JP3488357B2 - Non-low hydrogen coated arc welding rod - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding material used for light steel frames, automobile parts, segments, mild steel thin plates such as drums, and intermediate plates, and more specifically 400 to 570 N / m.
The present invention relates to a non-low-hydrogen coated arc welding rod (hereinafter referred to as "non-low-hydrogen rod"), which is intended for m ² steel and has significantly improved rod burning resistance when used at high current.

[0002]

2. Description of the Related Art Non-low hydrogen type rods have good welding workability and bead shape as compared with low hydrogen type coated arc welding rods.
It is well known that the welding rod is applied to a wide variety of steel materials and has a wide range of versatility.

However, non-low hydrogen type rods are generally used under severe welding conditions, and are currently used at a high current for the purpose of improving work efficiency. In this welding process, the arc force becomes excessively strong and deep penetration into the work piece can be obtained, but on the other hand, the steel core wire generates heat in the latter half of the welding rod and the organic matter in the coating material decomposes and burns due to Joule heat. The so-called stick burning phenomenon, which becomes a red hot state, easily occurs. If welding is continued in this burned state, the coating cylinder is not formed due to the deterioration of the coating material, the directivity of the arc deteriorates, and the arc state suddenly changes to become unstable and the arc force decreases. Further, there is a problem that pits and blow holes are generated in the weld metal due to the decomposition of the deoxidizer and the gas generating agent.

Therefore, there is a strong demand for improvement of the stick burning phenomenon in non-low hydrogen type sticks. For example, in JP-A-57-206595, in JP-A-57-206595, SiO ₂ / Na ₂ O in water glass as a fixing agent is used. The molar ratio is 2.8-3.
The use of the high molar ratio water glass of No. 8 prevents stick burning. However, as described in JP-A-57-100896, increasing the molar ratio of water glass causes dry cracks during production, and when the molar ratio increases, Na ₂ O or K ₂ O increases. Since the amount of alkali oxides such as is reduced, the arc state is deteriorated, and there is a problem that spattering is increased.

Further, as described in JP-B-63-7878, sepiolite is added in an amount of 0.5 to 0.5 in the coating material.
5.0 wt%, containing 0.5 to 8.5 wt% organic matter,
Moreover, the ratio of sepiolite to the amount of organic matter is 0.3 to
By setting the ratio to 3.5, the sticking property in the coating material is enhanced, the productivity is improved, and the flexibility of the coating material as well as the stick burn resistance in the use of high current is improved. However, there is a problem that the re-arcing property is slightly deteriorated.

As described above, it is very difficult for the current non-low hydrogen type rod to have excellent rod burning resistance and to satisfy the welding workability such as re-arcing property, arc condition, spatter condition, slag condition and bead appearance. Therefore, obtaining a welding rod satisfying these requirements has been strongly demanded by each industry that uses the welding rod.

[0007]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention examines the components in the steel core wire and the composition of the coating material to ensure the conventional performances and to deteriorate the re-arcing property. It is an object of the present invention to provide a non-low hydrogen system rod which can make stable welding up to the latter half of the welding rod even by using a high current by making the rod burning resistance extremely good.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a means for improving rod burn resistance while satisfying various performances, having good welding workability, and not degrading re-arcing property at high current use. I studied hard. That is, the present invention, as a result of various studies on the steel core wire and the coating material of the non-low hydrogen type rod in order to meet the above-mentioned demand, is one in which the bar burn resistance is remarkably improved and the gist thereof is, A steel core wire whose Mn is regulated to 0.15 to 0.28% by weight contains 1.0 to 8.0% by weight of one or more hydrous mineral pyrophyllite clays, and gas is generated. A non-low-hydrogen coated arc welding rod characterized by being coated with a coating agent consisting of an agent, an arc stabilizer, a slag generator, a deoxidizer, a fixing agent, and inevitable impurities. The non-low hydrogen according to claim 1, wherein the amount of released water of the light clay when heated at 400 ° C to 800 ° C is 0.05 to 0.55% by weight based on the total weight of the coating material. It is a system coated arc welding rod, and further C is 0.01 to 0.09. Is a non-low hydrogen type covered electrode as claimed in claim 1, wherein the an amount%.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. When the welding current exceeds the proper current of the welding rod, the cause of the burning of the rod is that the steel core wire generates heat due to its specific resistance in the latter half of the welding rod, and the organic substances in the coating material decompose and burn due to Joule heat. It is known to become red hot. If welding is continued in this burned state, the coating cylinder is not formed due to the deterioration of the coating material, the directivity of the arc deteriorates, and the arc state suddenly changes to become unstable and the arc force decreases. Furthermore, pits and blowholes are likely to occur in the weld metal due to the decomposition of the deoxidizer and the gas generating agent. Therefore, in order to improve the burn resistance of the rod, the heat generation of the core wire during welding is suppressed by controlling the components so that the specific resistance of the steel core wire becomes small.

