New roadmap solves a stubborn problem in 3D-printed jet engine parts
Engineers have cracked why 3D-printed superalloy components for gas turbines lose critical strength during manufacturing—and mapped out a heating schedule to fix it. The discovery matters because it could unlock cost savings and design flexibility for aerospace and power generation companies already betting on additive manufacturing for high-stakes engine components.
Originaltitel: Gamma prime formation in nickel-based superalloy IN738LC manufactured by laser powder bed fusion
<p>Complex components for high-temperature gas turbine applications require materials that offer a combination of excellent high-temperature strength and oxidation resistance. Nickel-based superalloys with high gamma prime (gamma)' volume fractions are particularly suited for these applications, especially combined with additive manufacturing for intricate geometries. Despite the complex thermal history that these materials experience during laser powder bed fusion (LPBF) processing, gamma'formation is suppressed when manufacturing IN738LC, which has a medium equilibrium gamma'content of about 40-50 vol%. This study follows gamma'formation in LPBF IN738LC during subsequent annealing treatments at temperatures ranging from 745 C-degrees to 865 C-degrees, creating an experimentally determined TTT (temperature-time-transformation) diagram. This diagram is largely based on scanning electron microscopy (SEM) imaging supported by Vickers hardness measurements and scanning transmission electron microscopy (STEM) bright field imaging. Atom probe tomography (APT) of the as-built material indicated nm-sized regions depleted in Cr and enriched in Ni, Al, and Ti, but show no characteristic superlattice patterns in TEM diffraction. APT and TEM diffraction analysis of material annealed at 850 C for 3 min confirmed the presence of the gamma'phase but indicated that gamma'had formed through spinodal decomposition instead of precipitation.</p>