Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEMS AND METHODS FOR CORROSION-RESISTANT
WELDING ELECTRODES
CROS S-REFERENCE
[0001] This application claims priority from and the benefit of U.S.
Provisional
Application Serial No. 61/888,965, entitled "SYSTEMS AND METHODS FOR
CORROSION-RESISTANT WELDING ELECTRODES", filed October 9, 2013, U.S.
Provisional Application Serial No. 62/054,818, entitled "SYSTEMS AND METHODS
FOR CORROSION-RESISTANT WELDING ELECTRODES", filed September 24,
2014, which are hereby incorporated by reference in their entireties for all
purposes.
BACKGROUND
[0002] The invention relates generally to welding and, more specifically,
to electrodes
for arc welding, such as Gas Metal Arc Welding (GMAW) or Flux Core Arc Welding
(FCAW).
[0003] Welding is a process that has become ubiquitous in various
industries for a
variety of applications. For example, welding is often used in applications
such as
shipbuilding, offshore platform, construction, pipe mills, and so forth.
Certain welding
techniques (e.g., Gas Metal Arc Welding (GMAW), Gas-shielded Flux Core Arc
Welding (FCAW-G), and Gas Tungsten Arc Welding (GTAW)), typically employ a
shielding gas (e.g., argon, carbon dioxide, or oxygen) to provide a particular
local
atmosphere in and around the welding arc and the weld pool during the welding
process,
while others (e.g., Flux Core Arc Welding (FCAW), Submerged Arc Welding (SAW),
and Shielded Metal Arc Welding (SMAW)) do not. Additionally, certain types of
welding may involve a welding electrode in the form of welding wire. Welding
wire may
generally provide a supply of filler metal for the weld as well as provide a
path for the
current during the welding process. Furthermore, certain types of welding wire
(e.g.,
tubular welding wire) may include one or more components (e.g., flux, arc
stabilizers, or
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other additives) that may generally alter the welding process and/or the
properties of the
resulting weld.
BRIEF DESCRIPTION
[0004] In an embodiment, a tubular welding wire has a sheath and a core,
and the
tubular welding wire includes an organic stabilizer component, a rare earth
component,
and a corrosion resistant component comprising one or more of: nickel,
chromium, and
copper.
[0005] In an embodiment, a corrosion resistant weld deposit is formed on a
coated
workpiece. The weld deposit includes between approximately 0.5% and
approximately
21% chromium by weight, between approximately 0.02% and approximately 12%
nickel
by weight, and between approximately 0.05% and approximately 1% copper by
weight.
Additionally, the weld deposit has a porosity less than approximately 0.25
inches per inch
of the weld deposit.
[0006] In an embodiment, a method of manufacturing a tubular welding wire
includes
disposing a core within a metallic sheath. The core includes an organic
stabilizer
component including a sodium or potassium salt of an organic molecule or an
organic
polymer. The core includes a rare earth component including one or more
elements or
compounds of the lanthanide series. The core also includes an agglomerate
having
oxides of one or more of: potassium, sodium, silicon, titanium, and manganese.
The core
further includes a corrosion resistant component including one or more of:
nickel,
chromium, and copper. The method also includes compressing the metallic sheath
around the core to form the tubular welding wire.
DRAWINGS
[0007] These and other features, aspects, and advantages of the present
invention will
become better understood when the following detailed description is read with
reference
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to the accompanying drawings in which like characters represent like parts
throughout the
drawings, wherein:
[0008] FIG. 1
is a block diagram of a gas metal arc welding (GMAW) system, in
accordance with embodiments of the present disclosure;
[0009] FIG. 2
is a cross-sectional view of a tubular welding wire, in accordance with
embodiments of the present disclosure;
[0010] FIG. 3
is a process by which the tubular welding wire may be used to weld a
workpiece, in accordance with embodiments of the present disclosure; and
[0011] FIG. 4
is a process for manufacturing the tubular welding wire, in accordance
with embodiments of the present disclosure.
DETAILED DESCRIPTION
[0012] One or
more specific embodiments of the present disclosure will be described
below. In an effort to provide a concise description of these embodiments, all
features of
an actual implementation may not be described in the specification. It should
be
appreciated that in the development of any such actual implementation, as in
any
engineering or design project, numerous implementation-specific decisions must
be made
to achieve the developers' specific goals, such as compliance with system-
related and
business-related constraints, which may vary from one implementation to
another.
Moreover, it should be appreciated that such a development effort might be
complex and
time consuming, but would nevertheless be a routine undertaking of design,
fabrication,
and manufacture for those of ordinary skill having the benefit of this
disclosure.
[0013] When
introducing elements of various embodiments of the present disclosure,
the articles "a," "an," "the," and "said" are intended to mean that there are
one or more of
the elements. The terms "comprising," "including," and "having" are intended
to be
inclusive and mean that there may be additional elements other than the listed
elements.
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It should be appreciated that, as used herein, the term "tubular welding
electrode" or
"tubular welding wire" may refer to any welding wire or electrode having a
metal sheath
and a granular or powdered core, such as metal-cored or flux-cored welding
electrodes.
It should also be appreciated that the term "stabilizer" or "additive" may be
generally
used to refer to any component of the tubular welding that improves the
quality of the
arc, the quality of the weld, or otherwise affect the welding process.
Furthermore, as
used herein, "approximately" may generally refer to an approximate value that
may, in
certain embodiments, represent a difference (e.g., higher or lower) of less
than 0.01%,
less than 0.1%, or less than 1% from the actual value. That is, an
"approximate" value
may, in certain embodiments, be accurate to within (e.g., plus or minus)
0.01%, within
0.1%, or within 1% of the stated value. As used herein, a "stainless steel" is
any steel
that includes at least 10.5 % chromium by weight and at least 50% iron by
weight. A
non-limiting list of example stainless steels include: 200 series stainless
steel, 300 series
stainless steel, and 400 series stainless steel.
[0014] As mentioned, certain types of welding electrodes (e.g., tubular
welding wire)
may include one or more components (e.g., flux, arc stabilizers, or other
additives) that
may generally alter the welding process and the properties of the resulting
weld. For
example, certain presently disclosed welding electrode embodiments include one
or more
corrosion resistant components (e.g., nickel, chromium, copper, and/or alloys
or mixtures
thereof) that may enable a weld deposit to have enhanced or improved
resistance to
corrosion or oxidation. Additionally, certain presently disclosed welding
electrode
embodiments include an organic stabilizer (e.g., a derivatized cellulose-based
component) that may generally improve the stability of the arc while providing
a
reducing atmosphere conducive to welding coated workpieces (e.g., galvanized
or
nitrided workpieces). As used herein, an "organic stabilizer" may refer to an
organic salt
or organometallic compound having an organic portion (e.g., a carbon-based
molecule or
polymer chain) and a stabilizer portion (e.g., a Group I/II metal ion).
Certain presently
disclosed welding electrode embodiments also include a rare earth component
(e.g., a
lanthanide alloys, lanthanide silicides) that may generally help to control
the shape and
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penetration of the arc during welding. In certain embodiments, a metal sheath
having
lower carbon content may be used to provide, for example, a lower spatter
rate, reduced
welding fumes, and/or reduced penetration into the workpiece during welding.
Furthermore, in certain embodiments, the disclosed tubular welding wire may
have a
suitable composition to enable the formation of a weld deposit with a
relatively high
chromium content (e.g., 4 ¨ 6 wt% chromium), which may hold nitrogen in
solution
within the weld deposit to mitigate or prevent weld porosity. It may be
appreciated that
is especially useful to provide low porosity weld deposits (e.g., a porosity
less than
approximately 0.25 inches or less than approximately 0.10 inches per inch of
weld) when
welding workpieces that have a high nitrogen content (e.g., nitrided steel).
[0015]
Accordingly, in certain embodiments, the presently disclosed tubular welding
wires enhance the weldability of coated (e.g., galvanized, galvannealed,
aluminized,
nitrided, painted, and so forth) workpieces and/or thinner (e.g., 20-, 22-, 24-
gauge, or
thinner) workpieces, even at high travel speed (e.g., greater than 30 in/min
or greater than
40 in/min). Further, when a corrosion resistant weld is desirable, the
aforementioned
corrosion resistant components (e.g., nickel, chromium, copper, and/or alloys
or mixtures
thereof) within the sheath and/or the core of certain embodiments of the
disclosed tubular
welding wires may improve the corrosion resistance of the weld deposit
relative to a mild
steel weld deposit. In certain embodiments, the sheath of the disclosed
tubular welding
wires may be a corrosion resistant sheath, such as a stainless steel sheath
(e.g., 304, 409,
410, or 430 stainless steel) as defined by the American Welding Society (AWS)
A5.22.
Additionally, in certain embodiments, the corrosion resistant weld deposit
formed by the
disclosed tubular welding wires may be stainless weld deposits (e.g., 304,
409, 410, or
430 stainless steel), in accordance with AWS A5.22. The improved corrosion
resistance
enabled by certain embodiments of the disclosed tubular welding wires may
either
obviate or supplement certain post-weld process steps, such as preparing and
coating
(e.g., zinc plating) the weld deposit after deposition. Additionally, certain
presently
disclosed tubular welding wires may be drawn to particular diameters (e.g.,
0.024 in,
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0.030 in, 0.035 in, 0.0375 in, 0.040 in, or other suitable diameters) to
provide good heat
transfer and deposition rates and/or to enable the welding of thinner
workpieces.
