公开(公告)号：US11136644B2

公开(公告)日：2021-10-05

申请号：US16325299

申请日：2017-08-29

Applicant: JFE STEEL CORPORATION

Inventor： Yoshie Obata ,  Katsutoshi Takashima ,  Takashi Kobayashi ,  Hiroshi Matsuda

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C23F17/00 ,  B32B15/01 ,  C23C2/06 ,  C22C38/60 ,  C21D8/04 ,  C22C38/18 ,  C23C2/28 ,  C23C2/40 ,  C21D1/18 ,  C21D1/25 ,  C22C18/04 ,  C25D3/22

Abstract: A high-strength cold rolled steel sheet having a specified chemical composition and a method for producing the same. The steel sheet having a microstructure including, in terms of volume fraction, 35% or less of ferrite, 1% or more and 10% or less of retained austenite, 2% or more and 12% or less of as-quenched martensite, and a total of 25% to 70% of bainite and tempered martensite. The microstructure has an average crystal grain diameter of the ferrite: 5.0 μm or less, an average crystal grain diameter of the retained austenite: 2.0 μm or less, an average crystal grain diameter of the as-quenched martensite: 3.0 μm or less, an average crystal grain diameter of the bainite and the tempered martensite phase: 4.0 μm or less, and an average intergrain distance of the as-quenched martensite of 1.0 μm or more.

公开(公告)号：US10954578B2

公开(公告)日：2021-03-23

申请号：US15520236

申请日：2015-10-29

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Takeshi Yokota ,  Takako Yamashita ,  Kazuhiro Seto

IPC: C21D9/46 ,  C23C2/12 ,  C23C2/28 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C22C38/14 ,  C22C38/00 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C22C38/38 ,  C23C2/40 ,  C23G1/00 ,  C25D3/22

Abstract: Disclosed is a steel sheet having a predetermined chemical composition and a steel microstructure that contains, in area ratio, 35% or more and 80% or less of polygonal ferrite and 5% or more and 25% or less of martensite, and that contains, in volume fraction, 8% or more of retained austenite, in which the polygonal ferrite, the martensite, and the retained austenite have a mean grain size of 6 μm or less, 3 μm or less, and 3 μm or less, respectively, and each have a mean grain aspect ratio of 2.0 or less, and in which a value obtained by dividing an Mn content in the retained austenite in mass % by an Mn content in the polygonal ferrite in mass % equals 2.0 or more.

公开(公告)号：US10940556B2

公开(公告)日：2021-03-09

申请号：US16323570

申请日：2017-08-21

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Hiroshi Matsuda ,  Rinsei Ikeda ,  Yoshiyasu Kawasaki

IPC: B32B15/00 ,  B23K11/16 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C22C38/14 ,  B23K11/20 ,  C22C38/04 ,  B23K11/11 ,  C22C38/12 ,  B32B15/01 ,  B23K11/00 ,  F16B5/08 ,  B23K103/04 ,  B23K103/18 ,  B23K101/18 ,  B23K101/34 ,  B23K101/00

Abstract: Provided is an automotive member, or particularly, a steel sheet having a tensile strength exceeding 900 MPa. The automotive member has a resistance weld for fixing two or more steel sheets containing a predetermined composition, in which a maximum hardness (HVBM) in a heat-affected zone of the resistance weld is at least 1.1 times hardness (HVW) of a nugget in the resistance weld formed in a softest steel sheet of a sheet set during resistance welding, and furthermore, an average grain size of a steel sheet structure of the heat-affected zone within 2 mm in a direction at a right angle to a sheet thickness from an end part of the nugget of the high-strength steel sheet is 3 μm or less, and a minimum hardness (HVmin) in the heat-affected zone is at least 90% of hardness (HVα) of the high-strength steel sheet before the resistance welding.

公开(公告)号：US20210023650A1

公开(公告)日：2021-01-28

申请号：US16980098

申请日：2019-03-20

Applicant: JFE Steel Corporation

Inventor： Muneo Matsushita ,  Rinsei Ikeda ,  Hiroshi Matsuda ,  Daiki Yamagishi

IPC: B23K20/12

Abstract: Disclosed are rotating tools for double-sided friction stir welding that are applied to double-sided friction stir welding, which is a technique for welding two metal plates by rotating a pair of rotating tools, which oppose each other, in opposite directions, a double-sided friction stir welding apparatus that uses the rotating tools, and a double-sided friction stir welding method. A pair of rotating tools for double-sided friction stir welding that are used in double-sided friction stir welding, which is a technique for welding metal plates by using a pair of rotating tools that are each disposed on one of first and second surfaces of an unwelded portion of the metal plates such that the rotating tools rotate in opposite directions, include end portions each of which is formed in a circular and planar shape. The end portions are each made of a material harder than the metal plates.

公开(公告)号：US10570475B2

公开(公告)日：2020-02-25

申请号：US15327126

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Yoshie Obata ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/32 ,  C22C38/14 ,  C22C38/60 ,  C21D8/02 ,  C23C2/28 ,  C23C2/40 ,  C23C2/06 ,  C22C38/12 ,  C22C38/28 ,  C22C38/38 ,  C22C18/04

Abstract: Disclosed is a high-strength steel sheet having a predetermined chemical composition, satisfying the condition that Mn content divided by B content equals 2100 or less, and a steel microstructure that contains, by area, 25-80% of ferrite and bainitic ferrite in total, 3-20% 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 an aggregate of retained austenite formed by seven or more identically-oriented retained austenite grains accounts for 60% or more by area of the entire retained austenite.

