(19)
(11) EP 0 480 355 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
02.09.1992 Bulletin 1992/36

(43) Date of publication A2:
15.04.1992 Bulletin 1992/16

(21) Application number: 91117059.5

(22) Date of filing: 07.10.1991
(51) International Patent Classification (IPC)5C25D 3/56, C23C 28/02
(84) Designated Contracting States:
DE

(30) Priority: 08.10.1990 JP 270171/90

(71) Applicant: NKK CORPORATION
Tokyo (JP)

(72) Inventors:
  • Sagiyama, Masaru, c/o NKK Corporation
    Tokyo (JP)
  • Abe, Masaki, c/o NKK Corporation
    Tokyo (JP)
  • Hiraya, Akira, c/o NKK Corporation
    Tokyo (JP)
  • Inagaki, Junichi, c/o NKK Corporation
    Tokyo (JP)
  • Morita, Masaya, c/o NKK Corporation
    Tokyo (JP)

(74) Representative: Henkel, Feiler, Hänzel & Partner 
Möhlstrasse 37
81675 München
81675 München (DE)


(56) References cited: : 
   
       


    (54) Iron-zinc alloy plated steel sheet having two plating layers and excellent in electropaintability and press-formability


    (57) An iron-zinc alloy plated steel sheet having two plating layers and excellent in electropaintability and press-formability, which comprises; a steel sheet; an alloying-treated iron-zinc alloy dip-plating layer as a lower layer formed on at least one surface of the steel sheet; and an iron-zinc alloy electroplating layer as an upper layer, formed on the iron-zinc alloy dip-plating layer. The iron content in the iron-zinc alloy dip-plating layer is from 7 to 15 wt.%, and the plating weight of the iron-zinc alloy dip-plating layer is from 30 to 120 g/m² per surface of the steel sheet. The iron content in the iron-zinc alloy electroplating layer is at least 60 wt.%. The iron-zinc alloy electroplating layer has a plurality of dots of another iron-zinc alloy; the iron content in each of the plurality of dots of another iron-zinc alloy is under 60 wt.%; the total exposed area per unit area of the plurality of dots of another iron-zinc alloy is from 5 to 50% of the unit area of the iron-zinc alloy electroplating layer; the diameter of each of the plurality of dots of another iron-zinc alloy is from 1 to 100 µm; and the total plating weight of the iron-zinc alloy electroplating layer and the plurality of dots of another iron-zinc alloy is from 1 to 10 g/m² per surface of the steel sheet.





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