JPS6057956B2 - Flux-cored wire for gas shield arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flux-cored wire for gas-shielded arc welding used for welding mild steel, high-strength steel, and low-alloy steel, and particularly for welding in a standing forward position or an upward position. The present invention also relates to flux-cored wires that can be manufactured with high efficiency and good performance.

In recent years, in order to perform welding work with high efficiency, welding has been performed semi-automatically or fully automatically using solid wire for carbon dioxide arc welding (solid wire). If this is done, the amount of spatter is large in the upright and upward postures, resulting in poor bead appearance and bead shape, and as a result, welding efficiency is reduced.

The reason for this decrease in welding efficiency is that good welding can only be performed in the low current short-circuit transition region (130 to 180 A for solid wire with a diameter of 1.2 mm) in the standing or upward position. be. Titania-based flux-cored wire has attracted attention as a welding material that provides good bead appearance, bead shape, and workability even when welding in all positions, but when welding using conventional titania-based flux-cored wire, Because it contains a large amount of titanium dioxide (melting point approximately 1855η), which has a much higher melting point than steel (approximately 153), it is easy to cause slag to stick to the bead surface. Heat input 30~50kj
If welding is carried out in a standing and advancing position with a high /Em, slag removal will be poor, and post-processing such as grinding will be required to remove the slag. If it remains, the appearance of the bead will deteriorate, and when multi-layer welding is performed, slag may be dragged in, causing defects such as blowholes and poor fusion.

The present invention was made to solve the above problems, and its purpose is to maintain the good workability of the conventional titania-based flux-cored wire, improve the slag releasability, and improve the overall The purpose is to perform position welding with high efficiency.

In order to achieve the above object, the present inventors believe that if a sulfide or oxide with a low melting point is added to the flux,
The study focused on the fact that when the molten slag and molten metal solidify, sulfides and oxides with low melting points are present at the interface between the weld metal and the slag, which is mainly made of titanium oxide, and can prevent the slag from seizing. I did it. The present invention was made as a result of the above studies, and its characteristics include 4.5 to 8.5% by weight of titanium oxide and 0.01 to 0.0% of vanadium oxide based on the total weight of the wire. and further contains a total of 0.01 to 0.15% by weight of one or more sulfides and oxides with a melting point of 500 to 1300'C, excluding vanadium oxide, or in addition to these, a wire is added to the flux. Contains 0.02 to 0.75% by weight of aluminum and/or aluminum oxide based on the total weight in terms of aluminum, and also contains 0.05 to 0.5% of metal fluoride in terms of the total weight of the wire in the flux. %, titanium dioxide is contained in an amount of 0.05 or less of the weight % of the titanium oxide, and calcium oxide is contained in an amount of 0.005 to 0.050 of the weight % of the total oxide, and the weight of the flux is based on the total weight of the wire. % to 10 to 3 heel weight%.

In order to investigate the effect of adding sulfides and oxides with low melting points to the flux on the peelability of slag, the flux shown in Table 2 was added to the metal sheath shown in Table 1 at 15% of the total weight of the wire. Steel grade JIS G3lO6SM-50 using a welding wire with a diameter of 1.2Tfr1ft filled with weight%
A1 plate thickness 127rn fillet joint and plate thickness 1 draw 500V
Test plates of grooved butt joints were welded under the welding conditions shown in Table 3, and the results are shown in Table 4.

Since sulfides and oxides with low melting points are generally considered to have low boiling points, Table 4 also shows the amount of fume generated in order to investigate the amount of fume generated by sulfides and oxides with low melting points. (Hereinafter, the percentage of each flux component and wire component refers to the weight percentage of the entire wire.) *1 The amount of fume generated is determined by collecting the entire amount of fume with a high volume air sampler and measuring its mass per unit time. Amount generated per hit (
Mg/min) was determined.

*2.

: Very good O: Good Δ: Slightly bad We investigated compounds with high boiling points in order to select low-melting sulfides and oxides that would not increase the amount generated.

Vanadium oxide has a high boiling point of 17 degrees Celsius or higher, so in order to investigate the effect of adding vanadium oxide to the flux on slag removability and the amount of fume generation, vanadium oxide was added to the metal sheath shown in Table 1. Diameter 1.2w1 filled with 15% by weight of the flux shown in Table 5 based on the total weight of the wire
Steel type JIS G3lO6SM-5 using welding wire of
0A) Fillet joint with plate thickness 12Tfgn and plate thickness 1gm!
l) Test plates of butt joints with a 50°V groove were welded under the welding conditions shown in Table 3, and the results are shown in Table 6. Table 6 shows 2wr of weld metal! NV Notsuchi Yarupi Impact Value (K
9f. m) 0°C is also shown. *1 The measurement of the amount of fume generated is the same as in Table 4. *2Wr of weld metal at 20℃
! Indicates the FtV notch shock value. The test pieces were collected at the center of the weld metal and the thickness of the plate.*3 The evaluation method for slag releasability is the same as Table 4, as shown in Table 6, adding vanadium oxide improves slag releasability. The amount generated is relatively small.

