Flux-cored wire

Abstract

Provide a flux-cored wire for stainless steel welding with good welding operability. A flux-cored wire for arc welding in which a steel sheath is filled with a flux, which contains, based on the total mass of the wire: Cr: 16.0 to 22.0% by mass, Ni: 6.0 to 11.0% by mass, Mn: 0.7 to 2.6% by mass, Si: 0.1 to 1.1% by mass, Zr: 0.2 to 0.8% by mass, Fe: 45.0 to 65.0% by mass, TiO 2 : 5.0 to 9.0% by mass, SiO 2 : 0.1 to 2.0% by mass, and ZrO 2 : 0.5 to 3.0% by mass, with Bi limited to less than 0.0020% by mass (including 0% by mass), and the value of the parameter A represented by A = [Si] + 2×[Zr] satisfying 1.4 to 2.5.

Description

Technical Field

[0001] The present invention relates to flux-cored welding wire. Background Art

[0002] Conventionally, research has been conducted on a flux-cored wire for high-strength stainless steel welding that can achieve high-strength weld joint properties comparable to those of austenitic stainless steel SUS304, good bendability, high low-temperature toughness, and good welding workability.

[0003] For example, Patent Document 1 discloses a flux-cored wire for high-strength stainless steel welding, wherein the flux-cored wire for high-strength stainless steel welding is filled with flux inside an austenitic stainless steel outer sheath, and contains: Ni: 8.0-10.0%, Cr: 17.0-22.0%, Ti: 0.5-2.0%, Bi: 0.10% or less, fluoride: 0.05-0.70%, slag forming agent: 5-10% in total, and the balance is deoxidizer, Fe and inevitable impurities, and the oxygen content in the weld metal is 0.07-0.20% by mass due to the deoxidizer component. However, in the flux-cored wire disclosed in Patent Document 1, since Bi is added to the wire in an amount of 0.01-0.10%, the heat cracking resistance, corrosion resistance and low temperature toughness of the weld metal are poor.

[0004] As a flux-cored welding wire that does not contain Bi, for example, Patent Document 2 discloses a flux-cored welding wire for stainless steel welding, which contains: C: 0.005-0.10%, Si: 0.1-1.0%, Mn: 0.5-4.5%, Ni: 7-12%, Cr: 18-25%, Mo: 0.01-1.0%, Ti: 0.1-0.5%, N: 0.1-0.3%, Nb: 0.05% or less, and the flux contains: TiO 2 :4.5~7.5%、SiO 2 :0.2~1.8%、ZrO 2 :0.01~0.10%、Al 2 O 3 :0.01~0.2 0%、Na of Na compound 2 O conversion value and K of K compound 2 One or two kinds of O conversion values: 0.01 to 0.20%, F conversion values ​​of fluorine compounds: 0.1 to 1.0, and the balance is Fe and inevitable impurities.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2007-160314

[0008] Patent Document 2: Japanese Patent Laid-Open No. 2015-139807 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, the flux cored wire described in Patent Document 2 has insufficient welding workability such as slag detachability because it does not contain Bi. In particular, for welding construction of joints such as fixed pipes, improvement is pursued in terms of welding workability.

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide a flux cored wire for stainless steel welding having good welding workability.

[0012] Means for Solving the Problems

[0013] As a result of intensive studies on flux cored wires for stainless steel with restricted Bi content, the present inventors have found that good workability can be achieved by adding a specified metal component and controlling its content.

[0014] In other words, a flux cored wire according to one aspect of the present invention is a flux cored wire for arc welding in which a flux is filled in a steel sheath, and is characterized in that, based on the total mass of the wire, it contains:

[0015] Cr: 16.0 to 22.0% by mass, Ni: 6.0 to 11.0% by mass, Mn: 0.7 to 2.6% by mass, Si: 0.1 to 1.1% by mass, Zr: 0.2 to 0.8% by mass, Fe: 45.0 to 65.0% by mass, TiO 2 : 5.0 to 9.0% by mass, SiO 2 : 0.1 to 2.0% by mass, and ZrO 2 : 0.5 to 3.0% by mass, restricted Bi: less than 0.0020% by mass (including 0% by mass),

[0016] When the content of Si is [Si] and the content of Zr is [Zr] expressed in mass%, the value of the parameter A represented by A = [Si] + 2 × [Zr] satisfies 1.4 to 2.5.

