Copper Alloy C71520
UNS C71520
C71520 is a 70/30 copper-nickel used as AWS ERCuNi filler metal for welding copper-nickel piping and vessels in shipbuilding and desalination plants, and is on file in O60, H55, H01–H04, M10, M11, WO50 and as-welded conditions.
Reference datasheet — C71520 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 O60 condition
C71520 tempers and conditions
C71520 is supplied in 8 conditions, soft to hard. O60 is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O60Default Soft annealed | Default stock condition for seawater tube, plate and fittings — maximum formability and best corrosion behaviour. | 140 | 380 | 45 | 85 HB | 4.6 % IACS |
As hot forged and air cooled | Standard mill condition for hot-forged valve bodies, flanges and fittings that are not subsequently annealed. | 165 | 380 | 40 | 95 HB | 4.6 % IACS |
As forged and quenched | Forgings water-quenched from finishing temperature to retain a solutionised, scale-free structure with the best seawater corrosion behaviour. | 170 | 395 | 42 | 90 HB | 4.6 % IACS |
As-welded deposit | Deposited ERCuNi filler condition — use these numbers when sizing joints in 90/10 and 70/30 Cu-Ni piping and vessels. | 250 | 400 | 30 | 105 HB | 4.3 % IACS |
Light drawn | Choose for condenser/heat-exchanger tube needing slightly higher strength and straightness than fully annealed while still expandable into tubesheets. | 255 | 415 | 30 | 110 HB | 4.6 % IACS |
Quarter hard | Use where moderate strength increase is needed but the part still has to be bent or flared. | 310 | 450 | 25 | 125 HB | — |
Half hard | Intermediate strength strip, rod and tube for fasteners, sleeves and machined fittings. | 415 | 505 | 15 | 150 HB | 4.5 % IACS |
Full hard | Pick for maximum strength and stiffness in springs, shafting and hard-drawn tube where little further forming is required. | 525 | 585 | 8 | 175 HB | — |
Supply forms, finishes and certifications
Ways C71520 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
WO50 | Welded tube, welded and annealed | Surface finish |
What is C71520?
C71520 is a 70/30 copper-nickel used as AWS ERCuNi filler metal for welding copper-nickel piping and vessels in shipbuilding and desalination plants, and is on file in O60, H55, H01–H04, M10, M11, WO50 and as-welded conditions. Properties of 380 MPa tensile, 140 MPa yield, 45 % elongation and 85 HB match Cu-Ni base metal, with a weldability score of 90 and corrosion resistance score of 80. Thermal conductivity is 29 W/m·K, electrical conductivity 4.6 % IACS and maximum service temperature 350 °C; cost is high next to steel or brass, so it is specified where seawater performance must be maintained across the joint. C71520 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,171°C (2,140 °F). C71520 has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 380 MPa (55.1 ksi) — weaker than 74% of copper alloy grades. Elongation at break is 45% and the elastic modulus is 152 GPa (22 Msi).
What is C71520 used for?
- welding of Cu-Ni piping
- marine pipe fabrication
- condenser repair welds
Advantages
- Stiff — 152 GPa (22 Msi), better than 99% of copper alloy grades
- Readily welded — 90/100, better than 98% of copper alloy grades
- Good corrosion resistance — 80/100, better than 96% of copper alloy grades
- High service temperature — 350°C (662 °F), better than 95% of copper alloy grades
- Ductile — tolerates forming and impact — 45%, better than 91% of copper alloy grades
Limitations
- Low electrical conductivity — 4.6 % IACS, worse than 96% of copper alloy grades
- High embodied carbon — 6.6 kg CO₂/kg, worse than 96% of copper alloy grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 93% of copper alloy grades
- Difficult to machine — 25/100, worse than 86% of copper alloy grades
C71520 properties
Typical room-temperature values for C71520-O60; bars are the position among copper alloy grades.
Physical3
C71520 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,171°C (2,140 °F).
Mechanical14
C71520 has a yield strength of 140 MPa (20.3 ksi) and a tensile strength of 380 MPa (55.1 ksi) — weaker than 74% of copper alloy grades. Elongation at break is 45% and the elastic modulus is 152 GPa (22 Msi).
Thermal6
C71520 is rated for continuous service to 350°C (662 °F). It conducts heat at 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 93% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
C71520 conducts electricity at 4.6 % IACS, worse than 96% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 96% of copper alloy grades.
Sustainability4
Producing a kilogram of C71520 takes about 90 MJ of energy and emits 6.6 kg of CO₂ — more than 93% of copper alloy grades. Typical recycled content is 35%.
