公开(公告)号：US11230744B2

公开(公告)日：2022-01-25

申请号：US16089051

申请日：2017-01-16

Applicant: JFE STEEL CORPORATION

Inventor： Tatsuya Nakagaito ,  Yoshimasa Funakawa ,  Yoshihiko Ono ,  Hiroshi Hasegawa

IPC: C21D8/02 ,  C22C38/04 ,  C22C38/02 ,  C22C38/06 ,  C22C38/00 ,  C22C38/12 ,  C22C38/14 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C21D9/46 ,  C22C38/60 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C22C18/00 ,  C22C18/04 ,  C22C38/22 ,  C22C38/24

Abstract: A steel sheet having excellent fatigue resistance as a material for automobile parts and a TS of 590 MPa or more, and a method for producing the same. The steel sheet has a composition comprising, by mass %, C: 0.04% or more and 0.15% or less, Si: 0.3% or less, Mn: 1.0% or more and 2.6% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.01% or more and 0.1% or less, N: 0.015% or less, one or two of Ti and Nb: 0.01% or more and 0.2% or less in a total, and the balance being Fe and unavoidable impurities. The steel sheet has 50% or more of ferrite and 10% or more and 50% or less of martensite in terms of an area ratio, and a microstructure in which a standard deviation of nano-hardness is 1.50 GPa or less and tensile strength of 590 MPa or more.

公开(公告)号：US20210381085A1

公开(公告)日：2021-12-09

申请号：US17284933

申请日：2019-08-06

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Yoshihiko Ono

IPC: C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C21D8/02 ,  C25D5/36 ,  C21D9/46

Abstract: A high-yield-ratio high-strength electrogalvanized steel sheet having an electrogalvanized coating layer formed on a surface of a base steel sheet, in which the base steel sheet has a certain chemical composition, and a steel microstructure, in which a total area fraction of one or both of bainite containing carbides having an average grain diameter of 50 nm or less and tempered martensite containing carbides having an average grain diameter of 50 nm or less is 90% or more in the whole of the steel microstructure, and in which a total area fraction of one or both of the bainite containing and the tempered martensite containing carbides is 80% or more in a region from the surface of the base steel sheet to a position located at ⅛ of a thickness of the base steel sheet, and diffusible hydrogen in steel in an amount of 0.20 mass ppm or less.

公开(公告)号：US20210310094A1

公开(公告)日：2021-10-07

申请号：US17269326

申请日：2019-06-10

Applicant: JFE Steel Corporation

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

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

Abstract: The high-strength steel sheet according to the present invention includes a specific chemical composition, a steel structure in which a total area fraction of martensite and bainite in a position of ¼ of a sheet thickness is 92% or more and 100% or less, the balance in a case where the total area fraction is not 100% contains retained austenite, and an area fraction of ferrite in a region extending up to 10 μm in a sheet thickness direction from a surface is 10% or more and 40% or less, in which a tensile strength is 1320 MPa or more, and a Vickers hardness in a position of 15 μm in the sheet thickness direction from the surface satisfies a specified formula.

公开(公告)号：US10961601B2

公开(公告)日：2021-03-30

申请号：US16089162

申请日：2017-01-23

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yoshimasa Funakawa

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

Abstract: A steel sheet has a composition comprising, in mass %, C: 0.0008 to 0.0024%, Si: less than 0.15%, Mn: more than 0.55% and less than 0.90%, P: more than 0.025% and less than 0.050%, S: 0.015% or less, sol. Al: 0.01% or more and 0.1% or less, N: 0.01% or less, B: more than 0.0003% and less than 0.0035%, Nb: more than 0.005% and less than 0.016%, Ti: 0.009% or less, and Sb: 0.002 to 0.030%, in which C and Nb satisfy the following formula (1), and the balance is Fe and unavoidable impurities, and in which a ds/d ratio of an average crystal grain diameter, at a ¼ thickness position of the sheet (d), to that at a steel sheet surface layer (ds), is 0.40 to 1.20, where d is 8 to 18 μm, and where −10≤([% C]−([% Nb]/93)×12)×10,000≤14.  Formula (1)

公开(公告)号：US20200299798A1

公开(公告)日：2020-09-24

申请号：US16089162

申请日：2017-01-23

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yoshimasa Funakawa

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

Abstract: A steel sheet has a composition comprising, in mass %, C: 0.0008 to 0.0024%, Si: less than 0.15%, Mn: more than 0.55% and less than 0.90%, P: more than 0.025% and less than 0.050%, S: 0.015% or less, sol. Al: 0.01% or more and 0.1% or less, N: 0.01% or less, B: more than 0.0003% and less than 0.0035%, Nb: more than 0.005% and less than 0.016%, Ti: 0.009% or less, and Sb: 0.002 to 0.030%, in which C and Nb satisfy the following formula (1), and the balance is Fe and unavoidable impurities, and in which a ds/d ratio of an average crystal grain diameter, at a ¼ thickness position of the sheet (d), to that at a steel sheet surface layer (ds), is 0.40 to 1.20, where d is 8 to 18 μm, and where −10≤([% C]−([% Nb]/93)×12)×10,000≤14.  Formula (1)

公开(公告)号：US10760142B2

公开(公告)日：2020-09-01

申请号：US15542203

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 ,  C22C38/14 ,  C22C38/60 ,  C22C38/00 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38

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, 30% or more of a ferrite phase, 40% to 65% 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 40% to 55% and the total area ratio of a bainite phase having a grain diameter of more than 5 μm and/or a martensite phase having a grain diameter of more than 5 μm is 20% or less, and a tensile strength is 980 MPa or more.

