U.S. patent application number 14/196010 was filed with the patent office on 2014-09-18 for enhanced wear resistant steel and methods of making the same.
This patent application is currently assigned to ExxonMobil Research and Engineering Company. The applicant listed for this patent is Raghavan Ayer, Jong-Kyo Choi, HyunWoo Jin, Hak-Cheol Lee, Ning Ma, Russell Robert Mueller, In-Shik Suh. Invention is credited to Raghavan Ayer, Jong-Kyo Choi, HyunWoo Jin, Hak-Cheol Lee, Ning Ma, Russell Robert Mueller, In-Shik Suh.
Application Number | 20140261918 14/196010 |
Document ID | / |
Family ID | 50391411 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140261918 |
Kind Code |
A1 |
Jin; HyunWoo ; et
al. |
September 18, 2014 |
ENHANCED WEAR RESISTANT STEEL AND METHODS OF MAKING THE SAME
Abstract
Improved steel compositions and methods of making the same are
provided. The present disclosure provides advantageous wear
resistant steel. More particularly, the present disclosure provides
high manganese (Mn) steel having enhanced wear resistance, and
methods for fabricating high manganese steel compositions having
enhanced wear resistance. The advantageous steel
compositions/components of the present disclosure improve one or
more of the following properties: wear resistance, ductility, crack
resistance, erosion resistance, fatigue life, surface hardness,
stress corrosion resistance, fatigue resistance, and/or
environmental cracking resistance. In general, the present
disclosure provides high manganese steels tailored to resist wear
and/or erosion.
Inventors: |
Jin; HyunWoo; (Easton,
PA) ; Ma; Ning; (Whitehouse Station, NJ) ;
Ayer; Raghavan; (Basking Ridge, NJ) ; Mueller;
Russell Robert; (Washington, NJ) ; Lee;
Hak-Cheol; (Pohang-si, KR) ; Choi; Jong-Kyo;
(Pohang-si, KR) ; Suh; In-Shik; (Pohang-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Jin; HyunWoo
Ma; Ning
Ayer; Raghavan
Mueller; Russell Robert
Lee; Hak-Cheol
Choi; Jong-Kyo
Suh; In-Shik |
Easton
Whitehouse Station
Basking Ridge
Washington
Pohang-si
Pohang-si
Pohang-si |
PA
NJ
NJ
NJ |
US
US
US
US
KR
KR
KR |
|
|
Assignee: |
ExxonMobil Research and Engineering
Company
Annandale
NJ
|
Family ID: |
50391411 |
Appl. No.: |
14/196010 |
Filed: |
March 4, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61790274 |
Mar 15, 2013 |
|
|
|
Current U.S.
Class: |
148/620 ;
148/325; 148/327; 148/329; 148/330; 148/332; 148/333; 148/336;
148/337; 148/609; 148/621; 148/654 |
Current CPC
Class: |
C21D 6/005 20130101;
G01N 17/046 20130101; C21D 9/08 20130101; C22C 38/02 20130101; C22C
38/20 20130101; C21D 9/44 20130101; C21D 8/005 20130101; C22C 38/06
20130101; C22C 38/38 20130101; C22C 38/04 20130101 |
Class at
Publication: |
148/620 ;
148/621; 148/654; 148/609; 148/329; 148/337; 148/325; 148/327;
148/333; 148/336; 148/332; 148/330 |
International
Class: |
C22C 38/38 20060101
C22C038/38; C22C 38/02 20060101 C22C038/02; C22C 38/06 20060101
C22C038/06; C21D 8/00 20060101 C21D008/00; C22C 38/20 20060101
C22C038/20 |
Claims
1. A method for fabricating a ferrous based component comprising:
a) providing a composition having from about 5 to about 40 weight %
manganese, from about 0.01 to about 3.0 weight % carbon, and the
balance iron; b) heating the composition to a temperature above the
austenite recrystallization stop temperature of the composition or
to a temperature to homogenize the composition; c) cooling the
composition to a rolling start temperature; d) deforming the
composition while the composition is at a temperature below the
austenite recrystallization stop temperature of the composition;
and e) quenching the composition.
2. The method of claim 1, wherein step c includes cooling to a
temperature below the T.sub.nr temperature.
3. The method of claim 1, wherein after step e), the carbide
precipitate fraction volume of the composition is about 5 volume %
or less of the composition.
4. The method of claim 1, wherein after step e), the composition
has a microstructure having a refined grain size of about 100 .mu.m
or less.
5. The method of claim 4, wherein the microstructure having a
refined grain size of about 100 .mu.m or less includes a surface
layer of the composition.
6. The method of claim 5, wherein the thickness of the surface
layer is from about 10 nm to about 5000 nm.
7. The method of claim 5, wherein the surface layer is formed prior
to or during use of the composition.
8. The method of claim 5, wherein the surface layer is comprised of
predominantly the austenite phase.
9. The method of claim 5, wherein the surface layer is formed via a
surface deformation technique selected from the group consisting of
shot peening, laser shock peening, surface burnishing and
combinations thereof.
10. The method of claim 1, further comprising after step e) a
surface deformation step selected from the group consisting of shot
peening, laser shock peening, surface burnishing and combinations
thereof.
11. The method of claim 1, wherein prior to step e), the
composition is slowly cooled or isothermally held.
12. The method of claim 1, wherein step e) includes rapidly
quenching the composition.
13. The method of claim 1, wherein step d) includes deforming the
composition while the composition is at a temperature below the
austenite recrystallization temperature and above the martensite
transformation start temperature.
14. The method of claim 1, wherein step d) includes deforming the
composition to induce martensite formation of the composition.
15. The method of claim 14, wherein the composition is deformed at
a temperature of from about 18.degree. C. to about 24.degree. C. or
form about -196.degree. C. to induce martensite formation of the
composition.
16. The method of claim 14, further comprising, after step d),
heating the composition to a temperature above the austenite
recrystallization stop temperature.
17. The method of claim 16, wherein heating the composition to a
temperature above the austenite recrystallization stop temperature
after step d) reverses deformation-induced martensite of the
composition into ultrafine grained austenite.
18. The method of claim 17, wherein the martensite start
temperature of the ultrafine grained austenite is below about
24.degree. C.
19. The method of claim 1, further comprising, after step e),
heating the composition to a temperature above the austenite
recrystallization stop temperature, and then quenching the
composition.
20. The method of claim 1, further comprising, prior to step c),
deforming the composition while the composition is at a temperature
above the austenite recrystallization stop temperature.
21. The method of claim 20, wherein the composition is deformed at
a temperature of from about 700.degree. C. to about 1000.degree.
C.
22. The method of claim 1, wherein step b) includes heating the
composition to at least about 1000.degree. C.
23. The method of claim 1, wherein step c) includes cooling the
composition at a rate of from about 2.degree. C. per second to
about 60.degree. C. per second.
24. The method of claim 1, wherein the composition further includes
one or more alloying elements selected from the group consisting of
chromium, aluminum, silicon, nickel, cobalt, molybdenum, niobium,
copper, titanium, vanadium, nitrogen, boron, zirconium, hafnium and
combinations thereof.
25. The method of claim 24, wherein the chromium ranges from 0.5 to
30 weight % of the total composition: wherein each of the nickel or
cobalt ranges from 0.5 to 20 weight % of the total composition;
wherein the aluminum ranges from 0.2 to 15 weight % of the total
composition; wherein each of the molybdenum, niobium, copper,
titanium or vanadium ranges from 0.2 to 10 weight % of the total
composition; wherein the silicon ranges from 0.01 to 10 weight % of
the total composition; wherein the nitrogen ranges from 0.01 to 3.0
weight % of the total composition; wherein the boron ranges from
0.001 to 0.1 weight % of the total composition; and wherein each of
the zirconium or hafnium ranges from 0.2 to 6 weight % of the total
composition.
26. The method of claim 1, wherein the composition includes from
about 8 to about 20 weight % manganese, from about 0.60 to about
3.0 weight % carbon, from about 0.5 to about 3 weight % chromium,
from about 0.5 to about 2.0 weight % copper, from about 0.1 to
about 1 weight % silicon, and the balance iron.
27. The method of claim 1, wherein step d) includes transformation
induced plasticity or twin-induced plasticity.
28. A ferrous based component comprising: a composition having from
about 5 to about 40 weight % manganese, from about 0.01 to about
3.0 weight % carbon, and the balance iron; and wherein the carbide
precipitate fraction volume of the composition is about 5 volume %
or less of the composition.
29. The component of claim 28, wherein the composition has a
microstructure having a refined grain size of about 100 .mu.m or
less.
30. The component of claim 29, wherein the microstructure having a
refined grain size of about 100 .mu.m or less includes a surface
layer of the composition.
31. The component of claim 30, wherein the thickness of the surface
layer is from about 100 nm to about 5000 nm.
32. The component of claim 30, wherein the surface layer is formed
prior to or during use of the composition.
33. The component of claim 28, wherein the composition further
includes one or more alloying elements chosen from the group
consisting of chromium, aluminum, silicon, nickel, cobalt,
molybdenum, niobium, copper, titanium, vanadium, nitrogen, boron,
zirconium, hafnium and combinations thereof.
34. The component of claim 33, wherein the chromium ranges from 0.5
to 30 weight % of the total composition; wherein each of the nickel
or cobalt ranges from 0.5 to 20 weight % of the total composition;
wherein the aluminum ranges from 0.2 to 15 weight % of the total
composition; wherein each of the molybdenum, niobium, copper,
titanium or vanadium ranges from 0.2 to 10 weight % of the total
composition; wherein the silicon ranges from 0.01 to 10 weight % of
the total composition; wherein the nitrogen ranges from 0.01 to 3.0
weight % of the total composition; wherein the boron ranges from
0.001 to 0.1 weight % of the total composition; and wherein each of
the zirconium or hafnium ranges from 0.2 to 6 weight % of the total
composition.
35. The component of claim 28, wherein the composition includes
from about 8 to about 20 weight % manganese, from about 0.60 to
about 3.0 weight % carbon, from about 0.5 to about 3 weight %
chromium, from about 0.5 to about 2.0 weight % copper, from about
0.1 to about 1 weight % silicon, and the balance iron.
36. A ferrous based component comprising: a composition having from
about 5 to about 40 weight % manganese, from about 0.01 to about
3.0 weight % carbon, and the balance iron; wherein the composition
has a microstructure having a refined grain size of about 100 .mu.m
or less.
37. The component of claim 36, wherein the microstructure having a
refined grain size of about 100 .mu.m or less includes a surface
layer of the composition.
38. The component of claim 37, wherein the thickness of the surface
layer is from about 10 nm to about 5000 nm.
39. The component of claim 37, wherein the surface layer is formed
prior to or during use of the composition.
40. The component of claim 36, wherein the composition further
includes one or more alloying elements chosen from the group
consisting of chromium, aluminum, silicon, nickel, cobalt,
molybdenum, niobium, copper, titanium, vanadium, nitrogen, boron,
zirconium, hafnium and combinations thereof.
41. The component of claim 36, wherein the chromium ranges from 0.5
to 30 weight % of the total composition; wherein each of the nickel
or cobalt ranges from 0.5 to 20 weight % of the total composition;
wherein the aluminum ranges from 0.2 to 15 weight % of the total
composition; wherein each of the molybdenum, niobium, copper,
titanium or vanadium ranges from 0.2 to 10 weight % of the total
composition; wherein the silicon ranges from 0.01 to 10 weight % of
the total composition; wherein the nitrogen ranges from 0.01 to 3.0
weight % of the total composition; wherein the boron ranges from
0.001 to 0.1 weight % of the total composition; and wherein each of
the zirconium or hafnium ranges from 0.2 to 6 weight % of the total
composition.
42. The component of claim 36, wherein the composition includes
from about 8 to about 20 weight % manganese, from about 0.60 to
about 3.0 weight % carbon, from about 0.5 to about 3 weight %
chromium, from about 0.5 to about 2.0 weight % copper, from about
0.1 to about 1 weight % silicon, and the balance iron.
43. A ferrous based component fabricated according to the steps
comprising: a) providing a composition having from about 5 to about
40 weight % manganese, from about 0.01 to about 3.0 weight %
carbon, and the balance iron; b) heating the composition to a
temperature above the austenite recrystallization stop temperature
of the composition; c) cooling the composition to a temperature
below the austenite recrystallization stop temperature of the
composition; d) deforming the composition while the composition is
at a temperature below the austenite recrystallization stop
temperature of the composition; and e) quenching the
composition.
