ER70S-2 TIG Filler Rod: Settings & Application Guide
Premium TIG filler rod for the cleanest possible carbon steel welds. Runs 40 to 220 amps on DCEN, rated for flat, horizontal, vertical up, overhead. Amperage chart by diameter below.
ER70S-2 is the premium TIG filler rod for carbon steel. It has three deoxidizers (titanium, zirconium, and aluminum) on top of the standard manganese and silicon, which means it produces the cleanest, most porosity-free welds of any carbon steel filler. It is overkill for most shop work, but if you are TIG welding pipe root passes or doing work that has to be perfect, this is the rod.
What This Means in Practice
ER70S-2 is the premium TIG filler rod for carbon steel. Triple-deoxidized (titanium, zirconium, and aluminum) for maximum weld purity. It produces the cleanest welds of any carbon steel filler but costs more than ER70S-6. Specify it for code work, X-ray quality joints, and any application where weld metallurgy matters more than cost per pound.
What Amps for ER70S-2?
| Diameter | Amperage Range |
|---|---|
| 1/16" (1.6 mm) | 40 - 90A |
| 3/32" (2.4 mm) | 80 - 150A |
| 1/8" (3.2 mm) | 120 - 220A |
Amperage by Individual Diameter
1/16 ER70S-2 Amperage
Set 1/16 ER70S-2 to 40 - 90 amps. Run DCEN. This is the smallest available size. Best for vertical-up and overhead where you need a small, controllable puddle. Start around 65A.
3/32 ER70S-2 Amperage
Set 3/32 ER70S-2 to 80 - 150 amps. Run DCEN. A versatile mid-range size. Start at 115A and adjust: lower for thin material and out-of-position work, higher for flat fillets on thicker stock.
1/8 ER70S-2 Amperage
Set 1/8 ER70S-2 to 120 - 220 amps. Run DCEN. Largest available diameter. High deposition for flat and horizontal fillet welds on thick plate. Requires 120A minimum to run properly.
ER70S-2 Suitability Scores
How well this electrode matches common applications. Not a quality rating. all AWS-certified electrodes meet their specification.
What Is ER70S-2 Good For?
TIG welding of carbon steel pipe root passes where maximum weld quality is required.
Welding on slightly contaminated base metal where the extra deoxidizers help.
Critical applications where the highest quality filler rod is justified.
Where ER70S-2 Falls Short
More expensive than ER70S-6 filler rod.
Deoxidizer content can affect weld chemistry in multi-pass applications.
Not commonly stocked.
ER70S-6 is more widely available and works fine for most non-critical TIG work.
How ER70S-2 Feeds Into the Puddle
The Arc
Smooth, quiet arc similar to ER70S-6. The triple-deoxidized chemistry (silicon, manganese, and titanium/zirconium/aluminum) produces an extremely clean puddle even on imperfect surfaces.
Technique
Standard TIG technique. Feed the rod into the leading edge of the puddle with your off hand. Dab at a consistent rhythm. Keep the tungsten 1/8 inch from the work.
The Puddle
Exceptionally clean puddle with minimal surface tension effects. The triple deoxidizer package absorbs contamination that would cause porosity with other filler rods. The bead wets out flat and smooth.
When It Goes Wrong
If the rod oxidizes and turns dark, your gas coverage is insufficient. Increase argon flow or use a larger cup. If the puddle looks dirty, clean the base metal more aggressively before welding.
Matching ER70S-2 Diameter to Your Steel
| Rod Diameter | Material Thickness | Application |
|---|---|---|
| 1/16" | 1/16" to 1/8" | Thin wall tubing and sheet |
| 3/32" | 1/8" to 1/4" | General purpose TIG on steel |
| 1/8" | 1/4" and up | Heavier sections and root passes |
Shop Talk
ER70S-2 is the premium TIG rod for carbon steel. The triple deoxidizer chemistry makes it the most forgiving filler on surfaces that are not perfectly clean. Pipe welders use it for open root passes where the fit-up is tight and contamination from the back purge setup can affect the root. It costs more than ER70S-6 but saves time on joints where you would otherwise stop to reclean.
Bottom Line
Structural work is where ER70S-2 belongs. Production is not its job. When ER70S-2 is wrong for the job, reach for ER70S-6.
Setup & Safety Reference
How to Store ER70S-2
Store in clean, dry container. Keep rod ends free from oil and contaminants. Triple-deoxidized wire is forgiving but still requires clean storage.
Shielding Gas for ER70S-2
| Gas Mix | Common Name | When to Use |
|---|---|---|
| 100% Argon | Argon | Standard for TIG welding carbon steel. 15-25 CFH flow rate. |
Pure argon only for TIG. The ER70S-2 classification also covers GMAW, but ER70S-6 is the preferred MIG wire for most applications.
Preheat & Interpass Temperature for ER70S-2
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: 15-25 CFH
Source: AWS D1.1 Table 3.2, Category B (low-hydrogen)
Fume Generation
Rating: Very Low
Typical fume rate: 0.1-0.3 g/min
TIG welding produces the least fume of any arc process.
Common Brand Names for ER70S-2
Look for Lincoln Electric Lincoln ER70S-2 at your supplier. 3 companies produce ER70S-2-classified rods.
| Manufacturer | Product Name | Notes |
|---|---|---|
| Lincoln Electric | Lincoln ER70S-2 | |
| Harris | Harris ER70S-2 | Popular for TIG pipe root passes |
| Weldcote | Weldcote ER70S-2 |
Full Specs
| Property | Value |
|---|---|
| AWS Classification | ER70S-2 |
| Process | TIG Welding (GTAW) |
| Polarity | DCEN |
| Positions | flat, horizontal, vertical up, overhead |
| Penetration | medium |
| Coating Type | bare solid rod |
| 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, low-alloy steel |
| Shielding Gas | 100% Argon |
| Gas Flow Rate | 15-25 CFH |
| Max Interpass Temp | 600°F |
| AWS Specification | AWS A5.18/A5.18M:2023 |
ER70S-2 Questions
What TIG filler rod for carbon steel?
ER70S-2 for the highest quality welds, ER70S-6 for general purpose. ER70S-2 has three deoxidizers (titanium, zirconium, aluminum) that produce the cleanest welds with the least porosity, making it the standard for pipe root passes and X-ray quality work. ER70S-6 is more widely available and cheaper, and works fine for non-critical TIG welding. Both are 70,000 psi tensile strength. Use ER70S-2 when the weld has to be perfect, ER70S-6 when it has to be good. See also: ER70S-6 specifications.
Can ER70S-2 be used as MIG wire?
Yes, but it is not the ideal choice. ER70S-2 works as MIG wire but its triple deoxidizer system is optimized for TIG welding. For MIG, ER70S-6 is more practical because its higher manganese and silicon content handles surface contamination better at MIG welding speeds.
What makes ER70S-2 better for root passes?
The zirconium, titanium, and aluminum deoxidizers in ER70S-2 produce a very clean weld puddle with minimal porosity. This is critical for root passes on pipe where the back side of the weld cannot be inspected during welding and must pass X-ray.
Where to Buy ER70S-2
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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.