Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED FERRO-ALLOYS
BACKGROUND
The present disclosure generally relates to steel production and, more
particularly, to methods and compositions of improved high melting point
element
iron alloys for steel production.
High strength, high performance steels have various applications in both the
commercial and military industries. For example, commercial applications of
high
strength, high performance steels include the following: pressure vessels;
hydraulic
and mechanical press components; commercial aircraft frame and landing gear
components; locomotive, automotive, and truck components, gas and oil drilling
platforms, including die block steels for manufacturing of components; and
bridge
structural members. Example military applications of high strength, high
performance
steels include hard target penetrator warhead cases, missile components
including
frames, motors, and ordnance components including gun components, armor
plating,
military aircraft frame and landing gear components.
Many high performance steels, however, suffer from inconsistent mechanical
properties. For example these steels may have inconsistent hardness, ultimate
tensile
strengths, yield strengths, and notch toughness.
SUMMARY
The present disclosure generally relates to steel production and, more
particularly, to methods and compositions of improved high melting point
element
iron alloys for steel production.
The present disclosure provides, in certain embodiments, methods comprising
providing a composition comprising iron and a high melting point element;
heating
the composition to an elevated temperature up to about 3,500 F; holding the
composition at the elevated temperature for a time sufficient for the heat's
temperature to stabilize; and allowing the composition to cool or solidify.
The present disclosure provides, in certain embodiments, methods comprising
providing a master alloy comprising iron and up to about 30% by weight of a
high
melting point element; and adding the master alloy to a heat of steel.
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The present disclosure provides, in certain embodiments, compositions
comprising an alloy of iron and high melting point element in which the alloy
is up to
about 30% by weight of the high melting point element.
The present disclosure provides, in certain embodiments, compositions
comprising an alloy of iron and high melting point element having a
substantially
uniform microstructure.
The present disclosure provides, in certain embodiments, compositions
comprising an alloy of iron and high melting point element having the high
melting
point element uniformly distributed throughout the microstructure of the
composition.
The present disclosure provides, in certain embodiments, compositions
comprising an alloy of iron and high melting point element having a near or
complete
absence of an elemental form of the high melting point element.
The features and advantages of the present disclosure will be readily apparent
to those skilled in the art upon a reading of the description of the
embodiments that
follows. While numerous changes may be made by those skilled in the art, such
changes are within the spirit of the invention.
DRAWINGS
The patent or application file contains at least one drawing executed in
color.
Copies of this patent or patent application publication with color drawing(s)
will be
provided by the Office upon request and payment of the necessary fee.
These drawings illustrate certain aspects of some of the embodiments of the
present disclosure, and should not be used to limit or define the invention.
Figure 1 is an analysis of 1% FeW and an analysis of 30% FeW.
Figure 2 is 1% FeW Sample SEM Micrograph (16x).
Figure 3 is 1% FeW Sample SEM Micrograph (5000x).
Figure 4 is an analysis of 1% FeW Sample (Area la) and an analysis of 1%
FeW Sample (Area lb).
Figure 5 is 30% FeW Sample SEM Micrograph (15x).
Figure 6 is 30% FeW Sample (Area 2) SEM Micrograph (200x) and 30% FeW
Sample (Area 2) SEM Micrograph (1000x).
Figure 7 is an analysis of 30% FeW Sample (Area 2a) and an analysis of 30%
FeW Sample (Area 2b).
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Figure 8 is an analysis of 30% FeW Sample (Area 2c) and an analysis of 30%
FeW Sample (Area 2d).
Figure 9 is 1st Melt Sample OLM Micrograph (lOx).
Figure 10 is 1st Melt Sample SEM Micrograph (17x).
Figure 11 is 1st Melt Sample (Area 2) SEM Micrograph (230x).
Figure 12 is 1st Melt Sample (Areas 2a, b, c, and d) SEM Micrograph (700x).
Figure 13 is an analysis of 1st Melt Sample (Area 2a) and an analysis of 1st
Melt Sample (Area 2b).
Figure 14 is an analysis of 1st Melt Sample (Area 2c) and an analysis of 1st
Melt Sample (Area 2d).
Figure 15 is 1st Melt Sample (Area 3) SEM Micrograph (2000x) and an
analysis of 1st Melt Sample (Area 3).
Figure 16 is 1st Melt Sample (Areas 3a and 3b) SEM Micrograph (5000x).
Figure 17 is an analysis of 1st Melt Sample (Area 3a) and an analysis of 1st
Melt Sample (Area 3b).
Figure 18 is 1st Melt Sample (Area 5) SEM Micrograph (2000x) and an
analysis of 1st Melt Sample (Area 5).
Figure 19 is 1st Melt Sample (Area 6) SEM Micrograph (2000x) and an
analysis of 1st Melt Sample (Area 6).
Figure 20 is 2nd Melt Sample OLM Micrograph (lOx).
Figure 21 is 2nd Melt Sample SEM Micrograph (14x).
Figure 22 2nd Melt Sample (Area 2) SEM Micrograph (500x) and an analysis
of 2nd Melt Sample (Area 2).
Figure 23 is 2nd Melt Sample (Area 3) SEM Micrograph (500x) and an
analysis of 2nd Melt Sample (Area 3).
Figure 24 is 2nd Melt Sample (Areas 3a and 3b) SEM Micrograph (5000x).
Figure 25 is an analysis of 2nd Melt Sample (Area 3a) and an analysis of 2nd
Melt Sample (Area 3b).
