KR102612724B1 - Flux cored wire for horizontal electrogas arc welding - Google Patents

Abstract

A flux-filled wire for transverse electrogas arc welding is provided.
The flux-filled wire for transverse electrogas arc welding of the present invention is a flux-filled wire for transverse electrogas arc welding in which the metal shell is filled with flux, and in percent by weight, C: 0.011 to 0.032%, Si: 0.21 to 0.21%. 0.63%, Mn: 1.47~2.10%, Mg: 0.21~0.42%, Al: 0.21.0~0.42%, Na: 0.06~0.11%, K: 0.13~0.21%, TiO ₂ :1.89~2.31%, ZrO ₂ :0.63~1.05%, SiO ₂ :0.42~0.84%, Al ₂ O ₃ :0.11~0.32%, F:0.02~0.06%, the remainder includes iron (Fe) and inevitable impurities, and satisfies equation 1.

Description

Flux filled wire for transverse electrogas arc welding {FLUX CORED WIRE FOR HORIZONTAL ELECTROGAS ARC WELDING}

The present invention relates to a flux-filled wire for arc welding, and more specifically, to a flux-filled wire with excellent welding performance in transverse electrogas arc welding.

Welding is a method of combining two different materials by rearranging their atomic bonds by melting metal materials through an arc heat source at the joint. At this time, the metal material that can design molten metal at the same time as arc generation is a flux cored wire welding rod.

General flux-filled wire has a welding metal material that can be welded in all directions, and it solidifies to fill the gap between blocks in a shipyard to create welded metal. As the gap opens, the welding time using the flux-filled wire lasts longer and the welded structure manufacturing process becomes longer.

To solve this problem, a flux-charged wire using the Electro Gas Arc Welding (EGW) method is used. Electrogas arc welding is a highly efficient welding method that can weld metal plates of 10 mm or more in a single pass. It is an up-and-up automatic welding technique for large storage tanks and steel structures outside of shipbuilding. In addition to vertical up automatic welding, recently a lateral electrogas arc welding technique that moves left, right or horizontal has been developed and its use in the shipbuilding field is gradually expanding. However, flux-filled wire, a welding material used in existing vertical electrogas arc welding, has a high frequency of occurrence of weld metal defects in transverse electrogas arc welding, and is problematic in that weld metal flows down and deteriorates welding performance.

Korean Patent No. 10-2018-0095772

The purpose of the present invention is to provide a flux-filled wire that satisfies weld metal defects, mechanical performance (Charpy impact test, tensile test), and welding performance that can be optimized for the transverse electrogas arc welding technique.

The object of the present invention is not limited to the above-described content. Anyone skilled in the art to which the present invention pertains will have no difficulty in understanding the additional problems of the present invention from the overall content of the present invention specification.

One aspect of the present invention is,

In the flux-filled wire for transverse electrogas arc welding in which the metal shell is filled with flux, in percent by weight, C: 0.011 to 0.032%, Si: 0.21 to 0.63%, Mn: 1.47 to 2.10%, Mg: 0.21 to 0.21%. 0.42%, Al: 0.21.0~0.42%, Na: 0.06~0.11%, K: 0.13~0.21%, TiO ₂ :1.89~2.31%, ZrO ₂ :0.63~1.05%, SiO ₂ :0.42~0.84%, Al ₂ O ₃ :0.11~0.32%, F:0.02~0.06%, the remainder contains iron (Fe) and inevitable impurities, and relates to a flux-filled wire for transverse electrogas arc welding that satisfies the following relational equation 1.

[Relationship 1]

During transverse electrogas arc welding using the flux-filled wire of the present invention having the composition as described above, the resulting sound weld metal can have excellent strength and low-temperature impact toughness.

Figure 1 is a cross-sectional view of weld metal obtained when a flux-filled wire is used in transverse electrogas arc welding under the welding conditions in Table 3 in one embodiment of the present invention.
Figure 2 is a cross-sectional view of the lateral carriage weld metal in which the secondary welding is performed under the welding conditions in Table 4 after the lateral electrogas welding is completed in one embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the invention examples disclosed below, but can be implemented in various different forms. The following invention is intended to ensure that the disclosure of the present invention is complete and to clarify the scope of the invention to those skilled in the art. It is provided for complete information.

