公开(公告)号：US20230416886A1

公开(公告)日：2023-12-28

申请号：US18039682

申请日：2021-11-16

Applicant: NIPPON STEEL CORPORATION

Inventor： Mutsumi SAKAKIBARA ,  Tatsuo YOKOI ,  Hiroshi SHUTO

IPC: C22C38/38 ,  C22C38/04 ,  C21D1/18 ,  C21D1/84 ,  C21D8/02 ,  C21D6/00 ,  C22C38/00 ,  C22C38/12 ,  C21D9/46 ,  C22C38/28 ,  C22C38/08 ,  C22C38/34 ,  C22C38/10 ,  C22C38/06 ,  C22C38/02 ,  C22C38/14 ,  C22C38/16

CPC classification number: C22C38/38 ,  C22C38/04 ,  C21D1/18 ,  C21D1/84 ,  C21D8/021 ,  C21D6/008 ,  C22C38/001 ,  C22C38/12 ,  C21D9/46 ,  C21D8/0205 ,  C22C38/28 ,  C22C38/08 ,  C21D6/001 ,  C21D6/005 ,  C21D6/007 ,  C22C38/34 ,  C22C38/10 ,  C22C38/06 ,  C21D8/0226 ,  C21D6/002 ,  C22C38/02 ,  C22C38/14 ,  C22C38/005 ,  C22C38/16 ,  C22C38/008 ,  C22C38/002 ,  C21D2211/005 ,  C21D2211/009 ,  C21D2211/008 ,  C21D2211/001 ,  C21D2211/002

Abstract: This hot-rolled steel sheet has a desired chemical composition, a microstructure contains, in area %, ferrite: 10 to 30%, bainite: 40 to 85%, retained austenite: 5 to 30%, fresh martensite: 5% or less, and pearlite: 5% or less, the ferrite has an average particle size of 5.00 μm or less, a difference between an average nanoindentation hardness of the ferrite and an average nanoindentation hardness of the bainite is 1,000 MPa or less, and the tensile strength is 980 MPa or more.

公开(公告)号：US20220090228A1

公开(公告)日：2022-03-24

申请号：US17425251

申请日：2020-03-05

Applicant: NIPPON STEEL CORPORATION

Inventor： Genki ABUKAWA ,  Hiroshi SHUTO ,  Kenta MORISAWA ,  Shohei YABU

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

Abstract: A hot-rolled steel sheet according to the present invention includes, as a chemical composition, by mass %: C: 0.030% to 0.250%; Si: 0.05% to 2.50%; Mn: 1.00% to 4.00%; Sol. Al: 0.001% to 2.000%; P: 0.100% or less; S: 0.0200% or less; N: 0.01000% or less; Ti: 0% to 0.20%; Nb: 0% to 0.20; B: 0% to 0.010%; V: 0% to 1.0%; Cr: 0% to 1.0%; Mo: 0% to 1.0%; Cu: 0% to 1.0%; Co: 0% to 1.0%; W: 0% to 1.0%; Ni: 0% to 1.0%; Ca: 0% to 0.01%; Mg: 0% to 0.01%; REM: 0% to 0.01%; Zr: 0% to 0.01%; and a remainder consisting of Fe and impurities, in which an area ratio of a scale damage portion, which is a portion lower than an average height of a surface of the steel sheet by 10 μm or more, is 20% or less, and a tensile strength of the hot-rolled steel sheet is 780 MPa or more.

公开(公告)号：US20220010396A1

公开(公告)日：2022-01-13

申请号：US17283476

申请日：2019-10-21

Applicant: NIPPON STEEL CORPORATION

Inventor： Tatsuo YOKOI ,  Teruki HAYASHIDA ,  Mutsumi SAKAKIBARA ,  Jun ANDO ,  Shinsuke KAI ,  Hiroshi SHUTO

IPC: C21D9/46 ,  B21B1/02 ,  C22C38/58 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23G1/08

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, and in a case where the thickness is denoted by t, the metallographic structure at a t/4 position from the surface contains one or both of tempered martensite and lower bainite at a volume percentage of 90% or more, the tensile strength is 980 MPa or more, and the average Ni concentration on the surface is 7.0% or more.

公开(公告)号：US20210395852A1

公开(公告)日：2021-12-23

申请号：US17285013

申请日：2019-10-21

Applicant: NIPPON STEEL CORPORATION

Inventor： Tatsuo YOKOI ,  Hiroshi SHUTO ,  Teruki HAYASHIDA ,  Jun ANDO ,  Mutsumi SAKAKIBARA

IPC: C21D9/46 ,  C22C38/58 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C23G1/08 ,  C21D8/02 ,  C21D6/00

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in which in a case where the thickness is denoted by t, a metallographic structure at a t/4 position from the surface includes, by area fraction, 77.0% to 97.0% of bainite or tempered martensite, 0% to 5.0% of ferrite, 0% to 5.0% of pearlite, 3.0% or more of residual austenite, and 0% to 10.0% of martensite, in the metallographic structure, the average grain size excluding the residual austenite is 7.0 μm or less, the average number density of iron-based carbides having a diameter of 20 nm or more is 1.0×106 carbides/mm2 or more, a tensile strength is 980 MPa or more, and an average Ni concentration on the surface is 7.0% or more.