Figure 26 is 2nd Melt Sample (Areas 4a and 4b) SEM Micrograph (5000x).
Figure 27 is an analysis of 2nd Melt Sample (Area 4a) and an analysis of 2nd
Melt Sample (Area 4b).
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Figure 28 is 2nd Melt Sample (Area 5) SEM Micrograph (1000x) and an
analysis of 2nd Melt Sample (Area 5).
Figure 29 is 2nd Melt Sample (Area 6) SEM Micrograph (500x) and an
analysis of 2nd Melt Sample (Area 6).
Figure 30 is 3rd Melt Sample OLM Micrograph (lOx).
Figure 31 is 3rd Melt Sample SEM Micrograph (16x).
Figure 32 is 3rd Melt Sample (Area 2) SEM Micrograph (500x) and an
analysis of 3rd Melt Sample (Area 2).
Figure 33 is 3rd Melt Sample (Area 3) SEM Micrograph (250x) and an
analysis of 3rd Melt Sample (Area 3).
Figure 34 is 3rd Melt Sample (Area 4) SEM Micrograph (1000x) and an
analysis of 3rd Melt Sample (Area 4).
Figure 35 is 3rd Melt Sample (Area 6) SEM Micrograph (1000x) and an
analysis of 3rd Melt Sample (Area 6).
Figure 36 is a Polished Sample: Mc 17% FeW (cross-section) OLM
Micrograph (8x).
Figure 37 is an analysis of Sample: Mc 17% FeW (from Zone 1) at 25kV and
an analysis of Sample: Mc 17% FeW (from Zone 2) at 25kV.
Figure 38 is an analysis of Sample: Mc 17% FeW (from Zone 4) at 25kV.
Figure 39 is a Polished Sample: Mc 17% FeW (cross-section) SEM
Micrograph (3000x).
Figure 40 is an analysis of Polished Sample: Mc 17% FeW (cross-section): W-
rich Phase at 25kV and an analysis of Polished Sample: Mc 17% FeW (cross-
section):
W-depleted Phase at 25kV.
Figure 41 is a Surface View of 20% FeW X090020 (Area 1) OLM Micrograph
01 (8x) and a Surface View of 20% FeW X090020 (Area 1) OLM Micrograph 02
(12.5x).
Figure 42 is a Surface View of 20% FeW X090020 (Area 1) SEM Micrograph
(15x).
Figure 43 is a Surface view of 20% FeW X090020 (Area 1, Spots A and B)
SEM Micrograph (380x) and a Surface View of 20% FeW X090020 (Area 1, Spots A
and B) SEM Micrograph (2000x).
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Figure 44 is an analysis of Surface View of 20% FeW X090020 (Area 1, Spot
A) and an analysis of Surface View of 20% FeW X090020 (Area 1, Spot B).
Figure 45 is a Surface View of 20% FeW X090020 (Area 1, Spots C-F) SEM
Micrograph (10000x).
Figure 46 is an analysis of Surface View of 20% FeW X090020 (Area 1, Spot
C) and an analysis of Surface View of 20% FeW X090020 (Area 1, Spot D).
Figure 47 is an analysis of Surface View of 20% FeW X090020 (Area 1, Spot
E) and an analysis of Surface View of 20% FeW X090020 (Area 1, Spot F).
Figure 48 is a Cross-sectional view of 20% FeW X090020 (Area 1) OLM
Micrograph 03 (6.25x) and a Cross-sectional View of 20% FeW X090020 (Area 1)
OLM Micrograph 04 (16x).
Figure 49 is a Cross-sectional View of 20% FeW X090020 (Area 1) SEM
Micrograph (l lx).
Figure 50 is a Cross-sectional view of 20% FeW X090020 (Area 1, Sports A
and B) SEM Micrograph 03 (380x) and a Cross-sectional View of 20% FeW
X090020 (Area 1, Spots A and B) SEM Micrograph (5000x).
Figure 51 is an analysis of Cross-sectional View of 20% FeW X090020 (Area
1, Spot A) and an analysis of Cross-sectional View of 20% FeW X090020 (Area 1,
Spot B).
Figure 52 is a Cross-sectional View of 20% FeW X090020 (Area 1, Spots C-
F) SEM Micrograph (10000x).
Figure 53 is an analysis of Cross-sectional View of 20% FeW X090020 (Area
1, Spot C) and an analysis of Cross-sectional View of 20% FeW X090020 (Area 1,
Spot D).
Figure 54 is an analysis of Cross-sectional View of 20% FeW X090020 (Area
1, Spot E) and an analysis of Cross-sectional View of 20% FeW X090020 (Area 1,
Spot F).
Figure 55 is a Surface View of M722575 ESI (Area 1) OLM Micrograph 05
(8x) and a Surface View of M722575 ESI (Area 1) OLM Micrograph 06 (12.5x).
Figure 56 is a Surface View of M722575 ESI (Area 1) SEM Micrograph
(17x).
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Figure 57 is BEI Surface View of M722575 ESI (Area 1, Spots A and B) SEM
Micrograph (1000x) and SEI Surface View of M722575 ESI (Area 1, Spots A and B)
SEM Micrograph (1000x).
Figure 58 is SEI Surface View of M722575 ESI (Area 1, Spots A-D) SEM
micrograph (2170x).
