ORGANIC COATED STEEL STRIP HAVING IMPROVED BAKE HARDENABILITY AND METHOD FOR MAKING

摘要

An organic coated steel strip having improved bake hardenability is provided which comprises an extra low carbon steel substrate having bake hardenability, a zinc alloy layer deposited on the substrate in a weight of 10 to 40 g/m2, a chromate layer formed on the zinc alloy layer in a weight of at least 10 mg/m2 of metallic chromium, and an organic coating, optionally containing silica, attached to the chromate layer. The coated strip is prepared by depositing a zinc alloy on an extra low carbon steel substrate, subjecting the substrate to a chromate treatment in an aqueous chromate solution containing a chromate compound, a reducing agent, and an acid residue, resin or silica, and applying an organic coating on the chromate layer and baking the coating at a temperature of up to 150.degree.C.