Note: Descriptions are shown in the official language in which they were submitted.
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WELDING WIRE
FXE~D 0~' THE TNVENTION
The present invention relates to a welding wire for
use in the MIG welding of Ti-based material. More
particularly, the present invention relates to a welding
wire allowing the compatibility between stable arc and
stable droplet transfer, and as a result, enabling the
formation of the excellent bead shape. Further, when a
welding wire of the present invention is used in a Ti
thermal spraying, the stability of arc can also be achieved
and then an excellent coating layer of the thermal spray
can be obtained.
BACKGROUND OF THE INVENTTON
As for the welding of a member made of Ti or a Ti
alloy, MIG welding (Metal Inert Gas Welding) that is more
excellent in welding efficiency has received attention in
place of TIG welding (Tungsten Inert Gas Welding). The MTG
welding is allowed to proceed in accordance with the
following embodiment. Tn a condition that a welding wire
made of Ti or a Ti alloy fed from a wire feeder and a base
metal to be welded are surrounded by a shielding gas, an
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arc is generated between both. The droplets of the welding
wire generated at this step are transferred and landed on
the base metal to be welded, thereby to continuously farm
beads.
The things that matter at this step are:
stabilization of the generated arc; and stable transfer and
landing of droplets from the welding wire on the weld zone.
When the generated arc is not stable, or droplets axe not
transferred to the weld zone with stability, for example,
as shown in Fig. 7, constriction occurs in the formed bead,
and the uniformly overlying state is not achieved. It is
difficult to say that the bead in such a shape ensures the
reliability of the strength characteristics at the weld
zone.
incidentally, Ti is an active metal. Therefore,
when an oxygen-containing gas is used as a shielding gas,
not only the bead surface is oxidized, but also the
reduction of ductility of the weld zone is caused. Such
being the case, in general, a high purity inert gas such as
a pure ~x gas is used as a shielding gas. However, the
following fact is also known: when oxygen is contained in
the shielding gas, the cathode spot upon arG generation is
fixed on the base metal to be welded under the welding
wire; as a result, arc is stabilized (see, Reference 1)
This means as follows: oxygen is supplied to the
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field of the generated arc, so that the cathode spot is
stabilized, and as a result, the generated arc is also
stabilized. Based on such a fact, the following welding
wires of Ti materials have been proposed (see, Reference 2y.
This welding wire is a welding wire configurEd as follows:
on the surface layer portion of a welding wire made of Ti
or a Ti allay, an oxygen enriched layer with a higher
oxygen concentration than that of the inward layer portion
of the welding wire is formed. and the thickness of the
oxygen enriched layer is larger than that of the very thin
natural oxide film present on the surface of the welding
wire.
This welding wire is manufactured in the following
manner. fox example, a Ti material of a preferable
composition is once rolled, and then, heat treated in an
oxygen-containing atmosphere to foam a Ti oxide layer
(oxygen enriched layer) thicker than the natural oxide film
on the surface layEr portion. Then, the resulting welding
wire is cold rolled to a prescribed wirE diameter. Then,
this welding wire is used as a welding wire for MIG welding.
In consequence, oxygen is fed tv the field of the generated
arc from the oxygen enriched layer even when an oxygen-
containing gas is not used as a shielding gas. Therefore,
the c~thvde spot is stabilized. As a result, a bead in a
favorable shape is formed.
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jReference 1] Proceedings of National Meeting of
Japan Welding Society 65 (1999), 276
[Reference 2] J~ 2003-326389 A
However, according to the subsequent study on the
welding wire of Reference 2, it has been proved that, when
MIA welding is carried out with this welding wire, the
following phenomenon occurs.
First, the cathode spot of the generated arc is
situated at the position of the base metal to be welded
under the welding wire as deduced, and stabilized without
fluctuating. However, at the tip of the welding wire,
there are generated two types of arcs: the concentrated arc
in such a shape as shown in dig. $ (which is hereinafter
referred to as a concentrated arc); and the diffused arc in
such a shape as shown in Fig. 9 (which is hereinafter
referred to as a diffused arc). The former arc has been
Stabilized, and the latter arc has been unstable.
Then, when the former concentrated arc is generated,
the tip of the welding wire is invariably released in the
form of droplets, which transfer to the weld zone. Thus,
the shape / outward appearance of the formed bead become
favorable. However, when the latter diffused arc is
generated, droplets may not be released from the welding
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wire tip. Even when droplets are released, the length of
time required for the release is long. Therefore, the
transfer time of the droplets to the weld zone is also long.
~s a result, the droplets cannot transfer to the weld zone
during one pulsed current flow period, so that the next one
pulsed current flow is carried out prior to the completion
of transfer of the droplet.
Far this reason, the overlying state of the formed
bead becomes ununiform, and constriction or the like may
occur partially along the direction of welding. Further, a
large amount of spatters are generated, resulting in the
poor outward appearance of the bead. Such a phenomenon is
conceivably generated due to the fact that the tip of the
welding wire, i.e., the anode spot has been unstabilized.
An object of the invention is to provide a welding
wire which solves such a problem, and whereby both of the
cathode spot and the anode spot upon arc discharge are
stabilized, and hence the arc is stabilized, and the
transfer of droplets is also stabilized.
SUMMARY OF THE INVENTION
The present inventors have made eager investigation
to examine the problem. As a result, it has been found
that the foregoing objects Gan be achieved by the following
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welding wire. With this finding, the pxesent invention is
accomplished.
The present invention is mainly directed to the
following items:
(~.) ~ welding wire cpmpris~.ng Ti or a Ti alloy,
wherein the welding wire has: an oxygen enriched layer on a
surface thereof; and a metal compound ha~riz~g at least one
metal selected from the group consisting of alkali metals
and alkaline earth metals.
(2) The welding wire according to item (1), wherein
the content of the metal compound is x.002 to 0.050 by
weight based on the total weight of the welding wire.
(3) The welding wire according to item (1), wherein
the welding wire has cracks an the surface, and the metal
compound is present in the cracks.
(4) The welding wire according to item (1), wherein
the boiling point of the metal is 2000°C or less.
(5) The welding wire according to item (1), wherein
the metal compound is a metal compound containing Ca.
(6) The welding wire according to item (1), wherein
the value of Tw/Dw is 0.3 x 10"3 to 1 x 10-1, wherein Tw
represents the thickness of the oxygen enriched layer, and
Dw represents the wire diameter of the welding wire, and
wherein the average oxygen concentration of the oxygen
enriched layer is not less than 1~ by weight.
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(7) The welding wire accoxd~.ng to item (6), wherein
the average oxygen concentration of the oxygen enriched
layer is 1 to 40~ by weight_
(8) The welding wire according to item (1), wherein
the surface roughness of the welding wire is 10 ~m or less
in terms of the surface roughness expressed as Ry specified
according to JIS B0601.