Figure 59 is an analysis of Surface View of M722575 ESI (Area 1, Spot A)
and an analysis of Surface View of M722575 ESI (Area 1, Spot B).
Figure 60 is an analysis of Surface View of M722575 ESI (Area 1, Spot C)
and an analysis of Surface View of M722575 ESI (Area 1, Spot D).
Figure 61 is a Cross-sectional View of M722575 ESI (Area 1) OLM
Micrograph 07 (6.25x) and Cross-sectional View of M722575 ESI (Area 1) OLM
Micrograph 08 (16x).
Figure 62 is a Cross-sectional View of M722575 ESI (Area 1) SEM
Micrograph (12x).
Figure 63 is a BEI Cross-sectional View of M722575 ESI (Area 1, Spots A
and B) SEM Micrograph (1000x) and SEI Cross-sectional View of M722575 ESI
(Area 1, Spots A and B) SEM Micrograph (1000x).
Figure 64 is a SEI Cross-sectional View of M722575 ESI (Area 1, Spots A-D)
SEM Micrograph (2170x).
Figure 65 is an analysis of Cross-sectional View of M722575 ESI (Area 1,
Spot A) and an analysis of Cross-sectional View of M722575 ESI (Area 1, Spot
B).
Figure 66 is an analysis of Cross-sectional View of M722575 ESI (Area 1,
Spot C) and an analysis of Cross-sectional View of M722575 ESI (Area 1, Pot
D).
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DESCRIPTION
Some high strength and/or high ductility steels require a high melting point
element (HME) to achieve desired mechanical properties. For example, Eglin
Steel
requires a tungsten range of 0.90% to 1.10% tungsten. The use of a ferro-HME
master
alloy (e.g., ferrotungsten) has been used to introduce HMEs into heats of
steel.
The addition of a master alloy in the production of steel appears to work for
materials that are evaluated on a macro basis particularly where discreet
carbide
particles are required, such as in some types of tool steel. When this alloy
is added to
materials that are evaluated on a micro basis, however, there are varying
results that
include a high rejection rate of production items. In addition, the inventors
have
observed that some heats of steel made in this manner fail to achieve
consistent
mechanical properties
The inventors believe that these inconsistent mechanical properties stem from
difficulties in getting the HME component into solution during the steelmaking
process. The present disclosure is based, at least in part, on the observation
that ferro-
HME alloys do not completely dissolve into the heat of steel resulting in
material that
may contain areas or phases of high HME content, or with HME bearing secondary
phase particles, resulting in materials with inconsistent mechanical
properties. The
inventors believe this may be due, at least in part, to HME phases that are
not
sufficiently alloyed to reach the eutectic point. That is, the master alloy
and/or
resulting steel may include three phases: substantially pure HME, iron (e.g.,
ferrite),
and Fe-HME alloy. Because steels are normally prepared at temperatures below
the
melting point of high melting point elements (HMEs), the melting point of the
HME
is never reached. This results in master alloys and steels with substantially
pure HME
phases, or non-eutectic phases, which likely result in the inconsistent
mechanical
properties observed in steels made without the benefit of the present
disclosure.
Accordingly, the present disclosure provides methods for making master alloys
and
steels, as well as master alloys and steels, with improved mechanical
properties (e.g.,
toughness and impact resistance).
The present disclosure provides, in certain embodiments, a method for making
a master alloy comprising providing a composition comprising iron and a high
melting point element (HME); heating the composition to an elevated
temperature up
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to about 3,500 F; holding the composition at the elevated temperature for a
time
sufficient for the compositions temperature to stabilize; and allowing the
composition
to cool or solidify. As used herein, the term "high melting point element"
(HME)
refers to an element having a melting point above 3,100 F. Examples of HME's
include tungsten (W), Rhenium (Re), Osmium (Os), Tantalum (Ta), Niobium (Nb),
Iridium (Ir), Boron (B), Ruthenium (Ru), Hafnium (Hf), Technetium (Tc),
Rhodium
(Rh), Zirconium (Zr), Platinum (Pt), and Thorium (Th). In some embodiments,
the
HME in the composition may be present up to about 30% by weight. While the
composition contains iron and HME, it also may include other elements known in
the
art to be useful in steel, such as, for example, carbon (c), manganese (Mn),
silicon
(Si), chromium (Cr), Nickel (Ni), Copper (Cu), phosphorous (P), sulfur (S),
calcium
(Ca), nitrogen (N), and aluminum (Al).
The composition is heated to an elevated temperature so that it will diffuse
to
form a molten composition. This molten composition is then held at the
elevated
temperature to allow the HME to diffuse throughout the molten composition. In
certain embodiments, the molten composition may be mixed while held at the
elevated temperature. For example, the composition may be mixed through
induction
stirring along with argon bubbling. By way of explanation, and not of
limitation, it is
believed that holding the molten composition at an elevated temperature allows
the
HME to diffuse throughout the molten composition providing opportunity for the
Fe
and HME to form a Fe-HME alloy phase of the intended composition such as a
eutectic or peritectic point. The particular hold time chosen can vary
depending on the
temperature of the molten composition until that temperature is substantially
stable.
The particular hold time chosen may vary depending on the exact amount and
type of
elements present in the composition. Examples of suitable hold times include
from
about 1 hour to about 10 hours. In general, suitable holding temperatures may
be fixed
close to or above the target eutectic or peritectic temperature (e.g.,
approximately
50 F to 100 F above the eutectic or peritectic temperature).
The composition may be processed further to form a master alloy, as is known
in the art. For example, the composition may be allowed to solidify or
actively cooled
and formed into suitable structures, such as, for example, splatter metal,
wire/rod
forms, and notch bars.
