公开(公告)号：US12060623B2

公开(公告)日：2024-08-13

申请号：US17040891

申请日：2018-03-30

Applicant: NIPPON STEEL CORPORATION

Inventor： Shohei Yabu ,  Koutarou Hayashi ,  Akihiro Uenishi

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/20 ,  C22C38/32

CPC classification number: C21D9/46 ,  C21D8/0205 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/20 ,  C22C38/32 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A steel sheet including, in mass %, C: 0.05% or more and 0.30% or less, Si: 0.05% or more and 6.00% or less, Mn: 1.50% or more and 10.00% or less, and the balance: Fe and impurities, a steel sheet structure is composed of, in area ratio, 15% or more and 80% or less of ferrite and 20% or more and 85% or less in total of a hard structure composed of any one of bainite, martensite, or retained austenite, or any combination thereof, and to a steel sheet thickness t, an area ratio of a maximum coupled ferrite region in a region from a t/2 position at the steel sheet thickness center to a position at a depth of 3t/8 from a surface is 80% or more in area ratio to a total ferrite area, and a two-dimensional isoperimetric constant of the maximum coupled ferrite region is 0.35 or less.

公开(公告)号：US12060631B2

公开(公告)日：2024-08-13

申请号：US17293010

申请日：2019-11-20

Applicant: NIPPON STEEL CORPORATION

Inventor： Genki Abukawa ,  Shohei Yabu

IPC: C22C38/58 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/52 ,  C22C38/54

CPC classification number: C22C38/58 ,  C21D8/0205 ,  C21D8/0226 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/52 ,  C22C38/54

Abstract: A hot-rolled steel sheet includes, as chemical composition, C, Si, Mn, and sol.Al. In the hot-rolled steel sheet, a sum of an average of pole densities in a crystal orientation group consisting of {211} to {111} and a pole density in a crystal orientation of {110} is 0.5 to 6.0 in the surface region, and the tensile strength is 780 to 1370 MPa.

公开(公告)号：US11939650B2

公开(公告)日：2024-03-26

申请号：US17295298

申请日：2019-11-20

Applicant: NIPPON STEEL CORPORATION

Inventor： Shohei Yabu ,  Kunio Hayashi ,  Yuji Yamaguchi ,  Marina Mori ,  Naoki Inoue ,  Genki Abukawa

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

CPC classification number: C22C38/06 ,  C21D8/0205 ,  C21D8/0226 ,  C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C21D2201/05

Abstract: A hot-rolled steel sheet includes, as chemical composition, C, Si, Mn, and sol.Al. In the hot-rolled steel sheet, an average of pole densities in crystal orientation group consisting of {110} to {110} in surface region is 0.5 to 3.0, a standard deviation of the pole densities in the crystal orientation group is 0.2 to 2.0, and the tensile strength is 780 to 1370 MPa.

公开(公告)号：US12215402B2

公开(公告)日：2025-02-04

申请号：US17784901

申请日：2020-12-15

Applicant: NIPPON STEEL CORPORATION

Inventor： Genki Abukawa ,  Masafumi Azuma ,  Eisaku Sakurada ,  Shohei Yabu

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, a microstructure includes 80% or more of tempered martensite by a volume percentage and a remainder consisting of one or more of ferrite, pearlite, bainite, fresh martensite, and residual austenite, the tempered martensite includes 5×109 pieces/mm3 or more of precipitates containing Ti and having an equivalent circle diameter of 5 nm or less per unit volume, in a surface layer region that is a range from a surface to a 1/10 position of a sheet thickness, a sum of an average pole density of a crystal orientation group consisting of {211} to {111} and a pole density in a crystal orientation of {110} is 6.0 or less, and a tensile strength is 980 MPa or more.

公开(公告)号：US12203148B2

公开(公告)日：2025-01-21

申请号：US17767229

申请日：2020-12-08

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke Ito ,  Shohei Yabu ,  Takeshi Toyoda

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/28 ,  C22C38/32

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in a microstructure at a ¼ position of a sheet thickness in a sheet thickness direction from a surface, a primary phase is bainite, a secondary phase is martensite or a martensite-austenite mixed phase, an average grain size of the secondary phase is 1.5 μm or less, an average grain size of particles having grain diameters that are largest 10% or less out of all particles in the secondary phase is 2.5 μm or less, a pole density in a (110) orientation is 3.0 or less, and, in a microstructure from the surface to a 1/16 position of the sheet thickness in the sheet thickness direction from the surface, a pole density in a (110) orientation is 3.0 or less.

公开(公告)号：US12180557B2

公开(公告)日：2024-12-31

申请号：US17434986

申请日：2020-03-31

Applicant: NIPPON STEEL CORPORATION

Inventor： Shohei Yabu ,  Koutarou Hayashi ,  Akihiro Uenishi

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

Abstract: The present invention relates to a cold rolled steel sheet containing C: 0.15% or more and 0.40% or less, Si: 0.50% or more and 4.00% or less, Mn: 1.00% or more and 4.00% or less, and sol. Al: 0.001% or more and 2.000% or less, having a metallic structure consisting of 35 to 65 area % of ferrite phases, 35 to 65 area % of hard second phases, and 0 to 5 area % of remaining phases, wherein 60% or more of the ferrite phases are recrystallized ferrite phases, an average crystal grain size defined by 15° grain boundaries is 5.0 μm or less, a maximum connecting rate of the hard second phases is 10% or more, and a two-dimensional isoperimetric constant of the hard second phases is 0.20 or less.