A method for production of a flat steel product including at least the following steps, completed in a continuous process: providing a flat steel product, wherein a protective metal layer of Zn, a Zn—Al alloy, a Zn—Mg alloy or a Zn—Mg—Al alloy is applied to at least one side by hot dip coating; at least partly removing a native oxide layer present on the surface of the protective metal layer by wetting this surface with an acidic solution of sulfuric acid, sulfurous acid, hydrochloric acid, phosphoric acid, phosphonic acid, nitric acid, formic acid, oxalic acid, acetic acid, citric acid, malic acid, tartaric acid, nitrous acid or hydrofluoric acid; activating the surface of the protective metal layer by applying an aqueous activation solution to the surface of the protective metal layer; and phosphating the activated surface of the protective metal layer by applying an aqueous phosphating solution to the activated surface.

Disclosed herein is an aqueous composition having a pH value at 55° C. in the range from 5 to 9, containing at least two different amino organophosphonic acid derivatives of formula (I)

##STR00001##

where residues R independently of each other are CH.sub.2—PO(OR″).sub.2, residues R′ independently of each other are alkylene residues with 2 to 4 carbon atoms, residues R″ independently of each other are H, Na, K, Li or NH.sub.4; and n is an integer from 0 to 4; and where the at least two different amino organophosphonic acid derivatives differ in the value of n. Further disclosed herein is a concentrate to produce such compositions, a pickling method for pickling metallic substrates making use of the compositions, a coating method for coating metallic substrates including the pickling method and a method of using the compositions for pickling metallic substrates.

The present invention is directed towards an aqueous alkaline cleaner composition comprising: an iron cation, a molybdenum cation, a cobalt cation, or combinations thereof; and an alkaline component; wherein the pH of the aqueous alkaline composition is at least 10, and the aqueous alkaline composition includes no more than 50 ppm of phosphate. Also disclosed are treatment systems comprising an aqueous alkaline composition for treating at least a portion of a substrate, and a pretreatment composition for treating at least a portion of a substrate. Also disclosed are substrates treated according to the disclosed treatment systems.

Disclosed herein is a phosphonate-free, aqueous pickling composition having a pH value at 55° C. in the range from 5 to 9, and containing at least one copolymer, which is water-soluble or water-dispersible and selected from the group consisting of polyvinylpyrrolidones; the content of water being in the range from 95.0 wt.-% to 99.9 wt.-% based on the total weight of the composition. Further disclosed herein is a concentrate to produce such compositions, a pickling method for pickling metallic substrates making use of the compositions, a coating method for coating metallic substrates including the pickling method and a method of using the compositions for pickling metallic substrates.

Disclosed herein is an aqueous composition having a pH value at 55° C. in the range from 5 to 9, containing at least one different amino organophosphonic acid derivatives of formula (I)

##STR00001##

where residues R independently of each other are CH.sub.2—PO(OR″).sub.2, residues R′ independently of each other are alkylene residues with 2 to 4 carbon atoms, residues R″ independently of each other are H, Na, K, Li or NH.sub.4; and n is an integer from 0 to 4; and at least one copolymer, which is water-soluble or water-dispersible Further disclosed herein are a concentrate to produce such compositions, a pickling method for pickling metallic substrates making use of the compositions, a coating method for coating metallic substrates including the pickling method and a method of using the compositions for pickling metallic substrates.

Described herein is an alternative acidic, aqueous composition for effectively phosphating metallic surfaces, which includes, besides zinc ions, manganese ions, phosphate ions and, preferably, nickel ions, at least one accelerator of a formula R.sub.1R.sub.2R.sub.3C—NO.sub.2 where each of the substituents R.sub.1, R.sub.2 and R.sub.3 on the carbon atom is selected, independently of the others, from the group consisting of hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-hydroxy-1-methyl ethyl and 2-hydroxy-1-methylethyl. Also described herein are a method for producing such a composition, an alternative method for phosphating metallic surfaces, and a method of using phosphate coatings produced accordingly.

A method for phosphating metal surfaces in a layer-forming manner using a colloidal aqueous solution as an activation stage containing a dispersed particulate constituent, the particulate constituent containing dispersed inorganic compounds of phosphates of polyvalent metal cations; plus polymeric organic compounds as dispersing agents, which are composed at least partially of styrene and/or an α-olefin having no more than 5 carbon atoms and are composed at least partially of maleic acid, its anhydride and/or its imide, the polymeric organic compounds additionally comprising polyoxyalkylene units. In the activation stage of the method according to the invention, the addition of condensed phosphates can be dispensed with such that the content of dissolved condensed phosphates in the colloidal aqueous solution is less than 0.25, based on the phosphate content in the particulate constituent thereof, in each case based on the element P.

The present invention is directed towards an aqueous alkaline cleaner composition comprising: an iron cation, a molybdenum cation, a cobalt cation, or combinations thereof; and an alkaline component; wherein the pH of the aqueous alkaline composition is at least 10, and the aqueous alkaline composition includes no more than 50 ppm of phosphate. Also disclosed are treatment systems comprising an aqueous alkaline composition for treating at least a portion of a substrate, and a pretreatment composition for treating at least a portion of a substrate. Also disclosed are substrates treated according to the disclosed treatment systems.

Disclosed is a system for treating a surface of a multi-metal article. The system includes first and second compositions for contacting at least a portion of the surface. The first composition includes phosphate ions and zinc ions and is substantially free of fluoride. The second composition includes a lanthanide series metal cation and an oxidizing agent. Methods of treating a multi-metal article using the system also are disclosed. Also disclosed are substrates treated with the system and method.

Disclosed herein is an aqueous composition having a pH value at 55 C. in the range from 5 to 9, containing at least one different amino organophosphonic acid derivatives of formula (I) ##STR00001##
where residues R independently of each other are CH.sub.2PO(OR).sub.2, residues R independently of each other are alkylene residues with 2 to 4 carbon atoms, residues R independently of each other are H, Na, K, Li or NH.sub.4; and n is an integer from 0 to 4; and at least one copolymer, which is water-soluble or water-dispersible. Further disclosed herein are a concentrate to produce such compositions, a pickling method for pickling metallic substrates making use of the compositions, a coating method for coating metallic substrates including the pickling method and a method of using the compositions for pickling metallic substrates.