Strength and ductility-related properties of ultrafine grained two-phase titanium alloy produced by warm multiaxial forging

Zherebtsov, Sergey; Kudryavtsev, Е. А.; Kostjuchenko, S.; Malysheva, S. P.; Салищев, Г. А.

doi:10.1016/j.msea.2011.12.102

Cited by 138 publications

(69 citation statements)

References 15 publications

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“…The tensile strength after ε = 2 or ε = 2.67 is 1315MPa in both cases. This is the same value as that obtained in Ti-6Al-4V alloy earlier by warm MAF [4,8,9]. Meanwhile some difference in the tensile elongation of specimens swaged to ε = 2 (δ=9%) or ε=2.67 (δ = 10.5%) is observed.…”

Section: Resultssupporting

confidence: 88%

“…Those processes were most likely intensified due to changing in deformation path, which is proper to swaging. For example very similar microstructure was obtained via multiaxial forging (MAF) [4,8]. However heritable preferred orientation of boundaries along the metal flow direction revealed itself as a lamellar microstructure at low magnifications.…”

Section: Resultsmentioning

confidence: 74%

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Ultrafine-grained structure formation in Ti-6Al-4V alloy via warm swaging

Klimova

Boeva²,

Zherebtsov

et al. 2014

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. The influence of warm swaging on the structure and properties of Ti-6Al-4V alloy was studied. Warm swaging of the alloy in the interval 680-500°C with the total strain of ε=2.66 was found to be resulted in the formation of a homogeneous globular microstructure with a grain size of 0.4µm in both longitudinal and transversal sections. Room temperature tensile strength and tensile elongation of the swaged alloy was 1315MPa and 10.5%, respectively. Ultrafine-grained Ti-6Al-4V alloy produced by swaging exhibited good workability at 600-700 °C. IntroductionOne of the promising approaches to improve mechanical properties of structural materials is the formation of an ultrafine-grained (UFG) structure with a grain size less than 1µm [1]. In comparison to coarse grained materials UFG materials exhibit enhanced static and cyclic strength, hardness and wear resistance [2]. Such combination of properties can reduce the dimensions and weight of parts while keeping their structural strength. This fact is especially important for titanium alloys. Providing low density, high specific strength and an excellent corrosion resistance [3], titanium alloys are used in a wide variety of aviation, aerospace, shipbuilding, automobile production.To obtain the UFG structure in metallic materials severe plastic deformation at low temperatures (typically below 0.5 T m ) is usually used [1]. One of the main parameters of severe plastic deformation which can influence on the kinetics of ultrafine-grained structure formation is strain path. In comparison to unidirectional deformation, change in the load direction during large straining can considerably increase both the kinetics of microstructure refinement and the final structure homogeneity. One of the well-known ways to use this approach is multidirectional forging (MF); this method shows particularly good result in case of two-phase titanium alloys allowing formation of a homogeneous microstructure with grain size of 0.4µm [4]. However MF has an essential fault associated with a relatively high laboriousness of the method.More efficient way to obtain the UFG structure in rod preforms is warm swaging [5]. Swaging consists in periodic compressions of a rod and reduction its diameter by split dies which simultaneously move along radial, rotational and axial directions relative to the axis of the rod. In this case the deformation has a quasi-hydrostatic compression scheme. This gives a possibility to deform materials with high accuracy to large strain without fracture.The aim of the present work was to study the formation of UFG microstructure of Ti-6Al-4V titanium alloy in both longitudinal and transversal sections during swaging in the temperature range 680-500 °C with the total strain of ε = 2.67.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 74%

Ultrafine-grained structure formation in Ti-6Al-4V alloy via warm swaging

Klimova

Boeva²,

Zherebtsov

et al. 2014

IOP Conf. Ser.: Mater. Sci. Eng.