[0016] Turning
to the figures, FIG. 1 illustrates an embodiment of a gas metal arc
welding (GMAW) system 10 that utilizes a welding electrode (e.g., tubular
welding wire)
in accordance with the present disclosure. It should be appreciated that,
while the present
discussion may focus specifically on the GMAW system 10 illustrated in FIG. 1,
the
presently disclosed welding electrodes may benefit any arc welding process
(e.g., FCAW,
FCAW-G, GTAW, SAW, SMAW, or similar arc welding process) that uses a welding
electrode. The welding system 10 includes a welding power source 12, a welding
wire
feeder 14, a gas supply system 16, and a welding torch 18. The welding power
source 12
generally supplies power to the welding system 10 and may be coupled to the
welding
wire feeder 14 via a cable bundle 20 as well as coupled to a workpiece 22
using a lead
cable 24 having a clamp 26. In the illustrated embodiment, the welding wire
feeder 14 is
coupled to the welding torch 18 via a cable bundle 28 in order to supply
consumable,
tubular welding wire (i.e., the welding electrode) and power to the welding
torch 18
during operation of the welding system 10. In another embodiment, the welding
power
unit 12 may couple and directly supply power to the welding torch 18.
[0017] The
welding power source 12 may generally include power conversion
circuitry that receives input power from an alternating current power source
30 (e.g., an
AC power grid, an engine/generator set, or a combination thereof), conditions
the input
power, and provides DC or AC output power via the cable 20. As such, the
welding
power source 12 may power the welding wire feeder 14 that, in turn, powers the
welding
torch 18, in accordance with demands of the welding system 10. The lead cable
24
terminating in the clamp 26 couples the welding power source 12 to the
workpiece 22 to
close the circuit between the welding power source 12, the workpiece 22, and
the welding
torch 18. The welding power source 12 may include circuit elements (e.g.,
transformers,
rectifiers, switches, and so forth) capable of converting the AC input power
to a direct
current electrode positive (DCEP) output, direct current electrode negative
(DCEN)
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output, DC variable polarity, pulsed DC, or a variable balance (e.g., balanced
or
unbalanced) AC output, as dictated by the demands of the welding system 10. It
should
be appreciated that the presently disclosed welding electrodes (e.g., tubular
welding wire)
may enable improvements to the welding process (e.g., improved arc stability
and/or
improved weld quality) for a number of different power configurations.
[0018] The
illustrated welding system 10 includes a gas supply system 16 that
supplies a shielding gas or shielding gas mixtures from one or more shielding
gas sources
17 to the welding torch 18. In the depicted embodiment, the gas supply system
16 is
directly coupled to the welding torch 18 via a gas conduit 32. In another
embodiment,
the gas supply system 16 may instead be coupled to the wire feeder 14, and the
wire
feeder 14 may regulate the flow of gas from the gas supply system 16 to the
welding
torch 18. A shielding gas, as used herein, may refer to any gas or mixture of
gases that
may be provided to the arc and/or weld pool in order to provide a particular
local
atmosphere (e.g., to shield the arc, improve arc stability, limit the
formation of metal
oxides, improve wetting of the metal surfaces, alter the chemistry of the weld
deposit,
and so forth). In certain embodiments, the shielding gas flow may be a
shielding gas or
shielding gas mixture (e.g., argon (Ar), helium (He), carbon dioxide (CO2),
oxygen (02),
nitrogen (N2), similar suitable shielding gases, or any mixtures thereof). For
example, a
shielding gas flow (e.g., delivered via the conduit 32) may include Ar, Ar/CO2
mixtures
(e.g., between 1% and 99% CO2 in Ar), Ar/CO2/02 mixtures, Ar/He mixtures, and
so
forth. By specific example, in certain embodiments, the shielding gas flow may
include
100% Ar; 75% Ar and 25% CO2; 90% Ar and 10% CO2; or 98% Ar and 2% 02.
[0019]
Accordingly, the illustrated welding torch 18 generally receives the welding
electrode (i.e., the tubular welding wire), power from the welding wire feeder
14, and a
shielding gas flow from the gas supply system 16 in order to perform GMAW of
the
workpiece 22. During operation, the welding torch 18 may be brought near the
workpiece 22 so that an arc 34 may be formed between the consumable welding
electrode
(i.e., the welding wire exiting a contact tip of the welding torch 18) and the
workpiece 22.
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Additionally, as discussed below, by controlling the composition of the
welding electrode
(i.e., the tubular welding wire), the chemistry of the arc 34 and/or the
resulting weld (e.g.,
composition and physical characteristics) may be varied. For example, the
welding
electrode may include fluxing or alloying components that may affect the
welding
process (e.g., act as arc stabilizers) and, further, may become at least
partially
incorporated into the weld, affecting the mechanical properties of the weld.
Furthermore,
certain components of the welding electrode (i.e., welding wire) may also
provide
additional shielding atmosphere near the arc, affect the transfer properties
of the arc 34,
deoxidize the surface of the workpiece, limit oxidation or corrosion in the
weld deposit,
and so forth.
[0020] A cross-
section of an embodiment of the presently disclosed welding wire is
illustrated in FIG. 2. FIG. 2 illustrates a tubular welding wire 50 that
includes a metallic
sheath 52, which encapsulates a granular or powdered core 54 (also referred to
as filler).
In certain embodiments, the tubular welding wire 50 may comply with one or
more AWS
standards. For example, in certain embodiments, the tubular welding wire 50
may be
classified in accordance with AWS A5.18 ("SPECIFICATION FOR CARBON STEEL
ELECTRODES AND RODS FOR GAS SHEILDED ARC WELDING"), or AWS A5.20
("CARBON STEEL ELECTRODES FOR FLUX CORED ARC WELDING"), or AWS
A5.29 ("SPECIFICATION FOR LOW ALLOY STEEL ELECTRODES FOR FLUX
CORED ARC WELDING"), or AWS A5.36 ("SPECIFICATION FOR CARBON AND
LOW-ALLOY STEEL FLUX CORED ELECTRODES FOR FLUX CORED ARC
WELDING AND METAL CORED ELECTRODES FOR GAS METAL ARC
WELDING"), or AWS A5.22 ("SPECIFICATION FOR STAINLESS STEEL FLUX
CORED AND METAL CORED WELDING ELECTRODES AND RODS"), or another
suitable AWS standard applicable to coated (e.g., galvanized, aluminized,
nitrided, etc.)
or uncoated mild steel, low-alloy steel, or weathering steel workpieces.
Additionally, in
certain embodiments, the disclosed tubular welding wire may not fall within an
existing
AWS standard. For example, in certain embodiments, the disclosed tubular
welding wire
may form martensitic weld deposits and, as such, may fall outside of an
existing AWS
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standard. However, such tubular welding wire embodiments may be useful, for
example,
as a hard-facing type wire used to form hard-facing weld deposits. It may be
appreciated
that, for such embodiments, the resulting martensitic weld deposit may be
subsequently
heat treated (e.g., at approximately 1200 F for approximately 1 hour or less)
to improve
the ductility of the weld deposit while still retaining its high strength.
However, it may
also be appreciated that such post-weld heat treatments may add time and cost
to the
welding operation and may cause deleterious distortions in certain types of
workpieces.
[0021] In
particular, certain embodiments of the tubular welding wire 50 may be
capable of providing quality welds on coated (e.g., galvanized, aluminized,
nitrided, etc.)
and uncoated mild steel workpieces. It may be appreciated that the
aforementioned
corrosion resistant components (e.g., nickel, chromium, copper, and/or
mixtures or alloys
thereof) of the tubular welding wire 50 may enable the formation of corrosion
resistant
weld deposits, and thereby alleviate or obviate certain process steps (e.g.,
cleaning and
coating the surface of the weld deposit). Further, elimination of such process
steps may
reduce welding process time and/or improve welding process efficiency. It may
also be
appreciated that, in certain embodiments, the tubular welding wire 50 may be
designed
for either single-pass or multi-pass welding operations. It may be appreciated
that,
generally speaking, single pass weld metal may be diluted by approximately 15%
and
50% by the base material of the workpiece, and, accordingly, the composition
of the
tubular welding wire 50 may be adjusted in order to provide particular target
concentrations of the corrosion resistant components in the resulting weld
deposit for a
particular type (e.g., single pass or multi-pass) of welding operation. By
specific
example, in certain embodiments, the tubular welding wire 50 may be capable of
achieving a weld deposit having ferritic stainless chemistry, in which a
minimum
chromium level (e.g., at least 2.5% chromium by weight of the weld deposit)
may be
provided to the weld deposit using a single pass welding operation to result
in a corrosion
resistant weld deposit on coated (e.g., galvanized, aluminized, nitrided) or
uncoated mild
steel workpieces, including workpieces having thicknesses of 0.3 inches or
less (e.g.,
gauge thicknesses).
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[0022] The
metallic sheath 52 of the tubular welding wire 50 illustrated in FIG. 2 may
be manufactured from any suitable metal or alloy, such as steel. It should be
appreciated
that the composition of the metallic sheath 52 may affect the composition of
the resulting
weld and/or the properties of the arc 34. In certain embodiments, the metallic
sheath 52
may account for between approximately 80% and 90% of the total weight of the
tubular
welding wire 50. For example, in certain embodiments, the metallic sheath 52
may
provide or account for between approximately 84% and approximately 86% of the
total
weight of the tubular welding wire 50. As mentioned, in certain embodiments,
the
metallic sheath 52 may be manufactured from 304, 409, 410, or 430 stainless
steel, as
defined by AWS A5.22.
