WO2022030159A1 - Welding flux and production method therefor, and submerged arc welding method using same welding flux - Google Patents

Welding flux and production method therefor, and submerged arc welding method using same welding flux Download PDF

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Publication number
WO2022030159A1
WO2022030159A1 PCT/JP2021/025376 JP2021025376W WO2022030159A1 WO 2022030159 A1 WO2022030159 A1 WO 2022030159A1 JP 2021025376 W JP2021025376 W JP 2021025376W WO 2022030159 A1 WO2022030159 A1 WO 2022030159A1
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mass
raw material
powder raw
flux
oxide
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PCT/JP2021/025376
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French (fr)
Japanese (ja)
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大祐 鳩本
統宣 佐藤
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株式会社神戸製鋼所
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
    • B23K35/362—Selection of compositions of fluxes

Definitions

  • the present invention relates to a welding flux having excellent moisture absorption resistance and a method for producing the same, and a submerged arc welding method using the welding flux.
  • Examples of welding methods to which welding flux is applied generally include submerged arc welding and electroslag welding.
  • submerged arc welding is a welding method used for pipe making welding for pipelines that transport petroleum, natural gas, and the like.
  • the flux designed for this submerged arc welding has a property that when it is left in a high temperature and high humidity atmosphere, moisture is adsorbed inside or on the surface of the pores of the flux particles and it is easy to absorb moisture.
  • the water adsorbed on the particles decomposes into hydrogen and oxygen, which increases the amount of diffusible hydrogen in the weld metal, causes low-temperature cracking, and adversely affects welding workability. Therefore, in submerged arc welding, improving the moisture absorption resistance of the welding flux is mentioned as one of the extremely important issues.
  • Patent Document 1 describes at least one of Al 2 O 3 , SiO 2 , MgO, CaF 2 converted value, Mn O converted value, Na 2 O converted value, K 2 O converted value and Li 2 O converted value in the flux.
  • Submerged arc that appropriately adjusts the content of one or more total, FeO conversion value, CaO, water-soluble SiO 2 , water-soluble Na 2 O, and water-soluble K 2 O, and limits the values obtained by a predetermined formula.
  • Welding flux has been proposed.
  • Patent Document 2 discloses a flux for submerged arc welding in which the contents of the oxide and TiO 2 in the flux and the values obtained by a predetermined mathematical formula are limited.
  • Patent Documents 1 and 2 describe that it is possible to reduce the amount of moisture absorbed by the flux and the amount of diffusible hydrogen in the weld metal.
  • the amount of moisture absorbed is evaluated by performing forced moisture absorption for 2 hours after re-drying the flux and measuring the amount of water contained in the flux.
  • the present invention has been made in view of the above problems, and excellent moisture absorption resistance can be obtained even when the weld metal is left for a long time, which is one of the causes of cracking of the weld metal. It is an object of the present invention to provide a welding flux capable of reducing the amount of diffusible hydrogen in a weld metal, a method for producing the same, and a submerged arc welding method using the welding flux.
  • the present inventors focused on oxides containing Si contained in welding flux. That is, since the particles containing the oxide containing Si are extremely easy to absorb moisture, the present inventors have improved the moisture absorption resistance of the flux by forming a compound layer having high moisture absorption resistance on the surface of the particles. , Found that the amount of diffusible hydrogen in the weld metal can be reduced.
  • the flux for welding may be simply referred to as flux.
  • the welding flux has particles containing oxides and has particles.
  • the oxide contains Si and contains A compound layer is formed on at least a part of the outer surface of the particles.
  • the compound layer contains a strongly deoxidizing element constituting an oxide having a standard produced Gibbs energy lower than the SiO 2 standard produced Gibbs energy in the temperature range of 500 to 1000 ° C. in the Ellingham diagram.
  • a preferred embodiment of the present invention relating to a welding flux relates to the following [2] to [5].
  • the strongly deoxidizing element is Ellingham The element for welding according to [1], which is an element constituting an oxide having an oxide standard production Gibbs energy value of ⁇ 800 kJ / g ⁇ molO 2 or less in the entire temperature range of 500 to 1000 ° C. in the figure. flux.
  • the oxide containing Si is an oxide of Si alone or a composite oxide containing at least one selected from K, Na and Al and Si, [1] to [3].
  • the welding flux according to any one.
  • TiO 2 conversion value of all Ti 0.5% by mass or more, 5.0% by mass or less, MnO conversion value of all Mn: 0.5% by mass or more, 13.0% by mass or less, and FeO conversion value of all Fe: 0.5% by mass or more, 7.0% by mass or less, As well as containing At least one selected from Mg, Ca and Ba, MgO conversion value of all Mg: 15.0% by mass or more, 30.0% by mass or less, CaO conversion value of all Ca: 7.0% by mass or more, 30.0% by mass or less, BaO conversion value of all Ba: 8.0% by mass or less, The welding flux according to any one of [1] to [4], which is contained in the range of.
  • the method for producing a welding flux according to any one of [1] to [5]. It has a step of adding a binder to a blending flux containing a powder raw material, granulating, and then firing at a temperature of 500 to 1000 ° C.
  • the compounded flux contains, as the powder raw material, a powder raw material of an oxide containing Si, and a powder raw material of a metal containing a strongly deoxidizing element or a powder raw material of a compound.
  • the method for producing a welding flux, wherein the strongly deoxidizing element is an element constituting an oxide having a standard enthalpy of formation lower than SiO 2 in the temperature range of 500 to 1000 ° C. in the Ellingham diagram.
  • a preferred embodiment of the present invention relating to a method for producing a flux for welding relates to the following [7].
  • the powder raw material of the metal containing the strongly deoxidizing element or the powder raw material of the compound is at least one selected from the powder raw material containing Mg, the powder raw material containing Ca and the powder raw material containing Ba.
  • Contains powder raw material The powder raw material containing Mg contains 25% by mass or more of Mg with respect to the total mass of the powder raw material containing Mg.
  • the powder raw material containing Ca contains 30% by mass or more of Ca with respect to the total mass of the powder raw material containing Ca.
  • the powder raw material containing Ba contains 60% by mass or more of Ba with respect to the total mass of the powder raw material containing Ba.
  • the ratio of the powder raw material containing Mg having a particle size of 75 ⁇ m or less to the total mass of the powder raw material containing Mg is [a].
  • the ratio of the powder raw material containing Ca having a particle size of 75 ⁇ m or less to the total mass of the powder raw material containing Ca is [b].
  • the ratio of the powder raw material containing Ba having a particle size of 75 ⁇ m or less to the total mass of the powder raw material containing Ba is [c].
  • the ratio of the powder raw material of the oxide containing Si having a particle size of 75 ⁇ m or less to the powder raw material of the oxide containing Si is determined by mass% with respect to the total amount of the powder raw material of the oxide containing Si [d]. ]
  • the present invention excellent moisture absorption resistance can be obtained even when the product is left for a long time, whereby the amount of diffusible hydrogen in the weld metal, which is one of the causes of cracking of the weld metal, can be reduced. It is possible to provide a welding flux that can be reduced, a method for producing the same, and a submerged arc welding method using the welding flux.
  • FIG. 1 is an example of an SEM photograph taken of a cross section of the welding flux obtained by the present embodiment.
  • the present invention is not limited to the embodiments described below. Further, in the present specification, "-" indicating a numerical range is used to mean that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.
  • the welding flux in the present invention include a flux for submerged arc welding and a flux for electroslag welding.
  • the flux for submerged arc welding will be described as an example of the flux for welding, but the present invention is not limited to the flux for submerged welding.
  • the welding flux according to the present embodiment has particles containing an oxide, the oxide contains Si, and a compound layer is formed on at least a part of the outer surface of the particles, and the compound layer is an eringham.
  • the above compound layer is formed on 50% or more of the outer surface containing a strongly deoxidizing element constituting an oxide having a standard production Gibbs energy lower than the SiO 2 standard production Gibbs energy.
  • the particles are present at a ratio of 50% or more with respect to the total number of particles containing the oxide containing Si.
  • Oxides containing Si are widely used as a powder raw material for producing a flux for welding, mainly because the appearance and shape of the bead are improved by imparting an appropriate viscosity to the molten slag.
  • the particles containing an oxide containing Si are extremely easy to absorb moisture, they have a characteristic of containing a large amount of water. Therefore, if a compound layer having high moisture absorption resistance, which will be described later, is formed on the outer surface of the particles containing an oxide containing Si, the moisture absorption resistance of the flux can be improved, whereby the moisture absorption resistance of the flux can be improved.
  • the amount of diffusible hydrogen can be reduced.
  • the oxide containing Si examples include an oxide of Si alone or a composite oxide containing at least one selected from K, Na and Al and Si, and these have characteristics that are particularly easy to absorb moisture. Therefore, the effect of the present invention can be expected. Further, among the oxides containing Si, the composite oxide containing Si and at least one selected from K, Na and Al has the property of being more easily absorbed by moisture, so that the effect of the present invention can be expected more. .. Specific examples of the composite oxide include KAlSi 3 O 8 , NaAlSi 3 O 8 , CaAl 2 Si 2 O 8 , and the like.
  • the compound layer contains a strongly deoxidizing element constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard produced Gibbs energy in the temperature range of 500 to 1000 ° C. in the Ellingham diagram.
  • This compound layer is, for example, a metal powder raw material containing a strongly deoxidizing element having a high affinity for oxygen or a compound powder raw material, an oxide powder raw material containing Si, and a binder such as water glass. It can be produced by granulating the flux using the above and baking it at a predetermined temperature.
  • the compound layer does not have to be formed on the outer surface of all the particles containing the oxide containing Si, nor does it need to be formed on the entire outer surface of the particles.
  • the amount of particles in which the compound layer is formed on 50% or more of the outer surface of the particles containing the oxide containing Si is 50% or more of the total number of particles of the particles containing the oxide. It suffices if it exists in proportion.
  • the ratio of the particles in which the compound layer is formed on 50% or more of the outer surface of the particles containing the oxide containing Si is preferably 60% or more with respect to the total number of particles containing the oxide. Yes, more preferably 65% or more, still more preferably 75% or more.
  • the outer surface of the particle referred to here refers to the circumference of the cross section of the particle, which is determined by observing the cross section of the particle.
  • the powder raw material of an oxide containing Si means a raw material containing particles containing an oxide containing Si.
  • the strongly deoxidizing element refers to an element constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy, and examples thereof include Ti, Ce, Al, Zr, Ba, Ca and Mg. ..
  • the particles of the metal or compound containing a strongly deoxidizing element come into contact with the outer surface of the particles containing an oxide containing Si to form Si with the particles of the metal or compound containing a strongly deoxidizing element. It is considered that the particles containing the oxide contained are produced by an interfacial reaction due to the heat at the time of firing in the flux manufacturing process.
  • a metal containing a strongly deoxidizing element constituting an oxide having a standard production Gibbs energy lower than the SiO 2 standard production Gibbs energy within the firing temperature range in the flux manufacturing process It is necessary to use the powder raw material of the above or the powder raw material of the compound as the powder raw material of the compounding flux.
  • the elements constituting the oxide having a standard generated Gibbs energy value of ⁇ 800 kJ / g ⁇ molO 2 or less in the entire temperature range of 500 to 1000 ° C. in the Ellingham diagram are adopted. Then, the difference from the SiO 2 standard generated Gibbs energy becomes large, and the compound layer is more easily formed, which is preferable.
  • the elements constituting the oxide having a standard generated Gibbs energy value of ⁇ 800 kJ / g ⁇ molO 2 or less in the entire temperature range of 500 to 1000 ° C. include Al, Zr, Ba, Ca and Mg.
  • the strongly deoxidizing element it is more preferable to select at least one element selected from Mg, Ca and Ba, and when a powder raw material of a metal or compound containing these strongly deoxidizing elements is used, Si A compound layer having high moisture absorption resistance is produced by contacting with the outer surface of particles containing an oxide containing an oxide and undergoing an interfacial reaction due to the heat during firing in the flux manufacturing process.
  • the content in the present embodiment means mass% with respect to the total mass of the flux unless otherwise specified.
  • the flux content has a component specified by a converted value due to the restrictions of the analysis method. Therefore, the total content of each component with respect to the total mass of the flux may exceed 100% by mass due to the property of using the converted value.
  • Total F amount 5.0% by mass or more and 20.0% by mass or less
  • Fluoride has the effect of increasing the electrical conductivity and fluidity of the molten slag, and also contributes to welding workability because it is one of the components that affect the high temperature viscosity of the molten slag.
  • the partial pressure of water vapor in the arc atmosphere can be reduced and the amount of diffusible hydrogen in the weld metal can be reduced by the decomposition reaction of fluoride during arc welding.
  • the content of fluoride with respect to the total mass of the flux is defined by the mass% of F (also referred to as the total amount of F) with respect to the total mass of the flux.
  • the total F amount is preferably 5.0% by mass or more. It is more preferably 0.0% by mass or more, and further preferably 12.0% by mass or more.
  • the total F amount is preferably 20.0% by mass or less, and 18.0% by mass or less. It is more preferably 17.0% by mass or less, and further preferably 17.0% by mass or less.
  • the F source in the flux of the present embodiment mainly includes CaF 2 , and may also contain BaF 2 , AlF 3 , MgF 2 , etc. However, if the total F amount is within the above range, the above-mentioned There is no change in the effect of fluoride.
  • SiO 2 conversion value of all Si 10.0% by mass or more, 25.0% by mass or less
  • the oxide containing Si mainly improves the bead appearance and the bead shape by imparting an appropriate viscosity to the molten slag.
  • Si in alloys such as metallic Si and Fe—Si acts as a reducing agent, prevents deterioration of mechanical properties due to an increase in the amount of oxygen in the weld metal, and suppresses the generation of pock marks.
  • the content of Si with respect to the total mass of the flux is defined by the value converted to SiO 2 in which the total amount of Si in the flux is converted to SiO 2 .
  • the SiO 2 conversion value is preferably 10.0% by mass or more, and more preferably 11.0% by mass or more.
  • the SiO 2 conversion value is preferably 25.0% by mass or less, and more preferably 20.0% by mass or less.
  • the SiO 2 conversion value specified here includes the SiO 2 conversion value of Si derived from a binder such as water glass, in addition to the above-mentioned Si-containing oxides, metal Si, and alloys such as Fe—Si. included.
  • Al is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing Al to the flux, a compound layer containing Al is formed on the outer surface of the particles containing the oxide containing Si, thereby improving the moisture absorption resistance of the flux. It can be improved and the amount of diffusible hydrogen in the weld metal can be reduced.
  • the Al content with respect to the total mass of the flux is defined by the Al 2 O 3 conversion value obtained by converting the total Al content in the flux into Al 2 O 3 .
  • the Al 2 O 3 conversion value is preferably 14.0% by mass or more. Further, it is preferably 30.0% by mass or less.
  • the powder raw material containing Al for example, it can be added in the form of an alloy such as Al 2 O 3 , Al F 3 , metal Al and Al—Mg.
  • Al 2 O 3 greatly contributes to the improvement of slag peelability and low temperature toughness, and is a component that improves the bead shape and bead appearance at the time of welding. Therefore, it can be added in the form of Al 2 O 3 . preferable.
  • the Al 2 O 3 conversion value is more preferably 16.0% by mass or more because a good bead shape and bead appearance can be obtained.
  • the Al 2 O 3 conversion value is more preferably 27.0% by mass or less because it can prevent the melting point of the molten slag from rising excessively and maintain good slag peelability at the bead end. ..
  • the alkali metals Na and K are components that mainly affect the arc stability during welding and the moisture absorption characteristics of the flux. From the viewpoint of arc stability during welding, it is preferable that the flux contains either or both of Na and K.
  • the contents of Na and K with respect to the total mass of the flux are defined by the Na 2 O conversion value and the K 2 O conversion value obtained by converting the total Na and total K amounts in the flux into Na 2 O and K 2 O, respectively.
  • the total of the Na 2 O conversion value and the K 2 O conversion value is preferably 1.0% by mass or more, and more preferably 1.5% by mass or more.
  • the total of the Na 2 O conversion value and the K 2 O conversion value is preferably 6.0% by mass or less, and more preferably 5.0% by mass or less. preferable.
  • a powder raw material containing Na and K for example, it can be added in the form of an oxide such as Na 2 O, K 2 O, KAlSi 3 O 8 , NaAlSi 3 O 8 , CaAl 2 Si 2 O 8 , etc.
  • the Na 2 O conversion value and the K 2 O conversion value specified here include the Na 2 O conversion of Na and K derived from a binder such as water glass in addition to the above-mentioned oxide containing Na and K. Values and K2O conversion values are also included.
  • Ti is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing Ti to the flux, a compound layer containing Ti is formed on the outer surface of the particles containing the oxide containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced.
  • the content of Ti with respect to the total mass of the flux is defined by the value converted to TiO 2 in which the total amount of Ti in the flux is converted to TiO 2 .
  • the TiO 2 conversion value is preferably 0.5% by mass or more. Further, it is preferably 5.0% by mass or less.
  • the powder raw material containing Ti for example, it can be added in the form of an alloy such as TiO 2 , metal Ti, or Fe—Ti.
  • TiO 2 is a component that can improve the peelability and low temperature toughness of slag, and is a component that improves the bead shape and bead appearance at the time of welding. Therefore, it should be added in the form of TiO 2 . Is preferable. It is more preferable that the TiO 2 conversion value is 1.0% by mass or more because a good bead shape and bead appearance can be obtained. On the other hand, the TiO 2 conversion value is more preferably 4.0% by mass or less because it can prevent the melting point of the molten slag from rising excessively and maintain good slag peelability at the bead end.
  • MnO conversion value of all Mn 0.5% by mass or more and 13.0% by mass or less
  • Mn affects the viscosity and solidification temperature of the molten slag, and is effective in improving the pockmark resistance. Further, when Mn is contained in an appropriate amount in the flux, good low temperature toughness can be obtained and the occurrence of pore defects can be prevented.
  • the Mn content with respect to the total mass of the flux is defined by the MnO conversion value obtained by converting the total Mn amount in the flux into MnO. In order to obtain the above effect, the MnO conversion value is preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and even more preferably 0.8% by mass or more. preferable.
  • the MnO conversion value is 13.0. It is preferably 5% by mass or less, more preferably 11.0% by mass or less, and further preferably 5.0% by mass or less.
  • a powder raw material containing Mn for example, oxides such as MnO, MnO 2 and Mn 2 O 3 and alloys such as metal Mn and Fe—Si—Mn can be added, but among various forms, in particular. When it is added in the form of an oxide and the MnO conversion value is 0.5% by mass or more and 13.0% by mass or less, the usefulness of Mn is more exhibited, which is more preferable.
  • FeO conversion value of all Fe 0.5% by mass or more, 7.0% by mass or less
  • Fe has the effect of promoting the deoxidation phenomenon and enhancing the pockmark resistance, and can obtain a higher effect particularly when the welding current is direct current (DC).
  • the Fe content with respect to the total mass of the flux is defined by the FeO conversion value obtained by converting the total Fe amount in the flux into FeO.
  • the FeO conversion value is preferably 0.5% by mass or more, and more preferably 1.0% by mass or more.
  • the FeO conversion value is preferably 7.0% by mass or less, and preferably 4.0% by mass or less. Is more preferable.
  • a powder raw material containing Fe for example, it can be added in the form of an oxide such as FeO, Fe 2 O 3 and Fe 3 O 4 , or an alloy such as metal Fe and Fe—Si, and in particular, Fe—Si and the like.
  • the FeO conversion value is 0.5% by mass or more and 7.0% by mass or less while being added in the form of the alloy or metal Fe of the above, the usefulness of Fe is more exhibited, which is more preferable.
  • the flux of the present embodiment more preferably contains at least one selected from Mg, Ba and Ca as the above-mentioned strongly deoxidizing element in the content shown below in addition to the above-mentioned contained components, preferably Mg and Ca. It is more preferable to contain at least one selected from the above in the content shown below, and it is most preferable to contain both Mg and Ca in the content shown below. The preferred contents of these components will be described below.
  • Mg is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing Mg to the flux, a compound layer containing Mg is formed on the outer surface of the oxide particles containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced.
  • the Mg content with respect to the total mass of the flux is defined by the MgO conversion value obtained by converting the total Mg content in the flux into MgO.
  • the MgO conversion value is preferably 15.0% by mass or more. Further, the MgO conversion value is preferably 30.0% by mass or less.
  • the Mg source converted into MgO include alloys such as MgO, MgF 2 , MgCO 3 , and Al—Mg, and forms such as metallic Mg.
  • the form of MgO is preferable because it is a component that greatly contributes to the improvement of slag peelability. Regardless of the polarity of the electrode, good slag peelability can be ensured and slag seizure can be prevented. Therefore, the MgO conversion value is more preferably 19.0% by mass or more, and 20.0% by mass or more.
  • the MgO conversion value is more preferably 26.0% by mass or less, and 25.0% by mass or less. Is more preferable.
  • CaO conversion value of all Ca: 7.0% by mass or more and 30.0% by mass or less Ca is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard produced Gibbs energy. Therefore, by adding the powder raw material containing CaO to the flux, a compound layer containing Ca is formed on the outer surface of the particles containing the oxide containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced.
  • the Ca content with respect to the total mass of the flux is defined by the CaO conversion value obtained by converting the total Ca content in the flux into CaO.
  • the CaO conversion value is preferably 7.0% by mass or more. Further, the CaO conversion value is preferably 30.0% by mass or less.
  • the Ca source converted into CaO include alloys such as CaO, CaF 2 , CaCO 3 , and Ca—Si, and forms such as metallic Ca.
  • the CaF 2 is a component that greatly contributes to the improvement of slag removability, it is preferable to add it in the form of CaF 2 .
  • the CaO conversion value is more preferably 17.0% by mass or more, and 20.0% by mass. The above is more preferable.
  • the CaO conversion value is more preferably 26.0% by mass or less, more preferably 24.0% by mass, because it prevents the fluidity of the molten slag from becoming excessively high and a good bead appearance and shape can be obtained. % Or less is more preferable.
  • Ba (BaO conversion value of all Ba: 8.0% by mass or less) Ba is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing BaO to the flux, a compound layer containing Ba is formed on the outer surface of the particles containing the oxide containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced.
  • the Ba content with respect to the total mass of the flux is defined by the BaO conversion value obtained by converting the total Ba content of the flux into BaO.
  • the BaO conversion value is preferably 0.1% by mass or more. Further, the BaO conversion value is preferably 8.0% by mass or less.
  • the Ba source converted into BaO include forms such as BaO, BaF 2 , BaCO 3 , and metal Ba.
  • the lower limit of the BaO conversion value is not particularly limited, but Ba is optionally added in order to improve the mechanical properties of the weld metal by increasing the basicity of the slag and increasing the cleanliness of the weld metal. In this case, the BaO conversion value is more preferably 1.0% by mass or more.
  • the BaO conversion value is preferably 6.0% by mass or less in order to prevent the fluidity of the molten slag from becoming excessively high and to obtain a good bead appearance and shape.
  • the total F amount shown above SiO 2 conversion value, Al 2 O 3 conversion value, Na 2 O conversion value, K 2 O conversion value, TiO 2 conversion value, MgO conversion value, CaO conversion value, BaO conversion value.
  • the total of the MnO-converted value and the FeO-converted value is preferably 92% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, from the viewpoint of obtaining good slag peelability and bead shape.
  • the flux of the present embodiment may contain at least one selected from Zr and B, if necessary, in addition to the above-mentioned components. The contents of these elements will be described below.
  • B 2 O 3 conversion value of all B: 0.50 mass% or less B is an effective component for improving the toughness of the weld metal.
  • the content of B with respect to the total mass of the flux is defined by the B 2 O 3 conversion value obtained by converting the total B content in the flux into B 2 O 3 .
  • the lower limit of the B 2 O 3 conversion value is not particularly set, but if the above effect is desired, the B 2 O 3 conversion value is preferably 0.01% by mass or more, and 0.03% by mass or more. Is more preferable.
  • the B2O3 conversion value is preferably 0.50% by mass or less, preferably 0.30% by mass or less. Is more preferable.
  • the powder raw material containing B for example, it can be added in the form of an alloy such as metal B, Fe—B, Fe—Si—B, an oxide of B, or the like.
  • ZrO 2 conversion value of all Zr: 3.0% by mass or less Zr is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing Zr to the flux, a compound layer containing Zr is formed on the outer surface of the particles containing the oxide containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced.
  • Zr affects the viscosity and solidification temperature of molten slag, and is an effective component for obtaining arc stability in high-speed welding, good bead shape and bead appearance, and good slag peeling property.
  • the Zr content with respect to the total mass of the flux is defined by the ZrO 2 conversion value obtained by converting the total Zr amount in the flux into ZrO 2 . Since the powder raw material containing Zr is relatively expensive, no lower limit is set, but if the above effect is desired, the ZrO2 conversion value is preferably 0.01% by mass or more , and 3.0% by mass. % Or less is preferable.
  • a powder raw material containing Zr for example, it can be added in the form of an alloy containing ZrO 2 , ZrSiO 4 and Zr.
  • the flux of this embodiment may contain elements such as Ni, Mo, Cu and Cr in addition to the above-mentioned contained components.
  • Ni, Mo, Cu and Cr are added to the flux, the total value thereof is preferably 5% by mass or less.
  • Examples of elements other than the above contained in the flux include unavoidable impurities such as P, S, Nb and V.
  • unavoidable impurities such as P, S, Nb and V.
  • Nb and V reduce the low temperature toughness of the weld metal, so it is preferable to regulate each to 0.5% by mass or less with respect to the total mass of the flux, and P and S which affect the welding quality. Is preferably regulated to 0.20% by mass or less with respect to the total mass of the flux.
  • the welding flux of the present invention can be obtained by adding a binder to a blended flux containing the following powder raw materials, granulating the flux, and then firing at a temperature of 500 to 1000 ° C.
  • the compounded flux contains, as the powder raw material, a powder raw material of an oxide containing Si, and a powder raw material of a metal containing the above-mentioned strongly deoxidizing element or a powder raw material of a compound.
  • the powder raw material of the metal containing the strongly deoxidizing element or the powder raw material of the compound the powder raw material containing the Mg, the powder raw material containing Ca, the powder raw material containing Ba, and the above-mentioned flux can be used.
  • Examples thereof include a powder raw material of an oxide containing a component, and a powder raw material containing a fluoride or a carbonate.
  • the binder for example, water glass, polyvinyl alcohol and the like can be used.
  • the granulation method is not particularly limited, but a method using a rolling granulation machine, an extrusion type granulation machine, or the like is preferable.
  • the firing after granulation can be performed in a rotary kiln, a stationary batch furnace, a belt-type firing furnace, or the like.
  • a flux raw material containing a strongly deoxidizing element constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard produced Gibbs energy in the temperature range of 500 to 1000 ° C. in the Ellingham diagram.
  • the firing temperature is preferably 500 to 1000 ° C, preferably 700 to 900 ° C.
  • the present inventors have found that a compound layer is likely to be formed on the outer surface of particles containing an oxide containing Si by appropriately defining the particle size of the powder raw material.
  • the particles having a particle size of 75 ⁇ m or less are particularly easy to absorb moisture, and therefore various strong deoxidization agents are used.
  • the mass ratio of the total amount of the powder raw materials having a particle size of 75 ⁇ m or less is 75 ⁇ m or less among the powder raw materials containing Si. It is preferable that it is larger than the mass ratio of a certain powder raw material.
  • particle size of 75 ⁇ m or less means that the particle size passes through the sieve when it is sieved using a sieve with a mesh size of 75 ⁇ m based on JIS Z 8801: 2019 by a method based on JIS Z 8815: 1994. Means that.
  • the metal powder raw material containing the strongly deoxidizing element and the compound powder raw material are at least one kind of powder selected from the powder raw material containing Mg, the powder raw material containing Ca, and the powder raw material containing Ba. It is preferable to contain a body material. Further, the powder raw material containing Mg contains 25% by mass or more of Mg with respect to the total mass of the powder raw material containing Mg, and the powder raw material containing Ca contains Ca with respect to the total mass of the powder raw material containing Ca. 30% by mass or more, and the powder raw material containing Ba is preferably one containing 60% by mass or more of Ba with respect to the total mass of the powder raw material containing Ba.
  • the ratio of the powder raw material containing Mg having a particle size of 75 ⁇ m or less is [a] in mass% with respect to the total mass of the powder raw material containing Mg, and the powder containing Ca is used.
  • the ratio of the powder raw material containing Ca having a particle size of 75 ⁇ m or less to the total mass of the powder raw material containing Ca is [b]
  • the ratio of the powder raw material containing Ba is calculated.
  • [C] is the mass% of the total mass of the powder raw material containing Ba
  • the ratio of the powder raw material containing Si having a particle size of 75 ⁇ m or less among the powder raw materials containing Si is the powder containing Si.
  • the powder raw material containing Mg it is more preferable to use one containing 50% by mass or more of Mg with respect to the total mass of the powder raw material containing Mg, and it is more preferable to use one containing 52% by mass or more.
  • the powder raw material containing such Mg for example, MgO, MgCO 3 , MgF 2 , and the like can be used.
  • the powder raw material containing Ca it is more preferable to use a powder raw material containing 40% by mass or more of Ca with respect to the total mass of the powder raw material containing Ca, and it is further preferable to use a powder raw material containing 45% by mass or more. preferable.
  • the powder raw material containing Ca for example, CaF 2 , CaCO 3 , CaO and the like can be used.
  • the powder raw material containing Ba it is more preferable to use a powder raw material containing 62% by mass or more of Ba with respect to the total mass of the powder raw material containing Ba, and it is further preferable to use a powder raw material containing 65% by mass or more. preferable.
  • the powder raw material containing such Ba for example, BaF 2 , BaCO 3 , BaO and the like can be used.
  • the content of each element with respect to the total mass of the powder raw material including Mg, Ca and Ba will be described.
  • the Mg content is 60% by mass with respect to the total mass of the powder raw material composed only of Mg ⁇ .
  • the Mg content is the total mass of magnesia clinker.
  • the Mg content is the total mass of the powder containing all Mg.
  • the powder raw material of the oxide containing Si for example, SiO 2 , KAlSi 3 O 8 , NaAlSi 3 O 8 , CaAl 2 Si 2 O 8 and the like can be used, and among these, SiO 2 , KAlSi can be used. It is more preferable to use 3 O 8 and NaAlSi 3 O 8 .
  • the present invention also relates to the submerged arc welding method using the welding flux of the present invention.
  • the composition and preferable components of the welding flux are as described above.
  • the L pole represents the leading pole
  • the T pole represents the trailing pole.
  • Welding current / arc voltage 500 to 1200A / 26 to 40V (1st, L pole), 500 to 1200A / 26 to 40V (1st, T pole), 500 to 1500A / 26 to 40V (2nd, L pole), 500 to 1500A / 26-40V (2nd, T pole)
  • Welding speed 10-1000 cm / min (1st, 2nd)
  • Electrode arrangement The angle between the L pole and the T pole is 0 to 45 °.
  • Steel type JIS G 3106: 2015 compliant
  • the powder raw material containing Mg contains 53 to 58% by mass of Mg with respect to the total mass of the powder raw material containing Mg, and the powder raw material containing Ca is the total mass of the powder raw material containing Ca.
  • the powder raw material containing 45 to 50% by mass of Ca and containing Ba a powder raw material containing 65 to 70% by mass of Ba with respect to the total mass of the powder raw material containing Ba was used.
  • EDX analysis was performed on the cross section of the compound layer using energy dispersive X-ray spectroscopy (EDX), and particles containing an oxide containing Si and compounds around it.
  • the elements contained in the layer were analyzed by mapping.
  • EDX analysis by SEM can be performed as follows. For example, a tabletop microscope (manufactured by Hitachi High-Technologies Corporation: Miniscope TM3030) is used to observe the polished observation surface at a magnification of 1000 times. In this example, the presence or absence of particles containing an oxide containing Si was observed, and elements other than Si were investigated in the particles containing an oxide containing Si. In addition, the compound layer on the outer surface of the particles containing the oxide containing Si was observed, and the coverage was evaluated. In addition, in the column of K, Na, Ti, Al and Mg in "elements other than Si in particles containing oxide containing Si" shown in Table 3 below, those in which these elements are detected are " ⁇ ". , "-" Was not detected.
  • any three fields of view (field of view 1, field of view 2, field of view 3) that are rectangles of 200 ⁇ m ⁇ 170 ⁇ m are selected, and particles containing an oxide containing Si are selected for each of the three fields of view.
  • the outer surface of one particle is observed per field of view, and the field of view in which the compound layer is formed in 50% or more of the outer surface is marked with " ⁇ ", and the compound layer is formed on the outer surface.
  • the visual field in which the compound layer is formed is less than 50% of the outer surface of the particles is defined as “ ⁇ ”, and the visual field in which the compound layer is not formed on the outer surface is defined as “x”, and the visual fields 1, the visual fields 2 and the visual fields 3 are observed.
  • ⁇ 50% of the outer surface of the particles
  • x the visual field in which the compound layer is not formed on the outer surface
  • FIG. 1 is an example of an SEM photograph taken of a cross section of the welding flux obtained by the present embodiment.
  • a compound layer 2 is formed on the outer surface of the particles 1 containing an oxide containing Si.
  • elemental analysis was performed on the particles 1 and the compound layer 2 by EDX, Si, O, K, Na, Al and the like were observed in the particles 1, and Mg and Ca were observed in the compound layer 2.
  • the moisture absorption resistance was evaluated by the water content of the flux after forced moisture absorption for 24 hours. Specifically, the obtained flux was re-dried at 250 ° C. for 1 hour, and then left to stand for 24 hours under the conditions of a temperature of 30 ° C. and a humidity of 80 RH%, and a moisture measuring device ( The water content in the flux was measured by the curl fisher (KF) method using CA-200) manufactured by Mitsubishi Chemical Corporation. In this example, those having a water content of 1200 ppm or less measured by the KF method were regarded as acceptable.
  • KF curl fisher
  • Welding current 450-550A Arc voltage: 30-34V Welding speed: 480 to 520 mm / min Steel grade: JIS G 3106: 2015 SM400 compliant Plate thickness: 12 mm Overhang length: 30 mm
  • oxides are obtained by forming a compound layer containing a strongly deoxidizing element at a predetermined coverage, that is, 50% or more of the outer surface, on the outer surface of particles containing an oxide containing Si. Since it is present at a ratio of 50% or more with respect to the total number of particles containing the above, excellent moisture absorption resistance can be obtained, whereby the amount of diffusible hydrogen in the weld metal is 3.5 ml / 100 g or less. We were able to obtain the welding flux.

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Abstract

Provided is a welding flux allowing excellent moisture absorption resistance to be obtained even when left standing for a long period of time, thereby allowing for a reduction in the amount of diffusing hydrogen in the welded metal, which is one factor causing welded metal cracking; also provided are a production method for the welding flux, and a submerged arc welding method using the welding flux. The welding flux comprises particles (1) containing an oxide. The oxide contains Si. A compound layer (2) has been formed over at least a portion of the outer surface on each of the particles (1). The compound layer (2) contains a strong deoxidizing element constituting an oxide having a lower standard Gibbs energy of formation than the standard Gibbs energy of formation of SiO2 in a temperature range of 500 to 1,000°C in an Ellingham diagram. The particles (1) having the compound layer formed over 50% or more of the outer surface are present at a proportion of 50% or higher with respect to the total particle count for the particles containing the oxide.

