The right aluminium TIG filler rod depends on the base alloy, the service conditions and whether the part will be anodised or heat-treated after welding. For most jobs the choice is ER4043 for 6xxx alloys and castings, and ER5356 or ER5183 for 5xxx alloys and marine work. This guide explains the classifications, gives a selection chart and covers sizes, packing and storage, so you can order the correct rod first time.
In gas tungsten arc welding (GTAW, or TIG) the arc melts the base metal and the welder feeds a straight, bare filler rod into the pool by hand. The rod supplies the metal that fills the joint, and its chemistry largely decides the strength, crack resistance, ductility, corrosion behaviour and colour of the finished weld.
Aluminium weld metal is a mixture of melted filler and melted base metal, typically somewhere between 20 % and 50 % base metal depending on joint design. That dilution is why filler choice matters so much: a filler that is fine on one alloy can produce a crack-sensitive or brittle weld on another. Hot cracking, the commonest defect in aluminium welding, happens when the weld metal passes through a composition range with a wide freezing range. Filler alloys are designed to push the weld chemistry out of that range.
TIG filler rods are made from the same wire as MIG welding wire, but straightened and cut to length rather than wound on spools. Rods are normally 914 mm (36 in) or 1000 mm long and come in diameters from 1.6 mm to 4.8 mm. They are classified under AWS A5.10 in North America with the prefix ER (usable as electrode or rod) or R (rod only), and under ISO 18273 internationally with the prefix S Al.
Most buyers ask for the AWS designation, while European and Asian drawings often quote the ISO 18273 symbol. The two systems describe the same alloys; the table maps the common TIG rods. Werkstoff numbers from the older DIN 1732 system are still printed on many boxes in Europe.
| AWS A5.10 | ISO 18273 symbol | Chemical symbol | Alloy family |
|---|---|---|---|
| ER1100 | S Al 1100 | Al99,0Cu | Commercially pure aluminium |
| ER2319 | S Al 2319 | AlCu6MnZrTi | Aluminium-copper |
| ER4043 | S Al 4043A | AlSi5(A) | Aluminium-silicon (5 % Si) |
| ER4047 | S Al 4047A | AlSi12(A) | Aluminium-silicon (12 % Si) |
| ER4145 | S Al 4145 | AlSi10Cu4 | Aluminium-silicon-copper |
| ER4643 | S Al 4643 | AlSi4Mg | Aluminium-silicon-magnesium |
| ER4943 | S Al 4943 | AlSi5Mg | Aluminium-silicon-magnesium |
| ER5183 | S Al 5183 | AlMg4,5Mn0,7(A) | Aluminium-magnesium-manganese |
| ER5356 | S Al 5356 | AlMg5Cr(A) | Aluminium-magnesium |
| ER5554 | S Al 5554 | AlMg2,7Mn | Aluminium-magnesium (low Mg) |
| ER5556 | S Al 5556A | AlMg5Mn | Aluminium-magnesium-manganese |
The "ER" and "R" prefixes do not change the chemistry. A rod marked ER4043 and one marked R4043 can be used interchangeably for TIG; the ER classification simply confirms the same alloy is also qualified as a MIG electrode.
The figures below are the main alloying ranges from AWS A5.10. Iron, zinc and other impurities are also capped, and beryllium is limited to 0.0003 % in all aluminium fillers because of the health risk in welding fume. Each Metline lot is supplied with a certificate that reports the actual analysis.