[0017] The flux cored wire preferably has a flux ratio of 23 to 29% by mass.

[0018] The flux cored wire preferably contains, based on the total mass of the wire: the Si: 0.5 to 1.1% by mass, and the Zr: 0.3 to 0.7% by mass, and the value of the parameter A satisfies 1.4 to 2.3.

[0019] The flux cored wire preferably further contains an alkali metal compound and a metal fluoride. The alkali metal compound, Na of Na2 O conversion value and K of K 2 The total content of the O conversion value is 0.1 to 3.0% by mass based on the total mass of the welding wire, and the content of the metal fluoride in terms of the F conversion value is 0.01 to 0.50% by mass based on the total mass of the welding wire.

[0020] Advantages of the Invention

[0021] According to the present invention, it is possible to provide a flux cored wire for stainless steel welding having good welding workability. Detailed Embodiments

[0022] Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the embodiments described below, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[0023] [Flux Cored Wire]

[0024] The flux cored wire of the present embodiment is a flux cored wire for arc welding in which a welding flux is filled in a steel sheath, and satisfies the following composition.

[0025] Based on the total mass of the welding wire, it contains: Cr: 16.0 to 22.0% by mass, Ni: 6.0 to 11.0% by mass, Mn: 0.7 to 2.6% by mass, Si: 0.1 to 1.1% by mass, Zr: 0.2 to 0.8% by mass, Fe: 45.0 to 65.0% by mass, TiO 2 : 5.0 to 9.0% by mass, SiO 2 : 0.1 to 2.0% by mass, and ZrO 2 : 0.5 to 3.0% by mass, limiting Bi: less than 0.0020% by mass (including 0% by mass),

[0026] When the content of Si is [Si] and the content of Zr is [Zr] in terms of mass%, the value of the parameter A represented by A = [Si] + 2 × [Zr] satisfies 1.4 to 2.5.

[0027] In addition, the flux cored wire means a wire in which a welding flux is filled in a steel sheath. The flux cored wire can be any form such as a seamless type without a seam on the sheath or a seamed type with a seam on the sheath such as an overlapping cross-section. In addition, the flux cored wire may or may not be plated with Cu or the like on the surface of the wire (outside the sheath).

[0028] (Composition)

[0029] The content of each component of the flux cored wire according to the present embodiment will be described below. Each component for obtaining a welding metal having desired properties can be added either from the steel sheath or the flux. Therefore, in the following description, unless otherwise specified, the content of each component in the flux cored wire is defined as a value obtained by taking the total amount of components contained in the steel sheath and the flux as the total mass of the wire.

[0030] In addition, the components shown below are added to the steel sheath and the flux in various forms such as simple substances, compounds, and alloys. In the present embodiment, the form in which each component is added is not specified, and the source of the raw material is not limited.

[0031] <Cr: 16.0 to 22.0 mass%>

[0032] Cr, as a ferrite stabilizing element, has the effect of adjusting the balance between the ferrite phase and the austenite phase, and also has the effect of improving the pitting corrosion resistance of the welded part as a forming element of the passivation film. By having the content of Cr be 16.0 mass% or more, this effect can be sufficiently obtained. On the other hand, by having the content of Cr be 22.0 mass% or less, precipitation of the σ phase as an intermetallic compound can be suppressed and the low-temperature toughness of the welded part can be prevented from decreasing. Therefore, the content of Cr is limited to 16.0 to 22.0 mass%. The content of Cr is preferably 17.5 mass% or more, more preferably 18.5 mass% or more. In addition, the content of Cr is preferably 21.0 mass% or less, more preferably 20.0 mass% or less.

