1. Core Identity & Standard
S355J0WP
Standard: EN 10025‑5 (European weathering structural steel)
Grade meaning:
S = structural steel; 355 = min yield strength (≤16 mm) ≥355 MPa
J0 = Charpy V‑notch impact ≥27 J at 0 °C
W = weathering resistance; P = high phosphorus (key feature)
2. Chemical Composition (Key Differences)
S355J0WP stands out with controlled high phosphorus (P) and balanced Cr‑Cu‑Ni, unlike other grades.
| Grade | C (%) | P (%) | Cr (%) | Cu (%) | Ni (%) | Key Alloy Feature |
|---|---|---|---|---|---|---|
| S355J0WP | ≤0.12 | 0.06–0.15 | 0.30–1.25 | 0.25–0.55 | ~0.2–0.5 | High P for dense patina |
| Corten A (SMA400AW) | ≤0.19 | ≤0.04 | 0.40–0.65 | 0.25–0.55 | ≤0.65 | Low P, moderate Cr |
| Corten B (SMA400BW) | ≤0.19 | ≤0.04 | 0.40–0.80 | 0.25–0.55 | 0.65–1.25 | Higher Ni for stability |
| Q355NH (GB) | ≤0.16 | ≤0.04 | 0.25–0.50 | 0.20–0.50 | ≤0.50 | Low P, basic weathering |
| Q235NH (GB) | ≤0.18 | ≤0.04 | 0.20–0.40 | 0.15–0.40 | ≤0.40 | Low strength, basic weathering |
| S355J0W | ≤0.16 | ≤0.03 | 0.40–0.80 | 0.25–0.55 | ~0.2–0.5 | No high P, standard weathering |
3. Mechanical Properties
S355J0WP offers high strength + good low‑temperature toughness, better than Q235NH and comparable to Q355NH/Corten A.
| Grade | Yield Strength (≤16 mm) | Tensile Strength | Impact (J0) |
|---|---|---|---|
| S355J0WP | ≥355 MPa | 470–630 MPa | ≥27 J @ 0 °C |
| Corten A | ≥345 MPa | 485–620 MPa | ≥27 J @ 0 °C |
| Corten B | ≥345 MPa | 485–620 MPa | ≥27 J @ 0 °C |
| Q355NH | ≥355 MPa | 490–630 MPa | ≥34 J @ 0 °C |
| Q235NH | ≥235 MPa | 360–510 MPa | ≥27 J @ 0 °C |
| S355J0W | ≥355 MPa | 470–630 MPa | ≥27 J @ 0 °C |
4. Weathering & Corrosion Resistance (The Biggest Difference)
S355J0WP's high phosphorus drives a denser, faster‑forming protective patina.
S355J0WP
P + Cu + Cr form a tight, adherent patina in 3–6 months
Atmospheric corrosion resistance: 2–8× ordinary carbon steel
Less rust runoff; patina stabilizes to dark chocolate brown faster
Better performance in industrial/urban atmospheres
Corten A
Lower P; patina forms slower (6–12 months)
More prone to loose rust and runoff in early stages
Final color: reddish‑brown → dark brown
Corten B
Higher Ni; patina is more uniform and stable long‑term
Better salt‑spray resistance than Corten A/S355J0WP
Final color: dark gray‑brown
Q355NH/Q235NH
Basic weathering; patina forms slowly (6–18 months)
Less dense; more prone to uneven color and runoff
Lower overall corrosion resistance
S355J0W
No high P; patina behavior similar to Corten A, slower than S355J0WP
5. Patina Color & Evolution
S355J0WP
Sequence: silver → yellow → orange → dark brown (stable in 3–6 months)
Final: uniform dark chocolate brown; less variation
High P accelerates patina densification
Corten A
Longer bright orange stage; slower darkening
Final: reddish‑brown → dark brown; more prone to unevenness
Corten B
More gradual; final gray‑brown; very stable
Least color variation over time
Q355NH/Q235NH
Slow, uneven color change; may stay orange longer
Final: patchy dark brown
6. Weldability & Processing
S355J0WP
Low C (≤0.12%); good weldability
Preheat recommended (80–120 °C) to avoid cold cracking
Good cutting, bending, and forming
Corten A/B
Similar weldability; preheat same range
Corten B slightly better toughness in heat‑affected zone
Q355NH/Q235NH
Good weldability; Q235NH easiest to process
