U.S. patent number 10,385,432 [Application Number 15/069,505] was granted by the patent office on 2019-08-20 for methods of producing wrought products with internal passages.
This patent grant is currently assigned to ARCONIC INC.. The grantee listed for this patent is ALCOA INC.. Invention is credited to Eric G. Bogan, Jason C. Brem, James T. Burg, Michael Cardinale, Erin J. Fulton, Philip Gacka, Raymond J. Kilmer, William B. Leith, Vivek M. Sample, Robert J. Speer.
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United States Patent |
10,385,432 |
Kilmer , et al. |
August 20, 2019 |
Methods of producing wrought products with internal passages
Abstract
Various methods are disclosed for additively manufacturing a
feedstock material to create an AM preform, wherein the AM preform
is configured with a body having an internal passage defined
therein, wherein the internal passage further includes at least one
of a void and a channel; inserting a filler material into the
internal passage of the AM preform; closing the AM preform with an
enclosure component such that the filler material is retained
within the internal passage of the AM preform; and deforming the AM
preform to a sufficient amount to create a product having an
internal passage therein, wherein the product is configured with
wrought properties for that material via the deforming step.
Inventors: |
Kilmer; Raymond J. (Pittsburgh,
PA), Sample; Vivek M. (Murrysville, PA), Fulton; Erin
J. (Irwin, PA), Burg; James T. (Verona, PA), Bogan;
Eric G. (Cabot, PA), Brem; Jason C. (New Kensington,
PA), Speer; Robert J. (Upper Burrell, PA), Leith; William
B. (Apollo, PA), Cardinale; Michael (Apollo, PA),
Gacka; Philip (Allison Park, PA) |
Applicant: |
Name |
City |
State |
Country |
Type |
ALCOA INC. |
Pittsburgh |
PA |
US |
|
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Assignee: |
ARCONIC INC. (Pittsburgh,
PA)
|
Family
ID: |
55640902 |
Appl.
No.: |
15/069,505 |
Filed: |
March 14, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160298218 A1 |
Oct 13, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62132613 |
Mar 13, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y
40/00 (20141201); B22F 3/24 (20130101); B21J
5/002 (20130101); C22F 1/047 (20130101); B23K
15/0086 (20130101); B22F 3/1055 (20130101); B33Y
10/00 (20141201); B23K 26/70 (20151001); B22F
5/10 (20130101); C22C 21/08 (20130101); B23K
26/342 (20151001); B33Y 70/00 (20141201); B22F
2998/10 (20130101); Y02P 10/25 (20151101); B22F
2005/103 (20130101); B23K 2101/04 (20180801); B22F
2301/052 (20130101); B22F 2998/10 (20130101); B22F
3/1055 (20130101); B22F 3/17 (20130101); B22F
2003/247 (20130101); B22F 2003/248 (20130101); B22F
2998/10 (20130101); B22F 3/1055 (20130101); B22F
3/18 (20130101); B22F 2003/247 (20130101); B22F
2003/248 (20130101); B22F 2998/10 (20130101); B22F
3/1055 (20130101); B22F 3/20 (20130101); B22F
2003/247 (20130101); B22F 2003/248 (20130101) |
Current International
Class: |
C22F
1/047 (20060101); B22F 3/105 (20060101); B21J
5/00 (20060101); B33Y 10/00 (20150101); B33Y
70/00 (20150101); B22F 5/10 (20060101); B23K
15/00 (20060101); C22C 21/08 (20060101); B22F
3/24 (20060101); B23K 26/70 (20140101); B23K
26/342 (20140101); B33Y 40/00 (20150101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1861296 |
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Nov 2006 |
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CN |
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2551040 |
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Jan 2013 |
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EP |
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Other References
International Preliminary Report on Examination and Written
Opinion, dated Sep. 19, 2017, from related International Patent
Application No. PCT/US2016/022331. cited by applicant.
|
Primary Examiner: Zimmer; Anthony J
Attorney, Agent or Firm: Greenberg Traurig, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a nom-provisional of and claims priority to
U.S. Application Ser. No. 62/132,613, entitled "Methods for
Producing Wrought Products with Internal Passages" filed on Mar.
13, 2015, which is incorporated herein by reference in its
entirety.
Claims
What is claimed is:
1. A method comprising: (a) additively manufacturing an additively
manufactured (AM) preform, wherein the AM preform comprises an
internal passage within a body of the AM preform, wherein the
internal passage comprises at least one of a void and a channel;
(b) inserting a filler material into the internal passage of the AM
preform; (c) closing the AM preform with an enclosure component
such that the filler material is retained within the internal
passage of the AM preform; and (d) creating a wrought product
having the internal passage therein from the AM preform, wherein
the creating comprises hot working the AM preform.
2. The method of claim 1, wherein the closing step comprises
sealing the filler material within the AM preform via an enclosure
component.
3. The method of claim 1, wherein the closing step comprises
welding an opening of the internal passage, thereby enclosing the
filler material within the AM preform.
4. The method of claim 1, wherein the internal passage comprises an
opening, and wherein the closing step comprises pressing a plug
into the opening to retain the filler material within the internal
passage.
5. The method of claim 1, wherein the closing step comprises
enclosing the filler material in the internal passage via
successive additively manufactured build layers.
6. The method of claim 1, wherein the hot working comprises
forging.
7. The method of claim 6, wherein the forging comprises using a
single die forging.
8. The method of claim 1, wherein the hot working comprises
rolling.
9. The method of claim 1, wherein the hot working comprises ring
rolling.
10. The method of claim 1, wherein the hot working comprises
extruding.
11. The method of claim 1, comprising: removing the filler material
from the internal passage of the wrought product.
12. The method of claim 11, wherein the removing step comprises:
melting the filler material; and draining the filler material from
the wrought product.
13. The method of claim 1, comprising annealing at least one of the
AM preform and the wrought product.
14. The method of claim 1, comprising cold working at least one of
the AM preform and the wrought product.
15. The method of claim 1, comprising at least one of (i) machining
the wrought product, (ii) polishing the wrought product, and (iii)
surface finishing the wrought product.
16. The method of claim 15, wherein the creating step comprises:
prior to the hot working, preheating the AM preform, thereby
melting the filler material within the internal passage.
17. The method of claim 1, comprising: solidifying the filler
material and then completing the creating step (d).
18. The method of claim 1, wherein the filler material comprises a
material different than the AM preform.
19. The method of claim 18, wherein the filler material comprises
at least one of an oil, polymer, organic solvent, inorganic
solvent, metal or metal alloy.
Description
BACKGROUND
Additive manufacturing (AM) provides an unprecedented means of
manufacturing 3D shapes with complex internal geometries hitherto
not possible by conventional manufacturing processes.
