1991 Volume 31 Issue 1 Pages 1-10
The history of precoated steel usage as car body materials in Japan is reviewed first. Japanese steelmakers developed galvannealed steel, duplex Zn–Fe coated steel, Zn–Ni coated steel and organic composite coated steel. All of them have been widely used. Recently, electrolytically Fe–Zn plated galvannealed steel and 1μm thick organic painted Zn–Ni electroplated steel have been applied. They have not only excellent corrosion resistance, but also good paintability, formability and weldability. Car body corrosion is classified into cosmetic corrosion and perforation. Newly clarified mechanisms for these two are explained. As for current research subjects, the development of inorganic and organic dispersion coating, Zn–Mn plating, galvannealed steel by vapor deposition, and vapor phase deposited Zn–Mg coating are described. Surface roughness control, application to vibration damping sheet, adhesive bonding, and the adaptation to lightweight cars are also important subjects to be studied now.