[0033] <Ni: 6.0 to 11.0 mass%>

[0034] Ni, as an austenite stabilizing element, has the effect of adjusting the balance between the ferrite phase and the austenite phase, and is an element effective for improving the low-temperature toughness of the welded part. By having the content of Ni be 6.0 mass% or more, this effect can be sufficiently obtained. On the other hand, by having the content of Ni be 11.0 mass% or less, excessive austenite phase in the welding metal can be suppressed and the strength of the welded part can be prevented from decreasing. Therefore, the content of Ni is limited to 6.0 to 11.0 mass%. The content of Ni is preferably 7.5 mass% or more, more preferably 8.0 mass% or more. In addition, the content of Ni is preferably 10.0 mass% or less, more preferably 9.0 mass% or less.

[0035] <Mn: 0.7 to 2.6 mass%>

[0036] Mn, as an austenite stabilizing element, has the effect of adjusting the balance of the ferrite phase / austenite phase, and acts as a deoxidizing element. This effect can be fully obtained by having a Mn content of 0.7% by mass or more. On the other hand, by having a Mn content of 2.6% by mass or less, it is possible to suppress the reduction in low-temperature toughness of the weld due to the formation of MnS. Therefore, the Mn content is limited to 0.7 to 2.6% by mass. The Mn content is preferably 1.0% by mass or more, more preferably 1.5% by mass or more. In addition, the Mn content is preferably 2.5% by mass or less.

[0037] <Si: 0.1 to 1.1 mass %>

[0038] Si, added by stainless steel outer skin, metallic silicon, iron silicon, iron silicon manganese, etc., has the effect of improving the weld bead shape and slag coating. By having an Si content of 0.1% by mass or more, the amount of slag formed by the deoxidation reaction during welding can be appropriate, and a good weld bead shape can be obtained. On the other hand, by having an Si content of 1.1% by mass or less, it is possible to prevent the slag coating from being excessive and deteriorating. Therefore, the Si content is limited to 0.1-1.1% by mass. The Si content is preferably 0.5% by mass or more, and more preferably 0.7% by mass or more. In addition, the Si content is preferably 1.0% by mass or less, and more preferably 0.9% by mass or less. In addition, the so-called Si means metallic Si, and its content means the total content of Si contained in the Si single substance and the alloy.

[0039] <Zr: 0.2 to 0.8 mass %>

[0040] Zr is added by the stainless steel outer skin, metal Zr, Fe-Zr-Si, etc. It is a strong deoxidizing element and has the effect of improving the toughness of the weld metal and improving the welding workability. In the flux-cored welding wire for stainless steel, when the Bi content is less than 0.0020 mass%, the corrosion resistance is good, but the welding workability such as slag stripping is insufficient. Therefore, in the flux-cored welding wire of the present embodiment, the welding workability such as slag stripping is improved by adding metal Zr. This effect can be fully obtained by the Zr content being 0.2 mass% or more. On the other hand, by the Zr content being 0.8 mass% or less, the toughness reduction caused by excessive strength accompanying the precipitation effect is suppressed, and good slag stripping can be obtained. Therefore, the Zr content is limited to 0.2-0.8 mass%. The Zr content is preferably 0.3 mass% or more, and more preferably 0.4 mass% or more. In addition, the Zr content is preferably 0.7 mass% or less, and more preferably 0.6 mass% or less. The term "Zr" means metal Zr, and the term "Zr content" means the total content of Zr contained in a single substance and an alloy.

[0041] <Bi: less than 0.0020 mass % (including 0 mass %)>

[0042] In the case of Bi, when the welded part is kept at a high temperature for a long time, Bi easily thickens at the austenite grain boundaries, deteriorating the crack resistance. In addition, when the Bi content is 0.0020% by mass or more, the corrosion resistance decreases. Therefore, the Bi content is limited to less than 0.0020% by mass. It is preferably as little as possible, preferably less than 0.0005% by mass, and may be 0% by mass (excluding).

[0043] <Parameter A = [Si] + 2×[Zr]: 1.4 to 2.5>

[0044] The inventors have found that by making the content of each component satisfy the above range, good low-temperature toughness and welding workability can be achieved. However, in order to achieve better low-temperature toughness and welding workability, in addition to the content of each component, the relationship between the contents of Si and Zr is also important. When the content of Si is [Si] and the content of Zr is [Zr], when the value of parameter A represented by A = [Si] + 2×[Zr] is 1.4 or more, these effects can be obtained sufficiently. In addition, by making the value of parameter A 2.5 or less, deterioration of low-temperature toughness and reduction of slag detachability due to excessive hardenability can be suppressed. Further, from the viewpoint of making the vertical welding bead flat, improving the slag detachability, and obtaining a good welding bead in the fixed tube welding construction, parameter A is preferably 1.5 or more, more preferably 1.7 or more, and further preferably 1.9 or more. In addition, the value of parameter A is preferably 2.3 or less, more preferably 2.1 or less.

