Welding wire

A welding wire capable of improving wettability between weld metal and wire surface, thereby providing excellent drawability and weldability in resistance welding of wires is provided. A wire is dipped in an aqueous solution of a sulfide of alkali metal or ammonium sulfide to generate iron sulfide (FeS.sub.2 or FeS) on the surface, whereby the wettability of weld metal to wire surface is improved in the resistance welding of the resulting wires. The S in the iron sulfide is preferably present in an amount of 0.1-20 atomic % as measured by X-ray photoelectron spectroscopy. At least one sulfide of S with an element of Mn, Ti, Cu, Cr, Ni, Al or Zn can be used instead of or in addition to the iron sulfide.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to welding wires used for automatic welding or 
semi-automatic welding of carbon steel or stainless steel and, more 
particularly, to welding wires capable of improving wire resistance 
weldability in manufacturing or productivity, and also improving wire 
feedability in welding. 
2. Description of the Prior Art 
In the manufacture of welding wires, generally, drawing is interrupted 
every lot of raw material. When the drawing is restarted, the wire of the 
following lot is joined to the wire of the lot which was drawn till then 
to omit the wire passing procedure through each drawing die of this lot. 
If the wire should be broken in the middle of drawing, it is necessary to 
quickly join the broken part to restart the drawing. Further, when a 
welding wire is wound onto a spool or housed in a pail pack, joining of 
wires of different lots is frequently performed in order to improve the 
yield of product. In such a joining of wires (wire welding), mechanical 
caulking by use of a sleeve, joining by resistance welding, and 
combination of the both are conventionally employed. 
It is disclosed, for example, to mutually join wires by inserting the end 
parts of the wires to a sleeve having an inside diameter slightly larger 
than the outer diameter of the wire, and mechanically caulking them from 
above the sleeve (Japanese Utility Model Laid-Open No. 6-69411). Although 
the use of this method never causes a dispersion in welding strength nor 
requires any high skill for the joining work, the joined part can not be 
drawn as it is since the outer diameter of the sleeve is larger than the 
wire diameter. 
It is also proposed to mutually connect two wires by reducing the outer 
diameter of the end parts of the wires to insert them to a sleeve having 
an outer diameter substantially equal to the outer diameter of the wires, 
and spot welding the sleeve to hoops in the wire end parts (Japanese 
Patent Application Laid-Open No. 7-116893). When the wires are mutually 
joined by this method, the joined part can not be a commercial product as 
welding wire since the chemical composition is differed between the sleeve 
and the wires. 
Therefore, in the mutual joining of welding wires, generally, resistance 
welding is most frequently used because of its low equipment cost and 
satisfactory appearance and strength of the joined part. As the resistance 
welding method of welding flux-contained wires, it is disclosed to 
pressurize and crimp the wire end part after removing the flux involved in 
the wire in this part, and resistance weld the tip part formed of only the 
metal hoop component (Japanese Patent Publication No. 5-1118). It is also 
known to remove the flux involved in the wire in the wire end part, and 
fill Ni powder into this end part instead of the flux followed by 
resistance welding (Japanese Patent Application Laid-Open No. 6-262392). 
When the resistance welding is executed after the flux is removed as 
described above, a welded product of constant quality can be provided, but 
a problem of complication of welding work arises. 
The resistance welding of wires is mostly executed by polishing the end 
surfaces of two wires to be joined, nipping the end surfaces of the wires 
by electrodes so as to be opposite to each other to contact pressurize the 
both, and also applying a current thereto. When the current is applied to 
the two wires, the contact pressurized wire end surfaces and the wires 
around them are heated and molten by the Joule heat by the 
current-carrying. When the current is I, and the electric resistance of 
the part to which the current is carried is R, the Joule heat W is 
calculated by the following mathematical expression 1. 
EQU W=I.sup.2 .times.R 
The current I is generally alternating current, and the Joule heat W 
corresponds to the value obtained by multiplying the square of the ac I by 
the resistance R of a weld. When the wire end surfaces are arranged so as 
to be mutually opposed with pressure, and the both are joined together by 
resistance welding, the resistance R is the highest in the contact of the 
wire end surfaces. Thus, the heating is started first in the wire end 
surfaces. 
The contact of the wire end surfaces is instantaneously molten because its 
heat capacity is extremely small to the calorific value, and the two wires 
are pressurized, whereby the molten metal is carried and discharged to the 
circumferential parts of the wires. The discharged initial molten part is 
generally cut and removed by a welding worker. The wire joining by 
resistance welding is widely used as general joining technique since the 
wires can be easily joined together in an extremely short time at low 
cost. 
