U.S. patent application number 14/706671 was filed with the patent office on 2015-08-27 for systems and methods for tubular welding wire.
The applicant listed for this patent is HOBART BROTHERS COMPANY. Invention is credited to Steven Edward Barhorst, Michael Scott Bertram, Joseph C. Bundy.
Application Number | 20150239072 14/706671 |
Document ID | / |
Family ID | 48170813 |
Filed Date | 2015-08-27 |
United States Patent
Application |
20150239072 |
Kind Code |
A1 |
Barhorst; Steven Edward ; et
al. |
August 27, 2015 |
SYSTEMS AND METHODS FOR TUBULAR WELDING WIRE
Abstract
A submerged arc welding (SAW) wire includes a metal sheath
surrounding a granular core. The metal sheath includes at least
approximately 0.6% manganese by weight and at least approximately
0.05% silicon by weight, and the granular core includes less than
2% manganese by weight and less than 2% silicon by weight. Further,
the granular core does not include components that provide
shielding gas during SAW.
Inventors: |
Barhorst; Steven Edward;
(Sidney, OH) ; Bundy; Joseph C.; (Piqua, OH)
; Bertram; Michael Scott; (Troy, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HOBART BROTHERS COMPANY |
Troy |
OH |
US |
|
|
Family ID: |
48170813 |
Appl. No.: |
14/706671 |
Filed: |
May 7, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13446796 |
Apr 13, 2012 |
9029733 |
|
|
14706671 |
|
|
|
|
Current U.S.
Class: |
219/73 ;
219/145.1 |
Current CPC
Class: |
B23K 35/0261 20130101;
C22C 1/02 20130101; B23K 9/173 20130101; B23K 9/186 20130101; B23K
35/406 20130101; B23K 35/0244 20130101; C22C 38/04 20130101; B23K
35/0266 20130101; B23K 35/3073 20130101; Y10T 428/12104 20150115;
B23K 9/167 20130101; C22C 38/02 20130101 |
International
Class: |
B23K 35/02 20060101
B23K035/02; B23K 35/30 20060101 B23K035/30; B23K 9/18 20060101
B23K009/18 |
Claims
1. A submerged arc welding (SAW) wire, comprising: a metal sheath
surrounding a granular core, wherein the metal sheath comprises at
least approximately 0.6% manganese by weight and at least
approximately 0.05% silicon by weight, and wherein the granular
core comprises less than 2% manganese by weight and less than 2%
silicon by weight, wherein the granular core does not include
components that provide shielding gas during SAW.
2. The SAW wire of claim 1, wherein the metal sheath comprises at
least approximately 0.1% silicon by weight.
3. The SAW wire of claim 1, wherein the metal sheath comprises
between approximately 0.2% and approximately 0.3% silicon by
weight.
4. The SAW wire of claim 1, wherein the metal sheath comprises
between approximately 0.25% and approximately 0.75% silicon by
weight.
5. The SAW wire of claim 1, wherein the metal sheath comprises less
than approximately 1.8% manganese by weight.
6. The SAW wire of claim 1, wherein the metal sheath comprises
between approximately 0.8% and approximately 2% manganese by
weight.
7. The SAW wire of claim 1, wherein the metal sheath comprises
between approximately 0.9% and approximately 1.1% manganese by
weight.
8. The SAW wire of claim 1, wherein the metal sheath comprises less
than approximately 0.1% carbon by weight.
9. The SAW wire of claim 1, wherein the granular core comprises
less than 1% manganese by weight and less than 1% silicon by
weight.
10. The SAW wire of claim 1, wherein the granular core comprises
less than 0.5% manganese by weight and less than 0.5% silicon by
weight.
11. The SAW wire of claim 1, wherein the granular core comprises
less than 0.05% manganese by weight and less than 0.05% silicon by
weight.
12. The SAW wire of claim 1, wherein the SAW wire is configured for
use in conjunction with a SAW flux that provides shielding gas near
a weld pool during SAW.
