ZN-MG ALLOY PLATED STEEL SHEET EXCELLENT IN CORROSION RESISTANCE AFTER COATING AND CORROSION RESISTANCE AT EXPOSED PART

摘要

PURPOSE: To obtain a plated steel sheet excellent in both corrosion resistance after coating and red rust resistance at the base steel exposed part. ;CONSTITUTION: The concn. of Mg in a Zn-Mg alloy plating layer disposed on the surface of a steel sheet is continuously or stepwise reduced from the interface between the plating layer and the base steel toward the surface of the plating layer. A plating layer may be formed by laminating plural layers different from each other in the concn. of Mg. The interfacial part having a high concn. of Mg has high corrosion preventing action to the base steel and the surface layer part having a low concn. of Mg maintains its sacrificial corrosion preventing action.;COPYRIGHT: (C)1995,JPO