A study on the microstructural evolution of a Ni-base superalloy (Allvac 718plus) was conducted to better understand how solutionizing temperature affects the final microstructure of solutionized and aged test samples. Four different solutionizing temperatures were used to obtain different fractions of gamma prime (γ’) and delta (δ) phase precipitates. This paper describes the solutionizing treatments and presents and analyzes the results of SE-SEM, EBSD, EDS, and XRD testing.

Laser powder bed fusion (L-PBF) is an additive manufacturing (AM) technique through which net shape/near-net components are built by selectively melting powder, one layer at a time, with a focused laser beam. The as-built microstructures have a great impact on the phase transformation and precipitation behavior during subsequent heat treatment. This study was directed to understand the effect of component thickness, in the case of complex shape components, on the microstructure, type of precipitates of L-PBF IN 718 in as-built and heat-treated conditions. Standard heat treatment cycles per ASTM F3055 and AMS 2774D were investigated. This work shows that microstructure, grain size, types of precipitates, and formed phases of components produced by L-PBF in the as-built condition and after heat treatment are profoundly different with different component thicknesses. In order to obtain the optimal microstructure and mechanical properties, specific heat treatments are necessary due to the complexity of the components produced.