Attenuation of the Ultrasonic Waves in Metals. I : Aluminium

概要

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Attenuation coefficients of longitudinal ultrasonic waves in aluminium were measured by pulsed ultrasonic waves at the frequencies ranging from 2 to 25 megacycles per second. Specimens were annealed several times successively at the temperatures below its melting point to promote the growth of crystal grain from 0.2 to 2 mm. Some corrections on the measured values of attenuation were carried out to eliminate the errors arising from propagation characteristics of the sound waves in the specimens. General feature of the change of attenuation coefficients with respect to frequency and grain sizes were as follows : (1) when the grain diameter was smaller than wave length of sound, the slope of attenuation versus frequency curve increased with grain size ; (2) when grain diameters were greater, the slope became very small ; (3) at the intermediate size of grain gradual variation of the slope appeared between lower and higher range of wave length, From these characters of ultrasonic attenuation in polycrystalline metals, several remarks for ultrasonic flaw inspection in metals and alloys were obtained.
東北大学の論文