Description

溶接用フラックス及びその製造方法、並びに該溶接用フラックスを使用したサブマージアーク溶接方法Welding flux and its manufacturing method, and submerged arc welding method using the welding flux.
　本発明は、耐吸湿性に優れた溶接用フラックス及びその製造方法、並びに該溶接用フラックスを使用したサブマージアーク溶接方法に関する。 The present invention relates to a welding flux having excellent moisture absorption resistance and a method for producing the same, and a submerged arc welding method using the welding flux.
　溶接用フラックスが適用される溶接方法の例として、一般的にサブマージアーク溶接やエレクトロスラグ溶接等が挙げられる。例えば、サブマージアーク溶接は、石油や天然ガス等を輸送するパイプライン用の造管溶接等に用いられる溶接方法である。このサブマージアーク溶接用に設計されたフラックスは、高温多湿の雰囲気に放置した場合、フラックス粒子の細孔内部や表面に水分が吸着して、吸湿しやすい性質を有している。そして、粒子に吸着した水分は、高温のアークにさらされると分解して水素及び酸素となり、溶接金属の拡散性水素量を増加させて低温割れを引き起こすとともに、溶接作業性に悪影響を及ぼす。したがって、サブマージアーク溶接においては、溶接用フラックスの耐吸湿性の向上が極めて重要な課題の一つとして挙げられている。 Examples of welding methods to which welding flux is applied generally include submerged arc welding and electroslag welding. For example, submerged arc welding is a welding method used for pipe making welding for pipelines that transport petroleum, natural gas, and the like. The flux designed for this submerged arc welding has a property that when it is left in a high temperature and high humidity atmosphere, moisture is adsorbed inside or on the surface of the pores of the flux particles and it is easy to absorb moisture. When the particles are exposed to a high-temperature arc, the water adsorbed on the particles decomposes into hydrogen and oxygen, which increases the amount of diffusible hydrogen in the weld metal, causes low-temperature cracking, and adversely affects welding workability. Therefore, in submerged arc welding, improving the moisture absorption resistance of the welding flux is mentioned as one of the extremely important issues.
　そこで、特許文献１には、フラックス中のＡｌ２Ｏ３、ＳｉＯ２、ＭｇＯ、ＣａＦ２換算値、ＭｎＯ換算値、Ｎａ２Ｏ換算値、Ｋ２Ｏ換算値及びＬｉ２Ｏ換算値のうち少なくとも一つ以上の合計、ＦｅＯ換算値、ＣａＯ、水溶性ＳｉＯ２、水溶性Ｎａ２Ｏ、並びに水溶性Ｋ２Ｏの含有量を適切に調整し、所定の数式により得られる値を限定したサブマージアーク溶接用フラックスが提案されている。
　また、特許文献２には、フラックス中の上記酸化物及びＴｉＯ２の含有量、並びに所定の数式により得られる値を限定したサブマージアーク溶接用フラックスが開示されている。 Therefore, Patent Document 1 describes at least one of Al 2 O 3 , SiO 2 , MgO, CaF 2 converted value, Mn O converted value, Na 2 O converted value, K 2 O converted value and Li 2 O converted value in the flux. Submerged arc that appropriately adjusts the content of one or more total, FeO conversion value, CaO, water-soluble SiO 2 , water-soluble Na 2 O, and water-soluble K 2 O, and limits the values obtained by a predetermined formula. Welding flux has been proposed.
Further, Patent Document 2 discloses a flux for submerged arc welding in which the contents of the oxide and TiO 2 in the flux and the values obtained by a predetermined mathematical formula are limited.
　上記特許文献１及び２には、フラックスの吸湿量及び溶接金属中の拡散性水素量を低減することが可能となる旨が記載されている。特に、吸湿量については、フラックスを再乾燥した後に、２時間の強制吸湿を実施し、フラックスが有する水分量を測定することにより評価している。 The above-mentioned Patent Documents 1 and 2 describe that it is possible to reduce the amount of moisture absorbed by the flux and the amount of diffusible hydrogen in the weld metal. In particular, the amount of moisture absorbed is evaluated by performing forced moisture absorption for 2 hours after re-drying the flux and measuring the amount of water contained in the flux.
日本国特開２０１６－１４０８８８号公報Japanese Patent Application Laid-Open No. 2016-140888 日本国特開２０１６－１４０８８９号公報Japanese Patent Application Laid-Open No. 2016-1408889
　しかしながら、一般的な使用現場では、再乾燥後に２時間を超えて放置されたフラックスを使用することがあり、上記特許文献１及び２に記載のサブマージアーク溶接用フラックスは、長時間放置後の吸湿性について、十分な検討がなされていなかった。 However, in a general use site, a flux left for more than 2 hours after re-drying may be used, and the flux for submerged arc welding described in Patent Documents 1 and 2 above absorbs moisture after being left for a long time. The sex has not been fully examined.
　本発明は上記課題を鑑みてなされたものであって、長時間放置された場合であっても優れた耐吸湿性を得ることができ、これにより、溶接金属の割れの要因の一つである溶接金属中の拡散性水素量を低減することができる溶接用フラックス及びその製造方法、並びに該溶接用フラックスを使用したサブマージアーク溶接方法を提供することを目的とする。 The present invention has been made in view of the above problems, and excellent moisture absorption resistance can be obtained even when the weld metal is left for a long time, which is one of the causes of cracking of the weld metal. It is an object of the present invention to provide a welding flux capable of reducing the amount of diffusible hydrogen in a weld metal, a method for producing the same, and a submerged arc welding method using the welding flux.
　本発明者らは鋭意研究を重ねた結果、溶接用フラックスに含まれるＳｉを含む酸化物について着目した。すなわち、本発明者らは、このＳｉを含む酸化物を含有する粒子は極めて吸湿しやすいため、この粒子の表面に耐吸湿性の高い化合物層を生成させることによりフラックスの耐吸湿性を向上し、溶接金属中の拡散性水素量を低減することができることを見出した。以下、溶接用フラックスを単にフラックスということがある。 As a result of diligent research, the present inventors focused on oxides containing Si contained in welding flux. That is, since the particles containing the oxide containing Si are extremely easy to absorb moisture, the present inventors have improved the moisture absorption resistance of the flux by forming a compound layer having high moisture absorption resistance on the surface of the particles. , Found that the amount of diffusible hydrogen in the weld metal can be reduced. Hereinafter, the flux for welding may be simply referred to as flux.
　本発明の上記目的は、溶接用フラックスに係る下記［１］の構成により達成される。 The above object of the present invention is achieved by the configuration of the following [1] relating to the welding flux.
［１］　溶接用フラックスであって、
　前記溶接用フラックスは酸化物を含有する粒子を有し、
　前記酸化物はＳｉを含み、
　前記粒子の外表面の少なくとも一部には化合物層が生成されており、
　前記化合物層は、エリンガム図における５００～１０００℃の温度範囲で、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素を含み、
　前記外表面の５０％以上に前記化合物層が生成されている前記粒子が、前記酸化物を含有する粒子の全粒子数に対して５０％以上の割合で存在する、溶接用フラックス。 [1] Welding flux
The welding flux has particles containing oxides and has particles.
The oxide contains Si and contains
A compound layer is formed on at least a part of the outer surface of the particles.
The compound layer contains a strongly deoxidizing element constituting an oxide having a standard produced Gibbs energy lower than the SiO 2 standard produced Gibbs energy in the temperature range of 500 to 1000 ° C. in the Ellingham diagram.
A welding flux in which the particles having the compound layer formed on 50% or more of the outer surface are present at a ratio of 50% or more with respect to the total number of particles containing the oxide.
　また、溶接用フラックスに係る本発明の好ましい実施形態は、以下の［２］～［５］に関する。 Further, a preferred embodiment of the present invention relating to a welding flux relates to the following [2] to [5].
［２］　前記強脱酸元素は、
　エリンガム図における５００～１０００℃の全温度領域において、酸化物標準生成ギブスエネルギーの値が、－８００ｋＪ／ｇ・ｍｏｌＯ２以下である酸化物を構成する元素である、［１］に記載の溶接用フラックス。 [2] The strongly deoxidizing element is
Ellingham The element for welding according to [1], which is an element constituting an oxide having an oxide standard production Gibbs energy value of −800 kJ / g · molO 2 or less in the entire temperature range of 500 to 1000 ° C. in the figure. flux.
［３］　前記強脱酸元素は、Ｍｇ、Ｃａ及びＢａから選択された少なくとも一種の元素である、［１］又は［２］に記載の溶接用フラックス。 [3] The welding flux according to [1] or [2], wherein the strongly deoxidizing element is at least one element selected from Mg, Ca and Ba.
［４］　前記Ｓｉを含む酸化物は、Ｓｉ単体の酸化物、又は、Ｋ、Ｎａ及びＡｌから選択された少なくとも一種とＳｉとを含有する複合酸化物である、［１］～［３］のいずれか１つに記載の溶接用フラックス。 [4] The oxide containing Si is an oxide of Si alone or a composite oxide containing at least one selected from K, Na and Al and Si, [1] to [3]. The welding flux according to any one.
［５］　溶接用フラックス全質量あたり、
　全Ｆ量：５．０質量％以上、２０．０質量％以下、
　全ＳｉのＳｉＯ２換算値：１０．０質量％以上、２５．０質量％以下、
　全ＡｌのＡｌ２Ｏ３換算値：１４．０質量％以上、３０．０質量％以下、
　Ｎａ及びＫのいずれか一方又は両方：全ＮａのＮａ２Ｏ換算値及び全ＫのＫ２Ｏ換算値の合計で１．０質量％以上、６．０質量％以下、
　全ＴｉのＴｉＯ２換算値：０．５質量％以上、５．０質量％以下、
　全ＭｎのＭｎＯ換算値：０．５質量％以上、１３．０質量％以下、及び
　全ＦｅのＦｅＯ換算値：０．５質量％以上、７．０質量％以下、
を含有するとともに、
　Ｍｇ、Ｃａ及びＢａから選択された少なくとも一種を、
　全ＭｇのＭｇＯ換算値：１５．０質量％以上、３０．０質量％以下、
　全ＣａのＣａＯ換算値：７．０質量％以上、３０．０質量％以下、
　全ＢａのＢａＯ換算値：８．０質量％以下、
の範囲で含有する、［１］～［４］のいずれか１つに記載の溶接用フラックス。 [5] Per total mass of welding flux
Total F amount: 5.0% by mass or more, 20.0% by mass or less,
SiO 2 conversion value of all Si: 10.0% by mass or more, 25.0% by mass or less,
Al 2 O 3 conversion value of all Al: 14.0% by mass or more, 30.0% by mass or less,
Either or both of Na and K: 1.0% by mass or more and 6.0% by mass or less in total of the Na 2 O conversion value of all Na and the K 2 O conversion value of all K.
TiO 2 conversion value of all Ti: 0.5% by mass or more, 5.0% by mass or less,
MnO conversion value of all Mn: 0.5% by mass or more, 13.0% by mass or less, and FeO conversion value of all Fe: 0.5% by mass or more, 7.0% by mass or less,
As well as containing
At least one selected from Mg, Ca and Ba,
MgO conversion value of all Mg: 15.0% by mass or more, 30.0% by mass or less,
CaO conversion value of all Ca: 7.0% by mass or more, 30.0% by mass or less,
BaO conversion value of all Ba: 8.0% by mass or less,
The welding flux according to any one of [1] to [4], which is contained in the range of.
　また、本発明の上記目的は、溶接用フラックスの製造方法に係る下記［６］の構成により達成される。 Further, the above object of the present invention is achieved by the configuration of the following [6] relating to the method for producing a flux for welding.
［６］　［１］～［５］のいずれか１つに記載の溶接用フラックスを製造する溶接用フラックスの製造方法であって、
　粉体原料を配合した配合フラックスに結合剤を添加して造粒後、５００～１０００℃の温度で焼成する工程を有し、
　前記配合フラックスは、前記粉体原料として、Ｓｉを含む酸化物の粉体原料、及び、強脱酸元素を含む金属の粉体原料又は化合物の粉体原料を含有し、
　前記強脱酸元素は、エリンガム図における５００～１０００℃の温度範囲でＳｉＯ２よりも低い標準生成ギブスエネルギーを有する酸化物を構成する元素である、溶接用フラックスの製造方法。 [6] The method for producing a welding flux according to any one of [1] to [5].
It has a step of adding a binder to a blending flux containing a powder raw material, granulating, and then firing at a temperature of 500 to 1000 ° C.
The compounded flux contains, as the powder raw material, a powder raw material of an oxide containing Si, and a powder raw material of a metal containing a strongly deoxidizing element or a powder raw material of a compound.
The method for producing a welding flux, wherein the strongly deoxidizing element is an element constituting an oxide having a standard enthalpy of formation lower than SiO 2 in the temperature range of 500 to 1000 ° C. in the Ellingham diagram.
　また、溶接用フラックスの製造方法に係る本発明の好ましい実施形態は、以下の［７］に関する。 Further, a preferred embodiment of the present invention relating to a method for producing a flux for welding relates to the following [7].
［７］　前記強脱酸元素を含む金属の粉体原料又は化合物の粉体原料は、Ｍｇを含む粉体原料、Ｃａを含む粉体原料及びＢａを含む粉体原料から選択された少なくとも一種の粉体原料を含有し、
　前記Ｍｇを含む粉体原料は、Ｍｇを含む粉体原料全質量に対してＭｇを２５質量％以上含有し、
　前記Ｃａを含む粉体原料は、Ｃａを含む粉体原料全質量に対してＣａを３０質量％以上含有し、
　前記Ｂａを含む粉体原料は、Ｂａを含む粉体原料全質量に対してＢａを６０質量％以上含有するものであり、
　前記Ｍｇを含む粉体原料のうち、粒径が７５μｍ以下であるＭｇを含む粉体原料の割合を、前記Ｍｇを含む粉体原料全質量に対する質量％で［ａ］、
　前記Ｃａを含む粉体原料のうち、粒径が７５μｍ以下であるＣａを含む粉体原料の割合を、前記Ｃａを含む粉体原料全質量に対する質量％で［ｂ］、
　前記Ｂａを含む粉体原料のうち、粒径が７５μｍ以下であるＢａを含む粉体原料の割合を、前記Ｂａを含む粉体原料全質量に対する質量％で［ｃ］、
　前記Ｓｉを含む酸化物の粉体原料のうち、粒径が７５μｍ以下であるＳｉを含む酸化物の粉体原料の割合を、前記Ｓｉを含む酸化物の粉体原料全量に対する質量％で［ｄ］としたとき、
　下記式（１）により得られる値が２．５以上である、［６］に記載の溶接用フラックスの製造方法。
　（［ａ］＋［ｂ］＋［ｃ］）／［ｄ］・・・（１） [7] The powder raw material of the metal containing the strongly deoxidizing element or the powder raw material of the compound is at least one selected from the powder raw material containing Mg, the powder raw material containing Ca and the powder raw material containing Ba. Contains powder raw material,
The powder raw material containing Mg contains 25% by mass or more of Mg with respect to the total mass of the powder raw material containing Mg.
The powder raw material containing Ca contains 30% by mass or more of Ca with respect to the total mass of the powder raw material containing Ca.
The powder raw material containing Ba contains 60% by mass or more of Ba with respect to the total mass of the powder raw material containing Ba.
The ratio of the powder raw material containing Mg having a particle size of 75 μm or less to the total mass of the powder raw material containing Mg is [a].
The ratio of the powder raw material containing Ca having a particle size of 75 μm or less to the total mass of the powder raw material containing Ca is [b].
The ratio of the powder raw material containing Ba having a particle size of 75 μm or less to the total mass of the powder raw material containing Ba is [c].
The ratio of the powder raw material of the oxide containing Si having a particle size of 75 μm or less to the powder raw material of the oxide containing Si is determined by mass% with respect to the total amount of the powder raw material of the oxide containing Si [d]. ] When
The method for producing a welding flux according to [6], wherein the value obtained by the following formula (1) is 2.5 or more.
([A] + [b] + [c]) / [d] ... (1)
　また、本発明の上記目的は、サブマージアーク溶接方法に係る下記［８］の構成により達成される。 Further, the above object of the present invention is achieved by the configuration of the following [8] relating to the submerged arc welding method.
［８］　［１］～［５］のいずれか１つに記載の溶接用フラックスを用いたサブマージアーク溶接方法。 [8] The submerged arc welding method using the welding flux according to any one of [1] to [5].
　本発明によれば、長時間放置された場合であっても優れた耐吸湿性を得ることができ、これにより、溶接金属の割れの要因の一つである溶接金属中の拡散性水素量を低減することができる溶接用フラックス及びその製造方法、並びに該溶接用フラックスを使用したサブマージアーク溶接方法を提供することができる。 According to the present invention, excellent moisture absorption resistance can be obtained even when the product is left for a long time, whereby the amount of diffusible hydrogen in the weld metal, which is one of the causes of cracking of the weld metal, can be reduced. It is possible to provide a welding flux that can be reduced, a method for producing the same, and a submerged arc welding method using the welding flux.
図１は、本実施形態により得られた溶接用フラックスの断面を撮影したＳＥＭ写真の一例である。FIG. 1 is an example of an SEM photograph taken of a cross section of the welding flux obtained by the present embodiment.
　以下、本発明を実施するための形態について詳細に説明する。なお、本発明は、以下に説明する実施形態に限定されるものではない。また、本明細書において、数値範囲を示す「～」とは、その前後に記載された数値を下限値及び上限値として含む意味で使用される。
　本発明における溶接用フラックスとしては、サブマージアーク溶接用フラックス及びエレクトロスラグ溶接用フラックス等が挙げられる。以下、本実施形態においては、溶接用フラックスの一例として、サブマージアーク溶接用フラックスに関して説明するが、本発明はサブマージ溶接用フラックスに限定されるものではない。 Hereinafter, embodiments for carrying out the present invention will be described in detail. The present invention is not limited to the embodiments described below. Further, in the present specification, "-" indicating a numerical range is used to mean that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.
Examples of the welding flux in the present invention include a flux for submerged arc welding and a flux for electroslag welding. Hereinafter, in the present embodiment, the flux for submerged arc welding will be described as an example of the flux for welding, but the present invention is not limited to the flux for submerged welding.
［溶接用フラックス］
　本実施形態に係る溶接用フラックスは、酸化物を含有する粒子を有し、酸化物はＳｉを含み、粒子の外表面の少なくとも一部には化合物層が生成されており、化合物層は、エリンガム図における５００～１０００℃の温度範囲で、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素を含み、外表面の５０％以上に上記化合物層が生成されている粒子が、Ｓｉを含む酸化物を含有する粒子の全粒子数に対して５０％以上の割合で存在するものである。
　以下、各要件について更に詳細に説明する。 [Flux for welding]