| Filler | Silicon | Magnesium | Manganese | Other key elements |
|---|---|---|---|---|
| ER1100 | ≤ 0.95 (Si + Fe) | — | ≤ 0.05 | Cu 0.05 – 0.20; Al ≥ 99.00 |
| ER4043 | 4.5 – 6.0 | ≤ 0.05 | ≤ 0.05 | Fe ≤ 0.8, Cu ≤ 0.30 |
| ER4047 | 11.0 – 13.0 | ≤ 0.10 | ≤ 0.15 | Fe ≤ 0.8, Cu ≤ 0.30 |
| ER4643 | 3.6 – 4.6 | 0.10 – 0.30 | ≤ 0.05 | — |
| ER4943 | 5.0 – 6.0 | 0.10 – 0.50 | ≤ 0.05 | Cu ≤ 0.10 |
| ER5183 | ≤ 0.40 | 4.3 – 5.2 | 0.50 – 1.0 | Cr 0.05 – 0.25 |
| ER5356 | ≤ 0.25 | 4.5 – 5.5 | 0.05 – 0.20 | Cr 0.05 – 0.20, Ti 0.06 – 0.20 |
| ER5556 | ≤ 0.25 | 4.7 – 5.5 | 0.50 – 1.0 | Cr 0.05 – 0.20, Ti 0.05 – 0.20 |
| ER5554 | ≤ 0.25 | 2.4 – 3.0 | 0.50 – 1.0 | Cr 0.05 – 0.20 |
Silicon lowers the melting point and makes the pool more fluid, which reduces solidification cracking and helps the rod wet the joint. Magnesium strengthens the weld by solid solution and matches the electrochemical behaviour of 5xxx base metals. Manganese and chromium refine grain structure and add strength, which is why ER5183 and ER5556 produce stronger welds than ER5356.
The most widely used aluminium rod. Fluid pool, bright smooth bead and very good resistance to hot cracking. Suits 6xxx extrusions and plate, 3xxx alloys and most castings. Not heat-treatable on its own, but picks up magnesium from 6xxx base metal by dilution. Turns dark grey after anodising.
General-purpose aluminium-magnesium rod. Higher as-welded strength and better ductility than 4043, good seawater resistance and a close colour match after anodising. Used on 5xxx alloys and on 6xxx where fillet shear strength or appearance matters.
Higher-strength 5xxx rod with added manganese. Specified for 5083 and 5456 so that the weld meets the base-metal strength required by marine class rules and cryogenic tank codes.
The strongest common 5xxx filler, for high-strength 5xxx plate and structures under dynamic load. Behaves much like ER5183 in the pool.
High-silicon rod with the narrowest freezing range and lowest melting point. Used to repair castings, reduce shrinkage and distortion in thin sections, and as a filler for some brazing and leak-tight joints.
A 4043 type with a magnesium addition, giving higher as-welded strength while keeping the easy handling and crack resistance of 4043. Increasingly used on 6xxx structures in place of 4043.
Silicon-magnesium rod designed for 6xxx parts that are solution heat-treated and aged after welding, so the weld responds to heat treatment and approaches T6 strength.
Lower-magnesium rod for 5454 and similar alloys in service above 65 °C, such as truck tanks carrying hot cargo and wheels.
ER1100 joins pure aluminium where conductivity or chemical resistance matters. ER2319 is for heat-treatable aluminium-copper alloys such as 2219 in aerospace tankage.
Pick the filler from the base metal first, then adjust for service temperature, anodising and post-weld heat treatment. When two different alloys are joined, choose a filler suitable for both; the chart gives the usual first choice and the alternative.
| Base metal | First choice | Alternative | Notes |
|---|---|---|---|
| 1050, 1060, 1100 | ER1100 | ER4043 | 1100 for conductivity and chemical service; 4043 for easier crack-free welding |
| 3003, 3004, 3105 | ER4043 | ER5356 / ER1100 | All three work; 5356 for higher strength |
| 5052, 5251 | ER5356 | ER4043 (Mg ≤ 2.5 %) | 4043 acceptable on lower-magnesium 5xxx only |
| 5083, 5086, 5456 | ER5183 | ER5356 / ER5556 | Never use 4xxx: magnesium silicide makes the weld brittle |
| 5454 (hot service) | ER5554 | ER5356 | Keep weld Mg below 3 % for service above 65 °C |
| 6061, 6082, 6005A | ER4043 | ER5356 / ER4943 | 5356 for fillet shear strength and anodised colour |
| 6063, 6060 | ER4043 | ER5356 | 4043 resists cracking on thin extrusions |
| 6xxx to be re-heat-treated | ER4643 | ER4043 | Weld responds to solution treatment and ageing |
| A356, 356, 319, 355 castings | ER4043 | ER4047 | 4047 for porous or crack-prone castings |
| 6xxx to 5xxx | ER5356 | ER5183 | Magnesium filler suits the 5xxx side |
| 2219, 2014 | ER2319 | ER4145 | Specialist aerospace procedures |
| 7xxx (7005, 7020) | ER5356 | ER5183 | 7075 and other high-copper 7xxx are generally not fusion welded |
The Aluminum Association and the major filler manufacturers publish full filler selection charts that rate each combination for strength, ductility, corrosion, crack sensitivity and colour match. Use them for code work and ask us if your combination is unusual.
