U.S. patent application number 11/954909 was filed with the patent office on 2008-06-26 for system, method and apparatus for hardfacing composition for earth boring bits in highly abrasive wear conditions using metal matrix materials.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. Invention is credited to James Leslie Overstreet.
Application Number | 20080149397 11/954909 |
Document ID | / |
Family ID | 39315115 |
Filed Date | 2008-06-26 |
United States Patent
Application |
20080149397 |
Kind Code |
A1 |
Overstreet; James Leslie |
June 26, 2008 |
SYSTEM, METHOD AND APPARATUS FOR HARDFACING COMPOSITION FOR EARTH
BORING BITS IN HIGHLY ABRASIVE WEAR CONDITIONS USING METAL MATRIX
MATERIALS
Abstract
A highly abrasive wear metal matrix composite hardfacing
material for downhole tools is disclosed. The hardfacing material
may comprise a matrix of a softer material with high hardness, such
as amorphous nanocomposite steel alloys, and one or more hard
component materials. The hard component materials may comprise
sintered tungsten carbide, monocrystalline WC, polycrystalline WC,
and the additional component of spherical cast tungsten carbide.
Alternatively, a matrix of softer material, hard component
materials and crushed cast tungsten carbide may be used.
Inventors: |
Overstreet; James Leslie;
(Tomball, TX) |
Correspondence
Address: |
BRACEWELL & GIULIANI LLP
P.O. BOX 61389
HOUSTON
TX
77208-1389
US
|
Assignee: |
BAKER HUGHES INCORPORATED
Houston
TX
|
Family ID: |
39315115 |
Appl. No.: |
11/954909 |
Filed: |
December 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60871270 |
Dec 21, 2006 |
|
|
|
Current U.S.
Class: |
175/374 ;
148/403; 76/108.4 |
Current CPC
Class: |
C22C 45/02 20130101;
E21B 10/50 20130101; C22C 29/08 20130101; B22F 2005/001 20130101;
C23C 30/005 20130101 |
Class at
Publication: |
175/374 ;
148/403; 76/108.4 |
International
Class: |
E21B 10/08 20060101
E21B010/08; C22C 45/02 20060101 C22C045/02; B21K 5/02 20060101
B21K005/02 |
Claims
1. A hardfacing material formed from a metal matrix composite for
highly abrasive wear applications, comprising: a matrix formed from
a softer amorphous nanocomposite steel alloy and having a hardness
of at least 60 Rc; and a hard component in the matrix of softer
amorphous nanocomposite steel alloy, the hard component having a
higher hardness than the matrix.
2. A hardfacing material according to claim 1, wherein the matrix
comprises a range of about 20 to 90 wt % of the metal matrix
composite, and the hard component comprises a range of about 10 to
80 wt % of the metal matrix composite.
3. A hardfacing material according to claim 1, wherein the matrix
comprises about 30 wt % of the metal matrix composite, and the hard
component comprises about 70 wt % of the metal matrix
composite.
4. A hardfacing material according to claim 1, wherein the matrix
comprises about 40 wt % of the metal matrix composite, and the hard
component comprises about 60 wt % of the metal matrix
composite.
5. A hardfacing material according to claim 1, wherein the hard
component comprises spherical sintered tungsten carbide
pellets.
6. A hardfacing material according to claim 1, wherein the hard
component is formed from at least one of sintered tungsten carbide
and cast tungsten carbide.
7. A hardfacing material according to claim 1, wherein the hard
component is formed from at least one of spherical and crushed
tungsten carbide.
8. A hardfacing material according to claim 1, wherein the hard
component is formed from at least one of monocrystalline WC,
macrocrystalline WC and polycrystalline WC.
9. A hardfacing material according to claim 1, wherein the hard
component further comprises spherical cast tungsten carbide.
10. A hardfacing material according to claim 1, wherein the hard
component has a particle size in a mesh range of -16 to +325, and
the matrix has a hardness of at least 65 Rc.
11. A downhole tool, comprising: a downhole tool body; a hardfacing
on the downhole tool body, the hardfacing being formed from a metal
matrix composite for highly abrasive wear applications; the
hardfacing comprising: a matrix formed from a softer amorphous
nanocomposite steel alloy and having a hardness of at least 60 Rc;
and a hard component in the matrix of softer amorphous
nanocomposite steel alloy, the hard component having a higher
hardness than the matrix.