13. A submerged arc welding (SAW) system, comprising: a welding
wire feeder that supplies a SAW wire to a SAW torch to form a weld
pool on the surface of a workpiece during SAW, wherein the SAW wire
comprises a metal sheath surrounding a granular core, wherein the
metal sheath comprises at least approximately 0.6% manganese by
weight and at least approximately 0.05% silicon by weight, and
wherein the granular core comprises less than 2% manganese by
weight and less than 2% silicon by weight; and a flux delivery
component that delivers a SAW flux to the surface of the workpiece,
wherein the SAW flux provides at least a portion of the atmosphere
near the weld pool during SAW.
14. The SAW system of claim 13, wherein the metallic sheath
comprises less than approximately 2% manganese by weight and less
than approximately 0.75% silicon by weight.
15. The SAW system of claim 13, wherein the metal sheath comprises
between approximately 0.2% and approximately 0.3% silicon by weight
and between approximately 0.9% and approximately 1.1% manganese by
weight.
16. The SAW system of claim 13, wherein the granular core comprises
less than 1% manganese by weight and comprises less than 1% silicon
by weight.
17. The SAW system of claim 13, wherein the granular core comprises
less than 0.05% manganese by weight and comprises less than 0.01%
silicon by weight.
18. A method of submerged arc welding (SAW), comprising: feeding a
SAW wire to a SAW torch near a workpiece, wherein the SAW wire
comprises a metal sheath surrounding a granular core, wherein the
metal sheath comprises at least approximately 0.6% manganese by
weight and at least approximately 0.05% silicon by weight, and
wherein the granular core comprises less than 2% manganese by
weight and less than 2% silicon by weight; establishing an arc
between the SAW wire and the workpiece to form a weld pool; and
providing a SAW flux that submerges the weld pool and provides at
least a portion of the atmosphere near the weld pool.
19. The method of claim 18, wherein the metal sheath comprises
between approximately 0.2% and approximately 0.3% silicon by weight
and between approximately 0.9% and approximately 1.1% manganese by
weight.
20. The method of claim 20, wherein the granular core comprises
less than 1% manganese by weight and comprises less than 1% silicon
by weight.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of U.S. Non-Provisional patent
application Ser. No. 13/446,796, entitled "SYSTEMS AND METHODS FOR
TUBULAR WELDING WIRE", filed Apr. 13, 2012, which is herein
incorporated by reference in its entirety 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), Submerged Arc Welding (SAW) or
Flux Core Arc Welding (FCAW)), typically employ 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.
BRIEF DESCRIPTION
[0004] In an embodiment, a submerged arc welding (SAW) wire
includes a metal sheath surrounding a granular core. The metal
sheath includes at least approximately 0.6% manganese by weight and
at least approximately 0.05% silicon by weight, and the granular
core includes less than 2% manganese by weight and less than 2%
silicon by weight. Further, the granular core does not include
components that provide shielding gas during SAW.
[0005] In another embodiment, a submerged arc welding (SAW) system
includes a welding wire feeder that supplies a SAW wire to a SAW
torch to form a weld pool on the surface of a workpiece during SAW.
The SAW wire includes a metal sheath surrounding a granular core,
wherein the metal sheath includes at least approximately 0.6%
manganese by weight and at least approximately 0.05% silicon by
weight, and the granular core includes less than 2% manganese by
weight and less than 2% silicon by weight. The system further
includes a flux delivery component that delivers a SAW flux to the
surface of the workpiece, wherein the SAW flux provides at least a
portion of the atmosphere near the weld pool during SAW.
[0006] In another embodiment, a method of submerged arc welding
(SAW) includes feeding a SAW wire to a SAW torch near a workpiece.
The SAW wire includes a metal sheath surrounding a granular core,
wherein the metal sheath includes at least approximately 0.6%
manganese by weight and at least approximately 0.05% silicon by
weight, and wherein the granular core includes less than 2%
manganese by weight and less than 2% silicon by weight. The method
includes establishing an arc between the SAW wire and the workpiece
to form a weld pool. The method further includes providing a SAW
flux that submerges the weld pool and provides at least a portion
of the atmosphere near the weld pool.