公开(公告)号：US20240384381A1

公开(公告)日：2024-11-21

申请号：US18285546

申请日：2022-04-12

Applicant: NIPPON STEEL CORPORATION

Inventor： Takeshi TOYODA ,  Hiroshi SHUTO

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

Abstract: This hot-rolled steel sheet has a predetermined chemical composition and microstructure, in which, within regions obtained by dividing a sheet thickness cross section parallel to a rolling direction into three parts in a sheet thickness direction, when a pole density of the {001} plane of ferrite and bainite in a center region is Pi, and a pole density of the {001} plane of ferrite and bainite in a surface layer region is Ps, Pi/Ps is 1.2 to 2.0, and a tensile strength is 950 MPa or more.

公开(公告)号：US20230140358A1

公开(公告)日：2023-05-04

申请号：US17908581

申请日：2021-03-09

Applicant: NIPPON STEEL CORPORATION

Inventor： Mitsuru YOSHIDA ,  Shunsuke TANIGUCHI ,  Koutarou HAYASHI ,  Hiroshi SHUTO

IPC: C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/00 ,  C22C38/06 ,  C22C38/02 ,  C22C38/54 ,  C23C2/04

Abstract: This steel sheet has a predetermined chemical composition, Ex. C that is obtained by Ex. C = (%C) - 12 ( (%Ti*)/48 + (%V)/51 + (%Nb)/93 + (%Mo)/96 + (%W)/184} is 0.020% or less, a microstructure at a ¼ depth position of a sheet thickness from a surface contains 60% or more of ferrite, 0% to 5% of MA and a total of 0% to 5% of pearlite and cementite with a remainder of bainite in terms of area fractions, in the microstructure, the average crystal grain diameter is 10.0 µm or less, the average aspect ratio of crystal grains is 0.30 or more, the standard deviation of a Mn concentration is 0.60 mass% or less, a Ti-based carbide having a Baker-Nutting orientation relationship in the ferrite is precipitated in a semi-coherent state, and a tensile strength is 980 MPa or more.

公开(公告)号：US20220119902A1

公开(公告)日：2022-04-21

申请号：US17422406

申请日：2020-01-30

Applicant: NIPPON STEEL CORPORATION

Inventor： Hiroshi SHUTO ,  Koutarou HAYASHI ,  Hiroshi KAIDO ,  Akifumi SAKAKIBARA ,  Jun ANDO ,  Tetsu ASATO

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in which a metal microstructure contains, by area %, 3.0% or more of residual austenite, has a ratio L52/L7 of a length L52 of a grain boundary having a crystal orientation difference of 52° to a length L7 of a grain boundary having a crystal orientation difference of 7° about a direction of 0.10 or more and 0.18 or less, has a standard deviation of a Mn concentration of 0.60 mass % or less, and has a tensile strength of 980 MPa or more.

公开(公告)号：US20240384378A1

公开(公告)日：2024-11-21

申请号：US18689095

申请日：2022-09-14

Applicant: NIPPON STEEL CORPORATION

Inventor： Hiroshi SHUTO ,  Kazumasa TSUTSUI ,  Shunsuke KOBAYASHI ,  Akifumi SAKAKIBARA ,  Jun ANDO ,  Toshiki SUGIYAMA

IPC: C22C38/04 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, has a microstructure including, by area %, residual austenite of less than 3.0%, ferrite of 15.0% or more and less than 60.0%, and pearlite of less than 5.0%, in which an entropy value obtained by analyzing an SEM image of the microstructure using a gray-level co-occurrence matrix method is 10.7 or more, an inverse difference normalized value is 1.020 or more, a cluster shade value is −8.0×105 to 8.0×105, and a standard deviation of an Mn concentration is 0.60 mass % or less, and has a tensile strength of 980 MPa or more.

公开(公告)号：US20230279532A1

公开(公告)日：2023-09-07

申请号：US18019738

申请日：2021-06-15

Applicant: NIPPON STEEL CORPORATION

Inventor： Kazumasa TSUTSUI ,  Hiroshi SHUTO ,  Koutarou HAYASHI ,  Mitsuru YOSHIDA

IPC: C22C38/58 ,  C22C38/44 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/46 ,  C21D8/02

CPC classification number: C22C38/58 ,  C22C38/44 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/005 ,  C22C38/002 ,  C22C38/001 ,  C21D9/46 ,  C21D8/0226 ,  C21D8/0205 ,  C21D2211/008 ,  C21D2211/001 ,  C21D2211/005

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in a microstructure, in terms of area %, martensite and tempered martensite are more than 92.0% and 100.0% or less in total, residual austenite is less than 3.0%, and ferrite is less than 5.0%, an E value that indicates periodicity of the microstructure is 11.0 or more, the I value that indicates uniformity of the microstructure is less than 1.020, a standard deviation of a Mn concentration is 0.60 mass % or less, and a tensile strength is 980 MPa or more.

公开(公告)号：US20230133134A1

公开(公告)日：2023-05-04

申请号：US17907883

申请日：2021-03-08

Applicant: NIPPON STEEL CORPORATION

Inventor： Mutsumi SAKAKIBARA ,  Hiroshi SHUTO ,  Kazumasa TSUTSUI ,  Koutarou HAYASHI

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in a microstructure, by area %, ferrite is less than 15.0%, residual austenite is less than 3.0%, L52/L7, which is a ratio of a length L52 of a grain boundary having a crystal orientation difference of 52° to a length L7 of a grain boundary having a crystal orientation difference of 7° about a direction is 0.10 to 0.18, a standard deviation of a Mn concentration is 0.60 mass % or, less, and a tensile strength is 980 MPa or more.