(9) The welding wire acaarding to item (6), wherein
the ~ralue of Tw/Dw is 1 x 10'3 to 50 x IO-3, wherein Tw
represents the thickness of the oxygen enriched layer, and
Dw represents the wire diameter of the welding wire, and
wherein the average oxygen concentration of the oxygen
enriched layer is 1 to 30b by weight.
$RxEF DESCRIPTION OF THE DRAWINGS
Fig_1 is a micraphotoqraph of a surface of a welding
wire of the present invention.
Fig. 2 is a cross-sectional microphotograph of a of
a surface layex portion of a welding wire of the invention.
Fig. 3 is a microphotograph of a surface layer
portion before wire drawing during manufacturing of a
welding wire of the invention.
Fig. 4 is a correlation diagram between the
ionization voltage and the boiling paint of each metal.
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Fig. 5 is an explanatory diagram of the concentrated
arc defined in the invention.
Fig. 6 is a photograph showing a bead formed by the
use of a welding wixe of Experimental Example 6.
Fig. 7 is a photograph showing a bead in a defective
shape.
Fig. 8 is a photograph showing an example of the
concentrated arc.
Fig. 9 is a photograph showing an example of a
diffused arc.
DETAILED DESCRIPTION OF THE IN51ENTION
The foregoing effects are achieved by a welding wire
comprising Ti or a Ti alloy, wherein the welding wire has:
an axygan enriched layer an a surface thereof; and a metal
compound having at least one metal selected, from the group
consisting of alkali metals and alkaline earth metals.
In the present invention, the term "welding wire"
has a meaning including a wire rod for thermal spraying
(thermal spraying wire) as well as a wire rod for welding.
First, the surface micraphatograph and the cross
sectional microphotograph of the surface layer portion of
the welding wire of the invention are shown as Figs. 1 and
2, respectively. As apparent from Fig. 1, this welding
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wire is formed such that the surface is covered with an
oxygen enriched layer, arid fine surface cracks generated in
a wire drawing step described later are distributed over
the surface of the entire welding wire. The foregoing
surface cracks are, as shown in Pig. 2, formed as cracks
with a depth from the oxygen enriched layer on the welding
wire surface toward the inward layer portion of the base
material. Then, in the cracks, the compound described
later, including an alkali metal or an alkaline earth metal
is packed.
In the invention, the oxygen enriched layer, and the
average oxygen concentration thereof are defined as follows.
Namely, the cross section of the welding wire is mirror
polished, and is subjected to area analysis by EPMA
(Electron Probe Micro Analysis) as to the oxygen
concentration distribution. The oxygen concentration at
the central part of the welding wire obtained by the
analysis is taken as 1, and the region having an oxygen
concentration of 1.2 or more (x. e., having an oxygen
concentration of not less than i.2 times as large as that
of the central part) is taken as an oxygen enriched layer.
~'urther, the average value (5 measuring points) of the
oxygen concentration in a region with the oxygen
concentration of 1.2 or more is taken as the average oxygen
concentration of the oxygen enriched layer. Tncidentally,
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when the oxygen concentration varies along the
circumferential direction of the welding wire cross section,
concentration measuring circles are set at various position
along the radius of the cross section, arid the oxygen
concentrations axe averaged along the respective
concentration measuring circles, thereby to determine the
oxygen concentration distribution along the radius of the
cross section, averaged along the cireumferential direction.
Then, the region having an oxygen concentration of not less
than 1.2 times as large as that of the central part in the
oxygen concentration distribution along the radius of the
cross section is taken as the oxygen enriched layer.
The thickness of the oxygen enriched layer of the
invention is preferably larger than that of the natural
oxide film generated on the welding wire surface. The
thickness of the natural oxide film is generally 40 to 100
nm.
Further, the oxygen enriched layer of the invention
preferably satisfies the following ~celationship.
Namely, it is preferable that the value of Tw/Dw is
0.3 x 10-3 to 1 x 10°1, where Tw denotes the thickness of
the oxygen enriched layer, and Dw denotes the wire diameter
of the welding wire, and that the average oxygen
concentration of the oxygen enriched layer is not less than
fro by weight. By forming the oxygen enriched layer having
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such a thickness and average oxygen concentration, it is
possible to largely improve the feedability of the welding
wire via a conduit tube of a wire feeder. Further, the
stability of the arc for carrying out axc welding or axc
thermal spraying also becomes favorable.
When the Tw/Dw is less than 0.3 x 10-3 (Tw is 0.03
ofi Dw), ox the average oxygen concentration of the oxygen
enriched layer is less than 1$ by weight, the feedability
improving effect becomes insufficient. F~.irther, the arc
becomes more likely to be unstabilized, resulting in a
disadvantage for forming a uniform welding bead or spray
deposit. When the Tw/Dw is 1 x 10-3 (Tw is 10$ of Dw) or
more, a very lung time is required for the formation
treatment of the oxygen enriched layer, and the effects are
poor for the difficulty of the formation. When it is used
for welding or the like, detrimental effects such as the
reduction of the welded joint strength of the welding
structure may be xather caused.
The upper limit value of the average oxygen
concentration of the oxygen enriched layer is described
below. The average oxygen concentration of the oxygen
enriched layer becomes maximum when the entire oxygen
enriched layer is farmed of titanium oxide. The value
becomes conceivably equal to the oxygen content ratio
calculated from the molecular formula of the oxide formed.
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For examp7.e, when the oxide to be formed is Ti02, the upper
limit value of the average oxygen concentration calculated
from the stoiohiometric oxygen content is 40.06ro by weight
(calculated assuming that the atomic weight of Ti is 47.88
and the atomic weight of oxygen is 16.0). AlternativeJ.y, a
Ti oxide haring a still higher oxygen stoichiometric ratio
of oxygen than that of Ti02 may be formed. For example,
when Tiz05 is formed, the upper lim~.t value of the average
oxygen conGentratzon is 45.52 by weight. Therefore, it is
generally unconceivable that the maximum value of the
average oxygen concentration of the oxygen enriched layer
exceeds 45.52 by weight. As a result, in the invention,
it can be said that the maximum value of the average oxygen
concentration of the oxygen enriched layer is 45.52% by
weight. However, when the value of the average oxygen
concentration of the oxygen enriched layer is set to 45.52$
by weight, adverse effects such as the deterioration of
ductility of a welded joint may occur. Therefore, the
average oxygen concentration of the oxygen enriched layer
is preferably not zaore than 40~ by weight.
In order to make the arc stabilizing effECt more
remarkable, the ratio 7.'w/Dw of the thickness of the oxygen
enriched J.ayer Tw to the wire diameter Dw is preferably
adausted in the range of 1 x 10-3 to 1 x 10-1. Particularly,
when the oxygen diffused layer is formed in addition to the
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titanium oxide layer of the outermost surface layer portion
(with a thickness equal to the thickness of about 40 to 100
nm of the natural oxide film, or larger), the thickness of
the oxygen enriched layer increases by that of the oxygen
diffused layer. Therefore, the possibility becomes higher
that the Tw/~w falls within the foregoing preferable range.
