SPA‑C is a moderate‑strength, formability‑focused weathering steel, with mechanical properties clearly different from high‑strength structural weathering steels (like SPA‑H, Q355NH, Q460NH, Corten‑B). Below is a clear, professional comparison.
1. Strength level
SPA‑C:
Yield strength: ~245 MPa min.
Tensile strength: 345–490 MPa
Designed for cold forming, stamping, welding (container manufacturing).
SPA‑H / Q355NH / Corten‑B:
Yield strength: ~355 MPa min. (much higher)
Higher tensile strength and load‑bearing capacity.
Used for load‑bearing structures: bridges, buildings, large steel structures.
2. Formability & ductility
SPA‑C:
Excellent ductility, bendability, stamping performance.
Optimized for container panel forming, cold bending, and deep drawing.
Better formability than most high‑strength weathering steels.
High‑strength weathering steels:
Formability is lower because higher strength reduces ductility.
More difficult for complex cold forming.
3. Weldability
SPA‑C:
Extremely good weldability; suitable for mass automated production lines.
Low carbon equivalent → less hardening risk during welding.
Other weathering steels:
Weldable but may require preheating or controlled heat input at high strength.
4. Toughness
SPA‑C:
Good room‑temperature toughness for general structural use.
Not designed for extremely low temperatures or high impact.
SPA‑H / Q355NH / Q460NH:
Generally better low‑temperature toughness for critical structures.
5. Typical design purpose
SPA‑C:Formability & weldability first, strength second.→ containers, vehicle shells, thin‑plate parts.
Other weathering steels:Strength & durability first, formability second.→ bridges, buildings, heavy structures.
