METHOD FOR COATING FLAT STEEL PRODUCTS WITH A METALLIC PROTECTIVE LAYER, AND FLAT STEEL PRODUCTS COATED WITH A METALLIC PROTECTIVE LAYER

摘要

The invention makes it possible to produce a flat steel product in operationally reliable manner and on an industrial scale that is protected in particularly effective manner against corrosive attacks, process in continuous feed mode, in which the flat steel product is a) provided; b) pickled; c) rinsed with an aqueous medium; d) conveyed through a flux bath that consists of an aqueous solution containing, besides unavoidable contaminants created during production and the process, 210–250 g/l chloride ions, and additionally 140–160 g/l zinc ions, 5–12 g/l ammonium ions or 30–40 g/l potassium ions and optionally in each case also 0.5 - 1.5 g/l sodium ions or calcium ions, and not more than 1 g/l magnesium ions, and traces of ions of the elements Al, Fe, Mn, Mo, Ni, P, Si, Sr and Li, wherein the density of the flux bath is at least 1.25 g/cm3 and at most 1.45 g/cm3, e) dried and warmed up to a bath entry temperature of 100–230 °C, f) hot dip coated in a melt bath, and g) optionally thermal, chemical or mechanical post-treated.