Process-induced Mechanical Property Heterogeneity along the Building Direction of Directed Energy Deposited IN718 Thin-walled Parts. (15th March 2022)

• Record Type: Journal Article
• Authors: Ning, Jinsheng; Yan, Zixi; Zhu, Lida; Zhao, Ji; Yang, Zhichao; Wang, Shuhao; Xue, Pengsheng; Xin, Bo
• Is Part Of: International journal of mechanical sciences. Volume 218(2022)
• Publication Date: 2022-03-15
• Subjects: Directed energy deposition -- Energy density -- Mechanical property -- Inconel 718 -- Thin-walled part; AM Additive manufacturing -- DED Directed energy deposition -- EBM Electron beam melting -- ED Energy density -- EDS Energy dispersive spectroscopy -- SLM Selective laser melting -- SEM Scanning electron microscope -- UTS Ultimate tensile strength -- XRD X-ray diffractometer -- YS Yield strength; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2022.107075
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: Effective energy density that considers the laser energy and powder distributions is introduced to explain the multi-layer deposition process. The correlation between energy density and the discrepancy in mechanical properties along the building direction is explicitly investigated. Deposition instability-induced defocus is used to interpret the microstructure and tensile property variations under a certain lift amount. Abstract: Directed energy deposition (DED) makes fabrication of large technological components more achievable; however, the process-induced heterogeneity of mechanical properties restrict reliability in many applications. In this study, the correlation among parameter (lift amount), process (energy density change), and property (mechanical property nonuniformity) in thin-walled part building was investigated. The non-uniform layer accumulation was captured using in-situ imaging, and an effective energy density model was established to interpret the heterogeneous mechanical properties along the building direction of the as-built multi-layer parts. Samples closer to the bottom region of the building direction possessed superior mechanical properties (microhardness, yield strength, and ultimate tensile strength), which corresponded to a higher range of absorbed effective energy density compared to the upper regions. Within a certain range, more absorbed energy density may result in superior strength and microhardness of the layers. Deposition regions that were dominated by a relatively large negative defocus could also achieve excellent mechanical properties despite only absorbing relatively low effective energy density. Graphical Abstract: Graphical Abstract Image, graphical abstract .