Copper Alloy C71640
UNS C71640
C71640 is a higher-manganese 70/30 copper-nickel developed for resistance to erosion-corrosion in high-velocity seawater piping, available in O61, H55, HR50 and WO50 within the C70000-series wrought Cu-Ni specifications.
Reference datasheet — C71640 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 O61 condition
C71640 tempers and conditions
C71640 is supplied in 3 conditions, soft to hard. O61 is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O61Default Annealed | Standard stocked condition for seawater condenser and heat-exchanger tube where bending, expanding and tube-sheet rolling are required. | 220 | 515 | 35 | 120 HB | 4.3 % IACS |
Light drawn | Light cold-drawn tube giving straighter, stiffer lengths with moderate strength gain where no heavy re-forming is needed. | 330 | 550 | 20 | 150 HB | — |
Drawn and stress relieved | Choose for high-pressure or high-velocity seawater piping needing 345 MPa minimum yield with residual stresses removed to avoid SCC. | 380 | 570 | 18 | 160 HB | 4.2 % IACS |
Supply forms, finishes and certifications
Ways C71640 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, annealed after welding | Surface finish |
What is C71640?
C71640 is a higher-manganese 70/30 copper-nickel developed for resistance to erosion-corrosion in high-velocity seawater piping, available in O61, H55, HR50 and WO50 within the C70000-series wrought Cu-Ni specifications. It is the strongest grade in this group at 515 MPa tensile, 220 MPa yield, 35 % elongation and 120 HB, with a corrosion resistance score of 80, and is normally bought as seamless tube and pipe. Thermal conductivity is 25 W/m·K, electrical conductivity 4.3 % IACS and the service limit is 300 °C; machinability is 28 and availability is limited, with C71500 the more widely stocked alternative. C71640 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). C71640 has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 515 MPa (74.7 ksi) — weaker than 51% of copper alloy grades. Elongation at break is 35% and the elastic modulus is 152 GPa (22 Msi).
What is C71640 used for?
- high-velocity seawater piping
- naval piping systems
- condenser tubes
Advantages
- Stiff — 152 GPa (22 Msi), better than 99% of copper alloy grades
- Good corrosion resistance — 80/100, better than 96% of copper alloy grades
- Readily welded — 85/100, better than 95% of copper alloy grades
- High service temperature — 300°C (572 °F), better than 85% of copper alloy grades
- Forms and bends easily — 80/100, better than 83% of copper alloy grades
Limitations
- Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 98% of copper alloy grades
- Low electrical conductivity — 4.3 % IACS, worse than 98% of copper alloy grades
- High embodied carbon — 7.5 kg CO₂/kg, worse than 97% of copper alloy grades
C71640 properties
Typical room-temperature values for C71640-O61; bars are the position among copper alloy grades.
Physical3
C71640 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).
Mechanical13
C71640 has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 515 MPa (74.7 ksi) — weaker than 51% of copper alloy grades. Elongation at break is 35% and the elastic modulus is 152 GPa (22 Msi).
Thermal6
C71640 is rated for continuous service to 300°C (572 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 98% of copper alloy grades. Thermal expansion is 15.9 µm/m·K (8.83 µin/in·°F).
Electrical3
C71640 conducts electricity at 4.3 % IACS, worse than 98% 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 C71640 takes about 95 MJ of energy and emits 7.5 kg of CO₂ — more than 95% of copper alloy grades. Typical recycled content is 30%.
Manufacturability8
C71640's machinability is poor (28/100, worse than 78% of copper alloy grades); weldability excellent (85/100); formability very good (80/100).
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. C71640 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C71640
Is C71640 easy to machine?
Tough and gummy — use sharp positive-rake carbide, low speed/heavy positive feed and copious coolant to avoid work hardening and built-up edge (≈20% of free-cutting brass).
Can C71640 be welded?
Readily GTAW/GMAW welded with matching 70/30 Cu-Ni filler (ERCuNi); keep interpass low, no preheat, and use very clean, oxide- and sulfur-free surfaces to avoid porosity and hot cracking.
Can C71640 be formed, bent or molded?
Excellent cold formability in O61 for bending, expanding and tube-sheet rolling; intermediate anneals ~700–800 °C needed for heavy cold work, and drawn tempers should be stress-relieved before seawater service.
C71640 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 |
|---|---|---|
| NiNi + Co | 29 – 32 | 30 |
| Feraises erosion-corrosion resistance | 1.7 – 2.3 | 2 |
| Mnkey distinction vs C71500 | 1.5 – 2.5 | 2 |
| Zn | ≤ 1 | |
| Pb | ≤ 0.05 | |
| C | ≤ 0.06 | |
| S | ≤ 0.03 | |
| P | ≤ 0.02 | |
| Curemainder, nominally ~64–66% | balance |
What surface finishes work on C71640?
Not anodizable; pickle/passivate before commissioning and grow the protective oxide with clean flowing seawater — avoid sulfide-polluted water during start-up; can be polished or coated but usually used bare.
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).
How much does C71640 cost?
C71640 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.
C71640 — frequently asked
What is C71640 used for?
C71640 is typically used for high-velocity seawater piping, naval piping systems and condenser tubes. In short: strongest Cu-Ni here; erosion-corrosion resistant 70/30; high-velocity seawater grade.
What is the yield strength of C71640?
C71640 has a typical yield strength of 220 MPa (31.9 ksi) and a tensile strength of 515 MPa (74.7 ksi) — weaker than 51% of copper alloy grades. Strength varies by condition: see the 3 listed tempers.
Is C71640 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 78% of copper alloy grades). Tough and gummy — use sharp positive-rake carbide, low speed/heavy positive feed and copious coolant to avoid work hardening and built-up edge (≈20% of free-cutting brass).
Can C71640 be welded?
Yes — weldability is rated excellent (85/100). Readily GTAW/GMAW welded with matching 70/30 Cu-Ni filler (ERCuNi); keep interpass low, no preheat, and use very clean, oxide- and sulfur-free surfaces to avoid porosity and hot cracking.
What surface finishes work on C71640?
Not anodizable; pickle/passivate before commissioning and grow the protective oxide with clean flowing seawater — avoid sulfide-polluted water during start-up; can be polished or coated but usually used bare.
Can C71640 be formed, bent or molded?
Excellent cold formability in O61 for bending, expanding and tube-sheet rolling; intermediate anneals ~700–800 °C needed for heavy cold work, and drawn tempers should be stress-relieved before seawater service.
What is the maximum service temperature of C71640?
C71640 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C71640-O61 and C71640-HR50?
O61 is the default condition — standard stocked condition for seawater condenser and heat-exchanger tube where bending, expanding and tube-sheet rolling are required. HR50: choose for high-pressure or high-velocity seawater piping needing 345 MPa minimum yield with residual stresses removed to avoid SCC. Yield strength is 220 MPa in O61 versus 380 MPa in HR50.
How much does C71640 cost?
C71640 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 and Ferrule Stock — ASTM International (2021)
- ASTM B466/B466M — Seamless Copper-Nickel Pipe and Tube — ASTM International (2020)
- CDA Alloy Database — C71640 — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
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.