Drive system
Use U-groove drive rolls and the lowest tension that feeds without slipping. V-knurled rolls for steel shave aluminium wire and cause bird-nesting.
Filler metal guide
Aluminium Welding Wire: Grades, Filler Selection and MIG/TIG Practice
Aluminium welding wire is the filler metal used in MIG (GMAW) welding, where it is fed continuously as the electrode, and in TIG (GTAW) welding, where it is added as straight rod or by an automatic feeder. Two families cover almost every job: Al-Si fillers (4043, 4943, 4047, 4643) for crack resistance and fluidity, and Al-Mg fillers (5356, 5183, 5556, 5554) for strength, ductility and seawater resistance. This guide explains how to choose between them for each base alloy and how to get sound welds.
- Main grades
- ER4043, ER5356, ER5183, ER4943
- Diameters
- 0.8 – 2.4 mm (0.030 – 3/32 in)
- Processes
- MIG / GMAW, TIG / GTAW
- Standards
- AWS A5.10 · ISO 18273
What makes aluminium welding wire different
Aluminium is harder to weld than steel for four reasons: it conducts heat away about five times faster, its tough oxide skin melts at over 2,000 °C while the metal melts near 600 °C, molten aluminium dissolves hydrogen that becomes porosity on freezing, and many high-strength alloys crack when they solidify. Filler wire is the main tool for managing the last two problems.
The filler is never just "aluminium". Its silicon or magnesium content is chosen so that, once mixed with melted base metal in the weld pool, the final weld chemistry avoids the composition range most prone to solidification (hot) cracking, gives the strength the joint needs and behaves well in service. That is why a 6061 structure is welded with 4043 or 5356 and never with 6061 wire: an autogenous or matching-composition 6061 weld sits right in the crack-sensitive range.
Wire quality matters as much as alloy. Aluminium wire is soft, so diameter consistency, a clean and smooth surface free of drawing lubricant and oxide, precise layer winding and moisture-proof packaging decide whether it feeds smoothly and welds without porosity. Metline supplies MIG wire and TIG filler rod in the standard AWS and ISO grades, with batch certificates.
How aluminium filler metals are classified
The two main specifications are AWS A5.10/A5.10M (used in the Americas and on many international projects) and ISO 18273 (used in Europe and much of Asia, published in Europe as EN ISO 18273). AWS uses the prefix ER for wire or rod that can be an electrode or a filler rod, and R for rod used only as filler. ISO uses S Al followed by the alloy number, and sometimes the chemical symbol, for example S Al 5183 (AlMg4,5Mn0,7(A)).
| AWS A5.10 | ISO 18273 | Alloy family | Main role |
|---|---|---|---|
| ER1100 | S Al 1100 (Al99,0Cu) | Commercially pure | Welding 1xxx and 3003 where conductivity and corrosion resistance matter |
| ER4043 | S Al 4043 / 4043A (AlSi5) | Al-5 % Si | General-purpose filler for 6xxx, castings and dissimilar joints |
| ER4943 | S Al 4943 | Al-Si-Mg | Higher-strength alternative to 4043 with similar crack resistance |
| ER4047 | S Al 4047A (AlSi12) | Al-12 % Si | Low melting, very fluid; leak-tight joints, castings, brazing-type work |
| ER4643 | S Al 4643 | Al-Si-Mg | Welds on 6xxx parts that are heat-treated after welding |
| ER5356 | S Al 5356 (AlMg5Cr(A)) | Al-5 % Mg | Most-used general filler for 5xxx and 6xxx |
| ER5183 | S Al 5183 (AlMg4,5Mn0,7(A)) | Al-Mg-Mn | Higher strength for 5083, 5086 marine and cryogenic structures |
| ER5556 | S Al 5556 / 5556A | Al-Mg-Mn | Highest-strength 5xxx filler for 5456 and high-strength joints |
| ER5554 | S Al 5554 (AlMg2,7Mn) | Al-2.7 % Mg | For 5454 and parts in service above 65 °C |
| ER2319 | S Al 2319 | Al-Cu | Welding 2219 aerospace and cryogenic tankage |
Under AWS A5.01 the purchaser can also specify the level of lot testing and certification. For coded fabrication, such as AWS D1.2 structures, ISO 9606-2 welder qualification or classification-society marine work, check that the filler grade and the manufacturer’s product approval are acceptable to the inspector before ordering.
