The paper is devoted to the analysis of such an important factor as deformation behavior in the simple shear conditions.It is shown that non-monotonous character of material plastic flow exerts significant influence on the intensity of initial structure refinement. Induced non-monotonous character that ensures formation of equiaxed structural states plays an important role in the process

A. G. Raab

G. I. Raab

V. G. Shibakov

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423 METALURGIJA 54 (2015) 2, 423-425G. I. RAAB, A. G. RAAB, V. G. SHIBAKOVANALYSIS OF SHEAR DEFORMATION SCHEME EFFICIENCY IN PLASTIC STRUCTURE FORMATION PROCESSESReceived – Primljeno: 2014-04-04Accepted – Prihvaćeno: 2014-09-30Review Paper – Pregledni radISSN 0543-5846METABK 54(2) 423-425 (2015)UDC – UDK 539.374:551.234:621.97=111G. I. Raab, A. G. Raab, Ufa State Aviation Technical University, Ufa, RussiaV. G. Shibakov, Kazan Federal University, Kazan, RussiaThe paper is devoted to the analysis of such an important factor as deformation behavior in the simple shear condi-tions. It is shown that non-monotonous character of material plastic flow exerts significant influence on the inten-sity of initial structure refinement. Induced non-monotonous character that ensures formation of equiaxed struc-tural states plays an important role in the process. Key words: plastic deformation, simple shear, equal-channel angular pressing (ECAP), non-monotony, severe and large plastic deformations.Severe plastic deformation (SPD) techniques have been recently widely used to fabricate nanostructured and ultrafine-grained states in a wide range of metal materials [1-3]. Development of SPD techniques was inspired by theoretical works of Prof. V.M. Segal and his colleagues (Minsk) on analysis of mechanics of shear deformation schemes. In these works simple shear features were thoroughly studied. The simple shear is the most promising technique from the authors’point of view. Its features are [4]:  – stability of the section perpendicular to the flow plane during straining. This makes possible process-ing of billets with large cross sections;  – orientation of spatial development of deformation is determined by one system of slip lines, which is im-portant for control over texture formation processes;   – possibility of multiple cyclic deformation of one bil-let and achievement of as high levels of accumulated strain as desired.For simple shear implementation, V.M. Segal devel-oped a processing technique in intersecting channels fur-ther referred to as equal channel angular pressing (ECAP). First experimental works on ECAP application were aimed at strengthening of materials. At the begin-ning of 90 s of the past century use of the scheme moved to the sphere of creating new structural states in metals, namely in ultrafine-grained and nanostructured grain size ranges. Research teams under the direction of Prof. R.Z. Valiev, Ufa State Aviation Technical University, and Prof. S.V. Dobatkin, MISIS, IMET RAS have been succes-sively developing this technique in Russia. The technique has been also widely used in a number of leading physi-cal metallurgy centers all over the world [2].It should be noted that simplicity of a laboratory die-set and high efficiency in forming new structural states in studied materials contributed to such development.  Another two advantages of the ECAP technique worth paying attention to are considered below. They are high localization of deformation and non-monotonic cha-racter of deformation through the simple shear scheme.Theoretical analysis of deformation processes in polycrystalline metals shows that strain rate discontinu-ity lines appear in the deformation zone, in which the strained state changes stepwise [5, 6]. Only the tangen-tial rate undergoes the discontinuity. It has been stated that “straight strain rate discontinuity lines are of spe-cial interest for settling the problems of plastic structure formation, as homogeneous stress and strained states are formed along these lines” [7] (Figure 1). The inten-sity of shear strain in the infinitely thin layer δ tending to 0 is determined from the ratio Г = |Vτ| / |Vn|, the in-tensity of shear strain rates Н and shear strain rate tend to the maximum values close to ∞ (Figure 1).Figure 1   Simple shear in the strain rate discontinuity line, where δ – the band width, V1 and  V11 – the rates of billet parts I and II on the rate discontinuity lines424   METALURGIJA 54 (2015) 2, 423-425G. I. RAAB et al.: ANALYSIS OF SHEAR DEFORMATION SCHEME EFFICIENCY IN