The changes in the structure and properties in the heat-affected zone of high-strength steel grade E690 depending on the level of linear energy during welding are studied. Recommendations are given for the selection of welding modes to prevent degradation of the properties of welded joints.

Behavior of gases at the stages of production of high-strength vessel steel made with REM complex material and standard technology of steel modification by ferrocalcium has been investigated. It has been shown that the nitrogen content in steel increases regardless of which of the tested modifying treatment methods was used, from liquid castings to sheet metal rolling.

Oxygen content regardless of the modifying method increases in liquid metal including casting, after which it decreases significantly in slab and sheets. Modification of high-strength vessel steel by complex alloys with REM allows to reduce the hydrogen content in the metal.

In the presented work, the approach of solid-phase alloying of a multicomponent system is tested for the first time as applied to an equiatomic mixture of single-phase powders of Al, Ni, Co, Fe and Cr and microplasma spraying of coatings based on them. It is established that in the process of mechanochemical synthesis, a composite powder is formed, which is rounded conglomerates of the “5me” system, with a granulometric distribution from 10 to 110 μm. Studies of the structure and properties of coatings showed the formation of gradients of microhardness and elemental composition, but homogeneity increases with an increase in the duration of mechanosynthesis. In the coatings after 15 minutes of mechanochemical synthesis of the composite powder, Fm3m, Im3m and Pm3m phases are formed, the pores are located along the boundaries of the interweavings (porosity 4.8%), in the distribution of microhardness it was possible to identify two areas with microhardness values of 600 HV and 300 HV (less than 10%) with an average deviation of 7%, adhesion to the steel substrate was 54 MPa.

The paper presents the results of developing the optimal composition of a precision copper-nickel alloy, from which composite powders, the surface of which is plated with titanium diboride, are obtained by highspeed mechanosynthesis. Functional coatings are made from the composite powders by cold gas-dynamic spraying on a DIMET-3 unit. The resulting coatings are characterized by high microhardness (24–26 GPa) and have a long service life (10,000 hours).

The paper presents the research results on high-entropy CoCrFeNiMnNx alloy obtained by selective laser melting. Powders of high-entropy alloy CoCrFeNiMnNx (with calculated nitrogen content x = 0.1 wt.%, 0.2 wt.%, 0.5 wt.%) are manufactured by mechanical alloying followed by plasma spheroidization. Alloys mechanical properties and its compaction by selective laser melting were investigated at room and cryogenic temperatures. Alloys with nitrogen content of 0.1 and 0.2 wt.% show an increase in mechanical properties at decreasing temperature. The conditional yield strength increased by 27.2 and 63.3%, the ultimate strength by 30.8 and 52.7%, respectively. The study was carried out with the financial support of the Ministry of Science and Higher Education of the Russian Federation (Grant Agreement No 075-03-2024-004).

The NRC “Kurchatov Institute” is working on the creation of antimicrobial nanocomposites containing biogenic colloidal nanosilver (NPsAg). Biogenic NPsAg obtained by microbial synthesis using bacterial cells and AgNO₃ solution in liquid and dry preparative forms. To protect underwater objects from biofouling, a composition has been developed that includes complex chelated compounds of transition metals Cu, Zn and biogenic NPsAg. Cu and Zn chelates are synthesized by a complexation reaction, the antimicrobial activity of which increases with the introduction of NPsAg. It has been established that NPsAg keep stability and biocidal effect during prolonged exposure to seawater, which is important for their utilization as part of antifouling coatings. The technology of introducing biocidal NPsAg into the composition of polymer nonwovens and ion exchange resins of various types has been developed.

The present work is devoted to the review of studies considering the influence of low and ultra-low temperatures on the properties of polyetheretherketone (PEEK) and composites based on it. The reviewed studies describe the changes in the physical-mechanical, thermo-mechanical, thermal and tribological properties of PEEK at low temperatures, as well as the influence of different fillers on the changes in these properties. The works presented in this review analyze the opportunities, prospects and limitations of PEEK applications under conditions of permanent or temporary exposure to low temperatures. Understanding the trends described in the presented studies can help in modeling the properties of various PEEK-based composites and designing products intended for low-temperature applications.

