U.S. patent application number 16/905223 was filed with the patent office on 2020-12-31 for powder metallurgical processing of high-manganese steels into parts.
The applicant listed for this patent is ExxonMobil Upstream Research Company. Invention is credited to Jamey A. Fenske, Howie W. Jin, Clifford Andrew Prescott, Neerav Verma, Andrew J. Wasson.
Application Number | 20200406360 16/905223 |
Document ID | / |
Family ID | 1000004916634 |
Filed Date | 2020-12-31 |
United States Patent
Application |
20200406360 |
Kind Code |
A1 |
Prescott; Clifford Andrew ;
et al. |
December 31, 2020 |
POWDER METALLURGICAL PROCESSING OF HIGH-MANGANESE STEELS INTO
PARTS
Abstract
Although high-manganese steels may have desirable mechanical
strength and corrosion resistance, machining and casting can be
difficult. Alternatively, high-manganese steel parts may be
fabricated to near-net shape parts using powder metallurgical
processing, such as hot pressing and powder injection molding,
thereby significantly minimizing or eliminating the need for
further machining of fabricated parts. Hot pressing processes may
comprise: loading a container with a plurality of particulates
comprising a high-manganese steel; establishing a reduced pressure
state in the container after loading the container with the
plurality of particulates, and sealing the container to maintain
the reduced pressure state therein and to afford a sealed
container; placing the sealed container in a pressure vessel;
heating the pressure vessel at a predetermined temperature while
applying a predetermined pressure isostatically to an exterior
surface of the sealed container with a pressurizing gas to
consolidate the plurality of particulates into a densified part
having a near-net shape; and removing the sealed container to
expose a surface of the densified part.
Inventors: |
Prescott; Clifford Andrew;
(The Woodlands, TX) ; Wasson; Andrew J.; (Spring,
TX) ; Fenske; Jamey A.; (Spring, TX) ; Verma;
Neerav; (Deer Park, TX) ; Jin; Howie W.;
(Easton, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Upstream Research Company |
Spring |
TX |
US |
|
|
Family ID: |
1000004916634 |
Appl. No.: |
16/905223 |
Filed: |
June 18, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62866672 |
Jun 26, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 3/15 20130101; C22C
38/002 20130101; C22C 38/02 20130101; B22F 3/225 20130101; B22F
5/106 20130101; C22C 38/44 20130101; B22F 2301/35 20130101; C22C
38/58 20130101 |
International
Class: |
B22F 3/15 20060101
B22F003/15; B22F 3/22 20060101 B22F003/22; B22F 5/10 20060101
B22F005/10; C22C 38/58 20060101 C22C038/58; C22C 38/44 20060101
C22C038/44; C22C 38/02 20060101 C22C038/02; C22C 38/00 20060101
C22C038/00 |
Claims
1. A process comprising: providing a plurality of particulates
comprising a high-manganese steel; loading a container with the
plurality of particulates, the container having an internal surface
formed in a near-net shape of a part; establishing a reduced
pressure state in the container after loading the container with
the plurality of particulates, and sealing the container to
maintain the reduced pressure state therein, thereby affording a
sealed container; placing the sealed container in a pressure
vessel; heating the pressure vessel at a predetermined temperature
while applying a predetermined pressure isostatically to an
exterior surface of the sealed container with a pressurizing gas;
wherein the predetermined temperature and the predetermined
pressure in combination are sufficient to consolidate the plurality
of particulates to form a densified part having the near-net shape;
and removing the sealed container to expose a surface of the
densified part.
2. The process of claim 1, wherein removing the sealed container
comprises a pickling treatment that dissolves the container.
3. The process of claim 1, wherein removing the sealed container
comprises a machining operation that disassembles the
container.
4. The process of claim 1, wherein sealing the container comprises
a seal welding operation.
5. The process of claim 1, wherein the densified part is a pipeline
connector.
6. The process of claim 5, wherein the densified part is a weld
neck pipe flange.
7. The process of claim 5, wherein the densified part is a flanged
pipe elbow or a flanged pipe T.
8. The process of claim 1, wherein the predetermined temperature
does not lead to formation of a liquid phase in the container.
9. The process of claim 1, further comprising: providing a second
plurality of particulates comprising a second high-manganese steel
with a different composition from the high-manganese steel or a
steel composition that is not a high-manganese steel; wherein the
loading the container with the plurality of particulates comprises
disposing the plurality of particulates of the high-manganese steel
in a first location of the container and disposing plurality of
particulates of the second high-manganese steel or the steel
composition that is not a high-manganese steel in a second location
of the container.
10. The process of claim 9, wherein the second location of the
container is in a location of the container that forms the internal
surface of the near-net shape part.
11. A process comprising: providing a plurality of particulates
comprising a high-manganese steel; introducing the plurality of
particulates and a binder material into a mold having an internal
surface formed in a near-net shape of a part; setting the binder
material to form a first intermediate part in which the plurality
of particulates remain in a substantially unconsolidated state;
removing the first intermediate part from the mold; heating the
first intermediate part at a first temperature sufficient to remove
the binder material while leaving the plurality of particulates in
the substantially unconsolidated state, thereby forming a second
intermediate part; and heating the second intermediate part at a
second temperature sufficient to consolidate the plurality of
particulates together to form a densified part.
12. The process of claim 11, wherein the binder material comprises
a polymer or a wax.
13. The process of claim 11, wherein introducing the plurality of
particulates and the binder material into the mold takes place by
injection molding.
14. The process of claim 11, wherein the plurality of particulates
and the binder material are premixed before being introduced to the
mold.
15. The process of claim 11, wherein the plurality of particulates
and the binder material are separately introduced into the
mold.
