Abstract: A method of increasing the rate of formation of zinc-iron alloy when hot-dip galvanizing a ferrous metal strip to effect complete alloying of the hot-dip zinc coating on at least one side of the strip, wherein a clean ferrous metal strip is provided on at least one lateral surface of the strip with a coating of metallic copper and heating the strip in a non-oxidizing atmosphere to a temperature sufficient to diffuse a portion of the copper coating into the ferrous metal strip (i.e. heating to a temperature between about 724.degree. C. and about 927.degree. C.)and thereafter hot-dip galvanizing the strip. With a very thin hot-dip zinc coating (i.e. having a thickness less than 0.1 mil) no further heating of the strip is necessary in order to provide on at least the one lateral surface a zinc-iron alloy diffusion coating free of unalloyed metallic zinc.

Abstract: A method of continuously producing a one-side-only zinc coated ferrous metal strip initially having zinc coated on both wide surfaces, as by differentially hot-dip coating, and with the zinc on one of the wide surfaces being in the form of a thin film which is transformed into a thin zinc-iron intermetallic layer by applying heat to only the wide surface of the strip having the zinc in the form of a thin film and abrading the surface of the intermetallic layer thus formed by brushing to effect complete removal thereof, leaving the other wide surface of the strip coated with zinc.

Abstract: A ferrous metal strip is continuously hot-dip coated by immersing the metal strip in a hot-dip coating bath containing between about 0.2 wt. percent and about 17 wt. percent aluminum, between about 0.02 wt. percent and about 0.15 wt. percent antimony while excluding lead in amounts more than 0.02 wt. percent, and the balance being essentially zinc. Smooth bright coatings are formed which are highly resistant to intergranular corrosion and blistering when exposed for an extended period to a hot humid atmosphere, have good formability in both the as coated state and after prolonged exposure to a hot humid atmosphere, have a markedly reduced susceptibility to the formation of white rust, and have a reduced rate of general surface corrosion without any diminution of the mechanical properties of the coating.