Work

Thickness-dependent microstructural transition and mechanical response in thin-walled LPBF-printed Inconel 718 structures

Year: 2026

Type: article

Abstract: Thin-walled features are increasingly used in architected materials produced by laser powder bed fusion (LPBF), yet the influence of geometric thickness on microstructure, defect formation, and mechanical behavior remains poorly understood. This study investigates the effect of thickness reduction in LPBF-fabricated Inconel 718 samples using optimized parameters, with a focus on interlayer rotation and contour scanning. Comparison between bulk samples and thin beams of varying thicknesses reveals that decreasing thickness promotes grain refinement. Texture analysis revealed a strengthening of the < 100 > crystallographic orientation along the build direction. Density measurements and microstructural observations showed increased porosity in the thinnest features, with a keyhole-like morphology consistent with localized heat accumulation associated with short scan vectors and constrained thermal conditions. Fine grains were preferentially observed in the contour-scanned regions, whose relative fraction increases as thickness decreases. Tensile tests showed increased variability and reduced ductility in the thinnest specimens, together with a trend toward a higher mean yield strength, to which grain refinement may contribute. The present results demonstrate that the transferability of bulk-optimized L-PBF parameters and bulk-derived mechanical properties to near-limit thin features cannot be assumed without geometry-specific validation.

Source: Materials & Design

DOI: 10.1016/j.matdes.2026.117193