The preferable upper limits of the xw/Dw value and
the average oxygen concentration of the oxygen enriched
layer vary between the case that the welding wire of the
present invention is used as a wire rod for welding and the
case that the welding wire is used as a wire rod for
thermal spraying. When the welding wire of the present
invention is used as a wire rod fox thermal spraying, the
requirement in terms of strength may not be so stringent
fox the spray deposzt as for the welded joint portion in
many cases (of course there are some exceptions). For
example, air may be used as a spraying medium tar molten
metal. xn such a case. the oxygen concentration in the
layer also inevitably increases because the molten Ti metal
is deposited as a spray deposit while reacting with oxygen
in the air. This is, however, sufficient for practical use,
when high strength is not particularly required.
Furthermore, when the welding wire of the present invention
is used as a wire rod for thermal spraying, in view of the
fact that oxidation eventually proceeds in molten state,
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even an increase in the value of xw/pw and the average
oxygen concentration of the oxygen enriched .layer to the
upper limit values does not particularly cause any
hindrance.
On the other hand, when used as a wire rod for
welding, an excessively large thickness of the oxygen
enriched layer or excessively high average oxygen
concentration thereof may sometimes unfavorably cause
degradation of the strength of a welded aoint of the
resulting welding structure or the strength of the spray
deposzt. Therefore, when used as a wire rod for welding,
it is further preferable to restrict the Tw/Dw from 1.0 x
10-3 to 50 x 10-3 (Tw is 1 tv 5~ of I~w), and the average
oxygen concentration of the oxygen enriched layer froze 1 to
30$ by we~.ght. When used as a wire rod for thermal
spxaying, further when a high strength spray deposit is
desired to be formed by uszx~g an inert gas such as argon as
a spraying medium, and minimizing the oxidation, the fw/17w
and the average oxygen concentration. may be preferably
restricted within the same ranges.
The weld~.ng wire of the present invention contains
Ti as a main component. Tn the invention, the woxding
"containing Ti as a main component" means that the
component having the highest content in the welding wire is
Ti. Ti. is pxefexably contained in an amount of not less
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than 50b by weight. then a Ti alloy is adopted, aiming at
the improvements of the strength or the ductility of the
resulting weld zone or the spray deposit, and the like,
various additive elements may be contained as sub-
components. Examples of the adoptable additive element$
and the preferable xanges of amounts of these to be added
are described below.
(1) Al: not more than 9% by weight
A1 has functions of stabilizing the a phase which is
a low temperature phase of Ti, and being solid solved in
the a phase and strengthening it. However, when the
content thereof exceeds 9% by weight, an inte~ctediate phase
(intermetallic compound) of Ti3Al or the like is formed in
a large amount, which leads to the inhibition of the
toughness and the ductility. On the other hand, in order
to make the foregoing effect remarkable, A1 is preferably
added in an amount of nat less than 1% by weight, and more
preferably added within a range of from 2 to 8% by weight.
(2) At least either of N and o: not more than 0.5% by
weight in total
N and O also function as the same ac phase
stabilizing and strengthening elements as with A1.
particularly, the effect of addition of O is remarkable.
However, a total content of these exceeding 0.5% by weight
leads to the inhibition of the toughness or the ductility.
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On the other hand, in order to make the foregoing effect
remarkable, the$e axe preferably added in a total amount of
not leas than 0.03 by weight, and more preferably added
within a range of from 0.08 to 0.2v by weight.
Incidentally, the oxygen content herein denotes the oxygen
content of the inward layer portion other than the oxxgen
enriched layer in any case.
(3y One, or two or more of V, Mo, Nb, and Ta: not more than
45b by weight in total
All of these elements are stabilizing elements of
the ~ phase which is a Ti high temperature phase, and
effective in achieving the improvement of the hat
workability and the higher strength through the improvement
of the heat treatability. However, all of these elements
are high in specific gravity and high in melting point.
Thus, excessive addition thereof nat only leads to the
impairment of the effects of the light weight and the high
specific strength, specific to Ti alloys. but also causes a
difficulty in manufacturing by melting due to the increase
in the alloy melting point. For this reason, the upper
limit of the total amount of these to be added is set at
45~ by weight. On the other hand, in order to make the
effect remarkable, these axe preferably added in a total
amount of not less than 1~ by weight. Mo or Ta may be
added in a small amount for improving the corrosion
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resistance of the alloy.
(4) One, or two or more of Cr, Fe, Ni, Mn, and Cu: not more
than 15v by weight iz~ total
These elements also have an effect of stabilizing
the Ji phase, and are effective in achieving the improvement
of the hot workability and the higher strength through the
improvement of the heat treatability. However, any of
these tends to form an intermediate phase (e. g., TiCrz,
TiFe, Tiz Ni, TiMn, or Ti2Cu) between it and Ti, and
excESSive addition thereof leads to degraded ductility and
toughness. Therefore, the upper limit of the total amount
of these to be added is set at 15ro by weight. On the other
hand, in order to make the effect remarkable, these are
preferably added in a total. amount of not ~.ess than 0.5~ by
weight. Ni may be added in a small amount far improving
the corrosion resistance of the alloy.
(5) At least either of Sn and Zr: not more than 20~ by
weight in total
These elements are known as neutral type additive
elements fox strengthening both of the oc phase and the J3
phase. However, excessive addition thereof results xn
saturation of the effect, so that the upper limit of the
total amount of these to be added is set at 20~ by weight.
On the other hand, in order to make the effect remarkab~.e,
these are preferably added in a total amount of not 3.ess
1?
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than 0.5% by weight.
(6) Si: not more than 0,7$ by weight
Si has effects of enhancing the creep resistance
(creep rupture strength) of the alloy, and improving the
heat resistance. However, an excessive addition thereof
conversely causes the reduction of the creep rupture
strength or the ductility due to the formation of an
intermetallic compound such as Ti5Si3. Therefore, the upper
limit of the amount of Si to be added is set at 0.7$ by
weight. On the other hand, in order to make the effect
remarkable, Si is preferably added in axe amount of not less
than 0.03$ by weight, and more preferably added in an
amount in the range of O.OS to 0.5$ by weight.
(7) At least either of Pd and Btu: not more than 0.5v by
weight xn total
These elements have an effect of improving the
corrosion resistance of the alloy. However, the upper
limit of the amount of these to be added is set at 0.5~ by
weight in ~riew of the saturation of the effect, and the
like, because all are noble metals and thus expensive. 0n
the other hand, in order to make the effect remarkable,
these are preferably added in an amount of not less than
0.02 key weight.
