U.S. patent application number 15/360655 was filed with the patent office on 2017-05-25 for grain boundary cohesion enhanced sulfide stress cracking (ssc)-resistant steel alloys.
The applicant listed for this patent is QUESTEK INNOVATIONS LLC. Invention is credited to Aziz Asphahani, Gregory B. Olson, James Saal.
Application Number | 20170145547 15/360655 |
Document ID | / |
Family ID | 58721408 |
Filed Date | 2017-05-25 |
United States Patent
Application |
20170145547 |
Kind Code |
A1 |
Saal; James ; et
al. |
May 25, 2017 |
GRAIN BOUNDARY COHESION ENHANCED SULFIDE STRESS CRACKING
(SSC)-RESISTANT STEEL ALLOYS
Abstract
Alloys, processes for preparing the alloys, and articles
including the alloys are provided. The alloys can include, by
weight, about 0% to about 8% nickel, about 1% to about 6% tungsten,
about 1% to about 4% copper, about 0.1% to about 2% chromium, about
0.01% to about 1% vanadium, about 0.01% to about 0.5% carbon, about
0.01% to about 0.1% titanium, about 0.001% to about 0.01% boron,
about 0% to about 1% silicon, and about 0% to about 0.1% calcium,
the balance essentially iron and incidental elements and
impurities.
Inventors: |
Saal; James; (Chicago,
IL) ; Olson; Gregory B.; (Riverwoods, IL) ;
Asphahani; Aziz; (Ottawa, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUESTEK INNOVATIONS LLC |
EVANSTON |
IL |
US |
|
|
Family ID: |
58721408 |
Appl. No.: |
15/360655 |
Filed: |
November 23, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62259835 |
Nov 25, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C21D 6/004 20130101;
C21D 8/105 20130101; B22D 18/00 20130101; C22C 38/44 20130101; C21D
9/08 20130101; C22C 38/46 20130101; C21D 1/18 20130101; C22C 38/50
20130101; C22C 38/54 20130101; C21D 1/25 20130101; C22C 38/42
20130101; F16L 9/02 20130101 |
International
Class: |
C22C 38/54 20060101
C22C038/54; C22C 38/42 20060101 C22C038/42; C22C 38/44 20060101
C22C038/44; C22C 38/50 20060101 C22C038/50; C22C 38/46 20060101
C22C038/46 |
Claims
1. An alloy comprising, by weight, about 0% to about 8% nickel,
about 1% to about 6% tungsten, about 1% to about 4% copper, about
0.1% to about 2% chromium, about 0.01% to about 1% vanadium, about
0.01% to about 0.5% carbon, about 0.01% to about 0.1% titanium,
about 0.001% to about 0.01% boron, about 0% to about 1% silicon,
and about 0% to about 0.1% calcium, the balance essentially iron
and incidental elements and impurities.
2. The alloy of claim 1 comprising, by weight, about 6% to about 7%
nickel, about 3.5% to about 4.5% tungsten, about 2% to about 3%
copper, about 0.1% to about 1% chromium, about 0.01% to about 0.2%
vanadium, about 0.01% to about 0.2% carbon, about 0.01% to about
0.05% titanium, and about 0.001% to about 0.002% boron, the balance
essentially iron and incidental elements and impurities.
3. The alloy of claim 1, wherein the alloy has a calculated
.DELTA.2.gamma. value of less than or equal to -2 J/m.sup.2.
4. The alloy of claim 1, wherein the alloy has a yield strength of
greater than or equal to 965 MPa (140 ksi), measured according to
ASTM E8.
5. The alloy of claim 1, wherein the alloy has a sulfide stress
corrosion cracking toughness (K1SSC) value of greater than or equal
to 44 MPa*m.sup.1/2 (40 ksi*in.sup.1/2).
6. The alloy of claim 1, wherein the alloy has an M.sub.2C phase
fraction of 0.01 to 0.015, wherein M is selected from the group
consisting of W, Cr, V, and Ti, or any combination thereof
7. The alloy of claim 1, wherein the alloy has a body centered
cubic copper phase fraction of
0. 025 to 0.035.
8. The alloy of claim 1 comprising about 6.5% nickel.
9. The alloy of claim 1 comprising about 4% tungsten.
10. The alloy of claim 1 comprising about 2.5% copper.
11. The alloy of claim 1 comprising about 0.5% chromium.
12. The alloy of claim 1 comprising about 0.1% vanadium.
13. The alloy of claim 1 comprising about 0.1% carbon.
14. The alloy of claim 1 comprising about 0.02% titanium.
15. The alloy of claim 1 comprising about 0.0015% boron.
16. The alloy of claim 1 comprising, by weight, about 6.5% nickel,
about 4.5% tungsten, about 2.5% copper, about 0.5% chromium, about
0.1% vanadium, about 0.1% carbon, about 0.02% titanium, and about
0.0015% boron, the balance essentially iron and incidental elements
and impurities.
17. A method for producing an alloy comprising: preparing a melt
that comprises, by weight, about 0% to about 8% nickel, about 1% to
about 6% tungsten, about 1% to about 4% copper, about 0.1% to about
2% chromium, about 0.01% to about 1% vanadium, about 0.01% to about
0.5% carbon, about 0.01% to about 0.1% titanium, about 0.001% to
about 0.01% boron, about 0% to about 1% silicon, and about 0% to
about 0.1% calcium, the balance essentially iron and incidental
elements and impurities.
18. The method of claim 17, wherein the melt comprises, by weight,
about 6% to about 7% nickel, about 3.5% to about 4.5% tungsten,
about 2% to about 3% copper, about 0.1% to about 1% chromium, about
0.01% to about 0.2% vanadium, about 0.01% to about 0.2% carbon,
about 0.01% to about 0.05% titanium, and about 0.001% to about
0.002% boron, the balance essentially iron and incidental elements
and impurities.
19. The method of claim 17, wherein the melt comprises, by weight,
about 6.5% nickel, about 4.5% tungsten, about 2.5% copper, about
0.5% chromium, about 0.1% vanadium, about 0.1% carbon, about 0.02%
titanium, and about 0.0015% boron, the balance essentially iron and
incidental elements and impurities.
20. The method of claim 17, wherein the alloy has a calculated
.DELTA.2.gamma. value of less than or equal to -2 J/m.sup.2.
21. The method of claim 17, wherein the alloy has a yield strength
of greater than or equal to 965 MPa (140 ksi), measured according
to ASTM E8.
22. The method of claim 17, wherein the alloy has a sulfide stress
corrosion cracking toughness (K1SSC) value of greater than or equal
to 44 MPa*m.sup.1/2 (40 ksi*in.sup.1/2).
23. The method of claim 17, wherein the alloy has an M.sub.2C phase
fraction of 0.01 to 0.015, wherein M is selected from the group
consisting of W, Cr, V, and Ti, or any combination thereof
24. The method of claim 17, wherein the alloy has a body centered
cubic copper phase fraction of 0.025 to 0.035.
25. The method of claim 17, wherein the alloy is produced by vacuum
melt or air melt practices.
26. A manufactured article comprising an alloy that comprises, by
weight, about 0% to about 8% nickel, about 1% to about 6% tungsten,
about 1% to about 4% copper, about 0.1% to about 2% chromium, about
0.01% to about 1% vanadium, about 0.01% to about 0.5% carbon, about
0.01% to about 0.1% titanium, about 0.001% to about 0.01% boron,
about 0% to about 1% silicon, and about 0% to about 0.1% calcium,
the balance essentially iron and incidental elements and
impurities.
27. The article of claim 26, wherein the alloy comprises, by
weight, about 6% to about 7% nickel, about 3.5% to about 4.5%
tungsten, about 2% to about 3% copper, about 0.1% to about 1%
chromium, about 0.01% to about 0.2% vanadium, about 0.01% to about
0.2% carbon, about 0.01% to about 0.05% titanium, and about 0.001%
to about 0.002% boron, the balance essentially iron and incidental
elements and impurities.