12. A downhole tool according to claim 11, wherein the matrix
comprises a range of about 20 to 90 wt % of the metal matrix
composite, and the hard component comprises a range of about 10 to
80 wt % of the metal matrix composite.
13. A downhole tool according to claim 11, wherein the downhole
tool body comprises a drill bit body having gage areas, legs, and
roller cones rotatably mounted to the legs, and each of the roller
cones having steel teeth extending therefrom, and wherein the
hardfacing is located on at least one of the gage areas, legs, and
steel teeth.
14. A downhole tool according to claim 11, wherein the matrix
comprises about 40 wt % of the metal matrix composite, and the hard
component comprises about 60 wt % of the metal matrix
composite.
15. A downhole tool according to claim 11, wherein the hard
component comprises spherical sintered tungsten carbide
pellets.
16. A downhole tool according to claim 11, wherein the hard
component is formed from at least one of sintered tungsten carbide
and cast tungsten carbide.
17. A downhole tool according to claim 16, wherein the hard
component further comprises at least one of spherical and crushed
tungsten carbide.
18. A downhole tool according to claim 16, wherein the hard
component further comprises at least one of monocrystalline WC,
macrocrystalline WC and polycrystalline WC.
19. A downhole tool according to claim 11, wherein the hard
component further comprises spherical cast tungsten carbide.
20. A downhole tool according to claim 11, wherein the hard
component has a particle size in a mesh range of -16 to +325, and
the matrix has a hardness of at least 65 Rc.
21. A method of forming a drill bit, comprising: (a) providing
roller cones with steel teeth extending therefrom; (b) applying a
hardfacing on the steel teeth, the hardfacing being formed from a
metal matrix composite for highly abrasive wear applications; the
hardfacing comprising a matrix formed from a softer amorphous
nanocomposite steel alloy and having a hardness of at least 60 Rc,
and a hard component in the matrix of softer amorphous
nanocomposite steel alloy, the hard component having a higher
hardness than the matrix; and (c) rotatably mounting the roller
cones to a drill bit body.
22. A method according to claim 21, wherein step (b) comprises
applying the hardfacing to the steel teeth with a welding technique
selected from the group consisting of PTA pulsed arc, PTA
continuous arc, MIG pulsed arc, MIG continuous arc, TIG pulsed arc,
TIG continuous arc, and oxy-acetylene.
23. A method according to claim 21, wherein the matrix comprises a
range of about 20 to 90 wt % of the metal matrix composite, and the
hard component comprises a range of about 10 to 80 wt % of the
metal matrix composite.
24. A method according to claim 21, wherein the hard component is
selected from the group consisting of sintered tungsten carbide,
cast tungsten carbide, spherical sintered tungsten carbide pellets,
spherical tungsten carbide, crushed tungsten carbide,
monocrystalline WC, macrocrystalline WC and polycrystalline WC.
25. A method according to claim 21, wherein the hard component
further comprises spherical cast tungsten carbide, and the hard
component has a particle size in a mesh range of -16 to +325, and
the matrix has a hardness of at least 65 Rc.
Description
[0001] This non-provisional patent application claims priority to
and the benefit of U.S. Provisional Patent App. No. 60/871,270,
which was filed on Dec. 21, 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention relates in general to hardfacing and,
in particular, to an improved highly abrasive wear metal matrix
composite hardfacing materials, such as for downhole tools.
[0004] 2. Description of the Related Art
[0005] It is a long-standing practice in the design and manufacture
of earth-boring bits to apply wear-resistant hardfacing materials
to the surfaces of such bits that are subjected to abrasive wear
during drilling operations. In earth-boring bits of the rolling
cutter variety, these surfaces include the teeth of bits of the
milled or steel tooth variety, the gage surfaces of the rolling
cutters and the shirttails of the bit legs comprising the bit
body.
