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Ductility of Welded Joints in CK45 Carbon Steel Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 H. R. Ghazvinloo, A. Honarbakhsh-Raouf
The procedure of gas-metal arc welding (GMAW) has received much attention in recent years and has numerous beneficial applications in the industry, including car industry and ship building. It is expected that the GMAW parameters, such as arc voltage, welding current and welding speed, strongly affect the mechanical properties of welded joints. As one of the most important mechanical properties that
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Strain Hardening of Alloys of the W–Ni–Fe System by Cold High-Cycle Reduction Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 S. E. Sheikin, I. V. Andreev, V. V. Melnychenko, S. F. Studenets, Ya. V. Melnychenko, I. O. Hnatenko
We study the regularities of strain hardening and structural transformations of a tungsten–nickel–iron heavy alloy under the conditions of cold reduction. It is discovered that the alloy with a tungsten content of 89% is hardened easier than the alloy containing 90% W.
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Estimation of the Fatigue Strength of a Plate Traction Chain Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 J. Wang, P. S. Kun, T. M. Lenkovskyi, I. A. Vikovych, V. M. Boiko
We present the results of simulations of the stress-strain state of a traction chain by the finite-element method with regard for the contact interaction and friction between the chain link and the roller. We propose an analytic relation for the approximate evaluation of the fatigue strength of the chain according to the distribution of stresses. We also establish conditions that should be imposed
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Influence of Surface Nanostructuring on the Serviceability of SShKhN Cast-Iron Rolls Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 О. V. Maksymiv, V. І. Kyryliv, B. P. Chaikovskyi, Ya. B. Kyryliv, L. М. Hordiichuk, І. H. Yaroshovych
We study the wear resistance, fatigue strength, and corrosion-fatigue strength of SShKhN-42 rolls made of cast iron with surface nanostructures obtained as a result of mechanical-pulse treatment under the operational conditions of rolls of the rolling mills. It is shown that the surface nanostructure makes the wear resistance of cast iron three times higher and almost doubles the fatigue strength.
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Influence of Chromium on the Phase Composition and Specific Features of Hardening of the MnFeCoNiCu High-Entropy Alloy Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 О. M. Myslyvchenko, М. О. Krapivka, О. S. Tereshchenko, М. I. Filep
A six-component system of CoNiCuCrx high-entropy alloys with different contents of chromium (where x = 0, 0.5, 1.0, 2.0, and 3.0 mole) is obtained by the method of argon-arc melting in a МІFІ-9 study. By the methods of X-ray diffraction analysis, scanning-electron microscopy, and indentation, we investigate the influence of chromium on the crystalline structure, microstructure, and hardness of these
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Physicochemical Properties of Carbonitrided 40Kh Steel Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 M. S. Stechyshyn, V. P. Oleksandrenko, А. V. Martynyuk, М. М. Luk’yanyuk, М. Ya. Dovzhyk, V. О. Herasymenko
We present the results of investigations of the influence of hydrogen-free carbonitriding in glow discharge on the physicochemical characteristics of the hardened layer of 40Kh steel depending on the content of propane and the pressure of gas atmosphere. We consider three versions of saturation: carbon + nitrogen, nitrogen + carbon, and simultaneous saturation with nitrogen and carbon. The analysis
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Microstructure and Abrasive Wear Resistance of Deposited Materials of the Ni–Cr–B–Si System with Inclusions of Dispersed Phases Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 S. О. Luzan, А. S. Luzan
We study the microstructure of deposited coatings formed by a composite material based on PG-10N-01 self-fluxing alloy and modified with a mechanically activated composite material obtained as a result of the self-propagating high-temperature sintering process. By the X-ray phase diffraction analysis, in the structure of the coating, we detect the presence of titanium diboride (TiB2), nickel boride
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Corrosion Resistance of Steel of the Frames of Boom Sprayers Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 R. L. Leshchak, А. V. Babii, R. А. Barna, А. М. Syrotyuk