44. The ferrous based component of claim 43, wherein after step e),
the carbide precipitate fraction volume of the composition is about
5 volume % or less of the composition.
45. The ferrous based component of claim 43, wherein after step e),
the composition has a microstructure having a refined grain size of
about 100 .mu.m or less.
46. The ferrous based component of claim 45, wherein the
microstructure having a refined grain size of about 100 .mu.m or
less includes a surface layer of the composition.
47. The ferrous based component of claim 46, wherein the thickness
of the surface layer is from about 10 nm to about 5000 nm.
48. The ferrous based component of claim 46, wherein the surface
layer is formed prior to or during use of the composition.
49. The ferrous based component of claim 46, wherein the surface
layer is formed via a surface deformation technique selected from
the group consisting of shot peening, laser shock peening, surface
burnishing and combinations thereof.
50. The ferrous based component of claim 43, further comprising
after step e) a surface deformation step selected from the group
consisting of shot peening, laser shock peening, surface burnishing
and combinations thereof.
51. The ferrous based component of claim 43, wherein prior to step
e), the composition is slowly cooled or isothermally held.
52. The ferrous based component of claim 43, wherein step e)
includes rapidly quenching the composition.
53. The ferrous based component of claim 43, wherein step d)
includes deforming the composition while the composition is at a
temperature below the austenite recrystallization temperature and
above the martensite transformation start temperature.
54. The ferrous based component of claim 43, wherein step d)
includes deforming the composition to induce martensite formation
of the composition.
55. The ferrous based component of claim 54, wherein the
composition is deformed at a temperature of from about 18.degree.
C. to about 24.degree. C. to induce martensite formation of the
composition.
56. The ferrous based component of claim 54, further comprising,
after step d), heating the composition to a temperature above the
austenite recrystallization stop temperature.
57. The ferrous based component of claim 56, wherein heating the
composition to a temperature above the austenite recrystallization
stop temperature after step d) reverses deformation-induced
martensite of the composition into ultrafine grained austenite.
58. The ferrous based component of claim 57, wherein the martensite
start temperature of the ultrafine grained austenite is below about
24.degree. C.
59. The ferrous based component of claim 43, further comprising,
after step e), heating the composition to a temperature above the
austenite recrystallization stop temperature, and then quenching
the composition.
60. The ferrous based component of claim 43, further comprising,
prior to step c), deforming the composition while the composition
is at a temperature above the austenite recrystallization stop
temperature.
61. The ferrous based component of claim 60, wherein the
composition is deformed at a temperature of from about 700.degree.
C. to about 1000.degree. C.
62. The ferrous based component of claim 43, wherein step b)
includes heating the composition to at least about 1000.degree.
C.
63. The ferrous based component of claim 43, wherein step c)
includes cooling the composition at a rate of from about 2.degree.
C. per second to about 60.degree. C. per second.
64. The ferrous based component of claim 43, wherein the
composition further includes one or more alloying elements selected
from the group consisting of chromium, aluminum, silicon, nickel,
cobalt, molybdenum, niobium, copper, titanium, vanadium, nitrogen,
boron, zirconium, hafnium and combinations thereof.
65. The ferrous based component of claim 64, wherein the chromium
ranges from 0.5 to 30 weight % of the total composition; wherein
each of the nickel or cobalt ranges from 0.5 to 20 weight % of the
total composition; wherein the aluminum ranges from 0.2 to 15
weight % of the total composition; wherein each of the molybdenum,
niobium, copper, titanium or vanadium ranges from 0.2 to 10 weight
% of the total composition; wherein the silicon ranges from 0.01 to
10 weight % of the total composition; wherein the nitrogen ranges
from 0.01 to 3.0 weight % of the total composition; wherein the
boron ranges from 0.001 to 0.1 weight % of the total composition;
and wherein each of the zirconium or hafnium ranges from 0.2 to 6
weight % of the total composition.
66. The ferrous based component of claim 43, wherein the
composition includes from about 8 to about 20 weight % manganese,
from about 0.60 to about 3.0 weight % carbon, from about 0.5 to
about 3 weight % chromium, from about 0.5 to about 2.0 weight %
copper, from about 0.1 to about 1 weight % silicon, and the balance
iron.
67. The ferrous based component of claim 43, wherein step d)
includes transformation induced plasticity or twin-induced
plasticity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 61/790,274 filed Mar. 15, 2013 and is herein
incorporated by reference in its entirety.
FIELD
[0002] The present disclosure relates to improved steel
compositions and methods of making the same, and more particularly,
to high manganese (Mn) steel compositions having enhanced wear
resistance and methods for fabricating high manganese steel
compositions having enhanced wear resistance.
BACKGROUND
[0003] Piping systems are widely used in a variety of settings
including, e.g., material conveying systems, fluids/solids
transport systems, mining operations, etc. For example, piping
systems in mining operations may be used to convey a mixture of
solid rock and sand particles in a liquid medium or slurry to the
processing plant, as well as to recycle the debris medium back to
the mining area. Some current pipe structures for slurry
hydro-transport or the like are typically made from low carbon,
pipeline grade steel (e.g., API specification 5L X65 or X70 grade
steels).
[0004] The conveying of slurries or the like often causes the
piping system to wear and fail prematurely. The abrasive/erosive
wear of piping systems can be produced by relative motion between
the pipe wall and hard solid particles in the fluid. For example,
the loss of piping materials may be the result of the sharp angular
edges of the particles cutting or shearing portions of the pipe
wall. As such, frequent repairs and/or replacements are considered
the norm, of which entails significant operation costs. Thus,
significant economic incentives exist to develop high strength
and/or wear resistance pipe materials to improve project economics
and reduce operational costs.
[0005] In general, various piping materials are available, from
low-alloy steels to bi-metallic and metallurgically bonded
composite materials. Some advantages of low alloy steel are low
cost and general availability. However, this steel has poor
abrasion resistance. Although such steel can typically be
strengthened to a certain extent by alloying and/or microstructure
modification, an increase in material hardness is generally
accompanied by a loss in ductility, which is unacceptable for most
material conveying systems. The bonded composite steel/pipe
typically has a shock resistant outer pipe jacketing and a hardened
wear resistant inner pipe. However, the applications of the bonded
composite steel/pipe are limited by availability and cost.
[0006] There also exists a need for enhanced wear resistant steel
in the oil sands mining industry. Such oil sands deposits have been
commercially recovered since the 1960's, and the recovery rate has
grown recently. The extraction of bitumen ore has generally been
extracted either by surface mining techniques for shallow deposits
(e.g., less than 100 m depth), or by in-situ thermal extraction
(e.g., involving the injection of steam, chemical solvents and/or
mixtures thereof) for deep deposits located deeper underground
(e.g., around 100 m or deeper). For the surface mining of shallow
oil sands, many types of heavy equipment and pipelines are
utilized. First, the oil sands are typically excavated using
shovels which transfer the mined material to trucks/vehicles. The
vehicles move the oil sand ores to ore preparation facilities,
where the mined ore is typically crushed and mixed with hot water.
The oil sands slurries are then typically pumped through
hydro-transport pipelines to the primary separation cell (PSC),
where the oil bitumen is generally separated from the sand and
water. After the bitumen is separated, the remaining sand and water
slurry is then transported through tailing pipelines to tailing
ponds for sands to settle down.
[0007] For example, the Canadian oil sands resources in
north-eastern Alberta contain large oil sands deposits covered by
shallow overburden, thereby making surface mining an efficient
method of oil bitumen extraction. In general, the sands are often
mined with shovels and transported to the processing plants by
hydro-transport pipelines or the like, where granular material oil
sand is typically transported as aqueous slurry. After bitumen
extraction, tailings are then typically transported by pipeline
from the processing facilities to sites where separation of solids
and water occurs. The hydro-transport of large amounts of slurry
mixture causes significant metal loss in conventional metallic
pipelines or the like, which results in short replacement cycles
and considerable cost.
[0008] Thus, the oil sands mining and ore preparation processes
involve several stress and/or impact abrasion challenges in
multiple equipment/operational areas (e.g., shovel teeth, hoppers,
crushers, conveyers, vibrating screens, slurry pumps, pipelines,
etc.). For example, in the downstream slurry transportation and
extraction processes, some of the challenges encountered in the
equipment, pipelines (e.g., hydro-transport pipelines), pumps
and/or the PSC include erosion, erosion/corrosion, corrosion,
stress, wear and/or abrasion or the like of the
equipment/materials. These equipment/material erosion/corrosion
challenges or the like lead to significant repair, replacement
and/or maintenance costs, as well as to production losses.
[0009] As noted, current piping structures for slurry
hydro-transport are typically made from low carbon, pipeline grade
steel (e.g., API specification 5L X70). In general, fast moving
solids in the slurry flow can cause considerable metal loss from
the pipes (e.g., metal loss of the inner pipe wall). The aqueous
and aerated slurry flow also typically causes accelerated pipe
erosion by providing for a corrosive environment. Moreover,
particulate matter in the slurry (under the influence of gravity)
causes damage along, inter alia, the bottom inside half of the
pipes. For example, the hydro-transport and tailings pipelines that
carry the sand and water slurry in oil sands mining operations
undergo severe erosion-corrosion damage during service, while the
bottom part (e.g., at the 6 o'clock position) of the pipeline
typically experiences the most severe erosion wear.
[0010] In order to extend service life of the pipelines some mine
operators have utilized the practice of periodically rotating
pipelines. For example, the pipelines are occasionally rotated
(e.g., after about 1500 hours of service) by about 90.degree..
After about three rotations (e.g., after about 6000 hours of
service), the pipelines are typically fully replaced. Various
materials, such as martensitic stainless steels, hard-facing
materials (e.g., WC-based, chromium-carbide based), and polymer
lining materials (e.g., polyurethane), have been evaluated and used
by oil sands mining operators. However, such materials have found
only niche applications, typically due to either relatively poor
wear/erosion performance (e.g., polymer liner) or high
material/fabrication costs (e.g., WC-based hard metal,
chromium-carbide based hard metal overlay material). However, pipe
erosion and the like remains a serious problem, and alternative
pipe structures and/or materials are sought to allow for a more
efficient/economical operation/solution.
[0011] Certain steels containing manganese (Mn) have been known
since about the 19th century. The first commercial high Mn steel
was invented by English metallurgist Robert Hadfield. "Hadfield
steel," with a composition of about 1.0 to about 1.4 weight %
carbon, and about 11 to about 14 weight % Mn, exhibits some wear
resistance, toughness and high work hardening. However, because of
various manufacturing pitfalls and challenges, Hadfield steel has
typically been used only as either cast or forged products. For
example, Hadfield steel requires high temperature soaking (e.g.,
normalizing) at temperatures above about 1050.degree. C., followed
by water quenching.
[0012] Recently, there has been some interest among steel mills in
alloys containing more manganese and generally less carbon than the
Hadfield steels. Steelmakers have researched the use of Mn steel
chemistry for automotive applications. Moreover, automakers have
investigated the use of high Mn steel for automotive
applications.
[0013] Thus, an interest exists for improved steel compositions
(e.g., having enhanced wear resistance), and methods for
fabricating the same. These and other inefficiencies and
opportunities for improvement are addressed and/or overcome by the
systems and methods of the present disclosure.
SUMMARY
[0014] The present disclosure provides advantageous steel
compositions. More particularly, the present disclosure provides
improved high manganese (Mn) steel having enhanced wear/erosion
resistance, and related methods for fabricating steel having
enhanced wear/erosion resistance. In exemplary embodiments, the
advantageous steel compositions/components of the present
disclosure improve one or more of the following properties: wear
resistance, ductility, crack resistance, erosion resistance,
fatigue life, surface hardness and/or environmental cracking
resistance.
[0015] In general, the present disclosure provides for
cost-effective high manganese steels having improved wear
resistance properties (e.g., step-out wear resistance, erosion
resistance, and/or erosion/corrosion resistance). More
specifically, the present disclosure provides ferrous steel alloyed
with a high amount (e.g., greater than or equal to about 5 weight
%) of manganese, and where the fabricated steel exhibits
increased/improved wear/abrasion resistance (e.g., improved
step-out wear resistance, wear resistance, erosion resistance,
and/or erosion/corrosion resistance). The present disclosure also
provides methods for fabricating such improved steel. In exemplary
embodiments and due to the unique combination of high strength and
work hardening rate, the high manganese steels of the present
disclosure have advantages/potential in applications where wear and
erosion resistances are desired/required.
