This WPS covers GTAW (TIG) welding of 1/4" 6061-T6 aluminum plate in the 2G (horizontal) position per AWS D1.2 Structural Welding Code — Aluminum. Aluminum GTAW requires AC current to break the oxide layer, with 100% argon shielding and ER4043 filler for the best combination of crack resistance and strength. IronKit generated this WPS for a marine fabrication shop that builds custom aluminum boat structures and trailer frames. The key aluminum-specific details — AC balance and frequency settings, no preheat requirement (6061 welds at room temperature), and the T6 temper degradation note — are all addressed in the procedure.
Frequently Asked Questions
Why does aluminum TIG require AC current?
Aluminum forms a tenacious oxide layer (Al2O3) with a melting point of 3,700°F — far above the 1,200°F melting point of the base metal. The electrode-positive half-cycle of AC breaks up this oxide layer (called "cleaning action"), while the electrode-negative half-cycle provides penetration. DC cannot break the oxide and will result in lack of fusion.
What is the T6 temper loss in the HAZ?
The heat-affected zone of 6061-T6 reverts to approximately T4 condition, losing about 40% of its tensile strength. This is permanent — the only recovery is solution heat treatment and re-aging (T6 temper), which is impractical for welded structures. Structural designs must use the reduced HAZ properties.
Why ER4043 filler instead of ER5356?
ER4043 has lower crack sensitivity on 6061 base metal and produces a brighter, more fluid weld puddle. ER5356 provides higher as-welded shear strength but is more prone to cracking on 6xxx-series alloys. For structural 6061, ER4043 is generally preferred per AWS D1.2 guidance.
Does IronKit generate AWS D1.2 WPS documents?
Yes. IronKit supports AWS D1.2 with aluminum-specific parameters including AC balance, frequency, M-group designations, and the HAZ temper degradation notes that other WPS generators miss.