Chemical composition of common welding wires (wt %)
Limits summarised from AWS A5.10. Single values are maximums. Aluminium is the remainder. Beryllium is limited to 0.0003 % in all aluminium filler metals; it is not shown below.
| Grade | Si | Fe | Cu | Mn | Mg | Cr | Zn | Ti |
|---|---|---|---|---|---|---|---|---|
| ER4043 | 4.5 – 6.0 | 0.80 | 0.30 | 0.05 | 0.05 | — | 0.10 | 0.20 |
| ER4943 | 5.0 – 6.0 | 0.40 | 0.10 | 0.05 | 0.10 – 0.50 | — | 0.10 | 0.15 |
| ER4047 | 11.0 – 13.0 | 0.80 | 0.30 | 0.15 | 0.10 | — | 0.20 | — |
| ER4643 | 3.6 – 4.6 | 0.80 | 0.10 | 0.05 | 0.10 – 0.30 | — | 0.10 | 0.15 |
| ER5356 | 0.25 | 0.40 | 0.10 | 0.05 – 0.20 | 4.5 – 5.5 | 0.05 – 0.20 | 0.10 | 0.06 – 0.20 |
| ER5183 | 0.40 | 0.40 | 0.10 | 0.50 – 1.0 | 4.3 – 5.2 | 0.05 – 0.25 | 0.25 | 0.15 |
| ER5556 | 0.25 | 0.40 | 0.10 | 0.50 – 1.0 | 4.7 – 5.5 | 0.05 – 0.20 | 0.25 | 0.05 – 0.20 |
| ER5554 | 0.25 | 0.40 | 0.10 | 0.50 – 1.0 | 2.4 – 3.0 | 0.05 – 0.20 | 0.25 | 0.05 – 0.20 |
Always check the current edition of AWS A5.10 or ISO 18273 and the certificate for the lot; individual producers may work to narrower internal ranges.
Two further fillers appear on specialist jobs. 5087 is an Al-Mg-Mn filler with a zirconium addition that refines the weld grain and lowers hot-cracking sensitivity, used in shipbuilding and rail vehicles under ISO 18273. 5754-type filler (around 3 % Mg) is sometimes used to match 5754 sheet. Both are ordered by their ISO designation.
How the main fillers compare
| Property | 4043 | 4943 | 4047 | 5356 | 5183 | 5556 |
|---|---|---|---|---|---|---|
| Hot-crack resistance | Excellent | Excellent | Excellent | Good | Good | Good |
| Fluidity / wetting | Very good | Very good | Excellent | Fair | Fair | Fair |
| Fillet shear strength, longitudinal (typ.) | 11.5 ksi / 79 MPa | Higher than 4043 | Similar to 4043 | 17 ksi / 117 MPa | 18.5 ksi / 128 MPa | 20 ksi / 138 MPa |
| Ductility | Lower | Lower | Lower | High | High | High |
| Seawater corrosion | Good | Good | Good | Excellent | Excellent | Excellent |
| Colour match after anodising | Poor (goes grey) | Poor (grey) | Poor (dark grey) | Good | Good | Good |
| Service above 65 °C | Suitable | Suitable | Suitable | Not recommended | Not recommended | Not recommended |
| Feedability in MIG | Softer; needs care | Softer; needs care | Softer | Stiff, feeds easily | Stiff, feeds easily | Stiff, feeds easily |
Shear strengths are typical published values for fillet welds and depend on joint, base metal and procedure; design to the governing code.