The welding flux according to the present embodiment has particles containing an oxide, the oxide contains Si, and a compound layer is formed on at least a part of the outer surface of the particles, and the compound layer is an eringham. In the temperature range of 500 to 1000 ° C. in the figure, the above compound layer is formed on 50% or more of the outer surface containing a strongly deoxidizing element constituting an oxide having a standard production Gibbs energy lower than the SiO 2 standard production Gibbs energy. The particles are present at a ratio of 50% or more with respect to the total number of particles containing the oxide containing Si.
Hereinafter, each requirement will be described in more detail.
＜Ｓｉを含む酸化物を含有する粒子＞
　Ｓｉを含む酸化物は、溶融スラグに適度の粘性を与えることによって、主にビード外観及びビード形状を良好にするため、溶接用フラックスを製造するための粉体原料として、広く使用される。しかし、Ｓｉを含む酸化物を含有する粒子は極めて吸湿しやすいため、水分を多く含む特徴がある。そこで、Ｓｉを含む酸化物を含有する粒子の外表面に、後述する耐吸湿性の高い化合物層が生成されていると、フラックスの耐吸湿性を向上させることができ、これにより溶接金属中の拡散性水素量を低減することができる。
　なお、Ｓｉを含む酸化物としては、Ｓｉ単体の酸化物、又は、Ｋ、Ｎａ及びＡｌから選択された少なくとも一種とＳｉとを含有する複合酸化物が挙げられ、これらは特に吸湿しやすい特性を有することから、本発明の効果が期待できる。また、Ｓｉを含む酸化物のうち、Ｋ、Ｎａ及びＡｌから選択された少なくとも一種とＳｉとを含有する複合酸化物は、より吸湿しやすい特性を有することから、本発明の効果がより期待できる。なお、上記複合酸化物の具体的な例としては、ＫＡｌＳｉ３Ｏ８、ＮａＡｌＳｉ３Ｏ８、ＣａＡｌ２Ｓｉ２Ｏ８等が挙げられる。 <Particles containing oxides containing Si>
Oxides containing Si are widely used as a powder raw material for producing a flux for welding, mainly because the appearance and shape of the bead are improved by imparting an appropriate viscosity to the molten slag. However, since the particles containing an oxide containing Si are extremely easy to absorb moisture, they have a characteristic of containing a large amount of water. Therefore, if a compound layer having high moisture absorption resistance, which will be described later, is formed on the outer surface of the particles containing an oxide containing Si, the moisture absorption resistance of the flux can be improved, whereby the moisture absorption resistance of the flux can be improved. The amount of diffusible hydrogen can be reduced.
Examples of the oxide containing Si include an oxide of Si alone or a composite oxide containing at least one selected from K, Na and Al and Si, and these have characteristics that are particularly easy to absorb moisture. Therefore, the effect of the present invention can be expected. Further, among the oxides containing Si, the composite oxide containing Si and at least one selected from K, Na and Al has the property of being more easily absorbed by moisture, so that the effect of the present invention can be expected more. .. Specific examples of the composite oxide include KAlSi 3 O 8 , NaAlSi 3 O 8 , CaAl 2 Si 2 O 8 , and the like.
＜化合物層＞
　化合物層は、エリンガム図における５００～１０００℃の温度範囲で、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素を含有する。この化合物層は、例えば、酸素との親和性が高い強脱酸元素を含む金属の粉体原料又は化合物の粉体原料と、Ｓｉを含む酸化物の粉体原料と、水ガラス等の結合剤を用いてフラックスを造粒し、所定の温度で焼成することにより生成することができる。
　なお、化合物層は、Ｓｉを含む酸化物を含有する全ての粒子の外表面に生成されている必要はなく、また、粒子の外表面全面に生成されている必要もない。具体的には、Ｓｉを含む酸化物を含有する粒子の外表面の５０％以上に化合物層が生成されている粒子が、上記酸化物を含有する粒子の全粒子数に対して５０％以上の割合で存在していればよい。また、上記酸化物を含有する粒子の全粒子数に対する、Ｓｉを含む酸化物を含有する粒子の外表面の５０％以上に化合物層が生成されている粒子の割合は、好ましくは６０％以上であり、より好ましくは６５％以上であり、更に好ましくは７５％以上である。
　なお、ここで指す粒子の外表面とは、該粒子の断面における観察により判断するものとし、粒子の断面の円周を指す。また、本願明細書において、Ｓｉを含む酸化物の粉体原料とは、Ｓｉを含む酸化物を含有する粒子を含む原料をいう。 <Compound layer>
The compound layer contains a strongly deoxidizing element constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard produced Gibbs energy in the temperature range of 500 to 1000 ° C. in the Ellingham diagram. This compound layer is, for example, a metal powder raw material containing a strongly deoxidizing element having a high affinity for oxygen or a compound powder raw material, an oxide powder raw material containing Si, and a binder such as water glass. It can be produced by granulating the flux using the above and baking it at a predetermined temperature.
The compound layer does not have to be formed on the outer surface of all the particles containing the oxide containing Si, nor does it need to be formed on the entire outer surface of the particles. Specifically, the amount of particles in which the compound layer is formed on 50% or more of the outer surface of the particles containing the oxide containing Si is 50% or more of the total number of particles of the particles containing the oxide. It suffices if it exists in proportion. Further, the ratio of the particles in which the compound layer is formed on 50% or more of the outer surface of the particles containing the oxide containing Si is preferably 60% or more with respect to the total number of particles containing the oxide. Yes, more preferably 65% or more, still more preferably 75% or more.
The outer surface of the particle referred to here refers to the circumference of the cross section of the particle, which is determined by observing the cross section of the particle. Further, in the present specification, the powder raw material of an oxide containing Si means a raw material containing particles containing an oxide containing Si.
＜強脱酸元素＞
　強脱酸元素とは、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する元素を指し、例えば、Ｔｉ、Ｃｅ、Ａｌ、Ｚｒ、Ｂａ、Ｃａ及びＭｇ等が挙げられる。上記化合物層は、強脱酸元素を含む金属又は化合物の粒子が、Ｓｉを含む酸化物を含有する粒子の外表面に接触して、強脱酸元素を含む金属又は化合物の粒子と、Ｓｉを含む酸化物を含有する粒子とが、フラックス製造工程における焼成時の熱により、界面反応することで生成されると考えられる。したがって、上記化合物層を生成するためには、フラックス製造工程における焼成温度の範囲内において、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素を含む金属の粉体原料又は化合物の粉体原料を、配合フラックスの粉体原料として用いることが必要である。 <Strong deoxidizing element>
The strongly deoxidizing element refers to an element constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy, and examples thereof include Ti, Ce, Al, Zr, Ba, Ca and Mg. .. In the compound layer, the particles of the metal or compound containing a strongly deoxidizing element come into contact with the outer surface of the particles containing an oxide containing Si to form Si with the particles of the metal or compound containing a strongly deoxidizing element. It is considered that the particles containing the oxide contained are produced by an interfacial reaction due to the heat at the time of firing in the flux manufacturing process. Therefore, in order to form the compound layer, a metal containing a strongly deoxidizing element constituting an oxide having a standard production Gibbs energy lower than the SiO 2 standard production Gibbs energy within the firing temperature range in the flux manufacturing process. It is necessary to use the powder raw material of the above or the powder raw material of the compound as the powder raw material of the compounding flux.
　これらの強脱酸元素のうち、特に、エリンガム図における５００～１０００℃の全温度領域において、標準生成ギブスエネルギーの値が、－８００ｋＪ／ｇ・ｍｏｌＯ２以下である酸化物を構成する元素を採用すると、ＳｉＯ２標準生成ギブスエネルギーとの差が大きくなり、より化合物層が生成されやすくなるため好ましい。５００～１０００℃の全温度領域において、標準生成ギブスエネルギーの値が、－８００ｋＪ／ｇ・ｍｏｌＯ２以下である酸化物を構成する元素としては、Ａｌ、Ｚｒ、Ｂａ、Ｃａ及びＭｇが挙げられる。なお、強脱酸元素としては、Ｍｇ、Ｃａ及びＢａから選択された少なくとも一種の元素を選択することがより好ましく、これらの強脱酸元素を含む金属又は化合物の粉体原料を使用すると、Ｓｉを含む酸化物を含有する粒子の外表面に接触して、フラックス製造工程における焼成時の熱により界面反応することで、耐吸湿性が高い化合物層が生成される。 Among these strongly deoxidized elements, the elements constituting the oxide having a standard generated Gibbs energy value of −800 kJ / g · molO 2 or less in the entire temperature range of 500 to 1000 ° C. in the Ellingham diagram are adopted. Then, the difference from the SiO 2 standard generated Gibbs energy becomes large, and the compound layer is more easily formed, which is preferable. Examples of the elements constituting the oxide having a standard generated Gibbs energy value of −800 kJ / g · molO 2 or less in the entire temperature range of 500 to 1000 ° C. include Al, Zr, Ba, Ca and Mg. As the strongly deoxidizing element, it is more preferable to select at least one element selected from Mg, Ca and Ba, and when a powder raw material of a metal or compound containing these strongly deoxidizing elements is used, Si A compound layer having high moisture absorption resistance is produced by contacting with the outer surface of particles containing an oxide containing an oxide and undergoing an interfacial reaction due to the heat during firing in the flux manufacturing process.
＜フラックスの組成＞
　以下、本実施形態に係るフラックスにおける各成分の含有量について説明する。なお、本実施形態における含有量とは、特に説明がない限り、フラックス全質量に対する質量％を意味する。なお、フラックスの含有量は、分析方法の制約上換算値で規定する成分が存在する。そのため、フラックス全質量に対する各成分の含有量の合計は、換算値を用いる性質上、１００質量％を超える場合がある。 <Composition of flux>
Hereinafter, the content of each component in the flux according to this embodiment will be described. The content in the present embodiment means mass% with respect to the total mass of the flux unless otherwise specified. The flux content has a component specified by a converted value due to the restrictions of the analysis method. Therefore, the total content of each component with respect to the total mass of the flux may exceed 100% by mass due to the property of using the converted value.
（全Ｆ量：５．０質量％以上、２０．０質量％以下）
　フッ化物は、溶融スラグの電気伝導性や流動性を高める効果があり、また、溶融スラグの高温粘性に影響を与える成分の１つでもあることから、溶接作業性に寄与する。また、アーク溶接時のフッ化物の分解反応によって、アーク雰囲気中の水蒸気分圧を下げ、溶接金属中の拡散性水素量を低減することができる。このフラックス全質量に対するフッ化物の含有量は、フラックス全質量に対するＦの質量％（全Ｆ量とも言う）で規定する。したがって、良好なスラグ剥離性と、スラグ焼付きの発生防止、及び溶接金属中の拡散性水素量の低減化の観点より、全Ｆ量は、５．０質量％以上であることが好ましく、１０．０質量％以上であることがより好ましく、１２．０質量％以上であることが更に好ましい。
　一方、ビードの波目が粗くなってビード外観が劣化することを防ぎ、良好なビード形状を得るため、全Ｆ量は２０．０質量％以下であることが好ましく、１８．０質量％以下であることがより好ましく、１７．０質量％以下であることが更に好ましい。 (Total F amount: 5.0% by mass or more and 20.0% by mass or less)
Fluoride has the effect of increasing the electrical conductivity and fluidity of the molten slag, and also contributes to welding workability because it is one of the components that affect the high temperature viscosity of the molten slag. In addition, the partial pressure of water vapor in the arc atmosphere can be reduced and the amount of diffusible hydrogen in the weld metal can be reduced by the decomposition reaction of fluoride during arc welding. The content of fluoride with respect to the total mass of the flux is defined by the mass% of F (also referred to as the total amount of F) with respect to the total mass of the flux. Therefore, from the viewpoint of good slag peelability, prevention of slag seizure, and reduction of the amount of diffusible hydrogen in the weld metal, the total F amount is preferably 5.0% by mass or more. It is more preferably 0.0% by mass or more, and further preferably 12.0% by mass or more.
On the other hand, in order to prevent the bead from becoming rough and deteriorating the appearance of the bead and to obtain a good bead shape, the total F amount is preferably 20.0% by mass or less, and 18.0% by mass or less. It is more preferably 17.0% by mass or less, and further preferably 17.0% by mass or less.
　本実施形態のフラックスにおけるＦ源としては、主にＣａＦ２が挙げられ、その他にＢａＦ２、ＡｌＦ３やＭｇＦ２などが含まれることがあるが、全Ｆ量が上記範囲内であれば、前述したフッ化物の効果に変わりはない。 The F source in the flux of the present embodiment mainly includes CaF 2 , and may also contain BaF 2 , AlF 3 , MgF 2 , etc. However, if the total F amount is within the above range, the above-mentioned There is no change in the effect of fluoride.
（全ＳｉのＳｉＯ２換算値：１０．０質量％以上、２５．０質量％以下）
　Ｓｉを含む酸化物は、溶融スラグに適度な粘性を与えることによって、主にビード外観及びビード形状を良好にする。また、金属Ｓｉ及びＦｅ－Ｓｉ等の合金中のＳｉは、還元剤として働き、溶接金属の酸素量の増加に伴う機械的性質の劣化を防ぎ、ポックマークの発生を抑制する。このフラックス全質量に対するＳｉの含有量は、フラックス中の全Ｓｉ量を、ＳｉＯ２に換算したＳｉＯ２換算値で規定する。上記効果を得るためには、ＳｉＯ２換算値は１０．０質量％以上であることが好ましく、１１．０質量％以上であることがより好ましい。
　一方、ＳｉＯ２換算値の上限が適切に規定されていると、ビード形状やスラグ剥離性及び靱性が劣化を防止することができる。したがって、ＳｉＯ２換算値は２５．０質量％以下であることが好ましく、２０．０質量％以下であることがより好ましい。 (SiO 2 conversion value of all Si: 10.0% by mass or more, 25.0% by mass or less)
The oxide containing Si mainly improves the bead appearance and the bead shape by imparting an appropriate viscosity to the molten slag. Further, Si in alloys such as metallic Si and Fe—Si acts as a reducing agent, prevents deterioration of mechanical properties due to an increase in the amount of oxygen in the weld metal, and suppresses the generation of pock marks. The content of Si with respect to the total mass of the flux is defined by the value converted to SiO 2 in which the total amount of Si in the flux is converted to SiO 2 . In order to obtain the above effect, the SiO 2 conversion value is preferably 10.0% by mass or more, and more preferably 11.0% by mass or more.
On the other hand, if the upper limit of the SiO 2 conversion value is appropriately defined, deterioration of the bead shape, slag peelability and toughness can be prevented. Therefore, the SiO 2 conversion value is preferably 25.0% by mass or less, and more preferably 20.0% by mass or less.
　なお、ここで規定するＳｉＯ２換算値には、前述したＳｉを含む酸化物、金属Ｓｉ及びＦｅ－Ｓｉ等の合金の他に、水ガラス等の結合剤に由来するＳｉのＳｉＯ２換算値も含まれる。 The SiO 2 conversion value specified here includes the SiO 2 conversion value of Si derived from a binder such as water glass, in addition to the above-mentioned Si-containing oxides, metal Si, and alloys such as Fe—Si. included.
（全ＡｌのＡｌ２Ｏ３換算値：１４．０質量％以上、３０．０質量％以下）
　Ａｌは、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素の一つである。そのため、フラックス中にＡｌを含む粉体原料を添加することにより、上記Ｓｉを含む酸化物を含有する粒子の外表面に、Ａｌを含む化合物層が生成され、これにより、フラックスの耐吸湿性を向上させることができ、溶接金属中の拡散性水素量を低減することができる。このフラックス全質量に対するＡｌの含有量は、フラックス中の全Ａｌ量を、Ａｌ２Ｏ３に換算したＡｌ２Ｏ３換算値で規定する。上記効果を得るためには、Ａｌ２Ｏ３換算値は１４．０質量％以上であることが好ましい。また、３０．０質量％以下であることが好ましい。上記Ａｌを含む粉体原料として、例えば、Ａｌ２Ｏ３、ＡｌＦ３、金属Ａｌ及びＡｌ－Ｍｇ等の合金等の形態で添加することができる。特にＡｌ２Ｏ３は、スラグの剥離性や低温靱性の向上に大きく寄与し、溶接時のビード形状及びビード外観を良好にする成分であることから、Ａｌ２Ｏ３の形態で添加することが好ましい。良好なビード形状及びビード外観を得られることからＡｌ２Ｏ３換算値は、１６．０質量％以上であることがより好ましい。
　一方、溶融スラグの融点が過度に上昇することを防ぎ、ビード端の良好なスラグ剥離性を保つことができるため、Ａｌ２Ｏ３換算値は、２７．０質量％以下であることがより好ましい。 (Al 2 O 3 conversion value of all Al: 14.0% by mass or more and 30.0% by mass or less)
Al is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing Al to the flux, a compound layer containing Al is formed on the outer surface of the particles containing the oxide containing Si, thereby improving the moisture absorption resistance of the flux. It can be improved and the amount of diffusible hydrogen in the weld metal can be reduced. The Al content with respect to the total mass of the flux is defined by the Al 2 O 3 conversion value obtained by converting the total Al content in the flux into Al 2 O 3 . In order to obtain the above effect, the Al 2 O 3 conversion value is preferably 14.0% by mass or more. Further, it is preferably 30.0% by mass or less. As the powder raw material containing Al, for example, it can be added in the form of an alloy such as Al 2 O 3 , Al F 3 , metal Al and Al—Mg. In particular, Al 2 O 3 greatly contributes to the improvement of slag peelability and low temperature toughness, and is a component that improves the bead shape and bead appearance at the time of welding. Therefore, it can be added in the form of Al 2 O 3 . preferable. The Al 2 O 3 conversion value is more preferably 16.0% by mass or more because a good bead shape and bead appearance can be obtained.
On the other hand, the Al 2 O 3 conversion value is more preferably 27.0% by mass or less because it can prevent the melting point of the molten slag from rising excessively and maintain good slag peelability at the bead end. ..
（Ｎａ及びＫのいずれか一方又は両方：全ＮａのＮａ２Ｏ換算値及び全ＫのＫ２Ｏ換算値の合計で１．０質量％以上、６．０質量％以下）
