Heat and convection pattern of the melt pool generated by DED on tilt surfaces

Abstract The convective evolution within the melt pool is crucial in directed energy deposition (DED), especially on inclined substrates, which are less studied compared to horizontal surfaces. This study presents a comprehensive CFD model to investigate melt pool dynamics across various tilt angles, integrating heat and mass transfer, surface tension, and gravity-driven convection. A critical threshold angle between 60° and 90° was identified, where the dominant convective mode shifts from Marangoni-driven to gravity-driven flow, significantly influencing the height and shape of the deposited layer. Specifically, the deposited layer height decreases at angles up to 60° but increases again as the substrate approaches vertical orientation. Additionally, the evaporation pattern and fluid flow behavior are altered by substrate inclination, impacting the melt pool’s temperature gradient and tension gradient. These findings enhance the understanding and optimization of DED processes on inclined surfaces, providing valuable insights for improving deposition quality in complex geometrical scenarios.