JP3293769B2 - Flux-cored wire for welding austenitic stainless steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux-cored wire used for welding austenitic stainless steel by gas shielded arc welding, and more particularly to a flux-cored wire for austenitic stainless steel having excellent slag removability. .

[0002]

2. Description of the Related Art Conventionally, in gas shielded arc welding of stainless steel, a flux-cored wire has been widely used. According to this welding method, a shielding effect by gas and a slag generated from a flux contained in an outer shell are obtained. With the shielding effect, the weld metal is protected, and the appearance and mechanical performance of the bead are ensured. Therefore, in the flux cored wire used for gas shielded arc welding, the arc is stable, the amount of spatter is small, the slag has appropriate fluidity, and the encapsulation of the weld bead is excellent. Therefore, it is required that the slag has good removability after cooling and solidification of the weld metal.

[0003] As a flux-cored wire for improving these characteristics, TiO ₂ : 4 to 12
%, SiO ₂ : 0.5 to 3.0% by weight, alkali metal fluoride: 0.5 to 1.5% by weight, Bi and Bi oxide: 0.002 to 0.02% by weight, and Ti: 0 .0
A wire to which 5 to 0.9% by weight is added has been proposed (Japanese Patent Laid-Open No. 1-215493). In this wire, Bi and Bi oxide are particularly added for the purpose of improving the slag removability.

On the other hand, it is known that Bi in the weld metal is a component that reduces the low-temperature toughness and the high-temperature ductility of the weld metal and also reduces the crack resistance. Therefore, a stainless steel flux-cored wire has been proposed in which the Bi content in the flux is regulated to less than 0.008% by weight to improve the high-temperature ductility of the weld metal (JP-A-Hei 7).
-276085). In addition, a stainless steel flux-cored wire has been disclosed in which the content of Bi and Pb in the flux is reduced to improve the low-temperature toughness, high-temperature ductility, and crack resistance of the weld metal (Japanese Patent Application Laid-Open No. 9-1997).
No. 66391). In these flux-cored wires, a decrease in the slag releasability caused by reducing the content of Bi and Bi compounds in the flux,
It is prevented by adjusting other flux components.

[0005]

However, even if stainless steel is welded using the above-mentioned conventional flux-cored wire, the effect of improving the slag removability cannot be sufficiently obtained. As described above, a flux-cored wire that can improve slag peelability and that satisfies all other required characteristics has not yet been developed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has an advantage that arc stability is good, spatter generation can be reduced, and excellent slag removability and bead shape can be obtained. An object of the present invention is to provide a flux-cored wire for welding austenitic stainless steel that can be formed.

[0007]

The flux-cored wire for welding austenitic stainless steel according to the present invention is a flux-cored wire for welding austenitic stainless steel, wherein the flux is filled in a shell made of stainless steel. Is the total weight of the wire,
TiO ₂ : 4.5 to 9.8% by weight, SiO ₂ : 0.5 to 1.8% by weight, ZrO ₂ : 1.4 to 3.0% by weight,
Metal fluoride (F conversion value): 0.1 to 1.5% by weight, Al ₂ O ₃ as an unavoidable impurity is 0.05% by weight or less, and Bi and Bi compounds (Bi conversion value) are 0%. .00
2% by weight or less, and the slag forming agent in the flux is 7.5 to 1 in total amount per total weight of the wire.
5.0 wt%, the TiO ₂ content is [TiO ₂ ] by weight%, and the SiO ₂ content is [Si
O ₂ ], when the ZrO ₂ content is expressed as [ZrO ₂ ] in weight%, the formula ΔX = [SiO ₂ ] / ([TiO ₂ ] + [S
iO ₂ ] + [ZrO ₂ ])｝ is 0.0
5 to 0.15, and the equation ΔY = [ZrO ₂ ] /
([TiO ₂ ] + [SiO ₂ ] + [ZrO ₂ ])}, wherein Y is 0.15 to 0.30.

