Tailoring the strength of inconel 718: Insights into LPBF parameters and heat treatment synergy

The enhancement of mechanical performance in Inconel 718 fabricated via Laser Powder Bed Fusion by optimizingprocess parameters and various post-processing heat treatments, such as double aging and hightemperatureisostatic pressing, are explored. Phase and texture evolution were characterized by high-energydiffraction electron backscatter diffraction analysis, showing a weak Goss-type texture in the as-built condition.Carrying out a homogenization annealing above δ solvus, e.g. at 1155 ◦C, suppresses its transformation intoδ phase and enables an aging treatment to achieve a controlled precipitation of γ’/γ’’ instead. MC-type carbideswere detected in different morphologies at grain boundaries and in the matrix. Linking the microstructuralchanges with trends in the tensile properties along three build orientations, i.e. horizontal, diagonal and verticalto the build platform, we show that texture and anisotropy in the as-built condition can largely be eliminated byan annealing at 1155 ◦C. The mechanical properties can be adjusted further by adding double-aging or varyingthe cooling rate after the solvus treatment. The findings reveal a clear correlation between optimized LPBFparameters, heat treatment strategies, microstructural evolution, phase distribution, and the resultant mechanicalproperties, which contributes to the development of tailored process chains for specific applicationrequirements.