公开(公告)号：US20210108282A1

公开(公告)日：2021-04-15

申请号：US17043514

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Kazuki ENDO ,  Yuki TOJI ,  Yoshimasa FUNAKAWA ,  Satoshi MAEDA ,  Mai AOYAMA

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  B32B15/01 ,  C23C2/02 ,  C23C2/28 ,  C23C2/40 ,  C23C2/06

Abstract: A high-strength steel includes a steel structure with: in area fraction, 60.0% to less than 90.0% of ferrite, 0% to less than 5.0% of unrecrystallized ferrite, 2.0% to 25.0% of martensite, 0% to 5.0% of carbide, and 0% to 3.0% of bainite; in volume fraction, more than 7.0% of retained austenite; in a cross-sectional view of 100 μm×100 μm, a value obtained by dividing number of retained austenite that are not adjacent to retained austenite whose crystal orientations are different by a total number of retained austenite being less than 0.80, an average crystal grain size of the ferrite being 6.0 μm or less, an average crystal grain size of the retained austenite being 3.0 μm or less, and a value obtained by dividing, by mass %, an average content of Mn in the retained austenite by an average content of Mn in steel being 1.50 or more.

公开(公告)号：US20230407485A1

公开(公告)日：2023-12-21

申请号：US18251269

申请日：2021-11-05

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke YAMAMOTO ,  Katsutoshi TAKASHIMA ,  Mai AOYAMA ,  Yusuke OKUMURA ,  Tomomi KANAZAWA ,  Katsuya HOSHINO ,  Hiroshi MATSUDA ,  Ei OKUMURA ,  Yoichi MAKIMIZU ,  Masaki KOBA

IPC: C23C28/02 ,  C21D9/46 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D6/00 ,  C22C33/04 ,  C21D8/02 ,  C21D1/74 ,  C25D3/20 ,  C25D5/36

CPC classification number: C23C28/021 ,  C21D9/46 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/002 ,  C22C38/001 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C22C33/04 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D1/74 ,  C21D8/0278 ,  C25D3/20 ,  C25D5/36 ,  C21D2251/02 ,  C23C2/28

Abstract: Provided is an alloyed galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The alloyed galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface exceeding 20.0 g/m2, and an alloyed galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50% at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

公开(公告)号：US20210010101A1

公开(公告)日：2021-01-14

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 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

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：US20220186334A1

公开(公告)日：2022-06-16

申请号：US17433875

申请日：2019-12-10

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki ENDOH ,  Yoshiyasu KAWASAKI ,  Yuki TOJI ,  Yoshimasa FUNAKAWA ,  Mai AOYAMA

IPC: C21D9/46 ,  C21D8/02 ,  B21C47/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/40

Abstract: An object is to provide a high strength steel sheet having a TS (tensile strength) of 980 MPa or more and excellent formability and a method for manufacturing the steel sheet.
A high strength steel sheet which is excellent in terms of formability, which is manufactured under optimized manufacturing conditions, and which has a predetermined chemical composition and a steel microstructure including, in terms of area fraction, 35% or more and 80% or less of ferrite, 5% or more and 35% or less of as-quenched martensite, 0.1% or more and less than 3.0% of tempered martensite, and 8% or more of retained austenite, in which the average grain size of the ferrite is 6 μm or less, in which the average grain size of the retained austenite is 3 μm or less, in which a value calculated by dividing the average Mn content in the retained austenite by the average Mn content in the ferrite is 1.5 or more, in which a value calculated by dividing the sum of the area fraction of as-quenched martensite having a circle-equivalent grain size of 3 μm or more and the area fraction of retained austenite having a circle-equivalent grain size of 3 μm or more by the sum of the area fraction of all the as-quenched martensite and the area fraction of all the retained austenite is less than 0.4, and in which a value calculated by dividing the area fraction of retained austenite grains adjacent to three or more ferrite grains having different crystal orientations by the area fraction of all the retained austenite is less than 0.6.

