ER70S-6 MIG Welding Wire: Complete Buyer's Guide
ER70S-6 is the workhorse of MIG welding — the wire most fab shops reach for on carbon and mild steel. If you've ever wondered which shielding gas to run, how to dial in your machine, what diameter to buy, or whether you can swap it in for a name-brand wire, this guide covers it. By the end you'll know exactly which spool or drum to order for your work.
What is ER70S-6?
ER70S-6 is a copper-coated solid MIG/MAG (GMAW) wire for mild and low-carbon steel, classified under AWS A5.18 with a minimum tensile strength of 70 ksi (70,000 psi). The "S-6" tells you it carries higher levels of silicon and manganese deoxidizers than other S-series wires. In practice that means it wets out smoothly and tolerates light rust and mill scale better than cleaner wires — which is why it's the default choice for general fabrication, structural work, automotive, and repair.
Shielding gas: 100% CO² vs. Ar/CO² blend
ER70S-6 runs on two common gas choices, and the gas changes how the arc behaves:
| Shielding gas | Arc characteristics | Best for |
|---|---|---|
| 100% CO² | Deeper penetration, more spatter, slightly rougher bead | Thicker steel, budget jobs, less-than-clean metal |
| 75–80% Argon / 20–25% CO² | Smoother arc, less spatter, cleaner bead | Thinner steel, visible welds, spray-transfer work |
Both are valid — the blend just buys you a cleaner, easier-to-control puddle at a higher gas cost. Polarity is always DC+ (DCEP, electrode positive) for solid MIG wire.
Choosing your wire diameter
Match the wire size to your metal thickness. As a starting point:
| Diameter | Typical material thickness | Notes |
|---|---|---|
| 0.023" | 24 ga – 1/8" | Sheet metal, auto body, thin work |
| 0.030" | 24 ga – 3/16" | Most versatile all-around shop size |
| 0.035" | 20 ga – 1/4"+ | General fabrication, the most popular size |
| 0.045" | 1/8" and heavier | Heavy fabrication, high deposition, spray transfer |
If you only buy one size for a general shop, 0.035" covers the widest range of work.
Common applications
- General steel fabrication and structural welds
- Automotive frames, chassis, and repair
- Farm, ranch, and equipment maintenance
- Manufacturing and production MIG on carbon steel
- Welds over light surface rust or mill scale where a cleaner wire would struggle
Can I replace a name-brand wire with ER70S-6?
Yes. The following popular wires are the same AWS A5.18 ER70S-6 classification, so HYW's ER70S-6 is a spec-equivalent substitute. Match the diameter and shielding gas, and confirm your welding procedure or code before switching:
| Brand | Their product | Replace with |
|---|---|---|
| Lincoln Electric | SuperArc L-56 | ER70S-6 |
| ESAB | Spoolarc 86 · OK Autrod 12.51 | ER70S-6 |
| Hobart | HB-28 | ER70S-6 |
Cross-references are a general guide only. All third-party brand names are trademarks of their respective owners; HYW Products is an independent distributor and is not affiliated with or endorsed by these companies.
Spool or drum — buying for volume
For hobby and light shop use, a standard spool is plenty. Production shops and automated/robotic cells run far more efficiently on bulk drums (e.g. 550 lb), which cut changeover downtime and lower cost per pound. If you're buying for a team or reselling, ask us about bulk and pallet pricing.
Browse spools and drums in 0.023"–0.045", or get a bulk quote: Shop ER70S-6 → · All Mild Steel Solid Wire →
Frequently asked questions
What polarity does ER70S-6 use?
DC+ (DCEP, electrode positive), the standard for solid MIG wire.
Can ER70S-6 weld over rust?
Its extra deoxidizers handle light surface rust and mill scale better than cleaner wires, but it is not a substitute for proper prep. Clean heavy rust, paint, and oil for the strongest, most consistent welds.
ER70S-6 vs. ER70S-2 — what's the difference?
ER70S-6 is the everyday general-purpose MIG wire. ER70S-2 is a triple-deoxidized TIG rod favored for X-ray-quality pipe root passes. Different processes, different jobs.
What gas is cheapest to run?
100% CO² is the most economical and gives deep penetration, at the cost of more spatter. An Ar/CO² blend costs more but runs cleaner.
Welding produces fumes and UV radiation. Always follow proper safety practices, ventilation, and PPE, and weld to your applicable procedure or code.