PLASTIC STRUCTURE FORMATION...One may assume that enhancement of the density of rate discontinuity lines in the conditions of large localiza-tion and strain degrees during ECAP contributes to much higher intensity of structure refinement, as it is known that large single strains actively fragment the initial struc-ture [8] and as a rule are extremely non-monotonous. Thus, during multi-cycle ECAP processing of billets, with different single strains per 1 processing cycle and an equal total accumulated strain of еۥΣ ~ 4,4, the highest ef-ficiency of structure refinement, formation of equi-axed grains and enhanced fraction of high-angle boundaries is achieved for the maximum value of a single strain per a processing cycle. The angle of channels intersection is 90 ° (true strain е = 1,1). The processing regime is with billet rotation about its longitudinal axis by 90 ° before each processing cycle (route В) [9].One should also pay attention to the non-monotonic character of simple shear strain [10] (Figure 2), which ensures continuous change of main strain components directions in the deformation zone. This contributes to appearance of new directions of rate discontinuity lines and their intersections, and therefore higher intensity of initial structure refinement.In case of monotonous deformation this graph should coincide with a direct line (φ13 - φ11 = π/2).Another important factor for enhancing efficiency of refinement during ECAP is change of direction of slip lines by 90 or 180 degrees via rotation of a billet about its longitudinal axis in the multicycle processing condi-tions. This effect should be qualified as induced non-monotony. Such effectiveness is confirmed by forma-tion of a homogeneous structural state in Al after 4 ECAP cycles (Figure 3).The structure with equiaxed UFG grains is formed. It is characterized by enhanced fraction of high-angle boundaries testifying to forma-tion of a grain-type structure for the minimally possible number of processing cycles. Analysis of finer processes of structure formation occurring on the dislocation level in the conditions of monotonous and non-monotonous deformation is also of special interest.  Figure 2   Graph of angle change (φ13 -φ11) between figure axis and main strain axis with increase of the relative shear value δ. Non-monotonous deformationφ13 – φ11 / ° φ13 – φ11 = /2 959085800  0,2 0,4 0,6 0,8  1 Figure 3   Microstructure and diffraction patterns of pure Al after 4 ECAP passes without billet rotation about the longitudinal axis (a) and with rotation by 90 ° before each pressing cycle (b). Electron microscopy [11]a)b)2 m2 mIt is known [3] that absorption of lattice dislocations by boundaries leads to significant misorientation angle increase in case the following ratio is fulfilled  J ent bS  Jleav bS,where the product of the Burgers vector and the dis-locations flow entering a boundary is given to the left of the non-equality sign, the similar product for disloca-tions leaving a boundary is given to the right of the non-equality sign. The flow directions of dislocations and their parts remaining in boundaries depend on the direc-tion of external stress. Contribution to the fixed increase of the misorienta-tion angle  is made only by sessile components of grain-boundary dislocations (GBD) with the Burgers vectors normal to the boundary plane. As the modules of entering 425 METALURGIJA 54 (2015) 2, 423-425G. I. RAAB et al.: ANALYSIS OF SHEAR DEFORMATION SCHEME EFFICIENCY IN PLASTIC STRUCTURE FORMATION...and leaving dislocations should correspond to the con-stant lattice, ⏐bS⏐ = ⏐bS′⏐ and the Burgers vector mod-ule of the GBD sessile component is equal to:  ⏐bn⏐=⏐b⏐sin   =2⏐bS⏐sin2     (1)Permeability of low-angle boundaries for lattice dis-locations is high. With the constant shear direction, only a small part of dislocation flow JB can pin on such boundaries, as the kinetic energy of dislocations (f v cos()), necessary for overcoming barriers, is low due to a small value of the Schmid factor   angle cosine between the force vectors  f, acting on a dislocation and its velocity  v:  JB = J – JP (2)where J  the number of mobile dislocations; JP – flow of dislocations that moved to the external surface.The misorientation angle between low-angle bound-aries is θм = b/h, where h  the distance between dislo-cations in a wall. Therefore, the angle increment Δθм is proportional to ⏐bn⎢ and JB:   (3)In case when the external stress acting on a sample is constant in its direction, which is typical of quasimonoto-nous deformation, for example drawing, and the external surface area increases significantly, there occurs a condi-tion upon which Jв→0 and Jв  JP. In this case the incre-ment Δθм is very small, as it is determined by the product of small values: the flow of dislocations Jв entering a boundary and settling in it is small, the low-angle bound-ary angle sine square is small either.  