Q295NH Atmospheric Corrosion Resistant Weathering Steel Plate
🛡️ Patina-Forming Steel with 295 MPa Minimum Yield Strength & Enhanced Durability
What is Q295NH Weathering Steel?
Q295NH is a Chinese-grade structural weathering steel standardized under GB/T 4171. The "NH" stands for "Nai Hou" (耐候), directly translating to "weather resistance". With a minimum yield strength of 295 MPa, Q295NH offers a higher strength-to-weight ratio compared to Q235NH, while retaining excellent weathering characteristics. It forms a dense, stable, and adherent rust layer (the patina) under cyclic wet/dry conditions, providing 2 to 8 times the atmospheric corrosion resistance of standard carbon steel. This grade is ideal for structural applications demanding both increased strength and long-term, low-maintenance durability.
Decoding the Grade: Q295NH
The naming follows the Chinese steel grade system, where each part reveals key performance characteristics:
Core Value Proposition
Q295NH delivers exceptional lifecycle cost savings by merging enhanced structural integrity with built-in corrosion protection. It is engineered for projects requiring higher strength-to-weight ratios without sacrificing longevity, providing a robust, low-maintenance material solution for more demanding applications.
Your Partner for Weathering Steel Supply
We are a professional Chinese supplier offering Q295NH weathering steel plates, sheets, and sections for global projects. We provide mill-direct ordering with full traceability and support the entire export process, ensuring you receive material that meets both GB/T 4171 and your specific project requirements.
Start Your Q295NH Project
We offer flexible procurement options for Q295NH, from technical consultation to reliable delivery. Benefit from competitive pricing, strict quality adherence to GB/T 4171, and dedicated support for your international project needs.
✓ Formal quotation within 8-12 hours
✓ Full technical data & mill certificates
✓ Export documentation support
Standards & International Comparisons
Q295NH is specified under the Chinese National Standard GB/T 4171 "Weathering Structural Steels". While direct, chemically identical equivalents in other standards are rare due to differing numbering systems, Q295NH is functionally comparable to several internationally recognized higher-strength weathering steel grades, offering similar performance characteristics for atmospheric corrosion resistance with enhanced yield strength.
Comparison with Key International Standards
| Standard | Comparable Grade | Key Similarity | Note |
|---|---|---|---|
| GB/T 4171 (China) | Q295NH | Primary reference grade. | Defines chemical composition & mechanical properties. |
| DIN EN 10025-5 (Europe) | S295W* | Similar yield strength (~295 MPa) and weathering principle. | *S295W is less common. Specific alloying may differ. |
| ASTM A588 (USA) | Grade A (~345 MPa) | Comparable weathering performance. | A588 typically has higher min yield (345 MPa). |
| JIS G3125 (Japan) | SMA400BW, SMA490W | Similar weathering performance. | Japanese high-performance weathering steel. |
Important Note: The table indicates functional comparability, not chemical identity. For any project requiring material substitution or governed by specific regional codes, engineers must verify suitability.
Chemical Composition (GB/T 4171)
The specific alloying elements (notably Copper, Chromium, and Nickel) are key to forming the protective patina. The following table details the mandatory and optional composition requirements for Q295NH.
| Grade | Chemical Composition (Quality Fraction)/% | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| C | Si | Mn | P | S | Cu | Cr | Ni | others | ||
| Q295NH | ≤0.15 | 0.1 ~ 0.5 | 0.3 ~ 1.0 | ≤0.03 | ≤0.03 | 0.25 ~ 0.55 | 0.40 ~ 0.8 | ≤0.65 | a , b | |
| Notes: ᵃ To improve properties, trace alloying elements may be added: Nb 0.015%~0.060%, V 0.02%~0.12%, Ti 0.02%~0.10%, Alt ≥0.020%. When used in combination, at least one element should meet lower limit. ᵇ The following alloying elements can be added: Mo≤0.30%, Zr≤0.15%. ᶜ Total amount of Nb+V+Ti ≤0.22%. ᵈ Through negotiation, S ≤0.008%. ᵉ Through negotiation, Ni lower limit may not be required. ᶠ Through negotiation, C may not exceed 0.15%. |
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Production & Delivery (Based on GB/T 4171)
Smelting Methods: The steel is smelted in a converter or electric furnace and is killed steel. Unless otherwise specified, the smelting method shall be selected by the supplier.