16. The process of claim 15, wherein the plurality of particulates
and the binder material are disposed heterogeneously in the first
intermediate part.
17. The process of claim 11, wherein the densified part is a
pipeline connector.
18. The process of claim 17, wherein the densified part is a weld
neck pipe flange.
19. The process of claim 17, wherein the densified part is a
flanged pipe elbow or a flanged pipe T.
20. The process of claim 11, wherein the second temperature does
not lead to formation of a liquid phase in the container.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application 62/866,672 filed Jun. 26, 2019 entitled POWDER
METALLURGICAL PROCESSING OF HIGH-MANGANESE STEELS INTO PARTS, the
entirety of which is incorporated by reference herein.
FIELD
[0002] The present disclosure relates to powder metallurgical
processing of high-manganese steels into parts having a desired
near-net shape.
BACKGROUND
[0003] High-manganese steels exhibiting excellent mechanical
properties in combination with good erosion and corrosion
resistance have been developed for applications in various
industries. As used herein, the term "high-manganese steel" refers
to an alloy composition comprising at least iron, carbon and
manganese, with iron being the predominant component and at least
about 9 wt. % manganese being present. Additional alloying elements
may be optionally present in high-manganese steels to tailor
further the mechanical and/or chemical properties featured by the
alloy composition.
[0004] While high-manganese steels may exhibit a desirable
combination of mechanical properties and corrosion and erosion
resistance, such steels tend to have relatively poor formability
and are difficult to machine, each as compared to typical standard
carbon steel grades. Work hardening may be particularly responsible
for the difficulty in machining Difficulty in machining
high-manganese steels may limit the range of parts having various
shapes that may be fabricated effectively therefrom. Likewise,
casting techniques for high-manganese steels may result in
components (parts) having low integrity with an inconsistent or
undesired microstructure. As such, the range of shapes for parts
that may be fabricated from high-manganese steels remains fairly
limited at present.
[0005] Currently, high-manganese steels may be readily fabricated
into pipeline sections. Despite having good erosion resistance,
pipeline sections comprising a high-manganese steel may still be
subject to internal erosion when passing particulate-laden fluids
there through, such as may occur in oil-sand hydrotransporting
lines. Due to gravity settling of sand and larger particulates
during fluid transport, the majority of the erosion tends to occur
along the bottom of the pipeline. To increase the lifetime of
individual pipeline sections, the pipeline sections are rotated
approximately 90 degrees on a set maintenance schedule, such that a
non-eroded internal pipeline surface is positioned at the bottom of
a given pipeline section once the pipeline is placed back into
service. Once a given pipeline section has been rotated three
times, it is typically replaced rather than being rotated again,
since all of the internal pipeline surfaces will have experienced
potentially eroding conditions after that time.
[0006] When high-manganese steels are used to form a pipeline,
connecting adjacent pipeline sections together may be problematic
in view of the common practice of rotating the individual pipeline
sections on a set maintenance schedule. If adjacent pipeline
sections are welded together, the weld needs to be broken and
subsequently reformed so that the pipeline sections may be rotated.
This approach can be very labor intensive and expensive. Another
option for joining adjacent pipeline sections together is to employ
a flange, such as a weld neck flange. However, the difficulty of
machining high-manganese steels into parts having even modestly
complex shapes may preclude forming a flange from the same type of
steel forming the pipeline section. As an example of present
solutions available to address this issue, a readily machined steel
composition (e.g., a carbon steel) may need to be used for
fabrication of pipeline connectors such as flanges, elbows,
T-joints and the like to be used in combination with pipeline
sections comprising a high-manganese steel. As such, the pipeline
connectors may undergo wear at a different rate than do the
pipeline sections comprising the high-manganese steel, and the
pipeline sections and the pipeline connectors may be subject to
differing maintenance schedules as a result. The differing
maintenance schedules can be challenging to manage and may result
in further pipeline downtime and increased operational costs.
SUMMARY
[0007] In some embodiments, the present disclosure provides hot
pressing processes comprising: providing a plurality of
particulates comprising a high-manganese steel; loading a container
with the plurality of particulates, the container having an
internal surface formed in a near-net shape of a part; establishing
a reduced pressure state in the container after loading the
container with the plurality of particulates, and sealing the
container to maintain the reduced pressure state therein, thereby
affording a sealed container; placing the sealed container in a
pressure vessel; heating the pressure vessel at a predetermined
temperature while applying a predetermined pressure isostatically
to an exterior surface of the sealed container with a pressurizing
gas; wherein the predetermined temperature and the predetermined
pressure in combination are sufficient to consolidate the plurality
of particulates to form a densified part having the near-net shape;
and removing the sealed container to expose a surface of the
densified part.
[0008] In other embodiments, the present disclosure provides powder
consolidation processes comprising: providing a plurality of
particulates comprising a high-manganese steel; introducing the
plurality of particulates and a binder material into a mold having
an internal surface formed in a near-net shape of a part; setting
the binder material to form a first intermediate part in which the
plurality of particulates remain in a substantially unconsolidated
state; removing the first intermediate part from the mold; heating
the first intermediate part at a first temperature sufficient to
remove the binder material while leaving the plurality of
particulates in the substantially unconsolidated state, thereby
forming a second intermediate part; and heating the second
intermediate part at a second temperature sufficient to consolidate
the plurality of particulates together to form a densified
part.
DETAILED DESCRIPTION
[0009] The present disclosure generally relates to powder
metallurgical processes for manipulating high-manganese steels into
parts having a desired near-net shape and, more specifically, hot
pressing and powder injection molding techniques for processing
high-manganese steels.