[0016] In certain aspects, the disclosure provides methods for
improving the strength, toughness, and wear and erosion resistances
of the steels through the control of microstructure and/or
chemistry. In certain embodiments, the methods include steps to
promote phase transformations (e.g., to alpha prime martensite or
epsilon martensite phases), twinning during deformation, and/or
introducing hard erosion resistant second phase particles to the
compositions.
[0017] Some exemplary uses/applications of the steel compositions
of present disclosure include, without limitation, use in piping
systems, oil sand piping systems, material conveying systems,
fluids/solids transport systems, in mining operations, and/or as
material for earth-moving equipment and/or drilling components
(e.g., where abrasive wear and erosion resistances are important
factors, such as oil and gas exploration, production,
transportation and petrochemical applications). Moreover, the use
of the steels of the present disclosure can improve the economics
of oil sands production, and will improve certain materials
technologies (e.g., for slurry transport/tailings pipeline, for
casing/tubing in in-situ thermal extraction of heavy oils or the
like).
Exemplary Methods for Fabrication:
[0018] The present disclosure provides for a method for fabricating
a ferrous based component including: a) providing a composition
having from about 5 to about 40 weight % manganese, preferably from
about 9 to about 25 weight % manganese, even more preferably from
about 12 to about 20 weight % manganese, and from about 0.01 to
about 3.0 weight % carbon, preferably from about 0.5% to about 2.0
weight % carbon, even more preferably from about 0.7% to about 1.5
weight % carbon, and the balance iron, b) heating the composition
to a temperature above the austenite recrystallization stop
temperature of the composition (e.g., to a temperature to
homogenize the composition); c) cooling to a rolling start
temperature (RST) d) deforming or hot rolling the composition; and
e) quenching or accelerated cooling or air cooling the
composition.
[0019] The present disclosure provides for a method for fabricating
a ferrous based component including: a) providing a composition
having from about 5 to about 40 weight % manganese, preferably from
about 9 to about 25 weight % manganese, even more preferably from
about 12 to about 20 weight % manganese, and from about 0.01 to
about 3.0 weight % carbon, preferably from about 0.5% to about 2.0
weight % carbon, even more preferably from about 0.7% to about 1.5
weight % carbon, and the balance iron, b) heating the composition
to a temperature above the austenite recrystallization stop
temperature of the composition (e.g., to a temperature to
homogenize the composition); c) cooling to a rolling start
temperature (RST); d) deforming or hot rolling the composition; and
e) quenching or accelerated cooling or air cooling the
composition.
[0020] The present disclosure provides for a method for fabricating
a ferrous based component wherein after step d), the matrix of the
composition is predominantly or substantially in the austenitic
phase. In one or more embodiments, the volume percent of austenite
in the steel composition is from about 50 volume % to about 100
volume %, more preferably from about 80 volume % to about 99 volume
%, even more preferably from about 90 volume % to about 98 volume
%.
[0021] The steel composition is preferably processed into
predominantly or substantially austenitic plates using a hot
rolling process. In one or more embodiments, a steel billet/slab
from the compositions described is first formed, such as, for
example, through a continuous casting process. The billet/slab can
then be re-heated to a temperature ("reheat temperature") within
the range of about 1,000.degree. C. to about 1,300.degree. C., more
preferably within the range of about 1050.degree. C. to
1250.degree. C., even more preferably within the range of about
1100.degree. C. to 1200.degree. C. Preferably, the reheat
temperature is sufficient to: (i) substantially homogenize the
steel slab/composition, (ii) dissolve substantially all the carbide
and/or nitrides and/or borides and/or carbonitrides, when present,
in the steel slab/composition, and (iii) establish fine initial
austenite grains in the steel slab/composition.
[0022] The re-heated slab/composition can then be hot rolled in one
or more passes. In exemplary embodiments, the rolling or hot
deformation can be initiated at a "rolling start temperature". In
one or more embodiments, the rolling start temperature is above
1100.degree. C., preferably above 1080.degree. C., even more
preferably above 1050.degree. C. In exemplary embodiments, the
final rolling for plate thickness reduction can be completed at a
"rolling finish temperature". In one or more embodiments, the
rolling finish temperature is above about 700.degree. C.,
preferably above about 800.degree. C., more preferably above about
900.degree. C. Thereafter, the hot rolled plate can be cooled
(e.g., in air) to a first cooling temperature or accelerated
cooling start temperature ("ACST"), at which an accelerated cooling
starts to cool the plates at a rate of at least about 10.degree. C.
per second to a second cooling temperature or accelerated cooling
finish temperature ("ACFT"). After the cooling to the ACFT, the
steel plate/composition can be cooled to room temperature (e.g.,
ambient temperature) in ambient air. Preferably, the steel
plate/composition is allowed to cool on its own to room
temperature.
[0023] In one or more embodiments, the ACST is about 750.degree. C.
or more, about 800.degree. C. or more, about 850.degree. C. or
more, or about 900.degree. C. or more. In one or more embodiments,
the ACST can range from about 700.degree. C. to about 1000.degree.
C. In one or more embodiments, the ACST can range from about
750.degree. C. to about 950.degree. C. Preferably, the ACST ranges
from a low of about 650.degree. C., 700.degree. C., or 750.degree.
C. to a high of about 900.degree. C., 950.degree. C., or
1000.degree. C. In one or more embodiments, the ACST can be about
750.degree. C., about 800.degree. C., about 850.degree. C., about
890.degree. C., about 900.degree. C., about 930.degree. C., about
950.degree. C., about 960.degree. C., about 970.degree. C., about
980.degree. C., or about 990.degree. C.
[0024] In one or more embodiments, the ACFT can range from about
0.degree. C. to about 500.degree. C. Preferably, the ACFT ranges
from a low of about 0.degree. C., 10.degree. C., or 20.degree. C.
to a high of about 150.degree. C., 200.degree. C., or 300.degree.
C.
[0025] Without being bound by any theory, it is believed that the
rapid cooling (e.g., more than about 10.degree. C./sec cooling
rate) to the low accelerated cooling finish temperature ("ACFT")
retards at least a portion of the carbon and/or nitrogen atoms from
diffusing from the austenite phase of the steel composition to the
grain boundary or second phase. It is further believed that the
high accelerated cooling start temperature ("ACST") retards at
least a portion of the carbon and/or nitrogen atoms from forming
precipitates such as, for example, carbides, carbonitrides, and/or
nitrides during subsequent cooling to the ACFT. As such, the amount
of precipitates at the grain boundaries is reduced. Therefore, the
steel's fracture toughness and/or resistance to cracking is
enhanced.
[0026] Following the rolling and cooling steps, the plate can be
formed into pipes or the like (e.g. linepipe). Any suitable method
for forming pipe can be used. Preferably, the precursor steel plate
is fabricated into linepipe by a conventional UOE process or JCOE
process which is known in the art.
[0027] The present disclosure also provides for a method for
fabricating a ferrous based component including: a) providing a
composition having from about 5 to about 40 weight % manganese,
from about 0.01 to about 3.0 weight % carbon, and the balance iron;
b) heating the composition to a temperature above the austenite
recrystallization stop temperature of the composition; c) cooling
the composition to a temperature below the austenite
recrystallization stop temperature of the composition; d) deforming
the composition while the composition is at a temperature below the
austenite recrystallization stop temperature of the composition;
and e) quenching the composition.
[0028] The present disclosure also provides for a method for
fabricating a ferrous based component wherein after step e), the
carbide precipitate fraction volume of the composition is about 20
volume % or less of the composition, preferably about 15 volume %
or less of the composition, and even more preferably about 10
volume % or less of the composition. The present disclosure also
provides for a method for fabricating a ferrous based component
wherein after step e), the composition has a microstructure having
a refined grain size of about 100 .mu.m or less, preferably about
50 .mu.m or less, even more preferably about 30 .mu.m or less.
[0029] The present disclosure also provides for a method for
fabricating a ferrous based component wherein the microstructure
having a refined grain size of about 100 .mu.m or less includes a
surface layer of the composition. The present disclosure also
provides for a method for fabricating a ferrous based component
wherein the thickness of the surface layer is from about 10 nm to
about 10000 nm. The present disclosure also provides for a method
for fabricating a ferrous based component wherein the surface layer
is formed prior to or during the use of the composition. The
present disclosure provides for a method for fabricating a ferrous
based component wherein the surface layer is formed via a surface
deformation technique selected from the group consisting of shot
peening, laser shock peening, surface burnishing and combinations
thereof. The present disclosure provides for a method for
fabricating a ferrous based component further including after step
e) a surface deformation step selected from the group consisting of
shot peening, laser shock peening, surface burnishing and
combinations thereof.
[0030] The present disclosure provides for a method for fabricating
a ferrous based component wherein prior to step e), the composition
is slowly cooled or isothermally held. The present disclosure
provides for a method for fabricating a ferrous based component
wherein step e) includes rapidly quenching the composition. The
present disclosure provides for a method for fabricating a ferrous
based component wherein step d) includes deforming the composition
while the composition is at a temperature below the austenite
recrystallization temperature and above the martensite
transformation start temperature.
[0031] The present disclosure provides for a method for fabricating
a ferrous based component wherein step d) includes deforming the
composition to induce martensite formation of the composition. The
present disclosure provides for a method for fabricating a ferrous
based component wherein the composition is deformed at a
temperature of from about 18.degree. C. to about 24.degree. C. to
induce martensite formation of the composition. The present
disclosure provides for a method for fabricating a ferrous based
component further including, after step d), heating the composition
to a temperature above the austenite recrystallization stop
temperature. The present disclosure provides for a method for
fabricating a ferrous based component wherein heating the
composition to a temperature above the austenite recrystallization
stop temperature after step d) reverses deformation-induced
martensite of the composition into ultrafine grained austenite. The
present disclosure provides for a method for fabricating a ferrous
based component wherein the martensite start temperature of the
ultrafine grained austenite is below about 24.degree. C.
[0032] The present disclosure provides for a method for fabricating
a ferrous based component further including, after step e), heating
the composition to a temperature above the austenite
recrystallization stop temperature, and then quenching the
composition. The present disclosure provides for a method for
fabricating a ferrous based component further including, prior to
step c), deforming the composition while the composition is at a
temperature above the austenite recrystallization stop temperature.
The present disclosure provides for a method for fabricating a
ferrous based component wherein the composition is deformed at a
temperature of from about 700.degree. C. to about 1000.degree. C.
The present disclosure provides for a method for fabricating a
ferrous based component wherein step b) includes heating the
composition to at least about 1000.degree. C. The present
disclosure provides for a method for fabricating a ferrous based
component wherein step c) includes cooling the composition at a
rate of from about 1.degree. C. per second to about 60.degree. C.
per second.
[0033] The present disclosure provides for a method for fabricating
a ferrous based component wherein the composition further includes
one or more alloying elements selected from the group consisting of
chromium, aluminum, silicon, nickel, cobalt, molybdenum, niobium,
copper, titanium, tungsten, tantalum, vanadium, nitrogen, boron,
zirconium, hafnium and combinations thereof. The present disclosure
provides for a method for fabricating a ferrous based component
wherein the chromium ranges from 0 to 30 weight % of the total
composition, more preferably from 0.5 to 20 weight % of the total
composition, even more preferably from 2 to 5 weight % of the total
composition; wherein each of the nickel or cobalt ranges from 0 to
20 weight % of the total composition, more preferably from 0.5 to
20 weight % of the total composition, even more preferably from 1
to 5 weight % of the total composition; wherein the aluminum ranges
from 0 to 15 weight % of the total composition, more preferably
from 0.5 to 10 weight % of the total composition, even more
preferably from 1 to 5 weight % of the total composition; wherein
each of the molybdenum, niobium, copper, titanium, tungsten,
tantalum, or vanadium ranges from 0 to 10 weight % of the total
composition, more preferably from 0.02 to 5 weight % of the total
composition, even more preferably from 0.1 to 2 weight % of the
total composition; wherein the silicon ranges from 0 to 10 weight %
of the total composition, more preferably from 0.1 to 6 weight % of
the total composition, even more preferably from 0.1 to 0.5 weight
% of the total composition; wherein the nitrogen ranges from 0 to
3.0 weight % of the total composition, more preferably from 0.02 to
2.0 weight % of the total composition, even more preferably from
0.08 to 1.5 weight % of the total composition; wherein the boron
ranges from 0 to 0.1 weight % of the total composition, more
preferably from 0.001 to 0.1 weight % of the total composition; and
wherein each of the zirconium or hafnium ranges from 0 to 6 weight
% (e.g., 0.2 to 5 wt %) of the total composition.
