S.P. Malysheva's research while affiliated with Institute for Metals Superplasticity Problems of Russian Academy of Sciences and other places

Publications (25)

Article
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This second part of the article describes the results of studies on technological properties (formability and solid state weldability) of sheet titanium alloy VT6 (Ti-6Al-4V) with improved superplastic properties at low temperatures. When studying the formability of the sheet blanks, the radius of curvature R and average thickness S in the spherica...
Article
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В работе описаны результаты сравнительных исследований механических свойств титанового сплава ВТ6 (Ti-6Al-4V) со стандартной равноосной микрокристаллической структурой (МК) с размером зерен α-фазы 10 мкм, однородной субмикрокристаллической структурой (СМК) с размером зерен (фрагментов) 0,5 мкм и бимодальной субмикро-микрозеренной структурой, состоя...
Article
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The paper describes the results of comprehensive studies of the microstructure, mechanical and technological properties (formability and weldability in the solid state) of the titanium sheet alloy VT6 (Ti-6Al-4V) with improved superplastic properties produced by PSC «VSMPO-AVISMA». In the first part the initial microstructure of the alloy and its m...
Article
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Investigations of technological properties of new titanium alloy sheet VST2k have been conducted. It is found that the titanium alloy has a good solid state weldability and formability under conditions of superplasticity at temperatures 750-900C. By the method of SPF/DB sheet of VST2k alloy in a low-temperature superplasticity at a temperature of...
Article
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In this paper we evaluated the possibility of increasing the mechanical properties of titanium alloy VT6 by forming it ultrafine structures with different grain size. Analyzed the prospects of using the strengthened state VT6 alloy for the production of highly machine parts with regard to their operating conditions.
Article
High-resolution electron back-scatter diffraction (EBSD) analysis was employed to establish mircostructure evolution in heavily cold-rolled alpha-titanium. After thickness reductions of 75% to 96%, significant microstructure and texture changes were documented. The surface area of high-angle grain boundaries was almost tripled, thus giving rise to...
Article
The most important room temperature mechanical properties of two-phase Ti–6Al–4V alloy with ultrafine grained microstructure were studied in the present work. Bulk preforms of the alloy with ultrafine grained microstructure were produced by warm multiaxial forging. The final structure consisted of alpha and beta particles with size of 150–500 nm de...
Article
The evolution of microstructure in commercial-purity titanium during cold rolling to a thickness strain of 2.6 was quantified using electron backscatter diffraction. The measurements were analyzed in terms of the mean grain size and the density of boundaries (the ratio of total boundary length to the scanned area). The density of high-angle boundar...
Article
Changes in the microstructure and texture due to cold rolling of sheets from commercial titanium with initial coarse-grained and submicrocrystalline structures are studied. The submicrocrystalline structure is obtained in titanium by uniform severe plastic deformation. The permissible degrees of deformation for rolling of titanium with different gr...
Article
The effect of deformation temperature on the grain size in titanium VT1-0 and double-phase titanium alloy VT6 is studied. The temperature-and-rate modes of formation of submicrocrystalline structure are determined. The mechanical behavior and the evolution of the microstructure in the course of warm severe deformation is investigated by means of su...
Chapter
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The structure evolution and mechanical behavior of titanium and Ti-64 alloy during successive compression of sample along three orthogonal directions or “abc” deformation were studied. It is shown formation of submicrocrystalline structure in the both materials under warm “abc” deformation. In titanium the structure evolution occurs via formation o...
Article
The fabrication of strips of commercial VT1-0 titanium with a submicrocrystalline (SMC) structure is studied. The SMC structure is preliminarily formed in blanks by warm severe plastic deformation. Such blanks have a mixed microstructurc with a high dislocation density, grains, subgrains, elements of a band structure, and regions with fine (0.1 μm)...
Article
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The structure of VT1-0 titanium in the submicrocrystalline (SMC) state and changes in its structure and mechanical properties during deformation in a temperature range of (0.15-0.45)Tm have been studied. The formation of an SMC structure in titanium via warm severe plastic deformation is accompanied by dynamic strain aging (DSA). The development of...
Article
An influence of cold rolling on structure and mechanical properties of strip and foil of BT1-0 alloy with submicrocrystalline (SMC structure) is investigated. X-ray diffraction analysis of the annealed specimens showed that the cold rolling leads to essential additional substructural and texture hardening. The billets with the SMC structure can be...
Article
Full-text available
Formation of submicrocrystalline (SMC) structures with grain sizes within interval of 0,06 - 0,5 μm in BT1-00 commercial pure titanium and BT6, BT8 and BT30 two-phase titanium alloys at severe plastic deformations realized by means of multiple three-dimensional forging under isothermal conditions in the temperature range of 400 - 700°C is considere...
Article
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Severe plastic deformation at temperatures below 0.4Tm was used to obtain submicrocrystalline titanium. It was revealed that the mass density of titanium with a grain size of 100 nm was decreased by 0,5% compared with coarse-grained titanium. The decrease in density is not connected with formation of pores or cracks during intensive deformation. On...
Article
Full-text available
Effect of the annealing temperature on the microstructure, logarithmic decrement, and elasticity modulus of submicrocrystalline commercial titanium (of grade VT1-00) and a VT8 titanium alloy was studied. Imparting these materials a submicrocrystalline condition was established to slightly enhance the elasticity modulus and have no effect on the log...
Article
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The effect of grain size varying between 0.2 and 50 μm on the mechanical behavior of VT1-00 grade titanium was studied. It was shown that grain refinement substantially increases room-temperature strength and deteriorates plasticity, especially in the range of uniform deformation. The strain hardening of the material was found to have a multistaged...
Article
Full-text available
The modulus of elasticity and the microstructure of a commercial VT1-00 titanium with a submicrocrystalline (SMC) structure (grain size 100-150 nm) produced by large plastic deformation were studied as a function of annealing in a temperature range of 420 to 800°C. It was established that, as the structure of titanium is refined from a coarse-grain...
Article
The density in submicrocrystalline titanium produced by repeated all-round deformation and its varying on subsequent recrystallization annealing were under study. The density was measured by the method of hydrostatic weighing. It is found that the density of microcrystalline titanium is 0.5% lower as compared to that of coarse-grained material. Thi...
Article
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Dynamic recrystallization in commercial titanium VT1-00 under hot deformation in the temperature range of mechanical twinning (lower 0.5 Tmelt) was investigated. Compression tests were carried out in the range of 450-650°C at strain rate of 3·10-4 s-1 using specimens with initial grain size of 150 μm. It is found that under 75% reduction at 450°C t...
Article
A method for qualitative characterization of the phase boundary spectrum using x-ray diffractometry is proposed. The method is tested on a two-phase titanium (α + β)-alloy with lamellar and globular structures.
Article
Full-text available
Dynamic recrystallization of commercially pure titanium during hot deformation in the temperature region of mechanical twinning (below 0.5 Tmelt) has been studied. It has been found that microstructure with a grain size of up to 0.2 mm is formed. Differences in mechanical behavior of titanium in submicrocrystalline and coarse-grained states are sho...

