Copper Alloy C71700-OS025
Temper
UNS C71700
OS025 = annealed to 0.025 mm grain size
Grain-size-controlled anneal for sheet/strip that must be deep drawn or spun without orange peel.
Values for the OS025 condition
Other C71700 tempers and conditions
C71700 is listed in 7 conditions; see the grade overview at C71700.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OS025This page Annealed to 0.025 mm grain size | Grain-size-controlled anneal for sheet/strip that must be deep drawn or spun without orange peel. | 150 | 390 | 45 | 80 HB | 4.6 % IACS |
O61Default Annealed | Standard stocked condition for seawater and aerospace tubing where bending, flaring and welding are required. | 160 | 400 | 42 | 85 HB | 4.6 % IACS |
Light drawn | Choose for straight tube lengths needing better handling stiffness while still allowing moderate bending. | 275 | 450 | 25 | 118 HB | 4.5 % IACS |
Quarter hard | Mild cold work for flat products that still need forming after cutting. | 310 | 470 | 22 | 125 HB | 4.6 % IACS |
Half hard | General structural flat/rod condition balancing strength and residual formability. | 420 | 540 | 14 | 155 HB | 4.6 % IACS |
Hard drawn | Highest-pressure tubing condition; use where hoop strength governs and no further cold bending is needed. | 515 | 585 | 10 | 9 HRC | 4.5 % IACS |
Full hard | Maximum as-drawn/rolled strength for springs, fasteners and wear faces; minimal further forming. | 550 | 620 | 8 | 13 HRC | 4.5 % IACS |
What is C71700-OS025?
C71700-OS025 is C71700 in the OS025 temper — grain-size-controlled anneal for sheet/strip that must be deep drawn or spun without orange peel. C71700-OS025 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 390 MPa (56.6 ksi) — weaker than 69% of copper alloy grades. Elongation at break is 45% and the elastic modulus is 152 GPa (22 Msi). C71700-OS025 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). O61 is the default condition FabDigit quotes; OS025 is available on request or by drawing note.
Advantages
- Good corrosion resistance — 83/100, better than 100% of copper alloy grades
- Stiff — 152 GPa (22 Msi), better than 99% of copper alloy grades
- Readily welded — 90/100, better than 98% 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
- Difficult to machine — 20/100, worse than 98% of copper alloy grades
- High embodied carbon — 7.5 kg CO₂/kg, worse than 97% of copper alloy grades
- Low electrical conductivity — 4.6 % IACS, 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
C71700-OS025 properties
Typical room-temperature values for C71700-OS025; 20 are specific to this condition. Other listed values are C71700 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C71700-OS025 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
C71700-OS025 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 390 MPa (56.6 ksi) — weaker than 69% of copper alloy grades. Elongation at break is 45% and the elastic modulus is 152 GPa (22 Msi).
Thermal6
C71700-OS025 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
C71700-OS025 conducts electricity at 4.6 % IACS, worse than 96% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (83/100), better than 100% of copper alloy grades.
Sustainability4
Producing a kilogram of C71700-OS025 takes about 105 MJ of energy and emits 7.5 kg of CO₂ — more than 97% of copper alloy grades. Typical recycled content is 30%.
Manufacturability8
C71700-OS025's machinability is poor (20/100, worse than 98% of copper alloy grades); weldability excellent (90/100); formability excellent (90/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C71700-OS025
Is C71700 easy to machine?
Gummy and work-hardening — use sharp positive-rake carbide, low speed (~30–60 m/min), heavy feed, rigid setup and flood coolant to avoid built-up edge.
Can C71700 be welded?
Excellent GTAW/GMAW with CuNi 70/30 (ERCuNi) filler; the Nb addition suppresses weld hot cracking and porosity — keep interpass low, no preheat, argon backing, and avoid sulphur/lead contamination.
Can C71700 be formed, bent or molded?
Very good cold formability in O61 (bend radii ≈1t); high work-hardening rate means interstage anneals at 700–850 °C with rapid cool for severe draws; hot work 900–1050 °C.
What surface finishes work on C71700?
Cannot be anodised; pickle in inhibited sulphuric/chromate-free solutions, then leave bare (self-forming protective oxide in seawater), or electroplate Ni/Sn or lacquer for decorative use — polishes to a bright silvery finish.
C71700 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 – 33 | 31 |
| Feerosion-corrosion resistance | 0.4 – 1 | 0.7 |
| Mndeoxidiser | 0.4 – 1 | 0.7 |
| Nbcolumbium; stabilises weld metal | 0.2 – 0.7 | 0.45 |
| Zn | ≤ 1 | — |
| Pb | ≤ 0.05 | — |
| C | ≤ 0.05 | — |
| S | ≤ 0.02 | — |
| P | ≤ 0.02 | — |
| Curemainder, ~65–68 % | balance | — |
C71700-OS025 — frequently asked
What is C71700-OS025 used for?
C71700-OS025 is typically used for aircraft hydraulic tubing, fuel lines and seawater piping. In short: weldable 70/30 copper-nickel; aerospace hydraulic tube alloy; highest formability in family.
What is the yield strength of C71700-OS025?
C71700-OS025 has a typical yield strength of 150 MPa (21.8 ksi) and a tensile strength of 390 MPa (56.6 ksi) — weaker than 69% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C71700-OS025 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, low speed (~30–60 m/min), heavy feed, rigid setup and flood coolant to avoid built-up edge.
Can C71700-OS025 be welded?
Yes — weldability is rated excellent (90/100). Excellent GTAW/GMAW with CuNi 70/30 (ERCuNi) filler; the Nb addition suppresses weld hot cracking and porosity — keep interpass low, no preheat, argon backing, and avoid sulphur/lead contamination.
What surface finishes work on C71700-OS025?
Cannot be anodised; pickle in inhibited sulphuric/chromate-free solutions, then leave bare (self-forming protective oxide in seawater), or electroplate Ni/Sn or lacquer for decorative use — polishes to a bright silvery finish.
Can C71700-OS025 be formed, bent or molded?
Very good cold formability in O61 (bend radii ≈1t); high work-hardening rate means interstage anneals at 700–850 °C with rapid cool for severe draws; hot work 900–1050 °C.
What is the maximum service temperature of C71700-OS025?
C71700-OS025 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 C71700-O61 and C71700-H04?
O61 is the default condition — standard stocked condition for seawater and aerospace tubing where bending, flaring and welding are required. H04: maximum as-drawn/rolled strength for springs, fasteners and wear faces; minimal further forming. Yield strength is 160 MPa in O61 versus 550 MPa in H04.
Sources
- ASTM B466/B466M — Seamless Copper-Nickel Pipe and Tube — ASTM International (2020)
- ASTM B122/B122M — Copper-Nickel-Zinc, Copper-Nickel Plate, Sheet, Strip and Rolled Bar — ASTM International (2021)
- CDA Standard Designations for Wrought Copper Alloys (UNS C71700) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (Copper-Nickel in Seawater) — ASM International (2005)
- Copper-Nickel Alloys — Properties and Fabrication Guide — Nickel Institute / CDA UK (2016)
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.