FIELD OF THE INVENTION
Broadly, the instant disclosure relates to improved methods for
producing worked metal products (e.g., forged metal products; other
types of hot worked and/or cold worked metal products) using an AM
preform (i.e. a preform made via additive manufacturing). More
specifically, the instant disclosure is directed towards methods
for making an AM preform (e.g. metal AM preform) into a product
that (1) includes at least one interior/internal void and/or (2)
corresponds to final wrought properties for that part.
SUMMARY
Additive manufacturing enables parts of varying configurations and
dimensions to be constructed. However, with ninny feedstock
materials, the AM part includes properties attributable from the AM
build, which can differ greatly from the desired properties (e.g.
strength, grain structure, etc) for the end use application. One or
more methods of the instant disclosure are directed towards
creating a product that has wrought properties (i.e. deforming an
AM preform), where the product includes at least one internal
passage (e.g. each passage including a void and/or a channel). In
some embodiments, wrought properties include, but not limited to: a
wrought microstructure (e.g. recrystallized grains, removal of AM
grain structure) while providing a higher toughness (and in some
cases higher strength)).
In some embodiments, the microstructure and properties of the AM
components can be significantly improved by subsequent working to
convert the as built (as cast) structure to wrought structure.
Thus, internal features in the AM preform (such as cooling
passages) need to be protected from collapsing and cracking during
deformation. Some non-limiting examples of AM preforms for certain
applications having internal passages include: closed die forgings
and/or hipping operations, in which hydrostatic pressures (i.e.
pressures experienced by the internal passages) can far exceed the
pressures (e.g. deformation pressures experienced by the body of
the AM preform) during open die forgings. Also, one has to account
for the change in geometry of these features to obtain the final
desired shape.
One or more methods of the instant disclosure are directed towards:
(1) deforming while conserving the internal passage(s) created
during the AM process to promote an appropriate shape change (AM
Preform to Product) without cracking and/or collapsing of the AM
part or internal passage(s); (2) prescribing the AM Preform shape
geometry (external profile/body as well as internal passages) so
that the final geometry of the product is attainable in a
deformation (e.g. single forging) step (i.e. explicitly accounting
for deformation and/or deformation boundary conditions (friction
and temperature)); and/or obtaining a wrought structure to improve
the properties of the complex component (i.e. body having internal
passage(s)) manufactured by an AM process.
In one aspect, a method is provided, comprising: additively
manufacturing a feedstock material to create an AM preform, wherein
the AM preform is configured with a body having an internal passage
defined therein, wherein the internal passage further includes at
least one of a void and a channel; inserting a filler material into
the internal passage of the AM preform; closing the AM preform with
an enclosure component such that the filler material is retained
within the internal passage of the AM preform; and deforming the AM
preform to a sufficient amount to create a product having an
internal passage therein, wherein the product is configured with
wrought properties for that material via the deforming step.
In some embodiments, the closing step further comprises sealing the
filler material within the AM preform via an enclosure
component.
In some embodiments, the closing step further comprises welding the
opening shut to enclose the filler material within the AM
preform.
In some embodiments, the closing step further comprises pressing a
plug into an opening in the body to retain the filler material
within the internal passage.
In some embodiments, the closing step further comprises enclosing
the filler material in the internal passage via successive build
layers of additive manufacturing feedstock.
In some embodiments, the deforming step further comprises
forging.
In some embodiments, the deforming step further comprises a single
die forging.
In some embodiments, the deforming step further comprises
rolling.
In some embodiments, the deforming step further comprises ring
rolling.
In some embodiments, the deforming step further comprises
extruding.
In some embodiments, the method further includes: removing the
filler material from the internal passage of the product.
In some embodiments, the removing step further comprises: opening
the sealed product having filler material therein; melting the
filler material; and draining the filler material from the
product.
In some embodiments, the removing step further comprises: annealing
the product.
In some embodiments, the method further comprises cold working the
product.
In some embodiments, the method further comprises: hot working the
product.
In some embodiments, the method comprises finishing the surface of
the product.
In some embodiments, finishing is selected from the group
consisting of machining, polishing, surface finishing, and/or
combinations thereof.
In some embodiments, the deforming step further comprises: prior to
deforming, preheating the AM preform to melt the filler material
retained within the internal passage.
In some embodiments, the deforming step further comprises waiting a
sufficient duration of time for the filler material to solidify in
the internal passage; and deforming the AM preform having a
solidified idler material therein.
In another aspect of the instant disclosure, a method is provided,
comprising: selecting a target product having target wrought
properties; designing a target AM preform with a target preform
body dimension and a target preform void dimension, wherein the
target AM preform is configured to undergo a deformation step and
provide the target product having: a target product body dimension
and a target product void dimension; additively manufacturing an AM
preform having a preform body with a preform body dimension and a
void with a preform void dimension, wherein the preform body
dimension corresponds to the target preform body dimension, further
wherein the preform void dimension corresponds to the target
preform void dimension; and deforming the AM preform to a
sufficient amount to form a product having wrought properties
corresponding to the target wrought properties, wherein the AM
preform is configured with a filler material enclosed via an
enclosure component in the void; further wherein product is
configured with a product body having a product body dimension and
a product void having a product void dimension, wherein, via the
design step, the product body dimension corresponds to the target
product body dimension and the product void dimension corresponds
to the target product void dimension.
In another aspect of the instant disclosure, a method is provided,
comprising: designing a target AM preform with a target preform
body dimension, a target preform void dimension, and target wrought
properties, wherein the target AM preform is configured to undergo
a deformation step and provide the target product having: a target
product body dimension and a target product void dimension;
additively manufacturing an AM preform having a preform body with a
preform body dimension and a void with a preform void dimension,
wherein the preform body dimension corresponds to the target
preform body dimension, further wherein the preform void dimension
corresponds to the target preform void dimension; and deforming the
AM preform to a sufficient amount to form a product having wrought
properties corresponding to the target wrought properties, wherein
the AM preform is configured with a filler material enclosed via an
enclosure component in the void; further wherein product is
configured with a product body having a product body dimension and
a product void having a product void dimension, wherein, via the
design step, the product body dimension corresponds to the target
product body dimension and the product void dimension corresponds
to the target product void dimension.
As used herein, "corresponds" means to be in agreement and/or
conformation with. As a non-limiting example, the product may have
properties and/or dimensions that correspond to the target product
properties and/or dimensions. As another non limiting example, the
AM preform may have properties and/or dimensions that correspond to
the target AM Preform form properties and/or dimensions.
In some embodiments, corresponds refers to corresponding wrought
properties, such that the product is enabled to be used in the same
way (e.g. particular application) with the same success and results
(i.e. within specification and property limits for that product
part) as that predicted for the target product wrought
properties.
In some embodiments, corresponds refers to corresponding dimensions
of the body and/or internal passage (channel and/or void) that
enables the AM preform to be deformed appropriately and/or the
product to be used in the same way (e.g. particular application)
with the same success and results (i.e. within specification and
property limits for that product part) as that predicted for the
target product dimensions.