We perform the comparative analysis of the corrosion resistance of St3ps steel in demineralized water and in saturated solutions of the Nurelle-D insecticide and UN-32 complex liquid fertilizer. It is shown that, in demineralized water, the general corrosion of the steel surface is predominant. In a solution of insecticide, parallel with general corrosion, we observe a partial realization of pitting
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Elastoplastic Properties of Polylactide Composites with Finely Divided Fillers Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 А. S. Masyuk, Kh. V. Kysil, D. S. Katruk, V. I. Skorokhoda, L. M. Bilyi, Т. V. Humenetskyi
By using the modular-deformation method of calculations, we established the influence of finely divided filler (talc) and additional heat treatment on the elastoplastic properties of polylactide materials. We detected the changes in the modulus of deformation, elasticity modulus, and thermomechanical characteristics of polylactide composites. The maximum values of the moduli and melting point were
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Deformation of an Isotropic Plate with Periodic System of Curvilinear Holes and Plasticity Bands Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 V. S. Kravets, М. P. Savruk
By the method of singular integral equations, we solve a plane elastoplastic problem of fracture mechanics for an isotropic plane with an infinite series of curvilinear holes and plasticity bands at their tips. We study the influence of the shapes of smooth holes and the radii of rounding of the contours at their tips on the opening displacements and lengths of the plasticity bands. The solutions of
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Electrochemical Method for the Diagnostics of Degradation of Steels of Marine Portal Cranes Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 O. O. Nemchuk, O. I. Zvirko
We develop an electrochemical method aimed at the evaluation of in-service degradation of the mechanical properties of rolled steels of the frames of marine portal cranes. The regularities of decrease in the impact toughness of steels and their polarization resistance are analyzed. The correlation between these parameters forms a basis for the development of a nondestructive method aimed at prediction
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New Zr 3 M N x ( M = Co, Ni) Subnitrides: Theoretical Analyses, Crystal Structure, and Hydrogen-Sorption Properties Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 I. Yu. Zavalii, P. Ya. Lyutyi, I. V. Oshchapovskyi, I. V. Kovalchuk, V. V. Berezovets
The free energy and density of states are computed by the DFT method for the Zr3NiO and Zr3NiN compounds. Their formation was confirmed and numerous Zr3MNx (M = Co, Ni) compounds were synthesized for the first time. It is shown that all these compounds are insertion derivatives of the Re3B structural type (space group Cmcm). We study the process of gas-phase hydrogenation of the obtained subnitrides
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Structure and Corrosion of Quasicrystalline Cast Alloys and Al–Cu–Fe Film Coatings Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 S. I. Ryabtsev, V. A. Polonskyi, O. V. Sukhova
We study a quasicrystalline cast alloy and a film coating obtained by the improved method of threeelectrode ion-plasma sputtering of assembled targets with the following nominal composition: Al60Cu28Fe12 . The structure of the specimens was studied by the methods of quantitative metallography, X-ray diffraction analysis, X-ray energy-dispersive spectrometry, and transmission and scanning electron microscopies
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High-Temperature Salt Corrosion of a Heat-Resistant Nickel Alloy Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 Yu. H. Kvasnytska, L. М. Ivaskevych, О. І. Balytskyi, І. І. Maksyuta, H. P. Myalnitsa
We develop a heat-resistant corrosion-resistant alloy based on nickel and alloyed with rhenium and tantalum. This alloy is intended for the production of blades for a new generation of power-generating and ship gas-turbine engines. It is shown that the introduction of rhenium (3.7–4.3 wt.%) and tantalum (2.5–4.3 wt.%) into the composition of the experimental alloy increases the high-temperature corrosion
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Influence of the Corrosiveness of a Medium on the Ratio of the Cathodic Protection Current to the Ultimate Diffusion Current for KH70 Pipe Steel Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 L. І. Nyrkova, S. О. Osadchuk, А. V. Klymenko, А. О. Rybakov, S. L. Mel’nychuk, S. М. Prokopchuk
We study the dependence of the ratio of the cathodic protection current to the ultimate diffusion current for Kh70 steel within the range of protective polarization potentials (-0.75)–(-1.05) V (relative to the silver-chloride reference electrode) standardized by the DSTU 4219 in media with different degrees of corrosiveness. It is shown that, within the рН range 5.6–9.6, as the potential shifts to
