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Onset of periodic oscillations as a precursor of a transition to pore generating turbulence in laser melting

Published

Author(s)

Tao Sun, Brian Simonds, Saad Khairallah

Abstract

Advanced laser based additive manufacturing, such as laser powder bed fusion, promise to revolutionize 3D metal printing. However, a challenge remains in controlling pore generating turbulence. Printed parts with pore defects can fail quality certification. We used high-fidelity simulations coupled with synchrotron experiments and ultrahigh-speed absorption radiometry to detect the onset of pore- generating turbulence. We discovered periodic oscillations in the melt pool surface and absorptivity driven by an extension and collapse mechanism. Over-extension by "recoil shock waves" followed by fast non-uniform melt pool collapse create "temporary pores" that signal a transition to pore- generating turbulence and a vanishing periodicity. Pores survival, in shallow or deep melt pools, depends on the turbulence's non-linear dependence on power and speed. Early detection of this transition will improve part quality.
Citation
Additive Manufacturing Letters

Keywords

Additive Manufacturing, Laser melting

Citation

Sun, T. , Simonds, B. and Khairallah, S. (2021), Onset of periodic oscillations as a precursor of a transition to pore generating turbulence in laser melting, Additive Manufacturing Letters, [online], https://doi.org/10.1016/j.addlet.2021.100002, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931937 (Accessed April 18, 2024)
Created June 29, 2021, Updated November 29, 2022