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AssigneeBethlehem Steel Corporation
InventorsNeal S. Berke, Herbert E. Townsend
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A coated ferrous article with improved properties, e.g., improved overall corrosion resistance and good appearance. The article has a ferrous substrate and a ductile, adherent, corrosion resistant alloy coating metallurgically bonded to the substrate. The alloy coating has a thin intermetallic alloy layer intermediate the substrate and an alloy overlay. The alloy overlay consists essentially of, by weight, magnesium from 3% to 20%, silicon from 3% to 15%, balance aluminum and zinc, where the ##EQU1## is between 1 and 1.5. The metallurgical structure of the overlay is a mixture of (1) cored aluminum-rich dendrites having dendrite arm spacings (DAS) of less than 10.mu., (2) zinc-rich interdendritic regions, and (3) intermetallic phases of zinc, aluminum, magnesium and silicon. The article may be produced by hot dip coating a ferrous substrate in a molten metal bath of the above composition.
In a corrosion resistant ferrous article comprising a ferrous base rendered corrosion resistant to both SO.sub.2 and salt water-containing environments by a ductile, adherent, coating metallurgically bonded to a surface thereof, said coating having an alloy overlay and an intermetallic alloy layer intermediate said overlay and said ferrous base, the improvement wherein said overlay is an alloy from essentially within the quaternary Al-Zn-Si-Mg system having a metallurgical structure containing (1) cored aluminum-rich dendrites having dendrite arm spacings (DAS) of less than 10.mu., (2) zinc-rich interdendritic regions, and (3) intermetallic phases of zinc, aluminum, magnesium and silicon;
In a method for producing a metallic coating metallurgically bonded to a ferrous base, comprising the steps of (1) preparing a surface of said ferrous base for the reception of a metallic coating;
Dependencies are inferred from the claim text.