KR102112159B1 - Flux cored wire for austenite stainless steel - Google Patents

Abstract

Provided is an austenitic stainless steel flux-cored wire. To this end, the flux-cored wire of the present invention comprises: 1.5-4.0 wt% of TiO_2; 1.5-4.0 wt% of SiO_2; 0.1-2.5 wt% of ZrO_2; 0.1-1.0 wt% of Al_2O_3; 0.5-1.5 wt% of MnO; 0.5-1.5 wt% of the sum of at least one kind of deoxidizer selected from Si, Mn and Al; 0.01-0.05 wt% of Li; 0.1-0.5 wt% of Na; 0.1-0.5 wt% of K; 0.05-0.15 wt% of Bi_2O_3; and the balance being metal components (Fe, Ni, Cr, Mo, Nb) and inevitable impurities (C, P, S, N). Furthermore, the value of A defined by the interaction formula 1 satisfies 4.5-7.5. Therefore, a beautiful bead appearance of a single color can be formed.

Description

Austenitic stainless steel flux charging wire {FLUX CORED WIRE FOR AUSTENITE STAINLESS STEEL}

The present invention relates to an austenitic stainless steel flux charging wire, and more specifically, both carbon dioxide gas (100% CO ₂ ) and mixed gas (Ar-15 to 25% CO ₂ ) can be used as a protective gas and good welding. The present invention relates to an austenitic stainless steel flux-filled wire that not only exhibits workability and arc stability, but can also form a beautiful, beautiful bead appearance.

Austenitic stainless steel welding materials are applied to places requiring excellent corrosion resistance and stable durability, such as chemical plants, seawater structures, and nuclear power plants. In particular, with the recent growth of semiconductor-related industries, demand for monochromatic bead appearance in addition to basic welding workability is increasing.

However, the welding material for stainless steel, which is used in the related art, forms a multi-colored bead by reaction with external air (oxygen) during welding despite a sufficient flow of a protective gas and proper welding conditions, thereby making it difficult to form a monochromatic beautiful bead appearance. There is. Accordingly, there is an increasing need to develop an austenitic stainless steel flux-filled wire capable of forming a fine bead appearance with good welding workability and solid color even when using either carbon dioxide gas or mixed gas as the protective gas.

Therefore, the present invention is to solve the problems of the prior art described above, by optimally controlling the components of the flux charging wire to both carbon dioxide (CO ₂ ) and mixed gas (Ar-15 ~ 25% CO ₂ ) as a protective gas. An object of the present invention is to provide an austenitic stainless steel flux-filled wire that is not only usable but also capable of forming a solid, beautiful bead appearance.

In addition, the subject of this invention is not limited to the above-mentioned content. The subject matter of the present invention will be understood from the entire contents of the present specification, and those skilled in the art to which the present invention pertains will have no difficulty in understanding the additional subject matter of the present invention.

The present invention for achieving the above object,

In the flux charging wire in which the flux is filled in the austenitic stainless steel shell, in weight percent, TiO ₂ : 1.5 to 4.0%, SiO ₂ : 1.5 to 4.0%, ZrO ₂ : 0.1 to 2.5%, Al ₂ O ₃ : 0.1 to 1.0%, MnO: 0.5 to 1.5%, sum of one or more deoxidizers selected from Si, Mn and Al: 0.5 to 1.5%, Li: 0.01 to 0.05%, Na: 0.1 to 0.5%, K: 0.1 to 0.5%, Bi ₂ O ₃ : 0.05 ~ 0.15%, consisting of residual metal components (Fe, Ni, Cr, Mo, Nb) and unavoidable impurities (C, P, S, N) An austenitic stainless steel flux-filled wire having an A value of 4.5 to 7.5.

[Relationship 1]

The austenitic stainless steel flux filling wire according to the present invention exhibits good welding workability and arc stability in both carbon dioxide gas and mixed gas, and can obtain a single color beautiful bead appearance rather than a conventional multicolor bead appearance.

Hereinafter, the present invention will be described.

First, the composition of the austenitic stainless steel flux-filled wire of the present invention will be described in detail, and in the following,% represents the weight percent of the entire wire.

TiO ₂ : 1.5 ~ 4.0%

TiO ₂ is a slag forming agent, and serves to exhibit effects such as improved arc stability, slag encapsulation, and peelability. The amount of TiO ₂ not see the above-mentioned effect is less than 1.5%, because when it exceeds 4.0%, this weakened good welding workability arc convergence when mixed gas welding slag amount over does not occur, the content of TiO ₂ It is preferable to make it 1.5 to 4.0%.

