公开(公告)号：US10435762B2

公开(公告)日：2019-10-08

申请号：US15129938

申请日：2015-03-13

Applicant: JFE Steel Corporation

Inventor： Katsutoshi Takashima ,  Yoshihiko Ono ,  Kohei Hasegawa

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/00

Abstract: A high-strength cold-rolled steel sheet has a composite structure containing 0.15 to 0.25% by mass of C, 1.8 to 3.0% by mass of Mn, and 0.0003 to 0.0050% by mass of B, and having a ferrite volume fraction of 20% to 50%, a retained austenite volume fraction of 7% to 20%, a martensite volume fraction of 1% to 8%, and the balance containing bainite and tempered martensite, and in the composite structure, ferrite has an average crystal grain diameter of 5 μm or less, retained austenite has an average crystal grain diameter of 0.3 to 2.0 μm and an aspect ratio of 4 or more, martensite has an average crystal grain diameter of 2 μm or less, a metal phase containing both bainite and tempered martensite has an average crystal grain diameter of 7 μm or less, the ratio of the volume fraction of tempered martensite to the volume fraction of a metal structure other than ferrite is 0.60 to 0.85, and the average C concentration in retained austenite is 0.65% by mass or more.

公开(公告)号：US20180002778A1

公开(公告)日：2018-01-04

申请号：US15542272

申请日：2015-08-28

Applicant: JFE STEEL CORPORATION

Inventor： Nobusuke Kariya ,  Yoshihiko Ono ,  Yoshimasa Funakawa ,  Kazuma Mori ,  Reiko Sugihara ,  Kenji Kawamura

IPC: C21D9/46 ,  B21B1/22 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/16 ,  C22C38/08 ,  C22C38/02 ,  C22C38/00 ,  C22C38/38 ,  B21B3/02 ,  C21D6/00 ,  C21D8/02 ,  C23G1/00

Abstract: Provided are a high-strength steel sheet and a method for manufacturing the steel sheet. The high-strength steel sheet has a specified chemical composition with the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 25% or less of a ferrite phase, 75% or more of a bainite phase and/or a martensite phase, and 5% or less of cementite, in which, in a surface layer that is a region within 50 μm from the surface in the thickness direction, the area ratio of a ferrite phase is 5% to 20%, and a tensile strength is 1180 MPa or more.

公开(公告)号：US09534269B2

公开(公告)日：2017-01-03

申请号：US14058580

申请日：2013-10-21

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Kenji Takahashi ,  Kaneharu Okuda ,  Shoichiro Taira ,  Michitaka Sakurai ,  Yusuke Fushiwaki

IPC: C21D8/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/58

CPC classification number: C21D8/0236 ,  C21D8/02 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/04 ,  C22C38/06 ,  C22C38/58

Abstract: A method of manufacturing a high strength cold rolled steel sheet includes hot-rolling and cold-rolling a steel slab annealing the steel sheet at an annealing temperature of 750° C. to 830° C.; subjecting the steel sheet to first cooling at an average cooling rate of 3° C./sec to 40° C./sec in a temperature range from the annealing temperature to 480° C.; subjecting the steel sheet to second cooling at an average cooling rate of 8° C./sec to 80° C./sec in a temperature range from 480° C. to Tc (° C.) given by formula (6): Tc=435−40×[% Mn]−30×[% Cr]−30×[% V]  (6) wherein [% A] is the content (% by mass) of alloying element A; and subjecting the steel sheet to third cooling at an average cooling rate of 0.3° C./sec to 30° C./sec in a temperature range from Tc (° C.) to 200° C.

