Hot-Dip Galvalume® Steel Sheet: Advanced Aluminum-Zinc Alloy Coated Steel for Extreme Environments
Hot-dip Galvalume Steel Sheet Product Overview
Hot-dip Galvalume® steel sheet is a high-performance, corrosion-resistant material coated with a 55% aluminum, 43.5% zinc, and 1.5% silicon alloy via continuous hot-dip processing. Engineered to surpass traditional galvanized steel, this innovative coating delivers 3× superior corrosion resistance, 1,500+ hours of salt spray protection (ASTM B117), and 30+ years of service life in harsh conditions. Compliant with ASTM A792, EN 10346, and JIS G3321, Galvalume® is ideal for roofing, automotive, HVAC, and industrial applications requiring durability and thermal efficiency.
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 (compatible with roll-forming, stamping, and laser cutting)
- Coating Weight: 30–185g/m² (8–50µm per side)
- Density: 3.75g/cm³ (alloy layer), 7.85g/cm³ (base steel)
2. Alloy Coating Composition
| Element | Content (%) | Role |
|---|---|---|
| Aluminum | 55–58 | Forms protective oxide barrier |
| Zinc | 41–43 | Sacrificial corrosion protection |
| Silicon | 1.5–2.0 | Prevents brittle Fe-Al intermetallic formation |
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
Superior Performance Features
- Enhanced Corrosion Resistance:
- The aluminum-rich matrix forms a self-healing Al₂O₃ layer upon exposure, reducing red rust by 85% vs. G90 galvanized steel.
- Salt spray resistance: 1,500+ hours (ASTM B117) vs. 900 hours for G90.
- Thermal Efficiency:
- Solar reflectance: 75% (ASTM E1918), reducing rooftop temps by 15–20°C and cooling costs by 18–25%.
- High-Temperature Stability:
- Maintains integrity up to 315°C (vs. 200°C for galvanized steel), ideal for exhaust systems and fire-rated construction.
- Aesthetic Versatility:
- Zero-spangle finish (Ra 0.8µm) for premium painted surfaces.
- Anti-fingerprint treatment (Code N5) prevents oxidation stains in humid environments.
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
- LEED Contributions: 3–6 points for solar reflectance & thermal emittance
- RoHS Compliance: Cadmium <0.01%, Lead <0.05%
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