Machinery & Energetics

It is shown that in order to study the kinetics of operational damage to materials and structural elements, it is necessary to develop modern means and methods for diagnosing damage that occurs in laboratory samples and structural elements. To determine the deformation state of the surface layer of a structural material (austenitic steel), in this work, we used the method of optical measurement of microplastic deformations, based on the correlation relationship between the radiation energy of a coherent light source reflected by the surface of a metal polycrystal and the amplitude of microplastic deformations of a deformed surface. In accordance with this method, the investigated local area of the surface of the material sample at certain stages of loading is irradiated with coherent light with a wavelength corresponding to the scale of localization of microplastic deformation of the sample surface. Using a fiber optic cable and a focusing lens system, a specklogram of rays reflected from the surface relief is obtained. The parameter in the form of the ratio of the number of light pixels to the total number of pixels in the specklogram image is used as the degree of intensity of the deformation relief change. As a result of the analysis of the statistical parameters of the specklogram, which correlate with the characteristics of the microplastic deformation of the surface of the austenitic steel samples, the characteristic parameters of the scattered damage of the structure of discrete deformations of the surface of the metal polycrystal were determined. On the basis of the obtained experimental data, the work revealed the regularities of the influence of static and cyclic deformation on the shape of the distribution of discrete surface properties. In particular, as a result of the analysis of the statistical characteristics of the correlation diagrams, a linear dependence of the parameters of the distribution of discrete properties of the relief of the deformed surface on the loading factor was obtained.

damage of metal structures, deformation microrelief of the surface, coherent optical scanning, microplastic deformation of the surface