Abstract translation: 提供一种用于例如通过压制成型工艺的汽车的压制成形用高强度冷轧钢板和这种钢板的制造方法。 多相钢板具有以质量％计含有0.015％以上且小于0.100％的碳，小于0.40％的硅，1.0〜1.9％的锰，超过0.015％〜0.05％的钢， 磷，0.03％以下的硫，0.01〜0.3％的可溶性铝，0.005％以下的氮，少于0.30％的铬，0.0050％以下的硼，小于0.15％的钼，0.4％以下 的钒，0.02％以下的钛，以及任选的铌，钨，锆，铜，镍，锡，锑，钙，铈，镧和镁中的至少一种，其中[Mneq]为2.0〜2.8， 是铁和杂质。 钢组成满足特定要素的多个参数公式。 钢板具有包含铁素体的微结构，并且含有马氏体的第二相的特定体积分数保留为3。

公开(公告)号：US12286680B2

公开(公告)日：2025-04-29

申请号：US17284981

申请日：2019-10-15

Applicant: JFE Steel Corporation

Inventor： Noriaki Kohsaka ,  Junya Tobata ,  Shinjiro Kaneko ,  Yasushi Kitani ,  Yoshihiko Ono ,  Tadachika Chiba

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06

Abstract: A thin steel sheet has a specific chemical composition. The thin steel sheet has a microstructure in which ferrite is present in an area fraction of 4% or less (including 0%), as-quenched martensite is present in an area fraction of 10% or less (including 0%), retained austenite is present in an amount of 7% or more and 20% or less, and upper bainite, lower bainite, and tempered martensite are present in a total area fraction of more than 71% and less than 93%; and BCC iron that has a misorientation of 1° or less and surrounds retained austenite having an equivalent circular diameter of 1 μm or less is present in an area fraction of 4% or more and 50% or less, and BCC iron that has a misorientation of more than 1° is present in an area fraction of 25% or more and 85% or less.

公开(公告)号：US12209299B2

公开(公告)日：2025-01-28

申请号：US17442744

申请日：2020-03-26

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yasushi Kitani ,  Hiroyuki Akimoto ,  Yoichiro Matsui

IPC: C22C38/00 ,  C21D1/25 ,  C21D1/76 ,  C21D8/02 ,  C21D8/04 ,  C21D9/48 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/34 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/58 ,  C22C38/60 ,  C23C2/28

Abstract: The steel sheet has a steel microstructure containing ferrite: 6% to 90% by area, a microstructure composed of one or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ: 10% to 94% by area in total, and retained γ: 3% to 20% by volume, a ratio (SUB/S2nd)×100(%) of an area ratio SUB of an upper bainite with a width in the range of 0.8 to 7 μm, a length in the range of 2 to 15 μm, and an aspect ratio of 2.2 or more in contact with retained γUB with a grain width in the range of 0.17 to 0.80 μm and an aspect ratio in the range of 4 to 25 to an area ratio S2nd of the microstructure composed of one or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ ranges from 2.0% to 15%.

公开(公告)号：US12071682B2

公开(公告)日：2024-08-27

申请号：US17415462

申请日：2019-10-25

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Yuma Honda ,  Nobuyuki Nakamura

IPC: C22C38/58 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C23C2/02

CPC classification number: C22C38/58 ,  C21D8/0205 ,  C21D8/021 ,  C21D8/0226 ,  C21D8/0236 ,  C22C38/001 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C23C2/02 ,  C23C2/0224 ,  C23C2/024 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A steel sheet having a specified chemical composition and a tensile strength of 1,320 MPa or more, and methods for producing the steel sheet. The steel sheet has a specified microstructure including martensite and bainite, the total area fraction of the martensite and the bainite being 92% or more and 100% or less, the balance being one or more selected from ferrite and retained austenite. The forumulae [% Ti]+[% Nb]>0.007 and [% Ti]×[% Nb]2≤7.5×10−6 are satisfied in the chemical composition.