The present invention relates to a flux-filled wire for transverse electrogas arc welding in which the metal shell is filled with flux, and in percent by weight, C: 0.011 to 0.032%, Si: 0.21 to 0.63%, Mn: 1.47 to 2.10%, Mg:0.21~0.42%, Al:0.21.0~0.42%, Na:0.06~0.11%, K:0.13~0.21%, TiO ₂ :1.89~2.31%, ZrO ₂ :0.63~1.05%, SiO ₂ :0.42 ~0.84%, Al ₂ O ₃ :0.11~0.32%, F:0.02~0.06%, the remainder includes iron (Fe) and inevitable impurities, and is characterized by satisfying relational equation 1.

Hereinafter, the role of each component of the flux in the flux-filled wire of transverse electrogas arc welding of the present invention, such as the function and effect on the wire, will be explained in detail, and the technical significance of numerical limitations of each component will be explained in detail. . In the following description, [%] means weight%, and the content of each component means the component content that is the sum of the weight% of each component of the sheath and flux relative to the total weight of the wire.

Carbon (C): 0.011~0.032%

Among the wire components of the present invention, the carbon (C) content is controlled to 0.011 to 0.032%. Carbon is an impurity contained in the wire sheath and flux, and its role is the element that can most effectively secure the strength of the weld metal. If the carbon content is less than 0.011%, the structure of the weld metal softens and strength and impact toughness decrease. If it exceeds 0.032%, a lot of spatter is generated around the arc during welding, and welding performance deteriorates. In addition, cracks in the weld metal increase due to rapid cooling after welding, and the tensile strength of the weld metal increases, resulting in a decrease in low-temperature impact toughness.

Silicon (Si): 0.21~0.63%

Silicon (Si) contains 0.21 to 0.63% in conversion. Silicon is a deoxidizing agent, and if its content is less than 0.21%, the deoxidizing power is insufficient, which reduces low-temperature impact toughness, reduces slag fluidity during welding, and causes weld metal defects. On the other hand, if the content exceeds 0.63%, the strength of the weld metal increases and the open rate decreases. In addition, silicon that has not been transferred to the weld metal turns into an oxide of SiO ₂ and exists as slag on the top of the weld metal, making slag removal difficult. Metals used as silicon in the present invention include FeSi, SiMn, CaSi, K ₂ SiF ₆ , etc.

Manganese (Mn): 1.47~2.10%

Manganese (Mn) contains 1.47 to 2.10% in converted value. Manganese is an element that increases the strength of weld metal. If it is less than 1.47%, the yield strength or impact toughness decreases, and if it exceeds 2.10%, the strength is high and the low-temperature impact toughness decreases. Metals used as manganese in the present invention include FeMn, SiMn, and Mn.

Magnesium (Mg): 0.21~0.42%

Magnesium (Mg) contains 0.21 to 0.42% in conversion. Magnesium is a powerful deoxidizing agent that reduces the amount of oxygen in the weld metal and improves impact toughness. If the content is less than 0.21%, the effect on the low-temperature impact toughness of the weld metal is minimal, and if it exceeds 0.42%, the effect of magnesium is on the upper part of the weld metal. As the slag content increases, the slag and weld metal are cooled unevenly during welding, ultimately resulting in the problem that the slag formed on the top of the weld metal cannot be removed. Metals used as magnesium in the present invention include MgAl, Mg, MgCO ₃ , and MgF ₂ .

Aluminum (Al): 0.21~0.42%

Aluminum (Al) contains 0.21 to 0.42% in conversion. Aluminum is an ingredient that improves impact toughness by reducing nitrogen (N) introduced into the atmosphere during welding and the oxygen content of the weld metal, similar to the role of magnesium as a deoxidizer. If the aluminum content is less than 0.21%, the reduction effect of nitrogen or oxygen in the weld metal is minimal, so there is no effect of improving low-temperature impact toughness, and slag debris is generated due to poor removal of weld metal and slag in transverse electrogas arc welding. . On the other hand, if the content exceeds 0.42%, nucleation and growth of AlN or TiAlO ₃ occur inside the weld metal in lateral electrogas arc welding with high welding heat input, resulting in extreme cracks or low-temperature impact toughness of the weld metal. There is a downside to it. Metals used as aluminum in the present invention include MgAl, Al, Fe-Al, AlF _3, NaAlF ₆ , etc.

