70/30 copper-nickel C71500 – UNS C71500
Copper-nickel alloy with high marine corrosion resistance
Alloy with ≈ 30% Ni and small additions of Fe and Mn, the most corrosion-resistant of the copper-nickel family. It withstands higher flow velocities, polluted seawater and higher pressures than 90/10, with higher strength as well. Used in high-performance condensers, exchangers and piping on ships, power plants and desalination plants.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | C71500 |
| W.Nr./EN | CW354H – CuNi30Mn1Fe |
| DIN | 2.0882 (CuNi30Mn1Fe) |
| JIS | C7150 |
| Trade names | 70/30 copper-nickel, CuNi 70/30 |
| Others | MIL-T-16420, MIL-T-15005 (tube); MIL-C-15726; SAE J461/J463 |
Standards by product form
| Form | Standard |
|---|---|
| Tube | ASTM B111/B111M (condenser), B466 (seamless), B467 (welded), B543, B552 |
| Plate | ASTM B122/B122M; B171/B171M (tubesheets) |
| Bar | ASTM B151/B151M |
| Bar | ASTM F467 / F468 (nuts and bolts) |
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 7407.29.10 | 7407.29 | 7407.29.4000 | 7407 29 00 |
| Hot-rolled bar | 7407.29.10 | 7407.29 | 7407.29.4000 | 7407 29 00 |
| Plate (> 10 mm, width ≥ 600 mm) | 7409.40.90 | 7409.40 | 7409.40.0000 | 7409 40 00 |
| Seamless pipe | 7411.22.10 | 7411.22 | 7411.22.0000 | 7411 22 00 |
| Welded pipe | 7411.22.10 | 7411.22 | 7411.22.0000 | 7411 22 00 |
Tariff class: copper-nickel alloy (cupronickel) (by chemical composition, under the Chapter 72 Notes and Section XV Note 5).
*: US and EU codes for reference. NCM per current legislation (General Rules of Interpretation, Notes to Chapters 72, 74 and 75 and Section XV Note 5). Confirm the final code with your customs broker according to the item size and finish. HS = first 6 digits of the NCM.
Chemical composition (%)
ASTM B111 / B466 (UNS C71500)
| Element | Range (%) |
|---|---|
| Ni (+Co) | 29.0 – 33.0 |
| Fe | 0.40 – 1.0 |
| Mn | ≤ 1.0 |
| Zn | ≤ 1.0 |
| Pb | ≤ 0.05 |
| Cu | balance (Cu + named elements ≥ 99.5) |
Mechanical properties
typical (CDA); annealed tube minimums per ASTM B111
| Property | Value |
|---|---|
| Annealed tube (OS025): tensile strength | ≈ 414 MPa |
| Annealed tube (OS025): elongation | ≈ 45% |
| Annealed tube (O61): minimum tensile strength | ≥ 360 MPa* |
| Annealed tube (O61): minimum yield strength (0.5%) | ≥ 125 MPa* |
| Half-hard bar (H02): tensile strength | ≈ 517 MPa |
| Hardness (annealed) | ≈ 36 – 45 HRB |
Typical physical properties
| Property | Value |
|---|---|
| Density | 8.94 g/cm³ |
| Melting range | 1,171 – 1,238 °C |
| Modulus of elasticity | 152 GPa |
| Electrical conductivity | ≈ 4.6% IACS |
| Thermal conductivity (20 °C) | ≈ 29 W/m·K |
| Thermal expansion (20–300 °C) | 16.2 µm/m·K |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | Usual from sub-zero temperatures up to ≈ 370 °C*. In seawater, typical design velocity up to ≈ 4.5 m/s in tubes*. |
| Heat treatment | Annealing at ≈ 650 – 815 °C. Hot working between ≈ 925 and 1,040 °C. Not hardenable by heat treatment, only by cold work. |
| Welding | Excellent by TIG/MIG, covered electrode, spot, seam and butt welding. Consumables AWS A5.7 ERCuNi and A5.6 ECuNi. Excellent brazing and soft soldering. |
| Machining | Ductile, gummy material (≈ 20, C36000 = 100). Sharp tool, positive rake, constant feed and coolant. |
Typical applications
- High-performance condenser and heat exchanger tubes
- Seawater piping with high flow or polluted water
- Desalination plants and feedwater heaters
- Exchanger tubesheets and pump components
- Marine fasteners (ASTM F467/F468)
Alternatives: 90/10 copper-nickel C70600 when flow is moderate and cost matters; Monel 400 for higher strength and HF service; nickel-aluminum bronze C63000 for mechanical parts in seawater.
Frequently asked questions
What is the chemical composition of 70/30 copper-nickel C71500?
Per ASTM B111 / B466 (UNS C71500): Ni (+Co) 29.0 – 33.0; Fe 0.40 – 1.0; Mn ≤ 1.0; Zn ≤ 1.0; Pb ≤ 0.05; Cu balance (Cu + named elements ≥ 99.5).
Which standards cover 70/30 copper-nickel C71500?
Tube: ASTM B111/B111M (condenser), B466 (seamless), B467 (welded), B543, B552. Plate: ASTM B122/B122M; B171/B171M (tubesheets). Bar: ASTM B151/B151M. Bar: ASTM F467 / F468 (nuts and bolts).
Up to what temperature can 70/30 copper-nickel C71500 be used?
Usual from sub-zero temperatures up to ≈ 370 °C*. In seawater, typical design velocity up to ≈ 4.5 m/s in tubes*.
Which materials can replace 70/30 copper-nickel C71500?
90/10 copper-nickel C70600 when flow is moderate and cost matters; Monel 400 for higher strength and HF service; nickel-aluminum bronze C63000 for mechanical parts in seawater.