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 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
electrode, in accordance with embodiments of the present
disclosure;
[0010] FIG. 3 is a flow chart of a process by which the tubular
welding electrode may be used to weld a workpiece, in accordance
with embodiments of the present disclosure; and
[0011] FIG. 4 is a flow chart of a process for manufacturing the
tubular welding electrode, 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.
[0014] The presently disclosed tubular welding wire embodiments may
include one or more components (e.g., flux, arc stabilizers, or
other additives) that generally alter the welding process and/or
the properties of the resulting weld. Furthermore, it may be
appreciated that, in addition to the chemical properties provided
by the tubular welding wire (e.g., the chemical composition of the
weld and the fumes produced during welding), it may be desirable
for the tubular welding wire to have certain physical properties as
well. For example, since the tubular welding wire is consumed
during welding, it may be constantly fed from a spool (e.g., in a
welding wire feeder) to the welding torch. As such, if, for
example, the stiffness of the welding wire is too low, then the
welding wire may crumple, tangle, or otherwise improperly feed when
the welding wire meets resistance during unspooling and/or feeding.
This is especially a problem for smaller diameter tubular welding
wires, which may generally be more prone to buckling. When the
tubular welding wire buckles while feeding, it may form a tangled
"bird's nest" that generally wastes welding wire and operator time
as well as, in certain circumstances, adversely affecting
operations of the welding system (e.g., welding wire feeder, wire
spool, or similar wire feeding components of the welding system).
Additionally, when the stiffness of a larger diameter welding wire
is too low, the wire may be more likely to crush (e.g., making the
tubular wire have an "egged" shape"), which may result in slippage
and/or other inconsistencies in wire feeding that may have
deleterious effects to the welding process. Accordingly, it may be
desirable to have welding wire having a greater stiffness, so that
it may be less likely to experience unspooling or feeding issues
throughout the welding process.
[0015] As such, the tubular welding wire embodiments described
herein have a metal sheath that includes one or more components,
such as manganese and/or silicon, which may not be included in
metals sheaths of other welding wires as presently disclosed. It
should be appreciated that these components may include components
that are provided by the granular core of conventional welding
wires. Moreover, certain disclosed tubular welding wire embodiments
also possess superior physical properties (i.e., stiffness and/or
hardness) as a result of having these components loaded into the
metal sheath rather than the granular core. In particular, the
disclosed tubular welding wire embodiments include a substantially
higher (e.g., two to three times higher) manganese content than
conventional metal sheaths, which may improve the stiffness of the
tubular welding wire and serve to increase the manganese content of
the weld. Additionally, certain tubular welding wire embodiments
include substantially higher (e.g., two to ten times higher)
silicon content than conventional metal sheaths, which may also
improve the stiffness of the tubular welding wire and serve to
increase the silicon content in the weld. As such, the presently
disclosed tubular welding wire enables greater flexibility in the
selection of components for the granular core since at least a
portion of these components may instead be delivered by the metal
sheath. Furthermore, since the disclosed tubular welding wire
provides benefits beyond improved stiffness, it should be
appreciated that while the present discussion may be directed
toward tubular welding wire, other embodiments (e.g., welding rods)
having similar components are also presently contemplated.
[0016] Generally speaking, there are advantages to utilizing a
tubular welding wire in which one or more components typically
found in the granular core of the tubular welding wire are instead
provided by the metal sheath, as presently disclosed. That is,
certain components of typical tubular welding wire may be present
within the granular core in order to affect the chemistry of the
weld. Furthermore, since the tubular welding wire has a finite
internal volume, by moving one or more components (e.g., manganese
and/or silicon sources) from the granular core and into the metal
sheath, more space may be available in the core of the tubular
welding wire for other components (e.g., other metals, fluxes,
stabilizers, or similar components). That is, the newly available
space within the tubular welding wire may be dedicated to other
additives to improve, for example, welding deposition rates.
