PRODUCTION OF DUPLEX COATED STEEL SHEET EXCELLENT IN IMAGE CLARITY OF COATING AND ELECTRODEPOSITION COATING PROPERTY

摘要

PURPOSE:To improve the image clarity of coating and electrodeposition coating property by applying regulation finish to an alloyed hot dip galvanized steel sheet by the use of prescribed laser dull finished rolls to regulate the rate of smoothness of the plated surface to the prescribed value and then carrying out electric flash plating. CONSTITUTION:The surface of a roll is irradiated with high-density energy beam, by which numerous crator-shaped recessed and projecting parts are formed and the part other than the above parts is formed into a flat part. Further, the plane area ratio of the above flat part is regulated to 70-90%. Subsequently, an alloyed hot dip galvanized steel sheet is subjected to temper rolling at 0.3-5% elongation by using the above laser dull finished rolls, by which the rate of smoothness of the plated surface is regulated to =30%. Then, electric flash plating is applied to the above surface.