Newly Developed Organic-Silicate Composite Coated Steel Sheet with Bake Hardenability

To improve the performance of zinc-rich painted steel sheets, such as Zincrometal®, we at first developed Zn-Ni plated steel sheet with a thin (about 1μm) organic-silicate composite film entirely different from a zinc-rich paint film. This product (EZN-UC) is superior to zinc-rich painted steel sheet in corrosion resistance, anti-powdering property and weldability. This product (EZN-UC), however, is not able to provide bake hardenability due to the high curing temperature of the film. In response to increasing demand for the product with bake hardenability, we have developed new organic-silicate composite coated steel sheet (EZN-UCII), which allows the coating to be cured in the temperature range, where bake hardenability can be maintained. The new product (EZN-UCII) attained higher corrosion resistance than the usual product (EZN-UC) by adopting a new organic-silicate composite, and also provides excellent weldability, anti-powdering property and paint-ability equivalent to the usual product (EZN-UC).