*When the product is subsequent welding applications and so specified by the purchaser, Zn shall be .50% max., Pb .02% max., P .02% max., Sulfur .02% max. and Carbon .05% max.

General Copper Nickel information

Cu-Ni alloys are alloys of copper (base metal with the largest individual content) and nickel with or without other elements, whereby the zinc content may not be more than 1%. When other elements are present, nickel has the largest individual content after copper, compared with each other element. As with other copper alloys, it is necessary to distinguish between wrought alloys, which are processed to semi-finished products, and cast alloys, from which castings are produced by various casting processes. The Cu-Ni alloys with additions of manganese are important in electrical engineering. Additions of iron significantly improve the resistance of Cu-Ni alloys to erosion corrosion in flowing seawater and other aggressive waters.

Copper Nickel Applications

• Desalination
• Seawater Piping Systems

Copper Nickel Corrosion Resistance

Copper alloys have very good resistance to seawater, brine water, organic compounds, salts, diluted non-oxidizing acids, and more. CuNi 90/10 (C70600 & C7060X) is a Copper Nickel Iron alloy with a small content of manganese which allows excellent resistance to sea- and brakish water. Of all commercial coper alloys, CuNi 70/30 (C71500) offers the best resistance to aqueous corrosion. It is resistant to acid solutions and highly resistant to stress corrosion cracking, and impingement corrosion. In addition, CuNi70/30 offers a greater strength for higher pressures.

Copper Nickel Heat Resistance

The hot strength of copper increases with only a small addition of nickel. By adding iron, mechanical properties are improved, not only at room temperature, but also at elevated temperatures. 10% Ni. CuNi10Fe1Mn, for example, can be used in pressure vessel construction up to 300°C, CuNi30Mn1Fe up to 350°C. Above these limit temperatures, strength drops markedly, particularly the creep strength and creep strain limit.

Copper Nickel Heat Treatment

In general, heat treatments are only used with Cu-Ni alloys for soft annealing and stress relieving. Temperatures for recrystallisation annealing can vary over wide limits between about 620 and 900°C, depending on degree of cold work, nickel content and additional constituents. High temperatures are associated with short annealing times (continuous annealing) and low temperatures with long annealing times (static annealing). Stress-relief annealing is carried out at 280 to 500°C. It is advisable to anneal excluding air or in a slightly reducing atmosphere, to avoid the pickling that is required with air-containing annealing atmospheres.