Article summary
The choice of welding wire depends on the material, the process, the diameter and the spool format.
- For ordinary steel (S235 to S355): G3Si1 / ER70S-6.
- For stainless steel: ER308LSi (304L), ER316LSi (316L), ER309LSi (dissimilar joints).
- For aluminium: ER4043 for castings, ER5356 for structures.
The diameter follows the thickness: 0.8 mm for 1 to 4 mm sheet, 1.0 mm from 3 to 8 mm, 1.2 mm for heavy fabrication. In regulated sectors (EN 1090), require a 3.1 material certificate.
Dagobert Industrie, an ESAB distributor in Annecy, keeps in stock the ARISTOROD 12.50 and AUTROD 12.51 MIG wires in 0.8 to 1.6 mm.
Why choosing a welding wire is a critical technical decision
In a fabrication shop, a robotic production line or a structural steel site, the welding wire is much more than a simple consumable. It determines the metallurgical quality of the bead, the mechanical strength of the joint, the productivity of the workstation and the cost of the operation. Yet it is still too often chosen out of habit or by default, without considering the essential parameters: the base material, the process used, the diameter suited to the thickness and available current, or the standards required by the manufacturing file.
This guide was written for welding professionals, welders, workshop managers, methods engineers and technical buyers, who want to make the right choices from the first order. At Dagobert Industrie, an official distributor based in Annecy, we keep a complete range of welding wires in permanent stock for all materials and all processes, with spools available in different formats and diameters to meet your immediate needs.
The main families of welding wire: an overview
Before going into detail by material, it helps to understand the two main categories of wire used in semi-automatic MIG/MAG welding.
Solid wire
Solid wire is a homogeneous metal wire, usually copper-coated to improve electrical conductivity and protect against oxidation. It is used with a shielding gas (pure argon, argon/CO₂ mix or pure CO₂ depending on the material). It is the most widespread wire in workshops for welding steel, stainless steel and aluminium. It gives a clean bead, little spatter when correctly set, and is perfectly suited to modern MIG MAG machines.
Some solid wires are now available in a non-copper-coated version, a development appreciated for robotic welding and applications requiring very high cleanliness of the deposited metal, notably in the food industry or process piping.
Flux-cored wire
Flux-cored wire is a metal tube filled with an internal flux. This flux can be rutile (E71T-1), basic, or absent in the case of gasless wires (E71T-GS). There are also metal-cored wires, which contain mainly metal powder and offer a very high deposition rate. Flux-cored wire is particularly suited to outdoor work, positional welding, hardfacing and high-yield-strength steels.
Choosing your welding wire according to the base material
Wire for non-alloy and low-alloy steel
This is the most common use. To weld ordinary steels (S235, S275, S355), the reference wires are G3Si1 (equivalent to ER70S-6) and G4Si1 (equivalent to ER70S-3). The difference between the two lies in their silicon and manganese content, which act as deoxidisers. G3Si1/ER70S-6 is more tolerant of slightly oxidised or greasy surfaces, which makes it the preferred choice for general fabrication, structural steelwork and industrial bodywork.
Two essential references in this family are available from Dagobert Industrie:
- The ESAB ARISTOROD 12.50 MIG wire, a high-quality copper-coated steel wire, known for its consistent feeding and clean beads. It is particularly suited to semi-automatic machines in the workshop and to series production.
- The ESAB AUTROD 12.51 MIG wire, a long-standing ESAB reference, highly appreciated for its versatility and compatibility with a wide range of MIG MAG machines. This steel welding wire is available in several diameters and spool formats to suit every production context.
For high-yield-strength steels (Hardox, Strenx, S690, S960), you need to turn to special wires such as ER80S-G or CrMo alloy wires, whose mechanical properties suit these demanding grades. The wire choice must then be validated against the welding procedure qualification record (WPQR).
Stainless steel welding wire
Welding stainless steels requires particular attention to the chemical composition of the wire, which must match that of the base metal to ensure corrosion resistance and mechanical properties. The main families are:
- ER308LSi: for 304/304L austenitic stainless steels, the most common in the food, pharmaceutical and architectural industries.
- ER316LSi: for 316/316L stainless steels, used in marine and chemical environments or for corrosive process piping.
- ER309LSi: for welding stainless steel to non-alloy steel, or for dissimilar joints. 309 wire is essential in hybrid constructions.
- ER347Si: for niobium-stabilised stainless steels, used at high temperature.
- 2209 duplex stainless wire: for duplex steels (2205), widely used in oil, gas and desalination.
The most common diameter for stainless MIG is 0.8 mm (308 LSi 0.8 wire), but 1.0 mm is frequent for medium thicknesses. The recommended shielding gas is an argon/helium mix or argon with a very low CO₂ content to avoid oxidising the chromium. Note: using pure CO₂ on stainless steel is a common mistake that degrades the corrosion resistance of the bead.
