Flux-cored wire, weld joint and weld metal

Abstract

To provide a flux-cored wire that is used in welding of a structure in an extra-low temperature region, from which weld metal having excellent strength and a lateral swelling amount equal to or more than a desired value can be obtained.SOLUTION: A flux-cored wire has regulated contents of Fe, C, Cr, Ni and the like to the total mass of a wire, and contains 0.001 to 0.15 mass% Nb, and 0.005 to 0.30 mass% V. A value A1 calculated by Expression (1) is 0.02 to 0.30, and a value A2 calculated by Expression (2) is 10.0 to 12.3. Expression (1): A1=[Nb]W+[V]W. Expression (2): A2=1.31×(0.98×[Cr]W+[Mo]W+0.7×[Nb]W)-1.1×([Ni]W+35×[C]W+20×[N]W+0.25×[Cu]W), provided that [element]W is a value representing the content of the element in the flux-cored wire by mass%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a flux-cored wire, a welded joint, and a weld metal.

Background Art

[0002] Generally, in order to improve the efficiency of transportation and storage, gas is liquefied at a low temperature and stored in a tank. Therefore, the structural members of the storage tank are required to have low-temperature toughness in the liquefaction temperature range of the stored gas. For example, Patent Document 1 discloses an austenitic stainless steel flux-cored wire capable of obtaining a weld metal having excellent cryogenic toughness near -196°C. The flux-cored wire described in Patent Document 1 has specified contents of C, Si, Mn, P, Ni, Cr, and N, and a value obtained by an equation using the contents of Ni, Cr, Mn, Si, and C in the wire is specified.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in consideration of the environment, hydrogen is considered to be used as a fuel for power generation, automobiles, etc., and the demand for hydrogen is increasing. Along with this, for storage tanks, the requirements for storage tanks that can safely store liquefied hydrogen are also increasing. Specifically, it is required that it can be used even in an extremely low temperature region that is lower than the temperature used in a normal liquefied storage tank, for example, about -253°C or higher. For this reason, the development of a flux-cored wire that can cope with the welding of structures in an even lower temperature region is desired. As an index of the low-temperature toughness of the welding metal for such a low-temperature tank, the value of transverse swelling may be required. However, in the flux-cored wire described in Patent Document 1, transverse swelling is not considered.

[0005] The present invention has been made in view of such problems, and is a flux-cored wire used for welding structures in an extremely low temperature region, which has excellent strength and can obtain a weld metal having a transverse swelling amount equal to or greater than a desired value, and an object of the present invention is to provide a welded joint obtained by using the flux-cored wire and a weld metal.

Means for Solving the Problems

[0006] As a result of intensive studies by the present inventors, in order to obtain a weld metal having excellent strength and transverse swelling amount in an extremely low temperature region, it is effective to control the total amount of Nb and V in the wire and to control the ferrite amount by setting the value obtained by the calculation formula using Cr equivalent and Ni equivalent within a predetermined range. The present invention has been made based on the above findings.

[0007] The above object of the present invention is achieved by the configuration of the following [1] related to the flux-cored wire.

[0008] [1] With respect to the total mass of the wire, Fe: 40 mass% or more and 70 mass% or less, C: 0.001 mass% or more and 0.030 mass% or less, Cr: 14.0 mass% or more and 28.0 mass% or less, Ni: 7.0 mass% or more and 20.0 mass% or less, Nb: 0.001 mass% or more and 0.15 mass% or less, and V: 0.005 mass% or more and 0.30 mass% or less, containing Mo: 4.0 mass% or less, Cu: 0.50 mass% or less, N: 0.020 mass% or less, and Value A1 calculated by the following formula (1): 0.02 or more and 0.30 or less, Value A2 calculated by the following formula (2): 10.0 or more and 12.3 or less, a flux-containing wire characterized by that. A1 = [Nb] W + [V] W ··· Formula (1) A2 = 1.31×(0.98×[Cr] W + [Mo] W + 0.7×[Nb] W ) - 1.1×([Ni] W + 35×[C] W + 20×[N] W + 0.25×[Cu] W ) ··· Formula (2) However, [Nb] W is the value representing the Nb content in the flux-containing wire in mass%, [V] W is the value representing the V content in the flux-containing wire in mass%, [Cr] W is the value representing the Cr content in the flux-containing wire in mass%, [Mo] W is the value representing the Mo content in the flux-containing wire in mass%, [Ni] W is the value representing the Ni content in the flux-containing wire in mass%, [C] W is the value representing the C content in the flux-containing wire in mass%, [N] W is the value representing the N content in the flux-containing wire in mass%, [Cu] W is the value representing the Cu content in the flux-containing wire in mass%.

[0009] Further, the preferred embodiments of the present invention relating to the flux-containing wire relate to the following [2] to [3].

[0010] [2] Further, with respect to the total mass of the wire, Si: 0.10 mass% or more and 1.00 mass% or less, F: 0.10 mass% or more and 0.50 mass% or less, Mn: 0.1 mass% or more and 1.60 mass% or less, TiO2: 4.00 mass% or more and 10.00 mass% or less, ZrO2 conversion value of metallic Zr and Zr compounds: 0.50 mass% or more and 4.00 mass% or less, MgO conversion value of metallic Mg and Mg compounds: 0.05 mass% or more and 1.00 mass% or less, Na: 0.01 mass% or more and 0.50 mass% or less, and K: 0.01 mass% or more and 0.50 mass% or less, are contained, P: 0.030 mass% or less, S: 0.030 mass% or less, Co: 0.300 mass% or less, W: 0.50 mass% or less, REM: 0.500 mass% or less, Ti: 1.0 mass% or less, Al: 0.3 mass% or less, Al2O3: 1.00 mass% or less, Li: 0.50 mass% or less, and the flux-containing wire according to [1] is characterized by this.

[0011] [3] The Ni: 10.0 mass% or more and 13.0 mass% or less, The Cr: 16.5 mass% or more and 18.0 mass% or less, The Mo: 1.7 mass% or more and 2.2 mass% or less, and the flux-containing wire according to [1] or [2] is characterized by this.

[0012] The above object of the present invention is achieved by the configuration of the following [4] related to the welded joint.

[0013] [4] A welded joint, characterized in that it is manufactured by welding using a flux-containing wire according to any one of [1] to [3] with a stainless steel plate as the base material.

[0014] The above object of the present invention is achieved by the following configuration [5] related to the weld metal.

