Rafail Galeyev

Rafail Galeyev
Institute for Metals Superplasticity Problems of Russian Academy of Sciences | IMSPRAS · 05 Ultrafine-grained Metals and Alloys

PhD

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83
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February 1988 - June 2021
Institute for Metals Superplasticity Problems of Russian Academy of Sciences
Position
  • Researcher

Publications

Publications (83)
Article
Исследовано влияние двух режимов всесторонней изотермической ковки (ВИК) на гидравлическом прессе и последующего отжига на структуру и механические свойства конструкционной низкоуглеродистой стали 12ГБА. Проведен структурный анализ стали методами дифракции обратно рассеянных электронов и растровой электронной микроскопии. Определены механические св...
Article
The Heusler alloys demonstrate magnetically induced strain and magnetocaloric properties, but the mechanical properties are poor. Therefore, in this work, the influence of thermomechanical treatment on the properties of Ni-Mn-Ga-Si Heusler alloys is considered. The effect of multi-axial isothermal forging on functional properties of the Ni2.30Mn0.7...
Article
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The manuscript considers microstructure, mechanical and processing properties (formability and solid state weldability) of sheet titanium alloy VT6(Ti-6Al-4V) with improved superplastic properties production of PJSC «VSMPO-AVISMA Corporation" for the process of superplastic forming at low temperatures and new experimental cheaper sheet titanium all...
Article
Heusler alloys demonstrate various effects, such as the ferromagnetic shape memory effect, the magnetocaloric effect, etc. But these alloys are also liable to destruction during multiple cycles of martensitic transformation. In order to increase stability of functional properties of the alloys, thermo-mechanical treatment by various methods is carr...
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An alloy design approach for titanium alloys is presented. New alloys are isolated, manufactured and tested with an emphasis on the superplastic response. The superplastic effect is found to be optimal between 650 to 750∘C at strain rates between 8.3×10⁻² and 8.3×10⁻³/s – this is a substantial improvement in terms of temperature and deformation rat...
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It is shown that in low carbon steel, the structure after the controlled rolling comprises grains of ferrite and carbides. The average grain size of ferrite was 2.5 µm, the carbide size varied from 1 to 5 µm. Additional warm rolling led to the formation of a fibrous ultrafine-grained (UFG) structure with an average grain/subgrain size about 0.3 µm,...
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The work presents the comparative analysis of the microstructure and character of martensitic transformation in Heusler Ni-Mn-Ga alloys subjected to plastic deformation by forging and complex treatment by forging with subsequent extrusion. It is shown that the treatment by forging leads to the formation of a bimodal structure with large grains of s...
Article
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The formation of a sharp crystallographic texture in a Ni–Mn–Ga Heusler alloy by the multiple isothermal forging has been studied. An analysis of the thermal expansion near the martensitic transformation temperatures in the as-cast and forged states of the alloy shows that the thermomechanical treatment leads to an increase in the anisotropy of the...
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В работе исследовали формирование острой кристаллографической текстуры в сплаве Гейслера системы Ni−Mn−Ga после всесторонней изотермической ковки сплава. Анализ термического расширения в области температур мартенситного превращения в исходном литом и кованном состояниях сплава показал, что деформационная обработка приводит к возрастанию анизотропии...
Article
The results of investigation of the microstructure of two polycrystalline Ni-Mn-Ga alloys subjected to thermo-mechanical treatment by multiple isothermal forging and extrusion are presented. Alloy forging at a temperature of 680°C and 700°C leads to the formation of a bimodal structure which has large grains of several hundred micrometers surrounde...
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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...
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The structure, mechanical properties and impact strength of 5-layered composites based on maraging and low-alloy mild steels are investigated. The effect of subsequent heat treatment on the microstructure and mechanical properties of layered composites is studied. The contribution of the presence of the initial ultrafine-grained microstructure of m...
