Samara State Technical University, Samara, Russia

D. A. Dunaev, Engineer at the Department of Casting and High-Performance Technology, Postgraduate Student, e-mail: dimjkee830@gmail.com
S. S. Zhatkin, Professor at the Department of Casting and High-Performance Technology, Candidate of Technical Science, e-mail: sergejat@mail.ru
K. V. Nikitin, Professor at the Department of Casting and High-Performance Technology, Dean of the Faculty of Mechanical Engineering, Metallurgy and Transport, Doctor of Technical Science, e-mail: kvn-6411@mail.ru
E. A. Minakov, Assistant Lecturer at the Department of Casting and High-Performance Technology, Engineer, e-mail: goodspik@yandex.ru

This paper describes the results of a study that looked at the structure and properties of arc additive manufactured Al – Si alloy. The surfacing was performed using Sv-Ak5 wire in standard pulse mode and in coldArc mode in an upgraded 3D printer. The arc currents of 60, 70 and 75 А were applied. The authors looked at how the different surfacing modes influenced the dimensions, microstructure, gas porosity and mechanical properties of surfaced specimens. It was found that in both modes the rising current strength leads to increased dimensions of a specimen. The surfacing width becomes bigger due to melt spreading. In the сoldArc mode such deviations are smaller. As the current strength rises, the cooling rate drops leading to larger sizes of α-Al dendrites. Maximum sizes of dendrites are typical of the middle zones of the built-up layer, whereas minimum size dendrites can be found in the bottom zones. This can be attributed to the fact that when building the first layer heat dissipates mainly through the substrate thus ensuring high cooling rates. At the same time, the middle layer is built when the heat dissipation and cooling rates are lower, which explains the larger α-Al sizes. It was also established that smaller dendrites are formed in the layer structure in the сoldArc mode compared with the standard pulse mode. A rise in the arc current to 75 A leads to a reduced cooling rate making the liquid phase stay longer. This explains a risen concentration of gas pores per unit area. The highest concentration of gas pores can be found in the middle zones of surfaced specimens. When applying either the standard pulse mode or the сoldArc mode, the surfaced specimens manifest almost identical mechanical properties.
Support for this research was provided by the Russian Science Foundation under Project No. 23-29-10195.

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