Generally speaking, the manganese and silicon content provided by
the metal sheath of the presently disclosed tubular welding wire
may provide deoxidation of the weld pool, which may also aid in
weld pool wetting of the base metal being welded. Silicon, by
specific example, may enable improved weld-bead wetting. For the
disclosed embodiments, the relative manganese and silicon content
included in the metal sheath may be balanced in order to balance
the desired chemical properties (e.g., the deoxidation and wetting
properties) and mechanical properties (e.g., stiffness).
[0017] Furthermore, by moving one or more components (e.g.,
manganese and/or silicon sources) from the granular core to the
metallic sheath, the chemistry of the welding process may also be
varied. For example, placing certain components (e.g., manganese
and/or silicon sources) in the metallic sheath rather than the
granular core may enable more freedom to select other components
for the granular core (e.g., including components that are not
otherwise compatible with the manganese and/or silicon sources). By
further example, in certain embodiments, by placing one or more
components (e.g., manganese and/or silicon sources) in the metallic
sheath rather than the granular core, a greater portion of these
components may become incorporated into the weld metal (e.g.,
rather than react with other components in the granular core and/or
form fumes). Accordingly, it may be desirable to instead use the
metal sheath of the tubular welding wire to deliver these
components to the weld.
[0018] Turning to the figures, FIG. 1 is a block diagram of an
embodiment of a gas metal arc welding (GMAW) system 10 that
utilizes a tubular welding wire 12, 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 wire may benefit any arc
welding process (e.g., FCAW, FCAW-G, GTAW, submerged arc welding
(SAW), or similar arc welding process) that uses a tubular welding
wire (e.g., a tubular welding electrode or rod). It should be
appreciated that certain welding system embodiments (e.g., SAW
welding systems or GTAW welding systems) using the disclosed
welding wire or electrode may include components not illustrated in
the example GMAW system 10 (e.g., a flux hopper, a flux delivery
component, a rod welding electrode, etc.) and/or not include
components that are illustrated in the example GMAW system 10
(e.g., the gas supply system 16). It should also be appreciated
that, in other embodiments, the presently disclosed tubular welding
wire may be utilized as a "cold welding wire," in which the tubular
welding wire does not carry the current (e.g., does not form the
arc to the surface of the workpiece) during the welding
process.
[0019] The welding system 10 includes a welding power unit 13, a
welding wire feeder 14, a gas supply system 16, and a welding torch
18. The welding power unit 13 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
12 (e.g., the welding electrode) and power to the welding torch 18
during operation of welding system 10. In another embodiment, the
welding power unit 13 may couple and directly supply power to the
welding torch 18.
[0020] The welding power unit 13 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 unit 13 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 unit 13 to
the workpiece 22 to close the circuit between the welding power
unit 13, the workpiece 22, and the welding torch 18. The welding
power unit 13 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) output, DC variable
polarity, 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 tubular welding
wire 12 may enable improvements to the welding process (e.g.,
improved wire feeding, improved arc stability, and/or improved weld
quality) for a number of different power configurations.
[0021] 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 other
embodiments, 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., 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 (CO.sub.2), oxygen (O.sub.2), nitrogen
(N.sub.2), 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/CO.sub.2 mixtures,
Ar/CO.sub.2/O.sub.2 mixtures, Ar/He mixtures, and so forth.
[0022] Accordingly, the illustrated welding torch 18 generally
receives the welding electrode (i.e., the 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 (e.g., the tubular welding wire 12 exiting a
contact tip of the welding torch 18) and the workpiece 22.
Additionally, as discussed below, by controlling the composition of
the welding electrode (e.g., the tubular welding wire 12), the
chemistry of the arc 34 and/or the resulting weld (e.g.,
composition and physical characteristics) may be tuned. For
example, the tubular welding wire 12 may include any number of
fluxing and/or alloying components that may 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., the tubular
welding wire 12) may also provide additional shielding atmosphere
near the arc 34, affect the transfer properties of the arc 34,
and/or deoxidize the surface of the workpiece 22.
