KR20200121197A - Flux cored wire for arc welding - Google Patents

Abstract

The present invention relates to a flux cored wire for arc welding. According to one embodiment of the present invention, provided is the flux cored wire for arc welding, which comprises: a titanium oxide (TiO2)-based core unit having manganese metal (Mn); and a shell unit surrounding the core unit. The flux cored wire for arc welding has a corrected optical basicity in a range of 0.60 to 0.64. The flux cored wire has excellent physical properties such as tensile strength when welded to advanced high-strength steel (AHSS).

Description

Flux cored wire for arc welding {FLUX CORED WIRE FOR ARC WELDING}

The present invention relates to welding technology, and more particularly, to a flux-cored wire for arc welding.

There is a growing demand for advanced high-strength steels (AHSS), including transformation-induced plasticity steels and twinning-induced plasticity steels, for the construction of infrastructure such as construction and shipbuilding. However, ultra-high strength steel (AHSS) containing manganese (Mn) or aluminum (Al), in a flux-cored arc-welded (FCAW) joint, is a hydrogen-delayed crack due to the penetration of hydrogen in atmospheric moisture or welding flux. hydrogen-delayed cracking). Moreover, the ultra-high strength steel (AHSS) containing manganese (Mn) is easily oxidized during welding and behaves as a starting point of cracks, and there is a concern that physical strength and performance are deteriorated. Therefore, there is a need for research on flux-cored wires for arc welding to minimize such welding defects.

The technical problem to be solved by the present invention is to provide a flux-cored wire for arc welding that has excellent physical properties such as tensile strength when welding to ultra-high tensile steel (AHSS).

According to an embodiment of the present invention, a titanium oxide (TiO2)-based core portion having a manganese metal (Mn); And a shell portion surrounding the core portion, and a flux-cored wire for arc welding having a corrected optical basicity in the range of 0.60 to 0.64 indicating an ionization measure of an oxide constituting the core portion may be provided. .

[Equation 1]

(xi is the mole fraction of the oxide component i, ni is the number of oxygen atoms in the molecule per mole oxide of the oxide component i, ∧i is the characteristic coefficient of the oxide component i)

In one embodiment, the corrected optical basicity may be excluded from the range of 0.615 to 0.625 from the range of 0.60 to 0.64.

In one embodiment, the core portion has a titanium oxide (TiO ₂ ) in the range of 50.00 wt% to 65.00 wt%, and the manganese metal (Mn) may be in the range of 16.00 wt% to 19.00 wt%. The core portion, aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), aluminum metal (Al), magnesium metal (Mg), silicon metal (Si) and manganese oxide (MnO), or a combination thereof. The aluminum oxide (Al ₂ O ₃ ) is in the range of 1.00 wt% to 15.00 wt%, the silicon oxide (SiO ₂ ) is in the range of 4.00 wt% to 20.00 wt%, and the sodium oxide (Na ₂ O) is 0.50 Wt% to 0.80 wt%, the potassium oxide (K ₂ O) is in the range of 0.30 wt% to 0.50 wt%, the aluminum metal (Al) is in the range of 2.00 wt% to 3.50 wt%, the magnesium Metal (Mg) is in the range of 2.00 wt% to 3.50 wt%, the silicon metal (Si) is in the range of 5.50 wt% to 6.50 wt%, and the manganese oxide (MnO) is in the range of 0.01 wt% to 12.00 wt% I can. The aluminum oxide (Al ₂ O ₃ ) may be in the range of 5.00 wt% to 12.00 wt%. The manganese oxide (MnO) may be in the range of 5.00 wt% to 12.00 wt%. The silicon oxide (SiO ₂ ) may be in the range of 5.00 wt% to 15.00 wt%. The core portion may further have carbon (C) in the range of 0.03% by weight to 0.30% by weight. The shell portion may have a nickel-iron alloy (Ni-Fe) in the range of 35.00% by weight to 42.00% by weight.

In one embodiment, it may be welded in an inert gas or carbon dioxide gas atmosphere. The inert gas may be any one of He, Ne, Ar, Kr, and Xe. The base material welded with the flux-cored wire for arc welding may be a welding steel material. The base material may be low carbon steel or high manganese steel.

In the case of welding the base material with the flux-cored wire for arc welding, the welding portion of the base material or the average particle diameter (d) of the base material may be defined by the following equation.

d = 3 * (2 * N _L ) ^-1

(N _L is the number of intercepts per unit length of random lines on the SEM image)

The flux-cored wire for arc welding according to an embodiment of the present invention includes a corrected optical basicity within the range of 0.60 to 0.64, thereby preventing deterioration of mechanical properties such as tensile strength during welding. have.

