ER70S-3 MIG Wire: Settings, Gas & Amperage Chart
ER70S-3 Amperage by Diameter
| Diameter | Amperage Range |
|---|---|
| 0.030" (0.8 mm) | 40 - 140A |
| 0.035" (0.9 mm) | 50 - 210A |
| 0.045" (1.2 mm) | 75 - 340A |
ER70S-3 is the cleaner cousin of ER70S-6. It has less manganese and silicon, which means less of those glassy silicon island deposits on your bead. The trade-off is it does not handle rust and contamination as well. If your steel is properly cleaned and you want the cleanest possible weld, use ER70S-3. For everything else, stick with ER70S-6.
What This Means in Practice
ER70S-3 is the choice when weld surface cleanliness matters more than forgiveness. Lower silicon content (0.45-0.75%) means less residue on the weld surface. Specify it for welds that will not be painted, for stainless steel root passes on carbon steel pipe (where silicon pickup is a concern), or in controlled shop environments where the steel is reliably clean.
ER70S-3 Suitability Scores
How well this electrode matches common applications. Not a quality rating. all AWS-certified electrodes meet their specification.
When to Use ER70S-3
Clean, well-prepared mild steel where a cleaner weld appearance is desired.
Single-pass welds on thin material.
Applications where lower silicon residue on the weld surface matters (like before painting).
ER70S-3 Limitations
Less tolerant of surface contaminants (rust, oil, mill scale) than ER70S-6.
Requires external shielding gas.
Higher porosity risk on dirty steel.
ER70S-6 is the better all-around choice for most shops.
ER70S-3 Storage Requirements
Store in dry area. Protect spool from moisture and contamination.
ER70S-3 Technical Specifications
| Property | Value |
|---|---|
| AWS Classification | ER70S-3 |
| Process | MIG Welding (GMAW) |
| Polarity | DCEP |
| Positions | flat, horizontal, vertical up, overhead |
| Penetration | medium |
| Coating Type | copper-coated solid wire |
| Tensile Strength | 70,000 psi |
| Yield Strength | 58,000 psi |
| Elongation | 22% |
| Impact Toughness | 20 ft-lbs at -20°F |
| Base Metals | carbon steel, low-carbon steel |
| Shielding Gas | 75% Ar / 25% CO2 (most common), 100% CO2, 95% Ar / 5% CO2 |
| AWS Specification | A5.18 |
ER70S-3 Questions
When should I use ER70S-3 instead of ER70S-6?
Use ER70S-3 when your steel is clean (no rust, oil, or mill scale) and you want the cleanest possible weld with less silicon residue. ER70S-3 has lower manganese and silicon, so it does not leave the glassy silicon island deposits that ER70S-6 sometimes does. This matters for visible welds, painted surfaces, or multi-pass welds where silicon inclusions can trap between passes. For everything else, stick with ER70S-6. See also: ER70S-6 specifications, ER70S-3 vs ER70S-6 comparison.
What is the difference between ER70S-3 and ER70S-6?
ER70S-3 has lower manganese and silicon content than ER70S-6. This means ER70S-3 produces slightly cleaner welds but is less forgiving of mill scale and surface contamination. ER70S-6 is the better choice for general shop work. ER70S-3 is preferred for clean material where the lower silicon reduces silica islands.
Can I use ER70S-3 instead of ER70S-6?
Yes, on clean, well-prepared material. Both have the same tensile strength (70k psi) and use the same shielding gas. The difference is surface tolerance. If your base metal is clean and free of mill scale, ER70S-3 works well and may produce a cleaner weld.
Where to Buy ER70S-3
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External Resources
Manufacturer data sheets and standards for ER70S-3.
Data sourced from AWS A5.18/A5.18M. Amperage ranges are approximate starting points. adjust based on position, fit-up, and material thickness. Always follow manufacturer recommendations and applicable codes.