Kanthal is a world-leading brand for products and services in the area of industrial heating technology and resistance materials.

Thermocouple iron (Thermocouple wire)

Datasheet updated 2013-03-19 10:36:00 (supersedes all previous editions)

Thermocouple iron is used for the positive leg of thermocouples type J and L. The alloy is also used as the positive leg of compensating cables type KCA (WX).

The alloy is transformed magnetically at 770°C (1420°F) and a crystallographic transformation occurs at 900°C (1650°F). Both transformations affect the thermoelectric properties of the alloy.

Iron can not be exposed to sulphur-containing atmospheres and to temperatures below zero. Thermocouple iron wire is supplied copper-coated to prevent oxidation.

Thermocouple type J and L are frequently used because of their high emf output and their low cost. Compensating cables of type KCA are used together with thermocouples of type K.

Chemical composition

C % Si % Mn % Fe %
Nominal composition 0.03 0.05 0.30 Bal.

Mechanical properties

Wire size Yield strength Tensile strength Elongation Hardness
Ø Rp0.2 Rm A
mm MPa MPa % Hv
2.0 - 450 15 100

Physical properties

Density g/cm3 7.86
Electrical resistivity at 20°C Ω mm2/m 0.13
Temperature coefficient of resistance between 20°C and 100°C x 10-6/K 5000

Coefficient of thermal expansion
Temperature °C Thermal Expansion x 10-6/K
20 - 100 11.7

Thermal conductivity
Temperature °C 100
W m-1 K-1 66.2

Specific heat capacity
Temperature °C 20
kJ kg-1 K-1 0.445

Melting point °C 1535
Magnetic properties The material is magnetic

Recommended maximum continuous operating temperature
Wire size Ø 3.26 1.63 1.00 0.50 0.25
Bare wire °C 760 760 720 650 560
Protected wire °C 760 760 760 760 670

Note that the indicated temperatures should be considered as guide values

Thermoelectric properties

Iron is used as positive leg in thermocouples of type J, L and in compensating type KCA. The emf values vs the negative thermocouple leg are listed in the data sheets for the respective thermocouples.

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Kanthal materials.

Article functions

Related information

Contact us

Print this datasheet

Export to PDF

Download this datasheet as PDF or send by email.
Download as PDF

Contact us