However, this joining largely depends on the skill of the worker, and has a 
problem in that a weld of high quality can not be constantly formed. For 
example, selection of cut form of wire end surface, pressurizing force, 
welding time or the like depends on the experience of the worker. In the 
joining of welding wires drawn to a product diameter by resistance 
welding, particularly, the wettability of the weld metal not only on the 
weld surface but also near the weld part with the wire surface has a 
significant influence on the product performance as welding wire. When the 
wettability between the weld metal and wire surface is poor, it becomes 
necessary to sufficiently file the surface, resulting in a remarkable 
reduction in efficiency of the wire welding. 
This filing often scratches a sound wire surface which requires no filing, 
and such a damaged wire surface makes the wire feedability or electric 
conductivity unstable in the welding by use of this wire. Further, the 
poor wettability of the weld metal near the weld part causes the breaking 
of the wire, a feeding failure, and an unstable arc in the actual welding 
by use of this wire. According to the recent improvement in quality of 
welding wires, the welding uniformity of the weld part which was not a 
problem in the past is also required to be improved. 
When wires are mutually welded only for joining purpose, the current I is 
properly selected for resistance welding according to the kind of wire 
such that whether the wire is for soft steel or for stainless steel, or 
whether the cored flux is present or not since the resistance R of the 
wire is changed depending on the chemical composition, dislocation density 
and flux ratio of the wire, whereby the wires can be easily joined. 
However, when the performance as welding wire is also taken into 
consideration, with respect to the part joined by resistance welding, the 
control of only the resistance welding current is not sufficient, and an 
improvement in wettability between weld metal and wire surface is an 
essential condition in order to provide an excellent performance as wire. 
Further, characteristics desired as welding wire include satisfactory wire 
feedability. A number of attempts were made to improve the wire 
feedability in the past. The improvement in wire feedability by adhering 
sodium salt or potassium salt of a higher fatty acid such as stearic acid, 
oleic acid, linoleic acid, linolenic acid or the like to the wire surface 
and applying a lubricating oil thereon after finish drawing (Japanese 
Patent Application Laid-Opened No. 1-166898) and the improvement in wire 
feedability by retainably adhering an oily lubricant containing sodium 
carboxylate or potassium carboxylate onto the wire surface (Japanese 
Patent Application Laid-Open No. 2-284792) are known. In these method, 
proper quantities of alkali salt of higher fatty acid and lubricating oil 
are adhered to the wire surface, whereby the wire feedability is improved. 
Since the metal salt and lubricating oil are likely to be peeled from the 
wire surface and accumulated within a spring liner when the welding work 
is executed over a long time, the oil is deposited in the spring liner, 
and the wire feedability is consequently lowered. Such a peeling is 
resulted from the weak bonding strength of the wire surface with the 
higher fatty acid salt and the lubricating oil. 
SUMMARY OF THE INVENTION 
This invention has been achieved to solve such problems described above. An 
object of this invention is thus to provide welding wires capable of 
improving the wettability between weld metal and wire surface in joining 
of wires by resistance welding, whereby excellent drawability, 
weldability, and wire feedability can be provided. 
One welding wire according to this invention is characterized by that at 
least one iron sulfide selected from the group consisting of FeS.sub.2 and 
FeS is present on a degreased wire. The "presence of iron sulfide" 
referred to herein means the state where FeS.sub.2 or FeS is generated 
over the whole wire surface and, in other words, that the peak of 
FeS.sub.2 or FeS can be confirmed over the whole wire surface when the 
wire surface is analyzed by confirming the presence of the iron sulfide by 
X-ray photoelectron spectroscopy described later. 
Since the presence of the part other than FeS.sub.2 or FeS on the wire is 
naturally conceivable when the wire surface is more microscopically 
observed, it is not objectionable that the peak of a material other than 
FeS.sub.2 or FeS is simultaneously observed in X-ray photoelectron 
spectroscopic measurement. 
The S present as the iron sulfide (FeS.sub.2, FeS) is preferably contained 
in an amount of 0.1-20 atomic % by X-ray photoelectron spectroscopically 
measured value. 
The other welding wire according to this invention is characterized by that 
a sulfide of S with at least one element selected from the group 
consisting of Fe, Mn, Pi, Cu, Cr, Ni, Al and Zn is present on a degreased 
wire surface. The "presence of a sulfide" referred to herein means, just 
as the "presence of iron sulfide" described above, the state where a 
sulfide of S with at least one element selected from the group described 
above is generated over the whole wire surface when the wire surface is 
macroscopically observed. In other words, it means that the peak of the 
above-mentioned sulfide can be confirmed over the whole wire surface when 
the wire surface is analyzed by confirming the presence of the sulfide by 
X-ray photoelectron spectroscopy. Similarly to the case of iron sulfide, 
it is not objectionable that the peak of a material other than it is 
observed. 
