U.S. patent application number 12/816413 was filed with the patent office on 2010-10-07 for friction stir method for joining materials having different thicknesses.
This patent application is currently assigned to UT-BATTELLE, LLC. Invention is credited to Stan A. David, Zhili Feng, David Alan Frederick.
Application Number | 20100252171 12/816413 |
Document ID | / |
Family ID | 40732084 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100252171 |
Kind Code |
A1 |
Feng; Zhili ; et
al. |
October 7, 2010 |
Friction Stir Method for Joining Materials Having Different
Thicknesses
Abstract
Methods for joining materials having different thicknesses is
provided. Friction stir material processing is typically used, and
a transition piece may be friction stir welded between the
materials being joined.
Inventors: |
Feng; Zhili; (Knoxville,
TN) ; David; Stan A.; (Knoxville, TN) ;
Frederick; David Alan; (Harriman, TN) |
Correspondence
Address: |
ORNL-UTB-LUEDEKA, NEELY & GRAHAM
P.O. BOX 1871
KNOXVILLE
TN
37901
US
|
Assignee: |
UT-BATTELLE, LLC
Oak Ridge
TN
|
Family ID: |
40732084 |
Appl. No.: |
12/816413 |
Filed: |
June 16, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12051972 |
Mar 20, 2008 |
7762447 |
|
|
12816413 |
|
|
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Current U.S.
Class: |
156/73.5 ;
228/112.1 |
Current CPC
Class: |
B23K 2101/18 20180801;
B23K 20/1225 20130101; B23K 20/128 20130101 |
Class at
Publication: |
156/73.5 ;
228/112.1 |
International
Class: |
B29C 65/06 20060101
B29C065/06; B23K 20/12 20060101 B23K020/12 |
Goverment Interests
GOVERNMENT RIGHTS
[0002] This invention was made with government support under
Contract No. DE-AC05-00OR22725 awarded by the U.S. Department of
Energy. The government has certain rights in the invention.
Claims
1. A method of joining a first portion of a fabrication preform
having a first thickness and second portion of the fabrication
preform having a second thickness comprising: a. disposing a
transition piece between the first portion of the fabrication
preform and the second portion of the fabrication preform wherein
the transition piece has a first edge and a second edge opposed to
the first edge and the transition piece is configured to vary in
thickness from approximately the first thickness at the first edge
to approximately the second thickness at the second edge and
wherein a first joint is formed between the first portion of the
fabrication preform and the transition piece and a second joint is
formed between the transition piece and the second portion of the
fabrication preform; b. friction stir welding at least a portion of
the first joint; and c. friction stir welding at least a portion of
the second joint.
2. The method of claim 1 wherein the first portion of the
fabrication preform and the second portion of the fabrication
preform are portions of the same workpiece.
3. The method of claim 1 wherein the first portion of the
fabrication preform and the second portion of the fabrication
preform are different materials and the transition piece is the
same material as the first portion of the fabrication preform.
4. The method of claim 1 wherein the first the first portion of the
fabrication preform and the second portion of the fabrication
preform and the transition piece are different materials.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This patent application claims priority from and is a
Divisional of U.S. patent application Ser. No. 12/051,972 filed
Mar. 20, 2008, entitled: Multiple Pass and Multiple Layer Friction
Stir Welding and Material Enhancement Processes.
FIELD
[0003] This disclosure relates to the field of friction stir
welding and material processing. More particularly, this disclosure
relates to friction stir material materials that have different
thicknesses.
BACKGROUND
[0004] Friction stir welding (FSW) is a welding process in which a
cylindrical, shouldered welding tool having a pin protruding from
the shouldered surface is rotated and plunged into a joint line
between two portions of a fabrication preform. The portions of the
fabrication preform are typically of metal, but the process may
also be used on various plastics and polymers. Typically the pieces
are clamped together to prevent relative motion between the pieces
during the welding process. Frictional heat is generated between
the pin and the material of the portions of the fabrication
preform. This heat causes the adjacent material to soften
(generally without reaching its melting point). The tool is then
moved relative to the portions of the fabrication preform along a
weld line while the shoulder of the tool is pressed against the
surface of each portion of the fabrication preform. The softened
material is transferred from the leading edge of the pin to the
trailing edge of the pin. The shoulder helps form a flat weld that
is even with the surface of each portion of the fabrication preform
and that, after cooling, bonds the portions of the fabrication
preform together.
[0005] The power required to spin a friction stir tool increases
significantly when the process is applied to thicker and/or harder
materials. Consequently, current friction stir welding processes
are generally best suited for welding aluminum or other
comparatively soft metals with thicknesses of less than
approximately one inch (2.5 cm). What are needed therefore are
improved friction stir welding processes that may be applied to
thicker and/or harder materials.
