JP2013151001A - Flux-cored wire for gas-shielded arc welding for weather-resistant steel - Google Patents

Abstract

The present invention provides a flux-cored wire for gas shielded arc welding for weathering steel, in which welding workability in all-position welding is good when welding weathering steel, and a weld metal having excellent strength and toughness can be obtained.
SOLUTION: In mass% with respect to the total mass of the wire, C: 0.01 to 0.08%, Si: 0.1 to 1.0%, Mn: 1.0 to 3.0%, Cu: 0.2 ~0.8%, Cr: 0.3~0.8%, Mg: 0.05~0.8%, TiO 2 converted value: 3 to 8%, SiO ₂ conversion value: 0.1 to 1.0 %, Al ₂ O ₃ converted value: 0.05 to 1.2%, Na converted value and K converted value: 0.01 to 0.4%, F converted value: 0.005 to 0.2% And the Al oxide has an apparent density of 1.4 to 2.5 g / cm ³ and an average particle diameter of 20 to 200 μm, and is a flux-cored wire for gas shielded arc welding for weathering steel. .
[Selection figure] None

Description

  The present invention has good welding workability in all-position welding when welding weatherable steel used for steel structures and the like, and is suitable for obtaining weathered steel excellent in strength and toughness. The present invention relates to a flux-cored wire for gas shielded arc welding.

  Weather-resistant steel is applied to ships, bridges, other steel structures, etc., and when welding such weather-resistant steel, rutile flux-cored wire is widely applied, as is low-carbon steel. The slag generated when welding with a rutile flux cored wire has very suitable characteristics for all position welding, so that the molten metal does not droop in an upright or upward position. It can be welded and has excellent welding workability.

  In recent years, in order to weld more efficiently, there is a tendency to perform welding at a high current, and a flux-cored wire for ordinary steel corresponding thereto is disclosed in, for example, JP 2009-61474 A (Patent Document 1) and JP It is proposed in 2010-17733 gazette (patent document 2). These disclosed techniques are all aimed to prevent molten metal from dripping even when a high welding current is used in vertical welding. Actually, however, it is not sufficient because the weld metal cannot be prevented from dripping sufficiently in the vertical welding at high currents, or the weld bead has a convex shape even if it can be prevented from dripping. is there.

  On the other hand, in the technique proposed in Japanese Patent Application Laid-Open No. 2011-156565 (Patent Document 3), molten metal does not sag in the vertical improvement welding at a high current, and the bead shape can be made flat. However, for that purpose, it is necessary to add a very large amount of metal Al. In this case, a large amount of Al remains in the weld metal, which causes a decrease in the toughness of the weld metal. Furthermore, when applied to a flux-cored wire for welding for weather-resistant steel, Cr that reduces the toughness of the weld metal is essential, and adding a large amount of metal Al causes a significant decrease in the toughness of the weld metal. is there.

JP 2009-61474 A JP 2010-17733 A JP 2011-156565 A

  The present invention has been devised in view of the above-mentioned problems, and the object of the present invention is to perform all-position welding in welding weathering steel used for ships, bridges, other steel structures and the like. Flux for weather-resistant steel gas-sealed arc welding with good welding workability, especially in high-current standing-up welding where molten metal does not sag and weld metal with excellent weld metal strength and toughness is obtained It is to provide a corrugated wire.

The gist of the present invention is as follows.
(1) In a flux-cored wire for gas-shielded arc welding for weatherproof steel, in which a steel outer shell is filled with flux, C: 0.01 to 0.08%, Si: 0.00 1 to 1.0%, Mn: 1.0 to 3.0%, Cu: 0.2 to 0.8%, Cr: 0.3 to 0.8%, Mg: 0.05 to 0.8% TiO ₂ conversion value of Ti oxide: 3 to 8%, SiO ₂ conversion value of Si oxide: 0.1 to 1.0%, Al ₂ O ₃ conversion value of Al oxide: 0.05 to 1. 2%, Na compound and K compound in Na converted value and K converted value: 0.01 to 0.4%, F in metal fluoride converted value: 0.005 to 0.2%, P: 0.03% or less, S: 0.03% or less, the balance is made of Fe of steel outer shell, iron powder, Fe content of iron alloy powder and inevitable impurities, the Al oxide is An apparent density: 1.4 to 2.5 g / cm ³ and an average particle size: 20 to 200 μm. A flux-cored wire for gas shielded arc welding for weatherproof steel.