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In certain embodiments, a master alloy made as described above may be used
to produce high strength and/or high ductility steels. For example, a master
alloy of
the present disclosure may be added to a heat of steel and allowed to melt.
The master
alloys of the present disclosure, according to certain embodiments, are able
to provide
the HME such that it is capable of melting at useful furnace operating
temperatures up
to about 3,500 F. Once the master alloy melts into the heat of steel, it may
be held for
a time sufficient to allow diffusion of the master alloy throughout the heat
of steel in a
timeframe which allows commercial production. Subsequent processing steps
known
in the art are also contemplated, such as, for example, cooling, casting,
forging,
rolling into bar stock or tube production, ESR and VAR remelting, and the
like.
As noted above, the present disclosure provides methods that may be used to
make HME master alloys and HME alloy steels. Accordingly, the present
disclosure
provides, in certain embodiments, a master alloy comprising iron (Fe) and a
HME in
which the HME is present up to about 30% by weight. For example, in certain
embodiments, the HME may be tungsten present at about 30% by weight.
The present disclosure also provides HME alloy steels with improved
mechanical properties with the HME present from about 0.5% to about 5% by
weight.
For example, in certain embodiments, the HME in the HME alloy steel may be
tungsten present at approximately 30% by weight.
In general, in particular embodiments, the master alloys and steels of the
present disclosure should comprise sufficient Fe-HME phases to achieve
consistent
mechanical properties. Such master alloys and steels of the present disclosure
may
show a more uniform distribution of phases under SEM and a more uniform
distribution of Fe to HME as shown by EDS. In certain embodiments, the HME
alloy
steels may have a substantially uniform microstructure as measured by scanning
electron microscopy. In other embodiments, the HME alloy steels may have
uniform
mechanical properties, such as hardness and notch toughness (e.g., hardness in
the
high 40S to low 50S RC). In other embodiments, improved elevated temperature
strength and ductility also may be present.
In certain embodiments, the master alloys and steels of the present disclosure
are characterized by a near or total absence of the elemental form of the HME
present
in the microstructure. See, for example, Example 5 below.
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In some embodiments, the HME master alloys and HME alloy steels of the
present disclosure can be manufactured by the following processes: (i)
Electric Arc,
Ladle Refined and Vacuum Treated; (ii) Vacuum Induction Melting; Argon Oxygen
Decarbization, Vacuum Oxygen Decarburization, Plasma Re-Melting (iii) Vacuum
Arc Re-Melting; and/or (iv) Electro Slag Re-Melting. The use of the end item
will
dictate the manufacturing process that should be applied. End products made
from the
compositions of the present disclosure can be produced using open die forging,
close
die forging, solid or hollow extrusion methods, static or centrifugal
castings, sand
casting, investment casting, permanent mold casting, "V"-process molding, lost
foam
processes, continuous casting, plate rolling, bar rolling, tube production, or
other
methods known in the art. Additionally, various heat treatments may be
employed,
normalizing, homogenization, austenitizing, quenching including air, oil,
polymer,
water, and/or cryo quenching/treatment, followed by single or multiple
tempering
processes.
The HME master alloys and HME alloy steels of the present disclosure have
utility wherever high strength, high performance steel is desired. In certain
embodiments, the HME master alloys and HME alloy steels of the present
disclosure
may be useful in industrial applications, such as mining (e.g., surface mining
ground
engagement tooling, subsurface mining parts, such as conveyor flight bars,
racks, rack
gears), railroad components (e.g., knuckles, couplers, car components, and
draft
system components). In other embodiments, the HME master alloys and HME alloy
steels of the present disclosure may be useful in military applications, such
as military
hardware and armaments. For example, the HME master alloys and HME alloy
steels
of the present disclosure may be useful for penetrating war heads, bombs,
canon
tubes, breach blocks, and armor. In certain embodiments, the compositions of
the
present disclosure may be particularly useful in projectile penetrator
applications
wherein high impact velocities, such as those greater than 1,000 feet per
second, are
imparted to the projectile to cause deep penetration of rock and concrete
barriers. The
strength, toughness and wear resistance of the steel produced according to the
present
invention provides enhanced penetrator performance.
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To facilitate a better understanding of the present disclosure, the following
examples of certain aspects of some embodiments are given. In no way should
the
following examples be read to limit, or define, the entire scope of the
invention.
EXAMPLES
Example 1
In the case of ferrotungsten, ASTM specification A 144 provides four grades:
A, B, C, and D. Grade A has a tungsten range of 85% to 95%, while the
remaining
grades B through D each have a tungsten range of 75% to 85% and differ from
one
another in terms of other elements including carbon, phosphorous, sulfur,
silicon,
molybdenum and aluminum. A supplementary requirement includes limitations on
several other additional elements. These alloys can include approximately 5%-
25%
iron.
Iron melts at approximately 2795 F, and tungsten melts at approximately
6170 F. A combination of Fe 70% and W 30% melts at approximately 2800 F, and a
combination of Fe 20% and W 80% melts at approximately 4300 F.
