Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg, Russia:

V. Sh. Sufiiarov, Leading Researcher, e-mail: vadim.spbstu@yandex.ru
A. A. Popovich, Professor, Director of the Institute of Metallurgy, Mechanical Engineering and Transport
E. V. Borisov, Post-Graduate Student, Researcher
I. A. Polozov, Student, Engineer

The microstructure and properties of the specimens of the Inconel 718 heatresistant nickel alloy produced by selective laser melting (SLM) were studied. The layer thickness, laser power, laser scanning speed and pass distance impact on the microstructure, porosity and phase composition of a compact specimen were studied. Varying the main technological parameters allowed to determine the values that provide maximum relative density of compact material. The study of microstructure of the obtained specimens allowed to estimate configuration of the solidified molten pools and their mutual arrangement. The height of these pools is more than the thickness of the layer which indicates of the significant remelting of the underlying lauer. The microstructure of the specimens represents directional columnar dendrite cells. The executed study showed distinctions between the initial powder material and compact specimens phase composition. These distinctions are caused by differences between metal cooling during the powder gas atomization and alloy laser treatment by the selective laser melting. There are also shown the distinction between phase compositions at different layer thickness which are the evidences of the alloy crystallisation under different conditions. Mechanical properties of the specimens made according to the selected process parameters were determined. The research allows to establish the influence of the specimens’ layer thickness during manufacturing on their strength and plastic properties. When using a thinner powder layer, strength properties are higher however the plastic ones are lower, compared to material obtained using thicker powder layers. Influence of the position of the samples on a base plate during manufacturing on their strength and plastic properties was also revealed. The horizontally grown samples show higher strength properties and lower ductility than the vertically built specimens.

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