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waves, and the measurement is performed by determining the time offset of the probing
signal relative to the reference sinusoidal signal.
To determine the distribution of surface layer parameters by thickness based on
probing surface acoustic Rayleigh waves with different frequencies, the inverse problem
is solved, which includes determining the effective penetration depth of the surface
acoustic Rayleigh wave and the algorithm for determining surface layer thickness
parameters which is based on velocity changes of acoustic surface Rayleigh wave with
different frequency.
This method has been tested on two types of control objects - sills and objects with
abrasive blasting, which confirmed the manufacturability and efficiency of its use.
A method for studying the parogon material has been developed and local sections
of the parogon in which the Rayleigh wave velocity decreases have been identified, and
the dependence of this decrease on the wave frequency is also observed. The presence of
degradation processes in these areas was also confirmed by metallographic studies.
A method for optimizing the technology of the metal abrasive blasting by the
frequency dependence of the surface acoustic Rayleigh wave velocity is developed.
Based on the research, it is shown that the main changes in the metal occurred in the
near-surface layer with a thickness of not more than 0,2 mm in the next treatment modes:
compressed air pressure 0,6 MPa, abrasive flow diameter 2 mm, distance from the nozzle
to the treatment surface 10 cm .
Developed technologies for assessing the metal condition were used in a small state
enterprise "Gazothermik" (Lviv) in the form of a method for evaluating the results of
abrasive blasting on the magnitude of the Rayleigh waves.
The proposed technologies, which are based on determining the speed of Rayleigh
waves of different frequencies, were implemented at the enterprise "Techmal" (Lviv).
They were used to determine the changes in the state of the metal surface layers under the
action of shot blasting in order to improve its strength characteristics, as well as to
optimize the technological regime.

Key words: diagnosing materials and structures, non-destructive testing, surface
acoustic Rayleigh waves, the Rayleigh waves propagation velocity, inhomogeneous
distribution of material properties by thickness, Rayleigh wave dispersion.