(2) The flux-cored wire for gas shielded arc welding for weathering steel according to (1), characterized by containing Ni: 0.05 to 0.8% by mass% relative to the total mass of the wire.

(3) Mass% based on the total mass of the wire, and the total of ZrO ₂ converted values of metal Zr and Zr oxide: 0.1 to 1%, Al: one or two of 0.05 to 0.6% The flux-cored wire for gas shielded arc welding for weathering steel according to (1) or (2), characterized by comprising.

(4) The mass% based on the total mass of the wire, and B: containing one or two of 0.0005 to 0.01%, according to any one of (1) to (3) Flux-cored wire for gas shielded arc welding for weathering steel.

(5) Mass% relative to the total mass of the wire, Mo: 0.05 to 0.3%, V: 0.02 to 0.2%, Nb: 0.02 to 0.2%, or one or more The flux-cored wire for gas-shielded arc welding for weatherproof steel according to any one of (1) to (4), characterized in that

  According to the flux-cored wire for gas shielded arc welding of the weathering steel of the present invention, the weld metal has good welding workability without dripping down the molten metal in all-position welding of the weathering steel, particularly in the vertical welding with high current. In addition, a weld metal excellent in strength and toughness can be stably obtained, and the quality of the welded portion can be improved.

  The inventors of the present invention have a welding workability in all-position welding, particularly in a high-current stand-up advancement welding, and a high strength for a flux-cored wire for gas shielded arc welding for rutile-based weathering steel. In addition, various investigations were made on the wire component composition from which a weld metal excellent in toughness was obtained.

  As a result, by optimizing the apparent density and average particle diameter of the Al oxide raw material added to the flux, and by further optimizing the addition amount of Al oxide, Ti oxide and Si oxide, It is possible to suppress the molten metal from being melted and to obtain a smooth weld bead in the progress welding of current, and to obtain an appropriate amount of C, Si, Mn as an alloy component and Mg as a deoxidizer. Thus, it has been found that a weld metal excellent in strength and toughness of the weld metal can be obtained stably.

That is, the flux-cored wire for gas shielded arc welding for weatherproof steel to which the present invention is applied is a mass with respect to the total mass of the wire in the flux-cored wire for gas shielded arc welding for weatherproof steel, in which the steel outer shell is filled with flux. %: C: 0.01 to 0.08%, Si: 0.1 to 1.0%, Mn: 1.0 to 3.0%, Cu: 0.2 to 0.7%, Cr: 0 .3~0.9%, Mg: 0.05~0.8%, TiO 2 converted value of Ti oxides: 3 to 8%, SiO ₂ conversion value of Si oxide: 0.1% to 1.0% , Al ₂ O ₃ conversion value of Al oxide: 0.05 to 1.2%, the total of Na converted value and K converted value of the Na compound and K compound: .01 to 0.4 percent, the metal fluoride F conversion value: 0.005 to 0.2% contained, P: 0.03% or less, S: 0.03% or less, the balance is made of steel Of Fe, iron powder, is made of Fe content and unavoidable impurities iron alloy powder.

Further, in the flux-cored wire for gas shielded arc welding for weather resistant steel to which the present invention is applied, the Al oxide has an apparent density of 1.4 to 2.5 g / cm ³ and an average particle size of 20 to 200 μm. It is characterized by.

  In addition, if this invention satisfy | fills the range of the component mentioned above, and a numerical value range, there will exist an effect effect desired, and it is contained in the scope of the present invention. However, it is more desirable to satisfy the following component ranges.

That is, Ni: 0.05 to 0.8% may be contained in mass% with respect to the total mass of the wire. Moreover, it is the mass% with respect to the total mass of the wire, and contains the metal Zr and the ZrO ₂ converted value of the Zr oxide: 0.1 to 1%, Al: one or two of 0.05 to 0.6%. You may do it. Moreover, you may make it contain B: 0.0005-0.01% by the mass% with respect to the total mass of a wire. Furthermore, in mass% with respect to the total mass of the wire, one or more of Mo: 0.05 to 0.3%, V: 0.02 to 0.2%, Nb: 0.02 to 0.2% You may make it contain.

