This
work
studied
microstructural
evolution,
precipitate
behaviors,
and
micro-hardness
distribution
along
the
building
direction
of
direct
energy
deposited
IN718
alloy.
In
combination
with
digital
image
correlation
crystallographic
orientation
analysis,
plastic
deformation
fracture
mechanisms
coarse
columnar
grains
were
explored
in
detail.
The
solidification
structure
deposition
zone
(DZ)
grows
<001>
crystallography.
However,
become
wider
increasing
height.
cumulative
misorientation
angle
length
within
first
gradually
decreases
then
slows
down
to
~
0.07
°/mm
when
height
is
1.8
mm.
DZ
decreased
direction,
which
may
be
due
average
grain
width
primary
dendrite
arm
spacing,
as
well
reducing
volume
fraction
y''
+
y'
phases.
During
uniaxial
tensile
loading,
most
always
occurs
irrespective
lowest
hardness
HAZ.
nucleation
microvoids
ascribed
granular
Laves
phase
debonding
from
y
matrix.
number
distance
fracture,
attributed
strain
gradient
distribution.
EBSD
results
substantiated
that
near
surface
occur
severe
lattice
rotation,
leading
Kernel
each
interior
about
1°
4°.
Applied Sciences,
Journal Year:
2024,
Volume and Issue:
14(15), P. 6420 - 6420
Published: July 23, 2024
The
combination
of
wrought
materials
and
laser-based
directed
energy
deposition
(DED-LB)
is
being
increasingly
used
for
manufacturing
new
repairing
old
or
damaged
components
in
several
industries.
Aerospace
made
Inconel
718
featuring
small-thickness
DED-LB
buildups
are
a
remarkable
example
such
due
to
the
high
added
value
it
brings.
Despite
that
these
usually
critical
components,
miniature
testing
methods
assess
local
mechanical
properties
buildup
area
not
fully
developed.
This
work
contributes
this
development
with
an
improvement
small
punch
(SPT)
technique
measuring
weld
line
between
substrate.
A
criterion
positioning
SPT
specimens
proposed
applied
on
samples
hybrid
wrought/DED-LB
718.
results
at
necking
site
specimen
show
approach
valid
assessing
transition
zone
additive
states.
For
specific
conditions
tested
taking
material
as
reference,
strength
drops
10%
20%
buildup.
Virtual and Physical Prototyping,
Journal Year:
2024,
Volume and Issue:
19(1)
Published: Dec. 2, 2024
The
solidification
process
of
laser
directed
energy
deposition
(LDED)
affects
elemental
separation,
microstructure,
and
tensile
properties.
This
work
proposes
an
interval
pulsed
(IPLD)
to
improve
the
cooling
rate.
IPLD
continuous
(CLD)
samples
are
prepared
at
same
power
for
comparative
analysis.
Solution
treatment
aging
(STA)
heat
processes
developed
compare
as-deposited
STA
samples.
Finite
element
simulation
results
showed
that
has
a
smaller
molten
pool
higher
In
microstructure
analysis,
have
stronger
<001>
texture
grains
in
all
Smaller
Laves
phase
distributions
Nb-rich
areas
found
After
STA,
long-chain
phases
completely
dissolve
into
discrete
almost
disappear.
More
short
rod
needle-like
δ-phases
observed
around
small
phases,
proportion
large-size
decreases
significantly.
Nb
mass
fraction
is
16.9
samples,
which
lower
than
26.66
CLD
For
YS
(1095
Mpa),
UTS
(1310
elongation
(24.5%)
reached
level
Inconel
718
wrought
parts.
In
this
study,
δ
aging
and
solution
treatment
were
employed
to
eliminate
Laves
phase
in
Inconel
718
alloy
fabricated
by
directed
energy
deposition.
The
effect
of
precipitated
during
the
on
dissolution
behavior
was
revealed.
Compared
direct
treatment,
characteristic
parameters
(i.e.,
size
volume
fraction)
Nb
segregation
degree
are
significantly
deceased
when
is
performed
before
treatment.
composition
morphology
pre-precipitated
crucial
for
dissolution.
On
one
hand,
formation
(Ni3Nb)
consumes
numerous
atoms
γ
matrix,
which
increases
element
concentration
gradient
at
Laves/γ
interface.
other
a
large
amount
needle-like
around
decreases
area
As
result,
number
diffusing
through
unit
interfacial
increased,
enhances
rate
mass
transfer
interface
accelerates
phase.
kinetics
investigated
using
Johnson-Mehl-Avrami-Kolmogorov
model,
Singh-Flemings
H.B.
Aaron
M.J.
Whelan
reaction
model.
model
demonstrated
that
diffusion
dominant
mechanism
transforms
from
long-striped
shape
blocky
shape.
However,
clarified
plays
role
phase,
may
be
due
decrease
segregation.
This
work
studied
microstructural
evolution,
precipitate
behaviors,
and
micro-hardness
distribution
along
the
building
direction
of
direct
energy
deposited
IN718
alloy.
In
combination
with
digital
image
correlation
crystallographic
orientation
analysis,
plastic
deformation
fracture
mechanisms
coarse
columnar
grains
were
explored
in
detail.
The
solidification
structure
deposition
zone
(DZ)
grows
<001>
crystallography.
However,
become
wider
increasing
height.
cumulative
misorientation
angle
length
within
first
gradually
decreases
then
slows
down
to
~
0.07
°/mm
when
height
is
1.8
mm.
DZ
decreased
direction,
which
may
be
due
average
grain
width
primary
dendrite
arm
spacing,
as
well
reducing
volume
fraction
y''
+
y'
phases.
During
uniaxial
tensile
loading,
most
always
occurs
irrespective
lowest
hardness
HAZ.
nucleation
microvoids
ascribed
granular
Laves
phase
debonding
from
y
matrix.
number
distance
fracture,
attributed
strain
gradient
distribution.
EBSD
results
substantiated
that
near
surface
occur
severe
lattice
rotation,
leading
Kernel
each
interior
about
1°
4°.
