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Severe plastic deformation is one of promising techniques for omproving metal properties. In this work a new SPD technique – Multi-ECAP-Conform – is studied. The technique ensures an accumulation of a true strain degree to е>2.5 during one processing cycle. Models for force characteristics calculation have been developed on the basis of theoretical procedures of metal forming. The derived equations determine force parameters of the Multi-ECAP-Conform process.

This article presents the results of a computer modeling study of a new technique of severe plastic deformation called Multi-ECAP-Conform, ensuring a high level of strain value e i ! 3 per one processing pass of a billet from an Al alloy. The main feature of this technique is multi-stage successive shear straining of a long-length billet under the conditions of equal-channel angular pressing (ECAP) via the Conform mode. The main area of investigation is the study of the effect of the geometry of channels and channels intersection angles on the homogeneity of the strained state, all other conditions being equal. A rational combination of the channels geometry has been established that provides for a homogeneous strained state of billets and allowable force conditions of processing.

This work presented the results of solution of the strain intensity evolution in a commercially pure copper billet in the process of severe plastic deformation (SPD) by equal channel angular pressing (ECAP) technique. At the stage of the modeling task preparation, the most significant factors affecting the strain intensity at ECAP are suggested to be the friction coefficient, as well as the deformation velocity. A computer virtual full factorial experiment (FFE) was conducted accompanied with the application program package "DEFORM-3D" by using two-level model with two unknown varied parameters, followed by the formalization of the results in the form of the regression equation, as well as the optimization of the selected factors. The deformation velocity which coincides with the punch displacement velocity and the friction factor were chosen as independent variables in the ECAP process of characterizing the processing and its effectiveness, which are in terms of strain intensity; whereas the strain intensity of the material was selected as a response variable (dependent variable). Based on the results of the friction coefficient (f.) determination and the strain intensity estimated value of 1.155, a friction coefficient priori was determined to be 0.10. Therefore, the deformation velocity (V) of 1.5 mm/s was obtained by solving the regression equation.

The quantitative concentration of alloying elements in low-alloyed copper alloys is an important factor in forming electrical and mechanical characteristics. It is known that severe plastic deformation is accompanied by both a substantial refinement of the structure and changes in the kinetics of phase transformations during the deformation and the post-deformation thermal treatment. This paper presents the results of a comparative analysis of the Cu–0.2Cr and Cu–1.1Cr alloys subjected to equal-channel angular pressing at room temperature. The analysis was performed for the grain structure, solid solution, and second-phase particles using transmission electron microscopy, scanning electron microscopy, X-ray crystal analysis, and the small-angle diffraction method. It was found that the level of structure refinement and mechanical characteristics after equal-channel angular pressing was almost the same for both studied alloys. Post-deformation aging of the Cu–0.2Cr alloy leads to the development of polygonization and re-crystallization within it. The aging of the Cu–1.1Cr alloy shows a better thermal stability than that of the Cu–0.2Cr alloy. In the Cu–1.1Cr alloy, after aging, in comparison with Cu–0.2Cr, a denser-packed ensemble of fine particles with an average size of 54 ± 2 nm is formed. In this case, the average size of fragments is 270 ± 15 nm and the ultimate tensile strength reaches 485 MPa.