JPH046477B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a composite wire for arc welding. [Prior Art] Composite wires for arc welding have rapidly become popular in recent years, mainly consisting of small diameter wires with a simple cross-section used for CO ₂ welding. The reason for this is that a relatively large current is passed through the small diameter wire, resulting in high welding efficiency and a large cost reduction effect.Also, since the main component of the filling flux is rutile, it has excellent arc characteristics and slag physical properties, resulting in a stable arc. is held,
The reason is that good welding can be easily performed. Particularly in the shipbuilding industry, where vertical and upward welding are often employed, the technology developed by the present inventors (Japanese Patent Laid-Open Publication No.
57-72795), CO ₂ welding using a composite wire can be easily performed from downward welding, to vertical welding, vertical downward welding, and upward position using the same current, so it is now the main welding method. Widely adopted. [Problems to be solved by the invention] Emphasizing all-position weldability in such applications,
When trying to raise the melting point of molten slag in order to obtain a beautiful weld bead, the filling flux inevitably has a high blending ratio of high melting point oxides such as TiO ₂ , ZrO ₂ , Al ₂ O ₃ , and MgO. I have no choice but to do so. However, in the case of small-diameter composite wires with simple wire cross-sections as shown in Figures 6a and 6b, when the blending ratio of high-melting point oxide is increased, the high-melting point flux filled in the wire melts more slowly than the outer skin, and the wire remains unused. During welding, the molten material protrudes into the arc column and irregularly transfers to the molten pool.
This is the cause of frequent spats. This phenomenon is particularly noticeable in composite wires to which arc stabilizers such as Na and K are added in combination for the purpose of improving the arc condition during all-position welding. this is
Adding arc stabilizers such as NaK and Li increases the arc length, so it is thought that only the outer metal melts and the filling flux remains unmelted in the arc column, causing more spatter. . In order to solve this problem, the present inventors have carried out various studies in order to achieve good welding with less spatter in composite wires that are filled with high-melting point flux and produce beautiful weld beads.
As a result, they obtained the knowledge that by using flaky iron powder, the arc condition could be fundamentally improved, the protrusion of unmelted flux could be prevented, and the occurrence of spatter could be reduced, and a patent application was filed.
(Special Application No. 61-6698). However, subsequent research revealed that in order to fundamentally improve the arc condition, not only the shape effect of the iron powder but also the use of iron powder with a low iron oxide content prevented the protrusion of unmolten flux and reduced the occurrence of spatter. I learned that it can be done. It has also been confirmed that by using iron powder with a low C content, wire breakage during drawing of a composite wire can be eliminated, and the present invention has been achieved. The present invention provides a composite wire for arc welding that eliminates the protrusion of unmelted flux when using the conventional composite wire for arc welding, significantly reduces the occurrence of spatter, and eliminates wire breakage during wire drawing. With the goal. [Means for Solving the Problems] The composite wire for arc welding according to the present invention is made of rutile containing 10% to 35% by weight of iron powder containing 2.0% by weight or less of iron oxide and 0.050% by weight or less of C. The metal shell is characterized by filling the metal shell with a flux based on the above-mentioned components, and further containing 5% to 35% by weight of iron powder having the above components and the shape defined by the following formula (1). It is characterized by the fact that 3≦W ₁ /t≦200 ... (1) where W ₁ : Maximum width diameter of iron powder t : Maximum thickness of iron powder [Function] The following is the reason why the composite wire for arc welding of the present invention has the above configuration. Each will be explained in detail. (Hereinafter, % by weight will be simply expressed as %.) First, the reason why the content of iron oxide in iron powder was specified to be 2.0% or less will be explained. The present inventors found that the iron oxide content was 0.5, 1.0, 1.5, 2.0, 2.5, 3.0,
3.5, 4.0, 4.5, 5.0%, and C content is 0.015%
The iron powder is TiO ₂ : 35%, SiO ₂ : 2%,
_ZrO2 : 5%, MgO: 3%, NaF: 0.5%,
_K2TiO3 : 1%, Fe-Si: 7%, _Fe -Mn: 15%,
Fe-Al: 3% of total flux weight
28.5% of the flux was added, and this flux was filled in at 16% of the total weight of the wire to form a wire with a simple cross-sectional shape as shown in Figure 6a.
We prototyped a composite wire with a diameter of 1.6 mm. Note that 1 is a metal shell and 2 is a flux. Using this prototype wire, a V-groove groove was vertically welded at 250 A and 26 V, and the protruding length of unmelted flux and the amount of spatter were measured. Here, the protrusion length of the unmelted flux was determined by photographing with a high-speed camera, and the entire amount of spatter was collected by surrounding it with a copper container and welding, and the amount of spatter generated per minute was evaluated. According to Figure 1 showing the measurement results, the protrusion length of the unmelted flux is more than twice the wire diameter (d) when the iron oxide content in the iron powder is 3.0% or more, but when the iron oxide content is 2.5% decreases to about the wire diameter (d), and further
