JSC “Science and Innovations”, Moscow, Russia:

A. V. Dub, Professor, First Deputy Director General

Joint Stock Company “Research and Manufacturing Association “Central Research and Development Institute for Mechanical Engineering Technology”, Moscow, Russia:
V. V. Beregovskiy, Deputy Director General, Director of the Institute for Surface and Nanomaterials Technology (ISNT)
E. V. Tretyakov, Deputy Director of the ISNT for production planning work
S. A. Shchurenkova, Head of the Vacuum Coatings and Evacuating Equipment Laboratory, e-mail: svetastch@yandex.ru

Presented in the paper are the experimental investigations of the physical parameters (laser output power within the limits of 245-305 W, scanning speed within the limits of 605–1005 mm/s) of selective laser melting of a KhN45MVTUBR (ХН45МВТЮБР) EP-718 (ЭП-718) nickel alloy in the process of a layer-by-layer synthesis of the complex-geometry products with curved elements and honeycomb structures influence on surface roughness, dimensions and density of pores distribution in a grown layer. It is found that the porosity of the complex-geometry samples being studied in the sections parallel and perpendicular to the direction of formation, amounts to 0.58–3.18% depending on the energy density of laser irradiation value, laying within the limits of 244–504 J/m, and the surface roughness varies within the Ra 8.6–19.3 m limits as well. It is determined that surface roughness depends on the energy density of laser irradiation in the same manner as a porosity does as well as pores distribution by their size for different process modes of operation. It is defined that process modes of operation based on high speeds (up to 1005 mm/s) with the linear energy density of laser irradiation of 244–303 J/m cause formation of a great number of coarse pores which appear due to instability of a molten track at high scanning speeds. The process modes of operations based on scanning speed within the 605 mm/s limits leads to increase of the small pores (up to 10 μm) quantity as the linear energy density grows up to 405–504 J/m. It is established that the optimal process mode of operations of a KhN45MVTUBR (EP-718) alloy selective laser melting (SLM) for the complex geometry parts comprises the following parameters: laser output power of 275 W, scanning speed of 605 mm/s, hatching range of 120 μm, laser spot diameter of 80 μm, powder layer thickness of 50 μm, checkerboard scanning strategy.

The work was performed with financial support of the Ministry of Education and Science of the Russian Federation (the unique identifier of the applied scientific research is RFMEFI57915X0125).

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