公开(公告)号：US12208462B2

公开(公告)日：2025-01-28

申请号：US17319134

申请日：2021-05-13

Applicant: JFE Steel Corporation

Inventor： Hiroshi Matsuda ,  Yasuaki Okita ,  Muneo Matsushita ,  Rinsei Ikeda ,  Kenji Oi

IPC: B23K11/16 ,  B23K1/20 ,  B23K11/11 ,  B23K11/30 ,  B23K11/34 ,  B23K35/00 ,  B23K35/02 ,  B23K103/04 ,  B32B15/04 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/18 ,  C22C38/60 ,  H05B3/03

Abstract: A welding process used in a method of manufacturing a steel sheet assembly includes spot welding steel sheets performed for a heat time of 0.08 seconds or more using a convex electrode with a tip radius of curvature of 20 mm or more or a flat electrode such that the weld force F (kN) for initial 0.03 seconds of the heat time satisfies formula: F

公开(公告)号：US11958123B2

公开(公告)日：2024-04-16

申请号：US17252276

申请日：2019-06-17

Applicant: JFE STEEL CORPORATION

Inventor： Chikaumi Sawanishi ,  Hiroshi Matsuda ,  Rinsei Ikeda

IPC: B23K11/11 ,  B23K11/25 ,  B23K31/12 ,  B23K103/04

CPC classification number: B23K11/115 ,  B23K11/258 ,  B23K31/125 ,  B23K2103/04

Abstract: A resistance spot welding method includes: performing test welding; and performing actual welding after the test welding, wherein in subsequent current passage in the test welding, current passage is performed by constant current control under a condition: 0.5 δ Vtp/Vtm δ 2.0 when tc

公开(公告)号：US11904404B2

公开(公告)日：2024-02-20

申请号：US16973766

申请日：2019-06-17

Applicant: JFE STEEL CORPORATION

Inventor： Chikaumi Sawanishi ,  Hiroshi Matsuda ,  Rinsei Ikeda

IPC: B23K11/25 ,  B23K11/11 ,  B23K11/16

CPC classification number: B23K11/257 ,  B23K11/115 ,  B23K11/16

Abstract: A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein in the test welding, 0.2≤Vtp/Vtm≤1.5 is satisfied where Vtm is an average value of a voltage between the electrodes in main current passage in the test welding and Vtp is an average value of a voltage between the electrodes in subsequent current passage in the test welding, and in each of main current passage and subsequent current passage in the actual welding, a time variation curve of an instantaneous amount of heat generated per unit volume and a cumulative amount of heat generated per unit volume that are stored in a corresponding one of the main current passage and the subsequent current passage in the test welding are set as a target, and adaptive control welding is performed to control a current passage amount according to the target.

公开(公告)号：US11623298B2

公开(公告)日：2023-04-11

申请号：US16635165

申请日：2018-08-02

Applicant: JFE STEEL CORPORATION

Inventor： Chikaumi Sawanishi ,  Hiroshi Matsuda ,  Rinsei Ikeda

IPC: B23K11/11 ,  B23K11/25

Abstract: A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding. The test welding is performed under each of two or more welding conditions. In the actual welding, preliminary current passage is performed by constant current control in the same current pattern as in the preliminary current passage of the test welding, an electrical property between the electrodes in the preliminary current passage in the actual welding and an electrical property between the electrodes stored in the preliminary current passage in the test welding are compared for each welding condition to set a target in main current passage in the actual welding, and thereafter adaptive control welding is performed to control a current passage amount as the main current passage.

公开(公告)号：US11198917B2

公开(公告)日：2021-12-14

申请号：US16221890

申请日：2018-12-17

Applicant: JFE STEEL CORPORATION

Inventor： Hiroshi Matsuda ,  Hideyuki Takahashi ,  Hiroi Yamaguchi ,  Yasuyuki Hayakawa ,  Yukihiro Shingaki ,  Takashi Terashima

IPC: C21D8/12 ,  C23C8/26 ,  C21D9/00 ,  C21D9/46 ,  H01F41/02 ,  H01J37/32 ,  C23C8/38 ,  H01F1/16 ,  C23C8/02 ,  C23C8/80

Abstract: Provided is a method for nitriding a grain-oriented electrical steel sheet which is very useful in obtaining excellent magnetic properties with no variation, that enables generating glow discharge between positive electrodes and negative electrodes disposed in a nitriding zone and irradiating the generated plasma to a strip to perform appropriate nitriding.