Specific examples of the alloy composition may
incJ.ude the following ones (incidentally, tk~e composition
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is expressed as being headed by Ti, which is the main
Component, followed by sub-components as being connected
with hyphens together with the Composition numerals while
omitting the unit of ~ Y~y weight ifor example, Ti-6b by
weight A1-4~ by weight V alloy is simply expressed as Ti-
6.F1.1-4V) ) ,
[1] a. type alloys:
Ti.-5A1-2.5Sn, Ti-5.5A1-3.5Sn-3Zr-1Nb-0.3Mo-0.3Si,
and Ti-2.SCu
[2] Near a type alloys:
Ti-6A1-2Sn-4Zr-2Mo-O.lSi, Ti-8A1-1Mo-1V, Ti-2.25A1-
2Sn-42r-2Mo, Ti-6A1-2Sn-2Zr-2Mo-0.25Si, Ti-6A1-2Nb-1Ta-
0.8Mo, Ti-6A1-25n-l.SZr-1Mo-0.35Hi~0_15i, xi-6A1-5Zr-0.5Mo-
0.2Sz, and xi-5A1-6Sn-2Zr~lMo-0.25Si
[ 3 ] a ~ (3-- type alloys
Ti-8Mn, Ti-3A1-2.5V, Ti-6A1-9V, Ti-6A1-6V-2Sn, Ti~
7A1-4Mo, Ti-6A1-2Sn-~Zr--6Mo, Ti-6A.J.-2Sn-2Zr-2Mo-2Cr-0.25Si,
Ti--lOV-2Fe-3A1, Ti-QAl-2Sn-4Mo-0.2Si, Ti-9A1-45n-4Mo-0.2Si,
Ti-2.25A1-llSn-4Mo-0.2Si, Ti-5A1-2Zr-4Mo-4Cr, Ti-4.5,A1-SMo,
l.SCr, Ti-6A1-5Zr-4Mo-1Cu-0.2Si, and Ti-5A1-2Cr-1Fe
[4] J3 type alloys:
Ti-13V-llCr-3R1, Ti-8Mo-8V-2Fe-3A1, Ti-3A1--8V~6Cr-
AMo-BZr, Ti-11.5MO-6Zr--4.5Sn, x~.-11V-l~,zr-2A1-2Sn, Ti-l5Mo-
5Zr, Ti~l5Mo-5Zr-3A1, Ti-15V-3Cr-3A7.,3Sn, Ti-22V-4A1, and
xi-J.5V-6Cr-9A1
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(5] Near ~i type alloy:
Ti--10V-2Fe-3A1
(6] Corrosion resistant alloys (while available for welding,
they are particularly useful when a corrosion resistant
coating layer is desired to be formed by thermal spraying):
Ti-0,15pd, Ti-0.3Mo-0.$131, and Ti-5Ta
The welding wire of the invention can be obtained by
once rolling Ti or the Ti alloy ingot into a coil, then
subjecting the rolled coil to an oxidation treatment, and
thereby forming an oxygen enriched layer on the surface.
Specifically, in the welding wire of the invention,
the oxygen enriched layer can be formed by subjecting a
metal welding wire to a thermal. oxidation treatment in an
oxygen-containing atmosphere. The usable oxygen-containing
atmosphere is a gas atmosphere containing an oxygen
compound such as an oxygen-containing nitrogen atmosphere
(including an air atmospherey, or an oxygen-containing
inert gas atmosphere, or in addition, water vapor. For
forming the oxygen enriched layer having a necessary and
sufficient thickness, it is preferable to use an oxygen-
containing atmosphere having a partial pressure of oxygen
of 5 x 103 to 15 x 10'3 Pa. Further, the treatment
temperature is preferably set at,.for example, 500 to 800°C.
On the other hand, other than the thermal oxidation
treatment, there is an adoptable method in which titanium
CA 02521820 2005-09-30
oxide grains are embedded in the welding wire surface, or a
titanium oxide layer is formed by a Vapor phase deposition
process such as vapor deposition or sputtering, resulting
in an oxygen enriched layer. Alternatively, the titanium
oxide layer may be formed by a known sol~gel process. xhen,
when the titanium oxide layer is formed according to any of
these methods, it ~.s further preferable that the oxygen
diffused layer is fiormed by a diffusion heat treatment.
Fig. 3 shows the cross sectional microphotograph of
the a coil welding wire in the foregoing state. As
apparent :~rvm Fig. 3, no crack is generated in the surface
made of the oxygen enriched layer at this stage.
Subsequently, the coil welding wixe is subjected to
a cold wire drawing processing, resulting in a welding wire
with a preferable wire diameter. At this step, depending
upon the magnitude of the surface reduction ratio, in the
surface of the weld~.ng wixe, cracks are formed from the
surface toward the inside of the welding wire as shown in
Fig. 1, which are generated in the farm of a large number
of surface cracks in the surface layer portion of the
welding wire.
Incidentally, in the invention, the surface
reduction ratio is defz.ned as the following equation:
Surface Reduction Ratio (%)
(Cross sectional area of welding wire before wire drawing - Cross sectional
area
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of welding wire after wire drawing) I (Cross sectional area of welding wire
before wire
drawing) x 100
Then, finally, in the surface cracks, a metal.
compound having at least one metal selected from alkali
metals and alkal~.z~e earth metals is packed. thereby to form
the welding wixe of the in~rention shown in Fig. 2.
In th~.s manner, the welding wixe of the invention
having an oxygen enriched layer and a metal compound is
manufactured.
As these metal compounds, metal. compounds such as
carbonates are preferred. In particular, sodium carbpnate,
potassium carbonate, and calcium carbonate are preferred.
The method for packing a metal compound in the
cracks is described below. As the packing method, for
example, mention may be made of the following method: any
of these metal compounds is m~.xed in a lubricant, and wire
drawing is carried out by the use of the lubricant for the
cold wire drawing; as a result, surface cracks are
generated, and at the same time, the lubricant is packed
therein; rasultingxy, a metal compound is packed in the
surface cracks.
The amount of the metal compound to be packed may be
adjusted by, for example, changing the mixing ratio of the
metal compound with the lubricant, changing the thickness
of the oxygen enriched layer, or changing the surface
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reduction ratio in wire drawing.
Incidentally, the one including a compound such as
Calcium hydroxide and calcium stearate is gezzerally used as
the lubricant. To such a lubricant, for example, a
carbonate of a prescribed metal i$ mixed, so that the whole
of the metal is packed in the surface cracks with being
combined with ca~.czwm.
Therefore, when a compound of a metal other than
calcium is packed, the following procedure may be adopted.
The welding wire is once washed after wire drawing, thereby
to remove the lubricant from the surface cracks. Then, by
the use of a prescribed metal compound, the welding wire is
passed through a wire drawing machine with a surface
reduction xat~.o of
When preferable alkali metals or alkaline earth
metals are contained in the lubricant itself, wire drawing
may be carried out by the use of the lubricant.
