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The chemical composition of alloys CuNi 90/10 and CuNi 70/30 have been optimised in order to maximize the behaviour of the metal under the most stringent conditions of seawater corrosion. Additionally, CuNi 90/10 and CuNi 70/30 meet all requirements of most international standards.
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| Corrosion Behaviour |
| CuNi 90/10 and CuNi 70/30 have an excellent behaviour when exposed to all forms of marine corrosion. This property is mainly due to the fact that the alloy prevents dissolution by forming a very strong protective surface film. |
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| CuNi 90/10 and CuNi 70/30 possible factors of corrosion |
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| Corrosive environment |
Probable Corrosive |
Behaviour in service |
| Clean sea water circulation at a velocity of up to 1 m/s |
Uniform or general |
0,0025 – 0,025 mm/an |
| Clean sea water circulation at a velocity of up to 3,5 m/s* : CuNi 90/10 and 4,5 m/s* : CuNi 70/30 |
Impact corrosion |
Satisfactory |
| Polluted sea water |
General corrosion and accelerated pitting corrosion |
Less resistance |
| Deposits accumulated at the surface |
Local attack |
Generally good |
| Corrosion + stress |
Stress corrosion |
Very resistant |
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| *The local speeds resulting from obstructions can be higher |
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| Physical Properties |
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| Typical values |
Units |
CuNi 90/10 |
CuNi 70/30 |
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Density (20°C)
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Kg /m3
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8900
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8900
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Electrical resistivity (20°C annealed)
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µΩ.cm
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19
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34
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Thermal conductivity ( 20° to 200°C)
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W/m.°K
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50
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30
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Coefficient of expansion ( 20° to 200°C)
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C x 10-6
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17
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16
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Modulus of elasticity ( 20°C annealed)
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MPa
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126 000
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126 000
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Annealing temperature
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°C
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760 - 800
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780 - 820
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Melting interval
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°C
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1100 - 1150
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1180 - 1240
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Magnetic Permeability ( 20° annealed)
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1.08 – 1.80
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<1.05
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| Mechanical Properties |
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Typical values
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Units
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CuNi 90/10
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CuNi 70/30
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Tensile strength (UTS), (Rm)
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MPa
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≥ 310
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≥ 350
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µΩ.cm
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19
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34
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Proof stress (YS 0,2), (Rp 0,2)
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MPa
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≥ 110
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≥ 130
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ksi
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≥ 16
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≥ 19
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Elongation (E 5,65 √S)
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%
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≥ 35
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≥ 30
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Hardness (HB10 D2)
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≥ 70
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≥ 80
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