ANALYSIS OF STRUCTURAL-PHASE STATE AND INTERNAL STRESS FIELDS AT A DISTANCE FROM THE ZONE OF DEFORMATION LOCALIZATION FOR SPECIMENS MADE OF HEAT-RESISTANT STEEL

The analysis of differences in the structural-phase state and internal stress fields in the deformation localization zones and at a distance of 1 mm from it for samples made of heat-resistant steel grade 12X1MF is performed. The microstructure of the samples was studied by transmission electron microscopy on thin foils. It is shown that the metal structure of all the studied sections of the samples after deformation before the formation of zones of stable localization of deformations consists of ferrite and perlite. Ferrite, which occupies the main part of the volume of the material, is present both non-fragmented and fragmented. Differences in the structural and phase state in the metal of 12X1MF steel samples in the zones of stable localization of deformation and at a distance from it were revealed. The established differences are both in the different percentage of morphological components of the microstructure (ferrite and perlite), including the content of fragmented and non-fragmented dislocation substructure, and in quantitative indicators (scalar and excessive dislocation density, curvature-torsion of the crystal lattice, amplitudes of the fields of internal shear and long-range stresses). It was found that after a short-term test until stable localization of deformation is achieved, not the entire metal volume of the sample has the same microstructure. The established differences in the structural-phase state and internal stress fields in the deformation localization zones and at a distance of 1 mm from it for samples made of heat-resistant steel grade 12X1MF indicate that it is in the deformation localization zones that the occurrence of microcracks is most likely.

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