[0045] <TiO 2 : 5.0 to 9.0% by mass>

[0046] TiO 2 is the main component of the slag former, has the effect of improving the coverage of the slag on the weld metal to make the bead shape good, and has the effect of accelerating the solidification of the slag and improving the welding workability during vertical and uphill welding. In addition, containing a specified amount of TiO 2 , has the effect of stabilizing the arc. By the content of TiO 2 being 5.0% by mass or more, these effects can be obtained sufficiently, and good welding workability can be obtained. On the other hand, by the content of TiO 2 being 9.0% by mass or less, hardening and reduction of detachability of the slag during welding are suppressed, and reduction of porosity defect resistance is suppressed. Therefore, the content of TiO 2 is limited to 5.0 to 9.0% by mass. The content of TiO 2 is preferably 6.0% by mass or more, more preferably 6.5% by mass or more. In addition, the content of TiO 2 is preferably 8.0% by mass or less, more preferably 7.5% by mass or less. Further, TiO 2means the TiO of the Ti compound 2 conversion value.

[0047] <SiO 2 : 0.1 to 2.0 mass% >

[0048] SiO 2 , has the effect of improving the coating of the slag on the welded metal to make the bead shape good, and has the effect of improving the bead fusion. By having the content of SiO 2 be 0.1 mass% or more, these effects can be fully obtained, and good welding workability can be obtained. On the other hand, by having the content of SiO 2 be 2.0 mass% or less, the hardening of the slag can be inhibited and the peelability is significantly reduced. Therefore, the content of SiO 2 is limited to 0.1 to 2.0 mass%. The content of SiO 2 is preferably 0.5 mass% or more, more preferably 0.8 mass% or more. In addition, the content of SiO 2 is preferably 1.5 mass% or less, more preferably 1.2 mass% or less. Also, SiO 2 means the SiO 2 conversion value of the Si compound, which is clearly distinguished from metallic Si.

[0049] <ZrO 2 : 0.5 to 3.0 mass% >

[0050] ZrO 2 , has the effect of accelerating the solidification of the slag and improving the welding workability during vertical up welding. By having the content of ZrO 2 be 0.5 mass% or more, this effect can be fully obtained, and good welding workability can be obtained. On the other hand, by having the content of ZrO 2 be 3.0 mass% or less, the reduction of the slag peelability can be inhibited. Therefore, the content of ZrO 2 is limited to 0.5 to 3.0 mass%. The content of ZrO 2 is preferably 1.0 mass% or more, more preferably 1.5 mass% or more. In addition, the content of ZrO 2 is preferably 2.6 mass% or less, more preferably 2.1 mass% or less. Also, ZrO 2 means the ZrO 2 conversion value of the Zr compound, which is clearly distinguished from metallic Zr.

[0051] <Total of the Na 2 O conversion value of the alkali metal compound Na and the K 2 O conversion value of K: 0.1 to 3.0 mass% >

[0052] As Na compounds and K compounds which are alkali metal compounds, they have the effect of stabilizing the arc and reducing the amount of spatter generated. The alkali metal compounds may not be contained, but when contained, through the Na 2 O conversion value of Na and the K 2 O conversion value of K, the total is 0.1% by mass or more, and this effect can be sufficiently obtained. On the other hand, through the Na 2 O conversion value of Na and the K 2 O conversion value of K, the total is 3.0% by mass or less, and the bead shape defect accompanied by the rapid solidification of the slag can be suppressed. Therefore, the total of the Na 2 O conversion value of Na and the K 2 O conversion value of K is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and still more preferably 1.0% by mass or more. In addition, the total of the Na 2 O conversion value of Na and the K 2 O conversion value of K is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and still more preferably 2.0% by mass or less.