[0015] [5] With respect to the total mass of the weld metal, C: 0.001% by mass or more and 0.040% by mass or less, Cr: 14.0% by mass or more and 22.0% by mass or less, Ni: 7.0% by mass or more and 18.0% by mass or less, Mn: 0.3% by mass or more and 1.5% by mass or less, Nb: 0.001% by mass or more and 0.15% by mass or less, and V: 0.005% by mass or more and 0.30% by mass or less, and contains Si: 1.0% by mass or less, Ti: 1.0% by mass or less, Mo: 4.0% by mass or less, Cu: 0.50% by mass or less, N: 0.020% by mass or less, and the balance is Fe and inevitable impurities, and The value A3 calculated by the following formula (3): 0.02 or more and 0.30 or less, and The value A4 calculated by the following formula (4): 10.0 or more and 12.3 or less, and a weld metal characterized by this. A3 = [Nb] M + [V] M ··· Formula (3) A4 = 1.18 × ([Cr] M + [Mo] M + 0.7 × [Nb] M ) - [Ni] M - 35 × [C] M - 20 × [N] M - 0.25 × [Cu] M ··· Formula (4) However, [Nb] M is the value representing the Nb content in the weld metal in mass%, and [V] Mis the value of the V content in the weld metal, expressed in mass%, [Cr] M is the value of the Cr content in the weld metal, expressed in mass%, [Mo] M is the value of the Mo content in the weld metal, expressed in mass%, [Ni] M is the value of the Ni content in the weld metal, expressed in mass%, [C] M is the value of the C content in the weld metal, expressed in mass%, [N] M is the value of the N content in the weld metal, expressed in mass%, [Cu] M is the value of the Cu content in the weld metal, expressed in mass%.

[0016] Moreover, a preferred embodiment of the present invention relating to the weld metal relates to the following [6].

[0017] [6] P: 0.030 mass% or less, S: 0.030 mass% or less, Co: 0.500 mass% or less, W: 0.50 mass% or less, the Ni: 12.0 mass% or more and 14.0 mass% or less, the Cr: 17.0 mass% or more and 19.0 mass% or less, the Mo: 1.7 mass% or more and 2.5 mass% or less, characterized in that the weld metal according to [5].

Advantages of the Invention

[0018] According to the present invention, it is possible to provide a flux-cored wire capable of obtaining a weld metal having excellent strength and a lateral bulging amount equal to or more than a desired value. Further, according to the present invention, by using the flux-cored wire, it is possible to provide a welded joint suitably used in an extremely low temperature environment. Furthermore, according to the present invention, it is possible to provide a weld metal having excellent strength and a lateral bulging amount equal to or more than a desired value.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.

[0020] [Flux-containing wire] The flux-containing wire according to this embodiment is a stainless steel flux-containing wire in which a stainless steel sheath is filled with flux. Further, the contents of Fe, C, Cr, Ni, Nb, V, Mo, Cu, and N in the wire are controlled, and the total content of Nb and V and the value calculated by a specific formula using the contents of Cr, Mo, Nb, Ni, C, N, and Cu are controlled.

[0021] Hereinafter, each component contained in the flux-containing wire according to this embodiment will be described in detail. In this specification, the flux-containing wire may be simply referred to as a wire.

[0022] <Fe: 40 mass% or more and 70 mass% or less> Fe is the main component constituting the sheath of the flux-containing wire according to this embodiment. Due to the relationship of the contents of flux components and the like contained in the wire, the Fe content with respect to the total mass of the wire is 40 mass% or more, preferably 45 mass% or more, and more preferably 50 mass% or more. On the other hand, the Fe content with respect to the total mass of the wire is 70 mass% or less, preferably 65 mass% or less, and more preferably 60 mass% or less.

[0023] <C: 0.001 mass% or more and 0.030 mass% or less> While C is an element that improves the tensile strength of the weld metal, it segregates to the final solidification part of the weld metal, lowers the melting point of the melt, and deteriorates the high-temperature crack resistance. If the C content in the wire is less than 0.001% by mass, a weld metal with good tensile strength cannot be obtained. Therefore, the C content based on the total mass of the wire is 0.001% by mass or more, preferably 0.003% by mass or more, and more preferably 0.005% by mass or more. On the other hand, when the C content in the wire exceeds 0.030% by mass, the high-temperature crack susceptibility increases. Therefore, the C content based on the total mass of the wire is 0.030% by mass or less, preferably 0.025% by mass or less, and more preferably 0.020% by mass or less.

[0024] <Cr: 14.0% by mass or more and 28.0% by mass or less> Cr is a component that has the effect of improving the strength of the weld metal and stabilizing the ferrite phase. If the Cr content in the wire is less than 14.0% by mass, a weld metal with sufficient strength cannot be obtained. Therefore, the Cr content based on the total mass of the wire is 14.0% by mass or more, preferably 15.0% by mass or more, and more preferably 16.5% by mass or more. On the other hand, when the Cr content in the wire exceeds 28.0% by mass, the toughness of the weld metal deteriorates, and the solidification segregation of Cr is promoted, resulting in deterioration of the high-temperature crack resistance. Therefore, the Cr content based on the total mass of the wire is 28.0% by mass or less, preferably 23.0% by mass or less, and more preferably 18.0% by mass or less.

[0025] <Ni: 7.0% by mass or more and 20.0% by mass or less> Ni is a component that has the effect of stabilizing the austenite structure. If the Ni content in the wire is less than 7.0% by mass, the austenite structure becomes unstable. Therefore, the Ni content with respect to the total mass of the wire is 7.0% by mass or more, preferably 8.5% by mass or more, and more preferably 10.0% by mass or more. On the other hand, if the Ni content in the wire exceeds 20.0% by mass, the solid solubility of C and N decreases, and blowholes are likely to occur. Therefore, the Ni content with respect to the total mass of the wire is 20.0% by mass or less, preferably 16.5% by mass or less, and more preferably 13.0% by mass or less.

[0026] <Nb: 0.001% by mass or more and 0.15% by mass or less> Nb is a component that has the effect of forming carbides to reduce the amount of dissolved C and improving the absorbed energy and lateral bulging amount. In the present embodiment, in particular, for the purpose of making the lateral bulging amount equal to or greater than a desired value, it is necessary to appropriately control the contents of Nb and V described later. If the Nb content in the wire is less than 0.001% by mass, the desired lateral bulging amount cannot be obtained. Therefore, the Nb content with respect to the total mass of the wire is 0.001% by mass or more, preferably 0.02% by mass or more, and more preferably 0.04% by mass or more. On the other hand, if the Nb content in the wire exceeds 0.15% by mass, the absorbed energy of the weld metal decreases. Therefore, the Nb content with respect to the total mass of the wire is 0.15% by mass or less, preferably 0.10% by mass or less, and more preferably 0.08% by mass or less.

[0027] <V: 0.005% by mass or more and 0.30% by mass or less> V, like Nb, is a component that has the effect of forming carbides, reducing the amount of dissolved C, and improving the absorbed energy and lateral bulging amount. In order to make the lateral bulging amount equal to or greater than a desired value, it is necessary to appropriately control the V content as well. If the V content in the wire is less than 0.005% by mass, the desired lateral bulging amount cannot be obtained. Therefore, the V content based on the total mass of the wire should be 0.005% by mass or more, preferably 0.03% by mass or more, and more preferably 0.05% by mass or more. On the other hand, if the V content in the wire exceeds 0.30% by mass, the absorbed energy of the weld metal decreases. Therefore, the V content based on the total mass of the wire should be 0.30% by mass or less, preferably 0.20% by mass or less, and more preferably 0.10% by mass or less.