  Hereinafter, the components of the flux-cored wire for gas shielded arc welding for weatherproof steel according to the present invention, the composition thereof, the content thereof, and reasons for limiting other numerical values will be described. First, the basic components of the flux-cored wire for gas shielded arc welding for weathering steel according to the present invention will be described. The composition of each component is expressed by mass% with respect to the total mass of the wire, and when expressing the mass%, it is simply expressed as%.

[C: 0.01 to 0.08%]
C has an effect of contributing to arc stabilization during welding. However, if the C content is less than 0.01%, this effect cannot be sufficiently obtained. On the other hand, when the C content exceeds 0.08%, C becomes excessive in the weld metal, and on the contrary, the toughness decreases. For this reason, content of C shall be 0.01-0.08%.

  C is added from a steel outer shell, metal powder, alloy powder, or the like in the flux.

[Si: 0.1 to 1.0%]
Si is partly welded slag during welding to improve the appearance and shape of the weld bead and contribute to the improvement of welding workability. However, if the Si content is less than 0.1%, the effect of improving the appearance and shape of the weld bead cannot be obtained sufficiently. On the other hand, when the Si content exceeds 1.0%, Si becomes excessive in the weld metal and the toughness is lowered. For this reason, content of Si shall be 0.1-1.0%.

  In addition, Si is added from alloy forms, such as Fe-Si and Fe-Si-Mn, besides the steel outer shell and metal Si in the flux.

[Mn: 1.0 to 3.0%]

  Mn, like Si, becomes part of the weld slag during welding to improve the appearance and shape of the weld bead and contribute to the improvement of welding workability. However, if the Mn content is less than 1.0%, these effects cannot be obtained sufficiently. Further, if the Mn content exceeds 3.0%, Mn becomes excessive in the weld metal, the strength becomes excessive, and the toughness decreases. For this reason, content of Mn shall be 1.0-3.0%.

  In addition, Mn is added from steel forms or alloy forms, such as Fe-Mn and Fe-Si-Mn in a flux.

[Cu: 0.2 to 0.7%]

  Cu is an essential element for imparting weather resistance to the weld metal. In JIS Z 3320, the P type to be used after painting, the W type to be used barely, and the rust stabilization treatment to be used depending on the usage situation, and the respective flux-cored wires for weathering steel are specified. In the former, Cu in the deposited metal is regulated to 0.20 to 0.50%, and in the latter, 0.30 to 0.60%. Therefore, the lower limit is set to 0.20%. The upper limit is set to 0.7%, which is higher than the upper limit of 0.6% for the JIS W type in consideration of a decrease in the rate of transition to the weld metal due to dilution of the base metal.

  Cu is added from Fe-Cu or the like in addition to Cu plating on the wire surface or metal Cu in the flux.

[Cr: 0.3-0.9%]

  Cr, like Cu, is an essential element for imparting weather resistance to the weld metal. Similar to Cu, in JIS Z 3320, the amount of Cr in the weld metal is defined for each of the P type and W type, and the ranges are 0.30 to 0.60% for the former and 0.45 to 0 for the latter. Therefore, the lower limit was set to 0.30%. The upper limit is set to 0.9%, which is higher than the upper limit of 0.75% of the JIS W type in consideration of a decrease in the rate of transition to weld metal due to dilution of the base metal. Note that Cr is added from a Cr alloy such as Fe—Cr in addition to the metal Cr in the flux.

[Mg: 0.05 to 0.8%]

  Mg acts as a strong deoxidizer, reduces oxygen in the weld metal, and increases the toughness of the weld metal. However, if the Mg content is less than 0.05%, this effect cannot be sufficiently obtained. On the other hand, if the Mg content exceeds 0.8%, the amount of spatter and fumes increases due to the intense reaction with oxygen in the arc during welding, resulting in poor welding workability. For this reason, content of Mg shall be 0.05-0.8%.

  In addition, Mg is added from Mg metal like Al-Mg other than metal Mg in a flux.

