Q265GNH Atmospheric Corrosion Resistant Weathering Steel Plate

GB/T 4171 | High Weathering Steel with 265 MPa Minimum Yield Strength

What is Q265GNH Weathering Steel?

Q265GNH is a Chinese-grade structural weathering steel standardized under GB/T 4171. The "GNH" stands for "Gao Nai Hou" (高耐候), meaning "high weathering resistance". This grade features enhanced phosphorus content (0.07-0.12%) which significantly improves atmospheric corrosion resistance. Q265GNH forms a dense, stable, and adherent protective patina layer when exposed to cyclic wet/dry atmospheric conditions, providing superior corrosion resistance while maintaining excellent formability and good weldability.

Decoding the Grade: Q265GNH

The naming follows the Chinese steel grade system, where each part reveals key performance characteristics:

Q Yield Strength Designator — Structural steel where "Q" stands for "Qu" (屈), representing Yield Point.
265 Minimum Yield Strength — Guarantees a minimum yield strength of 265 MPa (for thickness ≤16mm).
G High Weathering — "Gao" (高) indicates enhanced weathering resistance with higher phosphorus content.
NH Weathering Quality Grade — "Nai Hou" (耐候) indicates atmospheric corrosion resistance with alloying elements (Cu, Cr, Ni, P) enabling patina formation.

Domestic Grades Comparison

Q235NH

Yield Strength: ≥235 MPa
P Content: ≤0.030%
Application: General structural use
Key Alloy Elements (GB/T 4171)
Cu: 0.25-0.55% | Cr: 0.40-0.80% | Ni: ≤0.65%

Q265GNH

Yield Strength: ≥265 MPa
P Content: 0.07-0.12% (enhanced)
Application: Light to medium weathering structures
Key Alloy Elements (GB/T 4171)
Cu: 0.20-0.45% | Cr: 0.30-0.65% | Ni: 0.25-0.50%

Q295NH

Yield Strength: ≥295 MPa
P Content: ≤0.030%
Application: Medium-load structures
Key Alloy Elements (GB/T 4171)
Cu: 0.25-0.55% | Cr: 0.40-0.80% | Ni: ≤0.65%

Core Characteristics:
✔ Q265GNH features enhanced phosphorus content (0.07-0.12%) for superior atmospheric corrosion resistance.
✔ The "G" designation indicates "Gao Nai Hou" (高耐候) meaning high weathering resistance.
✔ Q265GNH offers excellent formability and is ideal for light to medium structural applications.

Chemical Composition (GB/T 4171)

Grade C Si Mn P S Cu Cr Ni Others*
Q265GNH ≤0.12 0.10-0.40 0.20-0.50 0.07-0.12 ≤0.020 0.20-0.45 0.30-0.65 0.25-0.50 ①,②
📌 Notes on chemical composition:
① Micro-alloying: may contain Nb (0.015-0.060%), V (0.02-0.12%), Ti (0.02-0.10%), Alt ≥0.020%. At least one element meets lower limit; total Nb+V+Ti ≤0.22%.
② Optional: Mo ≤0.30%, Zr ≤0.15% may be added by agreement.
③ Permissible deviations for product analysis according to GB/T 222. Sulphur can be agreed ≤0.008%.
④ Through negotiation, Ni lower limit may be waived, or C ≤0.15% upon request.
⑤ Smelting: converter or electric furnace, fully killed steel. Delivery states: hot-rolled / controlled-rolled / normalized.

Mechanical Properties & Bending Test

Grade Lower yield strength ReL (≥ MPa) Tensile strength Rm (MPa) Elongation after fracture A/% ≥ 180° Bending
mandrel diameter
≤16 >16-40 >40-60 >60 N/mm² ≤16 >16-40 >40-60 >60 ≤6 >6-16 >16
Q265GNH 265 — — — ≥410 27 — — — a — —
265 = Yield strength (MPa) for ≤16mm only — = not applicable for other thicknesses ≥410 = Tensile strength (min) (MPa) a = Bending mandrel diameter for ≤6mm only (a = specimen thickness)

Note: 'a' = specimen thickness. Rp0.2 applies if no yield plateau. Bending specimen width b=35mm for arbitration. "—" indicates the property is not specified for that thickness range.

265
Min Yield (MPa) ≤16mm
≥410
Tensile Rm (MPa) min
27%
Elongation A (≤16mm)
0.07-0.12
Phosphorus P %

Available Supply Range

Thickness Range

  • Hot-rolled plates: 2mm - 16mm
  • Sheets / Coils: 1.5mm - 16mm
  • Custom thickness: Available upon request

Width & Length

  • Width: 900mm - 4000mm
  • Length: 2000mm - 18000mm
  • Custom sizes: Cut-to-length available

Product Forms

  • Steel Plates (hot-rolled, normalized)
  • Steel Sheets & Coils
  • Sections: H-beams, I-beams, Channels, Angles
  • Flat bars & Round bars

Surface & Edge Options

  • As-rolled surface / Shot blasted
  • Primer coated (optional)
  • Mill edge / Trimmed edge
  • Beveled edge for welding
Stock availability: Regular sizes in stock for quick delivery | Mill order: Custom sizes available with 20-35 days lead time

Custom Dimensions & Processing

Custom Sizes

Non-standard dimensions

Laser/Plasma Cutting

CNC precision cutting

Edge Beveling

Single/double bevel

Drilling & Punching

Custom hole patterns

Bending & Forming

Plate rolling, profiling

Surface Treatment

Shot blasting, priming

Engineering Support: Free CAD assistance, nesting optimization, technical consultation

Advantages & Typical Applications

Key Advantages

  • Enhanced phosphorus content for superior weathering resistance
  • Excellent formability for complex shapes
  • High elongation (27%) for good ductility
  • Good weldability with standard processes
  • No painting required, reduces lifecycle costs
  • Forms dense protective patina naturally

Typical Applications

  • Railway rolling stock & light containers
  • Architectural cladding & roofing
  • Highway noise barriers & sign structures
  • Light structural frames & transmission towers
  • Outdoor sculptures & art installations

Frequently Asked Questions (FAQ)

1. What does "GNH" mean in Q265GNH?
2. What is the difference between Q265GNH and Q235NH?
3. What is the difference between Q265GNH and Q295GNH?
4. Does Q265GNH require painting?
5. Is Q265GNH weldable?

Supply Information

Available Forms

  • Plates & Sheets
  • Hot-rolled Coils
  • Sections (H-beams, Channels, Angles)
  • Bars

Delivery Condition

  • Hot-rolled: As-rolled, controlled-rolled, or normalized
  • Cold-rolled: Annealed condition
  • Mill test certificate (EN 10204 3.1) available

MOQ & Lead Time

  • Standard MOQ: 5 tons
  • Stock items: 30-35 days
  • Custom production: 35-45 days

Start Your Q265GNH Project

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