This paper presents studies about the influence of the surfacing mode on the formation of defects in the deposited metal produced by WAAM using Al-Mg alloy. As the main parameters that affected on the surfacing mode were the travel speed and the frequency of current pulses. Graphs about an influence of the travel speed on a size of pores and an influence the frequency of current pulses on a specific area of pores were constructed. It was concluded that with increasing of the surfacing speed, the size of defects decreased. Increasing the frequency of current pulses affected on increasing the specific area of pores. Changing the frequency of the current pulses leads to a change in the metal transfer. When using large-drop transfer metal, the defect concentration is minimal, but when using small-drop transfer, the arc stability decreases, which contributes to a higher pore concentration in the deposited metal.

Three brands of special electrodes for underwater welding were analyzed: LKI-1P, EPS-AN, UW-EZ-2. Experimental data on welding and processing behavior of these types of electrodes in the conditions of underwater arc welding were obtained: melting factor, metal deposit factor and losses. Experiments have been performed to determine the value of the arc breaking length of electrodes when welding under water. A comparative analysis was made with UONII-13/55 electrodes when welding in air conditions.

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