[0010] As discussed above, high-manganese steels may be used in
various applications in which good mechanical strength and
corrosion and erosion resistance are desirable. Although pipeline
sections (line pipe) may be satisfactorily fabricated from
high-manganese steels, parts having more complex shapes are often
not able to be produced by machining Without being bound by any
theory or mechanism, the difficulty in machining even modestly
complex parts from high-manganese steels is believed to arise from
work hardening. Casting of high-manganese steels is not yet a
well-developed technology and may lead to production of parts
having an inconsistent, unpredictable and/or undesired
microstructure. The difficulty in casting or machining
high-manganese steels into parts having even modestly complex
shapes significantly limits the range of applications in which
these types of steel may be most effectively used. As a
non-limiting example, it is presently not believed to be feasible
to join together pipeline sections formed from a high-manganese
steel using pipeline connectors also formed from a high-manganese
steel. As such, the maintenance schedule for the various components
of the pipeline may be rather complicated and difficult to manage,
thereby leading to increased downtime and operational costs.
[0011] The present disclosure provides alternative approaches for
manipulating high-manganese steels into parts having a desired
shape. In particular, the present disclosure provides powder
metallurgical processing techniques for high-manganese steels, such
as hot isostatic pressing and powder injection molding techniques,
which may afford parts with a desired near-net shape suitable for
deployment in various types of applications. In these techniques,
powder particulates comprising a high-manganese steel may undergo
consolidation into fully densified or near-fully densified parts
having a consistent, isotropic microstructure. As a non-limiting
example, the present disclosure advantageously allows pipeline
connectors, such as weld neck pipe flanges, flanged pipe elbows,
and flanged pipe T joints, to be fabricated from high-manganese
steels, thereby letting pipeline connectors and pipeline sections
to each be formed from a high-manganese steel of identical or
similar composition for use in combination with one another.
Pipeline connectors formed from a high-manganese steel may provide
appreciable economic, operational and maintenance benefits compared
to those obtained when significantly different steel compositions
are present in a pipeline.
[0012] Although hot isostatic pressing and powder injection molding
are known techniques for manipulating various types of steel
compositions, these techniques are not believed to have been
employed previously for processing high-manganese steels. Moreover,
hot isostatic pressing and powder injection molding techniques are
typically reserved for fabrication of parts having exceedingly
complex shapes, unlike parts formed according to the disclosure
herein. In particular, pipeline couplings are not exceedingly
complex in shape and would ordinarily not be manufactured by a
technique such as hot isostatic pressing or powder injection
molding, especially when using readily machined or castable steel
compositions. In the present case, the difficulty of shaping
high-manganese steels by machining makes the foregoing techniques
well-suited for fabricating even parts having relatively simple
shapes, since they cannot be easily fabricated otherwise. Although
it can be particularly advantageous to fabricate pipeline couplings
according to the disclosure herein, it is to be appreciated that
hot isostatic pressing and powder injection molding techniques may
afford similar advantages when used to produce other types of parts
formed from high-manganese steels as well.
[0013] Before describing the embodiments of the present disclosure
in further detail, a listing of terms follows to aid in better
understanding the present disclosure.
[0014] All numerical values within the detailed description and the
claims herein are modified by "about" or "approximately" with
respect to the indicated value, and take into account experimental
error and variations that would be expected by a person having
ordinary skill in the art. Unless otherwise indicated, room
temperature is about 25.degree. C.
[0015] As used in the present disclosure and claims, the singular
forms "a," "an," and "the" include plural forms unless the context
clearly dictates otherwise.
[0016] The term "and/or" as used in a phrase such as "A and/or B"
herein is intended to include "A and B," "A or B," "A", and
"B."
[0017] For the purposes of the present disclosure, the new
numbering scheme for groups of the Periodic Table is used. In said
numbering scheme, the groups (columns) are numbered sequentially
from left to right from 1 through 18, excluding the f-block
elements (lanthanides and actinides).
[0018] The terms "austenite" and "austenitic" refer to a steel
metallurgical phase having a face-centered cubic (FCC) atomic
crystalline structure.
[0019] The terms "martensite" and "martensitic" refer to a steel
metallurgical phase that may be formed by diffusionless phase
transformation, in which a parent steel (typically austenite) and
one or more product phases have a specific orientation
relationship.
[0020] The term "near-net shape" refers to fabrication of a part in
an initial shape that is very close to the final part shape, such
that no or minimal machining or surface finishing is needed.
Additionally, no or minimal mechanical or metallurgical
post-processing steps are needed when obtaining a finalized
part.
[0021] The term "reduced pressure state" refers to a pressure below
atmospheric pressure.
[0022] The term "consolidate" refers to the act of adjoining a
plurality of discrete particulates into a continuous body having
metallurgical bonds between particulates, thereby resulting in a
fully integral part.
[0023] The terms "densify" and "densification" refer to the removal
of at least a portion of voids between a plurality of discrete
particulates upon undergoing consolidation to form a continuous
body having metallurgical bonds between particulates.
[0024] The present disclosure provides techniques for processing
powder particulates comprising a high-manganese steel into parts
having a desired shape. Illustrative processing techniques that may
be suitable for use in the disclosure herein include hot pressing
(e.g., hot isostatic pressing) and powder injection molding, each
of which is described in more detail herein below. Both techniques
may afford a desired part in a near-net shape, which may undergo
further particulate consolidation thereafter to provide a fully or
near-fully densified part. Parts fabricated according to the
disclosure herein may exhibit isotropic properties once formed.
