公开(公告)号：US20230295783A1

公开(公告)日：2023-09-21

申请号：US18020598

申请日：2021-06-15

Applicant: NIPPON STEEL CORPORATION

Inventor： Hiroshi SHUTO ,  Kazumasa TSUTSUI ,  Koutarou HAYASHI ,  Akifumi SAKAKIBARA ,  Jun ANDO ,  Toshiki SUGIYAMA

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

CPC classification number: C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/002 ,  C22C38/001 ,  C21D9/46 ,  C21D8/0205 ,  C21D8/0226 ,  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 1.020 or more, 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：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：US20230055479A1

公开(公告)日：2023-02-23

申请号：US17792985

申请日：2020-12-11

Applicant: NIPPON STEEL CORPORATION

Inventor： Hiroshi SHUTO ,  Kazumasa TSUTSUI ,  Jun ANDO ,  Koutarou HAYASHI ,  Akifumi SAKAKIBARA ,  Shunsuke KOBAYASHI

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

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in which a metallographic structure contains, by area %, less than 3.0% of residual austenite, 15.0% or more and less than 60.0% of ferrite, and less than 5.0% of pearlite, has a ratio L60/L7 of a length L60 of a grain boundary having a crystal misorientation of 60° to a length L7 of a grain boundary having a crystal misorientation of 7° about a direction of 0.60 or more, 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：US20220389554A1

公开(公告)日：2022-12-08

申请号：US17760933

申请日：2020-09-04

Applicant: NIPPON STEEL CORPORATION

Inventor： Hiroshi SHUTO ,  Kazumasa TSUTSUI ,  Koutarou HAYASHI ,  Akifumi SAKAKIBARA ,  Jun ANDO ,  Shota ENDO

IPC: C22C38/58 ,  C22C38/50 ,  C22C38/16 ,  C22C38/12 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in which a microstructure contains, by area %, less than 3.0% of residual austenite, 15.0% or more and less than 60.0% of ferrite, and less than 5.0% of pearlite, has a ratio L60/L7 of a length L60 of a grain boundary having a crystal misorientation of 60° to a length L7 of a grain boundary having a crystal misorientation of 7° about a direction of less than 0.60, 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：US20210269903A1

公开(公告)日：2021-09-02

申请号：US17258704

申请日：2019-07-26

Applicant: NIPPON STEEL CORPORATION

Inventor： Mai NAGANO ,  Koutarou HAYASHI ,  Akihiro UENISHI

IPC: C22C38/38 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00

Abstract: What is provided is a high-strength steel sheet including, by mass %: C: 0.05% to 0.15%; Si: 1.5% or less; Mn: 2.00% to 5.00%; P: 0.100% or less; S: 0.010% or less; Al: 0.001% to 2.000%; N: 0.010% or less; and a remainder of Fe and impurities, in which Ceq defined by Ceq=C+Si/90+Mn/100+1.5P+3S is less than 0.21, the high-strength steel sheet contains martensite in an area ratio of 98% or more, and a residual structure is in an area ratio of 2% or less, a two-dimensional homogeneous dispersion ratio S defined by S=Sy2/Sx2 (Sx2 is a dispersion value of Mn concentration profile data in a sheet width direction, and Sy2 is a dispersion value of the Mn concentration profile data in a sheet thickness direction) is 0.85 or more and 1.20 or less, and a tensile strength is 1200 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.

公开(公告)号：US20230047602A1

公开(公告)日：2023-02-16

申请号：US17790645

申请日：2020-12-11

Applicant: NIPPON STEEL CORPORATION

Inventor： Kazumasa TSUTSUI ,  Hiroshi SHUTO ,  Koutarou HAYASHI

IPC: C22C38/50 ,  C22C38/44 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/10 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/46 ,  C21D8/02

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in which a metallographic structure contains, by area %, more than 92.0% and 100.0% or less of martensite and tempered martensite in total, less than 3.0% of residual austenite, and less than 5.0% of ferrite, has a ratio S60/S7, which is a ratio of a density S60 of a length of a grain boundary having a crystal misorientation of 60° to a density S7 of a length of a grain boundary having a crystal misorientation of 7° about a direction, of more than 0.34 and less than 0.60, 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：US20220145415A1

公开(公告)日：2022-05-12

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 ,  C23C2/06 ,  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.

公开(公告)号：US20220081748A1

公开(公告)日：2022-03-17

申请号：US17423307

申请日：2020-01-30

Applicant: NIPPON STEEL CORPORATION

Inventor： Koutarou HAYASHI ,  Hiroshi SHUTO ,  Kazumasa TSUTSUI ,  Hiroshi KAIDO

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

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in which a metallographic structure contains, by area %, 3.0% or more of retained austenite, has a ratio L52/L7 of a length L52 of a grain boundary having a crystal misorientation of 52° to a length L7 of a grain boundary having a crystal misorientation of 7° about a direction of more than 0.18, has a standard deviation of a Mn concentration of 0.60 mass % or less, and has a tensile strength of 1180 MPa or more.