The S as the sulfide is preferably contained in an amount of 0.1-20 atomic 
% by X-ray photoelectron spectroscopically measured value. 
In this invention, the presence of the iron sulfide (FeS.sub.2, FeS) or the 
sulfide on the wire surface is confirmed by X-ray photoelectron 
spectroscopy. The S content in the iron sulfide (FeS.sub.2, FeS) or in the 
sulfide can be calculated also by X-ray photoelectron spectroscopy.

DETAILED DESCRIPTION OF THE INVENTION 
As a result of the earnest experiments and studies to solve the above 
problems, the present inventors found that wettability between weld metal 
and wire surface can be improved by adhering or generating iron sulfide 
(FeS.sub.2, FeS) on a wire surface, and the iron sulfide (FeS.sub.2, FeS) 
on the wire surface can improve also wire feedability. The S present in 
the molten wire remarkably reduces the viscosity and surface tension of 
the weld metal. Therefore, when S is present in the wire, a burn through 
of weld metal is apt to occur since the viscosity and surface tension of 
the weld metal are reduced by the S in the weld metal in the resistance 
welding of the wires. 
Since S is an activated element, however, the wettability with the adjacent 
solid soft steel (wire) surface is improved by the presence of S, when 
present on the surface of the weld metal, to enhance the wettability 
between the weld metal and the wire surface. 
The presence of the iron sulfide (FeS.sub.2, FeS) on the wire surfaces 
leads to an improvement in the wettability, conformability, or bonding 
strength between wire surface and wire feeding oil, and the wire feeding 
oil is hardly dropped down even when the wire surface is slid with the 
spring liner or the like, so that the wire feedability in continuous 
welding is remarkably improved. 
As a prior art, an arc welding wire improved in wire feedability and 
current-carrying stability by adhering a proper amount of MoS.sub.2 on the 
wire surface is disclosed (Japanese Patent Application Laid-Open No. 
8-19893). Even if S is present on the wire surface in the form of 
MoS.sub.2, however, S is apt to be separated from the wire surface because 
of the insufficient sticking force of S with iron, so that the wettability 
between weld metal and wire surface can not be improved. 
Since S is present on the wire surface in the form of iron sulfide 
(FeS.sub.2, FeS) in this invention, the wire weldability in resistance 
welding can be improved. When S as the iron sulfide (FeS.sub.2, FeS) is 
contained in the wire surface in an amount of 0.1-20 atomic %, 
particularly, the wettability between weld metal and wire surface can be 
more improved. The quantity of S on the wire surface can be measured by 
X-ray photoelectron spectroscopy. In this case, the quantity of S in the 
area to a depth of several nm from the wire surface can be determined by 
atomic %. 
For diffusing the S on a wire surface layer part and concentrating the S, 
it is known to apply various sulfides on the wire surface followed by 
annealing at 650.degree. C.-1250.degree. C. for 1-300 minutes, and plating 
the resulting wire after pickling followed by drawing into a product 
(Japanese Patent Application Laid-Open No. 7-314179). In this method, a 
diffusion layer of S having a high concentration is formed on the wire 
surface layer part, whereby the surface tension of the molten drop is 
reduced to suppress sputtering. Although the effect as S can be expected 
in this method since the S is present as single body on the wire surface 
layer part, it is apparent that the wire feedability can not be improved 
since no iron sulfide (FeS.sub.2, FeS) is present on the wire surface. The 
reason that no iron sulfide (FeS.sub.2, FeS) is generated on the wire 
surface is that the wire surface is annealed at a high temperature of 
650.degree. C. or more in the atmosphere after applying S source thereto. 
Since the decomposition temperature of iron sulfide (FeS.sub.2) in the 
atmosphere is 600.degree. C., the S source on the wire surface is easily 
decomposed and oxidized, and diffused and scattered into the atmosphere as 
sulfur dioxide, or the one not oxidized is diffused as atomic S along the 
grain boundary at high speed from the wire surface to form a diffusion 
layer segregated in a high concentration on the grain boundary, or 
precipitated within the wire as a compound such as manganese sulfide 
thermodynamically more stable than the iron sulfide (FeS.sub.2, FeS), so 
that no film of iron sulfide (FeS.sub.2, FeS) can be generated on the wire 
surface. Even if the iron sulfide (FeS.sub.2, FeS) is left or generated 
even in a trace amount on the wire surface, the iron sulfide (FeS.sub.2, 
FeS) is never left on the wire surface since the wire is pickled after 
annealing. Further, the iron sulfide (FeS.sub.2, FeS) can not be present 
on the outermost surface of the wire since copper plating is performed 
after pickling. 