It is preferable that the content of Al ₂ O ₃ is not more than 0.02% by weight based on the total weight of the wire.

In the present invention, slag forming agents include TiO ₂ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ , Fe
Metal oxides such as O, MnO, MgO, Na ₂ O, K ₂ O and Li ₂ O, LiF, NaF, CaF ₂ , MgF ₂ , K ₂
Metal fluorides such as ZrF ₆ and KBF ₄ and Li ₂ C
O ₃ , Na ₂ CO ₃ , CaCO ₃ , MgCO ₃ and MnCO ₃
And the like metal carbonates.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors conducted various experimental studies to obtain a flux-cored wire capable of improving slag removability without substantially containing Bi and Bi compounds in the flux. went. as a result,
Does not contain low melting point compounds such as Bi and Bi compounds,
In a flux-cored wire containing an O ₂ —ZrO ₂ —SiO ₂ slag forming agent, it has been found that by reducing the Al ₂ O ₃ content in the wire, the slag removability can be significantly improved. .

Hereinafter, the reason for limiting the composition of the flux contained in the outer sheath of the flux-cored wire for welding austenitic stainless steel according to the present invention will be described.

TiO ₂ : 4.5 to 9.8% by weight TiO ₂ is a component having an effect of forming a slag having good bead encapsulation properties and improving the bead shape.
If the content of TiO ₂ in the flux is less than 4.5% by weight based on the total weight of the wire, the effect cannot be sufficiently obtained. On the other hand, if TiO ₂ is excessively added to the flux in excess of 9.8% by weight based on the total weight of the wire, the slag removability deteriorates. Therefore, the TiO _{2 in} the flux
Is 4.5 to 9.8% by weight based on the total weight of the wire.

SiO ₂ : 0.5 to 1.8% by weight SiO ₂ forms a slag having good fluidity, and has an effect of improving the encapsulating property of the slag and the adaptability of the bead at the toe. It is. If the content of SiO ₂ in the flux is less than 0.5% by weight based on the total weight of the wire, the effect cannot be sufficiently obtained. On the other hand, if SiO ₂ is added to the flux excessively in excess of 1.8% by weight based on the total weight of the wire, the slag removability decreases. Therefore, the content of SiO ₂ in the flux is 0.5 to 1.8% by weight based on the total weight of the wire.

ZrO ₂ : 1.4 to 3.0 wt% By adding ZrO ₂ to the flux, the slag removability can be improved. Z in flux
If the rO ₂ is less than 1.4% by weight based on the total weight of the wire, the effect cannot be sufficiently obtained. On the other hand, Zr
If O ₂ is added to the flux in excess of 3.0% by weight based on the total weight of the wire, it causes slag scattering and deterioration of slag encapsulation. Therefore, ZrO ₂ in the flux is 1.4 to 3.0% by weight based on the total weight of the wire.
And

Metal fluoride (F conversion value): 0.1 to 1.
If the metal fluoride content in the 5% by weight flux is less than 0.1% by weight based on the total weight of the wire in terms of F, good slag fluidity, slag encapsulation and pit resistance cannot be obtained. On the other hand, if the metal fluoride content in the flux exceeds 1.5% by weight based on the total weight of the wire in terms of F, the melting point of the flux is remarkably reduced, and the arc stability is reduced. Therefore, the metal fluoride content in the flux is 0.1 to 1.5% by weight in terms of F based on the total weight of the wire.

The metal fluorides are LiF, NaF,
It refers to fluorides of metals or metal compounds such as CaF ₂ , MgF ₂ , K ₂ ZrF ₆ and KBF ₄ . In the present invention, any of these metal fluorides may be used, and the total amount of these metal fluorides in terms of F is 0.1 to 0.1% of the total weight of the wire.
The metal fluoride is added to the flux so as to be in the range of 1.5 to 1.5% by weight.

