Abstract: Disclosed is a hot dip coated steel sheet obtained by hot dipping a steel sheet in a hot-dip metal bath comprising zinc-based or zinc/aluminum based alloy, and a process for producing the same.The hot dip coated steel sheet has a film of oxides which are compounds of cobalt or iron, or both of these, with oxygen, and the film can prevent the hot dip coated steel sheet from undergoing color change into grayish black in the case where spangles are minimized, where a coating contains corrosion resistance-improving elements such as magnesium and aluminum, or where a chromate treatment is applied after the mechanical processings were carried out.Formation of oxide film on the surface of the hot dip coated steel sheet is carried out by a method in which an aqueous solution obtained by dissolving a salt of cobalt or a salt of iron or both of these is sprayed on the surface of a coating of the steel sheet when the temperature of the coating is 170.degree. C. or higher.

Abstract: High nickel/iron alloy steel plate for LNG or LPG tanks having 35-37% nickel content is plated with nickel in an amount of 1 to 10 g/m.sup.2, and then chromated, except electro-chromating treatment, to obtain thereon a chromate film having a chromium content of 5 to 100 mg/m.sup.2.

Abstract: High nickel/iron alloy steel plate for LNG or LPG tanks having 35-37% nickel content is plated with nickel in an amount of 1 to 10 g/m.sup.2, and then chromated, except electro-chromating treatment, to obtain thereon a chromate film having a chromium content of 5 to 100 mg/m.sup.2.