Stainless Steel ER318
UNS S31980, S31900
ER318 is a niobium-stabilized 316-type austenitic stainless bare wire (UNS S31980 / S31900), the bare-wire counterpart to the E318 covered electrode.
Reference datasheet — ER318 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
ER318 tempers and conditions
ER318 is supplied in 2 conditions, soft to hard. AW is the default FabDigit quotes; the values on this page are for it.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
deposit solution annealed ~1050 °C and quenched | Choose when the fabricated assembly is solution annealed for maximum ductility, ferrite reduction and homogeneous corrosion resistance. | 300 | 550 | 42 | 160 HB | 2.3 % IACS |
AWDefault As-welded deposit | Default condition for design: undiluted deposit properties directly after welding, no post-weld heat treatment. | 420 | 590 | 33 | 190 HB | 2.3 % IACS |
Supply forms, finishes and certifications
Ways ER318 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-Ann | Wire, solution annealed | Supply form |
WIRE-CD | Wire, cold drawn / bright | Supply form |
What is ER318?
ER318 is a niobium-stabilized 316-type austenitic stainless bare wire (UNS S31980 / S31900), the bare-wire counterpart to the E318 covered electrode. Engineers use it to weld stabilized 316Ti and 316Nb base metals, where the niobium addition ties up carbon and limits sensitization in service to 800 C; it is supplied as cold-drawn spool wire and cut rod for GTAW, GMAW and SAW. As-welded properties are about 420 MPa yield, 590 MPa tensile, 33 % elongation and 190 HB (90 HRB). It is a specialty item with limited stock, and ER316L is the common alternative where stabilization is not specified. ER318 has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,375°C (2,507 °F). ER318 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 64% of stainless steel grades. Elongation at break is 33% and the elastic modulus is 196 GPa (28.4 Msi).
What is ER318 used for?
- Welding stabilized 316Ti/316Nb piping
- High-temperature chemical process piping
- Pressure vessel seams in stabilized 316
- Heat exchanger shells and nozzles
- Refinery flanges and fittings
- Stabilized stainless storage tanks
Advantages
- Readily welded — 88/100, better than 91% of stainless steel grades
ER318 properties
Typical room-temperature values for ER318-AW; bars are the position among stainless steel grades.
Physical3
ER318 has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,375°C (2,507 °F).
Mechanical16
ER318 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 64% of stainless steel grades. Elongation at break is 33% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
ER318 is rated for continuous service to 800°C (1,472 °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 16.2 µm/m·K (9 µin/in·°F).
Electrical3
ER318 conducts electricity at 2.3 % IACS, better than 55% 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 ER318 takes about 55 MJ of energy and emits 4.2 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
ER318's machinability is poor (32/100, worse than 62% 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. ER318 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ER318
Is ER318 easy to machine?
Weld deposits machine like 316: low speeds, positive-rake sharp carbide, heavy rigid setup and flood coolant to avoid work-hardened glazing; Nb carbides are abrasive on tool edges.
Can ER318 be welded?
Use GTAW/GMAW/SAW with pure Ar or Ar+2% CO₂ (or Ar-He for TIG), low interpass temperature (<150 °C), no preheat and no PWHT; keep 4–10 FN ferrite for hot-crack resistance.
Can ER318 be formed, bent or molded?
Not a forming product — supplied as drawn wire; cold-drawn spool wire must be kept clean and dry to avoid feed problems and porosity.
ER318 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 |
|---|---|---|
| CNb stabilizes carbon against sensitization | ≤ 0.08 | 0.05 |
| Cr | 18 – 20 | 19 |
| Ni | 11 – 14 | 12.5 |
| Mo | 2 – 3 | 2.5 |
| Nb+Tamin = 8 × C content | ≤ 1 | 0.6 |
| Mn | 1 – 2.5 | 1.8 |
| Si | 0.3 – 0.65 | 0.45 |
| Cu | ≤ 0.75 | 0.1 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Fe | balance |
What surface finishes work on ER318?
Pickle and passivate or electropolish the weld to restore the passive film; grind off heat tint and slag before service in chloride media.
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 ER318 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S31980S31900
How much does ER318 cost?
ER318 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.
ER318 — frequently asked
What is ER318 used for?
ER318 is typically used for welding stabilized 316Ti/316Nb piping, high-temperature chemical process piping, pressure vessel seams in stabilized 316, heat exchanger shells and nozzles, refinery flanges and fittings and stabilized stainless storage tanks. In short: nb-stabilized 316 wire; bare-wire E318 counterpart; stabilized service to 800 C.
What is the yield strength of ER318?
ER318 has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 64% of stainless steel grades. Strength varies by condition: see the 2 listed tempers.
Is ER318 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% of stainless steel grades). Weld deposits machine like 316: low speeds, positive-rake sharp carbide, heavy rigid setup and flood coolant to avoid work-hardened glazing; Nb carbides are abrasive on tool edges.
Can ER318 be welded?
Yes — weldability is rated excellent (88/100). Use GTAW/GMAW/SAW with pure Ar or Ar+2% CO₂ (or Ar-He for TIG), low interpass temperature (<150 °C), no preheat and no PWHT; keep 4–10 FN ferrite for hot-crack resistance.
What surface finishes work on ER318?
Pickle and passivate or electropolish the weld to restore the passive film; grind off heat tint and slag before service in chloride media.
Can ER318 be formed, bent or molded?
Not a forming product — supplied as drawn wire; cold-drawn spool wire must be kept clean and dry to avoid feed problems and porosity.
What is the maximum service temperature of ER318?
ER318 is rated for continuous use to about 800°C (1,472 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER318-AW and ER318 AW-SA?
AW is the default condition — default condition for design: undiluted deposit properties directly after welding, no post-weld heat treatment. AW-SA: choose when the fabricated assembly is solution annealed for maximum ductility, ferrite reduction and homogeneous corrosion resistance. Yield strength is 420 MPa in AW versus 300 MPa in AW-SA.
How much does ER318 cost?
ER318 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)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 6 — Welding, Brazing, and Soldering — ASM International (1993)
- Stainless filler metal datasheets (318/316Nb type) — voestalpine 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.