JPS61154793A - Filler metal for tig welding - Google Patents

Abstract

PURPOSE:To improve the coverability with penetration beads, weldability, etc. in one-side TIG welding by incorporating a specific ratio each of TiO, metallic fluoride and SiO2 into a flux of a filler metal and specifying the content of metallic carbonate and slag forming agent. CONSTITUTION:4.5-8.5% TiO2, by the total weight of the wire, 0.20-1.75% metallic fluoride (in terms of F) and 0.2-2.5% SiO2 are incorporated into the flux component of the filler metal filled with the flux in the cavity of a metallic sheath. The content of the metallic carbonate is controlled to <=1.0% and the total content of the slag forming agent to 6-10% by the total weight of the filler metal. The defectless penetration beads are obtd. in TIG welding without using a back shielding gas in all welding attitudes if such filler metal is used. The slag removability after welding is good as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a filler material for TIG welding that can obtain a sound bead, especially a back bead, in any welding position without using pack shielding gas. It is something.

[Conventional technology]

When welding stainless steel, Ni alloys, etc. from one side, single-sided TIG welding is often employed, but when performing such one-sided TlGg welding, pack shield gas is generally used. However, considering the complexity of welding design and the difficulty of supplying shielding gas that is lazy when welding in narrow areas, it is necessary to provide a filler metal for TIG bath welding that can obtain a sound back bead without using pack shielding gas. For example, JP-A-55-1
No. 09595 has been proposed. The filler metal is a composite wire filled with flux in the cavity surrounded by a metal shell, and the back bead is covered by the produced slag to achieve insulation from the outside air, making it possible to obtain a sound back bead. can. By the way, single-sided TIG bath welding is often applied to circumferential bath welding of relatively small-diameter pipes, and since the pipe is generally fixed and welded, it is possible to use all-position welding. considered essential. However, the filler metal proposed above can only achieve its purpose in a downward position, and the bath welding workability in an upright position or an upward position is not necessarily satisfactory.

In other words, in the downward position, it is relatively easy to cover the back bead with slag, but in the upright or upward position, the back bead is insufficiently covered due to dripping of the slag or insufficient amount of slag. There was a tendency, and it was not possible to make the back bead sound. Moreover, depending on the composition, there is a drawback that the tungsten electrode is considerably worn out due to the generation of spatter or the scattering of slag.

[Problem that the invention seeks to solve]

The present invention has been made with attention to these circumstances, and is a bath additive for TIG welding that can obtain a sound back bead in all welding positions without using back shield gas, and has good welding workability. The aim is to provide materials.

[Means for solving problems]

The filler metal of the present invention that achieves the above object is a filler metal for TIG welding in which a cavity surrounded by a metal sheath is filled with flux, and the flux contains a Tie value of 4.5 based on the total weight of the wire. ~8.5% Metal fluoride 0.20~1.75 East fluorine amount conversion) Si
0.2 to 2.5%, the total amount of metal carbonates is 1.0% or less, and the total content of slag forming agents is 6 to 10% by weight of the total filler metal. The main point lies in the following points.

[Effect]

The present invention aims to obtain good back bead coverage, welding workability, slag removability after welding, etc. when performing single-sided TIG welding in all postures including vertical and upward postures. The amount of flux to be filled into the cavity surrounded by the metal shell is defined as follows. Each flux component will be explained in order below. It should be noted that all blending amounts refer to proportions to the total weight of the filler material.

Tie,: 4.5-8.5% TiO, is the best slag forming agent that can exhibit the above required characteristics, and as a flux component, 4.5-8.5% TiO,
It is necessary to contain 8.5%. If the content is less than 4.5%, the encapsulation of the back bead will not be sufficient. On the other hand, if the content exceeds 8.5-, the meltability of the &7 flux is poor, and only the outer metal is melted, leaving the central flux in an unmelted state protruding for a long time, resulting in a marked deterioration in welding workability. T
ie, the sources are rutile, titanium white, illuminite,
Examples include potassium titanate.

