Excellent Seam Weldable Nano-Composite Coated Zn-Ni Plating Steels for Automotive Fuel Tank

Abstract

Steels for automotive fuel tank require unique properties such as corrosion resistance for fuel, weldingfor joining, forming for press, and painting for exterior. Recently, automakers have been requiring excellentseam weldable steels to enhance manufacturing productivity of fuel tank. Thus, POSCO developed a newtype of functional steels coated with nano-composite thin layer on Zn-Ni plating steels. The nano-compositecoating solution was prepared by mechanical fine dispersion of solutions consisting of polymeric resin andnano-composite materials in aqueous media. The composite solution was coated on the plating steel surfaceby using roll coater and cured through induction furnace. These new developed plating steels were evaluatedfor quality performances such as seam and spot weldability, press formability, and corrosion resistance. These new functional steels coated with nano-composite layer exhibited excellent seam weldability andpress formability. Detailed discussion of coating solution and experimental results suggest that nano-sizedcomposite dispersion as coating layer plays a key role in enhancing the quality performance.