[0034] The present disclosure provides for a method for fabricating
a ferrous based component wherein the composition includes from
about 8 to about 25 weight % manganese, from about 0.60 to about
3.0 weight % carbon, from about 0.05 to about 5 weight % chromium,
from about 0.0 to about 5.0 weight % copper, from about 0.01 to
about 7 weight % silicon, and the balance iron.
[0035] The present disclosure provides for a method for fabricating
a ferrous based component wherein step d) includes transformation
induced plasticity or twin-induced plasticity.
[0036] The present disclosure also provides for a ferrous based
component including a composition having from about 5 to about 40
weight % manganese, from about 0.01 to about 3.0 weight % carbon,
and the balance iron; and wherein the carbide precipitate fraction
volume of the composition is about 20 volume % or less of the
composition.
[0037] The present disclosure also provides for a ferrous based
component including a composition having from about 5 to about 40
weight % manganese, from about 0.01 to about 3.0 weight % carbon,
and the balance iron; and wherein the composition has a
microstructure having a refined grain size of about 150 .mu.m or
less.
[0038] The present disclosure also provides for a ferrous based
component including a composition having from about 5 to about 40
weight % manganese, from about 0.01 to about 3.0 weight % carbon,
and the balance iron; and wherein the composition has a tensile
yield strength of 300 MPa or higher at ambient temperature.
[0039] The present disclosure also provides for a ferrous based
component including a composition having from about 5 to about 40
weight % manganese, from about 0.01 to about 3.0 weight % carbon,
and the balance iron; and wherein the composition has a ultimate
tensile strength of 600 MPa or higher at ambient temperature.
[0040] The present disclosure also provides for a ferrous based
component including a composition having from about 5 to about 40
weight % manganese, from about 0.01 to about 3.0 weight % carbon,
and the balance iron; and wherein the composition has a tensile
uniform elongation of 7% or higher at ambient temperature.
[0041] The present disclosure also provides for a ferrous based
component including a composition having from about 5 to about 40
weight % manganese, from about 0.01 to about 3.0 weight % carbon,
and the balance iron; and wherein the composition has a Charpy
impact energy of about 20 J or higher at -40.degree. C.
[0042] The present disclosure also provides for a ferrous based
component including a composition having from about 5 to about 40
weight % manganese, from about 0.01 to about 3.0 weight % carbon,
and the balance iron; and wherein the composition has a wear and/or
erosion resistance of about 2 times or higher than that of API 5L
X70 grade carbon steels.
[0043] The present disclosure also provides for a ferrous based
component fabricated according to the steps comprising: a)
providing a composition having from about 5 to about 40 weight %
manganese, from about 0.01 to about 3.0 weight % carbon, and the
balance iron; b) heating the composition to a temperature above the
austenite recrystallization stop temperature of the composition; c)
cooling the composition to a temperature below the austenite
recrystallization stop temperature of the composition; d) deforming
the composition while the composition is at a temperature below the
austenite recrystallization stop temperature of the composition;
and e) quenching the composition.
[0044] Any combination or permutation of embodiments is envisioned.
Additional advantageous features, functions and applications of the
disclosed systems and methods of the present disclosure will be
apparent from the description which follows, particularly when read
in conjunction with the appended figures. All references listed in
this disclosure are hereby incorporated by reference in their
entireties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Features and aspects of embodiments are described below with
reference to the accompanying drawings, in which elements are not
necessarily depicted to scale.
[0046] Exemplary embodiments of the present disclosure are further
described with reference to the appended figures. It is to be noted
that the various steps, features and combinations of steps/features
described below and illustrated in the figures can be arranged and
organized differently to result in embodiments which are still
within the spirit and scope of the present disclosure. To assist
those of ordinary skill in the art in making and using the
disclosed systems, assemblies and methods, reference is made to the
appended figures, wherein:
[0047] FIG. 1 is an exemplary diagram of the phase stability and
deformation mechanism of high Mn steels as a function of alloy
chemistry and temperature;
[0048] FIG. 2 depicts exemplary approaches to improve the high Mn
steel wear resistance;
[0049] FIG. 3 displays the predicted influence of alloying elements
on the SFE values of the FeMn13C0.6 reference and the deformation
mechanism;
[0050] FIG. 4 depicts the effect of carbide precipitates on
mechanical properties and deformation mechanism (schematic, not in
scale);
[0051] FIG. 5 is a schematic drawing of an exemplary steel
fabrication method of the present disclosure;
[0052] FIG. 6 depicts a schematic of an exemplary fabrication
method for producing ultrafine grained high Mn steels according to
the present disclosure;
[0053] FIG. 7 shows a schematic of an exemplary impinging jet
testing facility/configuration;
[0054] FIG. 8 is a graph showing the erosion weight loss and volume
loss of three exemplary steels fabricated according to the present
disclosure, and a comparative X70 carbon steel:
[0055] FIGS. 9A and 9B depict transmission electron microscopy
bright field images of exemplary high Mn steel (FIG. 9A--sample
XM12), and X70 carbon steel (FIG. 9B--comparative steel), showing
the microstructure of a surface layer after erosion testing of high
Mn steel (sample XM12), and no surface layer after erosion testing
of the X70 carbon steel, wherein both samples were subjected to
identical erosion testing conditions;
[0056] FIG. 10 shows exemplary thermo-mechanical controlled process
(TMCP) hot rolling procedures/parameters for manufacturing improved
steels having further enhanced erosion/wear resistance; and
[0057] FIG. 11 is a graph that displays erosion volume loss in
exemplary high Mn steel compositions/components after the steel
compositions/components are fabricated in varied heat treatment
conditions.
DETAILED DESCRIPTION
[0058] The exemplary embodiments disclosed herein are illustrative
of advantageous steel compositions, and systems of the present
disclosure and methods/techniques thereof. It should be understood,
however, that the disclosed embodiments are merely exemplary of the
present disclosure, which may be embodied in various forms.
Therefore, details disclosed herein with reference to exemplary
steel compositions/fabrication methods and associated
processes/techniques of assembly and use are not to be interpreted
as limiting, but merely as the basis for teaching one skilled in
the art how to make and use the advantageous steel compositions of
the present disclosure. Drawing figures are not necessarily to
scale and in certain views, parts may have been exaggerated for
purposes of clarity.
[0059] All numerical values within the detailed description and the
claims herein are modified by "about" or "approximately" the
indicated value, and take into account experimental error and
variations that would be expected by a person having ordinary skill
in the art.
[0060] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limit of that range and any other stated or intervening
value in that stated range is encompassed within the invention.
Ranges from any lower limit to any upper limit are contemplated.
The upper and lower limits of these smaller ranges which may
independently be included in the smaller ranges is also encompassed
within the invention, subject to any specifically excluded limit in
the stated range. Where the stated range includes one or both of
the limits, ranges excluding either both of those included limits
are also included in the invention.
[0061] Although any methods and materials similar or equivalent to
those described herein can also be used in the practice or testing
of the present invention, the preferred methods and materials are
now described. All publications mentioned herein are incorporated
herein by reference to disclose and described the methods and/or
materials in connection with which the publications are cited.
[0062] It must be noted that as used herein and in the appended
claims, the singular forms "a", "and", and "the" include plural
references unless the context clearly dictates otherwise.
[0063] 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 to which this invention belongs. The
terminology used in the description of the invention herein is for
describing particular embodiments only and is not intended to be
limiting of the invention. All publications, patent applications,
patents, figures and other references mentioned herein are
expressly incorporated by reference in their entirety.
DEFINITIONS
[0064] CRA: Corrosion resistant alloys, can mean, but is in no way
limited to, a specially formulated material used for completion
components likely to present corrosion problems.
Corrosion-resistant alloys may be formulated for a wide range of
aggressive conditions.
[0065] Ductility: can mean, but is in no way limited to, a measure
of a material's ability to undergo appreciable plastic deformation
before fracture; it may be expressed as percent elongation (% EL)
or percent area reduction (% AR).
[0066] Erosion resistance: can mean, but is in no way limited to, a
material's inherent resistance to erosion when exposed to moving
solid particulates striking the surface of the material.
[0067] Toughness: can mean, but is in no way limited to, resistance
to fracture initiation.
[0068] Fatigue: can mean, but is in no way limited to, resistance
to fracture under cyclic loading.
[0069] Yield Strength: can mean, but is in no way limited to, the
ability to bear load without deformation.
[0070] Cooling rate: can mean, but is in no way limited to, the
rate of cooling at the center, or substantially at the center, of
the plate thickness.
[0071] Austenite: can mean, but is in no way limited to a solid
solution of one or more elements in face-centered cubic
crystallographic structure of iron; the solute can be, but not
limited to, carbon, nitrogen, manganese, and nickel.
[0072] Martensite: can mean, but is in no way limited to, a generic
term for microstructures formed by diffusionless phase
transformation in which the parent (typically austenite) and
product phases have a specific orientation relationship.
[0073] .epsilon.(epsilon)-martensite: can mean, but is in no way
limited to, a specific form of martensite having hexagonal close
packed crystal structure which forms upon cooling or straining of
austenite phase. .epsilon.-martensite typically forms on close
packed (111) planes of austenite phase and is similar to
deformation twins or stacking fault clusters in morphology.
[0074] .alpha.'(alpha prime)-martensite: can mean, but is in no way
limited to a specific form of martensite having body centered cubic
or body centered tetragonal crystal structure which forms upon
cooling or straining of austenite phase; .alpha.'-martensite
typically forms as platelets.
[0075] M.sub.s temperature: can mean, but is in no way limited to,
the temperature at which transformation of austenite to martensite
starts during cooling.
[0076] M.sub.f temperature: can mean, but is in no way limited to,
the temperature at which transformation of austenite to martensite
finishes during cooling.
[0077] M.sub.d temperature: can mean, but is in no way limited to,
the highest temperature at which a designated amount of martensite
forms under defined deformation conditions. Md temperature is
typically used to characterize the austenite phase stability upon
deformation.
[0078] Carbide: can mean, but is in no way limited to a compound of
iron/metal and carbon.
[0079] Cementite: can mean, but is in no way limited to, a compound
of iron and carbon having approximate chemical formula of Fe.sub.3C
with orthorhombic crystal structure.
[0080] Pearlite: can mean, but is in no way limited to, typically a
lamellar mixture of two-phases, made up of alternate layers of
ferrite and cementite (Fe.sub.3C).
[0081] Grain: can mean, but is in no way limited to, an individual
crystal in a polycrystalline material.
[0082] Grain boundary: can mean, but is in no way limited to, a
narrow zone in a metal corresponding to the transition from one
crystallographic orientation to another, thus separating one grain
from another.
[0083] Quenching: can mean, but is in no way limited to,
accelerated cooling by any means whereby a fluid selected for its
tendency to increase the cooling rate of the steel is utilized, as
opposed to air cooling.
[0084] Accelerated cooling start temperature (ACST): can mean, but
is in no way limited to, the temperature reached at the surface of
plate, when quenching is initiated.
[0085] Accelerated cooling finish temperature (ACFT): can mean, but
is in no way limited to, the highest, or substantially the highest,
temperature reached at the surface of the plate, after quenching is
stopped, because of heat transmitted from the mid-thickness of the
plate.
[0086] Slab: a piece of steel having any dimensions.
[0087] Recrystallization: the formation of a new, strain-free grain
structure grains from cold-worked metal accomplish by heating
through a critical temperature.
[0088] T.sub.nr temperature: the temperature below which austenite
does not recrystallize.
[0089] The present disclosure provides advantageous steel
compositions (e.g., having enhanced wear resistance). More
particularly, the present disclosure provides improved high
manganese (Mn) steel having enhanced wear resistance, and methods
for fabricating high manganese steel compositions having enhanced
wear resistance. In exemplary embodiments, the advantageous steel
compositions/components of the present disclosure improve one or
more of the following properties: wear resistance, ductility, crack
resistance, erosion resistance, fatigue life, surface hardness,
stress corrosion resistance, fatigue resistance, and/or
environmental cracking resistance.
