JP2021133412A - Low hydrogen type coated electrode for horizontal fillet welding - Google Patents

Abstract

To provide a low hydrogen type coated electrode for horizontal fillet welding, capable of obtaining a weld metal having favorable low-temperature toughness, having no weld defect, excellent in welding workability and favorable in productivity.SOLUTION: A low hydrogen type coated electrode for horizontal fillet welding is characterized by including in mass% based on total mass of coating material, 5-15% total of metal carbonates, 1-10% total of metal fluoride, 8-18% total of TiO2 conversion value, 8-18% total of SiO2 conversion value, 1-6% total of Al2O3 conversion value, 5-15% MgO, 0.1-0.3% total of C, 2-8% Mn, 1-5% Ni, 0.1-2.0% Mg, 1-5% Ni-Mg alloy, 20-40% iron dust and 1-6% total of both conversion values of Na2O and K2O.SELECTED DRAWING: None

Description

The present invention relates to a low hydrogen-based shielded metal arc welding rod for horizontal fillet welding, in which a weld metal having particularly good low-temperature toughness can be obtained, and welding defects such as pits do not occur in horizontal fillet welding of prime-coated steel plates, which is excellent. The present invention relates to a low hydrogen-based shielded metal arc welding rod for horizontal fillet welding, which has good welding workability such as a bead shape and excellent productivity.

In recent years, steel plates of 490 MPa class high-strength steel or higher have been used due to the increase in size of welded structures such as buildings, bridges and ships. The demand is increasing.

However, the low hydrogen-based shielded metal arc welding rod for horizontal fillet welding has a thicker core wire and a thicker outer diameter than the normal shielded metal arc welding rod in order to secure the welding amount and leg length in 1-pass welding. Since it is a scale, a relatively large amount of oxide remains in the weld metal, and the low temperature toughness of the weld metal tends to decrease.

In addition, the low-hydrogen shielded metal arc welding rod for horizontal fillet welding has a larger diameter core wire and a thicker outer diameter than the normal product, so the coating cracks are likely to occur during drying of the welding rod production in terms of production. There is a problem that the yield is low and the productivity is poor.

On the other hand, in places where the steel sheet is used for a long time in a harsh environment such as a marine area, a primer-coated steel sheet in which the surface of the steel sheet is coated with a primer for the purpose of rust prevention is widely used. In the welding of welded structures using such a prime-coated steel plate, it is possible to weld complicated structures, the welding efficiency is high, and the quality of the welded metal can be made uniform. A low-hydrogen-based cover arc welding rod is used, but there is a problem that the prima coated on the steel plate surface is vaporized during welding and pits are likely to occur, and bead shape defects such as undercuts are also likely to occur. ..

Under such circumstances, the low temperature toughness of the weld metal is good, a good bead shape can be obtained by gravity welding, welding defects such as pits do not occur even when welding with prime coated steel plate, and productivity is also improved. An excellent shielded metal arc welding rod for low hydrogen fillet welding is disclosed.

For example, Patent Document 1 specifies the contents of high carbon ferromanganese, magnesia clinker, magnesite, and metal fluoride having an average particle size of 50 to 90 μm, whereby a low hydrogen coating that can obtain a good bead shape can be obtained. Arc welding rods are disclosed. However, the low hydrogen-based shielded metal arc welding rod described in Patent Document 1 has improved slag fluidity and improved bead shape by containing high carbon ferromanganese, but contains a large amount of C in the weld metal. Therefore, the strength of the weld metal is increased and the toughness is decreased. Further, since the particle size of high carbon ferromanganese is relatively fine, drying cracks of the coating are likely to occur. Further, since the low hydrogen-based shielded metal arc welding rod described in Patent Document 1 does not contain any deoxidizing agent or the like, sufficient pit resistance cannot be obtained when welding with a primer-coated steel plate, and pits are formed. There is a problem that it is easy to occur.

Further, Patent Document 2 describes a low-hydrogen shielded metal arc welding rod for low-temperature steel that reduces oxygen in the weld metal and improves the low-temperature toughness of the weld metal by the synergistic effect of a strong deoxidizer such as Ti, Al or Mg. It is disclosed. However, with the shielded metal arc welding rod for low temperature steel described in Patent Document 2, although the low temperature toughness of the weld metal can be improved, a good bead shape cannot be obtained. In addition, since it contains a large amount of metal elements that are highly reactive with hydrogen or water, there is a problem that drying cracks of the coating are likely to occur.