In the non-low hydrogen type rod of the present invention, it is considered to reduce the contents of Mn and C in the steel core wire as a component for reducing the specific resistance of the steel core wire and improving the burn resistance of the steel core wire. However, as for C in the steel core wire, it reacts with O in the steel core wire and the coating agent to generate CO and CO ₂ gas, which brings about a shielding effect from the atmosphere, but these gases are contained in the droplets. There is also an effect that the droplets are crushed by the internal pressure and the droplets are made finer. When C is lowered, these reactions are reduced, the droplets are coarsened, the arc becomes unstable, and the spatter also increases. Therefore, addition of 0.01 to 0.09% by weight is preferable.

Mn in the steel core wire can suppress the heat generation of the steel core wire without deteriorating the welding workability and can improve the stick burn resistance, and is in the range of 0.15 to 0.28% by weight. Within that range, a good weld metal can be obtained, and the heat resistance of the steel core wire during welding is suppressed because the specific resistance of the steel core wire is appropriate. As a result, the mechanical performance deteriorates because a sound weld metal cannot be obtained. In addition, the arc becomes weak and pits and blowholes are easily generated due to insufficient deoxidation, so that X-ray performance is also deteriorated. On the other hand, if it exceeds 0.28% by weight, the specific resistance of the steel core wire increases and the melting rate becomes slow.
Therefore, the heat generated from the steel core wire becomes excessive and the stick burn resistance deteriorates. Further, the arc spray becomes too strong, and undercut easily occurs.

From the viewpoint of the coating material, by adding a hydrous mineral, the Joule heat generated from the steel core wire during welding is replaced with the heat of vaporization of H ₂ O in the hydrous mineral of the coating material, and It is extremely effective to accelerate the heat dissipation of the welding rod and prevent the temperature rise of the welding rod, but it deteriorates the re-arcing property. Therefore, as a result of investigating hydrous minerals that do not deteriorate the re-arcing property from various hydrous minerals, we focused on pyrophyllite clay. This water-containing mineral has structural water that is strongly bound to the structure of the mineral in the form of -OH group by ionic bond or covalent bond, which is dehydrated at 400 to 800 ° C and is a normal non-low hydrogen system. Under the manufacturing conditions of the rod, the structured water will remain in the coating agent without being dehydrated. Therefore, the of H ₂ O hydrous minerals coatings Joule heat generated from the steel core wire during welding has replaced the vaporization heat, to promote heat radiation from the welding rod, to prevent the temperature increase of the welding rod You can

Therefore, for example, when pyrophyllite clay is compared with sericite, which is the same hydrated aluminum silicate, the constituent minerals are different even though they are almost the same in composition, and sericite is more insulating. It contains a large amount of mica. Therefore, when sericite is used, the stick burn resistance is improved, but the occurrence of re-arcing after the interruption of welding is extremely deteriorated, so that the efficiency of welding is reduced. In addition, since pyrophyllite-based clay is mainly composed of pyrophyllite, compared with other clays such as kaolin-based clay and sericite-based clay containing other clay minerals, this also has a low mica content. This is because the electric conductivity of the coated cylinder is good and the occurrence of re-arc after the welding is interrupted is good.

