PSI - Issue 40

M.V. Nadezhkin et al. / Procedia Structural Integrity 40 (2022) 321–324 M.V. Nadezhkin at al. / Structural Integrity Procedia 00 (2022) 000 – 000

324

4

Figure 2a depicts the temperature dependences of the ultrasound attenuation coefficient  ( Т ) (curve 1), corresponding to the destruction point, and the destruction coefficient  ( Т ) (curve 2). It is established that, in deformable samples, the ultrasound attenuation coefficient behaves as a sigmoid function of tensile strength  ( σ B ) (Fig. 2b), while the ultrasound velocity-tensile strength V ( σ B ) plot is linear in the studied temperature range. The stresses corresponding to the maximum growth of the martensitic α' -phase and the decrease in the ultrasound velocity are determined as well. The samples under tension with decreasing temperature exhibited an increase in their yield strength and ultimate strength and a decrease in the ductility. The linear behavior of the correlation dependences can be qualitatively explained by the functional relationship of the tensile strength σ B with the elastic properties of the alloy. Indeed, V = ( G / ρ ) 1/2 , where G is the shear modulus, ρ is the density. Furthermore, the difference of the elastic moduli of the martensite phase released during plastic deformation (Murav'ev V.V. et al., 1996) from those of the material matrix is found to cause the change in the elastic and acoustic characteristics of the entire alloy. Thus, based on the sound propagation velocity and attenuation in the alloys under consideration, it is possible to predict the ultimate strength and maximum performance of the material at low temperatures. It is obvious that as long as the current deformation is below the value characteristic of point D , the entire total strain is mainly determined by its elasto-plastic component, while the damage-associated component is close to zero. Moreover, during the operation of the unit (product) or pressure treatment, the destruction coefficient remained nonzero, indicating the ability of the material to operate in the plastic-damage stage. 4. Summary The analysis of the ultrasound velocity in Fe-Ni-Cr alloys under tension in a wide temperature range of 180 K ≤ T ≤ 318 K revealed that a decrease in temperature exerted a significant effect on the ultrasonic wave propagation speed in the materials. The regression dependences were found between various parameters, enabling one to restore certain characteristics based on experimentally determined ones. Among the obtained pairs of dependences, particular attention was paid to the correlations between mechanical and acoustic parameters as the most interesting for practice. Since the experiments involving the acoustic parameters are less laborious and require no special pre treatment, they can be directly carried out on the structural elements during operation without destroying them. Acknowledgements This work was supported by the Russian Science Foundation (grant no. 21-19-00075). References Barannikova S.A., Bochkareva A.V., Lunev A.G., Shlyakhova G.V., Zuev L.B., 2016. Changes in ultrasound velocity in the plastic deformation of high-chromium steel. Steel in Translation 46, 552-557. Ding X., Wu X., Wang Y., 2014. Bolt axial stress measurement based on a mode-converted ultrasound method using an electromagnetic acoustic transducer. Ultrasonics 54 No. 3, 914 – 920. Kobayashi M., 2010. Analysis of deformation localization based on the proposed theory of ultrasonic wave velocity propagation in plastically deformed solids. International Journal of Plasticity 26, 107-125. Lunev A.G., Nadezhkin M.V., Barannikova S.A., Zuev L.B., 2018. Acoustic Parameters as Criteria of Localized Deformation in Aluminum Alloys. Acta Physica Polonica A 134, 342-345. Marcantonio V., Monarca D., Colantoni A., Cecchini M., 2019. Ultrasonic waves for materials evaluation in fatigue, thermal and corrosion damage. Mechanical systems and signals processing 120, 32-42. Murav'ev V.V., Zuev L.B., Komarov K.L., 1996. Sound Velocity and Structure of Steels and Alloys. Nauka, Novosibirsk, pp. 181. Pelleg J., 2013. Mechanical Properties of Materials. Springer, Dordrecht, pp. 634. Talonen J., Nenonen P., Pape G., Hanninen H., 2005. Effect of strain rate on the strain-induced γ → α′ -martensite transformation and mechanical properties of austenitic stainless steels. Metallurgical and Materials Transactions A 36, 421 – 32. Torello D., Thiele S., Matlack K. H., Kim J.-Y., Qu J., Jacobs L.J., 2015. Diffraction, attenuation, and source corrections for nonlinear Rayleigh wave ultrasonic measurements. Ultrasonics 56, 417-426.