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US 12,747,489 B2Granted
Metal-coated steel strip
AssigneeBluescope Steel Limited
InventorsQiyang Liu, Wayne Renshaw, Joe Williams
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Abstract
An Al—Zn—Si—Mg alloy coated strip that has Mg2Si particles in the coating microstructure is disclosed. The distribution of Mg2Si particles is such that the surface of the coating has only a small proportion of Mg2Si particles or is at least substantially free of any Mg2Si particles.
Claims20
A hot-dip coating method to form a corrosion-resistant coated steel strip, the method comprising:
- passing a steel strip through a hot dip coating bath comprising aluminum, zinc, silicon, and magnesium to form an alloy coating on the steel strip comprising, in weight %, 40% to 60% aluminum;
- 40% to 60% zinc;
- 0.3% to 3% silicon;
- and 0.3% to 10% magnesium;
- controlling a short range coating thickness variation of the alloy coating on the steel strip to be no more than 40% in a 5 mm diameter section of the alloy coating;
- and
- cooling the alloy coating on the steel strip;
- wherein the alloy coating has a microstructure comprising Mg2Si particles, and
- wherein controlling the short range coating thickness variation controls the distribution of Mg2Si within the microstructure such that the surface of the alloy coating has no more than 10 wt % of Mg2Si particles to thereby enhance corrosion resistance of the alloy coating.
6 more elements
Dependencies are inferred from the claim text.