公开(公告)号：US11085100B2

公开(公告)日：2021-08-10

申请号：US16453194

申请日：2019-06-26

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/12 ,  C21D8/02 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C22C38/14 ,  C22C38/00 ,  C22C38/08 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C22C18/00 ,  B32B15/01 ,  C22C38/18 ,  C22C38/06 ,  C22C38/34 ,  C21D6/00 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C23C2/40

Abstract: A high strength steel sheet having a high Young's modulus, the steel sheet having a chemical composition including, by mass %, C: 0.060% or more and 0.150% or less, Si: 0.50% or more and 2.20% or less, Mn: 1.00% or more and 3.00% or less, and one or both of Ti: 0.001% or more and 0.200% or less and Nb: 0.001% or more and 0.200% or less, in which the contents of C, N, S, Ti, and Nb satisfy the equation 500≤C*≤1300. The steel sheet has a microstructure including ferrite in an amount of 20% or more and martensite in an amount of 5% or more, in terms of area ratio, such that the average grain size of the ferrite is 20.0 μm or less and the inverse intensity ratio of γ-fiber for α-fiber is 1.00 or more in the ferrite and the martensite.

公开(公告)号：US11035019B2

公开(公告)日：2021-06-15

申请号：US15547876

申请日：2016-01-27

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C23C2/06 ,  C23C2/28 ,  C22C38/12 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/02 ,  C22C38/60 ,  C21D1/25 ,  B32B15/01 ,  C21D6/00

Abstract: A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 μm or less. An inverse intensity ratio of γ-fiber to α-fiber in the ferrite is 1.00 or more and an inverse intensity ratio of γ-fiber to α-fiber in the martensite and the tempered martensite is 1.00 or more.

公开(公告)号：US10934600B2

公开(公告)日：2021-03-02

申请号：US15547100

申请日：2016-01-27

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C23C2/06 ,  C22C38/14 ,  C22C38/60 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C23C2/02 ,  C21D6/00 ,  C21D8/04 ,  C23C2/28 ,  C21D8/00 ,  C21D1/25 ,  C22C38/04 ,  C22C38/22 ,  C22C38/24 ,  C22C38/28 ,  C22C38/38 ,  C23C2/40 ,  C23F17/00 ,  C22C38/18

Abstract: A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 μm or less. An inverse intensity ratio of γ-fiber to α-fiber in the ferrite is 1.00 or more and an inverse intensity ratio of γ-fiber to α-fiber in the martensite and the tempered martensite is 1.00 or more.

公开(公告)号：US10662496B2

公开(公告)日：2020-05-26

申请号：US15326811

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Kazunori Tahara ,  Takeshi Yokota ,  Kaneharu Okuda ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/04 ,  C22C38/60 ,  C22C38/00 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C23C2/06 ,  C23F17/00

Abstract: Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, balance between high strength and ductility, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, and 5-20% 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 the retained austenite has a mean free path of 1.2 μm or less.

公开(公告)号：US10550446B2

公开(公告)日：2020-02-04

申请号：US15520531

申请日：2015-10-29

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Takeshi Yokota ,  Takako Yamashita ,  Kazuhiro Seto

IPC: C22C38/04 ,  C22C38/58 ,  C21D8/02 ,  C22C38/38 ,  C21D6/00 ,  C21D9/46 ,  C23C2/02 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C22C38/00 ,  C22C38/14 ,  C22C38/60 ,  B32B15/01 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C23C2/40 ,  C23G1/00 ,  C25D3/22

Abstract: A high-strength steel sheet with excellent formability and high yield ratio that has TS of 980 MPa or more and YR of 68% or more is obtained by providing a predetermined chemical composition and a steel microstructure that contains, in area ratio, 15 to 55% of polygonal ferrite, 8% or more of non-recrystallized ferrite, and 15 to 30% of martensite, and that contains, in volume fraction, 12% or more of retained austenite, in which the polygonal ferrite has a mean grain size of 4 μm or less, the martensite has a mean grain size of 2 μm or less, the retained austenite has a mean grain size of 2 μm or less, and a value obtained by dividing an Mn content in the retained austenite (in mass %) by an Mn content in the polygonal ferrite (in mass %) equals 2.0 or more.