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Electron beam wire-feed additive manufacturing is given less attention in research community compared with other additive manufacturing methods, despite it allows higher deposition rate and less porosity. However, both gas and shrinking porosity are still met even with this method especially if applied to light alloys. The excess heat input may be the reason for evaporation of volatile metals, and forming the gas pores especially in the top layers of the built sample where cooling rate is reduced. Therefore, exponential decay heat input was used to grow AA5356 samples. Microstructural and mechanical characterization of the samples obtained at mean low, medium, and high heat input levels was carried out. An optimal heat input gradient was determined which allowed growing a defect-free metal in the bottom part of the sample and forcing out the shrinkage cavities to the top part. Shrinkage and gas pore structure formation was analyzed as a function of the heat input gradient and along the building direction. Gas pores resulted at two higher heat input regimes as a result of evaporation of magnesium as supported by the results of EDS and XRD. Tensile test showed the ultimate strength of the defect-free part equal to that of the base AA5356. [ABSTRACT FROM AUTHOR]

The paper is devoted to studying two different ways of obtaining the complex-shaped bell-type samples from the titanium alloy Ti-6Al-4V. It is shown that the process of obtaining the samples on a three-axis table is sensitive to the wire feed geometry as depended on four such geometry zones. These zones are characterized by the angles between the wire feed direction and the tangent to the printing path. On the contrary, samples obtained on a rotary four-axis table are not sensitive to the wire feed geometry. Each of the two ways provides formation of its own specific types of the structure and different mechanical characteristics. In this paper, the structure of geometry affected zones is determined and the most optimal way for obtaining the samples is selected. [ABSTRACT FROM AUTHOR]

Multipass friction stir processing was applied to AA2024 8-mm-thick samples with the goal of studying the microstructural evolution of the metal processed. Up to three parallel FSP tracks with an overlap of 0.375 between the neighboring ones have been obtained on the samples and then characterized for microstructure and mechanical strength. Clear macroscopic zones between the tracks have been observed. The specificity of microstructural evolution in the fine crystalline part of the thermo-mechanically affected zone formed close to the stirring zone is its over-aging due to less intensive strain dissolution of precipitates as compared with that of the stirring zone. The minimum hardness zone is formed there while higher hardness is observed in the less deformed part of the zone due to S(S′) (Al2CuMg) precipitates. The thermo-mechanically affected zone formation was considered from the viewpoint of tribology when the stirring zone metal flow slides over the thermo-mechanically affected zone metal and deforms it. [ABSTRACT FROM AUTHOR]