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Computational Model for the Evaluation of the Service Life Of Fiber-Reinforced Concrete Structures Under Long-Term Static Loading Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 О. E. Andreikiv, I. Ya. Dolinska, O. К. Raiter
We propose a computational model for the evaluation of the service life of fiber-reinforced concrete structural elements subjected to long-term tension. The model is based on the first law of thermodynamics and a proposed idealized tensile stress-strain diagram of fibrous concrete. This model is used for the evaluation of the service life of a fiber-reinforced concrete plate containing a circular hole
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Influence of Partial Filling of the Gaps with Compressible Liquid on the Contact of Elastic Bodies with Wavy Surfaces Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 О. P. Kozachok
We study the problem of contact of two elastic half planes (plane deformation), one of which has a wavy surface under the conditions of partial filling of the interface gaps with compressible liquid. The formulated contact problem is reduced to a singular integral equation for the derivative of the height of the interface gaps and its analytic solution is obtained. We axnalyze the contact behavior
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Influence of Stresses on Structural Changes in Gray Cast Iron Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 T. S. Skoblo, O. I. Sidashenko, O. V. Saichuk, O. Yu. Klochko, D. A. Levkin
According to the results of simulation of stressed states, it is shown that coarse graphite inclusions formed in the walls of case-shaped parts of transient in thickness are the sites of initiation of defects due to the changes in the dislocation structure and diffusion of carbon from graphite. The cavities formed in graphite also promote the development of oxidation.
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Detection of Microdefects on the Surfaces of Corroded Steel Pipes Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 P. O. Maruschak, Ya. V. Lytvynenko, V. O. Dzyura, R. T. Bishchak, M. S. Polutrenko
The micromechanisms of biocorrosion damage to specimens of 17G1S-U pipe steel are studied on the basis of a combination of the profilometry approaches with fracture mechanics. We develop new methods for the numerical analysis of stress concentration factors regarded as parameters of localization of the microscopic concentrators of corrosion stresses. The improved approach is applied to the analysis
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Relationship Between the Parameters of Acoustic Structural Noise and the Mechanical Properties of Structural Steels Mater. Sci. (IF 0.748) Pub Date : 2020-12-03 V. D. Myndyuk, N. I. Chaban, I. V. Rybitskyi, O. M. Karpash
We perform the comparative analysis of the parameters of acoustic structural noise in specimens of 40G structural steel with the use of ultrasonic flaw detectors with phased arrays. It is shown that the parameter of integral density of B-scan images most completely reproduces the variations of energy of acoustic vibrations reflected from the microstructural inhomogeneities (grain-size inhomogeneity
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Determination of the Maximal Temperature of a Pad–Disk Tribosystem during One-Time Braking Mater. Sci. (IF 0.748) Pub Date : 2020-12-02 О. Evtushenko, M. Kuciej, K. Topczewsка
We propose a computational scheme for the evaluation of the maximal temperature of a pad–disk tribosystem in the course of one-time braking with regard for the time of increase in pressure up to its nominal level, the temperature dependence of the characteristics of materials, and the roughness of the friction surfaces. We perform calculations for a three-disk brake made of Termar-ADF carbon composite
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Influence of the Working Media and Maneuvering Loading Mode on the Service Life of Spraying Booms of Field Sprinklers Mater. Sci. (IF 0.748) Pub Date : 2020-12-02 О. E. Andreikiv, А. V. Babii, І. Ya. Dolinska
We propose a method for the determination of the residual service life of wide-coverage spraying booms of field sprinklers with regard for the maneuvering mode of their loading and the action of corrosive media. This method is based on the energy approach developed earlier, the computational models of propagation of corrosion cracks under static and cyclic loads, and the scheme of the maneuvering loading
