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 materials under the trademark Kanthal®.
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.
C %
Si %
Mn %
Fe %
Nominal composition
0.03
0.05
0.30
Bal.
Wire size
Yield strength
Tensile strength
Elongation
Hardness
Ø
Rp0.2
Rm
A
mm
MPa
MPa
%
Hv
2.0
-
450
15
100
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
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 materials under the trademark Kanthal®.
