公开(公告)号：US20240123539A1

公开(公告)日：2024-04-18

申请号：US18278551

申请日：2021-04-05

Applicant: NIPPON STEEL CORPORATION

Inventor： Seiji FURUSAKO ,  Satoshi HIROSE ,  Chisato YOSHINAGA

IPC: B23K11/11 ,  F16B5/08

CPC classification number: B23K11/115 ,  F16B5/08

Abstract: A resistance spot welded joint according to an aspect of the present invention includes: a plurality of overlapping steel sheets; and a weld having a nugget by which the steel sheets are joined, and having a corona bond and a heat-affected zone formed around the nugget, in which one or more of the plurality of steel sheets are high strength steel sheets having a tensile strength of 780 MPa or more, one or more of the plurality of steel sheets are plated steel sheets having a zinc-based plating, the high strength steel sheet and the zinc-based plating are adjacent to each other on a contact surface, a diameter of the heat-affected zone is 1.5 times or more a diameter of the nugget, in the heat-affected zone, carbides having a circle equivalent diameter of 0.1 or more are distributed at a number density of 40/100 μm2 or more, and in the corona bond, an amount of an η phase of the zinc-based plating is 20 area % or less.

公开(公告)号：US20250144736A1

公开(公告)日：2025-05-08

申请号：US18833901

申请日：2023-02-07

Applicant: NIPPON STEEL CORPORATION

Inventor： Shinji KODAMA ,  Seiji FURUSAKO ,  Chisato YOSHINAGA ,  Takuya KUWAYAMA ,  Kengo TAKEDA ,  Takuya MITSUNOBU ,  Hironori SATO

IPC: B23K11/11 ,  B23K11/31 ,  B23K103/04

Abstract: This spot welding device is a spot welding device for performing spot welding on a plurality of steel sheets overlapping with each other by clamping the plurality of steel sheets between a pair of electrodes, and energizing the plurality of steel sheets while pressurizing the plurality of steel sheets, in which a speed at which the pair of electrodes approach each other is limited to at least 12.0 mm/s or slower during a period from start of the energization to end of the energization.

公开(公告)号：US20220055696A1

公开(公告)日：2022-02-24

申请号：US17275863

申请日：2019-09-26

Applicant: NIPPON STEEL CORPORATION

Inventor： Sho MATSUI ,  Chisato YOSHINAGA

IPC: B62D27/02 ,  B23K20/12 ,  B62D29/00

Abstract: According to the present invention, provided are a joint structure (100) which joins a plurality of overlapped steel members (110, 120) using a connecting element (130) having a shaft portion (131), the joint structure including: a first steel member (110); and one or more of second steel members (120) overlapping the first steel member (110), in which the shaft portion (131) of the connecting element (130) is penetrated through the second steel member (120), and the shaft portion (131) of the connecting element (130) and the second steel member (120) are joined by friction welding, and the shaft portion (131) and the first steel member (110) are joined by friction welding, and a joining method for obtaining the joint structure.

公开(公告)号：US20200325554A1

公开(公告)日：2020-10-15

申请号：US16772692

申请日：2017-12-15

Applicant: NIPPON STEEL CORPORATION

Inventor： Kengo TAKEDA ,  Kunio HAYASHI ,  Akihiro UENISHI ,  Hiroyuki KAWATA ,  Chisato YOSHINAGA ,  Yasunobu MIYAZAKI ,  Toyomitsu NAKAMURA

IPC: C21D9/46 ,  B32B15/01 ,  C22C38/38 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00

Abstract: A steel sheet having a chemical composition of the base metal including, in mass %, C: 0.17 to 0.40%, Si: 0.10 to 2.50%, Mn: 1.00 to 10.00%, P: 0.001 to 0.03%, S: 0.0001 to 0.02%, Al: 0.001 to 2.50%, N: 0.0001 to 0.010%, O: 0.0001 to 0.010%, Ti: 0 to 0.10%, Nb: 0 to 0.10%, V: 0 to 0.10%, B: 0 to 0.010%, Cr: 0 to 2.00%, Ni: 0 to 2.00%, Cu: 0 to 2.00%, Mo: 0 to 2.00%, Ca: 0 to 0.50%, Mg: 0 to 0.50%, REM: 0 to 0.50%, the balance: Fe and impurities, wherein the steel sheet has an internal oxidized layer in which at least one part of a crystal grain boundary is covered by oxides, and in which a grain boundary coverage ratio of oxides is 60% or more in a region from the surface of the base metal to a depth of 5.0 μm.

公开(公告)号：US20240327962A1

公开(公告)日：2024-10-03

申请号：US18711903

申请日：2022-11-29

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Chisato YOSHINAGA ,  Takuya KUWAYAMA ,  Kengo TAKEDA ,  Takuya MITSUNOBU ,  Seiji FURUSAKO ,  Tatsuya OBUCHI

IPC: C22C38/04 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C23C2/06 ,  C23C2/20 ,  C23C2/28 ,  C23C2/40

CPC classification number: C22C38/04 ,  C21D6/005 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C22C38/02 ,  C22C38/06 ,  C23C2/06 ,  C23C2/20 ,  C23C2/28 ,  C23C2/40 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/003 ,  C21D2211/005 ,  C21D2211/008 ,  C21D2211/009

Abstract: Provided are a hot dip galvanized steel sheet having a predetermined chemical composition, and a steel microstructure comprising, by vol %, ferrite: 0 to 50%, tempered martensite: 1% or more, retained austenite: 5% or more, fresh martensite: 0 to 15%, total of pearlite and cementite: 0 to 5%, and balance: bainite, when measuring by GDS, a maximum value of Al concentration of an Al rich layer present at an interface of the base steel sheet and the hot dip galvanized layer is 2.0 mass % or more and an Sis/Sib right under the interface is 0.90 or less, a number density of recessed parts with a depth of more than 2 μm at the interface is 2.0/100 μm or less per interface length, and a tensile strength is 980 MPa or more, and a method for producing the same.

公开(公告)号：US20240307992A1

公开(公告)日：2024-09-19

申请号：US18264933

申请日：2022-03-29

Applicant: NIPPON STEEL CORPORATION

Inventor： Chisato YOSHINAGA ,  Masanori YASUYAMA ,  Aoshi KAWAI ,  Matsuo KAYANO

IPC: B23K11/16 ,  B23K11/11 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54

CPC classification number: B23K11/16 ,  B23K11/11 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54

Abstract: A spot welded joint is provided in which, in a cross section in a sheet thickness direction of a sheet set in which two or more steel sheets including at least one steel sheet having a C content of 0.280% by mass or more and 0.700% by mass or less overlap, an average of ratios of major axes to minor axes (major axes/minor axes) of prior austenite grains in a melting boundary region, which is up to 1 mm inside a melting boundary of a nugget end portion, is in a range of 1.0 to 1.5, and the number density of iron-based carbides having an equivalent circle diameter of 30 nm or more in the melting boundary region is 3.0×106×C content (mass %) or more per 1 mm2. The sheet set, in which the C content of at least one steel sheet is 0.280% by mass or more and 0.700% by mass or less, is spot welded under a specific condition, and then tempered under a specific condition.