Aluminium welding wire
Aluminium is a tricky material to MIG weld because of its high thermal conductivity and natural oxide layer. The two most used wires are:
- ER4043 (AlSi5): silicon-aluminium wire, very fluid, ideal for casting alloys and joints that need low hot cracking. Bright, attractive bead.
- ER5356 (AlMg5): magnesium-aluminium wire, mechanically stronger, recommended for load-bearing structures, trailers, boats and equipment subject to dynamic loads.
There is also AlSi12 for high-silicon casting alloys. The standard diameter for aluminium MIG is 1.0 mm, 0.8 mm being harder to feed because of the softness of the metal. The shielding gas is always pure argon.
Wires for copper, bronze and brazing
For welding or brazing copper and its alloys, two wires are mainly used:
- CuSi3: silicon bronze wire, used for MIG brazing of galvanised sheet (car bodywork, cladding), welding copper and joining steel to copper.
- CuAl8: aluminium bronze wire, for parts subject to wear and corrosion.
MIG brazing with CuSi3 wire is a very widespread technique in bodywork for joining galvanised sheet without burning off the zinc, which limits paint rework and preserves the corrosion protection.
Choosing the right wire diameter according to thickness and process
The welding wire diameter is directly linked to the available welding current and the thickness of the base metal. Here are the correspondences generally observed in practice:
- 0.6 mm wire: very thin sheet, light bodywork, industrial electronics.
- 0.8 mm wire: general use, 1 to 4 mm sheet, the most common diameter in general workshops and bodywork.
- 1.0 mm wire: medium thicknesses (3 to 8 mm), aluminium, stainless steel in production.
- 1.2 mm wire: heavy fabrication, structural steelwork, thick plate work, high-output robotic welding.
- 1.6 mm wire: very heavy sections, hardfacing, submerged arc welding.
A frequent mistake is using too large a wire for thin sheet, which causes distortion, burn-through and an irregular bead. Conversely, too fine a wire on a thick part gives insufficient penetration and a weak weld.
Spool formats: how to choose according to your organisation
Welding wire comes on spools of different formats, and this choice directly affects the logistics and productivity of the workshop.
Standard formats
- D200 / S200 spool (200 mm diameter): light spools of 1 to 5 kg, suited to small machines, maintenance, occasional work or managing many different grades.
- D300 / S300 spool (300 mm diameter): 15 kg spools, the standard production format. 0.8 mm wire on a 15 kg D300 spool is the most ordered reference in fabrication workshops.
- Welding wire drum: packs of 100 to 500 kg, intended for robotic welding or very high-output production lines. Drastically reduces stoppages for spool changes.
The spool can be plastic or metal. Plastic spools are lighter and often used for delicate wires such as aluminium. Metal spools are more robust for heavy wires or harsh environments.
Advice on storing spools
Rusty or damp welding wire is a direct source of porosity in the bead. Spools must be stored in a dry place, protected from moisture, ideally in their original packaging until use. For stainless steel and aluminium wires, contamination by iron particles can compromise corrosion resistance. Use separate storage areas and clean gloves when handling.
Flux-cored wires: when and why to choose them?
Flux-cored wire offers specific advantages that solid wire cannot always match.
Rutile flux-cored wire (E71T-1)
Rutile flux-cored wire is the most versatile. It allows welding in all positions, produces slag that is easy to remove and gives a good bead appearance. It is widely used in steel construction, structural work and piping. It requires a shielding gas (CO₂ or argon/CO₂ mix).
Gasless flux-cored wire (E71T-GS)
Gasless flux-cored wire is ideal for outdoor or site work, where using a gas cylinder is impractical. The internal flux generates its own gas shield. In return, the bead is less clean, spatter is greater and mechanical properties are lower than with a gas-shielded wire. Reserve it for non-structural work or quick repairs.
Basic flux-cored wire
Basic flux-cored wire offers the best mechanical properties and excellent low-temperature toughness. It is used for structures under significant dynamic stress, high-yield-strength steels and offshore applications. It is more demanding to use and requires a very clean base surface.
Hardfacing and wear-resistant flux-cored wire
For hardfacing parts subject to abrasion, impact or hot corrosion, there are special flux-cored wires with hardnesses expressed in HRC. These wires are used in mining, agriculture, cement and steelmaking to extend the life of wear parts.
Standards, certification and traceability: what professionals need to know
In regulated sectors (EN 1090 steel construction, piping, pressure equipment), the choice of welding wire cannot be made without taking standards into account.
