1. What is Galvalume Steel Sheet?
Galvalume, also known as 55% aluminum-zinc alloy-coated steel sheet, is a type of steel coated with a mixture of 55% aluminum, 43.4% zinc, and 1.6% silicon through a hot-dip process. This coating combines the corrosion resistance of aluminum with the cathodic protection of zinc, making it superior to traditional galvanized steel (GI sheet).
2. Key Features
Superior Corrosion Resistance
The aluminum forms a dense oxide layer, while zinc provides sacrificial protection, resulting in a lifespan 2–6 times longer than regular galvanized steel, especially in harsh environments.
High-Temperature Resistance
Withstands continuous exposure to temperatures up to 315°C (600°F), compared to only 200°C (392°F) for standard galvanized steel.
Aesthetic Appeal
Smooth surface with a matte silver-gray finish, suitable for both painted and bare-metal applications.
Cost-Effectiveness
Although slightly more expensive than galvanized steel, its extended service life reduces long-term costs.
3. Common Standards & Grades
International Standards
ASTM A792 (U.S. standard for Galvalume sheets).
EN 10346 (European standard, designated as DX54D+AZ150, where "AZ" stands for aluminum-zinc coating and "150" indicates coating weight in g/m²).
Chinese Standard
GB/T 14978-2017(Continuous hot-dip aluminum-zinc alloy-coated steel sheets and strips).
Coating Weight
Common designations: AZ50, AZ100, AZ150(numbers represent grams per square meter, e.g., AZ150 = 150g/m²).
4. Typical Applications
Construction Industry
Roofing, wall panels, and canopies (e.g., corrugated sheets).
Appliance Manufacturing
Air conditioner housings, refrigerator back panels, and oven exteriors.
Transportation
Automotive exhaust heat shields, shipping container components.
Agriculture & Industrial Use
Grain silos, livestock roofing, and chemical equipment protection.
5. Galvalume vs. Other Coated Steel Sheets
Galvalume (55% Al-Zn) outperforms traditional galvanized steel (GI) and aluminized steel in corrosion resistance and heat tolerance. While galvanized steel relies solely on zinc for protection, Galvalume benefits from aluminum’s barrier properties. Aluminized steel (with pure aluminum coating) excels in extreme heat but lacks zinc’s sacrificial protection, making Galvalume a balanced choice for most environments.
6. Frequently Asked Questions
Can Galvalume be welded?
Yes, but it requires proper techniques to avoid coating damage.
Does Galvalume rust?
It resists rust significantly better than galvanized steel but may corrode if the coating is damaged.
Is painting necessary?
Not required for corrosion protection, but paint can enhance aesthetics.
Galvalume steel sheet is a versatile, durable, and cost-efficient material widely used across industries. Whether for construction, automotive, or appliances, its unique properties make it a preferred alternative to traditional coated steels.