Regulation of dimensional errors and surface quality of thin-walled components fabricated by blue laser directed energy deposition

The utilization of components fabricated by directed energy deposition (DED) faces certain limitations that hinder its widespread application. These critical challenges primarily include significant errors in dimension accuracy caused by the unreliable build-up of flowing powder and low surface quality arising from the interlayer cumulative effect and powder adhesion. The present study aims to comprehensively investigate the impact of process parameters and deposition height on the geometrical errors observed in the thin-walled structures fabricated by DED. By establishing a rational relationship between the dimensional error and the sample height, the mechanism underlying the influence of deposition height on printing stability and sustainability is eluci-dated. Furthermore, an innovative building strategy incorporating a variable speed is proposed to eliminate protrusions at the end of the components. The study also examines the surface roughness of inclined thin walls, revealing a correlation between roughness and both position and angle. The presence of adhering powder on the front side of the parts and the formation of a molten oxide layer on the backside result in a diminished impact of angle on roughness. Ultimately, the findings of this study are validated through the fabrication of a thin-walled axisymmetric curved structure, providing a guide for the printing of large special-shaped parts.