Weld metal from the 5xxx fillers is stronger and far more ductile, so it suits bending, impact and fatigue loads. Si-bearing fillers flow better, wet the joint edges, produce a flatter bead with fewer cracks and are less sensitive to cleanliness. Aluminium-magnesium fillers with more than about 3 % Mg should not be used where the weld will run continuously above 65 °C (150 °F), because magnesium-rich phases can form at grain boundaries and make the weld sensitive to stress-corrosion cracking. For hot service choose 5554 or a 4xxx filler.
| Base metal (as-welded) | Minimum tensile strength across a groove weld |
|---|---|
| 3003 | 95 MPa (14 ksi) |
| 5052 | 170 MPa (25 ksi) |
| 5454 | 215 MPa (31 ksi) |
| 5086 | 240 MPa (35 ksi) |
| 5083 | 275 MPa (40 ksi) |
| 6063-T6 | 115 MPa (17 ksi) |
| 6061-T6 | 165 MPa (24 ksi) |
These welded-strength values, used in the Aluminum Design Manual and AWS D1.2 procedure qualification, show the most important point about welding heat-treated alloys: the heat-affected zone of 6061-T6 drops to roughly half the parent strength whatever filler is used. Choosing a stronger filler raises the strength of fillet welds, but it cannot recover the heat-affected zone; only post-weld heat treatment can.
Filler selection by base alloy
Use the first choice unless one of the listed priorities applies. Where two base alloys differ, read the row for the less weldable alloy and check the combination.
| Base alloy(s) | First choice | Alternatives and when to use them |
|---|---|---|
| 1050, 1060, 1100, 1350 | ER1100 (or ER1188 for high purity) | 4043 for better crack resistance; 1100 keeps conductivity for electrical joints |
| 3003, 3004, 3105 | 4043 | 1100 for 3003 where purity matters; 5356 for 3004 when strength or anodised colour matters |
| 5005, 5050 | 5356 | 4043 where anodised colour is not important and cracking is a risk |
| 5052, 5652, 5754 | 5356 | 5554 or 4043 for service above 65 °C; 5183 for extra strength |
| 5454 | 5554 | 5356 if service stays below 65 °C |
| 5083, 5086, 5456 | 5183 | 5356 (slightly lower strength); 5556 for 5456 and the highest strength |
| 6061, 6063, 6082, 6005A | 4043 or 5356 | 4043: crack resistance, smoother bead, hot service. 5356: higher shear strength, ductility, anodise match. 4943: higher strength than 4043 with similar feel. 4643: when the weldment is solution heat-treated and aged |
| 6xxx to 5xxx | 5356 | 5183 when the 5xxx side is 5083 or 5086 |
| 6xxx or 3xxx to castings (356, A356) | 4043 | 4047 for fluidity and leak tightness; 4643 when heat-treated after welding |
| Castings 356, A356, 357 | 4043 | 4047 for repair and sealing; 4643 for post-weld heat treatment |
| 7005, 7020, 7039 (weldable 7xxx) | 5356 or 5183 | 5556 for higher strength; avoid 4xxx fillers |
| 2219 | 2319 | 4043 or 4145 in some dissimilar combinations |
| 2014, 2024, 7075 | Not recommended for fusion welding | Use mechanical fastening, friction stir welding or a weldable alternative alloy |
For a deeper look at the two most-requested grades see 4043 vs 5356, and for welding the most common structural alloy see welding 6061 aluminium. The 16 types of aluminium welding wire page lists less common grades.
Wire diameters, spools and packaging
| Diameter | Inch equivalent | Typical use |
|---|---|---|
| 0.8 mm | 0.030 in | Thin sheet about 1 – 3 mm, short-arc and pulsed MIG, spool guns |
| 0.9 / 1.0 mm | 0.035 / 0.040 in | Sheet and light plate, general fabrication |
| 1.2 mm | 3/64 in (0.047 in) | The standard size for 3 – 12 mm plate and robotic welding |
| 1.6 mm | 1/16 in | Thick plate, high deposition, spray transfer |
| 2.0 – 2.4 mm | 5/64 – 3/32 in | Heavy sections, mechanised welding; common TIG rod sizes |
| 3.2 – 5.0 mm | 1/8 – 3/16 in | TIG filler rod for thick sections |
Packaging options
- MIG spools
- Small spools (about 0.5 kg / 1 lb) for spool guns; 2 kg and 6 – 7 kg spools (200 and 300 mm) for push-pull and standard feeders
- Bulk
- Larger reels and drums for robotic lines, reducing changeovers
- TIG rod
- Straight lengths, usually 914 or 1000 mm, in sealed tubes or cartons, end-stamped with the grade
- Protection
- Vacuum-sealed or foil bags with desiccant to keep moisture out
- Documents
- Certificate of conformity or lot test certificate to AWS A5.01 / EN 10204, safety data sheet
Feeding and welding with aluminium MIG wire
Liner and tip
Use a PTFE or nylon liner and keep the gun cable as straight and short as practical. Contact tips for aluminium are slightly oversize to allow for thermal expansion.