Sodium (Na): 0.06~0.11%

Sodium (Na) contains 0.06 to 0.11% in conversion. Sodium is an alkali metal in the periodic table of elements and plays a role in increasing the ionization density necessary for arc formation during welding. However, if the sodium content is less than 0.06%, the above-mentioned role is insufficient, causing arc instability during welding or causing defects in the weld metal. On the other hand, if the sodium content exceeds 0.11%, the ionization density increases and the arc force during welding becomes strong. The downside is that welding becomes difficult as it ages. Metals or oxides used as sodium in the present invention include NaF, NaAlF ₆ , NaO·SiO ₂ ·Al ₂ O ₃ , NaO·SiO _{2 ,} etc.

Potassium (K): 0.13~0.21%

Potassium (K) contains 0.13 to 0.21% in conversion. Potassium, like sodium, is an alkali metal in the periodic table of elements and plays the same role as sodium, increasing the ionization density necessary for arc formation during welding. However, if the potassium content is less than 0.13%, the above-mentioned role is insufficient and arc formation becomes unstable during welding. On the other hand, if the potassium content exceeds 0.21%, the ionization density increases and the arc force becomes stronger during welding, making welding difficult or difficult. There is a disadvantage in that defects occur in the weld metal. In addition, in transverse electrogas arc welding, the stability of the arc during welding is most effective when the ratio of sodium and potassium is 1:2. Metals or oxides used as potassium in the present invention include KAlF ₄ , K ₂ SiF ₆ , K ₂ O·SiO ₂ ·Al ₂ O ₃ , and the like.

Titanium dioxide (TiO ₂ ):1.89~2.31%

Titanium dioxide (TiO ₂ ) contains 1.89 to 2.31% in conversion. During transverse electrogas arc welding, slag is necessary to secure the weld metal between the weld base material or steel material, the ceramic backing agent, and the copper immersion. In addition, after removing the slag after the first transverse electrogas arc welding, slag is absolutely necessary to make weld metal even when performing the second transverse welding two to three times. At this time, the main ingredient of slag is titanium dioxide. If the titanium dioxide content is less than 1.89%, the amount of slag generated is small, and the slag may not evenly cover the upper part of the welded metal, which may cause poor appearance of the welded metal and make it difficult to remove slag from the upper part of the welded metal. On the other hand, if the content exceeds 2.31%, the problem of slag flowing into the copper dip or leaking out of the copper dip during welding occurs, and the oxides of the slag increase the oxygen content in the weld metal, which reduces impact toughness. There is.

Zirconium dioxide (ZrO ₂ ):0.63~1.05%

Zirconium dioxide or zirconium oxide (ZrO ₂ ) contains 0.63 to 1.05% in conversion. Zirconium dioxide is one of the slag components and plays a role in creating the geometric shape of the weld metal. When its content is less than 0.63%, its role is insignificant, and slag formation on the upper part of the weld metal is not smooth in transverse electrogas arc welding. Bead defects occur. On the other hand, if the content exceeds 1.05%, the amount of slag generated during welding increases, leading to the problem of unstable slag formation between the copper dip and the weld metal, and the oxygen content of the weld metal increases, which has the disadvantage of reducing impact toughness.

Silicon oxide (SiO ₂ ):0.42~0.84%

Silicon dioxide or silicon oxide (SiO ₂ ) contains 0.42 to 0.84% in conversion. In transverse electrogas arc welding, it plays a role in improving the fluidity of slag between the copper dip and weld metal. When the silicon oxide content is less than 0.42%, the above-mentioned role is insufficient and there is no slag fluidity effect, so slag may cover the top of the weld metal unevenly and may not be removed. On the other hand, if the content exceeds 0.84%, the weld metal and slag are not uniform, or the slag is tilted downward or in one direction, making slag removal difficult. Additionally, as the oxygen content increases, impact toughness decreases.