[0028] <Mo: 4.0% by mass or less> Mo, like Cr, is a component that has the effect of improving the strength of the weld metal. However, in the flux-cored wire according to this embodiment, it is not necessarily required to contain Mo, and it may be 0% by mass. However, when Mo is contained in the wire for the purpose of improving the strength of the weld metal, the Mo content based on the total mass of the wire is preferably 1.0% by mass or more, and more preferably 1.7% by mass or more. On the other hand, if the Mo content in the wire exceeds 4.0% by mass, the toughness of the weld metal deteriorates, the solidification segregation of Mo is promoted, and the high-temperature crack resistance deteriorates. Therefore, the Mo content based on the total mass of the wire should be 4.0% by mass or less, preferably 3.1% by mass or less, and more preferably 2.2% by mass or less.

[0029] <Cu: 0.50% by mass or less> Cu is a component having the effect of stabilizing the austenite structure. However, in the flux-cored wire according to the present embodiment, it is not necessarily required to contain Cu, and it may be 0% by mass. However, when Cu is contained in the wire for the purpose of stabilizing the austenite structure, the Cu content with respect to the total mass of the wire is preferably 0.001% by mass or more, and more preferably 0.005% by mass or more. On the other hand, when the Cu content in the wire exceeds 0.50% by mass, the high-temperature crack resistance of the weld metal deteriorates. Therefore, the Cu content with respect to the total mass of the wire is 0.50% by mass or less, preferably 0.25% by mass or less, and more preferably 0.15% by mass or less.

[0030] <N: 0.020% by mass or less> N is a solid solution strengthening element and has the effect of improving the strength of the weld metal. However, in the flux-cored wire according to the present embodiment, it is not necessarily required to contain N, and it may be 0% by mass. However, when N is contained in the wire for the purpose of improving the strength of the weld metal, the N content with respect to the total mass of the wire is preferably 0.002% by mass or more, and more preferably 0.005% by mass or more. On the other hand, when the N content exceeds 0.020% by mass, the absorbed energy of the weld metal decreases. Therefore, the N content with respect to the total mass of the wire is 0.020% by mass or less, preferably 0.015% by mass or less, and more preferably 0.012% by mass or less.

[0031] <Value A1 calculated by formula (1): 0.02 or more and 0.30 or less> As described above, Nb and V are components that greatly affect the absorbed energy and transverse bulge amount of the weld metal. Therefore, by controlling the respective contents of Nb and V in the wire and appropriately controlling the total value of the contents of Nb and V, a desired transverse bulge amount can be obtained. If the value A1 calculated by the following formula (1), which is the total value of the contents of Nb and V in the wire, is less than 0.02, a desired absorbed energy and transverse bulge amount cannot be obtained. Therefore, the value A1 should be 0.02 or more, preferably 0.04 or more, and more preferably 0.06 or more. On the other hand, when the value A1 calculated by the following formula (1) exceeds 0.30, the absorbed energy of the weld metal decreases. Therefore, the value A1 should be 0.30 or less, preferably 0.20 or less, and more preferably 0.12 or less.

[0032] A1 = [Nb] W + [V] W ··· Formula (1) However, [Nb] W is the value representing the Nb content in the flux-cored wire in mass%, and [V] W is the value representing the V content in the flux-cored wire in mass%.

[0033] <Value A2 calculated by formula (2): 10.0 or more and 12.3 or less> In the present embodiment, by adjusting the parameters using the contents of Cr, Mo, and Nb, which are ferrite-stabilizing elements in the wire, and the contents of Ni, C, N, and Cu, which are austenite-stabilizing elements, the ferrite amount of the weld metal can be controlled within a desired range. More specifically, the following formula (2) is a formula for subtracting the Ni equivalent amount obtained by converting the degree of austenite-stabilizing element into the nickel amount from the Cr equivalent amount obtained by converting the degree of ferrite-stabilizing element into the chromium amount. Therefore, by defining the value A2 calculated by this formula (2), it is possible to prevent the ferrite from becoming excessive or insufficient and achieve a balance between strength and toughness.

[0034] When the value A2 calculated by the following formula (2) is less than 10.0, the amount of ferrite becomes too small and the strength of the weld metal decreases. Therefore, the value A2 should be 10.0 or more, preferably 11.0 or more, and more preferably 11.5 or more. On the other hand, when the value A2 calculated by the following formula (2) exceeds 12.3, the amount of ferrite becomes too large and the low-temperature toughness and transverse bulge of the weld metal deteriorate. Therefore, the value A2 should be 12.3 or less, preferably 12.1 or less, and more preferably 11.9 or less.

[0035] A2 = 1.31×(0.98×[Cr] W + [Mo] W + 0.7×[Nb] W ) - 1.1×([Ni] W + 35×[C] W + 20×[N] W + 0.25×[Cu] W ) ··· Formula (2) However, [Cr] W is the value representing the Cr content in the flux-cored wire in mass%, [Mo] W is the value representing the Mo content in the flux-cored wire in mass%, [Nb] W is the value representing the Nb content in the flux-cored wire in mass%, [Ni] W is the value representing the Ni content in the flux-cored wire in mass%, [C] W is the value representing the C content in the flux-cored wire in mass%, [N] W is the value representing the N content in the flux-cored wire in mass%, [Cu] W is the value representing the Cu content in the flux-cored wire in mass%.

[0036] In the flux-cored wire according to this embodiment, if each component is within the above content range, the problems of the present invention can be solved. In addition, in order to further improve the welding workability and the mechanical properties of the weld metal, it is preferable that the wire further contains Si, F, Mn, TiO2, metallic Zr, Zr compounds, metallic Mg, Mg compounds, Na, and K. It is also preferable that the contents of P, S, Co, W, REM, Ti, Al, Al2O3, and Li with respect to the total mass of the wire are defined. Hereinafter, the preferable ranges of these contents will be described.

[0037] <Si: 0.10 mass% or more and 1.00 mass% or less> Si is a component having the effects of improving the strength of the weld metal, ensuring low-temperature toughness, and suppressing the generation of blowholes. When the Si content in the wire is 0.10 mass% or more, the above effects can be obtained. Therefore, the Si content with respect to the total mass of the wire is preferably 0.10 mass% or more, and more preferably 0.40 mass% or more. On the other hand, when the Si content in the wire is 1.00 mass% or less, it is possible to prevent deterioration of the high-temperature crack resistance. Therefore, the Si content with respect to the total mass of the wire is preferably 1.00 mass% or less, and more preferably 0.70 mass% or less. Note that the Si content in the wire represents the total content of all Si contained in Si alone, Si alloys, and Si compounds in the wire.

[0038] <F: 0.10 mass% or more and 0.50 mass% or less> In this embodiment, for the purpose of suppressing the sputtering amount and stabilizing the arc, F can be contained in the wire. When the F content in the wire is 0.10% by mass or more, the effect of suppressing the sputtering amount and stabilizing the arc can be obtained. Therefore, when F is contained in the wire, the F content with respect to the total mass of the wire is preferably 0.10% by mass or more, and more preferably 0.15% by mass or more. On the other hand, when the F content in the wire is 0.50% by mass or less, sputtering and fume can be suppressed. Therefore, the F content with respect to the total mass of the wire is preferably 0.50% by mass or less, and more preferably 0.30% by mass or less.