公开(公告)号：US10450626B2

公开(公告)日：2019-10-22

申请号：US15462241

申请日：2017-03-17

Applicant: JFE Steel Corporation

Inventor： Hiroshi Matsuda ,  Tatsuya Nakagaito ,  Takayuki Futatsuka ,  Shusaku Takagi ,  Yasunobu Nagataki

IPC: C21D9/46 ,  B32B15/01 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/38 ,  C23C2/02 ,  C23C2/28 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/40 ,  C23C2/06 ,  C23F17/00

Abstract: A high-strength hot-dip galvanized steel sheet excellent in formability includes, on the basis of mass percent, 0.05-0.3% C, 1.4% or less (including 0%) Si, 0.08%-3% Mn, 0.003-0.1% P, 0.07% or less S, 0.1-2.5% Al, 0.1-0.5% Cr, and 0.007% or less N, Si+Al≥0.5%, and the balance being Fe and incidental impurities, wherein the steel sheet has a retained austenite content of 3% or more by volume fraction, a stretch-flange formability λ>50% and wherein the average aspect ratio (major axis/minor axis) of retained austenite grains is less than 2.5.

公开(公告)号：US20190001429A1

公开(公告)日：2019-01-03

申请号：US16062407

申请日：2016-12-13

Applicant: JFE STEEL CORPORATION

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

IPC: B23K11/11 ,  B23K11/16

Abstract: Provided is a resistance spot welding method that inhibits, in accordance with the degree of axis misalignment between electrodes, the occurrence of cracking in a weld regardless of the steel grade. In resistance spot welding methods according to the present invention, H (ms) is an electrode force retaining time after completion of current passage, D (mm) is an amount of axis misalignment between the electrodes, t (mm) is a total sum of sheet thicknesses of a plurality of overlapping steel sheets, T (MPa) is a tensile strength of a steel sheet having a highest tensile strength among the plurality of steel sheets, F (N) is an electrode force, and d (mm) is a tip diameter of one electrode of the pair of electrodes that has a smaller tip diameter. The electrode force retaining time H is specified to be a predetermined value or greater.

公开(公告)号：US09761360B2

公开(公告)日：2017-09-12

申请号：US14387953

申请日：2013-03-29

Applicant: JFE Steel Corporation

Inventor： Masanori Takenaka ,  Toshito Takamiya ,  Hiroshi Matsuda

IPC: H01F1/147 ,  C21D9/46 ,  C22C38/00 ,  C22C38/16 ,  H01F41/02 ,  C22C38/60 ,  H01F1/16 ,  C21D8/12 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08

CPC classification number: H01F1/14775 ,  C21D8/1222 ,  C21D8/1233 ,  C21D8/1261 ,  C21D8/1266 ,  C21D8/1272 ,  C21D8/1288 ,  C21D9/46 ,  C22C38/001 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/60 ,  H01F1/16 ,  H01F41/02

Abstract: A method of manufacturing a grain oriented electrical steel sheet uses austenite (γ)-ferrite (α) transformation which develops excellent magnetic properties, uses Tα calculated from equation (1) and performs the first pass of rough hot rolling at a temperature of (Tα−100)° C. or higher with a rolling reduction of 30% or more, and further uses Tγmax calculated from equation (2) and performs any one pass of finish hot rolling in a temperature range of (Tγmax±50)° C. with a rolling reduction of 40% or more: Tα[° C.]=1383.98−73.29[% Si]+2426.33[% C]+271.68[% Ni]  (1) Tγmax[° C.]=1276.47−59.24[% Si]+919.22[% C]+149.03[% Ni]  (2) where [% A] represents content of element “A” in steel (mass %).

公开(公告)号：US12276028B2

公开(公告)日：2025-04-15

申请号：US18251422

申请日：2021-11-05

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke Yamamoto ,  Katsutoshi Takashima ,  Mai Aoyama ,  Yusuke Okumura ,  Tomomi Kanazawa ,  Katsuya Hoshino ,  Hiroshi Matsuda ,  Ei Okumura ,  Yoichi Makimizu ,  Masaki Koba

IPC: C23C2/02 ,  C21D1/74 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C33/04 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C23C2/28 ,  C23C2/40 ,  C23C28/00 ,  C23F17/00 ,  C25D3/56 ,  C25D5/36 ,  C25D5/48 ,  B23K11/11 ,  B23K11/16 ,  B23K101/34

Abstract: Provided is a galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of more than 20.0 g/m2, and a galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50 % at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

公开(公告)号：US12134153B2

公开(公告)日：2024-11-05

申请号：US16311268

申请日：2017-06-19

Applicant: Kobe Steel, Ltd. ,  JFE Steel Corporation

Inventor： Minoru Miyata ,  Reiichi Suzuki ,  Hiroshi Matsuda ,  Rinsei Ikeda ,  Sachiko Suzuki ,  Satoru Ando

IPC: B23K9/173 ,  B23K9/025 ,  B23K9/23 ,  B23K35/30 ,  B23K35/32 ,  B23K35/38

Abstract: A gas-shielded arc welding method includes welding a steel plate having a tensile strength of 780 MPa or more while feeding a consumable electrode via a welding torch and flowing a shielding gas. The consumable electrode includes, in mass %, C: 0 to 0.20%, Si: 0 to 0.50%, Mn: 0 to 0.50%, Cr: 1.00% to 9.00%, S: 0.0020% to 0.0600%, and Ni: 0 to 0.50%. The shielding gas includes, in vol. %, at least one of CO2 and O2: 1% to 15% in total, with the remainder being Ar and unavoidable impurities. Welding is performed under the condition satisfying the relationship of 1≤{−0.05×[CO2+O2]}+[Cr]≤8.3, and [Cr] represents the content of Cr in the consumable electrode, and [CO2+O2] represents a total content of at least one of CO2 and O2 in the shielding gas.