CN116252066A - Alkaline flux-cored wire, deposited metal obtained using alkaline flux-cored wire, welding method, and method for manufacturing welded joint - Google Patents

Abstract

An alkaline flux-cored wire, a deposited metal obtained by using the alkaline flux-cored wire, a welding method, and a method for producing a welded joint, which can perform full-position welding and can obtain a deposited metal and a welded metal excellent in balance between strength and toughness. In the alkaline flux-cored wire containing the strong deoxidizing element, the total amount of the strong deoxidizing element is 1.50 to 4.0 mass percent, REM:0.03 to 0.12 mass percent, B:0.02 mass% or less, and values calculated from 32.1 x [ Si ] -40.6 x [ Mn ] -20.1 x [ Ni ] -19.7 x [ Mo ] -172.6 x [ C ] -408.2 x [ REM ] -5824.4 x [ B ] -38.4 x [ Cr ] -9960 x [ P ] +43793 x [ S ] for each content of REM, fe, C, si, mn, P, S, cr, mo, al, zr, ni and B satisfy 48.0 or less.

Description

Alkaline flux-cored wire, deposited metal obtained using alkaline flux-cored wire, welding method, and method for manufacturing welded joint

Technical Field

The present invention relates to an alkaline flux-cored wire which can be welded in a full posture and has an excellent balance between strength and toughness, a deposited metal obtained by using the alkaline flux-cored wire, and a welding method and a welded joint using the alkaline flux-cored wire.

Background

Flux-cored wires can be classified into rutile type, alkaline type, and metal type according to the kind of flux to be filled. These are used in a variety of applications, but among them, the alkaline flux-cored wire has a merit that excellent toughness can be obtained because the oxygen content of the weld metal can be suppressed to be low. However, the alkaline flux-cored wire is also poor in welding operability, and is particularly difficult to apply to such a short point as vertical welding, horizontal welding, and overhead welding, which are difficult to weld in a posture.

Patent document 1 discloses a technique for overcoming the above-mentioned drawbacks in an alkaline flux-cored wire. Specifically, patent document 1 describes that the flux includes a strongly deoxidized metal element containing Mg and Al and a fluorine compound powder, the strongly deoxidized metal element and the fluorine compound powder have a specific particle size, the flux ratio is 10 to 30 mass%, and the flux satisfies Al:1.0 to 3.5 mass% of Mg ₍ wire): 0.3 to 0.9 mass% and a fluorine conversion value F of the fluorine compound: 0.30 to 1.20 mass% of a total of strongly deoxidized metal elements: 2.2 mass% or more of a strongly deoxidized metal element: 15 to 35 mass percent of fluorine compound powder: 10 to 45 mass% or the like, thereby enabling full-position welding.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2021-000646

Disclosure of Invention

Problems to be solved by the invention

However, the flux-cored wire described in patent document 1 is added with a strong deoxidizing element so that the flux-cored wire can be welded in a full posture. As such a strong deoxidizing element, there are cases where it plays an excellent deoxidizing role in welding, and it is discharged with slag and remains as inclusions in the weld metal.

However, inclusions remaining in the weld metal adversely affect mechanical properties, particularly toughness. In other words, patent document 1, while overcoming the shortages of an alkaline flux-cored wire that can be welded in a full posture, on the other hand, fails to make the most of the advantages of an alkaline flux-cored wire having excellent toughness.

Further, there is a problem that the toughness depends on the strength value, and the balance between the strength and the toughness varies depending on the target strength. For example, when the strength is designed to be high, the toughness may be extremely deteriorated when the target strength is adjusted down and the design is repeated, although the toughness is good. This is because the added element changes according to the target strength, and affects the deposited metal structure or the welded metal structure.

The present invention has been made in view of the above-described problems, and an object thereof is to provide an alkaline flux-cored wire and a welding method which can perform all-position welding and can obtain a deposited metal and a welded metal (hereinafter, also referred to as a "welded joint") excellent in balance between strength and toughness, and a deposited metal and a welded joint excellent in balance between strength and toughness.

Means for solving the problems

The above object of the present invention can be achieved by the following constitution of [1] of an alkaline flux-cored wire.

[1] An alkaline flux-cored wire is characterized by comprising an alkaline flux-cored wire containing a strong deoxidizing element, wherein,

the total amount of the strong deoxidizing elements is 1.50 mass% or more and 4.00 mass% or less relative to the total mass of the welding wire, and contains REM:0.030 mass% or more and 0.120 mass% or less, fe:85.0 mass% or more and satisfies

C: 0.050% by mass or less,

Si:0.60 mass% or less,

Mn:2.00 mass% or less,

P:0.0150 mass% or less,

S:0.0150 mass% or less,

Cr:1.00 mass% or less,

Mo:1.00 mass% or less,

Al:3.00 mass% or less,

Mg:3.00 mass% or less,

Zr:3.000 mass% or less,

Ti:3.000 mass% or less,

Ca:3.00 mass% or less,

Ni:5.00 mass% or less,

B:0.0200 mass% or less,

Ba:4.00 mass% or less,

F: at most 2.00 mass% of the total mass,

a value calculated by the following formula (1): the temperature of the mixture is less than or equal to 48.0,

a value calculated by the following formula (2): the temperature of the mixture is less than or equal to 48.0,

a value calculated by the following formula (3): the number of the components is more than 0.09,

a value calculated by the following formula (4): 0.14 or more.

Formula (1): 32.1 xSi-40.6 xMn-20.1 xNi-19.7 xMo-172.6 xC-408.2 xREM-5824.4 xB-38.4 xCr-9960 xP+ 43793 xS

Formula (2): 33.9 xSi-47.0 xMn-22.2 xNi-11.9 xMo-203.9 xC-443.5 xREM-4482.2 xB-36.1 xCr-15281 xP+ 47868 xS

Formula (3): 0.001 XFe-0.71 XSi+0.08 XMn-0.08 XAl+0.69 XZr+0.03 XNi+0.01 XMo+0.32 XC+2.27 XREM+9.57 XB+0.11 XCr

Formula (4): 0.003 XFe-0.35 XSi +0.09 XMn-0.13 XAl +0.22 XZr +0.02 XNi-0.02 XMo-0.11 XC +1.17 XREM +4.30 XB +0.09 XCr

Wherein in the formulas (1) to (4), the contents of [ REM ], [ Fe ], [ C ], [ Si ], [ Mn ], [ P ], [ S ], [ Cr ], [ Mo ], [ Al ], [ Zr ], [ Ni ] and [ B ] are respectively represented by mass% relative to the total mass of the welding wire.

Further, preferred embodiments of the present invention of the alkaline flux-cored wire relate to the following [2] to [11].

[2] The alkaline flux-cored wire of [1], wherein at least one selected from the group consisting of,

nb:0.50 mass% or less,

Cu:2.00 mass% or less,

W:1.00 mass% or less,

Ta:1.00 mass% or less,

V:1.00 mass% or less,

Sr:4.00 mass% or less, and

total of alkali metal elements: 3.00 mass% or less of the total mass of the composition,

the balance being O, N and impurities.

[3] The alkaline flux-cored wire of [1] or [2], wherein the content of B is 0.0020 mass% or more and 0.0150 mass% or less with respect to the total mass of the wire.

[4] The alkaline flux-cored wire of any one of [1] to [3], wherein the content of B comprises a B conversion value of B oxide,

when the B conversion value of the B oxide with respect to the total mass of the wire is expressed as [ B oxide ], in mass%, the formula (5) is as follows: the value calculated by [ B oxide ]/[ B ] is 0.5 or more.

[5] The alkaline flux-cored wire of any one of [1] to [4], characterized in that,

contains a metal selected from the group consisting of Ba:4.00 mass% or less, ca:3.00 mass% or less and Sr: at least one selected from 4.00 mass% or less,

The flux contains BaF as a fluoride of Ba, ca and Sr ₂ 、CaF ₂ And SrF ₂ At least one of the group consisting of,

the Ba content includes the BaF ₂ The Ca content includes the CaF ₂ The content of Sr including the Ca-converted value of SrF ₂ Is a value of (1) in terms of Sr,

the content of F comprises the BaF ₂ The CaF is ₂ And the SrF ₂ F converted value of (c).

[6] The alkaline flux-cored wire of [5], wherein the F content is equal to the F conversion value of the total fluoride contained in the flux.

[7] The alkaline flux-cored wire of any one of [1] to [6], wherein the content of oxides in the flux is 0.005 mass% or more and 0.100 mass% or less relative to the total mass of the wire.

[8] The alkaline flux-cored wire of any one of [1] to [7], characterized in that,

the Cr content is 0.20 mass% or more and 0.90 mass% or less relative to the total mass of the welding wire, and,

the Mo content is 0.50 mass% or less relative to the total mass of the welding wire,

represented by formula (6): the calculated value of [ Cr ]/([ Cr ] + [ Mo ]) is more than 0.20.

[9] The alkaline flux-cored wire of any one of [1] to [7], characterized in that,

The Cr content is 0.90 mass% or less relative to the total mass of the welding wire, and,

the content of Mo is 0.10 to 0.80 mass% relative to the total mass of the welding wire,

represented by formula (7): the calculated value of [ Mo ]/([ Cr ] + [ Mo ]) is more than 0.10.

[10] The alkaline flux-cored wire of any one of [1] to [9], characterized in that,

the strong deoxidizing element contains 1.00 mass% or more and 2.50 mass% or less of Al with respect to the total mass of the wire,

the Mg content is 1.00 mass% or less,

when the content of Mg in the wire is expressed as Mg in mass% with respect to the total mass of the wire,

represented by formula (8): the calculated value of [ Al ]/([ Al ] + [ Mg ]) is 0.5 to 1.0.

[11] The alkaline flux-cored wire of any one of [1] to [10], wherein the REM comprises La and Ce.

The above object of the present invention relates to the following [12] regarding the deposited metal.

