ON THE INFLUENCE OF THE PARAMETERS OF GLOBULAR GRAPHITE INCLUSIONS ON THE ACOUSTIC CHARACTERISTICS OF CAST IRON AND ULTRASONIC LONGITUDINAL WAVE SIGNALS

Abstract

Based on analytical models, the dependence of the velocity and attenuation coefficient of the longitudinal ultrasonic wave in cast iron with globular graphite on the average size of graphite elements and its volume content is shown. Computer modeling of acoustic paths for a medium – cast iron with globular graphite for standard normal probes was carried out to assess the influence of such a medium on the characteristics of the transmitted and recorded signals during ultrasonic testing. Calculations of directivity characteristic of probes with normalization of each directivity characteristic to its maximum for steel and cast iron with globular graphite, a slight change in the width of the directivity characteristics due to the lower velocity of longitudinal waves in cast iron compared to steel. It is established that the amplitude of the bottom signal in cast iron with globular graphite can exceed its values for structural steel. Evaluation of the nonlinearity of attenuation for cast iron with globular graphite showed that it is very small. The features of DGS-diagrams for cast iron with globular graphite are noted, associated with higher attenuation of longitudinal waves than in steel, as well as with lower velocities of their propagation.