1 is a perspective view showing a flux-cored wire for arc welding according to an embodiment of the present invention.
2 is a table showing the composition of the flux-cored wire and SM490A for arc welding according to embodiments of the present invention.
3 is a diagram showing examples for a physical experiment.
4A is a graph showing the tensile strength for Examples A to G, and FIGS. 4B and 4C are graphs showing the hardness of the heat affected zone and the weld metal of Examples A to G.
5A to 5C are diagrams showing SEM images of Example B.
6A to 6F are diagrams showing SEM images of Examples A, D, and G.
7A and 7B are graphs showing the viscosity of Examples A, D, and G.
8A and 8B are graphs showing the ratio of active oxygen to TiOx-MnO-SiO2-AlO3-MgO-FeO.
9 is a graph showing the electronegativity of Examples A to G.
10A and 10B are graphs showing a ratio of depth to width for Examples A to G.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, and the scope of the present invention is as follows. It is not limited to the examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete, and to completely convey the spirit of the present invention to those skilled in the art.

In the drawings, the same reference numerals refer to the same elements. Also, as used herein, the term “and/or” includes any and all combinations of one or more of the corresponding listed items.

The terms used in this specification are used to describe examples, and are not intended to limit the scope of the present invention. In addition, even if it is described in the singular in this specification, a plurality of forms may be included unless the context clearly indicates the singular. In addition, the terms "comprise" and/or "comprising" as used herein specify the presence of the mentioned shapes, numbers, steps, actions, members, elements and/or groups thereof. It does not exclude the presence or addition of other shapes, numbers, movements, members, elements and/or groups.

Further, for those skilled in the art, a structure or shape arranged “adjacent” to another shape may have a portion disposed below or overlapping with the adjacent shape.

In this specification, "below", "above", "upper", "lower", "horizontal" or "vertical" Relative terms such as, as shown on the drawings, may be used to describe the relationship between one component member, layer, or region with another component member, layer, or region. It is to be understood that these terms encompass not only the orientation indicated in the figures, but also other orientations of the device.

In the following, embodiments of the present invention will be described with reference to cross-sectional views schematically showing ideal embodiments (and intermediate structures) of the present invention. In these drawings, for example, the size and shape of the members may be exaggerated for convenience and clarity of description, and in actual implementation, variations of the illustrated shape may be expected. Accordingly, the embodiments of the present invention should not be construed as being limited to the specific shape of the region shown in this specification. In addition, reference numerals of members in the drawings refer to the same members throughout the drawings.

1 is a perspective view showing a flux cored wire 10 for arc welding according to an embodiment of the present invention.

Referring to Figure 1, the flux cored wire 10 for arc welding according to an embodiment of the present invention is a titanium oxide (TiO ₂ )-based core portion 11 and a shell portion 13 surrounding the core portion 11 It may include. The core part 11 may be a flux including titanium oxide (TiO ₂ ) in a range of 50.00% by weight or more. Preferably, the titanium oxide (TiO ₂ ) may be in the range of 50% to 65% by weight. When the content of the titanium oxide (TiO ₂ ) is less than 50% by weight, there is a concern that penetration of hydrogen may increase during welding. And, when the content of the titanium oxide (TiO ₂ ) exceeds 65% by weight, there is a concern that slag, which is an oxidation product, may be excessively generated during welding.

In one embodiment, the core part 11 may further include manganese metal (Mn). The manganese metal (Mn) may range from 16.00 wt% to 19.00 wt%. When the content of the manganese metal (Mn) is less than 16.00% by weight, there is a concern that the wettability of the base material may be reduced during welding. And, when the content of the manganese metal (Mn) exceeds 19.00% by weight, there is a concern that the penetration of hydrogen may increase during welding.

In addition, the core portion 11, in addition to the titanium oxide (TiO ₂ ) having the manganese metal (Mn), aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), sodium oxide (Na ₂ O), oxidation Potassium (K ₂ O), aluminum metal (Al), magnesium metal (Mg), silicon metal (Si) and manganese oxide (MnO) any one or a combination thereof may be further included. The aluminum oxide (Al ₂ O ₃ ) may be in the range of 1.00 wt% to 15.00 wt%. The aluminum oxide (Al ₂ O ₃ ) may serve as a source of oxygen so that a stable arc of the anode is generated during welding. In addition, the melting point and viscosity of the molten slag can be adjusted, the shape of the bead can be improved during welding, and silicon oxide can be used as an alternative component. When the content of the aluminum oxide (Al ₂ O ₃ ) is less than 1.00% by weight, the endothermic reaction occurring during thermal decomposition of the aluminum oxide (Al ₂ O ₃ ) during welding becomes unstable, and the arc may be unstable. And, when the content of the aluminum oxide (Al ₂ O ₃ ) is more than 15.00% by weight, it may be difficult to form a good bead by forming a thin film on the surface and forming excessive slag and increasing the melting point, and forming a spinel compound to remove the slag It can worsen sex. The silicon oxide (SiO ₂ ) may be in the range of 4.00% by weight to 20.00% by weight, improves viscosity during welding, improves the appearance of beads, and lowers the melting point of slag. When the content of the silicon oxide (SiO ₂ ) is less than 4.00% by weight, the slag wettability may be weakened and the slag peelability may deteriorate. In addition, when the content of the silicon oxide (SiO ₂ ) exceeds 20.00% by weight, there is a concern that the viscosity becomes excessive during welding.

