Cupronickel (copper-nickel) is an alloy in which copper is the main element and nickel makes up between about 1% and 49%, since the two metals are fully soluble in each other. The most common grade is 90/10 (90% copper, 10% nickel); raising nickel towards 30%, as in UNS C71640, increases abrasion resistance and seawater flow tolerance.
What are the common cupronickel compositions?
| Grade | Copper | Nickel | Other |
|---|---|---|---|
| 90/10 cupronickel | ~90% | ~10% | - |
| 70/30 cupronickel (e.g. UNS C71640) | ~70% | ~30% | - |
| Coinage alloy | ~75% | 25% | 0.05-0.4% Mn |
| Hiduron® 130 | Balance | 13.0-16.0% | 2.0-3.0% Al, 0.6-1.5% Fe, 0.1-1.0% Mn |
| Hiduron® 191 | Balance | 13.5-16.5% | 3.5-5.5% Mn, 1.0-2.0% Al, 0.7-1.2% Fe |
Langley Alloys cupronickel grades
Hiduron® 130 (DTD 900/4805, 2.1504) and Hiduron® 191 (DEFSTAN 02-835, NES835) both contain about 15% nickel, an optimum level for mechanical and physical properties. Developed for naval use over 50 years ago, they are now used for subsea connectors, valve trim, fasteners and couplings, generally in seawater. See more copper alloys.
What is cupronickel used for?
| Application | Why cupronickel |
|---|---|
| Automotive | 90/10 needs no surface protection; used in brake, hydraulic suspension and cooling systems |
| Marine | 90/10 and 70/30 resist seawater corrosion and biofouling; hull cladding, desalination plants, rig legs, seawater intake screens |
| Coins | copper with 25% nickel and 0.05-0.4% manganese, for coins and medals |
| Resistance wire | low temperature coefficient of resistivity, for high-precision resistors |
| Thermocouples | high, uniform EMF when paired with metals such as copper and iron |
For more background, see what are copper nickels? and why is nickel added to copper?