[0039] <Mn: 0.1% by mass or more and 1.60% by mass or less> Since Mn has the effect of suppressing blowholes caused by oxygen-based gases due to its deoxidizing effect and also has the effect of stabilizing the austenite structure, Mn may be contained in the wire in this embodiment. When the Mn content in the wire is 0.1% by mass or more, a sufficient deoxidizing effect can be obtained. Therefore, the amount of Mn added with respect to the total mass of the wire is preferably 0.1% by mass or more, and more preferably 0.50% by mass or more. On the other hand, when the Mn content is 1.60% by mass or less, a decrease in the lateral bulging amount can be suppressed. Therefore, the Mn content with respect to the total mass of the wire is preferably 1.60% by mass or less, and more preferably 1.50% by mass or less.

[0040] <TiO2: 4.00% by mass or more and 10.00% by mass or less> TiO₂ is the main component of the slag former, which can form a uniform and well-coated slag and has the effect of improving arc stability. In addition, TiO₂ also has the effect of raising the melting point of the slag and flattening the bead shape in all-position welding. When the TiO₂ content in the wire is 4.00% by mass or more, the above effects can be fully obtained. Therefore, the TiO₂ content based on the total mass of the wire is preferably 4.00% by mass or more, and more preferably 5.00% by mass or more. On the other hand, when the TiO₂ content in the wire is 10.00% by mass or less, the flux is easily melted, and the generation of slag wrapping can be suppressed. Therefore, the TiO₂ content based on the total mass of the wire is preferably 10.00% by mass or less, and more preferably 7.0% by mass or less. Note that the TiO₂ content in the wire represents the TiO₂ conversion value of the Ti compounds contained in the wire. Here, the Ti compounds mean Ti oxides, Ti nitrides, etc.

[0041] <ZrO₂ conversion value of metallic Zr and Zr compounds: 0.50% by mass or more and 4.00% by mass or less> ZrO₂ is a component that has the effect of accelerating slag solidification and forming a flat bead shape in the vertical and upward positions. When the ZrO₂ conversion value in the wire is 0.50% by mass or more, the above effects can be fully obtained. Therefore, the ZrO₂ conversion value based on the total mass of the wire is preferably 0.50% by mass or more, and more preferably 1.00% by mass or more. On the other hand, when the ZrO₂ conversion value in the wire is 4.00% by mass or less, good slag coating property and slag peeling property can be obtained. Therefore, the ZrO₂ conversion value based on the total mass of the wire is preferably 4.00% by mass or less, and more preferably 2.00% by mass or less. Note that in this embodiment, the ZrO₂ conversion value is the value obtained by converting all the Zr contained in metallic Zr and Zr compounds into ZrO₂. Here, metallic Zr means the total amount of Zr contained in Zr single body and Zr alloy. Also, Zr compounds mean Zr oxides, etc.

[0042] <MgO equivalent value of metallic Mg and Mg compounds: 0.05 mass% or more and 1.00 mass% or less> Metallic Mg and Mg compounds are components that have the effect of raising the slag solidification point and improving arc stability. When the MgO equivalent value is 0.05 mass% or more, the above effects can be sufficiently obtained. Therefore, the MgO equivalent value in the wire is preferably 0.05 mass% or more, more preferably 0.15 mass% or more, based on the total mass of the wire. On the other hand, when the MgO equivalent value is 1.00 mass% or less, deterioration of the bead shape can be prevented. Therefore, the MgO equivalent value is preferably 1.00 mass% or less, more preferably 0.30 mass% or less. In this embodiment, the MgO equivalent value is the value obtained by converting all Mg contained in metallic Mg and Mg compounds into MgO. Here, metallic Mg means the total amount of Mg contained in Mg alone and Mg alloys. Also, Mg compounds mean Mg oxides and the like.

[0043] <Na: 0.01 mass% or more and 0.50 mass% or less> Alkali metals such as Na are components that have the effect of improving arc stability and can be contained in the wire as fluorides or complex oxides. When the Na content in the wire is 0.01 mass% or more, the effect of improving arc stability can be obtained. Therefore, the Na content based on the total mass of the wire is preferably 0.01 mass% or more, more preferably 0.10 mass% or more. On the other hand, when the Na content in the wire is 0.50 mass% or less, a decrease in the slag melting point can be suppressed and the bead shape in all-position welding can be improved. Therefore, the Na content based on the total mass of the wire is preferably 0.50 mass% or less, more preferably 0.20 mass% or less. Note that Na exists in the wire, for example, as Na2O.

[0044] <K: 0.01 mass% or more and 0.50 mass% or less> Alkali metals such as K are components that have the effect of improving arc stability, similar to the above-mentioned Na, and can be contained in the wire as fluorides or complex oxides. When the K content in the wire is 0.01% by mass or more, the effect of improving arc stability can be obtained. Therefore, the K content relative to the total mass of the wire is preferably 0.01% by mass or more, and more preferably 0.10% by mass or more. On the other hand, when the K content in the wire is 0.50% by mass or less, a decrease in the slag melting point can be suppressed, and the bead shape in all-position welding can be improved. Therefore, the K content relative to the total mass of the wire is preferably 0.50% by mass or less, and more preferably 0.20% by mass or less. Note that K exists in the wire, for example, as K2O or K2SiF6, etc.

[0045] <P: 0.030% by mass or less> P is an inevitable impurity in the wire. Since the lower temperature toughness decreases as the P content in the weld metal increases, it is preferable that the P content in the welding wire is less. Therefore, the P content relative to the total mass of the wire is preferably 0.030% by mass or less, and more preferably 0.020% by mass or less.

[0046] <S: 0.030% by mass or less> S is an inevitable impurity in the wire, similar to P. Since the lower temperature toughness decreases as the S content in the weld metal increases, it is preferable that the S content in the welding wire is less. Therefore, the S content relative to the total mass of the wire is preferably 0.030% by mass or less, and more preferably 0.010% by mass or less.

[0047] <Co: 0.300% by mass or less> Since Co is a component having the effect of adjusting the toughness of the weld metal, Co can be contained in the wire as necessary. When the Co content in the wire is 0.300% by mass or less, a decrease in the strength of the weld metal can be suppressed. Therefore, the Co content with respect to the total mass of the wire is preferably 0.300% by mass or less, and more preferably 0.200% by mass or less.

[0048] <W: 0.50% by mass or less> W is a solid solution strengthening element in steel and is a component having the effect of dissolving in the weld metal and improving the strength of the weld metal. Therefore, W can be contained in the wire as necessary. When the W content in the wire is 0.50% by mass or less, deterioration of toughness can be suppressed. Therefore, the W content with respect to the total mass of the wire is preferably 0.50% by mass or less, and more preferably 0.20% by mass or less.

[0049] <REM: 0.500% by mass or less> Since REM (rare earth element) is a deoxidizing element, REM can be contained in the wire as necessary. However, when the REM content in the wire is 0.500% by mass or less, a decrease in welding workability can be suppressed. Therefore, the REM content with respect to the total mass of the wire is preferably 0.500% by mass or less, and more preferably 0.400% by mass or less. Note that REM means 15 lanthanoid series rare earth elements from La to Lu in the periodic table. These elements may be added alone or in combination of two or more.

