We supply hot-rolled weathering structural steel for bridges (such as Q355NH), designed for different span bridges and harsh outdoor environments. For thickness ≤16 mm, it provides a minimum yield strength of ≥355 MPa and tensile strength of 490–630 MPa, with elongation of ≥22% and good 180° bending performance.
Compared with ordinary bridge steel, it offers similar or better load-bearing capacity while reducing corrosion-related section loss. In atmospheric, industrial, and coastal environments, it forms a dense protective rust layer, improving corrosion resistance by about 45% compared to carbon steel.
This allows the first maintenance coating to be delayed to 15–20 years or more, significantly reducing lifecycle maintenance costs. It is widely used in bridge trusses, arch bridge members, elevated structures, and heavy-duty outdoor steel frameworks.
We supply hot-rolled high weathering bridge structural steel in compliance with GB/T 4171-2008, covering grades such as Q235NH, Q355NH, and Q310GNH, designed to meet different load-bearing requirements for bridges of various spans.
Compared with conventional bridge steels (carbon steel or non-weathering low-alloy steel), which are prone to rusting, flaking, and section loss under humid, corrosive, and cyclic loading environments, GB/T 4171-2008 weathering steel maintains stable long-term mechanical performance.
For thickness ≤16 mm, key grades such as Q355NH provide a minimum yield strength of ≥355 MPa, while Q310GNH ensures ≥310 MPa, with excellent fatigue resistance and cold forming performance. In typical service conditions, its structural service life can be extended to 30–50 years or more, significantly outperforming ordinary carbon steel bridge structures.
In highway, railway, and urban elevated bridge applications, the first maintenance coating can be delayed to 15–20 years or longer, with overall service life typically 2–3 times that of conventional carbon steel structures. This greatly reduces long-term maintenance frequency, traffic interruption risks, and indirect operational losses.
Speicifcation of weathering structural steel for bridges
|
Item |
Specification |
|
Product Name |
GB/T 4171 Atmospheric Corrosion Resistant Structural Steel Sheet |
| Material Grade | Q235NH, Q295NH, Q295GNH, Q355NH, Q355GNH, Q415NH, Q460NH, Q500NH, Q550NH, Q265GNH, Q310GNH) |
| Thickness Range | 1.5 mm – 40.0 mm |
| Width Range | 1000 mm, 1250 mm, 1500 mm, 1800 mm, 2000 mm, or Customized |
| Length Range | 2000 mm, 3000 mm, 6000 mm, 12000 mm, or Customized |
| Surface Condition | As-Rolled, Pickled, or Pre-rusted (Accelerated Weathered Finish) |
| Manufacturing Process | Hot Rolled, Thermo-Mechanical Control Process (TMCP), Normalized |
| Processing Services | Laser Cutting, CNC Punching, Bending, Welding, Leveling |
| Edge Condition | Mill Edge (ME), Slit Edge (SE) |
| Delivery Condition | Hot Rolled / Controlled Rolled / Normalizing Rolled |
| Certificate | EN 10204 3.1 MTC, Mill Test Certificate |
| Inspection Available | PMI (Chemical Analysis), Mechanical Testing, Impact Testing, SGS, BV, TUV |
| Delivery Time | 7–15 Days |
Chemical Composition of GB/T 4171 Weathering Structural Steel for Bridge
| Grade | C (%) | Si (%) | Mn (%) | P (%) | S (%) | Cu (%) | Cr (%) | Ni (%) |
|---|---|---|---|---|---|---|---|---|