[12] A deposited metal, characterized by comprising, relative to the total mass of the deposited metal

C:0.020 to 0.100 mass%,

Si:0.05 to 0.50 mass%,

Mn:0.20 to 1.80 mass%,

Al:0.30 to 1.50 mass% inclusive,

Ce:0.002 to 0.010 mass%,

Fe:85.0 mass% or more,

and meet the following requirements

La:0.008 mass% or less,

P:0.0200 mass% or less,

S:0.0200 mass% or less,

Cr:1.00 mass% or less,

Mo:1.00 mass% or less,

Mg:0.50 mass% or less,

Zr:0.50 mass% or less,

Ti:0.05 mass% or less,

Ca:0.50 mass% or less,

Ni:3.00 mass% or less,

B:0.0090 mass% or less,

Ba:1.00 mass% or less,

Nb:0.001 mass% or less,

Cu:0.1 mass% or less,

V:0.001 mass% or less,

W:0.1 mass% or less,

Ta:0.1 mass% or less,

Sr:1.00 mass% or less,

Total of alkali metal elements: 0.05 mass% or less,

O:0.0250 mass% or less,

N:0.0100 mass% or less of the resin composition,

the balance being impurities.

The above object of the present invention relates to the following [13] of an alkaline flux-cored wire.

[13] An alkaline flux-cored wire characterized by obtaining the deposited metal of [12 ].

The above object of the present invention relates to the following [14] regarding the welding method.

[14] A welding method, wherein gas shielded arc welding is performed using the alkaline flux-cored wire of any one of [1] to [11] and [13].

The above object of the present invention relates to the following [15] regarding a welded joint.

[15] A welded joint characterized by being produced by the welding method according to [14 ].

Effects of the invention

According to the present invention, it is possible to provide an alkaline flux-cored wire and a welding method that can perform all-position welding and can obtain a deposited metal and a welded metal that are excellent in balance between strength and toughness, and a deposited metal and a welded joint that are excellent in balance between strength and toughness.

Detailed Description

In the present embodiment, by containing the strong deoxidizing element in an appropriate amount in the alkaline flux-cored wire, the welding operability can be improved and welding in a difficult posture can be performed. However, according to the element used for strength adjustment, there is a possibility that the strength and toughness of the deposited metal or the weld metal are out of balance.

Accordingly, the present inventors further derived a parameter formula from the relationship between the composition and the mechanical properties designed in the strength range used in industry. Specifically, as the composition and mechanical properties of the present embodiment, the relationship between strength, toughness, and brittleness ratio is summarized by a multiple regression equation, and a welding wire composition having an excellent balance between strength and toughness can be derived by satisfying the following 4 equations.

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the embodiments described below, and may be modified and implemented arbitrarily within a scope not departing from the gist of the present invention.

[1. Alkaline flux-cored wire ]

The alkaline flux-cored wire of the present embodiment (hereinafter, sometimes simply referred to as "wire") includes flux as a core and a strip steel as a sheath. Hereinafter, preferred ranges and reasons for limiting the components and the contents thereof contained in the alkaline flux-cored wire of the present embodiment will be specifically described.

In the specification, the term "to" is used in the sense that the numerical values before and after the term "to" are included as a lower limit value and an upper limit value. In this specification, the element is followed by "(Wire)" to indicate that the element is contained in the Wire.

Similarly, the element is followed by "(Metal)" to indicate that the element is contained in the deposited Metal.

Here, as the element, an example of Mn is assumed. If the metal Mn is the whole welding wire _(Wire) Examples of the Mn-converted value of the Mn compound in the whole welding wire include Mn contained in the strip steel and Mn metal powder contained in the flux ₍ Wire), an Mn equivalent value of an oxide of Mn or the like can be cited. In addition, so-called Mn _(Wire) The content of (C) is metal Mn of the whole welding wire _(Wire) Mn equivalent value of Mn-related compound _(Wire) Mn content of the whole welding wire is expressed as mass% relative to the total mass of the welding wire. In the total amount, the metal Mn of the whole welding wire _(Wire) Mn conversion value of Mn compound integrated with wire _(Wire) Either of them may be 0.

Total amount of strong deoxidizing elements: 1.50 mass% or more and 4.00 mass% or less

The alkaline flux-cored wire (hereinafter, sometimes simply referred to as "wire") of the present embodiment includes a flux as a core and a strip steel as a sheath. In the present embodiment, by adding a proper amount of the strong deoxidizing element, improvement of welding operability and application of difficult posture can be achieved. Examples of the strong deoxidizing element include Al, mg, ti, ca, zr, etc., and the total amount thereof is defined. The total amount is a total amount of these elements in terms of mass of the total mass of the welding wire, for example, when Al, mg, ti, ca, zr is contained in the welding wire. If the total amount of the strong deoxidizing elements is less than 1.50 mass%, it is difficult to apply the composition to difficult postures. Therefore, the total amount of the strong deoxidizing elements is 1.50 mass% or more, preferably 2.00 mass% or more.

On the other hand, if the total amount of the strong deoxidizing elements is more than 4.00 mass%, the number of inclusions in the weld metal excessively increases, and the toughness decreases. Accordingly, the total amount of the strong deoxidizing elements in the alkaline flux-cored wire of the present embodiment is 4.00 mass% or less, preferably 3.20 mass% or less, in the composition range satisfying the following formulas (1) to (4). As described later, al and Mg are preferably contained as strong deoxidizing elements.

＜REM _(Wire) :0.030 mass% or more and 0.120 mass% or less >, respectively

REM _{(Rare Earth Metals)} The rare earth element includes Ce, la, and the like. As described above, the welding in a difficult posture can be achieved by containing the strong deoxidizing element in the welding wire, but if the content of the strong deoxidizing element in the welding wire is excessive, inclusions remain in the weld metal, and toughness is deteriorated. The inventors of the present invention found from the relationship between the number density of inclusions in a weld metal and toughness that the toughness can be improved by reducing the number density. Furthermore, the inventors have found that REM is contained in a predetermined content range in a welding wire _(Wire) The number density can be reduced.

Specifically, by making REM _(Wire) When the content is 0.030 or more, REM functions as a binder for agglomerating the oxide of the added strongly deoxidizing element. For example, when the deposited metal is formed using the welding wire to which Al, mg, REM is added, the composite oxide REM, al, mg is formed when the structure in the deposited metal is observed, and it is confirmed that the number density of inclusions in the deposited metal is reduced.

If REM _(Wire) If the content of (2) is less than 0.030 mass%, the above-mentioned oxide cannot be coagulated. Thus, REM _(Wire) The content of (2) is 0.030 mass% or more, preferably 0.040 mass% or more, based on the total mass of the wire.

On the other hand, if REM _(Wire) If the content of (2) is more than 0.120 mass%, the inclusion coarsens due to the agglomeration, which may adversely affect the mechanical properties or cause unacceptable weld defects. Thus, REM _(Wire) The content of (2) is 0.120 mass% or less, preferably 0.110 mass% or less, based on the total mass of the wire.

In addition, REM is preferably contained in the flux. The added form is irrelevant, the form of the metal REM and the REM-containing alloyAny form such as gold form or REM compound form may be used. When the REM is contained in the flux in the form of a compound _(Wire) Comprises the REM converted value of REM compound. The REM is preferably contained in the flux as a REM-containing alloy, and more preferably, the REM is added to the welding wire in the flux as a REM-containing alloy. The REM contained in the basic cored wire of the present embodiment is preferably La or Ce.

In the present embodiment, in order to achieve the object of the present invention, a plurality of parameters using the content of a specific element are generated, and the values of these parameters are specified. In the present specification, the content of a certain component relative to the total mass of the welding wire is expressed as [ (component name) ]. Specifically, [ REM ]]、[Fe]、[C]、[Si]、[Mn]、[P]、[S]、[Cr]、[Mo]、[Al]、[Zr]、[Ni]、[B]And [ Mg ]]REM in the wire is expressed in mass% relative to the total mass of the wire _(Wire) 、Fe _(Wire) 、C _(Wire) ，Si _(Wire) 、Mn _(Wire) 、P _(Wire) 、S _(Wire) 、Cr _(Wire) 、Mo _(Wire) 、Al _(Wire) 、Zr _(Wire) 、Ni _(Wire) 、B _(Wire) And Mg (magnesium) _(Wire) Is a value of the content of (2).

< value calculated by the following formula (1): 48.0 or less >, of

The formula (1) is used for adjusting mechanical properties such as strength and toughness, and is a formula parameterized by a relationship between elements related to carbon equivalent and cold crack sensitivity and brittle fracture rate at-46 ℃ in multiple regression analysis. When the value calculated from the following formula (1) is 48.0 or less based on the content of each element, the composition of the welding wire is a combination of elements having a low brittle fracture surface rate at an extremely low temperature, and it is possible to say that the toughness at an extremely low temperature is excellent. On the other hand, if the value calculated by the following formula (1) is higher than 48.0, the brittle fracture surface ratio is high, and sufficient toughness cannot be ensured, and the welding wire composition is formed by combining elements that may deviate in toughness depending on the welding portion. Therefore, the value calculated by the following formula (1) is preferably 48.0 or less, more preferably 47.0 or less.

Formula (1):

32.1×[Si]－40.6×[Mn]－20.1×[Ni]－19.7×[Mo]－172.6×[C]－408.2×[REM]－5824.4×[B]－38.4×[Cr]－9960×[P]+43793×[S]

< value calculated by the following formula (2): 48.0 or less >, of

The formula (2) is used for adjusting mechanical properties such as strength and toughness, and is a formula parameterized by a relationship between elements related to carbon equivalent and cold crack sensitivity and brittle fracture rate at-20 ℃ in multiple regression analysis. When the value calculated from the following formula (2) is 48.0 or less based on the content of each element, the composition of the welding wire is a combination of elements having a high brittle fracture surface rate at low temperature, and therefore, it can be said that the toughness at low temperature is excellent. On the other hand, if the value calculated by the following formula (2) is higher than 48.0, the brittle fracture surface ratio is high, and sufficient toughness cannot be ensured, and the welding wire composition is formed by combining elements that may deviate in toughness depending on the welding portion. Therefore, the value calculated by the following formula (2) is preferably 48.0 or less, more preferably 40.0 or less.

Formula (2):

33.9×[Si]－47.0×[Mn]－22.2×[Ni]－11.9×[Mo]－203.9×[C]－443.5×[REM]－4482.2×[B]－36.1×[Cr]－15281×[P]+47868×[S]

< value calculated by the following formula (3): 0.09 >, above

The formula (3) is used for adjusting mechanical properties such as strength, toughness and the like by multiple regression analysis of elements related to carbon equivalent and cold crack sensitivity, and "balance of strength and toughness at-46℃"

(parameters of CVN (-46 ℃ C.)/TS). Here, CVN means pendulum impact absorption work (J), and TS means tensile strength (MPa). When the value calculated from the following formula (3) is 0.09 or more based on the content of each element, the composition of the welding wire is obtained by combining elements having a good balance between strength and toughness. On the other hand, if the value calculated by the following formula (3) is lower than 0.09, the welding wire composition is composed of elements having poor balance between strength and toughness. Therefore, the value calculated by the following formula (3) is preferably 0.09 or more, more preferably 0.10 or more.