[0025] High-manganese steels suitable for use in the disclosure
herein have an austenitic microstructure but are otherwise not
considered to be particularly limited in composition, provided that
powder particulates can be acceptably thrilled from the
high-manganese steel and the high-manganese steel has sufficient
erosion and corrosion resistance. At a minimum, suitable
high-manganese steels comprise iron, carbon and at least about 9
wt. % manganese, along with additional optional alloying elements
that may be further present to tailor the properties of the
high-manganese steels. Compositional details of illustrative
high-manganese steels suitable for use in the disclosure herein are
provided herein below.
[0026] Iron is the majority element in the high-manganese steels
utilized herein. Iron and unavoidable impurities introduced during
steel manufacturing account for the balance of elements present in
the high-manganese steels once carbon, manganese and additional
alloying elements are accounted for.
[0027] Typically, sufficient carbon is present in the
high-manganese steels discussed herein to aid in stabilizing the
austenite phase. Additionally, carbon may serve to strengthen the
high-manganese steels through solid solution strengthening, such as
through formation of one or more carbides. Excessive carbide
formation may reduce toughness, however. For the foregoing reasons,
the carbon content in the high-manganese steels may range from
about 0.4-0.8 wt. % C, or from about 0.5-0.7 wt. % C, or from about
0.55-0.65 wt. % C.
[0028] Manganese is the primary alloying element in high-manganese
steels discussed herein. As such, manganese is the second-most
prevalent element after iron in the steel compositions. Manganese
may particularly aid in stabilizing the austenite phase during
cooling and deformation of the steel during processing.
Additionally, the amount of manganese may determine how the steels
respond or transform when strained. At manganese contents greater
than about 25 wt. %, the austenite phase may deform via dislocation
slip when it is mechanically strained. At manganese contents
ranging from about 15 wt. % to about 25 wt. %, the austenite phase
is mildly metastable and may undergo twinning during deformation to
result in a high degree of work hardening, very high tensile
strength and uniform elongation. At manganese contents less than
about 15 wt. %, transformation of the austenite phase into an
-martensite and/or .alpha.'-martensite phase may occur upon
mechanical straining. For the foregoing reasons, the manganese
content in the high-manganese steels may range from about 9-25 wt.
% Mn, or about 12-25 wt. % Mn, or about 12-18 wt. % Mn, or about
14-19 wt. % Mn, or about 16-20 wt. % Mn. Manganese contents up to
about 30 wt. % or as low as 8 wt. % Mn may also be tolerated in
high-manganese steels suitable for use in the present
disclosure.
[0029] Chromium may be present in the high-manganese steels
discussed herein as an optional alloying element due to the ability
of this element to facilitate corrosion resistance. The chromium
content may be limited based upon one or more of the following
considerations: (1) limiting steel costs by avoiding Cr levels that
are too high, (2) limiting austenite phase destabilization by Cr
levels that are too high, and (3) limiting carbide precipitation
for Cr levels that are too high. Typically, the amount of chromium
is chosen to convey acceptable corrosion resistance to the
high-manganese steels without promoting excessive austenite phase
destabilization and/or carbide precipitation. For the foregoing
reasons, the chromium content in the high-manganese steels may
range from about 4-15 wt. % Cr, or from about 5-10 wt. % Cr, or
from about 10-15 wt. % Cr.
[0030] Silicon may play one or more of the following roles when
included as an optional alloying element: serving as a ferrite
stabilizer, promoting -martensite formation during ambient
temperature deformation, and strengthening the austenite phase
through solid solution strengthening. The silicon content may be
limited to promote sufficient strengthening without inducing
excessive ferrite stabilization. For the foregoing reasons, the
silicon content in the high-manganese steels may range up to about
3 wt. % Si or up to 1 wt. % Si, including from about 0.01 wt. % Si
to about 3 wt. % Si, or from about 0.01 wt. % Si to about 1 wt. %
Si, or from about 0.01 wt. % Si to about 0.2 wt. % Si.
[0031] Aluminum may serve a ferrite stabilizer when included as an
optional alloying element. Significant amounts of aluminum may
destabilize the austenite phase during cooling, while lower amounts
of aluminum may stabilize the austenite phase to some degree.
Stabilization may include action against strain-induced phase
transformation during deformation and providing solid solution
strengthening. For the foregoing reasons, the aluminum content in
the high-manganese steels may range up to about 0.5 wt. % Al or up
to about 0.1 wt. % Al, including about 0.001 wt. % Al to about 0.5
wt. % Al, or about 0.001 wt. % Al to about 0.1 wt. % Al, or about
0.001 wt. % Al to about 0.08 wt. % Al.
[0032] When included as an optional alloying element, molybdenum
may serve as a solid solution strengthener of the austenite phase
and may be utilized in small quantities to increase strength. For
the foregoing reasons, the molybdenum content in the high-manganese
steels may range up to about 5 wt. %, or up to about 1 wt. %, or up
to about 0.5 wt. %, or up to about 0.1 wt. %, including from about
0.001 wt. % Mo to about 1 wt. % Mo, or from about 0.001 wt. % Mo to
about 0.5 wt. % Mo, or from about 0.001 wt. % Mo to about 0.1 wt. %
Mo.
[0033] When included as an optional alloying element, nitrogen is
an effective solid solution strengthener and a precipitate
(nitride) former. In Cr- and Mn-alloyed austenitic steels, the
nitrogen solubility limit is typically determined by the
equilibrium between the matrix and chromium nitride (e.g.,
Cr.sub.2N). If the nitrogen content is too high, hot workability
(required for manufacturing) may be negatively impacted. For the
foregoing reasons, the nitrogen content in the high-manganese
steels may range up to about 0.1 wt. % N, or up to about 0.05 wt. %
N, or up to about 0.01 wt. % N, or up to 0.008 wt. % N, including
about 0.001 wt. % N to about 0.1 wt. % N, or from about 0.001 wt. %
N to about 0.05 wt. % N, or from about 0.001 wt. % N to about 0.01
wt. % N, or from about 0.001 wt. % N to about 0.008 wt. % N.
