公开(公告)号：US20170152580A1

公开(公告)日：2017-06-01

申请号：US15327489

申请日：2015-06-09

Applicant: JFE STEEL CORPORATION

Inventor： Hideyuki Kimura ,  Koichiro Fujita ,  Hiroshi Hasegawa ,  Mai Aoyama

IPC: C21D9/46 ,  B21B3/00 ,  C23C2/06 ,  C23C2/40 ,  C23G1/08 ,  C21D8/02 ,  C22C38/38 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  B21B1/26

CPC classification number: C21D9/46 ,  B21B1/26 ,  B21B1/28 ,  B21B3/00 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C18/00 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C22C38/58 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23G1/081 ,  C23G1/085

Abstract: A method for manufacturing a high-strength galvanized steel sheet includes performing hot rolling, cold rolling, first annealing, pickling, and second annealing. The first annealing is performed to obtain a steel sheet having a steel microstructure including ferrite in an amount of 10% or more and 60% or less in terms of area ratio, and martensite, bainite, and retained austenite in a total amount of 40% or more and 90% or less in terms of area ratio. The second annealing includes heating to an annealing temperature of 750° C. or higher and 850° C. or lower, holding at the annealing temperature for 10 seconds or more and 500 seconds or less, cooling at an average cooling rate of 1° C./s or more and 15° C./s or less, performing a galvanizing treatment, and cooling to a temperature of 150° C. or lower at an average cooling rate of 5° C./s or more and 100° C./s or less.

公开(公告)号：US11788163B2

公开(公告)日：2023-10-17

申请号：US17042291

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki Endo ,  Yoshiyasu Kawasaki ,  Yuki Toji ,  Yoshimasa Funakawa ,  Mai Aoyama

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/28 ,  C22C38/16 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C21D8/02 ,  C21D6/00 ,  C22C38/00 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

CPC classification number: C21D9/46 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C22C38/38 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80% and tempered martensite being greater than 5% and 20% or less in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 μm or less; and the retained austenite being 3 μm or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.

公开(公告)号：US20210010100A1

公开(公告)日：2021-01-14

申请号：US17041567

申请日：2019-03-26

Applicant: JFE Steel Corporation

Inventor： Satoshi Maeda ,  Yoshiyasu Kawasaki ,  Yusuke Fushiwaki ,  Mai Aoyama

IPC: C21D9/46 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/00 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/32 ,  C22C38/60 ,  C21D8/02

Abstract: A method for producing a high-strength hot-dip galvannealed steel sheet, in which a high-strength steel sheet is used as a base material, includes a rolling step (x) of rolling a hot-dip galvannealed steel sheet with a coating layer having an Fe concentration of 8% to 17% by mass, and a heat treatment step (y) of heating the coated steel sheet which has been subjected to the rolling step (x) under the conditions satisfying the following formulae (1) and (2): (273+T)×(20+2×log10(t))≥8000   (1) 40≤T≤160   (2) where T: heating temperature (° C.) of the coated steel sheet, and t: holding time (hr) at the heating temperature T.

公开(公告)号：US12221705B2

公开(公告)日：2025-02-11

申请号：US18251269

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: C23C28/02 ,  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 ,  C23C2/02 ,  C23C2/26 ,  C23C2/28 ,  C25D3/20 ,  C25D5/36 ,  C23C2/06 ,  C23C2/40

Abstract: Provided is an alloyed 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 alloyed 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 exceeding 20.0 g/m2, and an alloyed 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：US11661642B2

公开(公告)日：2023-05-30

申请号：US17042250

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki Endo ,  Yoshiyasu Kawasaki ,  Yuki Toji ,  Yoshimasa Funakawa ,  Mai Aoyama

IPC: C22C38/04 ,  B21B27/10 ,  C21D6/00 ,  C21D8/02 ,  C22C33/02

CPC classification number: C22C38/04 ,  B21B27/106 ,  C21D6/005 ,  C21D8/0226 ,  C22C33/0264

Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80%, martensite being 5% to 35%, and tempered martensite being 0% to 5% in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 μm or less; and the retained austenite being 3 μm or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.

公开(公告)号：US10570474B2

公开(公告)日：2020-02-25

申请号：US15323163

申请日：2015-06-15

Applicant: JFE STEEL CORPORATION

Inventor： Mai Aoyama ,  Yoshitsugu Suzuki ,  Hideyuki Kimura

IPC: C21D9/46 ,  B21B3/00 ,  C23C2/02 ,  C23C2/06 ,  C22C38/06 ,  C22C38/60 ,  B21B1/26 ,  C22C38/00 ,  B21B1/28 ,  C23C2/28 ,  B21B1/22 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C23C2/40 ,  C23G1/00

Abstract: A method for manufacturing a high-strength galvanized steel sheet. The method includes a first heating step of holding the steel sheet in a temperature range of 750° C. to 880° C. for 20 s to 600 s in an atmosphere having an H2 concentration of 0.05% to 25.0% by volume and a dew point of −45° C. to −10° C., a cooling step, a rolling step of rolling the steel sheet with a rolling reduction of 0.3% to 2.0%, a pickling step of pickling the steel sheet with a pickling weight loss of 0.02 gram/m2 to 5 gram/m2 in terms of Fe, a second heating step of holding the steel sheet in a temperature range of 720° C. to 860° C. for 20 sec. to 300 sec. in an atmosphere having an H2 concentration of 0.05% to 25.0% by volume and a dew point of −10° C. or lower, and a galvanizing step.

