Mechanical and Microstructural Investigation of Nickel‐Based Superalloy IN718 Manufactured by Selective Laser Melting (SLM)

Selective laser melting, a quite new layer‐wise manufacturing process for metals, is used for processing the nickel‐based superalloy IN718. The objective of this work is to compare the microstructure and the mechanical properties of the produced specimens, directly after the manufacturing process and additionally after two diverse heat treatments subsequent to the manufacturing process. As the resulting microstructure and properties for specimens manufactured by selective laser melting are directional, all investigations are made for specimens oriented vertically and horizontally. Optical, scanning, and transmission electron microscopy are carried out in order to characterize the microstructure explicitly. For investigating the texture of the material, additional EBSD measurements are undertaken. Mechanical tests include tensile testing at room temperature and at elevated temperatures and hardness measurements. The investigations reveal a very good quality of the SLM‐produced specimens. Nonetheless, differences in the grain sizes, the orientation, and especially in the precipitation behavior could be found.