ER4043 Aerospace Aluminium Welding Wire
ER4043 is the 5 % silicon aluminium filler wire, made for aerospace orders to SAE AMS 4190 and classified in AWS A5.10. It flows well and resists hot cracking, which makes it the standard filler for 6xxx alloys, Al-Mn alloys and Al-Si castings in ducts, tanks, brackets and ground equipment. Metline supplies ER4043 MIG wire and TIG rod with lot certificates, worldwide.
- Alloy
- 4043 (Al-5Si)
- Specs
- AMS 4190 · AWS A5.10 ER4043
- Base metals
- 6xxx, 3xxx, Al-Si castings
- Forms
- MIG spools, TIG rod
Why 4043 is the default filler for many aerospace welds
Silicon lowers the melting point of the weld pool and makes it more fluid. At 5 % silicon, 4043 fills the joint smoothly, wets the edges well and shrinks less as it solidifies, so it is much less prone to solidification cracking than pure aluminium or the base alloy itself.
That matters most with 6061, 6063 and 6082, which crack easily if welded with matching filler. 4043 dilutes the weld enough to move it out of the crack-sensitive range. It is also the usual choice for 3003 and 3A21 tanks and ducts, and for A356 and 356 castings welded without later heat treatment.
It has limits. 4043 is not used on 5xxx alloys with more than about 2.5 % magnesium (5083, 5086, 5456), because Mg2Si forms in the weld and makes it brittle. Its as-welded shear strength is lower than 5356, and anodised welds turn dark grey. Knowing those limits is the key to using it well.
4043 chemical composition (wt %)
| Element | Limit |
|---|---|
| Silicon (Si) | 4.5 – 6.0 |
| Iron (Fe) | 0.8 max |
| Copper (Cu) | 0.30 max |
| Manganese (Mn) | 0.05 max |
| Magnesium (Mg) | 0.05 max |
| Zinc (Zn) | 0.10 max |
| Titanium (Ti) | 0.20 max |
| Beryllium (Be) | 0.0003 max |
| Others, each / total | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
Physical properties (typical)
- Density
- about 2.68 g/cm³
- Melting range
- about 574 – 632 °C
- Thermal expansion
- about 22 µm/m·°C (20 – 100 °C)
- Electrical conductivity
- about 42 % IACS
What strength to expect from a 4043 weld
A filler wire does not have a single "strength" in service; the joint does. In 6061-T6, the heat-affected zone softens and usually controls the joint, so a groove weld made with 4043 typically breaks at about 190 – 210 MPa as welded. Design codes such as AWS D1.2 use a minimum of about 165 MPa (24 ksi) for 6061-T6 groove welds.
| Situation | Advice |
|---|---|
| 6061 / 6082 groove weld, as welded | 4043 or 5356 both acceptable; 4043 gives better crack resistance and fluidity |
| Fillet welds carrying shear | 5356 gives noticeably higher fillet shear strength than 4043 |
| Assembly heat-treated after welding | 4643 responds better than 4043 because it contains magnesium |
| Service above about 65 °C | 4043 is preferred over 5xxx fillers, which can become sensitised |
| Anodised appearance matters | Avoid 4043 (grey weld); 5356 gives a closer colour match |
| 5083 / 5086 / 5456 base metal | Do not use 4043; use 5356, 5183 or 5556 |
Older listings quote tensile strengths for 4043 wire in H12, H14 and H19 tempers. Those figures describe the drawn wire, not the weld, and are not a basis for joint design.