In this invention, iron sulfide (FeS.sub.2, FeS) is made present in film 
form on the wire surface, whereby the wire feeding oil can be prevented 
from being disadvantageously fallen from the wire surface and accumulated 
in the spring liner. The iron sulfide (FeS.sub.2, FeS) on the wire surface 
has an excellent effect of retaining the wire feeding oil to prevent the 
oil deposit from the wire surface in the spring liner. This can be 
supposed to be due to the effect of improving the wettability, 
conformability, or bonding strength with the wire feeding oil of the iron 
sulfide (FeS.sub.2, FeS) generated in thin film form on the wire surface. 
To generate the iron sulfide (FeS.sub.2, FeS) on the wire surface, it is 
most easy to dip the wire in an aqueous solution of a sulfide of alkali 
metal (NaS, KS or the like) or ammonium sulfide. The most important point 
in the process of generating the iron sulfide (FeS.sub.2, FeS) is that the 
operation is performed at a temperature lower than the decomposing 
temperature of iron sulfide (FeS.sub.2, FeS) in the atmosphere, and it is 
necessary to perform the operation at a temperature of, desirably, 
200.degree. C. or lower which is the decomposing temperature of FeS and, 
at the minimum, less than 600.degree. C. which is the decomposing 
temperature of FeS.sub.2. The iron sulfide (FeS.sub.2, FeS) generated on 
the wire is easily decomposed when passed through an annealing process of 
600.degree. C. or more after generation. Further, in addition to the 
dipping of the wire into the aqueous solution of sulfide, the iron sulfide 
(FeS.sub.2, FeS) can be generated by a gas phase or liquid phase reaction 
using H.sub.2 S gas, but this method is not preferred since it requires a 
high equipment cost. It is necessary not to apply the process of pickling 
or plating which inhibits the effect of the sulfide to the wire surface 
after the sulfide is generated on the wire surface. 
Other than the iron sulfide (FeS.sub.2, FeS), the same effect as in the 
iron sulfide (FeS.sub.2, FeS) can be expected when a sulfide of S with an 
element of Mn, Ti, Cu, Cr, Ni, Al or Zn is generated on the wire surface. 
To generate such a sulfide on the wire surface, the content of a selected 
element is increased in the wire to generate the sulfide of the selected 
element in the same manner as in the generation of the above iron sulfide 
(FeS.sub.2, FeS). 
The generation of the iron sulfide (FeS.sub.2, FeS) on the wire surface can 
be confirmed by ultrasonic cleaning of the wire surface with acetone to 
remove the applied oil and deposit followed by analysis by use of XPS 
(X-ray Photoelectron Spectroscopy) under conditions shown in Table 1. 
TABLE 1 
______________________________________ 
XPS Analysis Conditions 
______________________________________ 
Device Parkin Elmer PHI5400 
X-ray source Mg K.alpha. 
Analysis area Diameter 1.1 mm 
Angle between detector and 
45.degree. 
sample surface 
Peak calibration 
Hydrocarbon C(1s) binding energy is set to 
284.7 eV 
Sputtering Not used (for observation of outermost 
surface) 
______________________________________ 
FIG. 1 is a graph showing the S (2P) binding energy distribution of a wire 
surface on which iron sulfide (FeS.sub.2, FeS) is generated. The binding 
energy distribution shown in FIG. 1 is measured by XPS under the 
conditions shown in Table 1 described above. This measurement is performed 
while sputtering the wire surface with argon ion, the graph of T(0) in 
FIG. 1 shows the measurement result of the wire before sputtering, and the 
graph of T(0.5) shows the measurement result of the wire surface after 
sputtering (Ar ion sputtering, sputtering speed 3 nm/min as on SiO.sub.2) 
for 0.5 minute with argon ion. T(1), T(2), T(3) similarly show the 
measurement results of the wire surface after sputtering for 1 minute, 2 
minutes and 3 minutes, respectively. 
As shown in FIG. 1, the peak of binding energy of FeS.sub.2 appears near 
162.8 eV, and the peak of binding energy of FeS appears near 161.6 eV. 
Since the iron sulfide (FeS.sub.2, FeS) is generated only on the wire 
surface, the peak height of FeS.sub.2 and FeS is decreased when the wire 
surface is rubbed by extending the sputtering time. Therefore, when the 
wire surface is analyzed by XPS without sputtering, the binding energy 
distribution of a material present on the wire surface can be provided 
from the energy spectrum of photo-electron, whereby the presence of iron 
sulfide (FeS.sub.2, FeS) can be confirmed. The presence of iron sulfide 
can be confirmed by the peak of binding energy of Fe (2P), in stead of the 
peak binding energy of S (2P). 