SUMMARY
[0006] The present disclosure provides a method joining a first
portion of a fabrication preform having a first thickness and a
second portion of the fabrication preform having a second
thickness. In typical embodiments, the method includes a step of
disposing a transition piece between the first portion of the
fabrication preform and the second portion of the fabrication
preform. The transition piece has a first edge and a second edge
opposed to the first edge, and the transition piece is configured
to vary in thickness from approximately the first thickness at the
first edge to approximately the second thickness at the second
edge. A first joint may be formed between the first portion of the
fabrication preform and the transition piece and a second joint is
disposed between the transition piece and the second portion of the
fabrication preform. The method typically also includes a step of
friction stir welding at least portions of the first joint, and a
step of friction stir welding at least a portion of the second
joint.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Various advantages are apparent by reference to the detailed
description in conjunction with the figures, wherein elements are
not to scale so as to more clearly show the details, wherein like
reference numbers indicate like elements throughout the several
views, and wherein:
[0008] FIGS. 1A-1Q are somewhat schematic cross-sectional
illustrations of steps in friction stir welding processes.
[0009] FIGS. 2A-2M are somewhat schematic cross-sectional
illustrations of components and steps used in certain friction stir
processes.
[0010] FIGS. 3A-3C are somewhat schematic cross-sectional
illustrations of seams between edges of two portions of a
fabrication preform that may be joined using friction stir
welding.
[0011] FIG. 4 is a somewhat schematic cross-sectional view of two
friction stir welding tools performing a friction stir welding
operation on the portions of the fabrication preform of FIG.
3B.
[0012] FIGS. 5A-5C depict various features of weld paths and weld
planes used in friCTION STIR WELDING PROCESSES.
[0013] FIGS. 6A and 6C illustrate a friction stir welding process
for joining materials of different thicknesses.
[0014] FIGS. 7A and 7C illustrate a friction stir welding process
for joining materials of different thicknesses.
[0015] FIG. 8 illustrates an example of a friction stir welding
root pass.
[0016] FIG. 9 illustrates an example of a completed multi-pass
demonstration friction stir weld.
[0017] FIGS. 10A-10C are photographs of cross-sections of an
example of a multi-pass friction stir weld at successive stages of
completion.
DETAILED DESCRIPTION
[0018] In the following detailed description of the preferred
embodiments, reference is made to the accompanying drawings, which
form a part hereof, and within which are shown by way of
illustration the practice of specific embodiments of methods of
joining a first portion of a fabrication preform and a second
portion of the fabrication preform using friction stir welding and
embodiments of reinforcing a fabrication preform structure using
friction stir welding. Also depicted are various embodiments for
producing enhanced structures and materials using stir friction
processes. It is to be understood that other embodiments may be
utilized, and that structural changes may be made and processes may
vary in other embodiments.
[0019] FIGS. 1A-1Q illustrate various steps in a multiple-pass and
multiple-layer friction stir welding processes. FIG. 1A depicts a
cross-sectional edge view of a first portion 10 of a fabrication
preform and a second portion 12 of a fabrication. In some
embodiments the first portion 10 of the fabrication preform is a
first workpiece and the second portion 12 of the fabrication
preform is a second workpiece that is to be joined with the first
workpiece. In other embodiments the first portion 10 of the
fabrication preform and the second portion 12 of the fabrication
preform are portions of the same workpiece that are to be joined
together. In some embodiments the first portion 10 of the
fabrication preform and the second portion 12 of the fabrication
preform are composed of substantially the same composition of
material, and in other embodiments the first portion 10 of the
fabrication preform and the second portion 12 of the fabrication
preform may be composed of different compositions of material. When
referring herein to different compositions of material these
differences may be chemical differences and/or physical bulk
property differences such as density differences. The first portion
10 of the fabrication preform has a first edge 14 and the second
portion 12 of the fabrication preform has a second edge 16. The
first edge 14 and the second edge 16 abut and form a joint 18
between the first portion 10 of the fabrication preform and the
second portion 12 of the fabrication preform. The joint 18 has a
first height 20. A first groove 22 is disposed between the first
portion 10 of the fabrication preform and the second portion 12 of
the fabrication preform, adjacent the joint 18. The base of the
first groove 22 forms a first common surface 24 of the first
portion 10 of the fabrication preform and the second portion 12 of
the fabrication preform. The first portion 10 of the fabrication
preform and the second portion 12 of the fabrication preform and a
portion of the joint 18 form a second common surface 26 that is
opposed to the first common surface 24. As used herein, a "common
surface" is a generally flat planar surface formed by two or more
generally adjacent elements. It is understood that some
discontinuities and irregularities may occur in the contour of a
common surface provided that they do not prevent the application of
a friction stir welding process along a path on the common
surface.
[0020] In some embodiments as depicted in FIG. 1B, a back support
piece 28 may be used to help maintain the structural integrity of
the portions of the fabrication preform (e.g., portions of the
fabrication preform 10 and 12) during friction stir welding or
material enhancement processes. The back support piece 28 typically
does not become a portion of the assembly that is formed after
friction stir welding.