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Methods for the Determination of the Stress-Strain State of a Metal Under the Action of Gaseous Hydrogen and Temperature Mater. Sci. (IF 0.748) Pub Date : 2020-12-02 Ya. L. Ivanytskyi, V. М. Boiko, V. Z. Stankevych, B. K. Hanulich
We propose a procedure for the determination of the stress-strain state of exploited metals in gaseous hydrogen at temperature varying as a function of time. In this case, we use the principle of virtual work adapted for the quasistatic equilibrium equations with step-by-step formulation in time. The increments of displacements, hydrogen concentration, temperature, strains, and stresses for a certain
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Stressed State of an Orthotropic Plane with Two-Section Kinked Crack Under Antiplane Deformation Mater. Sci. (IF 0.748) Pub Date : 2020-12-02 M. P. Savruk, L. I. Onyshko, O. I. Kvasnyuk, N. M. Bida
The method of singular integral equations is used to obtain the solution of the antiplane problem of fracture mechanics for an orthotropic plane with two-section kinked crack with regard for the specific features of stresses at the tips of angular cracks. For this purpose, we apply the unified approach developed earlier to the solution of the problems of stress concentration in isotropic bodies with
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Influence of Alloying with Chromium and Vanadium Carbides on the Corrosion and Tribocorrosion Characteristics of Hard Alloys of the WC–Ni System Mater. Sci. (IF 0.748) Pub Date : 2020-12-01 V. І. Pokhmurskyi, Kh. B. Vasyliv, V. P. Bondarenko, V. А. Vynar, N. B. Ratska, О. М. Baranovskyi
We study the corrosion and tribocorrosion behaviors of hard alloys of the VN20 + Cr3C2 and VN20 + VC systems in solutions based on 3% NaCl with different рН values. In alkali media, the corrosion currents and friction coefficients are lower than in acid media, which is explained by the inertness of nickel. The VN20 + 1 wt.% Cr3C2 alloy has the highest corrosion and tribocorrosion characteristics.
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Influence of Titanium-Containing Inoculants on the Structure of Metal in the Welds of High-Strength Low-Alloy Steels Mater. Sci. (IF 0.748) Pub Date : 2020-12-01 G. M. Grigorenko, L. I. Markashova, V. V. Golovko, E. N. Berdnikov, T. A. Alekseenko, V. V. Zhukov
We study the influence of titanium-containing refractory inoculants (nitrides, carbides, and intermetallic materials) on the structure of metal in the welds of high-strength low-alloy steels. The character of structural-and-phase transformations and the specific features of fine structures are determined by the method of transmission electronic microscopy with regard for the dislocation density distribution
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Structure and Physicomechanical Properties of Cast Titanium Alloys of the Ti−Nb−Mo System Mater. Sci. (IF 0.748) Pub Date : 2020-12-01 О. М. Мyslyvchenko, A. А. Bondar, V. F. Horban, Yu. F. Luhovskyi, V. B. Sobolev, I. B. Tikhonova
Ternary alloys of the Ti–Nb–Mo system are obtained by the method of arc remelting with subsequent crystallization on a copper water-cooled hearth. In these alloys characterized by contents of alloying elements corresponding to the molybdenum equivalent (Moeqv) within the range 3.2–4.0, we observe the formation of hexagonal (α′) and orthorhombic (α′′ ) martensites. For higher Moeqv (4.6), we detect
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Pulsed Discharge Preparation of a Modifier of Ti–TiC System and its Influence on the Structure and Properties of the Metal Mater. Sci. (IF 0.748) Pub Date : 2020-12-01 О. М. Syzonenko, S. V. Prokhorenko, E. V. Lypyan, A. D. Zaichenko, M. S. Prystash, A. S. Тоrpakov, M. О. Pashchyn, R. Voinarovska-Novak, E. Sherehii
It is shown that the addition of 0.01 wt.% of Ti–TiC modifier synthesized by the method of high-voltage electric discharge treatment of Ti powders in kerosene and briquetted with the help of spark plasma sintering makes it possible to reduce the grain size from 1–2 mm to 0.2–0.6 mm in all modified specimens of SM88U heat-resistant alloy. In this case, the tensile strength of modified specimens at a
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Complex Diagnostics of the State of Operated Elements of a Grab Reloader Mater. Sci. (IF 0.748) Pub Date : 2020-12-01 P. О. Semenov, V. М. Pustovyi
We perform complex diagnostics of the technical state of steel structure of a grab reloader after operation for more than 40 yr by the methods of destructive and nondestructive testing. Fatigue cracks and mechanical defects caused by wear are detected on the shaped rolled products. By using the magnetic method with determination of the coercive force, we analyze the stress-strain states of various
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Evaluation of the Influence of Dispersion of Pearlite on the Fatigue of Carbon Steel Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 Kh. А. Askerov, І. О. Vakulenko
