Melt Pool characteristics on surface roughness and printability of 316L stainless steel in laser powder bed fusion
Abstract
Purpose
Surface quality and porosity significantly influence the structural and functional properties of the final product. This study aims to establish and explain the underlying relationships among processing parameters, top surface roughness and porosity level in additively manufactured 316L stainless steel.
Design/methodology/approach
A systematic variation of printing process parameters was conducted to print cubic samples based on laser power, speed and their combinations of energy density. Melt pool morphologies and dimensions, surface roughness quantified by arithmetic mean height (Sa) and porosity levels were characterized via optical confocal microscopy.
Findings
The study reveals that the laser power required to achieve optimal top surface quality increases with the volumetric energy density (VED) levels. A smooth top surface (Sa < 15 µm) or a rough surface with humps at high VEDs (VED > 133.3 J/mm3) can serve as indicators for fully dense bulk samples, while rough top surfaces resulting from melt pool discontinuity correlate with high porosity levels. Under insufficient VED, melt pool discontinuity dominates the top surface. At high VEDs, surface quality improves with increased power as mitigation of melt pool discontinuity, followed by the deterioration with hump formation.
Originality/value
This study reveals and summarizes the formation mechanism of dominant features on top surface features and offers a potential method to predict the porosity by observing the top surface features with consideration of processing conditions.
Keywords
Acknowledgements
The authors would like to acknowledge the support from the National Science Foundation under grant number 2029425, and Savannah River National Laboratory under Contract No. 89303321CEM000080 for the U.S. Department of Energy.
Declaration of interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests.
Lang Yuan reports financial support provided by National Science Foundation. Lang Yuan reports financial support was provided by Savannah River National Laboratory. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Citation
Zhang, T. and Yuan, L. (2024), "Melt Pool characteristics on surface roughness and printability of 316L stainless steel in laser powder bed fusion", Rapid Prototyping Journal, Vol. ahead-of-print No. ahead-of-print. https://doi.org/10.1108/RPJ-02-2024-0078
Publisher
:Emerald Publishing Limited
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