公开(公告)号：US20200270717A1

公开(公告)日：2020-08-27

申请号：US16089846

申请日：2017-01-16

Applicant: JFE STEEL CORPORATION

Inventor： Tatsuya NAKAGAITO ,  Yoshimasa FUNAKAWA ,  Yoshihiko ONO ,  Hiroshi HASEGAWA

IPC: C21D9/46 ,  B32B15/01 ,  C22C38/38 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

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 having a specified chemical composition and a microstructure of 50% or more and 90% or less of martensite, 10% to 50% of ferrite and bainite in total, in terms of an area ratio, and an average concentration of solute Mn in ferrite in a region from a surface of a base steel to a depth of 0.5 μm is 60% or more relative to an average concentration of solute Mn in ferrite at a location of ¼ in the thickness of the steel sheet.

公开(公告)号：US20190112681A1

公开(公告)日：2019-04-18

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

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：US20230120827A1

公开(公告)日：2023-04-20

申请号：US17905827

申请日：2021-03-11

Applicant: JFE STEEL CORPORATION

Inventor： Thihuyen DOAN ,  Sota GOTO ,  Hiroshi HASEGAWA ,  Noriaki MORIYASU ,  Takanori UMINO ,  Takeshi UEDA

IPC: C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C21D8/02 ,  B21C47/02

Abstract: Provided is a high strength steel sheet that has a tensile strength of 1180 MPa or more and a uniform elongation of 6 % or more. The high strength steel sheet has a chemical composition that contains predetermined components with a MSC of 3.0 mass% to 4.2 mass%. The high strength steel sheet has a microstructure including upper bainite in an area fraction of 70 % or more as a main phase, fresh martensite and retained austenite in a total area fraction of 7 % to 30 %, with the retained austenite having an area fraction of 2 % or more. The high strength steel sheet has a mechanical property with a uniform elongation of 6 % or more and a tensile strength of 1180 MPa or more.

公开(公告)号：US20190194775A1

公开(公告)日：2019-06-27

申请号：US16329672

申请日：2017-09-28

Applicant: JFE STEEL CORPORATION

Inventor： Yoshihiko ONO ,  Shimpei YOSHIOKA ,  Nobuyuki NAKAMURA ,  Hiroshi HASEGAWA

IPC: C21D9/46 ,  C23C2/06 ,  C23C2/40 ,  C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/42 ,  C22C38/46 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/44 ,  B32B15/01 ,  C21D8/02 ,  C21D6/00

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/021 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0405 ,  C21D8/041 ,  C21D8/0426 ,  C21D8/0436 ,  C21D8/0473 ,  C21D2211/002 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C23C2/06 ,  C23C2/40

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 more than 90% and 100% or less. The microstructure includes inclusion clusters A and B, the content of the clusters A in the microstructure being 2 clusters/mm2 or less, and the content of the clusters B in the microstructure being 5 clusters/mm2 or less. The microstructure includes carbide particles including Fe as a main constituent which have an aspect ratio of 2.0 or less and a major axis of 0.30 μm or more and 2 μm or less. The content of the carbide particles in the microstructure is 4000 particles/mm2 or less. The microstructure includes prior γ grains having an average size of 6 to 15 μm.

公开(公告)号：US20190040489A1

公开(公告)日：2019-02-07

申请号：US16073905

申请日：2017-01-26

Applicant: JFE STEEL CORPORATION

Inventor： Hiroshi HASEGAWA ,  Yoshimasa FUNAKAWA

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/14 ,  C22C38/12 ,  C22C38/60 ,  C22C38/38 ,  C22C38/24 ,  C22C38/28 ,  C22C38/16 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C23C2/06 ,  C23C2/40 ,  C23C2/26 ,  C23F17/00

Abstract: A high-strength steel sheet for warm working having excellent warm workability, and a method for manufacturing the steel sheet. The steel sheet has a chemical composition including, by mass %, C: 0.05% to 0.20%, Si: 3.0% or less, Mn: 3.5% to 8.0%, P: 0.100% or less, S: 0.02% or less, Al: 0.01% to 3.0%, N: 0.010% or less, one or more selected from Nb: 0.005% to 0.20%, Ti: 0.005% to 0.20%, Mo: 0.005% to 1.0%, and V: 0.005% to 1.0%. The steel sheet has a microstructure including, in terms of area ratio, 10% to 60% of retained austenite, 10% to 80% of ferrite, 10% to 50% of martensite, and 0% to 5% of bainite, in which a C content in the retained austenite is less than 0.40 mass % and the average crystal grain diameter of the retained austenite, the martensite, and the ferrite is 2.0 μm or less.

公开(公告)号：US20190071744A1

公开(公告)日：2019-03-07

申请号：US16089973

申请日：2017-01-17

Applicant: JFE STEEL CORPORATION

Inventor： Hiroshi HASEGAWA ,  Yoshimasa FUNAKAWA

IPC: C21D8/02 ,  C23C2/06 ,  C23C2/02 ,  C23C2/26 ,  C22C38/00 ,  C22C38/06 ,  C22C38/02 ,  C22C38/14 ,  C22C38/12

Abstract: A steel sheet, a plated steel sheet, and methods for producing a hot-rolled steel sheet, a cold-rolled full hard steel sheet, and a steel sheet. The steel sheet has a specified composition and a microstructure including 0 to 60% of polygonal ferrite and 40 to 100% of a total of martensite, bainite, and residual austenite in terms of an area ratio within 20 μm from the steel sheet surface. The content of Mn in martensite present within 20 μm of the steel sheet surface ([Mn]SM) and the content of Mn in a bulk ([Mn]B) satisfy [Mn]SM/[Mn]B≤1.5. At a location 300 μm from the steel sheet surface, an area ratio of the martensite is in a range of 40 to 80%, and the polygonal ferrite and the bainite have an average crystal grain size of less than 15 μm.