The sodium oxide (Na ₂ O) may be in the range of 0.50 wt% to 0.80 wt%, may improve the flowability of slag during welding, and may be used as an arc stabilizer. When the content of the sodium oxide (Na ₂ O) is less than 0.50% by weight, there is a concern that the fluidity of the slag may decrease during welding, and the arc stability may deteriorate. And, if the content of sodium oxide (Na ₂ O) exceeds 0.80% by weight, there is a concern that fume may be excessively generated during welding, and the viscosity is too low to protect the molten pool, which may deteriorate the appearance of the beads. have.

The potassium oxide (K ₂ O) may be in the range of 0.30 wt% to 0.50 wt%, and may improve the flowability of slag during welding and may be used as an arc stabilizer. When the content of the potassium oxide (K ₂ O) is less than 0.30% by weight, there is a concern that the fluidity of the slag may decrease during welding. And, if the content of the potassium oxide (K ₂ O) exceeds 0.50% by weight, there is a concern that fume may be excessively generated during welding, and the viscosity is too low to protect the molten pool, which may deteriorate the appearance of the beads. have.

The aluminum metal (Al) may be in the range of 2.00% by weight to 3.50% by weight, and particles may be fined during welding. When the content of the aluminum metal (Al) is less than 2.00% by weight, there is a concern that particles may increase during welding. In addition, when the content of the aluminum metal (Al) is greater than 3.50% by weight, the surface tension of the weld metal increases during welding, and the particles become large, so that spatter may be excessively generated. In addition, aluminum oxide can be replaced with aluminum, and aluminum can be used as a reducing agent to reduce major alloy elements such as MnO and SiO ₂ , thereby increasing the alloy component and taking into account a secondary role to protect it. Aluminum and aluminum oxide have high electronegativity and increase arc density, thereby increasing arc stability. It can also act as a carbonate and increase the cleanliness of the molten pool.

The magnesium metal (Mg) may be in the range of 2.00% by weight to 3.50% by weight, may fine particles during welding, and may act as a strong deoxidizer. When the content of the magnesium metal (Mg) is less than 2.00% by weight, there is a concern that particles may increase during welding. In addition, when the content of the magnesium metal (Mg) exceeds 3.50% by weight, there is a concern that fume and spatter may be excessively generated while the surface tension of the weld metal increases during welding.

The silicon metal (Si) is in the range of 5.50 wt% to 6.50 wt%, and may react with oxygen during welding to serve as a deoxidizer. When the content of the silicon metal (Si) is less than 5.50% by weight, there is a concern that oxygen excessively penetrates the welded portion during welding. In addition, when the content of the silicon metal (Si) exceeds 6.50% by weight, there is a concern that slag, which is an oxide, may be excessively generated during welding. In addition, the manganese oxide (MnO) is in the range of 0.01% by weight to 12.00% by weight, and the viscosity of the slag can be controlled during welding.

In one embodiment, the core portion 11 may further have carbon (C) in the range of 0.03% by weight to 0.30% by weight. The carbon (C) is a constituent element of austenite and may have a role of improving strength. When the content of the carbon (C) is less than 0.03% by weight, there is a concern that the strength of the welded portion is lowered. In addition, when the content of carbon (C) exceeds 0.30% by weight, there is a concern that fume and spatter may be excessively generated during welding.

The shell portion 13 may be formed in a cylindrical shape. However, the shell portion 13 is not limited to the cylindrical shape, and may be affected by the shape of the core portion 11. For example, if the core portion 11 is a polygon, the shell portion 13 may also be formed in a polygonal shape.

In addition, the material of the shell portion 13 may be steel or a steel alloy. For example, the shell part 13 may have a low carbon steel or a nickel-iron alloy to prevent moisture penetration and corrosion. The nickel-iron alloy may be in the range of 35% by weight to 42% by weight. When the content of the Ni-Fe alloy is more than 43% by weight, there is a concern that the viscosity of the welded portion increases excessively during welding. In addition, when the content of the nickel-iron alloy is less than 35% by weight, there is a concern that slag, which is an oxide, increases during welding.

In one embodiment, low carbon steel was used and the filling rate was approximately 15%, and in the case of FCW (flux cored wire), the filling rate was generally in the range of 15% to 20%. The filling rate was flux weight/total wire weight)*100. Can be defined.

In one embodiment, the shell portion 13 may be manufactured in a cylindrical shape by rolling treatment by a roller. After the core part 11 is filled inside the shell part 13, the flux-cored wire 10 for arc welding may be manufactured by wire drawing.

