Copper Alloy C71000-O61
Heat-treated state · default condition
UNS C71000 · GB B19
O61 = annealed
Standard stocked condition for condenser/heat-exchanger tube and deep-drawn parts; maximum ductility and formability.
Values for the O61 condition
Other C71000 tempers and conditions
C71000 is listed in 7 conditions; see the grade overview at C71000.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O61DefaultThis page Annealed | Standard stocked condition for condenser/heat-exchanger tube and deep-drawn parts; maximum ductility and formability. | 110 | 340 | 40 | 75 HB | 6.5 % IACS |
As hot rolled | Hot-rolled plate/bar taken as-produced; used where plate is later formed, welded or machined and temper is not critical. | 140 | 365 | 35 | 82 HB | 6.5 % IACS |
Quarter hard | Light cold work for parts needing more stiffness/strength than annealed while retaining good bending ability. | 275 | 415 | 20 | 105 HB | 6.5 % IACS |
Half hard | General-purpose strengthened strip/bar; good balance of strength and moderate forming for brackets and fittings. | 415 | 480 | 12 | 135 HB | 6.5 % IACS |
Full hard | High-strength strip/wire for flat springs, contacts and wear parts where only gentle bending is required. | 515 | 550 | 5 | 160 HB | 6.5 % IACS |
Extra hard | For flat springs and stamped parts needing near-maximum strength with minimal forming after rolling. | 550 | 585 | 4 | 175 HB | 6.5 % IACS |
Spring hard | Maximum cold-worked strength for spring strip and wire; very limited ductility, bends only along favourable grain direction. | 570 | 620 | 3 | 185 HB | 6.5 % IACS |
What is C71000-O61?
C71000-O61 is C71000 heat treated to O61 — standard stocked condition for condenser/heat-exchanger tube and deep-drawn parts; maximum ductility and formability. C71000-O61 has a yield strength of 110 MPa (16 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 82% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 138 GPa (20 Msi). C71000-O61 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,099°C (2,010 °F).
Advantages
- Stiff — 138 GPa (20 Msi), better than 95% of copper alloy grades
- Readily welded — 85/100, better than 95% of copper alloy grades
- High service temperature — 320°C (608 °F), better than 93% of copper alloy grades
- Polishes to a fine finish — 85/100, better than 92% of copper alloy grades
- Good corrosion resistance — 75/100, better than 90% of copper alloy grades
Limitations
- Difficult to machine — 20/100, worse than 98% of copper alloy grades
- Low electrical conductivity — 6.5 % IACS, worse than 91% of copper alloy grades
- High embodied carbon — 5.2 kg CO₂/kg, worse than 88% of copper alloy grades
- Poor heat conductor — 37 W/m·K (21.4 BTU/hr·ft·°F), worse than 85% of copper alloy grades
- Low strength — 110 MPa (16 ksi), worse than 82% of copper alloy grades
C71000-O61 properties
Typical room-temperature values for C71000-O61; 19 are specific to this condition. Other listed values are C71000 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C71000-O61 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,099°C (2,010 °F).
Mechanical13
C71000-O61 has a yield strength of 110 MPa (16 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 82% of copper alloy grades. Elongation at break is 40% and the elastic modulus is 138 GPa (20 Msi).
Thermal6
C71000-O61 is rated for continuous service to 320°C (608 °F). It conducts heat at 37 W/m·K (21.4 BTU/hr·ft·°F), worse than 85% of copper alloy grades. Thermal expansion is 15.6 µm/m·K (8.67 µin/in·°F).
Electrical3
C71000-O61 conducts electricity at 6.5 % IACS, worse than 91% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (75/100), better than 90% of copper alloy grades.
Sustainability4
Producing a kilogram of C71000-O61 takes about 72 MJ of energy and emits 5.2 kg of CO₂ — more than 86% of copper alloy grades. Typical recycled content is 30%.
Manufacturability8
C71000-O61's machinability is poor (20/100, worse than 98% of copper alloy grades); weldability excellent (85/100); formability excellent (90/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C71000-O61
Is C71000 easy to machine?
Gummy and work-hardening — use sharp, positive-rake carbide, rigid setups, heavy feeds at 25–60 m/min with flood coolant; rating ≈20 % of free-cutting brass.
Can C71000 be welded?
Excellent with GTAW/GMAW using ERCuNi (70/30) filler; keep interpass clean and sulfur/lead free, no preheat, low heat input to avoid hot cracking.
Can C71000 be formed, bent or molded?
Anneal at 700–800 °C for deep drawing and tube bending; cold-work rates are high so interstage annealing is needed above ~40 % reduction.
What surface finishes work on C71000?
Not anodizable — polishes to a bright silvery finish, accepts tin, nickel or chrome plating; natural protective oxide should be allowed to form for seawater service.
C71000 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 | 19 – 23 | 20 |
| Fe | ≤ 1 | 0.5 |
| Mn | ≤ 1 | 0.5 |
| Zn | ≤ 1 | — |
| Pb | ≤ 0.05 | — |
| CuCu + Ag = remainder, ≈78 % | balance | — |
C71000-O61 — frequently asked
What is C71000-O61 used for?
C71000-O61 is typically used for condenser tubes, ferrule stock, marine tubing and coinage stock. In short: mid-nickel 80/20 Cu-Ni; between 90/10 and 70/30; coinage and condenser strip.
What is the yield strength of C71000-O61?
C71000-O61 has a typical yield strength of 110 MPa (16 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 82% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C71000-O61 easy to machine?
Not especially — machinability is rated poor (20/100, worse than 98% of copper alloy grades). Gummy and work-hardening — use sharp, positive-rake carbide, rigid setups, heavy feeds at 25–60 m/min with flood coolant; rating ≈20 % of free-cutting brass.
Can C71000-O61 be welded?
Yes — weldability is rated excellent (85/100). Excellent with GTAW/GMAW using ERCuNi (70/30) filler; keep interpass clean and sulfur/lead free, no preheat, low heat input to avoid hot cracking.
What surface finishes work on C71000-O61?
Not anodizable — polishes to a bright silvery finish, accepts tin, nickel or chrome plating; natural protective oxide should be allowed to form for seawater service.
Can C71000-O61 be formed, bent or molded?
Anneal at 700–800 °C for deep drawing and tube bending; cold-work rates are high so interstage annealing is needed above ~40 % reduction.
What is the maximum service temperature of C71000-O61?
C71000-O61 is rated for continuous use to about 320°C (608 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C71000-O61 and C71000-H08?
O61 is the default condition — standard stocked condition for condenser/heat-exchanger tube and deep-drawn parts; maximum ductility and formability. H08: maximum cold-worked strength for spring strip and wire; very limited ductility, bends only along favourable grain direction. Yield strength is 110 MPa in O61 versus 570 MPa in H08.
Sources
- ASTM B111/B111M — Copper and Copper-Alloy Seamless Condenser Tubes — ASTM International (2021)
- ASTM B122/B122M — Copper-Nickel Plate, Sheet, Strip and Rolled Bar — ASTM International (2022)
- CDA Alloy Datasheet C71000 (UNS C71000) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (copper-nickel in seawater) — ASM International (2005)
- GB/T 2059 / GB/T 8890 (B19) (2017)
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.