The weJ.ding wire of the i.zwention zs useful as a
wire rod fox welding used in MzG welding of a Ti material.
Further, the welding wire of the invention also has the arc
stability and the droplet transfer stability. Therefore,
it can also be used as a wire rod for thermal spraying in
an arc thermal spraying z~ethod.
Tn the invention, examples of the alkali, metals
include Li, Na, K, Rb, and Cs, and examples of the alkaline
23
CA 02521820 2005-09-30
earth metals include Ca, Sr, and Ba. further, an
appropriate metal is selected from alkali metals, and
another appropriate metal is also selected from alkaline
earth metals, and the compounds thereof may be used
together. Namely, the alkali metal and the alkaline earth
metal may be contained together.
The metal compound of the invention preferably has a
metal having a boiling point of 2000°C ar less, more
preferably 600 to 2000°C, among the alkali metals or the
alkaline earth metals. Particularly, it preferably has one
or more of K, Na, Ca. E'urther, a metal compound containing
Ca is fuxther preferably used.
xhe content of the metal compound is preferably set
at 0.002 to 0.050 by weight based on the total weight of
the welding wire.
This is for the following reason. When the content
of the metal compound is less than 0.002 by weight, the
effects of the metal compound are not sufficiently exerted.
Accordingly, the rate of ocGUrrence of the concentrated arc
becomes small. As a result, ~t becomes difficult to attain
the object of generating one droplet during one pulsed
current flow period. This causes a difficulty in forming a
good bead. when the content of the metal compound is
larger than 0.050 by weight, the arc force becomes too
strong. Thus, in the process of transfer of the droplet to
24
CA 02521820 2005-09-30
the weld zone, the spattering phenomenon occurs centering
on the droplet. As a result, outward roughness is
generated certainly in the bead, but also i.n the sites
other than the weld zone.
Further, in view of the implementation of one
droplet during aria pulsed current flow period, the content
of the metal compound is preferably 0.007 to 0.015% by
weight based on the total weight of the welding wire.
A11 of these metals have lower boiling point and
ionization potential than those of Ti which is the main
component forming the base material. This is shown in Fig.
4. These metals are present in the cracks on the surface
layer portion of the welding wire of the present invention.
Therefore, during MxG welding, prior to melting of the base
material (xi) by the arc heat, these metals are present in
the field of the arc in the form of ionized metal vapors.
For this reason, the generated arc becomes a concentrated
arc, and stabilized.
Incidentally, the terra "concentrated arc" referred
to xx~ the invention is defined as the following arc. This
is described by reference to Fig. 5. A welding wire with a
d~.ameter D is arc discharged, and the boundary portion of
the arc is visually observed, The arc so blurred that the
boundary portion cannot be identified is naturally not
recognized as the concentrated arc, but referred to as a
CA 02521820 2005-09-30
diffused arc.
Then, a truncated cane having a bottom face at a
position lower than the lower end face of the welding wire
by the diameter D of the welding wire is assumed. The arc
in the case of 8 Z 60 °, where 9 denotes the angle formed
between the $ide face and the bottom face of the truncated
cone, is referred to as the concentrated arc. When it is
set that B ~ 60 °, it is invariably possible to foam a
droplet.
Since the welding wire of the invention has
characteristics described abover it can be used for a wise
feeder such as an apparatus for carrying out MIG welding.
The surface roughness of the welding wire surface of
the invention is preferably 10 ~m or less in terms of the
maximum height, which is referred to as Ry, from the
viewpoint of improving the feedability of the welding wire
in the wire feeder. Then, the oxygen enriched layer is
farmed with the foregoing thicJmess and average oxygen
concentration. This advantageously acts for obtaining the
welding wire surface which has been adjusted in surface
roughness to such a numerical value. The surface roughness
of the welding wire is preferably set at 0.5 dun ar less in
terms of the arithmetic average roughness Ra. Further, the
lower limit values of the maximum height Ry and the
arithmetic average roughnes$ Ra are riot particularly
26
CA 02521820 2005-09-30
restricted, and are appropriately set in view of the
tradeoff with the cost. Incidentally, the present
inventors confirmed that ~y can be reduced to about 1.0 Eun,
and that Ra to about 0.1 Vim. Incidentally, in this
specification, the surface roughness denotes the one
measured by the method specified in JIS: 80601 (ig~4).
In order to prevent the buckling of the welding wire
in the wire feeder, the tensile strength of the welding
wire is preferably 400 to 1500 MPa. When the tensile
strength is less than 400 MPa, it becomes difficult to
sufficiently prevent the buckling, When the tensile
strength exceeds 1500 MPa, the flexibility of the welding
wire is impaired, leading to deficiencies such as breakage
and a difficulty in winding. The tensile strength of the
welding wire can be controlled by, fox example, the
adjustment of the surface reduction ratio of the cold
working when the final stage of the wire drawing is carried
out by cold working, or by the adju$tment of the annealing
temperature and the time when annealing is subsequently
carried out for strain removal. The tensile strength of
the welding wire is more preferably 400 to 1200 Mfa.
EXAMPhES
27
CA 02521820 2005-09-30
The present invention is now illustrated in greater
detail with reference to Examples and Comparative Examples,
but it should be understood that the present invention is
not to be construed as being limited thereto.
Experimental Examples 1 to 25
(1) Manufacture of welding wire
Ti welding wire specified according to JTS H4670
(JIS Class 2, wire diameter 1.6 mm) was used for preparing
Experimental Examples. Experimental Examples 1 to 22 each
having a thick oxygen enriched layer were prepared by being
subjected to a heat treatment in an air at a temperature of
750°C for 6 minutes to form an oxygen enriched layer on the
surface. Experimental Examples 23 to 25 each having a thin
oxygen enriched layer were prepared in the same manner as
in Experimental Examples 1 to 2Z except that a temperature
in a heat treatment was set at 450°C.
On the other hand, powders of carbonates of the
alkali metals and the alkaline earth metals shown in Table
1 were prepared. As a lubricant, KOSHIN (a mixture of
calcium hydroxide and calcium stearate, trade name,
manufactured by KYOEISHA Chemical Co., Ltd.) was prepared.
By the use of the lubricant, a wire drawing processing was
carried out cold, resulting in a welding wire with a wire
28
CA 02521820 2005-09-30
diameter (Dw) of 1.0 mm. The surface reduction ratio at
this step was 37.5.
When a metal other than calcium is allowed to be
present alone with the oxygen enriched layer, the welding
wire after wire drawing was once washed with LTGHT ChEAN
(detergent) to wash off KOS~rN. Then, the welding wire was
passed through a wire drawing machine by the use of a
powder of a prescribed metal carbonate with a surface
rEduction ratio of 0~, so that the powder was packed in the
surface cracks. Experimental Example 25 that does not have
a metal with the oxygen enriched layer was prepared by
merely being washed in the same manner as the above after
wire drawing. Each resulting welding wire was measured
for the metal content (~ by weight) of the metal compound,
the thickness (Tw: dun) of the oxygen enriched layer, the
tensile strength (MPa), the surface roughness, and the
coefficient of dynamic friction according to the following
specifications.
