KR20110031119A - Flux-cored wire for welding - Google Patents

Abstract

PURPOSE: A flux-contained wire for welding is provided to improve the outer shape of bead and prevent the lowering of welding quality. CONSTITUTION: A flux-contained wire for welding comprises silicon0.5-1.0%, manganese1.5-3.0%, aluminum 0.1-0.3%, magnesium 0.01-0.3%, titanium dioxide 1.0-4.0%, silicon dioxide 0.1-0.5%, zirconia 0.1-0.5%, magnesium oxide 0.3-0.7%, sodium and potassium 0.15-0.5%, and fluorine 0.02-0.10% based on the entire mass of the wire.

Description

Flux-containing wire for welding {FLUX-CORED WIRE FOR WELDING}

The present invention relates to a titania-based flux-containing wire suitably used for horizontal fillet welding of carbon steel by carbon dioxide gas or mixed gas arc welding, and in particular, a weld portion having good porosity resistance without degrading welding workability. It relates to the flux-containing wire for welding obtained.

Conventionally, welding using flux-containing wire has been evaluated in the market for its high efficiency and excellent welding workability, and has been actively used in various fields using thick steel plates such as ships, bridges, offshore structures and oil tanks. .

In particular, in the field of ships with high utilization of flux-containing wires, steel sheets used for structures such as ships under construction are coated with shop primers and wash primers for rust prevention. In welding these coated steel sheets, a flux-containing wire having porosity resistance, such as that disclosed in JP-A-10-286692, for example, is used. However, the coating thereof often does not have sufficient uniformity of the film thickness, and particularly in high-speed horizontal fillet welding with a welding speed of 50 cm / min or more, a cause of pore defects such as pits and blow holes occurs in the welded portion. have. This pore defect arises in the welding part welded using this wire, for example, when a flux containing wire is exposed to air | atmosphere for a long time, and a rust inevitably generate | occur | produces on the wire surface and the water content in a wire increased.

Since the pore defect which arises in a weld part reduces the mechanical performance of a weld joint part called tensile strength and toughness, for example, it becomes a target of welding correction, and reduces the drying efficiency of ships or the like. Therefore, in order to suppress the construction cost of a structure, it is desirable that the generation of pore defects be as small as possible.

As a technique for suppressing the occurrence of conventional pore defects, there is a method of reducing the amount of diffusible hydrogen in the weld metal by adding fluoride to the flux-containing wire, as disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 8-281476. .

Moreover, as a technique proposed by the inventors of the present invention for the purpose of suppressing pore defects, there are the following. In Japanese Patent Laid-Open No. 2000-42787 and Japanese Patent Laid-Open No. 2007-152410, the inventors of the present invention have disclosed that good porosity resistance can be obtained by defining the composition amounts of oxides such as TiO ₂ , ZrO _2, and SiO ₂ in a wire. Further, in Japanese Patent Laid-Open No. 2008-55509, the inventors of the present invention have proposed a technique for suppressing the occurrence of pore defects from the viewpoint of a welding construction method by increasing the melt pool.

Japanese Patent Laid-Open No. 10-286692 Japanese Patent Laid-Open No. 8-281476 Japanese Patent Publication No. 2000-42787 Japanese Patent Publication No. 2007-152410 Japanese Patent Publication No. 2008-55509

However, the above-described prior art has the following problems. Although the technique of Unexamined-Japanese-Patent No. 8-281476 adds the fluoride which becomes a fluorine source to a flux containing wire as a method of suppressing generation | occurrence | production of a pore defect, in general, fluorine in a wire is a substance which reduces hygroscopic resistance. Therefore, in the case where the wire is exposed to the atmosphere for a long time, for example, the moisture content in the wire increases due to rust inevitably occurring on the surface of the wire. Moreover, when the flux containing wire of the said prior art is used, the amount of generation | occurrence | production of a fume, a spatter, etc. may be large and welding workability may fall.

In addition, Japanese Patent Laid-Open No. 2000-42787 proposed by the inventors of the present application can sufficiently solve the problem of reducing fumes and spatters, but depending on the composition of the oxide in the wire, the viscosity of the slag is increased or the slag peelability is reduced. In some cases, even when the porosity resistance is improved, welding workability may decrease or the bead shape may slightly deteriorate.

