SPA-H is a high‑performance atmospheric weathering steel with excellent and stable corrosion resistance - noticeably superior to entry‑level grades like SPA‑C, and comparable to classic weathering steels such as Corten‑A, Corten‑B, Q355NH, Q450NQR1.
1. Compared with SPA‑C (the most direct comparison)
SPA‑H has much higher corrosion resistance
Higher contents of Cu, Cr, P
Contains nickel (Ni), which SPA‑C does not
Forms a denser, tighter, more stable patina
Much less rust runoff and powdering
Longer service life in outdoor environments
2. Compared with standard Corten‑type weathering steels
Corrosion resistance is similar to Corten‑A / Corten‑B
Both rely on Cu‑Cr‑Ni‑P alloy system to form a stable protective patina
SPA-H is fully capable for long‑term structural use: bridges, buildings, landscapes
3. Compared with high‑strength structural weathering steels (Q355NH, Q460NH)
Atmospheric corrosion resistance is close
The difference is mainly in strength and toughness, not weatherability
SPA-H is optimized for weather resistance + moderate strength
4. Performance in different environments
Rural / urban atmosphere:SPA-H performs very well, with slow, stable corrosion.
Industrial / mildly acidic atmosphere:Excellent resistance due to Cr, Cu, P.
Coastal / salt‑spray environment:With Ni, SPA-H performs much better than SPA‑C, though not as good as stainless steel.
5. Summary of level
SPA‑C: basic weathering resistance
SPA‑H: high weathering resistance
Corten / Q355NH: high weathering resistance
