensile strength of 1,320 MPa or more, and methods for producing the steel sheet. The steel sheet has a specified microstructure including martensite and bainite, the total area fraction of the martensite and the bainite being 95% or more and 100% or less, the balance being one or more selected from ferrite and retained austenite. The forumulae [% Ti]+[% Nb]>0.007 and [% Ti]×[% Nb]2≤7.5×10−6 are satisfied in the chemical composition.

公开(公告)号：US20180100212A1

公开(公告)日：2018-04-12

申请号：US15558201

申请日：2016-03-23

Applicant: JFE STEEL CORPORATION

Inventor： Yoshihiko ONO ,  Yoshimasa FUNAKAWA ,  Ryosuke YAMAGUCHI ,  Nobuyuki NAKAMURA

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

CPC classification number: C21D9/46 ,  C21D8/0236 ,  C21D2211/002 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/60

Abstract: A cold-rolled steel sheet has: a predetermined chemical composition; and a microstructure in which tempered martensite and bainite are contained in a total area ratio of 95-100% with respect to a whole volume of the microstructure; a number of predetermined inclusion groups is at most 0.8/mm2, the inclusion groups being formed by one or more inclusion particles, the one or more inclusion particles having a major axis length of 0.3 μm or more and extending and/or distributed in a dot-sequence manner along a rolling direction; a number of carbides mainly composed of Fe having a predetermined size is at most 3,500/mm2; a number of carbides that are distributed in the tempered martensite and/or in the bainite and that have a diameter of 10 nm to 50 nm is at least 0.7×107/mm2; and prior γ grains have a mean grain size of 18 μm or less.

公开(公告)号：US20220090247A1

公开(公告)日：2022-03-24

申请号：US17415462

申请日：2019-10-25

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei YOSHIOKA ,  Yoshihiko ONO ,  Yuma HONDA ,  Nobuyuki NAKAMURA

IPC: C22C38/58 ,  C22C38/48 ,  C22C38/54 ,  C22C38/50 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/02 ,  C22C38/00 ,  C22C38/06 ,  C21D8/02

Abstract: A steel sheet having a specified chemical composition and a tensile strength of 1,320 MPa or more, and methods for producing the steel sheet. The steel sheet has a specified microstructure including martensite and bainite, the total area fraction of the martensite and the bainite being 92% or more and 100% or less, the balance being one or more selected from ferrite and retained austenite. The forumulae [%Ti]+[%Nb]>0.007 and [%Ti]×[%Nb]2≤7.5×10−6 are satisfied in the chemical composition.

公开(公告)号：US20160138141A1

公开(公告)日：2016-05-19

申请号：US14778339

申请日：2014-03-11

Applicant: JFE STEEL CORPORATION

Inventor： Katsumi NAKAJIMA ,  Yoshimasa FUNAKAWA ,  Nobuyuki NAKAMURA

IPC: C22C38/50 ,  C22C38/28 ,  C22C38/14 ,  C22C38/00 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/42 ,  C22C38/12

CPC classification number: C22C38/50 ,  B32B15/013 ,  C21D8/1222 ,  C21D8/1261 ,  C21D9/46 ,  C21D2211/002 ,  C21D2211/004 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/42 ,  C22C38/58 ,  C23C2/06 ,  C23C2/40 ,  H01F1/16

Abstract: A high strength hot rolled steel sheet with good formability, which has good magnetic properties, excellent punchability, and a tensile strength of 780 MPa or more. The high strength hot rolled steel sheet having a chemical composition containing C: 0.070% to 0.140%, Si: 0.10% to 1.00%, Mn: 1.00% to 1.80%, P: 0.050% or less, S: 0.0050% or less, N: 0.0080% or less, Al: 0.010% to 0.100%, Ti: 0.050% to 0.150%, and the remainder composed of Fe and incidental impurities, on a percent by mass basis, and 95% or more of bainite microstructure on a volume fraction basis, wherein carbides constituting 80% or more of total precipitation carbides are dispersed at grain boundaries of bainitic ferrite constituting the bainite microstructure and 80% or more of total precipitation carbides have particle grain sizes of 20 to 300 nm.

Abstract translation: 具有良好的成形性的高强度热轧钢板，具有良好的磁性能，优异的冲压性和780MPa以上的拉伸强度。 化学成分为C：0.070〜0.140％，Si：0.10〜1.00％，Mn：1.00〜1.80％，P：0.050％以下，S：0.0050％以下的高强度热轧钢板， N：0.0080％以下，Al：0.010〜0.100％，Ti：0.050〜0.150％，余量由Fe和杂质构成，以质量计为基准，95％以上的贝氏体组织 其中构成总沉淀碳化物的80％以上的碳化物分散在构成贝氏体组织的贝氏体铁素体的晶界处，并且总沉淀碳化物的80％以上的粒子粒径为20〜300nm。

公开(公告)号：US20190194775A1

公开(公告)日：2019-06-27

申请号：US16329672

申请日：2017-09-28

Applicant: JFE STEEL CORPORATION

Inventor： Yoshihiko ONO ,  Shimpei YOSHIOKA ,  Nobuyuki NAKAMURA ,  Hiroshi HASEGAWA

IPC: C21D9/46 ,  C23C2/06 ,  C23C2/40 ,  C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/42 ,  C22C38/46 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/44 ,  B32B15/01 ,  C21D8/02 ,  C21D6/00

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/021 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0405 ,  C21D8/041 ,  C21D8/0426 ,  C21D8/0436 ,  C21D8/0473 ,  C21D2211/002 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C23C2/06 ,  C23C2/40

Abstract: A steel sheet having a specified chemical composition and a method for producing the steel sheet. The steel sheet has a microstructure including martensite and bainite. The total area fraction of the martensite and the bainite to the entirety of the microstructure is more than 90% and 100% or less. The microstructure includes inclusion clusters A and B, the content of the clusters A in the microstructure being 2 clusters/mm2 or less, and the content of the clusters B in the microstructure being 5 clusters/mm2 or less. The microstructure includes carbide particles including Fe as a main constituent which have an aspect ratio of 2.0 or less and a major axis of 0.30 μm or more and 2 μm or less. The content of the carbide particles in the microstructure is 4000 particles/mm2 or less. The microstructure includes prior γ grains having an average size of 6 to 15 μm.