The 09CuPCrNi-A steel (per Chinese standard GB/T 4171-2008) is a weathering structural steel designed to form a stable, protective rust layer (patina) when exposed to atmospheric conditions. Its key properties are categorized below:
1. Core Mechanical Properties
(Per GB/T 4171-2008, as-tested transverse specimens)
| Property | Value |
|---|---|
| Yield Strength (ReH) | ≥ 345 MPa |
| Tensile Strength (Rm) | ≥ 490 MPa |
| Elongation (A₅₀) | ≥ 22% (A₅ for thickness ≤16mm) |
| Impact Toughness (V-notch, -40°C) | ≥ 27 J |
2. Weathering (Corrosion Resistance) Properties
Protective Patina: Forms an adherent, rust-colored barrier that retards further corrosion (typically 2–8x better than carbon steel).
Suitable Environments: Urban, rural, industrial atmospheres (Avoid stagnant water, coastal salt spray, or reducing environments).
Standard Exposure Test: Corrosion rate ≤0.25 mm/year after 7.5 years (accelerated lab test per GB/T 4171).
3. Chemical Composition (% by Weight)
(Typical ranges - balances corrosion resistance & weldability)
| Element | Range | Key Role |
|---|---|---|
| C | ≤0.12% | Strengthening (lower C aids weldability) |
| Si | 0.20–0.75% | Deoxidation |
| Mn | 0.20–0.60% | Strength & toughness |
| P | 0.07–0.15% | Critical for patina formation |
| S | ≤0.035% | Minimize (impurity) |
| Cu | 0.25–0.45% | Primary corrosion resistance |
| Cr | 0.30–0.65% | Stabilizes patina |
| Ni | 0.12–0.65% | Enhances toughness & corrosion resistance |
| Fe | Balance | - |
(Minor additions of V/Ti/Nb may refine grain size).
4. Fabrication & Processing
Hot Forming: 850–1100°C (avoid below 700°C).
Cold Forming: Possible with annealing for severe deformation.
Heat Treatment: Stress relieving < 600°C (patina damage above this).
Machinability: Similar to HSLA steels (use coolant for chip control).
5. Weldability
Preheating: Recommended for >16mm thickness or low temps (80–150°C).
Electrodes: Low-hydrogen types (e.g., J507CrNiCu per GB/T 5117; AWS E7016-G).
Shielding Gas: Use Ar+CO₂ mix for GMAW.
Post-Weld: Slag removal critical for corrosion resistance. No annealing required.
6. Limitations & Notes
Surface Prep: Patina requires cyclic wet/dry exposure (~1–3 years). Unpainted use ideal.
Avoid: Chloride-rich environments (marine), poor drainage designs, burrowing rust under paint.
Design: Ensure ventilation + drainage to prevent moisture trapping.
Typical Applications
Bridges, railways, power transmission towers.
Architectural facades, shipping containers.
Structural components in moderately corrosive industrial zones.
For compliance-critical projects, always consult GB/T 4171-2008 specifications and validate mechanical tests for your thickness/supplier.
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