　アルカリ金属であるＮａ及びＫは、主に溶接時のアーク安定性とフラックスの吸湿特性に影響を与える成分である。溶接時のアーク安定性の観点より、フラックス中にＮａ及びＫのいずれか一方又は両方が含有されていることが好ましい。このフラックス全質量に対するＮａ及びＫの含有量は、フラックス中の全Ｎａ及び全Ｋ量を、それぞれＮａ２Ｏ及びＫ２Ｏに換算したＮａ２Ｏ換算値及びＫ２Ｏ換算値で規定する。良好なアーク安定性が得られることから、Ｎａ２Ｏ換算値及びＫ２Ｏ換算値の合計は１．０質量％以上であることが好ましく、１．５質量％以上であることがより好ましい。
　一方、フラックスが過剰に吸湿することを防ぐため、Ｎａ２Ｏ換算値及びＫ２Ｏ換算値の合計は６．０質量％以下であることが好ましく、５．０質量％以下であることがより好ましい。Ｎａ及びＫを含む粉体原料として、例えばＮａ２Ｏ、Ｋ２Ｏ、ＫＡｌＳｉ３Ｏ８、ＮａＡｌＳｉ３Ｏ８、ＣａＡｌ２Ｓｉ２Ｏ８等の酸化物の形態で添加することができるが、より良好なアーク安定性を得るためにＫＡｌＳｉ３Ｏ８、ＮａＡｌＳｉ３Ｏ８の形態でフラックス中に添加されることがより好ましい。
　なお、ここで規定するＮａ２Ｏ換算値及びＫ２Ｏ換算値には、前述したＮａ及びＫを含む酸化物の他に、水ガラス等の結合剤に由来するＮａ及びＫのＮａ２Ｏ換算値及びＫ２Ｏ換算値も含まれる。 (One or both of Na and K: 1.0% by mass or more and 6.0% by mass or less in total of the Na 2 O conversion value of all Na and the K 2 O conversion value of all K)
The alkali metals Na and K are components that mainly affect the arc stability during welding and the moisture absorption characteristics of the flux. From the viewpoint of arc stability during welding, it is preferable that the flux contains either or both of Na and K. The contents of Na and K with respect to the total mass of the flux are defined by the Na 2 O conversion value and the K 2 O conversion value obtained by converting the total Na and total K amounts in the flux into Na 2 O and K 2 O, respectively. Since good arc stability can be obtained, the total of the Na 2 O conversion value and the K 2 O conversion value is preferably 1.0% by mass or more, and more preferably 1.5% by mass or more.
On the other hand, in order to prevent the flux from absorbing excessive moisture, the total of the Na 2 O conversion value and the K 2 O conversion value is preferably 6.0% by mass or less, and more preferably 5.0% by mass or less. preferable. As a powder raw material containing Na and K, for example, it can be added in the form of an oxide such as Na 2 O, K 2 O, KAlSi 3 O 8 , NaAlSi 3 O 8 , CaAl 2 Si 2 O 8 , etc. It is more preferable to add it to the flux in the form of KAlSi 3 O 8 and NaAlSi 3 O 8 in order to obtain good arc stability.
The Na 2 O conversion value and the K 2 O conversion value specified here include the Na 2 O conversion of Na and K derived from a binder such as water glass in addition to the above-mentioned oxide containing Na and K. Values and K2O conversion values are also included.
（全ＴｉのＴｉＯ２換算値：０．５質量％以上、５．０質量％以下）
　Ｔｉは、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素の一つである。したがって、フラックス中にＴｉを含む粉体原料を添加することにより、上記Ｓｉを含む酸化物を含有する粒子の外表面に、Ｔｉを含む化合物層が生成される。これにより、フラックスの耐吸湿性を向上させることができ、溶接金属中の拡散性水素量を低減することができる。このフラックス全質量に対するＴｉの含有量は、フラックス中の全Ｔｉ量を、ＴｉＯ２に換算したＴｉＯ２換算値で規定する。上記効果を得るためには、ＴｉＯ２換算値は０．５質量％以上であることが好ましい。また、５．０質量％以下であることが好ましい。上記Ｔｉを含む粉体原料として、例えばＴｉＯ２、金属Ｔｉ、又はＦｅ－Ｔｉ等の合金等の形態で添加することができる。特に、ＴｉＯ２は、スラグの剥離性や低温靱性を向上させることができる成分であるとともに、溶接時のビード形状及びビード外観を良好にする成分であることから、ＴｉＯ２の形態で添加することが好ましい。良好なビード形状及びビード外観を得られることからＴｉＯ２換算値は１．０質量％以上であることがより好ましい。
　一方、溶融スラグの融点が過度に上昇しすぎることを防ぎ、ビード端の良好なスラグ剥離性を保つことができるため、ＴｉＯ２換算値は４．０質量％以下であることがより好ましい。 (TIO 2 conversion value of all Ti: 0.5% by mass or more, 5.0% by mass or less)
Ti is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing Ti to the flux, a compound layer containing Ti is formed on the outer surface of the particles containing the oxide containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced. The content of Ti with respect to the total mass of the flux is defined by the value converted to TiO 2 in which the total amount of Ti in the flux is converted to TiO 2 . In order to obtain the above effect, the TiO 2 conversion value is preferably 0.5% by mass or more. Further, it is preferably 5.0% by mass or less. As the powder raw material containing Ti, for example, it can be added in the form of an alloy such as TiO 2 , metal Ti, or Fe—Ti. In particular, TiO 2 is a component that can improve the peelability and low temperature toughness of slag, and is a component that improves the bead shape and bead appearance at the time of welding. Therefore, it should be added in the form of TiO 2 . Is preferable. It is more preferable that the TiO 2 conversion value is 1.0% by mass or more because a good bead shape and bead appearance can be obtained.
On the other hand, the TiO 2 conversion value is more preferably 4.0% by mass or less because it can prevent the melting point of the molten slag from rising excessively and maintain good slag peelability at the bead end.
（全ＭｎのＭｎＯ換算値：０．５質量％以上、１３．０質量％以下）
　Ｍｎは、溶融スラグの粘性及び凝固温度に影響を与えるとともに、耐ポックマーク性改善に有効である。また、フラックス中にＭｎが適切な量で含まれていると、良好な低温靱性が得られ、気孔欠陥の発生を防止することができる。このフラックス全質量に対するＭｎの含有量は、フラックス中の全Ｍｎ量を、ＭｎＯに換算したＭｎＯ換算値で規定する。上記効果を得るためには、ＭｎＯ換算値で０．５質量％以上であることが好ましく、０．６％質量％以上であることがより好ましく、０．８質量％以上であることがさらにより好ましい。
　一方、溶接金属の低温における機械的性質の劣化を防ぎ、スラグ焼付きの発生を抑制することができるとともに、良好なビード形状及びスラグ剥離性を得ることができることから、ＭｎＯ換算値で１３．０質量％以下であることが好ましく、１１．０質量％以下であることがより好ましく、５．０質量％以下であることが更に好ましい。Ｍｎを含む粉体原料として、例えばＭｎＯ、ＭｎＯ２及びＭｎ２Ｏ３などの酸化物、金属Ｍｎ及びＦｅ－Ｓｉ－Ｍｎ等の合金の形態で添加することができるが、各種形態の中でも、特に酸化物の形態で添加するとともに、ＭｎＯ換算値が０．５質量％以上、１３．０質量％以下であると、Ｍｎの有用性がより発揮されるため、より好ましい。 (MnO conversion value of all Mn: 0.5% by mass or more and 13.0% by mass or less)
Mn affects the viscosity and solidification temperature of the molten slag, and is effective in improving the pockmark resistance. Further, when Mn is contained in an appropriate amount in the flux, good low temperature toughness can be obtained and the occurrence of pore defects can be prevented. The Mn content with respect to the total mass of the flux is defined by the MnO conversion value obtained by converting the total Mn amount in the flux into MnO. In order to obtain the above effect, the MnO conversion value is preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and even more preferably 0.8% by mass or more. preferable.
On the other hand, since it is possible to prevent deterioration of the mechanical properties of the weld metal at low temperature, suppress the occurrence of slag seizure, and obtain a good bead shape and slag peelability, the MnO conversion value is 13.0. It is preferably 5% by mass or less, more preferably 11.0% by mass or less, and further preferably 5.0% by mass or less. As a powder raw material containing Mn, for example, oxides such as MnO, MnO 2 and Mn 2 O 3 and alloys such as metal Mn and Fe—Si—Mn can be added, but among various forms, in particular. When it is added in the form of an oxide and the MnO conversion value is 0.5% by mass or more and 13.0% by mass or less, the usefulness of Mn is more exhibited, which is more preferable.
（全ＦｅのＦｅＯ換算値：０．５質量％以上、７．０質量％以下）
　Ｆｅは、脱酸現象を促進し、耐ポックマーク性を高める効果があり、特に溶接電流が直流（ＤＣ：Ｄｉｒｅｃｔ　Ｃｕｒｒｅｎｔ）の場合に、より高い効果を得ることができる。このフラックス全質量に対するＦｅの含有量は、フラックス中の全Ｆｅ量を、ＦｅＯに換算したＦｅＯ換算値で規定する。上記効果を得るためには、ＦｅＯ換算値で０．５質量％以上であることが好ましく、１．０質量％以上であることがより好ましい。
　一方、溶融スラグの凝固温度を適切にしてビード外観、ビード形状及びスラグ剥離性を向上させるため、ＦｅＯ換算値で７．０質量％以下であることが好ましく、４．０質量％以下であることがより好ましい。Ｆｅを含む粉体原料として、例えばＦｅＯ、Ｆｅ２Ｏ３及びＦｅ３Ｏ４などの酸化物、金属Ｆｅ及びＦｅ－Ｓｉ等の合金の形態で添加することができるが、特に、Ｆｅ－Ｓｉ等の合金や金属Ｆｅの形態で添加するとともに、ＦｅＯ換算値が０．５質量％以上、７．０質量％以下であると、Ｆｅの有用性がより発揮されるため、より好ましい。 (FeO conversion value of all Fe: 0.5% by mass or more, 7.0% by mass or less)
Fe has the effect of promoting the deoxidation phenomenon and enhancing the pockmark resistance, and can obtain a higher effect particularly when the welding current is direct current (DC). The Fe content with respect to the total mass of the flux is defined by the FeO conversion value obtained by converting the total Fe amount in the flux into FeO. In order to obtain the above effect, the FeO conversion value is preferably 0.5% by mass or more, and more preferably 1.0% by mass or more.
On the other hand, in order to appropriately adjust the solidification temperature of the molten slag and improve the bead appearance, bead shape and slag peelability, the FeO conversion value is preferably 7.0% by mass or less, and preferably 4.0% by mass or less. Is more preferable. As a powder raw material containing Fe, for example, it can be added in the form of an oxide such as FeO, Fe 2 O 3 and Fe 3 O 4 , or an alloy such as metal Fe and Fe—Si, and in particular, Fe—Si and the like. When the FeO conversion value is 0.5% by mass or more and 7.0% by mass or less while being added in the form of the alloy or metal Fe of the above, the usefulness of Fe is more exhibited, which is more preferable.
　本実施形態のフラックスは、前述した含有成分に加えて、上記強脱酸元素として、Ｍｇ、Ｂａ及びＣａから選択された少なくとも一種を以下に示す含有量で含有することがより好ましく、Ｍｇ及びＣａから選択された少なくとも一種を以下に示す含有量で含有することが更に好ましく、Ｍｇ及びＣａの両方を、いずれも以下に示す含有量で含有することが最も好ましい。これらの成分の好ましい含有量について、以下に説明する。 The flux of the present embodiment more preferably contains at least one selected from Mg, Ba and Ca as the above-mentioned strongly deoxidizing element in the content shown below in addition to the above-mentioned contained components, preferably Mg and Ca. It is more preferable to contain at least one selected from the above in the content shown below, and it is most preferable to contain both Mg and Ca in the content shown below. The preferred contents of these components will be described below.
（全ＭｇのＭｇＯ換算値：１５．０質量％以上、３０．０質量％以下）
　Ｍｇは、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素の一つである。したがって、フラックス中にＭｇを含む粉体原料を添加することにより、上記Ｓｉを含む酸化物粒子の外表面に、Ｍｇを含む化合物層が生成される。これにより、フラックスの耐吸湿性を向上させることができ、溶接金属中の拡散性水素量を低減することができる。このフラックス全質量に対するＭｇの含有量は、フラックス中の全Ｍｇ量を、ＭｇＯに換算したＭｇＯ換算値で規定する。上記効果を得るため、ＭｇＯ換算値は１５．０質量％以上であることが好ましい。また、ＭｇＯ換算値は３０．０質量％以下であることが好ましい。ＭｇＯに換算されるＭｇ源としては、例えばＭｇＯ、ＭｇＦ２、ＭｇＣＯ３、Ａｌ－Ｍｇ等の合金、又は金属Ｍｇ等の形態が挙げられる。特に、上記Ｍｇ源のうち、スラグ剥離性の向上にも大きく寄与する成分であることから、ＭｇＯの形態であることが好ましい。電極の極性によらず、良好なスラグ剥離性を確保し、スラグ焼付きを防ぐことができることから、ＭｇＯ換算値は１９．０質量％以上であることがより好ましく、２０．０質量％以上であることが更に好ましい。
　一方、ビード形状が凸になるのを防ぐことができ、良好なスラグ剥離性を保つことができるため、ＭｇＯ換算値は２６．０質量％以下であることがより好ましく、２５．０質量％以下であることが更に好ましい。 (MgO conversion value of all Mg: 15.0% by mass or more, 30.0% by mass or less)
Mg is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing Mg to the flux, a compound layer containing Mg is formed on the outer surface of the oxide particles containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced. The Mg content with respect to the total mass of the flux is defined by the MgO conversion value obtained by converting the total Mg content in the flux into MgO. In order to obtain the above effect, the MgO conversion value is preferably 15.0% by mass or more. Further, the MgO conversion value is preferably 30.0% by mass or less. Examples of the Mg source converted into MgO include alloys such as MgO, MgF 2 , MgCO 3 , and Al—Mg, and forms such as metallic Mg. In particular, among the above Mg sources, the form of MgO is preferable because it is a component that greatly contributes to the improvement of slag peelability. Regardless of the polarity of the electrode, good slag peelability can be ensured and slag seizure can be prevented. Therefore, the MgO conversion value is more preferably 19.0% by mass or more, and 20.0% by mass or more. It is more preferable to have.
On the other hand, since it is possible to prevent the bead shape from becoming convex and maintain good slag peelability, the MgO conversion value is more preferably 26.0% by mass or less, and 25.0% by mass or less. Is more preferable.
（全ＣａのＣａＯ換算値：７．０質量％以上、３０．０質量％以下）
　Ｃａは、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素の一つである。したがって、フラックス中にＣａＯを含む粉体原料を添加することにより、上記Ｓｉを含む酸化物を含有する粒子の外表面に、Ｃａを含む化合物層が生成される。これにより、フラックスの耐吸湿性を向上させることができ、溶接金属中の拡散性水素量を低減することができる。このフラックス全質量に対するＣａの含有量は、フラックス中の全Ｃａ量を、ＣａＯに換算したＣａＯ換算値で規定する。上記効果を得るため、ＣａＯ換算値は７．０質量％以上であることが好ましい。また、ＣａＯ換算値は３０．０質量％以下であることが好ましい。ＣａＯに換算されるＣａ源としては、例えばＣａＯ、ＣａＦ２、ＣａＣＯ３、Ｃａ－Ｓｉ等の合金、又は金属Ｃａ等の形態が挙げられる。特に、ＣａＦ２は、スラグ剥離性の向上にも大きく寄与する成分であることから、ＣａＦ２の形態で添加することが好ましい。スラグの塩基度を高めて溶接金属の清浄度を高めることにより、溶接金属の機械的性質を向上させるため、ＣａＯ換算値は１７．０質量％以上であることがより好ましく、２０．０質量％以上であることが更に好ましい。
　一方、溶融スラグの流動性が過度に高くなることを防ぎ、良好なビード外観及び形状を得ることができるため、ＣａＯ換算値は２６．０質量％以下であることがより好ましく、２４．０質量％以下であることが更に好ましい。 (CaO conversion value of all Ca: 7.0% by mass or more and 30.0% by mass or less)
Ca is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard produced Gibbs energy. Therefore, by adding the powder raw material containing CaO to the flux, a compound layer containing Ca is formed on the outer surface of the particles containing the oxide containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced. The Ca content with respect to the total mass of the flux is defined by the CaO conversion value obtained by converting the total Ca content in the flux into CaO. In order to obtain the above effect, the CaO conversion value is preferably 7.0% by mass or more. Further, the CaO conversion value is preferably 30.0% by mass or less. Examples of the Ca source converted into CaO include alloys such as CaO, CaF 2 , CaCO 3 , and Ca—Si, and forms such as metallic Ca. In particular, since CaF 2 is a component that greatly contributes to the improvement of slag removability, it is preferable to add it in the form of CaF 2 . In order to improve the mechanical properties of the weld metal by increasing the basicity of the slag and increasing the cleanliness of the weld metal, the CaO conversion value is more preferably 17.0% by mass or more, and 20.0% by mass. The above is more preferable.
On the other hand, the CaO conversion value is more preferably 26.0% by mass or less, more preferably 24.0% by mass, because it prevents the fluidity of the molten slag from becoming excessively high and a good bead appearance and shape can be obtained. % Or less is more preferable.
（全ＢａのＢａＯ換算値：８．０質量％以下）
　Ｂａは、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素の一つである。したがって、フラックス中にＢａＯを含む粉体原料を添加することにより、上記Ｓｉを含む酸化物を含有する粒子の外表面に、Ｂａを含む化合物層が生成される。これにより、フラックスの耐吸湿性を向上させることができ、溶接金属中の拡散性水素量を低減することができる。このフラックス全質量に対するＢａの含有量は、フラックスの全Ｂａ量を、ＢａＯに換算したＢａＯ換算値で規定する。
　上記効果を得るため、任意でＢａを添加する場合、ＢａＯ換算値は０．１質量％以上であることが好ましい。また、ＢａＯ換算値は８．０質量％以下であることが好ましい。ＢａＯに換算されるＢａ源としては、例えばＢａＯ、ＢａＦ２、ＢａＣＯ３、又は金属Ｂａ等の形態が挙げられる。ＢａＯ換算値の下限値は特に限定されるものではないが、スラグの塩基度を高めて溶接金属の清浄度を高めることにより、溶接金属の機械的性質を向上させるため、任意でＢａを添加する場合、ＢａＯ換算値は１．０質量％以上であることがより好ましい。
　一方、溶融スラグの流動性が過度に高くなることを防ぎ、良好なビード外観及び形状を得ることができるため、ＢａＯ換算値は６．０質量％以下であることが好ましい。 (BaO conversion value of all Ba: 8.0% by mass or less)
Ba is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing BaO to the flux, a compound layer containing Ba is formed on the outer surface of the particles containing the oxide containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced. The Ba content with respect to the total mass of the flux is defined by the BaO conversion value obtained by converting the total Ba content of the flux into BaO.
In order to obtain the above effect, when Ba is optionally added, the BaO conversion value is preferably 0.1% by mass or more. Further, the BaO conversion value is preferably 8.0% by mass or less. Examples of the Ba source converted into BaO include forms such as BaO, BaF 2 , BaCO 3 , and metal Ba. The lower limit of the BaO conversion value is not particularly limited, but Ba is optionally added in order to improve the mechanical properties of the weld metal by increasing the basicity of the slag and increasing the cleanliness of the weld metal. In this case, the BaO conversion value is more preferably 1.0% by mass or more.