As non-limiting examples, corresponding the product to the target
may be measured qualitatively (i.e. the product is within spec and
works for the particular purpose/end use application) or
quantitatively (i.e. product properties (or average particle
properties) are within a percentage of or specific threshold or
range of a particular parameter.
As used herein: "filler material" means: a material configured to
fill a void or area. In some embodiments, the filler material is
configured to fill the internal passage(s) in an AM preform, where
the internal passage(s) include at least one of: an
interior/internal void and a channel. Some non-limiting examples of
filler materials (incompressible materials) include: oils,
polymers, organic and/or inorganic solvents (e.g. water) metals
and/or metal alloys, including tin, tin alloys, copper, copper
alloys, and combinations thereof.
In some embodiments, the filler material is chosen so as to be in a
fluid state during the subsequent high temperature operations. In
some embodiments, the filler material is chosen so as to be in a
liquid state during the subsequent high temperature operations.
In some embodiments, the filler material is compliant and/or
incompressible. In some embodiments, the filler material is
configured to provide reaction to the hydrostatic stresses that are
imposed during a forging operation without constraining the bulk
deformation. In some embodiments, the filler material is a liquid.
In some embodiments, the filler material is a solid (e.g. during
deformation). In some embodiments, the filler material is this
regard, an inert liquid which does not undergo significant surface
reactions with the AM Preform.
In some embodiments, the liquid filler material is enclosed within
the AM preform. In some embodiments, the liquid filler material in
the AM preform is restricted from leaking from the AM preform
during the deformation step. In some embodiments, the AM preform is
sealed (with an enclosure component) to prevent the liquid filler
material from leaking from the AM preform during deformation.
In some embodiments, the filler material is a solid material that
is configured with a low flow stress would also be applicable. In
some embodiments, the solid material is configured with a melting
point such that it can be inserted into the AM preform (e.g. filled
easily) and is solid at deformation conditions (e.g. temperature).
In some embodiments, the solid filler material is configured to be
filled into the internal passages of the AM preform and removed
from the internal passages product easily (i.e. melting point above
deformation temperature, but not too high as to impact the wrought
properties obtained in the deformation step with removing the
filler material from the product).
In some embodiments, the AM preform is configured with a body
having/including at least one internal passage (e.g. void and/or
channel), where the body is configured with a preform body
dimension (e.g. size and shape) and the void is configured with a
preform void dimension (e.g. size and shape) such that, via the
deformation step, the body, including the void, undergoing a
deformation to create a product (i.e. the product having body with
a product body dimension and a void with a product void dimension,
where the product dimensions of the body and void (after
deformation) differ from the preform dimensions of the body and the
void). In some embodiments, the filler material is removed from the
product to provide a product having wrought properties and internal
passages (e.g. voids).
In one embodiment, a method includes using additive manufacturing
to produce an AM preform (e.g. a metal shaped-preform) having at
least one passage (e.g. internal passage). After the casing step,
inserting (e.g. filling) a filler material (e.g. incompressible
material) into the passage. The passage is filled with the filler
material and the filler material is enclosed within the body of the
AM preform (e.g. sealed shut). After the inserting step, the AM
preform is deformed (e.g. plastically deformed) into a product
(e.g. final deformed product) having corresponding deformed
passage.
In this embodiment, the filler material/incompressible material is
configured to provide stability (e.g. compressive force) to the
interior wall of the body (defining the passage) such that the
inner wall of the body defining the passage is configured to
prevent, reduce and/or eliminate cracking and/or collapsing of the
passage during the deformation step. Through one or more of the
instant methods, an AM preform configured with at least one
internal passage undergoes a deformation step to provide a product
having wrought properties and at internal passage, wherein the
passage is configured in the product after the deformation step,
and the product is configured with wrought properties.
As used herein: "AM preform" tins an additive manufacturing part
built with a particular dimension (i.e. size and/or shape). In some
embodiments, the AM preform is configured to undergo a deformation
step to create the product. IN some embodiments, the AM preform is
a metal-shaped preform.
In some embodiments, the AM preform may be comprised of a high
entropy alloy. In one embodiment, the metal preform comprises at
least one of titanium, aluminum, nickel, steel, and stainless
steel. In one embodiment, the metal shaped-preform may be a
titanium alloy. In another embodiment, the metal shaped-preform may
be an aluminum alloy. In yet another embodiment, the metal
shaped-preform may be a nickel alloy. In yet another embodiment,
the metal shaped-preform may be one of a steel and a stainless
steel. In another embodiment, the metal shaped-preform may be a
metal matrix composite. In yet another embodiment, the metal
shaped-preform may comprise titanium aluminide.
As used herein: "internal passage" means: at least one of a void
and a channel configured within a body of an AM preform. In some
embodiments, the internal passage is defined by an inner sidewall
of the body of the AM preform, which extends down into the body of
the AM preform via an opening in the outer sidewall of the AM
preform.
As used herein: "enclosure" means: an area that is sealed off with
a barrier. In some embodiments, the AM preform includes an
enclosure (e.g. enclosure device) to retain the filler material
(i.e. liquid filler material) in the internal passage (i.e. at
least one of: a void and a channel). Some non-limiting examples of
enclosures include: mechanical attachment devices, caps, plugs,
threaded plugs, welded plugs, welded enclosures, additively
manufactured layers, and/or a combination thereof.
As used herein, "deformation" means: a process configured to
distort preform into the shape of a product. There are many
processing parameters to achieve deformation including forging,
rolling, extrusion, and combinations thereof, and the like.
In some embodiments, the deforming step may comprise multiple
deforming steps. In some embodiments, the deforming step may
comprise a single deforming step. In some embodiments, the final
desired shape may be achieved with a single deforming step. In some
embodiments, deforming comprises at least one of: forging,
thermomechanical processing, and cold working.
In one embodiment, forging comprises a single die forging step.
In some embodiments, the deformation (e.g. plastic deformation) is
conducted at temperatures in which the filler material is trapped
hydrostatically and the passages maintain the desired contiguous
shape for the final application.
In some embodiments, the AM preform is configured (e.g. optimized)
using computer modeling software. One non-limiting example of
computer modeling is finite element modeling, including reverse 3-D
modeling. In some embodiments, the modeling, designing step is
configured to promote/ensure that a desired (target) wrought
structure and geometry (target dimension) is achieved with minimal
work (i.e. post deformation working), while accounting for
frictional and thermal boundary conditions of the deformation
process.
In some embodiments, the passage is on the interior of the
shaped-preform (e.g. internal to the body). In some embodiments,
the fluid is a liquid. Any suitable filler material that has
sufficient hydrostatic and desired chemical properties under the
deforming condition (i.e. non-reactive with the surface of the AM
preform) to result in passages having the desired shape in the
final product may be used.
In some embodiments, the passage (i.e. internal channel) changes
shape during the deforming step.
In some embodiments, the passage (i.e. internal channel) maintains
shape during the deforming step.
