Hello Robert,
thanks for your very good summary of your research concerning porous structures. It is quite interesting, that theses attached particals are observed more often with higher densities, if I understood you right. Do you have already an idea, how this can happen? I’m thinking about something like: Higher energy density results in more half-molten particals, whereas with lower energy density results in more loose powder. And speaking of loose powder: Can you distinguish in the CT-scan between solid, but small structures and loose powder, that is “trapped” in a porous structure? Thanks a lot, Lukas
Hello Lukas,
thank you for your feedback, I am glad you liked the presentation! Regarding the attached particles: true, that was our first (maybe subjective) impression. But you are totally right, higher volumetric energy density seems generally to result in more fused material and thus more half molten particles as well. This is an observation also made by the simulations of Khairallah et al. [1] for example. The energy input seems high enough to partly melt/ sinter particles, yet not high enough to melt them completely into the melt pool. As lower energy input melts less powder – more powder stays unmolten indeed. For the first analysis we can distinguish between small solid structures and loose powder in our CT-based images – but we are currently on it, so stay tuned! 🙂
Best regards, Robert
[1] S.A. Khairallah, A.T. Anderson, A. Rubenchik, W.E. King, Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones, Acta Materialia 108 (2016) 36-45.
Hello Robert,
thanks for your very good summary of your research concerning porous structures. It is quite interesting, that theses attached particals are observed more often with higher densities, if I understood you right. Do you have already an idea, how this can happen? I’m thinking about something like: Higher energy density results in more half-molten particals, whereas with lower energy density results in more loose powder. And speaking of loose powder: Can you distinguish in the CT-scan between solid, but small structures and loose powder, that is “trapped” in a porous structure? Thanks a lot, Lukas
Hello Lukas,
thank you for your feedback, I am glad you liked the presentation! Regarding the attached particles: true, that was our first (maybe subjective) impression. But you are totally right, higher volumetric energy density seems generally to result in more fused material and thus more half molten particles as well. This is an observation also made by the simulations of Khairallah et al. [1] for example. The energy input seems high enough to partly melt/ sinter particles, yet not high enough to melt them completely into the melt pool. As lower energy input melts less powder – more powder stays unmolten indeed. For the first analysis we can distinguish between small solid structures and loose powder in our CT-based images – but we are currently on it, so stay tuned! 🙂
Best regards, Robert
[1] S.A. Khairallah, A.T. Anderson, A. Rubenchik, W.E. King, Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones, Acta Materialia 108 (2016) 36-45.