MANUFACTURE OF GALVANIZED STEEL SHEET

摘要

PURPOSE:To inhibit the growth of coarse grains and to form a smooth and white galvanized surface by galvanizing a steel sheet at a high current density in an acidic galvanizing bath contg. nonionic polyacrylamide. CONSTITUTION:An acidic galvanizing bath is prepd. by adding 0.7-2.0mol/l zinc ions and 1-100ppm nonionic polyacrylamide having 10<6>-10<8> average mol.wt. or by further adding 0.1-2.0mol/l Ni or Fe ions. The bath is adjusted to 0.5-2.0pH and 40-70 deg.C. A steel sheet is galvanized in the bath at 100-450A/dm<2> current density and >=30m/min relative flow rate. A galvanized steel sheet obtd. by this method has moderate and uniform surface roughness, and when it is coated with paint, a fine appearance is provided.