公开(公告)号：US20170204490A1

公开(公告)日：2017-07-20

申请号：US15326540

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 ,  C21D6/00 ,  C22C38/60 ,  C22C38/38 ,  C23F17/00 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/00 ,  C23C2/06 ,  C21D8/02 ,  C22C38/16

CPC classification number: C21D9/46 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0273 ,  C21D8/0278 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C18/04 ,  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 ,  C23C2/02 ,  C23C2/06 ,  C23F17/00

Abstract: Disclosed is a high-strength steel sheet having a predetermined chemical composition and a steel microstructure that contains, by area, 25-80% of ferrite and bainitic ferrite in total, and 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 %, an area ratio of retained austenite having a mean C content in mass % at least 2.1 times the C content in the steel sheet in mass % is 60% or more of an area ratio of the entire retained austenite.

公开(公告)号：US20230374622A1

公开(公告)日：2023-11-23

申请号：US18247071

申请日：2021-08-05

Applicant: JFE STEEL CORPORATION

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

IPC: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/34 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D1/18 ,  C21D6/00

CPC classification number: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/34 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/002 ,  C22C38/001 ,  C22C38/005 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D1/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D2211/005 ,  C21D2211/008 ,  C21D2211/002 ,  C21D2211/001

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：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：US20220177992A1

公开(公告)日：2022-06-09

申请号：US17437357

申请日：2020-02-13

Applicant: JFE STEEL CORPORATION

Inventor： Yoshie OBATA ,  Katsutoshi TAKASHIMA ,  Minoru TANAKA ,  Yoshiko NAKAHARA

IPC: C21D9/46 ,  B21D22/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/14 ,  C22C38/12 ,  C22C38/60 ,  C23C2/06 ,  C23C2/12 ,  C23C2/40 ,  C23G1/00 ,  C21D8/02 ,  B21C47/02

Abstract: A hot press member includes excellent indentation peel strength which has a tensile strength of 1780 MPa or more. A plating layer has at a surface thereof a 10-point average roughness Rzjis of 25 μm or less, and a steel sheet contains, in mass %, not less than 0.25% but less than 0.50% of C, 1.5% or less of Si, 1.1-2.4% of Mn, 0.05% or less of P, 0.005% or less of S, 0.01-0.50% of Al, 0.010% or less of N, 0.001-0.020% of Sb, 0.005-0.15% of Nb, and 0.005-0.15% of Ti, the balance being Fe and incidental impurities. The average crystal grain size of prior austenite is 7 μm or less and the volume proportion of martensite is 90% or more, within 50 μm in the thickness direction from the surface of the steel sheet excluding the plating layer.

公开(公告)号：US20190203315A1

公开(公告)日：2019-07-04

申请号：US16325299

申请日：2017-08-29

Applicant: JFE STEEL CORPORATION

Inventor： Yoshie OBATA ,  Katsutoshi TAKASHIMA ,  Takashi KOBAYASHI ,  Hiroshi MATSUDA

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/60 ,  C23F17/00 ,  B32B15/01

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D1/18 ,  C21D1/25 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0273 ,  C21D8/0278 ,  C21D8/0405 ,  C21D8/0426 ,  C21D8/0436 ,  C21D8/0463 ,  C21D8/0473 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C18/04 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23F17/00 ,  C25D3/22

Abstract: A high-strength cold rolled steel sheet having a specified chemical composition and a method for producing the same. The steel sheet having a microstructure including, in terms of volume fraction, 35% or less of ferrite, 1% or more and 10% or less of retained austenite, 2% or more and 12% or less of as-quenched martensite, and a total of 25% to 70% of bainite and tempered martensite. The microstructure has an average crystal grain diameter of the ferrite: 5.0 μm or less, an average crystal grain diameter of the retained austenite: 2.0 μm or less, an average crystal grain diameter of the as-quenched martensite: 3.0 μtm or less, an average crystal grain diameter of the bainite and the tempered martensite phase: 4.0 μm or less, and an average intergrain distance of the as-quenched martensite of 1.0 μm 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.