[0053] The content of the Na 2 O conversion value of Na is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass or more. In addition, the content of the Na 2 O conversion value of Na is preferably 3.0% by mass or less, more preferably 1.5% by mass or less, and still more preferably 1.0% by mass or less.

[0054] The content of the K 2 O conversion value of K is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass or more. In addition, the content of the K 2 O conversion value of K is preferably 3.0% by mass or less, more preferably 1.5% by mass or less, and still more preferably 1.0% by mass or less.

[0055] <Metal fluoride fluorine conversion value: 0.01 - 0.50% by mass>

[0056] Metal fluorides play a role in adjusting the fluidity of the slag and improving the slag stripping property. In addition, they have the effect of suppressing porosity defects such as pits and pores. Metal fluorides may not be contained, but when contained, by having a fluorine conversion value content of 0.01% by mass or more of the metal fluoride, these effects can be fully obtained, and good welding workability can be achieved. On the other hand, even if the content of the fluorine conversion value is greater than 0.50% by mass, no further improvement in slag stripping property and improvement effect of porosity resistance can be obtained. In addition, by having a fluorine conversion value content of 0.50% by mass or less, excessive fluidity of the slag is suppressed, vertical and upward welding is facilitated, and excessive generation of fumes is prevented, and good arc stability is obtained. Therefore, the content of the fluorine conversion value of the metal fluoride is preferably 0.01% by mass or more, more preferably 0.10% by mass or more, and further preferably 0.15% by mass or more. In addition, the content of the fluorine conversion value of the metal fluoride is preferably 0.50% by mass or less, more preferably 0.35% by mass or less, and further preferably 0.25% by mass or less.

[0057] Furthermore, as components that can be included as metal fluorides, CaF 2 , BaF 2 , MgF 2 , LiF, NaF, KF, etc. can be cited. Among them, from the aspect of improving the upward arc stability, it is preferable to contain NaF and KF.

[0058] <Fe: 45.0 - 65.0% by mass>

[0059] Fe is the main component of the flux-cored wire. From the relationship between the deposition amount and the composition of other components, the content of Fe is 45.0% by mass or more, preferably 50.0% by mass or more, and more preferably 55.0% by mass or more. In addition, the content of Fe is 65.0% by mass or less, preferably 62.0% by mass or less, and more preferably 60.0% by mass or less.

[0060] The flux-cored wire of the present embodiment can preferably contain the above-mentioned Cr, Ni, Mn, Si, Zr, Fe, TiO 2 , SiO 2 , ZrO 2 and Bi in total of 85% by mass or more, more preferably 88% by mass or more, further preferably 92% by mass or more, and particularly preferably 95% by mass or more.

[0061] <Other components>

[0062] The flux-cored wire of the present embodiment contains inevitable impurities. As other components, if necessary, it may contain: Al ≤ 0.010% by mass, Ta ≤ 0.010% by mass, W ≤ 0.010% by mass, Sn ≤ 0.010% by mass, Mg ≤ 0.010% by mass, rare earth elements (REM) ≤ 0.010% by mass, etc. In addition, these components can be actively added within the range that does not impair the effects of the present invention.

[0063] (Flux ratio: 23 - 29% by mass)

[0064] The flux ratio of the flux-cored wire refers to the value expressed by (flux mass / total wire mass) × 100 (%).

[0065] The flux ratio is not particularly limited, but when the flux-cored wire of the present embodiment is used for SUS304 stainless steel, from the aspect of ensuring the mechanical properties in the weld metal, it is preferably 23% by mass or more, more preferably 24% by mass or more, and further preferably 25% by mass or more. In addition, from the aspect of ensuring welding operability, the flux ratio is preferably 29% by mass or less, more preferably 28% by mass or less, and further preferably 27% by mass or less.

[0066] [Manufacturing method of flux-cored wire]

[0067] The manufacturing method of the flux-cored wire of the present embodiment is not particularly limited, but for example, it can be manufactured by the method shown below.

