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According to the data of the automated analysis of images of the surfaces with thermal-fatigue cracks, we study the specific features of the deformation and fracture processes in 25Kh1М1F heat-resistant steel. We reveal and quantitatively describe the regularities and characteristic stages of its deformation with transformations of the block structure of cracking on the surface as a result of merging of separate thermal-fatigue cracks into a network, which is determined by the ability of the metal to be deformed within the framework of islets of the intact material surrounded with cracks. We also estimate the measure of interaction of each crack with the set of cracks by the intensity of shear and rotation processes inside the blocks of the material that are not damaged by thermal-fatigue cracks and by the changes in their orientation relative to the direction of the applied load.

We develop a method for the digital-optical analysis of defects in materials with simultaneous measuring of several diagnostic parameters and estimation of the degree of damage to the material in the vicinity of a stress concentrator by analyzing the displacements and distortions of the preliminarily made surface marks. By using the results of mathematical description of the field of displacements on the metal surface, we propose to use informative signs for the quantitative analysis of the parameters of damage.