High fidelity model of directed energy deposition: Laser-powder-melt pool interaction and effect of laser beam profile on solidification microstructure

Metal additive manufacturing technologies keep receiving a great deal of interest as well as strong requests to develop methods to link the process science to printed parts performance and understand how to overcome inherent limitations. A high-fidelity model based on the multiphysics ALE3D code was developed to reproduce the directed energy deposition process down to the powder scale. This includes resolving the laser-powder-melt pool interactions (powder impingement and incorporation into melt pool, hydrodynamics flow condition and laser absorption inefficiencies) as well as the resulting solidification microstructure. This micrometer scale digital twin captured the effect of powder incorporation process and powder flow rate on porosity. Furthermore, it was used to explore how a ring laser beam profile instead of the standard Gaussian laser profile could decrease the thermal gradient along the solidification front in the melt pool, which in turn can increase propensity for more desirable equiaxed grains.

Automated summary

Metal additive manufacturing technologies are receiving significant attention and there is a strong demand to develop methods that link the process science to printed parts performance and overcome inherent limitations. A high-fidelity model based on the multiphysics ALE3D code was developed to replicate the directed energy deposition process at the powder scale and capture the effect of powder incorporation process and flow rate on porosity. The model also explored the use of a ring laser beam profile to improve the solidification microstructure.