Experimental investigation of porosity distribution in selective laser melted Inconel 718

Abstract

This paper reviews the mechanisms of pore forming in additively manufactured metals and presents the statistical analysis of porosity and its distribution in selective laser melted Inconel 718. Samples were printed at different combinations of laser powers and scanning speeds. Printed samples were sectioned, ground, and polished for porosity study. Imaging techniques captured the pore profile and distribution at different region for comparison: from inside to outside and from bottom to top of a sample. Although a linear energy density of 350 J/m significantly reduced porosity in a sample, choosing different combinations of power and scanning speed for the same energy density produced different results in porosity. Pore density at the periphery of a sample was about 3-20 times denser than that in the interior. Finish machining with at least 200 µm depth of cut was recommended to enhance surface finish, control dimension and tolerance while removing the high density porosity layer.