KR20240063539A - Wire rod for welding, method of fabricating the same, method of welding using welding rod wire and welded metal using welding rod wire - Google Patents

Abstract

In the present invention, in weight percent, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 and less than 0.03%, S: more than 0 and less than 0.03%, Cu: more than 0.5%. Below, Ni: 0.05 ~ 0.9%, Cr: 0.001 ~ 0.1%, Mo: 0.001 ~ 0.5%, Al: 0.001 ~ 0.05%, B: 0.0005 ~ 0.01%, N: 0.001 ~ 0.01%, among V, Nb and Ti At least one of V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance contains Fe and inevitable impurities, and the tensile strength is up to 700 MPa and the deviation is 40 MPa or less. Provides wire rods for welding rods.

Description

Wire for welding rods, manufacturing method of wire for welding rods, welding method using welding rod wire, and welding metal using welding rod wire {WIRE ROD FOR WELDING, METHOD OF FABRICATING THE SAME, METHOD OF WELDING USING WELDING ROD WIRE AND WELDED METAL USING WELDING ROD WIRE }

The present invention relates to a wire and a method of manufacturing the same, and more specifically, to a wire for a welding rod, a method of manufacturing a wire for a welding rod, a welding method using a welding electrode wire, and a deposited metal.

Wire rods for welding rods have excellent mechanical properties of the weld zone and high welding efficiency, so they are widely used in many industrial fields such as automobiles, shipbuilding, bridges, and architecture. However, the coating layer is peeled off due to slag generated during welding, and corrosion occurs when this part is exposed to the external environment. In particular, when peeled parts of automobile chassis parts are exposed to the outside, corrosion occurs rapidly due to calcium chloride, which is used as a snow remover in winter. To overcome this, it is necessary to minimize the slag generated during welding.

Additionally, titanium is added to ensure arc stability in high current areas, strength of the welded metal, and impact toughness. However, adding titanium not only increases the tensile strength of the wire rod after hot rolling, but also increases the deviation, causing poor wire drawing (broken wire) and poor feeding. Therefore, welding rod manufacturers use annealing heat treatment for products with high tensile strength and variation.

Related prior art includes Korean Patent Application No. 10-2013-0013537.

The technical problem to be achieved by the present invention is to provide a welding electrode wire that has excellent electrodeposition coating properties and can omit the annealing heat treatment process, a method of manufacturing the welding electrode wire, a welding method using a welding electrode wire, and a welded metal using a welding electrode wire.

However, these tasks are illustrative and do not limit the scope of the present invention.

In order to solve the above problems, a wire rod for welding rods according to an embodiment of the present invention is provided. The wire for the welding rod is expressed in weight percent: C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: 0 to 0.03% or less, S: 0 to 0.03% or less, Cu: 0 to 0.03% or less. 0.5% or less, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 to 0.01%, N: 0.001 to 0.01%, V, Nb and At least one of Ti, V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance contains Fe and inevitable impurities, and has a tensile strength of up to 700 MPa and a deviation of 40 MPa or less. Do it as

In the wire for welding rods, the final microstructure of the wire may be composed of ferrite and pearlite.

In the wire for welding rods, the average size of precipitates in the final microstructure of the wire may be 100 to 150 nm.

To solve the above problems, a method for manufacturing a wire rod for a welding rod according to an embodiment of the present invention is provided. The manufacturing method of the wire for welding rods is expressed in weight percentage: C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: 0 to 0.03% or less, S: 0 to 0.03% or less, Cu : 0 and less than 0.5%, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 to 0.01%, N: 0.001 to 0.01%, V , providing a billet containing at least one of Nb and Ti, V: 0.05 to 0.2%, Nb: 0.005 to 0.1%, Ti: 0.05 to 0.3%, the balance containing Fe and inevitable impurities; Reheating the billet in the range of 950 to 1100°C; Wire rolling the billet under the condition of a finishing rolling entrance temperature of 860 to 980°C; and winding the rolled wire rod under conditions of a coiling temperature of 800 to 900°C.

In the method of manufacturing the wire for welding rods, the wire for welding rods may have a tensile strength of up to 700 MPa and a deviation of 40 MPa or less.

In the method of manufacturing the wire for welding rods, the final microstructure of the wire may be composed of ferrite and pearlite.

