Qualification of repair and remanufacturing operations through DED technology of Ti6Al4V parts

Qualification of repair and remanufacturing operations through Directed Energy Deposition (DED) offers a sustainable pathway to restore and even enhance the performance of high-value metallic components. By employing Additive Manufacturing (AM) techniques to deposit material onto damaged parts, this approach minimizes downtime and extends the lifecycle of critical components such as molds, dies and tooling. However, integrating newly deposited material with the original substrate poses challenges in terms of residual stress formation, distortions and alterations of the microstruc-ture. In this study, qualification is addressed from two interrelated perspectives: (1) the qualification of the component—ensuring dimensional accuracy, minimal residual stresses and preserved metal-lurgical integrity; and (2) the qualification of the DED process—focusing on buildability through optimized power supply, scanning speed and dwell times. Since extensive experimental testing on high-value parts is impractical and often destructive, simulation studies are the only viable means to qualify repair operations. A dynamic power control strategy is developed to maintain a consistent melt-pool through closed-loop power control based on simulation feedback. The approach is validated through finite element simulations and an experimental campaign used primarily for calibration purposes. Results reveal that, while modulated power and/or dwell time control effectively stabilize the melt-pool and reduce heat accumulation, it may lead to higher inter-layer residual stresses due to increased thermal gradients, while microstructure uniformity and hardness distribution improve. These findings highlight the trade-offs inherent in power modulation for DED-based remanufacturing and provide valuable insights for optimizing both process parameters and qualification strategies in repair operations.