A set of studies on the influence of tempering modes on structural changes in sheet metal products of various thicknesses of high-strength low-carbon martensitic steel has been carried out. It has been shown that the formation of a carbide phase in lath martensite and self-tempered martensite has a decisive influence on the level of impact work of steel with a martensitic structure.

The work investigates the effect of heat treatment on the formation of an α-phase layer with a modified structure, representing polyhedral grains of different sizes, on the surface of rolled sheet products made of high-strength low-carbon chromium-nickel-molybdenum bainitic-martensitic shipbuilding steel. After varying the hardening and tempering modes, metallographic studies and hardness measurements from the surface to the middle of the rolled product with a thickness of 10 mm were carried out. The deformation capacity of the rolled sheet products was estimated based on the results of bending tests at an angle of 180°. It was shown that the duration of high tempering has a decisive effect on the formation of such a layer. Based on the research results, a mode of heat treatment of rolled sheet products with a thickness of less than 16 mm was proposed, ensuring the formation of an α-phase layer with a modified structure of the smallest depth without significant changes in hardness.

The paper presents the comparable study of changes in hardness and microstructure of the 0.35Cr hot rolled chromium steel after isothermal and cycle annealing. After conducting the experiment, temperature modes of such annealing have been provided to meet additional requirements to hardness and depth of the decarburized layer according to National Standard GOST 4543–71. The advantage of the developed cycle annealing with soaking above the Ас₃ critical point in terms of temperature-and-rate conditions of cooling at the final cycle for formation of the uniform structure of granular pearlite and spheroidization of the carbide phase along the entire area of studied samples is demonstrated.

The microstructure of the material of the first-stage working blade of the Siemens SGT-400 gas turbine made of a heat-resistant single-crystal alloy was investigated in the post-operational state (after working out the assigned resource of ~25,000 h). The structural and phase state of the heat-resistant single-crystal nickel-based alloy after full-scale operation under conditions of long-term exposure to a high-temperature gas flow and working loads was studied using electron microscopy, X-ray diffraction analysis and differential scanning calorimetry. The regularities of the high-temperature aging process were studied, manifested in the appearance of coarse porosity, precipitation of the lamellar γ’-phase and local fusion of γ’-phase cells in the axes of dendrites. The micro indentation method was used to study the microhardness in different zones and structural components of the material of the locking and feather parts of the blade.

The structure and properties of the metal of construction beams in buildings of the 19th century have been studied: the I-beam as a load-bearing element of the Monier brick vault and the rail as the base of the balcony. The metal of the I-beam was found as low-carbon steel, moderately contaminated with impurities. The mechanical properties of the metal are sufficiently high at the ambient temperature. However due to the great amount of the carbon macrosegregations the metal is prone to cold brittleness. The rail is made in England from the puddling iron. The metal is characterized by brittleness and it contains numerous non-metal inclusions enriched with phosphorous.

Influence investigation of the angular die parameters on hydrostatic pressure during equal channel angular pressing was studied by finite element method. The channel intersection angle has been considered in the range 90–120°, and the outer die radius was studied in the range (0.05–1). The problem is solved under the assumption of а plane-strain state using a model of an ideal rigid-plastic body. The friction conditions with the coefficient of friction equal 0.1 are determined by Coulomb – Amonton’s law. The results of modeling the level of hydrostatic pressure on the axis of the deformation zone are compared with the analytical solution. The hydrostatic pressure distribution dependence at the input and output of the plastic deformation zone boundaries on the die geometry characteristics was estimated. The hydrostatic pressure heterogeneity in plastic deformation zone was determined.

In this work, a high-entropy alloy Fe^xCo⁶Al³Ni²Si (where x = 5, 6, 8) was obtained by mechanical alloying. The microstructure, phase and granulometric compositions of the obtained powders were studied. The required specific energy dose for the formation of a homogeneous solid solution (D = 30 W⋅h/g) was determined. Using the CALPHAD method, a phase diagram was constructed for the multicomponent Fe^xCo⁶Al³Ni²Si system. The Fe8Co6Al3Ni2Si alloy powder after mechanical alloying showed a saturation magnetization of 154 emu/g and a coercive force of 53 Oe. Compact samples were obtained from the Fe^xCo⁶Al³Ni²Si alloy powder in a spark plasma sintering installation and annealed at temperatures of 900, 950 and 1000°C. The microstructure and phase composition of the samples after annealing were studied. Tests of magnetic properties of samples showed that the saturation magnetization of samples ranged from 159 to 168 emu/g, coercive force – from 8.9 to 29.2 Oe. Compressive strength of samples ranged from 2190 to 2680 MPa, and microhardness – from 681 to 811 HV.

The paper studies formation of composite powders of the Alx NiCoFeCr system at 1.6 ≤ x ≤ 60 at%, suitable for coatings obtained by the microplasma spraying. The phase composition of all combinations was investigated. An analysis of the granulometric composition, uniformity of the distribution of elements in the synthesized conglomerates was carried out, and the Vickers microhardness of the powders was measured. For the equiatomic system, the microhardness indicators were 6–9 GPa with a range of values up to 16%, the morphology of the particles was round, the diameter was from 6 to 63 μm. It has been established that for microplasma spraying it is advisable to use powders containing aluminum 20 ≤ x ≤ 60 at%.

The article presents the results of the study of mechanical and operational properties of the metal of the experimental model made of titanium pseudo-α-alloy PT-3V, obtained using hot isostatic pressing (HIP technology). The mechanical properties, as well as the performance characteristics of the experimental model, fully comply with the requirements of the regulatory documentation imposed on deformed semi-finished products of similar sections. The microstructural studies carried out in various thicknesses demonstrate the isotropy of the compacted part compared to the deformed semi-finished product.