[0021] FIG. 1C illustrates an alternate embodiment wherein a bridge
material 30 is disposed between the first portion 10 of the
fabrication preform and the second portion 12 of the fabrication
preform. The first portion 10 of the fabrication preform and the
second portion 12 of the fabrication preform are considered to have
abutting edges (14 and 16) even though the bridge material is
disposed between the first edge 14 and the second edge 16. The
first edge 14 and the second edge 16 and the bridge material 30
form a joint 32 between the first portion 10 of the fabrication
preform and the second portion 12 of the fabrication preform. FIG.
1D depicts an alternate configuration of bridge material 38 that in
part defines a joint 40 between the first portion 10 of the
fabrication preform and the second portion 12 of the fabrication
preform. At least a portion of the bridge material 38 is configured
to be disposed above the first common surface 24 (identified in
FIG. 1A) and that portion of the bridge helps maintain a flow of
bridge material between the first portion 10 of the fabrication
preform and the second portion 12 of the fabrication preform during
friction stir welding. It should be noted that the joint 32 of FIG.
1C and the joint 40 of FIG. 1D (where a filler is disposed between
the edges of portions of a fabrication preform), and the joint 18
of FIG. 1A the joint 18 (where the joint is a seam between the
edges of portions of a preform without an intervening filler) are
each defined as "joints" herein.
[0022] The bridge material 30 or 38 may be useful in cases of
fabrication preform dimensional variations, and/or to form a first
bond between the first portion 10 of the fabrication preform and
the second portion 12 of the fabrication preform that has a
different composition and/or physical properties from either or
both the first and second portions of the fabrication preform (10
and 12). The bridge material 30 or 38 may be composed of
substantially the same composition of material as the first portion
10 of the fabrication preform and/or the second portion 12 of the
fabrication preform, or the bridge material 30 or 38 may be
composed of a composition of material that is different from the
composition of material of the first portion 10 of the fabrication
preform and different from the composition of material of the
second portion 12 of the fabrication preform. In some embodiments
the bridge material 30 or 38 is a composite material. As used
herein the term "composite material" refers to a plurality of
materials with each material being disposed in a separate physical
region of the composite material. In many but not all cases the
materials have different compositions of material. Examples of a
composite material are a metal/metal composite, a cermet composite,
a bundle of wires, a package of layered materials, and other
aggregations of materials having the same or different
compositions. For example, a bundle of wires or rods made of
different materials may be consolidated by thermal/mechanical
processes to synthesize a composite material for use as the bridge
material 30 or 38.
[0023] FIG. 1E shows a starting step of a friction stir welding
process to join the first portion 10 of the fabrication preform and
the second portion 12 of the fabrication preform as configured in
FIG. 1A. A similar starting step may be used to join the first
portion 10 of the fabrication preform and the second portion 12 of
the fabrication preform as configured in FIGS. 1B, 1C, or 1D. FIG.
1E illustrates a friction stir welding tool 42 with a pin 44 that
protrudes from a shoulder surface 46 of the tool 42. To start the
process of friction stir welding, the pin 44 of the tool 42 is
rapidly rotated around the axis of the pin and then typically the
pin 44 is plunged into or proximal to the first seam 18 (identified
in FIG. 1A). In the case of the configuration of FIG. 1C the
shoulder surface 46 of the tool 42 is pressed against the bottom of
the first groove 22 (identified in FIG. 1A). In the case of the
configuration of FIG. 1D the shoulder surface 46 of the tool 42 is
pressed against the top of the filler 38. While the tool 42
continues to rotate, the tool 42 is moved laterally along a weld
path that follows the joint 18 (or the joint 32 in the
configuration of FIG. 1C or the joint 40 in the configuration of
FIG. 1D). This is called a welding pass. The joint 18 (or 32 or 40)
and an associated weld path may follow a straight line, a curved
line, or a jagged line and may comprise a simple planar surface, a
collection of many simple planar surfaces, a non-planar surface, or
a collection of many non-planar surfaces. Material from the first
portion 10 of the fabrication preform that is adjacent the joint 18
(or 32 or 40) and material from the second portion 12 of the
fabrication preform that is adjacent the joint 18 are friction stir
welded to form a first bond 48 (as seen in FIG. 1F). The welding
pass that forms the first friction stir weld (i.e., the first bond
48 in this embodiment) of a multi-pass friction stir weld is
referred to herein as the "root pass."
[0024] As labeled in FIG. 1 G, a first fillet 50 cut into the first
portion 10 of the fabrication preform and a second fillet 52 cut
into the second portion 12 of the fabrication preform form a second
groove 54 between the first portion 10 of the fabrication preform
and the second portion 12 of the fabrication preform. The second
groove 54 is adjacent the first groove 22 (identified in FIG. 1A).