SiO ₂ : 1.5 ~ 4.0%

SiO ₂ is a slag forming agent, which uniformizes the application of slag and serves to control the viscosity of the slag. If the content of SiO ₂ is less than 1.5%, it is difficult to form a uniform slag, and when it exceeds 4.0%, the slag viscosity is excessive, so it sticks to the welding bead and the peelability falls and the fluidity is excessive, so that the bead's amortized field is struck down, so SiO ₂ It is preferable to limit the content of 1.5 to 4.0%.

ZrO ₂ : 0.1 ~ 2.5%

ZrO ₂ is a high-melting-point oxide, which has an effect of uniformly applying slag and preventing bead flow. When the ZrO ₂ content is less than 0.1%, the effect of adding is minimal, and when it exceeds 2.5%, the melting point of the wire rises excessively and the meltability of the wire decreases and spatter scattering increases, so the content of ZrO ₂ is 0.1 to 2.5. It is preferred to limit to%.

Al ₂ O ₃ : 0.1 ~ 1.0%

Al ₂ O ₃ is a high melting point oxide and has an effect of improving the beading by raising the slag solidification point. When the content of Al ₂ O ₃ is less than 0.1%, the above-described effect is insignificant, and when it exceeds 1.0%, meltability decreases and slag remains on the beads, making it difficult to obtain a beautiful bead appearance.

MnO: 0.5 to 1.5%

MnO has the effect of controlling the melting point and viscosity of the slag and improving the spread property to improve the bead appearance. If the content of the component is less than 0.5%, the effect is negligible, and when it exceeds 1.5%, molten metal is likely to flow down and bead spreadability is poor, making it difficult to form a good conforma.

Sum of one or more deoxidizers selected from Si, Mn and Al: 0.5 to 1.5%

Usually, Si, Mn, Al, Mg, Ti, etc. are used as the deoxidizer of the flux-filled wire, but in the present invention, arc stability is deteriorated and slag foreskin deteriorates when Mg, Ti raw materials are applied to exclude them. As a deoxidizing agent, one or more of Si, Mn, and Al are used to prevent defects such as pit and blow hole, and beads flow down due to stable formation of SiO ₂ and MnO, Al ₂ O ₃ slag at high temperatures. It can prevent a good bead appearance. When the total amount of the deoxidizer is less than 0.5%, the above-described effect cannot be seen, and when it exceeds 1.5%, the balance of slag formation is broken, and the slag is not uniformly enveloped and peeling property is poor, so 0.5 to 1.5% is preferable. In the present invention, the deoxidizing agent is added to Fe-Si, Fe-Mn, Me-Mn, Me-Al, or the like.

Alkali metal Li: 0.01 to 0.05%, Na: 0.1 to 0.5%, K: 0.1 to 0.5%

Generally, an alkali metal compound is used as an arc stabilizer. In the present invention, it is preferable to apply Li, Na, K, etc. among alkali metals and limit the content to the above range. If it is less than the lower limit of the above range, it does not sufficiently function as an arc stabilizer, and if it exceeds the upper limit, the arc becomes unstable and the concentration decreases, and the amount of spatters increases. Examples of the alkali metal feedstock include Li ₂ O, LiF, Na ₂ O, NaF, Na ₃ AlF ₆ , K ₂ O, K ₂ SiF ₆ , and K ₃ AlF ₆ .

Bi ₂ O ₃ : 0.05 ~ 0.15%

Bi ₂ O ₃ is a low-melting oxide, which has the effect of improving slag peelability, but may segregate at the grain boundary during final solidification, causing high-temperature cracking. If the Bi ₂ O ₃ content is less than 0.05%, the above effect is not sufficient, and if it exceeds 0.15%, the slag melting point is low, so the bead is vulnerable to high temperature cracking, and it is preferable to limit it to 0.05 to 0.15%.

The austenitic stainless steel plus charging wire of the present invention includes Fe, Ni, Cr, Mo, Nb, etc. as a residual metal component in the stainless steel shell and flux other than the above-mentioned compositional components, which is common in the technical field belonging to the present invention. As it is a matter, it does not explain the specific range of ingredients.

In addition, in addition to the above-mentioned compositional components, stainless steel shells and fluxes contain impurities such as C, P, S, and N which are inevitably added, which means that other components cannot be excluded. Since this is a common matter in the technical field belonging to the present invention, it does not describe the specific component range.

