Sep 18 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesOther DesignationsFabrication and Heat Treatment Annealing Cold Working Hot Working Welding Forging MachinabilityApplications
Introduction
Copper nickel alloys are alloys that have moderate strength and thermal stability in high temperature levels. The high oxidation resistance of these alloys is visible in moist air and steam. Copper nickel alloys have 2 to 30% nickel, high oxidation resistance and stress corrosion cracking resistance.
Copper nickel alloys have good fabricability and high inherent resistance to biofouling. The addition of manganese, niobium, iron and or chromium in these alloys improves their corrosion resistance and strength.
Nickel is soluble in copper and this renders the copper nickel alloys as single phase alpha structures. The cast structures have alpha dendrites that contain huge quantities of nickel. The dendrite structure is broken by mechanical treatments. However, the alloying elements do not become homogenized even by repeated thermal and mechanical treatments.
Copper nickel alloys are of two types that include 90/10 and 70/30. The 90/10 alloys are widely used as they are inexpensive. The 90/10 copper nickel alloys have great resistance to sea water corrosion due to the presence of significant amounts of manganese and iron.
Copper nickel alloys are used in the following applications:
- Hydraulic lines
- Fish cages for aquaculture
- Heat exchangers and condensers
- Desalination units
- Sea water pipework
- Tubes for power plants and ships
- Offshore fire water systems
- Pumps, valves, sheathing and fittings for ship hulls
The following datasheet will provide details about UNS C70600 copper nickel alloys.
Chemical Composition
The chemical composition of UNS C70600 copper nickel alloys is outlined in the following table.
| Element |
Content (%) |
| Cu |
88.7 |
| Fe |
1.3 |
| Ni |
10.0 |
Physical Properties
The following table shows the physical properties of UNS C70600 copper nickel alloys.
| Properties |
Metric |
Imperial |
| Density |
8.94 g/cm3 |
0.323 lb/in3 |
Mechanical Properties
The mechanical properties of UNS C70600 copper nickel alloys are displayed in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength, ultimate |
303-414 MPa |
43900-60000 psi |
| Tensile strength, yield (depending on temper) |
110-393 MPa |
16000-57000 psi |
| Elongation at break (in 254 mm) |
42.00% |
42.00% |
| Machinability (UNS C36000 (free-cutting brass) = 100%) |
20% |
20% |
| Shear modulus |
52.0 GPa |
7540 ksi |
| Poisson's ratio |
0.34 |
0.34 |
| Elastic modulus |
140 GPa |
20300 ksi |
Other Designations
Equivalent materials to UNS C70600 copper nickel alloys are:
| ASME SB111 |
ASTM B111 |
ASTM B466 |
ASME SB171 |
| ASME SB359 |
ASTM B122 |
ASTM B469 |
MIL T-22214 |
| ASME SB395 |
ASTM B151 |
ASTM B543 |
SAE J461 |
| ASME SB466 |
ASTM B171 |
ASTM B608 |
SAE J463 |
| ASME SB467 |
ASTM B359 |
DIN 2.0872 |
MIL T-16420 |
| ASME SB543 |
ASTM B395 |
MIL C-15726 |
MIL T-15005 |
| ASTM B432 |
|
|
Fabrication and Heat Treatment
Annealing
UNS C70600 copper nickel alloys are annealed at temperatures between 593 and 816°C (1100 and 1500°F)
Cold Working
UNS C70600 copper nickel alloys have good cold working capacity.
Hot Working
Copper nickel 90/10 alloys have good hot forming capacity.
Welding
Copper nickel 90/10 alloys can be welded using gas shielded arc welding, spot welding, coated metal arc welding, butt welding, oxyacetylene welding, brazing, soldering and seam welding processes.
Forging
Temperatures between 843 and 954°C (1550 and 1750°F) are suitable for the forging of 90/10 copper nickel alloys.
Machinability
The machinability rating of copper nickel 90/10 alloys is 20%.
Applications
UNS C70600 copper nickel alloys are used in areas where stainless steel cannot be used due to chloride stress-corrosion cracking and in other parts requiring high levels of corrosion resistance. These alloys are also used as machined and forged valve and pump parts that are utilized for seawater services.