公开(公告)号：US11739392B2

公开(公告)日：2023-08-29

申请号：US16076374

申请日：2017-02-07

Applicant: JFE STEEL CORPORATION

Inventor： Yusuke Kimata ,  Yoshihiko Ono ,  Kenji Kawamura

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

CPC classification number: C21D8/0247 ,  C21D6/002 ,  C21D6/005 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength steel sheet having a tensile strength TS of 1320 MPa or more and excellent workability. The high-strength steel sheet has a chemical composition containing, by mass %, C: 0.20% or more and 0.40% or less, Si: 0.5% or more and 2.5% or less, Mn: more than 2.4% and 5.0% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.01% or more and 0.5% or less, N: 0.010% or less, and Fe and inevitable impurities. A microstructure of the steel sheet includes, in terms of area fraction with respect to the whole steel sheet microstructure, lower bainite in an amount of 40% or more and less than 85%, martensite including tempered martensite in an amount of 5% or more and less than 40%, retained austenite in an amount of 10% or more and 30% or less, and polygonal ferrite in an amount of 10% or less (including 0%).

公开(公告)号：US11453927B2

公开(公告)日：2022-09-27

申请号：US16485511

申请日：2018-02-05

Applicant: JFE Steel Corporation

Inventor： Yuma Honda ,  Yoshihiko Ono

IPC: C21D9/46 ,  C21D8/02 ,  C23C2/06 ,  C22C38/00

Abstract: A cold rolled steel sheet having a high strength, an aging resistance, a high yield ratio and a small anisotropy of tensile strength is obtained by hot rolling and cold rolling a steel material containing in percent by mass C: 0.06-0.14%, Si: less than 0.50%, Mn: 1.6-2.5%, Nb: not more than 0.080% (including 0%), Ti: not more than 0.080% (including 0%), provided that Nb and Ti are contained in an amount of 0.020-0.080% in total, subjecting a cold rolled steel sheet continuous annealing including steps of soaking-annealing at a temperature of 840-940° C. for a holding time of 30-120 seconds, cooling from the soaking temperature to 600° C. at a rate of not less than 5° C./s, retaining in a temperature range of 600-500° C. for 30-300 seconds and then conducting a secondary cooling to apply such a steel structure that martensite is finely dispersed into ferrite base.

公开(公告)号：US11408059B2

公开(公告)日：2022-08-09

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 ,  C23C2/02 ,  C22C38/38 ,  C23C2/40 ,  C23C2/28 ,  C21D9/56 ,  C21D1/76 ,  C22C18/02 ,  C22C38/22 ,  C22C38/26 ,  C22C38/40 ,  C22C38/44 ,  C22C38/18 ,  C22C38/46 ,  C22C38/24 ,  C22C38/54 ,  C22C38/28 ,  C22C38/32 ,  C22C38/50 ,  C22C38/48 ,  C22C38/42 ,  C23C2/04 ,  B32B15/01 ,  C23C30/00 ,  C21D9/573 ,  B32B15/18 ,  C23C2/26 ,  B32B15/04

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：US11339452B2

公开(公告)日：2022-05-24

申请号：US16762501

申请日：2018-11-07

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi Takashima ,  Takayuki Futatsuka ,  Kentaro Sato ,  Shimpei Yoshioka ,  Yoshihiko Ono ,  Yoshimasa Funakawa

IPC: C22C38/58 ,  C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/60 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C23C2/06 ,  C23C2/12 ,  C21D1/18 ,  C22C38/04 ,  C22C38/12 ,  C23C2/26 ,  C23C2/40 ,  C23C2/28 ,  C23C30/00 ,  B32B15/04 ,  B32B15/18 ,  C22C38/26 ,  C22C38/18 ,  C22C38/28 ,  C22C38/34 ,  C22C38/24 ,  C22C38/14 ,  C22C38/30 ,  C22C38/20 ,  C22C38/32 ,  C22C38/40 ,  C22C38/10 ,  C22C38/22 ,  C22C38/38 ,  C22C38/16

Abstract: Disclosed is a hot-pressed steel sheet member having a tensile strength of 1780 MPa or more and excellent bending collapsibility. The hot-pressed steel sheet member includes: a specific chemical composition; a microstructure in which an average grain size of prior austenite grains is 8 μm or less, a volume fraction of martensite is 90% or more, and a solute C content is 25% or less of a total C content; and a tensile strength of 1780 MPa or more.