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Laser Power Modulation Influences Melt Pool Dynamics in Powder Bed Fusion

Strategic Insights

— 2 min read

Researchers at Lawrence Livermore National Laboratory (LLNL) have investigated the effects of laser power modulation on melt pool dynamics in powder bed fusion (PBF) metal additive manufacturing. The study, published in the Journal of Applied Physics, reveals that modulation of the laser power on tens-of-microsecond timescales can significantly impact melt pool fluid flow, defect formation, and nearby powder motion.

The researchers, led by N. P. Calta, used in situ high-speed x-ray and optical imaging to probe melt pool dynamics during PBF with both modulated and continuous wave (CW) laser heat sources. The study found that modulation of the laser power introduced unique melt pool dynamics, characterized by fluctuations in vapor depression depth, complex pore formation mechanisms, and changes to denudation physics when compared to CW melting.

The study concluded that at intermediate duty cycles, careful control of modulation parameters can repeatably and precisely yield one pore per laser pulse, suggesting a method for intentionally inserting engineered porosity at specific sites during an LPBF build. The findings have significant implications for the development of advanced materials and manufacturing techniques.

Key Takeaways:

  • Researchers at Lawrence Livermore National Laboratory (LLNL) investigated the effects of laser power modulation on melt pool dynamics in powder bed fusion (PBF) metal additive manufacturing.
  • The study found that modulation of the laser power introduced unique melt pool dynamics, characterized by fluctuations in vapor depression depth, complex pore formation mechanisms, and changes to denudation physics when compared to CW melting.
  • The study concluded that at intermediate duty cycles, careful control of modulation parameters can repeatably and precisely yield one pore per laser pulse, suggesting a method for intentionally inserting engineered porosity at specific sites during an LPBF build.
  • The findings have significant implications for the development of advanced materials and manufacturing techniques, particularly for applications involving Ti-6Al-4V, 316L stainless steel, and AL1100 alloys.
  • The study involved a collaboration between researchers from LLNL and other institutions, including the United States Department of Energy (DOE).
  • The research was funded by the United States Department of Energy (DOE), LLNL LDRD program, and other sources.

Statistics:

  • 10-20 μs timescale: The modulation of the laser power was observed to impact melt pool dynamics at a timescale of tens-of-microseconds.
  • 1:3 to 1:5 duty cycles: The study found that the modulation of the laser power introduced unique melt pool dynamics, characterized by fluctuations in vapor depression depth, complex pore formation mechanisms, and changes to denudation physics, at intermediate duty cycles (1:3 to 1:5).
  • 1 pore per laser pulse: The study concluded that at intermediate duty cycles, careful control of modulation parameters can repeatably and precisely yield one pore per laser pulse, suggesting a method for intentionally inserting engineered porosity at specific sites during an LPBF build.
  • 3 different alloys: The study investigated the effects of laser power modulation on melt pool dynamics in three different alloys: Ti-6Al-4V, 316L stainless steel, and AL1100.

Sources:

  • The Influence of Laser Power Modulation On Melt Pool Dynamics In Laser Powder Bed Fusion. Journal of Applied Physics, 2025;138(13).
  • NewsRx. Findings on Applied Physics Reported by Investigators at Lawrence Livermore National Laboratory (The Influence of Laser Power Modulation On Melt Pool Dynamics In Laser Powder Bed Fusion). Journal of Physics Research. November 4, 2025; p 82.
  • American Institute of Physics. Journal of Applied Physics. Available from: www.aip.org, jap.aip.org.

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