U.S. patent application number 11/445636 was filed with the patent office on 2006-11-16 for welding electrode and method for reducing manganese in fume.
Invention is credited to Lowell W. Mott, Thomas H. North.
Application Number | 20060255026 11/445636 |
Document ID | / |
Family ID | 25095958 |
Filed Date | 2006-11-16 |
United States Patent
Application |
20060255026 |
Kind Code |
A1 |
North; Thomas H. ; et
al. |
November 16, 2006 |
Welding electrode and method for reducing manganese in fume
Abstract
A method for reducing an amount of manganese in a fume generated
during arc welding including incorporating a quantity of manganese
in a core of a welding electrode as a composite particle of
manganese and a shielding material.
Inventors: |
North; Thomas H.;
(Burlington, CA) ; Mott; Lowell W.; (Troy,
OH) |
Correspondence
Address: |
THOMPSON HINE L.L.P.
P.O. BOX 8801
DAYTON
OH
45401-8801
US
|
Family ID: |
25095958 |
Appl. No.: |
11/445636 |
Filed: |
June 2, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10885382 |
Jul 6, 2004 |
7091448 |
|
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11445636 |
Jun 2, 2006 |
|
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|
09772708 |
Jan 30, 2001 |
6784401 |
|
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10885382 |
Jul 6, 2004 |
|
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|
Current U.S.
Class: |
219/137WM ;
219/145.22 |
Current CPC
Class: |
B23K 35/0266 20130101;
B23K 35/368 20130101; B23K 35/3053 20130101; B23K 35/30 20130101;
B23K 35/3608 20130101 |
Class at
Publication: |
219/137.0WM ;
219/145.22 |
International
Class: |
B23K 9/23 20060101
B23K009/23 |
Claims
1. A method for reducing an amount of manganese in a fume generated
during arc welding comprising incorporating a quantity of manganese
in a core of a welding electrode as a composite particle of
manganese and a shielding material.
2. The method of claim 1 wherein said shielding material is
TiO.sub.2.
3. The method of claim 2 wherein said TiO.sub.2 is rutile.
4. The method of claim 2 wherein said TiO.sub.2 is anatase.
5. The method of claim 1 wherein said incorporating step includes
encapsulating said manganese with said shielding material.
6. The method of claim 1 wherein said incorporating step includes
dispersing said manganese in a matrix of said shielding material.
Description
[0001] This application is a divisional of U.S. Ser. No. 10/885,382
filed on Jul. 6, 2004, which is a divisional of U.S. Ser. No.
09/772,708 filed on Jan. 30, 2001, now U.S. Pat. No. 6,784,401.
BACKGROUND
[0002] The invention relates generally to weld wires or electrodes
useful in joint and surface welding and more specifically to flux
cored weld wires.
[0003] Flux cored weld wires are commonly employed in electric arc
welding of mild and low alloy steel base metals. Flux cored wires
are used increasingly as an alternative to solid weld wires for
improved productivity in structural fabrication. These wires yield
high strength welds in single pass and multiple pass welding
operations at high welding speed. Flux core weld wires are
composite tubular filler metal electrodes having a metal sheath and
a core containing a composition of various powdered materials. The
core composition comprises approximately 1 to 45% of the total wire
weight. During the manufacture of the wire, the core composition is
blended and deposited onto a steel strip, which is formed into a
tube or sheath about the core composition in a forming mill. The
steel sheath surrounding the core composition is then drawn or
rolled through reducing dies to a specified diameter.
[0004] Manganese is an essential alloying addition in most welding
electrodes. Manganese has several functions. It is a key
strengthening alloy to the weld deposit; it chemically reacts with
sulphur components in the molten weld metal, it acts as a
de-oxidizer, and it affects weld puddle control, wetting action and
general ease of use of the welding electrode itself. The current
levels of manganese used in conventional electrodes reflect the
optimum combination of alloying elements with iron to produce
grades of welds that meet standard levels for strength and
ductility.
[0005] Recently, the amount of manganese present in the fume
generated when welding with electrodes containing manganese has
been scrutinized for possible health or safety related issues.
Governmental authorities have considered regulations to limit the
amount of manganese. However, it is not feasible to eliminate
manganese in conventional welds without negatively affecting the
mechanical properties of the weld. The use of other alloying
elements has been considered in an effort to lower total manganese
levels while maintaining sufficient mechanical property levels in
the weld without success. To date it has not been possible to
significantly reduce the use of manganese in conventional weld
wires and electrodes.