28. The article of claim 26, wherein the alloy comprises, by
weight, about 6.5% nickel, about 4.5% tungsten, about 2.5% copper,
about 0.5% chromium, about 0.1% vanadium, about 0.1% carbon, about
0.02% titanium, and about 0.0015% boron, the balance essentially
iron and incidental elements and impurities.
29. The article of claim 26, wherein the alloy has a calculated
.DELTA.2.gamma. value of less than or equal to -2 J/m.sup.2.
30. The article of claim 26, wherein the alloy has a yield strength
of greater than or equal to 965 MPa (140 ksi), measured according
to ASTM E8.
31. The article of claim 26, wherein the alloy has a sulfide stress
corrosion cracking toughness (K1SSC) value of greater than or equal
to 44 MPa*m.sup.1/2 (40 ksi*in.sup.1/2).
32. The article of claim 26, wherein the alloy has an M.sub.2C
phase fraction of 0.01 to 0.015, wherein M is selected from the
group consisting of W, Cr, V, and Ti, or any combination
thereof
33. The article of claim 26, wherein the alloy has a body centered
cubic copper phase fraction of 0.025 to 0.035.
34. The article of claim 26, wherein the article is a steel pipe or
steel tube.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/259,835, filed Nov. 25, 2015, and is herein
incorporated by reference in its entirety.
BACKGROUND
[0002] Sulfide stress cracking (SSC) is a primary cause of failure
for steel tubing in H.sub.2S-containing (sour) environments. In
general, the higher the strength of the steel, the more susceptible
the alloy is to failure in sour environments. It is observed that
such SSC steel failure is mostly caused by intergranular (IG)
cracking, which is related to fracture by hydrogen embrittlement
(HE). In addition, it is recognized that the IG-SSC of steels can
be correlated to IG stress corrosion cracking (SCC), as caused by
hydrogen. As such, there is a need for cost-competitive high
strength steels with enhanced resistance to SCC/SSC, since known
materials that are resistant to SCC/SSC (e.g., corrosion-resistant
nickel-based alloys) are expensive and hinder the economic
development of projects involving sour services.
SUMMARY
[0003] The oil and gas industry has a significant need for a high
strength low alloy (HSLA) steel with a yield strength of 965-1100
MPa (140-160 ksi). Existing HSLA steels suffer from either a low
sulfide stress corrosion cracking toughness or yield strength, or
both. Accordingly, there exists a need for an HSLA steel that can
be economically manufactured and have good sulfide stress corrosion
cracking toughness and good yield strength.
[0004] In one aspect, disclosed is an alloy comprising, by weight,
about 0% to about 8% nickel, about 1% to about 6% tungsten, about
1% to about 4% copper, about 0.1% to about 2% chromium, about 0.01%
to about 1% vanadium, about 0.01% to about 0.5% carbon, about 0.01%
to about 0.1% titanium, about 0.001% to about 0.01% boron, about 0%
to about 1% silicon, and about 0% to about 0.1% calcium, the
balance essentially iron and incidental elements and
impurities.
[0005] Other aspects of the disclosure include processes for
producing the alloy, and manufactured articles comprising the
alloy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The patent or application file contains at least one drawing
executed in color. Copies of this patent or patent application
publication with color drawing(s) will be provided by the Office
upon request and payment of the necessary fee.
[0007] FIG. 1 is an illustration of K1SCC versus yield strength.
The points labeled "Lit. HSLA (SSC)" in the lower left are
literature values for existing HSLA oil and gas SSC-resistant
steels. Note that these points are reported values of KISSC (which
correlates to KISCC). The bottom curve is a fit to these points.
The points labeled "HyTuf", "4340", "300M", and "AerMet100" are
existing high strength alloys, and follow the bottom curve. The
points labeled "QT S53", "QT PH48S" and "QT M54" are existing
steels and are significantly higher than the bottom curve,
presumably due to the increased grain boundary cohesion. The middle
curve is the bottom curve shifted up to cross the "QT S53" values.
An exemplary embodiment (QT-SSC alloy) is predicted to achieve a
KISSC along the middle curve with a 140-160 ksi (965-1100 MPa)
yield strength. The upper curve is the bottom curve shifted up to
the KIC values of "QT S53" and "4340" (which are equivalent). Since
KISCC/KISSC is a fraction of KIC, the purple curve demonstrates the
effect of cohesion on bringing corrosion toughness from about 20%
of KIC (the bottom curve) to about 80% of KIC (the middle
curve).
[0008] FIG. 2 is a CALPHAD equilibrium step diagram of phase
fraction vs. temperature for an exemplary embodiment (QT-SSC
alloy).
[0009] FIG. 3 is a CALPHAD metastable step diagram of phase
fraction vs. temperature for an exemplary embodiment (QT-SSC
alloy).
[0010] FIG. 4 is a plot of hardness vs. aging temperature for
QT-SSC steel, one embodiment of the disclosed alloys.
DETAILED DESCRIPTION
[0011] Disclosed are high strength low alloy (HSLA) steels, methods
for making the alloys, and manufactured articles comprising the
alloys. The disclosed alloys can possess both improved processing
and physical properties over existing HSLA steels, such as improved
sulfide stress cracking toughness with increased yield strength,
making the alloys useful in extreme environments, such as those in
oil and gas applications.
[0012] The disclosed alloys have improved sulfide stress cracking
(SSC) toughness, reduced hydrogen embrittlement (HE), improved
corrosion resistance, and improved yield strength, relative to
existing HSLA steels (FIG. 1). These improved properties may be the
result of incorporating comparatively greater amounts of tungsten,
nickel, and copper in the alloys, which was discovered, in part,
due to the development of predictive models. Additionally, the
alloy was designed to implement a variety of strategies,
includingin conjunction with improved grain boundary
cohesionsurface scale formation, improved hydrogen trapping, slow
bulk/grain boundary hydrogen diffusion, and promotion of surface
H.sub.2 formation.
[0013] Improved grain boundary cohesion: Intergranular fracture may
be a primary SSC mode in high yield strength steels. The occurrence
of intergranular fracture may be reduced by improving the grain
boundary cohesion with alloying additions. The change in grain
boundary cohesion due to alloying (.DELTA.2.gamma. in J/m.sup.2) is
quantified by the Rice-Wang model (Rice, J. R.; Wang, J. S.
Materials Science and Engineering, A107 (1989) 23-40):
.DELTA.2.gamma. = i .GAMMA. i E i pot , ( eq . 1 ) ##EQU00001##
where E.sub.i.sup.pot is the embrittling potency of element i and
.GAMMA..sub.i is the grain boundary composition of element i. Lower
(more negative) values of .DELTA.2.gamma. indicate a stronger
cohesion between grains and a greater resistance to intergranular
cracking by SSC. The grain boundary composition is predicted by the
McLean Gibbs isotherm (McLean, D. Grain boundaries in metals,
London: Oxford University Press; 1957):
.GAMMA. i 1 - .GAMMA. i = x i Matrix exp ( - E i GB RT ) , ( eq . 2
) ##EQU00002##
where x.sub.i.sup.Matrix is the alloy matrix composition
(calculated with CALPHAD and internal thermodynamic databases),
E.sub.GB.sup.i is the grain boundary segregation energy for element
i, R is the gas constant, and T is absolute temperature. See
"Segregation-induced changes in grain boundary cohesion and
embrittlement in binary alloys" by Gibson and Schuh, Acta
Materialia 95 (2015) 145-155 and "Designing Strength, Toughness,
and Hydrogen Resistance: Quantum Steel" a dissertation by Kantner,
Northwestern University (2002), each of which is herein
incorporated by reference.
