Rust preventive carbon steel sheet for fuel tank having good welding gastightness and anticorrosion after forming

Abstract

The present invention provides a hot-dip Al-plated steel sheet for fuel tanks excellent in air-tightness after welding and corrosion resistance subsequent to forming. The present invention provides, as concrete means, a hot-dip Al-plated steel sheet comprising a steel sheet comprising up to 0.003% of C, up to 0.03% of Si, up to 0.3% of Mn, up to 0.02% of P, up to 0.006% of N, up to 0.1% of Ti, Ti and Nb in a total amount of at least the atomic equivalent of (C+N) and up to 0.2%, 1 to 30 ppm of B, and the balance Fe and unavoidable impurities, and a plating layer comprising 2 to 13% of Si, and the balance Al and unavoidable impurities on the surface of the steel sheet, the steel sheet showing a total elongation of at least 45% after plating. Alternately, the hot-dip Al-plated steel sheet may have a chromate coating in an amount of 5 to 100 mg/m on the surface, and it may also have a resin coating on the top surface. As a result, the Al-plated steel sheet is excellent in elongation after Al plating. The Al-plated steel sheet is, therefore, significantly excellent in corrosion resistance subsequent to forming in the internal environment of fuel tanks compared with conventional steel sheets. Accordingly, the Al-plated steel sheet also having excellent air-tightness after welding is most appropriate as a material for fuel tanks of automobiles.