公开(公告)号：US20210047716A1

公开(公告)日：2021-02-18

申请号：US17043283

申请日：2018-03-30

Applicant: NIPPON STEEL CORPORATION

Inventor： Kohichi SANO ,  Hiroyuki KAWATA ,  Yuji YAMAGUCHI ,  Satoshi UCHIDA ,  Yoshinori IMAI ,  Riki OKAMOTO

IPC: C22C38/60 ,  B32B15/01 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/58 ,  C22C38/48 ,  C22C38/44 ,  C22C38/14 ,  C22C38/12 ,  C22C38/16 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/08 ,  C23C2/28 ,  C23C2/40 ,  C23C2/06

Abstract: A steel sheet includes a hot-dip galvanized layer or a galvannealed layer on a surface of the steel sheet, the steel sheet including: in mass %, C: 0.06% or more and 0.22% or less; Si: 0.50% or more and 2.00% or less; Mn: 1.50% or more and 2.80% or less; Al: 0.02% or more and 1.00% or less; P: 0.001% or more and 0.100% or less; S: 0.0005% or more and 0.0100% or less; N: 0.0005% or more and 0.0100% or less; and a balance: Fe and impurities.

公开(公告)号：US20200071799A1

公开(公告)日：2020-03-05

申请号：US16466610

申请日：2018-02-20

Applicant: NIPPON STEEL CORPORATION

Inventor： Kengo TAKEDA ,  Riki OKAMOTO ,  Kazuo HIKIDA ,  Katsuya NAKANO ,  Yuya SUZUKI ,  Genki ABUKAWA

IPC: C22C38/04 ,  C22C38/22 ,  C22C38/34 ,  C21D8/02 ,  C21D9/46

Abstract: Steel sheet low in cost and improved in fatigue characteristics without causing a drop in the cold formability, characterized in that it comprises an inner layer and a hard layer on one or both surfaces of the inner layer, a thickness of the hard layer is 20 μm or more and 40% or less of the thickness of the steel sheet, an average micro-Vickers hardness of the hard layer is 240 HV or more and less than 400 HV, an amount of C of the hard layer is 0.4 mass % or less, an amount of N is 0.02 mass % or less, a variation of hardness measured by a nanoindenter at a depth of 10 from the surface of the hard layer is a standard deviation of 2.0 or less, an average micro-Vickers hardness of the inner layer is 80 HV or more and less than 400 HV, a volume rate of carbides contained in the inner layer is less than 2.00%, and the average micro-Vickers hardness of the hard layer is 1.05 times or more the average micro-Vickers hardness of the inner layer.