Summarized results of research of the dynamic and static austenite recrystallization kinetics of low-carbon low-alloy and alloyed steels of strength classes 420, 620, 690, 750 and 890 and medium-carbon steels of strength class 1700 containing different amounts of vanadium, niobium and boron are presented. Studies were carried out by the plasmetric method under deformation conditions close to hot rolling. It was found that vanadium has a weak effect on recrystallization, and niobium in all the studied steels significantly slows it down in the hot rolling temperature range, regardless of the total doping level; microalloying of steels with boron leads to acceleration of austenite recrystallization.

The kinetics of growth of austenite grains during heating, the features of the processes of dynamic and static recrystallization occurring under various temperature-deformation regimes of hot plastic deformation have been studied. Phase transformations have been studied during continuous cooling of hot-worked austenite in a low-carbon low-alloy steel with a guaranteed yield strength of 890 MPa. As a result, the boundary temperature-deformation conditions for the formation of a finely dispersed bainite-martensite structure were established, on the basis of which technological modes for the production of thick-plate rolled products in industrial conditions were developed. The structure and properties of rolled sheets 35 mm thick from shipbuilding sparingly alloyed steel of strength level 890 are presented.

Tests of friction pairs steel–ice for two grades of structural steel with a yield strength of 540 and 760 MPa were carried out. The dependences of the friction coefficients on the applied load and changes in the ambient temperature are studied. It is shown that the coefficient of static friction of the samples is noticeably higher than the kinetic one, which indicates the adhesion of ice to steel.

The mechanism of strengthening of a two-phase chromium-nickel alloy 65Cr-(31-35)Ni–Ti–V–W depends on the heat treatment mode: the lattice periods of the α-phase (alloy matrix is a solid solution of Ni in Cr) in the hardened and equilibrium conditions are almost the same; level of strength and ductility properties of alloy determines dispersion and amount of γ-soft nuclei released during heat treatment (solid solution of Cr in Ni), its hardness is less than that of α-phase. Quenching from single-phase area from 1250°C and tempering at 800−900°C provides a higher strength than annealed alloy and increases the start temperature of high temperature failure. The nature of the destruction depends on the temperature. The influence of γ-phase is manifested more significantly at temperatures below equicohesive.

The paper presents the results of a study of changes in the structure and strength properties of a heat-resistant nickel alloy after various periods of operation in a gas turbine engine. It is shown that after 25,000 hours of operation, irreversible changes occur in the microstructure of the alloy, which adversely affect the performance of the parts. Ensuring the stability of the structural state and mechanical properties are very important in assessing the reliability and extending the service life. The results of a study of the effect of heat treatment parameters on the structural characteristics of the CrNi65CoMoWAlTi alloy are presented, and an assessment is made of the effect of structural parameters on mechanical properties. Timely application of recovery technologies can extend the service life of products.

The results of the development of technology for obtaining nanostructured composite powders in two ways – surface reinforcement and cladding are presented. The possibility of manufacturing functional coatings based on the obtained powders by the method of supersonic cold gas-dynamic spraying is shown. The characteristics of the resulting coatings (adhesive strength, microhardness, wear resistance, low porosity) were studied. The real prospect of using the created functional protective coatings for precision engineering is shown.

The physical and chemical foundations of the technology of cold gas-dynamic spraying of coatings on titanium for two types of charge are considered, in one of which chemically inactive copper is used as a ductile metal in combination with abrasive silicon carbide powder, in the other – chemically active aluminum in combined with silicon carbide. A thermodynamic modeling technique has been developed to select the composition of the coating charge and predict the change in its phase composition at high temperature.

The change in the properties of rubbers 98-1 and RP-10 based on nitrile butadiene rubbers with 17– 20% of acrylonitrile content under thermal cycling conditions in the range from –50 to +80°С is evaluated. The samples are exposed in the air and working hydrocarbon medium of hydraulic oil I-20A in stress-free and deformed states. It has been established that 98-1 rubber is more resistant in air and RP-10 rubber containing a sulfur-peroxide vulcanizing system and UHMWPE demonstrates high durability in a hydrocarbon medium in comparison with first one. The paper shows insignificant deformation on the rubbers properties and deterioration of the frost resistance of rubbers up to its complete loss during thermal cycling in the medium of I-20A hydraulic oil.

The particularities of 3D-woven composite’s defects are observed. Automated ultrasonic immersion through-transmission technique for their non-destructive testing is offered. X-ray computed tomography (X-ray CT) application for the definition of the reasons of ultrasonic waves high attenuation in 3D-orthogonal woven composite sample is described. The analysis of defects detected with X-ray CT is shown. The suggestion about connection between quantity of projection of defects total area at the plane which is perpendicular to ultrasonic wave propagation and ultrasonic wave attenuation has been made.