However, even if the amount of vanadium oxide added is increased, there is a limit to the improvement in slag releasability, and the impact value is also poor. Therefore, in order to further improve the slag releasability, the flux shown in Table 7, in which other low melting point compounds were added to the flux shown in Table 5, was added to the metal sheath shown in Table 1 at a rate of 15% based on the total weight of the wire. Diameter 1.2Wr filled by weight%! f
Steel type JIS G3lO6SM- using welding wire of l.
A test plate of a butt joint with a 50°V groove (50A plate thickness 1gw) was welded under the welding conditions shown in Table 3b, and the results were shown in Table 8.
Shown in the table.

*1 The measurement of the amount of fume generation is the same as in Table 4. *2 The measurement of the impact value is the same as Table 6. From Table 8, the start-up is improved by adding vanadium oxide and other low melting point compounds to the flux in combination. It shows very good slag removability even in postural butt welding.

The reason for limiting each component of the flux will be described below.

Titanium oxide 4.5-8.5% by weight Titanium oxide melting point (
In the case of titanium dioxide, the melting point of steel (approximately 15
39° C.), and titanium oxide increases the viscosity of the slag.

If the flux contains titanium oxide, even if welding is performed in a standing or upward position, the slag formed by melting the flux with arc heat is highly viscous and difficult to solidify. , it is possible to prevent the molten metal from dripping, it is possible to adjust the bead shape, and it is also possible to stabilize the arc. However, if titanium oxide is less than 4.5% by weight, the above-mentioned effects cannot be expected, and if it exceeds 8.5% by weight, the viscosity of the slag becomes too high, making it particularly difficult to weld in a downward position. In this case, the bead appearance and bead shape deteriorate, and furthermore, excessive reduced titanium and titanium oxide remain in the weld metal, resulting in a decrease in mechanical properties, particularly notch toughness. Note that titanium oxide includes titanium dioxide, titanium sesquioxide, titanium monoxide, titanium trioxide, etc., and titanium dioxide is the main type.

Vanadium oxide 0.01-0.0% vanadium oxide has a low melting point of 690°C and a boiling point of 1750°C.
Since the above is high, it is possible to improve the slag releasability without increasing the amount of fume generated, but if the weight % of the total weight of the wire is less than 0.01%, there is no effect of improving the slag releasability. If it exceeds 0.07%, excessive reduced vanadium or vanadium oxide will remain in the weld metal, resulting in a decrease in mechanical properties, especially notch toughness.

Total of one or more sulfides and oxides with a melting point of 500 to 1300°C excluding vanadium oxide: 0.01 to 0.15% by weight Addition of vanadium oxide alone cannot sufficiently improve slag releasability. However, if other low melting point sulfides and oxides are added, the slag removability can be dramatically improved.

If the melting point is less than 500°C, the yield as slag will be too low, and if it exceeds 1300'C, it will be too close to the melting point of steel and will not have the effect of improving the removability of slag. Melting point is 500-130
You must choose from those at 0°C.

If these sulfides and oxides are not added in a total amount of 0.01% or more based on the total weight of the wire, the slag removal effect cannot be fully exhibited, and if it exceeds 0.15%, the amount of fume generation increases. Not only will the amount increase, but there is also a risk that these sulfides, oxides, etc. will remain in excess in the weld metal and cause weld cracking. In addition, examples of sulfides and oxides with a melting point of 500 to 1300°C include tin sulfide, germanium sulfide, lead sulfide, bismuth sulfide, antimony sulfide, copper sulfide, iron sulfide, tin oxide,
These include germanium oxide, lead oxide, bismuth oxide, antimony oxide, and copper oxide.

Next, the ratio of flux to the total weight of the wire is 10 to 3.
If the weight is less than 1%, sufficient flux, that is, metal powder and slag forming agent cannot be contained, and if the weight is more than 3%, the mild steel plate used as the metal sheath of the wire will not be able to be contained. The thickness of the metal sheath must be reduced to expand the internal volume, and as the metal sheath becomes thinner, the wire becomes softer, resulting in poor conductivity and an unstable arc, making undercuts more likely to occur. This is because heat welding cannot be performed. Furthermore, ingredients other than the above-mentioned ingredients that can further enhance the uses and properties of the wire of the present invention will be explained.

Heat input 7KJ/C77 for vertical downward welding! If the heat input is higher than that, molten slag and molten metal are likely to drip down. To prevent this dripping, it is effective to add aluminum oxide, which has a high melting point of 2050°C, to the flux, but it is effective when converted to the amount of aluminum.
If the heel weight is less than %, the effect of the addition will not be sufficiently exerted, and 0.
If the content exceeds 75% by weight, the removability of the slag will be significantly reduced, so when welding in a vertical downward position, aluminum oxide and/or aluminum should be added in an amount of 0.02 to 0.75% by weight in terms of aluminum content. Should. Steel plates to be welded include rusted steel plates, steel plates coated with primer (wash primer, inorganic zinc, etc.), and when these steel plates are welded, bits are likely to occur.

