Stainless Steel ER309
UNS S30980 · EN 23 12
ER309 is a 23Cr-12Ni austenitic stainless bare welding wire (UNS S30980, 23 12), the bare-wire counterpart to the E309 covered electrode, carrying enough excess chromium and nickel to survive dilution from carbon and low-alloy steel.
Reference datasheet — ER309 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
ER309 tempers and conditions
ER309 is supplied in 5 conditions, soft to hard. AW is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Post-weld heat treated | Use when the fabrication is solution annealed after welding: ferrite is partly dissolved, strength drops and ductility/corrosion resistance recover. | 300 | 550 | 45 | 160 HB | 2.2 % IACS |
AW | High-deposition strip/wire cladding and heavy-section joints; properties depend strongly on flux, dilution runs higher. | 380 | 580 | 35 | 180 HB | 2.2 % IACS |
AW | Cut-length TIG rod deposit; cleanest, lowest-oxygen weld metal with the best toughness — pick for root passes and thin sections. | 390 | 590 | 40 | 175 HB | 2.2 % IACS |
AWDefault As-welded deposit | Standard reference condition: undiluted all-weld-metal tested as deposited, no post-weld heat treatment. | 400 | 600 | 38 | 180 HB | 2.2 % IACS |
AW | Spooled solid wire deposit for semi-automatic/robotic overlay; slightly higher strength and lower toughness than TIG because of oxidising shielding gas. | 410 | 610 | 36 | 185 HB | 2.2 % IACS |
Supply forms, finishes and certifications
Ways ER309 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 |
What is ER309?
ER309 is a 23Cr-12Ni austenitic stainless bare welding wire (UNS S30980, 23 12), the bare-wire counterpart to the E309 covered electrode, carrying enough excess chromium and nickel to survive dilution from carbon and low-alloy steel. It is chosen for dissimilar-metal joints and for buffer or overlay cladding, and is supplied as cold-drawn spooled MIG wire and cut TIG rod. As-welded deposits run about 400 MPa yield, 600 MPa tensile, 38% elongation and 180 HB (89 HRB), with scaling resistance to 1000 °C. Carbon is not restricted, so where intergranular attack in wet corrosive service is a concern, use ER309L or ER309LSi instead. ER309 has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F). ER309 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 38% and the elastic modulus is 196 GPa (28.4 Msi).
What is ER309 used for?
- Dissimilar joints between carbon steel and stainless steel
- Buffer layers under stainless or nickel-alloy overlay
- Weld overlay cladding of carbon steel vessels
- Stainless-clad plate seam and edge welds
- Transition joints in piping systems
- Repair welds on 309-type heat-resisting fabrications
- Furnace and high-temperature ductwork joints
Advantages
- Readily welded — 92/100, better than 98% of stainless steel grades
- High service temperature — 1,000°C (1,832 °F), better than 88% of stainless steel grades
ER309 properties
Typical room-temperature values for ER309-AW; bars are the position among stainless steel grades.
Physical3
ER309 has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
ER309 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 38% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
ER309 is rated for continuous service to 1,000°C (1,832 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
ER309 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (72/100), better than 73% of stainless steel grades.
Sustainability4
Producing a kilogram of ER309 takes about 62 MJ of energy and emits 5.2 kg of CO₂ — more than 75% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
ER309's machinability is poor (34/100, worse than 55% of stainless steel grades); weldability excellent (92/100); formability good (60/100).
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. ER309 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ER309
Is ER309 easy to machine?
Machining applies to the deposit/overlay: austenitic, gummy and work-hardening — rigid setup, sharp positive-rake carbide, heavy feed, flood coolant, no dwelling.
Can ER309 be welded?
Run with DCEN (GTAW) or DCEP (GMAW), Ar or Ar+2%O₂/Ar-He, low heat input and interpass ≤150 °C; aim for 8–15 FN ferrite to avoid hot cracking in dilute dissimilar joints.
Can ER309 be formed, bent or molded?
Supplied as cold-drawn wire; keep spool cast/helix within spec and use U-groove or knurl-free drive rolls plus a low-friction liner to prevent birdnesting.
ER309 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 |
|---|---|---|
| Cnon-L grade; ER309L is ≤0.03 | ≤ 0.12 | 0.08 |
| Cr | 23 – 25 | 24 |
| Ni | 12 – 14 | 13 |
| Mn | 1 – 2.5 | 1.8 |
| SiER309Si raises Si to 0.65–1.00 | 0.3 – 0.65 | 0.45 |
| Moresidual | ≤ 0.75 | |
| Curesidual | ≤ 0.75 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on ER309?
Pickle and passivate or mechanically blend the bead; do not anodise — grinding debris from carbon steel must be removed to avoid rust staining on the overlay.
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 ER309 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S30980
- EN / DIN / Werkstoff-Nr.
- 23 12
How much does ER309 cost?
ER309 is a premium-cost stainless steel ($$$), cheaper than about 51% 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.
ER309 — frequently asked
What is ER309 used for?
ER309 is typically used for dissimilar joints between carbon steel and stainless steel, buffer layers under stainless or nickel-alloy overlay, weld overlay cladding of carbon steel vessels, stainless-clad plate seam and edge welds, transition joints in piping systems and repair welds on 309-type heat-resisting fabrications. In short: standard dissimilar-metal filler; tolerates high carbon-steel dilution; service to 1000 °C.
What is the yield strength of ER309?
ER309 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 57% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is ER309 easy to machine?
Not especially — machinability is rated poor (34/100, worse than 55% of stainless steel grades). Machining applies to the deposit/overlay: austenitic, gummy and work-hardening — rigid setup, sharp positive-rake carbide, heavy feed, flood coolant, no dwelling.
Can ER309 be welded?
Yes — weldability is rated excellent (92/100). Run with DCEN (GTAW) or DCEP (GMAW), Ar or Ar+2%O₂/Ar-He, low heat input and interpass ≤150 °C; aim for 8–15 FN ferrite to avoid hot cracking in dilute dissimilar joints.
What surface finishes work on ER309?
Pickle and passivate or mechanically blend the bead; do not anodise — grinding debris from carbon steel must be removed to avoid rust staining on the overlay.
Can ER309 be formed, bent or molded?
Supplied as cold-drawn wire; keep spool cast/helix within spec and use U-groove or knurl-free drive rolls plus a low-friction liner to prevent birdnesting.
What is the maximum service temperature of ER309?
ER309 is rated for continuous use to about 1,000°C (1,832 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER309-AW and ER309 PWHT?
AW is the default condition — standard reference condition: undiluted all-weld-metal tested as deposited, no post-weld heat treatment. PWHT: use when the fabrication is solution annealed after welding: ferrite is partly dissolved, strength drops and ductility/corrosion resistance recover. Yield strength is 400 MPa in AW versus 300 MPa in PWHT.
How much does ER309 cost?
ER309 is a premium-cost stainless steel ($$$), cheaper than about 51% 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 — AWS (2017)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Specialty Handbook — Stainless Steels — ASM International (1994)
- ER309 / 309Si solid wire datasheets — Böhler Welding / ESAB / Lincoln Electric (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.