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：US20250065389A1

公开(公告)日：2025-02-27

申请号：US18726073

申请日：2023-04-05

Applicant: NIPPON STEEL CORPORATION

Inventor： Shunsuke KOBAYASHI ,  Ryoma KATO ,  Hiroshi SHUTO

IPC: B21D19/08

Abstract: A burring structural member resistant to fracture even if the burring structural part is bent back is provided. In the burring structural member of the present disclosure, a thickness T of the sheet-shaped part is 2.0 mm or more, a Charpy impact value vE(0) of the sheet-shaped part at 0° C. is 50 J/cm2 or more, a BCI value calculated by BCI=vE(0)/Lc based on the Charpy impact value vE(0) (J/cm2) and a maximum length Lc (μm) of a crack at the inside bend of the bent wall part of the burring structural parts is 2.5 or more, and a curvature radius R (mm) of the inside bend of the bent wall part is larger than R1 calculated by R1=25/BCI−1.5.

公开(公告)号：US20240209470A1

公开(公告)日：2024-06-27

申请号：US18288399

申请日：2022-03-02

Applicant: NIPPON STEEL CORPORATION

Inventor： Shunsuke KOBAYASHI ,  Hiroshi SHUTO

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

CPC classification number: C21D9/46 ,  C21D1/18 ,  C21D1/84 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: This hot-rolled steel sheet has a predetermined chemical composition and a microstructure containing, in area %, less than 3.00% of retained austenite with an Rcf value indicating a ratio between average fracture surface units before and after plastic deformation being 2.00 or more and a tensile strength of 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.