超音波法による高温構造材料に発生する空孔の非破壊的検出の試み

概要

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The nondestructive detection of cavities by ultrasonic technique was studied for the assessment of long-term degradation damage of high-temperature components. Focussing on the change of the frequency spectrum of the ultrasonic reflection echo due to cavity nucleation, two physical parameters were proposed to detect the cavity: one was the energy attenuation coefficient, a*, and other was the shift of the gravity center in the frequency spectrum of the ultrasonic reflection echo, Δf^^-*. The experimental result by means of the sintered material involving the internal pore of various volume fractions, which was prepared for simulation of cavity nucleation, showed that a* and Δf^^-* were hopeful parameters for the nondestructive detection of cavites. The theoretical equations for a* and Δf^^-* were also derived by applying the Williams theory for the scattering of ultrasonic wave. It was shown that the theoretical values of a* and Δf^^-* comparatively agreed with the experimental results by means of the above sintered material. Based on the results thus obtained, a discussion was made on both the detection limitation of cavities and the preferable method to improve the detection limitation.
一般社団法人日本機械学会の論文
1989-08-25