PRESERVATIVE STEEL PLATE HAVING HIGH RESISTANCE WELDABILITY, CORROSION RESISTANCE AND PRESS FORMABILITY FOR AUTOMOBILE FUEL TANKS

摘要

A preservative steel plate including (a) a steel plate, (b) an aluminum plating layer formed on one or both sides of the steel plate and using aluminum or an aluminum alloy containing 2-15 wt.% of silicon, and (c) a coating layer formed on at least one aluminum plating layer mentioned above. The aluminum plating layer is one of i) a resin chromate film of 0.1-2 mu m in thickness containing a resin and a chromate and having a resin/metallic chromium weight ratio of 0.5-18; ii) an inorganic chromate film the amount of which is 10-200 mg/m<2> in terms of metallic chromium, containing 100 parts by weight of chromate in terms of metallic chromium and 100-1000 parts by weight of colloidal silica in terms of metallic chromium, and one or more of 100-600 parts by weight of phosphate, 10-200 parts by weight of phosphonate and less than 50 parts by weight of resin; iii) an inorganic chromate film the amount of which is not less than 10 mg/m<2> and less than 35 mg/m<2> in terms of metallic chromium. The aluminum-plated steel plate is suitable for fuel tanks. An automobile fuel tank having high durability, formability and weldability, and a fuel tank seam welding method are also disclosed.