Dynamics of pore formation during laser powder bed fusion additive manufacturing
Abstrct:Laser powder bed fusion additive manufacturing is an emerging 3D printing technique for thefabrication of advanced metal components. Widespread adoption of it and similar additivetechnologies is hampered by poor understanding of laser-metal interactions under suchextreme thermal regimes. Here, we elucidate the mechanism of pore formation and liquid-solid interface dynamics during typical laser powder bed fusion conditions using in situ X-rayimaging and multi-physics simulations. Pores are revealed to form during changes in laserscan velocity due to the rapid formation then collapse of deep keyhole depressions in thesurface which traps inert shielding gas in the solidifying metal. We develop a universalmitigation strategy which eliminates this pore formation process and improves the geometricquality of melt tracks. Our results provide insight into the physics of laser-metal interactionand demonstrate the potential for science-based approaches to improve confidence incomponents produced by laser powder bed fusion.
