Base metals
1xxx, 3xxx (3003, 3103) and lower-magnesium 6xxx (6061, 6063). The base metal solidus must be comfortably above 604 °C.
Aerospace · Al-12Si filler
4047 Aerospace Aluminium Wire for Brazing and Welding
4047 is a near-eutectic aluminium-silicon alloy (11 – 13 % Si) that melts at about 577 – 582 °C. As wire it has two aerospace jobs: brazing filler to SAE AMS 4185 (AWS BAlSi-4) for heat exchangers and ducting, and ER4047 welding filler where low shrinkage and high fluidity prevent cracking. Metline supplies 4047 wire and rod worldwide with lot certificates.
- Alloy
- 4047 (Al-12Si)
- Specs
- AMS 4185 · AWS A5.8 BAlSi-4 · A5.10 ER4047
- Melting range
- about 577 – 582 °C
- Heat-treatable
- No
What 4047 wire does
At 12.6 % silicon, aluminium and silicon form a eutectic that melts at 577 °C. 4047 sits almost exactly on that point, so it melts over a narrow range, flows freely and solidifies with very little shrinkage.
For brazing, that low melting point is the whole point: 4047 melts about 60 – 80 °C below common base alloys such as 3003, 6061 and 6063, so joints can be filled by capillary action without melting the parts. For welding, the high silicon gives the most fluid weld pool and the lowest hot-cracking tendency of the common fillers, which is useful on crack-sensitive joints and leak-tight fillets.
4047 is not heat-treatable and is not a structural wire. Listings that offer it in T4, T6 or T6511 tempers are wrong; wire is supplied as drawn or annealed. Claims that 4047 wire is used for turbine blades, airframe structure or electrical cable are also wrong.
4047 chemical composition (wt %)
| Element | Limit |
|---|---|
| Silicon (Si) | 11.0 – 13.0 |
| Iron (Fe) | 0.8 max |
| Copper (Cu) | 0.30 max |
| Manganese (Mn) | 0.15 max |
| Magnesium (Mg) | 0.10 max |
| Zinc (Zn) | 0.20 max |
| Beryllium (Be) | 0.0003 max (welding grades) |
| Others, each / total | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
Physical properties (typical)
- Density
- about 2.66 g/cm³
- Solidus / liquidus
- about 577 / 582 °C
- Brazing temperature range
- about 582 – 604 °C
- Thermal expansion
- about 20 µm/m·°C, lower than most aluminium alloys
The melting point is about 577 – 582 °C, not 1080 °C as some older pages state.
Brazing with 4047 (BAlSi-4)
AMS 4185 covers 12Si brazing filler in wire, sheet, foil and other forms, and its later revisions align with AWS A5.8, where the same alloy is classified BAlSi-4. It has a long history in dip (molten flux) brazing and is used for torch, furnace and controlled-atmosphere brazing.
Flux
Torch and dip brazing need a suitable aluminium brazing flux; remove chloride flux residues completely after brazing to avoid corrosion.
Joint design
Lap and tee joints with clearances of about 0.1 – 0.25 mm fill well by capillary flow.
Magnesium
Base metals with more than about 1 % Mg are hard to flux-braze; vacuum brazing uses Mg-bearing fillers instead.
Welding with ER4047
ER4047 is used where 4043 still cracks, where a leak-tight fillet matters more than strength, or where the base metal already contains a lot of silicon (Al-Si castings). It gives a bright, smooth bead and less distortion.
- Use on 6xxx and 3xxx alloys and Al-Si castings; not on 5xxx alloys with more than about 2.5 % Mg
- Expect slightly lower ductility than 4043 and a dark grey colour after anodising
- Common in heat-exchanger, tank and duct fabrication where joints must be pressure-tight
Specifications
| Document | Designation | Note |
|---|---|---|
| SAE AMS 4185 | Filler metal, aluminium brazing, 12Si (4047) | Aerospace brazing specification |
| AWS A5.8 | BAlSi-4 | Brazing filler classification |
| AWS A5.10 | ER4047 / R4047 | Welding filler classification |
| ISO 18273 | S Al 4047A (AlSi12(A)) | International welding classification |
| QQ-B-655 (legacy) | Aluminium-silicon brazing filler | Older US federal document, replaced by AMS and AWS |
Sizes and packing
4047 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.
Fine brazing wire, rings and preforms are also available; see our brazing rings and preforms page.
- 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 4047 wire
- Heat exchangers: brazed oil coolers, fuel-oil heat exchangers and avionics cold plates
- Ducting: brazed and welded environmental-control ducts and manifolds
- Tanks and housings: leak-tight fillet welds on 3xxx and 6xxx parts
- Castings: repair of high-silicon castings where low shrinkage reduces cracking
- Ground equipment: brazed and welded cooling units and fluid systems
How to order 4047 wire
- SpecifyAlloy and temper, diameter and form, quantity and the governing specification with its revision (AMS 4185, AWS A5.8 BAlSi-4 or AWS A5.10 ER4047).
- 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 4185 – Filler Metal, Aluminum Brazing, 12Si (4047)
- AWS A5.8/A5.8M – Specification for Filler Metals for Brazing and Braze Welding
- AWS A5.10/A5.10M – Welding Consumables: Wires and Rods for Aluminum and Aluminum-Alloys, Classification
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
4047 aerospace aluminium (aluminum) wire: questions
Is 4047 wire for brazing or welding?
Both. As BAlSi-4 to AMS 4185 or AWS A5.8 it is a brazing filler; as ER4047 to AWS A5.10 it is a welding filler for crack-sensitive and leak-tight joints.
Can 4047 wire be heat-treated to T6?
No. 4047 is not heat-treatable. Wire is supplied as drawn or annealed; T tempers do not apply.
What is the melting point of 4047?
About 577 – 582 °C. Brazing is normally done at about 582 – 604 °C.
What is the difference between 4047 and 4043?
4047 has about 12 % silicon against 5 % in 4043, so it melts lower, flows more and shrinks less. 4043 gives slightly better ductility in welds; only 4047 is used as a brazing filler.
Do you supply 4047 wire outside India?
Yes. Metline ships 4047 wire, rod and preforms worldwide with lot certificates.
Need 4047 brazing or welding wire?
Send the diameter, form, quantity and specification. We will confirm availability and documentation.