The experimental data show that during quasimonotonous deformation the increment of angle misorientations is observed mainly near band boundaries and practically does not take place in cells, blocks and subgrains located in bands. The boundaries of these misorientation areas remain low-an-gle [12]. One may search for the analogy of rate disconti-nuity lines formation and formation of band boundaries occurring in a gradient field of material flow rates. As a result, band boundaries do not practically intersect in a low-gradient field of rates (during quasimonotonous drawing, for example), which results in formation of a grain-subgrain type structure. Another situation arises during non-monotonous de-formation, when the direction of external  force impact on the material changes constantly providing enhanced gradient of rates in the local areas of deformed billets and high intensity of formation and intersection of high-angle band boundaries (rate discontinuity lines). Such pattern is typical of ECAP being non-monotonous pro-cess, when the external surface of a sample does not change and dislocation flows close inside billets on the internal surfaces of the deformation zone. Nonmonoto-nous large deformation results in constant formation of new shear bands and therefore high-angle band bound-aries. High-angle boundaries with a high value of the angle  θ, as significant barriers for dislocations flow, contribute to more intensive increment of the angle Δθм (see Formula 1). It is evident that such conditions en-sure intensive formation of a grain-type structure.CONCLUSION 1.  Thus, the performed analysis shows that during de-velopment of effective SPD processes one should adhere to the procedure that accounts the following conditions:    – provision of a maximum high level of single ac-cumulated strain per a processing cycle;  – use of simple shear scheme;  – provision of induced non-monotony.2.  Localization of deformation zone against non-mo-notony also enhances the effects of grain refinement and ensures formation of equi-axed structures due to high density of differently directed rate discontinui-ty lines, formation and intersection of band high-angle boundaries.AcknowledgementG. I. Raab would like to acknowledge the support of Russian Foundation for Basic Research (project № 14-19-01062). The research was conducted at FSBFEI HPE «Ufa State Aviation Technical University».A.G. Raab would like to acknowledge the support of the Russian Ministry of Education and Science within the state task № 11.729.2014K. The research was con-ducted at FSBFEI HPE «Ufa State Aviation Technical University».REFERENCES[1]  Valiev R.Z., Alexandrov I.V., nanostructured materials pro-duced by severe plastic deformation. M: Logos, (2000). 272 p.[2]  R.Z. Valiev and T.G. Langdon, Principles of equal-channel angular pressing as a processing tool for grain refinement, Prog. Mater. Sci. 51 (2006), 881-981.[3]  Utyashev F.Z., Raab G.I., Deformation techniques for pro-ducing and processing ultrafine-grained and nanostructured materials. – Ufa: Ghilem, NIK Bashk. Encycl. 2013. 376 p.[4]  Segal V.M., Reznikov V.I., Drobyshevskiy A.S., Kopylov V.I. Plastic treatment of metals by simple shear // Metalur-gija 1981) 1, 115-123.[5]  Hill R. Mathematical theory of plasticity /translated from English. M., 1956. [6]  Tamlenov A.D. Theory of plastic deformation of metals. M., 1972.[7]  Processes of plastic structure formation in metals. V.M. Segal, V.I. Reznikov, V.I. Kopylov, et al. Minsk: Nauka i Tekhnika, 1994,-232 p. 38.[8] V.V.  Rybin. Large plastic deformations and metal failure. Metallurgia, M.1986. 224 p.[9]  Nakashima K., Horita Z., Nemoto M., Langdon T.G.. Acta. Mater., 1998. V. 46. P. 1589.[10]  G.E. Arkulis, V.G. Dorogobit, Theory of plasticity, M., “Metallurgia” 1987.[11]  Ywahashi Y., Horita Z., Nemoto M., Langdon T.G. An in-vestigations of microstructural evolution during equal-chan-nel angular pressing // Acta Mater.(1997) 45, 4733-4742.[12]  Hughes D.A., Hansen N. Microstructure and Strength of Nickel at Large Strains // Acta Mater. (2000) 48, 2985-3004.Note:   The responsible for English language is lecturer from Kazan Federal University, Kazan, Russia