The quantity of S on the wire surface can be analyzed by use of XPS 
similarly to the presence of the iron sulfide (FeS.sub.2, FeS) on the wire 
surface. Since other C sources such as acetone for degreasing are left on 
the wire surface, the area of peak of S (2P) per total area of all peaks 
excluding carbon (C) is calculated, whereby the atomic % of S present on 
the wire surface can be determined. When another sulfides, for example NiS 
or MnS, are present on the surface of degrease wire, the peak of binding 
energy of NiS appears 162.2 eV. In case of MnS, the peak of binding energy 
appears near 162.5 eV. For reference, the peak of binding energy of S, not 
sulfides, appears 164.0 eV. 
Preferred Embodiments of the Invention 
Preferred embodiments of welding wires according to this invention are 
further specifically illustrated in comparison with reference examples. 
First Example 
Carbon steel fluxes of F1-F4 having compositions shown in Table 3 were 
filled in metal hoops of H1-H4 having compositions shown in Table 2 in 
various combinations to form raw materials, which were then drawn, whereby 
carbon steel flux-contained wires having wire diameters of 0.8-1.6 mm were 
manufactured. As shown in Table 3, the fluxes were filled within the hoops 
so that the weight of flux per total weight of wire is 8, 10, 12, 14, 16, 
and 18 wt. %, respectively, by increasing and decreasing the wt. % of Mn 
and Fe powders. 
TABLE 2 
______________________________________ 
Chemical Composition of Hoop (wt %) 
Hoop C Si Mn P S 
______________________________________ 
H1 0.08 0.08 0.2 0.015 
0.020 
H2 0.08 0.7 
0.005 
H3 0.06 0.4 
0.015 
H4 0.01 0.04 
1.5 
0.005 
______________________________________ 
TABLE 3 
______________________________________ 
Chemical Composition of Carbon Steel Flux (wt %) 
Other metal Other 
Flux Code 
Fe Oxide 
compound 
______________________________________ 
F1 35 10 3 45 7 
F2 45 2 
F3 55 2 
F4 75 2 
______________________________________ 
Raw materials of B1-B8 having compositions shown in Table 4 were drawn, 
whereby carbon steel solid wires having wire diameters of 0.8-4.8 mm were 
manufactured. 
TABLE 4 
______________________________________ 
Chemical Composition of Carbon Steel Solid Wire (wt %) 
Raw mat. 
C Si Mn P S Cr Mo Ti 
______________________________________ 
B1 0.04 0.8 1.2 0.010 
0.02 0.03 -- 0.2 
B2 0.04 0.8 1.3 0.009 
0.005 
-- -- 0.19 
B3 0.08 1.2 1.0 0.015 
0.015 
0.03 -- 0.13 
B4 0.07 1.1 1.2 0.016 
0.003 
0.03 -- 0.12 
B5 0.09 0.8 1.6 0.012 
0.015 
0.03 -- -- 
B6 0.09 0.8 1.6 0.010 
0.005 
0.02 -- -- 
B7 0.08 1.3 1.5 0.015 
0.03 0.5 0.8 0.05 
B8 0.09 1.0 1.2 0.011 
0.006 
0.6 0.4 0.03 
______________________________________ 
Further, stainless steel fluxes of F5-F6 having compositions shown in Table 
6 were filled in hoops of H5-H6 having compositions shown in Table 5 in 
various combinations to form raw materials, which were then drawn, whereby 
stainless steel flux-contained wires having wire diameters of 0.8-1.6 mm 
were manufactured. The fluxes were filled into the hoops so that the flux 
weight per total weight of wire is 15-25 wt. %. 
TABLE 5 
______________________________________ 
Chemical Composition of Hoop (wt %) 
Hoop C Si Mn P S Ni Cr 
______________________________________ 
H5 0.02 0.4 1.2 0.015 0.015 8.1 19.2 
H6 0.03 0.4 1.3 0.019 0.003 9.5 20.1 
______________________________________ 
TABLE 6 
______________________________________ 
Chemical Composition of Stainless Steel Flux (wt %) 
Other metal 
Flux Fe Ni Cr powder Oxide Other compound 
______________________________________ 
F5 39 3 20 9 25 4 
F6 32 6 21 7 28 6 
______________________________________ 
Raw materials of B9-B17 having compositions shown in Table 7 were also 
drawn, whereby stainless steel solid wires having wire diameters of 
0.8-1.6 mm were manufactured. 