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The paper presents the results of plastic deformation by the multiple isothermal forging on microstructure and martensitic transformation in polycrystalline Ni54.1Mn19.6Ga24.6Si1.7 alloy. The method of plastic deformation was applied to Heusler alloys for the first time. By recording the temperature dependence of thermal expansion in the field of t...
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Optimization of the chemical composition of Ti2AlNb-based alloy resulted in development of high-strength Ti-20.3Al-22.1Nb-1.2Zr-1.3V-0.9Mo-0.3Si (at.%) intermetallic with rather low density ρ≈5.1 g/cm3. Mechanical properties of the alloy were considerably improved due to formation of the homogeneous ultrafine-grained structure. The ultrafine-graine...
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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...
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The paper reports on the investigation of the effect of various methods of plastic deformation on the structure, texture and mechanical properties of low carbon 12GBA steel. It is found that multiple isothermal forging results in formation of equiaxed ultrafine-grained (UFG) structure with a uniform distribution of the second phase, the size of whi...
Article
The effect of all-round isothermal forging on the structure and mechanical properties of low-carbon steel 12GBA is investigated.
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The influence of annealing temperature on ultrafine-grained structure (UFG) of low-carbon steel 05G2MFB, produced by multiple isothermal forging (MIF) and warm rolling is investigated. Following 1-hour annealing (from 20 to 550°С), the fibrous UFG-structure formed as a result of rolling remains virtually the same. The equiaxial UFG-structure is fou...
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.
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This work presents the results of experimental studies and computer modeling of the crystallographic texture evolution in the billets of titanium alloy VT6, subjected to plane rolling in the coarse-grained and ultrafine-grained (UFG) states. UFG state has been formed by the method of multiaxial isothermal forging at 650°С with the number of cycles...
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This paper presents results of a research on the effect of warm rolling on structure and mechanical properties of the low-carbon pipe steel. The warm rolling results in formation of anisotropic ultra-fine grained (UFG) structure with average grain / subgrain size 0.5 μm in transverse direction and 20—30 μm along the rolling direction. The formation...
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Alloys of Fe-Cr-Co have high magnetic properties, processability and relative low cost, therefore it is of interest for use as a electrical machine rotor. One promising approach to the manufacture of large rotor is the creation of composite rotor system Fe-Cr-Co magnetic alloys and low carbon steel, where low carbon steel is used as a magnetic core...
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Summarizing the results of the studies performed at IMSP RAS, the principles of processing of a uniform ultrafine-grained (UFG) structure in large-section billets by means of the technique of multiple isothermal forging are formulated. These principles imply a uniform introduction of plastic strain energy into large-section billets, minimization of...
Article
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The effect of severe warm rolling on the structure and mechanical characteristics of the 12GBA low-carbon steel has been studied. A fibrous ultrafine-grained structure has been formed; the average transverse size of structural elements was 0.5 μm and the length of fibers in the longitudinal section was 20–25 μm. An analysis of this ultrafine-graine...
Article
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The complex deformation processing effect on the structure and mechanical properties in the low-carbon steel 05G2MFB is investigated. The complex deformation processing of the low carbon steel was obtained ultrafine-grained (UFG) structure with an average size of grains of 0.4 μm. The formation of UFG structure leads to in to two times increase in...
Article
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It is shown that the intensive warm rolling of 12GBA low carbon steel leads to the formation of ultrafine-grained (UFG) structure with an average grain size of 0.5 µm in transverse section and to two times increase in strength by comparison to the initial coarse-grained (CG) state. Impact tests have shown an increase of fracture strength in fibrous...
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The submicrocryctalline structure of the 12GBA low carbon steel was processed by multi-axis isothermal forging. The average grain size was about of 0.3 µm. The submicrocryctalline steel has three times higher strength than the coarse-grained steel andsufficiently high ductility and impact strength. Subsequent annealing leads to a slight lowering of...
