The modification of metals and alloys by the external energy deposition methods makes it possible to locally strengthen the surface layer of parts and assemblies made of aluminum alloys. This study is aimed at revealing the regularities of the effect of electron beam processing modes on the mechanical characteristics and fracture surface morphology of the Ti-surface-modified AK5M2 alloy. The authors used the methods of modern physical materials science. The surface of the AK5M2 alloy was modified with a Ti film by the vacuum arc method. The modified samples of the AK5M2 alloy were irradiated with an intense pulsed electron beam in modes differing in the energy density of the electron beam (from 10 to 50 J/cm2). Mechanical tests were carried out by uniaxial tension to fracture of the alloy samples in the original state and the modified samples before and after the irradiation in five modes. Using scanning electron microscopy, the authors carried out a fractographic analysis of the fracture surface of the samples obtained as a result of tension. The development of a unique method for modifying the AK5M2 alloy makes it possible to improve its strength and morphological properties compared to the material in its original state. As a result of the mechanical tests, the authors determined the values of yield strength, ultimate tensile strength, and relative residual elongation and narrowing at fracture. The dependence between the change in the deformation characteristics and the structure of the fracture surface on the electron-beam processing modes was established. On the basis of the tests performed on the samples of the Ti-surface-modified AK5M2 alloy, the authors revealed a mode of electron-beam processing leading to the formation of a surface structure characterized by higher mechanical properties. The Ti surface modification of the AK5M2 alloy after electron-beam processing in a mode using an electron beam energy density of 30 J/cm2 results in an increase in the strength characteristics. The parameters of this mode can be used for local hardening of parts made of this alloy, for example, bush bearings.

The paper studies the influence of anisotropy of properties and structural inhomogeneity on hardness and mechanical properties of titanium Ti-4Al-3 V alloy produced by wire-feed electron-beam additive manufacturing. Tensile and compressive strength testing of the alloy specimens determines its elastic modulus and strength properties at different points. VIC-3D digital optical system is used to study the mechanical properties of the material under stress. The fractography analysis explains the observed behavior of the material under different loading. It is shown that after the tension, specimens possess close values of mechanical properties in various directions, except for their bottom, where the structure changes due to partial mixing of deposited and substrate materials. Just the material plasticity changes notably in the volume, which is the highest in the growth direction. This is probably stipulated by the low number of barriers to the dislocation motion during tension. In compressive strength testing, constrained conditions for the dislocation motion in columnar grains provide a higher strength for specimens cut in the growth direction, than for those cut in the printing direction. All this will allow us to more accurately choose the hardening technology of such materials and probably recommend methods of fabricating small-sized parts.

Rebar coupling connections are widely used for joints, and it is necessary to get information about the stress field distribution on the coupling surface at uniaxial tension to characterize operation of such joints. Purpose: The aim of the work is to study the stress-strain state of rebar connections under tension, full-scale junctions of the type A500 rods, and the deformation influence on the steel microstructure of grade С1020. Methodology: Non-contact three-dimensional imaging system VIC-3D and digital image correlation and tracking for studying stress-strain state of rebar connection; transmission electron microscopy for studying the steel microstructure. Research findings: Load-displacement curves are suggested for the valve coupling, and three deformation stages are identified: 1) elastic deformation of the coupling connection, 2) parabolic hardening, 3) preceding the coupling connection destruction. The analysis of the strain field distribution on the coupling connection shows that at any time, plastic strain localizes in certain zones of the sample. The stress field evolution on the coupling connection correlates with the indicated deformation stages. The compliance of the rebar joint made of seamless hot-deformed tube with an outer and inner diameters 51 and 32 mm, respectively, made of С1020 steel grade, induces 500 MPa stress in the normal section of rebar under the tensile axial load. Value: It is shown that during uniaxial tension of 0 to 5 %, perlite fractures, which is accompanied by further polarization of the dislocation structure. The internal stress amplitude increases and at 5% tension, far-range stresses grow as compared with those induced forest dislocations. The main contribution to far-range stresses and their change at 5 % tension is made by the elastic component, that promotes to the microcrack formation.