In one embodiment of the present invention, the flux cored wire 10 for arc welding may have a corrected optical basicity (ACORR) within the range of 0.60 to 0.64. The corrected optical basicity (ACORR) may be a parameter for showing a correlation between a configuration change of a welding flux with a measured mechanical property. The corrected optical basicity (ACORR) can be calculated by the following [Equation 1].

Here, xi is the mole fraction of the oxide component i, ni is the number of oxygen atoms in the molecule per mole oxide of the oxide component i, and ∧i is the characteristic coefficient of the oxide component i. The characteristic coefficients of TiO ₂ , MnO, Al ₂ O ₃ , SiO ₂ , MgO, and FeO are shown in Table 1 below.

TiO ₂ MnO Al ₂ O ₃ SiO ₂ MgO FeO Ai 0.61 1.0 0.6 0.48 0.78 1.0

The corrected optical basicity (ACORR) according to an embodiment of the present invention may be defined as a product of a molar ratio and a characteristic coefficient (∧i) of each oxide indicating a measure for phosphorylation potential, and the composition ratio of basic oxide As the value increases, the optical basicity may increase.

The flux-cored wire 10 for arc welding according to an embodiment of the present invention has the corrected optical basicity (ACORR) within the range of 0.60 to 0.64, thereby having the maximum value of the tensile strength during a tensile test. I can. In addition, when the flux cored wire 10 for arc welding has the corrected optical basicity (ACORR) in the range of 0.60 or more or the corrected optical basicity (ACORR) in the range of less than 0.64, it is destroyed by a tensile test. Can be.

In an embodiment of the present invention, the composition and composition ratio contained in the flux cored wire 10 for arc welding disclosed in FIG. 2 may be adjusted so that the corrected optical basicity (ACORR) has a range of 0.60 to 0.64, at this time It may have a tensile strength in the range of 520 MPa to approximately 780 MPa.

Further, the flux-cored wire 10 for arc welding may be welded in an inert gas or carbon dioxide gas atmosphere. The inert gas may be any one of helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). In one embodiment, the flux-cored wire 10 for arc welding may be welded only in the atmosphere of either the inert gas or the carbon dioxide gas. In another embodiment, the flux-cored wire 10 for arc welding may be welded in the carbon dioxide gas together with the inert gas atmosphere.

In addition, the base material welded with the flux-cored wire 10 for arc welding may be a welding steel material. For example, the base material may be low carbon steel (eg, SM490A) or ultra high tensile steel (AHHS).

Hereinafter, the present invention will be described in more detail through examples. The following examples are exemplary, and the present invention is not limited thereto.

(Examples)

2 is a table showing the composition of the flux-cored wire and SM490A for arc welding according to embodiments of the present invention. Examples A to G may be flux-cored wires for arc welding according to embodiments of the present invention. Examples A to G are the titanium oxide (TiO2), the aluminum oxide (Al ₂ O ₃ ), the silicon oxide (SiO ₂ ), the sodium oxide (Na ₂ O), and the potassium oxide (K ₂ O ), the aluminum metal (Al), the magnesium metal (Mg), the silicon metal (Si), the manganese metal (Mn), and the manganese oxide (MnO).

The content of the titanium oxide (TiO2) of Examples A to G may be in the range of 50.91% by weight to 61.09% by weight, but is not limited thereto, and may be in the range of 50.00% by weight to 65.00% by weight as described above. . The content of the aluminum oxide (Al ₂ O ₃ ) in Examples A to G may be in the range of 1.13% by weight to 11.45% by weight, but is not limited thereto, and as described above, in the range of 1.00% by weight to 15.00% by weight Can be tomorrow. The content of the silicon oxide (SiO ₂ ) of Examples A to G may be in the range of 4.74 wt% to 15.53 wt%, but is not limited thereto, and may be in the range of 4.00 wt% to 20.00 wt% as described above. have.

The content of sodium oxide (Na ₂ O) in Examples A to G may be in the range of 0.59 wt% to 0.67 wt%, but is not limited thereto, and as described above, the content of sodium oxide (Na ₂ O) may be in the range of 0.50 wt% to 0.80 wt% I can. The content of potassium oxide (K ₂ O) in Examples A to G may be in the range of 0.35 wt% to 0.40 wt%, but is not limited thereto, and as described above, the content of potassium oxide (K ₂ O) may be in the range of 0.30 wt% to 0.50 wt% I can. The content of the aluminum metal (Al) in Examples A to G may be in the range of 2.70 wt% to 3.05 wt%, but is not limited thereto, and may be in the range of 2.00 wt% to 3.50 wt% as described above. .

