Materials,
Journal Year:
2024,
Volume and Issue:
17(11), P. 2690 - 2690
Published: June 2, 2024
In
this
study,
the
decomposition
of
a
martensite/austenite
(M/A)
microconstituent
in
bainitic
steels
was
analyzed
using
differential
scanning
calorimetry
(DSC)
data
conjunction
with
Kissinger’s
and
Johnson–Mehl–Avrami–Kolmogorov
(JMAK)’s
formulas.
steel
subjected
to
austempering
heat
treatment,
presence
an
M/A
microstructure
adversely
affects
mechanical
properties.
According
kinetic
equations
derived,
it
is
observed
that
after
tempering
sample
at
600
°C
for
4000
s,
generation
each
phase
reaches
its
maximum.
The
SEM
images
taken
before
reveal
extensive
constituent
microstructure.
proportion
decreased
significantly
from
about
10%
less
than
1%
after.
Additionally,
content
residual
austenite
also
reduced
nearly
zero.
These
observations
are
consistent
predictions
equations.
Journal of Materials Research and Technology,
Journal Year:
2024,
Volume and Issue:
31, P. 1535 - 1546
Published: June 22, 2024
The
microstructure,
phase
transformation
behavior,
heat
treatment
effects,
and
their
impacts
on
the
mechanical
properties
high-temperature
oxidation
resistance
of
IN718
nickel-based
superalloy
processed
by
selective
laser
melting
(SLM)
both
before
after
was
systematically
investigated.
process
involved
a
two-step
aging
at
720°C
for
8
h
plus
620°C
10
with
controlled
slow
cooling
rate
10°C/min.
Through
comprehensive
use
scanning
electron
microscopy
(SEM),
X-ray
diffraction
(XRD),
backscattering
(EBSD),
transmission
(TEM),
evolution
microstructure
its
mechanism
influence
material
were
revealed.
study
identified
formation
γ
phase,
γ'
γ''
δ
Laves
during
SLM
forming
process.
Heat
played
key
role
in
improving
SLM-processed
alloy,
experimental
results
showing
that
performance
significantly
enhanced
treatment.
Specifically,
exhibited
yield
strength
1472
MPa,
tensile
1608
an
elongation
9.2%,
which
represented
increases
76.5%,
38.4%,
16.5%
respectively,
compared
to
as-printed
alloy.
Moreover,
1000°C
heat-treated
samples
improved
significantly,
weight
loss
reduced
from
-0.17
mg/cm2
-0.15
mg/cm2.
Microstructural
analysis
further
indicated
optimized
crystal
orientation,
promoted
more
precipitated
phases
defects,
thereby
enhancing
overall
material.
This
work
provides
significant
scientific
insights
into
understanding
optimizing
SLM,
demonstrating
crucial
properties.