In addition, in Japanese Patent Laid-Open No. 2007-152410, since a Zr source as a metal is added to the wire, good slag foreskinability in high-speed welding can be obtained, but slag depending on the composition of the oxide in the wire. The viscosity may increase or the slag peelability may decrease, and the welding workability may decrease or the bead shape may slightly deteriorate.

In addition, the technique of Unexamined-Japanese-Patent No. 2008-55509 is a welding method using a multielectrode, and does not target welding by a single electrode. Therefore, in the case of newly introducing equipment for multi-electrode welding as in the prior art, it is necessary to make additional equipment investment.

In addition to the above-mentioned problems, in the shipbuilding field, the paint management standards for ships under construction have become strict, and the demand for improvement of air resistance is further increased. That is, it is anticipated that the case where the welding using the conventional flux containing wire cannot satisfy | fill the newly severed coating control standard will be frequent. Therefore, it is anticipated that productivity will fall drastically from the frequent correction work after welding and being forced to enormous time and labor.

This invention is made | formed in view of such a problem, and an object of this invention is to provide the titania type welding flux containing wire which can obtain the weld part which has favorable porosity resistance, without degrading welding workability. .

The flux containing wire for titania-type welding which concerns on this invention is Si: 0.5-1.0 mass%, Mn: 1.5-3.0 mass%, Al: 0.1-0.3 mass%, Mg: 0.01-0.3 mass%, TiO ₂ : 1.0-4.0% by mass, SiO ₂ : 0.1-0.5% by mass, ZrO ₂ : 0.1-0.5% by mass, MgO: 0.3-0.7% by mass, and Na compound and / or K compound: Na and K conversion values, respectively The total amount of 0.02 to 0.10% by mass, the content of Al and Mg is 0.15 to 0.5% by mass per total mass of the wire, the total amount of fluorine is 0.02 to 0.10% by mass per total mass of the wire, At least a part contains synthetic fluorine mica in an amount of 5 to 30% by mass of fluorine, and the ratio of the amount of fluorine per mass of wire in the synthetic fluorine mica to the total amount of fluorine is 0.5 to 0.9.

Moreover, in the above-mentioned welding flux containing wire, it is preferable that the said synthetic fluorine mica contains 0.005-0.100 mass% of moisture per total mass of synthetic fluorine mica.

The welding flux-containing wire of the present invention appropriately defines each composition in the wire, and contains synthetic fluorine mica as at least a part of the fluorine source. In addition to specifying the amount of fluorine in the synthetic fluorine mica in an appropriate range, the fluorine is contained at an appropriate ratio with respect to the total amount of fluorine. Thereby, the weld part which has favorable porosity resistance is obtained, without degrading welding workability, and can maintain a bead shape and a bead external appearance also favorably.

(A)-(d) is a figure which shows an example of a flux containing wire.

The inventors of the present invention conducted various experiments to improve the moisture resistance of the flux-containing wire for welding, thereby improving the porosity resistance of the welded portion. When synthetic fluorine mica is added as at least a part of the fluorine source in the wire, even when fluorine which lowers the hygroscopic resistance as in the prior art is added, the structure unique to the synthetic fluorine mica in which the fluorine atoms are included in the layered crystal structure is utilized. It was found that the non-swelling and hygroscopic properties were obtained. That is, the inventors of the present application add synthetic mica mica as part of the fluorine source added for improving porosity resistance, and if the amount of fluorine in the synthetic fluorine mica is defined within an appropriate range for the total amount of fluorine, other fluorine sources ( For example, the balance between K ₂ SiF ₆ , NaAlF ₆ , NaF, etc.) can be used to make use of the properties of non-swelling and hygroscopicity of synthetic fluorine mica without deteriorating welding workability, bead shape, and bead appearance. In the flux-containing wire, it was found that the moisture absorption resistance could be effectively improved, whereby a welded portion having good porosity resistance was obtained.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely. FIG.1 (a)-(d) is a figure which shows an example of a flux containing wire. For example, as shown in Figs. 1A to 1D, the flux-containing wire 1 is filled with the flux 1b in the shell 1a, and the outer diameter is, for example, 0.9 to 2.0 mm. In the flux-containing wire for welding of the present invention, the filling rate of the flux 1b in the wire 1 is, for example, 10 to 25 mass% per total mass of the wire 1. In addition, in this invention, the filling rate of the flux 1b in the wire 1 can be set to arbitrary values as long as it satisfy | fills each component in the wire 1 and the scope of this invention. However, when considering the freshness of the wire 1 and the welding workability at the time of welding, etc., it is preferable that the filling rate of the flux 1b in the wire 1 is 10-25 mass%.