Citations

... Ti-6Al-4V is a most broadly used titanium alloy [1][2][3][4]. This is due to the wide spectrum of its mechanical properties, which are achieved by various thermo-mechanical treatments [1][2][3][4][5][6][7][8][9]. The resulting microstructures of the alloy are characterized by a stored deformation energy, which is related with dislocations, interfaces and other defects. ...
... The chemical composition of these materials complies with Russian standards (GOST 19807-91). The titanium sheet alloy has improved superplastic properties [19]. The three-layer material was obtained by diffusion bonding of the two plates with the intermediate sheet at temperature 800°C in a vacuum furnace under argon pressure using a flexible membrane. ...
... The stability of the manufacturing and machining process for metal alloy parts depends on the continuity and uniformity of the grain structure [1,2]. Recently, titanium alloys have become increasingly applicable in the deformed condition owing to the developments connected with the thermal and deformation processing technologies [3]. ...
... The use of UFG titanium, which has unique strength and fatigue char acteristics, makes it possible to develop medical implants with an improved design, i.e., with a smaller cross sectional area, as well as increased strength and reliability [7]. Currently, extensive studies of the evolu tion of the microstructure and mechanical properties of pure titanium under the effect of ECAP [4], all round forging [8][9][10][11], and combined SPD treatment involving ECAP followed by forging and rolling [7] have been carried out. ...
... Another method of synthesizing bulk nanostructured billets is multiple forging where dynamic recrystallization plays the important role on the refinement process ["Galeyev (1990)", "Imayev (1992)", " Salishchev (1993)"]. The process involves multiple forging operations: setting and pull broaching with a change of the axis of the applied strain or load. ...
... The value of the strain rate sensitivity after the final step of "abc" deformation was m = 0.1, thus indicating that the steady-state flow exhibited in the cumulative σ-Σε curve (Fig. 10b) was not related to superplasticity even though the material had developed a very-fine microstructure. In this regard, earlier results [31] have shown that superplasticity of UFG CP Ti can be mitigated by dynamic strain aging (and its associated negative rate sensitivity) inasmuch as the temperature interval for both processes (~0.3-0.4 of the melting temperature) overlap [31,32]. Therefore, it can be concluded that the presence of steady-state flow in the cumulative σ-Σε plot indicates a balance between strain hardening and softening due to the occurrence of dynamic recovery/continuous dynamic recrystallization. ...
... The MAF technique is based on stage-by-stage structure refinement in the process of repeated operations of uniaxial compression, and is distinguished by its labor intensity. As a result of the use of the MAF for the processing of titanium, bulk billets with a mean grain size of about 200 nm and a UTS of 810 MPa were produced [4]. Another efficient technique for UFG structure formation is ECAP. ...
... Wang stated that cold rolling process improves the tensile strength and reduce the elastic modulus of the TiNbTaZr titanium alloy through grain refinement [6]. Dyakonov studied the mircostructure evolution of the pure titanium subjected to cold rolled treatment [7]. The grains were significantly refined by the treatment, and the splitbasal texture strength was increased due to the activation of 〈c+a〉 slip. ...
... EBSD images were obtained for the Al and Ti grains without heat treatment in refs. [30,31], respectively. The Al grains had an elongated morphology, with grain size reaching 200-300 μm in length and 5-10 μm in width and elongated in the RD direction. ...
... By refining the structure of the Ti-45Nb alloy, the plasticity before fracture decreases to 6%. The decrease in the ductility of the alloys in the UFG state, as obtained by SPD, is usually associated with a general tendency for a rapid loss of plastic flow stability, due to the low ability of the material to tolerate strain-hardening [34,48,95]. It should be noted that, according to the results in previous studies [30,118], the limited strain at which the destruction of the UFG samples occurs during compression in the case of the Ti, Zr-1Nb, and Ti-45Nb alloy is at least 20%, which is 3 times larger than the plasticity before fracture seen in the tensile tests, in contrast with the fine-grained (FG) magnesium alloys produced by I-ECAP [41]. ...