Subsequent to the formation of the first bond 48, a first filler 56
is disposed in at least a portion of the first groove 22 between
the first portion 10 of the fabrication preform and the second
portion 12 of the fabrication preform. Typically the first filler
56 is a solid bar that is inserted into the first groove 22
(identified in FIG. 1A) after the first bond 48 is formed and
before further friction stir welding is performed. In some
embodiments the first filler 56 may be a powder or a paste
material. The first filler 56 may be composed of substantially the
same composition of material as the first portion 10 of the
fabrication preform and/or the second portion 12 of the fabrication
preform, or the first filler 56 may be composed of a composition of
material that is different from the composition of material of the
first portion 10 of the fabrication preform and different from the
composition of material of the second portion 12 of the fabrication
preform. In some embodiments the first filler 56 is a composite
material, such as metal/metal composite, a cermet composite, or a
bundle of wires, layered materials or other forms of mixture of the
same or different materials. For example, a bundle of wires or rods
made of different materials may be consolidated by
thermal/mechanical processes to synthesize the filler 56.
[0025] In the sequence of operations depicted in FIGS. 1A-1Q the
second groove 54 (identified in FIG. 1G) was cut into the first
portion 10 of the fabrication preform and the second portion 12 of
the fabrication preform before any friction stir welding was
performed. However, in alternate embodiments the second groove 54
may, for example, be machined out after the first bond 48 is formed
and either before or after the first filler 56 is disposed in at
least a portion of the first groove 22.
[0026] Continuing further with FIG. 1G, the base of the first
fillet 50, the top of the first filler 56 and the base of the
second fillet 52 form a third common surface 58. A first seam 64 is
formed between the first filler 56 and the first portion 10 of the
fabrication preform and a second seam 66 is formed between the
first filler 56 and the second portion 12 of the fabrication
preform. The first seam 64 and the second seam 66 each have a
second height 68, and the second height 68 is different from the
first height 20 of the joint 18. Configuring different seam heights
may be useful in balancing energy requirements between friction
stir welds in a multi-pass friction stir welding process. It is
understood that a "seam" as described herein (such as the seam 64
or seam 66) and an associated weld path may follow a straight line,
a curved line, or a jagged line and may comprise a simple planar
surface, a collection of many simple planar surfaces, a non-planar
surface, or a collection of many non-planar surfaces.
[0027] Then as depicted in FIG. 1H, a second friction stir tool 70
is used along the first seam 64 (identified in FIG. 1G) to form a
second bond 80, as seen in FIG. 1I. As further depicted in FIG. 1H,
a source of pre-heating 82 may be applied to the material adjacent
the second seam 64 (as identified in FIG. 1G). The preheating 82
may, for example, be provided by a laser, an electric arc, an
induction heating source, an infrared source, an ultrasonic source,
or a microwave source. The preheating 82 typically softens and may
even partially melt the materials being friction stir welded. This
typically reduces the energy load required to drive the second
friction stir tool 70.
[0028] In FIG. 1J the second friction stir tool 70 is used along
the second seam 66 (identified in FIG. 1G) to form a third bond 84,
as seen in FIG. 1K. As further depicted in FIG. 1J, a source of
pre-heating 82 may be applied to the material adjacent the second
seam 66 (as identified in FIG. 1G). In the embodiment of FIG. 1J a
portion 86 of the first filler 56 remains substantially unaltered
by the friction stir welding process. In alternate embodiments such
as depicted in FIG. 1K a further pass (or passes) of the friction
stir tool 70 may be used to mix the entirety of the first filler 56
with the second bond 80 and the third bond 84 to form a mixed bond
90 as depicted in FIG. 1L. In alternate embodiments the entirety of
the first filler 56 may be mixed with the second bond 80 and the
third bond 84 and with at least portions of the material of the
first portion 10 of the fabrication preform, the second portion 12
of the fabrication preform, and the root pass (the first bond 48)
to form a mixed bond. For maximum strength of a weld is desirable
to mix the materials so that the weld is formed without any voids
or discontinuities.
[0029] As further seen in FIG. 1L, after completion of the friction
stir welding processes of FIG. 1J and 1K, a second filler 94 is
disposed in at least a portion of the second groove 54 (identified
in FIG. 1G) between the first portion 10 of the fabrication preform
and the second portion 12 of the fabrication preform. A third seam
96 is formed between the second filler 94 and the first portion 10
of the fabrication preform, and a fourth seam 98 is formed between
the second filler 94 and the second portion 12 of the fabrication
preform.
[0030] Then as seen in FIG. 1M, two friction stir tools 110 and 112
are used simultaneously along the third seam 96 and the fourth seam
98 respectively. This forms a fourth bond 114 and a fifth bond 116
as seen in FIG. 1N. In the embodiments of FIGS. 1A-1N, a portion
118 of the second filler 94 remains substantially unaltered by the
friction stir welding processes, as depicted in FIG. 1N. As
illustrated in FIG. 10, in some embodiments further friction stir
welding passes represented by stir tools 130, may be made through
the portion 118 to mix substantially all of the second filler 94
with either or both of the fourth bond 114 and the fifth bond 116.