In some embodiments, the method further comprises sealing the
passage after the inserting step. In some embodiments, the method
further comprises unsealing the passage (removing the
enclosure/enclosure component) after the deforming step. In some
embodiments, the passage is sealed with an inert metal having a
relatively low melting point, such as tin, and/or a glass, such as
boron oxide.
Forging may comprise heating the metal shaped-preform to a stock
temperature, and contacting the metal shaped-preform with a forging
die. In one embodiment, when the contacting step is initiated, the
forging die may be a temperature that is at least 10.degree. F.
lower than the stock temperature. In another embodiment, when the
contacting step is initiated, the forging die is a temperature that
is at least 25.degree. F. lower than the stock temperature. In yet
another embodiment, when the contacting step is initiated, the
forging die is a temperature that is at least 50.degree. F. lower
than the stock temperature. In another embodiment, when the
contacting step is initiated, the forging die is a temperature that
is at least 100.degree. F. lower than the stock temperature. In yet
another embodiment, when the contacting step is initiated, the
forging die is a temperature that is at least 200.degree. F. lower
than the stock temperature.
In some embodiments, deforming comprises at least one of: (i)
rolling, (ii) ring rolling, (iii) ring forging, (iv) shaped
rolling, (v) extruding, and (vi) combinations thereof, in addition
to forging.
As used herein, "ring rolling" means the process of rolling a ring
of smaller diameter (e.g., a first ring having a first diameter)
into a ring of larger diameter (e.g., a second ring having a second
diameter, wherein the second diameter is larger than the first
diameter), optionally with a modified cross section (e.g., a cross
sectional area of the second ring is different than a cross
sectional area of the first ring) by the use of two rotating
rollers, one placed in the inside diameter of the ring and the
second directly opposite the first on the outside diameter of the
ring. As used herein, "ring forging" means the process of forging a
ring of smaller diameter (e.g., a first ring having a first
diameter) into a ring of larger diameter (e.g., a second ring
having a second diameter, wherein the second diameter is larger
than the first diameter), optionally with a modified cross section
(e.g., a cross sectional area of the second ring is different than
a cross sectional area of the first ring) by squeezing the ring
between two tools or dies, one on the inside diameter and one
directly opposite on the outside diameter of the ring. As used
herein, "shaped rolling" means the process of shaping or forming by
working the piece (i.e., the metal shaped-preform) between two or
more rollers, which may or may not be profiled, to impart a
curvature or shape to the work piece (i.e., the metal
shaped-preform).
In some embodiments, the deforming step comprises heating the metal
shaped-preform to a stock temperature, and contacting the metal
shaped-preform with a forging die. In this regard, the contacting
step may comprise deforming the metal shaped-preform via the
forging die. In one embodiment, the contacting step comprises
deforming the metal shaped-preform via the forging die to realize a
true strain of from 0.05 to 1.10 in the metal shaped-preform. In
another embodiment, the contacting step comprises deforming the
metal shaped-preform via the forging die to realize a true strain
of at least 0.10 in the metal shaped-preform. In yet another
embodiment, the contacting step comprises deforming the metal
shaped-preform via the forging die to realize a true strain of at
least 0.20 in the metal shaped-preform. In another embodiment, the
contacting step comprises deforming the metal shaped-preform
preform via the forging die to realize a true strain of at least
0.25 in the metal shaped-preform. In yet another embodiment, the
contacting step comprises deforming the metal shaped-preform via
the forging die to realize a true strain of at least 0.30 in the
metal shaped-preform. In another embodiment, the contacting step
comprises deforming the metal shaped-preform via the forging die to
realize a true strain of at least 0.35 in the metal shaped-preform.
In another embodiment, the contacting step comprises deforming the
metal shaped-preform via the forging die to realize a true strain
of not greater than 1.00 in the metal shaped-preform. In yet
another embodiment, the contacting step comprises deforming the
metal shaped-preform via the forging die to realize a true strain
of not greater than 0.90 in the metal shaped-preform. In another
embodiment, the contacting step comprises deforming the metal
shaped-preform via the forging die to realize a true strain of not
greater than 0.80 in the metal shaped-preform. In yet another
embodiment, the contacting step comprises deforming the metal
shaped-preform via the forging die to realize a true strain of not
greater than 0.70 in the metal shaped-preform. In another
embodiment, the contacting step comprises deforming the metal
shaped-preform via the forging die to realize a true strain of not
greater than 0.60 in the metal shaped-preform. In yet another
embodiment, the contacting step comprises deforming the metal
shaped-preform via the forging die to realize a true strain of not
greater than 0.50 in the metal shaped-preform. In another
embodiment, the contacting step comprises deforming the metal
shaped-preform via the forging die to realize a true strain of not
greater than 0.45 in the metal shaped-preform. As used herein "true
strain" (.epsilon..sub.true) is given by the formula:
.epsilon..sub.true=ln(L/L.sub.0) Where L.sub.0 is initial length of
the material and L is the final length of the material.
In one aspect, the step of using additive manufacturing to produce
a metal shaped-preform may comprise adding material, via additive
manufacturing, to a building substrate thereby producing the metal
shaped-preform. In one embodiment, the material is a first material
having a first strength and wherein the building substrate is
comprised of a second material having a second strength. The first
material may have a first fatigue property and the second material
may have a second fatigue property. For example, a layer of a first
material having low strength and high roughness could be added, via
additive manufacturing, to a building substrate comprised of a
second material having high strength and low toughness, thereby
producing a metal-shaped preform useful, for example, in ballistic
applications.
In one embodiment, the building substrate comprises a first ring of
a first material, and the using step comprises adding a second
material, via additive manufacturing, to the first ring thereby
forming a second ring, wherein the second ring is integral with the
first ring.
In some embodiments, the shaped-preform may realize a first amount
of residual stress due to, at least in part, the additive
manufacturing step. After the additive manufacturing and inserting
a filler material into the passage, at least a portion of the
additively manufactured shaped-preform may be cold worked, thereby
relieving stress in cold worked portions of the shaped-preform. At
least some of the cold worked portions of the shaped-preform may
realize a second amount of residual stress due, at least in part,
to the cold working step, wherein the second amount of residual
stress is lower than the first amount of residual stress.
Optionally, after the cold working, the shaped-preform may be
thermally treated at temperatures of not greater than 450.degree.
F. (232.2.degree. C.) to potentially further stress relieve and/or
strengthen the shaped-preform.
Additive manufacturing (3-D printing) is a process where layers of
a material are deposited one after another using various
techniques. Additive manufacturing may include powder bed
technology such as Selective Laser Sintering (SLS). Selective Laser
Melting (SLM), and Electron Beam Melting (EBM), among others.
Additive manufacturing may also include wire extrusion technologies
such as Fused Filament Fabrication (FFF), among others. Suitable
additive manufacturing systems include the EOSINT M 280 Direct
Metal Laser Sintering (DMLS) additive manufacturing system,
available from EOS GmbH (Robert-Stirling-Ring 1, 82.152
Krailling/Munich, Germany). Thus, precisely designed products can
be produced.