[TiO ₂ converted value of Ti oxides: 3-8%]

The Ti oxide contributes to arc stabilization during welding, and also has an effect of becoming a welding slag, improving the shape of the weld bead, and improving welding workability. In particular, in vertical welding, the inclusion of Ti oxide in the welding slag has the effect of adjusting the viscosity and melting point of the molten slag and preventing the molten metal from dripping. In addition, a part of the fine Ti oxide remains in the weld metal and refines the microstructure of the weld metal, thereby improving the toughness of the weld metal. However, if the TiO ₂ conversion value as the main component of the slag forming agent in the Ti oxide is less than 3%, these effects cannot be obtained sufficiently, the arc becomes unstable, the appearance of the weld bead due to increased spatter, Deterioration of the shape and further the toughness of the weld metal decreases. In addition, the molten metal drips in the vertical improvement welding, and it is difficult to continue the welding. On the other hand, if the TiO ₂ conversion value exceeds 8%, the arc is stabilized and the amount of spatter generated is reduced, but the Ti oxide remains excessively in the weld metal and the toughness decreases. Therefore, the content of Ti oxide, and 3-8% in terms of TiO ₂ value.

  The Ti oxide is added from rutile, titanium oxide, titanium slag, ilmenite or the like in the flux.

[Si oxide converted to SiO ₂ : 0.1 to 1.0%]

Si oxide has the effect of improving the slag encapsulation by adjusting the viscosity and melting point of the molten slag. However, this effect cannot be sufficiently obtained when the total of SiO ₂ conversion values as the main component in improving the slag encapsulation in Si oxide is less than 0.1%. On the other hand, if the SiO ₂ conversion value exceeds 1.0%, the basicity of the molten slag decreases, the oxygen content of the weld metal increases, and the toughness decreases. For this reason, the content of Si oxide is 0.1 to 1.0% in terms of SiO ₂ .

  Si oxide is added from silica sand, zircon sand or the like in the flux.

[Al ₂ O ₃ converted value of Al oxide: 0.05 to 1.2%]

The Al oxide becomes an Al oxide in the welding slag at the time of welding, and adjusts the viscosity and melting point of the welding slag, and has an effect of preventing the molten metal from dripping particularly in the vertical improvement welding. If the Al ₂ O ₃ conversion value as a main component for preventing dripping of molten metal in the Al oxide is less than 0.05%, this effect cannot be sufficiently obtained. On the other hand, if the Al ₂ O ₃ conversion value exceeds 1.2%, the Al oxide cannot be levitated and separated from the molten pool at the time of welding, and is left behind and slag is involved. Therefore, the content of Al oxide, and 0.05 to 1.2 percent terms of Al ₂ O ₃ value.

[Apparent density of Al oxide: 1.4 to 2.5 g / cm ³ , Average particle diameter of Al oxide: 20 to 200 μm]

In addition, as a result of various studies on various oxides containing Al, the inventors have found that when the apparent density of the Al oxide is less than 1.4 g / cm ³ and the average particle diameter of the Al oxide is less than 20 μm, It has been found that the arc in improved welding becomes thinner, the weld bead becomes thinner and the bead becomes convex.

On the other hand, although no adverse effect on welding workability was found with respect to the upper limit of the apparent density, it is very difficult to produce an Al oxide raw material exceeding 2.5 g / cm ³ and the production cost is increased. When the average particle diameter of the Al oxide exceeds 200 μm, breakage is likely to occur during wire drawing during wire production, and spatter during welding increases. For this reason, the apparent density of the Al oxide is 1.4 to 2.5 g / cm ^3, and the average particle diameter of the Al oxide is 20 to 200 μm.

  The Al oxide is added from Al oxide in the flux, a composite oxide of Al and Si, or the like. The apparent density was measured in accordance with JIS Z 2504 “Method for measuring apparent density of metal powder”. The average particle diameter is the same mass as the mass percentage of the sieve classification product of each particle size obtained by JIS Z 2510 “Metal powder-particle size test method by dry sieving”, integrated from the mass percentage of the sieve classification product having a small particle size. It was set as the particle size when the percentage reached 50%.

[Total of Na conversion value and K conversion value of Na compound and K compound: 0.01 to 0.4%]

  The Na compound and the K compound are added as an arc stabilizer or a slag forming agent as an oxide or fluoride. If the total of Na converted value and K converted value of Na compound and K compound is less than 0.01%, the effect cannot be obtained sufficiently, and if it exceeds 0.4%, the viscosity of molten slag during welding decreases. As a result, the molten metal drips down. For this reason, the total of Na conversion value and K conversion value of Na compound and K compound shall be 0.01 to 0.4%.

