Materials
What filler wire or rod for aluminium?
Quick answer
For aluminium use ER4043 (general) or ER5356 (stronger, better on 5xxx alloys). Matching filler to the parent grade is the rule — mismatched filler either cracks, corrodes or underperforms the base metal.
Filler selection
- Process choice: AC TIG for quality, MIG with a spool gun for speed, 1.6 mm+ only
- Filler: ER4043 (general) or ER5356 (stronger, better on 5xxx alloys)
- Prep: stainless brush the oxide layer off right before welding — it reforms within hours
Why matching matters
Filler chemistry controls strength, corrosion behaviour and crack resistance. The classic Australian mistake is welding 316 stainless with 308 filler — it works, until the job sits in a coastal or chemical environment and the weld rusts first. When in doubt, weld with a filler at least as alloyed as the parent.