公开(公告)号：US12098439B2

公开(公告)日：2024-09-24

申请号：US17915739

申请日：2021-03-25

Applicant: JFE STEEL CORPORATION

Inventor： Lingling Yang ,  Yoshiyasu Kawasaki ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Shunsuke Yamamoto ,  Katsuya Hoshino ,  Yuki Takeda

IPC: C22C38/60 ,  B21C47/02 ,  B32B15/01 ,  B32B15/04 ,  B32B15/18 ,  C21D1/18 ,  C21D1/25 ,  C21D1/76 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/30 ,  C22C38/32 ,  C22C38/34 ,  C22C38/38 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/58 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23C28/00 ,  C23C28/02 ,  C23C30/00

CPC classification number: C21D9/46 ,  B21C47/02 ,  B32B15/013 ,  B32B15/015 ,  B32B15/04 ,  B32B15/043 ,  B32B15/18 ,  C21D1/185 ,  C21D1/25 ,  C21D1/76 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0242 ,  C21D8/0263 ,  C21D8/0273 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/30 ,  C22C38/32 ,  C22C38/34 ,  C22C38/38 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/285 ,  C23C2/29 ,  C23C2/40 ,  C23C28/021 ,  C23C28/025 ,  C23C28/3225 ,  C23C30/00 ,  C23C30/005 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  Y10T428/12458 ,  Y10T428/12792 ,  Y10T428/12958 ,  Y10T428/12965 ,  Y10T428/12972 ,  Y10T428/24942 ,  Y10T428/2495 ,  Y10T428/24967 ,  Y10T428/24983 ,  Y10T428/26 ,  Y10T428/263 ,  Y10T428/264 ,  Y10T428/265

Abstract: A steel sheet having a tensile strength (TS) of 1180 MPa or more, high LME resistance, and good weld fatigue properties. The steel sheet has a specific chemical composition and a specific steel microstructure. Crystal grains containing an oxide of Si and/or Mn in a region within 4.9 μm in a thickness direction from a surface of the steel sheet have an average grain size in the range of 3 to 10 μm, the lowest Si concentration LSi and the lowest Mn concentration LMn in the region within 4.9 μm in the thickness direction from the surface of the steel sheet and a Si concentration TSi and a Mn concentration TMn at a quarter thickness position of the steel sheet satisfy a specified formula.

公开(公告)号：US20240052464A1

公开(公告)日：2024-02-15

申请号：US17766412

申请日：2020-09-25

Applicant: JFE Steel Corporation

Inventor： Yoshiyasu Kawasaki ,  Muneka Iwasawa ,  Yuki Toji ,  Yoshimasa Funakawa

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

CPC classification number: C22C38/04 ,  C22C38/001 ,  C22C38/06 ,  C21D8/0236 ,  C21D8/0273 ,  C21D8/0205 ,  C21D8/0278 ,  C21D2211/005 ,  C21D2211/008 ,  C21D2211/001

Abstract: A high strength steel sheet has a yield-point elongation of 1.0% or greater and a tensile strength of 980 MPa or greater. The high strength steel sheet has a specific chemical composition and microstructure. The ferrite has an average grain size of 5.0 μm or less, the retained austenite has an average grain size of 2.0 μm or less, a value obtained by dividing a Mn content of the retained austenite by a Mn content of steel is 1.50 or greater, 15% or more of all retained austenite grains in the retained austenite have an aspect ratio of 3.0 or greater, and 15% or more of all the retained austenite grains in the retained austenite have an aspect ratio of less than 2.0.

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：US20220364196A1

公开(公告)日：2022-11-17

申请号：US17770118

申请日：2020-10-08

Applicant: JFE Steel Corporation

Inventor： Kazuki Endoh ,  Yoshiyasu Kawasaki ,  Yuki Toji

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

Abstract: Provided is a high strength steel sheet that has a predetermined chemical composition and is manufactured under optimum conditions, the high strength steel sheet having a steel microstructure including, by area, ferrite: 30% or more and 80% or less, tempered martensite: 3.0% or more and 35% or less, and retained austenite: 8% or more, wherein the quotient of the area fraction of grains of the retained austenite, the grains having an aspect ratio of 2.0 or more and a minor axis length of 1 μm or less, divided by the total area fraction of the retained austenite is 0.3 or more, wherein the quotient of the average Mn content (mass %) in the retained austenite divided by the average Mn content (mass %) in the ferrite is 1.5 or more.

公开(公告)号：US11136641B2

公开(公告)日：2021-10-05

申请号：US16064526

申请日：2016-12-08

Applicant: JFE Steel Corporation

Inventor： Satoshi Maeda ,  Yoichi Makimizu ,  Yoshitsugu Suzuki ,  Katsumi Yamada ,  Yoshiyasu Kawasaki

IPC: C21D9/46 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C22C38/06 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/00 ,  B32B15/01 ,  B32B15/18 ,  C21D6/00 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/60 ,  C23C2/02

Abstract: High-strength galvannealed steel sheet including any of a) an oxide containing Fe and Mn, b) an oxide containing Fe and Mn and an Fe oxide, c) an oxide containing Fe and Mn and a Mn oxide, d) an oxide containing Fe and Mn, an Fe oxide, and a Mn oxide, and e) an Fe oxide and a Mn oxide is present in a zinc coated layer. The total amount of oxide is 0.01 to 0.100 g/m2; the ratio by mass % of Mn to Fe, e.g., Mn/Fe, contained in the oxide is 0.10 to 10.00; an oxide of at least one selected from Fe and Mn is present in an amount of 60% or more; and an oxide of at least one selected from Fe and Mn is present in a surface layer portion of a steel sheet in an amount of 0.040 g/m2 or less (not including zero).

