Welding Requirements
Filler Metal Selection (Critical)
Matching weathering filler is required to ensure welds develop the same patina and corrosion resistance as the base metal.
SMAW (stick): E7018‑W, E8018‑W (low‑hydrogen, weathering‑grade)
GMAW (MIG): ER70S‑G, ER80S‑G (low‑alloy, weathering‑compatible solid wire)
FCAW: E70T‑5‑W, E80T‑5‑W (flux‑cored, weathering‑grade)
Avoid plain carbon steel fillers (e.g., E7018, ER70S‑6) unless the weld will be fully painted; they will rust differently and break the protective patina.
Welding Process & Parameters
Preferred processes: GMAW (MIG) and SMAW are most common for thin sheets (A606‑2 is typically ≤6 mm)ASTM.
Heat input control: Use low‑to‑moderate heat to minimize distortion and hardening in the heat‑affected zone (HAZ).
Example for 2–4 mm sheet: GMAW with 1.0 mm wire, 120–160 A, 19–21 V, 8–12 L/min shielding gas (80% Ar + 20% CO₂).
Joint design: Use shallow, wide grooves (60–65° included angle) with minimal root gap (1.5–2 mm) to reduce heat input and distortion.
Avoid over‑welding: Excess weld metal increases residual stress and can trap moisture, accelerating corrosion.
Pre‑Weld & Post‑Weld Practices
Cleaning: Remove mill scale, oil, grease, and moisture from the joint and 20‑mm surrounding area before welding. Use a stainless‑steel wire brush (not carbon steel) to avoid contamination.
Preheat: Generally not required for thin A606‑2 (<6 mm) in ambient conditions. Preheat to 50–100°C only for cold environments (<0°C) or thick sections to prevent cold cracking.
Post‑weld treatment:
Remove weld spatter, slag, and discoloration (heat tint) with a wire brush or light grinding-do not over‑grind the HAZ.
Do not paint welds if the structure is to develop a natural patina; allow the weld to weather uniformly with the base metal.
Weld Quality & Corrosion Protection
Welds must be sound, porosity‑free, and crack‑free to maintain the self‑protective oxide layer.
Avoid crevices and tight joints that trap water-design for drainage and air circulation to prevent accelerated corrosion at welds.
