Akademik Veri Yönetim Sistemi
Russian Journal of Non-Ferrous Metals, cilt.66, sa.4, ss.165-176, 2025 (SCI-Expanded, Scopus)
Abstract: Laser Powder Bed Fusion (L-PBF)—an additive manufacturing technique—enables the manufacturing of high-resolution, complex geometries. However, the process’s steep thermal gradients induce residual stresses that can negatively impact material properties and part performance, often causing cracking, deformation, or compromised component geometry. Consequently, measuring and controlling these residual stresses is essential for successful L-PBF. Several studies have attempted to quantify residual stresses by designing geometries that deform predictably, including the Bridge Curvature Method (BCM). BCM is an indirect measurement approach that evaluates post-production distortion or warpage. It involves cutting a specially designed bridge-type specimen from its substrate, thereby releasing internal stresses and causing physical deformations measured as curvature changes. The magnitude of this curvature correlates with the thermal stresses experienced during fabrication. In this study, we investigate how laser power, scan speed, scan patterns, and second melting strategies affect residual stress and porosity in L-PBF-produced Ti6Al4V bridge-type specimens. Three distinct scan patterns—bidirectional laser scanning (zigzag), unidirectional island scanning (Chessboard 1), and bidirectional island scanning (Chessboard 2)—were each tested in both single-scan and double-scan (second melting) variations. Distortion in the specimens was quantified using BCM and correlated with residual stress levels, while relative density measurements based on Archimedes’ principle were used to determine porosity. The results were analyzed using ANOVA, providing insights and recommendations on how scanning strategies and laser parameters influence residual stress and porosity in Ti6Al4V. As a result, to minimize distortion, the Chessboard 1 strategy is most effective with single pass scanning at a scan speed of 800 mm/s. In contrast, to reduce porosity, the bidirectional scanning strategy yields optimal results with a laser power of 160 W and a scan speed of 900 mm/s.