Abstract: The invention relates to a steel substrate coated on at least one of its faces with a metallic coating based on zinc or its alloys wherein the metallic coating is itself coated with a conversion layer comprising: zincsulphate hydrate, aluminium in an amount up to 14 mg·m?2, wherein the conversion layer comprises neither zinc hydroxysulphate, nor free water molecules nor any compounds having free hydroxyl groups, the surface density of sulphur in the conversion layer being greater than or equal to 5.0 mg/m2. The invention also relates to the corresponding treatment method.

Abstract: A steel substrate is provided, coated on at least one of its faces with a metallic coating based on zinc or its alloys wherein the metallic coating is itself coated with a zincsulphate-based layer including at least one of the compounds selected from among zincsulphate monohydrate, zincsulphate tetrahydrate and zincsulphate heptahydrate, wherein the zincsulphate-based layer has neither zinc hydroxysulphate nor free water molecules nor free hydroxyl groups, the surface density of sulphur in the zincsulphate-based layer being greater than or equal to 0.5 mg/m2. A corresponding treatment method is also provided.

Abstract: A steel substrate coated on at least one of its faces with a metallic coating based on zinc or its alloys wherein the metallic coating is itself coated with a zincsulphate-based layer—includes at least one of the compounds selected from among zincsulphate monohydrate, zincsulphate tetrahydrate and zincsulphate heptahydrate, wherein the zincsulphate-based layer has neither zinc hydroxysulphate nor free water molecules nor free hydroxyl groups, the surface density of sulphur in the zincsulphate-based layer being greater than or equal to 0.5 mg/m2. A corresponding treatment method is provided.

Abstract: A coated metal sheet is provided. The coated metal sheet includes a steel substrate, a metal coating on at least one face of the steel substrate, the metal coating comprising at least 40% by weight of zinc; and a layer coating an outer surface of the metal coating, the layer including an amino acid in a neutral or salt form, the amino acid being selected from among alanine, arginine, aspartic acid, cysteine, glutamine, lysine, methionine, proline, serine, threonine, or of a mixture thereof, the amount of said amino acid or of said mixture being from 0.1 to 200 mg/m2, and optionally a base or a mixture of bases, or an acid or a mixture of acids.

Abstract: The invention relates to a method for preparing a metal sheet (1) comprising at least the steps of: providing a steel substrate (3) having two faces (5), for which at least one is coated with a metal coating (7) comprising at least 40% by weight of zinc, applying on the outer surface (15) of the metal coating (7) an aqueous solution comprising an amino acid, and the metal sheet which may be obtained.

Abstract: The invention relates to a method for preparing a metal sheet (1) comprising at least the steps: providing a steel substrate (3) having two faces (5), at least one of which is coated with a metal coating (7) comprising at least 40% by weight of zinc, applying on the outer surface (15) of the metal coating (7) an aqueous solution comprising an amino acid, and the metal sheet which may be obtained.

Abstract: A method for preparing a metal sheet (1) is provided including at least the steps for: providing a steel substrate (3) having two faces (5), at least one of which is coated with a metal coating (7) comprising at least 40% by weight of zinc, applying on the outer surface (15) of the metal coating (7) an aqueous solution comprising an amino acid, and the metal sheet which may be obtained.

Abstract: A steel substrate is provided, coated on at least one of its faces with a metallic coating based on zinc or its alloys wherein the metallic coating is itself coated with a zincsulphate-based layer including at least one of the compounds selected from among zincsulphate monohydrate, zincsulphate tetrahydrate and zincsulphate heptahydrate, wherein the zincsulphate-based layer has neither zinc hydroxysulphate nor free water molecules nor free hydroxyl groups, the surface density of sulphur in the zincsulphate-based layer being greater than or equal to 0.5 mg/m2. A corresponding treatment method is also provided.

Abstract: A steel substrate coated on at least one of its faces with a metallic coating based on zinc or its alloys wherein the metallic coating is itself coated with a zincsulphate-based layer—includes at least one of the compounds selected from among zincsulphate monohydrate, zincsulphate tetrahydrate and zincsulphate heptahydrate, wherein the zincsulphate-based layer has neither zinc hydroxysulphate nor free water molecules nor free hydroxyl groups, the surface density of sulphur in the zincsulphate-based layer being greater than or equal to 0.5 mg/m2. A corresponding treatment method is provided.

Abstract: A coated metal sheet is provided. The coated metal sheet includes a steel substrate, a metal coating on at least one face of the steel substrate, the metal coating comprising at least 40% by weight of zinc; and a layer coating an outer surface of the metal coating, the layer including an amino acid in a neutral or salt form, the amino acid being selected from among alanine, arginine, aspartic acid, cysteine, glutamine, lysine, methionine, proline, serine, threonine, or of a mixture thereof, the amount of said amino acid or of said mixture being from 0.1 to 200 mg/m2, and optionally a base or a mixture of bases, or an acid or a mixture of acids.

Abstract: The invention relates to a method for preparing a metal sheet (1) comprising at least the steps of: providing a steel substrate (3) having two faces (5), for which at least one is coated with a metal coating (7) comprising at least 40% by weight of zinc, applying on the outer surface (15) of the metal coating (7) an aqueous solution comprising an amino acid, and the metal sheet which may be obtained.

Abstract: A method for preparing a metal sheet (1) is provided including at least the steps for: providing a steel substrate (3) having two faces (5), at least one of which is coated with a metal coating (7) comprising at least 40% by weight of zinc, applying on the outer surface (15) of the metal coating (7) an aqueous solution comprising an amino acid, and the metal sheet which may be obtained.

Abstract: The invention relates to a method for preparing a metal sheet (1) comprising at least the steps: providing a steel substrate (3) having two faces (5), at least one of which is coated with a metal coating (7) comprising at least 40% by weight of zinc, applying on the outer surface (15) of the metal coating (7) an aqueous solution comprising an amino acid, and the metal sheet which may be obtained.

Abstract: The invention relates to a method for the carboxylation conversion of a metal surface under oxidizing conditions in relation to the metal, consisting in bringing the metal into contact with a hydro-organic or aqueous bath containing a mixture of organic acids. The invention is characterized in that; the organic acids comprise saturated linear carboxylic acids having between 10 and 18 carbon atoms; the mixture comprises a binary or ternary mixture of such acids; the respective proportions of said acids are such that (i) for a binary mixture x±5%?y±5%, wherein x and y represent the respective proportions, in molar percentages, of the two acids in a mixture with the composition of the eutectic and (ii) for a ternary mixture x±3%?y±3%?z±3%, wherein x, y and z represent the respective proportions, in molar percentages, of the three acids in a mixture with the composition of the eutectic; and the concentration of the mixture in the bath is greater than or equal to 20 g/l.

Abstract: The invention relates to a method for the carboxylation conversion of a metal surface under oxidising conditions in relation to the metal, consisting in bringing the metal into contact with a hydro-organic or aqueous bath containing a mixture of organic acids. The invention is characterised in that; the organic acids comprise saturated linear carboxylic acids having between 10 and 18 carbon atoms; the mixture comprises a binary or ternary mixture of such acids; the respective proportions of said acids are such that (i) for a binary mixture x±5%?y±5%, wherein x and y represent the respective proportions, in molar percentages, of the two acids in a mixture with the composition of the eutectic and (ii) for a ternary mixture x±3%?y±3%?z±3%, wherein x, y and z represent the respective proportions, in molar percentages, of the three acids in a mixture with the composition of the eutectic; and the concentration of the mixture in the bath is greater than or equal to 20 g/l.