Aluminum oxide (Al ₂ O ₃ ):0.11~0.32%

Aluminum oxide (Al ₂ O ₃ ) contains 0.11 to 0.32% in conversion. Aluminum oxide is a compound with a very high melting point. In transverse electrogas arc welding, it plays a role in uniform removal of slag on the upper part of the weld metal by raising the melting point of the slag between the copper immersion and the weld metal. However, if the content is less than 0.11%, the aforementioned role is insufficient and there is no slag removal effect. On the other hand, if the content exceeds 0.32%, the slag melting point increases and slag cannot be removed, or the impact toughness decreases due to the increase in the oxygen content of the weld metal. There may be a disadvantage of reducing .

Fluorine (F): 0.02~0.06%

Fluorine (F) contains 0.02 to 0.06% in converted value in the welding wire of the present invention. Fluorine reduces the viscosity of molten slag and improves the ability of slag to be discharged from the inside of the copper immersion to the outside during welding. However, if the fluorine content is less than 0.02%, the slag discharge ability is reduced, and slag increases around the welding arc, making the arc unstable, increasing spatter generation, and causing weld metal defects. On the other hand, if it exceeds 0.06%, welding becomes difficult due to an increase in the amount of fume during welding. In addition, the viscosity of the slag is lowered and the solidification speed of the slag is lowered, so melting of the weld metal may occur during welding, or the molten metal and slag may cool without being separated from each other, causing defects and making it difficult to remove the slag. In the present invention, CaF ₂ , NaF, LiF, Na ₃ AlF ₆ , K ₃ AlF ₆ , K ₂ SiF ₆ , AlF ₃ , MgF ₂ , etc. may be used as the fluorine compound.

Relation 1

The present invention is characterized in that the value defined by the following relational equation 1 satisfies the range of 0.15 to 0.35. A typical flux-filled wire should float as slag on the weld metal immediately after transverse welding. This slag plays a role in fixing the weld metal and makes multi-layer welding possible. However, transverse electrogas arc welding generates about 50% less slag than a typical flux-filled weld, making it impossible to fix the weld metal without copper immersion. Therefore, in the flux-filled wire for transverse electrogas arc welding, if the value defined in Equation 1 below is less than 0.15, the weld metal and slag mix or stick to the copper dip, making it difficult to remove the slag after welding. Additionally, due to the presence of slag inside the weld metal, there may be problems with welding defects in non-destructive testing. On the other hand, if the value defined in equation 1 below exceeds 0.35, the slag is irregularly cooled between the weld metal and the copper immersion, resulting in sections where slag increases and sections where it decreases, making it difficult to remove slag debris and causing more severe damage. In this case, a large amount of slag may exist between the weld metal and the copper dip, making welding impossible.

[Relationship 1]

In addition, the remaining components of the present invention include iron (Fe) powder and the like.

In addition to the above-mentioned ingredients, unintended impurities may inevitably be introduced from raw materials or the surrounding environment during normal manufacturing processes, so this cannot be excluded. Since these impurities are known to anyone skilled in the ordinary manufacturing process, all of them are not specifically mentioned in this specification.

The welding wire of the present invention can generally have a single-sheath structure in which a metal sheath surrounds a flux of alloy components. At this time, in the present invention, the diameter of the wire is suitably about 1.2 to 1.4 mm, and the weight fraction of the metal shell is approximately 50 to 90 as the weight fraction of the entire welding wire, considering the difference in density of the shell and the density of the flux. % is preferred.

During transverse electrogas arc welding using the flux-filled wire of the present invention having the composition as described above, the resulting sound weld metal can have excellent strength and low-temperature impact toughness.

Hereinafter, the present invention will be described in detail through examples.

