Constantan



Constantan is a copper-nickel alloy usually consisting of 60% Nickel. Its main feature is its resistance which is constant over a wide range of temperatures. Other alloys with similarly low temperature coefficients are known, such as Manganin (Cu86Mn12Ni2).

Constantan alloy

Of all modern strain gauge F); and this characteristic should be taken into account when zero stability of the strain gauge is critical over a period of hours or days.

A-Alloy

Very importantly, constantan can be processed for self-temperature compensation to match a wide range of test material alloy is supplied in self-temperature-compensation (S-T-C) numbers 00, 03, 05, 06, 09, 13, 15, 18, 30, 40 and 50, for use on test materials with corresponding thermal expansion coefficients, expressed in parts per million by length (or µm/m) per kelvin or degree Celsius or degree Fahrenheit.

P alloy

For the measurement of very large strains, 5% (50 000 microstrain) or above, annealed constantan (P alloy) is the grid material normally selected. Constantan in this form is very plastics, respectively.

Physical properties

Electrical resistivity at room temperature0.52 × 10-6 Ω·m
Temperature coefficient at 20 °C 0.00002 K-1
Density 8.9 × 103 kg/m³
Melting point 1221 to 1300 °C
Specific heat capacity 0.39 J/(g·K)
Thermal conductivity at 23°C 19,5 W/(m.K)
Linear coefficient of thermal expansion at 20-100°C 14,9 × 10-6 K-1
Tensile strength 400-490 MPa
Elongation at fracture <45%
Elastic modulus 162 Gpa

Temperature Measurement

Constantan is also used to form thermocouples with wires made of iron, copper, or chromel.

 
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