PRODUCTION OF STEEL SHEET ELECTROPLATED WITH LEAD/TIN-BASED ALLOY ON SINGLE SIDE HAVING IRON SURFACE EXCELLENT IN PHOSPHATE TREATABILITY AND COATING PROPERTY

摘要

PURPOSE:To produce a steel sheet electroplated on the single side which has iron surface excellent in phosphate treatability and coating properties by performing specified anodically electrolytic treatment for the steel sheet electroplated with lead/tin-based alloy on the single side in an aq. soln. incorporating the specified amount of citric acid and resorcin, etc. CONSTITUTION:Cathodically electrolytic treatment is performed by conducting electricity from an electrode opposite to the single side of steel strip in an aq. soln. incorporating Pb+2 and Sn+2 as a main component. After the steel sheet electroplated with lead/tin-based alloy on the single side obtained thereby is washed with water, anodically electrolytic treatment is performed. This treatment is performed in an aq. soln. wherein 0.01-10g/l one or two kinds of resorcin and hydroquinone is furthermore added to a bath incorporating 5-200g/l one or more kinds selected from among citric acid, tartaric acid, acetic acid, formic acid and/or salt thereof at 0.1-30A/dm2 for 0.5-30 seconds. Furthermore mechanical polishing or grinding is performed on the unplated face in accordance with necessity. Thereby deposit on the iron surface is removed without dissolving and damaging the plated face and the steel sheet electroplated with lead/tin-based alloy on the single side which has the iron surface excellent in phosphate treatability and coating properties is obtained.