The authors have presented results of uniaxial-tension testing of specimens of the layered composite "silumin/carbon-fiber-reinforced-plastic" (AK5M2/CFRP). AK5M2-grade silumin of hypoeutectic composition with the irradiation of the specimen′s surface by a pulsed laser beam was taken as the basic material. To create layered composites, carbon unidirectional fabric "CARBONWRAP Tape 230" produced at the Joint Stock Company Nanotechnological Center of Composites (NCC) was glued to the silumin surface. The binary epoxy compound "CARBONWRAP Resin 530+" produced at NCC was used as the binder. The uniaxial tension test of the specimens was implemented on an INSTRON 3382 testing machine at an extension rate of 0.3 mm/min. The evolution of deformation fields on the specimen′s surface was obtained using a VIC-3D digital optical system based on the method of correlation of digital stereoscopic images. From the testing results, the diagrams of deformation under uniaxial tension of the AK5M2/CFRP were constructed. The electron-microscopic image of the silumin surface layer was obtained by the scanning-electron-microscopy methods. An analysis of the structure of its influence on the physicomechanical properties was performed. An analysis of the strained state of the specimens was made by the patterns of distributions of longitudinal and transverse deformations in space and time.

The paper presents results of correlation analysis of longitudinal strain values at different times during uniaxial tensile loading of flat specimens of technically pure A7-grade aluminum. The factor analysis allows distinguishing several factors responsible for the coordinated change of surface deformations at different deformation stages. Three characteristic zones are identified for the correlation matrix and diagrams of factor loads, which are correlated with the stages on the deformation curve. The factors are described in accordance with the stages of the deformation process, and their interpretation is proposed through the initial variables: the distribution of deformation values over the sample surface and time.

This paper presents the results of uniaxial tensile tests on specimens of the hypoeutectic aluminum-silicon alloy A319. According to the results, the influence of surface treatment by pulsed electron beam on the mechanical properties of the material was determined. The peculiarities of deformation localization in the material caused by grinding of the surface layer material structure due to rapid crystallization during electron beam treatment were revealed. The surface treatment up to the depth of 100 µm leads to the formation of a fine dendritic columnar structure of silumin and to an increase in the plasticity of the samples. The influence of the surface treatment affects the increase in the deformation localization in the region of the stable concentrator before failure. The greatest increase in ductility and localization of deformation occurs during treatment with an energy density of 15 J/cm2. In the process of specimen deformation, unstable, metastable, and stable areas of plastic deformation localization are formed and replaced, and the formation of stable areas of localized plastic deformation, in which the specimen fails at the end of the test, can be detected at the initial stages of testing. In specimens, during the test in the zone of localized plastic deformation, bands are formed which pass through the entire surface of the specimen at an angle of 35 to 55 degrees to the tensile axis, and their development leads to the formation of stable zones of localized plastic deformation and to the failure of the specimen.

In this work, based on the multilevel approach, the features of the structure and properties of titanium alloy, formed during high-performance additive manufacturing by wire-feed electron beam technology, were studied. Methods of non-destructive X-ray control and tomography, along with optical and scanning electron microscopy, were used to study the structure at different scale levels of the sample material. The mechanical properties of the material under stress were revealed via the simultaneous observation of the peculiarities of deformation development, using a Vic 3D laser scanning unit. Using microstructural and macrostructural data, as well as fractography, the interrelations of structure and material properties caused by the technological features of the printing process and the composition of used welding wire were revealed.

The work presents the results of studying the effect of irradiation of the surface of hypoeutectic silumin with a pulsed electron beam on the mechanical properties of the material. Silumin of grade AK5M2 (Al–(4.0–6.0) Si–1.3 Fe–0.5 Mn–0.5 Ni–0.2 Ti–2.3 Cu–0.8 Mg–1.5 Zn) is used as a test material. To carry out uniaxial tensile deformation, double-sided proportional samples with heads are made. The results of studying the evolution of strain fields of layered composites silumin/carbon-fiber-reinforced plastic (CFRP) based on irradiated silumin in uniaxial tension are also presented. The carbon fiber is made of a filler (FibARM Tape-230 unidirectional carbon fabric) and a binder (FibARM Resin 530 two-component epoxy compound). The fracture surface of the samples is studied using scanning-electron-microscopy techniques. The dependences of the maximum and minimum values of strains in the localizers on the sample surface on the averaged strains over the working area of the sample are plotted. An increase (relative to silumin in the initial state) in the strength and plastic properties of both samples of irradiated silumin and of the silumin/CFRP composite is determined. The sawtooth character of the deformation curve of uniaxial tension of the silumin/CFRP composite material with a pre irradiated surface of the silumin plate is revealed.

