MIG Wire vs. TIG Rod: Choosing the Right ER70S Filler

If you weld mild steel, you've probably wondered whether to load a MIG spool or reach for a TIG rod — and once you're at the TIG bench, whether ER70S-6 or ER70S-2 is the right filler. Both wires share the same 70,000 psi tensile class, but they're built for different jobs. Here's how to pick the right filler metal for GMAW or GTAW, and the right rod once you've chosen TIG.

MIG Wire vs. TIG Rod: What's Actually Different

The underlying metallurgy can be nearly identical — both HYW ER70S-6 MIG wire and ER70S-6 TIG rod are AWS A5.18 ER70S-6, copper-coated, and rated to the same 70,000 psi minimum tensile. What changes is the process: MIG (GMAW) feeds continuous wire off a spool through a gun for fast, semi-automatic welding, while TIG (GTAW) uses a straightened, hand-fed 36" rod with a separate tungsten arc for slow, precise control. That difference in process — not the alloy — is what should drive your choice.

Choosing a TIG Rod: ER70S-6 vs. ER70S-2

Once you've decided TIG is the right process, HYW stocks two mild-steel rods built for different situations. ER70S-6 carries high manganese and silicon for strong deoxidizing power, giving it good tolerance for light rust and mill scale — a dependable, general-purpose choice. ER70S-2 is triple-deoxidized with zirconium, titanium, and aluminum, producing exceptionally clean, porosity-free welds even over less-than-clean base metal, which is why it's the preferred filler for X-ray-quality pipe root passes and code-governed work.

Both rods are AWS A5.18 ER70S classification, run on DCEN with 100% argon, and are available in 1/16", 3/32", and 1/8" diameters — recommended amperage runs roughly 70–110 A, 100–160 A, and 120–210 A respectively across both rods, so switching between them doesn't require re-learning your machine settings.

Common Applications

• General steel fabrication, structural welds, and repair (MIG, ER70S-6 wire or rod)
• Automotive frames, chassis, and exhaust work (either process)
• Farm, ranch, and heavy-equipment maintenance (MIG for speed, TIG for thin sheet)
• Tube, frame, and ornamental fabrication (ER70S-6 TIG rod)
• Pipe and pressure-vessel root passes, code-governed jobs (ER70S-2 TIG rod)

Buying for the Shop or the Job

MIG wire scales with volume: HYW's ER70S-6 solid wire ships on 10, 33, and 44 lb spools, with 550 lb bulk drums for production and robotic cells that need continuous feed. TIG rod is sold by weight in convenient 2 lb, 5 lb, and 10 lb tubes — pick the size that matches how often you're at the TIG bench so rod doesn't sit around collecting surface oxidation. If you're outfitting a shop for both processes, ask about combined bulk pricing on wire and rod together.

Frequently Asked Questions

Can I use ER70S-6 for both MIG and TIG welding?

Yes — ER70S-6 is available as both spooled MIG wire and straightened TIG rod, so you can standardize on one classification across both processes if your work doesn't require the root-pass performance of ER70S-2.

Why would I choose ER70S-2 over ER70S-6 for TIG?

ER70S-2's triple-deoxidized chemistry handles rust, mill scale, and less-than-ideal base metal more cleanly, and it's the rod most fabricators reach for on pipe root passes and pressure-vessel work where X-ray quality matters.

Is MIG or TIG faster?

MIG. Continuous wire feed gives a much higher deposition rate, which is why production shops default to MIG for general fabrication and save TIG for thin material or joints that need precise, controlled heat input.

What shielding gas do I need for TIG rod?

Both ER70S-6 and ER70S-2 TIG rod run on 100% argon with DCEN (straight polarity). MIG wire, by contrast, uses DC+ (DCEP) and either 100% CO₂ or an argon/CO₂ blend.

Welding produces fumes and UV radiation. Always follow proper safety practices, ventilation, and PPE, and weld to your applicable procedure or code.