Статті (відділ 36)

Постійне посилання зібранняhttps://archive.ipms.kyiv.ua/handle/123456789/125

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Influence of Hot Forging on the Elastic Properties and Character of Anisotropy of Powder Composites with Titanium Matrix
(Materials Science, 2021) Bagliuk G. А.; Bezimyanniy Yu. G.; Stasiuk О. О.
We analyze the specific features of the structure and elastic characteristics of powder titanium-matrix composites reinforced with titanium carbide and titanium boride. The difference between the characters of dependence of the modulus of elasticity on the content of high-modulus component is analyzed for sintered and hot-forged composites. It is discovered that the modulus of sintered materials is determined both by the content of reinforcing admixtures and by the porosity of the alloy. At the same time, for hot-forged specimens, the modulus monotonically increases with the content of the high-modulus components. It is shown that, for sintered composites of all compositions and for hot-forged composites reinforced by titanium carbide, anisotropy is practically absent, whereas for hot-forged composites reinforced by titanium boride, an insignificant (up to 10%) anisotropy of the structure and elastic characteristics is caused by the reorientation of acicular titanium monoboride particles in the direction perpendicular to the direction of application of the active force in course of hot forging.
The Structure and Properties of 65 wt.% Fe– 35 wt.% FKh800 Chromium Carbide Steel Doped with Titanium Boride Additions
(Powder Metallurgy and Metal Ceramics, 2021) Kyryliuk Y.S.; Maslyuk V.A.; Mamonova A.A.; Gripachevsky O.M.; Varchenko V.T.
The effect of TiB2 additions on the structure, phase composition, and mechanical and tribological properties of materials in the Fe–FKh800 system was studied. The introduction of titanium boride additions activated compaction of the iron-based composites through sintering with participation of the liquid phase that emerged with the formation of low-melting Fe–C–B (Tm ~ 1050°C) and γ-Fe–Fe2B–TiB2 (Tm ~ 1162) eutectics and led to a 50–70°C decrease in the sintering temperature of the compacts. Titanium boride additions between 0.38 to 0.74 wt.% provided 20–25% higher bending strength of the 65 wt.% Fe–35 wt.% FKh800 composite with a slight increase in hardness. Metallographic studies, X-ray diffraction, and electron microprobe analysis of the Fe–35 wt.% FKh800–TiB2 materials showed that titanium boride additions promoted a multiphase, microheterogeneous matrix-reinforced composite, consisting of Kh17 chromium steel, double M7C3 and M3C iron–chromium carbides, and complex Me3(CB) carboborides. The influence of TiB2 additions on the wear resistance of the composites subjected to dry friction against fixed diamond wheel particles and ShKh15 steel was studied. The study showed that the abrasive mass wear (Im) of carbide steels decreased from 36.94 to 14.8 mg/km and their linear wear (Il) decreased from 0.197 to 0.079 mm/km with TiB2 additions increasing from 0.38 to 1.48 wt.%. Titanium boride additions ranging from 0.38 to 2.2 wt.% reduced the mass wear rate from 4.9 to 1.9 mg/km in dry friction of the composite against a ShKh15 steel counterface with 50–55 HRC hardness and decreased the friction coefficient from 0.49 to 0.38.
Synthesis of Fe-Based Alloy Reinforced with Chromium Carbide Via Sintering of Iron- Ferrochrome Powder Mixture
(Powder Metallurgy Progress, 2021) Kyryliuk Yevheniia; Bagliuk Gennadii; Mamonova Alla; Maslyuk Vitaliy
The results of the investigation of the structure, phase composition, and properties of the alloy sintered from a mixture of iron (65 %) and high-carbon ferrochrome (35 %) powders are presented in the article. It was shown that sintering of the consolidated specimens results in a substantially heterogeneous structure consisting of two predominant phases: austenitic phase and double ferrochrome carbide. A mechanism is proposed for the dissolution of ferrochrome particles in the iron matrix as follows: M7C3 → M3C (1000÷1150 ºС) → M7C3 (1200÷1250 ºС).
Mathematical Modelling of Primary Recrystallization Kinetics and Precipitation of Carbonitride Particles in Steels. II. Recrystallization Kinetics
(Металофізика та новітні технології, 2021) Kaverinsky V. V.; Sukhenko Z. P.