Formula (3):

0.001×[Fe]－0.71×[Si]+0.08×[Mn]－0.08×[Al]+0.69×[Zr]+0.03×[Ni]+0.01×[Mo]+0.32×[C]+2.27×[REM]+9.57×[B]+0.11×[Cr]

< value calculated by the following formula (4): 0.14 or more >)

The formula (4) is used for adjusting mechanical properties such as strength, toughness and the like, and is characterized by analyzing elements related to carbon equivalent and cold crack sensitivity and 'balance of strength and toughness at-20 ℃ by multiple regression'

(parameters of CVN (-20 ℃ C.)/TS). Here, CVN means the work of absorption (J) of pendulum impact, and TS means the tensile strength (MPa). When the value calculated by the following formula (4) is 0.14 or more based on the content of each element, the composition of the welding wire is obtained by combining elements having a good balance between strength and toughness. On the other hand, if the value calculated by the following formula (4) is lower than 0.14, the welding wire composition becomes a combination of elements having poor balance between strength and toughness.

Formula (4):

0.003×[Fe]－0.35×[Si]+0.09×[Mn]－0.13×[Al]+0.22×[Zr]+0.02×[Ni]－0.02×[Mo]－0.11×[C]+1.17×[REM]+4.30×[B]+0.09×[Cr]

next, each element contained for the purpose of improving operability, adjusting mechanical properties, and the like will be described. The elements described below satisfy the above formulas (1) to (4) to achieve a good balance between strength and toughness, but in the technical common sense, if any element other than Fe is excessively added, weld cracks or the like may occur, so that the upper limit of each element is defined. Further, the content of the element may be as required for the purpose of improving the handleability, adjusting the mechanical properties, and the like, and it is understood that the definition of the element below without the lower limit includes 0 mass%.

＜Fe _(Wire) :85.0 mass% or more

Among the elements contained in order to satisfy the required mechanical properties, fe is a main element among the steel types commonly used in large quantities, such as mild steel, high tensile steel, and low temperature steel. If Fe is _(Wire) If the content of (2) is less than 85 mass%, the influence of the other elements becomes large, and the mechanical properties may be deteriorated. Thus, the first and second substrates are bonded together,Fe _(Wire) the content of (2) is 85 mass% or more, preferably 87.0 mass% or more, based on the total mass of the wire. Examples of the Fe source in the welding wire include Fe metal powder added to the flux, fe alloy metal powder, fe compound, fe contained in the strip steel, and the like. When Fe is contained in the flux, it is preferable to contain Fe in the form of metal powder of Fe or alloy metal powder of Fe from the viewpoint of improving the welding amount.

＜C _(Wire) :0.050 mass% or less

C is a component that affects the strength of the deposited metal and the welded metal, and if the C content in the deposited metal or the welded metal increases, the strength increases. In general, steel grades such as mild steel, high-tension steel, low-temperature steel, etc. are used in large quantities, and it is preferable to include C in the welding wire in order to satisfy the required strength range. However, if C _(Wire) If the content of (c) is increased, carbide is likely to be deposited in the deposited metal or the weld metal, and the toughness is lowered with respect to the target strength, and there is a possibility that the balance between strength and toughness may be lost. Thus C _(Wire) The content of (2) is 0.050 mass% or less, preferably 0.040 mass% or less, based on the total mass of the wire.

On the other hand, to adjust the strength, C _(Wire) The content of (2) is preferably 0.001 mass% or more relative to the total mass of the wire. Examples of the C source in the welding wire include graphite, carbide, and the like added to the flux, and C contained in the strip steel. However, from the viewpoint of carbide inhibition, C _(Wire) The smaller the content, the better, and more preferably the flux contains no C.

＜Si _(Wire) :0.60 mass% or less

Si is a component that affects the strength and toughness of the weld metal. In general, a large number of steel types such as mild steel, high-tension steel, and low-temperature steel are used, and in order to satisfy the required mechanical properties, it is preferable to include Si in the welding wire. Si has deoxidizing effect, and if Si is excessively contained in the wire, the inclusions increase, and the balance between strength and toughness may be lost. Thus, si is _(Wire) The content of (2) is 0.60 mass% or less, preferably 0.50 mass% or less, based on the total mass of the wireAnd (3) downwards.

On the other hand, si for adjusting strength _(Wire) The content of (2) is preferably 0.01 mass% or more relative to the total mass of the wire. The Si source in the welding wire includes Si metal powder added to the flux, si alloy metal powder, si compound, si contained in the strip steel, and the like. When Si is contained in the flux for the purpose of suppressing inclusions, it is preferable that Si is contained as a metal powder of Si or an alloy metal powder of Si.

＜B _(Wire) :0.0200 mass% or less

B is an element that increases crack resistance while preventing the toughness of the deposited metal and the weld metal from decreasing. Thus B _(Wire) The content of (2) is 0.0200 mass% or less, preferably 0.0150 mass% or less, based on the total mass of the wire. In addition, by including B in the welding wire according to the present embodiment, a decrease in the brittle fracture surface rate was confirmed. This is because, by including B in the welding wire, coarse ferrite phase or bainite phase generated in the grain boundary can be suppressed. Therefore, from the viewpoint of reducing the brittle fracture surface rate, B _(Wire) The content of (2) is preferably 0.0020 mass% or more relative to the total mass of the wire. In addition, zr _(Wire) Content and B _(Wire) The content results in a change in the balance of strength and toughness, therefore, B _(Wire) The preferred range of the content is based on Zr _(Wire) Is a content change of (c). That is, if Zr _(Wire) When the content of (B) is 0.045 mass% or less, B is preferably as described above _(Wire) The content of (3) is 0.0150 mass% or less, but if Zr _(Wire) If the content of (B) is more than 0.045 mass%, B is more preferably used _(Wire) The content of (2) is 0.0045 mass% or less.

Examples of the source of B in the welding wire include B metal powder added to the flux, B alloy metal powder, B compound, and B contained in the strip steel.

If B is contained as an oxide in the flux, the oxide of B is easily and uniformly mixed in the flux, which is advantageous from the viewpoint of production. Therefore, B is preferably contained in the flux in the form of an oxide, not in the form of a metal powder. In this case, B _(Wire) The content of (2) includes a B conversion value of B oxide, and the value calculated from the following formula (5) is preferably 0.5 or more, more preferably 0.7 or more, and still more preferably 1.0. When the value calculated by the following formula (5) is 1.0, B _(Wire) The content of (2) is expressed as a B-converted value of B oxide. In other words, when B is contained in the welding wire, it is preferable that all of B is contained in the flux as an oxide of B.

Formula (5): [ B oxide ]/[ B ]

In the above formula (5), the so-called [ B oxide ]]B conversion value representing B oxide relative to the total mass of the welding wire in mass% relative to the total mass of the welding wire _(Wire) Is a value of (2).

＜Mn _(Wire) :2.00 mass% or less

Mn is a component that affects the strength and toughness of the weld metal, similarly to Si. In general, a large number of steel grades such as mild steel, high tensile steel, low temperature steel, etc. are used, and in order to satisfy the required mechanical properties, it is preferable to include Mn in the welding wire. Mn has deoxidizing effect, and if Mn is excessively contained in the wire, the number of inclusions increases, and the balance between strength and toughness may be lost. Thus, mn _(Wire) The content of (2) is 2.00 mass% or less, preferably 1.80 mass% or less, based on the total mass of the wire.

On the other hand, in order to adjust the strength, mn _(Wire) The content of (2) is preferably 0.01 mass% or more relative to the total mass of the wire. The Mn source in the welding wire includes Mn metal powder added to the flux, mn alloy metal powder, mn compound, mn contained in the steel strip, and the like. When Mn is contained in the flux for the purpose of suppressing inclusions, it is preferable that Mn is contained in the flux as a metal powder of Mn or an alloy metal powder of Mn.

＜P _(Wire) :0.0150 mass% or less

P is an element that reduces crack resistance and mechanical properties of the weld metal. Thus, P _(Wire) The content of (2) is suppressed to 0.0150 mass% or less, preferably 0.0100 mass% or less, based on the total mass of the wire. It is preferable that P is not forcibly added to the wire.

＜S _(Wire) :0.0150 massLess than% by weight

S is an element that reduces crack resistance. Thus S _(Wire) The content of (2) is 0.0150 mass% or less, preferably 0.010 mass% or less, based on the total mass of the wire.

On the other hand, S _(Wire) The viscosity and surface tension of the molten droplet are reduced when the welding wire is melted, and the molten droplet is smoothly transited, so that the spatter is made small and granulated, and the welding operability is improved. Therefore, from the viewpoint of welding operability, S _(Wire) The content of (2) is preferably 0.0005 mass% or more based on the total mass of the wire. The S source in the welding wire is not limited to the so-called S source, and may be contained in the flux as a powder of S monomer or S compound, or may be contained in the strip steel, and it is more preferable not to forcibly add S to the welding wire.

＜Cr _(Wire) :1.00 mass% or less

Cr is a component that affects the strength and toughness of the deposited metal and the weld metal. In general, steel grades such as mild steel, high-tension steel, low-temperature steel, etc. are used in large quantities, and in order to satisfy the required mechanical properties, it is preferable to include Cr in the welding wire. If Cr is excessively contained in the welding wire, it is likely to precipitate as carbide at the grain boundary, and the balance between strength and toughness may be lost. Thus, cr _(Wire) The content of (2) is preferably 1.00 mass% or less and 0.90 mass% or less relative to the total mass of the wire.

On the other hand, in order to adjust the strength, cr _(Wire) The content of (2) is preferably 0.20 mass% or more relative to the total mass of the wire. The Cr source in the welding wire includes Cr metal powder added to the flux, cr alloy metal powder, cr compound, cr contained in the steel strip, and the like. When Cr is contained in the flux, it is preferable that Cr is contained in the flux as a metal powder of Cr or an alloy metal powder of Cr.