[0014] Grain boundary cohesion was accomplished in the disclosed
alloys by specific alloying additions that both segregate to the
matrix grain boundary (E.sub.GB.sup.i<0) and improve cohesion
(E.sub.i.sup.pot<0). Tungsten was found to be a particularly
potent cohesion enhancing element, and the tungsten content of the
disclosed alloys is unique compared to existing alloys. Boron was
also found to be a potent cohesion enhancing element, and a
significant amount of boron can be incorporated to be present at
the grain boundaries of the disclosed alloys.
[0015] Surface scale formation: Absorption of H into the alloy may
promote SSC failure. Therefore, modification of surface chemistry
to promote the formation of protective surface scales may slow
corrosion and H absorption. Scales may be made from oxides,
sulfides, or other p-block elements.
[0016] Effects of copper alloying: The addition of copper in the
disclosed alloys may provide BCC copper precipitates and copper in
the grain boundary, which can strengthen the alloy, alter scale
formation, and promote H.sub.2 recombination at the surface.
[0017] Improved hydrogen trapping: SSC may occur when hydrogen
collects at grain boundaries. Therefore, impeding hydrogen
diffusion by trapping hydrogen at precipitate interfaces may reduce
intergranular SSC. Modification of the alloy chemistry to promote
carbide and other precipitate formation with particular morphology
(e.g., fine homogenously dispersed globular carbides) may decrease
SSC in the alloys. Accordingly, the disclosed alloys may possess a
large volume fraction of M.sub.2C carbide, and heat treatment can
ensure a fine, homogeneous carbide dispersion.
[0018] Slow bulk/grain boundary hydrogen diffusion: Hydrogen may
diffuse through alloys in sufficient quantity and speed to promote
cracking. However, the disclosed alloy compositions may slow
diffusion of hydrogen in the bulk and along grain boundaries.
[0019] Promotion of surface H.sub.2 formation: Sulfides may poison
the steel surface hydrogen recombination reaction, greatly
increasing the steel-absorbed H content. Therefore, modification of
surface chemistry may promote the recombination of the adsorbed H
into H.sub.2 gas that evolves away from the surface. Introduction
of alloying elements that lower the hydrogen overvoltage (acting as
effective cathodic sites) may enhance the hydrogen recombination
process.
[0020] A representative composition of the disclosed alloys (alloy
QT-SSC) is summarized in Table 1. The table describes the nominal
composition of elements in weight and atomic percentages. In
addition, the matrix and grain boundary compositions are calculated
to have the values listed in Table 1 at 500.degree. C. (an example
temperature).
TABLE-US-00001 TABLE 1 Ni W Cu Cr V C Ti B Fe Nominal Comp 6.5 4
2.5 0.5 0.1 0.1 0.02 0.0015 balance (wt %) Nominal Comp 6.38 1.25
2.26 0.55 0.11 0.48 0.024 0.008 (atomic %) Matrix Comp 6.66 0.058
0.13 0.19 0.015 0.01 0 0.0075 (atomic %) Grain Boundary 52.1 4.65
10.3 0.51 0.063 2.09 0 89.18 Comp (atomic %)
[0021] In addition, the alloy is calculated to have a
.DELTA.2.gamma. value of -2.64 J/m.sup.2, an M.sub.2C phase
fraction of 0.0129, and a BCC copper phase fraction of 0.0295.
Also, a CALPHAD equilibrium step diagram of phase fraction vs.
temperature (FIG. 2), and a CALPHAD metastable step diagram of
phase fraction vs. temperature (FIG. 3) of the disclosed alloy were
generated. As shown in Table 2, QT-SSC has a significantly lower
calculated .DELTA.2.gamma. value compared to prior art alloys,
indicating superior predicted SSC resistance.
TABLE-US-00002 TABLE 2 Source Name C Si Mn P S Cr Mo Cu Ni W V Nb
Al N Ti B .DELTA.2.gamma. Delattre et al. 2011 A 0.43 0.79 0.01
0.003 0.5 1.46 0.64 0.2 0.019 0.03 0.0045 0.002 0.0005 -1.47
Delattre et al. 2011 B 0.34 0.36 0.39 0.011 0.003 0.49 1.29 0.52
0.1 0.021 0.02 0.0023 0.002 0.0005 -1.48 Delattre et al. 2011 C
0.33 0.37 0.38 0.011 0.003 0.93 1.5 0.008 0.05 0.081 0.02 0.0031
0.009 0.0012 -1.57 Turconi et al. 2012 13C 0.25 ? 0.41 0.98 0.71
0.024 ? ? ? -1.47 Turconi et al. 2012 14 0.25 ? 0.26 0.5 0.74 0.023
? ? ? -1.58 Turconi et al. 2012 15 0.25 ? 0.19 0.5 0.74 0.15 0.022
? ? ? -1.60 Turconi et al. 2012 16 0.24 ? 0.2 0.51 0.73 0.053 ? ? ?
-1.68 Turconi et al. 2012 17 0.25 ? 0.2 0.53 0.73 0.021 0.031 0.031
? ? ? -1.65 QT-SSC 0.1 0.5 2.5 6.5 4 0.1 0.02 0.0015 -2.64
I. Definitions of Terms
[0022] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art. In case of conflict, the present
document, including definitions, will control. Preferred methods
and materials are described below, although methods and materials
similar or equivalent to those described herein can be used in
practice or testing of the present invention. All publications,
patent applications, patents, and other references mentioned herein
are incorporated by reference in their entirety. The materials,
methods, and examples disclosed herein are illustrative only and
not intended to be limiting.
[0023] The term "solvus," as used herein, may refer to a line
(binary system) or surface (ternary system) on a phase diagram
which separates a homogeneous solid solution from a field of
several phases which may form by exsolution or incongruent
melting.
[0024] The term "solidus," as used herein, may refer to the
temperature below which a mixture is completely solid.
[0025] The term "liquidus," as used herein, may refer to the
temperature above which a material is completely liquid, and the
maximum temperature at which crystals can co-exist with the melt in
thermodynamic equilibrium.
[0026] As used in the specification and the appended claims, the
singular forms "a," "an," and "the" include plural references
unless the context clearly dictates otherwise. The terms
"comprise(s)," "include(s)," "having," "has," "can," "contain(s),"
and variants thereof, as used herein, are intended to be open-ended
transitional phrases, terms, or words that do not preclude the
possibility of additional acts or structures. The present
disclosure also contemplates other embodiments "comprising,"
"consisting of" and "consisting essentially of" the embodiments or
elements presented herein, whether explicitly set forth or not.
[0027] The conjunctive term "or" includes any and all combinations
of one or more listed elements associated by the conjunctive term.
For example, the phrase "an apparatus comprising A or B" may refer
to an apparatus including A where B is not present, an apparatus
including B where A is not present, or an apparatus where both A
and B are present. The phrases "at least one of A, B, . . . and N"
or "at least one of A, B, . . . N, or combinations thereof" are
defined in the broadest sense to mean one or more elements selected
from the group comprising A, B, . . . and N, that is to say, any
combination of one or more of the elements A, B, . . . or N
including any one element alone or in combination with one or more
of the other elements which may also include, in combination,
additional elements not listed.
[0028] The modifier "about" used in connection with a quantity is
inclusive of the stated value and has the meaning dictated by the
context (for example, it includes at least the degree of error
associated with the measurement of the particular quantity). The
modifier "about" should also be considered as disclosing the range
defined by the absolute values of the two endpoints. For example,
the expression "from about 2 to about 4" also discloses the range
"from 2 to 4." The term "about" may refer to plus or minus 10% of
the indicated number. For example, "about 10%" may indicate a range
of 9% to 11%, and "about 1" may mean from 0.9-1.1. Other meanings
of "about" may be apparent from the context, such as rounding off,
so, for example "about 1" may also mean from 0.5 to 1.4.
