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AssigneeNippon Steel Corporation
InventorsYashichi Oyagi, Takayuki Omori, Masahiro Fuda, Ken Sawada, Nobuyoshi Okada
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This invention provides a rust-proofed steel sheet for a fuel tank including an alloy layer containing at least one of Ni, Fe, Zn and Sn and deposited on the surface of a steel sheet to a thickness of 2 .mu.m per surface, and a Sn--Zn alloy plating layer consisting of 40 to 99 wt % of Sn and the balance of iron, containing not greater than 20 crystals/0.25 mm.sup.2 of zinc crystals having a major diameter of not greater than 250 .mu.m and deposited on the alloy layer to a thickness of 2 to 50 .mu.m per surface. The to-be-plated steel sheet to which the plating layer is applied has a composition consisting of C.ltoreq.0.1%, Si.ltoreq.0.1%, Mn: 0.05 to 1.2%, P.ltoreq.0.040%, Al<0.1% and if necessary, at least one of B, Ti, Nb and Cr, and the balance of Fe and unavoidable impurities. This invention provides also a production method of a rust-proofing steel sheet for a fuel tank comprising the steps of applying Ni--Fe type pre-plating to an annealed steel sheet in a quantity of 0.1 to 3.0 g/m.sup.2 per surface in terms of a Ni content, applying flux containing hydrochloric acid in a quantity of 2 to 45 wt % in terms of chlorine, immersing the steel sheet in a bath consisting of 40 to 99 wt % of Sn and the balance of Zn for less than 15 seconds at a bath temperature of (melting point+20.degree. C.) to (melting point+300.degree. C.) of a plating bath metal, for plating.
A rust-proofing steel sheet for a fuel tank characterized in that an alloy layer containing at least one of nickel, iron, zinc and tin is deposited onto each surface of a steel sheet to a thickness of not greater than 2 .mu.m per surface, and a Sn--Zn alloy plating layer consisting of 40 to 99 wt % of tin and the balance of zinc and containing not greater than 20 crystals/0.25 mm.sup.2 of zinc crystals having a major diameter of at least 250 .mu.m is deposited onto each alloy layer to a thickness of 2 to 50 .mu.m per surface.
A rust-proofing steel sheet for a fuel tank characterized in that an alloy layer containing at least one of nickel, iron, zinc and tin is deposited onto each surface of a steel sheet consisting of C.ltoreq.0.1%, Si.ltoreq.0.1%, 0.05.ltoreq.Mn.ltoreq.1.2%, P.ltoreq.0.04%, Al.ltoreq.0.1% and the balance of iron and unavoidable impurities to a thickness of not greater than 1.5 .mu.m per surface, and a Sn--Zn alloy layer consisting of 40 to 99 wt % of tin and the balance of zinc and containing not greater than 20 crystals/0.25 mm.sup.2 of zinc crystals having a major diameter of at least 250 .mu.m is deposited onto each alloy layer to a thickness of 2 to 50 .mu.m.
A rust-proofing steel sheet for a fuel tank characterized in that an alloy layer containing at least one of nickel, iron, zinc and tin is deposited onto each surfaces of a steel sheet consisting of C.ltoreq.0.1%, Si.ltoreq.0.1%, 0.05.ltoreq.Mn.ltoreq.1.2%, P.ltoreq.0.04%, Al.ltoreq.0.1%, 0.0002 to 0.0030% of B, Ti and/or Nb.ltoreq.1.0% and the balance of iron and unavoidable impurities to a thickness of not greater than 1.5 .mu.m per surface, and a Sn--Zn alloy plating layer consisting of 40 to 99 wt % of tin and the balance of zinc and containing not greater than 20 crystals/0.25 mm.sup.2 of zinc crystals having a major diameter of at least 250 .mu.m is deposited onto each alloy layer to a thickness of 2 to 50 .mu.m.
A rust-proofing steel sheet for a fuel tank characterized in that an alloy layer containing at least one of nickel, iron, zinc and tin is deposited onto each surface of a steel sheet to a thickness of not greater than 2 .mu.m, a Sn--Zn alloy plating layer consisting of 40 to 99 wt % of tin and the balance of zinc and containing not greater than 20 crystals/0.25 mm.sup.2 of zinc crystals having a major diameter of at least 250 .mu.m is deposited onto each alloy layer to a thickness of 2 to 50 .mu.m per surface, and the size of the major diameter of the plating metal crystals is not greater than 20 mm on the outermost surface of each alloy plating layer.
A production method for rust-proofing steel sheet for a fuel tank, comprising the steps of:
A production method for rust-proofing steel sheet for a fuel tank, comprising the steps of:
A production method for rust-proofing steel sheet for a fuel tank comprising the steps of:
Dependencies are inferred from the claim text.