TABLE 7 
______________________________________ 
Chemical Composition of Stainless Steel Solid Wire (wt %) 
Raw mat. 
C Si Mn P S Ni Cr Mo Nb 
______________________________________ 
B9 0.04 0.4 2.0 0.015 
0.010 
9.5 20.0 -- -- 
B10 0.04 0.4 1.9 0.015 
0.002 
9.2 21.0 -- -- 
B11 0.02 0.5 1.9 0.020 
0.015 
9.1 19.5 -- -- 
B12 0.04 0.5 1.8 0.020 
0.015 
12.5 23.0 -- -- 
B13 0.05 0.5 2.1 0.021 
0.002 
12.8 23.2 -- -- 
B14 0.02 0.3 2.3 0.025 
0.011 
12.4 19.5 3.0 -- 
B15 0.02 0.4 2.2 0.020 
0.003 
12.7 19.8 2.5 -- 
B16 0.04 0.4 1.9 0.019 
0.015 
10.0 20.1 -- 0.7 
B17 0.04 0.4 2.0 0.023 
0.002 
9.5 19.1 -- 0.6 
______________________________________ 
Of the resulting carbon steel flux-contained wires, carbon steel solid 
wires, stainless steel flux-contained wires, and stainless steel solid 
wires, a plurality of wires were selectively dipped in an aqueous solution 
of a sulfide of alkali metal (NaS, KS or the like) or ammonium sulfide to 
generate iron sulfide (FeS.sub.2, FeS) on the wire surfaces. Animal and 
plant oil, synthetic oil, or a mixture thereof was applied to all the 
wires as wire feeding oil in an amount of 0.5-2 g per 10 kg of the wire. 
The wires of Example having the iron sulfide (FeS.sub.2, FeS) generated on 
the surfaces and wires of Comparative Example having no treatment after 
drawing were manufactured. The quantity of S in iron sulfide (FeS.sub.2, 
FeS) on the wire surface can be regulated by changing the dipping time of 
the wire to the above aqueous solution. 
Under the conditions shown in Table 1, all the wire surfaces of the Example 
and Comparative Example were analyzed by X-ray photoelectron spectroscopy. 
Consequently, the same peak as T(0) in FIG. 1 could be confirmed with 
respect to all the wires of Examples. Namely, iron sulfides (FeS.sub.2, 
FeS) were generated on all the wire surfaces of Examples. 
Thereafter, the end surfaces of the wires of the same kind were joined by 
resistance welding, and the effect on wire resistance weldability of the 
quantity of S in hoop or in wire were examined. The wire resistance 
weldability was evaluated by examining the wet angle, the wettability and 
conformability of weld metal in weld part, the weld part rupture frequency 
in drawing, the fluctuation of arc length in weld part in arc welding by 
use of this wire. 
The wire feedability or the quantity of oil deposit from wire surface in 
spring liner was evaluated by measuring the mass change of the spring 
liner before and after continuous welding. 
FIG. 2 is a view showing a weld part when end surfaces of the wires of the 
Example were mutually joined by resistance welding, and FIG. 3 is a view 
showing a weld part when end surfaces of the wires of the Comparative 
Example were joined by resistance welding. As shown in FIGS. 2 and 3, the 
wettability between weld metal and wire surface can be evaluated by 
measuring the wet angle .theta.. The wet angle .theta. means the angle 
formed by the tangent 2 of the weld metal surface passing the contact 1 
between the weld metal surface and the wire surface and the wire surface 
3, and a smaller wet angle .theta. shows higher wettability of the wire 
surface and more satisfactory conformability. 
The manufacturing condition of the wires and the method of generating iron 
sulfides (FeS.sub.2, and FeS) are shown in Table 8, and the quantity of S 
in wire or in hoop, the presence of iron sulfide (FeS.sub.2, FeS) on the 
wire surface, and the quantity of S on the wire surface are shown in Table 
9, and the evaluation results of wire resistance weldability and wire 
feedability are shown in Tables 10, 11. 
TABLE 8 
______________________________________ 
Used 
hoop/ 
used flux 
Flux 
or used 
ratio 
diam. 
Method/time of generating 
No. raw mat. 
