Correlative spatter and vapour depression dynamics during laser powder bed fusion of an Al-Fe-Zr alloy
File(s)
Published version
OA Location
Author(s)
Type
Journal Article
Abstract
Spatter during laser powder bed fusion (LPBF) can induce surface defects, impacting the fatigue
performance of the fabricated components. Here, we reveal and explain the links between
vapour depression shape and spatter dynamics during LPBF of an Al-Fe-Zr aluminium alloy
using high-speed synchrotron x-ray imaging. We quantify the number, trajectory angle, velocity,
and kinetic energy of the spatter as a function of vapour depression zone/keyhole morphology
under industry-relevant processing conditions. The depression zone/keyhole morphology was
found to influence the spatter ejection angle in keyhole versus conduction melting modes: (i) the
vapour-pressure driven plume in conduction mode with a quasi-semi-circular depression zone
leads to backward spatter whereas; and (ii) the keyhole rear wall redirects the gas/vapour flow to
cause vertical spatter ejection and rear rim droplet spatter. Increasing the opening of the keyhole
or vapour depression zone can reduce entrainment of solid spatter. We discover a
spatter-induced cavity mechanism in which small spatter particles are accelerated towards the
powder bed after laser-spatter interaction, inducing powder denudation and cavities on the
printed surface. By quantifying these laser-spatter interactions, we suggest a printing strategy
for minimising defects and improving the surface quality of LPBF parts.
performance of the fabricated components. Here, we reveal and explain the links between
vapour depression shape and spatter dynamics during LPBF of an Al-Fe-Zr aluminium alloy
using high-speed synchrotron x-ray imaging. We quantify the number, trajectory angle, velocity,
and kinetic energy of the spatter as a function of vapour depression zone/keyhole morphology
under industry-relevant processing conditions. The depression zone/keyhole morphology was
found to influence the spatter ejection angle in keyhole versus conduction melting modes: (i) the
vapour-pressure driven plume in conduction mode with a quasi-semi-circular depression zone
leads to backward spatter whereas; and (ii) the keyhole rear wall redirects the gas/vapour flow to
cause vertical spatter ejection and rear rim droplet spatter. Increasing the opening of the keyhole
or vapour depression zone can reduce entrainment of solid spatter. We discover a
spatter-induced cavity mechanism in which small spatter particles are accelerated towards the
powder bed after laser-spatter interaction, inducing powder denudation and cavities on the
printed surface. By quantifying these laser-spatter interactions, we suggest a printing strategy
for minimising defects and improving the surface quality of LPBF parts.
Date Issued
2024-10-01
Date Acceptance
2024-05-19
Citation
International Journal of Extreme Manufacturing, 2024, 6 (5)
ISSN
2631-8644
Publisher
IOP Publishing
Journal / Book Title
International Journal of Extreme Manufacturing
Volume
6
Issue
5
Copyright Statement
© 2024 The Author(s). Published by IOP Publishing Ltd on behalf of the IMMT Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any fur ther distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
License URL
Identifier
10.1088/2631-7990/ad4e1d
Subjects
defects
DENUDATION
Engineering
Engineering, Manufacturing
GENERATION
HIGH-STRENGTH
Materials Science
Materials Science, Multidisciplinary
MECHANISMS
OXIDATION
PARTICLES
PARTS
PLATFORM
Science & Technology
spatter
SPEED
STAINLESS-STEEL
surface quality
Technology
vapour depression
x-ray imaging
Publication Status
Published
Article Number
055601
Date Publish Online
2024-06-05