REACTIVE SOLUTION FOR SURFACE TREATMENT AND METHOD FOR TREATING STEEL SHEET USING THE SAME

摘要

PURPOSE: A reactive solution for surface treatment and method for treating steel sheet using the same are provided to improve weldability, processability, adhesiveness of electrostatic painting, corrosion resistance and paintability of panels for automobile uses. CONSTITUTION: The absolute solution for surface treatment essentially consists of Mn 2.9-4.1wt.%, Ni 2.0-4.0wt.%, Cl 1.2-1.4wt.%, Fe 0.5-0.9wt.%, a balance of phosphate, and the mole ratio of (Ca+Mg)/P2O7 ranges from 0.4 to 0.8. The absolute solution, for the application, is diluted to 2.4-5wt.%·absolute solution/L·water. The diluted solution of which temperature is 30-60deg.C is reacted with electrolytic galvanized iron or hot dipped galvanized iron to regulate an amount of diluted solution on above steel sheet to 1.0-2.0g/m¬2. Phosphates formed on the surface treated steel sheet consist of phosphophyllite and hopeite.