Article
Laminated composite materials consisting of an orthorhombic Ti2AlNb based alloy and an (a+b) titanium alloy have been fabricated at a laboratory scale using a two-step process involving diffusion bonding and hot-pack rolling. The feasibility of fabrication of two- and three-layered materials with high quality bonding between layers has been demonst...
Article
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The principles of fabricating nanostructured bulk and sheet materials by the methods of multiple isothermal forging and warm rolling are formulated. The first method, which is based on dynamic recrystallization, allows one to obtain bulk materials with a uniform nanostructure. The second method makes it possible to transform the latter into a sheet...
Article
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Laminated composite materials consisting of an orthorhombic Ti2AlNb based alloy and an (α+β) titanium alloy have been fabricated at a laboratory scale using a two-step process involving diffusion bonding and hot rolling. The feasibility of fabrication of two and three layered materials with high quality bonding between layers was demonstrated. Prel...
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The microstructure and tensile properties of a layered composite material fabricated by solid-state bonding of its components using pressure welding are studied at room and elevated temperatures. The components are made of a high-temperature VT25U titanium alloy and an intermetallic alloy (O alloy) based on orthorhombic titanium aluminide of the co...
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Mechanical properties of a Ti2AlNb-based intermetallic alloy both at room and elevated temperatures were considerably improved due to formation of a homogeneous microstructure with the average grain size of about 300 nm. At room temperature, elongations up to 25% were obtained and the ultimate strength reached 1400 MPa. The alloy exhibited superpla...
Data
Laminated composite materials consisting of an orthorhombic Ti2AlNb based alloy and an (a+b) titanium alloy have been fabricated at a laboratory scale using a two-step process involving diffusion bonding and hot-pack rolling. The feasibility of fabrication of two- and three-layered materials with high quality bonding between layers has been demonst...
Article
Full-text available
This paper reports on investigations of the solid state formability and weldability of Ti–6Al–4V titanium alloy sheet with submicrocrystalline structure (grain size 0·5 and 0·8 μm) under superplastic conditions at temperatures of 700 and 800°C. It has been established that the submicrocrystalline condition of the sheet material reduces the temperat...
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...
Article
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The mechanical behavior and microstructure evolution of a stable beta, metastable beta, and beta-rich titanium alloys during hot deformation in both beta and alpha/beta phase fields were studied. The effects of thermomechanical processing and alloy content on final grain size and microstructure homogeneity in the alloys are given. The processing wi...
Article
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A comparative investigation of mechanical properties of Ti–6Al–4V titanium alloy with microcrystalline and submicrocrystalline structures in the temperature range of 20–600 C has been carried out. The grain sizes under the submicrocrystalline and microcrystalline conditions are 0.4 and 10 mm, respectively. The alloy with the microcrystalline struct...
Article
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The “abc” deformation method for production of large-scale billets with submicrocrystalline structure was developed. A large billet of Ti–6Al–4V alloy (150-mm diameter × 200-mm length) with a homogeneous submicrocrystalline structure was produced. The refined structure with a grain/subgrain size of about 0.4 μm leads to a substantial mechanical pro...
Article
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The microstructure, texture, room temperature and superplastic properties of the Ti-64 sheets with submicrocrystalline (SMC) structure were investigated. For evaluate the superplastic performance of submicron-grained sheets the tensile tests were carried out in the temperature range of 600-800°C. Submicron-grained sheets possessed a strong basal te...
Article
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Microstructure evolution and mechanical behavior in commercial pure titanium and Ti-6Al-4V alloy during successive compression of samples in three orthogonal directions ("abc" deformation) at 400 and 550degreesC, respectively have been investigated. Formation of submicrocrystalline (SMC) structure as a result of warm deformation both in Ti and allo...
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...
Chapter
Materials with a submicrocrystalline (SMC) structure have an average grain size less than 1 µm and show enhanced mechanical properties such as increased strength and fatigue resistance [1]. They also exhibit superplastic behavior at temperatures much below the temperature range typical for materials with micron-sized grains [1, 2], thereby leading...