It is shown that the slope of a tangent to the fatigue curve can be used to analyze the effect of dispersion of pearlite on the fatigue strength of carbon steel. For a constant thickness of the ferrite-pearlite layer, we established an inversely proportional relationship between the indicated parameter and the density of accumulated dislocations. We also estimated the mechanism of influence of the
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Corrosion Cracking of Kh70 Pipe Steel under the Conditions of Cathodic Protection Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 L. I. Nyrkova
We study the mechanism of corrosion cracking of Kh70 steel in a neutral soil electrolyte under the conditions of cathodic protection. We distinguished three areas of potentials in which the processes of corrosion cracking of steel are governed by different mechanisms. Thus, the process of local anodic dissolution proves to be predominant under potentials more positive than – 0.75 V, the mechanism of
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Modeling of Cold Plastic Deformation of the Holes Made in Specimens of Shape-Memory Alloy Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 P. V. Yasnii, O. V. Dyvdyk, V. P. Iasnii
The process of cold plastic deformation of a hole in a plate made of shape-memory alloy is simulated by the finite-element method by setting the mechanical characteristics and the temperatures of the onset and termination of direct and reverse phase transformations. By using the ANSYS Workbench software, we determine the distribution of residual stresses in the plate in the vicinity of a functional
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Corrosion-Fatigue Crack Propagation in Exploited Sucker Rods Made of 20N2M Steel Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 N. V. Kret, L. M. Svirska, T. P. Venhrynyuk
We analyze the influence of model stratal water with low acidity on the cyclic crack resistance of 20N2M steel of a sucker rod after operation for 5.5 yr. The state of the metal of a sucker rod head is conventionally regarded as the reference state. We revealed insignificant differences between the basic mechanical properties and the characteristics of cyclic crack-growth resistance of steel in air
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Influence of Thermomechanical Treatment on the Properties of Alloys of the Mg–Al–Zn–Mn System Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 Kh. Kug, Sh. S. M. Khalifa
Magnesium alloys are subjected, after low-pressure casting, to hot-rolling and extrusion. It is shown that their structural states, for different rates of these processes, are determined by the joint development of dynamic recrystallization, formation of twins, and changes in the phase composition. It is demonstrated that the dissolution of metastable phase components and the corresponding decrease
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Propagation of a Fatigue Crack on the Surface of Side Frame of a Freight Bogie under Irregular Operating Loads Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 D. V. Rudavskyi, М. S. Shefer, Yu. І. Kanyuk
We study the kinetics of propagation of fatigue cracks on the surface of side frame of a rail car with regard for the stochastic nature of the operating load. Its dependence on the initial geometry of the crack is established. Moreover, under given loading conditions, we determine the shape of semielliptic contour of the fatigue crack characterized by the highest growth rate into the depth of the frame
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Mechanical Strength of the Weld Metal in CK45 Carbon Steel Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 H. R. Ghazvinloo, A. Honarbakhsh-Raouf
The procedure of gas-metal arc welding (GMAW) has received much attention in recent years and has numerous beneficial applications in the industry. The arc voltage, welding current and welding speed are three independent variables of this process that may affect the mechanical properties of the weld metal. As one of the most important mechanical properties of the weld metal, we can mention its yield
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Determination of the Specific Fracture Energy of the Material under Shear Deformation Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 R. О. Shyshkovskyi
We present a procedure for the evaluation of the strain and fracture energy of the material under the conditions of shear deformation based on the application of the method of digital image correlation. The established characteristics are used to determine the stress-strain state and service life of drill columns and shafts of hydraulic turbine in bending and torsion.