The result may be a partially homogenous surface region 132
depicted in FIG. 1P. Further more, by using a friction stir welding
tool (such as friction stir welding tool 70) that has a longer pin
than the pin of friction stir welding tool 110 or 112, a portion of
the second filler 94 may be mixed with the second bond 80, and/or
with the portion 92 of the first filler 56, and/or with the third
bond 90. Furthermore, as illustrated in FIG. 1Q, by using
combinations of successive passes a substantially homogenously
region 134 may be created to bond the portions of the fabrication
preform together. The completed welds in FIGS. 1N, 1P, and 1Q are
examples of "multiple pass" and "multiple layer" friction stir
welds.
[0031] It is understood that some or all of the steps described in
FIG. 1A-1Q may be repeated multiple times to produce a welded
structure of virtually unlimited thickness.
[0032] FIGS. 2A-2M depict friction stir processes and results
performed on a fabrication "preform" in order to form an enhanced
structure (article of manufacture) and/or to produce enhanced
materials (compositions of material). The enhanced structure or
enhanced material may have enhanced chemical, physical, mechanical
or electrical properties, or combinations thereof For example, an
enhanced structure or enhanced material may have improved catalytic
properties or improved corrosion resistance. An enhanced structure
or enhanced material may have (in at least portions of the enhanced
structure) modified conductive, semi-conductive, or insulative
electrical or thermal properties or different magnetic properties.
An enhanced structure or enhanced material may have improved or
intentionally diminished strength, or may have a modified
coefficient of thermal expansion, or may have a modified melting
temperature.
[0033] FIG. 2A illustrates a fabrication preform 140 that includes
a first piece 142 and a second piece 144. The fabrication preform
140 has a first common surface 146. A gap 148 between the first
piece 142 and the second piece 144 forms a recess below the first
common surface 146 of the fabrication preform 140. FIG. 2B
illustrates a fabrication preform 160 formed from a single piece
162. The fabrication preform 160 has a first common surface 164. A
channel 166 forms a recess below the first common surface 164.
[0034] In FIG. 2C a filler 180 is disposed in at least a portion of
the recess (the gap 148 identified in FIG. 2A) in the fabrication
preform 140 to form a filled preform 182. The filler 180 typically
includes a composition of material that is different from the
composition of material of the first piece 142 of the fabrication
preform 140 and/or that this different from the composition of
material of the second piece 144 of the fabrication preform 140. In
some embodiments, the filler material 180 is a composite material,
such as metal/metal composite, a cermet composite, or a bundle of
wires, layered materials or other forms of mixture of the same or
different materials. The composite filler 180 may be consolidated
or synthesized by the thermal/mechanical deformation and mixing
action of the friction stir process to form an enhanced structure
and/or to produce enhanced or new materials. In other embodiments,
the filler 180 has a composition substantially same as either the
first piece 142 or the second piece of 144. A first seam 184 is
formed between the filler 180 and the recess (the gap 148) in the
fabrication preform 140 and a second seam 186 is formed between the
filler 180 and the recess (the gap 148) in the fabrication preform
140. In FIG. 2D a filler 200 is disposed in at least a portion of
the recess (the channel 166) in the fabrication preform 160 to form
a filled preform 202. A first seam 204 is formed between the filler
200 and the recess (channel 166) in the fabrication preform 160 and
a second seam 206 is formed between the filler 200 and the recess
(channel 166) in the fabrication preform 160.
[0035] FIGS. 2E-2L depict friction stir processes and results
performed on the filled preform 182 depicted in FIG. 2C. Similar
friction stir processes and similar results may be achieved using
the filled preform 202 depicted in FIG. 2D, or other similar filled
preforms.
[0036] FIG. 2E depicts a friction stir tool 220 being used along
the first seam 184 (identified in FIG. 2C) of filled preform 182 to
form a first bond 222, as seen in FIG. 2F. Then in FIG. 2G the
friction stir tool 220 is used along the second seam 186
(identified in FIG. 2C) of filled preform 182 to form a second bond
224, as seen in FIG. 2H.
[0037] In FIG. 2I, a further pass of the friction stir tool 220 is
made between the material of the first piece 142 (identified in
FIG. 2A) and the first bond 222 (identified in FIG. 2F). This
further pass is referred to as stir mixing and it blends the
materials of the first bond 222 and the first piece 142 and forms a
first blended bond 226 as depicted in FIG. 2J. Such blending may be
desirable to form a graded material having more gradual changes in
material composition. Additional mixing may be achieved with
additional passes between the first blended bond 226 and the first
piece 142 to vary the gradient of the material.
[0038] In FIG. 2K, a further stir mixing pass of the friction stir
tool 220 is made between the material of the second piece 144
(identified in FIG. 2A) and the second bond 224 (identified in FIG.