The flux-containing wire 1 for welding of this invention is Si: 0.5-1.0 mass%, Mn: 1.5-3.0 mass%, Al: 0.1-0.3 mass%, Mg: 0.01-0.3 per total mass of the wire 1 % By mass, TiO ₂ : 1.0 to 4.0% by mass, SiO ₂ : 0.1 to 0.5% by mass, ZrO ₂ : 0.1 to 0.5% by mass, MgO: 0.3 to 0.7% by mass, Na compound and / or K compound: Na and K, respectively It contains 0.02-0.10 mass% in conversion value total amount, and content of Al and Mg is 0.15-0.5 mass% per total mass of a wire in total amount. In addition, the total amount of fluorine in the wire 1 is 0.02-0.10 mass% per total mass of the wire 1.

The wire 1 contains synthetic fluorine mica as at least part of the fluorine source. The amount of fluorine in the synthetic fluorine mica is 5 to 30% by mass per total mass of the synthetic fluorine mica, and the ratio of the amount of fluorine per mass of the total wire in the synthetic fluorine mica to the total amount of fluorine in the wire 1 is 0.5 to 0.9. to be. Moreover, it is preferable that synthetic fluorine mica contains 0.005-0.100 mass% of water per total mass of synthetic fluorine mica.

Thus, the welding flux containing wire 1 of this invention contains synthetic fluorine mica as at least one part of a fluorine source. Therefore, the non-swelling property and the hygroscopic property of the synthetic fluorine mica can be obtained from the flux-containing wire 1.

In addition, after the amount of fluorine in the synthetic fluorine mica is defined in an appropriate range, it is contained at an appropriate ratio with respect to the total amount of fluorine. Thereby, when welding using the welding flux containing wire 1 of this invention, the weld part which has favorable porosity resistance is obtained, without degrading welding workability, and can maintain a bead shape and a bead appearance also favorable. have.

Hereinafter, the reason for numerical limitation in the composition of the welding flux containing wire of this invention is demonstrated.

"Si: 0.5-1.0 mass% per total mass of wire"

Si acts as a deoxidizer and is a component for adjusting the strength of the weld metal. When content of Si is less than 0.5 mass% per total mass of a wire, the toughness of a weld metal part will fall by deoxidation shortage, and also bead shape will deteriorate. On the other hand, when content of Si exceeds 1.0 mass% per total mass of a wire, while the intensity | strength of a weld metal will become excessive, toughness will fall. Therefore, in this invention, content of Si is prescribed | regulated to 0.5-1.0 mass% per total mass of a wire.

"Mn: 1.5-3.0 mass% per total mass of wire"

Mn acts as a deoxidizer similarly to Si and is a component for adjusting the strength of the weld metal. When content of Mn is less than 1.5 mass% per total mass of a wire, the intensity | strength of a weld part will fall by lack of deoxidation, and bead shape will also deteriorate. On the other hand, when content of Mn exceeds 3.0 mass% per total mass of a wire, the strength of a weld metal will become high too much and the toughness of a weld part will fall. Therefore, in this invention, content of Mn is prescribed | regulated to 1.5-3.0 mass% per total mass of a wire.

