AZ55 Galvalume® Steel Sheet: Premium 55% Aluminum-Zinc Alloy Coated Steel for Extreme Environments
AZ55 Galvalume Steel Sheet Product Overview
The AZ55 Galvalume® steel sheet is a high-performance building material featuring a 55% aluminum, 43.5% zinc, and 1.5% silicon alloy coating applied via hot-dip processing. With 3× superior corrosion resistance vs. traditional galvanized steel (G90), this advanced composite material delivers 1,500+ hours of salt spray protection (ASTM B117) and 30+ years of service life in coastal, industrial, and high-humidity applications. Compliant with ASTM A792, EN 10346, and JIS G3321, AZ55 excels in roofing, automotive, and HVAC systems requiring unmatched durability.
Key Technical Specifications
1. Base Material & Dimensions
- Thickness: 0.12mm (ultra-thin cladding) to 6.00mm (structural beams) ±0.03mm tolerance
- Width: 600–1,500mm (optimized for roll-forming and laser cutting)
- Coating Weight: 30–185g/m² (8–50µm per side)
- Alloy Density: 3.75g/cm³ (vs. 7.14g/cm³ for pure zinc)
2. Alloy Composition
| Element | Content (%) | Role |
|---|---|---|
| Aluminum | 55–58 | Forms protective Al₂O₃ oxide layer |
| Zinc | 41–43 | Sacrificial corrosion protection |
| Silicon | 1.5–2.0 | Prevents Fe-Al intermetallic brittleness |
3. Mechanical Properties
| Grade (EN 10346) | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (A80%) | Bendability |
|---|---|---|---|---|
| DX51D+AZ | 240–380 | 270–500 | ≥22% | 0t (180°) |
| S350GD+AZ | ≥350 | ≥420 | ≥16% | 1t (90°) |
| S550GD+AZ | ≥550 | ≥550 | – | Not recommended |
Tested per ISO 6892-1 tensile standards
Performance Advantages
- Unmatched Corrosion Resistance:
- The aluminum-rich matrix creates a self-healing oxide barrier, reducing red rust by 85% vs. G90 galvanized steel.
- 1,500+ hours salt spray resistance (ASTM B117) in marine environments.
- Thermal Efficiency:
- 75% solar reflectance (ASTM E1918) lowers rooftop temps by 15–20°C, cutting cooling costs by 18–25%.
- High-Temperature Stability:
- Withstands 315°C continuous exposure (vs. 200°C for galvanized steel), ideal for exhaust systems.
- Aesthetic Versatility:
- Zero-spangle finish (Ra 0.8µm) for premium painted surfaces.
- Anti-fingerprint treatment (Code N5) prevents oxidation stains.
Manufacturing Process
- Hot-Dip Alloying:
- Steel cleaning: 3-stage alkaline degreasing (pH 11.5, 65°C)
- Continuous annealing: 730°C in 10% H₂ + 90% N₂ atmosphere
- Alloy bath immersion: 590°C with 1.5% Si for interlayer adhesion
- Surface Treatment Options:
- Chromate passivation (Code C): 0.5µm layer for indoor storage
- PVDF coating: 25µm fluoropolymer for coastal architecture
Industry Applications
| Sector | Use Case | Recommended Coating |
|---|---|---|
| Construction | Standing seam roofing | 90g/m² AZ + PVDF |
| Automotive | Mufflers & heat shields | 150g/m² AZ (Code N5) |
| Appliances | Refrigerator backplates | 60g/m² AZ + epoxy |
| Agriculture | Grain silo roofs | 120g/m² AZ + polyester |
Global Material Equivalents
| China | Europe | USA | Japan |
|---|---|---|---|
| DC51D+AZ | DX51D+AZ | ASTM A792 | SGLCC |
| S350GD+AZ | S350GD+AZ | CS Type B | SGLC490 |
Sustainability & Compliance
- Recycled Content: 92% post-industrial steel scrap
- Coating Reclaim: 97% alloy recovery rate
- RoHS Compliance: Lead <0.05%, Cadmium <0.01%
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