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AssigneesDaido Steel Sheet Corporation, S-Tem Ltd.
InventorsMasanori Takeda, Youichiro Suzuki, Kunio Hayakawa
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An Al-Zn-Si base alloy coat including an Al-Zn-Si-Fe alloy layer which has remarkable high corrosion resistance is formed on an article. A ferrous base material is used as the article to provide Fe to the alloy layer. The alloy layer of the present invention consists of 55 to 65 wt % of Al, 25 to 35 wt % of Zn, 5 to 10 wt % of Fe, and 2 to 4 wt % of Si, and also has a cross sectional area of 15 to 90% of the entire cross sectional area of the alloy coat. A process for forming the alloy coat of the present invention comprises the step of dipping the article into a molten bath of Zn to form, on the article, an undercoat which results from a reaction between Fe of the article and Zn in the molten bath, and then dipping the undercoat into an alloy molten bath of Al, Zn and Si to form the alloy coat of the present invention on the undercoat.
A process for making an alloy-coated, ferrous-based article which consists essentially of a) dipping the article into a first bath of molten Zn to form an undercoat comprising Fe and Zn, b) removing the undercoated article from the first bath, c) dipping the undercoated article into a second bath consisting essentially of 20 to 70 wt % of molten Al, from 0.5 up to 4 wt % of Si and the balance Zn, to form an outer coating consisting essentially of Al, Zn, Fe and Si on the undercoating, and d) removing the alloy-coated article from the second bath.
A process for making an alloy-coated, ferrous-based article which consists essentially of a) dipping the article into a first bath of molten Zn to form an undercoat comprising Fe, Zn and at least one metal selected from the group consisting of Al, Ni, Mg, Ti and Si, b) removing the undercoated article from the first bath, c) dipping the undercoated article into a second bath consisting essentially of 20 to 70 wt % of molten Al, from 0.5 up to 4 wt % of Si and the balance Zn, to form an outer coating consisting essentially of Al, Zn, Fe and Si on the undercoating, and d) removing the alloy-coated article from the second bath.
Dependencies are inferred from the claim text.