Metal content: It is analyzed by the inductively
coupled plasma emission spectrometry.
Oxygen enriched layer: As described above, the cross
section of the welding wire was mirror polished. The
polished surface was subjected to area analysis on the
oxygen concentration distribution by EPMA. The oxygen
concentration at the cross section central part was taken
29
CA 02521820 2005-09-30
as 1, and the region of the welding wire having an oxygen
concentration of 1.2 or more (i.e., having an oxygen
concentration of not less than 1.2 times as large as that
of the central part) was taken as the oxygen enriched layer.
Average oxygen cpnGentration: As described above,
the average value (5 measuring points) of the oxygen
canGentxation in the oxygen enriched layer was determined,
and it was taken as the average oxygen concentration of the
oxygen enriched layer.
Thickness of the oxygen enriched layer: It was taken
as the average value of the thickness of the oxygen
enriched layer.
Tensile strength: A 100-mm long test piece was cut
out Pram each welding wire, and pulled at a cross head
speed of 1.0 mm/min by means of an Instron type tensile
tester. Thus, a stress-strain curve was determined, and a
maximum stress value was read as the tensile strength.
Surface Roughness: A roughness curve was determined
with a method specified by JIS B0601 (1994), in accordance
with an embodiment in which the assessment length was set
along the longitudinal direction ofi the welding wire. The
values of the maximum height Ry (gym) and the arithmetical
average roughness Ra (~.un.) were respectively read therefrom.
Coefficient of dynamic friction: This was measured
by using a 8owden~Leben-type friction tester. Specifically,
CA 02521820 2005-09-30
a welding wire sample was set on a sample table, a steel
material for pressing was stacked thereon from above, and
the sample table was moved at a constant velocity while
pressing the steel material by a weight with a given weight.
The frictional force at this step was detected by means of
a strain gauge type load sensor.
The foregoing results are summarized and shown zn
Table 1.
31
CA 02521820 2005-09-30
..
ca N N N N N N N N N N N N
E
O O O G O O O o o O O O
N ~ ~ 0 0 0 0 o d o o a o 0
a
~ r c~ ~ r- r ~ r ~ ~ r r
v
0
C
~ er d' ~r v d' ~r ~r ~ v er ~ 'a
E
O
r r r ~ ~ ~ r r ~ r ,r t-
C O G o 0 o O O O o c O
d
.~
w
Q
U
O O o O O c5 O O O C7 O o O
~ C O O O O t~ ~ p O O O o
O O O 00 a0 CO do 00 00 O o0
O O O O O O o O p p O O p
a0 c~ ao ao 00 00 cti o o ai atio0
c
~o
c
C O d O O O 4 O o o p O
N N N N CV N N N N N N N
C
.C
d
~~
C d
C
N
d
C
~
O t5 O O C 4 O O O O Q O
ao m ad co ~o o as ac ap ao 0 00
r
o sn
0
--, o ec~~ ~ ~n N ~ us o, o 4 0
~ O ~ o 0 is ~C
~_
E
~
~ ~ Q O 0 r o Y Y p1 m
'C 0
N
a~ ~ o, o d
~
3
a '~ o o ~ ~ vi
E .
~ .
.. _ ' o ~ ~ r,
c -~ z Y ~ C1 U V? m o
_ p v O
~
W ca
is ~ Z V U
aW
~ o 0 0 O O a
a"5
~
O 0 ~; O v : o
s- ~ ~ r r r r r s- r ~ r
W
v
. .~..w~ ~ W ~ ~.. ~ .~. ,~ _c0_c9
a- N of ~ u9 l0 i~ CD O r N
C G C C C ~C ~ ~ ~ C C C
~ r T
E a E E E E E E E E E E
N a '~ o. o_ o. a a a n a a c
'~ ~ 'w 'w 'C c 'c 'C 'C w 'c 'C
E ~ E E E E E E ~ ~
o~ as of N ~ ro a~toa~ m N m a~
ev m t ~p ~ ca wt'~ca m
w ~ i ~ ~ w 'u'~
'u5'u~ ~ tip u'~
t~
H
CA 02521820 2005-09-30
N N N N iV c~ C~ ~ N N N tV N
C? O O o C O G O C O C O O
O o O O O O O Q O O O O 4
r r t- ~ r r r .~-~~ r r r r
d~ 'd' ~1'ef''d'd~ ~ ~d'~1 d' d~ ~
r r ~ c- r~ r r y~ ~ r ~ r
O O O Q G Ci O O p O O O C
O O O O O O p O O G O O~ O
~ CO CD
op a0 0D 00 Cd ap a0
O Q 4 O O O O O, C, O ao c0 aD,
a0 aD 00 CO 0C)a0 ~ 00 CJ iG O O O
O O O 4 4 C O 4 ~ C O O Q
N N N N N N N N N N N N N
M
r7
O O 8 O G7 O O O O O ao 00 ~
0D G7 api00 EO Ib a0 00 00 00 O O O
O C _O tt!p Q O t17
O 4 O Q Q Q
C o O C1 p O O G
r O r
U V ~ m U U m V ~ ~, 0
0
~ o
N N ~ o o is eo id
~ Y
Q o O ~ Z V
0 0 o 0 0 , 0
0
Z Z Z ~ ~ ~ ~G
o o, o, o, o ca o, ~ o o o ~
r- r r e- r ~ r t- r r ~ w v-
ca ~ ~ c~ to ,~ ~ ca is ~ c~ co Tn
M ~ ~!7 tp i~ CO W O r ~ rs d' 47
g r c C ~ ~ C C ~ G ~E C
r- r r- A r N N N N N
Q7 W ~ m m 47 47 G~ G) 07 d N G?
~! ~1 d C~ ~ ~o _m G7 E'd ~ E~ d Q~
~ E E Ec E
Ea Eo. Eo.Ea ~ . E c . L a
~ m ~w ~m o ar3 ~a~. ~ ~a~ ~m
o. o, o, E n a ~ ~ ~ ~m m' ~ ~
~ 4 s~. fl. W n n
~ ~ n 0.
uxr~uu u~ ~ 'u~~ u'~u~Wi ux t~~u'~~u~~
~
CA 02521820 2005-09-30
(2) MIG welding
MIG weldings under the conditions shown in Table 2
were carried out using each welding wire shown in Table 1.
Tn these MIG weldings, Digital Pulse CPDP-350 (manufactured
by l7A.xI~EN Corpoxatiox~) was used as a welding electric power
source.