Analysis of shear deformation scheme efficiency in plastic structure formation processes

© 2014 Faculty of Metallurgy. All rights reserved. The paper is devoted to the analysis of such an important factor as deformation behavior in the simple shear conditions. It is shown that non-monotonous character of material plastic flow exerts significant influence on the intensity of initial structure refinement. Induced non-monotonous character that ensures formation of equiaxed structural states plays an important role in the process

Raab G.

Raab A.

Shibakov V.

Kazan Federal University Digital Repository

Metalurgija 2015 vol.54 N2, pages 423-425Analysis of shear deformation scheme efficiency inplastic structure formation processesRaab G., Raab A., Shibakov V.Kazan Federal University, 420008, Kremlevskaya 18, Kazan, RussiaAbstract© 2014 Faculty of Metallurgy. All rights reserved. The paper is devoted to the analysis of suchan important factor as deformation behavior in the simple shear conditions. It is shown that non-monotonous character of material plastic flow exerts significant influence on the intensity ofinitial  structure  refinement.  Induced  non-monotonous  character  that  ensures  formation  ofequiaxed structural states plays an important role in the process.KeywordsEqual-channel angular pressing (ECAP), Non-monotony, Plastic deformation, Severe and largeplastic deformations, Simple shear

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423METALURGIJA 54 (2015) 2, 423-425G. I. RAAB, A. G. RAAB, V. G. SHIBAKOVANALYSIS OF SHEAR DEFORMATION SCHEME EFFICIENCY IN PLASTIC STRUCTURE FORMATION PROCESSESReceived – Primljeno: 2014-04-04Accepted – Prihvaćeno: 2014-09-30Review Paper – Pregledni radISSN 0543-5846METABK 54(2) 423-425 (2015)UDC – UDK 539.374:551.234:621.97=111G. I. Raab, A. G. Raab, Ufa State Aviation Technical University, Ufa, RussiaV. G. Shibakov, Kazan Federal University, Kazan, RussiaThe paper is devoted to the analysis of such an important factor as deformation behavior in the simple shear condi-tions. It is shown that non-monotonous character of material plastic flow exerts significant influence on the inten-sity of initial structure refinement. Induced non-monotonous character that ensures formation of equiaxed struc-tural states plays an important role in the process. Key words: plastic deformation, simple shear, equal-channel angular pressing (ECAP), non-monotony, severe and large plastic deformations.Severe plastic deformation (SPD) techniques have been recently widely used to fabricate nanostructured and ultrafine-grained states in a wide range of metal materials [1-3]. Development of SPD techniques was inspired by theoretical works of Prof. V.M. Segal and his colleagues (Minsk) on analysis of mechanics of shear deformation schemes. In these works simple shear features were thoroughly studied. The simple shear is the most promising technique from the authors’point of view. Its features are [4]: – stability of the section perpendicular to the flow plane during straining. This makes possible process-ing of billets with large cross sections; – orientation of spatial development of deformation is determined by one system of slip lines, which is im-portant for control over texture formation processes;  – possibility of multiple cyclic deformation of one bil-let and achievement of as high levels of accumulated strain as desired.For simple shear implementation, V.M. Segal devel-oped a processing technique in intersecting channels fur-ther referred to as equal channel angular pressing (ECAP). First experimental works on ECAP application were aimed at strengthening of materials. At the begin-ning of 90 s of the past century use of the scheme moved to the sphere of creating new structural states in metals, namely in ultrafine-grained and nanostructured grain size ranges. Research teams under the direction of Prof. R.Z. Valiev, Ufa State Aviation Technical University, and Prof. S.V. Dobatkin, MISIS, IMET RAS have been succes-sively developing this technique in Russia. The technique has been also widely used in a number of leading physi-cal metallurgy centers all over the world [2].It should be noted that simplicity of a laboratory die-set and high efficiency in forming new structural states in studied materials contributed to such development.  