| Title |
Effect of Unit Cell Size on the Compressive Deformation Behavior of Inconel 718 Lattice Structures Fabricated by Laser Powder Bed Fusion Process |
| Authors |
강태훈(Tae-Hoon Kang) ; Holden Hyer(Holden Hyer) ; 손용호(Yongho Sohn) ; 이기안(Kee-Ahn Lee) |
| DOI |
https://doi.org/10.3365/KJMM.2025.63.11.863 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
3D lattice structure; Inconel 718; Laser powder bed fusion; Mechanical property; Deformation behavior |
| Abstract |
This study investigates the mechanical behavior and deformation characteristics of Inconel 718
lattice structures with different unit cell sizes fabricated by laser powder bed fusion (LPBF). Two bodycentered
cubic (BCC) lattice structures with unit cell sizes of 2 mm (BCC 2) and 4 mm (BCC 4) were
designed while maintaining a constant strut diameter. The measured relative densities were 31.48% for
BCC 2 and 8.67% for BCC 4, indicating a significant reduction in density as the lattice size increased.
Although the relative densities differed considerably, both lattices exhibited similar microstructural
features such as columnar grains, melt pool boundaries, and surface-attached partially melted powders. No
distinct thermal influence was observed with varying unit cell size, demonstrating that uniform build
quality was maintained regardless of geometric scale under the given LPBF conditions. Compressive testing
revealed that BCC 2 exhibited substantially higher compressive strength (58.47±3.23 MPa) than BCC 4
(1.78±0.11 MPa), which was attributed to enhanced structural stability and a higher number of struts and
nodes. Digital Image Correlation (DIC) analysis and cross-sectional microstructure observations confirmed
that BCC 2 displayed progressive densification and buckling-dominated deformation, while BCC 4
predominantly exhibited bending-dominated failure with localized deformation. Notably, despite the
narrower strut spacing in BCC 2, no discernible thermal influence?such as melt pool distortion or grain
coarsening?was identified, indicating that the effect of unit cell size on thermal behavior during LPBF
processing remained negligible under the given conditions. These findings were discussed in terms of the
effects of lattice unit cell size on microstructure, compressive properties, and deformation behavior. |