Constantan - An Overview

Constantan is an alloy consisting of copper (55%) and Nickel (45%).  It has a very low temperature coefficient of resistance which makes it ideal for use in instruments and bridges.  Constantan also has good mechanical properties such as good fatigue and elongation properties.

Constantan has better corrosion resistance than manganin.

Constantan is also used as the negative element in J and T type thermocouples.  Constantan has high resistivity.  This makes it ideal for use in resistance grids.  

Constantan is also used in the construction of industrial rheostats and wire wound precision resistors


Density                                                              - 0.321 lbs/

Melting Point (Approx.)                                     - 1210° C

Electrical Resistivity @ R.T.                               - 50.8 Microhm· cm

Temperature Coefficient of Resistivity (TCR)       - ± 30 PPM/° c
(25°C to 105°C)

Thermal Expansion Coefficient (20°C to 100°C)  - 14.9 x 10-6/°C

Thermal EMF vs. Copper (0°C to 100°C)           - -0.043 Millivolts/°C

Thermal Conductivity R.T.                                   - 21.2W/m· K

Magnetic Attraction                                             - None

Specific Heat                                                       - .094 gram· cal./°C

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