The amount of water released from the hydrous mineral containing pyrophyllite clay as a main component in the present invention when heated to 400 ° C. or higher is set to 0.05 to 0.55% by 0.05. If it is less than%, there is little structural water in the hydrous mineral, so there is no effect in improving the stick burn resistance, while 0.5
If it exceeds 5%, the amount of water in the coating material becomes excessive, so that the arc is intensified and undercut easily occurs.

Further, the amount of the hydrous mineral containing pyrophyllite-based clay as the main component is set in the range of 1.0 to 8.0% by weight in the coating material. There is no effect on the improvement of burnability, while if it exceeds 8.0%, the insulating property of the coated cylinder increases, so that rearcing after welding is interrupted becomes difficult. In addition, deterioration of welding workability such as arc instability and increase in spatter poses a problem.

The lime carbonate used in the present invention is a gas generating agent, which decomposes in the arc and generates CO ₂ gas, so that the weld metal and molten slag are shielded from the atmosphere,
It prevents the entry of nitrogen and oxygen, secures the arc force, and adjusts the fluidity and viscosity of the slag. Rutile acts as a slag generator and a viscosity adjuster, enhances the encapsulation of slag, and is also effective as an arc stabilizer.

Quartz sand acts as a refractory agent and slag modifier. Fe-Mn also uses welding workability and the function of an alloying agent. Iron powder is added to improve electric conductivity, improve re-arcability, increase the amount of deposition, and improve welding work efficiency. The organic substance is added to carbonize the tip of the coated cylinder during welding and to help improve the re-arcing property together with the iron powder, and to moderate the arc spraying strength. The fixing agents are potassium silicate and sodium silicate, and these can be used alone or in combination of two kinds. Inevitable impurities include C, P, S,
Cl and the like.

[0018]

EXAMPLES Steel core wires having the chemical composition shown in Table 1 and Table 2
A coating agent was applied to the outer periphery of the core wire diameter of 4.0 mm using the coating material shown in Table 1 and the pyrophyllite-based clay shown in Table 3 to prepare a non-low hydrogen system rod, and a welding test was conducted. The test methods and their acceptance criteria were as follows.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

The investigation of the re-arcing property was carried out with a plate thickness of 12 mm and a width of 1
Downward welding on a mild steel plate with a length of 00 mm and a length of 450 mm with an AC welding machine at a current of 220 A and a no-load voltage of 65 V for 5 seconds.
The arc is extinguished and left for 30 minutes. afterwards,
The tip of the residual welding rod was lightly contacted with a mild steel plate to investigate the state of arc generation. The number of tests was 6. The criterion is
Five or more of the six re-arced ones were marked with a circle, and four or less were marked with a cross.

In the investigation of welding workability, a mild steel plate having a plate thickness of 12 mm, a width of 100 mm and a length of 450 mm was assembled into a T type, an AC welding machine was used, a horizontal fillet had a current of 180 A, and a vertical fillet of 140 A was used. The arc state, slag state, bead shape, etc. were investigated. The judgment was made as a comprehensive judgment of each welding posture. Good marks were marked with a circle, and some of them were marked with a cross.

In the stick burn resistance test, a plate thickness of 12 mm and a width of 1
00 mm, 450 mm long mild steel plate, downward welding at a current of 210 A, no-load voltage 80 V by an AC welding machine, the determination method is that the coating material of the unused portion is degenerated and the coating cylinder is not formed, In addition, the arc is extinguished at a position where the arc state suddenly changes and becomes unstable and the arc force begins to decrease, and is represented by the remaining welding rod length at that time. The value is an average value of 10 test welding rods and is 100 mm. A value of less than was regarded as good and the judgment was marked with a circle. It was judged as inferior to 100 mm or more, and the judgment was marked with x.