[0023] The welding wire feeder 14 also includes components for
feeding the tubular welding wire 12 to the welding torch 18, and
thereby to the welding application, under the control of a
controller 36. For example, in certain embodiments, one or more
wire supplies (e.g., a wire spool 38) of tubular welding wire 12
may be housed in the welding wire feeder 14. A wire feeder drive
unit 40 may unspool the tubular welding wire 12 from the spool 38
and progressively feed the tubular welding wire 12 to the welding
torch 18. To that end, the wire feeder drive unit 40 may include
components such as circuitry, motors, rollers, and so forth,
configured in a suitable way for establishing an appropriate wire
feed. For example, in one embodiment, the wire feeder drive unit 40
may include a feed motor that engages with feed rollers to push
wire from the welding wire feeder 14 towards the welding torch 18.
Additionally, power from the welding power unit 13 may be applied
to the fed wire.
[0024] However, during this wire feeding process, if the stiffness
of the tubular welding wire 12 is insufficient, then the welding
wire 12 may crumple, tangle, or otherwise improperly feed. For
example, the tubular welding wire 12 may form a tangled "bird's
nest" of welding wire (e.g., in the spool 38 and/or the wire feeder
drive unit 40) instead of properly feeding to the welding torch 18.
Since such wire misfeeds may result in the welding operator ceasing
welding operations so that the improperly fed tubular welding wire
may be removed, these misfeeds generally waste operator time and
tubular welding wire. Additionally, in certain circumstances, such
wire misfeeds may adversely affect operation of the welding system
10 (e.g., the welding wire feeder 40, the wire spool 38, or similar
wire feeding components of the welding system 10), creating
additional costs. Accordingly, certain embodiments of the presently
disclosed tubular welding wire 12 utilize metal or metallic sheaths
having manganese and/or silicon (e.g., alloyed into the metal). In
certain embodiments, these higher-alloy metal sheaths demonstrate
improved stiffness, which may generally improve the feeding of the
tubular welding wire 12 through the welding system 10.
[0025] A cross-section of an embodiment of the presently disclosed
tubular welding wire 12 (or tubular welding rod) is illustrated in
FIG. 2. FIG. 2 is a cross-sectional view of an embodiment of the
tubular welding wire 12 that includes a metallic sheath 52
encapsulating a granular or powdered core 54. For example, the
tubular welding wire 12 may be a metal cored tubular wire.
Additionally, in certain embodiments, the granular core 54 may be
partially or completely absent, leaving a void within the tubular
welding wire 12.
[0026] The metallic sheath 52 may include any suitable metal or
alloy (e.g., iron, high-carbon steel, low-carbon steel, or other
suitable metal or alloy) having a manganese and/or silicon content,
in accordance with aspects of the present technique. For example,
in certain embodiments, the metallic sheath 52 may include 80%,
90%, 95%, or 98% iron or steel. It should be appreciated that since
the metallic sheath 52 may generally provide at least a portion of
the filler metal for the weld, the composition of the metallic
sheath 52 may affect the composition of the resulting weld. For
example, in addition to the manganese and/or silicon, the metallic
sheaths 52 may include other additives or impurities (e.g., carbon,
sulfur, phosphorus, copper, nickel, tin, chromium, and/or other
elements) that may also affect the properties of the weld. For
example, in certain embodiments, the metallic sheaths 52 may
include less than approximately 0.1%, less than approximately
0.02%, or between approximately 0.08% and 0.1% carbon by weight.
Additionally, in certain embodiments, the metallic sheaths 52 may
include less than approximately 0.02%, less than approximately
0.015%, or less than approximately 0.01% sulfur by weight.
Furthermore, in certain embodiments, the metallic sheaths 52 may
include less than approximately 0.02%, less than approximately
0.015%, or less than approximately 0.01% phosphorus by weight.
[0027] With respect to the manganese content, in certain
embodiments, the manganese content of the metallic sheath 52 may
generally be greater than approximately 0.3% or 0.6% by weight. In
certain embodiments, the metallic sheath 52 may include between
approximately 0.1% and approximately 2% manganese by weight,
between approximately 0.2% and approximately 1.9% manganese by
weight, between approximately 0.6% and approximately 1.8% manganese
by weight, between approximately 0.8% and approximately 2%
manganese by weight, between approximately 0.9% and approximately
1.1% manganese by weight, or any subranges in between. With respect
to the silicon content, in certain embodiments, the silicon content
of the metallic sheath 52 may generally be greater than
approximately 0.05% or 0.1% by weight. In certain embodiments, the
metallic sheath 52 may include between approximately 0.2% and
approximately 0.3% silicon by weight, between approximately 0.25%
and approximately 0.35% silicon by weight, between approximately
0.3% and approximately 0.75% silicon by weight, between
approximately 0.25% and approximately 0.75% silicon by weight, or
any subranges in between.
