公开(公告)号：US20240424596A1

公开(公告)日：2024-12-26

申请号：US18701761

申请日：2022-10-28

Applicant: JFE STEEL CORPORATION

Inventor： Chikaumi SAWANISHI ,  Daiki YAMAGISHI ,  Nao KAWABE ,  Koichi TANIGUCHI ,  Katsutoshi TAKASHIMA

IPC: B23K11/11 ,  F16B5/08

Abstract: A resistance spot welded member includes overlapping steel sheets resistance-spot-welded together at a spot-shaped weld called a nugget, and a Zn alloy layer formed between two of the overlapping steel sheets. At least one of the steel sheets is a galvanized steel sheet having a Zn-based coated layer on its steel sheet surface. The resistance spot welded member satisfies the following formulas (1) and (2): C Fe ≥ 20 ( 1 ) 0

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：US20240181555A1

公开(公告)日：2024-06-06

申请号：US18285571

申请日：2022-03-07

Applicant: JFE STEEL CORPORATION

Inventor： Nao KAWABE ,  Chikaumi SAWANISHI ,  Katsutoshi TAKASHIMA ,  Koichi TANIGUCHI ,  Hiroshi MATSUDA ,  Daiki YAMAGISHI

IPC: B23K11/11 ,  B23K11/16 ,  B23K101/34 ,  B23K103/04

CPC classification number: B23K11/115 ,  B23K11/166 ,  B23K2101/34 ,  B23K2103/04

Abstract: A resistance spot welding method for joining two or more steel sheets including at least one zinc-coated steel sheet. The method includes a first current applying step and a second current applying step. The first current applying step involves forming a nugget having a nugget diameter of 3√t or more and 4.5√t or less by setting a current value I1 (kA) and a weld time, where t is a thickness of the thinnest steel sheet among the overlapping steel sheets. The second current applying step involves growing the nugget by repeating a cooling step for maintaining a zero-current state for 10 ms or more and less than 160 ms and a current applying step for applying a current for 20 ms or more and less than 200 ms at a current value I2 (kA) greater than or equal to the current value I1 (kA).

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.

公开(公告)号：US20240238891A1

公开(公告)日：2024-07-18

申请号：US18291661

申请日：2022-07-19

Applicant: JFE STEEL CORPORATION

Inventor： Nao KAWABE ,  Chikaumi SAWANISHI ,  Katsutoshi TAKASHIMA ,  Koichi TANIGUCHI ,  Hiroshi MATSUDA ,  Daiki YAMAGISHI

IPC: B23K11/11

CPC classification number: B23K11/115

Abstract: A resistance spot welding method in which a high strength zinc-based coated steel sheet used in a sheet set has an equivalent carbon content of 0.20% or more and a tensile strength of 780 MPa or more. The method includes performing a first energization step such that a current value at the end of the energization, a current value Is at the start of the energization, and a thickness of the thinnest steel sheet among steel sheets overlapping each other satisfy specified relationships. The method includes performing a second energization step in which a cooling step of holding a non-energization state for 10 ms or longer and shorter than 160 ms and performing energization at a current value equal to or more than the current value at the end of the first energization step for 20 ms or longer and shorter than 200 ms are repeated.

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.