"Al: 0.1-0.3 mass% per total mass of wire"

Al acts as a deoxidizer, but in gas arc welding is added for the purpose of adjusting the concentration of the arc and the fluidity of the molten metal. If content of Al is less than 0.1 mass% per total mass of a wire, the concentration of arc will fall and welding workability will fall. On the other hand, when the content of Al exceeds 0.3% by mass per total mass of the wire, the solidification rate of the molten slag is increased, solidification unevenness occurs, and the bead shape deteriorates. In addition, the excessive deoxidation causes the strength of the weld metal to be excessive, and the toughness of the weld portion is lowered. Therefore, in this invention, content of Al is prescribed | regulated to 0.1-0.3 mass% per total mass of a wire.

"Mg: 0.01-0.3 mass% per total mass of wire"

Mg, like Si, Mn and Al, acts as a deoxidizer. It is also added to adjust the concentration of the arc and the flow of molten metal and slag. If the content of Mg is less than 0.01% by mass of the total mass of the wire, the concentration of the arc decreases and the weldability decreases. On the other hand, when content of Mg exceeds 0.3 mass% per total mass of a wire, the fluidity | liquidity of slag will fall and bead shape will deteriorate. Therefore, in this invention, content of Mg is prescribed | regulated to 0.01-0.3 mass% per total mass of a wire.

"Al and Mg: 0.15-0.5 mass% per total mass of a wire by total amount"

Al and Mg act as deoxidizers as described above, but in the present invention, each is added so as to be 0.15 to 0.5% by mass in total, while satisfying the aforementioned composition range. If content of Al and Mg is less than 0.15 mass% in the total amount per mass of a wire, the toughness of a weld part will fall by deoxidation shortage. On the other hand, when content of Al and Mg exceeds 0.5 mass% by the total amount per mass of wire, the generation amount of spatter will increase by deoxidation excess, and welding workability will fall. Therefore, in this invention, content of Al and Mg is prescribed | regulated as 0.15-0.5 mass% in total amount per total mass of a wire.

"TiO ₂ : 1.0-4.0 mass% per total mass of wire"

TiO ₂ acts as a slag former. When the content of TiO ₂ is less than 1.0 mass% per the total mass of the wire, the slag and the slag removability wrapping property is lowered, and at the same time the welding workability deteriorates to decrease the bead shape and the bead appearance. On the other hand, when the content of TiO ₂ exceeds 4.0% by mass per the total mass of the wire, the amount of generated slag is excessive, the porous bet is lowered.

Therefore, in the present invention, it defines the content of TiO ₂ in 1.0 to 4.0 mass% per the total mass of the wire.

"SiO ₂ : 0.1 to 0.5 mass% per total mass of wire"

SiO ₂ acts as a slag former. When the content of SiO ₂ is less than O.1% by weight per the total mass of the wire, the slag fluidity is reduced, the bet-porous decreases. On the other hand, when the content of SiO ₂ and if it exceeds 0.5 mass% per the total mass of the wire, the welding workability by increasing the amount of generated spatters is lowered. Accordingly, the present invention specifies the content of SiO ₂ in total 0.1 to 0.5 mass% per mass of the wire.

`` ZrO ₂ : 0.1 to 0.5 mass% per total mass of wire ''

ZrO ₂ has the effect of improving the bead shape by increasing the solidification point of the slag to increase the viscosity. When the content of ZrO ₂ is less than O.1% by weight per the total mass of the wire, the slag removability is deteriorated and together, thereby deteriorating the bead shape and the bead appearance. On the other hand, when the content of ZrO ₂ exceeds 0.5 mass% per the total mass of a wire, welding operability is lowered to increase the amount of generated spatters. Therefore, in the present invention, it defines the content of ZrO ₂ to O.1 to 0.5 mass% per the total mass of the wire.

"MgO: 0.3-0.7 mass% per total mass of wire"

MgO, like ZrO ₂ , has an effect of improving the shape of beads by increasing the solidification point of slag and increasing the viscosity. When content of MgO is less than 0.3 mass% per total mass of a wire, while the peelability of slag falls, bead shape and bead appearance deteriorate. On the other hand, when content of MgO exceeds 0.7 mass% per total mass of a wire, the generation amount of spatter will increase and welding workability will fall. Therefore, in this invention, content of Mg0 is prescribed | regulated as 0.3-0.7 mass% per total mass of a wire.

