PROPERTIES OF NEW CHROMATE-FREE ELECTROGALVANIZED STEEL SHEETS WITH NONRESINOUS COATINGS

摘要

Currently, most of the electrogalvanized steel sheets with chromate-free conversion coated layers (hereinafter called chromate-free electrogalvanized steel sheets) have synthetic resins as main components in their coated layers, instead of chromate treatment layers. However, the resinous coated steel sheets are inferior in some properties to chromate treated steel sheets, such as the poor appearance after press forming under severe condition, and difficulty in reaching electric conductivity good enough to meet clients' requirements with good corrosion resistance through the layer. To solve those problems inherent in the resinous coated steel sheets, we have newly developed a chromate-free electrogalvanized steel sheet with a big reduction of resin components in the coated layer. The new product meets those requirements, and also provides preferable finishing paint adhesion and weldability equivalent to those of the chromate treated products.