Q295GNH Structural Steel is a premium-grade weathering alloy engineered to withstand extreme atmospheric conditions, adhering to GB/T 4171-2008 standards . This advanced steel combines high tensile strength, self-healing corrosion resistance, and sustainable design, making it ideal for bridges, industrial infrastructure, coastal projects, and architectural structures exposed to salt-laden air, acid rain, and industrial pollutants.
Core Engineering Properties
Alloy Composition: Contains Cu (0.25-0.45%), Cr (0.30-0.65%), and Ni (0.25-0.50%) , forming a dense α-FeOOH oxide layer that reduces corrosion rates by 2-8 times compared to conventional carbon steel . Phosphorus (0.07-0.12%) enhances resistance to acidic environments, while controlled carbon (≤0.12%) ensures weldability and ductility .
Mechanical Performance:
Yield strength ≥295 MPa (thickness ≤16mm), tensile strength 430-560 MPa, and elongation ≥24% , ensuring load-bearing capacity under dynamic wind and seismic loads.
Impact resistance: ≥34J at -20℃ (Grade A) to ≥27J at -40℃ (Grade E) , critical for low-temperature and high-seismic zones.
Corrosion Resistance & Longevity
Atmospheric Protection: Develops a self-protective rust patina (50-100μm thick) through exposure to moisture and oxygen, which acts as a physical barrier against further corrosion . This passive layer resists chloride ingress in coastal areas and sulfur dioxide in industrial zones, with corrosion rates ≤0.1 mm/year in 5% NaCl environments .
Salt Spray Performance: Passes ASTM B117 testing with minimal corrosion after 1000 hours, making it suitable for marine piers and offshore platforms .
Long-Term Durability: In coastal environments, Q295GNH exhibits 3-4 times lower corrosion rates than carbon steel, with a projected service life exceeding 30 years without coatings.
FAQ
1. What is Q295GNH Structural Steel designed for?
Answer: It is engineered to withstand extreme atmospheric conditions, suitable for bridges, industrial infrastructure, coastal projects, and architectural structures exposed to salt-laden air, acid rain, and industrial pollutants.
2. Which standard does Q295GNH comply with?
Answer: It complies with GB/T 4171-2008.
3. What key alloy elements enhance Q295GNH's corrosion resistance, and how?
Answer:
Copper (Cu 0.25–0.45%), chromium (Cr 0.30–0.65%), nickel (Ni 0.25–0.50%): Form a dense α-FeOOH oxide layer, reducing corrosion rates by 2–8 times compared to conventional carbon steel.
Phosphorus (P 0.07–0.12%): Enhances resistance to acidic environments and chloride ingress.
Controlled carbon (C ≤0.12%): Ensures weldability and ductility for fabrication.
4. What are the mechanical properties of Q295GNH?
Answer:
Yield strength: ≥295 MPa (for thickness ≤16mm), supporting dynamic wind and seismic loads.
Tensile strength: 430–560 MPa, resisting deformation under stress.
Elongation: ≥24%, enabling flexibility for complex structural designs.
Impact resistance: ≥34 J at -20°C (Grade A) to ≥27 J at -40°C (Grade E), suitable for low-temperature and high-seismic zones.
5. What corrosion resistance and longevity features does Q295GNH offer?
Answer:
Self-protective patina: Forms a 50–100μm thick rust layer, acting as a barrier against chloride and sulfur dioxide; corrosion rates ≤0.1 mm/year in 5% NaCl environments.
Salt spray performance: Passes ASTM B117 testing with minimal corrosion after 1000 hours, ideal for marine and offshore applications.
Long-term durability: In coastal environments, corrosion rates are 3–4 times lower than carbon steel, with a projected service life exceeding 30 years without coatings.