Al ₂ O ₃ : 0.05% by weight or less, preferably
In a flux-cored wire for austenitic stainless steel welding containing 0.02% by weight or less of low melting point compounds such as Bi and Bi compounds, the welding workability in a vertical position and the leg length of a weld bead in a horizontal position are described. Al ₂ O ₃ is added for the purpose of improvement. However, the present inventors do not contain low melting point compounds such as Bi and Bi compounds,
In a flux-cored wire containing a TiO ₂ —ZrO ₂ —SiO ₂ slag forming agent, the slag removability is significantly improved by reducing the content of Al ₂ O ₃ as an unavoidable impurity in the wire. I found that I could do it. If the content of Al ₂ O ₃ as an inevitable impurity in the flux exceeds 0.05% by weight based on the total weight of the wire, the effect of improving the slag removability cannot be obtained. Therefore, A as an inevitable impurity in the flux
l ₂ O ₃ is 0.05% by weight or less based on the total weight of the wire. Preferably, Al ₂ O ₃ in the flux is 0.1%.
It is at most 02% by weight, whereby the effect of further improving the slag removability can be obtained.

Bi and Bi compound (Bi conversion value):
002 wt% or less In the present invention, the flux composition for improving the slag releasability of a wire substantially free of Bi and a Bi compound is appropriately adjusted. That is, when Bi and the Bi compound in the flux exceed 0.002% by weight based on the total weight of the wire in terms of Bi, the low-temperature toughness, crack resistance, high-temperature ductility, and the like of the weld metal deteriorate. Therefore,
The content of Bi and the Bi compound in the flux is 0.002% by weight or less in terms of Bi based on the total weight of the wire.

6. Total amount of slag forming agent in flux:
If the amount of the slag forming agent in the flux (slag ratio) is less than 7.5% by weight per 5 to 15.0% by weight of the total wire, good slag encapsulation cannot be obtained. Rate 1
If the content exceeds 5.0% by weight, the amount of slag becomes excessive and slag is likely to be involved. Therefore, the total amount of the slag forming agent in the flux is 7.5 to 15.0% by weight based on the total weight of the wire. In the present invention, slag forming agents include TiO ₂ , SiO ₂ , ZrO
₂ , Al ₂ O ₃ , FeO, MnO, MgO, Na ₂ O, K ₂
Metal oxides such as O and Li ₂ O, LiF, NaF, Ca
Metal fluorides such as F ₂ , MgF ₂ , K ₂ ZrF ₆ and KBF ₄ , and Li ₂ CO ₃ , Na ₂ CO ₃ , CaCO ₃ , Mg
There are metal carbonates such as CO ₃ and MnCO ₃ .

[0020]Formula ｛X = [SiO ₂ ] / ([TiO ₂ ] +
X calculated by [SiO ₂ ] + [ZrO ₂ ])｝:
0.05 to 0.15 Formula ｛Y = [ZrO ₂ ] / ([TiO ₂ ] + [SiO ₂ ]
+ [ZrO ₂ ]) Y: 0.15 to
0.30 As mentioned above, SiO_TwoAnd ZrO_TwoIs excessive in the flux
, The slag removability of the wire is reduced. So
Here, the inventors of the present application report that SiO 2_TwoContent and ZrO_TwoContained
The slag removability of these contents is varied by varying the amount
The effect on was investigated. As a result, SiO_TwoAnd Zr
O_TwoThe degree of effect obtained by the addition of
Rather than just depending on the amount of compound added, the effect is
TiO_Two, SiO_TwoAnd ZrO_TwoIs correlated with the content ratio of
I found something. That is, the present invention
TiO_TwoContent, SiO_TwoContent and ZrO_TwoContent
In weight% of the total weight of the wire, [Ti
O_Two], [SiO_Two] And [ZrO_Two], The formula {X
= [SiO_Two] / ([TiO_Two] + [SiO_Two] + [Zr
O_Two])} And the formula {Y = [ZrO_Two] / ([TiO_Two]
+ [SiO_Two] + [ZrO_Two] And X calculated by｝
And Y.