A mathematical physical based semi-empirical model and a corresponding computer program are developed for describing recrystallization process and carbonitrides particles precipitation in deformed austenite. The model is suitable for alloyed steels of a wide range of compositions. The model allows calculating a thermodynamic equilibrium for carbonitride excess phases with solid solution, the kinetics of their nucleation and growth, and their effect on recovery and recrystallization. A detailed description is given for each aspect of the model and its physical nature. Verification of the simulation results with the experimental data taken from published sources confirms the sufficient reliability of the proposed computer model for evaluative calculations. The model’s features are demonstrated by an example that simulates influence of Nb content on recristallization, recovery and nucleation, growth and Ostwald ripping of Nb and Ti carbonitride particles. The simulation shows and numerically predicts the effect of slowing down recrystallization and recovery with increasing in Nb content. That attests significance of the effect of dispersed carbonitrides on recrystallization and recovery. The simulation theoretically predicts an intensification of Ti(C, N) particles precipitation and growth with an increase in the Nb concentration. As another result, it is an increasing the dispersion and number of Nb(C, N) particles with an increase in the Nb concentration owing to more rapid transition to the Ostwald ripening stage, which is characterized by much more slowly average particle size growth than from a supersaturated solid solution.
Mathematical Modelling of Primary Recrystallization Kinetics and Precipitation of Carbonitride Particles in Steels. I. Precipitation
(Металофізика та новітні технології, 2021) Kaverinsky V. V.; Sukhenko Z. P.
A mathematical physical-based semi-empirical model and a corresponding computer program are developed for describing recrystallization process and carbonitrides particles precipitation in deformed austenite. The model is suitable for alloyed steels of a wide range of compositions. The model allows calculate a thermodynamic equilibrium for excess carbonitride phases with solid solution, the kinetics of their nucleation and growth, and their effect on recovery and recrystallization. A detailed description is given for each aspect of the model and its physical nature. Verification of the simulation results with the experimental data from published sources confirms the sufficient reliability of the proposed computer model for evaluative calculations. The model’s features are demonstrated by an example that simulates influence of Nb content on recristallization, recovery and nucleation, growth and Ostwald ripening of Nb and Ti carbonitride particles. The simulation shows and allows numerically evaluate the effect of slowing down recrystallization and recovery with increasing in Nb content. This indicates a significant effect of dispersed carbonitrides on recrystallization and recovery. The simulation theoretically predicts an intensification of Ti(C, N) particles precipitation and growth with an increase in the Nb concentration. Another result is an increase of dispersion and number of Nb(C, N) particles with an increase in the Nb concentration owing to more rapid transition to the Ostwald ripening stage, which is characterized by much more slowly average particle size growth than from a supersaturated solid solution.
The Influence of Sintering Temperature and Content of High-Carbon Ferrochrome on the Structure and Properties of Iron–FKh800 Powder Composites
(Powder Metallurgy and Metal Ceramics, 2021) Maslyuk V.A.; Kyryliuk Y.S.; Bondar A.A.; Gripachevsky O.M.; Podoprygora M.I.
The influence of sintering temperature and content of high-carbon ferrochrome on the phase composition, structure, and mechanical properties of chromium carbide powder steels was studied. When sintering temperature changed from 1100 to 1250°C, the bulk shrinkage, density, porosity, hardness, and bending strength of the iron-based composites with high-carbon ferrochrome FKh800 varying from 25 to 40 wt.% increased nonmonotonically and their porosity decreased. The optimal sintering conditions were established for the Fe–(25–40 wt.%) FKh800 composites, and FKh800 content in the composition range under study was found to hardly influence the optimal sintering temperature of the composites. A vertical section was constructed by analytical/graphical method and demonstrated wide regions of two-phase (γ-Fe) + (Cr, Fe)7C3 and (α-Fe) + (Cr, Fe)7C3 equilibria. The constructed vertical section allowed the eutectic composition and eutectic formation temperature to be determined for the iron-based composites with FKh800, which were 73.7 wt.% Fe–26.3 wt.% FKh800 and 1285°C, and a tentative optimal sintering range to be found, which varied from 1100 to 1250°C. Electron microscopy studies of the carbide steels showed that their microstructure was heterogeneous and consisted of metallic and carbide phases and a number of pores. According to electron microprobe analysis and X-ray diffraction of the carbide steel, its metallic phase was close in composition to chromium steel Kh17 and its carbide phase corresponded to (Cr, Fe)7C3. The effect of 25–40 wt.% high-carbon ferrochrome on the mechanical properties of the composites was examined. When FKh800 content changed from 25 to 35 wt.%, the hardness and bending strength increased and fracture toughness decreased. The optimal combination of these mechanical properties was shown by the 65 wt.% Fe–35 wt.% FKh800 carbide steel.