Spool gun or push-pull
Soft 4xxx wire in small diameters is best fed with a spool gun or push-pull system. Stiffer 5xxx wire feeds through standard push feeders over longer distances.
Transfer mode
Spray transfer or pulsed spray is normal for aluminium. Pulsed MIG controls heat input on thin sheet and in positional welding.
Shielding gas
Pure argon for most work. Argon-helium mixtures (typically 25 – 75 % helium) give hotter arcs and deeper penetration on thick sections. Never use CO2 or oxygen-bearing steel mixtures.
Technique
Push the torch (forehand angle about 10 – 15°) so gas shields ahead of the pool. Fill the crater at the end of each weld to avoid crater cracks.
As a starting point, 1.2 mm wire in spray transfer on 6 mm plate runs in the region of 180 – 230 A, rising with thickness and falling for vertical and overhead positions; 5xxx wires generally need slightly higher wire-feed speed and current than 4xxx wires of the same diameter. Develop and qualify the exact parameters on test pieces for your joint, equipment and position.
TIG welding with aluminium filler rod
TIG welding aluminium uses alternating current. The electrode-positive half of each cycle breaks up the oxide film (cleaning action), and the electrode-negative half puts heat into the work. Modern inverter machines let you adjust the balance and frequency to narrow the arc and control cleaning width. Pure argon is the standard shielding gas; argon-helium raises heat input for thick sections.
- Choose rod diameter close to the base-metal thickness on thin work, and not more than about half of it on thicker joints, so the rod melts without chilling the pool
- Use the same filler logic as MIG: 4043 or 5356 for 6xxx, 5183 for 5083, 4047 for castings and leak-tight joints
- Keep the hot end of the rod inside the gas shield between dips to avoid oxidising it
- For automated TIG with cold- or hot-wire feeders, layer-wound spools of TIG-quality wire are used instead of cut rod
See aluminium TIG filler rod for rod sizes and packaging. Shielded metal arc (stick) welding of aluminium uses flux-coated electrodes instead of wire; see aluminium stick welding rod.
Preventing porosity, cracking and feeding problems
| Defect | Main cause | Prevention |
|---|---|---|
| Porosity | Hydrogen from moisture, oil, hydrated oxide on wire or plate | Keep wire sealed and dry; degrease and stainless-brush the joint just before welding; check gas flow and hoses |
| Hot (solidification) cracking | Weld chemistry in the crack-sensitive range, too little filler, high restraint | Use the correct filler, add enough filler to dilute the base metal, use a convex bead and fill craters |
| Lack of fusion | Heat lost into thick, conductive plate; cold start | Preheat thick sections moderately (do not overheat 6xxx and 5xxx), use helium mixes, start on run-on tabs |
| Bird-nesting and burn-back | Wrong drive rolls, liner or tip; excessive feed resistance | U-groove rolls, PTFE liner, correct tip size, spool gun for soft wire |
| Black soot on bead | Magnesium oxide from 5xxx wire, poor gas coverage | Correct torch angle and gas flow; wire brush between passes |
Store aluminium wire in its original sealed packaging in a dry room at a stable temperature, and bring it into the workshop well before opening so condensation does not form on a cold spool. Partly used spools should be resealed in a bag with desiccant or kept in a heated cabinet. Wire that has picked up a dull grey surface film can produce porosity even if it still feeds.
