ER4043 vs ER5356 Aluminum Welding Wire: How to Choose
ER4043 and ER5356 are the two aluminum filler wires you'll choose between for almost any aluminum MIG or TIG job. Pick wrong and you can get cracking, a color mismatch after anodizing, or a weld that's weaker than the base metal. Here's how to choose.
Quick answer
| ER4043 (Al-5%Si) | ER5356 (Al-5%Mg) | |
|---|---|---|
| Best for | 6000-series, castings, general fab, easy running | 5000-series, marine, structural, anodized parts |
| Strength | Lower | Higher |
| Crack resistance | Excellent (more forgiving) | Good |
| Anodizing color match | Turns gray/dark | Stays close to base color |
| Feedability | Softer — very easy to feed | Stiffer — feeds well, better for spool guns/push-pull |
ER4043 — the easy, forgiving filler
ER4043 is an aluminum-silicon (Al-5%Si) wire that runs smooth, wets in nicely, and resists cracking thanks to its silicon content and lower melting point. It's the go-to for 6061 and other 6000-series alloys, cast aluminum, and general fabrication where appearance after anodizing isn't critical. The trade-off: lower strength and it darkens (turns grayish) if the part is later anodized.
ER5356 — the strong, anodize-friendly filler
ER5356 is an aluminum-magnesium (Al-5%Mg) wire with higher tensile and shear strength. It's the standard for 5000-series alloys, marine and saltwater environments, structural aluminum, and anything that will be anodized (it keeps a color close to the base metal). It's a bit stiffer to feed, so a spool gun or push-pull setup helps on longer runs.
How to choose
- Welding 6061 / 6000-series or castings, want easy running → ER4043
- Welding 5052 / 5083 / 5000-series, marine, or high-strength → ER5356
- Part will be anodized and color matters → ER5356
- Crack-sensitive joint, want the most forgiving puddle → ER4043
ER4043 16 lb Spool → · All Aluminum MIG Wire → · Aluminum TIG Rod →
FAQ
Can I use ER4043 on 5052 aluminum?
It's not recommended — ER4043 on high-magnesium 5000-series alloys can form a brittle compound. Use ER5356 for 5052/5083.
Which is stronger, ER4043 or ER5356?
ER5356 has higher tensile and shear strength.
Why did my ER4043 weld turn dark after anodizing?
The silicon in ER4043 darkens when anodized. Use ER5356 for a closer color match.
Welding produces fumes and UV radiation. Always follow proper safety practices, ventilation, and PPE, and weld to your applicable procedure or code.