[0023] In
certain embodiments, the metallic sheath 52 may include certain additives or
impurities (e.g., alloying components, carbon, alkali metals, manganese, or
similar
compounds or elements) that may be selected to provide desired weld
properties. For
example, in certain embodiments, the metallic sheath 52 of the tubular welding
wire 50
may be a low-carbon strip that includes a relatively small (e.g., lower or
reduced) amount
of carbon. In certain embodiments, the carbon content of the metallic sheath
52 may
account for less than approximately 0.01%, less than approximately 0.02%, less
than
approximately 0.03%, less than approximately 0.04%, less than approximately
0.05%,
less than approximately 0.06%, less than approximately 0.07%, less than
approximately
0.08%, less than approximately 0.09%, or less than approximately 0.1% of the
weight of
the entire tubular welding wire 50. Additionally, in certain embodiments, the
metallic
sheath 52 may be made of steel (e.g., low-carbon steel) generally having a
small number
of inclusions. For example, in certain embodiments, the manganese content of
the
metallic sheath 52 may account for between approximately 0.25% and
approximately
0.5%, or approximately 0.34% or approximately 0.35% manganese of the weight of
the
tubular welding wire 50. By further example, in certain embodiments, the
metallic sheath
52 may have a phosphorus content that is less than approximately 0.02% of the
total
weight of the tubular welding wire 50 and/or a sulfur content that is less
than
approximately 0.02% of the total weight of the tubular welding wire 50. The
metallic
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sheath 52, in certain embodiments, may also provide less a silicon content
that is less
than approximately 0.04% of the weight of the tubular welding wire 50, an
aluminum
content that is less than approximately 0.05% of the weight of the tubular
welding wire
50, a copper content that is less than approximately 0.1% of the weight of the
tubular
welding wire 50, and/or a tin content that is less than approximately 0.02% of
the weight
of the tubular welding wire 50. Accordingly, in certain embodiments, the iron
content of
the metallic sheath 52 may account for more than approximately 80% (e.g., 84%,
85%) of
the weight of the tubular welding wire 50. As mentioned above, in certain
embodiments,
one or more of the corrosion resistant components (e.g., nickel, chromium,
copper) may
be incorporated into the metallic sheath 52 in alternative or in addition to
the granular
core 54.
[0024] The
granular core 54 of the illustrated tubular welding wire 50 may generally
be a compacted powder. In certain embodiments, the granular core 54 may
account for
between approximately 5% and approximately 40% or between approximately 10%
and
approximately 20% of the total weight of the tubular welding wire 50. For
example, in
certain embodiments, the granular core 54 may provide approximately 14%,
approximately 15%, approximately 16%, or approximately 20% of the total weight
of the
tubular welding wire 50. Furthermore, in certain embodiments, the components
of the
granular core 54, discussed below, may be homogenously or non-homogenously
(e.g., in
clumps or clusters 56) disposed within the granular core 54. For example, the
granular
core 54 of certain flux-cored and metal-cored welding electrode embodiments
may
include one or more metals (e.g., iron, iron titanium, iron silicon, or other
alloys or
metals) that may provide at least a portion of the filler metal for the weld
deposit. By
specific example, in certain embodiments, the granular core 54 may include
between
approximately 0% and approximately 60% iron powder, as well as other alloying
components, such as ferro-titanium (e.g., 40% grade), ferro-magnesium-silicon,
and
ferro-silicon powder (e.g., 50% grade, unstabilized). Other examples of
components that
may be present within the tubular welding wire 50 (i.e., in addition to the
one or more
carbon sources and the one or more alkali metal and/or alkali earth metal
compounds)
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include other stabilizing, fluxing, and alloying components, such as may be
found in
METALLOY XCELTM welding electrodes available from Illinois Tool Works Inc.
[0025] In
certain embodiments of the tubular welding wire 50, the total percentage of
the combination of the one or more carbon sources and the one or more alkali
metal
and/or alkali earth metal compounds may be between approximately 0.01% and
approximately 10% by weight, relative to the granular core 54 or the entire
tubular
welding wire 50. For example, in certain embodiments, the total percentage of
the
combination of the one or more carbon sources and the one or more alkali metal
and/or
alkali earth metal may be between approximately 0.01% and approximately 8%,
between
approximately 0.05% and approximately 5%, or between approximately 0.1% and
approximately 4% of the granular core 54 or of the tubular welding wire 50 by
weight.
By specific example, in certain embodiments, the granular core 54 may include
a carbon
source and a potassium source that together account for approximately 10% or
less of the
granular core 54 by weight. It should be appreciated that, under the
conditions of the arc
34, the components of the welding wire 50 (e.g., the metal sheath 52, the
granular core
54, and so forth) may change physical state, chemically react (e.g., oxidize,
decompose,
and so forth), or become incorporated into the weld substantially unmodified
by the weld
process.
[0026] In
certain embodiments, the tubular welding wire 50 may include (e.g., in the
metallic sheath 52 and/or the granular core 54) one or more metals or alloys
that may
limit, block, or prevent corrosion within the weld deposit after deposition.
For example,
in certain embodiments, the metallic sheath 52 and/or the granular core 54 may
include
one or more of nickel (Ni), chromium (Cr), copper (Cu), and mixtures or alloys
thereof,
that may limit corrosion of the weld deposit by reactive species, such as
oxygen. By
specific example, in certain embodiments, chromium may account for between
approximately 0.1% and approximately 20%, between approximately 0.2% and
approximately 18%, between approximately 0.3% and approximately 17%, between
approximately 0.4% and approximately 16%, between approximately 0.5% and
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approximately 15.8%, approximately 0.6%, between approximately 4% and 6%,
approximately 2.5%, or approximately 16% of the tubular welding wire 50 by
weight.
Further, in certain embodiments, chromium may account for between
approximately
0.5% and approximately 90% or between approximately 4% and approximately 80%
of
the weight of the core 54. As mentioned, in certain embodiments, the tubular
welding
wire 50 may be designed to provide a weld deposit having a relatively high
chromium
content (e.g., a weld deposit having at least 3%, 4%, or 5% chromium by
weight), to
enable the formation of low porosity welds on base materials that are high in
nitrogen
(e.g., nitrided steel base materials).
[0027] By
further example, in certain embodiments, nickel may account for between
approximately 0% and approximately 5%, between approximately 0.1% and
approximately 2.5%, between approximately 0.2% and approximately 2%, between
approximately 0.3% and approximately 1%, between approximately 0.4% and
approximately 0.8%, or approximately 0.6% of the tubular welding wire 50 by
weight. In
certain embodiments, nickel may account for between approximately 0.5% and
approximately 10%, between approximately 1% and approximately 5%, or
approximately
4% of the weight of the core 54. In certain embodiments, copper may account
for
between approximately 0% and approximately 2%, between approximately 0.1% and
approximately 1%, between approximately 0.25% and approximately 0.9%, between
approximately 0.3% and approximately 0.75%, or approximately 0.6% of the
tubular
welding wire 50 by weight. Further, in certain embodiments, copper may account
for
between approximately 0.5% and approximately 10%, between approximately 1% and
approximately 5%, or approximately 4% of the weight of the core 54.
[0028]
Additionally, in certain embodiments, molybdenum (Mo) may be present in
the tubular welding wire 50 in order to capture carbon during the welding
process, which
may increase the availability of chromium for corrosion resistance. For
example, in
certain embodiments, molybdenum may be present in an amount that is
approximately
40% of the amount of chromium (by weight) in the tubular welding wire 50. By
specific
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example, in certain embodiments, molybdenum may account for between
approximately
0.01% and approximately 5%, between approximately 0.02% and approximately 4%,
between approximately 0.03% and approximately 3%, between approximately 0.05%
and
approximately 1.5%, between approximately 0.08% and approximately 1.2%, or
approximately 0.09% of the tubular welding wire 50 by weight. In other
embodiments,
titanium or niobium may be used in lieu of molybdenum in similar amounts to
provide a
similar effect.
[0029]
Additionally, presently disclosed embodiments of the tubular welding wire 50
may include an organic stabilizer disposed in the granular core 54. The
organic stabilizer
may be any organic molecule that includes one or more alkali metal ions (e.g.,
Group I:
lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs)) or
alkali earth
metal ions (e.g., Group II: beryllium (Be), magnesium (Mg), calcium (Ca),
strontium
(Sr), or barium (Ba)). That is, in certain embodiments, the organic stabilizer
includes an
organic subcomponent (e.g., an organic molecule or polymer), which includes
carbon,
hydrogen, and oxygen, and may be chemically (e.g., covalently or ionically)
bonded to
the alkali metal or alkali earth metal ions. In other embodiments, the organic
stabilizer
may include an organic sub-component (e.g., an organic molecule or polymer,
such as
cellulose) that has been mixed with (e.g., not chemically bonded with) the
alkali metal
and/or alkali earth metal salt (e.g., potassium oxide, potassium sulfate,
sodium oxide,
etc.).
[0030] By
specific example, in certain embodiments, the organic stabilizer may be a
cellulose-based (e.g., cellulosic) component including a cellulose chain that
has been
derivatized to form a sodium or potassium salt (e.g., sodium or potassium
carboxymethyl
cellulose). For example, in certain embodiments, the cellulose-based organic
stabilizer
may be sodium carboxymethyl cellulose having a degree of substitution (DS)
ranging
from approximately 0.5 and approximately 2.5. In general, the DS of a
derivatized
cellulose may be a real number between 0 and 3, representing an average number
of
substituted hydroxyl moieties in each monomer unit of the polysaccharide. In
other
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embodiments, the organic stabilizer may be other organic molecules that
include one or
more Group I/Group II ions. For example, in certain embodiments, the organic
stabilizer
may include derivatized sugars (e.g., derivatized sucrose, glucose, etc.) or
polysaccharides having one or more carboxylic acids or sulfate moieties
available to form
an alkali metal or alkali earth metal salt. In other embodiments, the organic
stabilizer
may include soap-like molecules (e.g., sodium dodecyl sulfate or sodium
stearate) or
alginates. Additionally, in certain embodiments, the organic stabilizer may
account for
less than approximately 10%, between approximately 0.05% and approximately 5%,
between approximately 0.1% and approximately 3%, between approximately 0.25%
and
approximately 2.5%, between approximately 0.5% and approximately 1.5%,
approximately 0.75%, or approximately 1% of the granular core 54 by weight.
