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A brief overview is presented for means of severe plastic deformation during the formation of gradient structure from the viewpoint of physical mesomechanics. An analysis of the results on the impact of the means of drawing with shear on steel; severe plastic deformation by high pressure torsion on steel, titanium, and copper; and alternating bending by applying a ECAP-Conform stand on copper. It is shown that structures with different degrees of gradient form in the materials as a result of these actions.

Problem Statement (Relevance): The paper describes some features and prospective benefits of deformation by methods of drawing with shear (SD) and high pressure torsion (HPT) in a temperature range of dynamic strain aging (DSA) effect, which allow receiving a high complex of physical and mechanical properties. Objectives: The study aims to investigate and analyze features of the structure formation with the combined application of severe plastic deformation (SPD) and the DSA effect during deformation by drawing with shear and high pressure torsion, to establish patterns of the gradient structure formation. Methods Applied: 1. Computer simulation in Deform 3D software to investigate the stress-strain state on materials with various types of a crystalline lattice: copper grade M1 (FCC), Steel 10 (BCC) and titanium VT1-0 (HCP) and a further comparison with experimental results. 2. Microhardness measurement 3. Scanning and transmission electron microscopy. Originality: This research resulted in investigation of the combined effect of the DSA effect and SPD on the gradient structure formation and mechanical properties of metals with various crystalline lattices. Findings: the paper presents the results of the study of the structure formation during non-monotonous plastic deformation of the alloys (steel 10, copper and titanium) with various crystalline lattice types by SD, as well as ECAP and HPT of low-carbon steel in the temperature range of the DSA effect. Deformation mechanisms and features of the deformation behavior on a mesoscopic scale under various deformation treatment modes are analyzed. The temperature range of the DSA effect in steel 10 under ECAP and the fact of the gradient structure formation under HPT are established. Practical Relevance: The study helped to obtain data that can be used to choose the optimal deformation treatment mode with the DSA effect.

The paper considers the features of the manifestation of dynamic strain aging (DSA) effect during severe plastic deformation processing via equal-channel angular pressing of low-carbon steel 10 and during the deformation processing via rolling of steel 20Kh. The deformation mechanisms under different regimes of deformation processing are analyzed. The temperature ranges for the manifestation of the DSA effect during the deformation by rolling of steel 20Kh and by equal-channel angular pressing of steel 10 are established. It is demonstrated that the deformation of low-carbon steels in the temperature range of DSA leads to further structure refinement and, as a consequence, to the enhancement in strength properties.

The paper analyzes the regularities of structure formation in low-alloyed carbon steels. During the investigation of ferritic-pearlitic steel samples it has been found that the structure formation in pearlite essentially lags behind structural changes in ferrite grains, and this delay is observed at all stages of deformation. An important feature of structure formation in pearlite is crack nucleation in cementite, accompanied by dislocation pile-up in the ferrite interlayers of pearlite. Using the method of dislocation dynamics, the relationship between structural transformations and the parameters of strain hardening is analyzed. It is demonstrated that the proposed method of computer analysis reflects well the processes taking place in a material during plastic deformation. The character of the theoretical curve of strain hardening is determined by the dislocation structure that forms in a material at various stages of deformation.

The paper investigates the effect of the free torsion rate of cylindrical specimes of commercially pure copper (grade M1) on their deformed state, microstructure, and mechanical properties. The study of the microstructure was carried out by means of transmission electron microscopy and X-ray diffraction analysis in the central region and at the periphery of the deformed rod. The mechanical properties were evaluated by measuring the microhardness. It was found that an increase of the torsion rate, other things being equal, promotes more intensive strengthening and refinement of the microstructure.

The paper presents the results of the computer simulation and physical experiment for the free and constrained transverse shear of round specimens of steel 10 with an accumulated strain of e> 1. The stress-strain state was investigated using computer simulation, and the degree of imperfection of the emerging structures was studied by metallographic methods. The laws governing the relationship between the parameters under study and the degree of imperfection of the structure during severe plastic deformation by shear are established.

In this paper, we analyze the microstructural features and mechanical properties of the Grade 4 titanium produced in Russia (VSMPO-AVISMA) and Grade 4 titanium from Carpenter Technology Corporation (USA). It is shown that during the ECAP-Conform processing and subsequent drawing, a homogeneous UFG structure is formed in both Ti materials, providing an enhanced level of mechanical properties with an ultimate tensile strength σB > 1200 MPa and an elongation to failure δ ~ 12%.

The formation of a gradient structure during the severe plastic deformation (SPD) by high-pressure torsion (HPT) of low- and medium-carbon steels under the influence of dynamic strain aging (DSA) is studied. Deformation mechanisms under various regimes of deformation processing are analyzed. The temperature ranges of the DSA effect during the ECAP processing of steel 10 and the fact of the formation of a gradient structure during the HPT processing under these conditions are established. It is shown that the deformation of carbon steels in the DSA temperature range enables controlling the structure of the deformed state.

The techniques of severe deformation of steel samples have been investigated – drawing and shear drawing in eccentric dies implemented at room temperature. The paper considers the features of structural changes occurring in low-carbon steel at different types of deformation treatment – conventional drawing and shear drawing of samples made of steel 10. The structural parameters and the nature of distribution of the plastic deformation intensity were investigated. Higher efficiency of the drawing process with shear was revealed in terms of strain intensity accumulation. A comparative analysis of structural changes and microhardness distribution over the bulk of samples produced by the investigated methods was conducted. The repeatability of the stress-strain state parameters obtained through physical and mathematical modeling was shown. The analysis of the obtained results leads to the conclusion that the use of drawing with shear is advanced for the production of samples and billets with high strength and sufficiently high ductility by creating a gradient structure.

The development of diffusion creep (DC) accompanying superplastic deformation (SPD) of the highly doped nickel alloy ZhS6KP is studied based on an investigation of the redistribution of dispersed intragrain deposits of the γ′ phase of Ni3(Al, Ti). Deposit-free zones (DFZ) are formed in the alloy, held at the temperature of SPD and accompanying deformation at the grain boundaries. The contribution of DC to the deformation was determined from a comparative analysis of the width of the DFZ in the deformed and undeformed parts of the samples for different grain sizes and rates of DC taking into account diffusion accommodation. It was established that for the optimum rate of SPD the upper limit of the contribution of DC to deformation for 2-μm grains does not exceed 11%. It is concluded, based on the distribution of DFZ, that the effect of DC accompanying SPD is determined by diffusion fluxes, associated with the local concentration of stress accompanying the development of grain-boundary slipping.