Further, Patent Document 3 discloses a low hydrogen-based shielded metal arc welding rod that improves fracture toughness by reducing oxygen in the weld metal by containing a Ni—Mg alloy in the coating agent. However, the low hydrogen-based shielded metal arc welding rod described in Patent Document 3 can obtain good low-temperature toughness of the weld metal, but cannot obtain a good bead shape, and has sufficient resistance when welding with a prime-coated steel sheet. Pit characteristics cannot be obtained and pits are likely to occur. In addition, there is a problem that coating cracks are likely to occur during drying during manufacturing of the welding rod.

Japanese Unexamined Patent Publication No. 5-261592 Japanese Unexamined Patent Publication No. 10-175094 Japanese Unexamined Patent Publication No. 9-327793

Therefore, the present invention has been devised in view of such a problem, and a weld metal having good toughness can be obtained at a low temperature of -60 ° C. An object of the present invention is to provide a low hydrogen-based shielded metal arc welding rod for horizontal fillet welding, which has excellent welding workability such as no defects and a good bead shape without undercuts and good productivity. do.

The gist of the present invention is that in a low hydrogen-based coated arc welding rod for horizontal fillet welding in which a coating agent is applied to a steel core wire, the coating agent is 1 of a metal carbonate in mass% with respect to the total mass of the coating agent. Total of seeds or 2 or more: 5 to 15%, Total of 1 or 2 or more of metal fluorides: 1 to 10%, Total of Ti Oxide _{converted to TiO 2} : 8 to 18%, Si oxide Total SiO ₂ conversion value: 8 to 18%, Total Al ₂ O ₃ conversion value of Al oxide: 1 to 6%, MgO: 5 to 15%, Total C in alloy containing C and C: 0.1-0.3%, Mn: 2-8%, Ni: 1-5%, Mg: 0.1-2.0%, Ni-Mg alloy: 1-5% for Ni and Mg. Contains 20-40% iron powder _{, total Na 2} O conversion value and K ₂ O conversion value of Na oxide and K oxide: 1 to 6%, and the others are coating agents and Fe from iron alloys. It is characterized by being composed of minutes and unavoidable impurities.

It is also characterized by further containing Al: 0.1 to 0.6% in mass% with respect to the total mass of the coating agent.

Further, the low hydrogen-based coated arc welding rod for horizontal fillet welding is also characterized in that it further contains _{MnO 2} : 0.1 to 3.0% in mass% with respect to the total mass of the coating agent.

According to the low hydrogen-based shielded metal arc welding rod for horizontal fillet welding of the present invention, a weld metal having excellent toughness can be obtained at a low temperature, and welding defects such as pits do not occur even in horizontal fillet welding of a prime-coated steel plate. Welding workability is good, such as obtaining a good bead shape without undercuts, and productivity is also excellent, so welding quality can be improved.

The present inventors have diligently studied the low-temperature toughness of the weld metal of a low-hydrogen shielded metal arc welding rod for horizontal fillet welding, and replaced a part of Ni and Mg with a Ni-Mg alloy to contain it in the coating agent. The present invention has been completed by finding that the low temperature toughness of the weld metal can be improved by this.

The low hydrogen-based shielded metal arc welding rod for horizontal fillet welding contains Ni, Mn and strong deoxidizers Al, Mg, Al-Mg, etc. for the purpose of ensuring good toughness of the weld metal at low temperature. There is. In particular, Mg is a metal element that has high reactivity with oxygen at high temperatures and is excellent as a strong deoxidizer. However, the melting point of Mg is about 650 ° C., and the Mg surface is oxidized in the temperature range of the firing temperature of 400 to 500 ° C. at the time of production of the welding rod, and the original deoxidizing ability as Mg is not sufficiently exhibited. In addition, a fixing agent containing water is added during the production of the welding rod, but since Mg has high reactivity with water, if the content of Mg is high, the water in the fixing agent reacts with Mg, and welding is performed. There is a problem that coating cracks are likely to occur during drying of the rod.

As a result of further study on deoxidizers such as Si, Mn, and Si-Mn as deoxidizers other than Mg, the present inventors further investigated the deoxidizers such as Si, Mn, and Si-Mn. I was able to suppress it. However, when trying to obtain the same amount of oxygen in the weld metal as when Mg was contained, the alloy component in the weld metal became excessive and the low temperature toughness could not be improved.

