Organic composite coated steel plates having improved corrosion resistance in as-worked state

An organic composite coated steel plate having improved corrosion resistance in an as-worked state that comprises:

• a steel plate substrate;
• a plating layer positioned in contact with said substrate, said plating layer being selected from the group consisting of zinc and zinc alloy;
• a chromate film positioned in contact with said plating layer, said chromate film having a Cr.sup.6+ content which is up to but no more than 70% of the total chromium content of said film, said chromate film being present in an amount of 5-500 mg/m.sup.2 in terms of metallic chromium;
• an aqueous resin layer comprising water-dispersed silica and anionic aqueous resin, which layer is positioned in contact with said chromate film, and which is deposited in an amount of 0.1-3 g/m.sup.2 on a dry weight basis, said resin layer comprising a non-gelled mixture of a water-dispersed silica and an anionic aqueous urethane resin, said water-dispersed silica comprising a dispersion of negatively-charged particles, whereby said resin layer possesses a structure resulting from repulsion between said negatively-charged particles and said anionic aqueous urethane resin, the proportion on a dry weight basis of the silica and the urethane resin in the resin layer being 10-60 parts by weight silica per 100 parts by weight urethane resin.