Characterization of Additively Manufactured parts of Inconel 718

This research focused on characterizing an Inconel 718 (IN718) nickel-based super alloy fabricated via Direct Metal Laser Sintering (DMLS), specifically examining the impact of homogenization, solution, and aging treatment on grain structure, crystallographic texture, precipitate formation/dissolution, and material hardness. Studies have revealed that as-printed IN718 exhibits a microstructure defined by extremely fine columnar or cellular dendrites with laves phase precipitates forming at both grain boundaries and inter-dendritic areas; this contrasts with the microstructure of cast materials and necessitates a unique heat treatment regimen distinct from conventional methods. The findings indicate that the homogenization process at 1080°C, combined with solution treatment at 980°C, as well as aging treatment at both 720°C and 620°C, is sufficient to drastically alter the grain structure as printed and eliminate the segregates and Laves phase, resulting in noticeable modifications to the crystallographic texture and grain structure. The hardness level rose by 51-72% relative to the as-printed state, and this increase was largely caused by the formation of γ', γ" phases within the γ-matrix, which occurred following the heat treatment. This study conducts a thorough examination and analysis of the as-built sample and the sample treated with heat under various conditions, such as the laser power, scanning speed, and layer thickness, which are established to govern the manufacturing process and subsequently dictate the microstructure, ultimately affecting the mechanical properties, including the tensile strength, yield strength, impact strength, and hardness.