SUMMARY
[0006] It has been found that the amount of manganese that is
present in the fume that is generated during arc welding can be
reduced significantly if the manganese is incorporated into the
electrode as a composite particle that contains a shielding
material. As the electrode melts during the welding operation, the
shielding material is believed to prevent the manganese from
vaporizing and oxidizing. As a result, more manganese resides in
the weld deposit and less is present in the fume. The preferred
shielding material is TiO.sub.2 and more particularly rutile
TiO.sub.2.
[0007] Accordingly, one manifestation of the invention is a flux
cored welding electrode in which manganese is incorporated entirely
or partially into the electrode fill as a composite particle of
manganese and shielding material.
[0008] Another manifestation of the invention is a process for arc
welding using the aforementioned electrode. This process is
advantageous because the fume contains significantly reduced levels
of manganese.
[0009] Another manifestation of the invention is a process for arc
welding on low carbon steel substrate using an electrode including
a core fill containing manganese wherein the fume contains less
than 7% by weight of manganese.
[0010] Another manifestation of the invention is a composite
particle of manganese and shielding material that is useful in the
electrode fill of a flux core welding electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic cross-sectional representation of an
electrode in accordance with the present invention;
[0012] FIGS. 2 and 3 are cross-sectional schematic representations
of composite particle morphologies useful in the invention; and
[0013] FIG. 4 is a graph obtained from a study of the amount of
manganese in the fume as a function of the amount of composite
particles in the wires.
DETAILED DESCRIPTION
[0014] The flux cored wire of the present invention includes a
steel sheath and a core composition disposed in the core of the
steel sheath. The core composition is generally between
approximately 1 to 45% of the total weight of the wire. FIG. 1
shows an electrode 10 in accordance with the invention having an
outer steel sheath 12. Electrode 10 is used with a shielding gas 20
which is preferably argon but which may be a mixture of argon and
carbon dioxide or carbon dioxide alone. Within the core 30 of the
electrode 10 is a fill of particulate material including alloying
agents, fluxing agents, and other constituents useful to form the
desired weld bead or molten metal pool 31 and slag 32 when an arc
50 is created between the end of the electrode 10 and the metal
work surface 40. In accordance with the invention, in a preferred
embodiment, in addition to conventional additives core 30 includes
composite manganese-containing particles 60 dispersed throughout
the core. The amount of composite manganese-containing particles is
selected to provide a weld having the desired performance
characteristics.
[0015] The composite particle can take a number of different forms.
Typically, the particle will be a composite admixture of manganese
and the shielding material. Depending upon the ratio of shielding
material to manganese and the process used to form the composite,
the amount of manganese particles exposed at the surface of the
composite particle will vary. In one embodiment, the composite
particle can also be a capsule in which the manganese particle is
entirely coated with a layer of the shielding material.
[0016] FIG. 2 illustrates a typical admixed particle 60 in which
particles of manganese 64 are embedded in a matrix of the shielding
material 62. These particles can vary in structure. The particles
60 shown in FIG. 2 include manganese particles 62 that extend from
the surface to the structure. In FIG. 3, the particle 60 has an
encapsulated structure in which a manganese particle 64 is coated
with the shielding material 62. A composite particle structure is
also possible in which multiple capsules agglomerate to produce the
polycapsular particles. Those skilled in the art will recognize
that the structure of the composite particle can be adjusted by
varying the amount and particle size of the manganese and shielding
material as well as varying the process used to create the
admixture.
[0017] The composite particle 60 used in the present invention
contains about 15 to 40% by weight manganese and about 60 to 85% of
a shielding material. More typically, the particle contains about
20 to 30% by weight manganese and about 70 to 80% of the shielding
material. A most preferred range is about 24 to 26% manganese. The
composite particle ranges in particle size from about -30 to 150
mesh (i.e., less than 30 mesh but greater than 150 mesh) and more
typically is about -50 to 100 mesh.