[0029] Any recited range described herein is to be understood to
encompass and include all values within that range, without the
necessity for an explicit recitation.
I. Alloys
[0030] The disclosed alloys may comprise nickel, tungsten, copper,
chromium, vanadium, carbon, titanium, boron, silicon, calcium, and
iron, along with incidental elements and impurities.
[0031] The alloys may comprise, by weight, about 0% to about 8%
nickel, about 1% to about 6% tungsten, about 1% to about 4% copper,
about 0.1% to about 2% chromium, about 0.01% to about 1% vanadium,
about 0.01% to about 0.5% carbon, about 0.01% to about 0.1%
titanium, about 0.001% to about 0.01% boron, about 0% to about 1%
silicon, and about 0% to about 0.1% calcium, the balance
essentially iron and incidental elements and impurities. It is
understood that the alloys described herein may consist only of the
above-mentioned constituents or may consist essentially of such
constituents, or in other embodiments, may include additional
constituents.
[0032] The alloys may comprise, by weight, about 0.5% to about 7.5%
nickel, about 2% to about 5% tungsten, about 1.5% to about 3.5%
copper, about 0.1% to about 1.5% chromium, about 0.01% to about
0.5% vanadium, about 0.01% to about 0.3% carbon, about 0.01% to
about 0.075% titanium, about 0.001% to about 0.005% boron, about 0%
to about 0.5% silicon, and about 0% to about 0.075% calcium, the
balance essentially iron and incidental elements and impurities. It
is understood that the alloys described herein may consist only of
the above-mentioned constituents or may consist essentially of such
constituents, or in other embodiments, may include additional
constituents.
[0033] The alloys may comprise, by weight, about 1% to about 7%
nickel, about 2.5% to about 4.5% tungsten, about 2% to about 3%
copper, about 0.1% to about 1% chromium, about 0.01% to about 0.2%
vanadium, about 0.01% to about 0.2% carbon, about 0.01% to about
0.05% titanium, about 0.001% to about 0.002% boron, about 0% to
about 0.2% silicon, and about 0% to about 0.05% calcium, the
balance essentially iron and incidental elements and impurities. It
is understood that the alloys described herein may consist only of
the above-mentioned constituents or may consist essentially of such
constituents, or in other embodiments, may include additional
constituents.
[0034] The alloys may comprise, by weight, about 6.3% to about 6.7%
nickel, about 3.8% to about 4.2% tungsten, about 2.3% to about 2.7%
copper, about 0.3% to about 0.7% chromium, about 0.08% to about
0.12% vanadium, about 0.08% to about 0.12% carbon, about 0.01% to
about 0.03% titanium, about 0.0013% to about 0.0017% boron, about
0% to about 0.02% silicon, and about 0% to about 0.02% calcium, the
balance essentially iron and incidental elements and impurities. It
is understood that the alloys described herein may consist only of
the above-mentioned constituents or may consist essentially of such
constituents, or in other embodiments, may include additional
constituents.
[0035] The alloys may comprise, by weight, about 0% to about 8%
nickel, about 0% to about 7% nickel, about 0% to about 6% nickel,
about 0% to about 5% nickel, about 0% to about 4% nickel, about 0%
to about 3% nickel, about 0% to about 2% nickel, about 0% to about
1% nickel, about 0% to about 0.5% nickel, about 0.5% to about 8%
nickel, about 0.5% to about 7% nickel, about 0.5% to about 6%
nickel, about 0.5% to about 5% nickel, about 0.5% to about 4%
nickel, about 0.5% to about 3% nickel, about 0.5% to about 2%
nickel, about 0.5% to about 1% nickel, about 1% to about 8% nickel,
about 1% to about 7% nickel, about 1% to about 6% nickel, about 1%
to about 5% nickel, about 1% to about 4% nickel, about 1% to about
3% nickel, about 1% to about 2% nickel, about 2% to about 8%
nickel, about 2% to about 7% nickel, about 2% to about 6% nickel,
about 2% to about 5% nickel, about 2% to about 4% nickel, about 2%
to about 3% nickel, about 3% to about 8% nickel, about 3% to about
7% nickel, about 3% to about 6% nickel, about 3% to about 5%
nickel, about 3% to about 4% nickel, about 4% to about 8% nickel,
about 4% to about 7% nickel, about 4% to about 6% nickel, about 4%
to about 5% nickel, about 5% to about 8% nickel, about 5% to about
7% nickel, about 5% to about 6% nickel, about 6% to about 8%
nickel, about 6% to about 7% nickel, and about 7% to about 8%
nickel. The alloys may comprise, by weight, 0%, 0.5%, 1%, 1.5%, 2%,
2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, or 8%
nickel. The alloys may comprise, by weight, about 0% nickel, about
0.5% nickel, about 1% nickel, about 1.5% nickel, about 2% nickel,
about 2.5% nickel, about 3% nickel, about 3.5% nickel, about 4%
nickel, about 4.5% nickel, about 5% nickel, about 5.5% nickel,
about 6% nickel, about 6.5% nickel, about 7% nickel, about 7.5%
nickel, or about 8% nickel.
[0036] The alloys may comprise, by weight, about 1% to about 6%
tungsten, about 1% to about 5% tungsten, about 1% to about 4%
tungsten, about 1% to about 3% tungsten, about 1% to about 2%
tungsten, about 1% to about 1.5% tungsten, about 1.5% to about 6%
tungsten, about 1.5% to about 5% tungsten, about 1.5% to about 4%
tungsten, about 1.5% to about 3% tungsten, about 1.5% to about 2%
tungsten, about 2% to about 6% tungsten, about 2% to about 5%
tungsten, about 2% to about 4% tungsten, about 2% to about 3%
tungsten, about 3% to about 6% tungsten, about 3% to about 5%
tungsten, about 3% to about 4% tungsten, about 4% to about 6%
tungsten, about 4% to about 5% tungsten, or about 5% to about 6%
tungsten. The alloys may comprise, by weight, 1%, 1.5%, 1.6%, 1.7%,
1.8%, 1.9%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, or 6.degree. A
tungsten. The alloys may comprise, by weight, about 1% tungsten,
about 1.5% tungsten, about 1.6% tungsten, about 1.7% tungsten,
about 1.8% tungsten, about 1.9% tungsten, about 2% tungsten, about
2.5% tungsten, about 3% tungsten, about 3.5% tungsten, about 4%
tungsten, about 4.5% tungsten, about 5% tungsten, about 5.5%
tungsten, or about 6% tungsten.
[0037] The alloys may comprise, by weight, about 1% to about 4%
copper, about 1% to about 3% copper, about 1% to about 2% copper,
about 2% to about 4% copper, about 2% to about 3% copper, or about
3% to about 4% copper. The alloys may comprise, by weight, 1%,
1.5%, 2%, 2.5%, 3%, 3.5%, or 4% copper. The alloys may comprise, by
weight, about 1% copper, about 1.5% copper, about 2% copper, about
2.5% copper, about 3% copper, about 3.5% copper, or about 4%
copper.
[0038] The alloys may comprise, by weight, about 0.1% to about 2%
chromium, about 0.1% to about 1.5% chromium, about 0.1% to about 1%
chromium, about 0.1% to about 0.5% chromium, about 0.5% to about 2%
chromium, about 0.5% to about 1.5% chromium, about 0.5% to about 1%
chromium, about 1% to about 2% chromium, about 1% to about 1.5%
chromium, or about 1.5% to about 2% chromium. The alloys may
comprise, by weight, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%,
0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%,
1.9%, or 2% chromium. The alloys may comprise, by weight, about
0.1% chromium, about 0.2% chromium, about 0.3% chromium, about 0.4%
chromium, about 0.5% chromium, about 0.6% chromium, about 0.7%
chromium, about 0.8% chromium, about 0.9% chromium, about 1%
chromium, about 1.1% chromium, about 1.2% chromium, about 1.3%
chromium, about 1.4% chromium, about 1.5% chromium, about 1.6%
chromium, about 1.7% chromium, about 1.8% chromium, about 1.9%
chromium, or about 2% chromium.
