JP2711077B2 - Flux-cored wire for gas shielded arc welding - 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 for gas shielded arc welding, and more particularly, to a vertical welding and an upward welding which can be applied to welding of mild steel, high tensile steel or low alloy steel. The present invention relates to a flux-cored wire for gas shielded arc welding having excellent workability.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher efficiency and de-skilling of welding work.
On the other hand, particularly in the case of downward welding and horizontal fillet welding, a welding robot or a line welder is introduced on the equipment side, and on the material side, as shown in the metal-based flux-cored wire, etc. Various welding materials exclusively for horizontal fillet welding have been developed and used, and technical development has been promoted to meet such requirements.

On the other hand, in the vertical or upward position, the use of flux-cored wires for welding in all positions has been increasing in recent years. However, such welding materials are not suitable for use in a vertical or upward position. However, the welding current needs to be considerably lower than in the case of the downward or horizontal attitude, which is insufficient from the viewpoint of high efficiency and de-skilling. For this reason, it has not yet been put to practical use. JP-A-57-190798 discloses a flux-cored wire for gas shielded arc welding, particularly considering a standing up posture and an upward posture. However, in some cases, defects in bead shape or the like due to dripping of molten metal or slag may occur, and practical difficulties have not been solved yet.

[0004] The present invention has been made in view of the above-described problems, and can perform welding with high efficiency in an upright posture and an upward posture, and can perform welding with a high welding current. An object of the present invention is to provide a flux-cored wire for gas shielded arc welding that does not cause dripping of molten metal and slag and failure of a bead shape.

[0005]

The flux-cored wire for gas-shielded arc welding according to the present invention is a flux-cored wire for gas-shielded arc welding comprising a mild steel or alloy steel sheath filled with a flux. , TiO ₂ : 3 to 10%, Al ₂ O ₃ : 0.3 to
2.0%, MgO: 0.01~1.0%, SiO 2:
_{0.3~1.0%, ZrO 2: 0.1~0.8%} , S
i: 0.5 to 1.5%, Mn: 1.0 to 3.0%, A
l: 0.1 to 0.5%, containing an alkali metal fluoride and / or an alkali metal oxide (however, a value converted into a monovalent oxide of an alkali metal): 0.05 to 0.7%, (A
l + Si + Al ₂ O ₃ + MgO) / (SiO ₂ × (alkali metal fluoride + oxide)) (however, alkali metal fluorides and oxides are values converted to alkali metal monovalent oxides) of 10 to 100. It is characterized by being.

Incidentally, Si, Mn and Al can be added not only from the flux but also from the outer shell.

[0007]

First, the inventors of the present application examined means for increasing the solidification point of slag by changing the composition of slag, which is generally performed, in order to prevent the molten metal from sagging, which causes defective bead shape. Therefore, the addition amount of Al ₂ O ₃ , MgO or ZrO ₂ , which is considered to be a high melting point slag, was increased.

[0008] However, when these are increased, the solidification temperature of the slag rises and the dripping of the molten metal decreases, but the conformity of the bead toe deteriorates conversely, and the bead shape is satisfactory. I couldn't do it.
Therefore, further studies were conducted, and other dripping prevention means were investigated. In addition to accelerating the solidification of the slag, the purpose is to make the molten metal itself a composition and characteristics that do not easily cause dripping. As a result of various studies, it was expected that increasing the viscosity of the molten metal at high temperatures would be effective, and an attempt was made to increase the viscosity by reducing the amount of oxygen in the molten metal to increase the viscosity. Therefore, various deoxidizing agents were added and their effects were verified. Usually, flux-cored wires include Mn, Si, Al, Ti, Mg as a deoxidizing agent.
Etc. are used. In the present invention, Al and Si are particularly used.
Is effective. Of course, deoxidizing agents other than Al and Si, for example, Mn and Ti and M which are stronger deoxidizing agents than them.
Although the amount of oxygen in the molten metal should be further reduced by g, etc., with respect to the dripping of the molten metal, Al and Si
Was essential.