[0090] In one aspect, the disclosure provides methods for improving
the strength, toughness, and wear and erosion resistances of the
steels through the control of microstructure and/or chemistry. In
certain embodiments, the strength, toughness, wear resistance
and/or erosion resistance of the steel compositions of the present
disclosure can be improved/increased through the control of
microstructure and/or chemistry. Some such possible routes include
promoting phase transformations (e.g., to martensite/epsilon
phases), twinning during deformation, and/or introducing hard
erosion resistant second phase particles to the compositions.
[0091] In another aspect, the present disclosure provides high
manganese steels tailored to resist wear and/or erosion (e.g.,
having improved wear/erosion resistance properties). In general,
due to the unique combination of high strength and work hardening
rate, the high manganese steels of the present disclosure have
advantages/potential in applications where wear and/or erosion
resistances are desired/required (e.g., oil and gas exploration,
production, transportation and petrochemical applications).
[0092] Any of the steel compositions as described or embraced by
the present disclosure may be advantageously utilized in many
systems/applications (e.g., piping systems, oil sand piping
systems, material conveying systems, fluids/solids transport
systems, in mining operations, and/or as material for earth-moving
equipment and/or drilling components), particularly where abrasive
wear and erosion resistances are important/desired. In exemplary
embodiments, the systems/methods of the present disclosure provides
for low-cost, high strength and wear/erosion resistance steels
(e.g., to be utilized in the manufacture of high performance slurry
transport lines, etc.).
[0093] As discussed in further detail below, the fabrication
methods/systems of the present disclosure can include one or more
of the following steps: (i) providing a high work hardening rate
matrix, through transformation induced plasticity ("TRIP") and/or
twin-induced plasticity ("TWIP"); (ii) providing meta-stability to
induce phase transformation during service; (iii) providing optimum
hardness of martensite (e.g., to be controlled by dissolved carbon
content, to provide required erosion resistance); (iv) the
dispersion of second phase particles (e.g., carbides,
quasi-crystals, etc.) of varying size ranges within the
compositions; (v) utilization of advantageous thermo-mechanical
controlled process ("TMCP") fabrication steps/schemes (e.g., to
achieve at least some of the steps above); and/or (vi) exemplary
joining methods, such as solid state joining (e.g., Friction Stir
Welding).
[0094] In general, the high manganese steels of the present
disclosure are relatively inexpensive alloys, and have potential
applications where wear resistance or the like of working
components is important. In certain embodiments, the steel
compositions have from about 0.60 to about 1.50 weight % carbon,
and from about 11 to about 20 weight % manganese.
[0095] In exemplary embodiments, the steel has a fully austenitic
structure obtained by quenching from a temperature above about
1000.degree. C. In this condition, the hardness of the material is
relatively low. One particularly advantageous feature of the high
manganese steel is the strong work hardening capability. Under
impact or other mechanical stress, the surface layer can increase
its hardness rapidly by martensitic transformation or twinning,
whereas other portions/parts of the steel remain substantially soft
and/or ductile. This combination of low cost and high work
hardening rate makes these steels advantageously suitable to be
applied as wear resistant piping material or the like.
[0096] In general, the present disclosure provides for steels that
exhibit a combination of high strength and erosion resistance.
Also, as the result of their good formability, the high manganese
steels as described herein can be used in a variety of settings,
including, mining and automotive applications.
[0097] As noted, the present disclosure relates to high manganese
steel chemistry and/or microstructures tailored to achieve step out
wear, erosion resistance and/or corrosion resistance. In exemplary
embodiments, surface grain refinement may take place in a surface
layer of certain high Mn steels either prior to and/or during
service/use (e.g., formed in-situ). For example, the grain
refinement at the surface can result in the formation of a layer
which possesses the unique combinations of high strength and
hardness, high ductility, and/or high toughness. Such fine grained
(e.g., about 100 nm layer in height) or ultrafine grained (e.g.,
about 10 nm layer in height) surface layer may be formed either
prior to and/or during service/use (e.g., formed in-situ), and can
impart step-out wear resistance, erosion resistance, and/or
corrosion resistance to the steel.
[0098] In exemplary embodiments, such fine grained (e.g., about 100
nm layer) or ultrafine grained (e.g., about 10 nm layer) surface
layer may be formed prior to use/installation of the exemplary
steel by such surface deformation techniques such as, without
limitation, shot peening, laser shock peening, and/or surface
burnishing.
[0099] Current practice provides that the mechanical loads against
the pipes in some piping systems are not strong enough to cause the
maximum work hardening of the steel. In exemplary embodiments, the
present disclosure provides high manganese steel with improved wear
resistance, which can provide pipes for piping systems with
advantageous wear life expectancies.
[0100] Current practice also provides that the steel in material
conveying systems (e.g., piping systems, heavy equipment, etc.)
often wears and/or fails prematurely, which leads to significant
repair, replacement and/or maintenance/production costs. In
exemplary embodiments, the present disclosure provides for
cost-effective steel compositions having improved
wear/corrosion/abrasion resistance properties, thereby providing a
significant commercial, manufacturing and/or operational advantage
as a result.
[0101] In additional exemplary embodiments, the present disclosure
provides for ferrous based components/compositions containing
manganese. In certain embodiments, the components/compositions
include from about 5 to about 40 weight % manganese, from about
0.01 to about 3.0 weight % carbon, and the balance iron. The
components/compositions can also include one or more alloying
elements, such as, without limitation, chromium, nickel, cobalt,
molybdenum, niobium, copper, titanium, vanadium, nitrogen, boron
and combinations thereof. Exemplary ferrous based
components/compositions containing manganese (and optionally other
alloying elements) are described and disclosed in U.S. Patent Pub.
No. 2012/0160363, the entire contents of which is hereby
incorporated by reference in its entirety.
Component Composition:
[0102] In exemplary embodiments and as noted above, the ferrous
based compositions include from about 5 to about 40 weight %
manganese, from about 0.01 to about 3.0 weight % carbon, and the
balance iron.
[0103] As such, the manganese level in the compositions may range
from about 5 to 40 wt % of the total component/composition. The
carbon level in the component/composition may range from 0.01 to
3.0 wt % of the total component/composition. In general, iron
constitutes the substantial balance of the
component/composition.
[0104] The components/compositions can also include one or more
alloying elements, such as, without limitation, chromium, aluminum,
nickel, cobalt, molybdenum, niobium, copper, titanium, vanadium,
nitrogen, boron, zirconium, hafnium and combinations thereof.
Weight percentages are based upon the weight of the total
component/composition.
[0105] Chromium may be included in the component from about 0 to
about 30 wt % (more preferably from 0.05 to 20 weight % of the
total composition, even more preferably from 1 to 5 weight % of the
total composition). Nickel may be included in the component from
about 0 to about 20 wt % (more preferably from 0.05 to 20 weight %
of the total composition, even more preferably from 1 to 5 weight %
of the total composition). Cobalt may be included in the component
from about 0 to about 20 wt % (more preferably from 0.05 to 20
weight % of the total composition, even more preferably from 1 to 5
weight % of the total composition). Aluminum may be included in the
component from about 0 to about 15 wt % (more preferably from 0.05
to 10 weight % of the total composition, even more preferably from
1 to 5 weight % of the total composition. Molybdenum may be
included in the component from about 0 to about 10 wt % (more
preferably from 0.2 to 5 weight % of the total composition, even
more preferably from 0.1 to 2 weight % of the total composition).
Silicon may be included in the component from about 0 to about 10
wt % (more preferably from 0.1 to 6 weight % of the total
composition, even more preferably from 0.1 to 0.5 weight % of the
total composition). Niobium, copper, tungsten, tantalum, titanium
and/or vanadium can each be included in the component from about 0
to about 10 wt % (more preferably from 0.02 to 5 weight % of the
total composition, even more preferably from 0.1 to 2 weight % of
the total composition). Nitrogen can be included in the component
from about 0.001 to about 3.0 wt % (more preferably from 0.02 to
2.0 weight % of the total composition, even more preferably from
0.05 to 1.5 weight % of the total composition). Boron can be
included in the component from about 0 to about 1 wt % (more
preferably from 0.001 to 0.1 weight % of the total
composition).
[0106] The ferrous based components/compositions containing
manganese may also include another alloying element selected from
the group consisting of zirconium, hafnium, lanthanium, scandium,
cerium and combinations thereof. Each of these other alloying
elements may be included in the component/composition in ranges
from about 0 to about 6 wt % (e.g., 0.02 to 5 wt %) based on the
total weight of the component/composition.
[0107] In general, the mechanical properties of the high Mn steels
of the present disclosure are dependent on the characteristics of
strain-induced transformation, which is typically controlled by the
chemical composition of the steels and/or the processing
temperatures. Unlike conventional carbon steels, high Mn steels
include a metastable austenite phase with a face centered cubic
(fcc) structure at ambient temperature (e.g., 18-24.degree.
C.).
[0108] Upon straining, the metastable austenite phase can transform
into several other phases through strain-induced transformation.
More particularly, the austenite phase could transform into
microtwins (fcc) structure (twin aligned with matrix),
.epsilon.-martensite (hexagonal lattice), and .alpha.'-martensite
(body centered tetragonal lattice), depending on steel chemistry
and/or temperature.
[0109] These transformation products could impart a range of unique
properties to high Mn steels. For example, fine microtwins
effectively segment primary grains and act as strong obstacles for
dislocation gliding. This leads to effective grain refinement which
results in an excellent combination of high ultimate strength and
ductility.
[0110] Chemical composition and temperature are known to be primary
factors controlling the strain-induced phase transformation
pathways as shown in FIG. 1. In general, high Mn steels can be
divided into four groups depending on the stability of austenite
phase upon straining and temperature, e.g., stable (A), mildly
metastable (B), moderately metastable (C) and highly metastable (D)
Mn steel. The metastability of these phases is affected by both
temperature and strain. These steels would tend to be more
metastable (e.g., higher tendency to transform) at lower
temperatures and higher strains.
[0111] FIG. 1 is an exemplary diagram of the phase stability and
deformation mechanism of high Mn steels as a function of alloy
chemistry and temperature. The letters (A, B, C, and D) indicate
the various methods of transformation during deformation. In this
diagram, steel A would deform by slip (similar to other metals and
alloys), while steels B-D would transform during deformation.
[0112] Steel in area A, with high Mn content (e.g., greater than or
equal to about 25 wt %), has stable austenite and deforms primarily
by dislocation slip upon mechanical straining. In general, steels
with a fully stabilized austenitic structure show lower mechanical
strength but remain tough at cryogenic temperatures, provide low
magnetic permeability and are highly resistant to hydrogen
embrittlement.
[0113] Steel in area B, which is mildly metastable, can be produced
with intermediate manganese content (e.g., from about 15 to about
25 wt % Mn, and about 0.6 wt % C). These steels form twins during
deformation. A large amount of plastic elongation can be achieved
by the formation of extensive deformation twins along with
dislocation slip, a phenomenon known as Twinning-Induced Plasticity
(TWIP). Twinning causes a high rate of work hardening as the
microstructure is effectively refined, as the twin boundaries act
like grain boundaries and strengthen the steel due to the dynamic
Hall-Petch effect. TWIP steels combine extremely high tensile
strength (e.g., greater than 150 ksi) with extremely high uniform
elongation (e.g., greater than 95%), rendering them highly
attractive for many applications.
[0114] The moderately metastable steels (Steel in area C) can
transform into .epsilon.-martensite (hexagonal lattice) upon
straining. Upon mechanical straining, these steels would deform
predominantly by the formation of .epsilon.-martensite, along with
dislocation slip and/or mechanical twinning.
[0115] The highly metastable steels (Steel in area D) will
transform to a strong body-centered cubic phase (referred to as
.alpha.'-martensite) upon deformation. This strong phase provides
resistance to erosion resulting from the impingement of external,
hard particles. Since the impact of the external particles results
in the deformation of the near surface regions of the steel, these
surface regions will transform during service, thereby providing
resistance to erosion. Therefore, these steels have a
"self-healing" characteristic in the sense that if the hard surface
layer gets damaged, it would reform by the impact of the
service.
[0116] Thus, the chemistry of the high Mn steels can be tailored to
provide a range of properties (e.g., wear resistance, cryogenic
toughness, high formability, erosion resistance) by controlling
their transformation during deformation.
Other Alloying Concepts in High Mn Steels:
[0117] Alloying elements in high Mn steels determine the stability
of the austenite phase and strain-induced transformation pathways.
