Q460NH is a high-strength structural weathering steel. It does not possess the special high-temperature properties of heat-resistant steels, boiler steels, or stainless steels, so it is not suitable for long-term service in high-temperature conditions.
1. Recommended Temperature Limits
200℃Within this range, strength decreases slightly, surface oxidation is minimal, and basic performance remains stable.
Short-term occasional exposure250℃Brief exposure causes no obvious damage, but prolonged use leads to obvious performance degradation.
Above 300℃: Severe strength loss, rapid oxidation, and structural risks may occur.
2. Performance Changes at Elevated Temperatures
Yield and tensile strength decrease noticeably as temperature rises, so it can no longer reliably meet the design requirements for Q460-grade high-strength structures.
Instead of forming a dense, protective rust layer, the surface produces thick, brittle, loose oxide scale that easily spalls, destroying its weathering resistance.
Prolonged high temperature causes microstructure softening, grain coarsening, and reduced toughness and fatigue resistance.
Under continuous load at high temperatures, the steel may slowly deform or even develop cracks over time.
3. Suitable and Unsuitable Applications
Normal atmospheric environments (−20℃ to 120℃)
Long-term high-temperature pipelines or structural components
Any environment with sustained temperatures above 250℃
