レーザー粉末床溶融結合法で積層造形したカンチレバー試験片における残留応力と反りの関係

抄録

Laser Powder Bed Fusion (PBF-LB) is widely used to fabricate complex geometries. However, simple evaluation methods, such as monitoring the warpage of cantilever specimens, are required due to residual stresses generated during the process. In this study, cantilever specimens of Inconel 718 alloy were fabricated by PBF-LB to investigate the relationship between residual stress and warpage. Surface residual stresses were measured using X-ray diffraction. Finite element analysis (FEA) was used to estimate the initial residual stress from the measured warped shapes. The results showed no simple correlation between surface residual stress and maximum deflection. However, under the same volumetric energy density (VED), deflection and residual stress displayed a linear relationship. Further, the through-thickness residual stress distribution, modelled as a fifth-order polynomial, closely matched the experimentally measured deflection. The analysis suggested that the curvature in the stress profile depends on the heat input, characterized by VED. These findings show that cantilever-based warpage measurements can serve as a practical screening method for evaluating residual stress in LPBF parts.