Исследован силумин АК10М2Н в литом состоянии и после облучения импульсным электронным пучком (17 кэВ, 50 Дж/см2, 3 имп., 100 мкс, 0,3 с-1). Определены элементный и фазовый составы сплава. Изучены структура и поверхность разрушения методами сканирующей электронной микроскопии и просвечивающей электронной дифракционной микроскопии. Проведены механические испытания сплава методом одноосного растяжения плоских пропорциональных образцов на машине "INSTRON 3386" с постоянной скоростью. Показано, что облучение сплава АК10М2Н импульсным электронным пучком сопровождается плавлением сравнительно тонкого (до 100 мкм) поверхностного слоя. Последующая высокоскоростная кристаллизация приводит к формированию субмикро- и нанокристаллической многофазной структуры ячеистой кристаллизации. Установлено, что облучение электронным пучком литого сплава способствует увеличению предела прочности в 1,8 раза и относительного удлинения в 2,2 раза. Рассмотрены основные причины такого эффекта.

The work intends to detect and analyze regularities in the evolution of structure and properties of the hypo-eutectic silumin irradiated by a pulsed electron beam and subjected to the uniaxial tensile deformation on the example of plane samples. It has been revealed that the treatment of silumin by a pulsed electron beam brings about a submicron-na-nocrystalline structure forming in the conditions of high-speed crystallization in the up to 90 µm thick surface layer. The study has found out that microcracks originate and propagate in the untreated material mainly along the aluminum/silicon inter-phase boundaries. The surface layer in the silumin modified by a pulsed electron beam is identified to fracture because of microcracks to form and propagate along the boundaries of high-speed crystallization cells. The important outcome to emerge from the study is that the irradiated silumin tends to fracture at higher (by ≈1.85 times) applied stresses and higher (by ≈2.1 times) plastic deformation in comparison with the untreated material.

The surface layer of AK5M2 alloy is modified with a Ti film by the vacuum-arc method. The modified samples are irradiated by the method of electron-beam processing using five modes. The dependences of the crystal-lattice parameter and the phase composition of samples of the AK5M2 alloy with surface-modified Ti alloy on the beam energy density during electron-beam processing are determined. The defect substructure of the samples is studied by scanning electron microscopy. The dependence of the coating thickness on the energy density of the electron beam is revealed. The modes are determined, in which the electron-beam energy density is insufficient for the formation of a homogeneous coating. The most rational mode of electron-beam processing is established, in which a homogeneous layer with the least number of surface defects is formed.

The paper reports changes in strain fields on welded sample surfaces from commercial pure titanium, joined by both laser beam welding (LBW) and gas tungsten arc welding (GTAW) procedures, under uniaxial tensile loads. Their dynamics were investigated by the digital image correlation method using a ‘Vic-3D’ optical system. In addition, stress-strain curves were drawn in both σeng-εeng and σtrue-εtrue coordinates. It was shown that the laser welded sample was characterized by a higher ultimate tensile strength to yield point ratio than the as-received one. The GTAW sample fractured under much less stresses than the LBW one.

In this work, we studied the evolution and features of localized strain fields in porous SHS-TiNi samples. Using the Vic-3D optical system and spayed speckle patterns, a localized plastic flow on the surface of porous plates of 0.85 mm and 2.7 mm thick loaded up to fracture in a quasi-static mode was traced and characterized. As seen, a 0.85 mm thick specimen indicated two strain-hardening distinctive parts in the stress-strain curve. Moreover, regions of localized strain are found that be wider than that of a 2.7 mm thick sample. It can be argued that by combining speckle patterns and quasi-static tension, one can effectively explore and predict the deformation behavior of a designing bone substitute made of porous SHS-TiNi.

The features of evolution in space and time of distributions of deformation fields on the surface of the composite, reinforced with carbon tape, have been studied at meso- and macroscopic scale levels by method of correlation of digital images. The obtained pictures reflect in detail the evolution of distribution of isofields of relative deformations on the surface of composite, corresponding to different degrees of deformation action under uniaxial tension. Based on the results of the conducted studies of the carbon composite samples, numerical values of the strain concentration factor, expressing the ratio of the maximum value of deformations on the surface of the sample to the total average deformation over the entire working field of the sample, have been obtained to estimate the concentration of deformations. It has been established that the strain concentration factor is equal to 1.3 for the non-stressed carbon composite of carbon plastic tapes and 1.21 for the prestressed one. Modification of the carbon composite during prestress molding leads to a 22% reduction in stress concentration on the surface of the carbon composite, increases strength by 37.8%, deformation by 25% and modulus of elasticity by 10.25%.

The influence of pulsed electron irradiation on the deformation behavior of Al–10Si–2Cu–1Ni (wt