[0050] <Ti: 1.0% by mass or less> Since Ti is a component that has the effect of improving the toughness of the weld metal, Ti can be contained in the wire as necessary. When the Ti content in the wire is 1.0 mass% or less, the oxygen amount in the weld metal can be reduced, and the toughness of the weld metal can be adjusted to a desired range. Therefore, the Ti content based on the total mass of the wire is preferably 1.0 mass% or less, and more preferably 0.8 mass% or less. Note that the Ti content in the wire represents the content of all metallic Ti contained in elemental Ti and Ti alloys contained in the wire.

[0051] <Al: 0.3 mass% or less> Since Al is a component that has a deoxidizing effect and has the effect of stabilizing the toughness of the weld metal, Al can be contained in the wire as necessary. When the Al content in the wire is 0.3 mass% or less, the yield of alloying elements into the weld metal can be appropriately adjusted, and excessive increase in strength can be suppressed. Therefore, the Al content based on the total mass of the wire is preferably 0.3 mass% or less, and more preferably 0.1 mass% or less. Note that the Al content in the wire represents the content of all metallic Al contained in elemental Al and Al alloys contained in the wire.

[0052] <Al2O3: 1.00 mass% or less> Since Al2O3 is a slag former and is a component that has the effect of improving the bead shape, Al2O3 can be contained in the wire as necessary. When Al2O3 in the wire is 1.00 mass% or less, good slag detachability can be obtained. Therefore, the Al2O3 content based on the total mass of the wire is preferably 1.00 mass% or less, and more preferably 0.20 mass% or less. Note that the Al2O3 content in the wire represents the value obtained by converting the Al in Al compounds such as Al oxides contained in the wire into Al2O3.

[0053] <Li: 0.50 mass% or less> Alkali metals such as Li, similar to the above-mentioned Na and K, are components having the effect of improving arc stability and can be contained in the wire as fluorides or complex oxides. Further, when the Li content in the wire is 0.50% by mass or less, a decrease in the slag melting point can be suppressed, and the bead shape in all-position welding can be improved. Therefore, the Li content based on the total mass of the wire is preferably 0.50% by mass or less, and more preferably 0.20% by mass or less.

[0054] <The balance of the flux-cored wire> The flux-cored wire in the present embodiment contains Fe, C, Cr, Ni, Nb, and V as essential components and can contain Mo, Cu, and N. The total content of these components is preferably 80% by mass or more, more preferably 83% by mass or more, and even more preferably 85% by mass or more based on the total mass of the wire. Further, the wire may further contain Si, F, Mn, TiO2, ZrO2, MgO, Na, K, P, S, Co, W, REM, Ti, Al, Al2O3, Li, etc. Furthermore, examples of the balance of these components include Ca, Ba, Ta, Bi, etc.

[0055] The method for manufacturing the flux-cored wire according to the present embodiment is not particularly limited and can be manufactured by a general manufacturing process. For example, it may be manufactured by a process of forming a stainless steel hoop into a U shape, filling the U-shaped formed hoop with flux, then forming it into a cylindrical mold filled with flux, and drawing the wire to the target diameter.

[0056] The material of the outer skin can be used without particular limitation such as the steel type of stainless steel, as long as the content of each component in the total mass of the flux-cored wire is controlled within the above range.

[0057] The flux-cored wire according to this embodiment can be suitably used, for example, for welding low-temperature steels such as 5% Ni steel and various austenitic stainless steels. Note that the shielding gas used is not particularly limited. For example, Ar gas, carbon dioxide gas (carbon dioxide, CO2), oxygen gas (O2), and a mixed gas thereof can be used. These may contain oxygen, nitrogen, hydrogen, etc. as inevitable impurities.

[0058] [Welded joint] The welded joint according to this embodiment is manufactured by welding using the above flux-cored wire with a stainless steel plate as the base material.

[0059] [Weld metal] The weld metal according to this embodiment is formed, for example, by welding using the above flux-cored wire, and has excellent strength and lateral bulge amount. Hereinafter, the components contained in the weld metal according to this embodiment and their contents will be described in detail. Note that each element is defined by a value obtained by taking the total amount of components contained in the weld metal in a predetermined region not affected by the composition of the base material as the content per total mass of the weld metal. The contents of the respective components in the weld metal according to this embodiment will be described below.

[0060] <C: 0.001 mass% or more and 0.040 mass% or less> C is a component that stabilizes the austenite phase in the weld metal and makes it difficult for the transformation to the martensite phase to occur. Also, C is a component that contributes to the increase in the strength of the weld metal. When the C content in the weld metal is less than 0.001% by mass, a weld metal having good tensile strength cannot be obtained. Therefore, the C content with respect to the total mass of the weld metal is 0.001% by mass or more, preferably 0.005% by mass or more, and more preferably 0.008% by mass or more. On the other hand, when the C content in the weld metal exceeds 0.040% by mass, the strength rises excessively and it becomes difficult to obtain excellent cryogenic toughness. Therefore, the C content with respect to the total mass of the weld metal is 0.040% by mass or less, preferably 0.030% by mass or less, and more preferably 0.025% by mass or less.

[0061] <Cr: 14.0% by mass or more and 22.0% by mass or less> Cr is a component that stabilizes the ferrite phase in the weld metal and makes it difficult for the transformation to martensite to occur. When the Cr content in the weld metal is less than 14.0% by mass, the ferrite phase becomes unstable and excellent cryogenic toughness cannot be obtained. Therefore, the Cr content with respect to the total mass of the weld metal is 14.0% by mass or more, preferably 16.0% by mass or more, and more preferably 17.0% by mass or more. On the other hand, when the Cr content in the weld metal exceeds 22.0% by mass, the ferrite phase is excessively stabilized and the cryogenic toughness decreases. Therefore, the Cr content with respect to the total mass of the weld metal is 22.0% by mass or less, preferably 20.0% by mass or less, and more preferably 19.0% by mass or less.

[0062] <Ni: 7.0% by mass or more and 18.0% by mass or less> Ni is a component that stabilizes the austenite phase in the weld metal and makes it difficult for transformation to martensite to occur. When the Ni content in the weld metal is less than 7.0% by mass, the austenite phase becomes unstable and the extremely low temperature toughness decreases. Therefore, the Ni content with respect to the total mass of the weld metal is 7.0% by mass or more, preferably 11.0% by mass or more, and more preferably 12.0% by mass or more. On the other hand, when the Ni content in the weld metal exceeds 18.0% by mass, the austenite phase is excessively stabilized and excellent extremely low temperature toughness cannot be obtained. Therefore, the Ni content in the weld metal is 18.0% by mass or less, preferably 15.0% by mass or less, and more preferably 14.0% by mass or less.

[0063] <Mn: 0.3% by mass or more and 1.5% by mass or less> Mn is an austenite stabilizing element and is a component that has the effect of removing oxygen in the weld metal as slag as a deoxidizer and improving the mechanical strength. When the Mn content in the weld metal is less than 0.3% by mass, the deoxidation effect is insufficient and the amount of oxygen in the weld metal increases, so excellent extremely low temperature toughness cannot be obtained. Therefore, the Mn content with respect to the total mass of the weld metal is 0.3% by mass or more, preferably 0.4% by mass or more, and more preferably 0.5% by mass or more. On the other hand, when the Mn content in the weld metal exceeds 1.5% by mass, the strength of the weld metal rises excessively and the extremely low temperature toughness decreases. Therefore, the Mn content with respect to the total mass of the weld metal is 1.5% by mass or less, preferably 1.0% by mass or less, and more preferably 0.9% by mass or less.

