Defect structure and thermomechanical stability of nano- and microcrystalline titanium obtained by different methods of intense plastic deformation

Бетехтин, В. И.; Sklenička, V.; Кадомцев, А. Г.; Kolobov, Yu. R.; Narykova, M. V.

doi:10.1134/s1063783417050043

Cited by 11 publications

(11 citation statements)

References 16 publications

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“…confirming the increase in impact toughness in all modified alloys, while their hardness was close to that of unmodified alloys [89][90][91][92][93]. Modification led to the refinement of borides, besides places with thinning ('necking') of the eutectic network appeared beneficial for easier network destruction [70].…”

Section: Control Of the Borides' Size And Morphologysupporting

confidence: 60%

“…4 595 Current Functional Materials for Wear-Resistant Casting (0.3-0.45 wt.%) and a high boron content (1.5-3.0 wt.% b), the wear resistance of high-boron alloy significantly exceeds the wear resistance of high-chromium cast iron. the wear resistance of fe-C-b alloys with high contents of carbon (0.5-1.0 wt.%) and boron (2.0 wt.%) is also higher than that of high-Cr cast iron [70,71].…”

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confidence: 99%

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2022

Prog. Phys. Met.

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in clude high-alloyed white cast irons, high-speed steels (hSSs), highentropy alloys (hEAs), cold-formed die steels, cemented carbide alloys, particle-reinforced metal matrix composites (PMMCs), etc. [7][8][9][10]. A wide range of conventional and innovative technologies are focused to modify a working surface via structural and chemical modi fication as well as coating deposition to create protecting layers of up to several millimetres thick [11][12][13]. however, in many applications, the wearinduced volume loss is much bigger; thus, the parts should be manufactured from special materials ensuring higher bulk wear resistance. the increased requirements for wear-resistant materials imply using non-standard solutions when creating new types of tribological alloys. Multicomponent Cast Ironsone of the relatively new classes of wear-resistant alloys is 'multicomponent cast irons' (MCCIs), which were first proposed by Matsubara with coauthors [14,15] in the mid-1990s to increase the durability of rolls of hot rolling mills. the idea of MCCIs followed the known concept of alloying high-speed steel M2 (AStM A600), which implies the addition of several carbide-forming elements in approximately equal proportions (M2 steel contains 0.78-0.88 wt.% C, 5.50-6.75 wt.% W, 4.50-5.50 wt.% Mo, 3.75-4.50 wt.% Cr, and 1.75-2.20 wt.% V). A basic chemical composition of MCCI is (in wt.%) fe-2 C-5 Cr-5 Mo-5 W-5 V-5 Co [16]. Molybdenum and tungsten (which act similarly) are adopted in MCCIs to form complex carbides (Mo, W, fe) 2 C or M 2 C, and (Mo, W, fe) 6 C or M 6 C, where M denotes a metal (martensite). being dissolved in matrix, Mo and W improve the hardenability and promote the secondary precipitation hardening under tempering (which is important for hot temperature wear applications). Vanadium forms hard eutectic carbides (V, fe)C or (V, fe) 4 C 3 (denoted as MC); also, it takes part in secondary hardening. Chromium is partially dissolved in matrix inhibiting pearlite and bainite transformations, thus, enhancing the hardenability. In addition, Cr contributes to wear resistance through eutectic carbide M 7 C 3 , which is harder than cementite carbide. In their turn, carbides M 2 C, M 6 C, and MC are harder than M 7 C 3 . Cobalt decreases the hardenability but it greatly improves the high-temperature strength suppressing the heat-induced grain coarsening. thus, MCCIs feature a multiphase structure consisting of different hard carbides dispersed in the metallic matrix.the main feature which distinguishes MCCIs from M2-hSS is about two-fold increased carbon content (1.8-2.2 wt.%) [17]. Carbon concentration controls the crystallization path and the set of carbide phases in MCCIs. According to [18], carbon content is selected based on C bal

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Section: Control Of the Borides' Size And Morphologysupporting

confidence: 60%

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confidence: 99%

Untitled

2022

Prog. Phys. Met.