It is understood that below 2.0%, the wire diameter (d) decreases to 1/2. In addition, the amount of spatter generated is 3.0% due to iron oxide.
In the above cases, it occurs very frequently at around 4.5g per minute,
At 2.5% it decreases by about 50%, and at 2.0% or less it decreases by 70%
This has also decreased. In other words, if the iron oxide content in the iron powder is 2.5% or more, it is difficult to conduct electricity due to the oxide film on the surface of the iron powder, which creates an insulating effect between the filling flux and the sheath metal, and allows power to be supplied from the outside of the sheath metal by the welding tip. The generated current mainly flows only through the outer metal. As a result, the shell metal melts before the filling flux, the unmelted flux protrudes longer, and the amount of spatter increases. Finally, when the iron oxide content is less than 2.0%, the conductivity of the iron powder improves, and when a current passes through the flux, the arc that previously occurred only from the outer metal can now also be generated from inside the cross section of the wire.
As a result of promoting melting of the filling flux, unmelted flux is prevented from protruding into the arc column, and spatter is reduced. Therefore, in the wire of the present invention, iron powder having an iron oxide content of 2.0% or less is preferable. Next, the reason why the C content in the flake iron powder was specified to be 0.050% or less will be explained. The present inventors found that the C content was 0.010%, 0.020, 0.030, 0.040, 0.050,
Using iron powder of 0.060, 0.070, 0.080, 0.090, 0.100% and 1.5% iron oxide content, the same flux mixture ratio as above, 16% of the total wire weight.
Filled with a simple cross-sectional shape of 1.6mmφ as shown in Figure 6a.
We prototyped a composite wire and investigated the number of wire breaks during drawing of this composite wire. The survey results are shown in Figure 2. The wire breakage investigation was carried out by drawing a 1 ton composite wire at a wire drawing speed of 500 m/min from a wire diameter of 3.2 mmφ to 1.6 mmφ with an area reduction rate of approximately 20% per die. According to Figure 2 showing the survey results, the C content is
No disconnection occurred at 0.05% or less, but at 0.06%
When the value exceeded 100%, wire breakage occurred almost linearly. The reason for this is thought to be that as the C content increases, the iron powder dispersed in the filling flux becomes difficult to deform, and only the outer sheath of the wire is rolled and broken.
Therefore, in the wire of the present invention, iron powder with a C content of 0.050% or less is preferable. Next, the reason why such iron powder is specified to be contained from 10% to 35% will be explained. In other words, iron powder with an iron oxide content of 1.0% and a C content of 0.030% was mixed with TiO ₂ : 28%, SiO ₂ : 2%, Al ₂ O ₃ : 4%,
_ZrO2 : 3%, NaF: 1%, Fe-Si: 7%, Fe-
Mn: 15%, iron oxide content 4.0%, C content
5, 10, to flux consisting of 40% of 0.050% iron powder.
Substituting the mixture up to 20, 30, and 40%, filling the mild steel sheath with a simple cross section as shown in Figure 6a at 15% of the total weight of the wire.
A composite wire of 1.6 mmφ was prototyped and a wire evaluation test similar to that shown in Fig. 1 was conducted. According to Figure 3, which shows the measurement results, the protrusion length of the unmelted flux is still 1.4 times the wire diameter (d) when the amount of iron powder added to the flux is 5%, but when the amount of iron powder added is 10%. It is understood that the wire diameter is reduced to approximately 1/2 of the wire diameter. This tendency does not change even if iron powder is added up to 40%. The amount of spatter was reduced by about 50% when 5% iron powder was added, which made the protrusion of unmolten flux 1.4 times the wire diameter (d), and by about 75% when 10% was added. Therefore, in the wire of the present invention, the iron oxide content is
2.0% or less, 10% iron powder with C content of 0.050% or less
to 35% flux. The upper limit of the amount added is 35% or less in order to maintain the characteristics of the rutile flux. Next, in the second invention, the shape of the iron powder is as follows (1)
The reason for specifying the formula and specifying that the iron powder be contained from 5% to 35% will be explained. 3≦W ₁ /t≦200 (1) where W ₁ : Maximum width diameter of iron powder t : Maximum thickness of iron powder The reason for adding iron powder that satisfies formula (1) in the present invention is that iron oxidation C content is less than 2.0%, C content is less than 2.0%.
This is because, compared to spherical or irregularly shaped iron powder of 0.050% or less, a small amount has an extremely large effect in reducing the protrusion of unmelted flux, and also has a large effect in reducing spatter. That is, the above-mentioned iron oxide content is 1.0
%, iron powder with a C content of 0.030%, the maximum width diameter