"Na compound and K compound: 0.02-0.10 mass% by total amount of Na and K conversion value, respectively, per total mass of a wire"

In the present invention, the flux-containing wire for welding contains one or both of the Na compound and the K compound in an amount of 0.02 to 0.10 mass%, respectively, in the total amount of Na and K converted values per total mass of the wire. When the total amount of the Na compound and the K compound is less than 0.02% by mass per total mass of the wire, the amount of spatter generated increases and welding workability deteriorates. On the other hand, when the total amount of the Na compound and the K compound exceeds 0.1% by mass per total mass of the wire, the hygroscopic resistance is lowered, and as a result, the porosity resistance is lowered. Therefore, in this invention, content of Na compound and K compound is prescribed | regulated as 0.02-0.10 mass% in total Na and K conversion value total amount, respectively, per total mass of a wire.

`` Total fluorine content: 0.02 to 0.10 mass% per total mass of wire ''

Fluorine is an important component for effectively obtaining the effect of improving the porosity. That is, although the flux containing wire contains fluorine is indispensable for the improvement of porosity resistance when welding a coated steel sheet, the moisture absorption resistance of a wire falls by adding a lot of fluorine. However, in the present invention, the hygroscopic resistance is improved by adding synthetic fluorine mica as at least a part of the fluorine source. Therefore, when synthetic fluorine mica is added to the flux-containing wire to increase the amount of fluorine, hygroscopicity can be improved while maintaining porosity resistance. If the total amount of fluorine is less than 0.02% by mass per total mass of the wire, the effect of improving porosity cannot be sufficiently obtained. On the other hand, when the total amount of fluorine exceeds 0.10% by mass per total mass of the wire, the amount of spatter generated increases, the welding workability decreases, and the porosity resistance also decreases. Therefore, in this invention, the total amount of fluorine is prescribed | regulated as 0.02-0.10 mass% per total mass of a wire.

"The amount of fluorine in synthetic fluorine mica: 5-30 mass% per total mass of synthetic fluorine mica"

As described above, in the case of welding the coated steel sheet, it is necessary for the flux-containing wire to contain fluorine in order to improve porosity resistance. In the present invention, as described above, by using synthetic fluorine mica as the fluorine source in the flux-containing wire requiring the fluorine content, hygroscopic resistance is improved. That is, since fluorine in the synthetic fluorine mica is contained in the layered crystal structure of the synthetic fluorine mica, contact with water existing outside the crystal structure can be suppressed to a minimum, so that characteristics of non-swelling and hygroscopicity can be obtained. have. For this reason, synthetic fluorine mica containing 5 mass% or more of fluorine is used. If the amount of fluorine in the synthetic fluorine mica is less than 5% by mass, the improvement of hygroscopic resistance cannot be sufficiently obtained. On the other hand, when the amount of fluorine in the synthetic fluorine mica increases, the ratio of the amount of fluorine in the synthetic fluorine mica to the total amount of fluorine increases, so that the amount of spatter generated during welding increases. In particular, when the amount of fluorine in the synthetic fluorine mica exceeds 30% by mass, the amount of spatter generated increases and welding workability deteriorates. Therefore, in this invention, the amount of fluorine in synthetic fluorine mica is prescribed | regulated to 5-30 mass%.

OH ions are usually present between the layers of mica. This OH ion can be substituted with fluorine ion. By adjusting this substitution rate, the amount of fluorine in synthetic fluorine mica can be adjusted. This substitution rate can be adjusted by adjusting the reaction temperature and time at the time of synthetic fluorine mica manufacture, for example.