[0028] As mentioned, the manganese and/or silicon included in the
metallic sheath 52 may affect the physical properties of the
metallic sheath 52 and the tubular welding wire 12. For example, an
embodiment of the metallic sheath 52 may have a fracture toughness
such that only pressures greater than approximately 68,000 psi, or
between approximately 68,000 psi and 69,000 psi, may induce
fracture. In contrast, similarly sized metallic welding strips
lacking the manganese and/or silicon content presently disclosed
may have a fracture toughness such that pressures of between
approximately 43,000 to 52,000 psi may induce fracture.
Accordingly, the addition of the manganese and/or silicon to the
metallic sheath 52 may generally provide improved mechanical and/or
physical properties (e.g., fracture toughness, tensile strength,
stiffness, and the like) that may improve the ability of the
resulting tubular welding wire 12 to properly feed within the
welding system 10.
[0029] The granular core 54 of the illustrated tubular welding wire
12 may generally be a compacted powder with a composition that, as
discussed below, may include components (e.g., filler metals,
fluxes, stabilizers, and the like) that affect the welding process.
For example, in certain embodiments, the granular core 54 of the
tubular welding electrode 12 may include elements (e.g., iron,
titanium, barium, lithium, fluorine, or other elements) and/or
minerals (e.g., pyrite, magnetite, and so forth) to provide arc
stability and to control the chemistry of the resulting weld. The
various components of the granular core 54 may be homogenously or
non-homogenously (e.g., in clumps or clusters 56) disposed within
the granular core 54. Since the manganese and/or silicon components
of the tubular welding wire 12 may be provided by the metallic
sheath 52, in certain embodiments, the granular core 54 may be
substantially free (e.g., approximately 0% by weight, only
including trace amounts, or less than approximately 0.01% or 0.05%)
of manganese and/or silicon. For example, in certain embodiments,
the granular core 54 of the tubular welding wire 12 may include
less than 5%, 2%, 1%, 0.5%, 0.05% or 0.01% manganese by weight. By
further example, in certain embodiments, the granular core 54 of
the tubular welding wire 12 may include less than 5%, 2%, 1%, 0.5%,
0.05%, or 0.01% silicon by weight. It should be appreciated that,
under the conditions of the arc 34, the components of the tubular
welding wire 12 (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.
[0030] FIG. 3 is a flow chart of a process 60 by which a workpiece
22 may be welded using the disclosed welding system 10 and the
tubular welding electrode 12, which includes a metal sheath 52
having manganese, silicon, or both. The illustrated process 60
begins with feeding (block 62) the tubular welding wire 12 to a
welding apparatus (e.g., the welding torch 18), in which the
tubular welding wire 12 includes manganese and/or silicon.
Additionally, the process 60 includes feeding (block 64) a
shielding gas flow (e.g., 100% argon, 75% argon/25% carbon dioxide,
90% argon/10% helium, or similar shielding gas flow) to the welding
apparatus (e.g., the contact tip of the welding 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., aluminum, iron,
various fluoride salts, or other components) of the tubular welding
wire 12 may provide a shielding gas component. Next, the tubular
welding wire 12 may be brought near (block 66) (e.g., 0.25 mm, 0.5
mm, 1 mm, 2 mm, 3 mm, 5, mm, 10 mm, or generally less than 30 mm
away from) the workpiece 22 such that an arc 34 may be formed
between the tubular welding wire 12 and the workpiece 22. It should
be appreciated that the arc 34 may be produced using a DCEP, DCEN,
DC variable polarity, balanced or unbalanced AC power configuration
for the GMAW system 10. Furthermore, in certain embodiments (e.g.,
SAW welding systems), a granular flux (e.g., a SAW flux) may be
provided at or near the arc and/or weld pool in order to provide at
least a portion of the atmosphere at or near the arc and/or weld
pool in addition to (or in alternative to) the shielding gas flow.