Upon analyzing an existing Fe-W alloy addition material at Fe 20% and W
80% on a scanning electron microscope (SEM), one may find that the tungsten
alloy
existed as a mixed structure of Fe-W, Fe, CaWO4 and W. The problem with this
alloying element is that the pure W will never melt - it will remain as W in
the final
chemistry. This is because the melting and refining process used to produce
high
strength high ductility steels is <3000 F.
In particular embodiments, using an alloy addition material that includes a
tungsten range of up to about 30% may be optimal to meet the requirements of
high
strength and/or high ductility materials. It may also reduce the current
tungsten
separation problems found when using commercially available ferro-alloys with
75%
and higher tungsten composition. This ferro-alloy may include an iron range of
approximately 70%-90%. The use of a tungsten ore such as Scheelite (calcium
tungstate CaWO4) may be one approach to producing this alloy.
Example 2
Eglin Steel (ES) is a high-strength, high-performance, low-alloy, low-cost
steel, developed in collaboration between the US Air Force and Private
Industry. The
development of Eglin Steel was commissioned in order to find a low-cost
replacement
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for strong and tough but expensive superalloy steels such as AF-1410, Aermet-
100,
HY-180, and HP9-4-20/30. The material can be less expensive because it can be
electric-arc melted, ladle-refined & vacuum de-gassed. It does not require
vacuum re-
melting or electro-slag re-melting processing. Unlike some other high-
performance
alloys, Eglin Steel can be welded easily, broadening the range of its
application. Also,
it uses about 1% nickel where as superalloys can use up to about 14% nickel
and/or
cobalt, substituting silicon to help with toughness and particles of vanadium
carbide
and tungsten carbide for additional hardness and high-temperature strength.
The
material also involves chromium, tungsten, and low to medium amounts of
carbon,
which contribute to the material's strength and hardness.
At room temperature, ES's yield (tensile strength before deformation) is
224,500 PSI, ultimate yield (breaking point) is 263,700 PSI. At 900 C, yield
is
193,900 PSI, and ultimate yield is 246,700. Rockwell hardness is 45.6. For
toughness,
the Charpy notch impact is 56.2 foot-pounds at room temperature, and 42.7 ft-
lbs at -
40F.
Eglin steel samples were analyzed: V297 (Original Item); V298 (Large Ingot
); V299 (Small Ingot). Table 1 provides hardness data as HV-10 (HRC). Table 2
provides Charpy impact test results for V299 and V298. Table 3 provides test
results
for V297.
Table 1. ASTM E 92 Hardness Test
Hardness Original (V297-4) Large Ingot Small Ingot
(V298) (V299)
Vickers 10kg 504 11 (49 HRC)
Vickers micro 500g 510 11 (50 HRC) 499 14 (49 HRC)
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Table 2. Charpy Impact Test (-40 F)
Sample Small Ingot (V299) Large Ingot (V298)
ft. lbf. ft. lbf.
13.0 26.8
16.2 19.7
17.7 20.0
12.3 23.4
21.2 21.9
21.6 20.6
Median 17.0 21.3
Std. Dev 4.0 2.7
Table 3. ASTM A370-08a test of V297
ft. lbf. Lat Ex p. % Shear
19.0 0.003 11
Range (Original): 15-25 ft. lbf.
Example 3
Five samples of potential alloying compounds of the present disclosure were
evaluated to show the different phases present in each with a corresponding
EDS
comparison of the elemental composition of each phase. Scanning electron
microscopy (SEM) was used in combination with energy dispersive x-ray
spectroscopy (EDS) to document the appearance of different phases and to
verify their
elemental composition in the various samples provided. EDS analysis was
performed
on 30% FeW and 1% FeW references for comparison with the three "Melt" samples:
1st Melt (hold time 2 hours); 2nd Melt (hold time 4 hours); 3rd Melt (hold
time 6
hours).
Each EDS spectrum was acquired using EDS system operating at an
acceleration energy of 15 W. Each SEM micrograph was taken in the
backscattered
electron image (BE1) mode using an instrument operating at acceleration energy
of 15
W. Prior to SEM/EDS analysis, each sample was sputter-coated with a thin film
of
carbon to enhance SEM image quality and/or EDS data collection. Each optical
light
microscopy photograph was taken with a stereo light microscope, equipped with
a
digital camera, using a high angle light source.
1% FeW and 30% FeW. The EDS spectra of Figure 1 compare the bulk
elemental compositions of these two reference samples. The SEM micrograph of
Figure 2 displays the entire 1% FeW sample, while the micrograph of Figure 3
is a
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higher magnification view of a typical area indicating locations (Areas la and
lb)
analyzed with EDS (Figure 4). The SEM micrograph of Figure 5 is a low
magnification view of the entire 30% FeW sample showing the general location
of the
regions (Areas 1 and 2) analyzed with SEM/EDS. The SEM micrographs of Figure 6
shows Area 2 at slightly higher magnifications; the areas analyzed with EDS
also are
shown (2a-2d). Corresponding EDS spectra are shown in Figures 7-8.
1st Melt. The micrographs of Figures 9 and 10 are optical light microscope
(OLM) and SEM views of this sample showing the areas (Areas 1-7) analyzed with
EDS. SEM images documenting general appearance and/or (microstructure)
features
specific to each of these areas, with corresponding EDS spectra verifying
elemental
composition are shown in Figures 11 (Area 2); Figure 12-14 (Area 2a-d); Figure
15
(Area 3); Figure 16-17 (Area 3a-b); Figure 18 (Area 5); Figure 19 (Area 6).
