Process for electroplating stainless steel strips with zinc or zinc-nickel alloy

Abstract

An exterior stainless steel sheet is provided comprising a stainless steel substrate and a coating layer formed on one surface of the steel substrate from Al, Al alloy, Zn or Zn alloy to a thickness of 0.1 to 70 .mu.m, preferably 1 to 70 .mu.m. A Zn or Zn-Ni alloy plated stainless steel strip is prepared by degreasing a stainless steel strip, substantially activating the surface of the strip, and electroplating the strip by immersing the strip in a hydrochloric acid solution having a concentration of 0.5 to 40 wt % in a zinc or zinc-nickel alloy plating bath at pH 3.5 or lower. Alternatively, activation may be carried out by cathodic electrolytic treatment in a hydrochloric acid solution having a concentration of 0.5 to 40 wt % at a current density of 0.1 to 100 A/dm. During electroplating of one side, the other side of the strip not to be plated is covered with a protective film. A stainless steel sheet comprising a stainless steel substrate and a coating layer formed on one surface of the steel substrate from Zn or Zn alloy to a thickness of 0.1 to 50 .mu.m, preferably 1 to 50 .mu.m is useful in preparing welded pipes.

Dependencies are inferred from the claim text.