The metal shape-preform may be made from any metal suited for both
additive manufacturing and deforming, including, for example metals
or alloys of titanium, aluminum, nickel (e.g., INCONEL), steel,
stainless steel, and high entropy alloys among others. An alloy of
titanium is an alloy having titanium as the predominant alloying
element. An alloy of aluminum is an alloy having aluminum as the
predominant alloying; element. An alloy of nickel is an alloy
having nickel as the predominant alloying element. An alloy of
steel is an alloy having iron as the predominant alloying element,
and at least some carbon. An alloy of stainless steel is an alloy
having iron as the predominant alloying element, at least some
carbon, and at least some chromium. A high entropy alloy is an
alloy having at least five principal elements, each of which has an
atomic concentration between 5% and 35%.
As discussed above, additive manufacturing may be used to produce a
shaped-preform. An aluminum alloy body is a body comprising
aluminum and at least one other substance, wherein the aluminum
comprises at least 50 wt. % of the body. Examples of aluminum
alloys that may be in additively manufactured include the 1xxx,
2xxx, 3xxx, 4xxx, 5xxx, 6xxx, 7xxx, and 8xxx aluminum series
alloys, as defined by The Aluminum Association. In one embodiment,
the aluminum alloy is a 1xxx series aluminum alloy. In one
embodiment, the aluminum alloy is a 2xxx series aluminum alloy. In
one embodiment, the aluminum alloy is a 3xxx series aluminum alloy.
In one embodiment, the aluminum alloy is a 4xxx series aluminum
alloy. In one embodiment, the aluminum alloy is a 5xxx series
aluminum alloy. In one embodiment the aluminum alloy is a 6xxx
series aluminum alloy. In one embodiment, the aluminum alloy is a
7xxx series aluminum alloy. In one embodiment, the aluminum alloy
is a 8xxx series aluminum alloy.
In one aspect, residual stress may be imparted to the
shaped-preform, for example, via the additive manufacturing
process. As used herein, "residual stress" is the stress present in
a shaped preform in the absence of external load on the
shaped-preform. Residual stress of a shaped-preform may be measured
via the "Slitting Method", as described in "Experimental Procedure
for Crack Compliance (Slitting) Measurements of Residual Stress,"
by M. B. Prime, LA-UR-03-8629, Los Alamos National Laboratory
Report, 2003 procedure. Residual stress may be measured in units of
1,000 pounds per square inch (ksi). Residual stress may comprise
compressive residual stress and/or tensile residual stress.
Compressive residual stress may be expressed as a negative value,
e.g., -15 ksi. Tensile stress may be expressed as a positive value,
e.g., 10 ksi. Accordingly, second amount of residual stress being
"lower" than a first amount of residual stress means that the
magnitude i.e., absolute value) of the second amount of stress is
smaller than the magnitude of the first amount of residual
stress.
As discussed above, after the using step and inserting a filler
material into the passage, at least a portion of the additively
manufactured shaped-preform may be cold worked, thereby relieving
stress in cold worked portions of the shaped-preform. As used
herein, "cold working" and the like means deforming a
shaped-preform in at least one direction and at temperatures below
hot working temperatures (e.g., not greater than 250.degree. F.
(121.1.degree. C.)). Cold working may be imparted by one or more of
compressing, stretching, and combinations thereof, among other
types of cold working methods. Compressing means pushing at least
one surface of a shaped-preform order to deform the shaped preform
by reducing at least one dimension of the shaped-preform.
Compressing includes rolling, forging and combinations thereof.
Stretching means pulling a shaped-preform in order to deform the
alloy body by expanding at least one dimension of the
shaped-preform.
In one embodiment, the cold working of the shaped-preform may be
uniform (i.e., all parts of the shaped-preform may realize
essentially the same amount of deformation). In another embodiment,
the cold working of the shaped-preform may be non-uniform (i.e.,
different parts of the shaped-preform may realize different amounts
of deformation). In one aspect, the cold working of the
shaped-preform may comprise cold working all of the shaped-preform
(e.g., all parts of the shaped-preform may realize at least some
deformation throughout the volume of the shaped-preform. In one
embodiment, the cold working may comprise cold deforming all parts
of the shaped-preform by at least 0.1%. In another embodiment, the
cold working may comprise cold deforming all parts of the
shaped-preform by at least 0.2%. In yet another embodiment, the
cold working may comprise cold deforming all parts of the
shaped-preform by at least 0.3%. In another embodiment, the cold
working may comprise cold deforming all parts of the shaped-preform
by at least 0.4%. In yet another embodiment, the cold working may
comprise cold deforming all parts of the shaped-preform by at least
0.5%. In another embodiment, the cold working may comprise cold
deforming all parts of the shaped-preform by at least 0.6%. In yet
another embodiment, the cold working may comprise cold deforming
all parts of the shaped-preform by at least 0.7%. In another
embodiment, the cold working may comprise cold deforming all parts
of the shaped-preform by at least 0.8%. In yet another embodiment,
the cold working may comprise cold deforming all parts of the
shaped-preform by at least 0.9%. In another embodiment, the cold
working may comprise cold deforming all parts of the shaped-preform
by at least 1.0%. In yet another embodiment, the cold working may
comprise cold deforming all parts of the shaped-preform by at least
1.5%. In another embodiment, the cold working may comprise cold
deforming all parts of the shaped-preform by at least 2.0%. In yet
another embodiment, the cold working may comprise cold deforming
all parts of the shaped-preform by at least 3.0%. In another
embodiment, the cold working may comprise cold deforming all parts
of the shaped-preform by at least 4.0%. In yet another embodiment,
the cold working may comprise cold deforming all parts of the
shaped-preform by at least 5.0%.
In another aspect, the cold working of the shaped-preform may
comprise cold working only a portion of the shaped-preform (i.e.,
some parts of the shaped-preform may realize at least some
deformation, while other parts of the shaped-preform may realize no
deformation). In one embodiment, the cold working comprises cold
deforming only a portion of the shaped-preform by at least 0.1%. In
mother embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 0.2%. In yet another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 0.3%. In another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 0.4. In yet another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 0.5%. In another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 0.6%. In yet another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 0.7%. In another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 0.8%. In yet another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 0.9%. In another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 1.0%. In yet another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 1.5%. In another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 2.0%. In yet another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 3.0%. In another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 4.0%. In yet another
embodiment, the cold working comprises cold deforming only a
portion of the shaped-preform by at least 5.0%.
In one embodiment, during the cold working step, the temperature of
the shaped-preform is not greater than 250.degree. F.
(121.1.degree. C.). In another embodiment, during the cold working
step, the temperature of the shapes-preform is not greater than
225.degree. F. (107.2.degree. C.). In yet another embodiment,
during the cold working step, the temperature of the shaped-preform
is not greater than 200.degree. F. (93.3.degree. C.). In another
embodiment, during the cold working step, the temperature of the
shaped-preform is not greater than 175.degree. F. (79.4.degree.
