Session: 04-23-01: Process Development, Characterization, and Optimization for Additive, Subtractive, and Hybrid Manufacturing

Paper Number: 166144

Effect of Size and Shape Parameters on the Mechanical And Material Properties of Additively Manufactured Inconel 718 

Additive Manufacturing (AM) has become a cornerstone in modern engineering practices, offering new avenues for fabricating parts with intricate geometries and tailored material properties. Among the various AM techniques, Laser Powder Bed Fusion (LPBF) stands out due to its precision, scalability, and compatibility with high-performance alloys. This method enables the layer-by-layer construction of components by selectively melting regions of a metal powder bed using a focused laser beam. As a result, LPBF is uniquely suited for producing complex shapes that would be difficult or economically unfeasible using conventional manufacturing approaches.

In aerospace engineering, where performance, reliability, and efficiency are critical, LPBF presents substantial advantages. One material that continues to gain traction in this context is Inconel 718, a nickel-based superalloy renowned for its outstanding high-temperature strength, oxidation resistance, and corrosion resistance. These characteristics make it particularly valuable in jet engine components, turbine disks, and other environments subject to thermal and mechanical stress. However, the microstructure and properties of Inconel 718 produced via LPBF differ significantly from those produced through traditional methods like forging or casting, largely due to the rapid thermal cycles and directional solidification inherent to the LPBF process.

This study focuses on investigating the microstructural evolution and mechanical response of LPBF-fabricated Inconel 718 components. Using a combination of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and Vickers microhardness testing, we analyzed how the process parameters influence grain morphology, texture development, and localized mechanical performance. Initial observations revealed a columnar grain structure aligned in the build direction, with a high density of dislocations and fine cellular dendritic substructures due to rapid solidification rates. Vickers hardness values for the as-built samples ranged between 275 and 305 HV, reflecting variability in microstructural features and internal stress distributions.

To enhance mechanical performance and reduce structural heterogeneities, standard heat treatments were applied. These thermal cycles were designed to dissolve interdendritic Laves phases and promote the precipitation of γ′ and γ″ strengthening phases, which are known to improve high-temperature mechanical properties. Post-treatment analysis showed a significant improvement in hardness uniformity and microstructural refinement, with the formation of equiaxed grains and reduced residual stresses, suggesting better long-term mechanical stability.

The findings underscore the critical role of post-processing in optimizing AM-fabricated superalloys for real-world applications. They also highlight the importance of understanding the interplay between thermal history, phase transformations, and mechanical performance in LPBF-manufactured components. As the adoption of AM continues to expand in aerospace and other high-performance industries, such insights will be essential for developing robust qualification pathways and ensuring that printed parts meet rigorous operational standards. In conclusion, the integration of LPBF with advanced materials like Inconel 718 holds significant promise for next-generation manufacturing. However, achieving reliable and repeatable component performance requires not only precise control over the printing process but also informed post-processing strategies that can tailor the final microstructure to specific service requirements.

Presenting Author: Showmik Ahsan wright state university

Presenting Author Biography: Pursuing a PhD in Materials Science and Engineering. Finished Bachelors and Masters degree in Mechanical Engineering. Research field has been related to Additive Manufacturing of Metals

Authors:

Showmik Ahsan wright state university
Daniel Young Wright State University
Ahsan Mian Wright State University
Vignesh Asam Wright State University
Raghavan Srinivasan Wright State University