＜Mo _(Wire) :1.00 mass% or less

Mo is a component that improves high temperature strength. In general, a large number of steel grades such as mild steel, high-tension steel, and low-temperature steel are used, and in order to satisfy the required mechanical properties, mo is preferably contained in the welding wire. If welding wireIf Mo is excessively contained in the steel, the strength is excessively increased, and the balance between strength and toughness may be lost. Thus, mo _(Wire) The content of (2) is preferably 1.00 mass% or less and 0.90 mass% or less based on the total mass of the wire.

On the other hand, mo for adjusting strength _(Wire) The content of (2) is preferably 0.10 mass% or more relative to the total mass of the wire. The Mo source in the welding wire includes Mo metal powder added to the flux, mo alloy metal powder, mo compound, mo contained in the strip steel, and the like. When Mo is contained in the flux, mo is preferably contained in the flux as a metal powder of Mo or an alloy metal powder of Mo.

In addition, the combination of Cr contributing to strength and toughness and Mo, which is a common element for improving high-temperature strength, is preferably determined in accordance with the use, as shown below, in order to balance strength and toughness.

(design for toughness improvement)

For example, when the toughness is to be further improved, the content of Cr contributing to the strength and toughness is preferably made larger than the content of Mo. Namely, cr is made to _(Wire) Is 0.20 mass% or more and 0.90 mass% or less relative to the total mass of the welding wire, and Mo is contained in the welding wire _(Wire) The content of (2) is 0.50 mass% or less relative to the total mass of the wire, preferably 0.20 or more, more preferably 0.50 or more, still more preferably 0.75 or more, and most preferably 1.00 as calculated from the following formula (6).

Formula (6): [ Cr ]/([ Cr ] + [ Mo ])

(design for improving high-temperature Strength)

On the other hand, in the case of use as heat-resistant steel, it is preferable to make the content of Mo, which is generally used as a high-temperature strength-improving element, more than the content of Cr, that is, to make Cr _(Wire) Is 0.90 mass% or less relative to the total mass of the welding wire, and Mo is contained in the welding wire _(Wire) The content of (2) is preferably 0.10 mass% or more and 0.80 mass% or less relative to the total mass of the wire, and the value calculated from the following formula (7) is preferably 0.10 or more and 0.45 or more, more preferably 0.70 or more, and most preferably 1.00.

Formula (7): [ Mo ]/([ Cr ] + [ Mo ])

＜Al _(Wire) :3.00 mass% or less

Al is a strongly deoxidizing component, and forms oxides (hereinafter also referred to as "slag") on a molten pool by oxidation reaction in a weld metal, so that the weld bead shape and burn-through resistance can be improved in full-position welding including difficult positions such as vertical welding and overhead welding. If Al is excessively contained in the welding wire, inclusions remaining in the weld metal increase, which adversely affects toughness. Thus, al _(Wire) The content of (2) is 3.00 mass% or less, preferably 2.50 mass% or less, and more preferably 1.70 mass% or less, based on the total mass of the wire.

On the other hand, al _(Wire) The content of (2) is preferably 0.50 mass% or more, more preferably 1.00 mass% or more, based on the total mass of the wire. Examples of the Al source in the welding wire include Al powder added to the flux, al alloy powder, al compound, and Al contained in the strip steel. When the flux contains Al in order to further reduce the amount of oxygen in the weld metal, it is preferable that Al be contained in the flux as a metal powder of Al or an alloy metal powder of Al.

＜Mg _(Wire) :3.00 mass% or less

Mg is a strong deoxidizing component like Al, and oxidation reaction occurs in the weld metal to form slag on the molten pool, so that the burn-through resistance can be improved in all-posture welding including difficult posture such as vertical welding and overhead welding. If Mg is excessively contained in the welding wire, inclusions remaining in the weld metal increase, which adversely affects toughness. Thus, mg is _(Wire) The content of (2) is 3.0 mass% or less, preferably 1.50 mass% or less, and more preferably 1.00 mass% or less, based on the total mass of the wire.

On the other hand, mg _(Wire) The content of (2) is preferably 0.30 mass% or more, more preferably 0.50 mass% or more, based on the total mass of the wire. Examples of the Mg source in the welding wire include Mg metal powder added to the flux, mg alloy metal powder, mg compound, mg contained in the strip steel, and the like. To further reduce the oxygen content in the solder metal, M is contained in the fluxIn g, it is preferable that the flux contains Mg metal powder or Mg alloy metal powder.

＜Zr _(Wire) :3.000 mass% or less

Zr is a strong deoxidizing component like Al, and forms slag on the molten pool by oxidation reaction in the weld metal, so that the burn-through resistance can be improved in all-posture welding including difficult posture such as vertical welding and overhead welding. If Zr is excessively contained in the welding wire, inclusions remaining in the weld metal increase, which adversely affects toughness. Thus, zr _(Wire) The content of (2) is 3.000 mass% or less, preferably 0.500 mass% or less, based on the total mass of the wire, if B is taken into consideration _(Wire) The content of (2) is more preferably 0.045 mass% or less.

On the other hand, define Zr _(Wire) The lower limit of (2) is not particularly limited. In addition, when the welding wire mainly contains Mg and Al as the strong deoxidizing element, zr is preferable _(Wire) The content of (2) is 0. Examples of the Zr source in the welding wire include Zr metal powder added to the flux, zr alloy metal powder, zr compound, ti contained in the strip steel, and the like. When Zr is contained in the flux for the purpose of further reducing the amount of oxygen in the weld metal, it is preferable to contain Zr in the flux as a metal powder of Zr or an alloy metal powder of Zr.

＜Ti _(Wire) :3.000 mass% or less

Ti is a strong deoxidizing component like Al, and oxidation reaction occurs in the weld metal to form oxides (slag) in the molten pool, so that the burn-through resistance can be improved in all-posture welding including difficult posture such as vertical welding and overhead welding. If Ti is excessively contained in the welding wire, inclusions remaining in the weld metal increase, which adversely affects toughness. Thus Ti is _(Wire) The content of (2) is 3.000 mass% or less, preferably 0.500 mass% or less, and more preferably 0.010 mass% or less, based on the total mass of the wire.

On the other hand, ti has a smaller effect as a deoxidizing component than Mg and Al, and may also form precipitates such as TiC that deteriorate toughness. Therefore, define Ti _(Wire) Lower limit of (2)The value is not particularly significant, and when the welding wire mainly contains Mg, al, ti _(Wire) The content of (2) is preferably 0. The Ti source in the welding wire includes Ti metal powder added to the flux, ti alloy metal powder, ti compound, ti contained in the strip steel, and the like. When the flux contains Ti in order to further reduce the amount of oxygen in the weld metal, it is preferable that Ti metal powder or Ti alloy metal powder be contained in the flux.

＜Ca _(Wire) :3.00 mass% or less

Ca is a strongly deoxidizing component, and oxidation reaction occurs in the weld metal to form oxides (slag) in the molten pool, so that the burn-through resistance can be improved in all-posture welding including difficult posture such as vertical welding and overhead welding. However, if Ca is excessively contained in the welding wire, inclusions remaining in the weld metal increase, which adversely affects toughness. Thus, ca _(Wire) The content of (2) is 3.0 mass% or less, preferably 1.00 mass% or less, more preferably 0.30 mass% or less, based on the total mass of the wire.

On the other hand, ca is produced by reacting as a fluoride CaF ₂ The inclusion in the flux contributes to improvement of deoxidizing action of the weld metal and welding workability. The Ca described above _(Wire) Comprises CaF in the flux ₂ The Ca conversion value of (2) is not limited to CaF, but is a fluoride in the flux ₂ For example, baF can be used ₂ 、SrF ₂ Etc., and therefore there is no need to set the lower limit of the Ca content. In addition, when Mg and Al are mainly added to the wire as strong deoxidizing components, ca is preferably used as the deoxidizing component _(Wire) The content of (2) was 0% by mass.

The source of Ca in the welding wire includes Ca metal powder added to the flux, ca alloy metal powder, ca compound, ca contained in the strip steel, and the like. In the present embodiment, when Ca is contained in the welding wire, if this Ca is contained in the flux, the amount of oxygen in the weld metal can be further reduced. Therefore, all Ca contained in the wire is preferably in the form of fluoride powder, i.e., caF ₂ Is contained in the flux.

In addition to the above-mentioned list Al, mg, zr, ti, ca, various elements are also present, and in the present embodiment, the above-mentioned 5 elements that are generally contained in the wire mainly in the form of metal powder are preferable as the strong deoxidizing elements as the elements to be contained in the basic flux-cored wire.

Among the above 5 elements, al and Mg in particular are elements useful for realizing welding in a difficult posture using an alkaline flux-cored wire because slag is easily aggregated and formed on the surface of the molten pool in early stages and in the entire region of the surface of the molten pool. On the other hand, zr, ti and Ca tend to disperse slag, and slag tends to form concentrated in time due to the flow of the molten pool, and the effect is inferior to that of Al and Mg.

Therefore, it is preferable to include at least one strong deoxidizing element of Al, mg, ti, ca and Zr in the welding wire. In addition, regarding the content of each element, al _(Wire) 1.00 mass% or more and 2.50 mass% or less of Mg _(Wire) 0.30 to 0.50 mass% of Ti _(Wire) 0.10 mass% or less (0 mass%) of Zr _(Wire) 0.20 mass% or less (0 mass%) of Ca _(Wire) The total amount of the strong deoxidizing elements contained in the wire is not more than 0.10 mass% (0 mass%), and not less than 1.50 mass% and not more than 4.00 mass%.

In the present embodiment, at least one of Al and Mg is more preferably contained, and at least Al is more preferably contained. In this case, it is particularly preferable to make Al with respect to the total mass of the wire _(Wire) Contains 1.00 mass% or more and 2.50 mass% or less of Mg _(Wire) 1.00 mass% or less, and a value calculated from the following formula (8) is 0.5 or more and 1.0 or less.

Formula (8): [ Al ]/([ Al ] + [ Mg ])

＜Ni _(Wire) :5.00 mass% or less

Ni stabilizes the austenitic structure of the weld metal, and is a component that improves toughness at low temperatures, and is a component that can adjust the amount of crystal of the ferrite composition. Steel generally used in large quantities such as mild steel, high tensile steel, low temperature steel and the like In the above, in order to satisfy the required mechanical properties, ni is preferably contained in the welding wire. If Ni is excessively contained in the wire, the strength is excessively increased, and the balance between strength and toughness may be lost. Thus Ni _(Wire) The content of (2) is 5.0 mass% or less, preferably 3.0 mass% or less, based on the total mass of the wire.

