INFLUENCE OF TECHNOLOGICAL PARAMETERS OF SLM-PROCESS ON POROSITY OF METAL PRODUCTS

摘要

Selective laser melting is one of the modern methods of manufacturing parts and assemblies of complex geometry, which are difficult or impossible to reproduce in the conditions of traditional production. The problem of this production is that product quality depends on many factors, which can be divided into such main groups as equipment, material, process, part, finishing. The influence of the specific energy density of scanning the heat-resistant alloy Inconel 718 on the 3D printer Alfa - 150 (ALT Ukraine) of the Ukrainian production was investigated. The influence of SLM - technology parameters on the quality of final products is shown and the analysis of the influence of technology factors on the quality of finished products is performed. As a result of metallographic examinations, it was found that the distance between the laser passes, at which the estimated overlap of a single track is 25%, the conditions of deep penetration are created, large elongated pores are formed at the root of the track, which are formed by collapsing holes (so-called keyhole). At the estimated overlap of a single track of 17% a small number of small rounded pores is formed. At the calculated overlap of 0... 8%, a structure with a minimum number of pores is formed. When the distance between the passages of the laser exceeds the width of a single track at a given combination of power and laser scanning speed, the cases of partial fusion of adjacent tracks are observed, pores with sharp edges are formed, which are stress concentrators - the most dangerous in terms of product reliability. Thus, a rational overlap of tracks during selective laser melting, which ranges from 0 to 8% of the width of a single track at specific process parameters.