Therefore, as a result of examining a strong deoxidizer effective for low temperature toughness in a low hydrogen-based shielded metal arc welding rod for horizontal fillet welding, the present inventors have defined the contents of Ni and Mg and have a melting point. By adding an appropriate amount of Ni-Mg alloy, which is as high as about 1200 ° C, oxidation of Mg is suppressed even at a firing temperature of 400 to 500 ° C, and Mg can function as a strong deoxidizer without reducing its deoxidizing ability. It was found that it is effective in improving the low temperature toughness of metals, and that the low temperature toughness can be further improved by adding an appropriate amount of Al. It was also found that sufficient strength of the weld metal can be secured by adding an appropriate amount of C and an alloy containing C and Mn.

Furthermore, the present inventors can reduce the content of Mg as a single substance by adding an appropriate amount of Ni-Mg alloy, so that it is possible to reduce the coating cracking during drying during production, and the productivity can be improved. I found out.

Regarding welding workability, the present inventors add an appropriate amount of metal carbonate, Na oxide and K oxide, alloy containing C and C, Ti oxide and iron powder for arc spraying and arc stability. It was found that the amount of spatter generated and the amount of fume generated could be reduced. In addition, the slag encapsulation property and slag peelability are obtained by adding an appropriate amount of Si oxide and MgO, and the bead shape is Ti oxide, Si oxide, an alloy containing C and C, Al oxide and Ni-Mg alloy. It was found that adding an appropriate amount improved the condition, and that stick burning during welding could be prevented by adding an appropriate amount of iron powder.

Further, the present inventors can sufficiently deoxidize the oxygen in the molten pool while maintaining a strong arc by adding an appropriate amount of metal fluoride and deoxidizing agents Mn and Mg to welding defects such as pits. Therefore, it was found that welding defects such as pits can be prevented.

Hereinafter, the component composition of the coating agent for the low hydrogen-based coated arc welding rod for horizontal fillet welding of the present invention and the reason for limiting the component composition will be described in detail. The content of each component composition shall be expressed in mass% with respect to the total mass of the coating agent, and when the mass% is expressed, it shall be simply described as%.

[Total of one or more metal carbonates: 5-15%]
Metallic carbonate is added from magnesium carbonate, calcium carbonate, barium carbonate, manganese carbonate, etc., and decomposes in an arc atmosphere to generate carbonic acid gas, which is a gas component such as oxygen, nitrogen, and hydrogen that tries to enter the molten pool. In addition to protecting from the pits, it has the effect of preventing the occurrence of welding defects such as pits by strengthening the spraying of the arc and increasing the agitation of the molten pool. If the total of one or more of the metal carbonates is less than 5%, the shielding effect is insufficient, the arc spraying is weakened, and welding defects such as pits are likely to occur. On the other hand, if the total of one or more of the metal carbonates exceeds 15%, the arc spraying becomes too strong and undercuts are likely to occur, resulting in a poor bead shape. Therefore, the total of one or more metal carbonates is 5 to 15%.

[Total of one or more metal fluorides: 1-10%]
Metal fluorides are added from fluorite, magnesium fluoride, barium fluoride, aluminum fluoride, cryolite, sodium fluoride, lithium fluoride, etc. to adjust the fluidity of molten slag and the vapor pressure of fluoride. Therefore, it has the effect of protecting the molten land from gas components such as oxygen, nitrogen and hydrogen. If the total of one type or two or more types of metal fluoride is less than 1%, the shielding property of the molten metal deteriorates, and welding defects such as pits are likely to occur. On the other hand, if the total of one or more of the metal fluorides exceeds 10%, the melting point of the molten slag is lowered and the slag peelability is deteriorated. Therefore, the total of one or more types of metal fluoride is 1 to 10%.

_{[Total TiO 2} conversion value of Ti oxide: 8-18%]
Ti oxide is added from rutile, titanium oxide, sodium titanate, titanium slag, illuminate, etc., acts as an arc stabilizer and a slag viscosity modifier, stabilizes the arc, reduces the amount of spatter generated, and beads. It has the effect of improving the shape. _{If the total of the TIO 2} conversion values of the Ti oxide is less than 8%, the arc becomes unstable and the amount of spatter generated increases. On the other hand, _{if the total value of the Ti oxides converted to TIO 2} is less than 8%, the viscosity of the slag becomes poor and the bead shape becomes poor. On the other hand, when _{the total of the TIO 2} conversion values of the Ti oxide exceeds 18%, the slag becomes dense and the slag peelability becomes poor. Therefore, _{the total TiO 2} conversion value of Ti oxide is set to 8 to 18%.