The work is devoted to the study of physical and mechanical properties and tribotechnical characteristics of new hybrid antifriction polymer composite materials (PCM). The influence of hybrid fabric composition on physical-mechanical properties and tribotechnical characteristics of hybrid PCMs has been investigated. It is shown that new hybrid antifriction materials are not inferior to antifriction carbon plastics and surpass them by some characteristics.

The article presents a method for producing thermoplastic prepreg tapes based on unidirectional carbon fiber with a low modulus of elasticity of the brand. UMT42S-3K-EP by impregnation in an aqueous polymer slurry. The granulometric composition of the initial fine components and their mixtures after the grinding and mixing stage was studied, as well as their structure was studied by SEM microscopy and PCMA analysis. Based on the theory of particle interaction on the solid-liquid surface, samples of suspensions based on polyetheretherketone (PEEK) stabilized with anionic and cationic surfactants were prepared. To implement the technology of impregnating carbon fiber with a polymer suspension with constant maintenance of the polymer suspension, a laboratory UPS-5-50-2L unit has been developed and incorporated into a TMA-600 impregnating device. The obtained laboratory samples of thermoplastic tapes were examined by SEM microscopy and PCMA analysis, and the ratio of polymer to reinforcing material was determined. The study shows that the use of surfactants can significantly reduce the hydrophobicity of PEEK to stabilize it in aqueous solution. The developed impregnation unit as part of the TMA-600 line makes it possible to implement the technology of producing thin unidirectional prepreg tapes with a polymer content in fiber of up to 46.8%. It was found that the concentration of cationic surfactant up to 2 wt% is sufficient to ensure the wettability of the PEEK surface.

Composite materials based on industrial polybutylene terephthalate and secondary polyethylene terephthalate were obtained, and their basic physical and mechanical properties are investigated. It was found that these polymers combine and form a homogeneous system at certain ratios. The optimal amount of secondary polyethylene terephthalate has been determined, which can be introduced into polybutylene terephthalate while preserving its basic physical and mechanical properties.

The paper considers the existing methods of desalination of water with a high content of minerals, as well as the problem of scale formation and corrosion in thermal engineering equipment. Such water is often used for technical water supply of heating equipment, where the salts contained in it lead to a decrease in efficiency, as well as equipment failure. In addition, the problem of desalination of seawater is relevant for countries located in arid regions of the globe, limited by low rainfall and countries with a shortage of freshwater sources.

An express method of scale formation is presented, which allows evaluating the effect of modifying additives on the anti-scale properties of a protective polymer coating. The process of sediment formation in real devices with real media is quite long, and it may take a considerable time to obtain a result suitable for evaluation, which is unacceptable, since the selection and optimization of the composition will take years. In the proposed installation, the formation of scale deposits on the substrate occurs in 2 hours. The method consists in exposing a brass plate with a protective polymer coating in an experimental laboratory installation that provides conditions similar to the operating condition of heat exchange equipment with unchanged composition of the mineral solution and experimental conditions, and subsequent analysis of the coating and carbonate deposits. The analysis consists in determining the thickness of the formed scale layer on the modified and unmodified coating, determining the elemental composition of these deposits, as well as evaluating the uniformity of their distribution.

The paper presents the methodology of scientifically substantiated concept of production improvement and repair technologies for ship structures based on the integrated application of modern technologies, power sources and promising domestic welding and surfacing materials. The proposed methodological approach is formed in accordance with the adopted strategy of scientific and technological development of the Russian Federation, which is aimed at the realization of tasks and national priorities in ensuring the country’s ability to effectively respond to great challenges. The direction associated with increasing the efficiency of domestic industrial production is inextricably linked with the development of welding, related processes and technologies, as fundamental technologies for obtaining high-strength permanent joints in the production and repair of wearable products and structures for critical purposes. Research objective: Justification of the most effective ways to improve production technologies, repair of ship structures and port infrastructure equipment on the basis of complex application of advanced technologies of its production, repair and strengthening treatments of highly loaded products, modern power sources and domestic welding and surfacing materials. Achievement of the above formulated goal is based on the complex application of positive results in the performance of fundamental, oriented and applied research aimed at the creation of a new generation of shipbuilding steels and technologies of their application, organization of production of welding and surfacing materials, modern power supply systems.