The reason for this has not been fully elucidated,
Al, in addition to its effect as a deoxidizing agent, generates Al ₂ O ₃ which is extremely stable even at high temperatures during the melting phenomenon. It is considered that this is to increase the melting point of the slag. In addition, for Si, it is thought that SiO ₂ generated by deoxidation acts in the direction of lowering the solidification point in slag, but since it has good stability at high temperatures, the effect is large enough to disturb the balance of slag components. It is considered that the effect as a deoxidizing agent is rather large. It is also considered that other deoxidizing agents did not have a large effect because the oxides generated in the deoxidizing process reacted or decomposed in the molten slag and affected the balance of the slag components.

The present invention provides the effects of Al and Si described above,
Further, in order to prevent the slag from dripping and to prevent the bead shape from deteriorating, the relationship between Al ₂ O ₃ , MgO and ZrO ₂ and SiO ₂ , alkali metal fluorides and alkali metal oxides expressed by the following equation 1 is expressed by the following equation 1. Was adjusted to be 10 to 100.

[0011]

## EQU1 ## (Al + Si + Al ₂ O ₃ + MgO) / (SiO
₂ x (alkali metal fluoride + alkali metal oxide)) where alkali metal fluoride and oxide are alkali metal 1
It is a value converted to a valent oxide.

Next, the reasons for limiting the numerical values in the present invention will be described.

TiO ₂ : 3-10% TiO ₂ generally acts as a slag former and an arc stabilizer. If the content of TiO ₂ is less than 3%, a sufficient amount of slag to support the molten metal cannot be secured, and the molten metal will drool. On the other hand, if it exceeds 10%, the arc becomes unstable, and the occurrence of spatter increases. For this reason, TiO ₂ is set to 3 to 10%, and more preferably,
5.0-8.0%.

The raw materials for supplying TiO ₂ include:
Rutile and lecoxine.

Al ₂ O ₃ : 0.3 to 2.0% Al ₂ O ₃ has an effect of increasing the slag solidification point.
If it is less than 0.3%, the effect is not obtained, and if it exceeds 2.0%, the bead shape is deteriorated. For this reason, Al ₂ O ₃ contains 0.1.
The content is set to 3 to 2.0%, more preferably 0.5 to 1.
5%.

MgO: 0.01 to 1.0% MgO increases the slag freezing point and acts as an arc stabilizer. If the content of MgO is less than 0.01%, the effect is small, and if it exceeds 1.0%, the beat shape is deteriorated. For this reason, MgO is 0.01 to 1.0%, more preferably 0.1 to 0.7%.

The raw materials for supplying MgO include magnesia clinker, magnesite, olivine sand and the like.

SiO ₂ : 0.3 to 1.0% SiO ₂ acts as a slag forming agent and an arc stabilizer. If the content of Si ₂ O is less than 0.3%, the arc becomes unstable and the generation of spatter increases. If the content exceeds 1.0%, the slag becomes hard and the slag separation deteriorates. Therefore, S
iO ₂ is set to 0.3 to 1.0%, more preferably 0.4 to 0.7%.

ZrO ₂ : 0.1-0.8% ZrO ₂ increases the slag freezing point and acts as an arc stabilizer. If ZrO ₂ is less than 0.1%, the effect is not obtained, and if it exceeds 0.8%, the arc tends to be unstable, and the generation of spatters increases. Therefore, Zr
O ₂ is 0.1 to 0.8%, more preferably 0.
2 to 0.6%.

The raw materials for supplying ZrO ₂ include:
There is zircon sand and the like.

Si: 0.5-1.5% Si acts as a deoxidizing agent as described above. Si is 0.5
If it is less than 10%, deoxidation is insufficient, so that a weld defect such as a blow hole is generated in a welded portion, and molten metal is liable to drop. If the Si content exceeds 1.5%, the slag tends to sag and the toughness deteriorates. For this reason, the content of Si is 0.1.
The content is 5 to 1.5%, more preferably 0.6 to 1.
2%.

