1. General effect of temperature on Q355NH
Yes, the mechanical properties of Q355NH weathering steel are affected by temperature changes, but this behavior is predictable, stable, and consistent with standard structural steel performance; it does not deteriorate abnormally due to its weathering composition.
2. Effect at low temperatures
As temperature decreases, yield strength and tensile strength slightly increase, but impact toughness decreases.
Q355NH is designed to maintain acceptable toughness at ambient low temperatures commonly seen in outdoor environments.
In very cold conditions (e.g., below -20°C or lower), it may show increased brittleness unless specified for low-temperature notch impact requirements.
Weathering alloy elements (Cu, Cr, Ni) do not cause abnormal brittle behavior compared to regular Q355 steel.
3. Effect at high temperatures
At moderately high temperatures (up to 200°C–250°C), yield strength and tensile strength remain relatively stable.
Above 300°C, strength begins to decrease noticeably, and creep behavior may appear under long-term load.
Q355NH is not intended for high-temperature service (such as boilers or high-temperature pipelines), so outdoor high-temperature exposure does not create unusual risk.
4. Effect of daily / seasonal temperature cycles
Normal outdoor temperature cycles (hot summers, cold winters) do not cause permanent damage to mechanical properties.
Thermal expansion and contraction are predictable and consistent with typical structural steels.
No embrittlement, softening, or strength loss occurs from normal cyclic temperature exposure.
5. Comparison with ordinary Q355B carbon steel
Q355NH responds to temperature changes in almost the same way as Q355B.
The weathering alloy composition does not significantly alter its temperature‑dependent mechanical behavior.
Design values for strength, toughness, and stability under temperature variation can be used similarly to conventional low-alloy structural steels.