On the other hand, the BaO conversion value is preferably 6.0% by mass or less in order to prevent the fluidity of the molten slag from becoming excessively high and to obtain a good bead appearance and shape.
　ところで、上記で示した全Ｆ量、ＳｉＯ２換算値、Ａｌ２Ｏ３換算値、Ｎａ２Ｏ換算値、Ｋ２Ｏ換算値、ＴｉＯ２換算値、ＭｇＯ換算値、ＣａＯ換算値、ＢａＯ換算値、ＭｎＯ換算値及びＦｅＯ換算値の合計は、良好なスラグ剥離性及びビード形状を得る観点から９２質量％以上であることが好ましく、９５質量％以上がより好ましく、９８質量％以上が更に好ましい。 By the way, the total F amount shown above, SiO 2 conversion value, Al 2 O 3 conversion value, Na 2 O conversion value, K 2 O conversion value, TiO 2 conversion value, MgO conversion value, CaO conversion value, BaO conversion value. The total of the MnO-converted value and the FeO-converted value is preferably 92% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, from the viewpoint of obtaining good slag peelability and bead shape.
　本実施形態のフラックスは、前述した成分に加えて、必要に応じてＺｒ及びＢから選択された少なくとも一種を含有してもよい。これらの元素の含有量について、以下に説明する。 The flux of the present embodiment may contain at least one selected from Zr and B, if necessary, in addition to the above-mentioned components. The contents of these elements will be described below.
（全ＢのＢ２Ｏ３換算値：０．５０質量％以下）
　Ｂは、溶接金属の靱性向上に有効な成分である。フラックス全質量に対するＢの含有量は、フラックス中の全Ｂ量を、Ｂ２Ｏ３に換算したＢ２Ｏ３換算値で規定する。Ｂ２Ｏ３換算値の下限は特に設けないが、上記効果を得たい場合は、Ｂ２Ｏ３換算値は０．０１質量％以上であることが好ましく、０．０３質量％以上であることがより好ましい。
　一方、溶接金属の硬化による高温割れの発生及び靱性の低下を防止することができることから、Ｂ２Ｏ３換算値は０．５０質量％以下であることが好ましく、０．３０質量％以下であることがより好ましい。Ｂを含む粉体原料として、例えば金属Ｂ、Ｆｅ－Ｂ、Ｆｅ－Ｓｉ－Ｂ等の合金、Ｂの酸化物等の形態で添加することができる。 (B 2 O 3 conversion value of all B: 0.50 mass% or less)
B is an effective component for improving the toughness of the weld metal. The content of B with respect to the total mass of the flux is defined by the B 2 O 3 conversion value obtained by converting the total B content in the flux into B 2 O 3 . The lower limit of the B 2 O 3 conversion value is not particularly set, but if the above effect is desired, the B 2 O 3 conversion value is preferably 0.01% by mass or more, and 0.03% by mass or more. Is more preferable.
On the other hand, since it is possible to prevent the occurrence of high - temperature cracking and the decrease in toughness due to the hardening of the weld metal , the B2O3 conversion value is preferably 0.50% by mass or less, preferably 0.30% by mass or less. Is more preferable. As the powder raw material containing B, for example, it can be added in the form of an alloy such as metal B, Fe—B, Fe—Si—B, an oxide of B, or the like.
（全ＺｒのＺｒＯ２換算値：３．０質量％以下）
　Ｚｒは、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素の一つである。したがって、フラックス中にＺｒを含む粉体原料を添加することにより、上記Ｓｉを含む酸化物を含有する粒子の外表面に、Ｚｒを含む化合物層が生成される。これにより、フラックスの耐吸湿性を向上させることができ、溶接金属中の拡散性水素量を低減することができる。また、Ｚｒは溶融スラグの粘性及び凝固温度に影響を与えるとともに、高速度の溶接でのアーク安定性、良好なビード形状及びビード外観、良好なスラグ剥離性を得るために有効な成分である。フラックス全質量に対するＺｒの含有量は、フラックス中の全Ｚｒ量を、ＺｒＯ２に換算したＺｒＯ２換算値で規定する。Ｚｒを含む粉体原料は比較的高価であるため、特に下限は設けないが、上記効果を得たい場合は、ＺｒＯ２換算値は０．０１質量％以上であることが好ましく、３．０質量％以下とすることが好ましい。Ｚｒを含む粉体原料として、例えばＺｒＯ２、ＺｒＳｉＯ４及びＺｒを含む合金等の形態で添加することができる。 (ZrO 2 conversion value of all Zr: 3.0% by mass or less)
Zr is one of the strongly deoxidizing elements constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard generated Gibbs energy. Therefore, by adding the powder raw material containing Zr to the flux, a compound layer containing Zr is formed on the outer surface of the particles containing the oxide containing Si. As a result, the moisture absorption resistance of the flux can be improved, and the amount of diffusible hydrogen in the weld metal can be reduced. In addition, Zr affects the viscosity and solidification temperature of molten slag, and is an effective component for obtaining arc stability in high-speed welding, good bead shape and bead appearance, and good slag peeling property. The Zr content with respect to the total mass of the flux is defined by the ZrO 2 conversion value obtained by converting the total Zr amount in the flux into ZrO 2 . Since the powder raw material containing Zr is relatively expensive, no lower limit is set, but if the above effect is desired, the ZrO2 conversion value is preferably 0.01% by mass or more , and 3.0% by mass. % Or less is preferable. As a powder raw material containing Zr, for example, it can be added in the form of an alloy containing ZrO 2 , ZrSiO 4 and Zr.
　本実施形態のフラックスは、前述した含有成分に加えて、Ｎｉ、Ｍｏ、Ｃｕ及びＣｒ等の元素を含有していてもよい。フラックス中にＮｉ、Ｍｏ、Ｃｕ及びＣｒを添加する場合に、これらの合計値は、５質量％以下とすることが好ましい。 The flux of this embodiment may contain elements such as Ni, Mo, Cu and Cr in addition to the above-mentioned contained components. When Ni, Mo, Cu and Cr are added to the flux, the total value thereof is preferably 5% by mass or less.
　フラックスに含まれる上記以外の元素として、Ｐ、Ｓ、Ｎｂ及びＶなどの不可避的不純物が挙げられる。これらの不可避的不純物のうち、Ｎｂ及びＶは溶接金属の低温靱性を低下させるため、フラックス全質量に対して各々０．５質量％以下に規制することが好ましく、溶接品質に影響するＰ及びＳはそれぞれ、フラックス全質量に対して０．２０質量％以下に規制することが好ましい。 Examples of elements other than the above contained in the flux include unavoidable impurities such as P, S, Nb and V. Of these unavoidable impurities, Nb and V reduce the low temperature toughness of the weld metal, so it is preferable to regulate each to 0.5% by mass or less with respect to the total mass of the flux, and P and S which affect the welding quality. Is preferably regulated to 0.20% by mass or less with respect to the total mass of the flux.
［溶接用フラックスの製造方法］
　本発明の溶接用フラックスは、以下の粉体原料を配合した配合フラックスに結合剤を添加して造粒後、５００～１０００℃の温度で焼成することにより得られる。
　上記配合フラックスは、粉体原料として、Ｓｉを含む酸化物の粉体原料、及び、上述の強脱酸元素を含む金属の粉体原料又は化合物の粉体原料を含有するものである。強脱酸元素を含む金属の粉体原料又は化合物の粉体原料としては、上記Ｍｇを含む粉体原料、上記Ｃａを含む粉体原料及び上記Ｂａを含む粉体原料の他、上述したフラックスの成分を含む酸化物の粉体原料、及びフッ化物又は炭酸塩等を含む粉体原料が挙げられる。さらに、結合剤としては、例えば、水ガラス、ポリビニルアルコール等を使用することができる。造粒法は、特に限定されるものではないが、転動式造粒機や押し出し式造粒機などを用いる方法が好ましい。 [Manufacturing method of welding flux]
The welding flux of the present invention can be obtained by adding a binder to a blended flux containing the following powder raw materials, granulating the flux, and then firing at a temperature of 500 to 1000 ° C.
The compounded flux contains, as the powder raw material, a powder raw material of an oxide containing Si, and a powder raw material of a metal containing the above-mentioned strongly deoxidizing element or a powder raw material of a compound. As the powder raw material of the metal containing the strongly deoxidizing element or the powder raw material of the compound, the powder raw material containing the Mg, the powder raw material containing Ca, the powder raw material containing Ba, and the above-mentioned flux can be used. Examples thereof include a powder raw material of an oxide containing a component, and a powder raw material containing a fluoride or a carbonate. Further, as the binder, for example, water glass, polyvinyl alcohol and the like can be used. The granulation method is not particularly limited, but a method using a rolling granulation machine, an extrusion type granulation machine, or the like is preferable.
　造粒後の焼成は、ロータリーキルン、定置式バッチ炉及びベルト式焼成炉などで行うことができる。本発明においては、エリンガム図における５００～１０００℃の温度範囲で、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素を含むフラックス原料を採用するため、焼成温度は５００～１０００℃とし、７００～９００℃とすることが好ましい。 The firing after granulation can be performed in a rotary kiln, a stationary batch furnace, a belt-type firing furnace, or the like. In the present invention, in order to employ a flux raw material containing a strongly deoxidizing element constituting an oxide having a standard generated Gibbs energy lower than the SiO 2 standard produced Gibbs energy in the temperature range of 500 to 1000 ° C. in the Ellingham diagram. The firing temperature is preferably 500 to 1000 ° C, preferably 700 to 900 ° C.
　また、本発明者らは、上記粉体原料の粒径を適切に規定することにより、Ｓｉを含む酸化物を含有する粒子の外表面に化合物層が生成されやすいことを見出した。本発明では、後述する式（１）で表されるように、Ｓｉを含む酸化物の粉体原料のうち、粒径が７５μｍ以下である粒子が特に吸湿しやすいことから、種々の強脱酸元素を含む金属の粉体原料及び化合物の粉体原料のうち、粒径が７５μｍ以下である粉体原料の合計量の質量割合が、Ｓｉを含む粉体原料のうち、粒径が７５μｍ以下である粉体原料の質量割合よりも大きいことを好ましいとしている。これにより、Ｓｉを含む酸化物の粉体原料の表面と、強脱酸元素を含む金属の粉体原料又は化合物の粉体原料の粒子の表面との接触面積及び接触回数が増加し、反応層が生成されやすくなる。
　なお、『粒径が７５μｍ以下』とは、ＪＩＳ　Ｚ　８８１５：１９９４に準拠した方法により、ＪＩＳ　Ｚ　８８０１：２０１９に基づく目開き７５μｍの篩いを用いてふるい分けを行った際に、その篩いを通過することを意味する。 Further, the present inventors have found that a compound layer is likely to be formed on the outer surface of particles containing an oxide containing Si by appropriately defining the particle size of the powder raw material. In the present invention, as represented by the formula (1) described later, among the powder raw materials of the oxide containing Si, the particles having a particle size of 75 μm or less are particularly easy to absorb moisture, and therefore various strong deoxidization agents are used. Among the powder raw materials of metal containing elements and the powder raw materials of compounds, the mass ratio of the total amount of the powder raw materials having a particle size of 75 μm or less is 75 μm or less among the powder raw materials containing Si. It is preferable that it is larger than the mass ratio of a certain powder raw material. As a result, the contact area and the number of contacts between the surface of the powder raw material of the oxide containing Si and the surface of the powder raw material of the metal containing the strongly deoxidizing element or the powder raw material of the compound are increased, and the reaction layer is formed. Is more likely to be generated.
In addition, "particle size of 75 μm or less" means that the particle size passes through the sieve when it is sieved using a sieve with a mesh size of 75 μm based on JIS Z 8801: 2019 by a method based on JIS Z 8815: 1994. Means that.
　なお、上記強脱酸元素を含む金属の粉体原料及び化合物の粉体原料は、Ｍｇを含む粉体原料、Ｃａを含む粉体原料及びＢａを含む粉体原料から選択された少なくとも一種の粉体原料を含有することが好ましい。また、Ｍｇを含む粉体原料は、Ｍｇを含む粉体原料全質量に対してＭｇを２５質量％以上含有し、Ｃａを含む粉体原料は、Ｃａを含む粉体原料全質量に対してＣａを３０質量％以上含有し、Ｂａを含む粉体原料は、Ｂａを含む粉体原料全質量に対してＢａを６０質量％以上含有するものであることが好ましい。
　さらに、Ｍｇを含む粉体原料のうち、粒径が７５μｍ以下であるＭｇを含む粉体原料の割合を、上記Ｍｇを含む粉体原料全質量に対する質量％で［ａ］、上記Ｃａを含む粉体原料のうち、粒径が７５μｍ以下であるＣａを含む粉体原料の割合を、上記Ｃａを含む粉体原料全質量に対する質量％で［ｂ］、上記Ｂａを含む粉体原料の割合を、上記Ｂａを含む粉体原料全質量に対する質量％で［ｃ］、上記Ｓｉを含む粉体原料のうち、粒径が７５μｍ以下であるＳｉを含む粉体原料の割合を、上記Ｓｉを含む粉体原料全質量に対する質量％で［ｄ］としたとき、下記式（１）により得られる値が２．５以上であると、反応層が所望の被覆率で生成されやすくなるため、好ましい。
　（［ａ］＋［ｂ］＋［ｃ］）／［ｄ］・・・（１） The metal powder raw material containing the strongly deoxidizing element and the compound powder raw material are at least one kind of powder selected from the powder raw material containing Mg, the powder raw material containing Ca, and the powder raw material containing Ba. It is preferable to contain a body material. Further, the powder raw material containing Mg contains 25% by mass or more of Mg with respect to the total mass of the powder raw material containing Mg, and the powder raw material containing Ca contains Ca with respect to the total mass of the powder raw material containing Ca. 30% by mass or more, and the powder raw material containing Ba is preferably one containing 60% by mass or more of Ba with respect to the total mass of the powder raw material containing Ba.
Further, among the powder raw materials containing Mg, the ratio of the powder raw material containing Mg having a particle size of 75 μm or less is [a] in mass% with respect to the total mass of the powder raw material containing Mg, and the powder containing Ca is used. The ratio of the powder raw material containing Ca having a particle size of 75 μm or less to the total mass of the powder raw material containing Ca is [b], and the ratio of the powder raw material containing Ba is calculated. [C] is the mass% of the total mass of the powder raw material containing Ba, and the ratio of the powder raw material containing Si having a particle size of 75 μm or less among the powder raw materials containing Si is the powder containing Si. When the mass% with respect to the total mass of the raw material is [d], when the value obtained by the following formula (1) is 2.5 or more, the reaction layer is likely to be formed with a desired coverage, which is preferable.
([A] + [b] + [c]) / [d] ... (1)
　Ｍｇを含む粉体原料としては、Ｍｇを含む粉体原料全質量に対してＭｇを５０質量％以上含有するものを用いることがより好ましく、５２質量％以上含有するものを用いることがより好ましい。このようなＭｇを含む粉体原料としては、例えば、ＭｇＯ及びＭｇＣＯ３、ＭｇＦ２等を用いることができる。
　また、Ｃａを含む粉体原料としては、Ｃａを含む粉体原料全質量に対してＣａを４０質量％以上含有するものを用いることがより好ましく、４５質量％以上含有するものを用いることが更に好ましい。このようなＣａを含む粉体原料としては、例えば、ＣａＦ２及びＣａＣＯ３、ＣａＯ等を用いることができる。
　また、Ｂａを含む粉体原料としては、Ｂａを含む粉体原料全質量に対してＢａを６２質量％以上含有するものを用いることがより好ましく、６５質量％以上含有するものを用いることが更に好ましい。このようなＢａを含む粉体原料としては、例えば、ＢａＦ２及びＢａＣＯ３、ＢａＯ等を用いることができる。 As the powder raw material containing Mg, it is more preferable to use one containing 50% by mass or more of Mg with respect to the total mass of the powder raw material containing Mg, and it is more preferable to use one containing 52% by mass or more. As the powder raw material containing such Mg, for example, MgO, MgCO 3 , MgF 2 , and the like can be used.
Further, as the powder raw material containing Ca, it is more preferable to use a powder raw material containing 40% by mass or more of Ca with respect to the total mass of the powder raw material containing Ca, and it is further preferable to use a powder raw material containing 45% by mass or more. preferable. As the powder raw material containing Ca, for example, CaF 2 , CaCO 3 , CaO and the like can be used.
Further, as the powder raw material containing Ba, it is more preferable to use a powder raw material containing 62% by mass or more of Ba with respect to the total mass of the powder raw material containing Ba, and it is further preferable to use a powder raw material containing 65% by mass or more. preferable. As the powder raw material containing such Ba, for example, BaF 2 , BaCO 3 , BaO and the like can be used.
　ここで、Ｍｇ、Ｃａ及びＢａを含む粉体原料全質量に対する各元素の含有量について説明する。例えば、Ｍｇを含む粉体原料で例示すると、ＭｇОのみからなる粉体原料のみを使用する場合は、ＭｇОのみからなる粉体原料全質量に対するＭｇ含有量とし、６０質量％となる。また、マグネシアクリンカーのようなＭｇО以外の成分や不純物を含む粉体原料の場合は、マグネシアクリンカー全質量に対するＭｇ含有量となる。さらに、Ｍｇを含む粉体原料を複数種使用する場合は、全てのＭｇを含む粉体の全質量に対するＭｇ含有量となる。 Here, the content of each element with respect to the total mass of the powder raw material including Mg, Ca and Ba will be described. For example, in the case of a powder raw material containing Mg, when only a powder raw material composed of MgО is used, the Mg content is 60% by mass with respect to the total mass of the powder raw material composed only of MgО. Further, in the case of a powder raw material containing components and impurities other than MgО such as magnesia clinker, the Mg content is the total mass of magnesia clinker. Further, when a plurality of types of powder raw materials containing Mg are used, the Mg content is the total mass of the powder containing all Mg.
　さらに、Ｓｉを含む酸化物の粉体原料としては、例えば、ＳｉＯ２、ＫＡｌＳｉ３Ｏ８、ＮａＡｌＳｉ３Ｏ８、ＣａＡｌ２Ｓｉ２Ｏ８等を用いることができ、これらのうち、ＳｉＯ２、ＫＡｌＳｉ３Ｏ８、ＮａＡｌＳｉ３Ｏ８を用いることがより好ましい。 Further, as the powder raw material of the oxide containing Si, for example, SiO 2 , KAlSi 3 O 8 , NaAlSi 3 O 8 , CaAl 2 Si 2 O 8 and the like can be used, and among these, SiO 2 , KAlSi can be used. It is more preferable to use 3 O 8 and NaAlSi 3 O 8 .
［溶接用フラックスを使用したサブマージアーク溶接方法］
　本発明は、上記本発明の溶接用フラックスを用いたサブマージアーク溶接方法にも関する。溶接用フラックスの構成及び好ましい成分については、上記の通りである。 [Submerged arc welding method using welding flux]
