Prepainted Galvanized Steel Coil Product Overview
Prepainted Galvanized Steel Coil combines continuous hot-dip galvanizing with advanced pre-painted polymer coatings, delivering unmatched corrosion resistance and aesthetic versatility. Using an automated “in-line” process, steel substrates (0.12–3.5 mm thickness) are dipped in molten zinc baths (60–275 g/m² coating weight), followed by precision coating removal via air knives or mechanical wipers for uniform thickness (±5%). Compliant with ASTM A653, EN 10346, and JIS G3302, this product is engineered for automotive panels, architectural cladding, and appliance manufacturing, offering 15–30 years of durability in harsh environments.
Key Technical Specifications
1. Dimensional & Coating Properties
- Base Steel Thickness: 0.12–3.5 mm (±5% tolerance per ASTM A924)
- Width: 600–1,500 mm (custom slit for HVAC, automotive stamping)
- Zinc Coating Weight:
- Standard (Z100): 100 g/m² (14 μm) for indoor appliances
- Heavy-Duty (Z275): 275 g/m² (38 μm) for coastal infrastructure
- Pre-Painted Coatings:
- Polyester (PE): 20–25 μm, UV-resistant for façades
- PVDF: 30–35 μm, chemical-resistant for industrial use
- Silicone-Modified Polyester (SMP): 15–20 μm, heat-reflective for roofing
2. Chemical Composition
| Grade (EN 10346) | C (%) | Si (%) | Mn (%) | P (%) | S (%) |
|---|---|---|---|---|---|
| DX51D+Z | ≤0.12 | ≤0.50 | ≤0.60 | ≤0.10 | ≤0.045 |
| S350GD+Z | ≤0.20 | ≤0.60 | ≤0.70 | ≤0.10 | ≤0.045 |
| S550GD+Z | ≤0.20 | ≤0.60 | ≤0.70 | ≤0.10 | ≤0.045 |
Key Alloy Features:
- Zinc Purity: ≥99.9% for optimal adhesion.
- Trace Elements: Controlled Al (0.15–0.22%) to minimize dross formation.
Mechanical Performance
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
|---|---|---|---|
| DX51D+Z | 240–380 | 270–500 | ≥22 |
| S250GD+Z | ≥250 | ≥330 | ≥19 |
| S550GD+Z | ≥550 | ≥550 | – |
Functional Metrics:
- Bendability: 0T–2T (180° bend @ 0.8 mm thickness).
- Weldability: 10–15 kA spot welding current (20% lower than bare steel).
- Impact Resistance: 40 J/cm² at -20°C (ISO 148-1).
Surface Finish Options
| Coating Type | Surface Texture | Gloss Level | Applications |
|---|---|---|---|
| Zero Spangle | Smooth, spangle-free | 70–80 GU | High-gloss façades, electronics |
| Minimized Spangle | Fine crystalline | 40–50 GU | Automotive interiors, appliances |
| Textured | Embossed patterns | 20–30 GU | Anti-slip roofing, industrial flooring |
Environmental Compliance:
- RoHS-Certified: Chromium-free passivation.
- VOC Emissions: <50 g/L (GreenGuard Gold compliant).
Applications
| Industry | Use Case | Recommended Grade |
|---|---|---|
| Construction | Roofing, cladding | S350GD+Z (Z275 coating) |
| Automotive | Body panels, chassis | DX54D+Z (Z180 coating) |
| Appliances | Refrigerators, washing machines | DX51D+Z (Z100 coating) |
| Energy | Solar panel frames | S550GD+Z (Z200 coating) |
Production Process
- Continuous Galvanizing:
- Degreasing (NaOH, 60°C) → Pickling (HCl, 15%) → Fluxing (ZnCl₂-NH₄Cl).
- Molten zinc immersion (445–465°C) → Air-knife coating control (±3 g/m²).
- Pre-Painting:
- Chromate-free pretreatment → Primer (5–7 μm) → Topcoat (15–35 μm).
- Curing: Infrared oven drying (200–220°C, 30 sec).
Global Standard Equivalents
| China (GB) | Europe (EN) | USA (ASTM) | Japan (JIS) |
|---|---|---|---|
| DC51D+Z | DX51D+Z | A653 CS Type B | SGCC |
| S350GD+Z | S350GD+Z | A653 SS345 | SGHC340 |
| S550GD+Z | S550GD+Z | A653 SS550 | SGHC550 |
Sustainability & Certifications
- Recycled Content: 25–35% (ISO 14021 compliant).
- Carbon Footprint: ≤1.3 tons CO₂ per ton of steel.
- Certifications: LEED v4.1, REACH, ISO 9001.
Packing And Delivery
