SPA-C weathering steel is not designed for long-term high-temperature service; it is a low-carbon atmospheric corrosion-resistant structural steel for normal-temperature outdoor use.
1. Temperature limits
Suitable range:Room temperature to approximately 120–150 °C (248–302 °F) intermittently.
Not recommended:Long-term use above 200 °C (392 °F).
Unsafe:Sustained high temperature above 300 °C will cause obvious softening, oxidation, and performance degradation.
2. Why it is not suitable for high temperatures
At high temperatures, the mechanical properties (strength, hardness) drop significantly.
Rapid high-temperature oxidation occurs, forming thick, loose oxide scale instead of the normal protective patina.
Its alloy system (Cu, Cr, P) is optimized for atmospheric corrosion at room temperature, not heat resistance or high-temperature oxidation resistance.
3. When it can still be used
Short-term, occasional low-level heat exposure (e.g., near warm equipment, normal solar heat).
Non-load-bearing parts where strength loss at mild heat is acceptable.
4. What to use instead for high temperature
If you need heat resistance + corrosion resistance at high temperatures:
Heat-resistant alloy steels
Stainless steel (e.g., 304, 316, 310S)
Special high-temperature weathering steels (not SPA-C)