C.). In yet another embodiment, during the cold working step, the
temperature of the shaped-preform is not greater than 150.degree.
F. (65.6.degree. C.). In yet another embodiment, during the cold
working step, the temperature of the shaped-preform is not greater
than 125.degree. F. (51.7.degree. C.). In yet another embodiment,
during the cold working step, the temperature of the shape preform
is not greater than 100.degree. F. (37.8.degree. C.). In one
embodiment, the cold working step is initiated when the
shaped-preform is at ambient temperature.
In one embodiment, the cold working may occur only after the using
additive manufacturing step is complete (e.g., only the final
version of the additively manufactured alloy body is cold worked).
Thus, prior to the cold working step, the method may be free of any
other cold working steps. In one embodiment, the cold working step
comprises cold deforming the shaped-preform by not greater than
25%. In another embodiment, the cold working step comprises cold
deforming the shaped-preform by not greater than 20%. In yet
another embodiment, the cold working step comprises cold deforming
the shaped-preform not greater than 15%. In another embodiment, the
cold working step comprises cold deforming the shaped-preform by
not greater than 14%. In yet another embodiment, the cold working
step comprises cold deforming the shaped-preform by not greater
than 13%. In another embodiment, the cold working step comprises
cold deforming the shaped-preform by not greater than 12%. In yet
another embodiment, the cold working step comprises cold deforming
the shaped-preform by not greater than 11%. In another embodiment,
the cold working step comprises cold deforming the shaped-preform
by not greater than 10%.
In one aspect, relieving residual stress in the additively
manufactured shaped-preform via the above-described methods may
provide improved strength properties as compared to relieving
residual stress via annealing the shaped-preform. For example, the
shaped-preform may realize increased tensile yield strength as
compared to a similar shaped-preform which has been annealed to
relieve stress. Thus, in one embodiment, the method of production
is free of any anneal and/or solution heat treatment step between
the using additive manufacturing step and the cold working step.
Thus, during production of the shaped-preform, after the additively
manufacturing step, the shaped-preform may be maintained at a
temperature of not greater than 450.degree.. In other embodiments,
during production of the shaped-preform, after the additively
manufacturing step, the shaped-preform is maintained at a
temperature of not greater than 400.degree. F., such as not greater
than 375.degree. F. or not greater than 350.degree. F. or not
greater than 325.degree. F., or not greater than 300.degree. F., or
not greater than 275.degree. F., or not greater than 250.degree.
F., or not greater than 225.degree. F., or not greater than
200.degree. F., or not greater than 175.degree. F., or not greater
than 150.degree. F., or not greater than 125.degree. F., or not
greater than 100.degree. F., or not greater than ambient (not
including any heat generated due to the cold working step).
In other embodiments, after the cold working step, the
shaped-preform may be thermally treated. The thermal treatment may
further stress relieve and/or strengthen one or more portions of
the shaped-preform. For instance, for precipitation hardenable
alloys, the thermal treatment may result in precipitation hardening
of one or more portion of the shaped-preform. The thermal treatment
may also or alternatively stress relieve the shaped-preform. This
optional thermal treatment step may occur at a temperature of from,
for example, 175.degree. F. (79.4.degree. C.) to 450.degree. F.
(232.2.degree. C.) and rain several minutes to several hours,
depending on temperature.
By deforming the metal shaped-preform, the final product may
realize improved properties, such as improved porosity (e.g., less
porosity), improved surface roughness (e.g., less surface
roughness, i.e., a smoother surface), and/or better mechanical
properties (e.g., improved surface hardness), among others.
In one aspect, after the forging step the final forged product may
optionally be annealed. Annealing is a heat treatment that alters
the physical and sometimes chemical properties of a material to
increase its ductility and to make it more workable. It involves
heating a material to above its glass transition temperature,
maintaining a suitable temperature, and then cooling. Annealing, in
some embodiments, can induce ductility, soften material, relieve
internal stresses, refine the structure by making it homogeneous,
and improve cold working properties.
The annealing step may facilitate the relieving of residual stress
in the metal-shaped preform due to the forging step. In some
embodiments, the annealing time is at least about 1 hour. In
another embodiment, the time is at least about 2 hours. In yet
another embodiment, the time is not greater than about 4 hours. In
another embodiment, the time is not greater than about 3 hours.
In one embodiment, the metal shaped-preform is a low ductility
material, such as a metal matrix composite or an intermetallic
material. In one embodiment, the metal shaped-preform is titanium
aluminide. Using the new processes disclosed herein may facilitate
more economical production of final forged products from such low
ductility materials. For instance, the low ductility materials may
be forged using dies and/or tooling that are at a lower temperature
than the low ductility material. Thus, in one embodiment, the
forging is absent of isothermal forging (i.e., the forging process
does not include isothermal forging), and thus can include any of
the stock temperature versus die temperature differentials noted in
the above-paragraph.
The step of preparing the metal shaped-preform via additive
manufacturing may include incorporating a building substrate into
the metal shaped-preform. In one embodiment, material is added to a
building substrate via additive manufacturing to produce the metal
shaped-preform. As used herein, "building substrate" and the like
means a solid material which may be incorporated into a metal
shaped-preform. The metal shaped-preform, which includes the
building substrate, may be deformed. Thus, the final product may
include the building substrate as an integral piece.
As mentioned above, a final forged product may realize an amount
(e.g., a pre-selected amount) of true strain due to the contacting
step. In some embodiments, the strain realized by the final forged
product may be non-uniform throughout the final forged product due
to, for example, the shape of the forcing dies and/or the shape of
the metal shaped-preform. Thus, the final forged product may
realize areas of low and/or high strain. Accordingly, the building
substrate may be located in a predetermined area of the metal
shaped-preform such that after the forging, the building substrate
is located in a predetermined area of low strain of the final
forged product. An area of low strain may be predetermined based on
predictive modeling or empirical testing.
The building substrate may have a predetermined shape and/or
predetermined mechanical properties (e.g., strength, toughness to
name a few). In one embodiment, the building substrate may be a
pre-wrought base plate. In one embodiment, the shape of the
building substrate may be predetermined based on the shape of the
area of low strain. In one embodiment, the mechanical properties of
the building substrate may be predetermined based on the average
true strain realized by the metal shaped-preform and/or the true
strain realized within the area of low strain. In one embodiment,
two or more building substrates may be incorporated into a
metal-shaped preform. In one embodiment, the building substrate
comprises a pre-wrought base plate.
The building substrate may be made from any metal suited for both
additive manufacturing and forging, including, for example metals
or alloys of titanium, aluminum, nickel (e.g., INCONEL), steel, and
stainless steel, among others. In one embodiment, the building
substrate is made of the same material(s) as the rest of the
metal-shaped preform. In one embodiment, the material added to the
metal shaped preform may be a first material, whereas the building
substrate may be made of a second material. In one embodiment, the
first material may have a first strength and the second material
may have a second strength. In one embodiment, the first material
may have a first fatigue property and the second material may have
a second fatigue property.