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“…All flow curves exhibited a peak flow stress at the initial stages of deformation followed by a moderate decrease in flow stress. The uniform elongation of the alloy was rather small in all cases which is quite typical of severely deformed materials [23]. However, after strain localization (at the maximum flow stress), when the plastic deformation had become concentrated in the neck, the alloy had showed quite pronounced additional elongation.…”

Section: Resultsmentioning

confidence: 79%

Evolution of Microstructure and Mechanical Properties of a CoCrFeMnNi High-Entropy Alloy during High-Pressure Torsion at Room and Cryogenic Temperatures

Zherebtsov

Stepanov

Ivanisenko

et al. 2018

Metals

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High-pressure torsion (HPT) is applied to a face-centered cubic CoCrFeMnNi high-entropy alloy at 293 and 77 K. Processing by HPT at 293 K produced a nanostructure consisted of (sub)grains of~50 nm after a rotation for 180 • . The microstructure evolution is associated with intensive deformation-induced twinning, and substructure development resulted in a gradual microstructure refinement. Deformation at 77 K produces non-uniform structure composed of twinned and fragmented areas with higher dislocation density then after deformation at room temperature. The yield strength of the alloy increases with the angle of rotation at HPT at room temperature at the cost of reduced ductility. Cryogenic deformation results in higher strength in comparison with the room temperature HPT. The contribution of Hall-Petch hardening and substructure hardening in the strength of the alloy in different conditions is discussed.

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“…Rectangular samples with initial dimensions of 10 mm × 12.2 mm × 15 mm were machined for multidirectional forging (MDF), which was carried out by performing isothermal multipass compression tests with a change in the compression direction of 90°in order of the three orthogonal axes from pass to pass [15,21,27]. The samples were compressed at temperatures of 500, 600, 700, and 800°C at a strain rate of 10 −3 s −1 to a strain of 0.4 in each pass.…”

Section: Methodsmentioning

confidence: 99%

“…The mechanical properties of structural metallic materials can be enhanced by grain refinement. Ultrafine-grained materials with an average grain size below 1 μm have been suggested to possess a unique combination of high strength and sufficient ductility that has aroused great interest in their production [13][14][15][16]. One of the most promising methods for obtaining ultrafine-grained steels and alloys is large strain plastic working [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Σ3 CSL boundary distributions in an austenitic stainless steel subjected to multidirectional forging followed by annealing

Tikhonova

Kuzminova

Fang

et al. 2014

Philosophical Magazine

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The effect of processing and annealing temperatures on the grain boundary characters in the ultrafine-grained structure of a 304-type austenitic stainless steel was studied. An S304H steel was subjected to multidirectional forging (MDF) at 500-800°C to total strains of~4, followed by annealing at 800-1,000°C for 30 min. The MDF resulted in the formation of ultrafine-grained microstructures with mean grain sizes of 0.28-0.85 μm depending on the processing temperature. The annealing behaviour of the ultrafine-grained steel was characterized by the development of continuous post-dynamic recrystallization including a rapid recovery followed by a gradual grain growth. The post-dynamically recrystallized grain size depended on both the deformation temperature and the annealing temperature. The recrystallization kinetics was reduced with an increase in the temperature of the preceding deformation. The grain growth during post-dynamic recrystallization was accompanied by an increase in the fraction of Σ3 n CSL boundaries, which was defined by a relative change in the grain size, i.e. a ratio of the annealed grain size to that evolved by preceding warm working (D/D 0 ). The fraction of Σ3 n CSL boundaries sharply rose to approximately 0.5 in the range of D/D 0 from 1 to 5, which can be considered as early stage of continuous post-dynamic recrystallization. Then, the rate of increase in the fraction of Σ3 n CSL boundaries slowed down significantly in the range of D/D 0 > 5. A fivefold increase in the grain size by annealing is a necessary condition to obtain approximately 50% Σ3 n CSL boundaries in the recrystallized microstructure.

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Strength and ductility-related properties of ultrafine grained two-phase titanium alloy produced by warm multiaxial forging

Cited by 138 publications

References 15 publications

Ultrafine-grained structure formation in Ti-6Al-4V alloy via warm swaging

Ultrafine-grained structure formation in Ti-6Al-4V alloy via warm swaging

Evolution of Microstructure and Mechanical Properties of a CoCrFeMnNi High-Entropy Alloy during High-Pressure Torsion at Room and Cryogenic Temperatures

Σ3 CSL boundary distributions in an austenitic stainless steel subjected to multidirectional forging followed by annealing

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