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Protective Properties of Alkyd Coatings Inhibited by Complex Zeolite-Phosphate Pigment Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 I. M. Zin, S. A. Kornii, A. R. Kytsya, L. M. Bilyi, M.-O. M. Danylyak, P. Ya. Lyutyi
We study a complex anticorrosion pigment based on calcium-containing zeolite with zinc phosphate precipitated on its nanoporous surface. It is discovered that this pigment efficiently retards corrosion in an aluminum alloy placed in a synthetic acid medium and inhibits the subfilm corrosion of the metal near defects of the alkyd paint coating. The proposed pigment may serve as a promising inhibiting
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Impact Toughness of Welded Joints on 34KhN2MA Steel Produced from Electrodes with Various Phase Compositions Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 A. R. Dzyubyk
We determine the brittle-fracture resistance of the metal taken from various zones of welded joints of 34KhN3MA steel produced from electrodes with different phase compositions or their combinations. It is shown that, regardless of the zone of welded joint in which a notch is made in the specimen, the highest values of impact toughness are observed for the weld metal obtained from the austenitic electrode
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Express Method for the Evaluation of the Frost Resistance of Silicate Building Materials Mater. Sci. (IF 0.748) Pub Date : 2020-11-29 S. V. Piddubnyi, H. О. Tatarchenko, V. М. Sokolenko
We analyze the existing ordinary and express methods aimed at the determination of the frost resistance of building materials and demonstrate their advantages and disadvantages. We propose a new express method, which enables us to determine the durability of stone with the smallest labor consumption and high efficiency. This method is based on the introduced criterion of frost resistance computed according
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Partial Opening of a Semiinfinite Crack on the Boundary of an Elastic Strip and a Rigid Wall Mater. Sci. (IF 0.748) Pub Date : 2020-11-27 V. І. Ostryk
We study the problems of compression and shear of an elastic strip containing a semiinfinite crack on the boundary of the strip and a rigid wall. The crack is opened in the middle and closed at the ends, where its faces are under the conditions of friction sliding. By the Wiener–Hopf method, we reduce the system of integral equations of the problem to an infinite system of algebraic equations. The
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Transverse Vibration of an Orthotropic Plate with Holes and Inclusions Mater. Sci. (IF 0.748) Pub Date : 2020-11-26 T. V. Shopa
Within the framework of the refined theory taking into account the transverse shear strains and inertial components, we consider the problem of stationary vibration of an orthotropic plate with holes and absolutely rigid inclusions. The inclusions may have different types of bonds with the plate. We analyze the case of translational motion of the inclusions along the direction of normal to the median
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Hydrogen Generation by the Hydrolysis of MgH 2 Mater. Sci. (IF 0.748) Pub Date : 2020-11-25 Yu. V. Verbovytskyy, V. V. Berezovets, A. R. Kytsya, I. Yu. Zavaliy, V. A. Yartys
Magnesium hydride (MgH2) is a hydrogen-rich compound generating significant amounts of hydrogen in the process of hydrolysis, i.e., in the course of its chemical interaction with water or with aqueous solutions. This process is of great interest for the on-site hydrogen generation aimed at application of H2 as a fuel for PEM fuel cells. We propose a review of recent reference publications in the field
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Influence of the Composition of Electrolytes on the Properties of Plasma-Electrolytic Oxide Coatings on Light Alloys Mater. Sci. (IF 0.748) Pub Date : 2020-11-25 H. V. Chumalo, V. M. Posuvailo, E. V. Kharchenko, V. M. Palyukh
We study the effect of various electrolytes on the functional characteristics of the coatings deposited by the method of plasma-electrolyte oxidation (PEO) on aluminum and magnesium alloys. The influence of the concentration of alkali on the formation of PEO coatings is demonstrated. The prospects of application of KOH (NaOH)–Na2SiO3 combined electrolytes with various additives (glycerin, borax, fluorides
