ER70S-3 MIG Wire: Settings, Gas & Amperage Chart
Cleaner MIG wire for clean steel. Runs 40 to 340 amps on DCEP, rated for flat, horizontal, vertical up, overhead. Amperage chart by diameter below.
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.
What Amps for ER70S-3?
| Diameter | Amperage Range |
|---|---|
| 0.030" (0.8 mm) | 40 - 140A |
| 0.035" (0.9 mm) | 50 - 210A |
| 0.045" (1.2 mm) | 75 - 340A |
Amperage by Individual Diameter
0.030 ER70S-3 Amperage
Set 0.030 ER70S-3 to 40 - 140 amps. Run DCEP. This is the smallest available size. Best for vertical-up and overhead where you need a small, controllable puddle. Start around 90A.
0.035 ER70S-3 Amperage
Set 0.035 ER70S-3 to 50 - 210 amps. Run DCEP. This is the most commonly used ER70S-3 size. Start at 130A for flat work, drop to 50-117A for vertical-up.
0.045 ER70S-3 Amperage
Set 0.045 ER70S-3 to 75 - 340 amps. Run DCEP. Largest available diameter. High deposition for flat and horizontal fillet welds on thick plate. Requires 75A minimum to run properly.
ER70S-3 Suitability Scores
How well this electrode matches common applications. Not a quality rating. all AWS-certified electrodes meet their specification.
What Is ER70S-3 Good For?
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).
Where ER70S-3 Falls Short
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.
How ER70S-3 Feeds
Arc Behavior
Similar to ER70S-6 but slightly stiffer arc. Less deoxidizer means the puddle is less forgiving of surface contamination. The arc runs clean on properly prepared joints.
How to Move
Same as ER70S-6. Push or pull at 15-20 degrees. The difference shows up in puddle behavior, not in how you hold the gun.
What the Puddle Does
Slightly less fluid than ER70S-6. The lower silicon content produces a puddle that does not wet out quite as aggressively. On clean metal, the difference is minimal. On dirty metal, the difference shows up as porosity.
Troubleshooting
If you see porosity that does not appear with ER70S-6, the metal needs better cleaning. ER70S-3 has less deoxidizer to compensate for surface contamination.
Matching ER70S-3 Diameter to Your Steel
| Wire Size | Material Thickness | Application |
|---|---|---|
| 0.023" | 22 ga to 1/8" | Thin gauge on clean, prepared joints |
| 0.030" | 1/8" to 3/16" | Light fabrication on clean steel |
| 0.035" | 3/16" to 3/8" | Structural work on clean material |
What the Spec Sheet Leaves Out
ER70S-3 costs slightly less than ER70S-6 because it has fewer alloying elements. Some production shops use it to save a few dollars per spool on high-volume work where the steel is always clean and prepared. For most users, the cost difference is not worth the reduced tolerance for contamination. If your metal is always prepped and clean, ER70S-3 works fine. If it is not, stick with ER70S-6.
Bottom Line
Use ER70S-3 for production work. Need something different? Look at ER80S-D2.
Setup & Safety Reference
How to Store ER70S-3
Store dry. More sensitive to surface contamination than ER70S-6 due to fewer deoxidizers.
Shielding Gas for ER70S-3
| Gas Mix | Common Name | When to Use |
|---|---|---|
| 75% Ar / 25% CO2 | C25 | Most common. Good all-around performance. |
| 95% Ar / 5% CO2 | C5 | Spray transfer. Less spatter. |
| 100% CO2 | CO2 | Deep penetration. Higher spatter. Budget-friendly. |
Less deoxidizer than ER70S-6. Requires cleaner base metal for best results.
Preheat & Interpass Temperature for ER70S-3
Preheat varies by base metal thickness. Low-hydrogen processes require less preheat than non-low-hydrogen.
| Base Metal Thickness | Minimum Preheat (°F) |
|---|---|
| up to 3/4" | Not required |
| 3/4" to 1-1/2" | 50°F |
| 1-1/2" to 2-1/2" | 150°F |
| over 2-1/2" | 225°F |
Maximum interpass temperature: 600°F
Shielding gas flow rate: 25-50 CFH
Source: AWS D1.1 Table 3.2, Category B (low-hydrogen)
Wire Feed Speed for ER70S-3
Similar to ER70S-6. Slightly less forgiving on dirty metal.
| Diameter | Amperage | Wire Feed Speed (IPM) |
|---|---|---|
| 0.030" | 40-80A | 90-200 IPM |
| 0.030" | 80-140A | 200-390 IPM |
| 0.035" | 50-120A | 90-250 IPM |
| 0.035" | 120-210A | 250-530 IPM |
| 0.045" | 75-180A | 75-250 IPM |
| 0.045" | 180-340A | 250-580 IPM |
Deposition Rates
| Diameter | Deposition Rate |
|---|---|
| 0.030" | 2-5 lbs/hr |
| 0.035" | 3-7 lbs/hr |
| 0.045" | 5-13 lbs/hr |
Fume Generation
Rating: Low
Typical fume rate: 0.2-0.4 g/min
Slightly less fume than ER70S-6 due to lower silicon/manganese.
Common Brand Names for ER70S-3
Lincoln Electric SuperArc L-50 is the most common ER70S-3 on the shelf. 1 other manufacturers make the same classification.
| Manufacturer | Product Name | Notes |
|---|---|---|
| Lincoln Electric | SuperArc L-50 | |
| Hobart | HB-25 |
Full Specs
| 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, 95% Ar / 5% CO2, 100% CO2 |
| Gas Flow Rate | 25-50 CFH |
| Max Interpass Temp | 600°F |
| AWS Specification | AWS A5.18/A5.18M:2023 |
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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Manufacturer Data Sheets
External links to standards bodies and manufacturers. These leave GageRef.
Reference data only. Verify all settings against manufacturer documentation and the applicable welding code before use. Amperage ranges are starting points that vary by position, fit-up, and material. Welding involves serious injury risks including burns, electric shock, fume exposure, and fire. This site does not replace proper training, certification, or employer safety procedures. See full terms of use.
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.