[0064] <Nb: 0.001% by mass or more and 0.15% by mass or less> Nb is a component that has the effect of forming carbides in the weld metal to reduce the amount of dissolved C, and improving the absorbed energy and the transverse swelling amount. When the Nb content in the weld metal is less than 0.001% by mass, the desired transverse swelling amount cannot be obtained. Therefore, the Nb content with respect to the total mass of the weld metal is 0.001% by mass or more, preferably 0.02% by mass or more, and more preferably 0.04% by mass or more. On the other hand, when the Nb content in the weld metal exceeds 0.15% by mass, the absorbed energy of the weld metal decreases. Therefore, the Nb content with respect to the total mass of the weld metal is 0.15% by mass or less, preferably 0.10% by mass or less, and more preferably 0.08% by mass or less.

[0065] <V: 0.005% by mass or more and 0.30% by mass or less> Similar to Nb, V is a component that has the effect of forming carbides in the weld metal to reduce the amount of dissolved C, and improving the absorbed energy and the transverse swelling amount. When the V content in the weld metal is less than 0.005% by mass, the desired transverse swelling amount cannot be obtained. Therefore, the V content with respect to the total mass of the weld metal is 0.005% by mass or more, preferably 0.02% by mass or more, and more preferably 0.04% by mass or more. On the other hand, when the V content in the weld metal exceeds 0.30% by mass, the absorbed energy of the weld metal decreases. Therefore, the V content with respect to the total mass of the weld metal is 0.30% by mass or less, preferably 0.20% by mass or less, and more preferably 0.10% by mass or less.

[0066] <Si: 1.0% by mass or less> Si is a component that has the effect of promoting deoxidation. However, in the weld metal according to this embodiment, Si may not be contained and may be 0% by mass. When Si is contained in the weld metal for the purpose of ensuring the strength and low-temperature toughness of the weld metal, the Si content in the weld metal is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, based on the total mass of the weld metal. On the other hand, when the Si content in the weld metal exceeds 1.0% by mass, the crystal strength of the weld metal decreases, and excellent ultra-low temperature toughness cannot be obtained. Therefore, the Si content based on the total mass of the weld metal is 1.0% by mass or less, preferably 0.6% by mass or less, more preferably 0.5% by mass or less.

[0067] <Ti: 1.0% by mass or less> Ti is a component that has the effect of improving the toughness of the weld metal. However, when it is contained in the weld metal in an amount exceeding a predetermined amount, the strength rises excessively and causes a decrease in toughness. Therefore, the Ti content based on the total mass of the weld metal is 1.0% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less.

[0068] <Mo: 4.0% by mass or less> Mo is a component that has the effect of improving the strength of the weld metal. However, when it is contained in the weld metal in an amount exceeding a predetermined amount, the strength rises excessively and causes a decrease in toughness. Therefore, the Mo content based on the total mass of the weld metal is 4.0% by mass or less, preferably 3.0% by mass or less, more preferably 2.5% by mass or less. Also, the Mo content based on the total mass of the weld metal is preferably 1.7% by mass or more.

[0069] <Cu: 0.50% by mass or less> Cu is a component that has the effect of improving the strength of the weld metal. However, when it is contained in the weld metal in an amount exceeding a predetermined amount, the strength rises excessively and causes a decrease in toughness. Therefore, the Cu content based on the total mass of the weld metal is 0.50% by mass or less, preferably 0.20% by mass or less, more preferably 0.10% by mass or less.

[0070] <N: 0.020 mass% or less> N is a component that stabilizes the austenite phase in the weld metal and makes it difficult for the transformation to the martensite phase to occur. Also, N is a component that contributes to the increase in the strength of the weld metal. When the N content in the weld metal exceeds 0.020 mass%, the strength excessively increases and it becomes difficult to obtain excellent cryogenic toughness. Therefore, the N content with respect to the total mass of the weld metal is 0.020 mass% or less, preferably 0.018 mass% or less, and more preferably 0.015 mass% or less.

[0071] <Value A3 calculated by the following formula (3): 0.02 or more and 0.30 or less> As described above, Nb and V are components that greatly affect the absorbed energy and transverse bulge amount of the weld metal. Therefore, by controlling the respective contents of Nb and V in the weld metal and appropriately controlling the total value of the contents of Nb and V, a desired transverse bulge amount can be obtained. When the value A3 calculated by the following formula (3), which is the total value of the contents of Nb and V in the weld metal, is less than 0.02, a desired absorbed energy and transverse bulge amount cannot be obtained. Therefore, the value A3 is 0.02 or more, preferably 0.04 or more, and more preferably 0.06 or more. On the other hand, when the value A3 calculated by the following formula (3) exceeds 0.30, the absorbed energy of the weld metal decreases. Therefore, the value A3 is 0.30 or less, preferably 0.20 or less, and more preferably 0.15 or less. A3 = [Nb] M + [V] M ··· Formula (3) However, [Nb] M is the value representing the Nb content in the weld metal in mass%, and [V] M is the value representing the V content in the weld metal in mass%.

[0072] <Value A4 calculated by the following formula (4): 7.6 or more and 10.3 or less> In this embodiment, by adjusting the parameters using the contents of Cr, Mo, and Nb, which are ferrite-stabilizing elements in the weld metal, and the contents of Ni, C, N, and Cu, which are austenite-stabilizing elements, the ferrite content of the weld metal can be controlled within a desired range. More specifically, the following formula (4) is a formula for subtracting the equivalent Ni amount obtained by converting the degree as an austenite-stabilizing element to the nickel amount from the equivalent Cr amount obtained by converting the degree as a ferrite-stabilizing element to the chromium amount. Therefore, by defining the value A4 calculated by this formula (4), it is possible to prevent the ferrite from becoming excessive or insufficient, and to achieve a balance between strength and toughness.

[0073] When the value A4 calculated by the following formula (4) is less than 7.6, the ferrite content becomes too small and the strength of the weld metal decreases. Therefore, the value A4 is preferably 7.6 or more, more preferably 8.0 or more, and even more preferably 8.5 or more. On the other hand, when the value A4 calculated by the following formula (4) exceeds 10.3, the ferrite content becomes too large and the low-temperature toughness and transverse bulge of the weld metal deteriorate. Therefore, the value A4 is preferably 10.3 or less, more preferably 10.0 or less, and even more preferably 9.5 or less.

[0074] A4 = 1.18×([Cr] M + [Mo] M + 0.7×[Nb] M ) - [Ni] M - 35×[C] M - 20×[N] M - 0.25×[Cu] M ) ··· Formula (4) However, [Cr] M is the value representing the Cr content in the weld metal in mass%, [Mo] M is the value representing the Mo content in the weld metal in mass%, [Nb] M is the value representing the Nb content in the weld metal in mass%, [Ni] M is the value representing the Ni content in the weld metal in mass%, [C] M is the value representing the C content in the weld metal in mass%, [N]M is the value representing the N content in the weld metal in mass%, and [Cu] M is the value representing the Cu content in the weld metal in mass%.

