We analyze the characteristics of in-service degradation of structural steels under the conditions of cyclic loading and take into account that the process of degradation of steels has two stages. In the first stage, cyclic strain hardening is predominant. The second stage can be described as the intense development of microdefects dispersed in the bulk of the metal. We distinguish the influence of in-service cyclic loading on the complex of basic mechanical properties of steels important for their serviceability and on a broad range of the characteristics of fatigue strength. In the first case, these are the characteristics of brittle-fracture resistance and, in particular, impact toughness and crack resistance. In the second case, we deal with fatigue-fracture resistance. The indicated characteristics are determined for smooth specimens and specimens with cracks. We analyze the influence of corrosive hydrogenating media on the intensity of in-service degradation of steels under cyclic loading.

The structure of as-cast quasicrystalline Al65Co20Cu15, Al72Co18Ni10, and Al72Ni23Fe5 alloys and their corrosion properties in acid media are investigated. We study the structure by the methods of quantitative metallography, X-ray diffraction analysis, scanning electron microscopy, and electron-probe microanalysis and investigate the corrosion resistance in aqueous solutions of HCl, H2SO4, HNO3 and H3PO4 acids (рН 1) by the gravimetric method. We reveal the formation of a quasicrystalline decagonal D-phase, which coexists with Al4(Co, Cu)3 and Al3(Cu, Co)2 phases in the Al65Co20Cu15 alloy, with the Al9(Co1–xNix)2 phase in the Al72Co18Ni10 alloy, and with Al13(Fe,Ni)4, Al3(Ni, Fe)2, and Al3(Ni, Fe) phases in the Al72Ni23Fe5 alloy. The Al72Ni23Fe5 and Al65Co20Cu15 alloys exhibit the highest corrosion resistance in solutions of nitric acid, the Al72Ni23Fe5 and Al72Co18Ni10 alloys are most corrosion-resistant in solutions of hydrochloric and orthophosphoric acids, and the Al65Co20Cu15 alloy exhibits the highest corrosion resistance in sulfuric acid. In most of the analyzed acids, the surface of samples dissolves relatively uniformly, except the areas with more defective structures, which dissolve at higher rates.

We study the fatigue life and microstructure of railway axles with certain specific features of macrostructure detected with the help of ultrasonic testing (axle No. 178) and without these features (axle No. 143) of EA1N grade produced according to the EN 13261:2020 standard. We perform the comparative analysis of the corresponding samples taken near the surface at a distance of a half of radius and in the central part of the analyzed railway axles. It is shown that the fatigue life of the metal in the surface layer of the investigated axles is higher than for the metal at a depth of one half of radius of the axles and in its central part. Moreover, the difference between the detected values over the cross section of the axles with defects does not exceed 10%, whereas for the axle without defects the value of fatigue life of the metal near the surface is almost five times greater than for the samples cut out from the central part. According to the results of microstructural and fractographic analyses, we establish the direct dependence between the initiation of fatigue cracks and the size and number of nonmetallic inclusions and micropores formed in steel and its structural inhomogeneity.

We study the kinetic characteristics of nitriding of thin-sheet (~ 1 mm) samples of Zr–1% Nb alloy treated in a nitrogen atmosphere (\( {P}_{{\textrm{N}}_2}={10}^5\textrm{Pa} \)) in broad temperature (T = 550; 650; 750; 850 and 950°С) and time (τ = 1; 5 and 10 h) ranges. It is shown that the process of nitriding of the analyzed alloy obeys a law close to a parabolic dependence (n ≈ 2). It is discovered that the activation energy of nitriding of the alloy within the temperature range 550–950°C is equal to 131.8 kJ/mole. The microstructure of the subsurface layer of the alloy after nitriding is analyzed. The distribution of the surface microhardness of Zr–1% Nb alloy is determined. The diagrams of intensity of the phase reflexes of α-Zr and ZrN on the surface of alloy after treatment in a nitrogen atmosphere are constructed.

