ER4043 vs ER5356: Which Aluminum Welding Wire to Use
ER4043 is the default aluminum wire for 6061 and cast aluminum. ER5356 is required for 5xxx marine alloys and anodized work. The base metal determines which one to use.
Key Differences
| Attribute | ER4043 | ER5356 |
|---|---|---|
| Difference 1 | ER4043 is silicon-alloyed (5% Si) with lower strength but better crack resistance and easier flow | |
| Difference 2 | ER5356 is magnesium-alloyed (5% Mg) with higher strength but more crack-sensitive | |
| Difference 3 | ER4043 does not match anodized color | ER5356 does |
| Difference 4 | ER4043 is 26 ksi tensile | ER5356 is 38 ksi |
Use ER4043 when:
6061, 6063, 3003, and cast aluminum. Most general aluminum repair. Automotive aluminum. When crack resistance matters more than strength. When the weld will not be anodized.
Use ER5356 when:
5052, 5083, 5086 aluminum (required). Marine applications. When the finished weld will be anodized. When fillet weld shear strength is critical. Boat hulls, fuel tanks, structural marine.
How ER4043 and ER5356 Work Together
The AWS Aluminum Filler Metal Selection Chart (in A5.10) is the definitive reference. For 6061 base metal, both 4043 and 5356 are acceptable, but 4043 is preferred for crack resistance and 5356 is preferred for strength and anodized color.
Common Mistake With ER4043
Using ER4043 on 5xxx alloys. The silicon-magnesium interaction at the weld boundary creates a low-melting eutectic that causes hot cracking.
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Data sourced from AWS A5.10.