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This work deals with metastable and immiscible Cu-Fe alloys with different iron contents with a homogeneous microstructure were successfully prepared. Such a result was achieved using AISI 321 and C11000 steel and the multi-wire electron beam additive manufacturing. The samples under study were of different compositions with steel varying from 10 mass. % to 75 mass. %. The results showed that as the content of the second component increased, the volume fraction of stainless steel inclusions in the copper matrix increased, forming a heterogeneous melt. In the present work, a scheme of convective motion with diffusion elements in the melt pool at simultaneous feeding of two heterogeneous wires was constructed. During the melting process, the material with higher density occupies the lower position, displacing the less dense material to the upper part of the melt pool. Fluid phase separation processes due to surface tension also take place. After solidification, a heterogeneous melt is observed with the inclusion of copper in the steel matrix and steel in the copper matrix. After reheating, typical for electron beam additive manufacturing, secondary phases precipitate out of supersaturated solid solutions through the phenomenon of diffusion. [ABSTRACT FROM AUTHOR]

In the current work, samples of functionally graded materials based on steel and copper were obtained by wire-feed electron beam addition technique. The samples presented were characterized by a sharp and a smooth interface. To form the sharp interface, it was necessary to change the wire-feed from AISI 321 to C11000 immediately after finishing the N layer pass. Structure formation occurred through convective mixing and primary crystallization. Thus the formation of mechanical mixture on both sides of the sharp interface of functionally gradient material is observed. The width of the sharp interface does not exceed 100 µm. In order to form a smooth interface in the structure between the parts, it was necessary to gradually increase the feeding speed of the copper wire to the molten pool and decrease the feeding speed of the steel wire until it stopped completely. Structure formation in the material occurs through recrystallization and the formation of diffusion volumes, which leads to the presence of solid-phase diffusion. The width of the smooth interface between the components is from 6 mm, and this value can be increased by varying the wire feed rate ratios. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the transition layer structure of bimetallic samples based on the nickel heat-resistant alloy Udimet500 and the heat-resistant bronze CuCr1. When printing the bronze part on top of the nickel part, the nickel is melted and kneaded into the bronze part at a distance of up to 5 mm. When printing the nickel part on top of the copper part, the size of the transition zone does not exceed 2-2.5 mm. No cracks or discontinuities were detected at the boundary of the nickel and bronze areas. In the transition zone due to the formation of fine grain structure reinforced by nickel alloy particles the mechanical properties of the bronze increase, resulting in the destruction of samples outside the boundary part inside the bronze. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the influence of the degree of mutual solubility of metals and alloys in obtaining composite materials with a metal matrix on the organization of the structure. The studies show that for materials with different degrees of mutual solubility of components the organization of the structure differs significantly, which must be taken into account when making products with composite structure. Samples based on components with limited mutual solubility are most susceptible to cracking, especially with excessive formation of intermetallic phases. When obtaining composite materials based on alloys, formation of secondary phases is possible not between the main components, but between the alloying elements. The melting temperature and density of the components, which additionally determine the structure organization of the samples, also have a significant influence when obtaining composites. [ABSTRACT FROM AUTHOR]

The paper presents the results of structure studies and mechanical tests of samples with gradient structure obtained on the basis of pure copper and Ni80Cr20 nickel-based alloy using double wire-feed electron beam technology. The obtained data testify to the high strength of structural gradient zone in the majority of the investigated specimens. The formation of defects in the form of cracks and a decrease in the strength of the structural gradient zone is noted for a number of samples. The material of the gradient zone exhibits sufficiently significant heterogeneity of structure with the presence of large fragments of nickel-based alloy in copper matrix. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the structure and mechanical properties of M1 copper samples obtained by electron beam printing with the implementation in the process of drop formation printing mode. The studies show high heterogeneity and defectiveness of the obtained structures. Pores of different sizes and cracks are formed in the samples in large numbers. The material of the boundary zone is characterized by a low degree of mutual fusion of the sample and the substrate materials. Mechanical properties of the obtained sample are at a rather low level due to high porosity of the sample [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the structure and properties of CuCr1 chromium bronze samples obtained by wire-feed electron beam additive technology. Structural studies show that the material of the samples is represented by large grains, elongated in the direction of heat removal. Nera the substrate there is a mixing of steel into the bronze structure with the formation of a composite fine-grained structure. The mechanical properties of the obtained specimens show little difference when tested in the horizontal and vertical directions and generally show low strength values and high ductility. [ABSTRACT FROM AUTHOR]

The bimetallic samples were produced by wire-feed electron beam additive manufacturing. Layer-by-layer and drip methods were chosen for the production of bimetal. The features of the methods in the distribution of dissimilar materials on the surface of the longitudinal section are revealed on the vertical walls. So, in the longitudinal section of the sample produced according to the layer-by-layer method, there is a homogeneous distribution of dissimilar metals over the entire surface. In the longitudinal section of the sample, produced according to the drip method, there is a pronounced inhomogeneous distribution of dissimilar materials, with a predominant accumulation of steel. The presence of large (up to 6 mm) "drops" of steel and inhomogeneous distribution has a negative impact. The inhomogeneous distribution of the material in this case leads to an increase in surface energy. In turn, this leads to an increase in the deformation energy, and, consequently, the energy of the crack surface formation. [ABSTRACT FROM AUTHOR]