Delivery Status: Hot-rolled steel is delivered in hot-rolled, controlled-rolled, or normalized condition. Steel grades Q460NH, Q500NH, and Q550NH can be delivered in quenched and tempered condition. Cold-rolled steel is generally delivered in annealed condition.
Permissible Deviations: Shall comply with GB/T 222.
Mechanical & Processing Properties
Q295NH provides enhanced structural strength (295 MPa min yield) combined with good formability and weldability. The mechanical properties vary slightly with plate thickness as detailed below.
| Grade | Tensile Test a | 180° Bending test mandrel diameter | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Lower yield strength ReL ≥ (MPa) | Tensile Strength Rm (MPa) |
Elongation after fracture A/% ≥ | ||||||||||||
| ≤16 | >16~40 | >40~60 | >60 | ≤16 | >16~40 | >40~60 | >60 | ≤6 | >6~16 | >16 | ||||
| Q295NH | 295 | 285 | 275 | 255 | 430 ~ 560 | 24 | 24 | 23 | 22 | a | 2a | 3a | ||
Note: 'a' represents the steel thickness (in mm). When a yield plateau is not evident, Rp0.2 may be used.
Advantages & Typical Applications
Key Advantages
- Enhanced Strength (295 MPa): Higher load-bearing capacity, allowing lighter sections.
- Superior Corrosion Resistance: 2-8x better than carbon steel.
- Low Maintenance & Lifecycle Cost: Eliminates or reduces painting.
- Aesthetic Appeal: Develops a stable russet-brown patina.
- Good Weldability & Fabrication.
- Sustainable Choice.
Typical Applications
- Structural components (beams, columns, trusses).
- Bridges, highway guardrails, sound barriers.
- Transmission & telecommunication towers.
- Railway rolling stock & containers.
- Industrial & agricultural equipment.
- Ventilation ducts & chimneys.
Frequently Asked Questions (FAQ)
Find quick answers to the most common questions about Q295NH weathering steel. For more detailed inquiries, please don't hesitate to contact us.
The primary difference lies in their minimum yield strength. Q295NH has a higher guaranteed minimum yield strength of 295 MPa (for thicknesses ≤16mm), compared to Q235NH's 235 MPa. This makes Q295NH suitable for applications requiring higher load-bearing capacity, potentially allowing for lighter structural sections while maintaining performance. Both grades offer similar excellent weathering resistance.
One of the primary advantages of Q295NH weathering steel is that painting is generally not required for corrosion protection. The steel is designed to form a dense, adherent patina that significantly slows down further corrosion. Painting may be applied for purely aesthetic reasons, but it is not necessary for its core function.
Yes, Q295NH has good weldability. Standard welding processes such as SMAW, GMAW/MIG, and FCAW can be used. It is recommended to use welding consumables that match or exceed the strength and corrosion resistance of the base metal. Standard pre-heating and post-weld heat treatment practices for low-alloy steels should be followed, especially for thicker sections.
According to GB/T 4171, hot-rolled Q295NH steel is typically delivered in hot-rolled, controlled-rolled, or normalized condition. Cold-rolled products are generally supplied in an annealed condition. The exact delivery condition can be specified based on project requirements.
We offer flexible MOQ options. For standard grades and sizes, typical MOQ starts from 5 metric tons, but we can discuss smaller quantities for trial orders. Lead time depends on product form and quantity. Please contact us for an accurate quotation.
Supply Information
Available Forms
- Plates & Sheets
- Hot-rolled Coils
- Sections (H-beams, I-beams, Channels, Angles)
- Bars
Delivery Condition
- Hot-rolled: As-rolled, controlled-rolled, or normalized.
- Cold-rolled: Generally annealed.
ℹ️ All technical data is based on GB/T 4171 and is for reference. Contact our sales team for a detailed technical consultation.
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