Damascus steel printed on a 3D printer

German
the materials scientists printed on
3D printer
modern
analog Damascus steel.
Characteristic
a layered structure with the alternation of more
soft and hard layers have been achieved
using the round-Robin
heating and cooling of iron-Nickel
alloy with additions of titanium.
Received
alloys withstand pressures up to 1,3 MPa —
this is significantly higher than that of materials of the same composition obtained in a traditional way.
Results
research published
in the journal Nature.

3D printing
metals
—the process of creating a layered products
from metal powder, which
melts under the action of the laser.
When
this was during
the application of the subsequent layers to the previous
layers that are already hardened again
hot.
Since modern printing techniques
allow you to control the temperature
with high precision, such warm-up cycles
and cooling
harmful material, on the contrary they can
to use for it
additional processing
for example, for
improving strength.

In
last year the German
material engineers
from
Institute of iron research, max Planck Society under
the leadership of Philip
Kursteiner
(Philipp
Kürnsteiner)
showed,
when
re
heating
iron-Nickel-aluminum alloy
happens
deposition of Nickel-aluminum,
the result material
becomes more durable.
In
the new study, researchers
applied this
technology
for
create
the modern analogue of the famous
Damascus
steel.

Damascus steel has
the specific layered structure
alternating
more
soft
and more
hard
layers that
makes products from it at the same time
very
durable and plastic.
For
create
the layered structure
blacksmiths used alloys
iron with different carbon content,
connected with multiple
folding and prosovyvaniya
scientists decided to reproduce this
the effect of cyclic heating
and
cooling
material
in
the process
3D printing.

For
the basis of the authors took iron-Nickel
alloy with titanium additive
composition Fe19Ni5Ti
(figures
denote the mass fraction of metals in
the alloy), which
received two
commercially available powders: titanium
and
iron-Nickel
alloy.
For
formation
melt
used
infrared
laser with a wavelength of 976
nanometers
and a beam diameter of 1.8
mm

it can be used to heat the alloy up
up to 700 degrees
Celsius.
After
application
one or more layers
the laser was turned off for a certain
the period of time during this time
material
had time to cool down. In
time cooling and the subsequent heating
in the sample formed thin —
thick
several
hundreds of nanometers
layers
more
the dark steel.

Mechanical
trials have shown
what
these
dark
layers
approximately 30 percent harder than
intermediate more
light.
The authors
this suggested the following explanation:
when
cooling the steel partially transferred
from the form of austenite
(high temperature
face-centered
modification
iron
and alloys on its basis)
in the form
martensite
(supersaturated
solid solution based on α-iron with
body-centred crystal
bars).
When
subsequent heating of the martensitic
the phase of the formation of Nickel-titanium
dendrites —
branched microstructures size
about ten
nanometers.
Such microstructure hinder
deformation of the material, making it more
solid.

Thus a thin, dark
layer is the part of the previous layer,
which manages to heat up during
the application of the subsequent coat. Dark
the light caused by the apparently more
surface roughness, that is
more intense light scattering.
I wonder
what
at
the results of the elemental analysis of secondary
the Nickel content
and titanium in the dark
light
layers
was
almost the same, just in light layers, these elements were distributed
evenly, and in the dark formed
dendrites.

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