ER347 – wire and rod for 321 and 347 stainless
Niobium-stabilized austenitic filler metal, used on 347 and 321 stainless that work in the sensitization range (about 425 to 850 °C).
Product forms and equivalents
| Process | Classification |
|---|---|
| TIG rod (GTAW) | ER347 |
| Solid MIG/MAG wire (GMAW) | ER347 / ER347Si |
| Covered electrode (SMAW) | E347-16/-17 – AWS A5.4 |
| Flux-cored wire (FCAW) | E347T0-1/-4 – AWS A5.22 |
| Submerged arc wire (SAW) | ER347 + flux |
| Designation | Value |
|---|---|
| AWS | ER347 |
| Specification | AWS A5.9/A5.9M / ASME SFA-5.9 |
| UNS | S34780 |
| Others | EN ISO 14343-A: W/G 19 9 Nb; W.Nr. 1.4551 |
Chemical composition (%)
| Element | wt. % |
|---|---|
| C | ≤ 0.08 |
| Cr | 19.0 – 21.5 |
| Ni | 9.0 – 11.0 |
| Mo | ≤ 0.75 |
| Mn | 1.0 – 2.5 |
| Si | 0.30 – 0.65 |
| P | ≤ 0.03 |
| S | ≤ 0.03 |
| Cu | ≤ 0.75 |
| Nb | 10 × C min. – 1.0 |
Properties of the deposited metal
| Property | Value |
|---|---|
| Tensile strength of deposited metal | ≥ 520 MPa (AWS A5.4 minimum for E347, reference) |
| Elongation | ≥ 30 % (AWS A5.4 minimum for E347, reference) |
Materials welded with ER347
Why the composition differs from the base metal
321 stainless is stabilized with titanium, but titanium oxidizes and is lost in the electric arc. That is why the wire uses niobium, which crosses the arc and keeps tying up the carbon as niobium carbides, keeping the bead stabilized.
Welding precautions
- No preheating; interpass up to 150 °C.
- Keep the bead ferrite within the recommended range to avoid hot cracking, to which Nb is sensitive.
- 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 ER347 used for?
Niobium-stabilized austenitic filler metal, used on 347 and 321 stainless that work in the sensitization range (about 425 to 850 °C).
Why is the composition of ER347 different from the material it welds?
321 stainless is stabilized with titanium, but titanium oxidizes and is lost in the electric arc. That is why the wire uses niobium, which crosses the arc and keeps tying up the carbon as niobium carbides, keeping the bead stabilized.
Which covered electrode corresponds to ER347?
E347-16/-17 – AWS A5.4.
What precautions apply when welding with ER347?
No preheating; interpass up to 150 °C. Keep the bead ferrite within the recommended range to avoid hot cracking, to which Nb is sensitive. TIG shielding with pure argon; in MIG/MAG use argon with 1–2 % O2 or 2–3 % CO2. Argon root purge in tubes.
