1. Material Overview (A606 Steel)
Type: Weathering steel (similar to ASTM A588, Corten)
Key Alloys: Cu, Cr, Ni, P (enhances corrosion resistance)
Yield Strength: 345 MPa (50 ksi) min
Notable Feature: Forms a protective rust layer ("patina") over time
2. Pre-Welding Preparation
(1) Surface Cleaning
Remove mill scale, rust, oil, or paint using grinding, sandblasting, or chemical cleaning.
Ensure joint edges are clean (no contaminants).
(2) Joint Design & Fit-Up
Bevelling: Use V-groove, J-groove, or U-groove for thick plates (>6mm).
Gap Control: Maintain 1.5–3mm root gap for full penetration.
Preheat (if required):
Preheat Temp: 50–150°C (depends on thickness, typically needed for >20mm plates).
Interpass Temp: ≤ 200°C (to avoid excessive heat input).
3. Welding Methods & Consumables
(1) Recommended Processes
| Method | Best For | Notes |
|---|---|---|
| SMAW (Stick) | Field welding, repairs | Use low-hydrogen rods |
| GMAW (MIG) | High-speed production | Requires shielding gas (Ar+CO₂) |
| FCAW (Flux-Cored) | Heavy plates, outdoor welding | Self-shielded or gas-shielded |
| GTAW (TIG) | Precision, thin plates | High-quality finish |
(2) Filler Metal Selection
AWS Classification:
SMAW: E7018-W (low-hydrogen, weathering grade)
GMAW/FCAW: ER70S-6 (for mild steel) or EWNi-1 (for better corrosion match)
GTAW: ER70S-2 (cleaner weld)
Note: If matching weathering properties is critical, use Corten-specific fillers (e.g., AWS A5.28 ER80S-Ni1).
4. Welding Parameters
(1) Typical Settings
| Process | Current (A) | Voltage (V) | Travel Speed | Gas (if used) |
|---|---|---|---|---|
| SMAW | 90–140 (DC+) | 22–28 | Moderate | N/A |
| GMAW | 150–250 | 22–30 | Fast | 75% Ar + 25% CO₂ |
| FCAW | 180–300 | 24–32 | Medium | CO₂ or Self-Shielded |
(2) Heat Input Control
Max Heat Input: ≤ 2.5 kJ/mm (to avoid HAZ brittleness).
Technique:
Use stringer beads (avoid excessive weaving).
Multi-pass welding for thick plates.
5. Post-Welding Treatment
(1) Cooling Rate
Allow natural cooling (avoid quenching).
(2) Post-Weld Heat Treatment (PWHT, if needed)
Stress Relieving: 550–650°C (for critical applications).
(3) Surface Finishing
Grinding: Smooth weld seams to match base metal.
Patina Formation:
Weathering steel will develop rust over time (no need for paint).
If painting is required, use weathering-compatible primers.
6. Inspection & Quality Control
Visual Inspection (VT): Check for cracks, porosity, undercut.
NDT (if required):
Dye Penetrant (PT) for surface defects.
Ultrasonic (UT) or X-ray (RT) for internal flaws.
Hardness Test: Ensure HAZ hardness ≤ 350 HV.