The present invention also relates to the submerged arc welding method using the welding flux of the present invention. The composition and preferable components of the welding flux are as described above.
（溶接条件）
　本実施形態に係るフラックスを用いた１電極溶接として、例えば以下の条件が例示できるが、下記条件になんら限定されるものではない。なお、１ｓｔとは鋼板の表面側の溶接を表し、２ｎｄとは鋼板の裏面側の溶接を表す。
　溶接電流：４００～１０００Ａ（１ｓｔ）、６００～１０００Ａ（２ｎｄ）
　アーク電圧：２６～３６Ｖ（１ｓｔ）、２６～３６Ｖ（２ｎｄ）
　溶接速度：６０～１５０ｃｍ／分（１ｓｔ、２ｎｄ）
　鋼種：ＪＩＳ　Ｇ　３１０６：２０１５準拠
　板厚：９～６０ｍｍ
　突出し長さ：１５～４５ｍｍ (Welding conditions)
As the one-electrode welding using the flux according to the present embodiment, for example, the following conditions can be exemplified, but the conditions are not limited to the following. Note that 1st represents welding on the front surface side of the steel sheet, and 2nd represents welding on the back surface side of the steel sheet.
Welding current: 400-1000A (1st), 600-1000A (2nd)
Arc voltage: 26 to 36V (1st), 26 to 36V (2nd)
Welding speed: 60-150 cm / min (1st, 2nd)
Steel type: JIS G 3106: 2015 compliant Plate thickness: 9-60 mm
Overhang length: 15-45 mm
　本実施形態に係るフラックスを用いた２電極溶接として、例えば以下の条件が例示できるが、下記条件になんら限定されるものではない。なお、Ｌ極とは先行極を表し、Ｔ極とは後行極を表す。
　溶接電流／アーク電圧：５００～１２００Ａ／２６～４０Ｖ（１ｓｔ、Ｌ極）、５００～１２００Ａ／２６～４０Ｖ（１ｓｔ、Ｔ極）、５００～１５００Ａ／２６～４０Ｖ（２ｎｄ、Ｌ極）、　５００～１５００Ａ／２６～４０Ｖ（２ｎｄ、Ｔ極）
　溶接速度：１０～１０００ｃｍ／分（１ｓｔ、２ｎｄ）
　電極配置：Ｌ極とＴ極とのなす角が０～４５°
　鋼種：ＪＩＳ　Ｇ　３１０６：２０１５準拠 As the two-electrode welding using the flux according to the present embodiment, for example, the following conditions can be exemplified, but the conditions are not limited to the following. The L pole represents the leading pole, and the T pole represents the trailing pole.
Welding current / arc voltage: 500 to 1200A / 26 to 40V (1st, L pole), 500 to 1200A / 26 to 40V (1st, T pole), 500 to 1500A / 26 to 40V (2nd, L pole), 500 to 1500A / 26-40V (2nd, T pole)
Welding speed: 10-1000 cm / min (1st, 2nd)
Electrode arrangement: The angle between the L pole and the T pole is 0 to 45 °.
Steel type: JIS G 3106: 2015 compliant
　以下に実施例を挙げて本実施形態を更に具体的に説明するが、本発明はこれら実施例に限定されるものではなく、本発明の趣旨に適合し得る範囲で変更を加えて実施することが可能であり、それらはいずれも本発明の技術的範囲に包含される。 Hereinafter, the present embodiment will be described in more detail with reference to examples, but the present invention is not limited to these examples, and the present invention shall be carried out with modifications to the extent that it can be adapted to the gist of the present invention. Are possible, all of which are within the technical scope of the invention.
＜発明例Ｎｏ．１～５及び比較例Ｎｏ．６～１２＞
　ＪＩＳ　Ｚ　８８１５：１９９４に準拠した方法により、ＪＩＳ　Ｚ　８８０１：２０１９に基づく目開き７５μｍの篩いを用いてふるい分けを行った下記表１に示す粒度分布を有する粉体原料と、その他の粉体原料を配合し、結合剤としての水ガラスとともに混錬した後、造粒し、更にロータリーキルンを使用して６００～９００℃で焼成して、整粒することにより、下記表２に示す溶接用フラックスを製造した。
　なお、発明例Ｎｏ．１～５及び比較例Ｎｏ．６～１２において、Ｍｇを含む粉体原料は、Ｍｇを含む粉体原料全質量に対してＭｇを５３～５８質量％含有し、Ｃａを含む粉体原料は、Ｃａを含む粉体原料全質量に対してＣａを４５～５０質量％含有し、Ｂａを含む粉体原料は、Ｂａを含む粉体原料全質量に対してＢａを６５～７０質量％含有する粉体原料を使用した。 <Invention Example No. 1 to 5 and Comparative Example No. 6-12>
The powder raw material having the particle size distribution shown in Table 1 below and other powder raw materials obtained by sieving using a sieve having a mesh size of 75 μm based on JIS Z 8801: 2019 by a method conforming to JIS Z 8815: 1994 were obtained. The welding flux shown in Table 2 below is manufactured by blending, kneading with water glass as a binder, granulating, firing at 600 to 900 ° C. using a rotary kiln, and sizing. did.
In addition, invention example No. 1 to 5 and Comparative Example No. In 6 to 12, the powder raw material containing Mg contains 53 to 58% by mass of Mg with respect to the total mass of the powder raw material containing Mg, and the powder raw material containing Ca is the total mass of the powder raw material containing Ca. As the powder raw material containing 45 to 50% by mass of Ca and containing Ba, a powder raw material containing 65 to 70% by mass of Ba with respect to the total mass of the powder raw material containing Ba was used.
　その後、得られたフラックスの断面を観察し、化合物層の有無及びその組成等を測定するとともに、フラックスの耐吸湿性を測定した。
　フラックス断面の観察方法、耐吸湿性及び拡散性水素量の測定方法等について、以下に具体的に説明する。また、これらの測定結果を下記表３に示す。 Then, the cross section of the obtained flux was observed, the presence or absence of the compound layer, its composition, and the like were measured, and the hygroscopicity of the flux was measured.
The method of observing the cross section of the flux, the method of measuring the hygroscopicity and the amount of diffusible hydrogen, and the like will be specifically described below. The measurement results are shown in Table 3 below.
（フラックス断面の観察）
　得られた溶接用フラックスを樹脂に埋め込んで、フラックス垂直断面が観察面となるように研磨を行い、観察面を走査型電子顕微鏡（Ｓｃａｎｎｉｎｇ　Ｅｌｅｃｔｒｏｎ　Ｍｉｃｒｏｓｃｏｐｅ；ＳＥＭ）で観察した。なお、ＳＥＭの倍率を１０００倍、加速電圧を５～１５ｋＶとし、反射電子（ＢａｃｋＳｃａｔｔｅｒｅｄ　Ｅｌｅｃｔｒｏｎ；ＢＳＥ）像による組成像を観察することにより、化合物層の生成有無及び状態を確認した。 (Observation of flux cross section)
The obtained welding flux was embedded in a resin, polished so that the vertical cross section of the flux became an observation surface, and the observation surface was observed with a scanning electron microscope (SEM). The presence or absence and state of formation of the compound layer were confirmed by observing the composition image by the backscattered electron (BSE) image with the SEM magnification of 1000 times and the acceleration voltage of 5 to 15 kV.
　また、化合物層の断面に対して、エネルギー分散型Ｘ線分光法（Ｅｎｅｒｇｙ　Ｄｉｓｐｅｒｓｉｖｅ　Ｘ－ｒａｙ　ｓｐｅｃｔｒｏｓｃｏｐｙ；ＥＤＸ）を用いて元素分析をし、Ｓｉを含む酸化物を含有する粒子、及びその周りの化合物層に含まれる元素を、マッピングにて分析した。
　ＳＥＭによるＥＤＸ分析は次のようにして行うことができる。例えば、卓上顕微鏡（株式会社日立ハイテクノロジーズ製：Ｍｉｎｉｓｃｏｐｅ　ＴＭ３０３０）を用いて、上記研磨を行った観察面を１０００倍の倍率にて観察する。
　本実施例では、Ｓｉを含む酸化物を含有する粒子の有無を観察するとともに、Ｓｉを含む酸化物を含有する粒子において、Ｓｉ以外の元素について調査した。また、Ｓｉを含む酸化物を含有する粒子の外表面における化合物層を観察し、被覆率の評価を行った。
　なお、下記表３に示す「Ｓｉを含む酸化物を含有する粒子中のＳｉ以外の元素」における、Ｋ、Ｎａ、Ｔｉ、Ａｌ及びＭｇの欄において、これらの元素が検出されたものを「○」、検出されなかったものを「－」とした。 In addition, elemental analysis was performed on the cross section of the compound layer using energy dispersive X-ray spectroscopy (EDX), and particles containing an oxide containing Si and compounds around it. The elements contained in the layer were analyzed by mapping.
EDX analysis by SEM can be performed as follows. For example, a tabletop microscope (manufactured by Hitachi High-Technologies Corporation: Miniscope TM3030) is used to observe the polished observation surface at a magnification of 1000 times.
In this example, the presence or absence of particles containing an oxide containing Si was observed, and elements other than Si were investigated in the particles containing an oxide containing Si. In addition, the compound layer on the outer surface of the particles containing the oxide containing Si was observed, and the coverage was evaluated.
In addition, in the column of K, Na, Ti, Al and Mg in "elements other than Si in particles containing oxide containing Si" shown in Table 3 below, those in which these elements are detected are "○". , "-" Was not detected.
　化合物層の観察による被覆率の評価は、２００μｍ×１７０μｍの矩形である任意の３視野（視野１、視野２、視野３）を選定し、各３視野について、Ｓｉを含む酸化物を含有する粒子を任意で１粒子選択することにより行った。具体的には、１視野につき１粒子の外表面を観察し、外表面の５０％以上の領域に化合物層が生成されている視野を「○」、外表面に化合物層が生成されているが、化合物層の生成領域が粒子の外表面の５０％未満である視野を「△」、外表面に化合物層が生成されていない視野を「×」とし、視野１、視野２及び視野３の観察結果として、下記表３の「任意の１粒子における化合物層の被覆率評価」の欄にそれぞれ示す。
　また、上記３視野における化合物層の観察による被覆率の評価結果に基づき、全３視野に対する上記で「○」と判断した視野の比率を分数で表し、下記表３の「被覆率評価で「○」と判断した視野の比率」の欄に示す。
　さらに、２視野以上で「○」となったもの、すなわち、上記比率が２／３以上であるものを、化合物層が「有」と評価し、２視野以上で「○」とならなかったもの、すなわち上記比率が１／３以下であるものを、化合物層が「無」と評価し、下記表３の「化合物層の有無」の欄に示す。 For the evaluation of the coverage by observing the compound layer, any three fields of view (field of view 1, field of view 2, field of view 3) that are rectangles of 200 μm × 170 μm are selected, and particles containing an oxide containing Si are selected for each of the three fields of view. Was performed by arbitrarily selecting one particle. Specifically, the outer surface of one particle is observed per field of view, and the field of view in which the compound layer is formed in 50% or more of the outer surface is marked with "○", and the compound layer is formed on the outer surface. , The visual field in which the compound layer is formed is less than 50% of the outer surface of the particles is defined as “Δ”, and the visual field in which the compound layer is not formed on the outer surface is defined as “x”, and the visual fields 1, the visual fields 2 and the visual fields 3 are observed. As a result, they are shown in the columns of "Evaluation of coverage of compound layer in any one particle" in Table 3 below.
Further, based on the evaluation result of the coverage by observing the compound layer in the above three visual fields, the ratio of the visual fields judged to be "○" to all three visual fields is expressed as a fraction, and "○ in the coverage evaluation" in Table 3 below. It is shown in the column of "Ratio of visual fields judged".
Further, those having "○" in two or more visual fields, that is, those having the above ratio of 2/3 or more were evaluated as "Yes" in the compound layer, and those having no "○" in two or more visual fields. That is, the compound layer having the above ratio of 1/3 or less is evaluated as "absent" and is shown in the column of "presence or absence of compound layer" in Table 3 below.
　また、上記元素分析により、化合物層に含まれる元素について調査した。下記表３に示す「化合物層に含まれる元素」におけるＳｉ、Ｔｉ、Ｃｅ、Ａｌ、Ｚｒ、Ｂａ、Ｃａ及びＭｇの欄において、これらの成分が検出されたものを「○」、検出されなかったものを「－」とした。 In addition, the elements contained in the compound layer were investigated by the above elemental analysis. In the columns of Si, Ti, Ce, Al, Zr, Ba, Ca and Mg in the "elements contained in the compound layer" shown in Table 3 below, those in which these components were detected were marked with "○" and were not detected. The thing was set to "-".
　図１は、本実施形態により得られた溶接用フラックスの断面を撮影したＳＥＭ写真の一例である。図１に示すように、Ｓｉを含む酸化物を含有する粒子１の外表面には、化合物層２が生成されている。粒子１及び化合物層２について、ＥＤＸにより元素分析を実施すると、粒子１にはＳｉ、Ｏ、Ｋ、Ｎａ及びＡｌ等が観測され、化合物層２にはＭｇ及びＣａが観測された。 FIG. 1 is an example of an SEM photograph taken of a cross section of the welding flux obtained by the present embodiment. As shown in FIG. 1, a compound layer 2 is formed on the outer surface of the particles 1 containing an oxide containing Si. When elemental analysis was performed on the particles 1 and the compound layer 2 by EDX, Si, O, K, Na, Al and the like were observed in the particles 1, and Mg and Ca were observed in the compound layer 2.
（耐吸湿性）
　耐吸湿性は、２４時間の強制吸湿後のフラックスの水分量により評価した。具体的には、得られたフラックスに対して、２５０℃で１時間の再乾燥を実施した後、気温が摂氏３０℃、湿度が８０ＲＨ％である条件下において２４時間放置し、水分測定装置（三菱化学株式会社製　ＣＡ－２００）を用いて、フラックス中の水分量をカールフィッシャー（ＫＦ）法により測定した。本実施例においては、ＫＦ法により測定された水分量が１２００ｐｐｍ以下であるものを合格とした。 (Hygroscopicity)
The moisture absorption resistance was evaluated by the water content of the flux after forced moisture absorption for 24 hours. Specifically, the obtained flux was re-dried at 250 ° C. for 1 hour, and then left to stand for 24 hours under the conditions of a temperature of 30 ° C. and a humidity of 80 RH%, and a moisture measuring device ( The water content in the flux was measured by the curl fisher (KF) method using CA-200) manufactured by Mitsubishi Chemical Corporation. In this example, those having a water content of 1200 ppm or less measured by the KF method were regarded as acceptable.
　また、得られたフラックスを使用して、以下に示す溶接条件にてサブマージアーク溶接を実施し、得られた溶接金属中の拡散性水素量を測定した。 In addition, using the obtained flux, submerged arc welding was performed under the welding conditions shown below, and the amount of diffusible hydrogen in the obtained weld metal was measured.
　溶接電流：４５０～５５０Ａ
　アーク電圧：３０～３４Ｖ
　溶接速度：４８０～５２０ｍｍ／分
　鋼種：ＪＩＳ　Ｇ　３１０６：２０１５　ＳＭ４００準拠
　板厚：１２ｍｍ
　突出し長さ：３０ｍｍ Welding current: 450-550A
Arc voltage: 30-34V
Welding speed: 480 to 520 mm / min Steel grade: JIS G 3106: 2015 SM400 compliant Plate thickness: 12 mm
Overhang length: 30 mm
（拡散性水素量）
　直径が４．０ｍｍであり、ＪＩＳ　Ｚ　３３５１　２０１２に準拠した組成を有するワイヤを使用して、上記溶接条件でサブマージアーク溶接を実施し、得られた溶接金属について拡散性水素量を測定した。拡散性水素量は、ＪＩＳ　Ｚ　３１１８：２００７に規定される鋼溶接部の水素量測定方法に準拠して測定した。本実施例では、溶接金属中の拡散性水素量が３．５ｍｌ／１００ｇ以下であるものを合格とした。耐吸湿性及び溶接金属中の拡散性水素量の測定結果を下記表３に併せて示す。 (Amount of diffusible hydrogen)
Submerged arc welding was performed under the above welding conditions using a wire having a diameter of 4.0 mm and a composition conforming to JIS Z 3351 2012, and the amount of diffusible hydrogen was measured for the obtained weld metal. The amount of diffusible hydrogen was measured according to the method for measuring the amount of hydrogen in a steel weld specified in JIS Z 3118: 2007. In this example, those having a diffusible hydrogen content of 3.5 ml / 100 g or less in the weld metal were accepted. The measurement results of moisture absorption resistance and the amount of diffusible hydrogen in the weld metal are also shown in Table 3 below.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　上記表１～表３に示すように、発明例Ｎｏ．１～５は、Ｓｉを含む酸化物を含有する粒子の外表面に、所定の被覆率、すなわち外表面の５０％以上で強脱酸元素を含む化合物層が生成されているものが、酸化物を含有する粒子の全粒子数に対して５０％以上の割合で存在するため、優れた耐吸湿性を得ることができ、これにより、溶接金属中の拡散性水素量を３．５ｍｌ／１００ｇ以下とする溶接用フラックスを得ることができた。 As shown in Tables 1 to 3 above, Invention Example No. In Nos. 1 to 5, oxides are obtained by forming a compound layer containing a strongly deoxidizing element at a predetermined coverage, that is, 50% or more of the outer surface, on the outer surface of particles containing an oxide containing Si. Since it is present at a ratio of 50% or more with respect to the total number of particles containing the above, excellent moisture absorption resistance can be obtained, whereby the amount of diffusible hydrogen in the weld metal is 3.5 ml / 100 g or less. We were able to obtain the welding flux.
　一方、比較例Ｎｏ．６～１２は、Ｓｉを含む酸化物を含有する粒子の外表面に、上記所定の被覆率で所定の化合物層が生成されているものが、酸化物を含有する粒子の全粒子数に対して５０％未満であったため、発明例と比較してフラックスの水分量が高くなり、このフラックスを用いて得られた溶接金属中の拡散性水素量が、発明例と比較して高くなった。 On the other hand, Comparative Example No. In Nos. 6 to 12, the outer surface of the particles containing the oxide containing Si has the predetermined compound layer formed at the above-mentioned predetermined coverage, with respect to the total number of particles of the particles containing the oxide. Since it was less than 50%, the water content of the flux was higher than that of the invention example, and the diffusible hydrogen content in the weld metal obtained by using this flux was higher than that of the invention example.
　以上、図面を参照しながら各種の実施の形態について説明したが、本発明はかかる例に限定されないことは言うまでもない。当業者であれば、特許請求の範囲に記載された範疇内において、各種の変更例又は修正例に想到し得ることは明らかであり、それらについても当然に本発明の技術的範囲に属するものと了解される。また、発明の趣旨を逸脱しない範囲において、上記実施の形態における各構成要素を任意に組み合わせてもよい。 Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present invention. Understood. Further, each component in the above-described embodiment may be arbitrarily combined as long as the gist of the invention is not deviated.
　なお、本出願は、２０２０年８月３日出願の日本特許出願（特願２０２０－１３１９３５）に基づくものであり、その内容は本出願の中に参照として援用される。 This application is based on the Japanese patent application filed on August 3, 2020 (Japanese Patent Application No. 2020-131935), the contents of which are incorporated herein by reference.
１　Ｓｉを含む酸化物を含有する粒子
２　化合物層 1 Particles containing oxides containing Si 2 Compound layer

