METHOD FOR MAKING A GALVANIZED STEEL SHEET WITH EXCELLANT BRIGHTENING AND WHITENING

摘要

The steel sheet is electroplated under following plating condition, where a plating solution is composed of 0.7-2.0 mol. Zn and 5.0-9.0 mol. Cl, pH of the plating solution is 2.0-5.5, temp. of the plating solution is 40-75 deg.C, flow velocity is 0.5-2.5 m/sec, current density is 30-180 A/dm2, and formaldehydes and ethylene glycol of above respective 0.1 ml are added to the plating solution in a range of total addition amount of below 8.0 ml/l. The plating condition supplies a fine plating structure.