`` The ratio of the amount of fluorine per mass of wire in the synthetic fluorine mica to the total amount of fluorine: 0.5 to 0.9 ''

In the present invention, in addition to the synthetic fluorine mica, NaAlF ₃ , K ₂ SiF ₆ , NaF and the like can be added. The addition of fluorine to the flux-containing wire lowers the hygroscopicity, but in the present invention, the amount of fluorine in the synthetic fluorine mica is optimized for the total amount of fluorine, thereby achieving balance with other fluorine sources. The moisture absorption resistance can be effectively improved without deteriorating the appearance, whereby a welded portion having good porosity resistance can be obtained. That is, in the present invention, the total fluorine content in the wire satisfies the above-mentioned range (0.02 to 0.10 mass% per total mass of the wire), and the ratio of the amount of fluorine is appropriate (5 to 30 mass% per total mass of the synthetic fluorine mica). By adding fluorine with the synthetic fluorine mica defined in the above), the fluorine in the synthetic fluorine mica can be balanced with other fluorine sources in an appropriate ratio (50 to 90%) relative to the total amount of fluorine. The moisture absorption resistance can be effectively improved, whereby a welded portion having good porosity resistance can be obtained. If the ratio of the amount of fluorine per mass of the wire in the synthetic fluorine mica to the total amount of fluorine is less than 0.5, sufficient hygroscopic resistance cannot be obtained. On the other hand, when the ratio of the amount of fluorine per mass of the wire in the synthetic fluorine mica to the total amount of fluorine exceeds 0.9, the amount of spatter generated increases and the welding workability deteriorates. Therefore, in the present invention, the ratio of the amount of fluorine per total mass of wire in the synthetic fluorine mica to the total amount of fluorine is defined as 0.5 to 0.9. The ratio of the amount of fluorine per wire total mass in the synthetic fluorine mica to the total amount of fluorine is preferably 0.7 to 0.8.

"Moisture in Synthetic Fluorine Mica: 0.005 to 0.100 Mass% per Total Mass of Synthetic Fluorine Mica"

The moisture in the synthetic fluorine mica can be increased or decreased by the length and the length of the firing time in the firing step (the firing temperature is, for example, 850 ° C.) of the flux-containing wire. However, the moisture in the synthetic fluorine mica is not made less than 0.005 mass% per total mass of the synthetic fluorine mica. In order to make water in synthetic fluorine mica less than 0.005 mass% per total mass of synthetic fluorine mica, it is necessary to make baking temperature high temperature, and the crystal structure of synthetic fluorine mica is destroyed by high temperature baking environment, and conversely moisture absorption resistance It will fall. On the other hand, when the moisture in the synthetic fluorine mica exceeds 0.100 mass% per total mass of the synthetic fluorine mica, the amount of diffusible hydrogen in the weld metal increases, and the porosity is easily deteriorated. Therefore, in this invention, it is preferable that the moisture in synthetic fluorine mica is 0.005-0.100 mass% per total mass of synthetic fluorine mica.

Example

EMBODIMENT OF THE INVENTION Hereinafter, the Example which shows the effect of the welding flux containing wire of this invention is demonstrated concretely compared with the comparative example. First, a flux having various compositions shown in Tables 3, 4, 5, and 6 was filled into a tubular outer shell (1.4 mm in diameter) made of mild steel having the composition shown in Table 1, and the present Example and Comparative Example Flux containing wire was produced. At this time, the filling rate of the flux was adjusted to be in the range of 13.0 to 15.0 mass% per total mass of the wire. On the other hand, in the wires shown in Tables 3 to 6, the balance was supplemented with an outer shell hoop, Fe alloys such as Fe-Mn, Fe-Si-Mn, Fe-Si, iron powder and the like. In addition, as the balance other than the fluorine source synthetic fluorine mica was used NaAlF ₃ and K ₂ SiF _6.

And gas arc welding was performed with respect to the base material which has a composition shown in Table 2 using the flux containing wire of each Example and a comparative example. At this time, the surface of the base material was coated (primer main component: Zn, primer thickness of 30 µm). On the other hand, it was used as the shielding gas 100% -CO _2.

Welding workability was evaluated about the gas arc welding using the flux containing wire of each Example and the comparative example, and the pore resistance of a weld part, the bead appearance, and the mechanical property of the weld part were evaluated.