The raw material for supplying Si includes metallic Si, Fe-Si, Fe-Si-Mn and the like.

Mn: 1.0 to 3.0% Mn acts not only as a deoxidizing agent but also for improving the strength and toughness of the weld metal. Mn is 1.0%
If less than the above, deoxidation is insufficient, so that a welding defect such as a blow hole is generated in a welded portion, and strength and toughness are deteriorated.
If Mn exceeds 3.0%, the strength of the weld metal becomes too large, and hot cracking is likely to occur.

The material for supplying Mn includes metal Mn, Fe-Mn or Fe-Si-Mn.

Al: 0.1-0.5% Al acts as a deoxidizing agent and a slag forming agent as described above. If Al is less than 0.1%, dripping of the molten metal tends to occur, and if it exceeds 0.5%, the bead shape deteriorates. For this reason, Al is set to 0.1 to 0.5%, more preferably 0.2 to 0.4%.

The raw materials for supplying Al include metal Al, Fe-Al, Al-Mg, and the like.

Alkali metal fluoride and / or alkali
Metal oxide: converted to alkali metal oxide (monovalent oxide)
The alkali metal fluoride and / or alkali metal oxide having a calculated value of 0.05 to 0.7% acts as an arc stabilizer, but if it is too much, it acts to lower the viscosity of the slag, causing the slag to sag. Is more likely to occur. If it is less than 0.05%, there is no effect as an arc stabilizer, and if it exceeds 0.7%, slag tends to drop.

The raw materials for supplying the alkali metal fluoride include potassium silicate, sodium silicate,
Examples include sodium fluoride, thylium fluoride, and Na ₂ AlF ₆ . Raw materials for supplying alkali metal oxides include feldspar, Na ₂ CO ₃ , sodium silicate, potash glass,
Li ₂ Co _{3 and the} like. In the present invention, the alkali metal fluoride and the alkali metal oxide are used alone or in combination to form an alkali metal oxide (a monovalent oxide such as Na
₂ O ₃ , K ₂ O, Li ₂ O, etc.)
0.7% (in the case of composite addition, the total amount).

The value of the above equation (1 ) : 10 to 100 The above equation (1) affects the dripping of the molten metal and the slag and the shape of the bead toe. Al, Si, Al ₂
The ratio of the total amount of O ₃ and MgO to the alkali metal fluoride and alkali metal oxide (monovalent oxide equivalent) affects the dripping of the molten metal and the slag, and the larger the value, the dripping occurs. Hateful. However, at the same time, the shape of the bead toe tends to be convex, and the balance between the amount of SiO ₂ and the value of Equation 1 is important for the improvement. One of the features of the present invention resides in adjusting the value of Equation 1 to 10 to 100. If the value of the formula 1 is less than 10, the slag tends to drop, and if it exceeds 100, the bead shape deteriorates. More preferably, it is 10 to 50.

Incidentally, alloy elements such as Si, Mn and Ti can be added from the outer shell and / or the flux. Further, in order to improve the corrosion resistance, high-temperature strength, high-temperature corrosion resistance and the like of the welded portion, alloy components other than the above (Cr, Cu, N
i, Mo, V, Nb, Sb, etc.). Further, there is no limitation on the state of the wire surface and the shape of the flux filling in the wire cross section. The surface of the wire may be plated with Cu or the like, and the cross-sectional shape of the wire is preferably circular in order to stabilize the conductivity and the like, but the internal shape is not limited.

[0031]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples.

First, steel (JIS G 3141, SP
CC) A flux-filled wire having a wire diameter of 1.2 mm was prepared by filling the outer shell with a flux so that the ratio of the flux to the total weight of the wire was 20%. The chemical composition of this wire is shown in Table 1 below. The prepared flux-cored wire was welded under the welding conditions shown in Table 2 below, and the dripping of molten metal and slag, bead shape, arc stability, and the like were evaluated. The results of this evaluation are shown in Table 3 below.

