Effect of Process and Geometric Parameters on Residual Distortion of Ti-6Al-4V Body-Centered Cubic Lattice Structures in Laser Powder Bed Fusion

The advent of laser powder bed fusion (LPBF) has provided an effective solution for fabricating lightweight structures with intricate designs that cannot be realized using other manufacturing methods. Lattice structures, however, which feature unique characteristics, pose greater challenges in the LPBF process than solid structures and exhibit more significant distortion. The underlying mechanisms and influencing factors of this distortion remain unclear, presenting a significant research gap. This study investigates the generation mechanism of residual stress in Ti-6Al-4V lattice structures during LPBF and examines how process and geometric parameters influence residual distortion. Lattice-type cantilever structures with various arm thicknesses and strut diameters were fabricated using different laser powers and scan patterns. The residual distortion after removal from the building substrate was measured using a non-contact coordinate-measuring machine. The results suggest that increasing the arm thickness, reducing the strut diameter, and employing a scanning pattern with interlayer rotation effectively reduce residual distortion. Among these factors, the scanning pattern had the most distinct impact, differing significantly from those affecting solid structures. P2 (45°) scanning pattern resulted in the greatest residual distortion, approximately twice that of the least distorted pattern. Meanwhile, the laser power exerted a minor influence on the distortion of the lattice structures. These findings provide insights and guidance for fabricating lattice structures using the LPBF process, broadening its applications in aerospace, automotive, and other weight-sensitive industries.