Virtual and Physical Prototyping,
Год журнала:
2024,
Номер
19(1)
Опубликована: Март 13, 2024
Unintended
end-of-process
depression
(EOPD)
commonly
occurs
in
laser
powder
bed
fusion
(LPBF),
leading
to
poor
surface
quality
and
lower
fatigue
strength,
especially
for
many
implants.
In
this
study,
a
high-fidelity
multi-physics
meso-scale
simulation
model
is
developed
uncover
the
forming
mechanism
of
defect.
A
defect-process
map
EOPD
phenomenon
obtained
using
model.
It
found
that
formation
mechanisms
are
different
under
distinct
regions
process
parameters.
At
low
scanning
speeds
keyhole
mode,
long-lasting
recoil
pressure
large
temperature
gradient
easily
induce
EOPD.
While
at
high
shallow
molten
pool
morphology
solidification
rate
allow
evolve
into
an
quickly.
Nevertheless,
conduction
Marangoni
effects
along
with
faster
Finally,
'step'
variable
power
strategy
proposed
optimise
defects
case
volumetric
energy
density
speeds.
This
work
provides
profound
understanding
valuable
insights
control
LPBF
fabrication.
Journal of Materials Research and Technology,
Год журнала:
2024,
Номер
31, С. 908 - 926
Опубликована: Июнь 19, 2024
Mg–Pb-9.2Al-0.8B
alloy
faces
a
significant
strength-toughness
balance
problem
in
applications.
To
address
this
challenge,
severe
plastic
deformation
was
applied
to
the
by
combining
traditional
extrusion
with
multi-pass
equal
channel
angular
pressing
(EX-ECAP).
The
research
delves
into
microstructural
evolution
(including
broken
β-Mg17Al12
and
non-uniform
Mg2Pb
particles)
its
effects
on
strengthening
mechanisms.
synergistic
of
grain
boundary
due
refinement,
Orowan
strengthening,
geometrically
necessary
dislocation
coefficient
thermal
expansion
collectively
enhance
tensile
strength
ductility,
balancing
toughness.
results
showed
an
impressive
ultimate
386.1
MPa,
which
is
2.33
times
that
as-cast
alloy.
altered
fracture
morphology
clearly
indicated
transformation
from
brittle
brittle-ductile
mode.
During
process,
activation
dislocations,
atomic-scale
ripples,
minor
lattice
distortions,
kink
bands
macroscopic
flexibility.
introduction
EX-ECAP
presents
new
opportunities
for
manufacturing
high-performance
through
integrated
techniques.
Virtual and Physical Prototyping,
Год журнала:
2024,
Номер
19(1)
Опубликована: Март 13, 2024
Unintended
end-of-process
depression
(EOPD)
commonly
occurs
in
laser
powder
bed
fusion
(LPBF),
leading
to
poor
surface
quality
and
lower
fatigue
strength,
especially
for
many
implants.
In
this
study,
a
high-fidelity
multi-physics
meso-scale
simulation
model
is
developed
uncover
the
forming
mechanism
of
defect.
A
defect-process
map
EOPD
phenomenon
obtained
using
model.
It
found
that
formation
mechanisms
are
different
under
distinct
regions
process
parameters.
At
low
scanning
speeds
keyhole
mode,
long-lasting
recoil
pressure
large
temperature
gradient
easily
induce
EOPD.
While
at
high
shallow
molten
pool
morphology
solidification
rate
allow
evolve
into
an
quickly.
Nevertheless,
conduction
Marangoni
effects
along
with
faster
Finally,
'step'
variable
power
strategy
proposed
optimise
defects
case
volumetric
energy
density
speeds.
This
work
provides
profound
understanding
valuable
insights
control
LPBF
fabrication.