(%) 
iron sulfide (FeS.sub.2, 
______________________________________ 
FeS) 
Ex. 1 H2/F4 16 1.2 Dipped in NaS aq soln/1 sec 
2 
Dipped in NaS aq soln/2 sec 
3 
-- 
Dipped in KS aq soln/15 sec 
4 
-- 
Dipped in KS aq soln/30 sec 
5 
Dipped in NaS aq soln/1 sec 
6 
-- 
Dipped in KS aq soln/15 sec 
7 
-- 
Dipped in NaS aq soln/30 sec 
8 
-- 
Dipped in KS aq soln/30 sec 
Comp. 9 
Dipped in KS aq soln/30 sec 
Ex. Annealed at 700.degree. C. for 
60 min 
10 
-- 
11 
-- 
-- 
12 
-- 
-- 
13 
-- 
14 
-- 
-- 
15 
-- 
______________________________________ 
-- 
TABLE 9 
______________________________________ 
Quantity of S 
Iron sulfide 
Quantity of S 
in wire or in hoop 
(FeS.sub.2, FeS) 
on wire surface 
No. on wire surface 
(atomic %) 
______________________________________ 
Ex. 1 0.005 Present 0.15 
2 0.28 
3 5.1 
4 18.9 
5 0.5 
6 5.7 
7 8.2 
8 11.5 
Comp. 9 0.2 
Ex. 10 tr. 
11 tr. 
12 tr. 
13 tr. 
14 tr. 
15 tr. 
______________________________________ 
tr: trace element 
TABLE 10 
______________________________________ 
Evaluation result of wire resistance weldability 
Weld part Fluctuation of 
Wet Wettability 
rupture frequency 
arc length in 
angle and 
in drawing 
weld part in 
(.degree.) conformability 
(Frequency/10 t) 
arc welding 
______________________________________ 
Ex. 1 11 .smallcircle. 
0 Nil 
2 
15 
.smallcircle. 
Nil 
3 
9 
.smallcircle. 
Nil 
4 
5 
.smallcircle. 
Nil 
5 
12 
.smallcircle. 
Nil 
6 
8 
.smallcircle. 
Nil 
7 
7 
.smallcircle. 
Nil 
8 
13 
.smallcircle. 
Nil 
Comp. 9 
62 
Present 
Ex. 10 
55 
Present 
11 
49 
Present 
12 
71 
Present 
13 
61 
Present 
14 
53 
Present 
15 
46 
Present 
______________________________________ 
TABLE 11 
______________________________________ 
Evaluation of Oil Deposit 
(wire speed 12/min, 24-hr continuous feed test) 
Quantity of Oil Deposit 
(g/10 kg wire) 
Feeding Failure 
______________________________________ 
Ex. 1 0.05 non stop (continuous feeding) 
2 
non stop (continuous feeding) 
3 
non stop (continuous feeding) 
4 
non stop (continuous feeding) 
5 
non stop (continuous feeding) 
6 
non stop (continuous feeding) 
7 
non stop (continuous feeding) 
8 
non stop (continuous feeding) 
Comp. 9 
After 19 hr 
Ex. 10 
After 15 hr 
11 
After 22 hr 
12 
After 20 hr 
13 
After 13 hr 
14 
After 18 hr 
15 
After 16 
______________________________________ 
hr 
As shown in Tables 8-10 and FIGS. 2 and 3, in Examples No. 1-8 having iron 
sulfide (FeS.sub.2, FeS) present on wire surfaces, the wet angle .theta. 
is minimized, compared with the Comparative Example, regardless of the 
quantity of S in wire or in hoop to enhance the wettability and 
conformability in resistance welding, and the weld part is never fractured 
in drawing. In table 10, ".largecircle." mark means good wettability and 
good conformability. The shape of weld metal of any one of Examples No. 
1-8 is concave. Further, the arc length was never fluctuated in the weld 
part in arc welding by use of these wires. Fluctuation of arc length was 
studied by H. S. V. (High Speed Video, 2000 frames/sec). In table 10, 
"Nil" means that arc length fluctuation is within 5 times wire dia. 
On the other hand, in Comparative Examples No. 9-15 having no iron sulfide 
(FeS.sub.2, FeS) present on wire surfaces, the wettability and 
conformability of weld metal were defective to require a long-time filing 
after welding, and the weld part was ruptured in drawing. The wire surface 
with which the weld metal makes contact was also notched because of the 
large wet angle .theta., and the stress became easily collected in this 
part. Thus, the tendency for the wire to fracture in the notched part 
increased. In table 10, "x" mark means poor wettability and poor 
conformability. The shape of weld metal of any one of Examples No.9-15 is 
convex. Further, the arc length was fluctuated in the weld part in arc 
welding. In table 10, "Present" means that arc length fluctuation is more 
than 5 times wire dia. The wire resistance weldability was determined 
depending on the presence of iron sulfide (FeS.sub.2, FeS) on the wire 
surface regardless of the amount of S in wire or in hoop. 