Tab~.e 2
Welding current 80 A
Arc voltage 18 V
Pulse peak current 320 A
Pulse peak time 1.2 ms
Base current 30 A
Rise time 0.4 ms
Fall time 0.8 ms
Welding speed 600 mmlmin
Shielding gas amount Pure Ar, 15 Umin
After shielding gas Pure Ar, 40 Umin
amount
Back shielding gas amountPure Ar, 10 Umin
Conduit Tube made of metal, length
1500 mm
The f8edability of the welding wire during welding,
the stability of the arc, and the amount of spatters
generated were evaluated according to the following
specifications. The shapE of the bead formed, and the
34
CA 02521820 2005-09-30
tensile strength and the elong~.t~.on of the joint portion
were evaluated according to the follow~.ng specifications.
Feedabi.lity of the welding wire: The case where no
buckling of the wire had been generated during welding was
rated as "TEA", and the case where the buckling of the wire
had been generated was rated as "B".
Stab~.lity of arc: The state of the generated arc was
photographed by means of a High Speed Camera System Model
1000 (one image / 1 ms; manufactured by Nao znc.), over 5
seconds after 2 seconds to 7 seconds from the start of
welding. xhus, the stability of the arc was rated from the
image.The case where the rate of occurrence of the
concentrated arc had been 80~ or more was rated as "AA",
the case of 65 to 60~ was rated as "A", and the case of
lower than 65~ was rated as "B".
Amount of spatters generated: Amount of sputters
generated was rated by an amount of sputters having a
diameter of 1 mist or more, which were deposited on the base
metal, with reference to a welding length of 100 mm. After
the completion of welding, the state in which spatters had
been deposited on the base metal to be welded was visually
observed. The case where no spatter having a diameter of 1
mm or mare had been depos~.ted was rated as "AA", and the
case where 1 to 10 spatters having the diameter range had
been deposited was rated as "A", arid the case where 11 or
CA 02521820 2005-09-30
more spatters having the diameter range had been deposited
was rated as "8".
Bead shape: After welding, the bead was visually
observed. The case where the width had been uniform and
the outward appearance had been smooth was rated as ".~1.~1",
az~d the case where irregularities of the width of the bead
had been small was rated as "A", and the case where
irregularities of the width of the bead had been large was
rated as "g".
Tensile strength of the joint portion: xhe case of a
measured value of 340 MPa or more was rated as "AA", and
the case of a measuxed value equal to, or smaller than this
was xated as "B".
The foregoing results are summarized and shown in
Table 3.
36
CA 02521820 2005-09-30
c
'Q
H
' ~'
a
~N
L
N
H
L
~i
""
.
.
G.
N
O
m
.3 O
4
M
f~
Oi
C
b
N
td
m
m
V,
r .~ ~ .~~..~ .~ ~ ~ ~ r~ ~
C N f9 ~' Vii!~ ('~Gp ~7 ~ T'
C c C c c ~ ~
~
N m ar p7 u~ m c c ~ c m
~ ~ ~ m ~ d m m N d~ m
~ m d m
C ~ '~ '~ ~ C ~ 'C 'C
~ ~ ~ E ~ ~ E ~
o_~~.~ ~.~n.~a c.~~' o.~'
' ~ ~ ~
'
~
u~ ~ u ut u~ si u~ ts~
u !
m
m
H
CA 02521820 2005-09-30
x
dd 4d ~d ~ ~ ~ ~ d ~ a ~t m
dd ~ ~d ~ ~d ~ ~d ~ "~ ~ ~
0
N_
G
Q
E
d
woc",~c~~~ c~u~ ~~ ,~r..~qo4~a~~go ~~r ~N ,f~c~~~ n"Wrs
~ ~ r C ~ C C r ~ ~ C ~ ~ c ,p
r s- a~ r r- ~~ N N N N N N
d N 0~ v N m 1 d1
N N
N G1 m a7 m N dy ~ m A1 N m q
91 m N ~
. ' ' ' , _
~
o.~~.~ ~~ ~ d .~am ~.~ ~ o.~ .~~~ ~ a~ v.~ i
' o ' ~ ' o w ' ~~ ~
~ixwu~ ,.,.,t'~ u~ ~w '~u)'~,~~~ ~ ~ ,~w ~ x
~,,, u'f ~u
CA 02521820 2005-09-30
As apparent from Tables 1 and 3, when a welding wire
of Experimental Example having an alkali metal or an
alkaline earth metal is used, the arc is stabilized, and
the bead shape becomes favorable in any case- Further, in
Experimental Examples 1 to 20 in each of which the welding
wire contains a metal compound in a proper amount, the
effects are more excellent.
However, when the welding wire of Experimental
Example 25 which does not have a metal compound at all, and
in which the thickness of the oxygen enriched layer is
small, is used, the generation of the concentrated arc is
reduced, and the amount of spatters also increases,
resulting in a degraded bead shape.
Incidentally, the photograph showing the shape of
the bead formed by the use of the welding wire of
Experimental Example 6 is shown in Fig. 6. As apparent
from the drawing, use of this welding wire enables the
formation of a bead with a uniform width and also in a
uniformly overlying form, and good in both the outward
appearance and the shape.
Experimental Examples 26 to 41
welding wires were manufactured in the same manner
as in Experimental Examples 1 to 25, except that Ti alloy
materials having constituents shown in Table 4 were used as
39
CA 02521820 2005-09-30
the base materials and that the alkali metals and the
alkaline eaxth metals were used according to the type and
contents shown in Table 4.
CA 02521820 2005-09-30
H N N N N N CV N N N C~ CV
v O O o 9 O t7 O O O O O
~t
4J ~ ~ ~ o 4 O ~ O 6 O O O O o
T t- T
_U
O ~ V' tt ~ '~ '~T '~l' eh st ~ V'
V r T r' T r r Y"
O CJ C O O O C1 0 d 0 0
U o
o Q 4~ ~ o q ~ i° °o
r r
r ..- t~ 1' r r
m~
a0 try, o O o O 6 o a0 of 4
O o a0 aC ep 0J oo a0 o O a7
H X.
N tOV N ~ c~~ N COV N cOV N
e2
m
a7 e0 o c7 O o O o ep a0 O
t'; O a0 00 aD ap a0 a0 o G CO
Q'
O m
m~~ oo~o_~__~o_°doc°o
Q Q Q ~ O O ~ ø ~ O
O O ~ d ~ O Q 4 p d 4
c J.7 j< ~ ~ ~ SC ~ SG tj SC ~ SC
R
o~oooo,c?ooo,o
r ~ r% r v- r~ ~ T
'v .....
N' N
°v u~
~r c~ '~ v~ a v 'Q > ? .
2 a.