Another two advantages of the ECAP technique worth paying attention to are considered below. They are high localization of deformation and non-monotonic cha-racter of deformation through the simple shear scheme.Theoretical analysis of deformation processes in polycrystalline metals shows that strain rate discontinu-ity lines appear in the deformation zone, in which the strained state changes stepwise [5, 6]. Only the tangen-tial rate undergoes the discontinuity. It has been stated that “straight strain rate discontinuity lines are of spe-cial interest for settling the problems of plastic structure formation, as homogeneous stress and strained states are formed along these lines” [7] (Figure 1). The inten-sity of shear strain in the infinitely thin layer δ tending to 0 is determined from the ratio Г = |Vτ| / |Vn|, the in-tensity of shear strain rates Н and shear strain rate tend to the maximum values close to ∞ (Figure 1).Figure 1  Simple shear in the strain rate discontinuity line, where δ – the band width, V1 and  V11 – the rates of billet parts I and II on the rate discontinuity lines424  METALURGIJA 54 (2015) 2, 423-425G. I. RAAB et al.: ANALYSIS OF SHEAR DEFORMATION SCHEME EFFICIENCY IN PLASTIC STRUCTURE FORMATION...One may assume that enhancement of the density of rate discontinuity lines in the conditions of large localiza-tion and strain degrees during ECAP contributes to much higher intensity of structure refinement, as it is known that large single strains actively fragment the initial struc-ture [8] and as a rule are extremely non-monotonous. Thus, during multi-cycle ECAP processing of billets, with different single strains per 1 processing cycle and an equal total accumulated strain of еۥΣ ~ 4,4, the highest ef-ficiency of structure refinement, formation of equi-axed grains and enhanced fraction of high-angle boundaries is achieved for the maximum value of a single strain per a processing cycle. The angle of channels intersection is 90 ° (true strain е = 1,1). The processing regime is with billet rotation about its longitudinal axis by 90 ° before each processing cycle (route В) [9].One should also pay attention to the non-monotonic character of simple shear strain [10] (Figure 2), which ensures continuous change of main strain components directions in the deformation zone. This contributes to appearance of new directions of rate discontinuity lines and their intersections, and therefore higher intensity of initial structure refinement.In case of monotonous deformation this graph should coincide with a direct line (φ13 - φ11 = π/2).Another important factor for enhancing efficiency of refinement during ECAP is change of direction of slip lines by 90 or 180 degrees via rotation of a billet about its longitudinal axis in the multicycle processing condi-tions. This effect should be qualified as induced non-monotony. Such effectiveness is confirmed by forma-tion of a homogeneous structural state in Al after 4 ECAP cycles (Figure 3).The structure with equiaxed UFG grains is formed. It is characterized by enhanced fraction of high-angle boundaries testifying to forma-tion of a grain-type structure for the minimally possible number of processing cycles. Analysis of finer processes of structure formation occurring on the dislocation level in the conditions of monotonous and non-monotonous deformation is also of special interest.  Figure 2  Graph of angle change (φ13 -φ11) between figure axis and main strain axis with increase of the relative shear value δ. Non-monotonous deformationφ13 – φ11 / ° φ13 – φ11 = /2 959085800 0,2 0,4 0,6 0,8 1 Figure 3  Microstructure and diffraction patterns of pure Al after 4 ECAP passes without billet rotation about the longitudinal axis (a) and with rotation by 90 ° before each pressing cycle (b). Electron microscopy [11]a)b)2 m2 mIt is known [3] that absorption of lattice dislocations by boundaries leads to significant misorientation angle increase in case the following ratio is fulfilled  Jent bS  Jleav bS,where the product of the Burgers vector and the dis-locations flow entering a boundary is given to the left of the non-equality sign, the similar product for disloca-tions leaving a boundary is given to the right of the non-equality sign. The flow directions of dislocations and their parts remaining in boundaries depend on the direc-tion of external stress. Contribution to the fixed increase of the misorienta-tion angle  is made only by sessile components of grain-boundary dislocations (GBD) with the Burgers vectors normal to the boundary plane. As the modules of entering 425METALURGIJA 54 (2015) 2, 423-425G. I. RAAB et al.: ANALYSIS OF SHEAR DEFORMATION SCHEME EFFICIENCY IN PLASTIC STRUCTURE FORMATION...and leaving dislocations should correspond to the con-stant lattice, ⏐bS⏐ = ⏐bS′⏐ and the Burgers vector mod-ule of the GBD sessile component is equal to:  ⏐bn⏐=⏐b⏐sin  =2⏐bS⏐sin2   (1)Permeability of low-angle boundaries for lattice dis-locations is high. With the constant shear direction, only a small part of dislocation flow JB can pin on such boundaries, as the kinetic energy of dislocations (f v cos()), necessary for overcoming barriers, is low due to a small value of the Schmid factor   angle cosine between the force vectors  f, acting on a dislocation and its velocity  v: JB = J – JP (2)where J  the number of mobile dislocations; JP – flow of dislocations that moved to the external surface.The misorientation angle between low-angle bound-aries is θм = b/h, where h  the distance between dislo-cations in a wall. Therefore, the angle increment Δθм is proportional to ⏐bn⎢ and JB:  (3)In case when the external stress acting on a sample is constant in its direction, which is typical of quasimonoto-nous deformation, for example drawing, and the external surface area increases significantly, there occurs a condi-tion upon which Jв→0 and Jв  JP. In this case the incre-ment Δθм is very small, as it is determined by the product of small values: the flow of dislocations Jв entering a boundary and settling in it is small, the low-angle bound-ary angle sine square is small either.  