As shown in Table 11, Examples No. 1-8 having iron sulfide (FeS.sub.2, FeS) 
present on wire surfaces have no trouble in feeding even in 24-hr 
continuous feed test, and the oil deposit in spring liner is little as 0.1 
g/10 kg wire. 
On the other hand, in Comparative Examples No. 9-15 having no iron sulfide 
(FeS.sub.2, FeS) present on wire surfaces, a feeding failure is caused in 
continuous feeding, and the oil deposit in spring liner is extremely large 
as about 1 g/10 kg wire. The analysis of the deposit component in spring 
liner showed that the most part was formed of the wire feeding oil. The 
wire feedability was determined depending on the presence of iron sulfide 
(FeS.sub.2, FeS) on wire surface regardless of the quantity of S in wire 
or in hoop. 
Second Example 
Various welding wires were manufactured by use of hoops, fluxes, or raw 
materials shown in Tables 2-7, and these were dipped in an aqueous 
solution of a sulfide of alkali metal (NaS, KS or the like) to generate 
the sulfide on the wire surface. To all the wires, animal and plant oil, 
synthetic oil or a mixture thereof was applied as wire feeding oil in an 
amount of 0.5-2 g per 10 kg of wire. In the same manner as in the first 
example, effects on wire resistance weldability and wire feedability of 
the quantity of S in hoop or in wire were examined. The manufacturing 
condition of wire and generating method of sulfide were shown in Table 12, 
the quantity of S in wire or in hoop, presence of sulfide on wire surface, 
and the quantity of S on wire surface are shown in Table 13, and the 
evaluation results of wire resistance weldability and wire feedability are 
shown in Tables 14 and 15. 
TABLE 12 
______________________________________ 
Used 
hoop/ 
used flux 
Flux 
or used 
ratio 
diam. 
Method/time of generating 
No. raw mat. 
(%) 
iron 
______________________________________ 
sulfide 
Ex. 16 H4/F3 13 1.2 Dipped in NaS Aq soln/1 sec 
17 
-- 
Dipped in NaS aq soln/20 sec 
18 
-- 
Dipped in KS aq soln/l5 sec 
19 
Dipped in KS aq soln/3 sec 
20 
-- 
Dipped in NaS aq soln/20 sec 
21 
-- 
Dipped in KS aq soln/30 
______________________________________ 
sec 
TABLE 13 
______________________________________ 
Quantity of S 
Kind of Quantity of S 
in wire or in hoop 
sulfide 
on wire surface 
No. on wire surface 
(atomic %) 
______________________________________ 
Ex. 16 0.005 MnS, FeS 0.19 
17 
MnS, FeS 
0.5 
18 
TiS, FeS 
3.7 
19 
NiS, CrS 
0.3 
20 
NiS, CrS 
11.4 
21 
NiS, CrS, 
17.9 
MnS, MoS 
______________________________________ 
TABLE 14 
______________________________________ 
Evaluation Result of Wire Resistance Weldability 
Weld part Fluctuation of 
Wet Wettability 
rupture frequency 
arc length in 
angle and 
of in drawing 
weld part in 
(.degree.) conformability 
(frequency/10 t) 
arc welding 
______________________________________ 
Ex. 16 13 .smallcircle. 
0 Nil 
17 
10 
.smallcircle. 
Nil 
18 
7 
.smallcircle. 
Nil 
19 
12 
.smallcircle. 
Nil 
20 
11 
.smallcircle. 
Nil 
21 
8 
.smallcircle. 
______________________________________ 
Nil 
TABLE 15 
______________________________________ 
Evaluation of Oil Deposit 
(wire speed 12 m/min, 24-hr continuous feed test) 
Quantity of Oil Deposit 
(g/10 kg wire) 
Feeding Failure 
______________________________________ 
Ex. 16 0.03 non stop (continuous feeding) 
17 
non stop (continuous feeding) 
18 
non stop (continuous feeding) 
19 
non stop (continuous feeding) 
20 
non stop (continuous feeding) 
21 
non stop (continuous 
______________________________________ 
feeding) 
As shown in Tables 12 and 13, in Examples No. 16-21 having sulfides present 
on wire surfaces, the wet angle .theta. is minimized regardless of the 
quantity of S in wire or in hoop to enhance the wettability in resistance 
welding, and the weld part is never fractured in drawing. The arc length 
was never fluctuated in the weld part even when arc welding was performed 
by use of these wires. 
As shown in Table 15, Examples Nos. 16-21 having sulfides present on wire 
surfaces have no trouble in feeding even in 24-hr continuous feed test 
regardless of the quantity of S in wire or in hoop, and the oil deposit in 
spring liner is little as less than 0.1 g.