Additionally, in certain embodiments, the organic stabilizer may account for
less than
approximately 5%, between approximately 0.05% and approximately 3%, between
approximately 0.08% and approximately 2%, between approximately 0.1% and
approximately 1%, or approximately 0.15% of the tubular welding wire 50 by
weight.
[0031] It may
be appreciated that the organic stabilizer component of the tubular
welding wire 50 may be maintained at a suitable level such that a reducing
environment
(e.g., hydrogen-rich) may be provided near the welding arc, but without
introducing
substantial porosity into the weld. It should further be appreciated that
utilizing an
organic molecule as a delivery vehicle for at least a portion of the Group
I/Group II ions
to the welding arc, as presently disclosed, may not be widely used since
organic
molecules may generate hydrogen under the conditions of the arc, which may
result in
porous and/or weak welds for mild steels. However, as set forth below, using
the
presently disclosed organic stabilizers afford quality welds (e.g., low-
porosity welds),
even when welding at high travel speed on coated (e.g., galvanized,
aluminized, nitrided)
and/or thin workpieces.
[0032]
Additionally, certain presently disclosed embodiments of the tubular welding
wire 50 may also include a carbon component disposed in the granular core 54.
For
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example, the carbon source present in the granular core 54 and/or the metal
sheath 52
may be in a number of forms and may stabilize the arc 34 and/or increase the
carbon
content of the weld. For example, in certain embodiments, graphite, graphene,
nanotubes, fullerenes and/or similar substantially sp2-hybridized carbon
sources may be
utilized as the carbon source in the tubular welding wire 50. Furthermore, in
certain
embodiments, graphene or graphite may be used to also provide other components
(e.g.,
moisture, gases, metals, and so forth) that may be present in the interstitial
space between
the sheets of carbon. In other embodiments, substantially sp3-hybridized
carbon sources
(e.g., micro- or nano-diamond, carbon nanotubes, buckyballs) may be used as
the carbon
source. In still other embodiments, substantially amorphous carbon (e.g.,
carbon black,
lamp black, soot, and/or similar amorphous carbon sources) may be used as the
carbon
source. Furthermore, while the present disclosure may refer to this component
as a
"carbon source," it should be appreciated that the carbon source may be a
chemically
modified carbon source that may contain elements other than carbon (e.g.,
oxygen,
halogens, metals, and so forth). For example, in certain embodiments, the
tubular
welding wire 50 may include a carbon black component in the granular core 54
that may
contain a manganese content of approximately 20%. In certain embodiments, the
carbon
component of the tubular welding wire 50 may be powdered or granular graphite.
[0033] In
certain embodiments, the carbon component may account for between
approximately 0.01% and approximately 9.9%, between approximately 0.05% and
approximately 5%, between approximately 0.1% and approximately 3%, between
approximately 0.25% and approximately 2%, between approximately 0.4% and
approximately 1%, or approximately 0.5% of the granular core 54 by weight.
Additionally, in certain embodiments, the carbon component may account for
less than
approximately 10%, between approximately 0.01% and approximately 5%, between
approximately 0.05% and approximately 2.5%, between approximately 0.1% and
approximately 1%, or approximately 0.5% of the granular core 54 by weight. In
certain
embodiments, the carbon component may account for less than approximately 5%,
between approximately 0.01% and approximately 2.5%, between approximately
0.05%
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and approximately 0.1%, or approximately 0.08% of the tubular welding wire 50
by
weight. In certain embodiments, the granular core 54 may not include a carbon
component.
[0034]
Furthermore, in addition to the organic stabilizer discussed above, the
tubular
welding wire 50 may also include one or more inorganic stabilizers to further
stabilize the
arc 34. That is, the granular core 54 of the tubular welding wire 50 may
include one or
more compounds of the Group 1 and Group 2 elements (e.g., Li, Na, K, Rb, Cs,
Be, Mg,
Ca, Sr, Ba). A non-limiting list of example compounds include: Group 1 (i.e.,
alkali
metal) and Group 2 (i.e., alkaline earth metal) silicates, titanates,
manganese titanate,
alginates, carbonates, halides, phosphates, sulfides, hydroxides, oxides,
permanganates,
silicohalides, feldspars, pollucites, molybdenites, and molybdates. For
example, in an
embodiment, the granular core 54 of the tubular welding wire 50 may include
potassium
manganese titanate, potassium sulfate, sodium feldspar, potassium feldspar,
and/or
lithium carbonate. By specific example, the granular core 54 may include
potassium
silicate, potassium titanate, potassium alginate, potassium carbonate,
potassium fluoride,
potassium phosphate, potassium sulfide, potassium hydroxide, potassium oxide,
potassium permanganate, potassium silicofluoride, potassium feldspar,
potassium
molybdates, or a combination thereof as the potassium source. In certain
embodiments,
the one or more alkali metal and/or alkaline earth metal compounds may include
Group 1
and Group 2 salts of carboxymethyl cellulose (e.g., sodium carboxymethyl
cellulose or
potassium carboxymethyl cellulose). Similar examples of stabilizing compounds
that
may be used are described in U.S. Application Serial No. 13/596,713, entitled
"SYSTEMS AND METHODS FOR WELDING ELECTRODES," and U.S. Patent No.
7,087,860, entitled "STRAIGHT POLARITY METAL CORED WIRES," and U.S.
Patent No. 6,723,954, entitled "STRAIGHT POLARITY METAL CORED WIRE,"
which are incorporated by reference in their entireties for all purposes.
[0035]
Furthermore, for certain embodiments of the presently disclosed tubular
welding wire 50, one or more inorganic stabilizers may be included in the
granular core
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54 in the form of an agglomerate or frit. That is, certain embodiments of the
tubular
welding wire 50 may include one or more of the inorganic stabilizers described
above in
an agglomerate or frit that may stabilize the arc during welding. The term
"agglomerate"
or "frit," as used herein, refers to a mixture of compounds that have been
fired or heated
in a calciner or oven such that the components of the mixture are in intimate
contact with
one another. It should be appreciated that the agglomerate may have subtly or
substantially different chemical and/or physical properties than the
individual
components of the mixture used to form the agglomerate. For example,
agglomerating,
as presently disclosed, may provide a frit that is better suited for the weld
environment
than the non-agglomerated materials.
[0036] In
certain embodiments, the granular core 54 of the tubular welding wire 50
may include an agglomerate or frit of one or more alkali metal or alkaline
earth metal
compounds (e.g., potassium oxide, sodium oxide, calcium oxide, magnesium
oxide, or
other suitable alkali metal or alkaline earth metal compound). In other
embodiments, the
granular core 54 of the tubular welding wire 50 may include an agglomerate of
a mixture
of alkali metal or alkaline earth metal compound and other oxides (e.g.,
silicon dioxide,
titanium dioxide, manganese dioxide, or other suitable metal oxides). For
example, one
embodiment of a tubular welding wire 50 may include an agglomerated potassium
source
including of a mixture of potassium oxide, silica, and titania. By further
example,
another embodiment of a tubular welding wire 50 may include in the granular
core 54
another stabilizing agglomerate having a mixture of potassium oxide (e.g.,
between
approximately 22% and 25% by weight), silicon oxide (e.g., between
approximately 10%
and 18% by weight), titanium dioxide (e.g., between approximately 38% and 42%
by
weight), and manganese oxide or manganese dioxide (e.g., between approximately
16%
and 22% by weight). In certain embodiments, an agglomerate may include between
approximately 5% and 75% alkali metal and/or alkaline earth metal compound
(e.g.,
potassium oxide, calcium oxide, magnesium oxide, or other suitable alkali
metal and/or
alkaline earth metal compound) by weight, or between approximately 5% and 95%
alkali
metal and/or alkaline earth metal (e.g., potassium, sodium, calcium,
magnesium, or other
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suitable alkali metal and/or alkaline earth metal) by weight. Furthermore, in
certain
embodiments, other chemical and/or physical factors (e.g., maximizing alkali
metal
and/or alkaline earth metal loading, acidity, stability, and/or hygroscopicity
of the
agglomerate) may be considered when selecting the relative amounts of each
component
present in the agglomerate mixture. In certain embodiments, the agglomerate
may
account for between approximately 0.01% and approximately 9.9%, between
approximately 0.05% and approximately 5%, between approximately 0.1% and
approximately 4%, between approximately 1% and approximately 3%, between
approximately 1.5% and approximately 2.5%, or approximately 2% of the granular
core
54 by weight. Additionally, in certain embodiments, the agglomerate may
account for
less than approximately 10%, between approximately 0.1% and approximately 6%,
between approximately 0.25% and approximately 2.5%, between approximately 0.5%
and approximately 1.5%, approximately 1%, or approximately 0.75% of the
granular core
54 by weight. In certain embodiments, the agglomerate may account for less
than
approximately 5%, between approximately 0.05% and approximately 2.5%, between
approximately 0.1% and approximately 0.5%, or approximately 0.75% of the
tubular
welding wire 50 by weight.
[0037] Additionally, the granular core 54 of the tubular welding wire 50
may also
include other components to control the welding process. For example, rare
earth
elements may generally affect the stability and heat transfer characteristics
of the arc 34.
