METHOD FOR ULTRASONIC CHECK-UP OF MEAN GRAIN SIZE OF MATERIALS Russian patent published in 1999 - IPC

FIELD: analyzing internal structure of materials by means of ultrasonic waves. SUBSTANCE: method for proximate check-up of mean grain size of materials dispensing with reference standards involves sequential emission of elastic wave pulses normal to part surface at frequencies f₁ and 3f₁. Amplitudes of signals detected are measured at these frequencies and their relationships are determined. Part is placed in immersing liquid, first and second pulses are detected upon crossing the part, amplitude of first detected pulse is measured at frequency 3f₁ and that of second pulse, at frequency f₁. Mean grain size is found from formula , where v(f₁) is amplitude of signal detected by transducer at frequency 3f₁ that has crossed immersing liquid layer; v₁(f₁) is amplitude of signal detected by transducer at frequency f₁ that has crossed immersing liquid; v₁(3f₁) is amplitude of first signal that has crossed part at frequency 3f₁; v₂(f₁) is amplitude of second signal that has crossed part at frequency f₁; F is function including diffraction attenuation of audio signal in acoustic channel; K_o is wave number in liquid at frequency f₁; a is transducer radius; L is distance between emitter and detector; K₁ is wave number in part material at frequency f₁; H is part thickness; B is factor characterizing sound dissipation in part material. EFFECT: provision for dispensing with reference standards to implement proposed method.