期刊
出版社
ASME
DOI: 10.1115/1.4048371
关键词
powder-bed fusion; laser; electron beam; CFD; melt pool; cooling rate; materials processing; mechanical behavior; metals
资金
- National Science Foundation [OIA-1541079]
- Louisiana Board of Regents
A multiphysics-based 3D numerical model was developed to compare the thermo-fluid properties of Ti-6Al-4V melt pools formed by the L-PBF and E-PBF processes. The results showed that the L-PBF process had a faster cooling rate and higher liquid velocity in the melt pool compared to the E-PBF process under similar irradiation conditions. The numerical model was validated by comparing the simulation results with experimental results and an analytical solution for the melting of a phase-change material.
Powder-bed fusion (PBF) process is a subdivision of additive manufacturing (AM) technology where a heat source at a controlled speed selectively fuses regions of a powder-bed material to form three-dimensional (3D) parts in a layer-by-layer fashion. Two of the most commercialized and powerful PBF methods for fabricating full-density metallic parts are the laser PBF (L-PBF) and electron beam PBF (E-PBF) processes. In this study, a multiphysics-based 3D numerical model is developed to compare the thermo-fluid properties of Ti-6Al-4V melt pools formed by the L-PBF and E-PBF processes. The temperature-dependent properties of Ti-6Al-4V alloy and the parameters for the laser and electron beams are incorporated in the model as the user-defined functions (UDFs). The melt-pool geometry and its thermo-fluid behavior are investigated using the finite volume (FV) method, and results for the variations of temperature, thermo-physical properties, velocity, geometry of the melt pool, and cooling rate in the two processes are compared under similar irradiation conditions. For an irradiance level of 26 J/mm(3) and a beam interaction time of 1.212 ms, simulation results show that the L-PBF process gives a faster cooling rate (1. 5 K/mu s) than that in the E-PBF process (0.74 K/mu s). The magnitude of liquid velocity in the melt pool is also higher in L-PBF than that in E-PBF. The numerical model is validated by comparing the simulation results for the melt-pool geometry with the PBF experimental results and comparing the numerical melt-front position with the analytical solution for the classical Stephan problem of melting of a phase-change material (PCM).
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