This is caused by rust or primer when welding! It is thought that this is due to the hydrogen remaining in the deposited metal, and it has been found that increasing the basicity of the flux and adding metal fluoride are effective ways to remove this hydrogen. In order to increase the basicity of the flux, it is recommended to reduce the acidic oxide and add a basic oxide. If the weight percent ratio to the oxide is less than 0.005, the effect of improving bit resistance will not be sufficiently obtained, and if the metal fluoride is less than 0.05 weight percent, the effect of improving bit resistance will not be sufficient. I can't get it.

Note that calcium oxide and metal fluoride improve the fluidity of the slag, so the ratio of calcium oxide to total oxides by weight may exceed 0.050,
When the amount of metal fluoride exceeds 0.5%, the fluidity of the slag becomes excessive, which may lead to increased spatter and deterioration of bead shape. Note that calcium carbonate (CaCO3) can also be used instead of calcium oxide.

This is because calcium carbonate is dissociated by arc heat and decomposed into calcium oxide and carbon dioxide gas. However, when the amount of calcium carbonate increases, the partial pressure of carbon dioxide gas generation increases and the amount of spatter increases. Therefore, in order to reduce the influence of spatter generation, the amount of calcium carbonate added must be 0.15% by weight or less based on the total weight of the wire.
Therefore, when welding rusted steel plates or primer-coated steel plates, 0.05 to 0.0 of metal fluoride should be added to prevent bit formation.
The ratio of silicon dioxide to titanium oxide should be 0.05 or less, and the ratio of calcium oxide to total oxide should be 0.005 to 0.050.

Examples of the present invention are shown below.

Using a welding wire with a diameter of 1.27 m filled with the flux shown in Table 9 at 15% by weight based on the total weight of the wire, an inorganic zinc primer was applied to the metal sheath shown in Table 1 to a film thickness of 20.
μ coated steel type JIS G3lO6SM-50 plate thickness 12
TnIn test plates were welded under the welding conditions shown in No. 1, and the results are shown in Table 11.

Claims (1)

[Claims] 1. A flux-cored wire formed by filling a metal sheath with flux, in which the flux contains 4.5 to 8.5% by weight of titanium oxide and 0 vanadium oxide based on the total weight of the wire.
．． 0.01 to 0.07% by weight, and further contains a total of 0.01 to 0.15% by weight of one or more sulfides and oxides with a melting point of 500 to 1300°C, excluding vanadium oxide. The weight% of flux to the weight is 10
A flux-cored wire for gas-shielded arc welding, characterized in that the concentration is 30% by weight. 2. In a flux-cored wire formed by filling a metal sheath with flux, the flux contains 4.5 to 8.5% by weight of titanium oxide and 0 vanadium oxide based on the total weight of the wire.
．． 0.01 to 0.07% by weight, and a total of 0.01 to 0.15% by weight of one or more sulfides and oxides with a melting point of 500 to 1300°C excluding vanadium oxide, and aluminum and/or 0.0 in terms of aluminum oxide
A flux-cored wire for gas-shielded arc welding, characterized in that the flux-cored wire contains 2 to 0.75% by weight, and the flux content is 10 to 30% by weight based on the total weight of the wire. 3. In a flux-cored wire formed by filling a metal sheath with flux, the flux contains 4.5 to 8.5% by weight of titanium oxide and 0 vanadium oxide based on the total weight of the wire.
．． 0.01 to 0.07% by weight, and a total of 0.01 to 0.15% by weight of one or more sulfides and oxides with a melting point of 500 to 1300°C, excluding vanadium oxide, and metal fluorides. In addition to containing 0.05 to 0.50% by weight, silicon dioxide is contained in an amount of 0.05 or less of the weight% of titanium oxide, and calcium oxide is contained in an amount of 0.05% by weight or less of the total oxide.
1. A flux-cored wire for gas-shielded arc welding, characterized in that the flux-cored wire contains 0.005 to 0.050 of flux, and the weight percent of the flux is 10 to 30 percent by weight based on the total weight of the wire. 4. In a flux-cored wire formed by filling a metal sheath with flux, the flux contains 4.5 to 8.5% by weight of titanium oxide and 0.5% by weight of vanadium oxide based on the total weight of the wire.
01 to 0.07% by weight, and further contains 1 of sulfides and oxides with a melting point of 500 to 1300°C, excluding vanadium oxide.
0.01 to 0.15% by weight in total of species or more, 0.02 to 0 in terms of aluminum and/or aluminum oxide
．． 75% by weight, and 0.05 to 0.50% by weight of metal fluoride, and silicon dioxide by weight% of titanium oxide.
It contains calcium oxide in an amount of 0.05 to 0.050 of the total weight of the oxide, and contains 10 to 30 percent of the flux based on the total weight of the wire. A flux-cored wire for gas-shielded arc welding, characterized in that the weight percentage is as follows.