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Introduction to CuNi 90/10 and CuNi 70/30

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.

 
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.
 
CuNi 90/10 and CuNi 70/30 possible factors of corrosion
 
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
 
*The local speeds resulting from obstructions can be higher
 
Physical Properties
 
Typical values Units CuNi 90/10 CuNi 70/30

Density (20°C)

Kg /m3

8900

8900

Electrical resistivity (20°C annealed)

µΩ.cm

19

34

Thermal conductivity ( 20° to 200°C)

W/m.°K

50

30

Coefficient of expansion   ( 20° to 200°C)

C x 10-6

17

16

Modulus of elasticity ( 20°C annealed)

MPa

126 000

126 000

Annealing temperature

°C

760 - 800

780 - 820

Melting interval

°C

1100 - 1150

1180 - 1240

Magnetic Permeability ( 20° annealed)

 

1.08 – 1.80

<1.05

 
Mechanical Properties
 

Typical values

Units

CuNi 90/10

CuNi 70/30

Tensile strength (UTS), (Rm)

MPa

≥ 310

≥ 350

 

µΩ.cm

19

34

Proof stress (YS 0,2), (Rp 0,2)

MPa

≥ 110

≥ 130

 

ksi

≥ 16

≥ 19

Elongation (E 5,65 √S)

%

≥ 35

≥ 30

Hardness (HB10 D2)

 

≥ 70

≥ 80

 
 
 
 
 
 
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