公开(公告)号：US20210332454A1

公开(公告)日：2021-10-28

申请号：US17270613

申请日：2019-08-22

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yuma Honda ,  Shimpei Yoshioka ,  Koichi Taniguchi ,  Hiroshi Matsuda ,  Takeshi Murai ,  Nobuyuki Nakamura

IPC: C21D9/46 ,  C21D8/02 ,  C23C2/06 ,  C21D6/00 ,  C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/60 ,  C23C2/40 ,  C23C2/02

Abstract: A high-strength steel sheet of the present invention has a specific chemical composition. Furthermore, in the steel sheet, a degree of Mn segregation in a specific region is 1.5 or less; a maximum P concentration in a specific region is 0.08 mass % or less; in a specific region, at least one specific MnS particle group is present, the number of specific MnS particle groups is 2.0 or fewer per 1 mm2, and the number of specific oxide-based inclusions is 8 or fewer per 1 mm2; of all oxide-based inclusions, oxide-based inclusions having a specific composition are present in a number ratio of 80% or greater; the microstructure includes, in terms of a volume fraction, 30 to 95% martensite, 5 to 70% ferrite phase, less than 30% (and 0% or greater) bainite, and less than 2.0% (and 0% or greater) austenite phase; and a tensile strength is 980 MPa or greater.

公开(公告)号：US11065712B2

公开(公告)日：2021-07-20

申请号：US16305152

申请日：2017-05-23

Applicant: JFE STEEL CORPORATION

Inventor： Chikaumi Sawanishi ,  Hiroshi Matsuda ,  Rinsei Ikeda

IPC: B23K11/25 ,  B23K11/24 ,  B23K11/11 ,  B23K101/18 ,  B23K103/04

Abstract: A resistance spot welding method of squeezing parts to be welded, which are a plurality of overlapping metal sheets, by a pair of electrodes and passing a current while applying an electrode force to join the parts to be welded comprises: a first step of passing a current by constant current control to form a fusion zone having a diameter of not less than 2√{square root over (t)}, expressed in mm, between the metal sheets, where t, expressed in mm, is a sheet thickness of a thinnest metal sheet of the metal sheets; a second step of cooling the fusion zone to have a diameter of not greater than 80% of D, where D, expressed in mm, is a diameter of the fusion zone formed in the first step; and a third step of performing adaptive control welding by controlling a current passage amount according to a target that is set.

公开(公告)号：US20200377978A1

公开(公告)日：2020-12-03

申请号：US16766398

申请日：2018-08-20

Applicant: JFE Steel Corporation

Inventor： Hiromi Yoshitomi ,  Yasuaki Okita ,  Masaki Koba ,  Yoshihiko Ono ,  Hiroshi Matsuda

IPC: C22C38/04 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/20 ,  C22C38/60 ,  C21D8/02 ,  C21D9/46 ,  C23G1/00 ,  C23C2/06 ,  C23C2/12

Abstract: A high-strength galvanized steel sheet includes a steel sheet having a steel composition having a specific component composition, a steel structure containing martensite and bainite at more than or equal to 70% (including 100%), ferrite at less than 20% (including 0%), and retained austenite at less than 5% (including 0%) in terms of area ratio, the amount of diffusible hydrogen in steel being less than or equal to 0.20 mass ppm; and a galvanizing layer provided on a surface of the steel sheet, having a content amount of Fe of 8 to 15% in mass %, and having an coating weight per one surface of 20 to 120 g/m2, wherein the amount of Mn oxides contained in the galvanizing layer is less than or equal to 0.050 g/m2, and a tensile strength is more than or equal to 1100 MPa and a yield ratio is more than or equal to 0.85.

公开(公告)号：US20200230735A1

公开(公告)日：2020-07-23

申请号：US16488703

申请日：2018-03-01

Applicant: JFE Steel Corporation

Inventor： Koichi Taniguchi ,  Chikaumi Sawanishi ,  Katsutoshi Takashima ,  Hiroshi Matsuda ,  Rinsei Ikeda

IPC: B23K11/11 ,  B23K11/16 ,  B23K11/00

Abstract: Provided is a resistance spot welding method. The resistance spot welding method for joining a sheet set including a plurality of lapped steel sheets includes: holding the sheet set between a pair of electrodes; and energizing the sheet set under application of electrode force to thereby join the steel sheets together. At least one of the plurality of lapped steel sheets is a surface-treated steel sheet including a metal coating layer on a surface thereof. The energizing includes: a primary energizing step of performing energization to form a nugget portion; a non-energizing step in which, after the primary energizing step, the energization is suspended for an energization suspension time Tc (cycles); and a secondary energizing step of, after the non-energizing step, performing energization for reheating while the nugget portion is prevented from growing. During the energizing, the relations of a particular formula are satisfied.

公开(公告)号：US10662496B2

公开(公告)日：2020-05-26

申请号：US15326811

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Kazunori Tahara ,  Takeshi Yokota ,  Kaneharu Okuda ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/04 ,  C22C38/60 ,  C22C38/00 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C23C2/06 ,  C23F17/00

Abstract: Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, balance between high strength and ductility, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, and 5-20% of martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, and the retained austenite has a mean free path of 1.2 μm or less.