METHOD FOR IMPROVING ADHERENCE.

摘要

The invention relates to a method for improving adherence to a protectively coated steel sheet (2), wherein in a continuous method a protective coating based on Zn-Al-Mg is applied to the steel sheet (2) and, in a further step, is subjected to a surface treatment (6), wherein an aqueous composition (7) is applied in order to modify the natural oxide layer (9) having Al2O3 and MgO without pickling the natural oxide layer. In order to significantly increase adherence to the protectively coated steel sheet, it is proposed that the protectively coated steel sheet (2) is skin-pass rolled and then the natural oxide layer (9) is reacted with an aqueous fluoride-containing composition (7), the MgO content of the natural oxide layer thereby being reduced, in order to thus modify the natural oxide layer (9).