SIM-AM 2023

Model validation by measurement of the directional distribution of reflected laser power in powder bed fusion metal additive manufacturing

  • Deisenroth, David (NIST)
  • Mekhontsev, Sergey (NIST)
  • Huang, Wenkang (University of Michigan)
  • Tan, Wenda (University of Michigan)

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The reflectivity of metals causes a significant portion of the applied laser power to reflect from the laser-matter interaction area in laser powder bed fusion additive manufacturing. For models to predict important process outcomes such as melt depth and material cooling rates, the amount of power absorbed into the melting process must be known accurately. This is the motivation for measurement of laser absorption. The laser absorption can also be quantified indirectly by measuring the time-resolved reflected laser power (referred to as ‘laser coupling’) with a light integrating device surrounding the laser-matter interaction. This approach has become well-established in the field. Recent advancements in measurement science have demonstrated the ability not only to measure the total reflected power but also the directional distribution of reflected laser power. These measurements provide insight into the dynamics of the melt pool geometry from initiation to steady state, as well as validation data for high-fidelity multiphysics models of the laser-matter interaction. The measurement approach, data processing, and experimental results are presented.