公开(公告)号：US20230256534A1

公开(公告)日：2023-08-17

申请号：US18005057

申请日：2021-05-26

Applicant: JFE STEEL CORPORATION

Inventor： Satoshi MAEDA ,  Kazuki ENDOH ,  Yuki TOJI ,  Nao KAWABE

IPC: B23K11/11 ,  B23K31/02 ,  B23K31/12

CPC classification number: B23K11/115 ,  B23K31/02 ,  B23K31/12

Abstract: Provided is a resistance spot welding method suitable for manufacturing a weld joint exhibiting excellent delayed fracture resistance. The resistance spot welding method includes sandwiching two or more overlapped steel sheets between a pair of welding electrodes, applying current to the steel sheets while pressing the steel sheets, forming a nugget on overlapping surfaces of the steel sheets to join the steel sheets, and after the joining, directly or indirectly irradiating the nugget with sound waves having a frequency of 10 Hz or more and 100000 Hz or less so that a sound pressure level on a surface of the steel sheet is 30 dB or more.

公开(公告)号：US20210108282A1

公开(公告)日：2021-04-15

申请号：US17043514

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Kazuki ENDO ,  Yuki TOJI ,  Yoshimasa FUNAKAWA ,  Satoshi MAEDA ,  Mai AOYAMA

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  B32B15/01 ,  C23C2/02 ,  C23C2/28 ,  C23C2/40 ,  C23C2/06

Abstract: A high-strength steel includes a steel structure with: in area fraction, 60.0% to less than 90.0% of ferrite, 0% to less than 5.0% of unrecrystallized ferrite, 2.0% to 25.0% of martensite, 0% to 5.0% of carbide, and 0% to 3.0% of bainite; in volume fraction, more than 7.0% of retained austenite; in a cross-sectional view of 100 μm×100 μm, a value obtained by dividing number of retained austenite that are not adjacent to retained austenite whose crystal orientations are different by a total number of retained austenite being less than 0.80, an average crystal grain size of the ferrite being 6.0 μm or less, an average crystal grain size of the retained austenite being 3.0 μm or less, and a value obtained by dividing, by mass %, an average content of Mn in the retained austenite by an average content of Mn in steel being 1.50 or more.

公开(公告)号：US20240150864A1

公开(公告)日：2024-05-09

申请号：US18548970

申请日：2022-02-25

Applicant: JFE STEEL CORPORATION

Inventor： Satoshi MAEDA ,  Nao KAWABE ,  Hiromi YOSHITOMI

IPC: C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06 ,  C23C2/28

CPC classification number: C21D9/46 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06 ,  C23C2/285

Abstract: To provide a galvanized steel sheet having high strength; specifically, with a tensile strength of 1160 MPa or more and excellent resistance spot weldability. A chemical composition of a base steel sheet contains one or more of Ti, Nb, V, and Zr: 0.02% or more and 0.20% or less in total, and an amount of diffusible hydrogen in a zinc or zinc alloy coating layer is 0.40 mass ppm or less.

公开(公告)号：US20240307991A1

公开(公告)日：2024-09-19

申请号：US18576741

申请日：2022-05-17

Applicant: JFE STEEL CORPORATION

Inventor： Satoshi MAEDA ,  Kazuki ENDOH ,  Yuki TOJI ,  Nao KAWABE

IPC: B23K11/11

CPC classification number: B23K11/115

Abstract: Provided is a resistance spot welding method suitable for manufacturing a welded joint exhibiting excellent delayed fracture resistance. The resistance spot welding method includes sandwiching two or more overlapped steel sheets between a pair of welding electrodes, applying current to the steel sheets while pressing the steel sheets, forming a nugget on overlapping surfaces of the steel sheets to join the steel sheets, and after the joining, applying vibration directly or indirectly to the nugget so that the steel sheets are caused to vibrate at a frequency of 100 Hz or more and a maximum amplitude of 10 nm to 500 μm.

公开(公告)号：US20240150882A1

公开(公告)日：2024-05-09

申请号：US18548927

申请日：2022-02-25

Applicant: JFE STEEL CORPORATION

Inventor： Satoshi MAEDA ,  Hiromi YOSHITOMI ,  Masaki KOBA ,  Nao KAWABE ,  Tatsuya NAKAGAITO ,  Katsuya HOSHINO ,  Hiroshi MATSUDA

IPC: C22C38/60 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C23C2/06 ,  C23C2/28

CPC classification number: C22C38/60 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C23C2/06 ,  C23C2/285

Abstract: To provide a galvanized steel sheet having high strength, specifically, a tensile strength of 1,150 MPa or more, and excellent resistance spot weldability, a base steel sheet has a defined chemical composition, an amount of diffusible hydrogen in the base steel sheet is 0.20 mass ppm or less, and surface roughness Ra of the galvanized steel sheet is 0.6 μm or less.