EN 10025-5 — Hot rolled products of structural steels. Part 5: Structural steels with improved atmospheric corrosion resistance
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Scope
Weathering (Cu-Cr-Ni-P) structural steels that form a protective rust patina: S235J0W, S235J2W, S355J0W, S355J2W, S355K2W and the phosphorus variants S355J0WP/J2WP, as plate, strip, sections and bar. Chemistry (Cu 0.25–0.55, Cr 0.40–0.80), mechanical properties by thickness, impact by quality, delivery conditions; the European home of the material sold as Corten A/B.
Grades covered by EN 10025-5
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Nearest equivalents |
|---|---|---|---|---|---|---|
| S355J2W | 1.8965 | Weathering (atmospheric-corrosion-resistant) structural steel, −20 °C impact | ≤ 0.16 | 355 | 470–630 | A588 Grade A / B, A242 Type 1, A606 Type 4 |
Revision history and superseded standards
| Year | Change |
|---|---|
| 1993 | EN 10155 — first European weathering-steel standard |
| 2004 | EN 10025-5:2004 — merged into the EN 10025 series |
| 2019 | EN 10025-5:2019 — current |
Supersedes: EN 10155:1993 (S355J2G1W, S355J2G2W …); DIN 17100 WT St 37-3 / WT St 52-3.
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Related standards
Weathering steel works by rusting properly
Part 5 covers structural steels with improved atmospheric corrosion resistance — S355J0WP, S355J2W and their relatives, known generically as weathering or Corten-type steel. Copper, chromium, nickel and phosphorus additions cause the rust layer to become dense and adherent rather than flaky, and that layer then slows further corrosion by roughly an order of magnitude.
The mechanism has conditions. The surface must go through wet and dry cycles; a permanently damp detail, a buried section or a sheltered face that never dries will keep corroding at ordinary rates. Weathering steel in the wrong detail is simply unpainted structural steel.
W and WP are not the same steel
The two suffixes divide the family. W grades have low phosphorus and are readily weldable — S355J2W is the structural choice. WP grades carry elevated phosphorus, typically 0.06–0.15 %, which improves the patina but makes welding harder and toughness lower; they belong in architectural cladding rather than in load paths.
A design allowance also applies. The patina consumes metal before it stabilises, so structural members are normally detailed with a corrosion allowance of around 1 mm per exposed surface over the design life, and run-off staining onto adjacent concrete is a detailing problem, not a defect.