_{[Total SiO 2} conversion value of Si oxide: 8-18%]
Si oxide is added from silica sand, feldspar, water glass and the like, and has an effect of improving slag viscosity adjusting agent and slag encapsulation. _{If the total SiO 2} conversion value of the Si oxide is less than 8%, the slag encapsulation property becomes poor and the bead shape becomes poor. On the other hand, when _{the total SiO 2} conversion value of the Si oxide exceeds 18%, the viscosity of the slag becomes high and the distance between the molten pool and the molten slag becomes short, so that the slag encapsulation property becomes poor. Therefore, the total value of Si oxide in _{terms of SiO 2} is set to 8 to 18%.

_{[Total Al 2} O ₃ conversion value of Al oxide: 1 to 6%]
Al oxide is added from alumina, feldspar, mica, etc., and has the effect of adjusting the viscosity of molten slag to improve the bead shape. _{If the total Al 2} O ₃ conversion value of the Al oxide is less than 1%, the viscosity of the molten slag becomes low and the bead shape becomes poor. On the other hand, when _{the total of the Al 2} O ₃ conversion values of the Al oxide exceeds 6%, the viscosity of the slag becomes high, so that the distance between the molten pool and the molten slag becomes short, and the slag encapsulation property becomes poor. Therefore, _{the total of Al 2} O ₃ conversion values of Al oxide is 1 to 6%.

[MgO: 5 to 15%]
MgO is added from magnesia clinker and the like, and has the effect of improving the slag peelability. If MgO is less than 5%, the solidification temperature of the slag is low and the slag peelability becomes poor. On the other hand, when MgO exceeds 15%, the solidification temperature of the slag becomes excessively high, and the bead shape becomes poor. Therefore, MgO is set to 5 to 15%.

[Total of C in the alloy containing C and C: 0.1 to 0.3%]
C is added in a state where C is attached to an alloy powder such as graphite or Fe-Mn to improve the strength of the weld metal, strengthen the spraying of the arc, deepen the penetration of the weld metal, and bead. It has the effect of improving the shape. If the total of C in the alloy containing C and C is less than 0.1%, the arc spraying becomes weak, a sufficient penetration depth cannot be obtained, the bead shape becomes poor, and the strength of the weld metal decreases. do. On the other hand, when the total of C in the alloy containing C and C exceeds 0.3%, the amount of C in the weld metal increases, the strength of the weld metal increases, and the toughness of the weld metal decreases. Furthermore, when the total of C in the alloy containing C and C exceeds 0.3%, the arc temperature of the molten ground rises, the amount of fume generated increases, and the arc spraying becomes excessively strong, resulting in spatter. The amount generated also increases. Therefore, the total C conversion value in the alloy containing C and C is set to 0.1 to 0.3%.

[Mn: 2-8%]
Mn is added from alloy powders such as metal Mn and Fe-Mn, acts as a deoxidizer, and has the effect of improving the strength and toughness of the weld metal. If Mn is less than 2%, deoxidation is insufficient, the strength and toughness of the weld metal are lowered, and welding defects such as pits are likely to occur. On the other hand, when Mn exceeds 8%, the strength of the weld metal becomes excessively high. Therefore, Mn is set to 2 to 8%.

[Ni: 1-5%]
Ni is added from alloy powders such as metallic Ni, Fe-Ni, and Ni-Mg alloys, and has the effect of improving the strength and toughness of the weld metal. If Ni is less than 1%, the required toughness of the weld metal cannot be obtained. On the other hand, when Ni exceeds 5%, the strength of the weld metal becomes excessively high. Therefore, Ni is set to 1 to 5%.

[Mg: 0.1 to 2.0%]
Mg is added from alloy powders such as metal Mg, Al-Mg, and Ni-Mg alloys, acts as a strong deoxidizer, prevents welding defects such as pits, and has the effect of improving the toughness of the weld metal. .. If Mg is less than 0.1%, deoxidation will be insufficient and the toughness of the weld metal will decrease. Further, if Mg is less than 0.1%, welding defects such as pits are likely to occur. On the other hand, if Mg exceeds 2.0%, the toughness of the weld metal is improved, but coating cracks are likely to occur during drying of the welding rod production, the product yield is lowered, and the productivity is deteriorated. Therefore, Mg is set to 0.1 to 2.0%.

