SPA-C weathering steel is not designed for long-term high-temperature service and is only suitable for low or mild temperature occasions.
1. Usable temperature range
Safe for long-term use:Room temperature up to about 120°C
Not recommended for long-term:Above 200°C
Unfit for any long-term use:300°C and above
2. Why it performs poorly at high temperatures
At high temperatures, its strength and mechanical properties drop significantly.
It forms loose, thick oxide scale instead of a protective patina.
The alloy system (Cu, Cr, P) is optimized for atmospheric corrosion at room temperature, not heat resistance or high-temperature oxidation.
Prolonged high temperature will cause deformation, softening, and accelerated oxidation.
3. Situations where it can still be used
Short-term, occasional low heat exposure (e.g., solar heating, near warm equipment).
Non-load-bearing parts where slight strength loss is acceptable.
4. What to use instead for high temperature
If you need material that works at high temperatures:
Heat-resistant steel
Stainless steel (304, 316, 310S, etc.)
Special high-temperature alloy steel