The Na compound and K compound are added from potassium feldspar, soda feldspar, NaF, KF, K ₂ SiF ₆ , AlF _{3 and the} like in the flux.

[F conversion value of metal fluoride: 0.005 to 0.2%]

  Metal fluoride has the effect of increasing the directivity of the arc to a stable molten state, but this effect cannot be sufficiently obtained when the F-converted value of metal fluoride is less than 0.005%. If the F-converted value of the metal fluoride exceeds 0.2%, the arc becomes unstable and a lot of spatter occurs. In addition, molten metal sag is likely to occur during vertical welding. For this reason, F conversion value of a metal fluoride shall be 0.005-0.2%.

The metal fluoride is added from CaF ₂ , NaF, KF, LiF, MgF ₂ , K ₂ SiF ₆ , AlF ₃ or the like in the flux.

[P: 0.03% or less]

  P decreases the toughness of the weld metal and increases the hot cracking susceptibility, but is acceptable if the content is 0.03% or less.

[S: 0.03% or less]

  S, like P, decreases the toughness of the weld metal and increases the hot cracking susceptibility, so it is made 0.03% or less.

[Ni: 0.05 to 0.8%]

  Ni is an element that improves the weather resistance of the weld metal. However, according to JIS Z 3320, Ni is not an essential element depending on the application. That is, in JIS Z 3320, the amount of Ni in the weld metal is defined for each of the P type and the W type. Ni is not essential in the former, Ni is essential in the latter, and the range is 0 for the weld metal. 0.05 to 0.70%. For this reason, the lower limit of the addition amount of Ni is set to 0.05%, which is the lower limit of the W type weld metal. The upper limit is set to 0.8%, which is higher than the upper limit of 0.70% of JIS in consideration of a decrease in the rate of transition to weld metal due to dilution of the base metal.

  In addition, Ni is added from the steel outer skin or the metal Ni, Fe—Ni, Ni—Mg, or the like in the flux.

[Total of ZrO ₂ converted values of metal Zr and Zr oxide: 0.1 to 1.0%]

The metal Zr and the Zr oxide become a weld slag as a Zr oxide during welding to adjust the viscosity and melting point of the weld slag, and have an effect of preventing the molten metal from dripping particularly in the vertical improvement welding. However, if the total of the ZrO ₂ conversion values of the metal Zr and the Zr oxide is less than 0.1%, this effect cannot be obtained sufficiently. On the other hand, if the sum of the metal Zr and ZrO ₂ conversion values exceeds 1.0%, the peelability of the weld slag becomes poor. Therefore, if the inclusion of metallic Zr and Zr oxide, the content thereof is 0.1 to 1.0% in total of ZrO ₂ equivalent.

  The Zr oxide is added from zirconium oxide, zircon sand or the like in the flux.

[Al: 0.05 to 0.6%]

  Al becomes a welding slag as an Al oxide during welding and adjusts the viscosity and melting point of the welding slag, and has an effect of preventing the molten metal from dripping particularly in the vertical improvement welding. However, if Al is less than 0.05%, this effect cannot be obtained sufficiently. On the other hand, if Al exceeds 0.6%, the Al oxide remains excessively in the weld metal and the toughness of the weld metal decreases. For this reason, the content of Al is set to 0.05 to 0.6%.

  Note that Al is added from a steel outer sheath or metal Al, Fe—Al, Al—Mg, or the like in the flux.

[B: 0.0005 to 0.01%]

  B has an effect of refining the microstructure of the weld metal by adding a small amount and improving the toughness of the weld metal. However, if the B content is less than 0.0005%, this effect cannot be sufficiently obtained. On the other hand, when the B content exceeds 0.01%, the weld metal is excessively hardened and the toughness is lowered, and hot cracks are likely to occur in the weld metal. For this reason, the content of B is set to 0.0005 to 0.01%.

  In addition, B is added from Fe-B, Fe-Mn-B, etc. in a steel outer shell or a flux.

[Mo: 0.05 to 0.3%]

  Mo is added to increase the strength of the weld metal. However, when the Mo content is less than 0.05%, this effect cannot be sufficiently obtained. On the other hand, if the Mo content exceeds 0.3%, the strength of the weld metal becomes too high and the toughness decreases. For this reason, when Mo is contained, the content is set to 0.05 to 0.3%.