公开(公告)号：US20230295762A1

公开(公告)日：2023-09-21

申请号：US18021287

申请日：2021-06-22

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Yoshie OBATA ,  Hiroshi MATSUDA

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C22C38/60 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/005 ,  C21D6/008 ,  C22C38/60 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/002 ,  C22C38/001 ,  C21D2211/008 ,  C21D2211/003 ,  C21D2211/001

Abstract: A hot-pressed member having a specified chemical composition in which Ti/Sb 2.0≤Ti/Sb≤20.0 is satisfied and a method for producing the hot-pressed member. The hot-pressed member has a microstructure in which a volume fraction of martensite is 95% or more, an average grain size of prior austenite is 7 μm or less, the number of cementite grains with a grain size of 0.10 μm or more is 2 grains/μm2 or more, and the number of Ti-based carbide grains with a grain size of 0.10 μm or less is 0.20 grains/μm2 or more, and a tensile strength of 2100 MPa or higher.

公开(公告)号：US20220186339A1

公开(公告)日：2022-06-16

申请号：US17432218

申请日：2020-01-17

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Minoru TANAKA ,  Yoshie OBATA ,  Michitaka SAKURAI

IPC: C21D9/48 ,  C21D8/04 ,  C21D6/00 ,  C22C38/60 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/58 ,  C22C38/00 ,  C22C38/02 ,  B32B15/01

Abstract: Provided is a hot-pressed member that combines both high strength of 1850 MPa or more in TS and excellent delayed fracture resistance. A hot-pressed member comprises: a predetermined chemical composition; a microstructure in which a prior austenite average grain size is 8 μm or less, a volume fraction of martensite is 95% or more, and a volume fraction of granular carbide of 0.1 μm or more in grain size is 0.10% to 4.0%; a Ni diffusion region of 2.0 μm or more in a depth direction in a surface layer; and a tensile strength of 1850 MPa or more.

公开(公告)号：US20190062863A1

公开(公告)日：2019-02-28

申请号：US16075747

申请日：2017-01-12

Applicant: JFE STEEL CORPORATION

Inventor： Yuji TANAKA ,  Sarka MIKMEKOVA ,  Takako YAMASHITA ,  Yoshie OBATA

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C23C2/02 ,  C23C2/40 ,  C23C2/06 ,  B32B15/01 ,  C22C38/04 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00

Abstract: A high-strength cold rolled steel sheet has both high strength, i.e. a tensile strength of 900 MPa or more, and high workability, i.e. a total elongation of 20% or more, and also has a low yield ratio of less than 60%. The high-strength cold rolled steel sheet comprises: a predetermined chemical composition; and a steel structure having, in area ratio, ferrite: 30% to 75%, martensite: 15% to 40%, and retained austenite: 10% to 30%. In the case where a distribution of crystal grain circularity of the retained austenite is represented by a histogram with a class range of more than 0.1×(n−1) and 0.1×n or less and a class value of 0.1×n (n is an integer from 1 to 10), a mode of the crystal grain circularity of the retained austenite is 0.7 or more.

公开(公告)号：US20190048436A1

公开(公告)日：2019-02-14

申请号：US16075750

申请日：2017-01-12

Applicant: JFE STEEL CORPORATION

Inventor： Yuji TANAKA ,  Sarka MIKMEKOVA ,  Takako YAMASHITA ,  Yoshie OBATA

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

Abstract: A high-strength cold rolled steel sheet has both high strength, i.e. a tensile strength of 900 MPa or more, and high workability, i.e. a total elongation of 20% or more, and also has a high yield ratio of 60% or more. The high-strength cold rolled steel sheet comprises: a predetermined chemical composition; and a steel structure having, in area ratio, ferrite: 30% to 75%, martensite: 15% to 40%, and retained austenite: 10% to 30%. In the case where a distribution of crystal grain circularity of the retained austenite is represented by a histogram with a class range of more than 0.1×(n−1) and 0.1×n or less and a class value of 0.1×n (n is an integer from 1 to 10), a mode of the crystal grain circularity of the retained austenite is 0.6 or less.