As such, in certain embodiments, the tubular welding wire 50 may include a
rare earth
component, such as the Rare Earth Silicide (e.g., available from Miller and
Company of
Rosemont, Illinois), which may include rare earth elements (e.g., elements of
the
lanthanide series), non-rare earth elements (e.g., iron and silicon), and
compounds thereof
(e.g., cerium silicide, lanthanum silicide, etc.). In other embodiments, any
lanthanide
element, alloy, or compound (e.g., cerium silicide, lanthanum silicide, nickel
lanthanum
alloys, etc.) may be used in an amount that does not negate the effect of the
present
approach. By specific example, in certain embodiments, the rare earth
component may
account for less than approximately 10%, between approximately 0.01% and
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approximately 8%, between approximately 0.5% and approximately 5%, between
approximately 0.25% and approximately 4%, between approximately 1% and
approximately 3%, between approximately 0.75% and approximately 2.5%,
approximately 2%, or approximately 1.5% of the granular core 54 by weight. In
certain
embodiments, the rare earth component may account for less than approximately
5%,
between approximately 0.01% and approximately 2.5%, between approximately 0.1%
and approximately 0.75%, or approximately 0.3% of the tubular welding wire 50
by
weight.
[0038] Furthermore, the tubular welding wire 50 may, additionally or
alternatively,
include other elements and/or minerals to provide arc stability and to control
the
chemistry of the resulting weld. For example, in certain embodiments, the
granular core
54 and/or the metallic sheath 52 of the tubular welding wire 50 may include
certain
elements (e.g., titanium, manganese, zirconium, fluorine, or other elements)
and/or
minerals (e.g., pyrite, magnetite, and so forth). By
specific example, certain
embodiments may include zirconium silicide, nickel zirconium, or alloys of
titanium,
aluminum, and/or zirconium in the granular core 54. In particular, sulfur
containing
compounds, including various sulfide, sulfate, and/or sulfite compounds (e.g.,
such as
molybdenum disulfide, iron sulfide, manganese sulfite, barium sulfate, calcium
sulfate, or
potassium sulfate) or sulfur-containing compounds or minerals (e.g., pyrite,
gypsum, or
similar sulfur-containing species) may be included in the granular core 54 to
improve the
quality of the resulting weld by improving bead shape and facilitating slag
detachment,
which may be especially useful when welding galvanized workpieces, as
discussed
below. Furthermore, in certain embodiments, the granular core 54 of the
tubular welding
wire 50 may include multiple sulfur sources (e.g., manganese sulfite, barium
sulfate, and
pyrite), while other embodiments of the tubular welding wire 50 may include
only a
single sulfur source (e.g., potassium sulfate) without including a substantial
amount of
another sulfur source (e.g., pyrite or iron sulfide). For example, in an
embodiment, the
granular core 54 of the tubular welding wire 50 may include between
approximately 0.01
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% and approximately 0.5%, or approximately 0.15% or 0.2% potassium sulfate by
weight
of the granular core 54.
[0039]
Generally speaking, the tubular welding wire 50 may generally stabilize the
formation of the arc 34 to the workpiece 22. As such, the disclosed tubular
welding wire
50 may improve more than one aspect of the welding process (e.g., deposition
rate, travel
speed, splatter, bead shape, weld quality, etc.). It should further be
appreciated that the
improved stability of the arc 34 may generally enable and improve the welding
of coated
metal workpieces and thinner workpieces. For example, in certain embodiments,
the
coated metal workpieces may include galvanized, galvannealed (e.g., a
combination of
galvanization and annealing), or similar zinc-coated workpieces. A non-
limiting list of
example coated workpieces further includes painted, sealed, dipped, plated
(e.g., nickel-
plated, copper-plated, tin-plated, or electroplated or chemically plated using
a similar
metal), chromed, nitrided, aluminized, or carburized workpieces. For example,
in the
case of galvanized workpieces, the presently disclosed tubular welding wire 50
may
generally improve the stability and control the penetration of the arc 34 such
that a good
weld may be achieved despite the zinc coating on the outside of the workpiece
22.
Additionally, by improving the stability of the arc 34, the disclosed tubular
welding wire
50 may generally enable the welding of thinner workpieces than may be possible
using
other welding electrodes. For example, in certain embodiments, the disclosed
tubular
welding wire 50 may be used to weld metal having an approximately 14-, 16-, 18-
, 20-,
22-, 24-gauge, or even thinner workpieces. For example, in certain
embodiments, the
disclosed tubular welding wire 50 may enable welding workpieces having a
thickness
less than approximately 5 mm, less than 3 mm, less than approximately 1.5 mm,
less than
approximately 1.27 mm (e.g., approximately 0.05 inches), less than
approximately 1.11
mm (e.g., approximately 0.0438 inches), or at approximately 1 mm (e.g.,
approximately
0.0375 inches).
[0040]
Furthermore, the presently disclosed tubular welding wire 50 enables welding
(e.g., welding of thin gauge galvanized steels) at travel speeds in excess of
30 or even 40
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inches per minute. For example, the tubular welding wire 50 readily enables
high quality
fillet welds at travel speeds above 40 inches per minute (e.g., 35 or 45
inches per minute)
with low weld porosity. That is, the presently disclosed tubular welding wire
50 may
enable higher (e.g., 50% to 75% higher) travel speeds than other solid-cored,
metal-
cored, or flux-cored welding wires. It should be appreciated that higher
travel speeds
may enable higher production rates (e.g., on a production line) and reduce
costs.
Additionally, the presently disclosed tubular welding wire 50 exhibits good
gap handling
and provides excellent weld properties (e.g., strength, ductility, appearance,
and so forth)
using a wide operating process window. Further, the tubular welding wire 50
generally
produces less smoke and spatter than other solid-cored, metal-cored, or flux-
cored
welding wires.
[0041]
Furthermore, the disclosed tubular welding wire 50 may also be combined with
certain welding methods or techniques (e.g., techniques in which the welding
electrode
moves in a particular manner during the weld operation) that may further
increase the
robustness of the welding system 10 for particular types of workpieces. For
example, in
certain embodiments, the welding torch 18 may be configured to cyclically or
periodically move the electrode in a desired pattern (e.g., a circular, spin
arc, or
serpentine pattern) within the welding torch 18 in order to maintain an arc 34
between the
tubular welding wire 50 and the workpiece 22 (e.g., only between the sheath 52
of the
tubular welding wire 50 and the workpiece 22). By specific example, in certain
embodiments, the disclosed tubular welding wire 50 may be utilized with
welding
methods such as those described in U.S. Provisional Patent Application Serial
No.
61/576,850, entitled "DC ELECTRODE NEGATIVE ROTATING ARC WELDING
METHOD AND SYSTEM,"; in U.S. Patent Application Serial No. 13/681,687,
entitled
"DC ELECTRODE NEGATIVE ROTATING ARC WELDING METHOD AND
SYSTEM"; and in U.S. Provisional Patent Application Serial No. 61/676,563,
entitled
"ADAPTABLE ROTATING ARC WELDING METHOD AND SYSTEM"; which are
all incorporated by reference herein in their entireties for all purposes. It
should be
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appreciated that such welding techniques may be especially useful when welding
thin
workpieces (e.g., having 20-, 22-, or 24-gauge thickness), as mentioned above.
[0042] FIG. 3
illustrates an embodiment of a process 60 by which a workpiece 22 may
be welded using the disclosed welding system 10 and tubular welding wire 50.
The
illustrated process 60 begins with feeding (block 62) the tubular welding
electrode 50
(i.e., the tubular welding wire 50) to a welding apparatus (e.g., welding
torch 18). As set
forth above, in certain embodiments, the tubular welding wire 50 may include,
for
example, one or more corrosion resistant components (e.g., nickel, chromium,
copper, or
mixtures or alloys thereof), organic stabilizer components (e.g., sodium
carboxymethyl
cellulose), and one or more rare earth components (e.g., rare earth silicide).
Further, the
tubular welding wire 50 may have an outer diameter between approximately 0.024
in and
approximately 0.062 in, between approximately 0.030 in and approximately 0.060
in,
between 0.035 in and approximately 0.052 in, or approximately 0.040 in. It may
also be
appreciated that, in certain embodiments, the welding system 10 may feed the
tubular
welding wire 50 at a suitable rate to enable a travel speed greater than 30
in/min or
greater than 40 in/min.
[0043]
Additionally, the process 60 includes providing (block 64) a shielding gas
flow
(e.g., 100% argon, 100% carbon dioxide, 75% argon / 25% carbon dioxide, 90%
argon /
10% carbon dioxide, or similar shielding gas flow) near the contact tip of the
welding
apparatus (e.g., the contact tip of the torch 18). In other embodiments,
welding systems
may be used that do not use a gas supply system (e.g., such as the gas supply
system 16
illustrated in FIG. 1) and one or more components (e.g., potassium carbonate)
of the
tubular welding wire 50 may decompose to provide a shielding gas component
(e.g.,
carbon dioxide).
[0044] Next,
the tubular welding wire 50 may be brought near (block 66) the
workpiece 22 to strike and sustain an arc 34 between the tubular welding wire
50 and the
workpiece 22. It should be appreciated that the arc 34 may be produced using,
for
example, a DCEP, DCEN, DC variable polarity, pulsed DC, balanced or unbalanced
AC
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power configuration for the GMAW system 10. Once the arc 34 has been
established to
the workpiece 22, a portion of the tubular welding wire 50 (e.g., filler
metals and alloying
components) may be transferred (block 68) into the weld pool on the surface of
the
workpiece 22 to form a weld bead of a weld deposit. Meanwhile, the other
components
of the tubular welding wire 50 may be released (block 70) from the tubular
welding wire
50 to serve as arc stabilizers, slag formers, and/or deoxidizers to control
the electrical
characteristics of the arc and the resulting chemical and mechanical
properties of the
weld deposit.
