Study of the microstructure of cast-iron by analysis of Rayleigh waves

By means of laser ultrasonics,we have used Rayleigh waves to study four cas t-iron samples with different morphology of graphite precipitation. The fre quency dependence of the wave attenuation and velocity were obtained in the range 0-30 MHz. In this frequency range the ultrasonic attenuation for ail samples was found to be proportional to the square of the frequency while the velocities,although clearly different between different samples were fo und non-dispersive. The mechanism of the attenuation for cast-iron is discu ssed and the link between microstructural sample properties and wave propag ation properties is discussed.