| 摘要 |
PURPOSE:To carry out the above mentioned hot dipping at low costs, by carrying out metal hot dipping on plating surface of steel sheet applied alkali or alkali earth metal ion on non-plating surface and removing oxides of the non-plating surface by acid after cooling in the atmosphere. CONSTITUTION:Water solution of each salt of formic acid, nitric acid or nitrous acid etc. of one or both of more than one kind of alkali metal, such as Na, K, Li and more than one kind of alkali earth metal, such as Ca, Mg, Ba, is applied on non-plating face of steel sheet and applying quantity of the metal ion is made 10mg/ m<2>-10g/m<2>. Plating is carried out contacting hot dipping metal with plating face of the steel sheet. The sheet carried from the plating room, is cooled in the atmosphere and on this occasion, iron oxide is produced on the non-plating face. The above oxide is easily removed at 50 deg.C or under by sulfuric acid, hydrochloric acid etc. of 5% concentration or under, because adhesive strength with the sheet itself is lowered by applied metal ion. |