On the other hand, when used for welding low-temperature steel or the like, ni _(Wire) The content of (2) is preferably 0.20 mass% or more relative to the total mass of the wire. The Ni source in the welding wire includes Ni metal powder of Ni added to the flux, ni alloy metal powder, ni compound, ni contained in the strip, and the like. When Ni is contained in the flux for the purpose of further reducing the amount of oxygen in the weld metal, it is preferable that Ni is contained in the flux as a metal powder of Ni or an alloy metal powder of Ni.

＜Ba _(Wire) :4.00 mass% or less

Ba mainly being fluoride BaF ₂ Is contained in the flux, thereby contributing to the deoxidization of the weld metal and the improvement of the welding workability. Fluoride is generally added as flux of alkaline flux-cored wire, and BaF is used among various fluorides ₂ . However, if Ba is excessively contained in the wire, arc deflection occurs, and there is a possibility that the welding operability may deteriorate. Thus, ba _(Wire) The content of (2) is 4.00 mass% or less, preferably 3.00 mass% or less.

Also, the Ba _(Wire) The content of (2) including BaF in the flux ₂ The Ba conversion value of (2) is not limited to BaF as fluoride in the flux ₂ For example, caF can be used ₂ 、SrF ₂ And the like, and therefore, it is not necessary to set the lower limit of the Ba content. However, the flux contains BaF ₂ Or BaCO ₃ When the Ba compound is equal to Ba _(Wire) The content is preferably 1.75 mass% or more based on the total mass of the welding wire. Examples of the Ba source in the bonding wire include Ba metal powder added to the flux, ba alloy metal powder, ba compound, and Ba contained in the strip steel. In the present embodiment, when Ba is contained in the bonding wire, it is preferable to use all Ba as fluoride BaF ₂ Is contained in the flux.

＜F _(Wire) :2.00 mass% or less

F _(Wire) Mainly from fluorides. The above-mentioned fluoride forms of Ca, ba, sr, etc. are contained in the flux of the flux-cored wire. Fluoride is commonly added in alkaline flux-cored wires, contributing to improvement of welding operability. However, F _(Wire) If the content of (2) is higher than 2.00 mass% relative to the total mass of the wire, the phenomenon of excessive vaporization of F occurs in the wire, and there is a possibility that deterioration of welding operability such as an increase in the amount of spatter generated may occur. Thus, ba _(Wire) The content of (2) is 2.00 mass% or less, preferably 1.00 mass% or less, and more preferably 0.80 mass% or less, based on the total mass of the wire.

On the other hand, when F is contained in the wire for the purpose of improving the welding workability, F _(Wire) The content of (2) is preferably 0.40 mass% or more relative to the total mass of the wire. The F source in the wire is preferably all derived from fluoride, and examples thereof include BaF ₂ 、SrF ₂ 、Na ₃ AlF ₆ 、NaF、CaF ₂ 、AlF ₃ 、MgF ₂ And the like, one or two or more thereof may be contained. Among these fluorides, the fluoride is exemplified by BaF ₂ 、SrF ₂ 、CaF ₂ At least one fluoride selected from the group consisting of the above-mentioned contents described in the columns of Ba, sr and Ca is preferably contained in the wire from the viewpoint of welding workability. Further, since Ba has a low work function and an effect of further stabilizing the cathode point and contributes to improvement of soldering workability, baF mainly used as Ba fluoride is more preferable in the present embodiment ₂ Is contained in the welding wire. In the present embodiment, all of Ba is preferable _(Wire) The source is BaF ₂ F above _(Wire) In the content of (2) except BaF ₂ F other than the F converted value of (2) _(Wire) The balance of the content of (C), preferably CaF ₂ Is a supply source.

The following elements may be added to steel grades which are generally used in large quantities, such as mild steel, high tensile steel, and low temperature steel, in addition to or instead of the above elements, for the purpose of adjusting mechanical properties and improving welding workability within a general technical range. The following Nb, cu, W, ta, V, sr and alkali elements are not added in the present embodiment, and are preferably added in the optimum range described below when various generally known effects are expected, although no special addition is required.

＜Nb _(Wire) :0.50 mass% or less

Nb is a component that affects mechanical properties such as strength. In general, steel grades such as mild steel, high tensile steel, low temperature steel, etc. which are used in large quantities, nb may be contained in the welding wire in order to satisfy the required mechanical properties. In this case, nb _(Wire) The content of (c) is preferably 0.50 mass% or less, more preferably 0.30 mass% or less, based on the total mass of the wire. Examples of the Nb source in the welding wire include Nb metal powder added to the flux, nb alloy metal powder, nb compound, nb contained in the strip steel, and the like.

＜Cu _(Wire) :2.0 mass% or less

Cu is an element contributing to improvement in strength and weather resistance of the weld metal. In general, a large number of steel grades such as mild steel, high-tension steel, low-temperature steel, etc. may be used, and Cu may be contained in the wire in order to satisfy the required strength and weather resistance. In this case, cu _(Wire) The content of (2) is preferably 2.0 mass% or less, more preferably 1.0 mass% or less, based on the total mass of the wire.

On the other hand, when Cu is contained in the wire for the purpose of securing strength and weather resistance of the weld metal, cu _(Wire) The content of (2) is preferably 0.01 mass% or more relative to the total mass of the wire. The Cu source in the wire includes Cu plating on the surface of the wire in addition to Cu metal powder, cu alloy metal powder, cu compound, cu contained in the strip steel, and the like added to the flux.

＜W _(Wire) :1.00 mass% or less

W is a component that improves high-temperature strength and pitting corrosion resistance. In steel grades such as mild steel, high tensile steel, low temperature steel and the like which are generally used in large quantitiesIn order to satisfy the required mechanical properties, W may be contained in the welding wire. In this case, W _(Wire) The content of (2) is preferably 1.00 mass% or less, more preferably 0.5 mass% or less, based on the total mass of the wire. The source of W in the welding wire includes W metal powder added to the flux, W alloy metal powder, W compound, and W contained in the strip steel.

＜Ta _(Wire) :1.00 mass% or less

Ta is an element that affects mechanical properties such as strength. In general, a large number of steel grades such as mild steel, high-tension steel, and low-temperature steel are used, and Ta may be contained in the welding wire in order to satisfy the required mechanical properties. In this case, ta _(Wire) The content of (2) is preferably 1.00 mass% or less, more preferably 0.50 mass% or less, based on the total mass of the wire. Examples of the Ta source in the welding wire include Ta powder added to the flux, ta alloy powder, ta compound, and Ta contained in the strip steel.

＜V _(Wire) :1.00 mass% or less

V exerts an effect of improving the strength of the weld metal, and is an element that reduces toughness and crack resistance. Thus, V in the welding wire _(Wire) The content of (2) is preferably 1.00 mass% or less, more preferably 0.50 mass% or less, based on the total mass of the wire. The V source in the welding wire includes V metal powder added to the flux, V alloy metal powder, V compound, V contained in the strip steel, and the like.

＜Sr _(Wire) :4.00 mass% or less

Sr is mainly used as fluoride SrF ₂ Is contained in the flux, thereby contributing to improvement of deoxidizing action of the weld metal and welding operability. However, if the Sr content in the wire is 4.00 mass% or less, arc deflection can be suppressed, and good welding operability can be obtained. Thus Sr _(Wire) The content of (c) is preferably 4.00 mass% or less, more preferably 3.00 mass% or less, based on the total mass of the wire.

The Sr _(Wire) Comprises SrF in the flux ₂ The Sr equivalent of (2) is not limited to SrF, but is a fluoride in the flux ₂ For example, caF can also be used ₂ 、BaF ₂ And the like, and therefore, it is not necessary to set the lower limit of the Sr content. However, the flux contains SrF ₂ Or SrCO ₃ When the Sr compound is equal, sr _(Wire) The content is preferably 0.05 mass% or more relative to the total mass of the welding wire. Examples of the Sr source in the welding wire include Sr metal powder added to the flux, sr alloy metal powder, sr compound, sr contained in the steel strip, and the like. In the present embodiment, when Sr is contained in the welding wire, it is preferable to use all Sr as fluoride SrF ₂ Is contained in the flux.

As described above, in the alkaline flux-cored wire of the present embodiment, the flux preferably contains a fluoride BaF of Ba, ca, and Sr ₂ 、CaF ₂ And SrF ₂ At least one selected from the group consisting of (a) and (b). In this case, the content of Ba includes BaF ₂ The Ca content includes CaF ₂ The content of Sr includes SrF ₂ The content of F includes BaF ₂ 、CaF ₂ And SrF ₂ F converted value of (c). It is preferable that all of the F sources in the welding wire are derived from fluoride, that is, the F content in the welding wire is equal to the F conversion value of the total fluoride contained in the flux.

Sum of alkali metals: 3.00 mass% or less

The alkali metal element acts as an arc stabilizer. The alkali metal of the present embodiment is based on metal powders and compounds containing one or more alkali metal elements. Examples of the alkali metal element include K, li, and Na. The total content of alkali metals in the welding wire means the total content of alkali metals in the welding wire in terms of metal powder and compound composed of alkali metal elements. Namely, K _(Wire) 、Li _(Wire) 、Na _(Wire) Etc. The total amount of alkali metals in the wire is preferably 3.00 mass% or less, more preferably 2, based on the total mass of the wire, from the viewpoint of easy adjustment to the melting characteristics preferable for improvement of the weld path shape.00 mass% or less.

( Oxides in the wire: 0.005 to 0.100 mass% )

Since oxides are the basis of coarse inclusions and affect toughness, it is preferable to avoid addition of oxides to the flux as much as possible. Therefore, the total amount of oxides of the elements added to the flux is preferably 0.100 mass% or less based on the mass% of the total mass of the welding wire. From the viewpoint of production, B and REM may be added as oxides, and more preferably 0.005 mass% or more of the oxides is contained.

(the balance O, N and unavoidable impurities)

In the present embodiment, the balance other than the above elements is preferably O, N and unavoidable impurities, and the total of the balance is preferably 0.50 mass% or less. The impurities mean unintentional addition, and examples of the other elements than the above elements include Sn, co, sb, as. The total content of impurities in the welding wire is preferably 0.45 mass% or less, more preferably 0.30 mass% or less.