[0018] The composite particle is present in the fill in an amount
which yields an electrode and a weld deposit having the manganese
content described in the tables below. The amount of the composite
particle in the fill varies with the amount of manganese in the
individual particles themselves and is adjusted to provide the
desired Mn level in the weld deposit. Usually, the composite
particle is present in the fill in an amount of about 10 to 60%
based on the total weight of the fill. FIG. 4 shows the results of
a study in which welding wires were prepared that contained 25, 50
and 75% composite particles in the core composition. The core
composition made up 15% of the wire by weight. The amount of
manganese in the wire remained the same, 2.32%. A shielding gas
containing 75% Ar/25% CO.sub.2 was used. FIG. 4 shows that the
amount of Mn in the fume decreased from 11.6% to 7.37% as the
amount of the composite particle increased. That is a reduction of
36% of the manganese in the fume.
[0019] In the preferred embodiment the shielding material is
TiO.sub.2. TiO.sub.2 is available in the form of rutile and
anatase. Rutile is currently preferred but anatase can also be
used. The function of the shielding material is to shield the
manganese from heating and oxygen during the time that the
electrode is melted and the melted electrode solidifies with the
weld pool. Based on the discovery that composite particles are
effective in preventing vaporization and oxidation and reducing the
amount of manganese in the fume, it will be recognized that
composite particles formed from other shielding materials should
also be effective for this purpose.
[0020] While rutile has been found to be an effective shielding
material, other materials which can coat the manganese particles
and shield them from oxidation during welding can be used. Rutile
is a desirable shielding material because it possesses a relatively
high melting point compared to manganese and it is capable of
insulating the manganese. It is also desirable because it
contributes to the stability of the arc and acts as a slag former.
Thus, other materials having similar properties to those of rutile
in terms of melting point, not destabilizing the arc and forming
slag can also be used in accordance with the invention.
[0021] In accordance with one embodiment of the invention, the
composite particle is formed by dry blending manganese particles
ranging in average particle size from about -60 to 400 mesh with
titanium dioxide particles ranging in particle size from about -60
to 325 mesh. The manganese and titanium dioxide are mixed in order
to provide the desired shielding effect. In one embodiment, they
can be mixed in a ratio of manganese to titanium dioxide of about
1:1 to 1:3. In one embodiment the shielding material has a smaller
particle size than the manganese.
[0022] Typically, to prepare the composite particles, the blend of
manganese and titanium dioxide is dry blended for approximately 10
minutes in a mixing blender. After dry blending, sodium silicate
(water glass) in liquid form is added to the dry blend to bind the
materials together into composite particles. In one example, the
water glass is added in an amount of about 10-15% of the total
weight of the manganese and titanium dioxide. This wet mixture
produces composite particles of approximately 1/4 inch diameter and
less. To dry the particles, they can be distributed in stainless
steel trays to form a bed approximately 1 inch deep. The particles
are baked to remove the water. It is important that baking be
conducted at a temperature which is high enough to drive the water
from the particles but low enough that it does not oxidize the
manganese. Heating one hour at 1260.degree. F. has been found
sufficient to dry particles in a stainless steel tray as described
above. After the particles are allowed to cool to 100.degree. F. or
cooler, they can be ground to a screen size of 50 mesh or less. In
one embodiment, 100% of the particles pass through a 50 mesh
screen, and not more than 10% are held back on a 100 mesh screen.
To remove the water from the composite particle alternate processes
may be applied such as metering the wet mixture at a controlled
rate into an inclined, rotating calciner.
[0023] While waterglass is the preferred binder, other materials
that can be used for this purpose include materials that are
capable of binding the manganese and shielding material into a
composite particle together. Examples of other materials that can
be considered for this purpose include other liquid silicates and
high molecular weight materials such as molasses.
[0024] In addition to containing the composite manganese-containing
particles, the fill material may include conventional alloying
agents, oxide fluxing ingredients, arc stablility and slag former
ingredients. Representative examples of fill additions include
SiO.sub.2, TiO.sub.2, Al.sub.2O.sub.3, ZrO/SiO.sub.2 alloy and
Mg/Al alloy.
[0025] Initial tests show reductions of manganese in fume can be
achieved using argon shielding gas. Reductions of 71% have been
achieved with argon. When using CO.sub.2 and argon mixtures as the
shielding gas, reductions in manganese initially have not been as
great. In accordance with one embodiment of the invention the steel
sheath or fill additionally contains magnesium. It has been found
that with the addition of magnesium to the wire, manganese
reductions of up to 36% are attainable with an argon-CO.sub.2
shielding gas mixture. In one embodiment, the magnesium is present
in the wire and/or fill in a total amount of up to about 3%.