In some embodiments, the following benefits are expected: healing
of porosity, wrought microstructure, net shape geometry with
improved surface finish, internal passages as required by desired
application.
In some embodiments, localized compressive stress is applied around
the internal passages in order to enhance fatigue performance of
the metal around and near the internal passages.
In some embodiments, a final product with superior properties,
better shape tolerance and surface attributes and product features
is attained by combining three independent technologies, additive
manufacturing, thermomechanical processing and reverse 3-D
modeling. Some embodiments may be ideally suited for applications
such as turbine blades and other high temperature demanding
components.
While various embodiments of the present disclosure have been
described in detail, it is apparent that modification and
adaptations of those embodiments will occur to those skilled in the
art. However, it is to be expressly understood that such
modifications and adaptations are within the spirit and scope of
the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic of an embodiment of the FEM modeling
completed to design an AM preform having a body dimension and
internal passage dimension configured to undergo deformation (i.e.
with a filler material retained within the internal passage) and
provide a product form having a final body dimension and internal
passage dimension, in accordance with the instant disclosure.
FIG. 2 depicts a cut away side view of a portion of the computer
model results of the initial geometry of the AM preform (left) and
final geometry of the product (right) expected utilizing the
computer modeling approach, in accordance with one or more
embodiments of the instant disclosure.
FIG. 3 is a graph depicting the computer modeled flow curve during
deformation at 300.degree. C. and a strain rate of 0.005/sec,
showing stress (MPa) as a function of Strain. As depicted in FIG.
3, upon straining (deforming) the AM preform, Stress immediately,
sharply increases and levels off to about 115 MPa at approximately
0.02-0.03.
FIG. 4 provides two top view photographs depicting embodiments of
two products made via a deformation step at 300.degree. C. (i.e.
with filler material initially retained within the cavity), in
accordance with the disclosure. Referring to FIG. 4, the
mechanically sealed AM preform exhibited leaking of filler
material, as did the welded plug seals depicted on the right.
FIG. 5 depicts two photographs of cross-sectional views of the
embodiments of the products from FIG. 4, depicting the filler
material retained in the internal passages, although some leaking
was observed adjacent to the enclosure component (e.g. mechanical
seal/interference plug and welded seal/plug), in accordance with
the instant disclosure. Without being bound by any particular
mechanism or theory, it is believed that the collapse of feed
passages and cracking of internal passages shown in FIG. 5 is
attributable to the failure of the seals (leaking) depicted in FIG.
4.
FIG. 6 depicts a top plan view photograph of the product deformed
at 200.degree. C., under constant load conditions, in accordance
with the instant disclosure. Since the filler material was deformed
at temperature conditions where the filler was solid, no leaking
occurred.
FIG. 7 depicts photographs of cross sections of two embodiments in
accordance with the instant disclosure. On the left, a proxy for
the "before" AM preform is depicted, wherein the AM preform body is
a control AM preform (that did not undergo a deformation step prior
to cross-sectioning), where the AM preform is configured with
preform body dimensions (i.e. slightly concave sidewalls along the
non-deformation surface of the body) and preform internal passage
dimensions (i.e. elliptically shaped void), where the fill material
is shown filling the internal passage (e.g. channels and void),
further wherein the interference plugs are shown extending, from
the upper surface of the body into the opening of the internal
passage (and extending down into a given distance into the
channel). On the right, the image of the cross-section of the
embodiment of the product "after" deformation step is in stark
contrast with the "before" AM preform on the left. More
specifically, the product or "after" embodiment shows product body
dimensions with as shorter height of the product, and the concave
walls of the AM preform have been directed in an outward direction
to a near perpendicular when compared to the product body top and
bottom surfaces. Moreover, the internal passage is configured with
product internal passage dimensions (i.e. the void was transformed
by deformation from an elliptical shape to a circular shape), and
the channels have also undergone axial shrinking and a slight
increase in perceived diameter of the channel, via the deformation
step. As can be seen from FIG. 7, the internal cavities deformed
uniformly and there was no minimal evidence of cavity collapse or
cracking in the passages.
FIG. 8 depicts the embodiments of FIG. 7, once the filler material
was removed (melted and removed) from the internal passage (e.g.
void and channels). As visually observable, after removing the
filler material (tin) there was little to no chemical reactivity
and/or wettability of materials. Also, it is noted the integrity of
feed passages was maintained after deformation and there was
minimal (if any) cracking observed in the internal passages.
FIG. 9 depicts the real profile of the samples before and after
deformation. Without being bound by a particular mechanism and/or
theory, it is believed that the slight bar cling visually
observable after deformation is attributable to the friction
between the platens and the work piece.
FIG. 10 depicts a schematic cross-sectional view of an embodiment
of the method, depicting the steps of creating (designing) an AM
preform based on the final product specifications (body dimension
and internal passage dimension), additively manufacturing an AM
preform having the body dimensions and internal passage dimensions
inserting (and enclosing) the filler material within the AM
preform, and deforming the AM preform to create a product having
the product specifications (body dimension and internal passage
dimension) after deforming, in accordance with the instant
disclosure.
FIG. 11 depicts a cut-away side view of an AM preform with preform
extensions configured away from deformation faces of the body
filled with solid filler material. As depicted in FIG. 11, the cap
enclosures are also configured outside elm, from the deformation
faces.
DETAILED DESCRIPTION
A series of experiments were completed in order to evaluate the
several of the embodiments of the instant disclosure.
Example: Computer Modeling of AM Preform and Product
A computer modeling approach was evaluated to select parameters of
the AM preform (e.g. body dimension and void dimension) to provide
a resulting product having a product body dimension and product
void dimension. Finite Element Modeling was completed, such that
reverse shape modeling was used to account for the deformation and
initial (AM preform) vs. final (product) boundary conditions (body
dimensions and void dimensions) in the components.
A true strain of 50% was selected as a bogie for validation and it
was assumed that there was no die friction, that the cavity was
filled (i.e. completely filled) with an incompressible fluid, and
that incompressible filler material was retained in the AM preform
via sealing (e.g. enclosure sufficient to retain the filler
material during deformation conditions). A final internal passage
(void) in the product was targeted to be a 0.25'' diameter circle
(D=0.25''). Accordingly, an elliptical shape with the cross
sectional area of the desired circle size a id aspect ratio
necessary to become circular after deformation was calculated as
shown in FIG. 1. The initial shape (of body and internal passage,
including void and channel) was estimated by a trial and error
procedure to obtain a near straight edge after deformation and a
circular shape for the internal passages.