The paper presents the results of analysis of the structure in the fracture zone of bobbin tool type in friction stir welding of AA2024 aluminum alloy. The conducted research demonstrates the complex and heterogeneous nature of the plastic flow in the processing zone before tool fracture. Two types of fracture caused by different reasons are shown. In the fracture of the tool directly at the material inlet, a coarse-crystalline grain structure prevails in the stir zone. At the macro level, the stir zone appears as a coarse-dispersed cluster of unconnected fragments. With a relatively stable welding process with the destruction of the tool, after 150 mm of the joint, a stir zone is formed with an ultrafine-dispersed structure with an average grain size of about 1 µm, which is quite typical for stirring welding. The destruction in this case is presumably due to defects in the tool itself. [ABSTRACT FROM AUTHOR]

In the work samples of large-sized blocks made of C11000 copper were obtained by wire-feed electron beam additive manufacturing. Selection of parameters of electron beam printing technology made it possible to obtain products with mechanical properties corresponding to cast C11000 copper. Obtained samples had an inhomogeneous scale-like surface, as well as violations of the specified geometry formation were revealed. With the chosen printing strategy, these drawbacks can be eliminated by a more accurate selection of printing parameters. The most effective way to obtain blocks with a defect-free structure may be to change the scanning strategy. Despite the presence of geometric distortions, the mechanical properties of the copper samples are at the level of the properties of cast copper. However, anisotropy of properties is observed in the additively formed material. Close to the substrate, the mechanical properties of the copper increase significantly due to mixing with substrate material—steel and grain size refinement. [ABSTRACT FROM AUTHOR]

The paper is devoted to the study of microhardness anisotropy of Ti-6Al-4V samples produced by the wire-feed electron beam additive manufacturing. Samples for the study were fabricated in the shape of vertical walls using different heat inputs. Results have shown that the decrease of the heat input leads to a decrease in microhardness values despite the primary β-phase grain refinement. The microhardness anisotropy also differs based on the average heat input and may vary by more than 2 times. [ABSTRACT FROM AUTHOR]

The bobbin-tool friction stir welding (BFSW) process is effective for welding aluminum alloys whose properties are determined by the structural-phase state. In this work, the evolution of the tool inlet area microstructure during the friction stir welding with a bobbin tool of a 20 -mm-thick plate made of AA2024 aluminum alloy was studied. Specific features of the welded joint formation at the initial stage in the central region of the weld and the near-surface one under the shoulder have been revealed. Regularities of the joint densification and structural changes in the material have been determined. [ABSTRACT FROM AUTHOR]

The results of structural studies of the bimetallic samples Fe-Ti system and the polymetallic samples Fe-Cu-Ti system produced by the wire-feed electron beam additive manufacturing are presented. It was found that for the Fe-Ti bimetal in the additive part of the Add Ti-6Al-4V titanium alloy there are a large number of cracks, delamination and microcracks. This is due to the formation of brittle FeTi and Fe2Ti intermetallic compounds. Growth of intermetallides and their subsequent deformation in the process lead to material destruction. To solve the problem of embrittlement of the workpiece, two copper layers of Add C11000 were introduced during the manufacturing process between steel and titanium parts of Add SS 321-Add Ti-6Al-4V. Thus, for Fe-Cu-Ti polymetal, the dominant phase on the boundary Add C110000-Add Ti-6Al-4V area is intermetallic CuTi2. Cracks are interrupted when encountered with the Cu solid solution, which suggests a positive effect of Cu on containing the crack propagation. Microcracks observed in Add Ti-6Al-4V do not propagate further in the Cu + CuTi2 region, which indicates a lower cracking tendency of intermetallic phases of CuTi2 in comparison with FeTi and Fe2Ti intermetallics. Experimental studies have confirmed and showed that the use of an additional layer between different components in the wire-feed electron beam additive manufacturing also helps to produce a quality defect-free product from heterogeneous materials. [ABSTRACT FROM AUTHOR]

By the method of electron beam additive manufacturing with simultaneous supply of steel and copper wire filaments, the bimetal sample Fe-Cu was produced. The simultaneous feed of filaments allowed to form a gradient transition from the steel part of the stainless steel 304 to the copper part of the C11000. The macrostructural study of gradient transition showed the presence of heterogeneous distribution of steel and copper particles. The microstructural study revealed that the Fe-matrix alloyed with Cr and Ni forms copper particles ranging in size from 130 nm to 2.3 µm. Interphase boundaries are sharp without transition areas. In some areas of the sample, a moire contrast of up to 200 nm wide can be observed around the copper particle. The copper particles have the regular spherical shape, which is due to the force acting on the length of the phase contact to reduce the surface to a minimum under interphase tension. This is evidence that during crystallization of austenite copper was in a liquid condition and had droplet shapes. [ABSTRACT FROM AUTHOR]