It was pressed into flakes so that the ratio of W ₁ to the maximum thickness t was 5 to 8. This iron powder was substituted to the above-mentioned flux mixture ratio to 5, 10, 20, 30, and 40%, and the simple cross-section mild steel sheath shown in Figure 6a was filled with 15% of the total weight of the wire. A prototype wire was manufactured and a wire evaluation test similar to that shown in FIGS. 1 and 3 was conducted. The test results are shown in FIG. As shown in Fig. 7, the maximum width diameter _W1 of the flaked iron powder 3 means the maximum value in the direction perpendicular to the maximum major axis _W2 , and the maximum thickness t means the maximum width diameter W1 of the flaked iron powder 3. The maximum value in the direction perpendicular to the plane or curved surface formed by the major axis W ₂ and the maximum width W ₁ . Figure 4 shows that the protrusion length of unmelted flux decreases to less than the wire diameter (d) when the amount of flaky iron powder added to the flux is 5%, and when the amount of flaky iron powder added to the flux is 10%, it is 1 of the wire diameter (d). It decreased to /2. It is also understood that the amount of spatter generated is reduced by approximately 70% at 5% and 80% at 10%. In other words, from Figures 3 and 4, in order to reduce the protrusion length of unmelted flux to less than the wire diameter (d) with iron powder before processing, it is necessary to replace 10% of the iron powder, while flake-like It is understood that this can be achieved with 5% substitution in iron powder processed to This difference in effect is thought to be because the iron powder processed into flakes has a larger specific surface area, and even if the amount added is small, there are more opportunities for the iron powder to come into contact with each other, making it easier to conduct electricity. However, the maximum width diameter of iron powder
It will be understood from the following test that when the ratio W ₁ /t of W ₁ to the maximum thickness t is less than 3, the above-mentioned effect is not present. That is, the iron oxide content is 1.0% and the C content is
By varying the ratio between the maximum width diameter W ₁ and the maximum thickness t of the iron powder, which is 0.030%, these iron powders were TiO ₂ :28
%, SiO ₂ : 2%, Al ₂ O ₃ : 3%, MgO: 3%,
_K2TiO3 : 1%, _MgF2 : 1%, _Fe -Si: 7%,
5 to a flux consisting of 40% iron powder with Fe-Mn: 15%, iron oxide content of 4.0%, and C content of 0.050%.
A composite wire with a diameter of 1.6 mm was prototyped by filling a mild steel outer shell with a simple cross section as shown in Fig. 6a at 15% of the total weight of the wire. Using this prototype wire, the first
A wire evaluation test similar to that shown in Figures 3 and 4 was conducted. FIG. 5, which shows the measurement results, shows that when the ratio W ₁ /t of the maximum width diameter W ₁ to the maximum thickness t is less than 3, there is little effect in reducing the protrusion of unmelted flux and spatter. It can be seen that when W ₁ /t is 3 or more, the shape effect of the iron powder appears, the protrusion of the unmelted flux becomes less than the wire diameter (d), and spatter is reduced. Therefore, flaky iron powder having an iron oxide content of 2.0% or less, a C content of 0.050% or less, and a W ₁ /t of 3 or more is contained in the flux from 5% to 35%. The upper limit of the amount of flaky iron powder added is determined in order to maintain the characteristics of rutile flux.
It shall be 35%. Further, the maximum width diameter W ₁ is desirably 1 mm or less in consideration of flux filling properties. Maximum width diameter
If W ₁ exceeds 1 mm, other flux raw materials added at the same time are often fine powders, so the particle size structure of the flux will be greatly different, and there is a risk of component segregation. Therefore, it is desirable that the maximum width diameter W ₁ of the flaky iron powder is 1 mm or less. Furthermore, regarding the upper limit of the ratio W ₁ /t between the maximum width diameter W ₁ and the maximum thickness t, the larger W ₁ /t is, the more the specific surface area of iron powder increases with the same addition amount. There are many opportunities for contact, and the current conduction to the filling flux improves, and the arc improvement effect is exerted. However, when W ₁ /t exceeds 200, the bulk density becomes extremely small, and segregation with other filling fluxes occurs. W ₁ /t is set to 200 or less. The flaky iron powder 3 having such an effect can be produced by pressing ordinary spherical or irregularly shaped iron powder to flatten it, by peeling or scratching a metal block to cut it, or by cutting metal foil. Manufactured by methods such as In the present invention, the addition of flux containing iron powder to the metal sheath is preferably 50% or less of the total weight of the wire. If more than 50% of flux is added, the ratio of flux to the cross-sectional area of the wire becomes too large, resulting in frequent wire breakages during wire drawing, which significantly impairs productivity. Therefore, the flux filling rate should be 50% or less. desirable. Further, the cross-sectional shape of the composite wire of the present invention is not particularly limited, and the present invention can be applied to a composite wire having a simple cross-section without seams as shown in FIGS. 6b to 6e, or a complex cross-section having internal folds. [Example] The effects of the present invention will be explained in more detail with reference to Examples. Table 1 shows the configuration of a composite wire prototyped with a diameter of 1.2 mm in the shape shown in Figure 6a using a mild steel outer sheath.
Table 2 shows the test results. The wire was evaluated by performing automatic horizontal fillet welding under the welding conditions shown below.
The protruding length of unmelted flux and the amount of spatter generated were measured. We also investigated whether or not there was any disconnection during wire trial production. Welding conditions Welding current: 270A DC (+) Arc voltage: 30V Welding speed: 35cm/min Shielding gas: CO ₂ , 20 / Base material: T-shaped fillet (Inorganic zinc primer coated steel plate: 20μ coating) Chip - Base material Distance = 25mm