[0034] Other alloying elements suitable for inclusion in
high-manganese steels may include, but are not limited to, nickel,
tungsten, copper, niobium, vanadium, titanium, sulfur, phosphorus,
boron, and any combination thereof.
[0035] In any embodiment, suitable high-manganese steels for use in
the disclosure herein may comprise: 0.4-0.8 wt. % C, 12-25 wt. %
Mn, 4-15 wt. % Cr, a non-zero amount of Si less than 3 wt. % Si, a
non-zero amount of Al less than 0.5 wt. % Al, less than 5 wt. % Mo,
a non-zero amount of N less than 0.1 wt. % N, and balance Fe and
inevitable impurities. The term "a non-zero amount" refers to a
concentration above that of a manufacturing impurity (inevitable
impurities) for a particular component in the high-manganese steels
discussed herein.
[0036] In any embodiment, suitable high-manganese steels for use in
the disclosure herein may comprise: 0.1-0.4 wt. % C, 15-25 wt. %
Mn, 2.0-8.0 wt. % Cr, less than 2.0 wt. % Mo, less than 10 wt. %
Ni, less than 0.7 wt. % Si, less than 100 ppm S, less than 200 ppm
P, and balance Fe and inevitable impurities. Such high-manganese
steels are described in U.S. Patent Application Publication
20170312862, which is incorporated herein by reference in its
entirety.
[0037] In any embodiment, suitable high-manganese steels for use in
the disclosure herein may comprise: 0.4-0.8 wt. % C, 18-24 wt. %
Mn, less than 6 wt. % Cr, less than 4 wt. % Mo, less than 5 wt. %
Ni, 0.4-1.0 wt. % Si, less than 200 ppm S, less than 200 ppm P, and
balance Fe and inevitable impurities. Such high-manganese steels
are described in U.S. Patent Application Publication 20180021895,
which is incorporated herein by reference in its entirety.
[0038] In any embodiment, suitable high-manganese steels for use in
the disclosure herein may comprise: 0.3-1.2 wt. % C, 9-30 wt. % Mn,
less than 8 wt. % Cr, less than 6 wt. % Mo, less than 6 wt. % Ni,
less than 5 wt. % W, less than 4 wt. % Cu, less than 2 wt. % Nb,
less than 2. wt. V, less than 2 wt. % Ti, less than 0.4 wt. % N,
less than 1 wt. % B. 0.1-3.0 wt. Si, and at least one of less than
0.3 wt. % S, less than 0.03 wt. % P, and any combination thereof,
and balance Fe and inevitable impurities. Such high-manganese
steels are described in U.S. Patent Application Publication
20170312861.
[0039] In any embodiment, suitable high-manganese steels for use in
the disclosure herein may comprise: 0.1-1.5 wt. % C, 8-30 wt. % Mn,
11-30 wt. % Cr, and one or more alloying elements selected from Al,
Si, Ni, Co, Mo, Nb, Cu, Ti, V, W, N, B, Zr, Hf, and any combination
thereof, and balance Fe and inevitable impurities. Such
high-manganese steels are described in U.S. Patent Application
Publication 20170088910, which is incorporated herein by reference
in its entirety.
[0040] In any embodiment, suitable high-manganese steels for use in
the disclosure herein may comprise: 0.34.2 wt. % C, 9-25 wt. % Mn,
0.5-30 wt. % Cr, and one or more alloying elements selected from
Al, Si, Ni, Co, Mo, Nb, Cu, Ti, V, W, N, B, Zr, Hf, and any
combination thereof, and balance Fe and inevitable impurities. Such
high-manganese steels are described in U.S. Patent Application
Publication 20170349983, which is incorporated herein by reference
in its entirety.
[0041] Methods of the present disclosure may comprise forming a
plurality of particulates comprising a chosen high-manganese steel.
Suitable techniques for forming particulates of a high-manganese
steel may include, for example, gas atomization, details of which
will be apparent to one having ordinary skill in the art. in brief,
suitable gas atomization techniques may include passing a molten
high-manganese steel composition through a nozzle into a jet of
inert gas such as nitrogen or argon. Upon contacting the jet of
inert gas, atomized droplets of molten high-manganese steel may
form, which may subsequently harden into discrete particulates upon
cooling. Particulates formed by such techniques may be utilized in
either hot pressing or powder injection molding processes described
herein.
[0042] High-manganese steels may be processed into parts having a
desired near-net shape by hot pressing techniques, such as hot
isostatic pressing. More particularly, such techniques for
processing high-manganese steels into a part may comprise:
providing a plurality of particulates comprising a high-manganese
steel; loading a container with the plurality of particulates, in
which the container has an internal surface formed in a near-net
shape of a part; establishing a reduced pressure state in the
container after loading the container with the plurality of
particulates, and sealing the container to maintain the reduced
pressure state therein, thereby affording a sealed container;
placing the sealed container in a pressure vessel; heating the
pressure vessel at a predetermined temperature while applying a
predetermined pressure isostatically to an exterior surface of the
sealed container with a pressurizing gas, such that the
predetermined temperature and the predetermined pressure in
combination are sufficient to consolidate the plurality of
particulates to form a densified part having the near-net shape;
and removing the sealed container to expose a surface of the
densified part.
