INVESTIGATION OF THE POSSIBILITIES OF ULTRASONIC TESTING OF CAST IRON WITH LAMELLAR GRAPHITE USING STANDARD NORMAL PROBE

Abstract

Computer simulation of acoustic paths for medium – cast iron with lamellar graphite for standard normal probe of several types was carried out in order to study the effect of such medium on the characteristics of transmitted and received signals during ultrasonic testing. In the course of studies to calculate the attenuation coefficient of longitudinal waves in cast iron with lamellar graphite, due to their Rayleigh and phase scattering by graphite inclusions, the previously developed model was used. Comparison of the results of calculations of spectra and pulses of the recorded signals for two samples of cast iron with lamellar graphite confirmed the possibility of using the developed calculation model for a description of real physical phenomena adequate for the practice of ultrasonic testing. The ratio of the recorded signal and structural noise levels for different models of transducers, reflectors and characteristics of the controlled cast iron is estimated. Shown that increased attenuation of the longitudinal wave in cast iron in comparison with steel as a result of scattering by inclusions leads to higher level of this noise and can greatly reduce the signal-to-noise ratio in the detection of the reflected from the defect signals.