[0026] Flux Cored wires in accordance with two embodiments of the
invention have the wire composition, between the approximate
ranges, by total weight of the wire indicated in Table 1. These
electrodes are formulated to weld on mild steel or low alloy base
materials and to meet AWS specifications for the weld deposit.
TABLE-US-00001 TABLE 1 Flux Core Wire Composition Constituent Mild
Steel.sup.1 Low Alloy.sup.2 C 0.0-0.12 0.0-0.13 Mn 0.5-3.0 0.5-3.75
Si 0.0-2.0 0.0-2.0 Ti 0.05-0.7 0.05-0.7 B 0.0-0.1 0.0-0.1 Cr
0.0-0.4 0.0-10.5 Ni 0.0-0.5 0.0-3.75 Mo 0.0-0.1 0.0-1.2 V 0.0-0.5
0.0-0.25 Al 0.0-0.5 0.0-0.5 Cu 0.0-0.1 0.0-0.75 Mg 0.0-0.5 0.0-0.5
Fe 01.48-99.45 75.87-99.45 .sup.1AWS A5.20-95 Mild Steel .sup.2AWS
A5.29-98 Low Alloy Steel
[0027] In the tables herein elemental percentages are reported to
within one-hundredth of a percent, however, those skilled in the
art will recognize that these percentages reflect industry
standards and are not a technical limit on the invention. In the
most typical embodiments of the invention, the wire (and weld bead)
contains a minimum of 0.5% Mn. In one embodiment the Mn is present
in an amount of about 0.5 to about 4.0%. While it is desirable to
minimize carbon to minimize fume generation, typically the wire
(and weld bead) will contain a minimum of 0.003% carbon. Industry
standards for mild and low alloy steel limit the combined amount of
Cr, Ni, Mo, V, Ti, B, and Mg to less than 0.5%. Higher amounts can
be used without departing from the invention but industry standards
would not be satisfied.
[0028] Core and sheath compositions by total weight of the wire for
flux core wires in two embodiments of the invention are provided in
Table 2 and Table 3: TABLE-US-00002 TABLE 2 Core Composition for
Flux Cored Wires Constituent Mild Steel Low Alloy C 0.0-0.12
0.0-0.13 Mn 0.5-3.0 0.5-3.75 Si 0.0-2.0 0.0-2.0 Ti 0.05-0.7
0.05-0.7 B 0.0-0.1 0.0-0.1 Cr 0.0-0.4 0.0-10.5 Ni 0.0-0.5 0.0-3.75
Mo 0.0-0.1 0.0-1.2 V 0.0-0.5 0.0-0.25 Al 0.0-0.5 0.0-0.5 Cu 0.0-0.1
0.0-0.75 Mg 0.0-0.5 0.0-0.5 Fe 0.0-45.0 0.0-45.0
[0029] A comparison of Table 1 and Table 2 shows that up to about
45% of the iron and all of the other additions may be present in
the core composition. Usually, the sheath will contain some of the
carbon, manganese and silicon that make up the wire composition as
shown in Table 3. These compositions follow AWS specifications and
conventions and are illustrative only. TABLE-US-00003 TABLE 3
Sheath Composition Constituent Mild Steel Low Alloy C 0.0-0.12
0.0-0.13 Mn 0.0-3.5 0.0-3.5 Si 0.0-2.0 0.0-2.0 Fe 55.25-99.25
55.0-99.0
[0030] In accordance with this invention any of the following (but
not limited to) commercially available carbon steel and low alloy
steel metal core wires can be modified as described herein to
incorporate all or a portion of the manganese in a composite
particle. The following tables represent these products and their
typical deposit chemistry. TABLE-US-00004 TABLE 4 AWS Class. C Mn
Si P S Mo Cr Ni V Cu E80T1-A1 .07 .68 .45 .010 .017 .46 E81T1-A1
.04 .83 .26 .014 .016 .48 E80T1-B2 .06 .70 .29 .011 .015 .43 1.33
E81T1-B2 .05 .91 .42 .009 .012 .50 1.50 E90T1-B3 .06 .64 .25 .010
.013 1.06 2.47 -- -- -- E91T1-B3 .05 .64 .27 .011 .013 .93 2.04 --
