Copper Nickel Alloy 90/10 – UNS C70600

Copper nickel alloy 90/10, also known as UNS C70600, CuNi10Fe1Mn, or simply Cupronickel, is an alloy containing approximately 90% copper and 10% nickel, with small additions of iron and manganese. This alloy offers moderate strength, high thermal stability at elevated temperatures, and excellent oxidation resistance in moist air and steam.

90/10 copper nickel (C70600) has great resistance to seawater corrosion due to the presence of significant amounts of manganese and iron. It is also immune to chloride stress-corrosion cracking – making it a preferred choice where stainless steel cannot be used.

Nickel is fully soluble in copper, giving C70600 a single-phase alpha structure. This provides good ductility and fabricability while maintaining high inherent resistance to biofouling.

GNEE supplies C70600 to meet all major global standards. Use this table for cross-referencing.

Common names: 90/10 Cu-Ni, CuNi10Fe1Mn, Cupronickel 90/10, ASTM B111 C70600, Copper Nickel 90/10.

C70600 is widely used in marine and industrial environments. Common applications include:

Q1: What is the difference between UNS C70600 (90/10 Cupronickel) and UNS C71500 (70/30 Cupronickel) for heat exchanger tubes?
A: UNS C70600 (90/10 Cu-Ni) contains 10% nickel and is more cost-effective. UNS C71500 (70/30 Cu-Ni) contains 30% nickel, offering higher strength and better erosion resistance at higher water velocities. For most seawater heat exchangers, ASTM B111 C70600 tube is sufficient.

Q2: What is the European equivalent to ASTM B111 C70600 seamless tube?
A: The European equivalent to ASTM B111 C70600 is DIN 2.0872 or CuNi10Fe1Mn. Under EN standards, it is CW352H.

Q3: Can UNS C70600 (90/10 Copper Nickel) be welded to stainless steel 316L?
A: Yes, C70600 can be welded to 316L stainless steel using ERNiCu-7 or AWS A5.7 ERCuNi filler metals. However, galvanic corrosion protection (e.g., coated flanges or cathodic protection) is recommended for seawater service.

Q4: What is the maximum operating temperature for UNS C70600 (CuNi10Fe1Mn) tube in condensers?
A: C70600 tube can operate continuously up to 300°C (572°F). Above this temperature, strength decreases. For higher temperatures, consider C71500.

Q5: Does ASTM B151 C70600 round bar require post-weld heat treatment?
A: No, C70600 typically does not require post-weld heat treatment. Stress relief annealing at 593-816°C may be used for heavily welded sections or to relieve residual stresses from cold working.

Q6: Is UNS C70600 (90/10 Cupronickel) resistant to ammonia stress-corrosion cracking?
A: Yes. C70600 failures due to stress-corrosion cracking are unknown in seawater polluted with ammonia, making it superior to many other copper alloys (e.g., brass) in this respect.

Q7: What is the forging temperature range for UNS C70600 (90/10 Copper Nickel)?
A: The recommended forging temperature for C70600 is 843 – 954°C (1550 – 1750°F).

Q8: What filler metal should be used for TIG welding UNS C70600 (CuNi10Fe1Mn) to itself?
A: For TIG welding C70600, use AWS A5.7 ERCuNi filler metal. It matches the 90/10 composition and provides good corrosion resistance.

Q9: What is the machinability rating of ASTM B466 C70600 pipe?
A: C70600 pipe has a machinability rating of 20% (UNS C36000 free-cutting brass = 100%). Use sharp carbide tools and ample coolant.

Q10: What product forms are available for UNS C70600 (90/10 Cupronickel) from GNEE?
A: C70600 is available as: seamless tube (ASTM B111), pipe (ASTM B466), round bar (ASTM B151), plate (ASTM B171), sheet, fittings, flanges, and forgings.

Q11: Is UNS C70600 (CuNi10Fe1Mn) suitable for desalination plants?
A: Yes, C70600 is one of the most common materials for desalination plant tubing due to its excellent resistance to chloride corrosion and biofouling.

Q12: What is the thermal conductivity of UNS C70600 (90/10 Copper Nickel)?
A: C70600 has a thermal conductivity of approximately 40-50 W/mK (depending on source). This is lower than pure copper but adequate for heat exchanger applications.

Q13: What is the difference between ASTM B111 C70600 and ASTM B466 C70600?
A: ASTM B111 C70600 covers seamless tubes specifically for heat exchangers and condensers. ASTM B466 C70600 covers seamless pipe for general piping systems. Both are the same C70600 alloy.

Q14: How is ASTM B111 C70600 tube inspected at GNEE?
A: Each C70600 tube undergoes chemical analysis, tensile testing, flattening test, expansion test, hydrostatic or eddy current testing, dimensional inspection, and visual inspection. Mill test reports (MTR) are traceable to heat number.

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