METHOD FOR MANUFACTURING ELECTROLYTIC CHROMATE-TREATED STEEL SHEET

摘要

This method for manufacturing an electrolytic chromate-treated steel sheet is characterized by comprising: a step for sequentially degreasing and pickling a base steel sheet; a step for setting the surface temperature of the base steel sheet to not more than 47°C, and subjecting the base steel sheet to cathodic electrolysis in a high-concentration chromic acid bath containing at least 150 g/L of chromic acid, sulfate ion in a concentration that is from 0.003 times to 0.006 times the concentration of said chromic acid, and a fluorine compound at a current density of not more than 120 A/dm2; a step for immersing the base steel sheet in a less-than-60°C low-concentration chromic acid bath containing from 30 g/L to 60 g/L of chromic acid, and a fluorine compound; and a step for rinsing the base steel sheet with water.