[0045] It is
believed that, for certain embodiments, the Group I or Group II metals
(e.g., potassium and sodium ions) of the organic stabilizer may generally
separate from
the organic stabilizer and provide a stabilization effect to the arc.
Meanwhile, it is
believed that the organic portion (e.g., comprising at least carbon and
hydrogen, but
possibly including oxygen) may decompose under the conditions of the arc to
provide a
reducing (e.g., rich in hydrogen) atmosphere at or near the welding site.
Accordingly,
while not desiring to be bound by theory, it is believed that the resulting
reducing
atmosphere, and in potential combination with the Group I/Group II stabilizing
metals,
the rare earth components, cyclical motion, and so forth, presently disclosed,
provides a
welding solution enabling high travel speeds and low-porosity, even when
welding
coated workpieces or performing gap fills. For example, in certain
embodiments, the
tubular welding wire 50 may generally enable the welding of thinner workpieces
as well
as painted, galvanized, galvannealed, plated, aluminized, nitrided, chromed,
carburized,
or other similar coated workpieces. For example, certain embodiments of the
presently
disclosed tubular welding wire 50 may enable welding workpieces having
thicknesses
less than 5 mm or less than 4 mm, or workpieces having thicknesses of
approximately 1.3
mm or 1.2 mm, while maintaining relatively high travel speed (e.g., in excess
of 30
in/min or in excess of 40 in/min) and low-porosity, even when performing gap
fills (e.g.,
1-3 mm gap fills).
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[0046]
Furthermore, it may be appreciated that, for embodiments in which corrosion
resistance is desirable, the process 60 illustrated in FIG. 3 may not
necessarily include
additional processing steps to prepare and coat the weld deposit. That is, the
corrosion
resistant components of the tubular welding wire 50 may enable the formation
of an as-
welded corrosion resistant (e.g., rust or oxidation resistant) weld deposit
that may obviate
additional processing steps that are commonly used for coated workpieces. In
other
words, when welding a coated (e.g., galvanized, nitrided) workpiece using
other welding
electrodes, after formation of the weld deposit, the surface of the weld
deposit and the
workpiece may be cleaned, prepared to receive a coating, and then coated with
the
coating to provide corrosion resistance to the workpiece. For example, after
formation of
a weld deposit using other welding electrodes, the surface of the weld deposit
and the
workpiece may be cleaned with a wire brush and then plated with zinc or
painted with a
zinc-based spray paint.
[0047] It may
be appreciated that the corrosion resistance afforded by the
aforementioned additional processing steps may be limited by how well the
operator
cleans, prepares, and coats the workpiece. In contrast, after formation of a
weld deposit
using the presently disclosed tubular welding wire 50, the weld deposit will
include at
least a portion of the corrosion resistant components of the tubular welding
wire 50,
which provides corrosion resistance to the weld deposit while obviating the
additional
cleaning, preparing, and coating processing steps. However, it may also be
appreciated
that, in certain embodiments of the present approach, the corrosion resistant
weld deposit
formed using the disclosed tubular welding wire 50 may undergo the
aforementioned
cleaning, preparing, and coating processing steps to provide even greater
corrosion
resistance to the workpiece. In such circumstances, a corrosion resistant weld
deposit
may ensure that the weld deposit and/or workpiece maintains a level of
corrosion
resistance even if the operator does a relatively poor job cleaning,
preparing, and/or
coating the workpiece.
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[0048] FIG. 4
illustrates an embodiment of a process 80 by which the tubular welding
wire 50 may be manufactured. It may be appreciated that the process 80 merely
provides
an example of manufacturing a tubular welding wire 50; however, in other
embodiments,
other methods of manufacturing may be used to produce the tubular welding wire
50
without negating the effect of the present approach. That is, for example, in
certain
embodiments, the tubular welding wire 50 may be formed via a roll-forming
method or
via packing the core composition into a hollow metallic sheath. The process 80
illustrated in FIG. 4 begins with a flat metal strip being fed (block 82)
through a number
of dies that shape the strip into a partially circular metal sheath 52 (e.g.,
producing a
semicircle or trough). After the metal strip has been at least partially
shaped into the
metal sheath 52, it may be filled (block 84) with the filler (e.g., the
granular core 54).
That is, the partially shaped metal sheath 52 may be filled with various
powdered
alloying, corrosion resisting, arc stabilizing, slag forming, deoxidizing,
and/or filling
components. For example, among the various fluxing and alloying components,
one or
more corrosion resistant components (e.g., nickel, chromium, copper, and/or
alloys or
combinations thereof), one or more organic stabilizer components (e.g., sodium
carboxymethyl cellulose), one or more carbon components (e.g., graphite
powder), and
one or more rare earth components (e.g., rare earth silicide) may be added to
the metal
sheath 52. Furthermore, in certain embodiments, other components (e.g., rare
earth
silicide, magnetite, titanate, pyrite, iron powders, and/or other similar
components) may
also be added to the partially shaped metal sheath 52.
[0049] Next in
the illustrated process 80, once the components of the granular core
material 54 have been added to the partially shaped metal sheath 52, the
partially shaped
metal sheath 52 may then be fed through (block 86) one or more devices (e.g.,
drawing
dies or other suitable closing devices) that may generally close the metal
sheath 52 such
that it substantially surrounds the granular core material 54 (e.g., forming a
seam 58).
Additionally, the closed metal sheath 52 may subsequently be fed through
(block 88) a
number of devices (e.g., drawing dies or other suitable devices) to reduce the
circumference of the tubular welding wire 50 by compressing the granular core
material
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54. In certain embodiments, the tubular welding wire 50 may subsequently be
heated to
between approximately 300 F and approximately 650 F for approximately 4 to 6
hours
prior to packaging the tubular welding wire onto a spool, reel, or drum for
transport,
while, in other embodiments, the tubular welding wire 50 may be packaged
without this
baking step.
[0050] Set
forth below are five example formulations (El, E2, E3, E4, and E5) for the
tubular welding wire 50, in accordance with embodiments of the present
approach. It
may be appreciated that formulations El-ES discussed below are merely provided
as
examples and are not intended to limit the scope of the present approach.
Table 1
includes the ingredients of the granular core 54 in weight percent relative to
the weight of
the granular core 54. Further, Table 1 includes the computed chemical
composition of
the metallic strip 52 and the granular core 54 for embodiments El-ES of the
tubular
welding wire 50, wherein values are provides as weight percent relative to the
entire
tubular welding wire 50. It may be appreciated that, for embodiments El, E2,
E4, and E5
of the tubular welding wire 50 set forth in Table 1, the granular core 54 may
account for
approximately 15% of the total weight of the tubular welding wire 50, while
for
embodiment E3, the granular core 54 may account for approximately 20% of the
total
weight of the tubular welding wire 50. Additionally, as set forth above, in
certain
embodiments, the tubular welding wire 50 may include one or more of chromium
(e.g.,
0.1% to 30% chromium by weight), copper (e.g., 0% to 1% copper by weight), and
nickel
(e.g., 0% to 10% nickel by weight), or any combination thereof, in order to
provide a
weld deposit that is substantially corrosion resistant.
[0051] It may
be appreciated that the AWS A5.29 specification defines all-weld metal
(AWM) deposit chemistry for a B classification and for a W2 classification,
both of
which provide greater corrosion resistance than typical mild steel
chemistries. For
example, the weld deposits of the B classification may be used in power plants
for
elevated temperature applications, while weld deposits of the W2
classification may be
formed on weathering steel workpieces. As such, the AWS A5.29 specification is
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generally directed toward forming weld deposits on mild steel and/or low-alloy
steel
workpieces. It may also be appreciated that the AWS A5.22 specification
defines AWM
chemistry for single-pass stainless steel weld deposits (e.g., the 409
classification, the 304
classification, and the 308 classification) that provide adequate corrosion
resistance
without surface treatment on stainless workpieces. As such, while the AWS
A5.29 and
A5.22 specifications define corrosion resistant weld deposits, these standards
do not
directly address welding coated workpieces (e.g., galvanized, galvannealed,
plated,
aluminized, chromed, nitrided, carburized, or other similar coated
workpieces).
Accordingly, it may be appreciated that embodiment El of the tubular welding
wire 50
may include similar corrosion resistant components as welding wires classified
under the
AWS A5.29 W2 classification, embodiment E2 of the tubular welding wire 50 may
include a combination of corrosion resistant components used in welding wires
classified
under the AWS A5.29 W2 and/or B classifications. Additionally, embodiment E3
of the
tubular welding wire 50 may include similar corrosion resistant components as
welding
wires classified under the AWS A5.22 409 classification, and embodiment E4 of
the
tubular welding wire 50 may include similar corrosion resistant components as
welding
wires classified under the AWS A5.22 308 classification. Additionally,
embodiment E5
of the tubular welding wire 50 may include similar corrosion resistant
components as
welding wires classified under the AWS A5.22 B3 and/or W2 classifications. As
such, in
certain embodiments, the tubular welding wire 50 (e.g., embodiment E3) may be
classified as A5.22 ECG welding wire (e.g., according to the classification
system
described in AWS A2.2.3-8) and may provide a ferritic stainless AWM chemistry
on
mild coated or uncoated steel workpieces of gauge thicknesses, wherein
sufficient
chromium is provided to the weld deposit during a single-pass welding
operation (e.g., at
approximately 15% - approximately 50% dilution) to impart corrosion resistance
to the
weld deposit. As mentioned above, in certain embodiments, the tubular welding
wire 50
may not fall within an AWS classification (e.g., due to low ductility) and may
form weld
deposits that would receive post-weld heat treatment to impart the desired
mechanical
properties to the weld deposits.