[Ni-Mg alloy: 1-5%]
The above-mentioned Ni-Mg alloy containing metallic Ni and metallic Mg has the effect of improving productivity and improving the bead shape. If the content of the Ni-Mg alloy containing Ni and Mg is less than 1%, the amount of Mg and Al-Mg in the coating agent is relatively large, and coating cracks are likely to occur during drying. Further, if the content of the Ni—Mg alloy containing Ni and Mg is less than 1%, the protective cylinder melts unevenly during welding, undercuts are likely to occur, and the bead shape becomes poor. On the other hand, if the content of the Ni—Mg alloy containing Ni and Mg exceeds 5%, the slag peelability becomes poor. Therefore, the Ni-Mg alloy containing Ni and Mg described above is set to 1 to 5%. The Ni-Mg alloy has a ratio of 70 to 90% for Ni and 10 to 30% for Mg.

[Iron powder: 20-40%]
Iron powder has the effect of stabilizing the arc. If the iron powder content is less than 20%, the arc becomes unstable and the amount of spatter generated increases. On the other hand, when the iron powder exceeds 40%, an electric current tends to flow through the coating agent, and stick burning is likely to occur. Therefore, the iron powder is 20 to 40%.

_{[Total of Na 2} O conversion value and K ₂ O conversion value of Na oxide and K oxide: 1 to 6%]
Na oxide and K oxide are added from sodium silicate and potassium silicate, potassium feldspar, potassium feldspar, soda feldspar and the like in water glass, and have the effect of stabilizing the arc and reducing the amount of spatter generated. _{If the total of the Na 2} O conversion value and the K ₂ O conversion value of the Na oxide and the K oxide is less than 1%, the arc becomes unstable and the amount of spatter generated increases. On the other hand, when _{the total of the Na 2} O conversion value and the K ₂ O conversion value of Na oxide and K oxide exceeds 6%, the arc spraying becomes excessively strong, undercut is likely to occur, and the bead shape is formed. Becomes defective. _{Therefore, the total of the Na 2} O conversion value and the K ₂ O conversion value of Na oxide and K oxide is 1 to 6%.

[Al: 0.1-0.6%]
Al is added from alloy powders such as metal Al, Fe-Al, and Al-Mg, acts as a strong deoxidizer, prevents welding defects such as pits, and has the effect of further improving the toughness of the weld metal. .. If Al is less than 0.1%, the effect of suppressing the occurrence of welding defects such as pits cannot be sufficiently obtained, and the effect of improving the toughness of the weld metal cannot be sufficiently obtained. On the other hand, when Al exceeds 0.6%, Al ₂ O ₃ stays excessively in the weld metal, the amount of oxygen in the weld metal increases, and the toughness of the weld metal decreases. Therefore, Al is 0.1 to 0.6%.

[MnO ₂ : 0.1 to 3.0%]
MnO ₂ is decomposed by an endothermic reaction in an arc atmosphere, and has the effect of further strengthening the spraying of the arc. If MnO ₂ is less than 0.1%, the effect of strengthening the spraying of the arc cannot be sufficiently obtained. On the other hand, when MnO ₂ exceeds 3.0%, the arc spraying becomes excessively strong, undercuts are likely to occur, and the bead shape becomes poor. Therefore, MnO ₂ is set to 0.1 to 3.0%.

In addition to the above-mentioned components, the other components in the coating agent for the low-hydrogen shielded metal arc welding rod for horizontal fillet welding of the present invention include 0.1 to 3 coating agents such as sodium alginate and cellulose from the viewpoint of productivity. %, Fe content from iron alloys such as Fe-Mn, Fe-Ni, Fe-Al and unavoidable impurities.

Further, it is preferable to use JIS G 3523 SWY11 as the steel core wire to be used. Further, the coverage of the coating agent on the steel core wire is preferably 35 to 55%.

Hereinafter, the effects of the present invention will be described in more detail with reference to Examples.

