Comparison between Galvalume Steel Coil and Galvanized Steel Coil

Galvalume Steel Coil is a common metal material widely used in construction, home appliances, automobile manufacturing and other fields. It combines the strength of steel with the corrosion resistance of aluminum and zinc by coating an aluminum-zinc alloy layer on the surface of a steel substrate.

The substrate of the galvanized steel coil is a cold-rolled steel sheet, and a layer of aluminum-zinc alloy is coated on the surface through a hot-dip coating process. The typical coating composition is 55% aluminum, 43.4% zinc and 1.6% silicon. The addition of silicon helps to improve the bonding strength between the coating and the steel substrate and prevent the coating from peeling. The coating thickness of the galvanized steel coil is usually between 10 and 30 microns, depending on the application requirements.

• Comparison between Galvalume Steel Coil and other coated steel coils

(1) Comparison with galvanized steel coils

The coating composition of galvanized steel coils is pure zinc. Although it has good corrosion resistance, it corrodes faster in certain environments (such as high humidity and high salt environments). In contrast, the aluminum-zinc alloy layer of galvanized steel coils can form a denser oxide film, which is more corrosion-resistant and has a longer service life. The addition of aluminum makes galvanized steel coils more stable in high-temperature environments, while pure zinc is easily oxidized and ineffective at high temperatures.

(2) Comparison with aluminum-coated steel coils

The coating of aluminum-coated steel coils is pure aluminum, and its high-temperature resistance is worse than that of galvanized steel coils, but its corrosion resistance in normal atmospheric environments is not as good as that of galvanized steel coils. The zinc in the aluminum-zinc alloy can provide cathodic protection. Even if the coating is partially damaged, the zinc will corrode first, protecting the steel base from rust. Pure aluminum coatings do not have this property. Once damaged, the steel base is prone to rust.