Abstract
Laser directed energy deposition (DED) is a multi-physics process that accompanies mass flow, energy transfer, and complex phase transitions. The printing characteristics of small size parts are significantly affected by the progressive variations of the temperature fields and the fluid flow within the molten pool. In this work, the deposition characteristics during multi-layer and multi-track laser DED were explored through a well-tested phenomenological model and corresponding experimental results. The variations of the build profiles and the decoupled track and layer profiles were systematically examined. Moreover, the printing characteristics of the builds with different scanning lengths were compared. Results showed that the multi-layer and multi-track transient deposition processes generated a significantly wavy surface profile. Compared with the long scanning length part, the beginning region of the short build produced an obvious bulge followed by sharply decreased height along the scanning direction. The transverse section of the short build varied significantly at different positions. Two adjacent columns of tracks were extracted from the overall build, demonstrating that the tracks tilted outwards and the angle increases along the scanning direction. The 3D numerical model was validated with corresponding experiments for builds with various layers. The scientific findings from this work can provide useful insights for the understanding of the additive mechanisms during laser DED for the precise shape control of small size parts.
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Acknowledgements
This work was financially supported by the Development of a Verification Platform for Product Design, Process, and Information Exchange Standards in Additive Manufacturing (No.2019-00899-1-1), the National Natural Science Foundation of China (No. 51805267), the Natural Science Foundation of Jiangsu Province (No. BK20180483), the Fundamental Research Funds for the Central Universities (No. 30921011202), and the fund of the State Key Laboratory of Solidification Processing in NWPU (No. SKLSP201830).
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Hui-liang Wei Ph.D., Professor. His research interests mainly focus on additive manufacturing of metallic materials. Prof. Wei has made significant progresses in the exploration of process-structure-properties correlations of powder bed fusion and directed energy deposition of diverse materials. He has developed advanced mechanistic and machine learning models to reveal the critical features of various geometrical and metallurgical factors for better printing. He has hosted and participated in over 10 research projects. He is the Associate Editor of Additive Manufacturing, and also serves on the Editorial Boards of Additive Manufacturing Letters, and Science and Technology of Welding and Joining journals. To date, he has published over 50 peer-reviewed papers.
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Liu, Fq., Wei, Hl., Wei, L. et al. Transient printing characteristics with wavy build profiles for laser additive manufacturing of small size structures. China Foundry 18, 409–415 (2021). https://doi.org/10.1007/s41230-021-1001-2
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DOI: https://doi.org/10.1007/s41230-021-1001-2