Electrode comparison
ER4043 vs ER5356
ER4043 is more crack resistant and easier to run; ER5356 is stronger, feeds better and is the only one of the two that anodizes to a colour match.
ER4043 vs ER5356 at a glance
| ER4043 | ER5356 | |
|---|---|---|
| AWS specification | AWS A5.10/A5.10M | AWS A5.10/A5.10M |
| Process | TIG (GTAW) / MIG (GMAW) | TIG (GTAW) / MIG (GMAW) |
| Form | Solid wire / rod | Solid wire / rod |
| Tensile strength (min) | 27 ksi | 38 ksi |
| Yield strength (min) | 16 ksi | 17 ksi |
| Elongation (min) | 8% | 17% |
| Impact toughness | Not applicable | Not applicable |
| Polarity | AC (GTAW), DCEP (GMAW) | AC (GTAW), DCEP (GMAW) |
| Positions | Flat, Horizontal, Vertical, Overhead | Flat, Horizontal, Vertical, Overhead |
| Penetration | Medium | Medium |
| Deposition rate | High on MIG, moderate on TIG | High on MIG, moderate on TIG |
| Coating / core | None — bare wire or rod | None — bare wire or rod |
| Slag | None; remove the oxide layer mechanically before welding | None; mechanical oxide removal required before welding |
| Shielding gas | 100% argon | 100% argon |
| Storage | Keep sealed and dry. Aluminum filler grows an oxide layer and picks up moisture that turns into weld porosity. | Sealed and dry. Magnesium-bearing aluminum oxidizes readily and moisture becomes weld porosity. |
| Primary use | Welding and repairing 6061 structures, frames and extrusions | Boat hulls, marine structures and 5083/5086 plate |
Which should you use?
This is the most common aluminium filler question and it has a clear framework. ER4043's 5% silicon lowers the melting point and widens the freezing range, making it fluid, forgiving and resistant to hot cracking — the right choice for castings, restrained 6061 joints and anyone learning aluminium. ER5356's 5% magnesium gives roughly 40% higher tensile strength and much better fillet shear strength, feeds more reliably through a long MIG gun because the wire is stiffer, and anodizes to a near match instead of going dark grey. The catch is that 5356 should not be used in sustained service above about 150 °F, and it is a poor choice on high-silicon castings.
Choose ER4043 when
- Aluminium castings, especially 356 and A356
- Restrained 6061 joints where cracking is the risk
- Service temperatures above about 150 °F
- Learning aluminium — the more forgiving puddle
Choose ER5356 when
- 5xxx base metals such as 5052, 5083 and 5086
- Structural joints where fillet shear strength governs
- Parts that will be anodized
- Long MIG guns and push-pull systems where feedability matters
Amperage compared
| Diameter | ER4043 | ER5356 |
|---|---|---|
| 0.030 in (0.8 mm) MIG | 60–175 A | 60–175 A |
| 0.035 in (0.9 mm) MIG | 70–200 A | 70–200 A |
| 3/64 in (1.2 mm) MIG | 100–260 A | 100–260 A |
| 1/16 in (1.6 mm) TIG | 40–90 A | 40–90 A |
| 3/32 in (2.4 mm) TIG | 80–130 A | 80–130 A |
| 1/8 in (3.2 mm) TIG | 120–190 A | 120–190 A |
Ranges are typical starting points. Diameters listed for only one electrode are shown as — for the other.
ER4043 vs ER5356 — common questions
Which filler is stronger, 4043 or 5356?
ER5356, at roughly 38 ksi tensile against 27 ksi for ER4043, with a substantially higher shear strength in fillet welds. That is why structural and marine work specifies 5356.
Which aluminium filler should I use on 6061?
Either works. ER4043 if the joint is restrained or crack-sensitive, or if the part will run hot. ER5356 if the joint's strength governs the design or the part will be anodized.
Why does 4043 look dark after anodizing?
Silicon in the weld metal reacts differently in the anodizing bath and turns the bead dark grey to black against the base metal. ER5356 has no silicon addition and comes out far closer in colour.
Why is ER5356 easier to feed?
It is a harder, stiffer alloy. Soft 4043 wire buckles and birdnests in the drive rolls on a long gun, while 5356 pushes through more reliably.
Full specifications
ER4043
AWS A5.10/A5.10M
ER4043 is the 5% silicon aluminum filler — fluid, crack-resistant and the default choice for welding 6061 and aluminum castings.
ER5356
AWS A5.10/A5.10M
ER5356 is the 5% magnesium aluminum filler — stronger than ER4043, stiffer to feed, and the choice when the joint must carry load or be anodized.