[0006] In the past, these hardfacing compositions generally
comprise carbides of the elements of Groups IVB, VB and VIB in a
matrix metal of iron, cobalt or nickel and alloys and mixtures
thereof. The hardfacing is applied by melting the matrix and a
portion of the surface to which the hardfacing is applied with an
oxyacetylene or atomic hydrogen torch. The carbide particles give
the hardfacing material hardness and wear resistance, while the
matrix metal lends the hardfacing fracture toughness. A hardfacing
composition must strike an adequate balance between wear resistance
(hardness) and fracture toughness. A hardfacing composition that is
extremely hard and wear-resistant may lack fracture toughness,
causing the hardfacing to crack and flake prematurely. Conversely,
a hardfacing with adequate fracture toughness, but inadequate
hardness and wear resistance, is eroded prematurely and fails to
serve its purpose.
[0007] Many factors affect the suitability of a hardfacing
composition for a particular application. These factors include the
chemical composition and physical structure of the carbides
employed in the composition, the chemical composition and
microstructure of the matrix metal or alloy, and the relative
proportions of the carbide materials to one another and to the
matrix metal or alloy.
[0008] One early advance in hardfacing compositions for use in
earth-boring bits is disclosed in commonly assigned U.S. Pat. No.
3,800,891, to White. This patent discloses a hardfacing composition
comprising sintered tungsten carbide in an alloy steel matrix.
Sintered tungsten carbide comprises grains or particles of tungsten
carbide sintered with and held together by a binder of non-carbide
material, such as cobalt. The sintered tungsten carbide possesses
greater fracture toughness than the more conventional cast tungsten
carbide, such that the resulting hardfacing composition possess
good fracture toughness without sacrificing hardness and wear
resistance.
[0009] U.S. Pat. No. 4,836,307, to Keshavan, discloses a hardfacing
composition employing particles of cemented or sintered tungsten
carbide and relatively small particles of single crystal
monotungsten carbide, sometimes referred to as "macrocrystalline"
tungsten carbide, in a mild steel matrix. This composition purports
to possess the advantages of sintered tungsten carbide, as
disclosed in U.S. Pat. No. 3,800,891, with the advantages of single
crystal monotungsten carbide, which is harder than the cemented or
sintered tungsten carbide, yet is less brittle than the alternative
cast carbide.
[0010] U.S. Pat. No. 5,089,182, to Findeisen, discloses a method of
manufacturing cast carbide pellets that are generally spherical in
shape and have improved mechanical and metallurgical properties
over prior-art carbide pellets. These cast pellets are not truly
spherical, but are sufficiently symmetrical that residual stresses
in the pellets are minimized. Also, the generally spherical shape
of these pellets eliminates corners, sharp edges and angular
projections, which are present in conventional crushed particles,
that increase residual stresses in the particles and tend to melt
as the hardfacing composition is applied to the surface.
[0011] U.S. Pat. No. 5,663,512, to Schader, discloses a hardfacing
composition which includes a quantity of spherical sintered
tungsten carbide granules and a quantity of cast spherical cast
tungsten carbide granules in a eutectic form of WC/W.sub.2C. During
application, some melting of the sintered spherical carbide
granules occurs, which precipitates into the metal matrix and coats
the spherical WC/W.sub.2C granules. Although this composition
provides a good balance between hardness and fractures toughness, a
drill bit having the toughness, ductility, and impact strength of
steel and the hardness and wear resistance of tungsten carbide or
other hard metal on the exterior surface, but without the problems
of prior art steel body or steel tooth bits would be desirable.
SUMMARY OF THE INVENTION
[0012] Embodiments of a system, method, and apparatus for a highly
abrasive wear metal matrix composite hardfacing material for
downhole tools are disclosed. The hardfacing material may comprise
a matrix of relatively softer material with high hardness, such as
amorphous nanocomposite steel alloys, and one or more hard
component materials. The hard component materials may comprise
sintered tungsten carbide (e.g., WC/Co), monocrystalline WC,
multicrystalline or polycrystalline WC, and the additional
component of spherical cast tungsten carbide (e.g., a eutectic of
WC/W.sub.2C). Alternatively, a matrix of softer material, hard
component materials and crushed cast tungsten carbide may be
used.
[0013] The foregoing and other objects and advantages of the
present invention will be apparent to those skilled in the art, in
view of the following detailed description of the present
invention, taken in conjunction with the appended claims and the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] So that the manner in which the features and advantages of
the present invention, which will become apparent, are attained and
can be understood in more detail, more particular description of
the invention briefly summarized above may be had by reference to
the embodiments thereof that are illustrated in the appended
drawings which form a part of this specification. It is to be
noted, however, that the drawings illustrate only some embodiments
of the invention and therefore are not to be considered limiting of
its scope as the invention may admit to other equally effective
embodiments.
