Stainless Steel ER320
UNS N08021
ER320 is a Carpenter 20-type superaustenitic bare wire (UNS N08021) with a Cr-Mo-Cu chemistry aimed at sulfuric acid and severely corrosive chemical service.
Reference datasheet — ER320 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
ER320 tempers and conditions
ER320 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 |
|---|---|---|---|---|---|---|
Solution Annealed | Pick when the fabricated Alloy 20 weldment is post-weld solution annealed for maximum acid corrosion resistance and ductility. | 300 | 560 | 42 | 160 HB | 1.6 % IACS |
AWDefault As-welded deposit | Default condition for filler metal: properties of the undiluted as-deposited weld metal. | 380 | 585 | 34 | 180 HB | 1.6 % IACS |
Supply forms, finishes and certifications
Ways ER320 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
ROD-CUT | Cut-length TIG rod | Supply form |
WIRE-SPOOL | Spooled MIG wire | Supply form |
LR | ER320LR | Certification |
What is ER320?
ER320 is a Carpenter 20-type superaustenitic bare wire (UNS N08021) with a Cr-Mo-Cu chemistry aimed at sulfuric acid and severely corrosive chemical service. It is used to weld Alloy 20 base metals and for corrosion-resistant overlay, and is supplied as spooled wire and cut rod for GTAW, GMAW and SAW. As-welded deposits give about 380 MPa yield, 585 MPa tensile, 34 % elongation and 180 HB (88 HRB), with service listed to 500 C. In restrained multipass joints use ER320LR instead, which is formulated with lower residuals to reduce hot cracking. ER320 has a density of 8.02 g/cm³ (0.29 lb/in³), heavier than 97% of stainless steel grades. It melts at 1,370°C (2,498 °F). ER320 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 52% of stainless steel grades. Elongation at break is 34% and the elastic modulus is 193 GPa (28 Msi).
What is ER320 used for?
- Sulfuric acid equipment
- Chemical processing tanks
- Alloy 20 pump and valve bodies
- Pickling line tanks and piping
- Acid mixers and agitator shafts
- Corrosion-resistant overlay on carbon steel
- Heat exchanger shells in acid service
Advantages
- Good corrosion resistance — 80/100, better than 88% of stainless steel grades
Limitations
- Low electrical conductivity — 1.6 % IACS, worse than 99% of stainless steel grades
- High embodied carbon — 8.5 kg CO₂/kg, worse than 99% of stainless steel grades
- Poor heat conductor — 12.6 W/m·K (7.28 BTU/hr·ft·°F), worse than 88% of stainless steel grades
ER320 properties
Typical room-temperature values for ER320-AW; bars are the position among stainless steel grades.
Physical3
ER320 has a density of 8.02 g/cm³ (0.29 lb/in³), heavier than 97% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical16
ER320 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 52% of stainless steel grades. Elongation at break is 34% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
ER320 is rated for continuous service to 500°C (932 °F). It conducts heat at 12.6 W/m·K (7.28 BTU/hr·ft·°F), worse than 88% of stainless steel grades. Thermal expansion is 14.8 µm/m·K (8.22 µin/in·°F).
Electrical3
ER320 conducts electricity at 1.6 % IACS, worse than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 88% of stainless steel grades.
Sustainability4
Producing a kilogram of ER320 takes about 95 MJ of energy and emits 8.5 kg of CO₂ — more than 96% of stainless steel grades. Typical recycled content is 30%.
Manufacturability8
ER320's machinability is poor (26/100, worse than 84% of stainless steel grades); weldability good (68/100); 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. ER320 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ER320
Is ER320 easy to machine?
Weld deposit machines like a gummy high-nickel austenitic: sharp positive-rake carbide, low speed, heavy positive feed, flood coolant, no dwelling.
Can ER320 be welded?
GTAW/GMAW/SAW with low heat input, interpass ≤ 100–150 °C and stringer beads; argon (or Ar+He) shielding and back purge; use ER320LR for restrained multipass joints to avoid hot cracking.
Can ER320 be formed, bent or molded?
Supplied as drawn wire; work-hardens quickly, so redrawing needs intermediate anneals — not a wrought structural product form.
ER320 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 |
|---|---|---|
| CER320LR: 0.025 max | ≤ 0.07 | 0.05 |
| Cr | 19 – 21 | 20 |
| Ni | 32 – 36 | 34 |
| Mo | 2 – 3 | 2.5 |
| Cu | 3 – 4 | 3.5 |
| NbCb+Ta, 8×C min to 1.00 max; ER320LR 0.15–0.35 | 0.4 – 1 | 0.7 |
| MnER320LR: 1.50–2.00 | ≤ 2.5 | 1.8 |
| SiER320LR: 0.15 max | ≤ 0.6 | 0.35 |
| PER320LR: 0.015 max | ≤ 0.04 | 0.02 |
| SER320LR: 0.015 max | ≤ 0.03 | 0.01 |
| Febalance, ~36 % | balance |
What surface finishes work on ER320?
Pickle and passivate weld areas (nitric/HF paste) to restore the Cr-Mo-Cu passive film; do not anodize; grind heat tint fully before acid service.
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 ER320 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- N08021
How much does ER320 cost?
ER320 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.
ER320 — frequently asked
What is ER320 used for?
ER320 is typically used for sulfuric acid equipment, chemical processing tanks, alloy 20 pump and valve bodies, pickling line tanks and piping, acid mixers and agitator shafts and corrosion-resistant overlay on carbon steel. In short: alloy 20 filler wire; built for sulfuric acid; highest corrosion rating here.
What is the yield strength of ER320?
ER320 has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 52% of stainless steel grades. Strength varies by condition: see the 2 listed tempers.
Is ER320 easy to machine?
Not especially — machinability is rated poor (26/100, worse than 84% of stainless steel grades). Weld deposit machines like a gummy high-nickel austenitic: sharp positive-rake carbide, low speed, heavy positive feed, flood coolant, no dwelling.
Can ER320 be welded?
Yes — weldability is rated good (68/100). GTAW/GMAW/SAW with low heat input, interpass ≤ 100–150 °C and stringer beads; argon (or Ar+He) shielding and back purge; use ER320LR for restrained multipass joints to avoid hot cracking.
What surface finishes work on ER320?
Pickle and passivate weld areas (nitric/HF paste) to restore the Cr-Mo-Cu passive film; do not anodize; grind heat tint fully before acid service.
Can ER320 be formed, bent or molded?
Supplied as drawn wire; work-hardens quickly, so redrawing needs intermediate anneals — not a wrought structural product form.
What is the maximum service temperature of ER320?
ER320 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER320-AW and ER320-SA?
AW is the default condition — default condition for filler metal: properties of the undiluted as-deposited weld metal. SA: pick when the fabricated Alloy 20 weldment is post-weld solution annealed for maximum acid corrosion resistance and ductility. Yield strength is 380 MPa in AW versus 300 MPa in SA.
How much does ER320 cost?
ER320 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 — AWS (2017)
- ASME BPVC Section II Part C, SFA-5.9 — ASME (2023)
- Alloy 20 / 20Cb-3 physical and corrosion data — Carpenter Technology (2022)
- ER320 / ER320LR filler metal all-weld-metal properties — Special Metals Welding Products / Sandvik (2021)
- ASM Handbook Vol. 6 — Welding, Brazing and Soldering — ASM International (1993)
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.