Copper-nickel (also known as cupronickel) alloys are copper in which nickel is added to increase strength and corrosion resistance while allowing the alloy to remain ductile. Other elements can be added to copper-nickel alloys to improve strength, corrosion resistance, hardenability, weldability and castability. It is widely used in marine applications due to its excellent seawater corrosion resistance, low macro-fouling rate, and good manufacturability. They have provided reliable service for decades while providing effective solutions to today's technological challenges.
90-10 copper-nickel alloy (C70600, CW352H), an alloy of 90% copper and 10% nickel, is the most commonly used alloy. It can be found in naval and commercial shipping, offshore oil and gas production, and desalination and power generation. Alloys with 30% nickel (C71500, C71640) and alloys more highly alloyed with aluminium, chromium or tin are used where greater resistance to seawater flow, sanding, abrasion and abrasion and higher mechanical properties are required .
Industry Applications:
Marine: Seawater system design and operation guidelines are presented; seawater system components are detailed; chapters cover Cu-Ni in desalination plants, offshore oil and gas, power generation, shipbuilding and ship repair, hull and marine antimicrobial applications.
Non-Marine: Mint; Brake Hose.
Alloy | UNS | Ni | Fe | Mn | Cr | Cu |
90-10 | C70600 | 9-11 | 1.0-1.8 | 1.0 Max | - | Bal |
70-30 | C71500 | 29-33 | 0.4-1.0 | 1.0 Max | - | Bal |
66-30-2-2 | C71640 | 29-32 | 1.7-2.3 | 1.5-2.5 | - | Bal |
Cu-30Ni-Cr | Def Stan 02-886 | 30.5 | 0.75 | 0.75 | 1.8 | Bal |
Cu-Ni alloy | UNS and Def Stan | 0.2% Proof Strength N/mm2 | Tensile Strength N/mm2 | % Elongation | Hardness Hv |
90-10 | C70600 | 100 | 300 | 30 | 90 |
70-30 | C71500 | 120 | 350 | 35 | 100 |
66-30-2-2 | C71640 | 150 | 420 | 30 | 110 |
30Ni-2Cr | Def Stan 02-886 | 350-750 | 550-820 | 20-35 | 175-225 (HB) |
Property | Units | 90-10 | 70-30 |
Density | kg/dm3 | 8.90 | 8.95 |
Melting point | °C | 1100-1145 | 1170-1240 |
Specific heat | J/KGK | 377 | 377 |
Thermal conductivity | W/mK | 50 | 29 |
Linear expansion coefficient 10-300°C | 10-6/K | 17 | 16 |
Electrical resistivity | Micro-ohm/cm | 19 | 34 |
Modulus of elasticity | GPa | 135 | 152 |
Modulus of rigidity | GPa | 50 | 56 |
In addition, the 70-30 alloy is non magnetic, but to obtain a low magnetic signature in the 90-10 alloy, e.g. for use in minesweepers, the alloy requires a fast cool following a final solution heat-treatment.
Alloy | Applications |
90-10 and 70-30 Cu-Ni | Seawater cooling and firewater systems, heat exchangers, condensers and piping, platform riser and leg sheathing, boat hulls, oil coolers, hydraulic tubing, antimicrobial touch surfaces. |
Cu-30Ni-Cr | Forgings, cast seawater pumps and valve components. |
High Strength Cu-Ni | |
Cu-Ni-Al | Shafts and bearing bushes, bolting, pump and valve trim, gears, fasteners. |
Cu-Ni-Sn | Bearings and drill components, subsea connectors, valve actuator stems, lifting nuts, ROV lock-on devices, seawater pump components. |