In the present invention, the diameter of the flux charging wire is suitably 1.2 to 1.6 mm, and the amount of flux to be filled in the sheath is not limited, but the amount of the flux to be charged is preferably 20 to 30% by weight relative to the total mass of the wire. Do. If the flux filling rate is less than 20%, the amount of slag generated during welding is insufficient, so the effect expected in the present invention cannot be seen, and if it exceeds 30%, there is a disconnection in the wire manufacturing process, or the wire shape and appearance are not constant, so that the feedability during welding Will fall.

On the other hand, in the present invention, as a protective gas, in order to secure good welding workability and arc stability in both carbon dioxide gas and mixed gas, and to form a beautiful bead appearance that is not a multicolored bead appearance, a balance between a slag forming agent and an arc stabilizer The inventor confirmed this need through research. This creates a multi-colored bead with high oxygen content as Cr and Fe oxide films of tens to hundreds of nanometers are formed on the welding bead by reaction with external air (oxygen) despite the adequate flow of the protective gas and proper welding conditions during welding. . Accordingly, in order to effectively prevent the reaction between the molten metal and the outside air, to secure a monochromatic beautiful bead appearance, it is necessary to properly balance the SiO ₂ and ZrO ₂ slag forming agent with the alkali metals Li, Na, and K. SiO ₂ and ZrO ₂ in the slag effectively prevent external oxygen penetration from the outside to the molten metal during welding, effectively preventing oxidation of the weld metal after welding and forming a multi-color to single-color bead. Since the ionization tendency among alkali metals is high in the order of Li, Na, and K, reactivity with external oxygen is also large in the order of Li, Na, and K. As the content of Li and Na increases with respect to K, the reactivity with external oxygen decreases during welding, thereby forming a multi-colored bead to a single-colored bead. Therefore, as the overall slag forming agent and the K content of alkali metals Li and Na decrease, the reactivity between molten metal and external oxygen is lowered, and the penetration of external oxygen can be blocked to secure a beautiful monochromatic bead appearance. However, if the balance between the above-described SiO ₂ and ZrO ₂ and the alkali metal is broken, the slag viscosity is excessive, and it adheres to the welding bead, deteriorating the peelability, the arc becomes unstable, the concentration is poor, and the welding workability is lowered. The balance of liver ionization tendency is broken, and reactivity with external oxygen is increased to form multicolored beads. Therefore, considering the relationship between SiO ₂ and ZrO ₂ and alkali metals Li, Na, and K, the following relational expression 1 was derived.

[Relationship 1]

In the present invention, it is preferable that the A value defined by the relational expression 1 satisfies the range of 4.5 to 7.5. If the value A is less than 4.5, the penetration of external oxygen into the molten metal cannot be effectively prevented, and its reactivity is also high, and multi-colored beads can be formed. In addition, when the A value exceeds 7.5, the amount of slag exceeds the appropriate amount, and the slag adheres to the welding bead, so that the peelability deteriorates and the arc concentration becomes poor, making it difficult to obtain good welding workability. In addition, the balance of ionization tendency between alkali metals is broken, and reactivity with external oxygen is increased, and multi-colored beads may be formed.

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

(Example)

An austenitic stainless steel flux filling wire having a diameter of 1.2 mm filled with 20 to 30% of flux in a stainless steel shell as shown in Table 1 below was prepared, respectively. Here, the outer shells used in the Inventive Examples and Comparative Examples of Table 1 are all the same as SUS 304L, and the composition is shown in Table 2 below.

Flux-cored arc welding (FCAW) was performed under the welding conditions shown in Table 3 below using the austenitic stainless steel plus filled wire prepared as described above. The specific welding conditions are horizontal fillet, welding current 200 ~ 220A, welding voltage 29 ~ 31V, welding speed 20 ~ 30CPM, tip-to-tip distance 15 ~ 20mm, shielding gas with carbon dioxide gas and mixed gas with flow rate of 20L / min (Ar-20 % CO ₂ ) was used to evaluate welding workability. Specifically, arc properties, spatter, fluidity, slag encapsulation, peelability, and bead shape were evaluated, and the results are shown in Table 4, wherein evaluation results ◎ are very good, ○ are good, and △ is usually , X represents a defect.