Claims (8)

  1. 　溶接用フラックスであって、
    　前記溶接用フラックスは酸化物を含有する粒子を有し、
    　前記酸化物はＳｉを含み、
    　前記粒子の外表面の少なくとも一部には化合物層が生成されており、
    　前記化合物層は、エリンガム図における５００～１０００℃の温度範囲で、ＳｉＯ２標準生成ギブスエネルギーよりも低い標準生成ギブスエネルギーを有する酸化物を構成する強脱酸元素を含み、
    　前記外表面の５０％以上に前記化合物層が生成されている前記粒子が、前記酸化物を含有する粒子の全粒子数に対して５０％以上の割合で存在する、溶接用フラックス。     Welding flux
    The welding flux has particles containing oxides and has particles.
    The oxide contains Si and contains
    A compound layer is formed on at least a part of the outer surface of the particles.
    The compound layer contains a strongly deoxidizing element constituting an oxide having a standard produced Gibbs energy lower than the SiO 2 standard produced Gibbs energy in the temperature range of 500 to 1000 ° C. in the Ellingham diagram.
    A welding flux in which the particles having the compound layer formed on 50% or more of the outer surface are present at a ratio of 50% or more with respect to the total number of particles containing the oxide.
  2. 　前記強脱酸元素は、
    　エリンガム図における５００～１０００℃の全温度領域において、酸化物標準生成ギブスエネルギーの値が、－８００ｋＪ／ｇ・ｍｏｌＯ２以下である酸化物を構成する元素である、請求項１に記載の溶接用フラックス。     The strongly deoxidizing element is
    The welding element according to claim 1, which is an element constituting an oxide having an oxide standard production Gibbs energy value of −800 kJ / g · molO 2 or less in the entire temperature range of 500 to 1000 ° C. in the Ellingham diagram. flux.
  3. 　前記強脱酸元素は、Ｍｇ、Ｃａ及びＢａから選択された少なくとも一種の元素である、請求項１又は２に記載の溶接用フラックス。 The welding flux according to claim 1 or 2, wherein the strongly deoxidizing element is at least one element selected from Mg, Ca and Ba.
  4. 　前記Ｓｉを含む酸化物は、Ｓｉ単体の酸化物、又は、Ｋ、Ｎａ及びＡｌから選択された少なくとも一種とＳｉとを含有する複合酸化物である、請求項１又は２に記載の溶接用フラックス。 The welding flux according to claim 1 or 2, wherein the oxide containing Si is an oxide of Si alone or a composite oxide containing at least one selected from K, Na and Al and Si. ..
  5. 　溶接用フラックス全質量あたり、
    　全Ｆ量：５．０質量％以上、２０．０質量％以下、
    　全ＳｉのＳｉＯ２換算値：１０．０質量％以上、２５．０質量％以下、
    　全ＡｌのＡｌ２Ｏ３換算値：１４．０質量％以上、３０．０質量％以下、
    　Ｎａ及びＫのいずれか一方又は両方：全ＮａのＮａ２Ｏ換算値及び全ＫのＫ２Ｏ換算値の合計で１．０質量％以上、６．０質量％以下、
    　全ＴｉのＴｉＯ２換算値：０．５質量％以上、５．０質量％以下、
    　全ＭｎのＭｎＯ換算値：０．５質量％以上、１３．０質量％以下、及び
    　全ＦｅのＦｅＯ換算値：０．５質量％以上、７．０質量％以下、
    を含有するとともに、
    　Ｍｇ、Ｃａ及びＢａから選択された少なくとも一種を、
    　全ＭｇのＭｇＯ換算値：１５．０質量％以上、３０．０質量％以下、
    　全ＣａのＣａＯ換算値：７．０質量％以上、３０．０質量％以下、
    　全ＢａのＢａＯ換算値：８．０質量％以下、
    の範囲で含有する、請求項１又は２に記載の溶接用フラックス。     Per total mass of welding flux
    Total F amount: 5.0% by mass or more, 20.0% by mass or less,
    SiO 2 conversion value of all Si: 10.0% by mass or more, 25.0% by mass or less,
    Al 2 O 3 conversion value of all Al: 14.0% by mass or more, 30.0% by mass or less,
    Either or both of Na and K: 1.0% by mass or more and 6.0% by mass or less in total of the Na 2 O conversion value of all Na and the K 2 O conversion value of all K.
    TiO 2 conversion value of all Ti: 0.5% by mass or more, 5.0% by mass or less,
    MnO conversion value of all Mn: 0.5% by mass or more, 13.0% by mass or less, and FeO conversion value of all Fe: 0.5% by mass or more, 7.0% by mass or less,
    As well as containing
    At least one selected from Mg, Ca and Ba,
    MgO conversion value of all Mg: 15.0% by mass or more, 30.0% by mass or less,
    CaO conversion value of all Ca: 7.0% by mass or more, 30.0% by mass or less,
    BaO conversion value of all Ba: 8.0% by mass or less,
    The welding flux according to claim 1 or 2, which is contained in the range of.
  6. 　請求項１又は２に記載の溶接用フラックスを製造する溶接用フラックスの製造方法であって、
    　粉体原料を配合した配合フラックスに結合剤を添加して造粒後、５００～１０００℃の温度で焼成する工程を有し、
    　前記配合フラックスは、前記粉体原料として、Ｓｉを含む酸化物の粉体原料、及び、強脱酸元素を含む金属の粉体原料又は化合物の粉体原料を含有し、
    　前記強脱酸元素は、エリンガム図における５００～１０００℃の温度範囲でＳｉＯ２よりも低い標準生成ギブスエネルギーを有する酸化物を構成する元素である、溶接用フラックスの製造方法。     A method for manufacturing a welding flux according to claim 1 or 2, wherein the welding flux is manufactured.
    It has a step of adding a binder to a blending flux containing a powder raw material, granulating, and then firing at a temperature of 500 to 1000 ° C.
    The compounded flux contains, as the powder raw material, a powder raw material of an oxide containing Si, and a powder raw material of a metal containing a strongly deoxidizing element or a powder raw material of a compound.
    The method for producing a welding flux, wherein the strongly deoxidizing element is an element constituting an oxide having a standard enthalpy of formation lower than SiO 2 in the temperature range of 500 to 1000 ° C. in the Ellingham diagram.
  7. 　前記強脱酸元素を含む金属の粉体原料又は化合物の粉体原料は、Ｍｇを含む粉体原料、Ｃａを含む粉体原料及びＢａを含む粉体原料から選択された少なくとも一種の粉体原料を含有し、
    　前記Ｍｇを含む粉体原料は、Ｍｇを含む粉体原料全質量に対してＭｇを２５質量％以上含有し、
    　前記Ｃａを含む粉体原料は、Ｃａを含む粉体原料全質量に対してＣａを３０質量％以上含有し、
    　前記Ｂａを含む粉体原料は、Ｂａを含む粉体原料全質量に対してＢａを６０質量％以上含有するものであり、
    　前記Ｍｇを含む粉体原料のうち、粒径が７５μｍ以下であるＭｇを含む粉体原料の割合を、前記Ｍｇを含む粉体原料全質量に対する質量％で［ａ］、
    　前記Ｃａを含む粉体原料のうち、粒径が７５μｍ以下であるＣａを含む粉体原料の割合を、前記Ｃａを含む粉体原料全質量に対する質量％で［ｂ］、
    　前記Ｂａを含む粉体原料のうち、粒径が７５μｍ以下であるＢａを含む粉体原料の割合を、前記Ｂａを含む粉体原料全質量に対する質量％で［ｃ］、
    　前記Ｓｉを含む酸化物の粉体原料のうち、粒径が７５μｍ以下であるＳｉを含む酸化物の粉体原料の割合を、前記Ｓｉを含む酸化物の粉体原料全量に対する質量％で［ｄ］としたとき、
    　下記式（１）により得られる値が２．５以上である、請求項６に記載の溶接用フラックスの製造方法。
    　（［ａ］＋［ｂ］＋［ｃ］）／［ｄ］・・・（１）     The powder raw material of the metal containing the strongly deoxidizing element or the powder raw material of the compound is at least one kind of powder raw material selected from the powder raw material containing Mg, the powder raw material containing Ca and the powder raw material containing Ba. Contains,
    The powder raw material containing Mg contains 25% by mass or more of Mg with respect to the total mass of the powder raw material containing Mg.
    The powder raw material containing Ca contains 30% by mass or more of Ca with respect to the total mass of the powder raw material containing Ca.
    The powder raw material containing Ba contains 60% by mass or more of Ba with respect to the total mass of the powder raw material containing Ba.
    The ratio of the powder raw material containing Mg having a particle size of 75 μm or less to the total mass of the powder raw material containing Mg is [a].
    The ratio of the powder raw material containing Ca having a particle size of 75 μm or less to the total mass of the powder raw material containing Ca is [b].
    The ratio of the powder raw material containing Ba having a particle size of 75 μm or less to the total mass of the powder raw material containing Ba is [c].
    The ratio of the powder raw material of the oxide containing Si having a particle size of 75 μm or less to the powder raw material of the oxide containing Si is determined by mass% with respect to the total amount of the powder raw material of the oxide containing Si [d]. ] When
    The method for producing a welding flux according to claim 6, wherein the value obtained by the following formula (1) is 2.5 or more.
    ([A] + [b] + [c]) / [d] ... (1)
  8. 　請求項１又は２に記載の溶接用フラックスを用いたサブマージアーク溶接方法。 Submerged arc welding method using the welding flux according to claim 1 or 2.
PCT/JP2021/025376 2020-08-03 2021-07-05 Welding flux and production method therefor, and submerged arc welding method using same welding flux WO2022030159A1 (en)