[0015] FIG. 1 is an isometric view of one embodiment of a bit
constructed in accordance with the present invention;
[0016] FIG. 2 is a micrograph illustration of one embodiment of
hardfacing material constructed in accordance with the invention;
and
[0017] FIG. 3 is a micrograph illustration of another embodiment of
hardfacing material constructed in accordance with the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Hardfacing materials formed from amorphous nanocomposite
steel alloys, such as NANOSTEEL.RTM., such as those now
commercially available for plasma transferred arc (PTA) welding
applications. Some recent materials are reported to have high
hardness while retaining their toughness, which is desirable for
impact loading.
[0019] One of the problems associated with conventional PTA
nickel-based or iron-based hardfacing materials is that their
retention of the hard component particles is compromised as the
hardness of the softer material is increased. This may produce an
embrittled deposit and compromise the hardfacing. However, as a
result of improved application techniques, more exotic materials
such as amorphous nanocomposite steel alloys may be utilized as a
relatively softer material in conjunction with hard component
materials on downhole tools.
[0020] For example, sintered tungsten carbide or cast tungsten
carbide, e.g., spherical or crushed, monocrystalline or
polycrystalline WC, or other carbide formers may be used as the
hard component materials in the softer amorphous nanocomposite
steel alloys to achieve even better wear resistance without losing
toughness or compromising the end deposit. By varying the physical
sizes and combinations of these hard component materials,
especially spherical sintered tungsten carbide pellets and/or
spherical cast tungsten carbide, superior wear resistant
compositions are achieved.
[0021] Referring now to FIG. 1, one embodiment of a highly abrasive
wear metal matrix composite hardfacing material 21 is shown. The
invention is particularly well suited for use at many different
locations on downhole tools, such as on the roller cone legs of a
drill bit 23 or other types of downhole tools (e.g., steel tooth
bits, TCI bits, steel body PDC bits, RWD tools, etc.) but it is not
limited to these applications.
[0022] As shown in FIG. 2, the hardfacing material may comprise a
matrix 11 of a softer material with high hardness (e.g., a minimum
of 60 Rc, and in some embodiments, 65+ Rc, e.g., 72 Rc) such as
amorphous nanocomposite steel alloys (e.g., NANOSTEEL.RTM.) and one
or more hard component materials. The hard component materials may
be selected from, for example, sintered tungsten carbide (e.g.,
WC/Co) (spherical 13 or crushed 15), monocrystalline WC,
macrocrystalline WC, multicrystal or polycrystalline WC and, in
some embodiments, the additional component of spherical cast
tungsten carbide (e.g., a eutectic of WC/W.sub.2C) 17, each of
which may be crushed in form. Another example is shown in FIG. 3,
having a matrix 31 of relatively softer material (e.g., amorphous
nanocomposite steel alloy) and hard component materials such as
monocrystalline WC 33 and crushed cast tungsten carbide 35.
[0023] The invention may comprise numerous different size ratios
between the various components. For example, the particle size for
each component may range from, for example, mesh -16 to +325. In
addition, the distribution between the components also may be
formulated in weight percentages as, for example, 30 wt % soft
component and 70 wt % hard component. The range for other
embodiments comprises a soft component low end of about 20 wt % to
a soft component high end of 90%, with complementary hard component
low and high ends at 10 wt % and 80 wt %. Moreover, the hard
component may comprise up to 100% sintered tungsten carbide (e.g.,
crushed or spherical), or less than 100% spherical cast tungsten
carbide (e.g., crushed), or mono-, macro- or polycrystalline WC, or
any combination thereof.
[0024] While the invention has been shown or described in only some
of its forms, it should be apparent to those skilled in the art
that it is not so limited, but is susceptible to various changes
without departing from the scope of the invention. For example,
although the invention is described with PTA welding, other welding
techniques known to those skilled in the art, such as MIG, TIG (any
of preceding may be continuous or pulsed arc applications),
Flamespray, oxyacetylene, etc., also may be used.
* * * * *