2F). This further stir mixing pass blends the materials of the
second bond 224 and the second piece 144 and forms a second blended
bond 228 as depicted in FIG. 2L. The result of these processes is
an enhanced structure 230 as depicted in FIG. 2L. Additional passes
with the friction stir tool 220 may be made through various
portions of the enhanced structure 230 in order to further bond or
blend the composition of materials.
[0039] In some cases, it may be desirable to process the remaining
material with one or more passes between 226 and 228 to form new
materials (e.g., composite materials) that combine materials from
the first piece 142 and the second piece 144 and the filler 180.
This may produce a substantially uniform block of material such as
substantially homogenous region 240 of FIG. 2M. The properties of
substantially homogenous region 240 are typically different from
the individual properties of the portions of the fabrication
preform and the fillers that were used to produce the substantially
homogenous region 240. The substantially homogenous region 240 may
be sectioned from the finished assembly as a new composition of
material and used to fabricate articles of manufacture. In summary,
the substantially homogenous region 240 may be produced by the
friction stir bonding and/or blending action on a compound of
individual materials, to provide a mechanical synthesis of
materials. Such processes may be useful to produce compositions of
material that are difficult to combine by other means, such as
combinations of copper and steel or copper and aluminum.
[0040] It is understood that the methods described in FIG. 1A-1Q
may be applied in combination with the methods described in FIG.
2A-2M to produce an enhanced structure and/or to produce enhanced
materials of unlimited thickness.
[0041] FIG. 3A depicts a first portion 250 of a preform that has a
first planar surface 252, a second planar surface 254 and a first
edge 256. FIG. 3A further depicts a second portion 258 of the
fabrication preform having a third planar surface 260 and a fourth
planar surface 262 and a second edge 264. In some embodiments the
first portion 250 of the fabrication preform is a first workpiece
and the second portion 258 of the fabrication preform is a second
workpiece that is to be joined with the first workpiece. In other
embodiments the first portion 250 of the fabrication preform and
the second portion 258 of the fabrication preform are portions of
the same workpiece that are to be joined together. The first edge
256 and the second edge 264 form a joint 266 (making a lap joint)
between the first portion 250 of the fabrication preform and the
second portion 258 of the fabrication preform. In the embodiment of
FIG. 3A the joint 266 is a seam between the first portion 250 of
the preform and the second portion 258 of the preform. In alternate
embodiments a joint between the first portion of a preform and the
second portion of a preform may include a filler. The first planar
surface 252 and the third planar surface 260 are substantially
co-planar and form a first common surface 268. The second planar
surface 254 and the fourth planar surface 262 are substantially
co-planar and form a second common surface 270 that is opposed to
the first common surface 268.
[0042] FIG. 3B depicts a first portion 300 of a fabrication preform
that has a first planar surface 302, a second planar surface 304
and a first edge 306. FIG. 3B further depicts a second portion 308
of the fabrication preform having a third planar surface 310 and a
fourth planar surface 312 and a second edge 314. In some
embodiments the first portion 300 of the fabrication preform is a
first workpiece and the second portion 308 of the fabrication
preform is a second workpiece that is to be joined with the first
workpiece. In other embodiments the first portion 300 of the
fabrication preform and the second portion 308 of the fabrication
preform are portions of the same workpiece that are to be joined
together. The first edge 306 and the second edge 314 form a joint
316 (making a bevel joint) between the first portion 300 of the
fabrication preform and the second portion 308 of the fabrication
preform. The first planar surface 302 and the third planar surface
310 are substantially co-planar and form a first common surface
318. The second planar surface 304 and the fourth planar surface
312 are substantially co-planar and form a second common surface
320 that is opposed to the first common surface 318.
[0043] FIG. 3C depicts a first portion 340 of a fabrication preform
that has a first planar surface 342, a second planar surface 344
and a first edge 346. FIG. 3C further depicts a second portion 348
of the fabrication preform having a third planar surface 350 and a
fourth planar surface 352 and a second edge 354. In some
embodiments the first portion 340 of the fabrication preform is a
first workpiece and the second portion 348 of the fabrication
preform is a second workpiece that is to be joined with the first
workpiece. In other embodiments the first portion 340 of the
fabrication preform and the second portion 348 of the fabrication
preform are portions of the same workpiece that are to be joined
together. The first edge 346 and the second edge 354 form a joint
356 (making a butt joint) between the first portion 340 of the
fabrication preform and the second portion 348 of the fabrication
preform. The first planar surface 342 and the third planar surface
350 are substantially co-planar and form a first common surface
358. The second planar surface 344 and the fourth planar surface
352 are substantially co-planar and form a second common surface
360 that is opposed to the first common surface 358.
[0044] In addition to the embodiments depicted in FIGS. 3A-3B other
configurations of joints may be used such as those formed by
tongue-in-groove joints or interlocking joints, and as previously
noted, fillers may be employed.