Structure and Physicomechanical Properties of the Fe3Al Intermetallic Compound Obtained by Impact Hot Compaction
(Materials Science., 2021) Тоlochyn О. І.; Baglyuk G. А.; Tolochyna O. V.; Evych Ya. І.; Podrezov Yu. M.; Molchanovska H. M.
We study the influence of the conditions of impact compaction and heat treatment on the physicomechanical properties and structure of intermetallic compounds. We carried out the procedure of compaction by impact hot pressing of a Fe–14Al (wt.%) intermetallic compound prepared from iron and aluminum powders at temperatures of 1050 and 1150°C, as well as the procedure of annealing of compacted specimens at 1250°C for 60 min and at 1350 or 1450°C for 20 min. It is shown that the procedure of impact hot pressing makes it possible to obtain practically porousless specimens at temperatures of compaction equal to 1050°C and 1150°C. We managed to get high-quality contacts between intermetallic particles and to improve the mechanical properties as a result of annealing at a temperature of 1350°C.
The structure of composite rollers with iron or nickel-iron base and hard surface layer of WC or TiC based hard alloy produced by the method of hot vacuum pressing with a liquid phase
(Archives of Mechanical Technology and Materials, 2020) Kaverinskiy Vladislav; Sukhenko Zoya
In this work the structure and properties of composite rollers with surface layer made of hard alloy were studied. The rollers were made by the powder metallurgy method with sintering during pressing and the presence of a certain liquid phase during sintering (semi-liquid sintering). WC-Co and TiC-Ni-Fe materials were used as hard alloys. Iron-carbon and iron-nickel materials were used as soft base. All of the composite layers were formed in one process. The structure of base materials and border layer of these composites were studied. Investigations of thermocycling sustainability of these composite samples were carried out.
Formation of Crystal Structure in Hot Forging of Powder Carbon Steels
(Powder Metallurgy and Metal Ceramics, 2020) Mamonova A.A.; Bagliuk G.A.
The crystal structure acquired by powder steels produced from undoped iron powder and mixtures of iron with 1.0 or 1.5% graphite in hot forging was studied by X-ray diffraction and optical microscopy. The heating temperature of the samples to be forged was varied in the range 950–1150°C. The fundamentally different dependence of the lattice distortion on the heating temperature for forging of the outer and inner layers of the samples was found. The lattice imperfection increases with forging temperature in the outer layers of the hot-forged samples made of the undoped iron powder. The γ→α martensitic transformation occurs when the samples are heated above 1100°C and rapidly cooled down. The lattice imperfection decreases in the inner layers of the samples made of the undoped iron powder. In the case of carbon steel samples, the lattice distortion and hardness increase with heating temperature, reaching the maximum at 1100°C and thus characterizing the γ→α martensitic transformation. When temperature increases to 1150°C, the lattice imperfection reduces as carbon burns out more intensively at elevated temperatures, but the hardness and tensile strength decrease insignificantly. This is attributed to the quenching temperature of steel to form a ferritic cement mixture, whose structure is presented by sorbitol with a microhardness of 2700– 2900 MPa, troostite (3000 MPa), and bainite (4500 MPa).
The Structure and Phase Composition Acquired by Fe–Ti–Ni–C Alloys in Thermal Synthesis
(Powder Metallurgy and Metal Ceramics, 2020) G.A. Bagliuk; G.A. Maksimova; A.A. Mamonova; D.A. Goncharuk
The structure and phase composition of Fe–Ti–Ni–C alloys produced in situ by thermal synthesis at 1200ºC using TiH2, Fe, graphite, and Ni powder mixtures have been studied. The synthesized alloys represent a skeleton of titanium carbide grains of different stoichiometry, with sizes varying from 0.5 to 16 μm, surrounded by metal reinforcement layers. The starting mixtures without nickel or with 5% Ni have coarse TiC grains. When Ni content of the mixture increases to 10–20%, the maximum grain size sharply decreases to 6–7 μm. The microhardness of the synthesized alloys decreases when nickel amount in the mixture increases to 15% but becomes somewhat higher at 20% Ni. The phase composition of the alloys substantially depends on the amounts of starting mixture components and includes titanium carbide, Fe3C cementite, α-iron solid solution, and intermetallic FeNi3 (for iron containing mixtures) and Ni3Ti and Ni4Ti (for nickel-containing mixtures). When Ni content of the starting mixture increases to 10–20%, the lattice parameter and stoichiometry of TiCx slightly decrease and carbide particles noticeably refine. The thermally synthesized alloys have been ground to produce reinforced steel composite powders, which can find extensive application in depositing wear-resistant coatings and fabricating bulky parts by compaction followed by sintering, hot pressing, or hot forging.

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