Copper nickel alloys: properties, processing and main applications

Thursday July 2nd, 2020 | Sangjoo Kim | Expertise, Technical Expertise

What is the Cupronickel?

CuNi is an alloy made of Copper and Nickel with less than 0.5% of other alloys. It is also known as cupronickel. There are two popular combinations of CuNi; 70% Copper/30% Nickel or 90% Copper/10% Nickel. 90/10 is most used on marine, offshore oil and gas platform while 70/30 is more commonly used in Navy since it has much more anti-corrosion ability and expensive. These percentages can vary from 69% to 96% of Copper and rest in Nickel but 70/30 and 90/10 are the most common combinations.

Properties of CuNi:

As it contains mostly copper and nickel, it combines the advantages of these two alloys. Copper enjoys low reactivity, excellent heat and electrical conductivity, great corrosion resistance, and machinability. On the other hand, nickel has got high strength and toughness, and excellent corrosion resistance. Beside these properties, CuNi is also non-bacterial, non-magnetic, light weight, and spark and pitting resistance. The corrosion resistance especially of the 90/10 alloy is due to a protective surface film that forms when the alloy comes into contact with water and seawater. The alloy is also resistant to corrosion that occurs through chemical and electrochemical processes. Therefore, copper’s low reactivity leads to less chemical/electrochemical processes.

Main Applications:

With these various advantages compared to other alloys, CuNi is well found in shipbuilding and marine hardware. For example, guidelines for seawater system design and operation, offshore oil and gas, power generation, ship repair, and marine antimicrobial applications. Also, since CuNi is easy to fabricate, CuNi can be applied to many designs.


Listed products are the products that can be produced with CuNi other than pipes:

  • Concentric reducers
  • Tubes
  • Elbows
  • T-piece
  • Flanges
  • Sockets
  • Reducing Tees
  • Caps
  • Saddle Pieces
  • Welding Outlets

Furthermore, average production ranges of pipes and tubes, fittings, and flanges are shown below:

Materials :
Cupro Nickel Flanges – CuNi Flanges
UNS C 70600 ( CU -NI- 90/10) – DIN 2.0872
UNS C 71500 ( CU -NI- 70/30) – DIN 2.0882

CuNi Flange Types:

  • Weld Neck Flanges
  • Slip On Flanges
  • Blind Flanges
  • Backing Flanges
  • Socket Weld Flanges
  • Plate Flanges
  • Loose Flanges
  • Orifice Flanges
  • AS 4087 Water Flanges
  • Large Diameter Flanges
  • Sorf Flanges
  • Table Flanges
  • Socket Weld Ring Flanges
  • Threaded Ring Flanges
  • Lap Joint Ring Flanges
  • Ring Type Joint Flanges
  • Blind Ring Flanges
  • Reducing Flanges
  • Tongue & Groove Flanges
  • Puddle Flanges

Other Copper Alloys Grades:

  • C61400, Aluminum Bronze , ASTM B 171 CDA 614
  • C63000, Nickel Aluminum Bronze, ASTM B 150 CDA 630 , ASTM B171
  • C70600, Cu-Ni 90/10, Cupro-Nickel 90/10
  • C71500, Cu-Ni 70/30, Cupro-Nickel 70/30
  • C46400, Naval Brass, ASTM B21 , ASTM B171
  • C36500, Copper-zinc brass

Non-marine Applications:

Non-marine applications include coinage such as silver coins and brake tubing. For example: 1-euro coin, 2-euro coin, and 5 US cent. The 1 euro bimetallic coin’s external part is made of Nickel brass alloy (75% copper, 20% zinc, 5% nickel) and the internal part is made of Cupronickel alloy (75% copper, 25% nickel ). The 2 euro coin’s internal part is made of nickel brass alloy (75% copper, 20% zinc, 5% nickel) and the external part of cupronickel alloy (75% copper, 25% nickel). The yellow color is given by a nickel brass alloy CuZn20Ni5, while the white color is given by a cupronickel alloy CuNi25. The 5 US cent coin is made of cupronickel alloy (75% copper, 25% nickel) This is because CuNi is known as hygienic due to non-bacterial properties.

Source: Federal Ministry of Finance presents the euro countries


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