Additive manufacturing of copper and steel gradient materials by electron beam freeform fabrication is a novel exploration. C11000 copper was deposited on 321 stainless steel in the experiment. The homogeneity of the microstructure and chemical composition of materials has been characterized at the macro- and micro-scale, using optical microscopy. At the macro level, defects in the type of pores and cracks in the final product were revealed. In order to ensure satisfactory strength characteristics of the product with alternating layers of heterogeneous materials as a whole, it is necessary to optimize the technology of additive manufacturing with the reduction or total elimination of factors influencing the formation of defects. In the present work the structure formation of Cu-Fe polymetallic samples is studied at gradual decrease in supply of stainless steel and increase in supply of copper. [ABSTRACT FROM AUTHOR]

At present the development of the basis for the formation of structures with specific properties by electron-beam additive metallurgy is currently important. Mechanical properties of additively manufactured products directly depend on the quality of the surface, so the presence of defects affects the strength of the entire structure. To obtain the wall-shaped samples from 321 stainless steel the electron-beam 3D-printing was used. As a result, 3D-printing samples were obtained with optimal mechanical properties. It is established that electron-beam additive manufacturing has no negative influence on mechanical properties and structure of studied material [ABSTRACT FROM AUTHOR]

In the paper, the formation of the gradient structure of the sample from 321 stainless obtained by the electron-beam additive manufacturing method is researched. For obtaining a high-quality product by the method of additive manufacturing, it is necessary to define possible values of electron-beam 3D-printing parameters. The macrostructure images show the layers of printing, but it is difficult to differentiate the individual elements of the sample structure. Upon further investigation, differences in the microstructure in the direction of sample growth in the next layer were revealed. According to X-ray analysis, the final sample obtained by electron-beam 3D-printing is in two-phase state: α- and γ-Fe. The proportion of the α-Fe phase in the lower part of the sample is 4.2 % higher than in the upper part. This indicates a recrystallization growth of the grain structure of the material. [ABSTRACT FROM AUTHOR]

In the paper, the quality of stainless steel products formation by the electron-beam wire-feed additive manufacturing method was studied. AISI 321 austenitic steel was selected as the material under study. As a result of the research, it was found that two main factors influence the quality of the obtained products. The first factor is the geometrical parameters of the printing process, the disruption of which leads to the deviation from the axis of fabrication. The second factor influencing the quality of steel products is the parameters of the electron beam. Incorrectly selected beam currents or accelerating voltages can lead to changes in the thickness and height of the product walls. [ABSTRACT FROM AUTHOR]

In this work, the fracture features of a titanium alloy Ti-6Al-4V samples obtained using the electron beam wire-feed additive manufacturing have been investigated. Studies have shown that the main character of sample fracture is viscous, with an in-grained dimple rupture observed. The strongest samples are characterized by the absence of defects in the fracture structure. For some samples, there are pores with sufficiently large sizes. Sample tests show a low dependence of mechanical properties on the direction of the applied load. Mechanical properties of the whole series of samples vary within the range of 3 – 6 %. [ABSTRACT FROM AUTHOR]

Al-Mg alloys are susceptible to hot cracking, porosity and oxide film formation during additive manufacturing (AM). At the same time, vacuum technology avoids environmental influences and thus protects against the formation of oxide films. One of the known vacuum additive technologies is electron-beam AM, which efficiency is higher in comparison with laser additive technologies. The efficiency of electron-beam technology is explained by higher electron energy absorption by aluminum alloys, while the absorption of laser radiation is very low. In this work, electron-beam wire additive technology is applied to the AA5083 aluminum-magnesium alloy. The macrostructure of the produced specimen has been studied. It is shown that the microhardness along the building direction are not constant, but linearly decrease as the specimen grows. It is also shown that AA5083 alloy is very sensitive to energy investments in the electron beam printing process. [ABSTRACT FROM AUTHOR]

Laser-arc hybrid welding (LAHW) is a promising method of producing welded joints. A distinctive feature of the LAHW process is the interaction of two heat sources in a single melt welding pool. With the help of LAHW it is possible to weld thick-walled metal workpieces in one pass without edge cutting, as well as at higher speed than conventional arc welding. Investigation of welds on the example of 321 stainless steel is very important in welding production. The purpose of this paper is to investigate the structure and mechanical properties of weld metal in laser-arc hybrid welding. Based on the research and the data obtained, it can be concluded that the weld metal structure is heterogeneous. Tests on the tensile strength of the weld metal indicated differences between the arc and laser melting zones. The results of mechanical tests also revealed seam metal anisotropy in mutually orthogonal directions. [ABSTRACT FROM AUTHOR]

In the present study, samples of products from nickel-based superalloy were obtained by wire-feed electron beam additive technology with various value of beam current and printing velocity. It was shown that defects inherent in cast materials (freckles and block structure) and materials obtained by powder-bed additive manufacturing (shrinkage and homogenization porosity) are uncharacteristic of wire-feed additive manufacturing. Also, the dependence of the different defect formation (peeling of the deposited material from the substrate, cracking and porosity in the area of the intensive mixing of the substrate with nickel-based superalloy, presence of cracking on dendrites colony boundaries) on parameters of additive growing is shown. [ABSTRACT FROM AUTHOR]