The strength of a welded aluminium joint is usually controlled by the heat-affected zone of the base metal, not by the filler. Heat-treated (T6) and strain-hardened (H) tempers soften next to the weld, so the joint is weaker than the parent plate whatever rod is used. Design codes such as AWS D1.2 and the Aluminum Design Manual, and qualification codes such as ASME Section IX, therefore specify minimum as-welded tensile strengths for each base alloy.
| Base alloy and temper | Minimum as-welded tensile strength (groove weld) | Typical filler |
|---|---|---|
| 3003 | 97 MPa / 14 ksi | ER1100 or ER4043 |
| 5052 | 172 MPa / 25 ksi | ER5356 |
| 5454 | 214 MPa / 31 ksi | ER5554 or ER5356 |
| 5086 | 241 MPa / 35 ksi | ER5356 or ER5183 |
| 5083 | 276 MPa / 40 ksi | ER5183 |
| 6063-T6 | 117 MPa / 17 ksi | ER4043 |
| 6061-T6 | 165 MPa / 24 ksi | ER4043 or ER5356 |
Values are the qualification minimums used in AWS D1.2 and ASME IX for groove welds; your procedure qualification record governs actual design values.
Where filler choice does matter is in fillet welds, which fail through the weld metal. Here a 5xxx filler gives noticeably higher shear strength than 4043: for the same fillet size, a 5356 weld carries roughly half as much load again. Undiluted 4043 weld metal is also less ductile, which matters in joints that must bend or absorb impact. Filler manufacturers typically quote all-weld-metal tensile strength around 200 MPa (29 ksi) for 4043 and around 260 MPa (38 ksi) for 5356; these are typical, not guaranteed, values.
| Diameter | Inch equivalent | Typical base-metal thickness | Comment |
|---|---|---|---|
| 1.6 mm | 1/16 in | Up to about 3 mm | Thin sheet, tube and fine fillets |
| 2.4 mm | 3/32 in | About 2 – 5 mm | The most popular general-purpose size |
| 3.2 mm | 1/8 in | About 4 – 8 mm | Plate, heavier fillets, faster fill |
| 4.0 mm | 5/32 in | About 6 – 12 mm | Thick sections, high-current torches |
| 4.8 mm | 3/16 in | Over about 10 mm | Heavy plate and casting repair |
A useful rule of thumb is to choose a rod diameter close to the base-metal thickness for thin material, and no more than about half the thickness on plate where several passes are needed. A rod that is too thin melts back before it reaches the pool; one that is too thick chills the pool and causes lack of fusion.
Use 4043 for 6xxx alloys, 3xxx alloys and castings when crack resistance and a smooth bead matter most, and for parts that run hot. Use 5356 on 5xxx alloys, on parts that will be anodised, and where fillet welds need higher shear strength or the weld must be more ductile.
ER4043 is the standard choice for 6061 and gives crack-free welds. ER5356 is equally common where the weld must match the colour after anodising or carry higher fillet loads. ER4943 offers higher as-welded strength than 4043, and ER4643 is used when the welded part is heat-treated again.
Yes. ER4043 suits most silicon-bearing castings such as A356, 319 and 355. ER4047 has more silicon and a lower melting point, which helps on porous or crack-prone castings. Clean and preheat castings to drive out absorbed oil and moisture before welding.
Use a 5xxx filler such as ER5356. Silicon-bearing fillers like 4043 and 4047 turn dark grey or black when anodised, leaving a visible weld line.
For sheet up to about 3 mm use 1.6 mm rod, 2.4 mm for general work between about 2 and 5 mm, and 3.2 mm or larger for plate. Match the rod to the welding current and joint size so it melts cleanly at the pool edge.
A certificate of conformity to AWS A5.10 or ISO 18273 with the lot chemistry is standard. An EN 10204 3.1 certificate and safety data sheet can be supplied on request.
Yes. Metline supplies aluminium filler rods and welding wire worldwide from Mumbai, in moisture-protected export packing.
Send the classification, diameter, length, quantity and destination. We will reply with availability, documents and a delivered price.