The process of single crystals plastic deformation at the atomic level according to the previously proposed discrete model is described. The single crystals are considered as a two-phase structure, consisting of surface layers and inner regions of a perfect crystalline lattice. The effect of surface on the strength of single crystals of perfect structure is analyzed. As the proportion of the surface layer in the total volume of thick single crystals is small, this influence is insignificant. Increase of the number of defects after plastic deformation significantly increases the crystal strength. On the other hand, because of the small size of whisker crystals, the surface is of significant influence. It is concluded that the mechanisms of plastic deformation at the atomic level are the same for both thin and thick crystals, despite the differences in their stress-strain diagrams.

It is shown that the corrosion rate of Q125 steel in model stratal water (MSW) saturated with carbon dioxide increases with time, which reveals the absence of protective effect in the course of formation of carbonate films. For t = 60°C and \({P}_{{\mathrm{CO}}_{2}}\) = 6 MPa, corrosion is accelerated and transforms from uniform corrosion into pitting corrosion. The corrosion rate of steel in the course of short-term tests in MSW + CO2 + H2S is proportional to the concentration of H2S in the solution and determined by the rate of the cathodic process. The mechanism of corrosion is independent of the concentration of hydrogen sulfide in the solution. In the long-term studies carried out in MSW + CO2 + H2S, the corrosion rate of Q125 steel becomes ∼ 2 times lower than in the case of carbon-dioxide corrosion in MSW + CO2 under normal conditions and 10–15 time lower for t = 60°C and \({P}_{{\mathrm{CO}}_{2}}\) = 6 MPa as a result of the formation of surface films consisting of a mixture of mackinawite, troilite, and impurities of iron oxides and hydroxides. The adhesion of sulfides is stronger than the adhesion of carbonates, which promotes a decrease in the corrosion rate. However, in view of the presence of porosity, the protective properties of sulfides are insufficiently high.

We compare the phase compositions of two test steels of grades K and K+ (with additional complex alloying with aluminum, nitrogen and titanium) and the well-known steel of grade 2 used as a material for railroad wheels. Complex alloying of steels with aluminum, titanium, and nitrogen leads to the formation (after crystallization) of a finer grain structure with elevated volume fraction of pearlite. It is shown that the procedure of additional alloying after crystallization leads to the formation of multilayer inclusions, oxides, nitrides and carbonitrides located on the grain boundaries and in the bulk of the pearlite grains. Hot plastic deformation makes it possible to lower the volume fraction and the sizes of oxides. After tempering, titanium nitrides and carbonitrides remain in the structure of steel. The application of complex alloying of K+ and K steels leads to the improvement of the characteristics of plasticity, strength, and hardness as compared with the properties of steel of grade 2.

Corrosion behavior of matte and bright galvanic nickel coatings in solutions and vapor of acetic acid are studied. Corrosion of the corresponding materials in the studied media occurs with oxygen depolarization. The rate of anodic dissolution of bright nickel deposits in acetic acid solutions is higher than that of matte ones, due to the effect of sulfur on the continuity of the passive film on bright nickel deposits and their ability to passivation. Based on EDX and XRD studies, the formation of corrosion products on the surface of bright nickel deposits in the form of nickel acetate and a film of nickel sulfides of variable stoichiometric composition during the exposure in acetic acid solutions and vapor are shown. The stoichiometric composition of sulfide corrosion products changes with increasing sulfur content from Ni3S2 to Ni3S4 under prolonged exposure of the studied bright nickel deposits in vapor or solutions of acetic acid.

The method for locating hidden subsurface non-metallic pipelines made of high-molecular compounds (polyethylene, polystyrene, PVC, polypropylene) is proposed. It is based on the self-reactance properties of liquids in pipelines, which become apparent under the forced polarization of liquid by turning the magnetic axis of their protons at some angle in relation to the Earth’s magnetic field. The precession of the liquid proton axis in the direction to the Earth’s magnetic field appears after the end of the polarization pulse action. It results in the appearance of the variable magnetic field of free nuclear precession with Larmor frequency thus testifying to the location of subsurface pipeline with liquid. Proton precession time depends on the liquid and serves as a sign for recognition of the liquid type in a pipeline.

The tribological characteristics of oxide layers synthesized by plasma electrolytic oxidation (PEO) in a weakly alkaline electrolyte in the pulsed cathodic-anodic mode on plasma Al–Ti–Cu coatings sprayed on a D16 aluminum alloy substrate are investigated. It is established that in the PEO layer–steel ball friction pair the highest wear resistance is provided by selective transfer conditioned by the presence of copper in the layer structure, and in the PEO layer–ceramic ball friction pair by the presence of high-strength Al2TiO5 phase.