[0045] FIG. 4 depicts a first friction stir tool 380 being used
along a portion of the joint 316 (identified in FIG. 3B) between
the first portion 300 of the fabrication preform and the second
portion 308 of the fabrication preform. The first friction stir
tool 380 is welding a portion of the joint 316 along a first weld
path 382 that is on the first common surface 318 at or at least
proximal to where the joint 316 intersects the first common surface
318. The first weld path 382 forms a first weld path plane 384 that
is perpendicular to the first common surface 318.
[0046] FIGS. 5A-5C illustrate various embodiments of weld paths and
weld planes. Each FIG. 5A-5C depicts a common surface 400. FIG. 5A
depicts a straight line weld path 402 that is on the common surface
400. FIG. 5B depicts a curved line weld path 404 that is on the
common surface 400. FIG. 5C depicts a jagged weld path 406 that is
on the common surface 400. FIG. 5A depicts a flat weld plane 408
that is perpendicular to the common surface 400. FIG. 5B depicts a
curvilinear weld plane 410 that is perpendicular to the common
surface 400. FIG. 5C depicts a jagged weld plane 712 that is
perpendicular to the common surface 400. Thus it seen from FIGS.
5A-5C, weld paths may, for example, be straight lines, curved lines
or jagged lines, and weld planes may be flat planes, curvilinear
planes, or jagged planes. It should also be noted that in FIGS.
5A-5C the common surface 400 is a flat surface. In other
embodiments the common surface may be a curved surface or a jagged
surface. When the common surface is a curved surface or a jagged
surface the weld plane is typically still perpendicular to the
common surface at each locus of the welding tool along the weld
path.
[0047] Returning to FIG. 4, a second friction stir welding tool 440
is used along a portion of the joint 316. The second friction stir
welding tool 440 is welding a portion of the joint 316 along a
second weld path 442 that is on the second common surface 320 at or
at least proximal to where the joint 316 intersects the second
common surface 320. The second weld path 442 forms a second weld
path plane 444 that is perpendicular to the second common surface
320. In the embodiment of FIG. 4 the first weld path plane and the
second weld path plane are not co-planar. In the embodiment of FIG.
4 the first friction stir welding tool 380 and the second friction
stir welding tool 440 are welding during substantially the same
time interval. In some embodiments the first friction stir welding
tool 380 and the second friction stir welding tool 440 may weld
during different time intervals. In some embodiments the first
friction stir welding tool 380 may be used along the first weld
path 382 and then subsequently the same first friction welding tool
380 may be used to friction stir weld along the second weld path
442. As further depicted in FIG. 4, a source of pre-heating 82 is
applied to the material adjacent the joint 316 (as identified in
FIG. 1G).
[0048] FIG. 6A depicts cross sections of a first portion 510 of a
fabrication preform and a second portion 512 of the fabrication
preform with a transition piece 514 disposed between the first
portion 510 of the fabrication preform and the second portion 512
of the fabrication preform. In some embodiments the first portion
510 of the fabrication preform is a first workpiece and the second
portion 512 of the fabrication preform is a second workpiece that
is to be joined with the first workpiece. In other embodiments the
first portion 510 of the fabrication preform and the second portion
512 of the fabrication preform are portions of the same workpiece
that are to be joined together. The first portion 510 of the
fabrication preform and the second portion 512 of the fabrication
preform may be fabricated from the same material or from different
materials. The transition piece 516 may be fabricated from the same
material as the first portion 510 of the fabrication preform or the
second portion 512 of the fabrication preform or from a different
material than either the first portion 510 of the fabrication
preform or the second portion 512 of the fabrication preform. There
is a first joint 516 between the first portion 510 of the
fabrication preform and the transition piece 514 and a second joint
518 between the transition piece 514 and the second portion 512 of
the fabrication preform. The first portion 510 of the fabrication
preform has a first thickness 520 and the second portion 512 of the
fabrication preform has a second thickness 522 that is different
from the first thickness 520. The transition piece 514 has a first
edge 524 and a second edge 526 opposed to the first edge 524. The
transition piece 514 is configured to vary in thickness from
approximately the first thickness 520 at the first edge 524 of the
transition piece 514 to approximately the second thickness 522 at
the second edge 526 of the transition piece 514. As shown in FIG.
6B three friction stir welding tools 550 may be used to weld at
least portions of the first joint 516 and the second joint 518.
[0049] FIG. 7A depicts cross sections of a first portion 610 of a
fabrication preform and a second portion 612 of the fabrication
preform with a transition piece 614 disposed between the first
portion 610 of the fabrication preform and the second portion 612
of the fabrication preform. In some embodiments the first portion
610 of the fabrication preform is a first workpiece and the second
portion 612 of the fabrication preform is a second workpiece that
is to be joined with the first workpiece. In other embodiments the
first portion 610 of the fabrication preform and the second portion
612 of the fabrication preform are portions of the same workpiece
that are to be joined together. The first portion 610 of the
fabrication preform and the second portion 612 of the fabrication
preform may be fabricated from the same material or from different
materials. The transition piece 614 may be fabricated from the same
material as the first portion 610 of the fabrication preform or the
second portion 612 of the fabrication preform or from a different
material than either the first portion 610 of the fabrication
preform or the second portion 612 of the fabrication preform.
