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：US20220025499A1

公开(公告)日：2022-01-27

申请号：US17297697

申请日：2020-03-03

Applicant: NIPPON STEEL CORPORATION

Inventor： Mitsuru YOSHIDA ,  Nobusato KOJIMA

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

Abstract: This steel sheet has a predetermined chemical composition and the steel sheet in which, at a ¼ depth position of a sheet thickness from a surface, an average grain size is 15.0 μm or less, a total grain boundary number density of solute C and solute B is 1.0 solute/nm2 or more and 12.0 solutes/nm2 or less, a total of pole densities of {211} and {332} in a thickness middle portion is 12.0 or less, and a tensile strength is 780 MPa or more is adopted.

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：US20240301537A1

公开(公告)日：2024-09-12

申请号：US18578652

申请日：2022-09-08

Applicant: NIPPON STEEL CORPORATION

Inventor： Mitsuru YOSHIDA ,  Kazuo HIKIDA

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 ,  C22C38/28

CPC classification number: C22C38/38 ,  C21D1/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0263 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C21D2211/009

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in which, when a region of ⅛ to ⅜ of a sheet thickness in a sheet thickness direction from a surface is defined as a ¼ depth position, a microstructure at the ¼ depth position includes, by area fraction, retained austenite: less than 3.0%, ferrite: less than 30.0%, and pearlite: less than 5.0%, at the ¼ depth position, an average number density of Ti-based carbides having a longest diameter of 15 nm or more is 1.0×104/mm2 or more, and an average grain size dq is 15.0 μm or less, and a tensile strength is 980 MPa or more.

公开(公告)号：US20230257845A1

公开(公告)日：2023-08-17

申请号：US18016141

申请日：2021-06-15

Applicant: NIPPON STEEL CORPORATION

Inventor： Hiroshi SHUTO ,  Kazumasa TSUTSUI ,  Koutarou HAYASHI ,  Akifumi SAKAKIBARA ,  Jun ANDO ,  Mitsuru YOSHIDA

IPC: C21D9/46 ,  C22C38/00 ,  C22C38/50 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/10 ,  C21D8/02 ,  C21D1/84

CPC classification number: C21D9/46 ,  C22C38/005 ,  C22C38/50 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/002 ,  C22C38/001 ,  C22C38/10 ,  C21D8/0226 ,  C21D8/0205 ,  C21D1/84 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/009

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in a microstructure, in terms of area %, residual austenite is less than 3.0%, ferrite is 15.0% or more and less than 60.0%, and pearlite is less than 5.0%, an E value that indicates periodicity of the microstructure is 10.7 or more, and an 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：US20230034898A1

公开(公告)日：2023-02-02

申请号：US17788672

申请日：2021-01-29

Applicant: NIPPON STEEL CORPORATION

Inventor： Masaharu OKA ,  Nobusato KOJIMA ,  Mitsuru YOSHIDA

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/00 ,  C22C38/06 ,  C22C38/14 ,  B21C47/02 ,  C23C2/04

Abstract: A hot-rolled steel sheet has a predetermined chemical composition in which a microstructure includes 99% or more of martensite by volume fraction and a remainder in microstructure including residual austenite and ferrite, in a cross section parallel to a rolling direction, an average aspect ratio of prior austenite grains is less than 3.0, a proportion of sulfides having an aspect ratio of more than 3.0 among sulfides having an area of 1.0 μm2 or more is 1.0% or, less, in a thickness middle portion, and a pole density of {211} orientation is 3.0 or less, and a tensile strength TS is 980 MPa or higher.

公开(公告)号：US20210140005A1

公开(公告)日：2021-05-13

申请号：US16624771

申请日：2018-07-06

Applicant: NIPPON STEEL CORPORATION

Inventor： Mitsuru YOSHIDA ,  Nobusato KOJIMA ,  Yuuki KANZAWA ,  Kohhei KAMIYA

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

Abstract: A hot-rolled steel sheet according to an aspect of the present invention has a predetermined chemical composition, in which, in a location at a depth of ¼ of a sheet thickness from a surface, an area ratio of ferrite is 10% to 55%, a total area ratio of bainite and martensite is 45% to 90%, a total area ratio of the ferrite, the bainite, and the martensite is 90% or more, an average crystal grain size is 12.0 μm or less, in a texture measured in a sheet thickness central portion, a maximum pole density of orientation groups of {100} , {211} , {311} , {110} , and {332} is 8.0 or less, a total of pole densities of {211} and {332} is 10.0 or less, and a tensile strength is 950 MPa or more.

公开(公告)号：US20230323496A1

公开(公告)日：2023-10-12

申请号：US18021066

申请日：2021-06-15

Applicant: NIPPON STEEL CORPORATION

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

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

CPC classification number: C21D8/0226 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/009

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in a microstructure, in terms of area%, residual austenite is less than 3.0%, ferrite is less than 15.0%, and pearlite is less than 5.0%, an E value that indicates periodicity of the microstructure is less than 10.7, and an 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 780 MPa or more.

公开(公告)号：US20230295761A1

公开(公告)日：2023-09-21

申请号：US18020596

申请日：2021-08-05

Applicant: NIPPON STEEL CORPORATION

Inventor： Mitsuru YOSHIDA ,  Tsuyoshi YAMAZAKI

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

CPC classification number: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/14 ,  C22C38/001 ,  C22C38/002 ,  C23C2/40 ,  C21D8/0226 ,  B21C47/02 ,  C21D2211/001 ,  C21D2211/003 ,  C21D2211/008 ,  C21D2211/009

Abstract: This steel sheet has a predetermined chemical composition, at a depth position of ¼ of a sheet thickness from a surface, an area fraction of GAM0.5-1.7 is 50% or more and 100% or less, an area fraction of GAM>1.7 is 0% or more and 20% or less, an area fraction of GAM≤0.5 is 0% or more and less than 50%, an area fraction of residual austenite is 0% or more and less than 4%, a total area fraction of the residual austenite, fresh martensite, cementite and pearlite is 0% or more and 10% or less, an average grain size is 15.0 μm or less, an average dislocation density is 1.0×1014/m2 or more and 4.0×1015/m2 less, a total of pole densities of {211} and {332} in a thickness middle portion is 12.0 or less, and a tensile strength is 980 MPa or more.