- EN ISO 14341: European standard for non-alloy and low-alloy solid steel wires (MIG/MAG process). Wires such as G3Si1 and G4Si1 are classified under this standard.
- AWS A5.18: American equivalent for MIG/MAG steel wires (ER70S-6, ER70S-3).
- EN ISO 14343 / AWS A5.9: standards for stainless steel wires.
Traceability is a key point: for regulated manufacturing files, require a 3.1 material certificate with each batch of wire. This document certifies the chemical composition and mechanical properties of the batch produced, and justifies the conformity of the consumable during an audit or inspection.
The spool marking must show the full standard designation, the production batch, the diameter and the net weight. Always check this information on receipt, especially for online orders.
ESAB wires such as ARISTOROD 12.50 and AUTROD 12.51 are supplied with complete technical documentation and meet the requirements of EN ISO 14341 and AWS A5.18, which makes them directly usable in WPQR files.
Common mistakes and how to avoid them
Porosity in the MIG bead
Porosity is often due to contamination of the base metal (oil, rust, paint), insufficient gas flow or a clogged nozzle. It can also come from damp wire or incorrect wire speed settings. Always check the surface condition before welding and check your gas flow with a flowmeter.
Too much spatter
Excess spatter generally indicates too high an arc voltage or an unsuitable wire speed. On a MIG MAG machine, adjusting the inductance (or dynamics) corrects this defect. Poor-quality or badly drawn wire can also cause excessive spatter, hence the importance of choosing a professional welding wire with tight dimensional tolerance.
The wire sticks to the contact tip
This problem occurs when wire speed is too low relative to current, or when the contact tip is worn and unsuited to the wire diameter. Replace the contact tip regularly and check that its bore matches the diameter of the wire used exactly.
The wire tangles on the spool
This phenomenon, known as a "bird's nest", occurs when the spool brake is badly adjusted or when the torch liner is too long or too bent. For aluminium, use a PTFE liner and suitable drive rolls (U-groove rolls without knurling) to avoid crushing the wire.
Irregular bead or porous weld on stainless steel
On stainless steel, an irregular or porous bead is often linked to cross-contamination (tools used on steel and then on stainless steel), the wrong shielding gas or too high a welding speed. Use tools dedicated to stainless steel, a suitable gas (pure argon or a low-activity mix) and reduce travel speed to improve fusion.
Our stock and range: everything you need, available immediately
At Dagobert Industrie, we have chosen to keep a permanent, complete stock of welding wires to meet professionals' needs without delay. Whether you need steel wire on a 15 kg spool for your daily production, 316L stainless wire for an urgent piping order, 5356 aluminium wire for your boatbuilding workshop, or wear-resistant flux-cored wire for hardfacing agricultural parts, we have the reference you need.
Our two flagship MIG steel wire references are available from stock in all common diameters (0.8 mm, 1.0 mm, 1.2 mm) and in several spool formats:
- The ESAB ARISTOROD 12.50 MIG wire: high-performance copper-coated steel wire, ideal for series production, robotic welding and all general fabrication applications requiring an even bead and trouble-free feeding.
- The ESAB AUTROD 12.51 MIG wire: the versatile reference par excellence, compatible with all MIG MAG machines on the market, available on D200 and D300 spools, in diameters from 0.8 to 1.6 mm.
Our technical team is available to help you identify the wire best suited to your application, validate compatibility with your WPQR, or point you to the right grade if in doubt. Feel free to contact us directly from our website or visit our branch in Annecy.
Frequently asked questions
Which MIG welding wire for standard steel?
For S235 to S355 steels, the reference wire is G3Si1, equivalent to ER70S-6. More tolerant than G4Si1 of slightly oxidised or greasy surfaces, it suits general fabrication, steel structures and industrial bodywork. ESAB AUTROD 12.51 and ARISTOROD 12.50 wires belong to this family.
Which wire diameter for which thickness?
0.8 mm covers 1 to 4 mm sheet and is the most common size in workshops. 1.0 mm suits 3 to 8 mm, aluminium and stainless steel in production. 1.2 mm is used for heavy fabrication and robotic welding, 1.6 mm for very thick sections.
Which wire for welding 316L stainless steel?
ER316LSi wire, used in marine and chemical environments and for corrosive process piping. For 304L stainless, use ER308LSi, and for welding stainless to unalloyed steel, ER309LSi. Avoid pure CO₂ as shielding gas: it impairs the corrosion resistance of the weld.
Which gas for MIG welding aluminium?
Always pure argon. For the wire, ER4043 (AlSi5) suits casting alloys and ER5356 (AlMg5) load-bearing structures. The standard diameter is 1.0 mm, as 0.8 mm is harder to feed. Use a Teflon liner and U-groove rollers without serrations.