OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 1 2023 the production costs, due to a significant reduction in allowances for the final dimensional machining of workpieces [2]. At the same time, one of the main problems in the additive manufacturing made of copper and its alloys is the oxidation of interlayer boundaries, which significantly worsens the physical and mechanical properties of printed products. In this regard, three-dimensional printing should be carried out either in a protective gas or in a vacuum [3]. An important advantage of additive technologies is the ability to control the printing modes, which allows varying the melting conditions of the material in a wide temperature range. This is especially important in the manufacture of three-dimensional curved products and non-uniform wall thickness. Indeed, the thickness and height of the wall, as well as the total volume of the printed material, significantly affect the heat removal [4] and, accordingly, the formation of the melt bath. The wire-feed electron-beam additive manufacturing is carried out in a vacuum using a thin wire as a filament. This type of filament is less expensive than powder, which makes this technology less expensive. In addition, this technology allows the use of several wires to feed it into the printing zone in different ratios. As a result, it becomes possible to print new multicomponent alloys with different alloying elements, as well as alloys and composites from dissimilar materials [5–8]. The electron-beam additive manufacturing (EBAM) is used to obtain products from nickel heat-resistant alloys [9–12], intermetallic compounds such as TiAl [13–15], soft magnetic materials based on iron [16], aluminum alloys [17, 18], and magnesium alloys [19], as well as bronze [20, 21]. In the native industry, the silicon bronze grade C65500 is of the most common use. It is used in parts intended to chemical industry, aviation, automotive and shipbuilding industries. At the same time, its analogue is known containing ~7 wt.% Al and ~2 wt.% Si that is produced abroad. This alloy has higher performance characteristics compared to C65500. Therefore, obtaining analogues of this alloy is an urgent task. To solve it a technology of the multiwire electron beam additive manufacturing can be used, which is implemented by feeding two or more wires to the melt bath. In the context of obtaining alloys of the Cu–Al– Si system, it is possible to use an aluminum filament and feed it in the process of printing bronze in a ratio of 10:1, which should provide the required composition of the alloy. Previously, the multiwire electron-beam additive manufacturing was successfully used to obtain specimens from the C65500 alloy [22] and the alloy of the Cu–Al– Si–Mn system [23]. However, in the works known to date, the operational properties of this alloy, obtained using additive technologies, have not been fully investigated. The properties of alloys printed on the basis of silicon bronze with the addition of aluminum filament also remain unexplored. Varying the EBAM heat input, conducting the post-deposition heat and thermomechanical treatments as well as alloying the bronze with Al-Si alloys are in fact three different approaches to the structure modification, which are based on altering cooling rate, recrystallization and constitutional undercooling, respectively. The aim of the work is to study the structural and phase state, mechanical and operational properties of C65500 bronze specimens printed using electron beam additive manufacturing technology. Research methodology The thin-walled specimens were made using the electron-beam additive manufacturing as shown in Figure 1. Two groups of specimens were obtained by EBAM. The first one was made from wire C65500 with different heat inputs: mode 1 – 0.19 kJ/mm, mode 2 – 0.25 kJ/mm, mode 3 – 0.31 kJ/mm. Some of these specimens, with the most coarse-grained structure, were subjected to thermal (annealing at 850 °C) and mechanical treatment (compression deformation by 10 % and subsequent annealing at 850 °C), which made it possible to successfully change its structural state. More detailed information about the processing modes and the structural state of these specimens is given elsewhere [22]. The second part of the specimens was made using the multiwire technology. This approach was used to change the composition of specimens and assess the possibility of controlling its structure and properties, as well as to obtain an alloy of the Cu–Al– Si system with a composition close to foreign analogues (alloy C64200) used in aviation and marine engineering. To do this, two wires were fed into the melt bath so that
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