Thermal diffusivity measurement of stainless-steel alloys through use of the Angstrom’s method

ABSTRACT

The aim of this study is to estimate the thermal diffusivity of metallic materials, in particular AISI 304 and AISI 316 stainless steel. To this end, an experimental setup based on the Angstrom’s method is used, where one face of a considerably large sample is subjected to a periodic heat flux and the other face is kept at a constant temperature. A low cost measurement system was developed to provide the fundamental requirements of the applied method. This consisted of thermophysical properties independent of temperature within the adopted measurement range, complete damping of the heat wave before it reaches the face at a prescribed temperature, one-dimensional heat transfer ensured by exposing the sample side to a vacuum or by thermal insulation. Following this, the feasibility of these scenarios was assessed. In order to conclude the proposed testing, thermocouples are fixed at specific locations on the exterior of the sample, for measuring the amplitude and phase of the thermal wave resulting from periodic heating at a certain frequency. The measurements carried out on a permanent periodic regime are inserted into a mathematical model so that the thermal diffusivity can be determined by linear regression. The results obtained for the two materials under analysis showed good agreement with the literature, with absolute deviations below 5.5 %, proving the effectiveness of the experimental arrangement. Uncertainty quantification, assessed by the Monte Carlo Method, indicates a greater dispersion of the results when using the vacuum. Therefore, thermal diffusivity was estimated with greater precision and reliability, with thermal insulation applied to the side of the sample.

KEYWORDS:

• Angstrom’s Method
• Thermal Wave
• Thermophysical Properties
• Experimental Setup
• Uncertainty Quantification

Acknowledgments

The authors would like to thank the Brazilian financing agencies Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo à Pesquisa de Minas Gerais (FAPEMIG) for supporting the development of this research.

Disclosure statement

On behalf of all authors, the corresponding author states that there is no conflict of interest.

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