Q310GNH Weathering Steel for Bridge Construction is a premium structural alloy engineered to meet the rigorous demands of bridge engineering, offering exceptional atmospheric corrosion resistance and mechanical performance. Compliant with GB/T 4171-2008, this steel combines a yield strength of ≥310 MPa with a tensile strength of ≥450 MPa, ensuring robust load-bearing capacity while minimizing maintenance costs in corrosive environments such as coastal regions or industrial zones. Its self-protective rust layer (γ-FeOOH) reduces corrosion rates to 1/5–1/8 that of carbon steel, making it ideal for long-term exposure in bridges .
Technical Properties
Chemical Composition
Cu-P-Cr-Ni Microalloy System: Copper (Cu) enhances patina formation, phosphorus (P) improves corrosion resistance, and chromium (Cr) and nickel (Ni) stabilize the protective oxide layer. This combination results in a weathering index (I) ≥6.0, exceeding industry standards for durability .
Low Carbon Content (C ≤0.12%): Ensures excellent weldability and ductility, critical for complex bridge fabrications like box girders and trusses.
Strict Sulfur Control (S ≤0.02%): Reduces hot brittleness and enhances toughness, vital for dynamic loading scenarios.
Mechanical Performance
High Strength: Yield strength ≥310 MPa supports medium-to-high load applications, including main girders and piers.
Impact Resistance: Achieves ≥34 J at room temperature (V-notch), with optional -20°C testing available for cold-climate bridges .
Fatigue Resistance: Engineered to withstand cyclic loading typical of bridge traffic, with a fatigue limit exceeding 200 MPa in bending tests.
Corrosion Resistance
Self-Healing Patina: Over 3–6 months, a dense, adherent rust layer (50–100 μm thick) forms, creating a natural barrier against chloride ions and moisture. This eliminates the need for frequent painting, reducing lifecycle costs by 30–50% .
FAQ
1. What is Q310GNH Weathering Steel designed for?
Answer: It is engineered for bridge construction, meeting rigorous demands with exceptional atmospheric corrosion resistance and mechanical performance, suitable for coastal or industrial environments.
2. Which standard does Q310GNH comply with?
Answer: It complies with GB/T 4171-2008.
3. What are the key mechanical properties of Q310GNH for bridges?
Answer:
Yield strength: ≥310 MPa (supports medium-to-high loads for main girders/piers).
Tensile strength: ≥450 MPa.
Impact resistance: ≥34 J at room temperature (V-notch), with optional -20°C testing for cold climates.
Fatigue resistance: Fatigue limit exceeds 200 MPa in bending tests for cyclic loading.
4. How does Q310GNH enhance corrosion resistance for bridges?
Answer:
Self-healing patina (γ-FeOOH): Forms a 50–100 μm dense rust layer over 3–6 months, reducing corrosion rates to 1/5–1/8 that of carbon steel.
Cu-P-Cr-Ni microalloy system: Copper promotes patina formation, phosphorus improves corrosion resistance, and chromium/nickel stabilize the oxide layer (weathering index ≥6.0).
5. What are the technical advantages of Q310GNH in bridge construction?
Answer:
Low carbon content (C ≤0.12%): Ensures excellent weldability and ductility for complex fabrications (e.g., box girders).
Strict sulfur control (S ≤0.02%): Reduces hot brittleness and enhances toughness for dynamic loads.
Lifecycle cost savings: Eliminates frequent painting, reducing maintenance costs by 30–50%.