Where each filler is typically used
- Shipbuilding and offshore: ER5183 and ER5356 on 5083 and 5086 hulls and superstructures; 6082 extrusions welded with 5183 or 5356
- Road tankers and trailers: 5183 and 5356 on 5083, 5454 and 5182 plate, with 5554 on hot-product tankers
- Rail and bus bodies: 5356 and 5087 on 6005A and 6082 extrusions, often robotic
- Automotive and EV battery trays: 4043, 4943 and 5356 on 6xxx extrusions and castings
- Structural and architectural: 4043 and 5356 on 6061 and 6063 frames, railings and handrails; 5356 where parts are anodised
- Pressure vessels and cryogenic tanks: 5183 on 5083, 2319 on 2219
- Castings and repair: 4043 and 4047 for cast housings, wheels and leak-tight joints
- Additive manufacturing: wire-arc additive manufacturing uses high-quality 4043, 5183 and similar wires
Common mistakes when buying and using aluminium wire
- Ordering "6061 wire" to weld 6061: matching-composition fillers crack; use 4043, 4943 or 5356.
- Using 5356 on parts that run hot: engine parts, hot-product tanks and heat exchangers above 65 °C need 5554 or 4xxx filler.
- Using 4043 on parts to be anodised for appearance: the weld turns grey; choose 5356.
- Choosing 4043 for 5083 marine structures: Al-Si filler with high-Mg base metal forms brittle magnesium silicide; use 5183 or 5356.
- Assuming a stronger wire makes a stronger joint in 6061-T6: the heat-affected zone governs; design to welded properties.
- Buying large spools for a spool gun or slow consumption: opened spools absorb moisture; match spool size to usage.
How to order aluminium welding wire from Metline
- Grade and standardState the AWS or ISO classification (for example ER5183 / S Al 5183) and any approval or certification level required.
- Form and sizeMIG wire or TIG rod, diameter, spool type and weight or rod length.
- QuantityTotal quantity and call-off pattern, so spool sizes match your consumption.
- DocumentsLot certificate with chemistry, conformity certificate and safety data sheet.
- ShippingMoisture-proof packed spools or rod cartons on pallets, shipped on EXW, FOB, CIF or DAP terms worldwide.
References and standards
- AWS A5.10/A5.10M – Welding Consumables: Wires and Rods for Welding of Aluminum and Aluminum-Alloys
- ISO 18273 – Welding consumables: wire electrodes, wires and rods for welding of aluminium and aluminium alloys
- AWS D1.2/D1.2M – Structural Welding Code: Aluminum
- The Aluminum Association – Aluminum Design Manual
- ESAB University – Choosing the right filler metal for aluminium welding
Aluminium (aluminum) welding wire: FAQ
What is the most common aluminium welding wire?
ER4043 and ER5356 together cover most fabrication. 4043 is chosen for crack resistance, a smooth bead and hot service; 5356 for higher strength, ductility, seawater resistance and better colour match after anodising.
Which wire should I use to weld 6061?
ER4043 or ER5356. Use 4043 for crack-sensitive joints, parts in service above 65 °C and smoother beads; use 5356 for higher fillet shear strength and anodised parts. ER4943 offers higher strength than 4043, and ER4643 suits weldments that are heat-treated after welding.
Which wire is used for 5083 marine aluminium?
ER5183 is the usual first choice because it matches the strength of 5083 and resists seawater corrosion. ER5356 is also widely used; ER5556 gives the highest strength. Avoid 4xxx fillers on high-magnesium alloys.
Can I use the same wire for MIG and TIG?
The same alloy grades are used in both processes. MIG uses layer-wound spooled wire; manual TIG uses straight cut rod, although automatic TIG systems can feed spooled wire.
What shielding gas is used for aluminium MIG welding?
Pure argon for most work, and argon-helium mixtures for thicker sections where more heat and penetration are needed. Carbon dioxide and oxygen-containing mixtures used for steel must not be used on aluminium.
Why does my aluminium weld have porosity?
Almost always hydrogen from moisture or contamination: damp or oxidised wire, oil or hydrated oxide on the joint, or poor gas coverage. Store wire sealed and dry, clean the joint just before welding and check the gas system.
Can 7075 or 2024 be welded with aluminium wire?
They are generally considered unsuitable for arc welding because they crack and lose strength. Weldable 7xxx alloys such as 7005 and 7020 are welded with 5356 or 5183, and 2219 with 2319.
Need aluminium welding wire?
Send the grade, diameter, spool or rod type and quantity. We will confirm certification and quote delivery to your workshop.