-- -- E90T1-Ni1 .10 .89 .38 .011 .008 -- -- .98 -- -- E81T1-Ni1 .06
1.20 .57 .009 .015 -- -- .94 -- -- E80T1-Ni2 .05 .90 .30 .012 .019
-- -- 2.33 -- -- E81T1-Ni2 .05 .94 .37 .011 .018 -- -- 2.42 -- --
E91T1Ni2 .08 1.18 .60 .012 .021 -- -- 2.41 -- -- E100T5-D2 .11 2.00
.55 .009 .010 .44 -- -- -- -- E90T1-D3 .06 1.12 .60 .010 .011 .41
-- -- -- -- E80T1-K2 .08 1.11 .26 .009 .019 .01 -- 1.46 -- --
E90T1-K2 .05 1.00 .34 .008 .015 .13 .03 1.41 -- -- E91T1-K2 .05
1.04 .19 .009 .014 .01 -- 1.92 -- -- E90T5-K2 .05 .83 .33 .009 .016
.22 -- 1.65 -- -- E100T1-K3 .05 1.16 .46 .011 .018 .39 -- 1.88 .01
-- E100T5-K3 .08 1.34 .48 .013 .017 .39 -- 1.89 -- -- E110T1-K3 .05
1.15 .50 .010 .012 .52 -- 2.25 .02 -- E110T1-K3 .07 1.55 .34 .009
.0117 .37 .03 1.97 .02 -- E110T1-K3 .05 1.46 .32 .008 .014 .36 .03
2.08 .02 -- E110T5-K3 .05 1.49 .33 .011 .017 .37 -- 2.24 -- --
E120T5-K4 .07 1.88 .42 .010 .016 .61 .52 2.13 .01 -- E80T1-W .05
1.05 .42 .009 .014 -- .52 .67 -- .43 E80T1-W .06 1.30 .70 .008 .014
-- .59 .75 -- .38 E71T1 .021 1.30 0.69 .015 .011 E110T5-K .04 1.5
.41 .01 .014 .42 2.37 .42 E71T-12J .04 0.67 .16 .008 .013 .44
E71J-1M .04 1.24 .29 .010 .015 .37 E81T-Ni1 .068 1.35 .40 .014 .011
1.06 E70T-4 .27 .73 .30 .011 .005 Al = 1.42
[0031] The invention is illustrated in more detail by the following
examples:
EXAMPLE 1
[0032] Composite particles were prepared by dry blending 4.7 parts
by weight manganese particles (avg. particle size about 80 mesh),
33.4 parts Mn/Fe/Si alloy particles having a particle size of about
80 mesh, and 56.7 parts rutile TiO.sub.2 particles (avg. particle
size about 80 mesh) for 10 minutes in a mixer blender. After
blending, 5 parts sodium silicate (containing 3 parts water and 2
parts silicate) was added and blending continued until particles
about 0.25 inch or less were obtained. These particles were dried
60 minutes in an oven at 1260.degree. F. The composite particles
were mixed with conventional fill materials for flux cored wires to
provide the fill composition shown in Table 5 in parts by weight.
The fill composition was deposited on a strip of metal and formed
into a tube which enclosed the particles by drawing it through a
series of forming dies in a manner well known in the art. The wire
contained 15% fill.
[0033] The core, sheath and wire compositions of the wire are shown
in Table 6 where all percentages are based on the total weight of
the wire. TABLE-US-00005 TABLE 5 Mg. Al. ZRO.sub.2 Si/O.sub.2
Al.sub.2O.sub.3 TiO.sub.2 Fe.sub.2O.sub.3 Ti Fe NA.sub.2O
B.sub.2O.sub.3 K.sub.2O Mn Si CaO MgO Fill 49.3% Core 2.3 2.3 2.56
4.65 0.59 29.9 0.02 2.5 0 3.56 0.32 0.67 Comp. Particle50.7% Core
1.76 15.9 1.29 1.4 0.24 13.1 4.9 9.85 0.72
[0034] TABLE-US-00006 TABLE 6 Core 15% Wire 0.35 0.4 0.38 0.96 0.09
6.86 0.2 0.4 0.21 0.57 0.05 0.1 1.96 0.7 1.48 0.11 Sheath 85% Wire
84.7 0.26 Total Wire 0.35 0.4 0.38 0.96 0.09 6.86 0.9 0.4 84.9 0.57
0.05 0.1 2.32 0.7 1.48 0.11
EXAMPLE 2
[0035] A study of the effect of composite particles on manganese
levels in the weld and the fume was conducted using the following
wires:
[0036] Wire 1: A commercially available fluxed cord wire having a
composition that meets AWS E71T-1 Class.