Various coating agents shown in Table 1 are used for JIS G 3523 SWY11 steel core wire having a diameter of 5.0 mm and a length of 700 mm (C: 0.06% by mass, Si: 0.09% by mass, based on the total mass of the steel core wire). Mn: 0.51%, P: 0.008%, S: 0.003 mass), the coating agent of the composition component shown in Table 1 was applied at a coverage rate of 40 to 50%, and then the welding rod was fired at 400 ° C. We made various prototypes and investigated productivity, welding workability, pit resistance and mechanical properties.

In the productivity evaluation, 500 kg of various prototype welding rods were produced, and the presence or absence of coating cracks was visually confirmed at the time of production, and those having a good coating appearance and no defects were considered to be good.

Welding workability was evaluated by using various prototype welding rods and using a T-shaped primer-coated steel plate with a JIS G 3106 SM490A, plate thickness 12 mm x width 100 mm x length 1000 mm coated with a wash primer with a thickness of 25 to 35 μm. Horizontal fillet welding is performed with a T-shaped test piece assembled in a mold with a welding current of 200 A by gravity welding using an AC welding machine, and arc spraying, arc stability, spatter generation amount and fume generation amount, bead shape. , The slag encapsulation property, the quality of the slag peeling property, and the presence or absence of stick burning were visually investigated. The pit resistance was good when no pits were generated over the entire length of the weld bead.

For the evaluation of mechanical properties, a weld metal test was conducted with an AC welder according to JIS Z 3111 using a steel plate with a thickness of 20 mm of JIS G 3106 SM490A, and a tensile test piece (A1) and an impact test piece (V notch) were evaluated. The test piece) was collected and subjected to a tensile test and an impact test. In the tensile test, the tensile strength was 490 to 600 MPa, and in the impact test, the test temperature was -60 ° C., and the average value of the absorbed energy three times was set to be good at 34 J or more. The results of these surveys are summarized in Table 2.

Welding rod Nos. in Tables 1 and 2. 1-Welding rod No. 15 is an example of the present invention, welding rod No. 15. 16-Welding rod No. 30 is a comparative example. Welding rod No. of the present invention. 1-Welding rod No. Reference numeral 15 denotes a total of metal carbonates in the coating agent, a total of metal fluorides, a total of Ti oxide _{converted to TiO 2,} a total of Si oxide _{converted to SiO 2} , and an Al oxide converted to _{Al 2} O _{3. Total values, total C in alloys containing MgO, C and C, Na 2} O conversion values and K ₂ O conversion values of Mn, Ni, Mg, Ni-Mg alloys, iron powder, Na oxides and K oxides Since the total value was an appropriate amount, the productivity was good, such as no coating cracking during production. In addition, the spraying of the arc is good, the arc is stable, the amount of fume and spatter generated is small, the bead shape is good, the slag encapsulation and slag peelability are good, and the stick burns. Welding workability was good, such as no occurrence of slag. In addition, no pits were generated in the weld metal, and both the tensile strength and the absorbed energy of the weld metal were good.

In addition, the welding rod No. In 4, 6, 8, 9, 12, 13, and 15, since an appropriate amount of Al was added, the absorption energy of the weld metal was even better at 60 J or more. Furthermore, the welding rod No. In 5, 8, 9, 11, 13 to 15, _{since an appropriate amount of MnO 2} was added, the arc spraying was strong and good.

Welding rod No. in the comparative example. In No. 16, since the total amount of metal carbonate was large, the arc spraying became excessively strong, undercut occurred, and the bead shape was poor. Further, since the total amount of C in the alloy containing C and C was large, the amount of fume generated and the amount of spatter generated were large. Further, C was excessively dissolved in the weld metal, the tensile strength of the weld metal was high, and the absorbed energy was low.

Welding rod No. In No. 17, since the total amount of metal carbonate was small, the arc was weakly sprayed and pits were generated. Further, since the amount of Mn was large, the tensile strength of the weld metal was high.

Welding rod No. In No. 18, the total amount of metal fluoride was large, so that the slag removability was poor. _{Further, since the total of the Na 2} O conversion value and the K ₂ O conversion value of Na oxide and K oxide was large, the arc spraying was excessively strong, undercut occurred, and the bead shape was poor.

Welding rod No. In No. 19, since the total amount of metal fluoride was small, the shielding property of the molten pool was lowered and pits were generated. Further, since the amount of Ni—Mg alloy was small, undercut occurred and the bead shape was poor. Further, since the amount of Ni—Mg alloy is small, drying cracks occur during production, resulting in poor productivity.