The content of the magnesium metal (Mg) in Examples A to G may be in the range of 2.75 wt% to 3.03 wt%, but is not limited thereto, and may be in the range of 2.00 wt% to 3.50 wt% as described above. . The content of the silicon metal (Si) in Examples A to G may be in the range of 5.72 wt% to 6.45 wt%, but is not limited thereto, and may be in the range of 5.50 wt% to 6.50 wt% as described above. . The content of the manganese metal (Mn) in Examples A to G may be in the range of 16.59% by weight to 18.71% by weight, but is not limited thereto, and as described above, the manganese metal (Mn) is from 16.00% by weight to 16.00% by weight. It may be in the range of 19.00% by weight. And, in order to more clearly confirm the effect of the manganese oxide (MnO) in Examples A to G, the manganese oxide (MnO) is not included, or the manganese metal of Examples A to G The content of (Mn) may be in the range of 5.98 wt% to 11.29 wt%, but is not limited thereto, and may be in the range of 0.01 wt% to 12.00 wt% as described above.

The content of the aluminum oxide (Al ₂ O ₃ ) in Example A is 11.45% by weight, and may be greater than the content of the aluminum oxide (Al ₂ O ₃ ) in the other embodiments. The content of the aluminum oxide (Al ₂ O ₃ ) of Example B may be greater than that of the other examples except Example A, and the content of the silicon oxide (SiO ₂ ) of Example B is the embodiment. It may be larger than other embodiments except for Example C. The content of the silicon oxide (SiO ₂ ) in Example C is 15.33% by weight, and may be greater than the content of the silicon oxide (SiO ₂ ) in the other embodiments.

The content of the titanium oxide (TiO2) in Example D is 61.09% by weight, and may be greater than the content of the titanium oxide (TiO2) in the other embodiments. The content of the silicon oxide (SiO ₂ ) in Example E may be greater than in other embodiments except for Example C. The content of manganese oxide (MnO) in Example F may be greater than in other embodiments except for Example G. The content of manganese oxide (MnO) in Example G is 11.29% by weight, and may be greater than the content of titanium oxide (TiO2) in the other embodiments.

And, the base material may be the SM490A. The SM490A is a low carbon steel having 0.17% by weight of carbon (C), and may include silicon (Si), manganese (Mn), phosphorus (P), and sulfur (S). The content of carbon (C) in SM490A is not limited to 0.17% by weight, and may be 0.2% by weight or less. In addition, the base material is not limited to SM490A, and may be an ultra-high tensile steel (AHSS) such as high manganese steel having a large content of manganese (Mn).

3 is a diagram showing a specimen for a physical experiment.

First, each of Examples A to G of FIG. 2 may be welded to the base material using a welding machine. The welding machine may be P500L (welbee, Daihen, Janpan). The welding machine can generate an arc with a current of 280 A and a voltage of 30 V. The welding machine can be operated in a protective gas atmosphere. The protective gas may include argon (Ar) and carbon dioxide (CO2). In another embodiment, the protective gas is not limited to including both argon (Ar) and carbon dioxide (CO2), and any one of argon (Ar) and carbon dioxide (CO2) may be selectively included. Specifically, when the welding material is a low-carbon steel, a mixed gas of argon (Ar) and carbon dioxide (CO2) is used as a protective gas, and when the welding material is high manganese steel, carbon dioxide (CO2) may be used as a protective gas. Examples A to G are wires having a diameter of 1.4 Φ, and the welding speed by the welding machine may be 0.3 m/min.

Referring to FIG. 3, the base material 30 welded by the above embodiments includes a base portion 31, a weld metal 33, and a heat-affected zone 35 (HAZ: heat-affected zone). I can. The base portion 31 may be the same as the configuration of the base material before welding. The weld metal 33 may refer to a part of the base part 31 that is melted by welding and any one of the above melted embodiments fused to each other. The heat-affected part 35 is located between the base part 31 and the weld metal 33, and may be a part of the base material 30 that is not melted although the metal structure and mechanical properties change during welding.

Meanwhile, the specimen 40 may be manufactured from the welded base material 30 to measure physical properties such as a tensile test. The specimen 40 may be elongated in the length (a) direction, like a typical tensile specimen. The length (a) may be, for example, 100 mm. In addition, the width f of the central portion of the specimen 40 may be smaller than the width g of both ends of the specimen 40. For example, the width f of the central portion may be 6 mm in an error range of plus/minus 0.1 mm. In addition, the width g of both ends may be 10 mm. In addition, the thickness of the specimen 40 may be, for example, 1.4 mm.

A weld metal 43 may be located in the central portion of the specimen 40. Heat affected portions 45 may be located on both sides of the weld metal 43. In addition, the base portion 41 may be positioned on both side surfaces of the heat affected portion 45. In one embodiment, a part of the weld metal 43, the heat affected part 45, and the base part 41 may be located in the central part. And, the length (C) of the central portion may be, for example, 32 mm. The specimen 40 may have rod portions positioned on both sides of the central portion. The base portion 41 is located in the rod portion, and the length (b) of the rod portion may be, for example, 30 mm.

4A is a graph showing the tensile strength for Examples A to G, and FIGS. 4B and 4C are graphs showing the hardness of the heat affected zone and the weld metal of Examples A to G.