If X calculated by the above formula is less than 0.05, the bead encapsulation property of the slag and the conformability of the bead are reduced. On the other hand, if X exceeds 0.15 or Y calculated by the above formula is less than 0.15, the slag removability decreases, and if Y exceeds 0.30, the bead coverage of the slag increases. The slag is scattered while the packaging property is reduced. Therefore, X is 0.05 to 0.15,
TiO ₂ , S such that Y is 0.15 to 0.30
Adjust the contents of iO ₂ and ZrO ₂ .

[0022]

EXAMPLES Examples of welding using the flux-cored wire for welding austenitic stainless steel according to the present invention will be specifically described below in comparison with comparative examples.

First, an outer cover made of stainless steel having the composition shown in Table 1 below was prepared, and the outer cover was filled with flux having various compositions to weld an austenitic stainless steel having a wire diameter of 1.2 mm. A flux-cored wire was produced. Next, using these wires, horizontal fillet welding was performed on SUS304L steel assembled in a T-shape under the welding conditions shown in Table 2 below, and welding workability was evaluated. The welding workability was evaluated by observing arc stability, spatter generation amount, bead encapsulation property of slag, slag peeling property, slag scattering resistance, bead conformability, bead shape and slag entrainment. . The flux composition of each wire is shown in Tables 3 to 8 below, and the evaluation results of the welding workability are shown in Tables 9 to 12 below.
Note that X and Y shown in Tables 5 and 8 below indicate the TiO ₂ content, SiO ₂ content, and ZrO ₂ content in the flux in terms of% by weight based on the total weight of the wire, respectively.
When [O ₂ ], [SiO ₂ ] and [ZrO ₂ ] are used, the equation ΔX = [SiO ₂ ] / ([TiO ₂ ] + [SiO ₂ ] +
[ZrO ₂ ])} and the formula {Y = [ZrO ₂ ] / ([Ti
O ₂ ] + [SiO ₂ ] + [ZrO ₂ ])}. In the welding workability evaluation result columns shown in Tables 9 to 12 below, ◎ indicates extremely excellent, and ○ indicates good. In addition, Δ indicates that there is some problem, and X indicates that it is not suitable for practical use.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

[0030]

[Table 7]

[0031]

[Table 8]

[0032]

[Table 9]

[0033]

[Table 10]

[0034]

[Table 11]

[0035]

[Table 12]

As shown in Tables 3 to 12 above, Example N
o. 1 to 8, X and Y calculated from the composition of the flux and the contents of TiO ₂ , SiO ₂ and ZrO _{2 in} the flux are appropriately regulated, so that arc stability, bead encapsulation of slag, Good slag peeling and slag scattering resistance, low spatter generation,
Both the bead shape and the bead conformability were improved.
In particular, in Example No. 1 in which the content of Al ₂ O ₃ was regulated to 0.02% by weight or less. In Nos. 1 and 4, the removability of the slag was further improved.

On the other hand, in Comparative Example No. 9 is T in flux
Since the iO ₂ content was less than the lower limit of the range of the present invention, the slag encapsulating property was poor, and a portion where the slag covering the weld bead was thin and a portion where the slag was thick were generated.
As a result, in the region covered with the thin slag, the slag removability was reduced due to the lack of the slag thickness. Comparative Example No. In No. 10, since the TiO ₂ content in the flux exceeded the upper limit of the range of the present invention, the amount of spatters increased, and the bead adaptability was poor. Comparative Example No. In No. 11, since the SiO ₂ content in the flux was less than the lower limit of the range of the present invention, the slag encapsulation property and the bead adaptability were reduced. Comparative Example No. 12, since the SiO ₂ content in the flux exceeds the upper limit of the range of the present invention,
The slag removability decreased.

