Effect of substrate preheating and in situ cooling on dimensional accuracy, microstructure, and hardness of wire-arc directed energy deposition components

Abstract Arc-based directed energy deposition (DED-Arc) is a promising manufacturing technology on the rise in the industry. On the one hand, convincing process advantages, such as the possibility of sustainably producing complex and large-volume component geometries with comparatively high building rates, favor further industrial interest. On the other hand, there are still challenges, like the difficulty of controlling heat input and the intricate thermal history. The resulting temperature gradients and heat accumulations lead to inhomogeneous component properties and reduced process efficiency, which delays further establishment in the manufacturing industry. Therefore, implementing and developing concepts for thermal management in DED-Arc is necessary. The study examines how controlling the substrate temperature can affect the dimensional accuracy, microstructure, and hardness of DED-Arc components. Different preheating and in situ cooling strategies were developed based on numerical investigations, including a water-cooled in situ cooling unit, a cobot-guided inductor, and classical preheating approaches. The findings indicate that substrate tempering significantly impacts the penetration zone and heat-affected zone dimensions, layer widths, microstructure, and hardness profiles. A special combination of preheating and in situ cooling resulted in enhanced substrate bonding, uniform layer widths (4.0 ± 0.1) mm, and consistent hardness values (142 ± 10) HV due to a more uniform microstructure. These results indicate that integrated substrate plate tempering can significantly improve thermal process control in DED-Arc, supporting its further industrial establishment.