About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
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Additive Manufacturing Modeling, Simulation, and Machine Learning: Microstructure, Mechanics, and Process
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| Presentation Title |
Investigation of Near-Pore Microstructure in Laser Powder Bed Fusion Alloy 718 |
| Author(s) |
Jonathan David Reyes Ortiz, Anthony D. Rollett, Sneha Prabha Narra, Chris Pistorius |
| On-Site Speaker (Planned) |
Jonathan David Reyes Ortiz |
| Abstract Scope |
Pores in laser powder bed fusion (LPBF) components are treated as stress concentrators, yet their influence on the surrounding solidification microstructure remains understudied. This work presents our findings in LPBF Alloy 718, where pores exceeding approximately 20 µm equivalent circular diameter are surrounded by a zone of fine equiaxed grains that also exhibit coarser solidification sub-structure than the bulk columnar microstructure. Electron backscatter diffraction and scanning electron microscopy were employed to quantify grain size, crystallographic texture, and cellular spacing as a function of distance from the pore boundary. A three-step mechanism is proposed in which the pore acts as a thermal barrier, suppressing the local thermal gradient and cooling rate while simultaneously promoting heterogeneous nucleation and a columnar-to-equiaxed transition at the pore boundary. Transient thermal simulation corroborates the proposed mechanism. These deviations may influence recrystallization behavior during post-processing heat treatments and, consequently, the mechanical performance in the vicinity of pores |