The experimental data show that during quasimonotonous deformation the increment of angle misorientations is observed mainly near band boundaries and practically does not take place in cells, blocks and subgrains located in bands. The boundaries of these misorientation areas remain low-an-gle [12]. One may search for the analogy of rate disconti-nuity lines formation and formation of band boundaries occurring in a gradient field of material flow rates. As a result, band boundaries do not practically intersect in a low-gradient field of rates (during quasimonotonous drawing, for example), which results in formation of a grain-subgrain type structure. Another situation arises during non-monotonous de-formation, when the direction of external  force impact on the material changes constantly providing enhanced gradient of rates in the local areas of deformed billets and high intensity of formation and intersection of high-angle band boundaries (rate discontinuity lines). Such pattern is typical of ECAP being non-monotonous pro-cess, when the external surface of a sample does not change and dislocation flows close inside billets on the internal surfaces of the deformation zone. Nonmonoto-nous large deformation results in constant formation of new shear bands and therefore high-angle band bound-aries. High-angle boundaries with a high value of the angle θ, as significant barriers for dislocations flow, contribute to more intensive increment of the angle Δθм (see Formula 1). It is evident that such conditions en-sure intensive formation of a grain-type structure.CONCLUSION 1.  Thus, the performed analysis shows that during de-velopment of effective SPD processes one should adhere to the procedure that accounts the following conditions:   – provision of a maximum high level of single ac-cumulated strain per a processing cycle; – use of simple shear scheme; – provision of induced non-monotony.2.  Localization of deformation zone against non-mo-notony also enhances the effects of grain refinement and ensures formation of equi-axed structures due to high density of differently directed rate discontinui-ty lines, formation and intersection of band high-angle boundaries.AcknowledgementG. I. Raab would like to acknowledge the support of Russian Foundation for Basic Research (project № 14-19-01062). The research was conducted at FSBFEI HPE «Ufa State Aviation Technical University».A.G. Raab would like to acknowledge the support of the Russian Ministry of Education and Science within the state task № 11.729.2014K. The research was con-ducted at FSBFEI HPE «Ufa State Aviation Technical University».REFERENCES[1] Valiev R.Z., Alexandrov I.V., nanostructured materials pro-duced by severe plastic deformation. M: Logos, (2000). 272 p.[2] R.Z. Valiev and T.G. Langdon, Principles of equal-channel angular pressing as a processing tool for grain refinement, Prog. Mater. Sci. 51 (2006), 881-981.[3] Utyashev F.Z., Raab G.I., Deformation techniques for pro-ducing and processing ultrafine-grained and nanostructured materials. – Ufa: Ghilem, NIK Bashk. Encycl. 2013. 376 p.[4] Segal V.M., Reznikov V.I., Drobyshevskiy A.S., Kopylov V.I. Plastic treatment of metals by simple shear // Metalur-gija 1981) 1, 115-123.[5] Hill R. Mathematical theory of plasticity /translated from English. M., 1956. [6] Tamlenov A.D. Theory of plastic deformation of metals. M., 1972.[7] Processes of plastic structure formation in metals. V.M. Segal, V.I. Reznikov, V.I. Kopylov, et al. Minsk: Nauka i Tekhnika, 1994,-232 p. 38.[8] V.V. Rybin. Large plastic deformations and metal failure. Metallurgia, M.1986. 224 p.[9] Nakashima K., Horita Z., Nemoto M., Langdon T.G.. Acta. Mater., 1998. V. 46. P. 1589.[10] G.E. Arkulis, V.G. Dorogobit, Theory of plasticity, M., “Metallurgia” 1987.[11] Ywahashi Y., Horita Z., Nemoto M., Langdon T.G. An in-vestigations of microstructural evolution during equal-chan-nel angular pressing // Acta Mater.(1997) 45, 4733-4742.[12] Hughes D.A., Hansen N. Microstructure and Strength of Nickel at Large Strains // Acta Mater. (2000) 48, 2985-3004.Note:  The responsible for English language is lecturer from Kazan Federal University, Kazan, Russia

Analysis of shear deformation scheme efficiency in plastic structure formation processes

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