AWS A5.9/A5.9M · Stainless Steel
ER308L Welding Electrode
ER308L is the bare wire and TIG rod for 304 and 304L stainless — the same low-carbon 19Cr-10Ni chemistry as E308L, without a flux coating.
- 75 ksi tensile
- Polarity DCEP (GMAW), DCEN (GTAW)
- 4 positions
- Medium penetration
- TIG (GTAW) / MIG (GMAW)
What ER308L means
| Part | Meaning |
|---|---|
| ER | Electrode or rod — usable for MIG or TIG |
| 308 | Nominal 19–21% chromium, 9–11% nickel, matching Type 304 |
| L | Low carbon, 0.03% maximum, to resist carbide precipitation |
ER308L specifications
| AWS specification | AWS A5.9/A5.9M |
|---|---|
| Process | TIG (GTAW) / MIG (GMAW) |
| Form | Solid wire / rod |
| Polarity | DCEP (GMAW), DCEN (GTAW) |
| Welding positions | Flat, Horizontal, Vertical, Overhead |
| Tensile strength (min) | 75 ksi (515 MPa) |
| Yield strength (min) | 45 ksi (310 MPa) |
| Elongation (min) | 35% |
| Impact toughness | Not required; austenitic deposits stay tough to cryogenic temperatures |
| Coating / core | None — bare wire or rod |
| Penetration | Medium |
| Deposition rate | Medium to high depending on process |
| Slag | None; a light oxide film should be brushed or pickled off |
| Arc character | Stable with a fluid, slow-freezing puddle |
| Shielding gas | 100% argon for TIG; tri-mix 90% He / 7.5% Ar / 2.5% CO2 for spray MIG |
ER308L amperage by diameter
Typical operating ranges. Start near the middle of the range, then adjust by sound and bead profile. Reduce 10–15% for vertical and overhead work.
| Diameter | Amperage range | Typical start |
|---|---|---|
| 0.030 in (0.8 mm) MIG | 50–150 A | 100 A |
| 0.035 in (0.9 mm) MIG | 70–180 A | 125 A |
| 0.045 in (1.2 mm) MIG | 100–250 A | 175 A |
| 1/16 in (1.6 mm) TIG | 40–90 A | 65 A |
| 3/32 in (2.4 mm) TIG | 70–130 A | 100 A |
| 1/8 in (3.2 mm) TIG | 100–180 A | 140 A |
Polarity: MIG runs DCEP. TIG runs DCEN with the current set by the tungsten; the filler is hand-fed and carries no polarity of its own.
Shielding gas for ER308L
| Gas | Notes |
|---|---|
| 100% argon | Standard for all TIG work on stainless. Also used for pulsed MIG. |
| 90% He / 7.5% Ar / 2.5% CO2 | The classic stainless tri-mix for short-circuit MIG — good wetting with minimal carbon pickup. |
| 98% Ar / 2% CO2 | Spray transfer on stainless plate. Keep CO2 low to avoid raising weld carbon. |
| Ar / 2% O2 | Spray transfer with improved arc stability and wetting. |
Flow rate: 15–20 CFH (7–9 L/min) for TIG; 25–35 CFH for MIG. Back purge the root side with argon.
What ER308L is used for
- Sanitary tube and pipe welding for food, dairy and pharma
- Orbital and manual TIG on 304/304L process piping
- Stainless sheet and architectural fabrication
- Pressure vessel and tank work in 304L
- Any 304 joint where a flux-free, clean weld is needed
Base metals
- Type 304 and 304L
- Type 302, 305 and 308
- Austenitic grades not requiring molybdenum
Characteristics
- Low carbon at 0.03% maximum, slightly tighter than the 0.04% of covered E308L
- Deposit carries delta ferrite around FN 4–10, which resists hot cracking
- Needs a root-side purge on pipe to prevent sugaring
- Wets more slowly than carbon steel — expect a narrower, more crowned bead at equal settings
- Same chemistry family as E308L but with no slag to trap between passes
Storage and handling
Keep clean and dry. Contamination, not moisture, is the main enemy for bare stainless filler.
- Store TIG rods in a sealed tube; handle with clean gloves.
- Never let stainless filler touch carbon steel surfaces, benches or brushes — embedded iron rusts and initiates pitting.
- Bag MIG spools with desiccant when not in the machine.
- Wipe rods with acetone before use if they have been handled bare-handed.
Welding tips
- Back purge pipe roots with argon until oxygen is under about 0.1% or the inside will sugar.
- Use a 2% lanthanated or ceriated tungsten on DCEN; ground to a sharp point for thin material.
- Keep interpass temperature below 350 °F (175 °C) and use stringer beads.
- Dedicate a stainless-only wire brush; a carbon steel brush leaves iron that rusts within days.
- Match the rod to the base metal: ER308L for 304, ER316L for 316, ER309L for dissimilar joints.
ER308L frequently asked questions
What gas do you use with ER308L?
100% argon for TIG. For MIG, a helium-rich tri-mix (90/7.5/2.5) is the traditional short-circuit choice, while 98% argon / 2% CO2 or argon / 2% oxygen is used for spray transfer.
What is the difference between ER308L and E308L?
Same alloy family, different form. ER308L is bare wire or rod for MIG and TIG; E308L is a flux-covered stick electrode for SMAW. The bare filler makes cleaner welds with no slag to remove.
Do you need to back purge when welding 304 with ER308L?
On pipe and tube, yes. Without an argon purge the root side oxidizes into a rough gray scale called sugaring, which destroys corrosion resistance and cannot be brushed off.
What amperage for 1/16 in ER308L TIG rod?
Roughly 40–90 A DCEN depending on thickness — about 40–55 A on 16 gauge sheet and 70–90 A on 1/8 in material.
Can ER308L weld 316 stainless?
Mechanically yes, but it contains no molybdenum, so the joint gives up the chloride and pitting resistance that 316 was chosen for. Use ER316L.
Compare ER308L with
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