In the method of manufacturing the wire for a welding rod, the average size of precipitates in the final microstructure of the wire may be 100 to 150 nm.

To solve the above problems, a welding method using a welding electrode wire according to another embodiment of the present invention is provided. The welding method using the above welding electrode wire is in weight percent, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 and less than 0.03%, S: more than 0 but less than 0.03%, Cu : 0 and less than 0.5%, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 to 0.01%, N: 0.001 to 0.01%, V , at least one of Nb and Ti, V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance includes Fe and inevitable impurities, but the tensile strength is up to 700 MPa and the tensile strength is Providing a welding electrode wire realized by drawing a wire for a welding electrode having a deviation of 40 MPa or less; And supplying the welding electrode wire in a welding process using the welding electrode wire, wherein the standard deviation of the feeding speed of the welding electrode wire is 30 to 50.

In order to solve the above problems, a welded metal using a welding electrode wire according to another embodiment of the present invention is provided. The welded metal using the welding electrode wire contains, in weight percent of the weld base material, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 but less than 0.03%, S: more than 0.03%. % or less, Cu: more than 0 but less than 0.5%, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 to 0.01%, N: 0.001 to 0.01%, at least one of V, Nb, and Ti, V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance includes Fe and inevitable impurities, and the tensile strength is up to 700 MPa. It is a deposited metal obtained by welding using a welding electrode wire obtained by drawing a welding electrode wire having a tensile strength deviation of 40 MPa or less. The deposited metal has slag attached to its surface, and the deposited metal has slag attached to its surface, and is silicon-based for the entire surface area of the deposited metal. The area fraction occupied by oxide slag is less than 5%.

According to an embodiment of the present invention, a welding rod wire that has excellent electrodeposition paintability and can omit the annealing heat treatment process, a method of manufacturing a welding rod wire, a welding method using a welding electrode wire, and a welded metal using a welding electrode wire can be implemented.

Of course, the scope of the present invention is not limited by this effect.

1 is a diagram schematically illustrating the steps required to form a bloom as part of a method of manufacturing a wire for a welding rod according to an embodiment of the present invention.
Figure 2 is a diagram schematically illustrating the steps of forming a wire after manufacturing a billet in bloom as part of a method of manufacturing a wire for a welding rod according to an embodiment of the present invention.
Figure 3 is a diagram showing the equilibrium phase fraction according to temperature change in the composition of the wire rod for a welding rod according to an embodiment of the present invention.
Figure 4 is an optical microscope photograph comparing the sizes of crystal grains in Comparative Example 1 (A) and Example 1 (B) of the experimental examples of the present invention.
Figure 5 is a scanning electron microscope photograph comparing the sizes of precipitates in Comparative Example 1 (A) and Example 1 (B) of the experimental examples of the present invention.
Figure 6 is a diagram comparing the bead surface slag generation pattern according to the silicon content in the welding electrode wire in an experimental example of the present invention.
FIG. 7A is a graph showing the welding current under the conditions of a welding process using the welding electrode wire of Comparative Example 9, and FIG. 7B is a graph showing the welding current under the conditions of the welding process using the welding electrode wire of Example 1.
Figure 8a is a graph showing the welding voltage under the conditions of the welding process using the welding electrode wire of Comparative Example 9, and Figure 8b is a graph showing the welding voltage under the conditions of the welding process using the welding electrode wire of Example 1.
Figure 9a is a graph showing the wire feeding speed among the conditions of the welding process using the welding electrode wire of Comparative Example 9, and Figure 9b is a graph showing the wire feeding speed among the conditions of the welding process using the welding electrode wire of Example 1.

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

The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following examples may be modified into various other forms, and the scope of the present invention is as follows. It is not limited to examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the spirit of the present invention to those skilled in the art. Additionally, the thickness and size of each layer in the drawings are exaggerated for convenience and clarity of explanation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to drawings that schematically show ideal embodiments of the present invention. In the drawings, variations of the depicted shape may be expected, for example, depending on manufacturing technology and/or tolerances. Accordingly, embodiments of the present invention should not be construed as being limited to the specific shape of the area shown in this specification, but should include, for example, changes in shape resulting from manufacturing.

