公开(公告)号：US20220275469A1

公开(公告)日：2022-09-01

申请号：US17629857

申请日：2020-07-29

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Yu Hashimoto ,  Shinjiro Kaneko ,  Yoshihiko Ono

IPC: C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C21D8/02 ,  C23C2/40

Abstract: The high strength steel sheet of the present invention has a specific chemical composition, and contains, in terms of area fraction relative to an entire steel microstructure, 30% or more and 100% or less ferrite, 0% or more and 70% or less martensite, and less than 20% in total of pearlite, bainite and retained austenite, a total content of Nb and Ti contained in a precipitate having a particle size of smaller than 20 nm is 25 mass ppm or more and 220 mass ppm or less, and the difference between the maximum value and the minimum value of the total content of Nb and Ti contained in the precipitate having a particle size of smaller than 20 nm, in the longitudinal direction of the steel sheet, is smaller than 20 mass ppm.

公开(公告)号：US20220235442A1

公开(公告)日：2022-07-28

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

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：US20220170126A1

公开(公告)日：2022-06-02

申请号：US17425824

申请日：2020-01-14

Applicant: JFE Steel Corporation

Inventor： Yuka Miyamoto ,  Yasuhiro Sakurai ,  Yoshihiko Ono

IPC: C21D9/46 ,  C22C38/46 ,  C22C38/44 ,  C22C38/54 ,  C22C38/28 ,  C22C38/26 ,  C22C38/20 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00

Abstract: A high-carbon hot-rolled steel sheet and a method for manufacturing the steel sheet are provided. The high-carbon hot-rolled steel sheet has a particular chemical composition. The microstructure of the steel sheet includes ferrite, cementite, and pearlite that accounts for 6.5% or less of the entire microstructure by area fraction. The proportion of the number of cementite grains having an equivalent circle diameter of 0.1 μm or less to the total number of cementite grains is 20% or less, the average cementite grain size is 2.5 μm or less, and the cementite accounts for 3.5% or more and 10.0% or less of the entire microstructure by area fraction. The average concentration of solute B in a region extending from a surface layer to a depth of 100 μm is 10 mass ppm or more. The average concentration of N present as AlN in the region is 70 mass ppm or less.

公开(公告)号：US20220106663A1

公开(公告)日：2022-04-07

申请号：US17425112

申请日：2020-01-14

Applicant: JFE Steel Corporation

Inventor： Yuka Miyamoto ,  Yasuhiro Sakurai ,  Yoshihiko Ono

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/54 ,  C22C38/46 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/20 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

Abstract: A high-carbon hot-rolled steel sheet and a method for manufacturing the steel sheet are provided. The high-carbon hot-rolled steel sheet has a particular chemical composition. The microstructure of the steel sheet includes ferrite, cementite, and pearlite that accounts for 6.5% or less of the entire microstructure by area fraction. The proportion of the number of cementite grains having an equivalent circle diameter of 0.1 μm or less to the total number of cementite grains is 20% or less, the average cementite grain size is 2.5 μm or less, and the cementite accounts for 1.0% or more and less than 3.5% of the entire microstructure by area fraction. The average concentration of solute B in a region extending from a surface layer to a depth of 100 μm is 10 mass ppm or more. The average concentration of N present as AlN in the region is 70 mass ppm or less.

公开(公告)号：US11268164B2

公开(公告)日：2022-03-08

申请号：US16329504

申请日：2017-09-28

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Kenta Hidaka ,  Ryosuke Yamaguchi

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/12 ,  C23C2/06 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C23C2/02 ,  C23C2/40 ,  C21D1/18 ,  C22C38/18 ,  C23C2/28 ,  C22C38/60

Abstract: A steel sheet having a specified chemical composition and a method for producing the steel sheet. The steel sheet has a microstructure including martensite and bainite. The total area fraction of the martensite and the bainite to the entirety of the microstructure is 95% or more and 100% or less. The balance of the microstructure is at least one of ferrite and retained austenite. The microstructure includes specific inclusion clusters, the content of the inclusion clusters in the microstructure being 5 clusters/mm2 or less. The microstructure includes prior-austenite grains having an average size of more than 5 μm. The steel sheet has a tensile strength of 1320 MPa or more.

