Thermal conductivity and electrical resistance of 38KHN3MA steel near phase transformations

This paper presents experimental data on measuring the thermal diffusivity a(T) and electrical resistivity (T) of 38KhN3MA structural steel in the temperature range 600-1600 K. It is shown that in the heating-cooling mode, the dependences a(T) and (Т) have a significant temperature hysteresis associated with the martensite-austenite structural transformation. The temperatures of the magnetic (Curie temperature) and martensitic transformations during thermal cycling at a rate of up to 10 K/min have been established. Approximating equations for determining a(T) and (T) are obtained. The temperature dependence of the thermal conductivity coefficient of this alloy at high temperatures has been estimated. Based on the results of electrical resistivity measurements using the Wiedemann-Franz-Lorentz law, the electronic contribution of energy transfer to the overall process of heat conduction is determined. It is also shown that the analysis of the tem-perature dependence of the thermal conductivity a(Т) is best suited for determining the temperatures of the beginning and end of magnetic and structural phase transitions in steel grade 38KhN3MA.