* In Table 1, the remaining components are metal components (Fe, Ni, Cr, Mo, Nb) and inevitable impurities (C, P, S, N), and the deoxidizing agent is the sum of one or more deoxidizing agents selected from Si, Mn and Al. And A value is a value defined by relation (1).

division C Si Mn P S Ni Cr Fe Own weight% 0.02 0.52 1.05 0.02 0.005 10.05 18.25 residual

Welding posture Current (A) Voltage (V) Welding speed (CPM) Distance between towers (mm) polarity Protective gas Horizontal fillet 200 ~ 220 29 ~ 31 20 ~ 30 15-20 DC + 100% CO2,
Ar-20% CO2,
Flow rate 20L / min

As shown in Table 1 and Table 4, it can be seen that the flux-filled wires of Inventive Examples 1 to 13 satisfying the wire composition component range of the present invention all exhibit excellent weldability and form a beautiful white bead appearance.

On the other hand, in Comparative Examples 1 to 20, the A value defined in the relational expression 1 of the present invention was satisfied to form a monochromatic (silver white) bead appearance, but out of the range of wire composition components, the slag fluidity and encapsulation property was insufficient, and arc formation and Welding workability was poor, such as poor concentration.

Specifically, in Comparative Example 1, the TiO ₂ content was high, so the amount of slag was large and the arc concentration in the mixed gas was particularly poor. In Comparative Example 2, where the TiO ₂ content was excessive, the arc was unstable and the slag was not uniformly covered. Slag debris remained on the beads even after slag peeling.

In Comparative Example 3, since the MnO content was higher than the upper limit of the suggested range, molten metal flowed to form a longer lower intestine than the upper angle, and in Comparative Example 4 in which the MnO content was excessive, the content was low and the spread of beads was insufficient.

In Comparative Example 5, the ZrO ₂ content exceeded the suggested range, and the melting point increased due to an increase in melting point, resulting in a large amount of spatter.

In Comparative Examples 6, 10, and 17, ZrO ₂ , Al ₂ O ₃ , and Bi ₂ O ₃ were out of the suggested range, and the beads were struck down, resulting in poor bead shape.

In Comparative Example 7, the fluidity was good due to the excess of SiO _2, but the slag viscosity was high, so that some of the slag adhered to the beads, resulting in deterioration of the peelability, and the remains of slag after peeling. In addition, in Comparative Example 8, the bead shape was poor because the SiO ₂ content was too low and the slag fluidity was poor, so that the bottom cabinet was not uniform.

In Comparative Example 9, the bead appearance was poor because the Al ₂ O ₃ content was high, so that meltability was poor and slag debris remained on the beads.

In the case of Comparative Examples 11 to 16, the Li, Na, or K content was outside the scope of the present invention, and the arc formation was unstable and the concentration was poor, resulting in a large number of spatters, resulting in poor welding workability.

In Comparative Example 18, the Bi ₂ O ₃ content was low, resulting in poor peelability, leaving a residue of slag on the beads. In addition, in Comparative Example 19, the deoxidizer content was high, so that the slag could not be uniformly covered, and the slag debris remained on the beads even after slag peeling.

In Comparative Example 20, a defect such as a blow hole occurred in the mixed gas due to a lack of deoxidizing power in the content of the deoxidizer being less than the suggested range.

And Comparative Examples 21 to 24 satisfies the wire composition component range suggested in the present invention, but the multi-colored beads were formed as the case where the A value defined by the relational expression 1 is outside the range provided in the present invention.

As described above, in the detailed description of the present invention, the preferred embodiments of the present invention have been described, but those skilled in the art to which the present invention pertains have various modifications within the limits that do not depart from the scope of the present invention. Of course it is possible. Therefore, the scope of rights of the present invention should not be limited to the described embodiments, but should be defined by the equivalents as well as the claims described later.

Claims (2)

In the flux charging wire in which the flux is filled in the austenitic stainless steel shell, in weight percent, TiO ₂ : 1.5 to 4.0%, SiO ₂ : 1.5 to 4.0%, ZrO ₂ : 0.1 to 2.5%, Al ₂ O ₃ : 0.1 to 1.0%, MnO: 0.5 to 1.5%, sum of one or more deoxidizers selected from Si, Mn and Al: 0.5 to 1.5%, Li: 0.01 to 0.05%, Na: 0.1 to 0.5%, K: 0.1 to 0.5%, Bi ₂ O ₃ : 0.05 ~ 0.15%, consisting of residual metal components (Fe, Ni, Cr, Mo, Nb) and unavoidable impurities (C, P, S, N) Austenitic stainless steel flux filled wire with an A value of 4.5 to 7.5
[Relationship 1]

The austenitic stainless steel flux charging wire according to claim 1, wherein the amount of the flux to be filled satisfies 20 to 30% by weight of the entire wire.