[0068] First, prepare a steel strip that constitutes the steel outer skin. While transporting the steel strip in the length direction, it is formed by a forming roller into a U-shaped open tube. Then, the flux mixed with various raw materials is filled into the steel outer skin so as to have a specified composition, and then it is processed so that the cross-section becomes circular. Then, it is drawn by cold working to become a flux-cored wire with a desired wire diameter.

[0069] The wire diameter is not particularly limited, but for example, it is 1.2 mm to 1.6 mm.

[0070] In addition, annealing can be performed during the cold working. Moreover, any of the structures of a seamless wire that welds the seam of the formed steel outer skin during manufacturing and a wire that leaves a gap state without welding the seam can be adopted.

[0071] Examples

[0072] Hereinafter, examples and comparative examples will be described in detail regarding the present invention, but the present invention is not limited to these.

[0073] The flux with appropriately combined raw materials is filled into the steel outer skin to produce a flux-cored wire with a wire diameter of 1.2 mm such that the proportion of the flux is 26% by mass relative to the total mass of the welding wire.

[0074] In Table 1 below, the contents (mass %) of the chemical components in the flux-cored wires of the examples and comparative examples are shown. In Table 1, the so-called metal fluoride means the content of the fluorine conversion value of the metal fluoride, and the so-called alkali metal compound means the total content of the Na 2 O conversion value of Na and the K 2 O conversion value of K.

[0075] Table 1

[0076]

[0077] Using the obtained flux-cored wire, a steel plate with the composition shown in Table 2 is used as the base material, and horizontal fillet welding and vertical-up fillet welding are carried out under the test conditions shown in Table 3 to evaluate the welding operability at that time. Also, the composition of Table 2 shows the main chemical components other than Fe.

[0078] The evaluation method of the welding operability is as described below, and the evaluation results are shown in Table 4.

[0079] The evaluation criteria for arc stability are as described below, and ○ and △ are qualified.

[0080] ○: The arc is very stable.

[0081] △: The arc is slightly stable.

[0082] ×: The arc is unstable.

[0083] The evaluation criteria for the amount of spatter are as described below, and ○ and △ are qualified.

[0084] ○: The amount of spatter is very small.

[0085] △: The amount of spatter is slightly small.

[0086] ×: The amount of spatter is large.

[0087] The evaluation criteria for the amount of fume are as described below, and ○ and △ are qualified.

[0088] ○: The amount of fume is very small.

[0089] △: The amount of fume is slightly small.

[0090] ×: The amount of fume is large.

[0091] The appearance of the weld bead is evaluated by visually inspecting the weld metal. The evaluation criteria are as described below, and ○ and △ are qualified.

[0092] ○: The appearance of the weld bead is good.

[0093] △: The appearance of the weld bead is slightly good.

[0094] ×: The appearance of the weld bead is poor.

[0095] The shape of the weld bead is evaluated by visually inspecting the welded metal. The evaluation criteria are as follows. ○ and △ are qualified.

[0096] ○: The shape of the weld bead is good.

[0097] △: The shape of the weld bead is slightly good.

[0098] ×: The shape of the weld bead is poor.

[0099] The evaluation criteria for slag peeling are as follows. ○ and △ are qualified.

[0100] ○: The slag peeling is good.

[0101] △: The slag peeling is slightly good.

[0102] ×: The slag peeling is poor.

[0103] Fusion and alignment are evaluated by visually inspecting the welded metal. The evaluation criteria are as follows. ○ and △ are qualified.

[0104] ○: The fusion and alignment are good.

[0105] △: The fusion and alignment are slightly good.

[0106] ×: The fusion and alignment are poor

[0107] Table 2

[0108] Table 2

[0109]

[0110] Table 3

[0111] Table 3

[0112]

[0113] Table 4

[0114] Table 4

[0115]

[0116] From the above results, in either horizontal fillet welding or vertical-up fillet welding, compared with Comparative Examples 1 and 2 that do not contain Zr, any of Examples 1 to 4 obtained good results in slag peeling. In vertical-up fillet welding, there were also excellent results in the appearance and shape of the weld bead.

[0117] In addition, in Comparative Example 3, which contains a specified amount of Zr and Si and has a value of parameter A represented by [Si] + 2×[Zr] less than 1.4, the bead shape is poor in vertical up fillet welding, but the bead shape is good in any of Examples 1 to 4.

