ER309L – wire and rod for stainless-to-carbon steel joints
Low-carbon 23Cr-13Ni filler metal, used to join stainless to carbon or low-alloy steel and as a buttering layer before stainless overlay.
Product forms and equivalents
| Process | Classification |
|---|---|
| TIG rod (GTAW) | ER309L |
| Solid MIG/MAG wire (GMAW) | ER309L / ER309LSi |
| Covered electrode (SMAW) | E309L-16/-17 – AWS A5.4 |
| Flux-cored wire (FCAW) | E309LT0-1/-4 – AWS A5.22 |
| Submerged arc wire (SAW) | ER309L + flux |
| Designation | Value |
|---|---|
| AWS | ER309L |
| Specification | AWS A5.9/A5.9M / ASME SFA-5.9 |
| UNS | S30983 |
| Others | EN ISO 14343-A: W/G 23 12 L; W.Nr. 1.4332 |
Chemical composition (%)
| Element | wt. % |
|---|---|
| C | ≤ 0.03 |
| Cr | 23.0 – 25.0 |
| Ni | 12.0 – 14.0 |
| Mo | ≤ 0.75 |
| Mn | 1.0 – 2.5 |
| Si | 0.30 – 0.65 |
| P | ≤ 0.03 |
| S | ≤ 0.03 |
| Cu | ≤ 0.75 |
Properties of the deposited metal
| Property | Value |
|---|---|
| Tensile strength of deposited metal | ≥ 520 MPa (AWS A5.4 minimum for E309L, reference) |
| Elongation | ≥ 30 % (AWS A5.4 minimum for E309L, reference) |
Materials welded with ER309L
Dissimilar joints: Typical joint: 304L/316L stainless with carbon steel (e.g. an A105 flange) or with Cr-Mo steel at moderate temperature. When a joint with 316L must keep molybdenum in the bead, for pitting resistance, ER309LMo is used. Also used on martensitic and ferritic stainless (416, 431, 446) when an austenitic bead, softer than the base metal, is acceptable.
Why the composition differs from the base metal
It is more highly alloyed than 304 on purpose. When the bead mixes with carbon steel, which has no Cr or Ni, dilution lowers the alloy content; starting from 23Cr-13Ni the result is still austenitic with a little ferrite, without brittle martensite or cracks.
Welding precautions
- Control dilution: torch angle toward the stainless side and moderate heat input.
- Preheat the carbon steel or martensitic side according to thickness and carbon equivalent.
- Not indicated above about 370 °C in joints with carbon steel because of carbon migration; in that case prefer a nickel alloy.
- TIG shielding with pure argon; in MIG/MAG use argon with 1–2 % O2 or 2–3 % CO2. Argon root purge in tubes.
Frequently asked questions
What is ER309L used for?
Low-carbon 23Cr-13Ni filler metal, used to join stainless to carbon or low-alloy steel and as a buttering layer before stainless overlay.
Why is the composition of ER309L different from the material it welds?
It is more highly alloyed than 304 on purpose. When the bead mixes with carbon steel, which has no Cr or Ni, dilution lowers the alloy content; starting from 23Cr-13Ni the result is still austenitic with a little ferrite, without brittle martensite or cracks.
Which covered electrode corresponds to ER309L?
E309L-16/-17 – AWS A5.4.
What precautions apply when welding with ER309L?
Control dilution: torch angle toward the stainless side and moderate heat input. Preheat the carbon steel or martensitic side according to thickness and carbon equivalent. Not indicated above about 370 °C in joints with carbon steel because of carbon migration; in that case prefer a nickel alloy. TIG shielding with pure argon; in MIG/MAG use argon with 1–2 % O2 or 2–3 % CO2. Argon root purge in tubes.