| Q235NH | ≤0.14 | 0.20–0.50 | 0.30–0.65 | 0.060–0.120 | ≤0.030 | 0.25–0.55 | 0.30–1.25 | ≤0.65 |
| Q265GNH | ≤0.14 | 0.20–0.50 | 0.40–0.80 | 0.060–0.120 | ≤0.030 | 0.25–0.55 | 0.30–1.25 | ≤0.65 |
| Q295NH | ≤0.13 | 0.20–0.50 | 0.50–1.00 | 0.060–0.120 | ≤0.030 | 0.25–0.55 | 0.30–1.25 | ≤0.65 |
| Q295GNH | ≤0.13 | 0.20–0.50 | 0.50–1.00 | 0.060–0.120 | ≤0.030 | 0.25–0.55 | 0.30–1.25 | ≤0.65 |
| Q310GNH | ≤0.13 | 0.20–0.50 | 0.60–1.20 | 0.060–0.120 | ≤0.030 | 0.25–0.55 | 0.30–1.25 | ≤0.65 |
| Q355NH | ≤0.12 | 0.20–0.50 | 0.80–1.50 | 0.060–0.120 | ≤0.030 | 0.25–0.55 | 0.30–1.25 | ≤0.65 |
| Q355GNH | ≤0.12 | 0.20–0.50 | 0.80–1.50 | 0.060–0.120 | ≤0.030 | 0.25–0.55 | 0.30–1.25 | ≤0.65 |
| Q415NH | ≤0.12 | 0.20–0.50 | 0.90–1.60 | ≤0.060 | ≤0.030 | 0.25–0.55 | 0.40–1.25 | ≤0.65 |
| Q460NH | ≤0.12 | 0.20–0.50 | 1.00–1.70 | ≤0.060 | ≤0.030 | 0.25–0.55 | 0.40–1.25 | ≤0.65 |
| Q500NH | ≤0.12 | 0.20–0.50 | 1.20–1.80 | ≤0.060 | ≤0.030 | 0.25–0.55 | 0.40–1.25 | ≤0.65 |
| Q550NH | ≤0.12 | 0.20–0.50 | 1.20–1.80 | ≤0.060 | ≤0.030 | 0.25–0.55 | 0.40–1.25 | ≤0.65 |
Mechanical Properties of GB/T 4171 Weathering Structural Steel for Bridge
| Grade | Yield Strength ReH (MPa) | Tensile Strength Rm (MPa) | Elongation A (%) | Impact Toughness |
|---|---|---|---|---|
| Q235NH | ≥235 | 360–500 | ≥26 | 20°C ≥ 27J |
| Q265GNH | ≥265 | 400–520 | ≥25 | 20°C ≥ 27J |
| Q295NH | ≥295 | 420–540 | ≥24 | 20°C ≥ 27J |
| Q295GNH | ≥295 | 420–540 | ≥24 | 20°C ≥ 27J |
| Q310GNH | ≥310 | 440–570 | ≥23 | 20°C ≥ 27J |
| Q355NH | ≥355 | 490–630 | ≥22 | 20°C ≥ 27J |
| Q355GNH | ≥355 | 490–630 | ≥22 | 20°C ≥ 27J |
| Q415NH | ≥415 | 520–680 | ≥20 | 20°C ≥ 27J |
| Q460NH | ≥460 | 550–720 | ≥19 | 20°C ≥ 27J |
| Q500NH | ≥500 | 610–760 | ≥17 | 20°C ≥ 27J |
| Q550NH | ≥550 | 620–780 | ≥16 | 20°C ≥ 27J |
Equivalent Grades of GB/T 4171 Weathering Steel
| GB/T 4171 Grade | EN Standard (Europe) | ASTM (USA) | JIS (Japan) |
|---|---|---|---|
| Q235NH | S235J0W / S235J2W | ASTM A242 | SPA-H (lower range) |
| Q265GNH | S275J0W | ASTM A242 / A588 (low) | SPA-H |
| Q295NH | S355J0WP (approx. low) | ASTM A242 | SPA-H |
| Q295GNH | S355J0WP | ASTM A588 Grade A | SPA-H |
| Q310GNH | S355J2W (close match) | ASTM A588 Grade A | SPA-H |
| Q355NH | S355J0WP / S355J2W | ASTM A588 Grade B | SPA-H |
| Q355GNH | S355J2W | ASTM A588 Grade B | SPA-H |
| Q415NH | S420W (approx.) | ASTM A588 Grade B/C | SPA-H (high strength) |
| Q460NH | S460W (approx.) | ASTM A588 Grade C | SPA-H (high strength) |
| Q500NH | S500W (approx.) | ASTM A588 Grade K (close) | SPA-H modified |
| Q550NH | S550W (approx.) | ASTM A588 Grade K / A709 | SPA-H modified |
Application Case: Weathering Steel Bridges
Thames Valley Parkway – North Branch - London, ON
Owner: City of London
Scope: Design, Fabrication, Delivery and Erection
Whirlpool Road Multi-Use Pathway Pedestrian Bridge - Niagara, ON
Owner: City of Niagara Falls
Scope: Design, Fabrication, Delivery and Erection
Rowntree Mills Park North Bridge & Pathway Rehabilitation - North York, ON
Owner: City of Toronto
Scope: Design, Fabrication, Delivery and Erection
Weathering steel bridges feature a zero-coating lifecycle, which not only eliminates VOC emissions from on-site spraying but also slashes your bridge superstructure construction timeline by over 20% by skipping the coating process entirely.
