Tokutaro Hirone and Kazuo Kamigaki
The ultrasonic attenuation coefficients in stainless steel were measured in the frequency range from 0.5 to 6 Mc/s. The stainless steel used here contained about 19 percent of chromium and 10 percent of nickel and had austenite structure at room temperature. The effect of austenite grain size on ultrasonic attenuation was examined. Specimens of various grain sizes were prepared by applying high temperature heat-treatments. The attenuation coefficient increases steeply with frequency and the main part of this attenuation is explained as Rayleigh scattering of ultrasound by austenite grains. The predominant factor determining the magnitude of this scattering is the degree of elastic anisotropy in austenite grains. The value of this anisotropy obtained here in stainless steel is about a hundredfold larger than that of aluminium.
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