Stainless Steel ER347
UNS S34780 · JIS Y347 · ISO 19 9 Nb
ER347 is a niobium-stabilized austenitic stainless bare wire (UNS S34780, also listed as Y347) for welding titanium- or niobium-stabilized 321 and 347 base metals.
Reference datasheet — ER347 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AW condition
ER347 tempers and conditions
ER347 is supplied in 4 conditions, soft to hard. AW is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
stabilization anneal 870–900 °C / air cool after welding | Choose when the joint will see prolonged 425–815 °C service or severe nitric-acid duty; ties residual carbon into NbC and relieves welding stress. | 350 | 580 | 42 | 150 HB | 2.4 % IACS |
As-welded weld metal | For high-deposition-rate multi-pass welds on heavy stainless plate; check flux for Nb recovery so stabilization ratio is maintained. | 395 | 590 | 34 | 172 HB | 2.4 % IACS |
As-welded weld metal | Pick for spray-transfer MIG deposition on thicker sections; slightly lower toughness than GTAW due to higher heat input and oxygen pick-up. | 405 | 610 | 35 | 180 HB | 2.4 % IACS |
AWDefault As-welded deposit | Default condition: all-weld-metal deposited by GTAW with argon shielding, no post-weld heat treatment. | 420 | 620 | 38 | 175 HB | 2.4 % IACS |
Supply forms, finishes and certifications
Ways ER347 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
WIRE-CD | Wire as supplied | Supply form |
Cryo | AW | Certification |
What is ER347?
ER347 is a niobium-stabilized austenitic stainless bare wire (UNS S34780, also listed as Y347) for welding titanium- or niobium-stabilized 321 and 347 base metals. It resists intergranular corrosion at elevated temperature, is qualified in cryogenic as well as stabilizing heat-treated conditions, and is supplied as cold-drawn spool wire and cut rod for GTAW, GMAW and SAW. As-welded deposits are about 420 MPa yield, 620 MPa tensile, 38 % elongation and 175 HB (87 HRB), with service listed to 815 C. Niobium segregation makes it more hot-crack sensitive than ER308L, which is the alternative when stabilization is not required. ER347 has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,400°C (2,552 °F). ER347 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 64% of stainless steel grades. Elongation at break is 38% and the elastic modulus is 195 GPa (28.3 Msi).
What is ER347 used for?
- stabilized stainless piping
- high-temperature pressure vessels
- aerospace ducting
Advantages
- Readily welded — 88/100, better than 91% of stainless steel grades
- High service temperature — 815°C (1,499 °F), better than 77% of stainless steel grades
Limitations
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
ER347 properties
Typical room-temperature values for ER347-AW; bars are the position among stainless steel grades.
Physical3
ER347 has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
ER347 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 64% of stainless steel grades. Elongation at break is 38% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
ER347 is rated for continuous service to 815°C (1,499 °F). It conducts heat at 16.1 W/m·K (9.3 BTU/hr·ft·°F), better than 61% of stainless steel grades. Thermal expansion is 16.6 µm/m·K (9.22 µin/in·°F).
Electrical3
ER347 conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), better than 59% of stainless steel grades.
Sustainability4
Producing a kilogram of ER347 takes about 60 MJ of energy and emits 5.5 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
ER347's machinability is fair (35/100, better than 51% of stainless steel grades); weldability excellent (88/100); formability fair (50/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. ER347 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ER347
Is ER347 easy to machine?
Deposited weld metal machines like 347 bar — low speed, positive rake, rigid setup and heavy feed to cut under the work-hardened layer; expect ~45 % of AISI 1212 rates.
Can ER347 be welded?
Use DCEN for GTAW / DCEP for GMAW with Ar or Ar+He (add ≤2 % O₂ or CO₂ for spray MIG); keep interpass below ~150 °C, low heat input and stringer beads to limit hot cracking and Nb segregation; no preheat and normally no PWHT.
Can ER347 be formed, bent or molded?
Supplied as drawn wire — coil straightening and light bending only; the deposited austenitic metal is very ductile but work-hardens rapidly when cold formed.
ER347 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CAWS A5.9 max | ≤ 0.08 | 0.05 |
| Cr | 19 – 21.5 | 20 |
| Ni | 9 – 11 | 10 |
| Mn | 1 – 2.5 | 1.7 |
| Si | 0.3 – 0.65 | 0.45 |
| Nb+Ta10×C min, 1.00 max (Nb+Ta) | 0.5 – 1 | 0.7 |
| Moresidual | ≤ 0.75 | |
| Curesidual | ≤ 0.75 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on ER347?
Pickle/passivate (ASTM A380/A967) or mechanically blend and electropolish the bead to restore the chromium oxide film; never anodize.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel ER347 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S34780
- ISO
- 19 9 Nb
- JIS
- Y347
How much does ER347 cost?
ER347 is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
ER347 — frequently asked
What is ER347 used for?
ER347 is typically used for stabilized stainless piping, high-temperature pressure vessels and aerospace ducting. In short: nb-stabilized 347 filler; service to 815 C; cryogenic-qualified deposit.
What is the yield strength of ER347?
ER347 has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 64% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is ER347 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of stainless steel grades). Deposited weld metal machines like 347 bar — low speed, positive rake, rigid setup and heavy feed to cut under the work-hardened layer; expect ~45 % of AISI 1212 rates.
Can ER347 be welded?
Yes — weldability is rated excellent (88/100). Use DCEN for GTAW / DCEP for GMAW with Ar or Ar+He (add ≤2 % O₂ or CO₂ for spray MIG); keep interpass below ~150 °C, low heat input and stringer beads to limit hot cracking and Nb segregation; no preheat and normally no PWHT.
What surface finishes work on ER347?
Pickle/passivate (ASTM A380/A967) or mechanically blend and electropolish the bead to restore the chromium oxide film; never anodize.
Can ER347 be formed, bent or molded?
Supplied as drawn wire — coil straightening and light bending only; the deposited austenitic metal is very ductile but work-hardens rapidly when cold formed.
What is the maximum service temperature of ER347?
ER347 is rated for continuous use to about 815°C (1,499 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER347-AW and ER347 AW-SAW?
AW is the default condition — default condition: all-weld-metal deposited by GTAW with argon shielding, no post-weld heat treatment. AW-SAW: for high-deposition-rate multi-pass welds on heavy stainless plate; check flux for Nb recovery so stabilization ratio is maintained. Yield strength is 420 MPa in AW versus 395 MPa in AW-SAW.
How much does ER347 cost?
ER347 is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- AWS A5.9/A5.9M Bare Stainless Steel Welding Electrodes and Rods — American Welding Society (2017)
- ASME BPVC Section II Part C, SFA-5.9 — ASME (2023)
- EN ISO 14343 (19 9 Nb) — ISO (2017)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.6: Welding, Brazing and Soldering — ASM International (1993)
- Stainless filler metal weld-metal typical property sheets (Böhler, ESAB, Lincoln) — various (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.