Specifications for 4043 wire
| Document | Designation | Note |
|---|---|---|
| SAE AMS 4190 | 4043 welding wire, 5.2Si | Aerospace purchasing specification |
| AWS A5.10 | ER4043 (wire) / R4043 (rod) | Commercial classification |
| ISO 18273 | S Al 4043A (AlSi5(A)) | International classification |
| BS 2901-4 (legacy) | N21 | Older British designation, now replaced by ISO 18273 |
| UNS | A94043 |
Sizes, packing and storage
ER4043 wire supply range
- MIG (GMAW) wire
- Layer-wound spools, typically 0.8, 1.0, 1.2 and 1.6 mm diameter; 100, 200 and 300 mm spools and larger drums
- TIG (GTAW) rod
- Straight cut lengths, typically 1.6, 2.0, 2.4, 3.2, 4.0 and 5.0 mm diameter, about 914 or 1000 mm long
- Condition
- Hard-drawn (H18 / H19-type) for feeding; softer tempers for other wire uses on request
- Surface
- Shaved or cleaned, free of drawing lubricant, oxide and moisture
- Packing
- Sealed bags or cans with desiccant, cartons on pallets; tube packs for TIG rod
- Documents
- EN 10204 3.1 certificate or certificate of conformity with chemical analysis per lot
Diameter tolerance, cast and helix of spooled wire follow AWS A5.10 or the AMS document named on the order.
- Storage: keep wire sealed in its original packing in a dry, heated store; aluminium oxide hydrates and causes weld porosity
- Open spools: return part-used spools to a sealed bag with desiccant, or to a wire cabinet
- Cleaning base metal: degrease, then remove the oxide with a dedicated stainless-steel brush shortly before welding
- Feeding: use U-groove drive rolls, a PTFE or nylon liner and contact tips sized for aluminium
- Traceability: record the lot number from the label on the weld record, so the certificate links to the joint
Aerospace uses of 4043
- Ducting and tanks: 3003, 3A21 and 6061 ducts, reservoirs and tanks
- Brackets and frames: 6061 and 6082 welded secondary structure, racks and supports
- Castings: repair and joining of 356 and A356 castings where no post-weld heat treatment follows
- Ground support equipment: stands, steps, carts and trailers in 6xxx extrusions
- Dissimilar joints: 6xxx extrusions to Al-Si castings
How to order ER4043
- SpecifyAlloy and temper, diameter, spool size or rod length, quantity and the governing specification with its revision (AMS 4190 or AWS A5.10 ER4043).
- ConfirmWe confirm the specification can be met, the tolerance class, test requirements and delivery terms (EXW, FOB, CIF or DAP).
- InspectMaterial is checked for dimensions and surface condition; any extra tests named on the order are carried out or arranged.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing chemistry and mechanical results, traceable to the cast or lot number.
- Pack and shipExport packing in sealed, moisture-protected cases or on pallets, shipped by sea or air to your port or door.
References and standards
- SAE AMS 4190 – Aluminum Alloy Welding Wire, 5.2Si (4043)
- AWS A5.10/A5.10M – Welding Consumables: Wires and Rods for Aluminum and Aluminum-Alloys, Classification
- ISO 18273 – Welding consumables: wire electrodes, wires and rods for welding of aluminium and aluminium alloys
- AWS D1.2 – Structural Welding Code: Aluminum
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
ER4043 aerospace aluminium (aluminum) wire: questions
Can ER4043 be used on 5083 or 5086?
No. With high-magnesium 5xxx alloys, 4043 forms brittle Mg2Si in the weld. Use 5356, 5183 or 5556 instead.
Is 4043 or 5356 better for 6061?
Both work. 4043 resists cracking and flows better; 5356 gives higher fillet shear strength and a better anodised colour match. Choose by joint type and finish.
Is ER4043 heat-treatable after welding?
Only slightly, because it contains almost no magnesium. For welds that will be solution treated and aged, 4643 is the better filler.
What is the aerospace specification for 4043 wire?
SAE AMS 4190. Commercial orders normally use AWS A5.10 ER4043 or ISO 18273 S Al 4043A.
Do you ship ER4043 wire worldwide?
Yes. Metline supplies ER4043 from Mumbai to customers worldwide, in sealed packing with lot certificates.
Need ER4043 wire or rod?
Send diameter, form, quantity and specification. We will confirm availability and documents.