Metal fluoride: 0.20 to 1.75 ts (in terms of fluorine content) Provides appropriate fluidity to the molten slag and improves the encapsulation of the back bead, but if it is less than 0.20%, a sufficient effect cannot be obtained.On the other hand If the content exceeds 1.75, the slag becomes too fluid and welding workability deteriorates, and the amount of fluoric gas generated by thermal decomposition increases, resulting in a poor welding work environment. Examples of metal fluorides include CaF,
, MgF, , B@F,.

AIF, , LiF, NaF, Na, 41F
, etc.kf ratt6°SiO,: 0.2~2.
5% A slag forming agent that exhibits an excellent effect in stably enclosing the back bead, and imparts appropriate viscosity and surface tension to the slag, allowing it to stably form a good back bead and improve welding. It ensures the integrity of the metal and also provides good X-ray performance. However, no effect was observed below 0°2%.
On the other hand, if the content exceeds 2.5%, the slag releasability becomes poor and a great deal of effort is required for cleaning work after welding. Sources of such Sin include silica sand, wollastonite, feldspar, and the like.

Metal carbonate: i, os and below Metal carbonates have an arc stabilizing effect, but they thermally decompose during welding, causing spatter and scattering of molten slag. Furthermore, the generation of spatter causes the molten slag bath to shake, and the spatter and slag adhere to the tungsten electrode, thereby accelerating the wear of the tungsten electrode. As a result, welding workability is significantly hindered. As described above, metal carbonates have a large adverse effect on TIG welding, and it is desirable not to include them, but the permissible limit is 1.0 cm. As a carbonate, Caωs 1Mg■5. BaC
0,.

Examples include MnCO3, Li, GO3, Sr(:03).

Total content of slag forming agent = 6 to 10% The slag forming agent includes the above-mentioned components, metal oxides, metal fluorides, metal carbonates, composite compounds thereof, etc. other than the above-mentioned components. The total content of this mild slag-forming agent should be 6 to 10% in order to ensure the necessary amount of slag to protect the back bead from the atmosphere. If it is less than 6%, the back bead cannot be completely encapsulated in an upright or upward position. On the other hand, if it exceeds 10%, the amount of molten slag becomes excessive and the slag flows out to the front inside the groove. In this special upward position, the slag hangs down, making welding work extremely difficult.

Slag forming agents other than those mentioned above include ZrO, AI, 0
．． , CaO, BaO.

MgO, MnO, FeO, K,0, Na□0, B
i, 0. etc.

The basic structure of the present invention is as described above, and this not only gives the molten slag appropriate viscosity or fluidity, but also prevents the generation of spatter and scattering of the slag, and furthermore, the flux portion filled in the western part of the metal shell. Due to its good meltability, its meltability as a filler material is also improved.

As a means of further increasing the meltability of the filler material, it is recommended not only to adjust the flux composition as described above, but also to use a flux raw material whose melting point has been lowered by, for example, melting it and then solidifying it. The effect of improving meltability is further enhanced and excellent welding workability can be obtained.

Furthermore, Si in the filler metal contributes to the formation of the back bead, and particularly improves the slag envelopment at the end of the back bead. For this purpose, it is desirable to contain at least 0.5% of Si, but if it is contained in excess of 1.5%, it is undesirable because it increases the cracking resistance of the weld metal and the susceptibility to embrittlement during high-temperature use. A situation occurs. Therefore, the Si content is 0.
It is desirable to set it as 5-1.5%. Note that Si exhibits the same effect not only when added to the filling flux but also when added to the metal sheath, so the amount of Si contained in both the metal sheath and the flux may be within the above range.

Regarding the other components of the metal sheath, matching threads or non-matching metals may be appropriately selected depending on the type of metal to be welded.

