TIN-PLATING OR ALUMINUM-PLATING SURFACE TREATED STEEL MATERIAL WITH EXCELLENT CORROSION RESISTANCE

摘要

A surface treated steel product which is prepared by tin-based plating or aluminum-based plating and is excellent in the resistance to corrosion, characterized as containing an intermetallic compound comprising one or more Group IIa (alkaline earth metal) elements and one or more Group IVb elements in a tin-based plating layer or an aluminum-based plating layer thereof. In the case of the tin-based plating layer, the intermetallic compound is preferably present in a massive form having a longer diameter of 1 .mu. or more and a ratio of a shorter diameter to a longer diameter of 0.4 or more, and in the case of the aluminum-based plating layer, the intermetallic compound is preferably present in a massive form having a longer diameter of 10 .mu. or more and a ratio of a shorter diameter to a longer diameter of 0. 4 or more.