2nd Melt. The micrographs of Figures 20 and 21 are OLM and SEM views of
this sample showing the areas (Areas 1-7) analyzed with EDS. The SEM images
document general appearance and/or (microstructure) features specific to Areas
2, 3,
4, 5, and 6, with corresponding EDS spectra verifying elemental composition
(Figures
22-29). Note that surface "texturing" which is visible in the SEM micrograph
for Area
1 is an artifact created by the lifting of the carbon film from the surface of
the sample
due to contamination.
3rd Melt. The micrographs of Figures 30 and 31 are OLM and SEM views of
this sample showing the areas (Areas 1-7) analyzed with EDS. SEM images are
displayed documenting the general microstructure of each Areas 2, 3, 4, and 6
with
corresponding EDS spectra verifying elemental composition in Figures 32-35.
Please
note that surface "texturing" which is visible in the SEM micrographs for
Areas 2 and
3 is an artifact created by the lifting of the carbon film from the surface of
the sample
due to contamination.
After holding for 4 hours (2nd Melt) the sample showed a more uniform
distribution of phases under SEM, a more uniform distribution of
ferrotungsten, and a
near or complete absence of elemental W as shown by EDS.
Example 4
A 17% FeW sample as-cast was polished and etched with nital. The sample
showed a distinct surface layer and columnar grains extending into the
section. The
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surface layer contained two separate phases with an equiaxed grain
orientation,
transitioning to the more direction grains in the interior. The interior
showed large
oriented grains with two phases. (Data not shown.)
Scanning electron microscopy (SEM) using an SEM beam energy setting of
25kV and energy dispersive x-ray spectroscopy (EDS) was used to study the
surface
and inclusions/phase structures and corresponding elemental composition of 17%
FeW samples. All SEM micrographs were taken in either the secondary electron
image (SEI) or BE1 modes using a Tescall Vega II instrument operating at an
acceleration energy of l5kV. EDS spectra were collected with an Oxford INCA
EDS
system using an electron beam operating at an acceleration energy of 15 W.
Prior to
SEM/EDS analysis, each polished sample was sputter-coated with a thin film of
carbon to enhance SEM image quality. All optical light microscope photographs
were
taken with an Olympus SZX12 stereo light microscope, equipped with a digital
camera using a high angle light source.
The 17% FeW sample showed a distinct surface layer when etched, but EDS
scans of the surface layers showed no difference from the interior. Two
distinct
phases were present in the alloy with the second phase appearing as acicular
grains
about 1 to 4 microns wide by 10-20 microns long. The second phase had
significantly
higher levels of tungsten, but still was an intermetallic compound of tungsten
and iron
rather than pure tungsten. The iron-tungsten phase diagram suggests that the
matrix is
an alpha phase with about 8% tungsten while the second is a delta phase with
upwards
of 60% tungsten
The optical light microscope photograph of Figure 36 is a low magnification
view of the crosssectioned polished Me 17% FeW sample showing distinct regions
visible in this material with corresponding EDS spectra (Figures 37-38).
The SEM micrograph of Figure 39 is a higher magnification view of the cross-
sectioned/polished Me 17% FeW sample photographed in the backscattered
electron
image (BE1) mode showing the morphology of tungsten (W) rich and depleted
phases.
The accompanying EDS spectra highlight differences in W concentration among
these
two areas (Figure 40).
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In these samples, elemental W was detected indicating that the W did not go
into solution. These samples also did not show a uniform distribution of
phases under
SEM and did not show a uniform distribution of ferrotungsten.
Example 5
SEM was used in combination with EDS to document the appearance of
different phases and to verify their elemental composition of 20% FeW X0900200
and M722575 ES 1.
Each EDS spectrum was acquired using a system operating at acceleration
energies of either l5kV or 25kV. SEM micrographs were taken in the secondary
electron image (SEI) and backscattered electron image (BE1) modes using a
instrument operating at acceleration energies of 15 kV (20% FeW X0900200) or
25
kV (M722575 ESI). Prior to SEM/EDS analysis, the 20% FeW X0900200 sample was
sputter-coated with a thin film of carbon to enhance SEM image quality and/or
EDS
data collection. The M722575 ES1 sample was not carbon-coated. Each optical
light
microscopy photograph was taken with a stereo light microscope, equipped with
a
digital camera, using a high angle light source.
Both the 20% FeW and ES 1 samples were sectioned and portions from both
the face and section were mounted, ground and polished for metallographic
examination.
20% FeW X0900200 (Surface Orientation). A 20% FeW (sample X0900200)
under a low magnification optical light microscope is shown in Figure 41. The
same
sample is shown using SEM with the general location of the areas analyzed with
EDS
identified (Figure 42-43). SEM images are displayed documenting general
appearance
and/or microstructure features specific to each of these areas, with
corresponding EDS
spectra verifying elemental composition (Figures 44-47).
20% FeW X0900200 (Cross-sectional Orientation). A 20% FeW (sample
X0900200) under a low magnification optical light microscope is shown in
Figure 48.
The same sample is shown using SEM with the general location of the areas
analyzed
with EDS identified (Figure 49-50). SEM images are displayed documenting
general
appearance and/or microstructure features specific to each of these areas,
with
corresponding EDS spectra verifying elemental composition (Figures 51-54).