The temperature cycle in the welding of near-β-titanium alloys has an effect on the final characteristics of the welded joint in connection with the possibility of forming an enlarged low-plastic state of individual zones. In order to prevent the occurrence of adverse thermal effects on the metal of the structure, welding through pre-surfacing is often used. In this regard, the problem arises of experimental and computational study of the distribution of the temperature field in the process of welding titanium near-β-alloy through surfacing of various thickness. The ANSYS Workbench software product was used for the calculated welding simulation. Comparison of experimental and calculated results showed a good coincidence of the distribution of temperature fields in the welded joint zone.

The structure and properties of diffusion brazed titanium alloys joints of the various titanium alloys (PT-3V, VT6, VT6S, VT20 and VT22) are investigated. The optimal technological parameters to produce the joints of the equal to the base metals strength are proposed. The effect of plasticization of the two-phase titanium alloys (VT6S) after high temperature annealing near the polymorphous transformation temperature (during brazing) is shown. An improved method for brazing high-alloyed titanium alloys is considered using the example of (α+β)-titanium alloy of the transition class VT22. Brazing was carried out through a titanium interlayer using an amorphous tape filler, providing a joint strength of 1000 MPa.

The effect of ultrasonic vibrations on the structural-phase composition and wear resistance of hypoeutectic and hypereutectic surfacing alloys of the Fe–Cr–Ni–Mn–Mo–Ti–Nb–C system was studied. Vibrations were introduced into the weld pool using a filler flux-cored wire during electric arc surfacing with a consumable electrode. Metallographic studies of the alloys, micro-X-ray spectral and X-ray structural analyses were performed. Alloy samples were tested for resistance to gas-abrasive wear, as well as wear through an abrasive layer at normal and elevated temperatures up to 600°C. It was found that acoustic treatment of the weld pool, differently affecting the structure of the alloys of the alloying system under consideration, can cause both a decrease and an increase in the wear resistance of the alloys.

The experimental study results of the fracture properties and mechanisms are represented for austenitic 18Cr–9Ni steel irradiated at 400°С up to damage dose of 15 dpa. The fracture properties have been obtained for cylindrical smooth and notched specimens under uniaxial tension over temperature range from 20° up to 500°С, and the fracture surfaces have been examined by SEM to analyze the main fracture modes with emphasis on specific fracture mechanism of irradiated austenitic steels – channel fracture. Basing on the performed study results the temperature range and the main features of channel fracture are found. It is shown that the strain hardening decreases over the temperature range of channel fracture that is caused by channel (localized) deformation in the irradiated steel being necessary condition for channel fracture. Shares of various fracture modes are estimated depending on stress triaxiality and test temperature. It is shown that the channel fracture area share relative to total fracture surface area increases when stress triaxiality increases. The relief of channel fracture area and channel fracture facets surface is studied. Secondary deformation channels exits are revealed on the channel fracture facets surface that locate regularly on the distance of 1–2 μm each other. The obtained results are used for elaboration of channel fracture model and formulation of channel fracture criterion and for the proposed criterion verification that are considered in the second part of the paper.

On the basis of experimental data considered in the first part of the paper the channel fracture model is represented and channel fracture criterion is formulated for irradiated austenitic steels. The model and criterion are based on the initiation of microcracks in channel deformation plane due to intersection with secondary channels and on the microcracks growth by shear. The proposed model and criterion of the microcracks initiation in channel deformation plane explain why channel fracture is observed in irradiated FCC metals and never observed in irradiated BCC metals although channel deformation being necessary condition for channel fracture occurs in the both metals. Procedure for the criterion parameter determination is proposed on the basis of the test results of standard tensile cylindrical specimen and cylindrical specimen with circular notch tested at one temperature over the channel fracture temperature range. Numerical values of the criterion parameters are found when using the test results represented in the first part of the paper. The proposed channel fracture criterion has been verified as applied to irradiated 18Cr–9Ni steel by comparison of the experimental and calculated values of the fracture strain for specimens with various stress triaxialities and for specimens tested at different temperatures.