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[0052] For example, certain embodiments of the tubular welding wire 50
(e.g., E4)
may enable the formation of an austenitic stainless weld deposit at
approximately 30%
dilution during a single-pass welding operation. Such an austenitic weld
deposit may
include corrosion resistant components similar to the AWS A5.22 308 or 304
classification (e.g., including between approximately 18% and approximately
21%
chromium and between approximately 9% and 11% nickel). For this example, to
provide
the aforementioned levels of corrosion resistant components to the weld
deposit, certain
embodiments of the presently disclosed tubular welding wire 50 (e.g., E4) may
include
greater than approximately 20% (e.g., between approximately 25% and
approximately
30%) chromium by weight and/or greater than approximately 10% (e.g., between
approximately 12% and approximately 18%) nickel by weight of the tubular
welding
wire 50. Further, as illustrated in Table 1 below, certain embodiments of the
tubular
welding wire 50 (e.g., E4) may utilize a stainless steel strip (e.g.,
according to the AWS
A5.22 304 classification) for the metallic sheath 52 of the tubular welding
wire 50. By
specific example, in certain embodiments, the metallic sheath 52 of the
tubular welding
wire 50 may include approximately 0.02% carbon, approximately 18.3% chromium,
approximately 70% iron, approximately 1.85% manganese, and approximately 9.8%
nickel by weight. Accordingly, for embodiments of the tubular welding wire 50
using a
stainless steel metallic sheath 52, chromium (e.g., in the sheath 52 and the
core 54) may
account for between approximately 15% and approximately 30% of the weight of
the
tubular welding wire 50, and nickel (e.g., in the sheath 52 and the core 54)
may account
for between approximately 5% and approximately 10% of the weight of the
tubular
welding wire 50.
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Ingredients of Granular Core (wt% relative to total weight of the core)
Ingredient El E2 E3 E4 ES
Ferro-Molybdenum metal powder 1 1 0 0 1
Iron Powder 57.6 40.8 0 0 21.9
Potassium Sulfate 0.2 0.2 0.15 0.2 0.2
Rare Earth Silicide 2 2 1.5 2 2
Sodium carboxymethyl cellulose 1 1 0.75 1 1
K/Ti/Mn Frit 1 1 0.75 1 1
Nickel Metal Powder 4 4 0 4 4
Ferro-chromium low carbon metal powder 5.7 22.5 0 0 22.5
Ferro-titanium (40% grade) 1.1 1.1 0.8 1.1 0
Ferro-manganese-silicon 17.1 17.1 12.8 17.1 17.1
Copper Metal Powder 4 4 0 0 4
Graphite (granular) 0.5 0.5 0 0.5 0.5
Ferro-Silicon Powder 4.8 4.8 3.6 4.8 4.8
Chromium Metal Powder 0 0 79.65 68.3 20
Chemical Composition of Metallic Sheath (wt% relative to total weight of
entire wire)
Carbon 0.0765 0.0765 0.072 0.017
0.0765
Manganese 0.34 0.34 0.32 1.5725 0.34
Iron 84.5835 84.5835 79.61 59.5
84.5835
Chromium 0 0 0 15.555 0
Nickel 0 0 0 8.33 0
Chemical Composition of Granular Core (wt% relative to total weight of entire
wire)
Aluminum 0.0067 0.0069 0.0383 0.0271
0.0084
Carbon 0.2066 0.2055 0.1027 0.2044
0.2046
Calcium 0.0003 0.0003 0.0003 0.0003
0.0003
Cobalt 0.0015 0.0015 0 0.0015
0.0015
Chromium 0.6259 2.4705 15.7707 10.1426
5.4405
Copper 0.5958 0.5958 0 0 0.5958
Iron 9.5635 7.7141 0.7125 0.7000
4.8056
Potassium Oxide 0.0375 0.0375 0.0375 0.0375
0.0375
Potassium Sulfate 0.0288 0.0288 0.0288 0.0288
0.0288
Lanthanides (Ln) 0.0900 0.0900 0.0900 0.0900
0.0900
Manganese 1.5852 1.5852 1.5821 1.5820
1.5852
Manganese Oxide 0.0270 0.0270 0.0270 0.0270
0.0270
Molybdenum 0.0941 0.0941 0 0 0.0941
Nitrogen 0.0001 0.0001 0.0001 0.0001 0
Nickel 0.5970 0.5970 0 0.5970
0.5970
Oxygen 0.0004 0.0004 0.0004 0.0004 0
Phosphorus 0.0041 0.0039 0.0049 0.0038
0.0038
Lead 0.0003 0.0003 0 0 0.0003
Sodium oxide 0.1281 0.1281 0.0961 0.1281
0.1281
Sulfur 0.0009 0.0008 0.0036 0.0024
0.0011
Silicon 1.2220 1.2329 1.2487 1.2388
1.2378
Silicon Dioxide 0.0240 0.0240 0.0240 0.0240
0.0240
Tin 0.0003 0.0003 0 0 0.0003
Titanium 0.0672 0.0672 0.0651 0.0672 0
Titanium Dioxide 0.0615 0.0615 0.0615 0.0615
0.0615
Table 1: Ingredients and calculated chemical composition of the metallic
sheath 52 and
the granular core 54 for embodiments El -E5. Note that ingredients for the
granular core
54 are provided in weight percent relative to the total granular core. Note
that chemical
composition values are computed values provided as weight percent relative to
the total
weight of the tubular welding wire 50. Further, the list of chemical
composition list is
not exhaustive and, as such, the amounts of each component may not sum up to
unity.
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[0053] Table 2
below includes example welding parameters that may be used when
forming a weld deposit using the embodiments E1-E3 of the disclosed tubular
welding
wire 50. For example, weld deposits were formed from the tubular welding wire
embodiments E1-E3 using robotic welder (e.g., a Miller Auto-Axcess 450 and a
Motoman EA1400N robot arm) and a galvanized steel sheet metal workpiece
according
to the parameters set forth in Table 2. These example weld deposits did not
show signs
of burn-through and provided an acceptable surface appearance. Each of the
embodiments El-E3 provided good weldability as well as good feedability.
Additionally,
certain embodiments of the tubular welding wire 50 (e.g., El) provided weld
deposits
exhibiting good ductility based on longitudinal bend tests (e.g., according to
the testing
procedure set forth in AWS A5.36 for single-pass butt-welds). Further, each of
the
embodiments El-E5 are believed to provide sound weld deposits having a tensile
strength
greater than approximately 70 ksi.
[0054] For each
the weld deposits formed according to the parameters of Table 2, the
exterior of the weld deposits showed little or no external porosity, while the
starts and
stops of the welding operation showed some minor external porosity that is
common in
welding of galvanized coated materials. X-ray analysis of these weld deposits
confirmed
the presence of only minor internal porosity. Accordingly, it may be
appreciated that the
present approach enables low-porosity (e.g., a low surface porosity and/or low
total
porosity) welds to be attained at high travel speed (e.g., in excess of 30
in/min or 40
in/min), even when welding coated workpieces. In certain embodiments, the low-
porosity enabled by the presently disclosed tubular welding wire 50 may
provide a weld
that is substantially non-porous. In other embodiments, the disclosed tubular
welding
wire 50 may provide a low-porosity weld having only small voids or pores
(e.g., less than
approximately 1.6 mm in diameter) that are separated from one another by a
distance
greater than or equal to the respective diameter of each pore. Further, in
certain
embodiments, the porosity may be represented as a sum of the diameters of the
pores
encountered per distance of the weld in a direction (e.g., along the weld
axis). For such
embodiments, the weld may have a porosity less than approximately 0.3 inches
per inch
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of weld, less than approximately 0.25 inches per inch of weld, less than
approximately
0.2 inches per inch of weld, or less than approximately 0.1 inches per inch of
weld. In
certain embodiments, the amount of chromium present in the tubular welding
wire 50
may keep a substantial portion of the nitrogen present in the workpiece in
solution to
provide such low porosity welds, especially when welding workpieces having
high
nitrogen content (e.g., nitrided steel). It may be appreciated that the
porosity of the weld
may be measured using an X-ray analysis, microscope analysis, or another
suitable
method.
El E2 E3
Current ¨ 245A ¨ 247A ¨ 244A
Voltage 22 V 22 V 22 V
Wire Feed Speed 270 in/min 285 in/min 285 in/min
Travel Speed 40 in/min 40 in/min 40 in/min
Electrical Stick Out 0.625 in 0.625 in 0.625 in
Shielding Gas Mixture 90% An / 10% CO2 90% An / 10% CO2 90% An / 10% CO2
Table 2. Example welding parameters for a welding operation performed using
embodiments E1-E3 of the tubular welding wire 50 on a galvanized workpiece.
[0055] However,
as mentioned above, certain embodiments of the tubular welding
wire 50 may form weld deposits that initially have high strength, but also
have relatively
low ductility and toughness. By way of example, in a single (e.g., 1+1) pass
butt weld
test, an embodiment of the tubular welding wire 50 (e.g., E5) was used to form
a weld
deposit using an flux-cored arc welding process (e.g., current: ¨280 A,
voltage: 28 V,
travel speed: approximately 12 in/min, electrical stickout: 7/8 in, shielding
gas mixture:
90% Ar / 10% CO2). For this example, while the as-welded deposit may have
sufficient
strength (e.g., approximately 93,200 pounds per square inch (PSI)) to meet the
carbon
equivalent (CE) single pass strength classification, the weld deposit may not
have
sufficient ductility to comply with the remainder of the AWS classification.