(Example)

Flux-cored welding wires having the same components as shown in Tables 1 and 2 above were prepared. Meanwhile, in the case of the comparative example in Table 2, Si, Mn, Mg, Al, Na, K, TiO ₂ , ZrO 2 , SiO _{2 ,} Al ₂ O ₃ , and F in the flux-cored wire of transverse electrogas arc welding according to the present invention. Twenty-two comparative examples were set, each with a composition exceeding the upper and lower limits of the composition, and four comparative examples were additionally set, which satisfied the composition range of the present invention but did not satisfy relational equation 1.

Transverse electrogas arc welding was performed using the welding materials prepared as described above. Specifically, as shown in Table 3 below, transverse electrogas arc welding was performed to form 80% of the total weld metal, and then the slag on the upper part of the weld metal was removed. And the final welding was performed under the lateral welding conditions shown in Table 4 below.

Figure 1 is a cross-sectional view of weld metal obtained when a flux-filled wire is used in transverse electrogas arc welding under the welding conditions shown in Table 3 above. And Figure 2 is a cross-sectional view of the lateral carriage weld metal in which the secondary welding is performed under the welding conditions in Table 4 after the lateral electrogas welding is completed. Meanwhile, in FIGS. 1-2, reference numeral 100 denotes a weld base material, 110 denotes a root gap, 120 denotes copper immersion, 130 denotes a ceramic backing agent, 140 and 200 denote weld metal, and 150 denotes slag.

After welding is completed under the welding conditions in Tables 3 and 4, non-destructive testing, Charpy impact testing, and A tensile test was conducted and the results are shown in Tables 5-6 below. In addition, welding performance was evaluated during transverse electrogas arc welding, and the results are shown in Table 5-6 below.

Meanwhile, in Tables 5-6 below, the non-destructive test of the weld metal to which the flux-filled wire of the invention example and comparative example was applied is a radiographic test (RT), which uses gamma (γ) radiation to sensitize the film on the other side of the weld metal. The presence or absence of defects was confirmed. Additionally, the Charpy impact test was conducted at a temperature of -20°C, and impact toughness was measured at -20°C. And, for welding performance, ◎ is very good, ○ is good, △ is average, and × is poor. In the comprehensive evaluation, satisfying all three items (non-destructive test, Charpy impact test) with good welding performance is considered very good. ◎, one or more deficiencies are indicated as good ○, one or more deficiencies with deteriorated welding performance are indicated with average △, and those with two or more deficiencies with deteriorated welding performance are indicated with ×.

As shown in Tables 1 and 5 above, it can be confirmed that in the case of invention examples in which the composition of the plus-filled wire satisfies the scope of the present invention, good welding performance can be observed and excellent low-temperature impact toughness characteristics are observed. Specifically, the Charpy impact test results showed low-temperature impact toughness characteristics of more than 70J on average, tensile strength of 543 ~ 588 MPa, elongation of 28.5 ~ 32.1%, and yield strength characteristics of more than 455 MPa, confirming that the tensile properties are also excellent. .

In contrast, as shown in Tables 2 and 6 above, in the case of comparative examples in which the composition of the flux-filled wire and the relational equation 1 were outside the scope of the present invention, welding performance was mostly reduced, and the low-temperature impact toughness properties were also lower than the standard value of 50J. The following is shown. In addition, it can be seen that the tensile strength exceeded the standard value of 600 MPa, and there were many cases where the elongation was less than 22% and the yield strength exceeded 400 MPa.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible without departing from the technical spirit of the present invention as set forth in the claims. This will be self-evident to those with ordinary knowledge in the field.

Claims (1)

In the flux-filled wire for transverse electrogas arc welding in which the metal shell is filled with flux,
In percent by weight, C: 0.011 to 0.032%, Si: 0.21 to 0.63%, Mn: 1.47 to 2.10%, Mg: 0.21 to 0.42%, Al: 0.21.0 to 0.42%, Na: 0.06 to 0.11%, K :0.13~0.21%, TiO ₂ :1.89~2.31%, ZrO ₂ :0.63~1.05%, SiO ₂ :0.42~0.84%, Al ₂ O ₃ :0.11~0.32%, F:0.02~0.06%, the rest is iron. A flux-filled wire for transverse electrogas arc welding that contains (Fe) and inevitable impurities and satisfies the following relational expression 1.
[Relational Expression 1]

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