The methodology for monitoring damage kinetics and assessing the bearing capacity of structures using acoustic emission (AE), developed in relation to products made of polymer composite materials (PCM), has been adapted to the evolution of structural steel failure. Due to the higher plasticity of structural steels compared to PCMs, the relative energy ( E p ) of AE pulses generated during the rupture of structural bonds at the same scale level turned out to be approximately 5–15 dB lower than in composites. Therefore, during the AE diagnostics of structural steel products, the following boundaries of the separation of AE pulses into energy clusters are established: E p < 80 dB for the low cluster, E p = 80–100 dB for the medium cluster, and E p > 100 dB for the high cluster. We consider testing of the methodology for monitoring the kinetics of damage and assessing the load-bearing capacity of products in the loading mode during static and cyclic tests of samples made of 08Kh18N10T steel with an edge-cut notch.

The paper considers the effect of various stress concentrators on processes of damage accumulation, initiation and propagation of crack in steel (steel 3) samples during uniaxial tensile. In the middle of the samples there was a transverse welded joint or a hole with a diameter of 5 mm. The acoustic-emission testing results showed that weight content of location impulses (Wi) in the clusters of low, middle and high energy level and criteria parameters value Wi at the stages of the samples destruction have similar pattern of change despite the various types of concentrators, stress-strain material diagrams, pattern of damage accumulation, number of registered acoustic emission (AE) events and its registration activity.

The influence of various kinds of stress raisers on the processes of damage accumulation, initiation, and propagation of cracks in specimens of steel St3 under uniaxial tension has been considered. The investigated samples had a central aperture with diameter of ∅ = 5 mm or a transverse weld. The results of acoustic emission diagnostics showed that, despite the different nature of the stress raisers, the loading diagrams, the nature of damage accumulation and development of main cracks, the number of recorded acoustic emission (AE) events, and the activity of their recording, as well the dynamics of changes in the weight content of location pulses ( W_i ) in the energy clusters of the low, medium, and high levels were quite similar, along with the values of these parameters during sample failure.

— Specific features of fabricating welded structures of the international thermonuclear experimental reactor (ITER) blanket components are considered. The results from elaborating the technology for electron-beam welding of cooling system’s channel caps in the first wall bearing structure (FWBS) of the ITER blanket shielding module are presented. The design of welded joint samples made of Grade 316L(N) steel and the welding equipment are described. The welding techniques and butt joint design features whose use makes it possible to obtain the required strengthening of weld bead and to avoid metal droplets from appearing in the FWBS inner cavities are considered. A simplified thermal–mechanical model of the cap-welding technological process is described, and the results from experimentally evaluating the structural and mechanical state of the obtained welded structures are presented. A comparison between the modeling and experimental results is given. It is pointed out that the stressed and strain state varies in an active manner at the initial loading stage. Initially, the metal in the heat-affected zone (HAZ) experiences plastic deformation followed by elastic relief at the subsequent stages. It is pointed out that the postweld deformations are on the whole characterized by a low level and remain within the permissible limits. The distribution of mechanical properties in weld joint local zones determined using the indentation method is given. The results from tensile tests and an indenter impressing test show that the weld metal has even better mechanical characteristics than the parent metal. Data are presented from metallographic investigations, which testify that there is no growth of grains in the HAZ, which is due to high rates of cooling in the used welding method. Based on the results of elaborating the electron-beam welding technology and using the developed techniques, an FWBS mockup has been fabricated that complies with the class VQC 1A tightness requirements.

The plastic deformation zone sizes in various metallic materials (steel, copper, armco-iron) are studied during tests by scratching with a tetrahedral Vickers pyramid under the scratch formation conditions at a constant depth. The ratio of the plastic deformation zone depth under a scratch to the scratch depth is found to weakly depend on the scratch depth and to be 6.3–8.5 for the materials under study. Based on these results, we concluded that, when the mechanical properties of a metallic material are determined by scratching, the ratio of the material thickness to the scratch depth should be at least 8.5.

The mechanical properties of the welded joint of EP517 steel and 36NKhTYu alloy, which is formed by electron-beam welding followed by heat treatment, are studied. The strength of the soft layer that forms in the welded joint is shown to have the strength of the base metal under certain conditions. The relative weld width that ensures the same strength of the welded joint and the base metal due to local strengthening is experimentally determined.

Results of the study of microstructure and hardness distribution of weld joints of BrKh1Tsr bronze by electron–beam welding (EBW) after welding and thermal aging are given. Thermal aging provides an increase in the hardness of weld metal up to 80% of the hardness of the base metal, while the hardness of the heat-affected zone is up to 60%.

Surface strengthening of structural steels with carbon nanomaterials using laser and electron-beam heating is studied. It is shown that during laser treatment the maximum microhardness of a modified layer is achieved in a strengthened zone up to 70 μm thick with q = 9 × 10 4 W/cm 2 , and with electron beam treatment in a strengthened zone up to 300 μm thick with q = 4.6 × 10 4 W/cm 2 . It is established that in both cases with optimum treatment regimes strengthening is due to forming martensite, a cellular structure, and grain disintegration.

The depths to which plastic deformation occurs under ball indentation of a steel plate at various loads is determined. It is established that the ratio of the depth that plastic deformation reaches to the indentation depth is constant (approximately 15) independently of the indentation load. This finding allows us to conclude that this ratio should be held no less than 15 in hardness measurements. Experiments demonstrate that the lower the hardness of the metal substrate, the larger the decrease in the measured hardness when the ratio is lower than 15.

It is shown that the processing parameters of electron beams with power up to 6 kW and energy of 60 keV used in electron beam installations can be determined by means of light radiation from drift space. A digital photo camera-assisted technique to obtain an image is described. It is shown that the registered image processing allows one to obtain information on the internal structure of an electron beam. The dependence of focal length on the focusing magnet lens current is obtained. The peculiarities of current density distribution over beam cross section are revealed. It is found that the behavior of the beam current density distribution depends strongly on the conditions of major cathode heating. The proposed method to determine electron beam parameters can be applied to control operation conditions of processing equipment, for example, to find the accuracy of gun adjustment, as well as cathode state, from the behavior of the power density distribution. The obtained dependences of beam parameters on the operating conditions of an electron gun can be used when choosing processing parameters to reduce the quantity of work on experimental optimization of welding conditions.