Welding rod No. In No. 20, since the total amount of C in the alloy containing C and C was small, the arc spraying was weak, sufficient penetration could not be obtained, and the bead shape was poor. In addition, the tensile strength of the weld metal was low. Further, _{since the amount of MnO 2} is small, the effect of strengthening the spraying of the arc could not be obtained.

Welding rod No. In No. 21, since Mn was small, deoxidation was insufficient, pits were generated, and the tensile strength and absorbed energy of the weld metal were low. Further, since the amount of Al is small, the effects of suppressing the generation of pits and improving the absorbed energy of the weld metal could not be obtained.

Welding rod No. In No. 22, _{since the total of the TiO 2} conversion values of the Ti oxide was large, the slag became dense and the slag peelability was poor. Further, since the total value of the Si oxides _{converted to SiO 2} is small, the slag encapsulation property is poor and the bead shape is poor.

Welding rod No. In No. 23, _{since the total of the TIO 2} conversion values of the Ti oxide was small, the arc was unstable, the amount of spatter generated was large, and the bead shape was poor. Further, since the total of the Al ₂ O ₃ conversion values of the Al oxide was large, the slag encapsulation property was poor.

Welding rod No. In No. 24, _{the total value of Si oxides converted to SiO 2} was large, so that the slag encapsulation property was poor. Further, since MnO ₂ is large, the arc spraying is excessively strong, undercut occurs, and the bead shape is poor.

Welding rod No. No. 25 had a poor bead shape because the total _{of Al 2} O _{3 conversion values of Al oxide was small.} Moreover, since the amount of Ni was small, the absorbed energy of the weld metal was low.

Welding rod No. In No. 26, since there was a large amount of MgO, the slag solidified quickly and the bead shape was poor. _{Further, since the total of the Na 2} O conversion value and the K ₂ O conversion value of Na oxide and K oxide was small, the arc became unstable and the amount of spatter generated was large.

Welding rod No. In No. 27, since the amount of MgO was small, the solidification temperature of the slag was low and the slag peelability was poor. Further, since the amount of iron powder was small, the electrical conductivity of the coating was deteriorated, the arc became unstable, and the amount of spatter generated was large.

Welding rod No. No. 28 had a high tensile strength of the weld metal because it contained a large amount of Ni. In addition, since the amount of Mg is large, coating cracks occur during drying, resulting in poor productivity.

Welding rod No. In No. 29, since the amount of Mg was small, deoxidation was insufficient and pits were generated. Moreover, since the amount of Mg was small, the absorbed energy of the weld metal was low. Furthermore, since there is a large amount of iron powder, stick burning occurred during welding.

Welding rod No. No. 30 had a large amount of Ni-Mg, so that the slag peelability was poor. Moreover, since the amount of Al was large, the absorbed energy of the weld metal was low.

Claims (3)

In a low hydrogen-based shielded metal arc welding rod for horizontal fillet welding in which a coating agent is applied to the steel core wire,
The coating agent is a mass% based on the total mass of the coating agent.
Total of one or more metal carbonates: 5-15%,
Total of one or more metal fluorides: 1-10%,
_{Total TiO 2} conversion value of Ti oxide: 8-18%,
_{Total SiO 2} conversion value of Si oxide: 8-18%,
_{Total Al 2} O ₃ conversion value of Al oxide: 1 to 6%,
MgO: 5-15%,
Total of C in the alloy containing C and C: 0.1-0.3%,
Mn: 2-8%,
Ni: 1-5%,
Mg: 0.1 to 2.0%,
The Ni and Mg contain a Ni—Mg alloy: 1 to 5%.
Iron powder: 20-40%,
_{Total of Na 2} O conversion value and K ₂ O conversion value of Na oxide and K oxide: 1 to 6% is contained.
Others are low hydrogen-based shielded metal arc welding rods for horizontal fillet welding, which are composed of a coating agent, Fe content from an iron alloy, and unavoidable impurities. The low hydrogen-based coated arc welding rod for horizontal fillet welding according to claim 1, further containing Al: 0.1 to 0.6% in mass% with respect to the total mass of the coating agent. The low hydrogen-based shielded metal arc welding for horizontal fillet welding according to claim 1 or 2, further containing _{MnO 2} : 0.1 to 3.0% in mass% with respect to the total mass of the coating agent. rod.