Copper Alloy ERCuNi-AW (As-welded deposit)
Heat-treated state · default condition
UNS C71581 · GB HSCuNi
Default condition: undiluted all-weld-metal deposit properties used for procedure qualification and design.
Values for the AW condition
Other ERCuNi tempers and conditions
ERCuNi is listed in 3 conditions; see the grade overview at ERCuNi.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AW | Pick for higher deposition on thicker Cu-Ni pipe and plate; pulsed spray with argon or Ar-He keeps porosity down. | 215 | 395 | 30 | 92 HB | 4.5 % IACS |
AWDefaultThis page As-welded deposit | Default condition: undiluted all-weld-metal deposit properties used for procedure qualification and design. | 220 | 400 | 32 | 90 HB | 4.6 % IACS |
AW | Pick for root passes, thin-wall Cu-Ni tube and heat-exchanger work where the cleanest, lowest-oxygen deposit is needed. | 225 | 410 | 34 | 88 HB | 4.7 % IACS |
What is ERCuNi-AW?
ERCuNi-AW is ERCuNi heat treated to AW — default condition: undiluted all-weld-metal deposit properties used for procedure qualification and design. ERCuNi-AW has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 51% of copper alloy grades. Elongation at break is 32% and the elastic modulus is 152 GPa (22 Msi). ERCuNi-AW has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,170°C (2,138 °F).
Advantages
- Stiff — 152 GPa (22 Msi), better than 99% of copper alloy grades
- High service temperature — 315°C (599 °F), better than 92% of copper alloy grades
- Readily welded — 78/100, better than 91% of copper alloy grades
- Good corrosion resistance — 74/100, better than 88% of copper alloy grades
- Forms and bends easily — 75/100, better than 82% of copper alloy grades
Limitations
- Poor heat conductor — 28 W/m·K (16.2 BTU/hr·ft·°F), worse than 96% of copper alloy grades
- Low electrical conductivity — 4.6 % IACS, worse than 96% of copper alloy grades
- High embodied carbon — 6.2 kg CO₂/kg, worse than 93% of copper alloy grades
ERCuNi-AW properties
Typical room-temperature values for ERCuNi-AW; 20 are specific to this condition. Other listed values are ERCuNi reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
ERCuNi-AW has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,170°C (2,138 °F).
Mechanical14
ERCuNi-AW has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 51% of copper alloy grades. Elongation at break is 32% and the elastic modulus is 152 GPa (22 Msi).
Thermal6
ERCuNi-AW is rated for continuous service to 315°C (599 °F). It conducts heat at 28 W/m·K (16.2 BTU/hr·ft·°F), worse than 96% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
ERCuNi-AW conducts electricity at 4.6 % IACS, worse than 96% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (74/100), better than 88% of copper alloy grades.
Sustainability4
Producing a kilogram of ERCuNi-AW takes about 78 MJ of energy and emits 6.2 kg of CO₂ — more than 90% of copper alloy grades. Typical recycled content is 25%.
Manufacturability8
ERCuNi-AW's machinability is poor (28/100, worse than 78% of copper alloy grades); weldability very good (78/100); formability very good (75/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ERCuNi-AW
Is ERCuNi easy to machine?
Weld metal machines like 70/30 Cu-Ni — gummy, ~20 % of AISI 1212; use sharp positive-rake carbide, slow feeds and generous coolant.
Can ERCuNi be welded?
GTAW/GMAW with 100 % argon (or Ar-He) DCEN/DCEP; joints must be oil-, sulfur- and lead-free, use wide 70–80° grooves, stringer beads, low heat input and interpass ≤150 °C, no preheat or PWHT normally required.
Can ERCuNi be formed, bent or molded?
Supplied as cold-drawn spool or cut rod; the deposit itself is highly ductile and can be dressed or peened cold without cracking.
What surface finishes work on ERCuNi?
Pickle or wire-brush (stainless brush) to remove weld oxide; not anodizable — leave bare for natural patina/biofouling resistance or apply antifouling-compatible coatings only where required.
ERCuNi 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 |
|---|---|---|
| NiCo counted as Ni | 29 – 32 | 30.5 |
| Fe | 0.4 – 0.75 | 0.55 |
| Tideoxidizer, controls porosity | 0.2 – 0.5 | 0.35 |
| Mn | ≤ 1 | 0.6 |
| Si | ≤ 0.25 | 0.1 |
| C | ≤ 0.05 | 0.02 |
| P | ≤ 0.02 | — |
| S | ≤ 0.01 | — |
| Pb | ≤ 0.02 | — |
| Other, total | ≤ 0.5 | — |
| Cu | balance | — |
ERCuNi-AW — frequently asked
What is ERCuNi-AW used for?
ERCuNi-AW is typically used for seawater piping welds, shipboard CuNi tubing, offshore condenser tube repair and desalination plant piping. In short: matched 90/10 Cu-Ni filler; seawater corrosion resistance; sensitive to joint contamination.
What is the yield strength of ERCuNi-AW?
ERCuNi-AW has a typical yield strength of 220 MPa (31.9 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 51% of copper alloy grades. Strength varies by condition: see the 3 listed tempers.
Is ERCuNi-AW easy to machine?
Not especially — machinability is rated poor (28/100, worse than 78% of copper alloy grades). Weld metal machines like 70/30 Cu-Ni — gummy, ~20 % of AISI 1212; use sharp positive-rake carbide, slow feeds and generous coolant.
Can ERCuNi-AW be welded?
Yes — weldability is rated very good (78/100). GTAW/GMAW with 100 % argon (or Ar-He) DCEN/DCEP; joints must be oil-, sulfur- and lead-free, use wide 70–80° grooves, stringer beads, low heat input and interpass ≤150 °C, no preheat or PWHT normally required.
What surface finishes work on ERCuNi-AW?
Pickle or wire-brush (stainless brush) to remove weld oxide; not anodizable — leave bare for natural patina/biofouling resistance or apply antifouling-compatible coatings only where required.
Can ERCuNi-AW be formed, bent or molded?
Supplied as cold-drawn spool or cut rod; the deposit itself is highly ductile and can be dressed or peened cold without cracking.
What is the maximum service temperature of ERCuNi-AW?
ERCuNi-AW is rated for continuous use to about 315°C (599 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ERCuNi-AW and ERCuNi AW-GTAW?
AW is the default condition — default condition: undiluted all-weld-metal deposit properties used for procedure qualification and design. AW-GTAW: pick for root passes, thin-wall Cu-Ni tube and heat-exchanger work where the cleanest, lowest-oxygen deposit is needed. Yield strength is 220 MPa in AW versus 225 MPa in AW-GTAW.
Sources
- AWS A5.7/A5.7M — Specification for Copper and Copper Alloy Bare Welding Rods and Electrodes — AWS (2011)
- ASME BPVC Section II Part C, SFA-5.7 — ASME (2023)
- UNS C71581 / C71500 alloy data — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Copper-nickel filler metal datasheets (ERCuNi) — Various welding consumable producers (2023)
- Guide to the Welding of Copper-Nickel Alloys — Nickel Institute / CDA (2018)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.