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：US10711333B2

公开(公告)日：2020-07-14

申请号：US15516698

申请日：2015-10-29

Applicant: JFE STEEL CORPORATION

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

IPC: C21D9/46 ,  C22C38/14 ,  C23C2/12 ,  C22C38/60 ,  C23C2/02 ,  C22C38/00 ,  C23C2/06 ,  C23C2/28 ,  B32B15/01 ,  B32B15/18 ,  B32B15/20 ,  C21D1/26 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C23C2/40 ,  C23F17/00 ,  C25D3/22

Abstract: Disclosed is a steel sheet having a predetermined chemical composition and a steel microstructure that contains, in area ratio, 15% or more and 55% or less of polygonal ferrite and 15% or more and 30% or less of martensite, and that contains, in volume fraction, 12% or more of retained austenite, in which the polygonal ferrite, the martensite, and the retained austenite have a mean grain size of 4 μm or less, 2 μm or less, and 2 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：US10662495B2

公开(公告)日：2020-05-26

申请号：US15326116

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Kazunori Tahara ,  Takeshi Yokota ,  Kaneharu Okuda ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/00 ,  C22C38/04 ,  C22C38/60 ,  B32B15/01 ,  C21D1/60 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23G1/00

Abstract: Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, stretch flangeability, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, 1-10% of martensite, and 5-15% of tempered 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 %, the retained austenite has a mean free path of 1.2 μm or less, and the tempered martensite has a mean free path of 1.2 μm or less.

公开(公告)号：US09617614B2

公开(公告)日：2017-04-11

申请号：US14351943

申请日：2012-10-17

Applicant: JFE Steel Corporation

Inventor： Hiroshi Hasegawa ,  Yoshiyasu Kawasaki ,  Tatsuya Nakagaito ,  Shinjiro Kaneko ,  Yasunobu Nagataki

IPC: C21D8/02 ,  C21D8/04 ,  C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/34 ,  C22C38/38 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  B32B15/01 ,  C22C38/00

CPC classification number: C21D8/0263 ,  B32B15/013 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0252 ,  C21D8/0436 ,  C21D8/0473 ,  C21D8/0478 ,  C21D9/46 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/34 ,  C22C38/38 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A method of manufacturing a high strength steel sheet having excellent formability suitable for the material of an automotive part has a tensile strength (TS) of 980 MPa or more and total elongation (EL) is 25% or more. A steel slab has a chemical composition containing C: 0.03% to 0.35%, Si: 0.5% to 3.0%, Mn: 3.5% to 10.0%, P: 0.100% or less, S: 0.02% or less, and the remainder includes Fe and incidental impurities on a percent by mass basis is hot-rolled, a heat treatment is performed, in which an achieved temperature of Ac1 to Ac1+100° C. is held for 3 minutes or more, subsequently, cold rolling is performed at a rolling reduction of 20% or more and, annealing is performed, in which an achieved temperature of Ac1−30° C. to Ac1+100° C. is held for 1 minute or more.

公开(公告)号：US20170067131A1

公开(公告)日：2017-03-09

申请号：US15119778

申请日：2015-02-03

Applicant: JFE Steel Corporation

Inventor： Yusuke Fushiwaki ,  Yoshiyasu Kawasaki

IPC: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/16 ,  C22C38/14 ,  C21D6/00 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C25F1/06 ,  C22C38/12

CPC classification number: C21D9/46 ,  C21D1/26 ,  C21D1/76 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0473 ,  C21D9/561 ,  C22C38/00 ,  C22C38/002 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C25F1/06

Abstract: A steel sheet contains, by mass %, 0.03% to 0.35% C, 0.01% to 0.50% Si, 3.6% to 8.0% Mn, 0.01% to 1.0% Al, 0.10% or less P, and 0.010% or less S, the remainder being Fe and inevitable impurities. The steel sheet is continuously annealed, heated at a heating rate of 7° C./s or more in a temperature range corresponding to an annealing furnace inside temperature of 450° C. to A° C. (where 500≦A≦600), the maximum end-point temperature of the steel sheet in an annealing furnace is 600° C. to 700° C., the transit time of the steel sheet in a temperature range corresponding to a steel sheet temperature of 600° C. to 700° C. is 30 seconds to 10 minutes, and the concentration of hydrogen in an atmosphere is 20% by volume or more in a heating step.

Abstract translation: 钢板以质量％计含有0.03％〜0.35％的C，0.01％〜0.50％的Si，3.6％〜8.0％的Mn，0.01％〜1.0％的Al，0.10％以下的P和0.010％以下的S， 余量为Fe和不可避免的杂质。 将钢板连续退火，在450℃〜450℃的退火炉对应的温度范围内以7℃/ s以上的加热速度加热。（500≤A≤600） ，退火炉中的钢板的最终终点温度为600℃〜700℃，钢板在钢板温度为600℃〜700℃的运转时间 ℃为30秒〜10分钟，在加热工序中，气氛中的氢浓度为20体积％以上。