First, looking at Figure 4a, it can be seen that Examples A to G have a tensile strength in the range of about 520 MPa to about 780 MPa in the corrected optical basicity (ACORR) in the range of 0.60 to 0.64. have. Therefore, the flux-cored wire for arc welding according to the embodiments of the present invention has a corrected optical basicity (ACORR) within the range of 0.60 to 0.64, thereby ensuring tensile strength within the range of approximately 520 MPa to approximately 780 MPa. There is an advantage. Specifically, the composition of the flux-cored wire for arc welding may be adjusted to have a corrected optical basicity (ACORR) ranging from 0.60 to 0.64.

In addition, it can be seen that Example A has the highest content of aluminum oxide (Al ₂ O ₃ ) compared to the other examples, and has the highest tensile strength in the atmosphere of the carbon dioxide gas. Likewise, Example A can secure a relatively high tensile strength even in an atmosphere of argon gas. That is, the flux-cored wire for arc welding according to an embodiment of the present invention has an advantage of securing high tensile strength by having an aluminum oxide (Al ₂ O ₃ ) content of 11.45% by weight.

Next, it can be seen that Example D has the highest content of titanium oxide (TiO2) compared to other examples, and has relatively low tensile strength. In addition, it can be seen that Example C has the highest content of silicon oxide (SiO ₂ ) and the lowest tensile strength compared to other examples. In addition, Example B and Example E contain a relatively large amount of the silicon oxide (SiO ₂ ) in common compared to the other examples compared to Example D. Although Example B contains a relatively large amount of the silicon oxide (SiO ₂ ), it contains a relatively large amount of the aluminum oxide (Al ₂ O ₃ ), thereby securing higher tensile strength compared to Example C and Example D. It can be seen that. In addition, Example E secures high tensile strength compared to Example C and Example D by containing a relatively large amount of the titanium oxide (TiO ₂ ) despite the relatively large amount of the silicon oxide (SiO ₂ ). Can be seen.

In addition, it can be seen that Example G has the highest content of manganese oxide (MnO) compared to other examples, and has high tensile strength except for Example A in the atmosphere of the argon gas. Likewise, Example G can secure relatively high tensile strength even in an atmosphere of carbon dioxide gas. In addition, it can be seen that Example F has a high content of manganese oxide (MnO) compared to other examples excluding Example G, and has a relatively high tensile strength. That is, the flux-cored wire for arc welding according to an embodiment of the present invention has the manganese oxide (MnO) in the range of 5.98 wt% to 11.29 wt%, thereby securing relatively high tensile strength.

The flux-cored wire for arc welding according to embodiments of the present invention has the corrected optical basicity (ACORR) in the range of 0.600 to 0.615 and 0.625 to 0.640 than the corrected optical basicity (ACORR) in the range of 0.615 to 0.625. ), it can be seen that higher tensile strength can be secured. That is, according to an embodiment of the present invention, the design of the composition of the flux-cored wire for arc welding has the advantage of using the corrected optical basicity (ACORR) without simply considering only the content of a specific component.

FIG. 4B shows the hardness of the heat affected zone (HAZ), and FIG. 4C shows the hardness of the weld metal. 4B and 4C, the hardness of the embodiments is constant, similar to the tensile strength shown in FIG. 4A in the corrected optical basicity (ACORR) in the range of 0.600 to 0.640. It can be seen that it has the above hardness. In addition, it can be seen that the heat-affected portion HAZ of Example A has the highest hardness compared to the heat-affected portion HAZ of other embodiments.

In addition, it can be seen that the weld metal of Example F has the highest hardness compared to the weld metal of other embodiments in an argon gas atmosphere. Accordingly, the flux-cored wire for arc welding according to the embodiments of the present invention has the corrected optical basicity in the range of 0.600 to 0.615 and the corrected optical basicity in the range of 0.625 to 0.640 than that having the corrected optical basicity (ACORR) in the range of 0.615 to 0.625. It can be seen that having (ACORR) can secure higher hardness.

As described above, in the region where the corrected optical basicity (ACORR) is lower than 0.62, the tensile strength is affected by the content of aluminum oxide (Al ₂ O ₃ ), and the corrected optical basicity (ACORR) is higher than 0.62. In the region, it can be seen that the tensile strength is affected by the content of the manganese oxide (MnO).

5A to 5C are diagrams showing SEM images of Example B.

The weld metal of Example B may have an austenite phase and a ferrite phase, as shown in FIG. 5A. As shown in FIG. 5B, the heat-affected part HAZ of Example B may have a pearlite phase. As shown in FIG. 5C, the base portion of Example B may have a pearlite phase and a ferrite phase. That is, it can be seen that the weld metal, the heat-affected part, and the base part of Example B have different phases. The pearlite phase may be generated from the base metal of SM490A, which is the base material.

The ferrite phase may contribute to the high strength of the weld metal. In addition, the weld metal has a ferrite phase and an austenite phase having a small particle size, and thus may have a somewhat higher strength than the heat affected zone.