[0039] The alloys may comprise, by weight, about 0.01% to about 1%
vanadium, about 0.01% to about 0.8% vanadium, about 0.01% to about
0.6% vanadium, about 0.01% to about 0.4% vanadium, about 0.01% to
about 0.2% vanadium, about 0.01% to about 0.1% vanadium, about
0.01% to about 0.05% vanadium, about 0.05% to about 1% vanadium,
about 0.05% to about 0.8% vanadium, about 0.05% to about 0.6%
vanadium, about 0.05% to about 0.4% vanadium, about 0.05% to about
0.2% vanadium, about 0.05% to about 0.1% vanadium, about 0.1% to
about 1% vanadium, about 0.1% to about 0.8% vanadium, about 0.1% to
about 0.6% vanadium, about 0.1% to about 0.4% vanadium, about 0.1%
to about 0.2% vanadium, about 0.2% to about 1% vanadium, about 0.2%
to about 0.8% vanadium, about 0.2% to about 0.6% vanadium, about
0.2% to about 0.4% vanadium, about 0.4% to about 1% vanadium, about
0.4% to about 0.8% vanadium, about 0.4% to about 0.6% vanadium,
about 0.6% to about 1% vanadium, about 0.6% to about 0.8% vanadium,
or about 0.8% to about 1% vanadium. The alloys may comprise, by
weight, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%,
0.09%, 0.1%, 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%,
or 1% vanadium. The alloys may comprise, by weight, about 0.01%
vanadium, about 0.02% vanadium, about 0.03% vanadium, about 0.04%
vanadium, about 0.05% vanadium, about 0.1% vanadium, about 0.2%
vanadium, about 0.3% vanadium, about 0.4% vanadium, about 0.5%
vanadium, about 0.6% vanadium, about 0.7% vanadium, about 0.8%
vanadium, about 0.9% vanadium, or about 1% vanadium.
[0040] The alloys may comprise, by weight, about 0.01% to about
0.5% carbon, about 0.01% to about 0.4% carbon, about 0.01% to about
0.3% carbon, about 0.01% to about 0.2% carbon, about 0.01% to about
0.1% carbon, about 0.1% to about 0.5% carbon, about 0.1% to about
0.4% carbon, about 0.1% to about 0.3% carbon, about 0.1% to about
0.2% carbon, about 0.2% to about 0.5% carbon, about 0.2% to about
0.4% carbon, about 0.2% to about 0.3% carbon, about 0.3% to about
0.5% carbon, about 0.3% to about 0.4% carbon, or about 0.4% to
about 0.5% carbon. The alloys may comprise, by weight, 0.01%,
0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%
carbon. The alloys may comprise, by weight, about 0.01% carbon,
about 0.05% carbon, about 0.1% carbon, about 0.15% carbon, about
0.2% carbon, about 0.25% carbon, about 0.3% carbon, about 0.35%
carbon, about 0.4% carbon, about 0.45% carbon, or about 0.5%
carbon.
[0041] The alloys may comprise, by weight, about 0.01% to about
0.1% titanium, about 0.01% to about 0.075% titanium, about 0.01% to
about 0.05% titanium, about 0.01% titanium to about 0.025%
titanium, about 0.025% to about 0.1% titanium, about 0.025% to
about 0.075% titanium, about 0.025% to about 0.05% titanium, about
0.05% to about 0.1% titanium, about 0.05% to about 0.075% titanium,
or about 0.075% to about 0.1% titanium. The alloys may comprise, by
weight, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%,
0.09%, or 0.1% titanium. The alloys may comprise, by weight, about
0.01% titanium, about 0.02% titanium, about 0.03% titanium, about
0.04% titanium, about 0.05% titanium, about 0.06% titanium, about
0.07% titanium, about 0.08% titanium, about 0.09% titanium, or
about 0.1% titanium.
[0042] The alloys may comprise, by weight, about 0.001% to about
0.01% boron, about 0.001% to about 0.0075% boron, about 0.001% to
about 0.005% boron, about 0.001% to about 0.0025% boron, about
0.0025% to about 0.01% boron, about 0.0025% to about 0.0075% boron,
about 0.0025% to about 0.005% boron, about 0.005% to about 0.01%
boron, about 0.005% to about 0.0075% boron, or about 0.0075% to
about 0.01% boron. The alloys may comprise, by weight, 0.001%,
0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, or
0.01% boron. The alloys may comprise, by weight, about 0.001%
boron, about 0.002% boron, about 0.003% boron, about 0.004% boron,
about 0.005% boron, about 0.006% boron, about 0.007% boron, about
0.008% boron, about 0.009% boron, or about 0.01% boron.
[0043] The alloys may comprise, by weight, about 0% to about 1%
silicon, about 0% to about 0.75% silicon, about 0% to about 0.5%
silicon, about 0% to about 0.25% silicon, about 0.25% to about 1%
silicon, about 0.25% to about 0.75% silicon, about 0.25% to about
0.5% silicon, about 0.5% to about 1% silicon, about 0.5% to about
0.75% silicon, or about 0.75% to about 1% silicon. The alloys may
comprise, by weight, 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%,
0.8%, 0.9%, or 1% silicon. The alloys may comprise, by weight,
about 0% silicon, about 0.1% silicon, about 0.2% silicon, about
0.3% silicon, about 0.4% silicon, about 0.5% silicon, about 0.6%
silicon, about 0.7% silicon, about 0.8% silicon, about 0.9%
silicon, or about 1% silicon.
[0044] The alloys may comprise, by weight, about 0% to about 0.1%
calcium, about 0% to about 0.075% calcium, about 0% to about 0.05%
calcium, about 0% to about 0.025% calcium, about 0.025% to about
0.1% calcium, about 0.025% to about 0.075% calcium, about 0.025% to
about 0.05% calcium, about 0.05% to about 0.1% calcium, about 0.05%
to about 0.075% calcium, or about 0.075% to about 0.1% calcium. The
alloys may comprise, by weight, 0%, 0.01%, 0.02%, 0.03%, 0.04%,
0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1% calcium. The alloys may
comprise, by weight, about 0% calcium, about 0.01% calcium, about
0.02% calcium, about 0.03% calcium, about 0.04% calcium, about
0.05% calcium, about 0.06% calcium, about 0.07% calcium, about
0.08% calcium, about 0.09% calcium, or about 0.1% calcium.
[0045] In one embodiment, the alloys comprise, by weight, about
6.5% nickel, about 4.5% tungsten, about 2.5% copper, about 0.5%
chromium, about 0.1% vanadium, about 0.1% carbon, about 0.02%
titanium, about 0.0015% boron, about 0% silicon, and about 0%
calcium, the balance essentially iron and incidental elements and
impurities.
[0046] The alloys may comprise, by weight, a balance of iron and
incidental elements and impurities. The term "incidental elements
and impurities," may include one or more of niobium, ruthenium,
lanthanum, zirconium, manganese, cerium, magnesium, and
nitrogen.
[0047] The incidental elements and impurities may include one or
more of niobium (e.g., maximum 2%), ruthenium (e.g., maximum 2%),
lanthanum (e.g., maximum 2%), zirconium (e.g., maximum 2%),
manganese (e.g., maximum 2%), cerium (e.g., maximum 2%), magnesium
(e.g., maximum 2%), and nitrogen (e.g., maximum 0.02%).
