(19)
(11) EP 0 260 374 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
06.09.1989 Bulletin 1989/36

(43) Date of publication A2:
23.03.1988 Bulletin 1988/12

(21) Application number: 87104231.3

(22) Date of filing: 23.03.1987
(51) International Patent Classification (IPC)4: C25D 5/12, C25D 11/38
(84) Designated Contracting States:
BE DE FR GB IT LU NL

(30) Priority: 18.09.1986 JP 220521/86

(71) Applicant: NIPPON STEEL CORPORATION
Tokyo 100 (JP)

(72) Inventors:
  • Ezure, Kazuya
    1, Fuji-cho Hirohata-ku Himeju-shi Hyogo (JP)
  • Saito, Takao
    1, Fuji-cho Hirohata-ku Himeju-shi Hyogo (JP)

(74) Representative: Kador & Partner 
Corneliusstrasse 15
80469 München
80469 München (DE)


(56) References cited: : 
   
       


    (54) Process for producing a multilayer-coated strip having excellent corrosion resistance and weldability and useful for containers


    (57) A multilayer-coated steel strip having an excellent corrosion resistance and weldability and useful for cans and containers is produced by a process in which a steel strip substrate is plated with nickel or a nickel-based alloy to form nickel based coating layers each having an average amount of 2 to 10 mg/m2, provided with a number of convex and concave portions thereof, portions of which layers having a coating thickness of 0.001 pm or more have a total area corresponding to 10 to 90% of the entire area of the surfaces of the substrate; the nickel based plated substrate is coated with tin to form tin coating layers on the nickel-based coating layers, each of which tin coating layers has an average amount of 200 to 2000 mg/m2; the resultant precursory coated steel strip is heated at a temperature equal to or higher than the melting point of tin to convert the nickel-based coating layers and the tin coating layers to base coating layers consisting essentially of an Fe-Ni-Sn-based alloy and having a number of convex and concave portions thereof, and intermediate coating layers formed on the base coating layers, consisting essentially of tin and having a number of convex and concave protions thereof; and then an electrolytic chromate treatment is applied onto the intermediate tin coating layers to form surface coating layers consisting of electrolysed chromate.






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