[0118] Using the obtained flux-cored wire, downward welding was carried out under the test conditions shown in Table 5. For the obtained weld metal, as an evaluation of mechanical properties, tests were conducted on the 0.2% proof stress, tensile strength, and thermal stress.

[0119] The evaluation method of the mechanical properties is as described below, and the evaluation results are shown in Table 6.

[0120] For the 0.2% proof stress and tensile strength, tensile test pieces were fabricated by welding the total cladded metal under the conditions shown in Table 5, and the tests were carried out in accordance with AWA5.22:2012. For the 0.2% proof stress, it is evaluated as good when it is 350 MPa or more and less than 400 MPa, and as particularly good when it is 400 MPa or more. For the tensile test, it is evaluated as good when it is 550 MPa or more and less than 600 MPa, and as particularly good when it is 600 MPa or more.

[0121] The Charpy impact value was measured by fabricating a V-notch test piece by welding the total cladded metal under the conditions shown in Table 5 and conducting the test at 0°C. When the νE value at 0°C is 47 J or more, it is good.

[0122] Table 5

[0123] Table 5

[0124]

[0125] Table 6

[0126] Table 6

[0127]

[0128] From the above results, it can be seen that the flux-cored wires of Examples 1 to 4 satisfy the mechanical properties required for the obtained weld metal, and the welding operability is also very good.

[0129] As described above, various embodiments have been described with reference to the drawings. Of course, the present invention is not limited to this example. It is clear that those skilled in the art can conceive of various variations or modifications within the scope described in the claims, and these are of course also understood to belong to the technical scope of the present invention. In addition, within the scope not departing from the gist of the invention, the constituent elements of the above embodiments can be arbitrarily combined.

[0130] Furthermore, this application is based on a Japanese patent application (Japanese Patent Application No. 2020-150048) filed on September 7, 2020, the content of which is incorporated herein by reference.

Claims

1. A flux-cored wire is a flux-cored wire for arc welding in which a flux is filled in a steel outer sheath, and contains, based on the total mass of the wire: Cr: 16.0 to 22.0 mass%, Ni: 6.0 to 11.0 mass%, Mn: 1.5 to 2.6 mass%, Si: 0.1 to 1.1 mass%, Zr: 0.2 to 0.8 mass%, Fe: 45.0 to 65.0 mass%, TiO 2 : 5.0 to 9.0 mass%, SiO 2 : 0.1 to 2.0 mass%, and ZrO 2 : 0.5 to 3.0 mass%, Specified Bi: less than 0.0020% by mass and including 0% by mass, When the content of the Si is expressed as [Si] and the content of the Zr is expressed as [Zr] in % by mass, the value of the parameter A represented by A = [Si] + 2 × [Zr] satisfies 1.4 to 2.

5.

2. The flux-cored wire according to claim 1, wherein, The flux ratio is 23 to 29% by mass.

3. The flux-cored wire according to claim 1 or 2, wherein, Contains, based on the total mass of the wire: the Si: 0.5 to 1.1% by mass, and the Zr: 0.3 to 0.7% by mass, The value of the parameter A satisfies 1.4 to 2.

3.

4. The flux-cored wire according to claim 1 or 2, wherein, Also contains an alkali metal compound and a metal fluoride, Among the alkali metal compounds, the content of the Na 2 conversion value of Na and the K 2 conversion value of K in total is 0.1 to 3.0% by mass based on the total mass of the welding wire. In the metal fluoride, the content of the fluorine conversion value is 0.01 to 0.50% by mass based on the total mass of the wire.

5. The flux-cored wire according to claim 3, wherein, Also contains an alkali metal compound and a metal fluoride, Among the alkali metal compounds, the content of the total of the Na 2 O conversion value of Na and the K 2 O conversion value of K is 0.1 to 3.0% by mass based on the total mass of the welding wire. 2 O conversion value of Na and the K 2 O conversion value of K is 0.1 to 3.0% by mass based on the total mass of the welding wire. In the metal fluoride, the content of the fluorine conversion value is 0.01 to 0.50% by mass based on the total mass of the wire.

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