公开(公告)号：US20220090224A1

公开(公告)日：2022-03-24

申请号：US17420024

申请日：2019-12-24

Applicant: NIPPON STEEL CORPORATION

Inventor： Takeshi TOYODA ,  Hitoshi NIKAIDO ,  Kohei NAKADA ,  Yui YAMASHITA ,  Kazuki MATSUDA

IPC: C21D9/46 ,  C21D9/50 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/50 ,  B23K9/16 ,  C22C38/58 ,  C22C38/54 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42

Abstract: Hot-rolled steel sheet having a chemical composition including, in mass %, C: 0.02 to 0.20%, Si: 0.01 to 1.50%, Mn: 0.10 to 3.00%, P: 0.10% or less, S: 0.010% or less, Al: 0.005 to 0.100%, Ti: 0.02 to 0.20%, N: 0.001 to 0.010%, Cu: 0 to 0.50%, Ni: 0 to 0.50%, Cr: 0 to 1.00%, Mo: 0 to 0.40%, Nb: 0 to 0.060%, V: 0 to 1.00%, B: 0 to 0.0100%, Ca: 0 to 0.0050%, O: 0.0100% or less, and the balance: Fe and impurities; in which: a steel micro-structure includes, in area %, ferrite: 60 to 80%, and a total of ferrite and bainite: 90% or more; an average of the crystal grain size of ferrite and bainite is 7.0 μm or less, a standard deviation of the crystal grain size is 2.0 or less; and a standard deviation of a diameter of Ti carbo-nitrides is 10 nm or less.

公开(公告)号：US20200378420A1

公开(公告)日：2020-12-03

申请号：US16636788

申请日：2018-08-20

Applicant: NIPPON STEEL CORPORATION

Inventor： Kazuki MATSUDA ,  Shinji KODAMA ,  Kotaro WATANABE ,  Masatoshi TOKUNAGA

IPC: F16B5/08

Abstract: A lap fillet arc welded joint includes: a first steel sheet and a second steel sheet which are overlapped each other, the first steel sheet and the second steel sheet each having a tensile strength of 950 MPa or more; and a weld metal which extends along a corner formed by an upper surface of the first steel sheet and an end surface of the second steel sheet. When: a toe angle of the weld metal is defined as β; the total number of concave portions present on the surface of the weld metal included a range of 0.4 mm or less from a fusion boundary is defined as NA; and the number of concave portions in contact with ferrite grains having a maximum grain size of 10 μm or more is defined as NB, the weld metal satisfies the following conditional expressions (1) and (2) at the same time. 0°

公开(公告)号：US20220379409A1

公开(公告)日：2022-12-01

申请号：US17761196

申请日：2020-10-05

Applicant: NIPPON STEEL CORPORATION

Inventor： Kazuki MATSUDA ,  Shinji KODAMA

IPC: B23K31/02 ,  B23K9/23

Abstract: A welded joint comprising: a pair of steel base materials having a sheet thickness of 0.4 to 4.0 mm, and at least one of which has a tensile strength of 780 MPa or more; and a weld metal that welds the pair of steel base materials, wherein, when the weld metal is seen in plan view, a weld toe of the weld metal has peaks and valleys, an average distance in a direction orthogonal to a weld line direction between a top point of a peak and a bottom point of a valley that are adjacent to one another is 3.0 mm or less, and an average number of a total of peaks and valleys, at which the distance in the direction orthogonal to the weld line direction between the top point of the peak and the bottom point of the valley that are adjacent to one another is 0.1 mm to 3.0 mm, is 2 to 30/15 mm, and an automobile component having the welded joint.

公开(公告)号：US20250059635A1

公开(公告)日：2025-02-20

申请号：US18725054

申请日：2022-12-22

Applicant: NIPPON STEEL CORPORATION

Inventor： Kazuki MATSUDA ,  Shinji KODAMA ,  Masahiro MATSUBA ,  Yoshinari ISHIDA

IPC: C22C38/04 ,  B23K35/30 ,  C22C38/00 ,  C22C38/02

Abstract: An arc weld metal according to an aspect of the present invention contains, in a unit mass %, 0.10% or more and 0.30% or less of C, 0.30% or more and 1.00% or less of Si, 1.30% or more and 3.00% or less of Mn, 0.0500% or less of P, 0.0100% or less of S, 0.01% or less of N, and 0.02% or more and 0.07% or less of O, a remainder including iron and impurities, and the residual austenite volume percentage being 3.0% or more and 16.0% or less, in a unit mass %.

公开(公告)号：US20190388995A1

公开(公告)日：2019-12-26

申请号：US16489144

申请日：2018-02-28

Applicant: NIPPON STEEL CORPORATION

Inventor： Shinji KODAMA ,  Kazuki MATSUDA ,  Yoshinari ISHIDA

IPC: B23K9/23 ,  B23K9/02 ,  B23K35/30

Abstract: The present invention relates to a fillet welded joint and a manufacturing method thereof, and addresses the problem of providing a fillet welded joint having excellent weld fatigue strength while suppressing low temperature cracking. In a fillet welded joint according to the present invention, a tensile strength of a base material is 980 MPa or more, a carbon equivalent is 0.36 or more and 0.60 or less, a tensile strength [MPa] is 1950 times or more of the carbon equivalent [wt%], an average carbon equivalent of weld metal is 0.45 or more and 0.65 or less, and at a prescribed position below a surface of a weld toe, a Vickers hardness HVbond at a boundary between the weld metal and a heat affected zone, an average value HVwmt of theVickers hardness of the weld metal in a position 0.1 mm or more and 0.3 mm or less to the weld metal side of the boundary, and an average value HVhaz of the Vickers hardness of the heat affected zone in a position 0.1 mm or more and 0.3 mm or less to the heat affected zone side of the boundary satisfy HVbond≤HVwmt, HVbond≥HVhaz−50, and HVhaz≤350.