Fused deposition modeling (FDM) is one of the most common additive manufacturing technologies based on the extrusion of thermoplastic filament. The creation of composite materials for FDM-printing by introducing dispersed fillers into a thermoplastic matrix allows obtaining parts with the required set of characteristics. In this paper, an attempt was made to improve the wear resistance of PETG-based polymer composite materials (PCM) samples by modifying them with aluminum oxide micropowder. The optimal content of the modifying component was determined, thus ensuring the 3D-printing process and reducing the wear of such PCM.

Experimental studies of the heating process of cured carbon, glass and organoplastics and their components placed in an ultra-high-frequency (UHF) electromagnetic field have been performed. It has been shown that the main influence on the kinetics of the process is exerted by the thermal and electrophysical properties of the filler, as well as the absorbed radiation power. The effect of exposure time is less pronounced and is described quite accurately by power functions. For an epoxy binder, this dependence is close to linear. It has been established that the heating of carbon plastic in the first minute of microwave exposure exceeds this indicator for glass and organoplastic by 35–38%, despite an almost 4 times lower level of absorption of radiation power. The fact of more intense microwave heating of aramid fabric and organoplastic than fiberglass, which is manifested in an almost 2 times greater dependence of the heating temperature on the absorbed radiation power, requires additional study and justification.

The article presents the results of a study on the recycling of polymer composite materials (PCMs) based on reactive matrices using solvolysis. Epoxy and epoxy vinyl ester resins were used as the matrix material, which were cured at room temperature. To optimize the selection of the solvolysis medium, the solubility parameter of the matrix component was calculated using the method of A. Askadsky. This method has been shown to be effective in selecting solvents for polymer matrices destruction. Based on experimental studies, pyridine was found to be the best solvent out of those considered. Its use reduced the time of the solvolysis process to 1 hour at boiling point (115°C). The resulting fibers had a residual content of 20% of the original polymer matrix. The strength of these recovered fibers was found to be up to 91% of their initial strength. However, composites made from these reconstituted fibers showed a 29.7% reduction in bending strength compared to the original compo sites. Despite this, the recovered fibers can be used to create non-essential, low-weight products. The study confirms the potential of using nitrogen-based solvents for recycling polymer composites.

The work investigated the effect of neutron irradiation on the aggregate- and dispersion-hardened structure of composite ceramics of the composition α-Al₂O₃ + n% YSZ (ZrO₂ + 3 mol.% Y₂O₃) (n = 0; 1; 5; 10 and 15 wt.%) obtained as a result of processing compacts with high hydrostatic pressure (HHP) – 300 and 700 MPa. X-ray structural analysis showed that neutron irradiation of two-phase ceramics did not cause phase changes in the ceramic composite. In the course of the work it was established that the effect of grain fragmentation in the material is observed only in relation to YSZ particles and is not observed in relation to α-Al₂O₃ grains, which may be associated with the structural features of the crystal lattices of α-Al₂O₃ and t-ZrO₂. The results of the research allow us to talk about the prospects for using the studied ceramics under conditions of radiation exposure.

Welding operations in the manufacture of marine structural parts from titanium pseudo-β-alloys of large thicknesses inevitably lead to the occurrence of residual stresses that arise in various areas of the weld and the weld-affected zone and contribute in some cases to the occurrence of defects and cracks. The development of high-gradient fields of temporary and residual welding stress, occurring at various locations within the weld joint and heat-affected zones, poses a specific risk. These stress fields can contribute to the formation of defects and cracks in certain circumstances. Computer simulation of welding processes is extensively utilized today for analyzing and predicting the performance of welded joints, as well as optimizing the welding process. Given the substantial complexity involved in modeling welding operations, mathematical descriptions of these processes have increasingly embraced numerical methods over the past decade. These methods, grounded in Finite Element Method (FEM) software solutions, facilitate the resolution of thermodeformation challenges within spatiotemporal parameters. The purpose of this work is to develop a calculation method that models the formation of temporary and residual welding stresses during sequential filling of the weld bevel and its non-simultaneous execution along the length of the joint.

The results of tests of control welded joints of steels containing 2.25% Cr and 1.0% Mo with different modes of post-weld heat treatment are presented. A decrease of the plastic characteristics of welded joints with decreasing temperature and increasing of the duration of post-weld heat treatment has been shown.

The paper offers an analytical review of theoretical and applied research devoted to high-temperature hydrogen attack on steel. Advanced diagnostic techniques of hydrogen attack are examined, the fundamen tal domestic and foreign developments are reviewed. The article is focused on the most promising recent studies of HTHA damage for purposes of estimating fitness-for-service of metal equipment exposed to hydrogen at elevated temperatures and risk/failure assessment.

The article presents the results of studies of the data on crack resistance characteristics of dissimilar welded joint metal of the main circulation pipeline insert and the branch pipe of main circulation pump. The obtained data are necessary for performing calculations to justify “Leak-before-break” concept application at lifetime extension of the main circulation pipelines of VVER-1000 reactor to 60 years (up to 520 thousand hours). The studies were performed on specimens from manufactured control welded joints of DN800 pipeline insert made of steel grade 10GN2MFA to the main circulation pump branch pipe made of steel grade 06Kh12N3DL. Studies of crack resistance were carried out to obtain J_r-curves of the weld metal, made by manual and automatic welding, and the transition weld zone in the initial state and after thermal aging in the operating temperature range from 100°C to 290°C state. According to the predicted values of T_k(τ), the values of the fracture toughness K_jc(τ), as well as the impact strength KCV at design temperature of 290°C for the end of the service life are estimated.