公开(公告)号：US20170159151A1

公开(公告)日：2017-06-08

申请号：US15323163

申请日：2015-06-15

Applicant: JFE STEEL CORPORATION

Inventor： Mai AOYAMA ,  Yoshitsugu SUZUKI ,  Hideyuki KIMURA

IPC: C21D9/46 ,  B21B3/00 ,  C21D8/02 ,  C23G1/00 ,  C23C2/06 ,  C23C2/40 ,  C23C2/02 ,  C22C38/60 ,  C22C38/38 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  B21B1/22

CPC classification number: C21D9/46 ,  B21B1/22 ,  B21B1/26 ,  B21B1/28 ,  B21B3/00 ,  B21B2001/225 ,  C21D8/0226 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23G1/00

Abstract: A method for manufacturing a high-strength galvanized steel sheet. The method includes a first heating step of holding the steel sheet in a temperature range of 750° C. to 880° C. for 20 s to 600 s in an atmosphere having an H2 concentration of 0.05% to 25.0% by volume and a dew point of −45° C. to −10° C., a cooling step, a rolling step of rolling the steel sheet with a rolling reduction of 0.3% to 2.0%, a pickling step of pickling the steel sheet with a pickling weight loss of 0.02 gram/m2 to 5 gram/m2 in terms of Fe, a second heating step of holding the steel sheet in a temperature range of 720° C. to 860° C. for 20 sec. to 300 sec. in an atmosphere having an H2 concentration of 0.05% to 25.0% by volume and a dew point of −10° C. or lower, and a galvanizing step.

公开(公告)号：US20240009962A1

公开(公告)日：2024-01-11

申请号：US18251244

申请日：2021-11-05

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke YAMAMOTO ,  Yusuke OKUMURA ,  Katsutoshi TAKASHIMA ,  Mai AOYAMA ,  Tomomi KANAZAWA ,  Katsuya HOSHINO ,  Yoichi MAKIMIZU ,  Takashi KAWANO ,  Takako YAMASHITA ,  Hiroshi MATSUDA

IPC: B32B15/01 ,  C22C38/02 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/00 ,  C21D9/46 ,  C22C33/04 ,  C21D8/02 ,  C21D6/00 ,  C22C38/32 ,  C22C38/28 ,  C22C38/38 ,  C25D3/20 ,  C25D5/50 ,  C23F17/00 ,  C23C2/02 ,  C23C2/28 ,  C23C2/06

CPC classification number: B32B15/011 ,  C22C38/02 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/002 ,  C22C38/001 ,  C21D9/46 ,  C22C33/04 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D6/001 ,  C21D6/005 ,  C21D6/008 ,  C22C38/32 ,  C22C38/28 ,  C22C38/38 ,  C21D6/002 ,  C25D3/20 ,  C25D5/50 ,  B32B15/01 ,  C23F17/00 ,  C23C2/02 ,  C23C2/28 ,  C23C2/06

Abstract: To provide an Fe-based electroplated steel sheet that not only has excellent chemical convertibility or excellent coating appearance when subjected to hot-dip galvanizing, but also has excellent resistance to cracking in resistance welding. Disclosed is an Fe-based plated steel sheet including: a cold-rolled steel sheet having a chemical composition containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; and an Fe-based electroplating layer formed on one or both surfaces of the cold-rolled steel sheet with a coating weight per surface of 1.0 g/m2 or more, in which a thickness of an internal oxidation layer is 2.00 μm or less, and an average value of C concentration in a range of 10 μm to 20 μm in a thickness direction from the surface of the Fe-based electroplating layer is 0.10 mass % or less.

