Pulse Method for the Measurement of Thermal Diffusivity of Metals

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Abstract
A pulse method for measuring thermal diffusivitity of metals has been developed. The temperature in an effectively infinite rod is zero everywhere up to the time t=0, when a very short heat pulse is introduced in the plane x=0. The subsequent temperature histories of several points at different distances from x=0 are recorded, and from these data the thermal diffusivity may be calculated. Since an experimental run lasts less than one minute, the requirements on the stability of the ambient temperature are not as stringent as in previously reported methods. The present method saves time without sacrificing accuracy, a maximum error of ±4% being estimated. Although this work was all done at room temperature, the specimens were mounted in a vacuum furnace which should permit measurements at elevated temperatures. The method was tested on commercial ``A'' nickel, giving a result in excellent agreement with previous values. Results are reported for four new steels developed by the Bethlehem Steel Company.