Drilling process and resulting surface properties of Inconel 718 alloy fabricated by selective laser melting additive manufacturing

Abstract

One of the challenges is to produce holes with expected dimensional accuracy in metal additive manufacturing. Although post-processing is usually carried out for the additively manufactured components but improving the quality of the holes produced through additive manufacturing seems to be requirement. Otherwise, it is difficult to obtain expected quality for the holes in metal components. Therefore, this study focuses on drilling operation of Inconel 718 alloy fabricated by selective laser melting additive manufacturing. Specimens fabricated by selective laser melting (SLM) were drilled using carbide drill bit under various drilling conditions including cutting speed and feed values. The measured outputs were surface quality of drilled hole, surface topography, surface and subsurface microhardness, and microstructure. Obtained results were compared with the results from wrought Inconel 718. This study showed that drilling process helps to improve the surface quality of additively manufactured Inconel 718 by reducing the surface roughness. Besides, increased feed rate results in work hardening effect on the hole surface and eventually microhardness of surface and subsurface increases notably. © 2020 The Author(s).