On the basis of the previously developed model for estimating the attenuation coefficient of elastic longitudinal waves in cast iron due to their Rayleigh scattering on graphite inclusions, the influence of such attenuation for cast iron with globular graphite on the characteristics of signals with frequency spectra of different widths depending on the nominal pulse frequencies, cast iron models and the distance traveled by the ultrasonic wave is studied. Computer modeling acoustic channel for environment – cast iron with globular graphite for standard normal probes of two types for studying influence of such environment on characteristics real transmitting and registered signals at the ultrasonic testing. Comparison of results of calculations of spectrums and pulses of registered bottom signals with their experimental values for two samples of cast iron with globular graphite has shown an opportunity of use of the applied settlement model for description of the actual physical phenomena quite adequate for practice. Influence of attenuation of longitudinal waves in cast iron with globular graphite on the directivity characteristic of their radiation is shown on model of cast iron and duration of a pulse. The estimation of the relation of levels of a registered signal and structural noise for various reflectors and characteristics of controllable cast iron has shown performance of recommendations by I. N. Ermolov on reliable detection of a useful signal on a background of noise for thickness, before established experimentally. Features of DGS-diagrams for cast iron with globular graphite, caused by higher, than in steel, attenuation of longitudinal waves and a little smaller speeds of their distribution are marked.
NANOSTRUCTURAL PROCESSES OF MELTING AND MOULDING OF CAST IRON WITH GLOBULAR GRAPHITE