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
The superplastic behavior of extremely fine-grained (300 nm) Ti–6Al–4V was studied by performing elevated temperature uniaxial tensile tests in the temperature range of 700–900°C. The strain rate was varied from 10−5 to 10−1s−1 to estimate the value of the strain rate sensitivity coefficient, m. The ductility of the fine-grained Ti–6Al–4V specimens...
Article
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The mechanical behavior and structure formation during deformation under high pressure of titanium and Ti64 alloy were studied. It was shown that deformation at low temperature (0.4Tm) leads to the formation of structure with grain size less than 0.5 μm both in the Ti and Ti64. The contribution of the strengthening processes with decreasing deforma...
Conference Paper
The features of mechanical behavior and structure formation of commercial pure titanium during warm severe plastic deformation (WSPD) were studied. It is shown that after the strain е=6 at the temperature 400oС and the strain rate 10-3 s-1 a structure with a grain size of 0.2 mcm is formed. Its mechanical behavior at WSPD is described by a curve wi...
Conference Paper
Warm severe plastic deformation realized via multiple forging can be used for formation of fine-grained microstructures with grain size of several hundred nanometers or less in titanium alloys. The smaller the grain size, the better the superplastic properties are resulted from lower temperature deformation. It has been established that the smalles...
Conference Paper
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Comparative investigations of superplastic behavior and formability of commercial sheets with microcrystalline (MC, a grain size of 3-5 mcm) and submicrocrystalline (SMC, a grain size of 0.3 mcm) structure out of titanium Ti-6Al-4V alloy have been performed. It is shown that the decrease in the grain size leads to a significant decrease in the temp...
Article
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A Ti–6Al–4V alloy sheet with a submicrocrystalline structure (grain size of 0.3 μm) was produced by multistep isothermal forging followed by flat rolling at temperatures below 650°C. The sheet showed a very strong basal texture and isotropic properties in the sheet plane. Room temperature yield strength, ultimate tensile strength, and fatigue limit...
Conference Paper
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The effects of the initial microstructure and thermomechanical conditions of deformation on the formation of fine-grain microstructure in alloy Ti-6Al-4V were examined. Continuous dynamic recrystallization (DR) takes place over a wide temperature range within the (+)-region. The conversion of α/β phase-boundaries from a semi-coherent state into a...
Conference Paper
Full-text available
The features of mechanical behavior and structure formation during deformation of the titanium and the alloy Ti64 were studied. The mechanism of titanium structure formation depends on a deformation temperature. At high temperatures (650C) the formation of new grains occurs via migration of initial grain boundaries that is a feature of discontinu...
Article
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For the example of two-phase VT8 titanium alloy, the correlation between the rate sensitivity of the plastic stress, which is the basic index of the appearance of superplasticity, and increased solid-state weldability of the material is established. It is shown experimentally that depressing the lower boundary of superplastic deformation, by changi...
Article
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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
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Mechanical behavior and structural changes in a VT30 titanium alloy quenched from the β field were studied in the course of deformation at temperatures of 0.4-0.43Tm (550-600°C). A decrease in the test temperature was shown to change the single-peak σ-ε curve typical of high-temperature deformation, leading to the repeated strengthening and softeni...
Article
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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
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The mechanical properties of VT6 titanium alloy with microcrystalline (MC) and submicrocrystalline (SMC) structure are compared in the temperature range 20-600°C. The mean grain size for the SMC and MC states is 0.4 and 10 μm, respectively. The alloy with MC structure is used in a state strengthened by quenching and aging. Conversion to the SMC sta...
Article
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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
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Severe plastic deformation at temperatures below 0.4...0.5Tm was used to obtain submicrocrystalline (SMC) structure in pure titanium and titanium alloys Ti-6.7Al-4.7Mo and Ti-11Mo-5.5Sn-4.2Zr. The structural studies showed that the density of titanium and its alloys in the SMC condition was less that in the coarse grained (CG) one. This change is c...
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
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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...