1. Material Overview
Standard: GB/T 4171-2008 (Chinese weathering steel)
Composition:
C ≤ 0.12%, Cu 0.25-0.55%, P 0.07-0.15%, Cr 0.30-1.25%, Ni ≤ 0.65%
Enhances rust layer formation (patina) for corrosion protection.
Mechanical Properties:
Yield Strength (≥345 MPa), Tensile Strength (≥490 MPa)
Impact Toughness: Good at low temperatures (tested at -40°C).
2. Key Welding Challenges
(1) Hydrogen-Induced Cracking (HIC) Risk
High P (Phosphorus) content increases crack sensitivity.
Moisture & hydrogen in welding rods must be minimized.
(2) Loss of Corrosion Resistance in Weld Zone
Improper filler metal selection can disrupt the protective patina formation.
(3) Heat-Affected Zone (HAZ) Softening
Excessive heat input may reduce strength near welds.
3. Recommended Welding Methods
| Process | Filler Metal | Shielding Gas (if applicable) | Notes |
|---|---|---|---|
| SMAW (MMA) | J507CrNiCu (GB/T 5118) | – | Low-hydrogen, preheat 100-150°C |
| GMAW (MIG) | ER50-6 (AWS A5.18) + Cu coating | 80% Ar + 20% CO₂ | Low spatter, good penetration |
| FCAW | E71T-1C/J (AWS A5.20) | – | High efficiency, outdoor use |
| SAW | H08MnA + SJ101 flux | – | For thick plates (>20mm) |
Preheating:
50–120°C (for thickness >12mm or low ambient temp).
Interpass Temp: ≤200°C to avoid excessive grain growth.
4. Post-Weld Treatment
Slag Removal: Clean welds to prevent crevice corrosion.
Stress Relief Annealing: Not usually required (unless for thick sections >30mm).
Corrosion Protection:
Allow natural patina formation.
If painting is needed, use weathering-resistant primers.
5. Weld Performance Evaluation
Mechanical Tests: Tensile, bend, and Charpy impact (-40°C).
Corrosion Test: Salt spray (ASTM B117) vs. bare carbon steel.
Microstructure: Ensure no excessive martensite in HAZ.
6. Comparison with Other Weathering Steels
| Property | 05CuPCrNi | Corten A (A242) | Q355GNH |
|---|---|---|---|
| Corrosion Resistance | Excellent | Excellent | Good |
| Weldability | Good (low-H₂ needed) | Moderate (higher P) | Good |
| Typical Use | Bridges, containers | Architecture, facades | Structural beams |
Conclusion & Recommendations
Best for: Bridges, rail cars, and outdoor structures where corrosion resistance + weldability are critical.
Critical Factors:
Use low-hydrogen electrodes.
Control heat input (10–25 kJ/cm).
Avoid moisture contamination.