[0043] Materials for forming containers suitable for use in
conjunction with the hot pressing techniques disclosed herein may
include, for example, any steel composition that is formable and
capable of maintaining a vacuum environment. Various carbon steels
may be suitable for use in forming the container. The term "can"
may be used to describe the "container" housing the plurality of
particulates in the hot pressing processes disclosed herein.
[0044] Suitable techniques for loading the container with the
plurality of particulates are not considered to be particularly
limited. Both manual and automated loading approaches are suitable
for use in the disclosure herein. In some embodiments, the
container may be vibrationally agitated following particulate
loading to promote settling of the particulates and to afford more
complete filling of the internal space within the container prior
to particulate consolidation.
[0045] After loading the container with the plurality of
particulates, the container may be evacuated by pulling a vacuum
thereon and then sealing the container to maintain a reduced
pressure state therein. Sealing the container may comprise a seal
welding operation, in particular embodiments of the present
disclosure. Depending on the material comprising the container,
other types of sealing operations may be appropriate as well. Once
sealing has taken place, the pressure within the container may
range from vacuum pressures up to less than one atmosphere of
pressure. Suitable pressure conditions will be familiar to one
having ordinary skill in the art.
[0046] After sealing the container under a reduced pressure state,
the sealed container may then be placed in a pressure vessel (i.e.,
a pressurizable vessel) capable of being heated to promote
consolidation of the particulates without formation of an
intermediate liquid phase in the container. The combination of
heating at the predetermined temperature and pressurizing at the
predetermined pressure is chosen to be effective for consolidating
the plurality of particulates into a densified part. In particular
embodiments, suitable pressures applied by the pressurizing gas in
the pressure vessel may range from about 8 ksi to about 20 ksi.
Similarly, suitable temperatures for promoting consolidation of the
particulates comprising the high-manganese steel may range from
about 700.degree. C. to about 2,000.degree. C.
[0047] The pressure within the pressure vessel is applied with a
pressurizing gas. The pressurizing gas may comprise an inert gas
such as nitrogen or argon, according to particular embodiments of
the present disclosure. The pressure applied to the sealed
container with the pressurizing gas may be isostatic in character,
such that the pressure is applied at substantially the same
magnitude in all directions upon the container. It is to be
appreciated that the magnitude of the applied pressure may vary at
different times throughout the hot isostatic pressing process,
provided that the pressure remains isostatically applied.
[0048] After particulate consolidation has taken place, processes
of the present disclosure may comprise removing the sealed
container from the densified part to expose a surface of the
densified part. Suitable removal techniques may be dictated by the
material comprising the container. Illustrative removal techniques
may include, for example, chemical removal or mechanical removal.
Mechanical removal may be suitable when the sealed container is not
metallurgically bonded to the densified part therein. Mechanical
removal may comprise a machining operation, for example, that at
least partially disassembles the sealed container to promote its
separation from the densified part. Mechanical removal need not
necessarily destroy the container in all cases, since slip off
separation of the container from the densified part may leave at
least a portion of the container suitably intact for reuse in
forming additional parts in some instances. Chemical removal may be
suitable when the sealed container is metallurgically bonded to an
exterior surface of the densified part. Chemical removal of the
container may utilize a chemical reaction to promote dissolution or
disintegration of the sealed container to promote its separation
from the densified part, thereby exposing a surface of the
densified part underneath the container.
[0049] In particular embodiments, suitable chemical treatments to
promote chemical removal of the sealed container may comprise a
pickling treatment that dissolves the sealed container or a portion
thereof. Pickling treatments for steel compositions will be
familiar to one having ordinary skill in the art. In general, when
a pickling treatment is to be used for promoting container removal,
a proper dwell time may be selected to limit loss of the
high-manganese steel once the container has been substantially
removed. The container may be fabricated from a carbon steel in any
embodiment of the present disclosure.
[0050] Grain sizes obtainable in the hot pressing processes of the
present disclosure may be fine and equiaxed, which may aid in
promoting consistent, isotropic mechanical properties within the
part. In contrast, forged or cast components formed from the same
high-manganese steel may possess directional properties, either
longitudinal or transverse, depending on the particular
manufacturing parameters used.
[0051] Processing particulates comprising a high-manganese steel
into a densified part may also take place by alternative techniques
to promote particulate consolidation. In particular embodiments,
powder injection molding processes may be used to promote
fabrication of densified parts comprising a high-manganese
steel.
[0052] Powder injection molding processes of the present disclosure
may comprise: providing a plurality of particulates comprising a
high-manganese steel; introducing the plurality of particulates and
a binder material into a mold having an internal surface forming in
a near-net shape of a part; setting the binder material to form a
first intermediate part within the mold, in which the plurality of
particulates remain in a substantially unconsolidated state;
removing the first intermediate part from the mold; heating the
first intermediate part at a first temperature sufficient to remove
the binder material while leaving the plurality of particulates in
the substantially unconsolidated state, thereby forming a second
intermediate part; and heating the second intermediate part at a
second temperature sufficient to consolidate the plurality of
particulates together to form a densified part.
[0053] Densified parts formed via powder injection molding
techniques may be less densified than are those formed through the
hot pressing techniques discussed above. Namely, upon removal of
the binder material (e.g., by carbonization), voids may remain
within the first intermediate part. The voids may not undergo
complete filling once the plurality of particulates undergo
consolidation to form the second intermediate part. Moreover, part
shrinkage may take place when converting the first intermediate
part to the second intermediate part due to the presence and
filling of the voids. Despite their lower density, densified parts
formed via powder injection molding processes may be sufficiently
dense for some purposes. In particular, since a phase change does
not take place when performing powder injection molding processes,
the part shrinkage may be small enough to produce a sufficiently
densified part.