6A to 6F are diagrams showing SEM images of Examples A, D, and G.

First, a scanning electron microscope (SEM) image can be used to obtain an average particle size d. The average particle size d may be determined by the following [Equation 2] which is the following Smith and Gutterman equation.

N _L may be the number of intercepts per unit length of a random line on the SEM image. Table 2 below may represent values obtained by the above [Equation 2].

Argon gas Carbon dioxide gas Example A Example D Example G Example A Example D Example G Average particle size
(μm) 3.26 6.36 3.15 4.07 7.74 4.56

The heat-affected part (HAZ) of Example A is formed by welding in an argon gas atmosphere, as shown in FIG. 6A, and may have the average particle size (d) of 3.26 μm. The heat-affected part (HAZ) of Example D is formed by welding in an argon gas atmosphere, as shown in FIG. 6B, and may have the average particle size (d) of 6.36 μm. The heat-affected part (HAZ) of Example G is formed by welding in an argon gas atmosphere, as shown in FIG. 6C, and may have the average particle size (d) of 3.15 μm.

The heat affected zone (HAZ) of Example A is formed by welding in a carbon dioxide gas atmosphere, as shown in FIG. 6D, and may have the average particle size d of 4.07 μm. The heat-affected part (HAZ) of Example D is formed by welding in a carbon dioxide gas atmosphere, as shown in FIG. 6E, and may have the average particle size (d) of 7.74 μm. The heat-affected part (HAZ) of Example G is formed by welding in a carbon dioxide gas atmosphere, as shown in FIG. 6F, and may have the average particle size d of 4.56 μm.

As such, it can be seen that the heat-affected zone (HAZ) of Example D has a larger average particle size than that of other examples, and thus has a lower tensile strength than other examples. In addition, it can be seen that the average particle size (d) of the heat-affected unit (HAZ) of the embodiments is reduced by welding in an argon gas atmosphere compared to the average particle size (d) by welding in a carbon dioxide gas atmosphere. That is, it can be seen that the heat-affected unit HAZ of the embodiments can have a tensile strength secured in the argon gas atmosphere rather than the carbon dioxide gas atmosphere.

7A and 7B are graphs showing the viscosity of Examples A, D, and G.

7A and 7B, Example A, Example D, and Example G added 6% by weight sodium oxide (Na ₂ O) with the function of a fusing agent for the viscosity test. Thus, it may be a welding flux synthesized from TiOx-MnO-Al ₂ O ₃ -MgO_FeO. 7A shows that the viscosity test was performed in an argon gas atmosphere, and FIG. 7B shows that the viscosity test was performed in a carbon dioxide gas atmosphere.

It can be seen that Example D has a somewhat higher viscosity compared to Examples A and D in both an argon gas (Ar) atmosphere and a carbon dioxide gas (CO2) atmosphere in a molten state as a whole. However, it can be seen that there is no significant difference between Example A and Example D and Example G at a temperature of approximately 1773 K. That is, although the viscosity according to Tanner's law affects the spreading phenomenon, it can be seen that the overall extremely low viscosity of Examples A, D and G is an negligible effect.

8A and 8B are graphs showing the ratio of active oxygen to TiOx-MnO-SiO ₂ -Al ₂ O ₃ -MgO-FeO.

First, the active oxygen of TiOx-MnO-SiO ₂ -Al ₂ O ₃ -MgO-FeO may be of three different types. The active oxygen may be expressed according to the following reaction equation in a state in which the TiOx-MnO-SiO ₂ -Al ₂ O ₃ -MgO-FeO is melted. The O2- may cause the O0 to be broken, thereby generating two O- ions.

[Reaction Scheme]

O2- + O0 → 2O-

As shown in FIGS. 8A and 8B, it can be seen that Example D has a minimum of O2- and O0 in both an argon gas atmosphere and a carbon dioxide atmosphere. This is to form a [TiO5]6- or [TiO6]9- structure while the complex network structure formed of [AlO4]5- and [SiO4]4- is depolymerized. It can be explained that the tetrahedral structure consumes O2-, thereby increasing O-.

In addition, it can be seen that Example A has a smaller value of the corrected optical basicity (ACORR) compared to Example D, and contains more O2- and less O0 compared to Example D. have. In addition, it can be seen that Example G has a smaller value of the corrected optical basicity (ACORR) compared to Example D, and contains more O2- and less O0 compared to Example G. have.

9 is a graph showing the electronegativity of Examples A to G.

Referring to FIG. 9, an electronegativity, which is an important property of the welding flux for Examples A to G, will be described. First, the average electronegativity may be defined as the average electronegativity of the superconducting oxide at a high temperature. Example C and Example D, as shown in Fig. 9, while having the corrected optical basicity (ACORR) in the range of 6.15 to 6.25 in both the argon gas atmosphere and the carbon dioxide gas atmosphere It can be seen that it has a higher electrical voice level than that.