In addition, O, N when the above elements are contained in the flux as oxides or nitrides or dissolved in the strip steel is also included in the balance. In the flux-cored wire, O, N cannot be clearly analyzed, but in the present embodiment, the total amount of O and N can be estimated to be 0.05 mass% or less based on the amount of oxide added to the flux-cored wire or O, N amount added to the strip steel, based on mass% relative to the total mass of the wire. In addition, in the alkaline flux-cored wire, O, N is higher than 0.05 mass%, and it is impossible in the technical sense from the viewpoint of mechanical properties.

[ strip steel ]

The flux-cored wire of the present embodiment is a wire in which a flux is filled in a strip steel, and the strip steel is formed of a cold-rolled steel strip, and is preferable from the viewpoints of usability and economy. As the cold-rolled steel strip, for example, JIS G3141 is preferably used: 2017, type number SPCC, SPCD, SPCE, SPCF, SPCG, etc.

Another embodiment of the present inventionThe alkaline flux-cored wire of (2) is a wire for obtaining a deposited metal shown below. In addition, the welding wire can be defined by defining the composition of the deposited metal obtained under the welding conditions that are generally used in order to represent the metal that transitions from the repair material to the welded portion. The welding conditions generally used may be, for example, welding conditions according to the method for producing a deposited metal described in JIS Z3184. For example, the following conditions and the like can be used for the welding current: 200-220A, welding voltage: 0-23V, shielding gas: 100% CO ₂ Gas, weld line energy: 0.8-1.1 kJ/mm.

[2 ] deposited Metal ]

As described above, the alkaline flux-cored wire of the present embodiment can perform welding in a difficult posture and can obtain a good balance between strength and toughness by containing the strong deoxidizing element and REM. Similarly, the deposited metal of the present embodiment appropriately defines B _(Metal) In (2) as REM, la is properly defined _(Metal) And Ce (Ce) _(Metal) The content of (3) can thereby further enhance the above-mentioned effects. The composition and reasons for limiting the deposited metal according to the present embodiment will be specifically described below.

＜C _(Metal) : 0.020% by mass or more and 0.100% by mass or less

C is a component affecting the strength of the deposited metal, and if the C content in the deposited metal increases, the strength increases. Thus C _(Metal) The content of (2) is 0.020 mass% or more, preferably 0.040 mass% or more, based on the total mass of the deposited metal.

On the other hand, if C _(Metal) If the content of (c) is increased, carbide is likely to be precipitated in the deposited metal, and the toughness is lowered with respect to the target strength, and the balance between strength and toughness may be lost. Thus C _(Metal) The content of (2) is 0.100 mass% or less, preferably 0.095 mass% or less, based on the total mass of the deposited metal.

＜Si _(Metal) :0.05 mass% or more and 0.50 mass% or less

Si is a component affecting the strength and toughness of the deposited metal byThe deposited metal contains Si in a predetermined content, and can satisfy the required chemical properties. Thus, si is _(Metal) The content of (b) is preferably 0.05 mass% or more, more preferably 0.10 mass% or more, based on the total mass of the deposited metal.

On the other hand, si has a deoxidizing effect, and if Si is excessively contained, si is highly likely to remain as inclusions in the deposited metal, and there is a possibility that the balance between strength and toughness may be lost. Thus, si is _(Metal) The content of (2) is 0.50 mass% or less, preferably 0.45 mass% or less, based on the total mass of the deposited metal.

＜Mn _(Metal) :0.20 mass% or more and 1.80 mass% or less

Mn is a component that affects the strength and toughness of the deposited metal, like Si, and can satisfy the required mechanical properties by containing Mn in a predetermined content in the deposited metal. Thus, mn _(Metal) The content of (b) is preferably 0.20 mass% or more, more preferably 0.50 mass% or more, based on the total mass of the deposited metal.

On the other hand, mn has a deoxidizing effect, and if Mn is excessively contained, mn is highly likely to remain as inclusions in the deposited metal, and there is a possibility that the strength and toughness may be out of balance. Thus, mn _(Metal) The content of (2) is 1.80 mass% or less, preferably 1.65 mass% or less, based on the total mass of the deposited metal.

＜Al _(Metal) :0.30 mass% or more and 1.50 mass% or less

Al is a strongly deoxidizing component, and forms oxides (slag) on a molten pool by oxidation reaction in a deposited metal, and is considered to be an element preferably contained in a welding wire because it improves burn-through resistance in full-length welding including difficult welding such as vertical welding and overhead welding. Thus, al _(Metal) The content of (c) is preferably 0.30 mass% or more, more preferably 0.40 mass% or more, based on the total mass of the deposited metal.

On the other hand, if Al is excessively contained, al is highly likely to remain as inclusions in the deposited metal, and adversely affects toughness. Thus, al _(Metal) Content of (3)The amount of the metal to be deposited is 1.50 mass% or less, preferably 1.10 mass% or less, and more preferably 1.00 mass% or less, based on the total mass of the metal to be deposited.

＜La _(Metal) :0.008 mass% or less

La is one of REM contained in a welding wire, and functions as a binder that aggregates oxides of a strong deoxidizing element in deposited metal. In the present embodiment, although the lower limit of the La content in the deposited metal is not particularly set, la is used to obtain the above-described effect _(Metal) The content of (2) is preferably 0.001 mass% or more based on the total mass of the deposited metal.

On the other hand, if La _(Metal) If the content of (2) is more than 0.008 mass%, the inclusion may be coarsened due to the agglomeration, which may adversely affect the mechanical properties or may cause unacceptable weld defects. Therefore La _(Metal) The content of (2) is 0.008 mass% or less, preferably 0.006 mass% or less, based on the total mass of the deposited metal.

＜Ce _(Metal) :0.002 mass% or more and 0.010 mass% or less

Ce is one of REM contained in a welding wire, and acts as a binder for agglomerating oxides of a strong deoxidizing element in a deposited metal, similarly to La. Thus Ce _(Metal) The content of (2) is 0.002 mass% or more, preferably 0.003 mass% or more, based on the total mass of the deposited metal.

On the other hand, if Ce _(Metal) If the content of (2) is more than 0.010 mass%, the inclusion may be coarsened due to the agglomeration, which may adversely affect the mechanical properties or may cause unacceptable weld defects. Thus Ce _(Metal) The content of (2) is 0.010 mass% or less, preferably 0.009 mass% or less, based on the total mass of the deposited metal.

＜Fe _(Metal) :85.0 mass% or more

Among the elements contained in order to satisfy the required mechanical properties, fe is a main element among the steel types commonly used in large quantities, such as mild steel, high tensile steel, and low temperature steel. If Fe is _(Metal) Is less than 85 massThe influence of the remaining elements becomes large, and the mechanical properties may deteriorate. Thus Fe _(Metal) The content of (2) is 85 mass% or more, preferably 87.0 mass% or more, based on the total mass of the deposited metal.

＜P _(Metal) :0.0200 mass% or less

P is an element that reduces crack resistance and mechanical properties of the deposited metal. Thus, P _(Metal) The content of (2) is 0.020 mass% or less, preferably 0.0100 mass% or less, based on the total mass of the deposited metal.

＜S _(Metal) :0.0200 mass% or less

S is an element that reduces crack resistance. Thus S _(Metal) The content of (2) is 0.0200 mass% or less, preferably 0.0100 mass% or less, based on the total mass of the deposited metal.

＜Cr _(Metal) :1.00 mass% or less

Cr is a component that affects the strength and toughness of the deposited metal, but if Cr is excessively contained in the deposited metal, cr is likely to precipitate as carbide at grain boundaries, and there is a possibility that the balance between strength and toughness may be lost. Thus, cr _(Metal) The content of (2) is 1.00 mass% or less relative to the total mass of the deposited metal.

＜Mo _(Metal) :1.00 mass% or less

Mo is a component that improves high-temperature strength, but if Mo is excessively contained in the deposited metal, the strength is excessively increased, and there is a possibility that the balance between strength and toughness may be lost. Thus, mo _(Metal) The content of (2) is 1.00 mass% or less relative to the total mass of the deposited metal.

＜Mg _(Metal) :0.50 mass% or less

Mg is a strongly deoxidizing component similar to Al, and if Mg is excessively contained, mg is highly likely to remain as inclusions in the deposited metal, and adversely affects toughness. Thus, mg is _(Metal) The content of (2) is 0.50 mass% or less, preferably 0.30 mass% or less, and more preferably 0.20 mass% or less, based on the total mass of the deposited metal.

＜Zr _(Metal) :0.50 mass% or less

Zr is a strongly deoxidized component like Al, and if Zr is excessively contained, zr is highly likely to remain as an inclusion in the deposited metal, and adversely affects toughness. Thus, zr _(Metal) The content of (2) is 0.50 mass% or less, preferably 0.45 mass% or less, based on the total mass of the deposited metal.

＜Ti _(Metal) :0.05 mass% or less

Ti is a strongly deoxidizing component like Al, and if it is excessively contained, it is highly likely that Ti remains as an inclusion in the deposited metal, and adversely affects toughness. Thus Ti is _(Metal) The content of (c) is 0.05 mass% or less, preferably 0.03 mass% or less, and more preferably 0.01 mass% or less, based on the total mass of the deposited metal.

＜Ca _(Metal) :0.50 mass% or less

Ca is a strongly deoxidized component similar to Al, and if Ca is excessively contained, ca is highly likely to remain as inclusions in the deposited metal, adversely affecting toughness. Thus, ca _(Metal) The content of (2) is 0.50 mass% or less, preferably 0.45 mass% or less, based on the total mass of the deposited metal.

＜Ni _(Metal) :3.00 mass% or less

Ni stabilizes the austenitic structure of the deposited metal, and is a component that improves toughness at low temperatures, and is a component that can adjust the amount of crystallization of the ferritic structure. However, if Ni is excessively contained in the deposited metal, the strength is excessively increased, and there is a possibility that the balance between strength and toughness may be lost. Thus Ni _(Metal) The content of (2) is 3.0 mass% or less, preferably 2.5 mass% or less, based on the total mass of the deposited metal.

＜B _(Metal) :0.0090 mass% or less

B is an element that reduces cracking resistance while preventing the toughness of the deposited metal from being reduced. Thus B _(Metal) The content of (2) is 0.0090 mass% or less, preferably 0.0050 mass% or less, based on the total mass of the deposited metal. In addition, B has a dropThe effect of the low brittleness fracture surface ratio is preferably 0.0010 mass% or more, more preferably 0.0020 mass% or more.