[0048] The alloys may comprise, by weight, 6.5% nickel, 4.5%
tungsten, 2.5% copper, 0.5% chromium, 0.1% vanadium, 0.1% carbon,
0.02% titanium, 0.0015% boron, 0% silicon, and 0% calcium, the
balance essentially iron and incidental elements and impurities.
The incidental elements and impurities may include one or more of
niobium (e.g., maximum 2%), ruthenium (e.g., maximum 2%), lanthanum
(e.g., maximum 2%), zirconium (e.g., maximum 2%), manganese (e.g.,
maximum 2%), copper (e.g., maximum 2%), vanadium (e.g., maximum
2%), cerium (e.g., maximum 2%), magnesium (e.g., maximum 2%), and
nitrogen (e.g., maximum 0.02%).
[0049] The alloys may consist of, by weight, 6.5% nickel, 4.5%
tungsten, 2.5% copper, 0.5% chromium, 0.1% vanadium, 0.1% carbon,
0.02% titanium, 0.0015% boron, 0% silicon, and 0% calcium, the
balance essentially iron and incidental elements and impurities.
The incidental elements and impurities may include one or more of
niobium (e.g., maximum 2%), ruthenium (e.g., maximum 2%), lanthanum
(e.g., maximum 2%), zirconium (e.g., maximum 2%), manganese (e.g.,
maximum 2%), copper (e.g., maximum 2%), vanadium (e.g., maximum
2%), cerium (e.g., maximum 2%), magnesium (e.g., maximum 2%), and
nitrogen (e.g., maximum 0.02%).
[0050] The alloys may have a 42y value of about -4 J/m.sup.2 to
about 0 J/m.sup.2, about -4 J/m.sup.2 to about -1 J/m.sup.2, about
-4 J/m.sup.2 to about -2 J/m.sup.2, about -3 J/m.sup.2 to about -2
J/m.sup.2, about -3 J/m.sup.2 to about -1 J/m.sup.2, about -3
J/m.sup.2 to about 0 J/m.sup.2, or about -2.8 J/m.sup.2to about
-2.5 J/m.sup.2. The alloys may have a .DELTA.2.gamma. value of less
than or equal to 0 J/m.sup.2, less than or equal to -0.5 J/m.sup.2,
less than or equal to -1 J/m.sup.2, less than or equal to -1.5
J/m.sup.2, less than or equal to -2 J/m.sup.2, less than or equal
to -2.1 J/m.sup.2, less than or equal to -2.2 J/m.sup.2, less than
or equal to -2.3 J/m.sup.2, less than or equal to -2.4 J/m.sup.2,
less than or equal to -2.5 J/m.sup.2, less than or equal to -2.6
J/m.sup.2, less than or equal to -2.7 J/m.sup.2, less than or equal
to -2.8 J/m.sup.2, less than or equal to -2.9 J/m.sup.2, or less
than or equal to -3 J/m.sup.2. The alloys may have a
.DELTA.2.gamma. value of 0 J/m.sup.2, -0.5 J/m.sup.2, -1 J/m.sup.2,
-1.5 J/m.sup.2, -2 J/m.sup.2, -2.1 J/m.sup.2, -2.2 J/m.sup.2, -2.3
J/m.sup.2, -2.4 J/m.sup.2, -2.5 J/m.sup.2, -2.6 J/m.sup.2, -2.64
J/m.sup.2, -2.7 J/m.sup.2, -2.8 J/m.sup.2, -2.9 J/m.sup.2, -3
J/m.sup.2, -3.1 J/m.sup.2, -3.2 J/m.sup.2, -3.3 J/m.sup.2, -3.4
J/m.sup.2, -3.5 J/m.sup.2, or -4 J/m.sup.2. The alloys may have a
.DELTA.2.gamma. value of about 0 J/m.sup.2, about -0.5 J/m.sup.2,
about -1 J/m.sup.2, about -1.5 J/m.sup.2, about -2 J/m.sup.2, about
-2.5 J/m.sup.2, about -2.64 J/m.sup.2, about -3 J/m.sup.2, about
-3.5 J/m.sup.2, or about -4 J/m.sup.2.
[0051] The alloys may have a yield strength of about 800 MPa to
about 1300 MPa, about 800 MPa to about 1200 MPa, about 800 MPa to
about 1100 MPa, about 900 MPa to about 1100 MPa, or about 965 MPa
to about 1100 MPa. The alloys may have a yield strength of greater
than or equal to 800 MPa, greater than or equal to 825 MPa, greater
than or equal to 850 MPa, greater than or equal to 875 MPa, greater
than or equal to 900 MPa, greater than or equal to 925 MPa, greater
than or equal to 950 MPa, greater than or equal to 975 MPa, greater
than or equal to 1000 MPa, greater than or equal to 1025 MPa,
greater than or equal to 1050 MPa, greater than or equal to 1075
MPa, greater than or equal to 1100 MPa, greater than or equal to
1150 MPa, greater than or equal to 1200 MPa, greater than or equal
to 1250 MPa, or greater than or equal to 1300 MPa. The alloys may
have a yield strength of 800 MPa, 810 MPa, 820 MPa, 830 MPa, 840
MPa, 850 MPa, 860 MPa, 870 MPa, 880 MPa, 890 MPa, 900 MPa, 910 MPa,
920 MPa, 930 MPa, 940 MPa, 950 MPa, 960 MPa, 965 MPa, 970 MPa, 980
MPa, 990 MPa, 1000 MPa, 1010 MPa, 1020 MPa, 1030 MPa, 1040 MPa,
1050 MPa, 1060 MPa, 1070 MPa, 1080 MPa, 1090 MPa, 1100 MPa, 1150
MPa, 1200 MPa, 1250 MPa, or 1300 MPa. The alloys may have a yield
strength of about 800 MPa, about 900 MPa, about 1000 MPa, about
1100 MPa, about 1200 MPa, or about 1300 MPa. The yield strength may
be measured according to ASTM E8 or ASTM E21.
[0052] The alloys may have a sulfide stress corrosion cracking
toughness (K1SSC) value of about 30 MPa*m.sup.1/2 to about 60
MPa*m.sup.1/2, about 40 MPa*m.sup.1/2 to about 60 MPa*m.sup.1/2,
about 50 MPa*m.sup.1/2 to about 60 MPa*m.sup.1/2, about 40
MPa*m.sup.1/2 to about 50 MPa*m.sup.1/2, or about 40 MPa*m.sup.1/2
to about 45 MPa*m.sup.1/2. The alloys may have a sulfide stress
corrosion cracking toughness (K1SSC) value of greater than or equal
to 30 MPa*m.sup.1/2, greater than or equal to 33 MPa*m.sup.1/2,
greater than or equal to 35 MPa*m.sup.1/2, greater than or equal to
38 MPa*m.sup.1/2, greater than or equal to 40 MPa*m.sup.1/2,
greater than or equal to 43 MPa*m.sup.1/2, greater than or equal to
45 MPa*m.sup.1/2, greater than or equal to 48 MPa*m.sup.1/2,
greater than or equal to 50 MPa*m.sup.1/2, greater than or equal to
55 MPa*m.sup.1/2, greater than or equal to 58 MPa*m.sup.1/2, or
greater than or equal to 60 MPa*m.sup.1/2. The alloys may have a
sulfide stress corrosion cracking toughness (K1SSC) value of 30
MPa*m.sup.1/2, 31 MPa*m.sup.1/2, 32 MPa*m.sup.1/2, 33
MPa*m.sup.1/2, 34 MPa*m.sup.1/2, 35 MPa*m.sup.1/2, 36
MPa*m.sup.1/2, 37 MPa*m.sup.1/2, 38 MPa*m.sup.1/2, 39
MPa*m.sup.1/2, 40 MPa*m.sup.1/2, 41 MPa*m.sup.1/2, 42
MPa*m.sup.1/2, 43 MPa*m.sup.1/2, 44 MPa*m.sup.1/2, 45
MPa*m.sup.1/2, 46 MPa*m.sup.1/2, 47 MPa*m.sup.1/2, 48
MPa*m.sup.1/2, 49 MPa*m.sup.1/2, 50 MPa*m.sup.1/2, 51
MPa*m.sup.1/2, 52 MPa*m.sup.1/2, 53 MPa*m.sup.1/2, 54
MPa*m.sup.1/2, 55 MPa*m.sup.1/2, 56 MPa*m.sup.1/2, 57
MPa*m.sup.1/2, 58 MPa*m.sup.1/2, 59 MPa*m.sup.1/2, or 60
MPa*m.sup.1/2. The alloys may have a sulfide stress corrosion
cracking toughness (K1SSC) value of about 30 MPa*m.sup.1/2, about
35 MPa*m.sup.1/2, about 40 MPa*m.sup.1/2, about 45 MPa*m.sup.1/2,
about 50 MPa*m.sup.1/2, about 55 MPa*m.sup.1/2, or about 60
MPa*m.sup.1/2.