(Welding workability evaluation)

Regarding the welding workability evaluation, the amount of spatter generated in the welded portion welded downward using the flux-containing wires in each of Examples and Comparative Examples was measured. On the other hand, as welding conditions, the welding current value was 290-320 A (DC-EP), the welding speed was 50 cm / min, and the number of repetitions was repeated twice. And it was determined that the amount of spatter generated was 1 g / min or less.

(Porosity evaluation)

Regarding the porosity evaluation, the other plate was placed on one plate using two plate-like base metals, and the horizontal fillet portion was horizontally welded using the flux-containing wires of the Examples and Comparative Examples. On the other hand, as welding conditions, the welding current value was 300-310A (DC-EP), the welding speed was 60 cm / min (automatic machine), the torch angle was 45 degrees, and the back and forth retreat angle was 0 degrees. In addition, the target angle length was 6 mm, and the welding length 600 mm section was welded twice in repeating times. Then, the number of occurrences of welding defects such as pits or gas bulbs generated in the welded portion on the side plate side is measured to be extremely good in the absence of defects, very good in the case of one defect, and in the case of two to three defects. Was good and the number of defects was four or more.

(Bead appearance evaluation)

About the bead appearance evaluation, the weld part welded by horizontal fillet welding was observed by the said porosity resistance evaluation, and the intimacy and the convex shape degree of the weld upper end were visually evaluated. At this time, the good intimacy of the weld top part and the thing with small convex shape were made into favorable, and it judged in 3 steps as good, a little inferior, and bad.

(Evaluation of Mechanical Properties of Welded Part)

About the mechanical property of a weld part, the impact test prescribed | regulated to JIS Z 3111 was performed and evaluated in the weld part welded down six-layer 12 passes using the flux containing wire of each Example and the comparative example. On the other hand, the welding current value was set to 290-320 A (DC-EP) and the interpass temperature of 150 +/- 10 degreeC. And it was made favorable that the impact value in atmospheric temperature 0 degreeC is 70J or more.

About the flux-containing wire of each Example and the comparative example, it is shown in Table 7 and 8 about the evaluation result of the weld workability, porosity resistance, bead shape, bead appearance, and the mechanical property of a weld part.

As shown in this Table 3 to Table 8, Examples 1 to 24, the composition in the flux-containing wire for welding satisfies the scope of the present invention, good welding workability, porosity resistance, bead shape and bead appearance, and The mechanical properties of the weld were also good.

In these Examples 1-24, Examples 4-7, 15, 18, and 19 are the ratio of the amount of fluorine per mass of wire in synthetic fluorine mica with respect to the total amount of fluorine is a preferable range of this invention. Therefore, porosity resistance was further improved as compared with the other examples.

Examples 21 to 24 are examples in which the amount of moisture in the synthetic fluorine mica satisfies the range of claim 2 of the present invention. Therefore, porosity resistance was further improved as compared with the other examples.

In the comparative example 1, total fluorine amount was less than the range of this invention, and porosity resistance fell. On the other hand, in the comparative example 2, total fluorine amount exceeded the range of this invention, and welding workability fell. In Comparative Example 3, the ratio of the amount of fluorine per total mass of the wire in the synthetic fluorine mica to the total amount of fluorine exceeded the range of the present invention, the amount of spatter generated increased, the welding workability decreased, and the appearance of beads deteriorated. In Comparative Example 4, the ratio of the amount of fluorine per total mass of wire in the synthetic fluorine mica to the total amount of fluorine was less than the scope of the present invention, and the effect of improving porosity was not obtained.

In Comparative Example 5, the amount of fluorine in the synthetic fluorine mica was less than the scope of the present invention, and the porosity was lowered. On the other hand, in the comparative example 6, the amount of fluorine in synthetic fluorine mica exceeded the range of this invention, and welding workability fell. In the comparative example 7, the total amount of Na conversion value of a Na compound and K conversion value of a K compound was less than the range of this invention, the generation amount of spatters increased and welding workability fell. In Comparative Example 8, the total amount of the Na conversion value of the Na compound and the K conversion value of the K compound exceeded the scope of the present invention, and the porosity resistance decreased due to the decrease in hygroscopic resistance. Similarly, Comparative Example 9 is the ratio of the amount of fluorine per total mass of wire in the synthetic fluorine mica to the total amount of fluorine in the preferred range of the present invention, but the total amount of the Na compound and the K compound exceeds the range of the present invention, so that the hygroscopic resistance is lowered. As a result, the porosity was lowered.