In general, manganese is the main alloying element in high Mn
steels, and it is important in stabilizing the austenitic structure
both during cooling and deformation. In the Fe--Mn binary system,
with increasing Mn content, the strain induced phase transformation
pathway changes from .alpha.'-martensite to .epsilon.-martensite
and then to micro-twinning.
[0118] Carbon is an effective austenite stabilizer and the carbon
solubility is high in the austenite phase. Therefore, carbon
alloying can be used to stabilize the austenite phase during
cooling from the melt and during plastic deformation. Carbon also
strengthens the matrix by solid solution hardening. As noted, the
carbon in the components/compositions of the present disclosure may
range from about 0.01 to about 3.0 wt % of the total
component/composition.
[0119] Aluminum is a ferrite stabilizer and thus destabilizes
austenite phase during cooling. The addition of aluminum to high Mn
steels, however, stabilizes the austenite phase against
strain-induced phase transformation during deformation.
Furthermore, it strengthens the austenite by solid solution
hardening. The addition of aluminum also enhances the corrosion
resistance of the high Mn containing ferrous based components
disclosed herein due to its high passivity. The aluminum in the
components/compositions of the present disclosure may range from
about 0.0 to about 15 wt % of the total component.
[0120] Silicon is a ferrite stabilizer and sustains the
.alpha.'-martensite transformation while promoting
.epsilon.-martensite formation upon deformation at ambient
temperature. Due to solid solution strengthening, addition of Si
strengthens the austenite phase by about 50 MPa per 1 wt % addition
of Si. The silicon in the components/compositions of the present
disclosure may range from about 0.01 to about 10 wt % of the total
component.
[0121] Chromium additions to high Mn steel alloys enhance the
formation of ferrite phase during cooling and increase corrosion
resistance. Furthermore, the addition of Cr to the Fe--Mn alloy
system reduces the thermal expansion coefficient. The chromium in
the components/compositions of the present disclosure may range
from about 0.05 to about 30 wt % of the total component.
[0122] Based on the understanding of these alloying element effects
on strain-induced phase transformation, suitable steel chemistries
can be designed for specific applications. Some criteria for the
design of high Mn steels can be the critical martensite
transformation temperatures, e.g., M.sub.s and M.sub..epsilon.s.
M.sub.s is a critical temperature below which austenite to
.alpha.'-martensite transformation occurs, and M.sub..epsilon.s is
a critical temperature below which austenite to
.epsilon.-martensite transformation takes place.
[0123] The effects of alloying elements on M.sub.s and
M.sub..epsilon.s can be expressed as follows (unit of alloying
elements in weight percent, and where A.sub.3 is a critical
temperature above which all ferrite phases (including .alpha.'- and
.epsilon.-martensite phases) transform to austenite):
M.sub.s(K)=A.sub.3-410-200(C+1.4N)-18Ni-22Mn-7Cr-45Si-56Mo; and
M.sub..epsilon.s(K)=670-710(C+1.4N)-19Ni-12Mn-8Cr+13Si-2Mo-23Al
[0124] In general, only austenite to .alpha.'-martensite
transformation takes place if M.sub.s is much higher than
M.sub..epsilon.s. If M.sub..epsilon.s is much higher than M.sub.s,
only austenite to .epsilon.-martensite transformation takes place.
Both .alpha.'-martensite and e-martensite phase transformation
occur if M.sub.s and M.sub..epsilon.s are close to each other.
[0125] It is noted that the ferrous based components/compositions
containing manganese may be utilized in a wide variety of
applications/uses/systems (e.g., piping systems, oil sand piping
systems, material conveying systems, fluids/solids transport
systems, in mining operations, and/or as material for earth-moving
equipment and/or drilling components).
[0126] For example, as described and disclosed in U.S. Patent Pub.
No. 2012/0160363 noted above, the ferrous based
components/compositions containing manganese of the present
disclosure may find numerous non-limiting uses/applications in the
oil, gas and/or petrochemical industry or the like (e.g., cryogenic
applications, corrosion resistant applications, erosion resistant
applications, natural gas liquefaction/transportation/storage type
structures/components, oil/gas well completion and production
structures/components, subterraneous drilling equipment, oil/gas
refinery and chemical plant structures/components, coal mining
structures/equipment, coal gasification structures/equipment,
etc.).
[0127] The relatively low alloying content (e.g., less than about
20 wt % Mn, and about 1.5 wt % C) produces the highly metastable
austenite phase. The highly metastable austenite phase often
transforms into hard .alpha.'-martensite upon straining, which
typically is an irreversible transformation. Upon surface wear of
these steels, a surface layer of the highly metastable austenite
phase can transform to .alpha.'-martensite phase. This
friction-induced phase transformation leads to the formation of a
thin, hard surface layer composed of martensite over an interior
that consists of tough, untransformed austenite. This unique
combination renders high Mn steels suitable for wear/erosion and
impact resistant applications.
[0128] Moreover, the joining of the high Mn steels of the present
disclosure can be performed using conventional (e.g., fusion,
resistance welding, etc.) and emerging joining methods (e.g.,
laser, electron beam, friction stir welding, etc.), as described
and disclosed in U.S. Patent Pub. No. 2012/0160363 noted above. In
exemplary embodiments, preferred joining methods include solid
state welding methods (e.g., resistance welding, friction stir
welding), where such welding methods do not require the use of a
weld metal, although the present disclosure is not limited
thereto.
Bulk Modification:
[0129] The systems/methods of the present disclosure
provide/produce high Mn steel having, inter alia, excellent
abrasive wear resistance. The high strength and work hardening rate
of the steel compositions of the present disclosure reduce the
material losses of the steel during abrasion.
[0130] Some potential metallurgical approaches to enhance the
materials of the present disclosure are shown in FIG. 2. As such,
FIG. 2 depicts exemplary approaches to improve the high Mn steel
wear resistance. The bulk chemistry modification and second phase
particle strengthening is depicted in FIG. 2.
[0131] In exemplary embodiments, bulk modification is utilized to
promote phase transformation (TRIP) and twinning (TWIP) during
deformation. In general, the dispersed particles strengthen the
materials/compositions, but have complex effects. It is noted that
the dispersed particles may influence the: (i) chemistry of the
composition matrix itself, (ii) grain size, and (iii) overall
material/composition toughness. In general, the proper balance of
these effects is important to exemplary embodiments of the present
disclosure.
[0132] High manganese steel generally has a rapid work hardening
rate because of the TRIP/TWIP effects. Their activations are
typically triggered by the value of the stacking fault energy
("SFE") of the alloy. It is noted that the plastic deformation is
associated with martensitic transformation at low SFE values (e.g.,
less than about 12 mJ/m.sup.2), and by twinning at intermediate SFE
values. At even higher SFE values (e.g., greater than 35
mJ/m.sup.2), plasticity and strain hardening is typically
controlled solely by dislocation sliding. As such, the SFE value is
an important parameter in steel design.
[0133] The SFE is a function of alloy chemistry and temperature.
The intrinsic stacking fault can be represented as a
.epsilon.-martensite embryo of two planes in thickness. The SFE
includes both volume energy and surface energy contributions. It
has been demonstrated that the chemistry and temperature dependence
of SFE arises largely from the volume energy difference between
.epsilon.-martensite and austenite. Moreover, the volume free
energy of phases can be obtained from available databases or the
like.
[0134] FIG. 3 shows the predicted SFE values when adding each
alloying element to FeMn13C0.6. Stated another way, FIG. 3 displays
the predicted influence of alloying elements on the SFE values of
the FeMn13C0.6 reference and the deformation mechanism.
[0135] As shown in FIG. 3, the SFE contribution from the addition
of various alloying elements is different. Carbon has the strongest
effect, and manganese has the smallest influences. When the
interaction of multiple alloying elements is considered, the
dependence of SFE on chemistry will be complex and non-monotonic.
In general, the deformation mechanism can be controlled by properly
tailoring the bulk chemistry.
Second Phase Particle Dispersion Strengthening:
[0136] In exemplary embodiments, the systems/methods of the present
disclosure also include the introduction of second phase particles
to further improve the wear resistance of the exemplary steel
compositions. In certain non-limiting embodiments the exemplary
systems/methods are described primarily with respect to
carbide/nitride particles. However, it is noted that the
systems/methods of the present disclosure may utilize, apply to
and/or include other particles/precipitates, such as, without
limitation, borides and oxides. In exemplary embodiments, when
primarily carbide/nitride and oxide particles are considered, the
grain size refinement can be an additional benefit from the second
phase particles.
[0137] In general, the size and spatial distribution of the
particles are important. It has been demonstrated that the
effectiveness of the particles on the steel/material strengthening
increases with decreasing particle size. Thus, fine particles
generally contribute to the material wear resistance largely by
strengthening the materials, while coarse particles typically
provide additional resistance to erosive damage.
[0138] It is noted that the size and/or spatial distribution of the
particles can be adjusted or optimized based on materials service
conditions. For example, for compositions for us in a piping system
or the like, the wear damage may be caused by sands having wide
particle size distribution. Therefore, a bimodal particle
distribution could be considered for the steel composition. It is
noted that the fabrication or manufacture of high manganese steel
with various type and size second phase particle can be achieved
through various exemplary thermo-mechanical controlled processes
("TMCP"), as discussed further below.
[0139] In certain embodiments, the carbide/nitride precipitation
can also locally enhance the TRIP or TWIP effects in the austenitic
matrix. The interstitial elements (carbon and nitrogen)
concentration in carbide/nitride particles is much higher than the
average value of the steel. Due to diffusion gradients at the
interface, the interstitial elements could be depleted in
precipitates surrounding the matrix, which results in a lower
activation energy for TRIP or TWIP.
[0140] FIG. 4 (schematic, not in scale) displays the overall effect
of carbide precipitates on mechanical properties and the
corresponding deformation mechanism. Compared to the fully
austenitic steel with substantially the same chemistry, the high
manganese steel with the exemplary carbide/nitride particles can
have a higher yield strength and work hardening capability. In
exemplary embodiments, the combination of hard particles and a
work-hardenable material matrix makes the compositions of the
present disclosure suitable to withstand and/or reduce the abrasive
wear effects caused by operational use (e.g., by hard particle
cutting/shearing or the like).
Fabrication and Microalloying:
[0141] The steel compositions/components of the present disclosure
can be fabricated or manufactured by various processing techniques
including, but not limited to, various exemplary thermo-mechanical
controlled processing ("TMCP") techniques, steps or methods. In
general, some TMCP processes have been utilized to produce low
alloy steel, particularly where grain size and microstructure
refinement is desired.
[0142] In exemplary embodiments, to produce the desired
carbide/nitride particles, the particles should be in a
substantially dissolved state before the deformation, as
undissolved particles will suffer relatively rapid coarsening at
the elevated temperatures. The controlled deformation should take
place below the recrystallization stop temperature so that
deformation results in elongated austenite grains filled with
intra-granular crystalline defects, which are the preferred sites
for nucleation.
[0143] A slow cooling or isothermal holding is then required to
promote the particles precipitation. Finally, a rapid quench is
applied to keep a fully austenitic matrix.
[0144] FIG. 5 illustrates an exemplary fabrication schedule for the
production of steel compositions/components according to the
present disclosure. As such, FIG. 5 is a schematic drawing of an
exemplary steel fabrication method of the present disclosure. As
shown in FIG. 5. T.sub.nr is the austenite recrystallization stop
temperature, and A.sub.s is the austenite start temperature.
[0145] In exemplary embodiments, the TMCP methods have a
synergistic effect of micro-alloy additions. Depending on the
alloying elements to be added/utilized in the composition, the
appropriate thermo-mechanical conditions should be selected in
order to produce the desired fine particles. In general, the
alloying elements utilized in the methods of the present disclosure
can have some effect on either the TMCP, or the bulk property
modification, or both.
[0146] In certain embodiments, carbon is the one of the most
effective alloying elements to control the bulk deformation
mechanism, promote carbide precipitation and stabilize the
austenite phase during cooling. It is noted that the total carbon
content of the compositions could be much larger or higher compared
to conventional high manganese steel, but the amount of carbon in
solution after TMCP steps should be controlled to a much lower
level.
[0147] In exemplary embodiments, manganese is the austenite phase
stabilizer. This element can be mainly added to the compositions to
maintain a fully austenitic matrix during cooling and TMCP. In
general, it has little effect on the deformation mechanism.
[0148] Chromium is a carbide former. It will promote different
types of carbide, such as M7C and M23C6, depending on the alloy
level and/or thermal treatment temperature. Moreover, chromium
addition is typically important for corrosion resistance
enhancement.