公开(公告)号：US20190040511A1

公开(公告)日：2019-02-07

申请号：US16072904

申请日：2017-01-26

Applicant: JFE STEEL CORPORATION

Inventor： Hiroshi HASEGAWA ,  Yoshimasa FUNAKAWA ,  Hiromi YOSHITOMI ,  Yoichi MAKIMIZU ,  Yoshitsugu SUZUKI ,  Gentaro TAKEDA ,  Yoshikazu SUZUKI ,  Yoshimasa HIMEI

IPC: C23C2/02 ,  C22C38/60 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C21D9/46 ,  C23C2/06 ,  C23C2/26 ,  C23C2/40

Abstract: A high-strength galvanized steel sheet having improved post-work impact resistance, a method for producing the high-strength galvanized steel sheet, and a high-strength member produced using the steel sheet. The high-strength galvanized steel sheet includes a steel sheet having a microstructure including ferrite and carbide-free bainite, martensite and carbide-containing bainite, and retained austenite, the total area fraction of ferrite and carbide-free bainite being 0% to 55%, the total area fraction of martensite and carbide-containing bainite being 45% to 100%, and the area fraction of retained austenite being 0% to 5%. Additionally, a galvanizing layer is disposed on the steel sheet. The density of gaps that cut across the entire thickness of the galvanizing layer in a cross section of the galvanizing layer, which is taken in the thickness direction so as to be perpendicular to the rolling direction, is 10 gaps/mm or more.

公开(公告)号：US20180030564A1

公开(公告)日：2018-02-01

申请号：US15543271

申请日：2015-11-24

Applicant: JFE STEEL CORPORATION

Inventor： Hiroshi HASEGAWA ,  Hideyuki KIMURA ,  Yoshimasa FUNAKAWA ,  Yoichi MAKIMIZU ,  Yoshitsugu SUZUKI

IPC: C21D9/46 ,  C22C38/26 ,  C22C38/24 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C21D6/00 ,  C22C38/38

CPC classification number: C21D9/46 ,  B32B15/013 ,  B32B15/04 ,  B32B15/043 ,  B32B15/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0463 ,  C21D8/0473 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/24 ,  C22C38/26 ,  C22C38/38 ,  C22C38/58 ,  C23C2/02 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C23C2/285 ,  C23C2/40 ,  C23C30/00 ,  C23C30/005 ,  Y10T428/12757 ,  Y10T428/12799 ,  Y10T428/12951 ,  Y10T428/12958 ,  Y10T428/12972

Abstract: A high-strength galvanized steel sheet and method for producing the same. The high-strength galvanized steel sheet including a specified chemical composition and a microstructure comprising, in terms of area fraction, a tempered martensite phase: 30% or more and 73% or less, a ferrite phase: 25% or more and 68% or less, a retained austenite phase: 2% or more and 15% or less, and other phases: 10% or less (including 0%), the other phases comprising a martensite phase: 3% or less (including 0%) and a bainitic ferrite phase: less than 5% (including 0%), the tempered martensite phase having an average grain size of 8 μm or less, the ferrite phase having an average grain size of 5 μm or less, and the retained austenite phase having a C content less than 0.7% by mass.

公开(公告)号：US20180002800A1

公开(公告)日：2018-01-04

申请号：US15543062

申请日：2015-11-24

Applicant: JFE STEEL CORPORATION

Inventor： Hiroshi HASEGAWA ,  Hideyuki KIMURA ,  Yoshimasa FUNAKAWA ,  Yoichi MAKIMIZU ,  Yoshitsugu SUZUKI

IPC: C23C2/40 ,  C22C38/04 ,  C21D9/46 ,  C22C38/02 ,  C23C2/28 ,  C22C38/06

CPC classification number: C23C2/40 ,  B32B15/013 ,  B32B15/04 ,  B32B15/043 ,  B32B15/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0273 ,  C21D9/46 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/24 ,  C22C38/26 ,  C22C38/38 ,  C22C38/58 ,  C23C2/02 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C23C2/285 ,  C23C30/00 ,  C23C30/005 ,  Y10T428/12757 ,  Y10T428/12799 ,  Y10T428/12951 ,  Y10T428/12958 ,  Y10T428/12972

Abstract: A high-strength galvanized steel sheet that includes a chemical composition containing, by mass %, C: 0.15% or more and 0.25% or less, Si: 0.50% or more and 2.5% or less, Mn: 2.3% or more and 4.0% or less, P: 0.100% or less, S: 0.02% or less, Al: 0.01% or more and 2.5% or less, and Fe and inevitable impurities. The steel sheet having a microstructure containing, by an area percentage basis, a tempered martensite phase: 30% or more and 73% or less, a ferrite phase: 25% or more and 68% or less, a retained austenite phase: 2% or more and 20% or less, and other phases: 10% or less (including 0%), the other phases containing a martensite phase: 3% or less (including 0%) and a bainitic ferrite phase: less than 5% (including 0%).

公开(公告)号：US20170211164A1

公开(公告)日：2017-07-27

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 ,  B32B15/01 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C21D8/02 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  B21B1/22

CPC classification number: C21D9/46 ,  B21B1/22 ,  B21B2001/221 ,  B21B2001/225 ,  B32B15/013 ,  B32B2255/06 ,  B32B2255/205 ,  B32B2307/536 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  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 ,  C22C38/32 ,  C22C38/38 ,  C22C38/58 ,  C23C2/02 ,  C23C2/06 ,  C23C2/26 ,  C23C2/28

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.