  Mo is added from metal Mo, Fe-Mo, or the like in the flux.

[V: 0.02 to 0.2%]

  V is also added to increase the strength of the weld metal. However, when the V content is less than 0.02%, this effect cannot be sufficiently obtained. On the other hand, if the V content exceeds 0.2%, the strength of the weld metal becomes too high and the toughness is lowered. For this reason, when it contains V, the content shall be 0.02-0.2%.

  Note that V is added from a steel outer sheath, metal V in the flux, Fe-V, or the like.

[Nb: 0.02 to 0.2%]

  Nb is also added to increase the strength of the weld metal. However, if the Nb content is less than 0.02%, this effect cannot be sufficiently obtained. On the other hand, if the Nb content exceeds 0.2%, the strength of the weld metal becomes too high and the toughness decreases. For this reason, when it contains Nb, the content shall be 0.02-0.2%. Nb is added from metal Nb, Fe—Nb, etc. in the flux.

  Incidentally, among the components described above, Ni, Al, and B exhibit the desired effects of the present invention even if they are not necessarily included in the range of the components described above. Therefore, even if Ni, Al, and B deviate from the above-described component ranges, they are treated as examples of the present invention.

  Note that the flux-cored wire for gas shielded arc welding for weathering steel according to the present invention has a structure in which a steel outer shell is formed into a pipe shape and the inside is filled with flux. As for the types of wires, there are two types of wires: a seamless wire in the steel skin obtained by welding the seam of the molded steel skin, and a seam in the steel skin that is left unwelded in the steel skin. It can be roughly divided into wires. In the present invention, a wire having any cross-sectional structure may be adopted. However, a wire with a seamless steel outer sheath can be heat-treated at 500 to 1000 ° C. for the purpose of reducing the amount of moisture in the wire, and since there is no moisture absorption of the flux after manufacture, Since the amount of diffusible hydrogen can be reduced and the cold cracking resistance can be improved, it is preferable to use a wire having no seam in the steel outer sheath.

  The remainder of the flux-cored wire for gas shielded arc welding for weathering steel of the present invention is Fe of steel outer sheath, Fe of iron alloy powder such as Fe powder, Fe-Mn, Fe-Si alloy added for component adjustment. Minute and inevitable impurities. The flux filling rate is not particularly limited, but is preferably 8 to 20% with respect to the total mass of the wire from the viewpoint of productivity.

  Next, examples of the flux-cored wire for gas shielded arc welding for weathering steel to which the present invention is applied will be described in detail.

  First, flux cored wires having various component compositions shown in Table 1 were made using SPCC defined in JIS G 3141 as a steel outer sheath. The wire diameter was 1.2 mm.

  In Table 1, components whose wire composition is outside the range defined in the present invention are underlined.

  Using a flux-cored wire shown in Table 1, a 12 mm thick steel plate (JIS G 3114 SMA 490BW) was used as a T-shaped fillet weld specimen, and the horizontal and vertical improvements were made under the welding workability evaluation conditions shown in Table 2. Welding workability evaluation by welding was performed.

  Further, in accordance with JIS Z 3320, a weld metal test was conducted under the welding conditions shown in Table 2 using a steel plate (JIS G 3114 SMA 490BW) having a thickness of 20 mm as a test body.

  Evaluation of welding workability by horizontal fillet welding and vertical improvement welding is as follows: arc stability when semi-automatic MAG welding, spatter generation state, fume generation state, peelability of generated slag, bead shape, bead appearance and The state of dripping of molten metal was investigated.

  In the weld metal test, samples for a tensile test and an impact test (conforming to JIS Z3111) were collected from the central portion in the plate thickness direction of the weld metal and used for each test. In the evaluation of the mechanical properties in the weld metal test, the absorbed energy (vE0) at 0 ° C. was 47 J or more, and the tensile strength (TS) was 490 MPa or more. These results are summarized in Table 3.

  In Table 3, those whose mechanical properties are outside the above-described range are underlined.