Comparative Example 10, to fall below the range of the invention the content of the TiO ₂ present, the slag removability is reduced, the bead shape was degraded. On the other hand, in Comparative Example 11, the content of TiO ₂ exceeded the range of the present invention, and the porosity resistance decreased. In Comparative Example 12, the content of SiO ₂ was less than the range of the present invention, and the porosity resistance was lowered due to the decrease in the fluidity of the slag. In comparison, Example 13 is in excess of the range of the invention the content of SiO ₂ present, the slag removability is reduced, the welding workability was degraded.

Comparative Example 14 is lower than the range of the invention the content of ZrO ₂ present, the slag removability was degraded is reduced, the bead shape and the bead appearance. On the other hand, Comparative Example 15 and the content of ZrO ₂ exceeds the range of the present invention, the welding workability was degraded. In the comparative example 16, content of MgO was less than the range of this invention, slag peelability fell like the comparative example 14, and the bead shape and the bead appearance deteriorated. In Comparative Example 17, the content of MgO exceeded the range of the present invention, and the welding workability was reduced in the same manner as in Comparative Example 15.

In the comparative example 18, content of Si was less than the range of this invention, the toughness of the weld part fell, and the bead shape also deteriorated. On the other hand, in Comparative Example 19, the content of Si exceeded the range of the present invention, and the appearance of beads deteriorated. In the comparative example 20, content of Mn was less than the scope of the present invention, and the appearance of the beads deteriorated. On the other hand, in the comparative example 21, content of Mn exceeded the range of this invention, the toughness of the weld part fell, and the appearance of the beads also deteriorated.

Comparative Example 22 did not contain Mg, and the total content of Al and Mg was less than the scope of the present invention, and the toughness of the weld portion was lowered. In Comparative Example 23, the total amount of Mg and Al and Mg content satisfies the scope of the present invention. However, the Al content is lower than the range of the present invention, and the concentration of arc is lowered, resulting in a decrease in welding workability. . Similarly, in Comparative Example 24, although the total amount of Al content and Al and Mg content satisfies the scope of the present invention, the Mg content is less than the scope of the present invention, and the concentration of arc is lowered, and the welding workability Degraded.

In the comparative example 25, content of Mg exceeded the range of this invention, the fluidity of slag fell, the bead shape deteriorated, and weldability also fell. In Comparative Example 26, although the contents of Al and Mg each satisfied the scope of the present invention, the total amount exceeded the scope of the present invention, the deoxidation excess was increased, the amount of spatter generated increased, and the weldability was deteriorated. In the comparative example 27, content of Al exceeded the range of this invention, the toughness of the weld part fell, and the appearance of the bead also deteriorated.

Claims (2)

As a flux containing wire for titania-based welding,
Per total mass of wire,
Si: 0.5-1.0 mass%,
Mn: 1.5 to 3.0 mass%,
Al: 0.1-0.3 mass%,
Mg: 0.01-0.3 mass%,
TiO ₂ : 1.0 to 4.0% by mass,
SiO ₂ : 0.1-0.5 mass%,
ZrO ₂ : 0.1-0.5 mass%,
MgO: 0.3-0.7 mass%, and
At least one of a Na compound and a K compound: each containing 0.02 to 0.10 mass% in Na and K equivalent values,
The content of Al and Mg is 0.15 to 0.5% by mass based on the total mass of the wire,
The total amount of fluorine is 0.02 to 0.10 mass% per total mass of the wire,
At least a part of the fluorine source contains 5 to 30% by mass of synthetic fluorine mica, and the welding flux-containing wire having a ratio of 0.5 to 0.9 of the amount of fluorine per total mass of wire in the synthetic fluorine mica to the total amount of fluorine. . The method of claim 1,
The said synthetic fluorine mica is a flux-containing wire for welding containing 0.005 to 0.100 mass% of water per total mass of synthetic fluorine mica.

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