For
example, when the as-welded deposit is subjected to a longitudinal bend (e.g.,
about a
0.75 in radius), openings may begin to form in the weld bead. However, for
this
example, it may be appreciated that, once the weld deposit has been subjected
to post-
weld heat treatment (e.g., approximately 1200 F for approximately 1 hour or
less), the
weld deposit may pass similar longitudinal bend tests while still maintaining
a high
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strength. However, it may be appreciated that, for applications where strength
is the only
concern, the example weld deposit may be acceptable for use without the post-
weld heat
treatment.
[0056]
Additionally, Table 3 below includes chemical analysis of weld deposits
formed using a commercially available tubular welding wire, FabCORO F6
(available
from Hobart Brothers Company of Troy, OH) and using embodiments E 1-E3 of the
present tubular welding wire 50 for three different welding experiments (i.e.,
a melt-
button, an AWM Chem Pad, and 1 layer pad). As set forth above, the tubular
welding
wire 50 (e.g., embodiments El, E2, E3, and E5) may deposit one or more of the
corrosion
resistant components discussed above to limit, block, or prevent corrosion
within the
resulting weld deposit. For example, in certain embodiments, the weld deposit
may
include one or more of nickel, chromium, copper, and mixtures or alloys
thereof, which
may limit corrosion of the weld deposit by reactive species, such as oxygen.
It may be
appreciated that certain embodiments of the disclosed tubular welding wire 50
may
produce low alloy weld deposits having a martensitic and/or a ferritic
structure, while
other embodiments may produce high alloy weld deposit having a martensitic
and/or a
ferritic structure. As used herein, a "low alloy weld deposit" is a weld
deposit having an
iron content greater than 50% by weight and a total alloy content (e.g.,
chromium, nickel,
copper, etc.) less than 10% by weight. As used herein, a "high alloy weld
deposit" is a
weld deposit having an iron content greater than 50% by weight and a total
alloy content
(e.g., chromium, nickel, copper, etc.) greater than 10% by weight. For
example, in
certain embodiments, the weld deposit may be a stainless steel. By specific
example, in
certain embodiments, the weld deposit may be a 200 series stainless steel, a
300 series
stainless steel, or a 400 series stainless steel.
[0057] By
specific example, as set forth in Table 3, in certain embodiments, copper
may account for between approximately 0.05% and approximately 2%, between
approximately 0.07% and approximately 1%, between approximately 0.08% and
approximately 0.9%, between approximately 0.09% and approximately 0.8%,
between
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approximately 0.1% and approximately 0.8%, or approximately 0.4% of the weld
deposit
by weight. By further example, in certain embodiments, chromium may account
for
between approximately 0.4% and approximately 20%, between approximately 0.5%
and
approximately 16%, between approximately 0.6% and approximately 11%, between
approximately 0.7% and approximately 10% of the weld deposit by weight. By
still
further example, in certain embodiments, nickel may account for between
approximately
0.1% and approximately 1%, between approximately 0.2% and approximately 0.7%,
between approximately 0.3% and approximately 0.65%, between approximately 0.4%
and approximately 0.65%, or approximately 0.35% of the weld deposit by weight.
Additionally, in certain embodiments, molybdenum may be present in the tubular
welding wire 50, a portion of which may be incorporated into the resulting
weld deposit.
By specific example, in certain embodiments, molybdenum may account for
between
approximately 0.001% and approximately 0.2%, between approximately 0.01% and
approximately 0.15%, between approximately 0.01% and approximately 1.2%, or
approximately 0.07% of the weld deposit by weight. In other embodiments,
titanium
and/or niobium may, additionally or alternatively, be present in the weld
deposit.
[0058]
Technical effects of the present disclosure include enabling the formation of
corrosion resistant weld deposits on coated workpieces. In particular, the
presently
disclosed tubular welding wires include one or more corrosion resistant
components (e.g.,
nickel, chromium, copper, and/or alloys or mixtures thereof) that may enable a
weld
deposit to have enhanced or improved resistance to corrosion or oxidation.
Furthermore,
in certain embodiments, the disclosed tubular welding wire may have a suitable
composition to enable the formation of weld deposits having relatively high
chromium
content (e.g., 4 ¨ 6 wt% chromium), which may hold nitrogen in solution within
the weld
deposit to mitigate or prevent weld porosity when welding nitrided steel
workpieces.
Accordingly, the presently disclosed tubular welding wires enhance the
weldability of
coated (e.g., galvanized, galvannealed, aluminized, nitrided, painted, and so
forth)
workpieces and/or thinner (e.g., 20-, 22-, 24-gauge, or thinner) workpieces,
even at high
travel speed (e.g., greater than 30 in/min or greater than 40 in/min).
34
Melt-Button AWM Chem Pad 1 layer
pad (90/10 gas) 0
Welding Wire F6 El E2 E3 F6 El E2 E3 F6 El E2
E3 ES (DCEP) ES (DCEN) Base Plate n.)
o
Carbon 0.126 0.059 0.136 0.085 0.105 0.115 0.118 0.102
0.143 0.131 0.135 0.130 0.123 0.134 0.107
un
Manganese 1.655 1.548 1.832 1.869 1.456 1.701 1.671
1.855 1.283 1.58 1.543 1.511 1.65 1.62 0.98 -a-,
un
Phosphorous 0.006 0.010 0.011 0.013 0.007 0.011 0.012 0.016 0.010 0.011 0.012
0.016 0.009 0.009 0.009 .6.
c...)
Sulfur 0.010 0.013 0.016 0.018 0.014 0.013 0.015 0.021
0.008 0.010 0.010 0.015 0.019 0.018 0.025
1-,
Silicon 0.856 0.892 1.044 1.254 0.852 1.085 1.111
1.403 0.627 0.859 0.831 0.912 0.91 0.92 0.22
Copper
0.068 0.921 0.581 0.075 0.056 0.611 0.615 0.052 0.140 0.487
0.505 0.153 0.46 0.47 0.23
Chromium 0.036 0.663 2.617 15.86 0.026 0.705 2.638 15.64 0.072 0.515 1.785
10.34 3.80 3.74 0.08
Vanadium 0.003 0.005 0.003 0.014 0.004 0.005 0.003 0.017 0.004 0.005 0.004
0.009 0.008 0.008 0.02
Nickel 0.003 0.583 0.668 0.032 0.023 0.622 0.646 0.021
0.078 0.456 0.490 0.071 0.43 0.43 0.09
Molybdenum 0.006 0.101 0.099 0.011 0.006 0.121 0.119 0.012 0.017 0.081 0.082
0.023 0.08 0.07 0.02
Aluminum 0.018 0.001 0.027 0.006 0.001 0.008 0.009 0.018 0.014 0.016 0.015
0.032 0.018 0.019 0.001
Titanium
0.019 0.007 0.018 0.027 0.018 0.022 0.023 0.029 0.026 0.025
0.026 0.031 0.016 0.011 0.001
Niobium
0.002 0.003 0.003 0.007 0.003 0.005 0.006 0.011 0.001 0.004
0.004 0.008 0.005 0.005 0.001 P
Cobalt
0.001 0.002 0.003 0.027 0.002 0.006 0.007 0.041 0.006 0.005
0.007 0.026 0.007 0.008 0.006 0
1.,
Boron
0.00125 0.00335 0.00148 0.00163 0.00044 0.00092 0.00106 0.00144
0.00029 0.00137 0.00061 0.00149 0.00078 0.00091 0.0001 .
1.,
Tungsten 0.116 0.116 2.037 0.11 0.012 0.005 0.015 0.015 0.017 <0.005 0.009
0.013 0.014 0.008 0.01 0.005 L,
1-
L,
Tin
0.0072 0.011 0.012 0.0017 0.004 0.012 0.013 0.017 0.008
0.011 0.012 0.016 0.006 0.006 0.009
0
Lead
<0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 0.0016
<0.0001 <0.0001 <0.0001 0.0008 <0.0001 <0.0001 0.004 1-
1
Zirconium
0.0016 0.0022 0.0022 0.0029 <0.001 <0.001 0.0016 0.0034
<0.001 0.0015 <0.001 0.0045 <0.001 <0.001 <0.001 0
1.,
1
Antimony 0.0016 0.0108 0.0028 0.0075 0.0018 0.0006 0.0025 0.0070 <0.0001
0.0006 <0.0001 0.0045 0.003 0.005 0.005 1-
1-
Arsenic
0.00398 0.00487 0.00357 0.01713 0.00347 0.00271 0.00181
0.01389 0.00515 0.00358 0.00284 0.01027 0.00347 0.00505 0.00754
Table 3: Chemical analysis of weld deposits formed using the commercially
available FabCORO F6 welding wire as well as
embodiments El, E2, E3 and E5 of the disclosed tubular welding wire 50. Values
are provided in weight percentage relative
to the total weight of the weld deposit. Note that E5 is illustrated under
both DCEP and DCEN bias, and that the composition
of the base plate is also included in the table for the 1 layer pad welding
experiments. Further note that italicized values are
higher due to unintentional pick-up of tungsten and/or copper from the
electrode and/or crucible during the welding operation. 1-d
n
,-i
cp
w
=
.6.
-a-,
u,
,4z
--.1
=
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[0059] While
only certain features of the invention have been illustrated and described
herein, many modifications and changes will occur to those skilled in the art.
It is,
therefore, to be understood that the appended claims are intended to cover all
such
modifications and changes as fall within the true spirit of the invention.
36