FIG. 1 is a schematic of an embodiment of the FEM modeling
completed to design an AM preform having a body dimension and
internal passage dimension configured to undergo deformation (i.e.
with a filler material retained within the internal passage) and
provide a product form having a final body dimension and internal
passage dimension initial geometry of the AM component, in
accordance with the instant disclosure. Depicted in FIG. 1 is the
cut-away side view of an engineering drawing of the AM preform
designed in the corresponding Example section, a table depicting
some of the parameters of the AM preform (e.g. dimensions), a
mathematical algorithm utilized in the FEM modeling, and a
perspective cut away view of the cross-section depicted in the
engineering drawing, depicting the differing three-dimensional
depths of the void and the channels of the internal passage, as
well as the concavity of the body sidewall (e.g., at the
non-deformation surface sidewall), accordance with one or more
embodiments of the instant disclosure.
FIG. 2 depicts a cut away side view of a portion of the computer
model results of the initial geometry of the AM preform (left) and
final geometry of the product (right) expected utilizing the
computer modeling approach, in accordance with one or more
embodiments of the instant disclosure. With reference to FIG. 2,
the initial geometry and final expected geometry are depicted after
deformation, under isothermal conditions, and frictionless
axisymmetric compression. FIG. 2 (initial vs. final) contrasts the
different external shape profile (loss of concavity of sidewall
from preform to product) as well as the change in shape of the
internal cavity (preform depicts an elliptical portion vs. product
depicts a circular portion).
Example: AM Preform Build with Filler Material (Incompressible
Material)
Four identical AM preforms were additively manufactured using a
laser powder bed additive manufacturing process on the EOS M280.
The feedstock material used to make the parts was an AlSi10Mg alloy
powder.
A 2'' diameter and 2'' high cylindrical sample was chosen as a
prototype sample for experimental validation, based on factors
including internal passage size and tonnage limit on the
deformation simulator. Each AM preform was configured with a
concentric internal void, where the void was configured with two
corresponding channels configured to communicate from the void to
the surface of the body of the AM preform. The two vertical
passages (channels) in the AM preforms were utilized to enable
filling the cavity via one channel while and the other to bleeding
the air during filling and ensure a proper and complete fill.
Three of the AM preforms were heated to a temperature of
325.degree. C. and then filled with a filler material using a tin
feed rod of 0.125 inch diameter which melted in situ (in the
cavity). Complete fill was confirmed by visually observing molten
tin from the bleed passage (i.e. second channel). The feed and
bleed ports (channels) were closed (e.g. sealed) either by: plugs
with interference fit or by plugging the openings of the channels
and then welding them with 6061 filler alloy.
Example: AM Preform Deformation
A deformation simulator was utilized on the three AM preforms. The
deformation simulator was a compression machine (press) with a
capacity of 150,000 lbs, configured with a furnace to heat the
press surfaces and/or AM preform to deform via hot compression. The
deformation simulator of this experimental section was utilized as
a proxy for a single step forging die, where the simulator allowed
for control over temperature, strain rate and strain of the AM
preform to make a product having wrought properties.
During deformation, the furnace was heated up to the indicated
temperature and deformation was completed (e.g. with heated
surfaces of the press). In addition, there were PTFE polymer sheets
configured between the AM preform deformation surfaces (upper and
lower surfaces of the AM preform) and the press surfaces to promote
frictionless surfaces of deformation. The estimated internal
hydrostatic pressure was 5.5 KSI, and it is noted that the
hydrostatic pressure during uniaxial deformation is about 1/3 of
the applied flow stress.
Two samples tone with an interference fit plug and one with welded
plugs) were then deformed in axisymmetric compression at
300.degree. C. and a strain rate of 0.005/sec. A hold time of 30
minutes prior to deformation was provided to ensure that the tin
filler was completed melted prior to deformation. FIG. 3 shows the
flow curve as measured during deformation.
As can be seen in FIG. 5, molten tin is depicted on top of the
product, which indicates that leakage occurred. Without being bound
by a particular mechanism or theory, the leakage of molten tin
during deformation is believed to be the cause of the resulting
collapse of the cavity and/or cracking of the cavity (i.e. leaking
resulted in uncontrolled distortion of the internal passages during
deformation).
The third sample was deformed in the deformation simulator at a
temperature of 200.degree. C., such that the filler material (tin)
was maintained in a solid state during deformation in order to
prevent escape from the cavity/void (leaking). This experiment was
completed under constant load, as the maximum tonnage on the
simulator was exceeded in maintaining the desired strain rate of
0.005/sec. As shown in FIG. 6, there was no evidence of any molten
tin leakage on the top surface of the product.
It was observed that filling the cavity (internal passage) with a
molten filler material which solidifies before/during deformation
provided a suitable product and corresponding cavity. Also, while
it was observed that both molten filler material runs leaked, it
was unclear if each of the seals was complete/appeared as
sufficient prior to deformation, such that it would be expected to
retain the molten filler material during deformation at a pressure
of 5.5 KSI.
Based on the above experiments, without being bound by any
particular mechanism or theory, it is believed that deformation of
AM preforms with molten filler material configured in (e.g.
enclosed and/or sealed within) at least one internal passage(s)
will result in products having internal passages (e.g. voids and/or
channels) in accordance with the instant disclosure, so long as
sufficient enclosures/seals of the molten filler material are in
place prior to (and during) deformation.
Prophetic Example: Enclosure of Fill Material with AM Build Layers
in AM Preform
As an alternative embodiment, the filler material is enclosed in
the internal passage of an AM preform during the AM build process.
More specifically, a filler material is added to an AM preform, (if
needed) allowed to solidify, and then additive manufacturing is
resumed, such that additional build layers are configured over the
opening to form an AM enclosure that retains the filler material
within the AM preform.
In yet another embodiment, if the filler material is liquid at
additive manufacturing conditions, then a cover (e.g. substrate
configured to extend across the opening of the internal passage) is
fitted into/onto the opening, followed by successive additive
manufacturing build layers to enclose the filler material into the
internal passage.
In another embodiment, after the filler material is added to the
internal passage, the opening is capped (e.g. with a small plug),
the surface is milled (i.e. to create a continuous build surface)
and then returned to the additive machine to deposit at least one
additional build layer onto the cap (and/or over the surface of the
body that is configured with the opening of the internal
passage).
In one or more of these embodiments, additional build layers are
configured to provide an enclosure with a predetermined thickness
(i.e. sufficient to retain the filler material in the internal
passage while undergoing the deformation step).
REFERENCE NUMBERS
AM preform 10 Body 12 Preform body dimension 14 Internal passage
(e.g. void+channel) 16 Void 18 Preform void dimension 20 Channel 22
Channel dimension 22 Opening 24 Enclosure 26 Cap (e.g. plug) 28
Weld 30 AM cover 32 Filler material (e.g. incompressible material)
34 Solid 36 Liquid (e.g. molten or liquid) 38 Within body:
Deformation faces/surface onto which deformation step is applied:
40 (e.g. 40', 40'') Preform extension (e.g. configured for channel
and/cap outside of deformation zone, not on deformation
face/surface) 42 Product 50 Product body dimension 46 Product void
dimension 48
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