METHOD FOR MANUFACTURING ELECTRO-GALVANIZED STEEL SHEET WITH SUPERIOR SURFACE HARDNESS AND APPEARANCE

摘要

PURPOSE: A method for manufacturing electro-galvanized steel sheet with superior surface hardness and appearance is provided. CONSTITUTION: The method is characterized in that peak current in pulse direction is 300 to 500 A/dm¬2; plating time is 0.1 to 1 msec; peak current in reverse direction is 100 to 165 A/dm¬2; plating time is 0.02 to 0.25 msec; and tetrabutylammonium chloride is added in chloride bath in an amount of 0.5 to 2.5g/L.