[0037] Wire 2: A wire having the same composition as Wire 1 except
the manganese is incorporated in composite particles prepared using
a CaO plus rutile mix.
[0038] Wire 3: A wire analogous to Wire 2 containing composite
rutile-manganese particles with less manganese available in the
core.
[0039] Wire 4: A wire analogous to Wire 3 except a MgO containing
rutile was used in place of the CaO rutile of Wire 3.
[0040] Wire 5: A wire analogous to Wire 4 but containing less MgO
rutile.
[0041] Wire 6: A wire analogous to Wire 2 having less Mn available
in the core.
[0042] Wire 7: A wire analogous to Wire 6 having less Mg available
in the core.
[0043] Wires 2-7 were prepared using composite particles having the
following compositions: TABLE-US-00007 Wire SiO2 TiO2 Fe2O3 Fe Na2O
Mn Si CaO MgO 2 1.61 14.5 1.18 1.56 0.22 14.76 5.7 9.02 0.65 3 1.57
14.09 1.15 1.72 0.21 14.29 6.59 9.54 0.64 4 0.66 15.41 1.82 0.2
14.34 6.6 10.19 5 0.66 22.51 1.82 0.2 14.34 6.6 3.09 6 1.76 15.9
1.29 1.35 0.24 13.05 4.91 9.85 0.7 7 1.76 15.9 1.29 1.35 0.24 13.05
4.91 9.85 0.7
[0044] Welds were prepared using these wires and the shielding gas
compositions shown in table 7. The gas compositions are identified
using the argon to carbon dioxide ratios.
[0045] Table 7 reports Mn available in each wire (1), Mg available
in each wire (2), Mn in the weld (3), Mn in the slag (4), Mn in the
fume (5), and the Mn reduction in the fume (6). The results show
that by using the composite particle, the level of manganese in the
fume can be reduced. The results also show that the manganese is
more efficiently introduced into the weld. TABLE-US-00008 TABLE 7
Mn Fume Study (1) (2) (3) (4) (5) (6) Mn Mg Mn Mn Mn Mn AVAIL.
AVAIL. WELD SLAG FUME RED. % Shielding Gas: 100% Ar Wire #1 2.59
.15 1.79 7.18 6.2 STD Wire #2 2.59 .15 2.04 5.59 1.77 71 Wire #3
2.52 .15 1.60 4.98 2.05 67 Wire #4 2.51 .15 1.45 6.92 2.55 59 Wire
#5 2.51 .15 1.55 8.08 2.17 65 Shielding Gas 98/2 Ar/CO.sub.2 Wire
#1 2.59 .15 1.47 7.68 5.15 STD Wire #2 2.59 .15 1.77 5.10 4.15 19
Shielding Gas 85/15 Ar/CO.sub.2 Wire #1 2.59 .15 1.55 7.38 5.09 STD
Wire #6 2.32 .15 1.63 4.89 4.67 Wire #7 2.32 .30 1.66 3.89 4.30 29
Shielding Gas 75/25 Ar/CO.sub.2 Wire #1 2.59 .15 1.67 8.45 6.15 STD
Wire #2 2.59 .15 1.83 5.45 4.61 Wire #6 2.32 .15 1.68 4.35 Wire #7
2.32 .30 1.68 3.59 41 Shielding Gas CO.sub.2 Wire #1 2.59 .15 1.43
8.99 5.95 STD Wire #2 2.59 .15 1.60 6.06 5.17 Wire #6 2.32 .15 1.39
6.07 4.71 Wire #7 2.32 .30 1.34 4.75 4.44 25
EXAMPLE 3
[0046] A standard wire (Wire #1) was modified such that 25, 50, 75,
and 100% of the available manganese was introduced into the core of
the wire in the form of composite particles with rutile. The wires
were used in a welding test using a 75% argon and 25% carbon
dioxide mixture. The amount of manganese in the fume was measured.
The results are shown in Table 8. The results show that by
incorporating the manganese in a composite particle, the amount of
manganese in the fume is reduced. TABLE-US-00009 TABLE 8 Wire #1 Mn
in Fume 0% 11.6 25% 10.05 50% 7.87 75% 7.37 100% 8.1
[0047] Having described the invention in detail and by reference to
specific embodiments thereof, it will be apparent the numerous
modifications and variations are possible without departing from
the spirit and scope of the invention.
* * * * *