1. Key Characteristics
① Weathering Resistance
Forms a protective rust layer (patina) when exposed to weather, reducing further corrosion.
Contains alloying elements (Cu, Cr, Ni, P) to enhance atmospheric corrosion resistance.
Eliminates the need for painting in many applications, reducing maintenance costs.
② Mechanical Properties (EN 10155 Standard)
| Property | Value |
|---|---|
| Yield Strength (ReH) | ≥ 355 MPa |
| Tensile Strength (Rm) | 470–630 MPa |
| Elongation (A₅) | ≥ 20% |
| Impact Toughness (Charpy V-notch, -20°C) | ≥ 27 J (J2 grade requirement) |
| Brinell Hardness (HBW) | ~ 140–180 HBW |
③ Chemical Composition (Typical, wt%)
| Element | Content (Max, unless range specified) |
|---|---|
| C (Carbon) | ≤ 0.12% |
| Si (Silicon) | 0.10–0.50% |
| Mn (Manganese) | 0.80–1.25% |
| P (Phosphorus) | ≤ 0.08% (improves corrosion resistance) |
| S (Sulfur) | ≤ 0.030% |
| Cu (Copper) | 0.25–0.55% (key for weathering) |
| Cr (Chromium) | 0.40–0.80% |
| Ni (Nickel) | ≤ 0.65% |
| Others (V, Ti, etc.) | Optional for grain refinement |
Key Notes:
Higher Mn & Cu than standard S355 steels → better corrosion resistance.
Low S & P → good weldability and toughness.
2. Comparison with Similar Weathering Steels
| Grade | Standard | Yield Strength (MPa) | Impact Test Temp. | Key Difference |
|---|---|---|---|---|
| S355J2G1W (EN 10155) | EN 10155 | ≥ 355 | -20°C | Optimized for structural weathering |
| S355J0WP (Corten B, EN 10025-5) | EN 10025-5 | ≥ 355 | 0°C | Slightly lower impact toughness |
| S355J2WP (EN 10025-5) | EN 10025-5 | ≥ 355 | -20°C | Similar to S355J2G1W, but different standard |
| ASTM A588 Grade A/B | ASTM | ≥ 345 | -20°C to -40°C | US equivalent, stricter impact requirements |
3. Key Applications
Bridges & Highway Structures (due to corrosion resistance).
Architectural Facades & Sculptures (rust aesthetic desired).
Transmission Towers & Offshore Platforms (harsh environments).
Railway Wagons & Shipping Containers (durability in wet conditions).
4. Weldability & Machinability
Weldability
Good weldability with common methods (SMAW, MIG, TIG).
Preheating (100–150°C) may be needed for thick sections to avoid cracking.
Recommended electrodes: Low-hydrogen types (E7018, E71T-1).
Machinability
Moderate machinability (similar to S355 steels).
Cutting tools: Use carbide or coated tools for better life.
Cutting speed:
Turning: 80–120 m/min (carbide).
Drilling: 20–30 m/min (HSS).
5. Advantages Over Standard Structural Steels
Superior corrosion resistance (reduces maintenance costs).
High strength-to-weight ratio (good for load-bearing structures).
Aesthetic rust appearance (popular in modern architecture).
Good weldability & formability (suitable for fabrication).
