Adaptive laser power planning via simulation for thermal regulation in LDED of IN718 thin-walled structures

Thermal accumulation phenomenon occurs during the continuous layer-by-layer manufacturing process of components fabricated via Laser Directed Energy Deposition (LDED), which leads to issues such as deteriorated forming performance. Molten pool temperature can well reflect thermal accumulation during manufacturing, molten pool fluidity, as well as influence post-manufacturing forming and performance characteristics. This paper presents a simulation-driven, restart-enabled laser power planning strategy for the regulation of molten pool temperature during the laser directed energy deposition process. Through numerical simulations, the spatial distribution of laser power has been optimized to avoid thermal accumulation during the printing process. This strategy employs two incremental PI controllers incorporating a restart mechanism, which uses iterative feedback within the finite-element simulation to generate a precomputed, position-dependent laser power schedule to achieve precise control over the molten pool temperature. This numerical model-based deposition strategy can not only control the temperature value around the target value but also realize flexible control of temperature fluctuations according to different production requirements. A comparison was conducted on the molten pool temperature, forming quality, and mechanical properties of IN718 superalloy deposited under the two modes (the simulation-planned variable-power deposition and conventional constant-power deposition). For the investigated IN718 thin-walled structure, the control mode reduced the top-region surface roughness from 27.87 ± 1.11 μm to 13.58 ± 0.89 μm and decreased the representative substrate warpage angle from 2.9° to 1.9° compared with the conventional mode, while maintaining higher average tensile strength. These results indicate that the simulation-planned laser power profile can mitigate heat accumulation and improve the macroscopic forming quality of the deposited thin-walled structure.