【table】

[Table] *marks are comparative examples

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to significantly reduce the protrusion of unmelted flux during welding, thereby significantly reducing the amount of spatter generated, improving welding efficiency and welding quality. improves.

[Brief explanation of drawings]

Figure 1 shows the relationship between the iron oxide content in iron powder, the protrusion length of unmelted flux, and the amount of spatter, and Figure 2 shows the relationship between the C content in iron powder and wire breakage during wire drawing. Figure 3 is a diagram showing the relationship between the number of times the flux is added, and Figure 4 is a diagram showing the relationship between the amount of iron powder added to the flux, the protrusion length of unmelted flux, and the amount of spatter.
The figure shows the relationship between the amount of flaky iron powder added in flux, the protrusion length of unmelted flux, and the amount of spatter. Figure 5 shows the relationship between the shape of iron powder, the protrusion length of unmelted flux, and the amount of spatter. 6A to 6E are cross-sectional views of composite wires in various embodiments, and FIG. 7 is a schematic view showing the shape of flaky iron powder. 1...Metal shell, 2...Flux, 3...Flake-like iron powder.

Claims (1)

[Claims] 1 Iron oxide is 2.0% by weight or less, C is 0.05% by weight
A composite wire for arc welding characterized by having a metal sheath filled with rutile flux containing 10% to 35% by weight of the following iron powder. 2 Iron oxide is 2.0% by weight or less, C is 0.05% by weight
A composite wire for arc welding, characterized in that a metal sheath is filled with a rutile-based flux containing 5% to 35% by weight of iron powder having a shape defined by the following formula (1). 3≦W ₁ /t≦200 ...(1) Here, W ₁ : Maximum width diameter of iron powder t: Maximum thickness of iron powder