4047 Aluminium Coil, Strip and Sheet
4047 is an aluminium-silicon alloy with 11 – 13 % silicon, close to the eutectic composition, so it melts over a narrow range of about 577 – 582 °C, roughly 50 – 70 °C below the 3xxx and 6xxx alloys it joins. In coil and strip form it is used as brazing filler foil, as the cladding layer on brazing sheet and as feedstock for stamped brazing preforms. Metline supplies 4047 coil, slit strip and sheet, worldwide.
- Silicon
- 11.0 – 13.0 %
- Melting range
- About 577 – 582 °C
- Forms
- Coil, strip, foil, sheet, discs
- Use
- Brazing filler and cladding
What 4047 strip is used for
4047 is not a structural alloy. Its value is its melting behaviour: with about 12 % silicon it sits almost exactly at the aluminium-silicon eutectic (577 °C), so it turns from solid to liquid over just a few degrees and flows freely into capillary joints.
That makes 4047 the filler of choice for brazing aluminium heat exchangers, where thousands of fin-to-tube joints must form at once in a furnace. It is supplied in three ways: as thin foil or strip placed between parts, as a cladding layer roll-bonded onto a 3003 or similar core to make brazing sheet, and as strip stamped into washers, rings and other preforms.
Because 4047 is also the composition of ER4047 welding wire, the alloy is familiar to welders: it gives fluid weld pools and low shrinkage, which reduces hot cracking in castings and 6xxx joints. For brazing, though, the key property is the narrow melting range and the large margin below the melting point of the parts being joined.
4047 chemical composition (wt %)
| Element | Minimum | Maximum | Comment |
|---|---|---|---|
| Silicon (Si) | 11.0 | 13.0 | Lowers melting point to the eutectic |
| Iron (Fe) | — | 0.8 | Impurity |
| Copper (Cu) | — | 0.30 | Impurity |
| Manganese (Mn) | — | 0.15 | |
| Magnesium (Mg) | — | 0.10 | Kept low: magnesium interferes with fluoride fluxes |
| Zinc (Zn) | — | 0.20 | |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder |
Aluminum Association limits for 4047. The European EN AW-4047A (AlSi12(A)) has very similar limits. AWS A5.8 classifies the same composition as brazing filler BAlSi-4.
Melting and physical properties
Physical properties (typical)
- Solidus / liquidus
- About 577 °C / 582 °C
- Recommended brazing temperature
- About 582 – 604 °C (AWS A5.8 range for BAlSi-4)
- Density
- 2.66 g/cm³
- Thermal conductivity
- About 140 W/m·K
- Coefficient of thermal expansion
- About 21 µm/m·°C
Mechanical properties of 4047 strip are rarely specified because the alloy melts during use. Strip is supplied in O (annealed) temper where it will be stamped or formed into preforms, and in harder H1x tempers where flatness and stiffness during handling matter. Ask for the temper that suits your punching or interleaving process.
4047 compared with other aluminium brazing alloys
| Alloy | Si % | Melting range | Main use |
|---|---|---|---|
| 4343 (BAlSi-2) | 6.8 – 8.2 | About 577 – 613 °C | Cladding on brazing sheet for controlled-atmosphere brazing; less erosion of thin fins |
| 4045 (BAlSi-5) | 9.0 – 11.0 | About 577 – 591 °C | Cladding and filler; more fluid than 4343 |
| 4047 (BAlSi-4) | 11.0 – 13.0 | About 577 – 582 °C | Most fluid; filler foil, preforms and cladding where large fillets are needed |
| 4004 / 4104 | 9 – 10.5, with 1 – 2 % Mg (+Bi in 4104) | About 559 – 591 °C | Vacuum brazing; magnesium acts as a getter |
The trade-off is fluidity against erosion. 4047 flows most freely and builds the largest fillets, but the extra silicon also dissolves more of the parent metal, so very thin fins (below about 0.1 mm) are usually clad with 4343 instead. For vacuum brazing, a magnesium-bearing filler such as 4004 or 4104 is used because there is no flux to break the oxide film.
