About this Abstract |
Meeting |
MS&T22: Materials Science & Technology
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Symposium
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Additive Manufacturing Modeling, Simulation, and Machine Learning: Microstructure, Mechanics, and Process
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Presentation Title |
The Effect of the Process Environment on Gas and Particle Entrainment in Laser Powder Bed Fusion |
Author(s) |
Michael Stokes, Saad A Khairallah, Alexey N Volkov, Alexander M Rubenchik |
On-Site Speaker (Planned) |
Michael Stokes |
Abstract Scope |
The laser irradiation of metal powders induces strong evaporation forming a vapor microjet that entrains powder metal particles causing denudation and spatter defects. The present work theoretically investigates the effect of the type of the ambient gas, its pressure, and surface temperature on the vapor jet structure and corresponding gas and powder particle entrainment. Gas kinetic simulations of the microjet are performed using the direct simulation Monte Carlo (DSMC) method. Trajectories of metal powders are also simulated to predict spatter-related defects. The results indicate that the structure of the microjet heavily depends on the processing environment. Changes in the surface temperature, pressure, and surface geometry affect the transition from subsonic to supersonic flow. The results also show that the degree of particle entrainment, e.g., the thickness of the surface denudation zone, strongly depends on the molar mass of the ambient gas, and characteristic vapor microjet velocity. LLNL-JRNL-829362; This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE- AC52-07NA27344. Lawrence Livermore National Security, LLC. LLNL-ABS-829363. This work was also partially supported by NSF through awards CMMI-1554589 and CMMI-1663364. |