公开(公告)号：US20190040490A1

公开(公告)日：2019-02-07

申请号：US16077266

申请日：2017-02-15

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Yusuke Kimata ,  Hiroyuki Masuoka

IPC: C21D9/46 ,  C22C38/20 ,  C22C38/16 ,  C22C38/14 ,  C22C38/60 ,  C22C38/12 ,  C22C38/10 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00

Abstract: Provided is a high-strength cold-rolled steel sheet has a chemical composition containing, by mass %, C: 0.10% or more and 0.6% or less, Si: 1.0% or more and 3.0% or less, Mn: more than 2.5% and 10.0% or less, P: 0.05% or less, S: 0.02% or less, Al: 0.01% or more and 1.5% or less, N: 0.005% or less, Cu: 0.05% or more and 0.50% or less, and the balance being Fe and inevitable impurities, and a tensile strength of 1180 MPa or more, in which a steel sheet surface coverage of oxides mainly containing Si is 1% or less, a steel sheet surface coverage of iron-based oxides is 40% or less, CuS/CuB is 4.0 or less, and a tensile strength is 1180 MPa or more, where CuS denotes a Cu concentration in a surface layer of a steel sheet and CUB denotes a Cu concentration in base steel.

公开(公告)号：US20190017156A1

公开(公告)日：2019-01-17

申请号：US16065867

申请日：2016-12-26

Applicant: JFE Steel Corporation

Inventor： Kenji Kawamura ,  Yoshihiko Ono ,  Nobusuke Kariya ,  Shinichi Furuya ,  Kohei Hasegawa

IPC: C22C38/60 ,  C22C38/00 ,  C22C38/08 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/06 ,  C22C38/04 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/02 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40 ,  C21C7/10 ,  C21D9/46 ,  C21D8/02

Abstract: Provided are a high-strength steel sheet having a specified chemical composition, in which a Mn-segregation degree in a region within 100 μm from a surface thereof in a thickness direction is 1.5 or less, in a plane parallel to the surface of the steel sheet in a region within 100 μm from the surface of the steel sheet in the thickness direction, the number of oxide-based inclusion grains having a grain long diameter of 5 μm or more is 1000 or less/100 mm2, a proportion of the number of oxide-based inclusion grains having a chemical composition containing alumina of 50 mass % or more, silica of 20 mass % or less, and calcia of 40 mass % or less to the total number of oxide-based inclusions having a grain long diameter of 5 μm or more is 80% or more, a specified metallographic structure, and a TS of 980 MPa or more, a high-strength galvanized steel sheet, and a manufacturing method thereof.

公开(公告)号：US09297060B2

公开(公告)日：2016-03-29

申请号：US14104451

申请日：2013-12-12

Applicant: JFE STEEL CORPORATION

Inventor： Yoshihiko Ono ,  Kenji Takahashi ,  Kaneharu Okuda ,  Shoichiro Taira

IPC: C23C2/40 ,  C21D6/00 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/18 ,  C22C38/22 ,  C22C38/28 ,  C22C38/32 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28

CPC classification number: C23C2/40 ,  C21D6/00 ,  C21D9/46 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/18 ,  C22C38/22 ,  C22C38/28 ,  C22C38/32 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  Y10T428/12799 ,  Y10T428/12972

Abstract: The high strength galvanized steel sheet contains C: more than 0.015% and lower than 0.100%, Si: 0.3% or lower, Mn: lower than 1.90%, P: 0.015% or more and 0.05% or lower, S: 0.03% or lower, sol.Al: 0.01% or more and 0.5% or lower, N: 0.005% or lower, Cr: lower than 0.30%, B: 0.0003% or more and 0.005% or lower, and Ti: lower than 0.014% in terms of mass %, and satisfies 2.2≦[Mneq]≦3.1 and 0.42≦8[% P]+150B*≦0.73. The steel microstructure contains ferrite and a second phase, in which the second phase area ratio is 3 to 15%, the ratio of the area ratio of martensite and retained γ to the second phase area ratio is more than 70%, and 50% or more of the area ratio of the second phase exists in the grain boundary triple point.

Abstract translation: 高强度镀锌钢板含有C：大于0.015％且低于0.100％，Si：0.3％以下，Mn：低于1.90％，P：0.015％以上0.05％以下，S：0.03％以下 较低，sol.Al：0.01％以上且0.5％以下，N：0.005％以下，Cr：0.30以下，B：0.0003％以上且0.005％以下，Ti：低于0.014％ 质量％，满足2.2＆nlE; [Mneq]＆nlE; 3.1和0.42＆nlE; 8 [％P] + 150B *＆nlE; 0.73。 钢微结构含有铁素体和第二相，其中第二相面积比为3〜15％，马氏体与残留γ的面积比与第二相面积比的比例为70％以上，50％以下 在晶界三点存在更多的第二相面积比。

公开(公告)号：US20140102596A1

公开(公告)日：2014-04-17

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

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: 制造高强度冷轧钢板的方法包括在退火温度为750℃至830℃的条件下对钢板进行热轧和冷轧。 在退火温度至480℃的温度范围内以3℃/秒至40℃/秒的平均冷却速度对钢板进行第一次冷却; 在由式（6）给出的480℃至Tc（℃）的温度范围内以8℃/秒至80℃/秒的平均冷却速率对钢板进行第二次冷却：Tc = 435-40×[％Mn] -30×[％Cr] -30×[％V]（6）其中[％A]为合金元素A的含量（质量％）; 在Tc（℃）〜200℃的温度范围内以0.3℃/秒〜30℃/秒的平均冷却速度对钢板进行第3次冷却。