[0050] There is a first joint 616 between the first portion 610 of
the fabrication preform and the transition piece 614 and a second
joint 618 between the transition piece 614 and the second portion
612 of the fabrication preform. The first portion 610 of the
fabrication preform has a first thickness 620 and the second
portion 612 of the fabrication preform has a second thickness 622
that is different from the first thickness 620. The transition
piece 614 has a first edge 624 and a second edge 626 opposed to the
first edge 624. The transition piece 614 is configured to vary in
thickness from approximately the first thickness 620 at the first
edge 624 of the transition piece 614 to approximately the second
thickness 622 at the second edge 626 of the transition piece 614.
As shown in FIG. 7B a first friction stir welding tool 650 may be
used to weld at least a portion of the first joint 616 and a second
friction stir welding tool 652 may be used to weld at least a
portion of the second joint 618.
[0051] FIG. 6C illustrates the cross-section of a completed
assembly 710 made by the process illustrated in FIG. 6B. The
completed assembly 710 includes friction stir welds 712, 714 and
716. In the embodiment of FIG. 6C a portion 720 of the second joint
518 between the transition piece 514 and the second portion 512 of
the fabrication preform (identified in FIG. 6A) is not welded. In
other embodiments the portion 720 may be welded if, for example,
friction stir weld tools are used that have a longer pin than the
pin depicted for friction stir weld tools 550 in FIG. 6B. FIG. 7C
illustrates the cross-section of a completed assembly 750 made by
the process illustrated in FIG. 7B. The completed assembly 750
includes friction stir welds 752 and 754. The friction stir welds
712, 714, 716, 752 and 754 may be stir mixed with materials from
the adjoining portions of the fabrication preform and transition
pieces to form mixed bonds that may provide a more gradual gradient
of material property changes across the completed assemblies.
[0052] It is understood that the methods described in FIG. 1A-1Q
may be applied in combination with the methods described in FIG.
6A-7C to produce welds of unlimited thickness.
[0053] It should be noted that in most embodiments no flux is used
with friction stir welding processes. Generally a protective
atmosphere is not used, although a protective atmosphere such as
argon or nitrogen may be used to prevent oxidation of the welded
materials. Generally the temperatures of the pieces, portions of a
fabrication preform, transition pieces, and fillers individually or
collectively are maintained at a temperature that is less than
their respective melting temperature.
Example
[0054] A proof-of-concept test was conducted to demonstrate the
feasibility of certain processes described herein using two
aluminum alloy portions of a fabrication preform configured like
those depicted in FIG. 1A. FIG. 8 illustrates the portions of the
fabrication preform after being joined by a first (root) friction
stir welding pass. FIG. 9 illustrates the portions of the
fabrication preform after four further friction stir welding
passes. FIG. 10A is a cross-sectional photo of the two portions of
the fabrication preform showing the root pass 760 and a cover pass
762. As used herein, the term "cover pass" refers to a welding pass
that is made at least in part over a root pass or over a previous
cover pass. FIG. 10B shows a subsequent cover pass 764. FIG. 10C
shows the cross section of the completed joint.
[0055] In summary, embodiments disclosed herein provide processes
for joining a first portion of a fabrication preform and a second
portion of the fabrication preform where the portions of a
fabrication preform have abutted edges that form a first seam and
wherein a groove is disposed adjacent at least a portion of the
first seam. Also disclosed are embodiments of methods for forming
an enhanced structure/material from a fabrication preform that has
a first common surface and a recess below the first common surface.
Further disclosed are methods of joining a first portion of a
fabrication preform and a second portion of the fabrication preform
where the first portion of the fabrication preform has a first
planar surface, an opposing second planar surface, and a first edge
and the second portion of the fabrication preform has a third
planar surface and an opposing fourth planar surface and a second
edge, and the first edge and the second edge form a seam between
the first portion of the fabrication preform and the second portion
of the fabrication preform and the first planar surface and the
third planar surface are substantially co-planar and form a first
common surface and the second planar surface and the fourth planar
surface are substantially co-planar and form a second common
surface. Also disclosed herein are articles of manufacture made by
these processes.
[0056] The foregoing descriptions of embodiments have been
presented for purposes of illustration and exposition. They are not
intended to be exhaustive or to limit the embodiments to the
precise forms disclosed. Obvious modifications or variations are
possible in light of the above teachings. The embodiments are
chosen and described in an effort to provide the best illustrations
of principles and practical applications, and to thereby enable one
of ordinary skill in the art to utilize the various embodiments as
described and with various modifications as are suited to the
particular use contemplated. All such modifications and variations
are within the scope of the appended claims when interpreted in
accordance with the breadth to which they are fairly, legally, and
equitably entitled.
* * * * *