,
~ ,o ~ ~ c
m ~ ~ o ';~ ~ ~ ~ o o ~ ~ ';i o
_, ~ ~ a~
N N ~ ~ ~ ~ ~ ~" ~ N
i
E= (=
GN G~ ~~ .~.~N ~~ GN ~~j C~ C~ C~'~7
o~ m m d as as m ca as of m m as as m m m ~r m
'EC G ~ G ~ ~~ ~ ~ ~ ~ E ~ E ~ E'
H
CA 02521820 2005-09-30
N N ht N t~
O o O Q
o O 4 O S5
r t- r
~C s~'V V_' V_'
. .,..
r
C o 0 o p
0
h
O m c0 c? O
alb G G OJ CD
N N N N N
O t4 OD 6 0
Q S? a! o7
N
4'
0
o v $ ~ o
O G o 0 0
v z m
Y.
0 o c v o
Y- Y e~ r ~
O
N r Y
C o
N
N
n
C
~t
p,
CA 02521820 2005-09-30
By the use of the welding Wires of Experimental
Examples 26 to 41, MIG welding was carried out. The
results are shown in Table 5.
43
CA 02521820 2005-09-30
C
o>
a' i
n
m
g.
tit
~d ~ ~ a ~ d ~ Q
c om ~ ~ '~ ~d ~ ~ dd ~ dd dd a
C
-
a
U
.~-_T
C_
'O
'~
m
a~
~G ~0 l~ ~ ~ ~ ,~ ,l~~ t~
i0 ~. W Of p r N CY!d- Ip
~ ~ C c ~ c C ~ e0 M
N N N N t"7t'7t'7 c0
91 ~ ~ ~ ~ ~ ~ ~ ~ N
m d1 d~ d~ o m m
~ ~ ~ ~ ~ d ~ .~ ~
W t~Q R ~ N ~ tie 1~0
'~ '~ ,~ ,~ '~ ,,u'~Is~ ,~ t'~au to
ti5u1 w u~ u'~ t~
N
CA 02521820 2005-09-30
a Q ~ ~d
a ~ ~ a a
a
C G C
M M
N a1 ~b
~ ~
~ Q ~ ~
~
Q. Q u'~wO. O.
~ i~~ U~ '~u'~
~i~ X
u
U
CA 02521820 2005-09-30
Experimental Examples 42 to 53
Welding wires were manufactured in such a manner
that the base material was made of JZS Class 2 as in the
case of Example 1-24 and that the alkali metals and the
alkaline earth metals were used according to the type and
contents shown in Table 6.
46
CA 02521820 2005-09-30
l0 N N N N N N N N t~(h1 N N
~
V ~ O O O O Q G , O O O O Q
~ ~ O
C
> n
> 5~ C7 ~1 C O O O O O t~ O O O
p ~
W .' r" r r r r r r ~ s-~r r r
3
wr
V
C
'ta tp CD to Sd t0 cD (D tp cp tD ~ cD
N
O
c r ~ ~r r ~- r r ~ r r ~ r-
~ O O O O O O o o O Q C O
U
o
a~
~
..,
0 0 0 0 0 0 0 ~ 0 0 0 0
h. A T~ 1r.i'-h~ 1'~1~ 1'.!~ t'.I~
D
M M c~! crfc~SM M M M M
cc m cc ca m co <o ~ cc v o
H cc
..
~
_a
.c
.
~ ~? ~? 4 O O O O O O O Q Q
C
3
N N N N N N N N N N N N
L
O
a
~ ~~
x
o o v o 0 0 o Q Q o a o
r r r r r r r r T '~' Z- T
=A
C O O
GG
C 1." p Q O r ~? O O ~ ~ ~ O G
~ d "
N ~ d O O ~ o O G Q Q O O
~
~ ~ Y
m~ ~ Z V U m m Q o Y U
~ O o
_
E""
to Y Y
L
~
_ m m
s- ~~ ~- ~~ ~~ r r r r r r r
C.~rC.~ W :.n9,rte..yr9 w .~..~~.rr~ +~rw
,p, ~ ~' ~' ~ ~ ~ 'a'u7 ~ ~ It7
C C C C C C C C
C C C c
41 C7 C~ d ~ m G1 ~ m a~ m d
N N W 41 Q~ ~ G~ 07 07 p~ 4? a7
E E E aE E E E E ~ ~ E E
a. a a a 4 c~ a a a a a
N _~ L 'c6'~ 'c 'c 'c '~ . ~ '~ '~5
E E E E E E E 'c E E E
E
'
'~ ~ ~~ u~ ~~ ~~ ~~ u~ ~ ~ ~ a ~
' ~ ~ ~ ~
u~ u u , u , u u u
u 3
CA 02521820 2005-09-30
The welding wires of Experimental.trxamples 42 to 53
was mounted in a thermal spray unit of a wire feeder, and
fed to a welding gun to be thermally sprayed on the surface
of an article to be processed. The feedability of the
welding wire and the stability of the arc at this step were
examined. The results ar~ shown, in Table 7.
Table 7
Evaluation
Feedability ability of
of welding arc
wire
Experimental Example AA AA
42
Experimental Example AA AA
43
Experimental Example AA RA
44
Experimental Example AA AA
45
Experimental Example AA AA
46
f=xperimental ExampleAA AA
47
Experimental Example AA AA
48
Experimental Example AA AA
49
Experimental Example AA AA
50
Experimental Example AA AA
51
Experimental F~campleAA A
S2
Experimental Example AA A
53
The boiling point and the ionizat~.on potential of az~
alkali metal or an alkaline earth metal are lower than the
melting point and the ionization potential of Ti,
respectively. Therefore, prior to melting of the k~ase
48
CA 02521820 2005-09-30
material (Ti ox Ti alloy) by the arc heat, the alkali metal
or the alkaline earth metal is present in the forza of an
ionized metal vapor in the field of the generated arc. For
this reason, the generated arc column becomes stable,
resulting in a concentrated arc. Further, the oxygen in
the oxygen enriched layer also stabilize the generated arc,
and at the same time, reduces the surface tension of the
welding wire surface, so that generated droplets become
more likely to be released from the welding wire tip.
These enable one droplet to transfer to the weld
zone in one pulsed cuxxent flow period in MIG welding with
reliability. As a result, the formation of the bead good
in shape and outwaxd appearance becomes possible.
With the welding wixe of the present invention, the
resulting arc becomes the concentrated arc, and one droplet
transfer can be achieved during one pulsed current flow
pexiod with reliability. Therefore, the shape and the
outward appearance of the bead at the weld zone become
excellent. This welding wire is useful as a wire rod for
welding in MTG welding of a Ti material, or as a wire rod
for thermal spraying at the time of Ti thermal spraying.
While the present invention has been described in
detail arid with reference to specific embodiments thereof,
it will be apparent to one skilled in the art that various
49
CA 02521820 2005-09-30
changes and modifications can be made therein without
departing from the spirit and scope thereof.
The present application is based on Japanese Patent
Application No. 2004-300497 filed on October 14, 2004, and
the contents thereof are incorporated herein by reference.