公开(公告)号：US10329638B2

公开(公告)日：2019-06-25

申请号：US15329117

申请日：2015-06-10

Applicant: JFE STEEL CORPORATION

Inventor： Hideyuki Kimura ,  Hiroshi Hasegawa ,  Noriaki Kohsaka ,  Mai Aoyama

IPC: C21D9/46 ,  C23C2/02 ,  C23C2/06 ,  C23C2/26 ,  C23C2/28 ,  C22C38/00 ,  C22C38/14 ,  C22C38/58 ,  B21B1/22 ,  B32B15/01 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C18/00

Abstract: A high strength galvanized steel sheet that has a tensile strength (TS) of 780 MPa or higher and excellent bendability, fatigue resistance, and surface appearance quality and a method for producing the high strength galvanized steel sheet. The steel sheet includes, at a position ½ of a thickness of the steel sheet, 5% or more and 80% or less of a ferrite phase in terms of area fraction, 20% or more and 70% or less of a martensite phase in terms of area fraction, and 0% or more and 25% or less of a bainite phase in terms of area fraction.

公开(公告)号：US20240318290A1

公开(公告)日：2024-09-26

申请号：US18577328

申请日：2022-06-09

Applicant: JFE Steel Corporation

Inventor： Gentaro Takeda ,  Hideyuki Takahashi ,  Mai Aoyama ,  Maiko Watanabe ,  Tatsuya Ehashi

IPC: C23C2/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C23C2/00 ,  C23C2/28 ,  C23C2/40

CPC classification number: C23C2/0224 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C23C2/004 ,  C23C2/285 ,  C23C2/40

Abstract: When a hot-dip galvanizing treatment is performed on a steel sheet containing Si in an amount of 0.2 mass % or more by using a continuous hot-dip galvanizing apparatus including an annealing furnace in which a heating zone, a soaking zone, and a cooling zone are arranged in this order, a snout adjacent to the cooling zone, and hot-dip galvanizing equipment, a humidified nitrogen-hydrogen gas mixture containing moisture in such a manner that a certain expression is satisfied is supplied into a region on the downstream side of the soaking zone, gas nozzles are arranged over the entire perimeter of an inner wall of the snout, nitrogen gas or a nitrogen-hydrogen gas mixture is supplied through the gas nozzles downward along the inner wall, and the dew point in the snout is controlled to be −50° C. to −35° C.

公开(公告)号：US11643700B2

公开(公告)日：2023-05-09

申请号：US17043514

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Kazuki Endo ,  Yuki Toji ,  Yoshimasa Funakawa ,  Satoshi Maeda ,  Mai Aoyama

IPC: C21D9/46 ,  B32B15/00 ,  C21D6/00 ,  C21D8/00 ,  C22C38/00 ,  B32B15/01 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C21D2211/001 ,  C21D2211/003 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength steel includes a steel structure with: in area fraction, 60.0% to less than 90.0% of ferrite, 0% to less than 5.0% of unrecrystallized ferrite, 2.0% to 25.0% of martensite, 0% to 5.0% of carbide, and 0% to 3.0% of bainite; in volume fraction, more than 7.0% of retained austenite; in a cross-sectional view of 100 μm×100 μm, a value obtained by dividing number of retained austenite that are not adjacent to retained austenite whose crystal orientations are different by a total number of retained austenite being less than 0.80, an average crystal grain size of the ferrite being 6.0 μm or less, an average crystal grain size of the retained austenite being 3.0 μm or less, and a value obtained by dividing, by mass %, an average content of Mn in the retained austenite by an average content of Mn in steel being 1.50 or more.

公开(公告)号：US20200347479A1

公开(公告)日：2020-11-05

申请号：US16960733

申请日：2018-12-13

Applicant: JFE Steel Corporation

Inventor： Mai Aoyama ,  Kazuaki Tsuchimoto ,  Yusuke Fushiwaki

IPC: C21D9/46 ,  B32B15/01 ,  C22C38/38 ,  C22C38/28 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D6/00 ,  C25D5/36 ,  C25D5/50

Abstract: Provided are a high-strength electrogalvannealed steel sheet that has a TS of 780 MPa or higher and a method for manufacturing the high-strength electrogalvannealed steel sheet. The high-strength electrogalvannealed steel sheet has a composition including, in terms of % by mass, C: 0.030% or more and 0.250% or less, Si: 0.01% or more and 3.00% or less, Mn: 1.00% or more and 10.00% or less, P: 0.001% or more and 0.100% or less, and S: 0.0001% or more and 0.0200% or less, with the balance being Fe and unavoidable impurities. The steel sheet has an electrogalvannealed coating layer on a surface thereof. The electrogalvannealed coating layer has an Fe content of 8.0% to 15.0%. The steel sheet has a tensile strength of 780 MPa or higher. The steel sheet has a diffusible hydrogen content of 0.2 wt. ppm or less.