＜Ba _(Metal) :1.00 mass% or less

Ba is an element that contributes to deoxidization of the deposited metal and improves welding workability, but if Ba is excessively contained in the deposited metal, arc deflection occurs and there is a possibility that welding workability may be deteriorated. Thus, ba _(Metal) The content of (2) is 1.00 mass% or less, preferably 0.90 mass% or less.

＜Nb _(Metal) :0.001 mass% or less

Nb is a component that affects mechanical properties such as strength. In general, steel grades such as mild steel, high tensile steel, low temperature steel, etc. that are used in large quantities may contain Nb in the deposited metal in order to satisfy the required mechanical properties. In this case, nb _(Metal) The content of (2) is 0.001 mass% or less, preferably 0.0008 mass% or less, based on the total mass of the deposited metal.

＜Cu _(Metal) :0.1 mass% or less

Cu is an element contributing to improvement in strength and weather resistance of the weld metal. In general, a steel grade such as mild steel, high-tension steel, low-temperature steel, etc. is used in large quantities, and Cu may be contained in the deposited metal in order to satisfy the required strength and weather resistance. In this case, cu _(Metal) The content of (2) is 0.1 mass% or less, preferably 0.08 mass% or less, based on the total mass of the deposited metal.

＜V _(Metal) :0.001 mass% or less

V exerts an effect of improving the strength of the weld metal, and is an element that reduces toughness and crack resistance. Thus, V in the deposited metal _(Metal) The content of (2) is 0.001 mass% or less, preferably 0.0006 mass% or less, based on the total mass of the deposited metal.

＜W _(Metal) :0.1 mass% or less

W is a component that improves high-temperature strength and pitting corrosion resistance. Is generally used in a large amount in soft steel, high-tension steel, low-temperature steel, etcIn the steel grade, W may be contained in the deposited metal in order to satisfy the required mechanical properties. In this case, W _(Metal) The content of (2) is 0.1 mass% or less, preferably 0.08 mass% or less, based on the total mass of the deposited metal.

＜Ta _(Metal) :0.1 mass% or less

Ta is an element that affects mechanical properties such as strength. In general, a large number of steel grades such as mild steel, high-tension steel, and low-temperature steel are used, and Ta may be contained in the deposited metal in order to satisfy the required mechanical properties. In this case, ta _(Metal) The content of (2) is 0.1 mass% or less, preferably 0.08 mass% or less, based on the total mass of the deposited metal.

＜Sr _(Metal) :1.00 mass% or less

Sr contributes to improvement of deoxidizing action and welding workability of the weld metal, and it is found that Sr can be contained in the deposited metal because Sr is an element preferably contained in the flux. In this case, sr _(Metal) The content of (2) is 1.00 mass% or less, preferably 0.90 mass% or less, based on the total mass of the deposited metal.

＜O _(Metal) : 0.0250% by mass or less

O is solid-dissolved in the weld metal or exists as an oxide. If O is excessively contained, there is a high possibility that a large amount of oxide inclusions remain in the weld metal, which adversely affects toughness. Thus, O _(Metal) The content of (2) is 0.0250 mass% or less, preferably 0.0200 mass% or less, based on the total mass of the deposited metal.

＜N _(Metal) :0.0100 mass% or less

N is solid-dissolved in the weld metal or exists in the form of nitride. If N is excessively contained, the strength is excessively increased due to the solid solution strengthening, and there is a possibility that the balance between strength and toughness may be lost. Thus N _(Metal) The content of (2) is 0.0100 mass% or less, preferably 0.0050 mass% or less, based on the total mass of the deposited metal.

(balance: impurity)

In the present embodiment, the balance other than the above elements is preferably an impurity. The impurity means an unintentional addition, and examples of the element other than the above include Sn, co, sb, as. The total content of impurities in the deposited metal is preferably 0.010 mass% or less, more preferably 0.005 mass% or less.

The deposited metal of the present embodiment can be produced by gas shielded arc welding using, for example, the above [1. Alkaline flux-cored wire ].

[3. Welding method ]

The welding method according to the present embodiment is a method of performing gas shielded arc welding using the alkaline flux-cored wire described in [1 ] above.

Specifically, among various gas shielded arc welding methods, gas shielded arc welding is preferably performed using positive polarity with the electrode side being- (negative) and the base material side being + (positive). The type of gas used for welding is not particularly limited, and examples thereof include 100% by volume of Ar gas and 100% by volume of CO ₂ Gas, 100% by volume of O ₂ Gas, and also a mixed gas thereof, and the like. When Ar gas is used, a shielding gas containing 70% by volume or more of Ar is preferably used, and CO is used ₂ In the case of gas, CO is preferably used ₂ The amount of the shielding gas is 70% by volume or more, and more preferably 100% by volume of CO is used ₂ Gas (hereinafter, also referred to as "carbon dioxide"). In addition, ar gas and CO gas are used ₂ In the case of the mixed gas of the gases, 80% by volume of Ar gas and 20% by volume of CO are preferable ₂ A mixed gas of gases. The flow rate of the gas is not particularly limited, and may be, for example, about 15 to 30L/min.

The shape of the welding current waveform may be a straight line or a pulse shape. The term "straight line" as used herein means that there is no special waveform. The welding current range is not particularly limited, and for example, 200 to 300A in the case of flat welding, 150 to 250A in the case of vertical welding and horizontal welding, and the range of combination of these conditions can be used in the case of circumferential welding of a fixed pipe or the like. The arc voltage is not particularly limited, and may be 15 to 35V, for example. The welding speed is not particularly limited, and may be, for example, 10 to 50 cm/min. The protruding length of the wire is not particularly limited, and may be set to 10 to 30mm, for example. However, all welding conditions are not limited to the above-described range, and can be appropriately determined according to the application.

[4. Welded Joint ]

The welded joint of the present embodiment is manufactured by using the welding method described in the above [3. Welding method ]. In the welded joint according to the present embodiment, the portion of the deposited metal preferably has the composition described in [2 ] above.

Examples

The present invention will be described more specifically below by way of examples of the invention and comparative examples, but the present invention is not limited to these examples, and the present invention can be modified and practiced within the scope of the gist of the present invention, and these are included in the technical scope of the present invention. The welding conditions described herein are examples, and the present embodiment is not limited to the following welding conditions.

Using welding wires having various compositions shown in tables 1 to 4 below, deposited metals were produced under the welding conditions shown below, strength (TS) was measured by a tensile test, and pendulum impact absorption work (CVN) at-20 ℃ and-46 ℃ was measured by an impact test.

< welding Condition >)

Welding current: 210A

Arc voltage: 21V

Polarity: DCEN

Protective gas: 100% CO by volume ₂

The lamination method comprises the following steps: 7 layers 14 lanes

Line energy: 0.8 to 1.0kJ/mm

< measurement method >)

(tensile test)

From the obtained deposited metal, JIS Z3111 was extracted: 2005, A1, by a tensile test piece according to JIS Z3111: 2005, a tensile test of "tensile and impact test method of deposited metal" was performed to measure Tensile Strength (TS) and 0.2% yield strength (yield stress: PS) of the weld metal.

(impact test)

From the obtained deposited metal, JIS Z3111 was extracted: 2005 by a V-notch impact test piece of 2mm according to JIS Z3111: 2005, "tensile and impact test method of deposited metal", the work of absorption (CVN) of 3-point welded metal at-20 ℃ and-46 ℃ was measured, and the average value thereof was used as CVN (-46 ℃) and CVN (-20 ℃).

< evaluation method >)

Next, the balance between strength and toughness, and the brittle fracture surface ratio were evaluated. Specifically, values obtained by the following formulas (a) and (b) were calculated, and the balance between strength and toughness was evaluated.

Formula (a): CVN (-46 ℃ C.)/TS

Formula (b): CVN (-20 ℃ C.)/TS

The values obtained by the formulas (a) and (b) are closer to 1, and it can be determined that the balance between strength and toughness is better. Specifically, in the formula (a), if the ratio is 0.100 or more, the balance between strength and toughness is good, and if the ratio is 0.150 or more, the ratio is more excellent, and if the ratio is 0.180 or more, the ratio is judged to be good. In the formula (b), the balance between strength and toughness is good if it is 0.150 or more, more preferably 0.200 or more, and still more preferably 0.220 or more, and the quality is judged as being good or acceptable.

In addition, brittle fracture surface ratios at-20℃and-46℃were also evaluated. The brittle fracture surface ratio is the ratio of the area occupied by the region exhibiting the brittle fracture surface with respect to the predetermined cross-sectional area before the test, which is obtained by observing the fracture surface of the test piece after the pendulum impact test. The brittle fracture surface ratio was judged to be satisfactory at-20℃and-46℃and was excellent at 40% or less and at 30% or less. The composition of the deposited metal obtained is shown in tables 5 and 6 below, and the evaluation results are shown in tables 7 and 8 below. In tables 1, 3, 5 and 6 below, the term "-" indicates that the detection limit is not higher than the detection limit. In table 4, the symbol "-" indicates that the calculation was impossible. The balance of the welding wire composition shown in tables 1 and 3 below was O, N and the balance of the deposited metal composition shown in tables 5 and 6 below was Fe and the balance of the impurities.

In tables 2 and 4, the following formulas are represented by formulas (1) to (8).

Formula (1):

32.1×[Si]－40.6×[Mn]－20.1×[Ni]－19.7×[Mo]－172.6×[C]－408.2×[REM]－5824.4×[B]－38.4×[Cr]－9960×[P]+43793×[S]

formula (2):

33.9×[Si]－47.0×[Mn]－22.2×[Ni]－11.9×[Mo]－203.9×[C]－443.5×[REM]－4482.2×[B]－36.1×[Cr]－15281×[P]+47868×[S]

formula (3):

0.001×[Fe]－0.71×[Si]+0.08×[Mn]－0.08×[Al]+0.69×[Zr]+0.03×[Ni]+0.01×[Mo]+0.32×[C]+2.27×[REM]+9.57×[B]+0.11×[Cr]

formula (4):

0.003×[Fe]－0.35×[Si]+0.09×[Mn]－0.13×[Al]+0.22×[Zr]+0.02×[Ni]－0.02×[Mo]－0.11×[C]+1.17×[REM]+4.30×[B]+0.09×[Cr]

formula (5): [ B oxide ]/[ B ]

Formula (6): [ Cr ]/([ Cr ] + [ Mo ])

Formula (7): [ Mo ]/([ Cr ] + [ Mo ])

Formula (8): [ Al ]/([ Al ] + [ Mg ])

Wherein, [ REM ]]、[Fe]、[C]、[Si]、[Mn]、[P]、[S]、[Cr]、[Mo]、[Al]、[Zr]、[Ni]、[B]And [ Mg ]]REM is expressed in mass% relative to the total mass of the wire _(Wire) 、Fe _(Wire) 、C _(Wire) 、Si _(Wire) 、Mn _(Wire) 、P _(Wire) 、S _(Wire) 、Cr _(Wire) 、Mo _(Wire) 、Al _(Wire) 、Zr _(Wire) 、Ni _(Wire) 、B _(Wire) And Mg _(Wire) Is a value of the content of (2). In addition, [ B oxide ]]The value is a value representing a B conversion value of B oxide in the wire in mass% with respect to the total mass of the wire. In this example, only B was added in the form of an oxide. In other words, the amount of oxide in the welding wire of the present embodiment is B _(Wire) B of the value of (2) ₂ O ₃ And (5) converting the value.