[0054] In some instances, further densification of parts formed by
powder injection molding processes may be desired, in which case
the densified part may undergo heating and pressurization in a
pressure vessel to promote additional densification of the
densified part. Such techniques for further densifying the
densified part may resemble the hot pressing techniques discussed
above, except for placing the densified part directly in the
pressure vessel instead of in a container.
[0055] Suitable binder materials for use in powder injection
molding processes of the present disclosure are not considered to
be particularly limited, provided that the binder material may be
suitably dispensed into the mold in conjunction with the plurality
of particulates comprising the high-manganese steel. Once hardened,
suitable binder materials are also sufficient to hold the plurality
of particulates in the near-net shape following removal of the
first intermediate part from the mold. Suitable binder materials
may be thermally decomposable at the first temperature, so as to
promote removal of the binder material and formation of the second
intermediate part. In illustrative embodiments, suitable binder
materials may include, for example, polymers or waxes. Both
thermoplastic and thermosetting polymers may be suitably used.
Particularly suitable binder materials may be liquefiable (e.g., by
heating) at a temperature below the first temperature, such that
the hinder material may be introduced to the mold in a liquid
state. Liquid polymer precursors may also be suitably used in this
regard. Thereafter, the binder material may undergo setting (e.g.,
hardening or solidification) to maintain the plurality of
particulates and the binder material in a near-net shape defined
within the mold.
[0056] Powder injection molding processes of the present disclosure
may take place with the plurality of particulates mixed with the
binder material. That is, according to particular embodiments of
the present disclosure, the plurality of particulates and the
binder material may be premixed before being introduced to the
mold. In other embodiments of the present disclosure, the plurality
of particulates and the binder material may be introduced to the
mold separately. In more particular embodiments of the present
disclosure, the plurality of particulates and the binder material
may be separately introduced into the mold. When introduced to the
mold separately, the plurality of particulates and the binder
material may be disposed heterogeneously within the first
intermediate part, according to particular embodiments of the
present disclosure.
[0057] Moreover, different steel compositions may be disposed
heterogeneously within the near-net shape part formed within the
mold. For example, in particular embodiments, a first plurality of
particulates comprising a high-manganese steel may be disposed in a
first location within the near-net shape part, and a second
plurality of particulates comprising a different high-manganese
steel or a steel composition that is not a high-manganese steel may
be disposed at a second location within the near-net shape part. In
particular embodiments, the first plurality of particulates
comprising the high-manganese steel may be located on or near the
surface of the near-net shape part to afford erosion and/or
corrosion resistance thereto. In a preferred embodiment, the
surface of the near-net shape part to afford erosion and/or
corrosion resistance is located at the internal surface of the
part, such as the internal wall of a pipe or pipe fitting.
[0058] Grain sizes obtainable in the powder injection molding
processes of the present disclosure may be fine and equiaxed, which
may aid in promoting consistent, isotropic mechanical properties
within the part. In contrast, forged or cast components formed from
the same high-manganese steel may possess directional properties,
either longitudinal or transverse, depending on the particular
manufacturing parameters used.
[0059] Densified parts formed by the hot pressing and powder
injection molding processes disclosed herein are not considered to
be particularly limited in form. In particularly advantageous
embodiments, however, densified parts formed according to the
present disclosure may comprise a pipeline connector. Suitable
pipeline connectors that may be formed from a high-manganese steel
include, for example, weld neck flanges, flanged elbows, flanged T
joints, and similar structures. Design components of these
structures will be familiar to one having ordinary skill in the
art.
Embodiments Disclosed Herein Include:
[0060] A. Hot pressing processes. The processes comprise: providing
a plurality of particulates comprising a high-manganese steel;
loading a container with the plurality of particulates, the
container having an internal surface formed in a near-net shape of
a part; establishing a reduced pressure state in the container
after loading the container with the plurality of particulates, and
sealing the container to maintain the reduced pressure state
therein, thereby affording a sealed container; placing the sealed
container in a pressure vessel; heating the pressure vessel at a
predetermined temperature while applying a predetermined pressure
isostatically to an exterior surface of the sealed container with a
pressurizing gas; wherein the predetermined temperature and the
predetermined pressure in combination are sufficient to consolidate
the plurality of particulates to form a densified part having the
near-net shape; and removing the sealed container to expose a
surface of the densified part.
[0061] B. Intermediate part formation processes. The processes
comprise: providing a plurality of particulates comprising a
high-manganese steel; introducing the plurality of particulates and
a binder material into a mold having an internal surface formed in
a near-net shape of a part; setting the binder material to form a
first intermediate part in which the plurality of particulates
remain in a substantially unconsolidated state; removing the first
intermediate part from the mold; heating the first intermediate
part at a first temperature sufficient to remove the binder
material while leaving the plurality of particulates in the
substantially unconsolidated state, thereby forming a second
intermediate part; and heating the second intermediate part at a
second temperature sufficient to consolidate the plurality of
particulates together to form a densified part.
[0062] Embodiments A and B may have one or more of the following
additional elements in any combination:
[0063] Element 1: wherein removing the sealed container comprises a
pickling treatment that dissolves the container.
[0064] Element 2: wherein removing the sealed container comprises a
machining operation that disassembles the container.
[0065] Element 3: wherein sealing the container comprises a seal
welding operation.
[0066] Element 4: wherein the densified part is a pipeline
connector.
[0067] Element 5: wherein the densified part is a weld neck pipe
flange.
[0068] Element 6: wherein the densified part is a flanged pipe
elbow or a flanged pipe T.