The wire symbols 1 to 17 in Tables 1 and 3 are examples of the present invention, and the wire symbols 18 to 30 are comparative examples. Incidentally, in Table 1, even if it is not necessarily included in the range of the component mentioned above among Ni, Al, and B among the wire components, the desired effect of the present invention is exhibited. Therefore, even if Ni, Al, and B deviate from the above-described component ranges, they are included in the examples of the present invention. Since the composition of each component is within the range specified in the present invention, the wire symbols 1 to 17 as examples of the present invention have good tensile strength and absorbed energy values of the weld metal, welding workability and production The results were very satisfactory. Note that the total of ZrO ₂ converted values of the metal Zr and the Zr oxide cannot be confirmed from the range defined in the present invention, and the wire symbols 3, 6, 13, and 16 in which Al is less than the lower limit defined in the present invention. Some metal dripping occurred during the vertical improvement welding. In addition, in the wire symbols 3, 7, 10, 15 and 17 in which B was added within the range specified in the present invention, the absorbed energy (vE-20) at −20 ° C. exceeded 70 J and was very high.

  In the comparative example, since the wire symbol 18 has an average particle size of Al oxide larger than the range defined in the present invention, wire breakage occurred frequently during wire production. Moreover, since C was less than the range specified in the present invention, the arc was unstable.

Since the wire symbol 19 has more C than the range specified in the present invention, the absorbed energy was low. Further, since the F-converted value of the metal fluoride was less than the range specified in the present invention, the arc was unstable. Furthermore, since the total of the ZrO ₂ conversion values of the metal Zr and the Zr oxide is larger than the range defined in the present invention, the slag peelability on the weld bead was poor.

  Since the wire symbol 20 has less Si than the range defined in the present invention, the appearance and shape of the weld bead were poor. Moreover, since B is more than the range prescribed | regulated in this invention, the hot crack generate | occur | produced in the weld bead and the absorbed energy of the deposit metal was a low value.

  Since the wire symbol 21 has more Si than the range defined in the present invention, the absorbed energy was low. Further, since the total of Na converted values and K converted values of the Na compound and K compound is larger than the range defined in the present invention, it is difficult to continue welding because the metal drips down in the vertical improvement welding.

  The wire symbol 22 had poor bead appearance and shape because Mn was less than the range defined in the present invention. Further, since the apparent density of the Al oxide is higher than the range specified in the present invention, the manufacturing cost is increased.

In the wire symbol 23, since Mn is larger than the range defined in the present invention, the tensile strength of the weld metal is high and the absorbed energy is low. Moreover, since the Al ₂ O ₃ converted value of the Al oxide is larger than the range defined in the present invention, slag entrainment occurred.

In the wire symbol 24, the SiO ₂ equivalent value of the Si oxide is larger than the range defined in the present invention, so the absorbed energy of the weld metal was low. Moreover, since the total of Na conversion value and K conversion value of Na compound and K compound was less than the range prescribed | regulated in this invention, the arc was unstable.

In the wire symbol 25, since the Al ₂ O ₃ equivalent value of the Al oxide is less than the range defined in the present invention, it is difficult to continue the welding due to dripping of the molten metal in the vertical improvement welding. Moreover, since Mg is less than the range prescribed | regulated in this invention, the absorbed energy of the deposit metal was a low value.

In the wire symbol 26, since the TiO ₂ converted value of the Ti oxide is less than the range defined in the present invention, the arc is unstable and the amount of spatter generated is large. Further, the bead appearance and shape are poor, and in the vertical improvement welding, the molten metal drips down and it is difficult to continue the welding. Furthermore, the absorbed energy of the weld metal was low.

  In the wire symbol 27, the F-converted value of the metal fluoride is larger than the range specified in the present invention, so that the arc is unstable and the amount of spatter is large, and the molten metal drips down in the vertical welding, making it difficult to continue welding. Met. Further, since B is less than the range defined in the present invention, a high value could not be obtained with the absorbed energy of the weld metal at −20 ° C.

In the wire symbol 28, since the TiO ₂ converted value of the Ti oxide is larger than the range defined in the present invention, the absorbed energy of the deposited metal was low. Further, since the apparent density of the Al oxide is lower than the range defined in the present invention, the weld bead in the vertical improvement welding has a convex shape. Furthermore, since the total of the ZrO ₂ converted values of metal Zr and Zr oxide and Al are less than the range defined in the present invention, the molten metal dripped slightly in the vertical improvement welding.

In the wire symbol 29, since the average particle diameter of the Al oxide is smaller than the range defined in the present invention, the weld bead has a convex shape. Further, SiO ₂ conversion value of Si oxide is because less than the range specified in the present invention, horizontal corner poor bead appearance is encapsulated in the slag in the weld was poor.