公开(公告)号：US20230407506A1

公开(公告)日：2023-12-21

申请号：US18251396

申请日：2021-11-05

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke YAMAMOTO ,  Katsutoshi TAKASHIMA ,  Mai AOYAMA ,  Yusuke OKUMURA ,  Tomomi KANAZAWA ,  Katsuya HOSHINO ,  Hiroshi MATSUDA ,  Ei OKUMURA ,  Yoichi MAKIMIZU ,  Masaki KOBA

IPC: C25D3/20 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/04 ,  C21D8/02 ,  C23C22/78 ,  C25D5/36 ,  C23C28/02

CPC classification number: C25D3/20 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/06 ,  C22C38/04 ,  C21D8/0236 ,  C21D8/0273 ,  C23C22/78 ,  C25D5/36 ,  C23C28/02 ,  C21D2201/05

Abstract: Provided is a steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if the crystal orientations of an Fe-based electroplating layer and a Si-containing cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet. Provided is an Fe-based electroplated steel sheet having a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % or more and 3.0 mass % or less; and an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of more than 20.0 g/m2, where the crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50% at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

公开(公告)号：US20180327884A1

公开(公告)日：2018-11-15

申请号：US15779157

申请日：2016-11-08

Applicant: JFE STEEL CORPORATION

Inventor： Mai AOYAMA ,  Minoru TANAKA ,  Yoshitsugu SUZUKI ,  Yoshiyasu KAWASAKI ,  Hideyuki TAKAHASHI

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

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D1/185 ,  C21D1/76 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0273 ,  C21D8/0278 ,  C21D8/0463 ,  C21D8/0473 ,  C21D9/48 ,  C21D2211/001 ,  C21D2211/005 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/38 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40

Abstract: A high-strength galvanized steel sheet and a method for producing the steel sheet. The steel sheet has a composition that includes C: 0.030% to 0.250%, Si: 0.01% to 3.00%, Mn: 2.00% to 10.00%, P: 0.001% to 0.100%, S: 0.0001% to 0.0200%, N: 0.0005% to 0.0100%, Ti: 0.005% to 0.200%, on a mass basis, and Fe and inevitable impurities. Additionally, the steel sheet has concentration of solute Mn at a depth of 5 μm or less from a surface of the steel sheet that is 1.50% by mass or less, and a value obtained by dividing the average mass percentage of Mn in retained austenite by the average mass percentage of Mn in ferrite is 2.0 or more.

公开(公告)号：US20230407447A1

公开(公告)日：2023-12-21

申请号：US18251422

申请日：2021-11-05

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke YAMAMOTO ,  Katsutoshi TAKASHIMA ,  Mai AOYAMA ,  Yusuke OKUMURA ,  Tomomi KANAZAWA ,  Katsuya HOSHINO ,  Hiroshi MATSUDA ,  Ei OKUMURA ,  Yoichi MAKIMIZU ,  Masaki KOBA

IPC: C23C2/02 ,  C22C33/04 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/00 ,  C21D1/74 ,  C25D5/36 ,  C25D5/48 ,  C25D3/56 ,  C23C2/28 ,  C23C2/40 ,  C23F17/00 ,  C23C28/00

CPC classification number: C23C2/02 ,  C22C33/04 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C21D9/46 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C22C38/002 ,  C22C38/001 ,  C21D1/74 ,  C25D5/36 ,  C25D5/48 ,  C25D3/562 ,  C23C2/28 ,  C23C2/40 ,  C23F17/00 ,  C23C28/34 ,  C23C28/321 ,  C21D2251/02 ,  B23K11/166

Abstract: Provided is a galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of more than 20.0 g/m2, and a galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50 % at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

公开(公告)号：US20210115541A1

公开(公告)日：2021-04-22

申请号：US17042250

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki ENDO ,  Yoshiyasu KAWASAKI ,  Yuki TOJI ,  Yoshimasa FUNAKAWA ,  Mai AOYAMA

IPC: C22C38/04 ,  C22C33/02 ,  B21B27/10 ,  C21D6/00 ,  C21D8/02

Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80%, martensite being 5% to 35%, and tempered martensite being 0% to 5% 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.