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

A fuel tank fabricated from an aluminum plated steel sheet excellent in air-tightness after welding and corrosion resistance subsequent to forming, said aluminum plated steel sheet comprising:

• an iron based steel sheet consisting of iron and, in terms of % by weight, up to 0.01% of C, up to 0.2% of Si, less than 0.6% of Mn, up to 0.04% of P, up to 0.1% of soluble Al, up to 0.01% of N, at least one or both of Ti and Nb in a total amount of at least the atomic equivalent of (C+N) and up to 0.2%, 0.0003 to 0.0030% of B, and at least one element selected from the group consisting of 0.05 to 0.5% of Cu, 0.05 to 0.5% of Ni, and 0.05 to 0.5% of Mo, and,
• an aluminum based plating layer on the surface of the steel sheet consisting essentially of aluminum and 2 to 13% of Si in terms of % by weight.

A fuel tank fabricated from an aluminum plated steel sheet excellent in air-tightness after welding and corrosion resistance subsequent to forming, said aluminum plated steel sheet comprising:

• an iron based steel sheet consisting of iron and, in terms of % by weight, up to 0.003% of C, up to 0.1% of Si, up to 0.4% of Mn, up to 0.02% of P, up to 0.1% of soluble Al, up to 0.01% of N, at least one of Ti and Nb in a total amount of at least the atomic equivalent of (C+N) and up to 0.2%, 0.0003 to 0.0030% of B, and at least one element selected from the group consisting of 0.05 to 0.5% of Cu, 0.05 to 0.5% of Ni, and 0.05 to 0.5% of Mo, and,
• an aluminum based plating layer on the surface of the steel sheet consisting essentially of aluminum and 2 to 13% of Si in terms of % by weight.

A fuel tank fabricated from an aluminum plated steel sheet excellent in air-tightness after welding and corrosion resistance subsequent to forming, said aluminum plated steel sheet comprising:

• an iron based steel sheet consisting of iron and, in terms of % by weight, 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 soluble N, and up to 0.1% of Ti, and,
• an aluminum based plating layer on the surface of the steel sheet consisting essentially of aluminum and 2 to 13% of Si in terms of % by weight,
• the steel sheet showing a total elongation of at least 45% after plating.

A fuel tank fabricated from an aluminum plated steel sheet excellent in air-tightness after welding and corrosion resistance subsequent to forming, said aluminum plated steel sheet comprising:

• an iron based steel sheet consisting of iron and, in terms of % by weight, 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 soluble N, up to 0.1% of Ti, and at least one element selected from the group consisting of 0.05 to 0.5% of Cu, 0.05 to 0.5% of Ni, and 0.05 to 0.5% of Mo, and,
• an aluminum based plating layer on the surface of the steel sheet consisting essentially of aluminum and 2 to 13% of Si in terms of % by weight,
• the steel sheet showing a total elongation of at least 45% after plating.

A fuel tank fabricated from an aluminum plated steel sheet excellent in air-tightness after welding and corrosion resistance subsequent to forming;

• said aluminum plated steel sheet comprising an iron based steel sheet consisting of iron and, in terms of % by weight, up to 0.01% of C, up to 0.2% of Si, less than 0.6% of Mn, up to 0.04% of P, up to 0.1% of soluble Al, up to 0.01% of N, at least one of Ti and Nb in a total amount of at least the atomic equivalent of (C+N) and up to 0.2%, 0.0001 to 0.0030% of B, and at least one element selected from the group consisting of 0.05 to 0.5% of Cu, 0.05 to 0.5% of Ni, and 0.05 to 0.5% of Mo;
• an Al-Fe-Si intermetallic compound layer disposed on said steel sheet substrate and an aluminum based plating layer consisting essentially of Al and Si, and unavoidable impurities, disposed on the intermetallic compound layer, the difference between the immersion potential of the steel sheet substrate for plating and that of the intermetallic compound layer in a solution comprising 100 ppm of formic acid and the balance water and unavoidable impurities being up to 0.35 V.