Tin-plating or aluminium-plating surface treated steel material with excellent corrosion resistance

摘要

A tin-plating or aluminium-plating surface treated steel material with excellent corrosion resistance, containing an intermetallic compound composed of one or more Group IIa (alkaline earth metal) elements and one or more Group IVb elements in a tin-based plating layer or aluminium-based plating layer on the surface of a steel material. For a tin-based plating layer, the long diameter of the intermetallic compound massive bodies is 1 ìm or greater and the short diameter/long diameter ratio is at least 0.4ìm. For an aluminum-based plating layer, the long diameter of the intermetallic compound massive bodies is 10 ìm or greater and the short diameter/long diameter ratio is at least 0.4 ìm.