Comparative Example No. 13 is ZrO in flux
_{2 Since the} content was less than the lower limit of the range of the present invention, the slag removability was reduced. Comparative Example No. No. 14 is because the ZrO ₂ content in the flux exceeds the upper limit of the range of the present invention,
The bead encapsulation property of the slag was poor, and the slag was scattered. Comparative Example No. 15 is Al in the flux
_{Since the 2} O ₃ content is contained beyond the scope of the present invention,
The slag peelability was poor, and a wire suitable for practical use could not be obtained. Comparative Example No. In No. 16, since the X calculated by the formula was less than the lower limit of the range of the present invention, the bead encapsulation property of the slag and the conformability of the bead were reduced. Comparative Example No. In No. 17, since the X calculated by the formula exceeded the upper limit of the range of the present invention, the slag removability was reduced.

Comparative Example No. In No. 18, since the Y calculated by the mathematical formula was less than the lower limit of the range of the present invention, the slag removability was reduced. Comparative Example No. 19 is Y calculated by an equation
, The bead encapsulation of the slag was reduced, and the slag was scattered. Comparative Example No. In Comparative Example No. 20, the metal fluoride (F conversion value) in the flux was less than the lower limit of the range of the present invention. 22
Since the total amount of the slag agent (slag ratio) was less than the lower limit of the range of the present invention, the bead encapsulation of the slag was poor. Comparative Example No. In No. 21, the arc stability decreased because the metal fluoride (F conversion value) in the flux exceeded the upper limit of the range of the present invention. Comparative Example No. In No. 23, slag entrainment occurred because the total amount of the slag agent (slag ratio) exceeded the upper limit of the range of the present invention.

[0040]

As described in detail above, according to the present invention,
Composition of flux and TiO ₂ , Si in flux
Since X and Y calculated from the contents of O ₂ and ZrO ₂ are appropriately regulated, without adding Bi and Bi compounds, the arc stability is good and the amount of spatter generation can be reduced. It is possible to obtain an austenitic stainless steel capable of obtaining excellent slag releasability and bead shape as well as being capable of obtaining excellent bead shape. In addition, Al in the flux
_When the content of ₂ O ₃ is strictly regulated, the slag removability can be further improved.

Continuation of the front page (56) References JP-A-9-94693 (JP, A) JP-A-9-94962 (JP, A) JP-A-9-122977 (JP, A) JP-A-9-122978 (JP) JP-A-10-230391 (JP, A) JP-A-59-127995 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 35/368 B23K 9/23

Claims (2)

(57) [Claims] 1. A flux cored wire for welding austenitic stainless steel comprising a stainless steel outer shell filled with a flux, wherein the flux is TiO ₂ : 4.5 to 9.8% by weight, based on the total weight of the wire.
SiO ₂ : 0.5 to 1.8% by weight, ZrO ₂ : 1.4 to 3.0% by weight, metal fluoride (F conversion value): 0.1 to 1.5% by weight, inevitable Al ₂ as impurity
O ₃ is 0.05% by weight or less, Bi and Bi compound (Bi
(Converted value) is regulated to 0.002% by weight or less, and the slag forming agent in the flux is 7.5 to 15.0% by weight based on the total weight of the wire.
iO ₂ content with wt% [TiO _2], the content of SiO ₂ in% by weight [SiO _2], wherein the ZrO ₂ content% by weight
When [ZrO ₂ ] is used, the mathematical formula ΔX = [SiO ₂ ] /
([TiO ₂ ] + [SiO ₂ ] + [ZrO ₂ ])} is 0.05 to 0.15, and the formula {Y
= [ZrO ₂ ] / ([TiO ₂ ] + [SiO ₂ ] + [Zr
O ₂ ])｝ is 0.15 to 0.30
A flux-cored wire for welding austenitic stainless steel, characterized in that: Wherein said Al ₂ O ₃ is the total wire weight per 0.
The flux-cored wire for welding austenitic stainless steel according to claim 1, wherein the content is not more than 02% by weight.