Svetlana Kiseleva

Microtwins and their effect on accumulation of excess dislocation density in grains with different types of crystal lattice bending in deformed austenitic steel

The investigation of excess dislocation density accumulation in the deformed polycrystalline austenitic steel was carried out using transmission electron microscopy (TEM). The distributions of the excess dislocation density in the grains of the deformed austenitic steel with different bending types were obtained and plotted. It was established that in the austenitic polycrystalline steel at the deformation degrees e = 14 and 25 % the distributions of the excess dislocation density are multimodal. In both cases the grain with compound bending is more stressed. The values of the average excess dislocation density in the grains with the compound and simple bending are less at e = 25 % than that at e = 14 %. This is explained by a significant relaxation of the internal stresses in steel with the increase of the deformation degree from 14 % to 25 %. The increase of the number of twinning systems and the material volume fraction covered by twinning leads to the internal stress relaxation and consequently to the...

Internal stresses and stored energy density in the grains at deformation of FCC-polycrystal

The distribution of internal stresses and the density of the accumulated energy in the deformed polycrystal austenitic steel were investigated. The internal stresses and the accumulated energy density were determined using the bend extinction contours observed on the deformed steel micrographs. The laws of internal stresses distributions and the accumulated energy density in the grains with various bending types were determined. At the deformation degrees e = 14 % and e = 25 % the average values of internal stresses and the accumulated energy density inside the individual grains with compound bending were higher than in the grains with simple bending. It testified the fact that the grains with compound bending were more stressed. At the increase of the steel deformation degree up to e = 25 % the growth of contributions from additional modes observed on the internal stress distributions slowed down and at e > 25 % the average internal stress decreased. The relaxation of internal stresses was due to the ori...

Distribution of stored energy density in grains with different types of bends in deformed polycrystals

The results of study of stored energy density disttibution in deformed polycrystal austenitic steel are presented. The density of the stored energy is determined using bend extinction contours observed in electron microscopy images of the deformed steel. Patterns in the distribution of stored energy are established for grains with different types of bends.

Tensor of internal stresses in polycrystalline grains with complex bending

Processes that occur upon the straining of a polycrystal are studied. Components of the internal stress tensor were determined. Changes in the bending and torsion stresses in the crystal lattice of a strained polycrystal are analyzed. A correlation between changes in the internal stress tensor components and the fraction of material with complex bending is established.

Contributions of the lattice bending and torsion stresses to the plastic component of the internal stresses in a deformed austenitic steel

The parameters of bend extinction contours are used to determine the tensor components of internal stresses, namely, the lattice bending and torsion stresses. The laws of their distribution and the contributions of the internal stresses to the plastic component during the deformation of an austenitic steel are found.

Deformation of face-centered cubic polycrystal and stress tensor components in grains

The transmission electron microscopy (TEM) has been used to indicate the contribution of stress tensor components to internal stresses in deformed polycrystalline austenitic steel. TEM images of steel deformation demonstrate bend extinction contours the parameters of which allow detecting the stress tensor components (bending and torsional stresses of a crystal lattice). The diagrams are constructed for the contribution of stress tensor components to internal stresses in grains having different types of bending. The regularities are obtained for the stress distribution due to bending-torsion of a crystal lattice in the deformed face centered cubic crystal system. The experiment shows that the contribution of bending and torsion stress components to the internal stresses is different during the increase of deformation. The torsion stress component always grows with the increase of deformation, while the bending stress component either grows or lowers. The growth in the torsion stress component is typical f...

Evolution of Contributions from Components of Lattice Bending-Torsion to the Elastic Component of Internal Stresses during the Deformation of a Polycrystal

The contributions from the components of lattice bending–torsion to the elastic component of internal stresses are determined and the evolution of these components at various degrees of deformation of 1.1–13Mn–Fe austenitic steel is studied. The components of the internal stress tensor are determined using the parameters of the bending extinction contours observed in electron micrographs of deformed specimens. The results are discussed by comparing them and the defect structure of the deformed steel.

Deformation effect on plastic and elastic stress components in grains with different bending

The paper presents the investigations of deformation processes in polycrystal. Austenitic steel of the type 1.1C–13Mn–Fe is subjected to tensile deformation on a test machine at a rate of 3.4×10−4 s−1 and room temperature. The suggested experimental methodology implies the recovery of internal stresses using the parameters of the bend extinction contours observed on TEM images of the deformed polycrystal structure. The contribution of plastic and elastic stress components is determined in this paper. The analysis of these components is given for grains with different bending in deformed austenitic steel specimens. TEM images are obtained for a single polycrystal grain at different goniometer inclinations. The experimental findings are given for different degrees of steel deformation resulting in its rupture. It is shown that in the vicinity of the material rupture (e = 36%), the plastic component mostly contributes to the internal stresses, while the contribution of elastic component is considerably reduc...

Distribution of excess dislocation density during the deformation of austenitic steel

Electron microscopy studies of the accumulation of excess dislocation density in deformed austenitic steel are performed. The distributions of the excess dislocation density are obtained for different rates of deformation. The results are compared the observed defect structure of the steel.