Q295NH and Q355NH are Chinese (GB/T) standard weathering (Corten) steel plates, offering high strength and superior atmospheric corrosion resistance, with 'Q' for steel, numbers for minimum yield strength (295 MPa & 355 MPa), and 'NH' indicating its weathering performance, ideal for bridges, buildings, and containers needing durability and low maintenance in harsh outdoor environments.
Specifications and Standards
| Standard | Grade | Thickness (mm) | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
|---|---|---|---|---|---|
| GB/T 4171 | Q355NH | 3-40 | ≥355 | 490-630 | ≥20 |
| GB/T 4171 | Q295NH | 3-40 | ≥295 | 430-580 | ≥21 |
Chemical Composition (%)
| Element | C | Si | Mn | P | S | Cu | Ni | Cr | Nb |
|---|---|---|---|---|---|---|---|---|---|
| Q355NH | ≤0.20 | 0.30 | 1.00 | ≤0.035 | ≤0.035 | 0.25 | 0.30 | 0.30 | ≤0.10 |
| Q295NH | ≤0.22 | 0.30 | 1.20 | ≤0.035 | ≤0.035 | 0.20 | 0.25 | 0.20 | ≤0.10 |
Mechanical Properties
| Grade | Thickness (mm) | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Impact Energy (J) at -20℃ |
|---|---|---|---|---|---|
| Q355NH | 3-16 | ≥355 | 490-630 | ≥20 | ≥27 |
| Q355NH | 16-40 | ≥345 | 470-630 | ≥20 | ≥27 |
| Q295NH | 3-16 | ≥295 | 430-580 | ≥21 | ≥27 |
| Q295NH | 16-40 | ≥285 | 410-580 | ≥21 | ≥27 |
Key Characteristics:
Corrosion Resistance: Forms a protective, stable rust-like layer, reducing further corrosion.
High Strength: Q355NH has higher strength (≥355 MPa yield) than Q295NH (≥295 MPa yield).
Weldability: Good welding performance, suitable for complex structures.
Low-Temperature Performance: Q355NH offers excellent impact toughness at low temperatures.
Applications:
Infrastructure: Railway bridges, highway overpasses, pedestrian walkways.
Construction: Architectural steel frames, urban overpass retrofitting.
Industrial: Trucks, shipping containers, towers, and structural parts exposed to atmosphere.
Comparison:
Q295NH: Minimum yield strength 295 MPa; common for general weathering applications like containers and structures.
Q355NH: Minimum yield strength 355 MPa; used where higher strength and better low-temp performance are needed, like bridges.