4047 coil and strip sizes
Supply range
- Thickness
- Foil from about 0.05 mm; strip and sheet up to several millimetres
- Width
- Slit strip from a few millimetres to wide coil, to suit your press or interleaving line
- Inner diameter
- 75, 150 or 300 mm for narrow strip; 405 – 508 mm for wide coil
- Temper
- O for stamping and forming; H14 – H18 for flat interleaving foil
- Surface
- Clean, degreased, free from oil residues that would contaminate brazing
- Other forms
- 4047 discs, rod, wire and clad brazing sheet
Approximate weight of a 4047 coil on a 508 mm core at 2.66 g/cm³:
| Coil width (mm) | OD 1000 mm (kg) | OD 1200 mm (kg) | OD 1500 mm (kg) |
|---|---|---|---|
| 500 | 775 | 1235 | 2081 |
| 1000 | 1550 | 2469 | 4161 |
| 1250 | 1938 | 3087 | 5202 |
| 1500 | 2325 | 3704 | 6242 |
Using 4047 strip in brazing
- Choose the processControlled-atmosphere brazing (CAB) with non-corrosive fluoride flux, or flame and induction brazing with flux. For vacuum furnaces use a magnesium-bearing filler instead.
- Check the parent metalParts should have a solidus well above 600 °C: 1xxx, 3xxx and low-magnesium 6xxx alloys (e.g. 6063, 6951). 6061 and 5xxx alloys are difficult.
- Place the fillerInterleave foil, place preforms or use clad sheet so filler sits next to every joint. A gap of about 0.05 – 0.25 mm suits capillary flow.
- BrazeHeat to about 590 – 605 °C, hold just long enough for the filler to flow, and cool. Over-temperature or long holds erode thin parts.
Standards and designations
| System | Designation |
|---|---|
| Aluminum Association | 4047 |
| UNS | A94047 |
| AWS A5.8 (brazing filler) | BAlSi-4 |
| AWS A5.10 (welding wire) | ER4047 / R4047 |
| European (EN) | EN AW-4047A / AlSi12(A) |
| ISO 17672 (brazing) | Al 112 |
| Japan (JIS) | A4047 |
Brazing filler compositions are given by AWS A5.8 and ISO 17672; wire by AWS A5.10 and ISO 18273. Sheet and strip tolerances are normally agreed to EN 485-4 or ASTM B209 tables.
How to order 4047 coil and strip
- SpecifyAlloy (4047 or 4047A), thickness, width, temper, coil ID, maximum OD or weight, and surface cleanliness requirements.
- QuoteWe confirm availability, tolerance, certificate and terms (EXW, FOB, CIF or DAP).
- DocumentMill test certificate to EN 10204 3.1 with chemical analysis of the lot.
- ShipCoils sealed in moisture-barrier wrap with desiccant, on pallets or in wooden cases.
References and standards
- AWS A5.8M/A5.8 – Specification for Filler Metals for Brazing and Braze Welding (BAlSi-4)
- ISO 17672 – Brazing: Filler metals
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
- EN 573-3 – Chemical composition and form of wrought products
4047 aluminium strip: frequently asked questions
What is the melting point of 4047 aluminium?
About 577 – 582 °C. It is close to the aluminium-silicon eutectic, so it melts over a very narrow range, which is why it flows so well as a brazing filler.
What is the difference between 4047 and 4045?
4047 has 11 – 13 % silicon and 4045 has 9 – 11 %. 4047 melts over a narrower range and is more fluid; 4045 melts up to about 591 °C and erodes thin parent metal slightly less.
Can 4047 strip be used for structural parts?
Not normally. It is a filler and cladding alloy. For structural aluminium sheet use 3xxx, 5xxx or 6xxx alloys.
Is 4047 suitable for vacuum brazing?
Not on its own. Vacuum brazing needs a magnesium-bearing filler such as 4004 or 4104 to break the oxide film. 4047 is used with flux, in CAB furnaces or for flame and induction brazing.
Can you supply 4047 as discs or preforms?
Yes. 4047 discs and stamped preforms are available, as are rod, wire and clad brazing sheet in the same alloy.
Need 4047 strip or foil?
Send thickness, width, temper and quantity. We will confirm availability and quote a delivered price.
