Q355NH High Strength Weathering Steel For Bridges
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Gnee Steel (Tianjin) Co., Ltd. is one of the most professional q355nh high strength weathering steel for bridges manufacturers and suppliers in China. Welcome to wholesale customized q355nh high strength weathering steel for bridges at competitive price from our factory. Good service and quality products are available.
Products Description
Q355NH High Strength Weathering Steel is a premium low-alloy structural steel designed for critical bridge infrastructure, adhering strictly to GB/T 4171-2008 standards. Its unique alloy composition and mechanical properties deliver exceptional strength, ductility, and corrosion resistance, making it ideal for long-term exposure to harsh outdoor environments.
Chemical Composition (GB/T 4171-2008, Mass Fraction, %)
| Element | C | Si | Mn | P | S | Cu | Cr | Ni |
|---|---|---|---|---|---|---|---|---|
| Range | ≤0.16 | ≤0.50 | 0.50-1.50 | ≤0.030 | ≤0.030 | 0.25-0.55 | 0.30-1.25 |
≤0.65 |
Key alloying elements-Cu, Cr, and Ni-promote the formation of a dense, adherent α-FeO(OH)–γ-FeO(OH) oxide layer, which acts as a natural barrier against moisture and corrosive gases. This self-protective rust layer reduces corrosion rates to 1/5–1/3 of ordinary carbon steel, extending service life by 3–5 times with minimal maintenance.
Mechanical Properties (Thickness ≤16mm, GB/T 4171-2008)
| Property | Value |
|---|---|
| Yield Strength (ReL) | ≥355 MPa |
| Tensile Strength (Rm) | 490–630 MPa |
| Elongation (A) | ≥20% |
| Charpy Impact Energy (20℃, V-Notch) | ≥47 J |
Supplied in hot-rolled or normalized conditions, Q355NH ensures reliable performance under dynamic loading and temperature fluctuations (-20℃ to 60℃), critical for bridges subjected to heavy traffic and cyclic stress .
Corrosion Resistance Mechanism
In moderate-humidity environments (urban, rural, or mild industrial), Q355NH forms a stable rust layer that self-heals over time. Unlike ordinary steel, which suffers from continuous pitting, Q355NH exhibits stable corrosion kinetics, minimizing thickness loss. However, it is not recommended for high-salt (coastal) or strongly acidic (pH <4) environments .
Fabrication & Weldability
Q355NH supports standard cold/hot forming processes (bending, punching, shearing) with performance comparable to low-alloy carbon steels. For welding, use E5015-NH or E5515-NH electrodes to maintain corrosion consistency between the base metal and welds. Post-weld treatments (e.g., slag removal) are essential to prevent localized corrosion at joints .
Advantages for Bridge Applications
High Strength-to-Weight Ratio: Reduces structural weight while meeting load-bearing requirements, optimizing material usage and construction costs.
Low Life-Cycle Cost: Eliminates frequent repainting through natural rust-layer protection, cutting maintenance expenses by up to 60% .
Proven Durability: Successfully applied in landmark projects like the Hong Kong-Zhuhai-Macao Bridge and Lanzhou Xigu Bridge, demonstrating resistance to complex climates and heavy loads .
Standards & Compliance
GB/T 4171-2008: Ensures chemical and mechanical consistency for atmospheric corrosion resistance.
ASTM A588 Grade A Equivalence: Exhibits comparable corrosion resistance to international standards, making it suitable for global bridge projects .
By integrating advanced alloy design and rigorous quality control, Q355NH High Strength Weathering Steel sets a benchmark for durability and cost-efficiency in bridge construction.
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