Patent ID: 6677053
Filing Date: 2004-01-13
Classification: C23C,Y10S,Y10T

Abstract:
A surface-treated steel sheet comprising:a steel sheet; an Alâ€”Zn-base alloy plating layer formed on said steel sheet; a chemical conversion film provided on said alloy plating layer; a concentric layer of a Cr compound that is formed on said alloy plating layer of said chemical conversion film; said alloy plating layer containing Al in an amount of from 20 to 75%; said chemical conversion film being formed by applying a chemical treatment liquid comprising principal components of an aqueous organic resin and chromic acid, the chemical conversion film having a weight ratio of resin/Cr in a range of from 20 to 200, and a coating weight of the Cr in a range of from 3 to 50 mg/m2 (as converted to metallic chromium); and said concentric layer containing a Cr compound in a ratio of resin/Cr that is below 0.8 times a mean ratio of resin/Cr in the chemical conversion film.