[0149] Niobium, vanadium, tantalum and titanium are effective
elements to retard the recrystallization during TMCP by forming
strain induced (e.g., (Ti,Nb) (C,N)) precipitation on the deformed
austenite. In addition, the niobium, and/or vanadium, and/or
tantalum and/or titanium addition facilitates the bulk carbon
concentration modification according to exemplary embodiments of
the present disclosure.
[0150] Aluminum and silicon are added to tune or adjust the SFE of
the high manganese steel of the present disclosure. It is noted
that aluminum addition can facilitate quasi-crystalline phase
formation, as discussed below.
Quasi-Crystal Precipitation Hardened High Mn Steels:
[0151] It is another object of the present disclosure to provide
high Mn steels utilizing precipitation hardening of quasi-crystals.
In exemplary embodiments, high Mn steels can be strengthened by the
precipitation of quasi-crystals, and such structures can be
achieved by heat treating at elevated temperatures (e.g., up to
about 700.degree. C.).
[0152] In general, quasi-crystalline materials have periodic atomic
structures (e.g., 5-fold or 10-fold rotational symmetry), but
usually do not conform to the 3-D symmetry typical of ordinary
crystalline materials. Due to their crystallographic structure,
quasi-crystalline materials with tailored chemistry exhibit unique
properties, which are attractive for the strengthening of high Mn
steels.
[0153] It is noted that the quasi-crystalline precipitates can
provide higher strengthening effects than that of crystalline
precipitates (e.g., carbides), because of the difficulty of
dislocations to move through quasi-crystal lattices. Furthermore,
quasi-crystals usually will not grow beyond certain sizes unlike
crystalline precipitates, thereby alleviating over-aging concerns
associated with certain crystalline precipitates.
[0154] Quasi-crystal materials typically provide non-stick surface
properties due to their low surface energy (e.g., about 30
mJ/m.sup.2) on stainless steel substrates in icosahedral Al--Cu--Fe
chemistries. Due to their low surface energy, quasi-crystal
materials exhibit a low friction coefficient (e.g., about 0.05) in
scratch tests with diamond indentor in dry air, combined with
relatively high micro-hardness. Quasi-crystalline materials are
found in Al-TM (TM=transition metals; e.g., V, Cr, Mn), Al--(Mn,
Cu, Fe)--(Si), and Al--Cu-TM (e.g., Cr, Fe, Mn, Mo) systems.
Ultrafine Grained High Mn Steels:
[0155] In exemplary embodiments, improved steel compositions (e.g.,
ultrafine grained high Mn steel compositions) can be fabricated by
exemplary thermo-mechanical controlled processes (TMCP). In certain
embodiments, especially in lower Mn alloying chemistry such as 8
wt. % or less in which ferrite or martensite phase is
thermodynamically more stable than the austenite phase, the TMCP of
the present disclosure includes heavy plastic deformation at
ambient (e.g., 18-24.degree. C.) and/or cryogenic (e.g.,
-196.degree. C.) and/or intermediate temperatures to induce
martensite formation, and subsequent annealing at elevated
temperatures to reverse deformation-induced martensite into
ultrafine grained austenite. An exemplary thermo-mechanical
controlled process is schematically shown in FIG. 6. FIG. 6 depicts
a schematic of an exemplary fabrication method for producing
ultrafine grained high Mn steels according to the present
disclosure. As shown in FIG. 6, A.sub.f is the austenite finish
temperature (austenite recrystallization stop temperature), and
A.sub.s is the austenite start temperature.
[0156] In exemplary embodiments and after heating and holding the
steel composition at a normalizing temperature, the metastable
austenite phase of the steel composition is transformed to a
strain-induced martensite phase by heavy plastic deformation at
ambient (e.g., 18-24.degree. C.) and/or cryogenic (e.g.,
-196.degree. C.) and/or intermediate temperatures (FIG. 6). The
strain-induced martensite phase may be further heavily deformed to
destroy lath or plate structures prior to a reversion treatment
(e.g., reversion annealing in FIG. 6). The strain-induced
martensite phase may be reverted to the austenite phase at
temperatures low enough to suppress the grain coarsening of the
reverted austenite phase. In exemplary embodiments, the chemistry
of the steel compositions of the present disclosure (e.g., high Mn
steel compositions) can be tailored so that the martensite start
temperature (Ms) of reverted austenite is below room temperature
(e.g., 18-24.degree. C.).
Exemplary Methods for Fabrication:
[0157] The present disclosure provides for a method for fabricating
a ferrous based component including: a) providing a composition
having from about 5 to about 40 weight % manganese, preferably from
about 9 to about 25 weight % manganese, even more preferably from
about 12 to about 20 weight % manganese, and from about 0.01 to
about 3.0 weight % carbon, preferably from about 0.5% to about 2.0
weight % carbon, even more preferably from about 0.7% to about 1.5
weight % carbon, and the balance iron, b) heating the composition
to a temperature above the austenite recrystallization stop
temperature of the composition (e.g., to a temperature to
homogenize the composition); c) deforming the composition while the
composition is at a temperature below the austenite
recrystallization stop temperature of the composition; and d)
quenching or accelerated cooling or air cooling the
composition.
[0158] The present disclosure provides for a method for fabricating
a ferrous based component wherein after step d), the matrix of the
composition is predominantly or substantially in the austenitic
phase. In one or more embodiments, the volume percent of austenite
in the steel composition is from about 50 wt % to about 100 wt %,
more preferably from about 80 wt % to about 99 wt %.
[0159] The steel composition is preferably processed into
predominantly or substantially austenitic plates using a hot
rolling process. In one or more embodiments, a steel billet/slab
from the compositions described is first formed, such as, for
example, through a continuous casting process. The billet/slab can
then be re-heated to a temperature ("reheat temperature") within
the range of about 1,000.degree. C. to about 1,300.degree. C., more
preferably within the range of about 1050.degree. C. to
1250.degree. C., even more preferably within the range of about
1100.degree. C. to 1200.degree. C. Preferably, the reheat
temperature is sufficient to: (i) substantially homogenize the
steel slab/composition, (ii) dissolve substantially all the carbide
and/or carbonitrides, when present, in the steel slab/composition,
and (iii) establish fine initial austenite grains in the steel
slab/composition.
[0160] The re-heated slab/composition can then be hot rolled in one
or more passes. In exemplary embodiments, the reheated
slabs/billets can be cooled to the rolling start temperature. In
one or more embodiments, the rolling start temperature is above
900.degree. C., preferably above 950.degree. C., even more
preferably above 1000.degree. C.
[0161] In exemplary embodiments, the final rolling for plate
thickness reduction can be completed at a "finish rolling
temperature". In one or more embodiments, the finish rolling
temperature is above about 700.degree. C., preferably above about
800.degree. C., more preferably above about 900.degree. C.
Thereafter, the hot rolled plate can be cooled (e.g., in air) to a
first cooling temperature or accelerated cooling start temperature
("ACST"), at which an accelerated cooling starts to cool the plates
at a rate of at least about 10.degree. C. per second to a second
cooling temperature or accelerated cooling finish temperature
("ACFT"). After the cooling to the ACFT, the steel
plate/composition can be cooled to room temperature (e.g., ambient
temperature) in ambient air. Preferably, the steel
plate/composition is allowed to cool on its own to room
temperature.
[0162] In one or more embodiments, the ACST is about 700.degree. C.
or more, about 750.degree. C. or more, about 800.degree. C. or
more, or about 850.degree. C. or more. In one or more embodiments,
the ACST can range from about 700.degree. C. to about 1000.degree.
C. In one or more embodiments, the ACST can range from about
750.degree. C. to about 950.degree. C. Preferably, the ACST ranges
from a low of about 650.degree. C., 700.degree. C., or 750.degree.
C. to a high of about 900.degree. C., 950.degree. C., or
1000.degree. C. In one or more embodiments, the ACST can be about
750.degree. C., about 800.degree. C., about 850.degree. C., about
890.degree. C., about 900.degree. C., about 930.degree. C., about
950.degree. C., about 960.degree. C., about 970.degree. C., about
980.degree. C., or about 990.degree. C.
[0163] In one or more embodiments, the ACFT can range from about
0.degree. C. to about 500.degree. C. Preferably, the ACFT ranges
from a low of about 0.degree. C., 10.degree. C., or 20.degree. C.
to a high of about 150.degree. C., 200.degree. C., or 300.degree.
C.
[0164] Without being bound by any theory, it is believed that the
rapid cooling (e.g., more than about 10.degree. C./sec cooling
rate) to the low accelerated cooling finish temperature ("ACFT")
retards at least a portion of the carbon and/or nitrogen atoms from
diffusing from the austenite phase of the steel composition to the
grain boundary or second phase. It is further believed that the
high accelerated cooling start temperature ("ACST") retards at
least a portion of the carbon and/or nitrogen atoms from forming
precipitates such as, for example, carbides, carbonitrides, and/or
nitrides during subsequent cooling to the ACFT. As such, the amount
of precipitates at the grain boundaries is reduced. Therefore, the
steel's fracture toughness and/or resistance to cracking is
enhanced.
[0165] Following the rolling and cooling steps, the plate can be
formed into pipes or the like (e.g., linepipe). Any suitable method
for forming pipe can be used. Preferably, the precursor steel plate
is fabricated into linepipe by a conventional UOE process or JCOE
process which is known in the art.
[0166] The present disclosure will be further described with
respect to the following examples; however, the scope of the
disclosure is not limited thereby. The following examples
illustrate improved systems and methods for fabricating or
producing improved steel compositions (e.g., improved high Mn steel
compositions having enhanced wear resistance or the like). As
illustrated in the below examples, the present disclosure
illustrates that the advantageous steel compositions/components of
the present disclosure improve one or more of the following
properties: wear resistance, ductility, crack resistance, erosion
resistance, fatigue life, surface hardness, stress corrosion
resistance, fatigue resistance, and/or environmental cracking
resistance. In general, the strength/toughness and/or wear/erosion
resistances of the steels of the present disclosure can be
improved/increased through the control of microstructure and/or
chemistry. As noted, some possible routes include promoting phase
transformations (e.g., to martensite or epsilon phases), twinning
during deformation, and/or introducing hard erosion resistant
second phase particles to the compositions.
[0167] In exemplary embodiments, the present disclosure provides
for a ferrous based component fabricated according to the steps
comprising: a) providing a composition having from about 5 to about
40 weight % manganese, from about 0.01 to about 3.0 weight %
carbon, and the balance iron; b) heating the composition to a
temperature above the austenite recrystallization stop temperature
of the composition; c) cooling the composition; d) deforming the
composition while the composition is at a temperature below the
austenite recrystallization stop temperature of the composition;
and e) quenching or accelerated cooling or air cooling the
composition.
EXAMPLES
Example 1
[0168] In general, the erosion-corrosion behavior of a material
(e.g., steel piping material) is a function of multiple
interrelated parameters including slurry composition, erodent
particle size/shape, and flow rate, as well as the
chemistry/microstructure of the target materials. Impinging jet
testing and gas impingement tests have been utilized to evaluate
the erosion weight loss of selected steel materials under impact
erosion conditions, thereby simulating hydro-transport pipeline
environments.
[0169] FIG. 7 shows a schematic of an exemplary impinging jet
(e.g., jet impingement) testing facility/configuration. Erosion
tests were carried out with a water and sand slurry containing
about 25 weight % sand (AFS 50/70 standard silica sand). The water
slurry also contained about 1500 ppm of NaCl, and the pH and
temperature of the water was maintained at about 8.5 pH and about
45.degree. C., respectively.
[0170] The target materials (e.g., steel compositions/components)
were exposed to high speed (e.g., about 6 m/sec) water/sand slurry
at three different impingement angles (.alpha.) (e.g., about
15.degree., about 45.degree., about 90.degree.) for about four
hours. The erosion weight loss and volume loss of the target
materials were evaluated after each test using microbalance and
laser profilometry, respectively.
[0171] The erosion weight loss and volume loss of three exemplary
steels (Steel 11 or EM11, Steel 12 or EM12, Steel 13 or EM13)
fabricated according to the present disclosure, and a comparative
X70 carbon steel are shown in FIG. 8. The nominal chemical
compositions of the three (Steel 11 or EM11, Steel 12 or EM12,
Steel 13 or EM13) exemplary high Mn steels are shown below in Table
1 (all compositions in weight %). FIG. 8 shows the weight loss and
volume loss of the samples (X70 control sample, Steel 11 or EM11,
Steel 12 or EM12, Steel 13 or EM13) after impingement jet testing
at the about 45.degree. impingement angle.