Manufacturability8
C71520's machinability is poor (25/100, worse than 86% of copper alloy grades); weldability excellent (90/100); formability excellent (90/100).
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 copper alloy family
Yield strength against density for every copper alloy grade FabDigit runs. C71520 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C71520
Is C71520 easy to machine?
Gummy and work-hardening — run sharp positive-rake carbide at low speed, heavy positive feed and generous coolant; rating only about 20% of AISI 1212.
Can C71520 be welded?
Very good with GTAW/GMAW using ERCuNi (Ti-deoxidised) filler, no preheat, low interpass temperature, and scrupulously clean, oil- and sulphur-free surfaces to avoid porosity and hot cracking.
Can C71520 be formed, bent or molded?
Excellent cold formability in O60 — deep draws, tube bends and expansions are routine; interanneal at 700–850 °C followed by rapid cooling after roughly 50% reduction, and hot work at 850–1000 °C.
C71520 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 |
|---|---|---|
| Ninickel plus cobalt | 29 – 33 | 31 |
| Feessential for erosion-corrosion resistance | 0.4 – 1 | 0.6 |
| Mn | ≤ 1 | 0.6 |
| Zn | ≤ 1 | |
| Pb0.02 max for condenser tube per ASTM B111 | ≤ 0.05 | |
| C | ≤ 0.05 | |
| S | ≤ 0.02 | |
| P | ≤ 0.02 | |
| Tionly in ERCuNi filler per AWS A5.7 (deoxidiser) | 0.2 – 0.5 | 0.3 |
| Cu65.0 % min including silver | balance |
What surface finishes work on C71520?
Takes a bright polish and self-forms a protective brown-green patina in seawater; do not anodize — use pickling/passivation, tin or nickel plating, or marine paint over an etch primer where colour matching is needed.
Surface treatments FabDigit runs on copper alloy 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).
Equivalent designations
Standards and trade names that resolve to Copper Alloy C71520 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- ERCuNi
How much does C71520 cost?
C71520 is a high-cost copper alloy ($$$$), 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.
C71520 — frequently asked
What is C71520 used for?
C71520 is typically used for welding of Cu-Ni piping, marine pipe fabrication and condenser repair welds. In short: 70/30 Cu-Ni filler metal; matches base-metal corrosion; top weldability in family.
What is the yield strength of C71520?
C71520 has a typical yield strength of 140 MPa (20.3 ksi) and a tensile strength of 380 MPa (55.1 ksi) — weaker than 74% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C71520 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 86% of copper alloy grades). Gummy and work-hardening — run sharp positive-rake carbide at low speed, heavy positive feed and generous coolant; rating only about 20% of AISI 1212.
Can C71520 be welded?
Yes — weldability is rated excellent (90/100). Very good with GTAW/GMAW using ERCuNi (Ti-deoxidised) filler, no preheat, low interpass temperature, and scrupulously clean, oil- and sulphur-free surfaces to avoid porosity and hot cracking.
What surface finishes work on C71520?
Takes a bright polish and self-forms a protective brown-green patina in seawater; do not anodize — use pickling/passivation, tin or nickel plating, or marine paint over an etch primer where colour matching is needed.
Can C71520 be formed, bent or molded?
Excellent cold formability in O60 — deep draws, tube bends and expansions are routine; interanneal at 700–850 °C followed by rapid cooling after roughly 50% reduction, and hot work at 850–1000 °C.
What is the maximum service temperature of C71520?
C71520 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C71520-O60 and C71520-H04?
O60 is the default condition — default stock condition for seawater tube, plate and fittings — maximum formability and best corrosion behaviour. H04: pick for maximum strength and stiffness in springs, shafting and hard-drawn tube where little further forming is required. Yield strength is 140 MPa in O60 versus 525 MPa in H04.
How much does C71520 cost?
C71520 is a high-cost copper alloy ($$$$), 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
- ASTM B111/B111M — Copper and Copper-Alloy Seamless Condenser Tubes — ASTM International (2021)
- ASTM B466/B466M — Seamless Copper-Nickel Pipe and Tube — ASTM International (2020)
- AWS A5.7/A5.7M — Copper and Copper-Alloy Bare Welding Rods and Electrodes (ERCuNi) — American Welding Society (2007)
- C71520 alloy datasheet — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Copper-Nickel Alloys: Properties and Applications in Seawater Systems — Nickel Institute / CDA (2018)
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.