Thermothal® N

Thermocouple wireDatasheet

Datasheet updated 2021-02-04 13:28 (supersedes all previous editions)

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^®.

Thermothal^® N is an austenitic nickel alloy (Ni alloy) used for the negative leg of thermocouples type K. Thermocouples type K have a good resistance to oxidation and better than other combinations of thermocouples.

Thermothal N can not be exposed to atmospheres containing sulphur gases.

Chemical composition

	Ni %	Al %	Mn %	Si %	Co %
Nominal composition	Bal.	1.5	1.5	1.5	0.5

Mechanical properties

Wire size	Yield strength	Tensile strength	Elongation	Hardness
Ø	R_p0.2	R_m	A
mm	MPa	MPa	%	Hv
2.0	250	550	35	120

Mechanical properties at elevated temperature

Temperatur	Yield strength	Tensile strength	Elongation
	R_p0.2	R_m	A₅₀
°C	MPa	MPa	%
100	253	563	42
300	224	551	36
500	203	481	41

Ultimate tensile strength - deformation rate 6.2 x 10^-6 min^-1

Physical properties

Density g/cm³	8.60
Electrical resistivity at 20°C Ω mm²/m	0.292
Temperature coefficient of resistance between 20°C and 100°C x 10^-6/K	1900

Young's modulus
Temperature °C	20	100	300	500
GPa	194	91	61	42

Coefficient of thermal expansion
Temperature °C	Thermal Expansion x 10^-6/K
20 - 100	17

Thermal conductivity
Temperature °C	100
W m^-1 K^-1	29.7

Specific heat capacity
Temperature °C	20
kJ kg^-1 K^-1	0.523

Melting point °C	1400
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	1050	930	900	800	710
Protected wire °C	1150	1080	1050	910	820

Note that the indicated temperatures should be considered as guide values

Thermoelectric properties

Nominal emf values vs Pt 67 - Reference junction 0°C
°C	100	200	300	400	500	600	700	800	900	1000	1100	1200
mV	-1.283	-2.168	-2.886	-3.633	-4.431	-5.287	-6.178	-7.070	-7.940	-8.777	-9.575	-10.330

Nominal emf values vs Thermothal P (ITS 90) - Reference junction 0°C
°C	100	200	300	400	500	600	700	800	900	1000	1100	1200
mV	4.096	8.139	12.209	16.397	20.644	24.906	29.129	33.275	37.326	41.276	45.119	48.838