Electrode comparison
E309L vs ER309L
Same over-alloyed 23Cr-12Ni chemistry for dissimilar joints. E309L is the covered electrode; ER309L is bare wire and TIG rod.
E309L vs ER309L at a glance
| E309L | ER309L | |
|---|---|---|
| AWS specification | AWS A5.4/A5.4M | AWS A5.9/A5.9M |
| Process | Stick (SMAW) | TIG (GTAW) / MIG (GMAW) |
| Form | Covered electrode | Solid wire / rod |
| Tensile strength (min) | 75 ksi | 75 ksi |
| Yield strength (min) | 45 ksi | 45 ksi |
| Elongation (min) | 30% | 30% |
| Impact toughness | Not required by the specification | Not required by the specification |
| Polarity | DCEP, AC | DCEP (GMAW), DCEN (GTAW) |
| Positions | Flat, Horizontal, Vertical, Overhead | Flat, Horizontal, Vertical, Overhead |
| Penetration | Shallow to medium | Medium |
| Deposition rate | Medium | Medium to high depending on process |
| Coating / core | Lime-titania (-16) | None — bare wire or rod |
| Slag | Self-lifting, must be fully removed between passes | None; light oxide film to be cleaned |
| Shielding gas | None — self-shielding | 100% argon for TIG; tri-mix or 98/2 for MIG |
| Storage | Dry storage, rod oven after opening — same discipline as E308L. | Clean, dry, isolated from carbon steel contamination. |
| Primary use | Joining austenitic stainless to carbon or low-alloy steel | Stainless-to-carbon-steel transition joints |
Which should you use?
Both are deliberately over-alloyed fillers that survive dilution from carbon steel, so either will make a sound stainless-to-carbon-steel joint or overlay buffer layer. The process is what differs. E309L, as a covered electrode, is portable and wind tolerant but leaves slag. ER309L, as bare filler, gives no slag and much finer control of heat input — which matters on overlay work, where keeping dilution low is the whole objective.
Choose E309L when
- Field repair and heavy dissimilar joints
- Outdoor and windy conditions
- Thick-section transition welds
Choose ER309L when
- Overlay and cladding where dilution control is critical
- Thin material and precise root passes
- Welds that will be inspected or ferrite tested
Amperage compared
| Diameter | E309L | ER309L |
|---|---|---|
| 3/32 in (2.4 mm) | 40–80 A | — |
| 1/8 in (3.2 mm) | 65–110 A | — |
| 5/32 in (4.0 mm) | 95–150 A | — |
| 3/16 in (4.8 mm) | 130–190 A | — |
| 0.030 in (0.8 mm) MIG | — | 50–150 A |
| 0.035 in (0.9 mm) MIG | — | 70–180 A |
| 0.045 in (1.2 mm) MIG | — | 100–250 A |
| 1/16 in (1.6 mm) TIG | — | 40–90 A |
| 3/32 in (2.4 mm) TIG | — | 70–130 A |
| 1/8 in (3.2 mm) TIG | — | 100–180 A |
Ranges are typical starting points. Diameters listed for only one electrode are shown as — for the other.
E309L vs ER309L — common questions
Which gives lower dilution on an overlay?
ER309L with TIG or pulsed MIG, because heat input and filler addition are controlled independently. That is why cladding procedures usually specify a bare-wire process for the buffer layer.
Is the deposited chemistry the same?
Effectively yes — both are nominal 23Cr-12Ni with 0.03–0.04% maximum carbon. Both retain ferrite after dilution, which is what prevents hot cracking.
Can I stick weld the buffer layer and MIG the rest?
Yes, that combination is common. The important thing is that the first layer on carbon steel is a 309-type filler, regardless of which process lays it.
Full specifications
E309L
AWS A5.4/A5.4M
E309L is the dissimilar-metal electrode — its extra chromium and nickel survive dilution when joining stainless to carbon steel or laying a stainless overlay.
ER309L
AWS A5.9/A5.9M
ER309L is the bare filler for welding stainless to carbon steel — over-alloyed at 23Cr-12Ni so the joint stays crack-free after dilution.