In addition, Example A and Example G had the corrected optical basicity (ACORR) within the range excluding the range of 6.15 to 6.25 in both the argon gas atmosphere and the carbon dioxide gas atmosphere, while having lower electronegativity than other embodiments. It can be seen that it has a degree.

10A and 10B are graphs showing a ratio of depth to width for Examples A to G.

First, in the above embodiments, the depth with respect to the width of the molten metal may affect the shape of the weld metal. For example, as the depth with respect to the width increases, the shape of the weld metal may be more convex from the surface of the base portion. In addition, the embodiments may be concentrated in the direction of the center of the molten metal, which greatly absorbs electrons when they have a large electronegativity, and this electronegativity will affect the ratio of depth to width (depth/width radio). I can.

Examples C and D are different implementations while having the corrected optical basicity (ACORR) within the range of 6.15 to 6.25 in both the argon gas atmosphere and the carbon dioxide gas atmosphere, as shown in FIGS. 10A and 10B. It can be seen that it has a higher depth-to-width ratio (depth/width radio) than the examples. In addition, Example A and Example G have the corrected optical basicity (ACORR) within a range excluding the range of 6.15 to 6.25 in both the argon gas atmosphere and the carbon dioxide gas atmosphere, and the width is lower than that of other embodiments. It can be seen that it has a depth ratio of (depth/width radio).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those who have knowledge.

10: flux cored wire for arc welding
11: core part
13: shell part

Claims (16)

A titanium oxide (TiO2)-based core portion having manganese metal (Mn); And
It includes a shell portion surrounding the core portion,
A flux cored wire for arc welding having a corrected optical basicity in the range of 0.60 to 0.64 indicating an ionization measure of an oxide constituting the core portion.
[Equation 1]

(xi is the mole fraction of the oxide component i, ni is the number of oxygen atoms in the molecule per mole oxide of the oxide component i, ∧i is the characteristic coefficient of the oxide component i)
The method of claim 1,
The corrected optical basicity is a flux-cored wire for arc welding excluding the range of 0.615 to 0.625 in the range of 0.60 to 0.64.
The method of claim 1,
The core portion, a flux cored wire for arc welding having a titanium oxide (TiO2) in the range of 50.00% by weight to 65.00% by weight.
The method of claim 3,
The manganese metal (Mn) is a flux-cored wire for arc welding in the range of 16.00% by weight to 19.00% by weight.
The method of claim 4,
The core portion, aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), aluminum metal (Al), magnesium metal (Mg), silicon metal A flux-cored wire for arc welding having any one of (Si) and manganese oxide (MnO) or a combination thereof.
The method of claim 5,
The aluminum oxide (Al ₂ O ₃ ) is in the range of 1.00 wt% to 15.00 wt%,
The silicon oxide (SiO ₂ ) is in the range of 4.00 wt% to 20.00 wt%,
The sodium oxide (Na ₂ O) is in the range of 0.50 wt% to 0.80 wt%,
The potassium oxide (K ₂ O) is in the range of 0.30 wt% to 0.50 wt%,
The aluminum metal (Al) is in the range of 2.00 wt% to 3.50 wt%,
The magnesium metal (Mg) is in the range of 2.00 wt% to 3.50 wt%,
The silicon metal (Si) is in the range of 5.50 wt% to 6.50 wt%,
The manganese oxide (MnO) is a flux-cored wire for arc welding in the range of 0.01% to 12.00% by weight.
The method of claim 6,
The aluminum oxide (Al ₂ O ₃ ) is a flux-cored wire for arc welding in the range of 5.00 wt% to 12.00 wt%.
The method of claim 6,
The manganese oxide (MnO) is a flux-cored wire for arc welding in the range of 5.00 wt% to 12.00 wt%.
The method of claim 6,
The silicon oxide (SiO ₂ ) is a flux-cored wire for arc welding in the range of 5.00 wt% to 15.00 wt%.
The method of claim 6,
The core portion, a flux cored wire for arc welding further has a carbon (C) in the range of 0.03% by weight to 0.30% by weight.
The method of claim 1,
The shell portion, a flux cored wire for arc welding having a nickel-iron alloy (Ni-Fe) in the range of 35.00% by weight to 42.00% by weight.
The method of claim 1,
Flux cored wire for arc welding that is welded in an inert gas or carbon dioxide gas atmosphere.
The method of claim 11,
The inert gas is any one of He, Ne, Ar, Kr, and Xe flux-cored wire for arc welding.
The method of claim 1,
The base material to be welded with the flux-cored wire for arc welding is a flux-cored wire for arc welding, which is a welding steel material.
The method of claim 14,
The base material is a flux-cored wire for arc welding of low carbon steel or high manganese steel.
The method of claim 14,
When welding the base material with the flux-cored wire for arc welding,
The welding portion of the base material or the average particle diameter (d) of the base material is a flux-cored wire for arc welding defined by the following equation.

(N _L is the number of intercepts per unit length of random lines on the SEM image)

Images