Abstract: The present invention relates to galvanized steel having a high aluminum content in the coating, as well as a batch hot-dip galvanization process for making such steel. The galvanized steel herein has a coating comprising an inner layer of intermetallic iron aluminum compounds, such as Fe2Al5 (which may have some zinc present), and an outer layer of intermetallic zinc aluminum compounds containing from about 17% to about 40% (preferably about 22%, the Zn—Al eutectoid) aluminum (which may have some iron present). The batch hot-dip galvanization process for making such steel comprises: (a) fluxing the steel by electroless plating on the surface of the steel of a metal such as tin, copper or nickel; and (b) dipping the fluxed steel into a molten galvanization bath comprising zinc and from about 17% to about 40% aluminum.

Abstract: The present invention relates to galvanized steel having a high aluminum content in the coating, as well as a batch hot-dip galvanization process for making such steel. The galvanized steel herein has a coating comprising an inner layer of intermetallic iron aluminum compounds, such as Fe2Al5 (which may have some zinc present), and an outer layer of intermetallic zinc aluminum compounds containing from about 17% to about 40% (preferably about 22%, the Zn—Al eutectoid) aluminum (which may have some iron present). The batch hot-dip galvanization process for making such steel comprises: (a) fluxing the steel by electroless plating on the surface of the steel of a metal such as tin, copper or nickel; and (b) dipping the fluxed steel into a molten galvanization bath comprising zinc and from about 17% to about 40% aluminum.

Abstract: An improved fluxing method for the galvanization of steel, particularly batch galvanization, is disclosed. In this process, a metallic element is deposited (for example, by electroless plating) on the surface of the steel sheet or other article prior to its being dipped in the galvanization bath. Preferred metals for use in this fluxing process are tin, copper, nickel, with tin being more preferred, and mixtures of copper and tin being most preferred. This metallic film layer has a thickness between about 5 and about 50 nm. The process of the present invention provides a number of benefits when compared to conventional fluxing processes: for example, it is compatible with the inclusion of aluminum in the galvanization bath; it permits a greater time delay between the fluxing and galvanization operations; and it eliminates the formation of hydrogen chloride or other toxic fumes when the fluxed article is dipped in the molten zinc galvanization bath.