One-step pretreatment method of metallic substrates at non-neutral ph values for metal cold forming

A method of pretreatment of a metallic substrate for a subsequent metal cold forming process, said method comprising at least steps (1) and (2) and optionally step (3), namely

• (1) providing at least one substrate having at least one surface at least partially made of at least one metal and/or alloy thereof, wherein said metal and/or alloy thereof is at least one of steel, aluminum and alloys of aluminum and/or steel,
• (2) contacting the at least one surface of the substrate provided in step (1) with an aqueous lubricant composition (B) having a pH value, which is in the non-neutral pH range, wherein the neutral pH range is a pH range of from >6.0 to <8.0,
• wherein the aqueous lubricant composition (B) comprises besides water at least constituents (b1) to (b4) and optionally (b5), which are different from one another, namely
• (b1) at least one film-forming polymer, which is a homopolymer and/or copolymer prepared by polymerization of at least vinyl pyrrolidone as at least one monomer, wherein said homopolymer and/or copolymer has a polydispersity index (PDI) in a range of from 1.5 to 8.0,
• (b2) at least one wax,
• (b3) at least one defoamer,
• (b4) (i) oxalate anions and/or phosphate anions or (ii) calcium cations, chloride anions and hydroxide anions, and
• (b5) optionally Fe(III) ions, wherein constituent (b5) is present in case at least oxalate anions are present as constituent (b4),
• and
• (3) optionally drying the coating film obtained after having performed step (2).