“Particle Impact Observations and Simulations in Laser Directed Energy Deposition Additive Manufacturing”
Department of Materials Science & Engineering
Friday April 5, 2019
1:30 – 2:30 PM ~ 405 Ferris Hall
“Particle Impact Observations and Simulations
in Laser Directed Energy Deposition Additive Manufacturing”
Speaker: Dr. James Cameron Haley
Oak Ridge National Laboratory-Oak Ridge, TN
Laser Directed Energy Deposition (L-DED) Additive Manufacturing (AM) offers unprecedented manufacturing flexibility in fabrication and repair of metallic components in a way that can be readily integrated with existing CNC technologies. Performance and stability of the technique relies on controlling the feedstock material: a gas fluidized powder sprayed onto the molten pool of metal. In this work, the dynamic impact of individual powder particles on the surface of the melt pool was imaged with high speed video at up to 500,000 frames per second at micron resolution. It was revealed that instead of penetrating into the bulk of the fluid, particles are briefly trapped by surface tension on the melt pool surface and float before melting. It is shown that this previously unreported phenomenon has sweeping implications for process efficiency, surface roughness, and porosity retention. Finally, this particle retention time was further investigated with a multiphase CFD numerical simulation to dissect its relationships with particle size, impact velocity, thermal distributions and wettability.
Dr. James Haley is a postdoctoral researcher at Oak Ridge National Laboratory developing in-situ monitoring techniques and modelling tools to understand process behaviors in metal Additive Manufacturing. His Ph.D. was recently granted from the University of California, Irvine for his work observing particle impact behavior and machine stability phenomena. He received his MS from UC Davis studying combinatorial diffusion and electromigration analysis in titanium alloys, and previously worked for the TimkenSteel company to qualify and expand capabilities of new inline forging and seamless tube piercing practices.