[0075] <P: 0.030 mass% or less> P is an inevitable impurity in the weld metal. Since the extremely low temperature toughness decreases as the P content in the weld metal increases, it is preferable that the P content in the weld metal is less. Therefore, the P content with respect to the total mass of the weld metal is preferably 0.030 mass% or less, and more preferably 0.020 mass% or less.

[0076] <S: 0.030 mass% or less> S is, like P, an inevitable impurity in the weld metal. Since the extremely low temperature toughness decreases as the S content in the weld metal increases, it is preferable that the S content in the weld metal is less. Therefore, the S content with respect to the total mass of the weld metal is preferably 0.030 mass% or less, and more preferably 0.010 mass% or less.

[0077] <Co: 0.500 mass% or less> Co is a component having the effect of adjusting the toughness of the weld metal, so Co can be contained in the weld metal as necessary. When the Co content in the weld metal is 0.500 mass% or less, a decrease in strength can be suppressed. Therefore, when Co is contained in the weld metal, the Co content with respect to the total mass of the weld metal is preferably 0.500 mass% or less, and more preferably 0.200 mass% or less.

[0078] <W: 0.50 mass% or less> W is a component having the effect of improving the strength of the weld metal, so W can be contained in the weld metal as necessary. However, if W is contained in the weld metal in an amount exceeding a predetermined amount, the strength will increase excessively and cause a decrease in toughness. Therefore, the W content with respect to the total mass of the weld metal is preferably 0.50 mass% or less, and more preferably 0.20 mass% or less.

[0079] <Remainder: Fe and inevitable impurities> In the weld metal according to the present embodiment, the remainder excluding the above components is Fe and inevitable impurities. Fe is the main component constituting the sheath of the flux-cored wire according to the present embodiment and remains in the weld metal. The Fe content with respect to the total mass of the weld metal is preferably, for example, 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. On the other hand, the Fe content with respect to the total mass of the weld metal is preferably 70% by mass or less, more preferably 68% by mass or less, and even more preferably 66% by mass or less. In addition, examples of the inevitable impurities include O, As, Sb, Sn, Bi, and S in addition to the above P and S. O in the weld metal is preferably less than 0.100% by mass with respect to the total mass of the weld metal. Further, the total amount of inevitable impurities excluding P, S, and O in the weld metal is preferably 0.10% by mass or less with respect to the total mass of the weld metal.

Examples

[0080] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, and it is possible to make modifications within the range that conforms to the gist of the present invention and implement them, and all of them are included in the technical scope of the present invention.

[0081] [Production of flux-cored wire] Using sheaths and fluxes with various compositions, flux-cored wires having the compositions shown in Tables 1 to 3 below were produced. The flux ratio was 18 to 26.5% by mass. In Table 3, "-" indicates that the corresponding component was not actively contained. In addition, in Table 1, formula (1): A1 indicates the value A1 calculated by formula (1), and formula (2): A2 indicates the value A2 calculated by formula (2). Formulas (1) and (2) are as follows.

[0082] A1 = [Nb] W + [V] W ···Formula (1) A2 = 1.31×(0.98×[Cr] W + [Mo] W + 0.7×[Nb] W ) - 1.1×([Ni] W + 35×[C] W + 20×[N] W + 0.25×[Cu] W ) ··· Equation (2) However, [Nb] W is the value representing the Nb content in the flux-containing wire in mass%, and [V] W is the value representing the V content in the flux-containing wire in mass%, and [Cr] W is the value representing the Cr content in the flux-containing wire in mass%, and [Mo] W is the value representing the Mo content in the flux-containing wire in mass%, and [Ni] W is the value representing the Ni content in the flux-containing wire in mass%, and [C] W is the value representing the C content in the flux-containing wire in mass%, and [N] W is the value representing the N content in the flux-containing wire in mass%, and [Cu] W is the value representing the Cu content in the flux-containing wire in mass%.

[0083] [Gas shielded arc welding] Two carbon steel plates with a thickness of 20 mm were prepared and processed so that the groove angle was 45°. After that, using the prepared flux-containing wire, 2 - 3 layers of buttering layers were formed on the surface of the groove part and the surface of the backing material, and the carbon steel plates were arranged to have a V-groove. Then, using each flux-containing wire, gas shielded arc welding was carried out on the groove. The welding conditions were using 100% CO2 shielding gas, 190 A - 28 V, and 6 layers and 12 passes in the downward position.

[0084] [Measurement of the composition of the weld metal] For the obtained weld metal, solid-state emission spectroscopic analysis was performed in accordance with JIS G 1253:2002 at the same position as the tensile test specimen sampling position described later to measure the composition of each weld metal. The contents of chemical components in the weld metal are shown in Tables 4 and 5. In Table 4, formula (3): A3 indicates the value A3 calculated by formula (3), and formula (4): A4 indicates the value A4 calculated by formula (4). Formulas (3) and (4) are as follows. The remainder of the weld metal is Fe and unavoidable impurities.

[0085] A3 = [Nb] M + [V] M ··· Formula (3) A4 = 1.18 × ([Cr] M + [Mo] M + 0.7 × [Nb] M ) - [Ni] M - 35 × [C] M - 20 × [N] M - 0.25 × [Cu] M ) ··· Formula (4) However, [Nb] M is the value representing the Nb content in the weld metal in mass%, [V] M is the value representing the V content in the weld metal in mass%, [Cr] M is the value representing the Cr content in the weld metal in mass%, [Mo] M is the value representing the Mo content in the weld metal in mass%, [Ni] M is the value representing the Ni content in the weld metal in mass%, [C] M is the value representing the C content in the weld metal in mass%, [N] M is the value representing the N content in the weld metal in mass%, [Cu] M is the value representing the Cu content in the weld metal in mass%.

[0086] [Mechanical Property Evaluation Test] (Charpy Impact Test) In accordance with JIS Z 2242:2023, standard V-notch test pieces were taken from the obtained weld metal, and Charpy impact tests were carried out. The test temperature for the Charpy impact test was -196 °C, and the Charpy impact value (vE-196 °C) and the lateral expansion amount LE (mm) were measured. Note that five test pieces for measuring the Charpy impact value and five test pieces for measuring the lateral expansion amount were taken from each weld metal respectively. For the Charpy impact value, the average value of the measured values was evaluated. Also, for the lateral expansion amount, the minimum value among the five test results was evaluated.

[0087] (Tensile test) In accordance with JIS Z 3111:2005, in the obtained weld metal, A0 test pieces were taken from the position where the center of the test piece was the weld center line, and tensile tests were carried out. The test temperature for the tensile test was room temperature (20 °C).

[0088] The Charpy impact value and lateral expansion amount obtained by the Charpy impact test, and the measurement results of the tensile strength are shown in Table 6 below. In each of the above evaluation tests, those with an average Charpy impact value of 35.0 (J / cm 2 ) or more, a lateral expansion amount of 0.53 mm or more, and a tensile strength of 498 MPa or more were considered qualified. Also, those that did not achieve the reference value in any item were considered unqualified. Also, those with an average Charpy impact value of 38.0 (J / cm 2 ) or more, a lateral expansion amount of 0.60 mm or more, and a tensile strength of 503 MPa or more were evaluated as more preferable.