Hereinafter, a method for manufacturing a wire rod for a welding rod according to an embodiment of the present invention will be described in detail.

Figure 1 is a diagram schematically illustrating the steps required to form a bloom as part of a method of manufacturing a wire for a welding rod according to an embodiment of the present invention, and Figure 2 is a wire for a welding rod according to an embodiment of the present invention. This is a diagram schematically illustrating the steps of forming a wire rod after manufacturing a billet in Bloom as part of the manufacturing method.

Referring to Figure 1, in order to implement the step of providing a billet, the steel making and casting steps may be performed first. For example, introducing raw materials into an electric furnace; Refining using a ladle; Fine-tuning the molten steel; The steps of performing a continuous casting process can be performed sequentially to provide bloom. The bloom may have a size of, for example, 390 mm x 530 mm.

Referring to FIG. 2, a billet or large steel bar can be produced by performing the steps of heating the bloom using a heating furnace and performing rough rolling and finishing rolling processes. The rolling process for manufacturing billets in Bloom can be understood as a large-scale rolling process. The billet may have a size of, for example, 150 mm x 150 mm or 180 mm x 180 mm. Large bar steel may, for example, have a diameter of 80 mm to 320 mm. Scarfing using heat can also be performed between rough rolling and finishing rolling.

The billet can be put into a heating furnace to perform a reheating process, and the reheated billet can then be subjected to rough rolling, intermediate rolling, and finishing rolling. The rolling process applied to the reheated billet can be understood as a small rolling process. Furthermore, after finishing the billet, a precision rolling step may be performed using a precision rolling mill (RSM). The precision-rolled wire rod is wound by a laying head, continuously stacked and transported in a ring shape on a roller conveyor, and then accumulated into a wire rod coil in an accumulator. At this time, the wire coil being transported is cooled by the blowing equipment installed at the bottom of the roller conveyor. The blowing air generated from the blowing equipment is sprayed through a slot-shaped blowing opening disposed at the bottom of the roller conveyor through a duct, and a wire coil is continuously stacked and transported in a ring shape on the roller conveyor by the sprayed cooling air. It can be cooled. The blowing cooling method using the above-described blowing equipment is called the Stelmor method.

In the method of manufacturing a wire for a welding rod according to an embodiment of the present invention, the composition of the billet in weight% is C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: 0 to 0.03. % or less, S: 0.03% or less above 0, Cu: 0.5% or less above 0, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 ~ 0.01%, N: 0.001 ~ 0.01%, at least one of V, Nb, and Ti, with V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance being Fe and inevitable impurities. It can be included.

Below, the role and content of each component included in the billet for forming the wire for the welding rod will be described.

Carbon (C): 0.01 ~ 0.15%

Carbon (C) increases the hardness of steel and reduces toughness and ductility. Strength increases up to a certain content, but as the content increases, toughness and brittleness become stronger. In order to secure the strength of the welding material, that is, to secure the required strength during high-heat input welding, the lower limit of the carbon content is set to 0.01%, and the upper limit is set to 0.01% to prevent excessive increase in tensile strength and decrease in toughness and weldability, and to reduce brittleness. It is necessary to set it to 0.15%.

Silicon (Si): 0.001 ~ 0.15%

Typically, the silicon content of carbon steel welding materials ranges from 0.4 to 1.15%. Silicon is used as a deoxidizer and forms SiO ₂ or silicic acid inclusions. It increases the hardness, elastic limit and tensile strength of the steel, while reducing the elongation and impact values. Additionally, the size of the crystal grains is increased to reduce malleability and malleability. However, if the silicon content exceeds 0.15%, the amount of silicon-based slag generated increases, making it impossible to manufacture a weld metal with excellent electrodeposition coating properties. In addition, toughness may decrease and deformation resistance may increase, resulting in a decrease in ductility properties. To ensure electrodeposition coating properties and porosity resistance, the silicon (Si) content can be more preferably controlled to 0.10% or less. Considering the aspect of securing the tensile strength of the weld zone, it is more preferable that the silicon (Si) content is in the range of 0.001 to 0.15%.

