Melt pool simulations in PBF-LB/M, Part 6, Fraunhofer IWM, Bastien Dietemann
Part 6: Melt pool simulations in PBF-LB/M
Dr. Bastien Dietemann, Fraunhofer IWM
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The essential step during Laser Powder Bed Fusion is the melting of the powder upon laser irradiation. This step affects the porosity of the produced part as well as its mechanical properties.
The laser is absorbed by the powder particles, the local temperature greatly rises and the material melts. Surface tension, viscosity and possibly gas recoil pressure determine the melt pool shape. The stability of the melt pool is essential for a controlled manufacturing process.
The interaction of the laser with the material is critical. The laser can be reflected or absorbed at the particle surface. By means of multiple reflections between the particles, it’s possible that the laser travels deeper into the powder bed. The laser absorptance depends on both the state and temperature of the material.
The melting of the powder leads to several other physical effects that need to be considered in the melt pool simulation. The result of this simulation displays the residual porosity as well as the local temperature history.