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Stressed State of a Viscoelastic Layer on the Rigid Foundation Under the Action of Concentrated Cyclic Loads Mater. Sci. (IF 0.748) Pub Date : 2020-11-25 І. S. Skorodyns’kyi, О. V. Maksymuk
By using a generalized two-parameter model, we study main regularities of the deformation of an infinite viscoelastic layer on the rigid foundation under the action of concentrated cyclic loads. The process of transition to the steady-state conditions of deformation under periodic nonharmonic loading is simulated. The possibility of taking into account residual strains (displacements) in a layer made
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Selection of the Composition of a Multicomponent Alloy of the Nb–Ti–Al–X System with High-Temperature Strength, Heat Resistance, and Technological Efficiency Mater. Sci. (IF 0.748) Pub Date : 2020-11-20 M. P. Brodnikovs’kyi, T. L. Kuznetsova, O. A. Rokytska, Yu. Yu. Zubets
We establish the physicochemical conditions required for the creation of multicomponent Nb–Ti–Al–X (X – Cr, Zr, Mo, Sr) niobium alloys with improved characteristics of high-temperature strength, heat resistance, and technological efficiency. The conclusions are based on the relationship between the physical properties of alloying elements, enthalpy of mixing, compositions of alloys, and the diagrams
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Influence of the Working Media of Fuel Cells on the Structure and Physicomechanical Characteristics of Ceramics of the ZrO 2 –Y 2 O 3 –NiO System Mater. Sci. (IF 0.748) Pub Date : 2020-11-20 B. D. Vasyliv, V. Ya. Podhurska, O. P. Ostash, I. O. Polishko, E. M. Brodnikovs’kyi, S. E. Ivanchenko, O. D. Vasyl’ev
We study the properties of ZrO2 –Y2O3 –NiO ceramics obtained by using the technologies of sintering of powders and tape casting in the intact state and after one-time reduction both in pure hydrogen and in Ar–5% H2 and N2 –10% H2 –5% CO2 mixtures. It is demonstrated that, by using the technology of tape casting, it is possible to obtain materials for anodes-substrates of solid-oxide fuel cells with
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Specific Features of Saturation with Deuterium of Vacuum-Arc Coatings Based on Iron Mater. Sci. (IF 0.748) Pub Date : 2020-11-20 H. D. Tolstolutska, V. V. Ruzhytskyi, I. E. Kopanets, O. S. Kuprin, V. М. Voevodin, V. А. Bilous, V. L. Vasylenko
We study the accumulation of deuterium in coatings made of FeCrAl alloys and stainless steel, as well as (for comparison) in the Zr1%Nb alloy under the conditions of their saturation with a hydrogen isotope (deuterium) from a gaseous medium. By the method of nuclear reactions, we measure the space distribution of the concentration of deuterium in the coatings after their saturation at a temperature
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Plastic Exfoliation of a Periodic System of Thin Near-Boundary Inclusions Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 V. А. Kryven, А. R. Boiko, V. B. Valyashek, L. І. Tsymbalyuk
We obtain a numerical-analytic solution of an antiplane problem of the stress-strain state of elastoplastic half space containing a periodic system of thin rigid tunnel inclusions parallel to the boundary of the half space. Prior to loading, these inclusions were in unilateral mechanical contact with the medium. We determine the stress-strain state and study the phenomenon of plastic exfoliation of
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Friction Behavior of Electric-Spark Coatings Under the Conditions of Boundary Lubrication Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 V. М. Holubets, V. М. Dovhunyk, M. І. Pashechko, S. А. Kornii, Yu. S. Shpulyar
We study the friction characteristics of “disk–shoe (segment)” friction couples of 45 steel with applied electric-spark coatings. Their wear resistance under the conditions of boundary lubrication and the morphology of the surface layers or secondary structures formed on the counterbody in the course of friction are analyzed.
