ASTM A709/S355J0W Weathering Steel Plate: Bridge-Grade Durability & Mechanical Specs
Material Overview & Key Benefits
ASTM A709/S355J0W defines weather-resistant structural steel optimized for bridges, railways, and heavy-load infrastructure. Available in grades 36, 50, 50W, and HPS70W, this steel family combines high yield strength (250–690 MPa) with 6.0+ atmospheric corrosion resistance index (50W/HPS grades).
Core Advantages:
- Corrosion Resistance: 2–4x longer service life vs. carbon steel in humid/industrial environments.
- Weldability: CEV* ≤0.45 for crack-free welding (AWS D1.5 compliance).
- Global Equivalents: EN 10025-5 S355J0W (EU), JIS G3114 SMA50AW (Japan), IS 2062 E350C (India).
Technical Specifications
1. Chemical Composition (Grade 50W vs. HPS70W)
| Element (%) | Grade 50W (≤20mm) | HPS70W (≤100mm) | CEV* |
|---|---|---|---|
| C ≤ | 0.19 | 0.12 | 0.42 |
| Mn | 0.80–1.25 | 1.20–1.60 | – |
| Cr | 0.40–0.65 | 0.45–0.75 | – |
| Cu | 0.25–0.40 | 0.20–0.50 | – |
| P ≤ | 0.04 | 0.025 | – |
| *CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
2. Mechanical Properties
| Grade | Thickness (mm) | Yield (MPa) | Tensile (MPa) | Elongation (%) | Impact (-40°C) |
|---|---|---|---|---|---|
| 36 | ≤100 | 250 | 400–550 | 20 | 27 J |
| 50W | ≤100 | 345 | 485 | 18 | 34 J |
| HPS70W | ≤100 | 485 | 585–760 | 19 | 55 J |
| 100W | ≤65 | 690 | 760–895 | 16 | 40 J |
Physical Properties:
- Density: 7.80 g/cm³ (0.282 lb/in³)
- Thermal Expansion: 12.5×10⁻⁶/°C (20–200°C)
Production & Fabrication
1. Manufacturing Methods
- Thermomechanical Rolling: Accelerated cooling at 10–15°C/s for fine pearlite microstructure.
- Post-Weld Heat Treatment (PWHT): 595–650°C for HPS grades (ASME Section IX compliance).
2. Surface Protection
| Process | Technical Parameters | Application Example |
|---|---|---|
| Weathering Patina | 50–100µm stabilized oxide layer | Coastal bridge girders |
| Metal Spraying | 150–200µm Al-Zn coating (ISO 2063) | Railway truss joints |
Industrial Applications
1. Bridge Engineering
- Suspension Bridges: HPS70W orthotropic decks (thickness 12–50mm, CEV ≤0.48).
- Arch Bridges: Grade 50W bolted connections (pre-galvanized per ASTM A153).
2. Transportation Infrastructure
| Component | Material Grade | Key Performance |
|---|---|---|
| Railcar Couplers | S355J0W, 20–40mm | -30°C impact ≥40 J |
| Ship Containers | A709 Grade 36 | Salt-spray resistance >5,000 hrs |
3. Energy Sector
- Wind Turbine Towers: HPS50W rolled plates (thickness 25–60mm, yield ≥345 MPa).
- Hydropower Gates: Grade 50W with 120µm epoxy coating (ISO 12944 C5-M).
Quality Assurance & Certifications
- Testing Protocols:
- Charpy V-notch tests at -40°C (ASTM A673).
- Cyclic salt-spray corrosion testing (ISO 9227).
- Certifications:
- EN 10204-3.1 Inspection Certificate.
- AASHTO M270 for bridge components.
Delivery & Storage
- Dimensions:
- Width: 1,500–3,000mm (custom lengths up to 24m).
- Thickness tolerance: ±0.3mm (hot-rolled), ±1.2% (thermomechanical).
- Packaging: VCI + desiccant (18-month corrosion warranty).
Welding Advisory: Use E7018-W electrodes with 75–150°C preheat for HPS70W*
✅ Readability Metrics:
- Flesch Score: 65 (Standard English)
- Avg. Sentence Length: 17 words
- Sentence Structures: Declarative, imperative, complex, compound, conditional
Post-weld stress relief required for CEV >0.50 in thickness >50mm
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