[ Table 1 ]

[ Table 2 ]

[ Table 3 ]

[ Table 4 ]

[ Table 5 ]

[ Table 6 ]

[ Table 7 ]

[ Table 8 ]

As shown in tables 1 to 4, tables 7 and 8, in invention examples No.1 to 16, the components contained in the alkaline flux-cored wire and the values obtained by formulas (1) to (8) are within the ranges specified in the present invention, so that the burn-through property is improved, the welding can be performed in all the postures, and the weld metal excellent in the balance between the strength and the toughness can be obtained. In comparative examples 5 to 7, when the Zr content in the welding wire is 0.045 mass% or less, the balance between strength and toughness becomes excellent with an increase in the B content. In addition, when comparative examples nos. 5, 11 and 14 were conducted, if the Zr content in the wire was increased to more than 0.045 mass% in the state where the B content was 0.0046 to 0.0055 mass%, at least one of the formulas (a) and (B) showing the balance between strength and toughness was seen to be decreased with the increase in Zr content. That is, it is understood that the balance between strength and toughness decreases as the content of B and Zr is closer to the upper limit of the range defined in the present invention.

In particular, examples Nos. 9, 10, 12, 13, 15 and 16 have excellent brittle fracture surface ratio and balance between strength and toughness because the Zr content and B content in the welding wire are within the preferred ranges specified in the present invention.

On the other hand, in comparative examples 1 to 19, at least one of the REM content, the C content and the values obtained by the formulas (1) to (4) in the welding wire is out of the range defined in the present invention, and therefore at least one of the brittle fracture surface ratio and the balance between strength and toughness is poor.

As shown in tables 5 to 8, in invention examples nos. 1 to 16, the contents of the components contained in the deposited metal were within the ranges specified in the present invention, so that the deposited metal having an excellent balance between strength and toughness was obtained.

Thus, according to the alkaline flux-cored wire, the welding method, and the method for manufacturing a welded joint of the present invention, it is possible to perform full-position welding, and to obtain a deposited metal and a welded joint excellent in balance between strength and toughness.

Claims (15)

1. An alkaline flux-cored wire is characterized in that the flux-cored wire is an alkaline flux-cored wire containing strong deoxidizing elements, wherein,

the total amount of the strong deoxidizing elements is 1.50 mass% or more and 4.00 mass% or less relative to the total mass of the welding wire, and

Contains REM:0.030 mass% or more and 0.120 mass% or less, fe:85.0 mass% or more, and satisfies

C: 0.050% by mass or less,

Si:0.60 mass% or less,

Mn:2.00 mass% or less,

P:0.0150 mass% or less,

S:0.0150 mass% or less,

Cr:1.00 mass% or less,

Mo:1.00 mass% or less,

Al:3.00 mass% or less,

Mg:3.00 mass% or less,

Zr:3.000 mass% or less,

Ti:3.000 mass% or less,

Ca:3.00 mass% or less,

Ni:5.00 mass% or less,

B:0.0200 mass% or less,

Ba:4.00 mass% or less,

F: at most 2.00 mass% of the total mass,

a value calculated by the following formula (1): the temperature of the mixture is less than or equal to 48.0,

a value calculated by the following formula (2): the temperature of the mixture is less than or equal to 48.0,

a value calculated by the following formula (3): the number of the components is more than 0.09,

a value calculated by the following formula (4): the number of the components is more than 0.14,

formula (1):

32.1×[Si]－40.6×[Mn]－20.1×[Ni]－19.7×[Mo]－172.6×[C]－408.2×[REM]－5824.4×[B]－38.4×[Cr]－9960×[P]+43793×[S]

formula (2):

33.9×[Si]－47.0×[Mn]－22.2×[Ni]－11.9×[Mo]－203.9×[C]－443.5×[REM]－4482.2×[B]－36.1×[Cr]－15281×[P]+47868×[S]

formula (3):

0.001×[Fe]－0.71×[Si]+0.08×[Mn]－0.08×[Al]+0.69×[Zr]+0.03×[Ni]+0.01×[Mo]+0.32×[C]+2.27×[REM]+9.57×[B]+0.11×[Cr]

formula (4):

0.003×[Fe]－0.35×[Si]+0.09×[Mn]－0.13×[Al]+0.22×[Zr]+0.02×[Ni]－0.02×[Mo]－0.11×[C]+1.17×[REM]+4.30×[B]+0.09×[Cr]

wherein in the formulas (1) to (4), the contents of [ REM ], [ Fe ], [ C ], [ Si ], [ Mn ], [ P ], [ S ], [ Cr ], [ Mo ], [ Al ], [ Zr ], [ Ni ] and [ B ] are respectively represented by mass% relative to the total mass of the welding wire.

2. The alkaline flux-cored wire of claim 1, further comprising, relative to the total mass of the wire, a metal selected from the group consisting of Nb:0.50 mass% or less, cu:2.00 mass% or less, W:1.00 mass% or less, ta:1.00 mass% or less, V:1.00 mass% or less, sr:4.00 mass% or less and alkali metal elements in total: 3.00 mass% or less, the balance being O, N and impurities.

3. The alkaline flux-cored wire of claim 1, wherein the content of B is 0.0020 mass% or more and 0.0150 mass% or less relative to the total mass of the wire.

4. The alkaline flux-cored wire of claim 1, wherein the flux-cored wire comprises,

the content of B comprises the B conversion value of B oxide,

when the B conversion value of the B oxide with respect to the total mass of the wire is expressed as [ B oxide ] in mass%,

represented by formula (5): the value calculated by [ B oxide ]/[ B ] is 0.5 or more.

5. The alkaline flux-cored wire of claim 1, wherein the flux-cored wire comprises,

contains a metal selected from the group consisting of Ba:4.00 mass% or less, ca:3.00 mass% or less, and Sr:4.00 mass% or less of at least one selected from the group consisting of,

the flux contains BaF as a fluoride of Ba, ca and Sr ₂ 、CaF ₂ And SrF ₂ At least one of the group consisting of,

the Ba content includes the BaF ₂ Is used for the conversion of Ba to Ba,

the Ca content includes the CaF ₂ The Ca-converted value of (2),

the Sr content, including the SrF ₂ Is a value of (1) in terms of Sr,

the content of F comprises the BaF ₂ The CaF is ₂ And the SrF ₂ F converted value of (c).

6. The alkaline flux-cored wire of claim 5, wherein the F content is equal to the F conversion value of total fluoride contained in the flux.

7. The alkaline flux-cored wire of claim 1, wherein the content of oxides in the wire is 0.005 mass% or more and 0.100 mass% or less relative to the total mass of the wire.

8. The alkaline flux-cored wire of any one of claim 1 to 7,

the Cr content is 0.20 mass% or more and 0.90 mass% or less relative to the total mass of the welding wire, and,

the Mo content is 0.50 mass% or less relative to the total mass of the welding wire,

represented by formula (6): the calculated value of [ Cr ]/([ Cr ] + [ Mo ]) is more than 0.20.

9. The alkaline flux-cored wire of any one of claim 1 to 7,

the Cr content is 0.90 mass% or less relative to the total mass of the welding wire, and,

The Mo content is 0.10 mass% or more and 0.80 mass% or less relative to the total mass of the welding wire,

represented by formula (7): the calculated value of [ Mo ]/([ Cr ] + [ Mo ]) is more than 0.10.

10. The alkaline flux-cored wire of any one of claim 1 to 7,

the Al is contained as the strong deoxidizing element in an amount of 1.00 mass% or more and 2.50 mass% or less relative to the total mass of the wire,

the Mg content is 1.00 mass% or less,

when the content of Mg in the wire is expressed as Mg in mass% with respect to the total mass of the wire,

represented by formula (8): the calculated value of [ Al ]/([ Al ] + [ Mg ]) is not less than 0.5 and not more than 1.0.

11. The alkaline flux-cored wire of any one of claims 1 to 7, wherein REM comprises La and Ce.

12. A deposited metal, characterized by comprising, relative to the total mass of the deposited metal

C:0.020 to 0.100 mass% inclusive,

Si:0.05 to 0.50 mass% inclusive,

Mn:0.20 to 1.80 mass% inclusive,

Al:0.30 to 1.50 mass% inclusive,

Ce:0.002 to 0.010 mass%,

Fe:85.0 mass% or more,

And meet the following requirements

La:0.008 mass% or less,

P:0.0200 mass% or less,

S:0.0200 mass% or less,

Cr:1.00 mass% or less,

Mo:1.00 mass% or less,

Mg:0.50 mass% or less,

Zr:0.50 mass% or less,

Ti:0.05 mass% or less,

Ca:0.50 mass% or less,

Ni:3.00 mass% or less,

B:0.0090 mass% or less,

Ba:1.00 mass% or less,

Nb:0.001 mass% or less,

Cu:0.1 mass% or less,

V:0.001 mass% or less,

W:0.1 mass% or less,

Ta:0.1 mass% or less,

Sr:1.00 mass% or less,

Total of alkali metal elements: 0.05 mass% or less,

O:0.0250 mass% or less,

N:0.0100 mass% or less of the resin composition,

the balance being impurities.

13. An alkaline flux-cored wire, characterized in that the deposited metal of claim 12 is obtained.

14. A welding method characterized in that gas shielded arc welding is performed using the alkaline flux-cored wire of any one of claims 1 to 11 and 13.

15. A welded joint, characterized in that it is manufactured using the welding method according to claim 14.