公开(公告)号：US20210332454A1

公开(公告)日：2021-10-28

申请号：US17270613

申请日：2019-08-22

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yuma Honda ,  Shimpei Yoshioka ,  Koichi Taniguchi ,  Hiroshi Matsuda ,  Takeshi Murai ,  Nobuyuki Nakamura

IPC: C21D9/46 ,  C21D8/02 ,  C23C2/06 ,  C21D6/00 ,  C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/60 ,  C23C2/40 ,  C23C2/02

Abstract: A high-strength steel sheet of the present invention has a specific chemical composition. Furthermore, in the steel sheet, a degree of Mn segregation in a specific region is 1.5 or less; a maximum P concentration in a specific region is 0.08 mass % or less; in a specific region, at least one specific MnS particle group is present, the number of specific MnS particle groups is 2.0 or fewer per 1 mm2, and the number of specific oxide-based inclusions is 8 or fewer per 1 mm2; of all oxide-based inclusions, oxide-based inclusions having a specific composition are present in a number ratio of 80% or greater; the microstructure includes, in terms of a volume fraction, 30 to 95% martensite, 5 to 70% ferrite phase, less than 30% (and 0% or greater) bainite, and less than 2.0% (and 0% or greater) austenite phase; and a tensile strength is 980 MPa or greater.

公开(公告)号：US20210238719A1

公开(公告)日：2021-08-05

申请号：US17262975

申请日：2019-06-10

Applicant: JFE Steel Corporation

Inventor： Sota Goto ,  Kazuhiko Yamazaki ,  Thi Huyen Doan ,  Yoshihiko Ono

IPC: C22C38/60 ,  B32B15/01 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/22 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

Abstract: The high-strength hot-rolled coated steel sheet includes a steel sheet having a chemical composition containing, by mass %, C: 0.03% to 0.09%, Si: 0.01% to 1.60%, Mn: 2.20% to 3.60%, P: 0.100% or less, S: 0.0100% or less, Ti: 0.05% to 0.18%, B: 0.0005% to 0.0050%, Al: 0.005% to 0.40%, N: 0.010% or less, and a balance of Fe and inevitable impurities, in which a CSM value expressed by the equation 33.8[% C][% Mn]+12.4[% Si]/[% Mn] is 3.3 to 12.0, and a steel microstructure containing bainite in an amount of 85% or more in terms of area fraction and martensite in an amount of 2.0% or more and 15.0% or less in terms of area fraction and includes a coating layer or an alloyed coating layer on a surface of the steel sheet.

公开(公告)号：US20200377978A1

公开(公告)日：2020-12-03

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

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：US10655201B2

公开(公告)日：2020-05-19

申请号：US15557547

申请日：2016-02-16

Applicant: JFE STEEL CORPORATION

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

IPC: C21D9/46 ,  C22C38/60 ,  C22C38/00 ,  C22C38/46 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58

Abstract: A high-strength, cold-rolled steel sheet having a tensile strength of 980 MPa or more, the steel sheet having a chemical composition containing, by mass %, C: 0.070% to 0.100%, Si: 0.50% to 0.70%, Mn: 2.40% to 2.80%, P: 0.025% or less, S: 0.0020% or less, Al: 0.020% to 0.060%, N: 0.0050% or less, Nb: 0.010% to 0.060%, Ti: 0.010% to 0.030%, B: 0.0005% to 0.0030%, Sb: 0.005% to 0.015%, Ca: 0.0015% or less, Cr: 0.01% to 2.00%, Mo: 0.01% to 1.00%, Ni: 0.01% to 5.00%, Cu: 0.01% to 5.00%, and the balance being Fe and inevitable impurities, a metallurgical microstructure including a ferrite phase in an amount of 30% or more in terms of area fraction, at least one selected from a bainite phase and a martensite phase in an amount of 40% to 65% in total in terms of area fraction, and a cementite in an amount of 5% or less in terms of area fraction at a position located at ¼ of the thickness from the surface of the steel sheet, and a metallurgical microstructure including a ferrite phase in an amount of 40% to 55% in terms of area fraction at a position located at 50 μm in the thickness direction from the surface of the steel sheet and a method for manufacturing the steel sheet.

公开(公告)号：US20200017933A1

公开(公告)日：2020-01-16

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.