Z275 Galvanized Steel Sheet: Superior Corrosion Protection for Demanding Environments
Product Overview
Z275 galvanized steel sheet is a premium-grade carbon steel product featuring a 275g/m² zinc coating applied via the continuous hot-dip galvanizing (HDG) process. Compliant with ASTM A653, EN 10346, and JIS G3302 standards, this material delivers 1,200+ hours of salt spray resistance (ISO 9227), making it ideal for coastal infrastructure, heavy-duty industrial equipment, and automotive underbody components. The triple-layer zinc-iron alloy structure ensures sacrificial protection even when the surface is scratched, outperforming standard galvanized sheets by 300% in corrosion resistance.
Technical Specifications
1. Base Material Properties
- Thickness: 0.12mm (ultra-thin electrical enclosures) to 6.00mm (structural beams) ±0.03mm tolerance
- Width: 600–1,500mm (compatible with roll-forming automation systems)
- Coating Weight:
- Z275: 275g/m² (38.5µm per side)
- G90 (ASTM Equivalent): 0.90 oz/ft² total
2. Mechanical Performance
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (A80%) |
|---|---|---|---|
| DX54D+Z275 | 120–220 | 260–350 | ≥36% |
| S350GD+Z275 | 350 | 420 | ≥16% |
| SGCD3+Z275 | 160–240 | 280–400 | ≥32% |
Advanced Coating Technology
The HDG process involves:
- Cleaning: Alkaline degreasing at 70°C to remove mill oils
- Annealing: Continuous furnace treatment at 720°C for optimal formability
- Zinc Bath Immersion: 455°C molten zinc with 0.2% aluminum for spangle control
- Air Knife Finishing: Precision coating thickness control (±3g/m²)
This creates a metallurgical bond between the zinc and steel substrate, achieving 6,500 hours to first red rust in C5-M marine environments (ISO 12944).
Surface Treatment Options
| Code | Process | Key Applications |
|---|---|---|
| C | Chromate passivation | Outdoor electrical cabinets |
| Q | Phosphating + oiling | Pre-painted roofing systems |
| S | Sealed chromate + oiling | Automotive chassis parts |
| PV | PVDF coating (30µm) | Architectural façades |
Environmental Durability Guide
| Exposure Condition | Recommended Solution | Service Life* |
|---|---|---|
| Indoor dry environments | Z275 + oiling (Code O) | 25–30 years |
| Coastal salt spray zones | Z275 + PVDF coating | 40+ years |
| Chemical processing plants | Z275 + epoxy primer | 15–20 years |
| High-abrasion mining equipment | Z275 + ceramic coating | 10–12 years |
Based on ISO 14713-1 corrosion protection guidelines
Forming & Fabrication Advantages
- Cold Bending Performance
- Minimum bend radius: 0.5× thickness (for 2mm sheet: R1.0mm)
- Springback angle: ≤2° after 90° bending
- Welding Compatibility
- Resistance spot welding: 9–14kA current range
- Laser welding speed: 5m/min (1.5mm thickness)
- Punching & Stamping
- Blank holder force: 15–25 tons (for 300mm dies)
- Tool life improvement: 40% vs. Z180-coated sheets
Chemical Composition
| Element | C | Mn | P | S | Al |
|---|---|---|---|---|---|
| Content | ≤0.15% | ≤1.70% | ≤0.025% | ≤0.025% | 0.15–0.22% |
The low sulfur/phosphorus content minimizes hot cracking during welding, while aluminum additives refine zinc crystal structure for uniform coating.
Competitive Comparison
| Feature | Z275 Galvanized | Aluminized Steel | Galvalume |
|---|---|---|---|
| Salt spray resistance | 1,200+ hours | 800 hours | 1,500 hours |
| Thermal resistance | 200°C max | 650°C | 340°C |
| Conductivity | 13% IACS | 20% IACS | 25% IACS |
| Cost per ton | $1,100 | $1,400 | $1,250 |
Industry Applications
- Renewable Energy
- Solar farm mounting structures (Z275 + MPPO coating)
- Wind turbine tower interiors
- Transportation
- Truck trailer floors (3mm Z275 withstands 20-ton loads)
- Railway container doors
- Construction
- Seawall reinforcement panels
- Industrial warehouse roofing (0.7mm Z275 + SMP coating)
Sustainability Features
- 92% recycled content in steel substrate
- Zinc recovery rate: 99.8% in closed-loop galvanizing plants
- Water-based pretreatment systems (VOC emissions <15g/m²)
Logical Flow Enhancers:
- For instance, coastal infrastructure projects benefit from Z275’s 40-year service life.
- Moreover, the triple-layer zinc-iron alloy prevents underfilm corrosion.
- In addition, automotive manufacturers achieve 30% weight reduction vs. stainless steel.
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