[0053] The alloys may have an M.sub.2C phase fraction of about 0.01
to about 0.015, about 0.01 to about 0.013, or about 0.012 to about
0.013. The alloys may have an M.sub.2C phase fraction of 0.01,
0.011, 0.012, 0.0125, 0.0126, 0.0127, 0.0128, 0.0129, 0.013,
0.0131, 0.0132, 0.0133, 0.0134, 0.0135, 0.014, or 0.015. The alloys
may have an M.sub.2C phase fraction of about 0.01, about 0.011,
about 0.012, about 0.0129, about 0.013, about 0.014, or about
0.015.
[0054] In certain embodiments, M is selected from the group
consisting of Fe, Cr, Cu, Ni, W, V, and Ti, or any combination
thereof. In certain embodiments, M is selected from the group
consisting of Cr, W, V, and Ti, or any combination thereof. In
certain embodiments, M is selected from the group consisting of Cr,
W, and V, or any combination thereof.
[0055] The alloys may have a BCC copper phase fraction of about
0.025 to about 0.035, about 0.025 to about 0.033, about 0.025 to
about 0.03, about 0.027 to about 0.033, or about 0.027 to about
0.03. The alloys may have a body centered cubic copper phase
fraction of 0.025, 0.026, 0.027, 0.028, 0.029, 0.0295, 0.03, 0.031,
0.032, 0.033, 0.034, or 0.035. The alloys may have a body centered
cubic copper phase fraction of about 0.025, about 0.026, about
0.027, about 0.028, about 0.029, about 0.0295, about 0.03, about
0.031, about 0.032, about 0.033, about 0.034, or about 0.035.
II. Methods of Manufacture
[0056] Also disclosed are methods of manufacturing the disclosed
alloys. The alloys may be produced by vacuum melt practices or air
melt practices. Calcium or silicon may be added to the melt for the
purpose of decreasing impurities such as sulfur, phosphorous, or
nitrogen. Calcium or silicon may be added in minute quantities.
Additional titanium may be added to the melt for the purpose of
converting nitrogen to TiN. The alloys may be produced by methods
including, but not limited to, single melting, double melting,
casting, centrifugal casting, additive manufacturing, or powder
production.
[0057] A method for producing the disclosed alloys may include, but
are not limited to, steps such as preparing a melt, melting,
casting, homogenization, hot rolling, hot working, cold rolling,
cold working, solutionizing, quenching, quenching with oil,
cooling, subzero cooling, warming, aging, hardening, or softening.
These steps may be performed in a different order. These steps may
be performed more than once, in a cycle. Not all steps are
required. Other common preparation techniques and variations upon
the methods disclosed herein will be apparent to one of ordinary
skill in the art.
III. Articles of Manufacture
[0058] Also disclosed are manufactured articles including the
disclosed alloys. Exemplary manufactured articles include, but are
not limited to, steel pipes or tubes. The steel pipes or tubes may
be used in oil or gas drilling, extraction, transport, or other
services. The steel pipes or tubes may be formed by various
methods, including piercing followed by hot rolling, extruding,
forging, and other techniques, including those that form a tube or
a pipe with no seam.
IV. Examples
[0059] A steel alloy was prepared and tested for physical
properties. Table 3 shows the design and composition of the
exemplified alloy (QT-SSC).
TABLE-US-00003 TABLE 3 Nominal composition (weight percentage) of
exemplified alloy Ni W Cu Cr V C Ti B Fe QT-SSC 6.5 4 2.5 0.5 0.1
0.1 0.02 0.0015 balance
Example 1: QT-SSC
[0060] A melt was prepared with the nominal composition of 6.5 Ni,
4 W, 2.5 Cu, 0.5 Cr, 0.1 V, 0.1 C, 0.02 Ti, 0.0015 B, and balance
Fe, in wt %. From the melt, the QT-SSC alloy was prepared. Steel
was melted and cast by vacuum induction melting at a weight of
about 50 pounds. The steel was subjected to homogenization at
1204.degree. C. for 8 hours, and hot rolled from an initial 4 inch
round cross section to 0.75 inch by 2.75 inch plate. Test samples
of the QT-SSC alloy were excised from the hot rolled plate and
solutionized at 950.degree. C. for 1 hour, quenched with oil,
subzero cooled at -73.degree. C. for about 1 hour, and warmed in
air to room temperature.
[0061] In the as-solutionized state, the hardness of the QT-SSC
steel was measured at about 38 on the Rockwell C scale. Samples
were then subjected to isochronal aging heat treatments at
secondary hardening temperatures in the range of 450 and
625.degree. C. for 5 hours. As shown in FIG. 4, hardness was
increased by aging in the range of 450 to 550.degree. C., followed
by softening by over-aging at above 550.degree. C. Additional
testing of room temperature mechanical properties indicated a range
of achievable strength-toughness combinations with different aging
conditions, as shown in Table 4.
TABLE-US-00004 TABLE 4 % Hardness Aging UTS TYS % Reduction CVN
(Rockwell KIC KISCC Ratio Condition (ksi) (ksi) Elongation in Area
(ft-lb) C) (ksi in) (ksi in) K1SCC/K1C 450.degree. C./5 hr 190 170
16 53 26.5 41 103 -- 550.degree. C./5 hr 178 160 20 67 71 39 101
.gtoreq.90.7 .gtoreq.0.898 625.degree. C./5 hr 157 138 20 66 79.5
30 93 -- Test ASTM ASTM ASTM E8 ASTM E8 ASTM ASTM ASTM ASTM
Specification E8 E8 E23 E18 E399 F1624 Typical ~0.2-0.3
High-strength Steel
[0062] Aging at 550.degree. C. for 5 hours was shown to result in
an optimal balance between tensile yield strength and fracture
toughness for the exemplified alloy. The tensile yield strength in
this condition was about 160 ksi and ultimate tensile strength was
about 178 ksi. The ambient impact toughness in this condition was
about 71 ft-lb, and the plain strain fracture toughness was about
101 ksiIin. Stress corrosion cracking testing in accordance with
ASTM F1624 test methods indicated a fracture toughness of about
90.7 ksiIin in a 3.5% NaCl solution at an open circuit potential of
about -0.571 VSCE.
[0063] It is understood that the disclosure may embody other
specific forms without departing from the spirit or central
characteristics thereof. The disclosure of aspects and embodiments,
therefore, are to be considered in all respects as illustrative and
not restrictive, and the claims are not to be limited to the
details given herein. Accordingly, while specific embodiments have
been illustrated and described, numerous modifications come to mind
without significantly departing from the spirit of the invention
and the scope of protection is only limited by the scope of the
accompanying claims. Unless noted otherwise, all percentages listed
herein are weight percentages.
