Effect of Infill Pattern on Impact Toughness, Microstructure, and Surface Roughness of Inconel 625 Built via Filament-Based Material Extrusion Additive Manufacturing

Abstract

Filament-based material extrusion additive manufacturing (FMEAM) is an additive manufacturing technique that uses 3D printing. Additive manufacturing could build parts with infill variations. Solid or triangular infill pattern could be selected as needed. The solid pattern will have the maximum material volume, while the triangular pattern will contain a triangular lattice structure that fills the voids in the volume so the material requirement is reduced. This is valuable in optimizing the requirements of metallic materials for mechanical properties without changing the surface shape. The alloy Inconel 625, which is very popular in the aerospace industry have been developed as a feed material of FMEAM. However, for developing rotating parts, such as turbine blades, impact toughness, surface roughness and microstructure need to be investigated. This research was conducted to determine the effect of the infill pattern on the impact toughness, morphology of surface fracture, microstructure of side surface and surface roughness with Inconel 625 material built using FMEAM. The Charpy impact test, s ASTM 23, with v-notch testing method and SEM with EDS were performed. The results showed that the impact toughness for solids was higher than the value for the triangular infill pattern. It was discovered that the cavities in the triangular lattice structure within the specimen reduced the impact toughness to 57.6%. Micropores and residual polymer trapped on the surface reduce impact toughness. However, the same surface shape on solid and triangular infill patterns with surface roughness of 2.44 and 10.03 µm is still feasible for manufacture.