1. Difference in Chemical Composition (Core Feature)
S355J0WP
High phosphorus (P) design: 0.06–0.15% P is specially added to promote dense patina formation.
Low carbon, with Cu, Cr, Ni for weathering resistance.
Optimized for fast, stable rust layer in industrial atmosphere.
Ordinary weathering steels (Q355NH, Q235NH, S355J0W)
Low phosphorus (P ≤ 0.035%), no high‑P enhancement.
Relatively basic alloy system, slower patina formation.
Corten A / ASTM A242
Low P, medium Cr‑Cu, focus on general atmospheric corrosion.
No high‑P effect for accelerated patina densification.
Corten B / ASTM A588
Higher nickel (Ni) content, better chloride resistance.
More suitable for coastal environments than S355J0WP.
2. Difference in Patina Formation Speed & Uniformity
S355J0WP
Forms stable, dark brown patina faster (3–6 months).
More uniform color, less early‑stage rust runoff.
High P makes the rust layer denser from the beginning.
Q355NH / Corten A
Patina takes 6–12 months to stabilize.
Longer bright orange stage, more obvious runoff.
Color more uneven during maturation.
3. Difference in Corrosion Resistance Performance
S355J0WP
Excellent in urban & industrial environments (SO₂, acid rain).
Good in rural atmosphere.
Weak in high‑salt coastal zones (not marine‑grade).
Corten B / A588
Better salt resistance; more reliable in mild coastal areas.
Slightly lower patina speed but better long‑term stability.
Q355NH / Q235NH
Basic weathering performance, lower overall corrosion resistance.
Not ideal for heavy industrial or mildly corrosive environments.
4. Difference in Mechanical Properties
S355J0WP
S355 grade: yield strength ≥ 355 MPa.
J0 toughness: ≥27 J at 0°C.
High strength, suitable for load‑bearing structures.
Q235NH
Lower strength (≥235 MPa), for non‑critical lightweight parts.
S355J0W / Corten A/B
Similar strength level to S355J0WP, but different toughness and HAZ behavior.
5. Difference in Weldability
S355J0WP
Good weldability, but needs attention to phosphorus embrittlement in heavy sections.
Preheat recommended for thick plates or low temperatures.
Q355NH / Corten A/B
More forgiving in welding; less sensitive to phosphorus effect.
6. Difference in Application Scope
S355J0WP
Bridges, steel structures, containers, railway equipment, industrial buildings.
Best for inland & industrial environments requiring fast stable patina.
Corten B / A588
Better choice for mild coastal structures, landscape facades.
Q355NH / Q235NH
General outdoor structures, cost‑sensitive projects.