[0172] As shown in FIG. 8, the improved high Mn steels (Steel 11 or
EM11, Steel 12 or EM12, Steel 13 or EM13) fabricated according to
the systems/methods of the present disclosure showed up to four
times the erosion resistance over the X70 carbon steel after the
lab-scale jet impingement tests.
[0173] As such, the high strength and work hardening rate of the
improved steels reduce the material loss during abrasion. It is
noted that one drawback of enhancing material strength for
wear/erosion resistance is that high strength can come with a
compromise in ductility/fracture toughness. The metallurgical
approaches of exemplary embodiments of the present disclosure
enhance strength and ductility of the steel at the same time by
refining the grain size.
[0174] After the erosion tests, the cross-sectional microstructure
of the three high Mn steels (Steel 11 or EM11, Steel 12 or EM12,
Steel 13 or EM13) and the comparative X70 steel were characterized
using focused ion beam (FIB) combined with transmission electron
microscopy (TEM). The three high Mn steels showed the formation of
an ultrafine grained (about 10 nm grain size) surface layer after
erosion testing, whereas the comparative X70 linepipe grade steel
displayed the absence of a distinct ultrafine grained surface layer
when it was subjected to identical erosion testing.
[0175] FIGS. 9A and 9B depict transmission electron microscopy
bright field images of exemplary high Mn steel (FIG. 9A--sample
Steel 12 or EM12), and X70 carbon steel (FIG. 9B--comparative
steel), showing the microstructure of a surface layer after erosion
testing of high Mn steel (sample Steel 12 or EM12), and no surface
layer after erosion testing of the X70 carbon steel, wherein both
samples were subjected to identical erosion testing conditions. The
exemplary high Mn steel (FIG. 9A--Steel 12 or EM12) showed the
formation of an ultrafine grained (e.g., about 10 nm grain size)
surface layer after erosion testing, and the X70 steel (FIG. 9B)
displayed the absence of a distinct ultrafine grained surface layer
when it was subjected to identical erosion testing conditions.
[0176] Prior to erosion testing, the three high Mn steels (Steel 11
or EM11, Steel 12 or EM12. Steel 13 or EM13) were re-heated at
about 1100-1120.degree. C. and finished rolled at about 830.degree.
C. into about 12 mm thick plates, followed by accelerated cooling.
The chemical composition of the three inventive steels are shown
below in Table 1.
TABLE-US-00001 TABLE 1 Nominal chemical composition of high Mn
steels (Compositions in weight %): Sample Manganese Chromium Copper
Silicon I.D. Carbon (C) (Mn) (Cr) (Cu) (Si) Steel 1.2 18 3 0.5 0.1
11/EM11 Steel 1.5 14 3 0.5 0.1 12/EM12 Steel 0.8 14 3 0.5 0.1
13/EM13
[0177] Without being bound by any theory, it is noted that an
increase in carbon content in the high Mn steel matrix enhances the
mechanical strength of the steel and the work hardening rate. In
exemplary embodiments, Mn alloying in the range of about 12-20
weight % of the total composition stabilizes the austenite phase,
and increases the carbon solubility in the steel matrix. The Cr
alloying up to about 3 weight % increases the corrosion resistance
and the mechanical strength by solution strengthening. The Cu
alloying of about 0.5 to about 2 weight % increases carbon
solubility and corrosion resistance.
Example 2
[0178] Table 2 below shows the heat treatment conditions and
microstructure of various embodiments of exemplary high Mn steel
(Steel11/EM11). The nominal chemical compositions of the exemplary
high Mn steel samples (Steel 11/EM11) utilized in Table 2 are shown
above in Table 1.
TABLE-US-00002 TABLE 2 Various heat treatment/deformation
conditions and resulting microstructure of exemplary high Mn steel
compositions (Steel 11/EM11): Hot Cooling Grain Carbide Sample
Normalizing deformation rate size fraction I.D. temp. (.degree. C.)
temp. (.degree. C.) (.degree. C./sec) (.mu.m) (Vol. %) Steel 11 Not
830 ~30 20-30 >5 (EM11): Applicable As-rolled Steel 11 1100 Not
>60 ~200 <1 (EM11): Applicable Solution heat treat Steel 11A
1050 1000 ~30 ~20 <2 (EM11A) Steel 11B 1050 700 ~30 ~200 <2
(EM11B) Steel 11C 1050 700 ~2 ~200 <2 (EM11C)
[0179] In exemplary embodiments and as shown in Table 2 and FIG.
10, the best erosion resistances were achieved in the steels with
finer grain sizes (e.g., about 30 .mu.m or less) and/or lower
carbide precipitate fractions (e.g., less than about 2 volume %),
as shown for samples Steel 11A (EM11A), Steel 11B (EM11B), and
Steel 11C (EM11C).
[0180] FIG. 10 shows exemplary thermo-mechanical controlled process
(TMCP) hot rolling procedures/parameters for manufacturing improved
steels (e.g., high Mn steels) having further enhanced erosion/wear
resistance. As such, FIG. 10 shows exemplary TMCP hot rolling
procedures/parameters for fabricating steels having improved grain
size and/or precipitates (e.g. carbide precipitate fraction vol. %)
refinement. As shown in FIG. 10, T.sub.nr is the austenite
recrystallization stop temperature (austenite finish
temperature).
[0181] In exemplary embodiments, the (TMCP) hot rolling parameters
can be adjusted to obtain steel compositions having a refined grain
sizes of about 200 .mu.m or less, and/or low carbide precipitate
fractions of about 5 volume % or less. The methods may include a
finish rolling step or steps at lower temperatures, which would
introduce deformation banding/dislocations tangles to thereby
enhance the formation of fine intra-grain precipitates.
[0182] The exemplary modified TMCP hot rolling steps/parameters can
be combined with the addition of various micro-alloying elements
such as, without limitation, V, Nb, Ti, Mo and/or N. It has been
found that the micro-alloying elements in high Mn steels can result
in the formation of fine carbide/nitride/carbo-nitride precipitates
finely dispersed in the steel matrix. The finely dispersed
precipitates can retard grain coarsening during reheating and
recrystallization during hot rolling, which thereby advantageously
enhances the strength of the steel compositions/components of the
present disclosure.
[0183] FIG. 11 is a graph that displays erosion volume loss in
exemplary high Mn steel compositions/components after the steel
compositions/components are fabricated in varied heat
treatment/deformation conditions. More particularly, FIG. 11 shows
erosion volume loss, evaluated by gas impingement testing, of
exemplary high Mn steels to illustrate the effect of manufacturing
processes on the microstructure and resulting erosion resistance of
the exemplary steels. As noted, the best erosion resistances were
achieved in the steels with finer grain sizes (e.g. about 30 .mu.m
or less) and/or lower carbide precipitate fractions (e.g., less
than about 2 volume %), as shown for samples Steel 11A (EM11A),
Steel 11B (EM11B), and Steel 11C (EM11C).
Example 3
[0184] Gas impingement erosion tests were carried out with an air
and silicate glass beads slurry. The gas impingement tests were
carried out at about 10 psi air pressure or 122 m/s gas flow rate
with glass beads about 50 .mu.m average diameter. The other
parameters followed ASTM G76.
[0185] The target materials (e.g., steel compositions/components)
were exposed to a high speed air/glass bead slurry at three
different impingement angles (e.g., about 15.degree., about
45.degree., about 90.degree.) for about 1 hour. The erosion weight
loss and volume loss of the target materials were evaluated after
each test using microbalance and laser profilometry,
respectively.
[0186] The erosion weight loss and volume loss of three exemplary
steels fabricated according to the present disclosure, and a
comparative X65 carbon steel, are shown below in Table 3. The
nominal chemical compositions of the exemplary high Mn steels are
also shown in Table 3 (all compositions in weight %).
TABLE-US-00003 TABLE 3 Chemical composition and gas impingement
erosion weight loss of high Mn steels (compositions in weight %):
Volume loss C Si Mn Al Cr Cu (mm3) Note X65 0.08 0.09 1.5 0.15 0.1
0.015 0.45 Steel C 0.593 0.111 17.92 1.47 -- -- 0.186 Finish
rolling Steel D 0.592 0.103 18.37 1.51 5.03 -- 0.199 temperature
Steel E 0.594 0.104 15.2 1.48 -- -- 0.191 (FRT) >1000.degree. C.
Steel 302 0.9 0.13 9.05 -- 5.01 -- 0.0893 Steel 305 0.9 0.13 11.8
-- 5.01 -- 0.117 Steel 303 1.2 0.1 8.9 -- 5.0 -- 0.067 Steel 306
1.2 0.1 12.1 -- 4.9 -- 0.045 Steel F 1.2 0.5 18.0 -- 2.1 -- 0.067
Steel 11 1.2 0.1 18.0 -- 3.0 0.5 0.071 830.degree. C. FRT Steel 202
1.2 0.1 18.0 -- 3.0 0.5 0.103 930.degree. C. FRT Steel 204 1.2 0.1
18.0 -- 3.0 2.0 0.053 930.degree. C. FRT Steel 206 1.5 0.1 18.0 --
3.0 0.5 0.128 930.degree. C. FRT Steel 208 1.5 0.1 18.0 -- 3.0 2.0
0.065 930.degree. C. FRT
[0187] As shown in Table 3, the high Mn steels fabricated according
to the systems/methods of the present disclosure showed up to ten
times the erosion resistance over the X65 carbon steel.
Example 4
[0188] Table 4 below shows the chemical composition and gas
impingement erosion weight loss of micro-alloyed high Mn steels.
All the micro-alloyed high Mn steels (e.g., Steel 601, Steel 602,
Steel 603, Steel 604, Steel 605) were fabricated by reheating at
about 1120.degree. C., finish rolling at about 970.degree. C.,
followed by accelerated cooling to room temperature.
TABLE-US-00004 TABLE 4 Chemical composition and gas impingement
erosion weight loss of micro-alloyed high Mn steels (compositions
in weight %): Volume loss C Si Mn Cr Cu Mo Ti Nb V N (mm3) X65 0.08
0.09 1.5 0.1 0.015 0.008 0.008 0.004 0.45 Steel 601 1.22 0.071
17.76 3.04 0.5 -- -- 0.022 -- -- 0.0595 Steel 602 1.24 0.167 18.3 3
0.5 -- 0.019 0.023 -- 0.083 0.0445 Steel 603 1.21 0.114 18.08 3 0.5
-- -- 0.022 0.095 -- 0.0536 Steel 604 1.19 0.119 18.02 2.96 0.5
1.01 -- 0.02 -- -- 0.0587 Steel 605 1.17 0.109 12.18 2.92 0.5 -- --
0.02 -- -- 0.0612
[0189] As shown in Table 4, the micro-alloyed high Mn steels
fabricated according to the systems/methods of the present
disclosure showed up to ten times the erosion resistance over the
X65 carbon steel.
[0190] Whereas the disclosure has been described principally in
connection with steel compositions for use in components for
material conveying systems, fluids/solids transport systems, mining
operations, oil sand piping systems, earth-moving equipment,
drilling components, and/or oil/gas/petrochemical applications,
such descriptions have been utilized only for purposes of
disclosure and are not intended as limiting the disclosure. To the
contrary, it is to be recognized that the disclosed steel
compositions are capable of use in a wide variety of applications,
systems, operations and/or industries.
[0191] Although the systems and methods of the present the systems
and methods of the present disclosure have been described with
reference to exemplary embodiments thereof, the present disclosure
is not limited to such exemplary embodiments and/or
implementations. Rather, the systems and methods of the present
disclosure are susceptible to many implementations and
applications, as will be readily apparent to persons skilled in the
art from the disclosure hereof. The present disclosure expressly
encompasses such modifications, enhancements and/or variations of
the disclosed embodiments. Since many changes could be made in the
above construction and many widely different embodiments of this
disclosure could be made without departing from the scope thereof,
it is intended that all matter contained in the drawings and
specification shall be interpreted as illustrative and not in a
limiting sense. Additional modifications, changes, and
substitutions are intended in the foregoing disclosure.
Accordingly, it is appropriate that the appended claims be
construed broadly and in a manner consistent with the scope of the
disclosure.
* * * * *