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Citations (6)

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JPS62130793A (en) * 1985-12-02 1987-06-13 Nippon Steel Corp Baked flux for submerged arc welding
JPH0237833B2 (en) * 1985-04-19 1990-08-27 Nippon Steel Corp SABUMAAJIAAKUYOSETSUYOSHOSEIFURATSUKUSU
JPH0999392A (en) * 1995-07-28 1997-04-15 Kawasaki Steel Corp Baked flux for submerged arc welding having excellent hygroscopic resistance
JPH11239893A (en) * 1998-02-25 1999-09-07 Mitsui Eng & Shipbuild Co Ltd Welding flux
JP2003039196A (en) * 2001-07-24 2003-02-12 Kobe Steel Ltd Bond flux for submerged arc welding and manufacturing method therefor
WO2018182025A1 (en) * 2017-03-31 2018-10-04 株式会社神戸製鋼所 Flux for submerged arc welding

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JPH0237833A (en) * 1988-07-27 1990-02-07 Nec Corp Output circuit

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0237833B2 (en) * 1985-04-19 1990-08-27 Nippon Steel Corp SABUMAAJIAAKUYOSETSUYOSHOSEIFURATSUKUSU
JPS62130793A (en) * 1985-12-02 1987-06-13 Nippon Steel Corp Baked flux for submerged arc welding
JPH0999392A (en) * 1995-07-28 1997-04-15 Kawasaki Steel Corp Baked flux for submerged arc welding having excellent hygroscopic resistance
JPH11239893A (en) * 1998-02-25 1999-09-07 Mitsui Eng & Shipbuild Co Ltd Welding flux
JP2003039196A (en) * 2001-07-24 2003-02-12 Kobe Steel Ltd Bond flux for submerged arc welding and manufacturing method therefor
WO2018182025A1 (en) * 2017-03-31 2018-10-04 株式会社神戸製鋼所 Flux for submerged arc welding

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