Results of comparative research of wear resistance of polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), ultrahigh molecular weight polyethylene (UHMWPE) and polyamide 6 (PA6) in friction pairs with 18Kh2N4МА, 08Kh18N10Т and 40Kh13 are presented. Self-lubricating ability of polymers was determined by the contact pressure value corresponding to the upper border of the diapason, in which the effect of stabilization of linear wear intensity values and by the length of this diapason along the axis of loads is shown. Carbon steel 45 was used as a base steel in the comparison. PEEK, UHMWPE and PA6 friction pairs show higher values of intensity of linear wear but decrease in ability to self-lubrication. However in friction pair PTFE – steel 18Kh2N4МА with the prevailing content of nickel (about 4%), expansion of a range of stabilization of linear wear intensity is observed. In friction pairs PTFE with steel 40Kh13, containing a considerable percentage of chrome (13%), in absence of nickel, and with steel 18Kh2N4МА containing a complex of nickel and chrome (10% and 18%, respectively), the least wear resistance and ability to self-lubrication of polymer are marked. Temperatures on polymer tribocontact corresponding to ranges of wear stabilization loadings in researched friction pairs are determined.

Fracture toughness of rolled plates of high-strength medium-alloy steel with a martensitic or martensitic- bainite microstructure can vary widely depending on the parameters of their microstructure, which depends on the specific chemical composition, rolling parameters, quenching and tempering. In previous works, the authors studied the metal of various experimental smelts. The studied materials were significantly different in the size of structural components separated by large-angle boundaries (hereditary austenitic grain, martensite packages, and bainite crystallites). The continuation of these studies is the analysis of the relationship between the fracture toughness of a metal of one smelt and the general quenching parameters and, as a consequence, with the same parameters of the microstructure formed during quenching, but with different tempering parameters. A general structural state parameter based on the obtained data, and correlated with fracture toughness is proposed.

The authors estimate possible losses of transported compressed hydrogen (P = 10 MPa) due to diffusion through the pipe wall applying Sieverts law and Arrhenius equation and using tabular data on the coefficients of permeability and solubility. The calculation was carried out for pipelines made of various metallic and non-metallic materials at room and elevated temperatures. It is shown that the volume of the diffused gas at T = 298°K (25°С) is only fractions of a percent of the pumped hydrogen volume. At the same time, the biggest loss occurs in a pipeline made of polyethylene (~0.03%), and the most insignificant one in austenitic steels (~10^-6%). For carbon and low-alloy steels, the main materials of gas pipelines, these losses are at the level of 10^-4–10^-5 %. When the temperature rises to 683°K (410°C), the losses in steel pipelines increase to 0.25%, in polymer pipelines to 20%.

The paper presents the results of mechanical tests of ring specimens made of the 42XNM alloy after irradiation as part of the control and protection system of the VVER-1000 reactor to a damaging dose of ~12 dpa at a temperature of ~350°C and subsequent isothermal annealings in the temperature range of 400– 1150°C (heating and holding for ~2 h). A model was constructed and validated by the finite element method, it describes the mechanical characteristics of irradiated and non-irradiated samples from the 42XNM alloy during tests in the temperature range from 500 to 1000°C. The model was used to plot the temperature dependences of the maximum local plastic deformation and the yield strength of the material under study.

The paper presents the results of structural studies of ring specimens made of the 42XNM alloy after irradiation as part of the control and protection system of the VVER-1000 reactor to a damaging dose of ~12 dpa at a temperature of ~350°C and subsequent isothermal annealings in the temperature range of 400– 1150°C (heating and holding for ~2 h). It is shown that during long-term isothermal annealing, a change in the phase composition of the alloy is observed, dislocation structures and grain-boundary segregations are annealed, and porosity evolves. It has been confirmed that decrease in the plastic properties of the 42XNM alloy after irradiation and subsequent isothermal annealing in the temperature range of 400–1000°C could be explained by the formation of precipitates of the second phases (zones of discontinuous decomposition of the solid solution with the release of α-Cr particles along the grain boundaries) and pores at the grain boundaries.

The results of the study of mechanical properties and brittle fracture resistance (BFR) are presented for weld metal of WWER RPV performed by automatic arc welding with use welding wire Sv-15CrNiMoTiA and ceramic flux 48AF-71. Mechanical properties are determined on the basis of test results of tensile smooth round bar. BFR are determined from impact strength tests and fracture toughness tests. The anisotropy of mechanical properties and BFR is investigated by testing the specimens with different orientations. Tests are conducted for specimens of two orientations: first orientation corresponds to the position of the specimen, in which the fracture surface is perpendicular to the axis of the weld; second orientation corresponds fracture surface parallel to the axis of t he weld. It i s shown that the weld metal performed according to above mentioned technology has no anisotropy both in mechanical properties and in BFR. An explanation of the significant scatter of BFR on the basis of the results of metallographic studies is proposed. The obtained experimental results on mechanical properties for investigated weld metal allow to use tensile smooth round bar with 3 mm diameter with transverse orientation instead of specimens with 6 mm diameter with longitudinal orientation as the scale factor and anisotropy are negligible. The correlation dependence between the values of reference temperature T₀ determined by the Master Curve method and reference temperature T₁₀₀ determined by the Advanced Unified Curve method and the value of critical brittleness temperature T_K0 for the studied weld metal in the initial state is established.