Contact us today to get the complete design and rapid construction blueprint for coating-free steel bridges!
Contact now to get the Corten Steel Bridge Quote
GNEE Steel operates fully equipped heavy-duty processing centers to offer a comprehensive range of services for weathering steel bridge engineering:
Precision Cutting & Beveling:
High-power laser cutting, CNC plasma cutting, and flame cutting (specifically optimized for high-strength heavy plates up to 50mm+). We provide high-precision groove processing (V, X, Y types) to ensure a perfect fit for subsequent bridge assembly.
Surface Pre-treatment:
Advanced automatic shot blasting (achieving Sa2.5/Sa3.0 cleanliness standard) to completely remove mill scale. We also provide eco-friendly chemical accelerated weathering treatment to help form a uniform, dense protective rust layer (Fe3O4) in days, preventing early-stage rust staining on piers.
Heavy Forming & Leveling:
Large-tonnage CNC bending, plate leveling (eliminating internal rolling stress), and precision rolling, perfectly ideal for U-ribs, box girders, and curved bridge structural components.
Matching Welding and Sub-assembly:
Factory-controlled automated sub-assembly and welding services utilizing specialized weathering welding consumables. Our processes strictly match the atmospheric corrosion resistance and low-temperature impact toughness of the base metal, compliant with AWS, EN, and third-party inspection (SGS/BV) standards.
Lead Time of Corten Steel Bridge
Standard Stock:
Constant inventory is maintained for common bridge weathering steel specifications (e.g., Grades A588/SPA-H/Q355NH, thickness 6mm–40mm, width 1500mm/2000mm/2500mm).
Delivery: Products can be processed, dispatched from the warehouse, and ready for shipment within 3 to 7 working days upon receipt of the advance payment or Letter of Credit (L/C).
Customized / Special Specifications:
Production scheduling orders must be placed directly with the steel mills for heavy plates requiring extra width (up to 3500mm+), extra thickness (50mm–100mm+), stringent Z-direction performance (Z15/Z25/Z35), or specialized processing (e.g., pre-blasting/welded components).
Delivery: The lead time is typically around 20 to 35 working days, depending on the mill's production schedule and project volume.
Testing and Inspection of weathering structural steel for bridges
MTC (Material Test Certificate):
Provides comprehensive material test certificates compliant with EN 10204 3.1 or 3.2 standards. The MTC covers detailed chemical composition (including key weathering elements like Cu, Cr, Ni, P) and precise mechanical properties (yield strength, tensile strength, elongation).
Low-Temperature Impact Toughness Test:
Crucial for bridge safety, testing Charpy V-notch impact energy at specified temperatures (e.g., 0°C, -20°C, or -40°C) to prevent brittle fracture in cold climates.
Ultrasonic Testing (UT):
Performed in accordance with ASTM A435/A578 or EN 10160 standards for heavy bridge plates to detect internal defects, laminations, or voids, ensuring structural integrity.
Z-Direction (Through-Thickness) Tension Test:
Available upon request (Z15/Z25/Z35) for thick welded sections to prevent lamellar tearing during heavy bridge fabrication and welding.
Atmospheric Corrosion Index (I-Value) Verification:
Calculates the weathering steel corrosion index based on heat analysis to guarantee premium long-term weathering and anti-corrosion performance.
Third-Party Inspection:
Third-party inspections (such as SGS or Bureau Veritas) are fully supported.