Then, a portion of the tubular welding wire 12 is consumed (block
68) while forming the weld on the workpiece 22. In certain
embodiments, the manganese and/or silicon disposed in the metallic
sheath 52 may be liberated to interact with the arc 34 and/or, at
least partially, become incorporated into the weld.
[0031] It may generally be appreciated that the loading of
components (e.g., manganese and/or silicon) into the metal sheath
52 rather than the granular core 54 may also have an effect on how
these materials react in the arc 34 and/or are incorporated into
the welding process. That is, an advantage of disposing the
manganese and/or silicon in the metallic sheath 52 rather than the
granular core 54 may be that a greater portion of the manganese
and/or silicon reaches the weld (e.g., rather than forming fumes).
In other words, there may be substantial or subtle differences in
the arc 34 and/or weld pool conditions (e.g., temperature, voltage,
relative positions of reactants, and the like) experienced by the
manganese and/or silicon components delivered via the metallic
sheath 52 rather than by the granular core 54. Accordingly, in
certain embodiments, the disclosed tubular welding wire 12 may
produce fumes having a lower manganese concentration than other
welding wires having manganese supplied by the granular core 54.
Furthermore, in certain embodiments, the total amount of a
component (e.g., manganese and/or silicon) that may be used when
delivering the component via the metallic sheath 52 may be
substantially less than the amount of the component used when
delivering the component to the weld via the granular core 54,
since less of the component may be consumed in the formation of
welding byproducts (e.g., fumes and/or slag).
[0032] FIG. 4 is a flow chart of a process 70 by which the tubular
welding electrode 12 may be manufactured. The process 70 begins
with a flat metal strip (i.e., including manganese, silicon, or
both) being fed (block 72) 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
74) with the granular core material 54. Accordingly, the partially
shaped metal sheath 52 may be filled with various powdered fluxing
and alloying components (e.g., iron, iron oxide, fluoride salts, or
similar fluxing and/or alloying components). In certain
embodiments, no manganese or silicon components may be added to the
partially shaped metal sheath 52. Once the partially shaped metal
sheath 52 has been filled with the various components of the
granular core 54, the partially shaped metal sheath 52 may then be
fed through (block 76) one or more dies that may generally close
the metal sheath 52 such that it substantially surrounds the
granular core material 54 (e.g., forming a seam 58, such as shown
in FIG. 2). Additionally, the closed metal sheath 52 may
subsequently be fed through (block 78) a number of dies (e.g.,
drawing dies) to reduce the diameter of the tubular welding wire 12
by compressing the granular core material 54.
[0033] It should be appreciated that while improving the stiffness
of the metal sheath of a tubular welding wire 12 may improve the
feeding of tubular welding wire 12, this approach also presents
certain challenges. For example, by increasing the stiffness of the
metal sheath 52 of the tubular welding electrode 12, the amount of
cold working used to shape the metal sheath 52 around the granular
core 54 (e.g., in blocks 72, 76, and 78) may also increase.
Furthermore, since the hardness of the metal sheath 52 may also
increase with the addition of the manganese and/or silicon
components, the aforementioned dies (e.g., in blocks 72, 76, and
78) that may be used to shape the metal sheath 52 around the
granular core 54 may wear more quickly due to the increased
stiffness and/or hardness of the tubular welding wire 12.
Additionally, the dies used to shape the metal sheath 52 during the
manufacture of the tubular welding wire 12 may be manufactured from
a material also having improved mechanical properties (e.g., a
harder or tougher die material) in order to accommodate the altered
mechanical properties of the disclosed tubular welding wire 12
embodiments. As such, there may be design challenges when
attempting to improve the feeding of tubular welding wire 12 by
increasing the stiffness of the metal sheath, as presently
disclosed.
[0034] 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.
* * * * *