The influence of the nature of corrosive media on the corrosion resistance of the Fe78.5Ni1.0Mo0.5Si14.0B6.0 amorphous ribbon metal alloy is investigated by using different electrochemical methods. We determine the electrochemical characteristics of the alloy in 0.5 M aqueous solutions of NaCl, HCl, KOH, and H2SO4 at T = (293 ± 1)°K. It is shown that the corrosion resistance of the amorphous material strongly depends on the component composition of corrosive media. We observe the formation of dense passivation layers on the surfaces of Fe78.5Ni1.0Mo0.5Si14.0B6.0 alloy in alkaline solutions.

The morphology of relief formations on the surface of a titanium alloy treated with a femtosecond laser pulse for cyclicity has been evaluated. An assumption is introduced about the presence of a segmentcyclic structure, which has a spatial repeatability formed by segment-cycles. In addition to the segment structure, a rhythmic structure with an constant or variable rhythm is also considered based on a mathematical model of a cyclic random process (stochastic case). A method has been developed for checking the cyclicity of the formed relief formations, which makes it possible to evaluate the morphology of the resulting surface and its statistical characteristics.

We study the influence of hydrogen-sulfide concentration (0–1500 mg/dm3 ) in chloride-acetate solutions on the corrosion processes, hydrogenation, and corrosion-mechanical wear of 07Kh16N6 steel. It is shown that, independently of its content, the corrosion resistance of steel in these solutions is much lower than in the medium without hydrogen sulfide in which it is passivated. On the steel surface, we observe the appearance of corrosion products in the form of oxide-sulfide compounds whose thickness increases with the hydrogen-sulfide concentration. Their upper layer loses its continuity at a concentration of 1500 mg/dm3 . The tribocorrosion characteristics of steel for hydrogen-sulfide concentrations of 100 and 500 mg/dm3 do not undergo substantial changes. At the same time, for 1000 and 1500 mg/dm3 , they decrease by ∼ 30%. The corrosion processes determine the corrosion-mechanical wear of steel in media with different contents of hydrogen sulfide, which is connected with hydrogenation of the surface layers and intense restoration of homogeneous oxide-sulfide films on the surface of friction paths in the case of friction contact.

We study the protective properties of a composite anticorrosion pigment based on synthetic zeolite and monocalcium phosphate and obtained by the method of mechanochemical synthesis on the surface of 09G2S low-alloy carbon steel. It is shown that, as a result of mechanical dispersion of the pigment in a ball mill for 1 h with a rotational speed of the milling cylinder equal to 200 rpm, the crystal structure of zeolite is preserved with partial formation of the amorphous component. On the basis of the results of X-ray phase diffraction analyses, it is suggested that, in the course of synthesis, phosphates are intercalated into the nanopores of zeolite. The corrosion resistance of 09G2S steel in a 0.1% NaCl solution and in the extracts of synthesized zeolites with different compositions was investigated by the methods of potentiodynamic polarization and impedance spectroscopy. It is shown that the synthesized pigment exerts an inhibitory effect on the corrosion of steel, and its anticorrosion efficiency is maximum if the mass ratio of zeolite and phosphate components is equal to 1 : 3. The formation of protective film on the steel surface after holding in inhibited media is discovered by the method of electron microscopy. The morphology and composition of the film formed by weakly soluble calcium and iron phosphates depend on the ratio of components of the pigment.

The influence of ion-plasma nitriding time of Zr–1Nb alloy fuel cladding tubes on their resistance to oxidation in water vapor at 600–1200°C was studied. The hardness of the samples along the wall thickness increases from 2 to 3 GPa, and on the surface up to 12 GPa depending on the processing time. The nitrided tubes oxidize much more under cracking and delamination of the oxide layer compared to the initial state.