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Cyclic Corrosion Crack Resistance of an Exploited Welded Joint of 17G1S Pipe Steel Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 V. A. Voloshyn
We analyze the influence of numerous factors, such as an NS4 model soil medium, the load ratio (R = 0.1 and 0.9), and the potential of cathodic protection (–0.98 V) on the cyclic crack-growth resistance of the base metal and the metal of circular butt weld of 17G1S pipe steel in the intact state and after 30 years of the operation in a gas main. It is shown that the long-term operation of steel maximizes
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Influence of the Ambient Medium in the Course of Laser Treatment on the Resistance of Titanium to Hydrogen Embrittlement Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 T. V. Pryadko, V. A. Dekhtyarenko, A. A. Shkola
We study the kinetic parameters of the physicochemical interaction of hydrogen with annealed titanium and titanium whose surface layers are modified by laser treatment and differ, in their phase and chemical compositions, from the volume of the material. The possibilities of attainment of the maximum degree of protection of the material against hydrogen penetration and prevention of the possibility
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Elevation of the Fatigue Strength of Pump Rods as a Result of Treatment with a Special Medium Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 B. V. Kopei, O. I. Zvirko, T. P. Venhrynyuk, Z. V. Slobodyan, I. P. Shtoiko
We analyze the causes of the in-service loss of integrity of the steel rods of pumps due to the fatigue fracture of their main part as a result of propagation of the surface cracks. To increase the service life of the rods, it is proposed to use a special liquid working medium inhibiting the process of propagation of fatigue cracks as a result of the artificial creation of the effect of crack closure
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Structure and Properties of Bimetallic Centrifugally Cast Milling Rollers Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 Zh. Zheng, A. P. Shatrava, V. P. Likhoshva, O. A. Pelikan, K. Zheng
We propose a way to increase the wear and crack resistance of the main working tools for roller mills. Bimetallic rollers (with a diameter of 252 mm and a length of 1620 mm) are produced by sequential pouring of alloys with similar temperatures of phase transformations. The microstructure, phase composition, redistribution of alloying elements, and the properties of bimetallic materials are studied
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Determination of the Residual Life of the Spraying Boom of a Field Sprinkler in the Maneuvering Loading Mode Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 O. E. Andreikiv, A. V. Babii, I. Ya. Dolinska, Yu. Ya. Matviiv
We propose a computational model for the evaluation of the residual service life of spraying booms of the field sprinklers in the maneuvering loading mode (stationary oscillations of sections of the boom together and separate shocks caused by the irregularities of the field surface). This model is based on the energy approach earlier developed by the authors. A scheme of maneuvering load is proposed
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Mathematical Modeling of the Influence of Hydrogen on the Corrosion Activity of Metal Structures Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 W.-G. Song, O. V. Hembara, Ya. I. Sapuzhak
On the basis of the well-known theoretical concepts and some experimentally substantiated hypotheses, we propose a mathematical model aimed at description of the effect of diffusion-mobile hydrogen on the corrosion of pipe materials of crucial metal structures. The influence of hydrogenation of the metal on the corrosion rate of heat-exchange equipment is quantitatively evaluated.
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Wear Kinetics of Steels with Diffusion Coatings in Rolling Friction Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 P. V. Kaplun, V. A. Honchar, T. V. Donchenko
It is shown that the wear kinetics of steels with diffusion coatings under the conditions of rolling friction strongly depends on the physicomechanical properties and phase compositions of the coatings, hardness of the base, and the modes of thermal and thermochemical treatments. The dependence of the degree of wear on the number of loading cycles is always parabolic. The contact fatigue strength in
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Optimization of the Modes of Heat Treatment of Structural Elements Made of Functionally Graded Materials Mater. Sci. (IF 0.748) Pub Date : 2020-11-19 M. H. Stashchuk, E. M. Irza
We propose a procedure of control over the speed of response of thermal conditions in the case of thermal loading of the bodies of revolution made of functionally graded materials. The construction of solutions of the analyzed problems is based on numerical methods. To solve direct problems, we use the method of weighed residuals and the finite-element method. The solution of the posed extreme problem
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Stressed State of a Plane with Periodic System of Closely Located Curvilinear Holes with Edge Cracks Mater. Sci. (IF 0.748) Pub Date : 2020-10-13 V. S. Kravets’
A plane periodic problem of the theory of elasticity for an isotropic plane with infinite row of closely located curvilinear holes with edge cracks is solved by the method of singular integral equations. The stress intensity factors (SIF) at the tips of edge cracks propagating from symmetric holes of various shapes (elliptic holes, rhombic holes with rounded vertices, and narrow slots) are computed
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Healing of Cracks in Anisotropic Bodies Mater. Sci. (IF 0.748) Pub Date : 2020-10-12 V. P. Sylovanyuk, N. A. Ivantyshyn
We obtain the solution of a plane problem of the theory of elasticity on the phenomenon of “healing” of a crack in an anisotropic body. By using the model of Winkler’s base, this problem is reduced to a singular integrodifferential equation for the displacements of points of the crack surface. In the case of a defect in the form of flattened ellipse, we obtain the exact analytic solution of the problem
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