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M722575 ES1 (Surface Orientation). A ES1 steel (sample M722575) under a
low magnification optical light microscope is shown in Figure 55. The same
sample is
shown using SEM with the general location of the areas analyzed with EDS
identified
(Figure 56-58). SEM images are displayed documenting general appearance and/or
microstructure features specific to each of these areas, with corresponding
EDS
spectra verifying elemental composition (Figures 59-60).
M722575 ES1 (Cross-sectional Orientation). A ES1 steel (sample M722575)
under a low magnification optical light microscope is shown in Figure 61. The
same
sample is shown using SEM with the general location of the areas analyzed with
EDS
identified (Figure 62-64). SEM images are displayed documenting general
appearance
and/or microstructure features specific to each of these areas, with
corresponding EDS
spectra verifying elemental composition (Figures 65-68).
In these samples, a near or complete absence of elemental W indicating that
the W went into solution. These samples also showed a more uniform
distribution of
phases under SEM and a more uniform distribution of ferrotungsten.
Example 6
A 30% FeW master allow of the present disclosure was used to prepare an
ES1 alloy of the present disclosure in a VIM furnace. This ES1 alloy was
tested for
impact and tensile strength. The data, shown in the tables below, shows that
the ES 1
(an example of an HME alloy steel of the present disclosure) had improved
mechanical properties.
Impact testing was performed using Charpy V-notch according to ASTM E23-
07a at -40 F (Table 4), -65 F (Table 5), and 74 F (Table 6). Tensile testing
was
performed at room temperature using a seed of 0.005 in./in./min., 0.05
in./min./in.
(Table 7) according to ASTM E8-08.
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Table 4. Impact Results: ASTM E23-07a
Specimen ID Sample Size Temp. F Energy Mils Lat % Shear
ft-lbs Exp Fracture
M722575-1A-C2-CHT-40 Standard -40 34 10 30
M722575-1A-C5-XX-40 Standard -40 33 10 30
M722575-1A-C8-CHT-40 Standard -40 32 10 30
M722575-1A-C11-XX-40 Standard -40 33 11 30
M722575-1A-C14-CHT-40 Standard -40 33 11 30
M722575-1A-C17-XX-40 Standard -40 33 9 30
M722575-1B-C2-CHT-40 Standard -40 30 8 30
M722575-1B-C5-XX-40 Standard -40 29 7 30
M722575-1B-C8-CHT-40 Standard -40 30 8 30
M722575-1B-C11-XX-40 Standard -40 34 9 30
M722575-1B-C14-CHT-40 Standard -40 31 7 30
M722575-1B-C17-XX-40 Standard -40 32 9 30
M722575-2A-C2-CHT-40 Standard -40 36 12 30
M722575-2A-C5-XX-40 Standard -40 32 11 30
M722575-2A-C8-CHT-40 Standard -40 35 11 30
M722575-2A-C11-XX-40 Standard -40 34 9 30
M722575-2A-C14-CHT-40 Standard -40 34 10 30
M722575-2A-C17-XX-40 Standard -40 34 12 30
M722575-2B-C2-CHT-40 Standard -40 32 7 30
M722575-2B-C5-XX-40 Standard -40 29 9 30
M722575-2B-C8-CHT-40 Standard -40 27 7 30
M722575-2B-C11-XX-40 Standard -40 31 8 30
M722575-2B-C14-CHT-40 Standard -40 32 9 30
M722575-2B-C17-XX-40 Standard -40 29 6 30
Table 5. Impact Results: ASTM E23-07a
Specimen ID Sample Size Temp. F Energy Mils Lat % Shear
ft-lbs Exp Fracture
M722575-1A-C3-XX-65 Standard -65 32 9 30
M722575-1A-C6-CHT-65 Standard -65 30 8 30
M722575-1A-C9-XX-65 Standard -65 28 7 30
M722575-1A-C12-CHT-65 Standard -65 30 9 30
M722575-1A-C15-XX-65 Standard -65 30 9 30
M722575-1A-C18-CHT-65 Standard -65 31 8 30
M722575-1B-C3-XX-65 Standard -65 27 5 30
M722575-1B-C6-CHT-65 Standard -65 27 7 30
M722575-1B-C9-XX-65 Standard -65 27 7 30
M722575-1B-C12-CHT-65 Standard -65 29 7 30
M722575-1B-C15-XX-65 Standard -65 26 5 30
M722575-1B-C18-CHT-65 Standard -65 23 5 30
M722575-2A-C3-XX-65 Standard -65 31 8 30
M722575-2A-C6-CHT-65 Standard -65 27 6 30
M722575-2A-C9-XX-65 Standard -65 31 9 30
M722575-2A-C12-CHT-65 Standard -65 30 9 30
M722575-2A-C15-XX-65 Standard -65 31 7 30
M722575-2A-C18-CHT-65 Standard -65 30 9 30
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M722575-2B-C3-XX-65 Standard -65 23 5 30