[0025]

[Table 4]

[0026]

[Table 5]

The following are considered from Tables 4 and 5. The present invention examples (No. 1 to No. 17) relate to the welding rod of the present invention, the content of Mn in the steel core wire is appropriate, the content of pyrophyllite-based clay and the released water content are also appropriate. Therefore, not only the stick burn resistance but also the re-arcing property,
The welding workability was also good.

Next, No. 18-No. No. 32 is an example of a comparative welding rod. 18, No. 25, no. 31 is
Although the Mn content of the steel core wire is appropriate and the amount of water released from the pyrophyllite-based clay is also appropriate, the insulation content of the coated cylinder increases due to the large content, and re-arcing after welding is interrupted becomes worse. Further, the welding workability is deteriorated such that the arc becomes unstable and the spatter increases.

No. 19, No. No. 26 has an appropriate content of pyrophyllite-based clay and an appropriate amount of released water,
Although the rod burn resistance and the re-arcing property are good, since the Mn content in the steel core wire is low, the arc becomes weak and pits and blow holes occur due to insufficient deoxidation.

No. 20, No. No. 24, although the content of pyrophyllite-based clay and the amount of released water are appropriate, the specific resistance increases due to the high Mn content in the steel core wire, and the melting rate becomes slow, so the stick burn resistance deteriorates, Further, the arc spraying becomes too strong and undercutting easily occurs.

No. No. 21 has a proper Mn content in the steel core wire, but has a good content of pyrophyllite-based clay and a large amount of released water, and therefore has good rod burning resistance, but the arc spraying becomes strongly unstable and undercuts. Deterioration of welding workability such as occurrence of arc and increase of spatter is observed, and re-arcability is also deteriorated.

No. 22, No. 27 is M in the steel core wire
Although the amount of n is appropriate and the amount of water released from the pyrophyllite clay is also appropriate, no improvement in stick burn resistance can be seen due to the low content.

No. 23, No. 30 is M in the steel core wire
Although the amount of n is proper and the content of pyrophyllite-based clay is also proper, the amount of released water is large, so that the arc spraying becomes strong and undercutting and other welding workability deteriorate.

No. 28, No. 32 is M in the steel core wire
Although the amount of n is proper and the content of the pyrophyllite-based clay is also proper, the stick burn resistance is not improved because the amount of released water is small.

No. In No. 29, the Mn content in the steel core wire is appropriate, but since the content of pyrophyllite clay and the amount of released water are low, no improvement in stick burn resistance can be seen.

[0036]

As described above, the welding rod of the present invention overcomes the drawbacks of conventional non-low hydrogen type welding rods, and Mn in the steel core wire.
By controlling the amount, the content of pyrophyllite-based clay, and the amount of released water, it is possible to provide a welding rod that significantly improves rod burning resistance without degrading re-arcing and welding workability. The welding work is easy and contributes greatly to the improvement of the welding work efficiency.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-52-131944 (JP, A) JP-A-54-62135 (JP, A) JP-A-53-66839 (JP, A) JP-A-10- 193177 (JP, A) JP-A-9-234589 (JP, A) JP-A-8-276292 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23K 35/365

Claims (3)

(57) [Claims] 1. A steel core wire in which Mn is regulated to 0.15 to 0.28% by weight and 1 of hydrous mineral pyrophyllite clay
1.0 to 8.0% by weight of one kind or two or more kinds, and a coating agent composed of a gas generating agent, an arc stabilizer, a slag forming agent, a deoxidizing agent, a fixing agent, and inevitable impurities is applied. A non-low hydrogen system coated arc welding rod characterized by the following. 2. A hydrous mineral pyrophyllite clay 4
The non-low hydrogen type covered arc welding according to claim 1, wherein the amount of released moisture when heated at 00 ° C to 800 ° C is 0.05 to 0.55% by weight based on the total weight of the coating agent. rod. 3. The non-low hydrogen type coated arc welding rod according to claim 1, wherein C is 0.01 to 0.09% by weight.