Development of post-treatment for enhanced performance of an additively manufactured Alloy 718

The post-processing of additively manufactured components is key to optimizing the microstructure of the as-built condition to improve certain mechanical properties. When Alloy 718, a nickel-based superalloy, was manufactured using laser powder bed fusion (LPBF) and subjected to the standard post-processing thermal treatment for wrought Alloy 718, an excessive formation of delta (delta) phase particles, which could compromise the mechanical integrity of the manufactured part, was observed. To address this, both experimental and calculated time-temperature-transformation (TTT) diagrams, along with precipitation kinetics for the formation of delta phase particles, were carefully studied and analyzed to develop a new and effective thermal post-processing treatment. This new heat treatment resulted in a moderate precipitation of delta phase particles. Furthermore, the mechanical property in terms of the microhardness value of AMed Alloy 718 subjected to this new treatment was found to be comparable to that of the wrought material treated with the recommended heat treatment.