Differences Between Aluminum-Zinc Coated Steel Coils and Galvanized Steel Coils

1. Core Difference: Coating Composition
– Galvanized Steel Coils: The coating is pure zinc (Zn), which adheres to the steel coil surface via hot-dip galvanizing or electrolysis. The coating thickness is usually 50-275g/㎡.
– Aluminum-Zinc Coated Steel Coils: The coating is an aluminum-zinc alloy (standard composition: 55% aluminum, 43.4% zinc, 1.6% silicon), produced only by the hot-dip galvanizing process. The coating thickness is mostly 120-225g/㎡.
2. Key Performance Differences
– Corrosion Resistance: Aluminum-zinc coated steel coils are far superior to galvanized steel coils.
Aluminum forms a dense oxide film (aluminum trioxide) on the surface, which can block the penetration of corrosive media, with an outdoor weathering life of up to 10-20 years; while the zinc layer of galvanized steel coils has no self-healing ability after corrosion, and its outdoor life is usually only 3-5 years.
– High-Temperature Resistance: Aluminum-zinc coated steel coils are better, capable of withstanding temperatures above 300℃ (short-term resistance to 600℃), making them suitable for high-temperature scenarios such as ovens and chimneys; galvanized steel coils are prone to zinc layer peeling at temperatures above 200℃, so they have poor applicability in high-temperature scenarios.
– Cost: For the same specification, the price of aluminum-zinc coated steel coils is 10%-30% higher than that of galvanized steel coils, due to higher raw material and process costs.
3. Differences in Application Scenarios
– Galvanized Steel Coils: Suitable for light corrosion protection, indoor or short-term outdoor scenarios, such as home appliance liners, ventilation ducts, indoor decorative parts, and simple temporary buildings.
– Aluminum-Zinc Coated Steel Coils: Suitable for long-term outdoor, high-corrosion or high-temperature scenarios, such as roof load-bearing panels, photovoltaic brackets, curtain walls, outdoor billboards, and automobile exhaust pipe heat shields.