1. Product Definition & Industry Significance
Q500NH is a high-strength, low-alloy weathering steel tube specifically engineered for structural applications requiring superior atmospheric corrosion resistance. This product belongs to the NH-class weathering steels (EN 10025-5), where "NH" denotes improved resistance to atmospheric corrosion through alloying elements that promote protective patina formation.
2. Material Composition & Metallurgical Advantages
Chemical composition (%):
C: ≤0.12
Si: 0.15-0.50
Mn: 0.90-1.60
P: ≤0.030
S: ≤0.025
Cu: 0.25-0.55
Cr: 0.40-0.80
Ni: ≤0.65
The strategic combination of Cu, Cr, and Ni creates a dense, adherent oxide layer that significantly slows corrosion progression compared to conventional carbon steel.
3. Key Mechanical Properties
Yield strength (Rp0.2): ≥500 MPa
Tensile strength: 610-770 MPa
Elongation: ≥17%
Charpy V-notch impact: ≥40J at -20°C
Hardness: 150-200 HBW
4. Corrosion Performance Characteristics
Atmospheric corrosion rate: 0.002-0.005 mm/year in rural environments
Protection factor: 4-6 times superior to carbon steel
Patina formation time: 6-18 months depending on environment
Suitable for corrosion categories C2-C4 per ISO 12944
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