  Since the wire symbol 30 has more Mg than the range defined in the present invention, the amount of spatter and fumes generated was large. Moreover, since Al is higher than the range prescribed | regulated by this invention, the absorbed energy of the deposit metal was a low value.

  Next, the effect of the present invention will be specifically described with reference to Example 2. In the second embodiment, only conditions different from the first embodiment will be described. In Example 2, flux-cored wires having various component compositions shown in Tables 4 and 5 below were made as trial products.

  Using the flux-cored wires shown in Tables 4 and 5, a welding workability evaluation by horizontal and vertical improvement welding under the same conditions as in Example 1 and a weld metal test were performed.

  In the evaluation of the mechanical properties in the weld metal test, the absorbed energy (vE0) at 0 ° C. of the weld metal was 47 J or more and the tensile strength (TS) was 570 MPa or more. These results are summarized in Table 6.

  In Tables 4 and 5, components whose wire composition is outside the range defined in the present invention are underlined. In Table 6, those whose mechanical properties are outside the above-described range are underlined.

  The wire symbols 31 to 35 in Tables 4 to 6 are examples of the present invention, and the wire symbols 36 to 41 are comparative examples. Incidentally, in Tables 4-6, even if it is not necessarily contained in the range of the component mentioned above among Al, B, Mo, Nb, and V among wire components, there exists an effect of the effect of the present invention. Therefore, even if Al, B, Mo, Nb, and V deviate from the above-described component ranges, they are included in the examples of the present invention. Since the composition of each component is within the range specified in the present invention, the wire symbols 31 to 35 as examples of the present invention show good welding workability, and the tensile strength and absorbed energy of the deposited metal are also good values. The result was extremely satisfactory.

  Since the wire symbols 36 and 38 and the wire symbol 40 had more Mo, Nb, and V than the ranges specified in the present invention, the tensile strength was high and the absorbed energy was low.

  Since the wire symbols 37 and 39 and the wire symbol 41 had less Mo, Nb, and V than the range prescribed | regulated in this invention, tensile strength was a low value.

Claims (5)

In the flux-cored wire for gas shielded arc welding for weathering steel, which is formed by filling the steel outer shell with flux,
% By mass relative to the total mass of the wire
C: 0.01 to 0.08%,
Si: 0.1 to 1.0%,
Mn: 1.0 to 3.0%
Cu: 0.2 to 0.7%,
Cr: 0.3-0.9%
Mg: 0.05-0.8%,
TiO ₂ conversion value of Ti oxide: 3 to 8%,
SiO ₂ conversion value of Si oxide: 0.1 to 1.0%,
Terms of Al ₂ O ₃ value of Al oxide: 0.05 to 1.2%,
Total of Na converted value and K converted value of Na compound and K compound: 0.01 to 0.4%,
F conversion value of metal fluoride: 0.005 to 0.2%,
P: 0.03% or less,
S: 0.03% or less,
The balance consists of Fe of steel hull, iron powder, Fe content of iron alloy powder and inevitable impurities,
The Al oxide has an apparent density of 1.4 to 2.5 g / cm ³ and an average particle size of 20 to 200 μm. A flux-cored wire for weather-resistant steel for gas shielded arc welding.   The flux-cored wire for gas shielded arc welding for weathering steel according to claim 1, wherein Ni is contained in an amount of 0.05 to 0.8% by mass with respect to the total mass of the wire. The total amount of metal Zr and Zr oxide in terms of ZrO _{2 in} terms of mass% relative to the total mass of the wire: 0.1 to 1%, Al: one or two of 0.05 to 0.6%. The flux-cored wire for gas shielded arc welding for weathering steel according to claim 1 or 2, characterized by the above.   The gas-shield arc welding for weathering steel according to any one of claims 1 to 3, wherein B: 0.0005 to 0.01% by mass with respect to the total mass of the wire. Flux-cored wire.   Containing one or more of Mo: 0.05 to 0.3%, V: 0.02 to 0.2%, and Nb: 0.02 to 0.2% in mass% with respect to the total mass of the wire. The flux-cored wire for gas shielded arc welding for weathering steel according to any one of claims 1 to 4, characterized in that