We study the biomedical Ti–18Nb–4Zr–xSi cast alloys with a silicon content of 0.5–1.5 wt.%. Quenching in water was carried out within the temperature range 900–1200°С with durations of holding equal to 5 min and 1 h. It is discovered that the procedure of heating of these alloys to the temperatures of quenching leads to the decay of nonequilibrium phases, and the silicon content is redistributed between the phases in a solid solution and silicides. Since almost all silicon is bound with zirconium and titanium and form silicides, the hardness of the Ti–18Nb–4Zr–xSi alloys mainly depends on the amount of silicides and constitutes 26–28 HRC. Moreover, its maximum values are reached for the alloys with eutectoid compositions containing 0.8–1.2 wt.% Si characterized by the most intense release of finely divided silicides. The increase in the silicon content of the hypereutectoid alloys leads to an increase in the sizes of silicides, as well as to the formation of larger amounts of the β-phase in the as-cast Ti–18Nb–4Zr–xSi alloys, and as a result, their hardness noticeably decreases. For low quenching temperatures (within the range 900–1000°C), the complete eutectoid destruction accompanied by the formation of relatively large stable (Ti, Zr)3Si silicides leads to a decrease in hardness < 25 HRC. In the course of quenching of the as-cast Ti–18Nb–4Zr–xSi alloys at temperatures ≥ 1100°C, we observe the formation of more finely divided silicides, which increases the level of hardness of the eutectoid alloys up to 38–39 HRC. The observed changes in the parameters of the α″-phase demonstrate that, as a result of partial dissolution of silicides in the course of quenching at 1200°C, silicon passes into a solid solution and the amount of large silicides on the grain boundaries increases. Therefore, the level of hardness of the analyzed quenched alloys decreases.

The stress-strain state in a crystalline solid body is determined by solving the problem of the theory of elasticity for an edge dislocation containing a cavity on its continuation. The cavity is modeled by a microcrack. We deduce equations for the energy of a body containing a microcrack of this kind under pressure. The geometric parameters of the crack-like dislocation cavity and the lengths of equilibrium and nonequilibrium cracks are presented. We also determine the critical pressure corresponding to the onset of crack growth on the continuation of the dislocation defect. In addition, we computed the stress intensity factors for the indicated kind of cracks.

We present the results of investigations of the electrochemical dissolution of silicon at the anodic potential E = 3 V in the field of ultrasound in solutions of hydrofluoric acid (HF) in dimethylsulfoxide (DMSO), dimethylformamide (DMF), and acetonitrile (AN). It is shown that, in the course of anodizing, cylindrical pores with an average diameter of 150 nm are formed on the silicon surface. These pores are uniformly distributed over the substrate. It is shown that the geometry of silicon pores and the rate of their formation are affected by the following main factors: the concentration of HF in the solution, the duration of electrolysis, and the nature of the aprotic solvent. It is shown that the rate of formation of porous silicon (PSi) increases with the HF concentration and the strength of anodic currents. The influence of ultrasound on the process of anodizing is explained. We present the results of scanning electron microscopy and the histograms of distribution of particles in size depending on the conditions of anodic dissolution of silicon.

The distribution of magnetic fluxes during reversal magnetization of three- and four-layer ferromagnetic materials with the same layer thickness by attachable probes with a U-shaped core is analyzed. The analytical expressions for determination of magnetic fluxes effective coercive force (CF) are obtained. The application of linear approximation for hysteresis loop demagnetizing sections of separate layers is substantiated. The stable regularities in these expressions are established. Based on them, a recurrent formula for the effective CF of layered ferromagnetic materials, which consist of an arbitrary number of layers of the same thickness, is proposed. The effective CF depends not only on the CF of individual layers, but also on their residual magnetic inductions. An experimental verification of the obtained expression is carried out on the 08kp and St3 steel samples. A magnetic analyzer of the KRM-Ts-MA type is used for CF and residual magnetic induction measurements. The calculated values of the effective CF for the two-layer ferromagnetic material of the mentioned steels according to the obtained recurrent formula and the measurement results agree well (the error does not exceed 3%).

We present the results of impedance testing of the protective coating of the bar frame of an agricultural sprayer with thermoplastic powder paints under the operating conditions. The accumulated results confirm high quality and durability of the coating. However, due to the presence of mechanical defects, penetration of liquid working media or chemical destruction, through defects may appear in the coating. As a result, the access of water, oxygen, and corrosive ions to the metal surface is significantly simplified. At the site of defect, we observe the development of local corrosion, and the barrier properties of the coating deteriorate.