Wire-arc additive manufacturing (WAAM) is considered as a rather promising alternative to conventional subtracting production process for manufacture of large expensive metal components with complicated geometrical shape. Up-todate direction of WAAM investigations is aimed on production of functional metallic components with complicated geometrical shape and high accuracy, surface processing and mechanical properties meeting the strict requirements of aerospace, automotive and instrumental industries. At the same time, structural application of metal components based on their mechanical properties is studied insufficiently. It is necessary to understand additionally influence of technological conditions (such as energy input, protective gas role, speed of wire feed, welding speed, facing features and its sequence etc.) on the thermal initial parameters and finishing mechanical properties. The paper displays that mechanical properties of low-alloyed silicon-manganese composition of C-Mn-Si type with ferrite-pearlite structure is higher comparing with conventional steel 09G2S. It is shown that impact strength values for C-Mn-Si-type composition, which id formed via WAAM method, is higher by 2 times in comparison with welded joints which are faced by Sv-08G2S wire.

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X-ray diffraction analysis is essential in studying stacking faults. Most of the techniques used for this purpose are based on theoretical studies. These studies suggest that the observed diffraction patterns are caused by random stacking faults in crystals. In reality, however, the condition of randomness for stacking faults may be violated. The purpose of the study was to develop a technique that can be used to calculate the diffraction effects of the axis of the thin plates of twin, new phases, as well as other variations in defective structures. Materials and methods. This was achieved through modern X-ray diffraction methods using differential equations (transformations and Fourier transforms) and the construction of the Ewald sphere, mathematical analysis, mathematical logic, and mathematical modeling (complex Markov chain). Conclusion. The study made it possible to develop a technique for the calculation of the diffraction effects of the axis of the thin plates of twin, new phases and other variations in defective structures. The technique makes it possible to solve several complex, urgent problems related to the calculation of X-ray diffraction for crystals with face-centered lattices containing different types of stacking faults. At the same time, special attention was paid to the correlations between the relative positions of faults. The calculations showed that the proposed method can help to determine the nature and structure of stacking faults by identifying the partial and vertex dislocations limiting them in twin crystals with a face-centered cubic structure of silicon carbide based on X-ray diffraction analysis.

Investigations of the structural components of rail joints, obtained by contact butt welding using burning-off, which are revealed on the surface of kinks after the destruction of the compounds during static bending tests and after destruction in operating conditions, were carried out. Analysis of the microstructure and chemical heterogeneity of the fracture surface was carried out with the help of a scanning electron microscope JEOL JIB-Z4500, equipped with an attachment for energy-dispersive analysis. The analysis showed that the main structural defects were poor penetration and inclusions of iron-manganese silicates that significantly reduced the parameters for mechanical tests of welded joints. Their presence in welded joints is unacceptable. Clusters of inclusions of aluminosilicates, so-called matte spots, and oxide films of a more complex composition are formed in the compound on the basis of non-uniformly distributed nonmetallic inclusions of the metal of the rail.