ZN-P ALLOY ELECTROPLATED STEEL SHEET WITH SUPERIOR CORROSION RESISTANCE

摘要

PURPOSE:To obtain a Zn-P alloy electroplated steel sheet with superior corrosion resistance suitable for use as a material for a car body or the like by incorporating a small amount of Ni, Co, Fe or Cr into a Zn-P alloy layer formed by plating. CONSTITUTION:This Zn-P alloy electroplated steel sheet has a Zn-P alloy layer contg. 0.0003-0.5wt% P and 0.01-5wt% one or more among Ni, Co, Fe and Cr formed by electroplating. Since at least one among Ni, Co, Fe and Cr bonds to P in the layer, a zinc hydroxide film which is very effective in inhibiting a cathodic reaction and an oxygen reducing reaction is liable to be produced. Accordingly, local pitting corrosion is prevented.