[0089] [Table 1]

[0090] [Table 2]

[0091] [Table 3]

[0092]

Table 4

[0093]

Table 5

[0094]

Table 6

[0095] As shown in Tables 1 to 6, in Invention Examples No. 1 to 21, the content of specific components in the wire was appropriately controlled, and the values A1 and A2 calculated by formulas (1) and (2) were within the ranges defined in the present invention. Also, in the obtained weld metal, the content of each component and the values A3 and A4 calculated by formulas (3) and (4) were within the ranges defined in the present invention. Therefore, a weld metal with excellent mechanical properties, particularly with a transverse bulge amount equal to or greater than the desired value, was obtained. In Invention Example No. 20, since the values of A2 and A4 were lower compared to other invention examples, the tensile strength value was inferior to those of other invention examples. Also, in Invention Example No. 21, since the Cr and Ni contents were higher compared to other invention examples, the Charpy impact absorption value and the transverse bulge amount values were inferior to those of other invention examples.

[0096] On the other hand, for the wires of Comparative Examples No. 1 and 2, since the values of A2 and A4 exceeded the upper limits defined in the present invention, the Charpy impact values and the transverse bulge amounts were low. Also, for the wires of Comparative Examples No. 3 and 4, since the values of A2 and A4 were less than the lower limits defined in the present invention, the tensile strength decreased.

Claims

1. With respect to the total mass of the wire, Fe: 40% by mass or more and 70% by mass or less, C: 0.001% by mass or more and 0.030% by mass or less, Cr: 14.0% by mass or more and 28.0% by mass or less, Ni: 7.0% by mass or more and 20.0% by mass or less, Nb: 0.001% by mass or more and 0.15% by mass or less, and V: 0.005% by mass or more and 0.30% by mass or less, are contained, Mo: 4.0% by mass or less, Cu: 0.50% by mass or less, N: 0.020% by mass or less, and Value A1 calculated by the following formula (1): 0.02 or more and 0.30 or less, Value A2 calculated by the following formula (2): 10.0 or more and 12.3 or less, A flux-containing wire characterized by this. A1 = [Nb] Ｗ + [V] Ｗ ... Equation (1) A2 = 1.31×(0.98×[Cr] Ｗ + [Mo] Ｗ + 0.7×[Nb] Ｗ ) - 1.1×([Ni] Ｗ + 35×[C] Ｗ + 20×[N] Ｗ + 0.25×[Cu] Ｗ )... Equation (2) However, [Nb] Ｗ represents the value of the Nb content in the flux-containing wire expressed in mass%, and [V] Ｗ represents the value of the V content in the flux-containing wire expressed in mass%, and [Cr] Ｗ represents the value of the Cr content in the flux-containing wire expressed in mass%, and [Mo] Ｗ represents the value of the Mo content in the flux-containing wire expressed in mass%, and [Ni] Ｗ represents the value of the Ni content in the flux-containing wire expressed in mass%, and [C] Ｗ represents the value of the C content in the flux-containing wire expressed in mass%, and [N] Ｗ represents the value of the N content in the flux-containing wire expressed in mass%, and [Cu] Ｗ represents the value of the Cu content in the flux-containing wire expressed in mass%.

2. Furthermore, with respect to the total mass of the wire, Si: 0.10% by mass or more and 1.00% by mass or less, F: 0.10% by mass or more and 0.50% by mass or less, Mn: 0.1% by mass or more and 1.60% by mass or less, TiO ２ : 4.00% by mass or more and 10.00% by mass or less, ZrO of metallic Zr and Zr compounds ２ Conversion value: 0.50 mass% or more and 4.00 mass% or less MgO conversion value of metallic Mg and Mg compounds: 0.05% by mass or more and 1.00% by mass or less, Na: 0.01% by mass or more and 0.50% by mass or less, and K: 0.01% by mass or more and 0.50% by mass or less, are contained, P: 0.030% by mass or less, S: 0.030% by mass or less, Co: 0.300% by mass or less, W: 0.50% by mass or less, REM: 0.500% by mass or less, Ti: 1.0% by mass or less, Al: 0.3% by mass or less, Al ２ O ３ : 1.00 mass % or less, Li: 0.50% by mass or less, A flux-containing wire according to claim 1, characterized by this.

3. Said Ni: 10.0% by mass or more and 13.0% by mass or less, Said Cr: 16.5% by mass or more and 18.0% by mass or less, Said Mo: 1.7% by mass or more and 2.2% by mass or less, A flux-containing wire according to claim 1, characterized by this.

4. A welded joint characterized by being manufactured by welding using the flux-containing wire according to any one of claims 1 to 3 with a stainless steel plate as the base material.

5. With respect to the total mass of the weld metal, C: 0.001% by mass or more and 0.040% by mass or less, Cr: 14.0% by mass or more and 22.0% by mass or less, Ni: 7.0% by mass or more and 18.0% by mass or less, Mn: 0.3% by mass or more and 1.5% by mass or less, Nb: 0.001% by mass or more and 0.15% by mass or less, and V: 0.005% by mass or more and 0.30% by mass or less, are contained, Si: 1.0% by mass or less, Ti: 1.0% by mass or less, Mo: 4.0% by mass or less, Cu: 0.50% by mass or less, N: 0.020 mass% or less, the balance being Fe and inevitable impurities, and the value A3 calculated by the following formula (3): 0.02 or more and 0.30 or less, and the value A4 calculated by the following formula (4): 7.6 or more and 10.3 or less, a weld metal characterized by being such. A3 = [Nb] Ｍ + [V] Ｍ ··· Formula (3) A4 = 1.18×([Cr] Ｍ + [Mo] Ｍ + 0.7×[Nb] Ｍ ) - [Ni] Ｍ - 35×[C] Ｍ - 20×[N] Ｍ - 0.25×[Cu] Ｍ ・・・Equation (4) However, [Nb] Ｍ represents the value of the Nb content in the weld metal expressed in mass%, and [V] Ｍ represents the value of the V content in the weld metal expressed in mass%, and [Cr] Ｍ represents the value of the Cr content in the weld metal expressed in mass%, and [Mo] Ｍ represents the value of the Mo content in the weld metal expressed in mass%, and [Ni] Ｍ represents the value of the Ni content in the weld metal expressed in mass%, and [C] Ｍ represents the value of the C content in the weld metal expressed in mass%, and [N] Ｍ represents the value of the N content in the weld metal expressed in mass%, and [Cu] Ｍ represents the value of the Cu content in the weld metal expressed in mass%.

6. P: 0.030 mass% or less, S: 0.030 mass% or less, Co: 0.500 mass% or less, W: 0.50 mass% or less, the Ni: 12.0 mass% or more and 14.0 mass% or less, the Cr: 17.0 mass% or more and 19.0 mass% or less, the Mo: 1.7 mass% or more and 2.5 mass% or less, a weld metal according to claim 5, characterized by being such.

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