M722575-2B-C6-CHT-65 Standard -65 26 8 30
M722575-2B-C9-XX-65 Standard -65 25 6 30
M722575-2B-C12-CHT-65 Standard -65 25 5 30
M722575-2B-C15-XX-65 Standard -65 25 2 30
M722575-2B-C18-CHT-65 Standard -65 23 4 30
Table 6. Impact Results: ASTM E23-07a
Specimen ID Sample Size Temp. F Energy Mils Lat % Shear
ft-lbs Exp Fracture
M722575-1A-CI-CHT-RT Standard 74 50 18 50
M722575-1A-C4-XX-RT Standard 74 49 19 50
M722575-1A-C7-CHT-RT Standard 74 50 20 50
M722575-1A-C10-XX-RT Standard 74 51 17 50
M722575-1A-C13-CHT-RT Standard 74 53 17 50
M722575-1A-C16-XX-RT Standard 74 52 17 50
M722575-1B-CI-CHT-RT Standard 74 46 16 50
M722575-1B-C4-XX-RT Standard 74 48 14 50
M722575-1B-C7-CHT-RT Standard 74 51 20 50
M722575-1B-C10-XX-RT Standard 74 50 17 50
M722575-1B-C13-CHT-RT Standard 74 48 18 50
M722575-1B-C16-XX-RT Standard 74 45 14 50
M722575-2A-CI-CHT-RT Standard 74 55 21 50
M722575-2A-C4-XX-RT Standard 74 51 17 50
M722575-2A-C7-CHT-RT Standard 74 52 19 50
M722575-2A-C10-XX-RT Standard 74 52 13 50
M722575-2A-C13-CHT-RT Standard 74 51 16 50
M722575-2A-C16-XX-RT Standard 74 54 17 50
M722575-2B-CI-CHT-RT Standard 74 47 17 50
M722575-2B-C4-XX-RT Standard 74 45 14 50
M722575-2B-C7-CHT-RT Standard 74 46 15 50
M722575-2B-C10-XX-RT Standard 74 49 16 50
M722575-2B-C13-CHT-RT Standard 74 48 18 50
M722575-2B-C16-XX-RT Standard 74 46 18 50
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Table 7. Tensile Results: ASTM E8-08
ID UTS 0.2% Elong RA Mod. Ult. 0.2% Orig. Final 4D 4D Orig. Area
ksi YS % % Msi Load YLD Dia. Dia. Org Final (sq. in.)
ksi lbf lbf (in.) (in.) GL GL
(in.) (in.)
IA-C-TI 231.7 178.3 13 45 29.3 23002 17697 0.3555 0.2641 1.40 1.58 0.09925882
1A-T2 231.3 178.2 14 47 29.4 22957 17684 0.3555 0.2578 1.40 1.59 0.09925882
1A-C-T3 230.7 178.0 14 49 29.4 22926 17686 0.3557 0.2547 1.40 1.59 0.09937053
1A-T4 231.0 178.1 13 47 29.6 22889 17647 0.3552 0.2584 1.40 1.58 0.09909136
1A-C-T5 230.9 177.7 14 48 29.5 22935 17647 0.3556 0.2567 1.40 1.59 0.09931467
1A-T6 230.8 178.0 14 46 29.1 22990 17726 0.3561 0.2608 1.40 1.59 0.09959415
lB-C-TI 229.0 176.7 14 46 29.4 22728 17541 0.3555 0.2607 1.40 1.60 0.09925882
1B-T2 229.0 176.5 13 43 29.6 22730 17523 0.3555 0.2694 1.40 1.58 0.09925882
1B-C-T3 228.2 176.6 13 45 29.5 22731 17585 0.3561 0.2643 1.40 1.58 0.09959415
1B-T4 229.0 176.5 13 44 29.5 22780 17557 0.3559 0.2666 1.40 1.58 0.09948231
1B-C-T5 228.4 176.9 12 44 29.3 22675 17560 0.3555 0.2666 1.40 1.57 0.09925882
1B-T6 228.8 175.9 13 45 29.4 22802 17526 0.3562 0.2646 1.40 1.58 0.09965009
2A-C-T1 230.8 178.1 14 48 29.5 22933 17699 0.3557 0.2559 1.40 1.59 0.09937053
2A-T2 233.1 179.6 14 49 29.5 23227 17901 0.3562 0.2535 1.40 1.60 0.09965009
2A-C-T3 231.7 178.3 14 48 29.5 23008 17706 0.3556 0.2557 1.40 1.60 0.09931467
2A-T4 232.2 178.5 14 49 29.5 23074 17740 0.3557 0.2530 1.40 1.59 0.09937053
2A-C-T5 230.2 178.2 14 51 28.5 22864 17697 0.3556 0.2479 1.40 1.60 0.09931467
2A-T6 231.4 178.4 13 49 29.7 22985 17714 0.3556 0.2538 1.40 1.58 0.09931467
2B-C-T1 230.1 177.5 13 45 29.3 22888 17656 0.3559 0.2640 1.40 1.58 0.09948231
2B-T2 229.9 177.8 14 47 29.1 22879 17700 0.3560 0.2588 1.40 1.60 0.09953822
2B-C-T3 230.0 178.0 14 46 28.9 22892 17721 0.3560 0.2625 1.40 1.59 0.09953822
2B-T4 230.5 178.0 13 46 29.4 22914 17700 0.3558 0.2625 1.40 1.58 0.09942641
2B-C-T5 229.7 177.0 12 44 29.4 22834 17603 0.3558 0.2673 1.40 1.57 0.09942641
2B-T6 232.0 179.4 14 44 29.0 23064 17842 0.3558 0.2654 1.40 1.59 0.09942641
Therefore, particular embodiments are well adapted to attain the ends and
advantages mentioned as well as those that are inherent therein. Numerous
other
changes, substitutions, variations, alterations and modifications may be
ascertained by
those skilled in the art and it is intended that various embodiments encompass
all such
changes, substitutions, variations, alterations and modifications as falling
within the
spirit and scope of the appended claims.
