Evaluation of Engineered Microstructure Developed Using Interpenetrating Lattices Fabricated by Laser Powder Bed Fusion

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August 2023

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Abstract

Laser powder bed fusion (LPBF) is one of the well-adapted additive manufacturing processes used to fabricate near-net shaped complex metal parts with high accuracy. LPBF involves various process parameters such as laser power, scan speed, scan strategy, hatch spacing, and layer thickness, which significantly affect the properties of the fabricated parts. The microstructure of LPBF parts can be controlled by selecting appropriate process parameters. However, achieving a controlled combination of both coarse and fine grains has been a challenge due to rapid changes in the thermal gradient. To address this challenge, this study introduces an innovative approach using interpenetrating triply periodic minimal surfaces (TPMS) lattices. These lattices are employed to control the percentage and distribution of both coarse and fine grains. However, implementing the LPBF process to fabricate interpenetrating lattices presents various challenges, including selecting suitable process parameters for designing and fabricating the defect-free parts. Initially, a comprehensive investigation is conducted to understand the processing, structure, and properties of bulk structures created using the LPBF process in a single metallic alloy. Subsequently, different lattice designs, unit cell sizes, and fabrication strategies are examined to achieve defect-free interpenetrating TPMS lattice parts. Finally, the appropriate process parameters, interpenetrating TPMS lattice design, and fabrication strategy are optimized to create parts with an isotropic microstructure. The parts with engineered microstructure exhibit a desired combination of coarse and fine grains, leading to improved electrochemical and comparable mechanical properties when compared to bulk specimens fabricated using LPBF.

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Engineering, Mechanical

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