1. Key Differences in Chemical Composition
| Grade | C (Max) | Si | Mn | P | S (Max) | Cu | Cr | Ni (Optional) |
|---|---|---|---|---|---|---|---|---|
| S355J0WP | 0.12% | 0.25-0.75% | ≤1.00% | 0.06-0.15% | 0.030% | 0.25-0.55% | 0.50-1.25% | ≤0.65% |
| S355J0W | 0.12% | 0.10-0.40% | 0.20-0.50% | ≤0.030% | 0.025% | 0.25-0.55% | 0.40-0.80% | - |
| S355J2WP | 0.12% | 0.25-0.75% | ≤1.00% | 0.06-0.15% | 0.030% | 0.25-0.55% | 0.50-1.25% | ≤0.65% |
Key Observations:
Phosphorus (P) Content:
S355J0WP & S355J2WP have higher P (0.06-0.15%), improving corrosion resistance.
S355J0W has low P (≤0.03%), making it less corrosion-resistant but better for welding.
Silicon (Si) & Manganese (Mn):
S355J0WP/J2WP have higher Si (0.25-0.75%) for better patina formation.
S355J0W has lower Mn (0.20-0.50%), reducing strength slightly.
Chromium (Cr) & Copper (Cu):
S355J0WP/J2WP have higher Cr (0.50-1.25%) for better rust stabilization.
2. Mechanical Properties Comparison
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Impact Test (J) at -20°C |
|---|---|---|---|---|
| S355J0WP | ≥355 MPa | 470-630 MPa | ≥22% | Not required (0 = no impact test) |
| S355J0W | ≥355 MPa | 470-630 MPa | ≥22% | Not required |
| S355J2WP | ≥355 MPa | 470-630 MPa | ≥22% | ≥27 J (2 = tested at -20°C) |
Key Observations:
S355J2WP is tougher at low temperatures (impact-tested at -20°C), making it better for cold climates.
S355J0WP & J0W are not impact-tested, limiting use in extreme conditions.
3. Corrosion Resistance & Weathering Performance
Best for Rust Patina Formation:
S355J0WP & S355J2WP (higher P, Cr, Cu) form a denser, more stable rust layer than S355J0W.
Moderate Resistance:
S355J0W has lower P and Cr, so it weathers slower and may need maintenance in harsh environments.
4. Weldability & Fabrication
| Grade | Weldability | Notes |
|---|---|---|
| S355J0WP | Moderate | Higher P can increase crack risk; preheating may be needed. |
| S355J0W | Best | Low P & S improve weldability. |
| S355J2WP | Moderate | Similar to J0WP but tougher for low-temp welding. |
Key Observations:
S355J0W is the easiest to weld (low P, S).
S355J0WP/J2WP require precautions (preheat, low-hydrogen electrodes).
5. Common Applications
| Grade | Typical Uses |
|---|---|
| S355J0WP | Bridges, outdoor sculptures, façades (urban/rural areas). |
| S355J0W | Light structural applications where welding is critical. |
| S355J2WP | Heavy structures in cold climates (e.g., Nordic bridges, offshore platforms). |