[0064] For reasons of completeness, various aspects of the present
disclosure are set out in the following numbered clauses:
[0065] Clause 1. An alloy comprising, by weight, about 0% to about
8% nickel, about 1% to about 6% tungsten, about 1% to about 4%
copper, about 0.1% to about 2% chromium, about 0.01% to about 1%
vanadium, about 0.01% to about 0.5% carbon, about 0.01% to about
0.1% titanium, about 0.001% to about 0.01% boron, about 0% to about
1% silicon, and about 0% to about 0.1% calcium, the balance
essentially iron and incidental elements and impurities.
[0066] Clause 2. The alloy of clause 1 comprising, by weight, about
6% to about 7% nickel, about 3.5% to about 4.5% tungsten, about 2%
to about 3% copper, about 0.1% to about 1% chromium, about 0.01% to
about 0.2% vanadium, about 0.01% to about 0.2% carbon, about 0.01%
to about 0.05% titanium, and about 0.001% to about 0.002% boron,
the balance essentially iron and incidental elements and
impurities.
[0067] Clause 3. The alloy of clause 1, wherein the alloy has a
calculated .DELTA.2.gamma. value of less than or equal to -2
J/m.sup.2.
[0068] Clause 4. The alloy of clause 1, wherein the alloy has a
yield strength of greater than or equal to 965 MPa (140 ksi),
measured according to ASTM E8.
[0069] Clause 5. The alloy of clause 1, wherein the alloy has a
sulfide stress corrosion cracking toughness (K1SSC) value of
greater than or equal to 44 MPa*m.sup.1/2 (40 ksi*in.sup.1/2).
[0070] Clause 6. The alloy of clause 1, wherein the alloy has an
M.sub.2C phase fraction of 0.01 to 0.015, wherein M is selected
from the group consisting of W, Cr, V, and Ti, or any combination
thereof.
[0071] Clause 7. The alloy of clause 1, wherein the alloy has a
body centered cubic copper phase fraction of 0.025 to 0.035.
[0072] Clause 8. The alloy of clause 1 comprising about 6.5%
nickel.
[0073] Clause 9. The alloy of clause 1 comprising about 4%
tungsten.
[0074] Clause 10. The alloy of clause 1 comprising about 2.5%
copper.
[0075] Clause 11. The alloy of clause 1 comprising about 0.5%
chromium.
[0076] Clause 12. The alloy of clause 1 comprising about 0.1%
vanadium.
[0077] Clause 13. The alloy of clause 1 comprising about 0.1%
carbon.
[0078] Clause 14. The alloy of clause 1 comprising about 0.02%
titanium.
[0079] Clause 15. The alloy of clause 1 comprising about 0.0015%
boron.
[0080] Clause 16. The alloy of clause 1 comprising, by weight,
about 6.5% nickel, about 4.5% tungsten, about 2.5% copper, about
0.5% chromium, about 0.1% vanadium, about 0.1% carbon, about 0.02%
titanium, and about 0.0015% boron, the balance essentially iron and
incidental elements and impurities.
[0081] Clause 17. A method for producing an alloy comprising:
preparing a melt that comprises, by weight, about 0% to about 8%
nickel, about 1% to about 6% tungsten, about 1% to about 4% copper,
about 0.1% to about 2% chromium, about 0.01% to about 1% vanadium,
about 0.01% to about 0.5% carbon, about 0.01% to about 0.1%
titanium, about 0.001% to about 0.01% boron, about 0% to about 1%
silicon, and about 0% to about 0.1% calcium, the balance
essentially iron and incidental elements and impurities.
[0082] Clause 18. The method of clause 17, wherein the melt
comprises, by weight, about 6% to about 7% nickel, about 3.5% to
about 4.5% tungsten, about 2% to about 3% copper, about 0.1% to
about 1% chromium, about 0.01% to about 0.2% vanadium, about 0.01%
to about 0.2% carbon, about 0.01% to about 0.05% titanium, and
about 0.001% to about 0.002% boron, the balance essentially iron
and incidental elements and impurities.
[0083] Clause 19. The method of clause 17, wherein the melt
comprises, by weight, about 6.5% nickel, about 4.5% tungsten, about
2.5% copper, about 0.5% chromium, about 0.1% vanadium, about 0.1%
carbon, about 0.02% titanium, and about 0.0015% boron, the balance
essentially iron and incidental elements and impurities.
[0084] Clause 20. The method of clause 17, wherein the alloy has a
calculated .DELTA.2.gamma. value of less than or equal to -2
J/m.sup.2.
[0085] Clause 21. The method of clause 17, wherein the alloy has a
yield strength of greater than or equal to 965 MPa (140 ksi),
measured according to ASTM E8.
[0086] Clause 22. The method of clause 17, wherein the alloy has a
sulfide stress corrosion cracking toughness (K1SSC) value of
greater than or equal to 44 MPa*m.sup.1/2 (40 ksi*in.sup.1/2).
[0087] Clause 23. The method of clause 17, wherein the alloy has an
M.sub.2C phase fraction of 0.01 to 0.015, wherein M is selected
from the group consisting of W, Cr, V, and Ti, or any combination
thereof.
[0088] Clause 24. The method of clause 17, wherein the alloy has a
body centered cubic copper phase fraction of 0.025 to 0.035.
[0089] Clause 25. The method of clause 17, wherein the alloy is
produced by vacuum melt or air melt practices.
[0090] Clause 26. A manufactured article comprising an alloy that
comprises, by weight, about 0% to about 8% nickel, about 1% to
about 6% tungsten, about 1% to about 4% copper, about 0.1% to about
2% chromium, about 0.01% to about 1% vanadium, about 0.01% to about
0.5% carbon, about 0.01% to about 0.1% titanium, about 0.001% to
about 0.01% boron, about 0% to about 1% silicon, and about 0% to
about 0.1% calcium, the balance essentially iron and incidental
elements and impurities.
[0091] Clause 27. The article of clause 26, wherein the alloy
comprises, by weight, about 6% to about 7% nickel, about 3.5% to
about 4.5% tungsten, about 2% to about 3% copper, about 0.1% to
about 1% chromium, about 0.01% to about 0.2% vanadium, about 0.01%
to about 0.2% carbon, about 0.01% to about 0.05% titanium, and
about 0.001% to about 0.002% boron, the balance essentially iron
and incidental elements and impurities.
[0092] Clause 28. The article of clause 26, wherein the alloy
comprises, by weight, about 6.5% nickel, about 4.5% tungsten, about
2.5% copper, about 0.5% chromium, about 0.1% vanadium, about 0.1%
carbon, about 0.02% titanium, and about 0.0015% boron, the balance
essentially iron and incidental elements and impurities.
[0093] Clause 29. The article of clause 26, wherein the alloy has a
calculated .DELTA.2.gamma. value of less than or equal to -2
J/m.sup.2.
[0094] Clause 30. The article of clause 26, wherein the alloy has a
yield strength of greater than or equal to 965 MPa (140 ksi),
measured according to ASTM E8.
[0095] Clause 31. The article of clause 26, wherein the alloy has a
sulfide stress corrosion cracking toughness (K1SSC) value of
greater than or equal to 44 MPa*m.sup.1/2 (40 ksi*in.sup.1/2).
[0096] Clause 32. The article of clause 26, wherein the alloy has
an M.sub.2C phase fraction of 0.01 to 0.015, wherein M is selected
from the group consisting of W, Cr, V, and Ti, or any combination
thereof.
[0097] Clause 33. The article of clause 26, wherein the alloy has a
body centered cubic copper phase fraction of 0.025 to 0.035.
[0098] Clause 34. The article of clause 26, wherein the article is
a steel pipe or steel tube.
* * * * *