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“…The first one was prepared from a bar with a diameter of 30 mm. The bar was deformed by one step of helical rolling, one step of lengthwise rolling (both at 673 K), and, finally, again by helical rolling at ambient temperature to reach a final diameter of about 8 mm [ 19 , 20 ]. Thus, the deformed material corresponds to the imposed strain of about 1.5.…”

Section: Methodsmentioning

confidence: 99%

Influence of Cryo-Processing and Post-SPD Annealing on Creep Behavior of CP Titanium

et al. 2022

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The commercial purity of VT1-0 titanium was processed by the rolling process and executed at elevated, room, and cryo-temperatures. These processings led to the formation of an ultrafine-grained microstructure, with the mean grain size at a nanometer level. Some of these materials were statically annealed at a temperature of 823 K for 1 h, which led to significant subgrains and grain coarsening. The constant load creep tests in tension were carried out in argon on all states of materials, at temperatures of 648–723 K and different ranges of applied stresses. From the value of the steady-state creep rate, the control creep mechanisms were determined. The microstructure analyses were carried out via SEM and TEM. It was found that titanium prepared at elevated and room temperatures have a higher creep strength than titanium prepared at cryo-temperatures. Furthermore, the post-SPD —annealing led to a significant decrease in the creep properties. The influence of the preparation temperature on the difference of the creep behavior were discussed and explained using the microstructure analyses of the tests’ samples.

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“…Однако в таких материалах часто возникают несплошности в виде нанопор, расположенных вдоль границ и тройных стыков зерен [2][3][4][5][6][7]. В статьях [8][9][10] показано, что с накоплением нанопор связано снижение долговечности СМК материалов в условиях длительного нагружения. Согласно [10], в процессе ползучести СМК материалов определенная доля нанопор развивается в микропоры, создавая тем самым «очаги» разрушения, снижающие долговечность материала.…”

Section: Introductionunclassified

Diffusion Nucleation of Cavities in Grain Junctions of Submicrocrystalline Materials

Pupynin

Kirikov

Перевезенцев

2021

PSP

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The conditions of diffusional cavity nucleation in submicrocrystalline materials processed by the methods of intensive plastic deformation (equal-channel angular pressing, multiaxial forging, high pressure torsion, etc.) are analyzed. To date, the question of the mechanism of nucleation of cavities in such materials remains debatable due to the fact that the processing of materials by the methods of intensive plastic deformation is carried out at high hydrostatic pressures that prevent the appearance of pores. The possibility of diffusive nucleation of nanopores in the region of triple junctions of grains containing negative strain-induced wedge disclinations, generating high tensile stresses in the vicinity of triple junctions, comparable in magnitude to external hydrostatic pressure, is shown. Such junction disclinations inevitably occur at the grain junctions due to the heterogeneity of the plastic deformation through the ensemble of polycrystal grains. It is shown that an important condition for the nucleation of cavities is not only the presence of high internal tensile stresses from junction disclinations, but also an extremely high concentration of nonequilibrium strain-induced vacancies characteristic of submicrocrystalline metals, comparable in values to the vacancy concentration, at temperatures close to solidus. The influence of the strength of junction disclinations, the value of external hydrostatic pressure and the degree of supersaturation of the material by nonequilibriumstrain-induced vacancies on the rate of diffusional nucleation and the volume of critical pore nuclei is analyzed. It is established that in order to effectively suppress the process of pore formation in the grain boundary triple junctions, it is necessary to apply an external hydrostatic pressure that compensates for internal elastic fields from junction disclinations.

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Defect structure and thermomechanical stability of nano- and microcrystalline titanium obtained by different methods of intense plastic deformation

Cited by 11 publications

References 16 publications

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Influence of Cryo-Processing and Post-SPD Annealing on Creep Behavior of CP Titanium

Diffusion Nucleation of Cavities in Grain Junctions of Submicrocrystalline Materials

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