Flat steel product having an improved zinc coating

A flat steel product, comprising:

• a steel substrate;
• and
• an anticorrosion coating at least on one side of the steel substrate, wherein the anticorrosion coating is made of zinc or a zinc alloy and comprises nanocrystals on a surface remote from the steel substrate, wherein an average diameter of the nanocrystals is less than 500 nm, and wherein the anticorrosion coating has at least one of characteristics selected from:
• a surface energy of the anticorrosion coating is greater than 50 mN/m with a dispersive component greater than 40 mN/m;
• an electrochemical potential of the anticorrosion coating in an aqueous solution having a pH of 8.4 is at least −0.7 V;
• and
• a surface reactivity of the anticorrosion coating in an aqueous solution having a pH of 8.4 is greater than 800 μW/cm2.

A process for producing a flat steel product, comprising:

• producing or providing a steel substrate;
• continuously introducing the steel substrate into a coating chamber at a reduced pressure;
• applying an anticorrosion coating on the steel substrate by physical vapor deposition with a coating rate of at least 0.3 μm/s in the coating chamber, wherein the anticorrosion coating is at least on one side of the steel substrate, the anticorrosion coating is made of zinc or a zinc alloy and has a lumpy microstructure comprising nanocrystals and lumps taking a form of an agglomeration of the nanocrystals, wherein the nanocrystals have an average diameter of less than 500 nm and the lumps have an average lump size between 1 μm and 5 μm;
• and
• continuously discharging the steel substrate from the coating chamber.