[0069] Element 7: wherein the predetermined temperature does not
lead to formation of a liquid phase in the container.
[0070] Element 8: wherein the binder material comprises a polymer
or a wax.
[0071] Element 9: wherein the further comprises: providing a second
plurality of particulates comprising a second high-manganese steel
with a different composition from the high-manganese steel or a
steel composition that is not a high-manganese steel; wherein the
loading the container with the plurality of particulates comprises
disposing the plurality of particulates of the high-manganese steel
in a first location of the container and disposing plurality of
particulates of the second high-manganese steel or the steel
composition that is not a high-manganese steel in a second location
of the container.
[0072] Element 10: wherein the second location of the container is
in a location of the container that forms the internal surface of
the near-net shape part.
[0073] Element 11: wherein introducing the plurality of
particulates and the binder material into the mold takes place by
injection molding.
[0074] Element 12: wherein the plurality of particulates and the
binder material are premixed before being introduced to the
mold.
[0075] Element 13: wherein the plurality of particulates and the
binder material are separately introduced into the mold.
[0076] Element 14: wherein the plurality of particulates and the
binder material are disposed heterogeneously in the first
intermediate part.
[0077] Element 15: wherein the second temperature does not lead to
formation of a liquid phase in the container.
[0078] By way of non-limiting example, exemplary combinations
applicable to A include, but are not limited to: 1 or 2 and 3; 1 or
2 and 4; 1 or 2 and 5; 1 or 2 and 6; 1 or 2 and 7; 1 or 2, 3 and 4;
1 or 2, 3 and 5; 1 or 2, 3 and 6; 1 or 2, 3 and 7; 3 and 4; 3 and
5; 3 and 6; 3 and 7; 3, 4 and 7; 3, 5 and 7; 3, 6 and 7; 4 and 7; 5
and 7; 6 and 7; and 8 and 9. By way of further non-limiting
example, exemplary combinations applicable to B include, but are
not limited to: 4 and 8; 5 and 8; 6 and 8; 4 and 11; 5 and 11; 6
and 11; 4 and 12; 5 and 12; 6 and 12; 4 and 13; 5 and 13; 6 and 13;
8 and 11; 8 and 12; 8 and 13; 8, 13 and 14; 8 and 15; 11 and 12; 11
and 13; 11, 13 and 14; 12 and 13; 12-14; 12 and 15; and 13 and
15.
[0079] All documents described herein are incorporated by reference
herein for purposes of all jurisdictions where such practice is
allowed, including any priority documents and/or testing procedures
to the extent they are not inconsistent with this text. As is
apparent from the foregoing general description and the specific
embodiments, while forms of the disclosure have been illustrated
and described, various modifications can be made without departing
from the spirit and scope of the disclosure. Accordingly, it is not
intended that the disclosure be limited thereby. For example, the
compositions described herein may be free of any component, or
composition not expressly recited or disclosed herein. Any method
may lack any step not recited or disclosed herein. Likewise, the
term "comprising" is considered synonymous with the term
"including." Whenever a method, composition, element or group of
elements is preceded with the transitional phrase "comprising," it
is understood that we also contemplate the same composition or
group of elements with transitional phrases "consisting essentially
of," "consisting of," "selected from the group of consisting of,"
or "is" preceding the recitation of the composition, element, or
elements and vice versa.
[0080] Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as molecular weight,
reaction conditions, and so forth used in the present specification
and associated claims are to be understood as being modified in all
instances by the term "about." Accordingly, unless indicated to the
contrary, the numerical parameters set forth in the following
specification and attached claims are approximations that may vary
depending upon the desired properties sought to be obtained by the
embodiments of the present invention. At the very least, and not as
an attempt to limit the application of the doctrine of equivalents
to the scope of the claim, each numerical parameter should at least
be construed in light of the number of reported significant digits
and by applying ordinary rounding techniques.
[0081] Whenever a numerical range with a lower limit and an upper
limit is disclosed, any number and any included range falling
within the range is specifically disclosed. In particular, every
range of values (of the form, "from about a to about b," or,
equivalently, "from approximately a to b," or, equivalently, "from
approximately a-b") disclosed herein is to be understood to set
forth every number and range encompassed within the broader range
of values. Also, the terms in the claims have their plain, ordinary
meaning unless otherwise explicitly and clearly defined by the
patentee. Moreover, the indefinite articles "a" or "an," as used in
the claims, are defined herein to mean one or more than one of the
element that it introduces.
[0082] One or more illustrative embodiments are presented herein.
Not all features of a physical implementation are described or
shown in this application for the sake of clarity. It is understood
that in the development of a physical embodiment of the present
disclosure, numerous implementation-specific decisions must be made
to achieve the developer's goals, such as compliance with
system-related, business-related, government-related and other
constraints, which vary by implementation and from time to time.
While a developer's efforts might be time-consuming, such efforts
would be, nevertheless, a routine undertaking for one of ordinary
skill in the art and having benefit of this disclosure.
[0083] Therefore, the present disclosure is well adapted to attain
the ends and advantages mentioned as well as those that are
inherent therein. The particular embodiments disclosed above are
illustrative only, as the present disclosure may be modified and
practiced in different but equivalent manners apparent to one
having ordinary skill in the art and having the benefit of the
teachings herein. Furthermore, no limitations are intended to the
details of construction or design herein shown, other than as
described in the claims below. It is therefore evident that the
particular illustrative embodiments disclosed above may be altered,
combined, or modified and all such variations are considered within
the scope and spirit of the present disclosure. The embodiments
illustratively disclosed herein suitably may be practiced in the
absence of any element that is not specifically disclosed herein
and/or any optional element disclosed herein.
* * * * *