Adjusting the microstructure of additively manufactured parts with tailored temperature fields by the combination of powder bed fusion with cw-laser and ablation with ultrashort laser pulses

In powder bed fusion with laser beams (PBF-LB/M), the component's quality and mechanical properties are limited by restricted process parameter combinations and the geometry of the component. Combining PBF-LB/M with ultrashort laser ablation enables additional control of the heat flow to adjust local solidification. On the one hand it is possible to print heat-dissipating structures, which can be added and removed during the build process. On the other hand, ablated slits in the component can serve as a thermal barrier. To investigate the effect of slits and heat-dissipation structures on the local temperature field and solidification conditions, a numerical model was developed. Two different ablation strategies were investigated and compared to conventional PBF-LB. Numerical investigations of an additively manufactured AlSi10Mg component showed a larger melt pool, a lower temperature gradient, and a lower cooling rate if there are slits present next to the current PBF-LB track. This approach provides the potential to independently adjust microstructure and mechanical properties, exceeding limitations imposed by the component's geometry in conventional additive manufacturing.