[0033]

[Table 1] Note 1) Unit:% by weight based on the total weight of the wire (however, the value of Equation 1 is dimensionless) Note 2) The values of alkali metal fluorides and oxides are expressed in terms of the amount of alkali metal element and alkali metal oxide (monovalent oxidation Note 3) The balance represents Fe, C, P, S, etc.

[0034]

[0035]

[Table 2]

[0036]

[Table 3] Evaluation criteria: (excellent) ← ◎ ○ △ × → (poor) As shown in Table 3, in Comparative Example 1, Al ₂ O ₃ was out of the lower limit, and SiO ₂ and Al were out of the upper limit. As a result, slag dripping occurs, the bead shape is poor, and the slag peelability is poor.

In Comparative Example 2, since MgO and the alkali metal fluoride / oxide were out of the lower limit, and Mn was out of the upper limit, slag dripping occurred and spattering occurred frequently. The strength of the weld metal is too high.

In Comparative Example 3, since SiO ₂ was out of the lower limit, Si was out of the upper limit, and the value of Equation 1 was out of the upper limit, spattering occurred much and the bead shape was large. Is bad.

In Comparative Example 4, since TiO ₂ and Al were outside the lower limits, and Al ₂ O ₃ and MgO were outside the upper limits, the molten metal dripped off and the bead shape was poor. It is.

In Comparative Example 5, since TiO ₂ and ZrO ₂ were out of the upper limit, Si was out of the lower limit, and the value of Equation 1 was out of the lower limit, spattering occurred frequently, and molten metal and Slag dripping occurs.

In Comparative Example 6, since ZrO ₂ and Mn were out of the lower limits, and alkali metal fluorides and oxides were out of the upper limits, spattering occurred frequently and slag dripping occurred. Low strength and toughness of welds.

Comparative Examples 7 and 8 are examples in which the content of each chemical component itself satisfies the claims of the present invention, but only the value of Expression 1 is out of the range. In Comparative Example 7, since the value of Expression 1 is out of the lower limit, the slag drops. In Comparative Example 8, since the value of Expression 1 was outside the upper limit, the bead shape was poor.

On the other hand, since Examples 9 to 15 are examples of the present invention, no dripping of molten metal and slag occurs.
The bead shape was also good, and welding workability such as spatter generation and slag peelability was also good.

[0044]

As described above, according to the present invention, the welding operation can be performed with high efficiency by the upright posture and the upward posture, and the molten metal and the slag can be welded even when welding with a high welding current. Of the bead is prevented, and a defective bead shape is prevented.

Continuation of the front page (56) References JP-A-61-283493 (JP, A) JP-A-62-33093 (JP, A) JP-A-62-33094 (JP, A) JP-A-61-286089 (JP, A) , A) Tokiko Hei 4-53638 (JP, B2)

Claims (1)

(57) [Claims] 1. A flux cored wire for gas shielded arc welding comprising a mild steel or alloy steel sheath filled with a flux, wherein TiO ₂ : 3 to 1 per total weight of the wire.
_{0%, Al 2 O 3:} 0.3~2.0%, MgO: 0.01
_{~1.0%, SiO 2: 0.3~1.0%} , ZrO 2:
0.1-0.8%, Si: 0.5-1.5%, Mn:
1.0 to 3.0%, Al: 0.1 to 0.5%, alkali metal fluoride and / or alkali metal oxide (however, a value converted into a monovalent oxide of alkali metal): 0.05 ~
0.7%, (Al + Si + Al ₂ O ₃ + MgO)
/ (SiO ₂ × (alkali metal fluoride + oxide))
A flux-cored wire for gas shielded arc welding, wherein the value of the alkali metal fluoride and oxide is a value converted to an alkali metal monovalent oxide from 10 to 100.