[Example] A composite wire with a metal sheath having the composition shown in Table 1 and filled with the flux shown in Table 2 was used, and JIS-G-4
Pipe made of stainless steel plate or Inconel alloy plate specified in 305 (100mmφX6- and 300m+
TIG welding was performed in all positions of φX12-). The welding conditions were as follows. Welding results are evaluated for welding workability and slag encapsulation.

The results shown in Table 2 were evaluated based on the formation of the back bead, slag removability, X-ray transmission test results, etc.

(Welding conditions) Welding power source: DC drooping characteristics Polarity: DC positive welding voltage = 10 to 15V Welding current: 280 to 130A Conditions: 1 layer, 1 pass Welding electrode: Thorium-containing tungsten 3.2mm diameter shielding gas "", 15 I! /min Bevel shape: 1st
As shown in the figure (%) Blacks 1 and 2 had a low rio content, so the slag envelopment on the back bead was poor, and a satisfactory bead could not be formed. A3 is Tie.

In the comparative example where the slag content is excessive, the slag coverage is good and a back bead is formed, but the flux in the wire is difficult to melt and protrudes, resulting in poor welding workability and welding in an upward position. It was confirmed through an X-ray transmission test that unmelted wire was mixed into the metal. In case of No. 4, the slag encapsulation property deteriorated due to the lack of metal fluoride. In A5, the fluidity of the slag was excessively high due to the excessive amount of metal fluoride, and in the downward position, the molten slag flowed forward inside the groove, resulting in poor welding workability. In addition, in the vertical position and the upward position 1, the slag flows out and the slag coverage of the back bead deteriorates, making it impossible to form a satisfactory back bead. Since A6 lacked Sin, the slag envelopment was slightly poor and the back bead formation was also slightly poor. 7 is Sin,
In the comparative example in which there was an excessive amount of , very good results were obtained, but the removability of the slab was not satisfactory. /8.9 contained more than 1.0% of metal carbonate, so welding workability deteriorated. / and No. 10 had poor slag envelopment properties and poor back bead formation properties due to insufficient slag forming agent. Circles 11 to 13 have an excessive total content of slag forming agents, so that the front of the groove is filled with molten slag especially in the downward position, resulting in poor welding workability. Circles 414 to 21 all meet the requirements of the present invention. This is a satisfactory example and good results were obtained.

Next, a case will be described in which a flux that has been melted and then cooled is added as the flux.

Using a composite wire filled with the flux shown in Table 4 in the metal sheath shown by A in Table 1, JIS-G-4
Stainless steel plate pipe specified in 305 (100s
All-position TIG welding of Esl φ The chemical composition and melting point of the melt-treated flux are shown in Table 3, and the flux component composition indicates the composition of the flux including the melt-treated flux and the single flux.

Table 3 The melting points of all the molten fluxes shown in Table 3 are as follows: (TiO2: 1640°C, C@F: 1386°C)
It has a lower melting point and is easier to melt than single flux.

As shown in Table 4, samples Nos. 23 to 33 all contain 1.0% or more of melted flux as a flux component, and therefore have good flux meltability.

Extremely better welding workability was achieved compared to the case where no melt-treated flux was used.

〔Effect of the invention〕

The present invention is constructed as described above, and a sound back bead can be achieved by using the filler metal according to the present invention without using pack shielding gas in all welding positions (such as when performing TIG welding). Obtainable.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view showing the groove shape.

Claims (1)

[Claims] TIG in which a cavity surrounded by a metal shell is filled with flux
It is a filler metal for welding, and the flux contains TiO_2: 4.5 to 8.5% (the meaning of weight %, the same hereinafter) based on the total weight of the wire, metal fluoride: 0.20 to 1.75% ( fluorine amount conversion)
Contains SiO_2: 0.2 to 2.5%, the metal carbonate content is 1.0% or less, and the total content of slag forming agents is 6 to 10% based on the total weight of the filler metal. A filler metal for TIG welding characterized by the following.