Optimization Path for LB-PBF Manufactured Structures of Inconel 738 LC

Inconel 738LC is a high temperature alloy with a high content of gamma prime precipitates to improve its high temperature creep strength. This type of material is difficult to process in Additive Manufacturing by Laser Based Powder Based Fusion (LB-PBF), also referred to as Metal 3D Printing, due to its inherent tendency to form microcracks during the laser-based processing. This paper reviews a systematic approach to mitigate the crack formation in 738 type compositions for LB-PBF by varying the alloy chemistry, the processing conditions, and the necessary heat treatments. Hereby the heat treatments are not only used to perform a solution annealing and a precipitation treatment for the alloy but also to coarsen the grain structure which, in the as-3D-printed condition, is significantly finer compared to an as-cast material status.