Manganese (Mn): 0.50 ~ 3.00%

Typically, manganese (Mn) in carbon steel ranges from 0.35% max for AISI 1005 steel to 1.0% max for AISI 1085 steel. Mn combines with S in steel to form MnS, preventing the formation of FeS, a low-melting point compound, and preventing the occurrence of high-temperature cracks. It also refines pearlite and causes solid solution strengthening of ferrite, increasing yield strength. Therefore, in order to reduce weldability and maintain minimum yield strength, it is necessary to set the lower limit of the Mn content to 0.50%. On the other hand, if the manganese content exceeds 3.0%, there is a problem that segregation occurs in the center of the wire, a low-temperature structure occurs during cooling, and the toughness of the weld zone deteriorates. Additionally, in the present invention, since the Si content, which is the main deoxidizing element in the wire, is kept very low, the Mn content, which acts as a deoxidizing agent, in the welded metal tends to decrease. Therefore, in the present invention, it is desirable to set the upper limit of Mn to 3.00%. Meanwhile, in the present invention, it is preferable to control the Mn and Si contents so that the Si ² /Mn content ratio satisfies the range of 0.015 or less. This is because if the content ratio exceeds the range of 0.015, the appearance of the bead of the wire may deteriorate, silicon-based slag may begin to be generated, and corrosion resistance after painting may decrease.

Phosphorus (P): 0.030% or less

P forms Fe3P compounds, which are extremely weak among steels and cause grain boundary segregation, so the upper limit needs to be limited to 0.030%.

Sulfur (S): 0.030% or less

S is usually present in carbon steel at a maximum of 0.05%. In the red-hot state, brittleness increases and tensile strength, elongation, and impact value decrease. In addition, since it reduces the porosity of the weld zone when welding galvanized steel sheets, it is desirable to limit the upper limit to 0.030%. If the sulfur content exceeds 0.03%, brittleness may be caused by excessive MnS formation.

Copper (Cu): 0.50% or less

Copper (Cu) increases the tensile strength and elastic limit of the deposited metal and increases corrosion resistance. However, since it causes surface cracks when rolling wire rods at high temperatures, it is desirable to limit the upper limit of the content to 0.50%.

Nickel (Ni): 0.05 ~ 0.9%

Nickel (Ni) is an element that increases strength and improves corrosion resistance. Nickel is used to strengthen the base because it refines the steel structure and is well dissolved in austenite and ferrite. Since it is an austenite stabilizing element, it is used in combination with chromium for austenitic stainless steel and heat-resistant steel. It is also a useful component that strengthens the low-temperature toughness of steel and does not impair weldability and malleability. In the present invention, it is preferable to control the lower limit of the content to 0.05% to ensure corrosion resistance and strength of the welded metal. Meanwhile, since nickel is an austenite stabilizing element, when added in large amounts, excessive residual austenite is formed, which reduces fatigue life and increases manufacturing costs, so it is desirable to limit the upper limit to 0.9%.

Chromium (Cr): 0.001 ~ 0.100%

Chromium (Cr) is an element that increases strength and improves corrosion resistance. It increases the strength and hardness of the welded metal and facilitates the formation of carbides. It also increases corrosion resistance, heat resistance and wear resistance. In the present invention, in order to maintain appropriate strength, it is desirable to limit the lower limit of the content to 0.001% and the upper limit to 0.100%. If the chromium content exceeds 0.1%, low-temperature structures occur when the wire is cooled after rolling, manufacturing costs increase, and the toughness of the weld zone deteriorates.

Molybdenum (Mo): 0.001~0.500%

Molybdenum (Mo) increases strength, toughness, and corrosion resistance and prevents temper embrittlement. In order to secure the strength of the deposited metal, it is desirable to set the lower limit of the content to 0.001%. On the other hand, if the content exceeds 0.500%, the strength and hardenability of the deposited metal no longer increases, so it is desirable to control the upper limit to 0.500%. If the molybdenum content exceeds 0.5%, low-temperature structures are generated when the wire is cooled after rolling, manufacturing costs increase, and the toughness of the weld zone deteriorates.

Aluminum (Al): 0.001 ~ 0.05%

Aluminum (Al) acts as a strong deoxidizer and is an element that improves toughness by refining the grain size. Aluminum is useful as a strong deoxidizer along with silicon, but if the amount added in the weld metal is large, it weakens the steel, so in the present invention, it is limited to 0.001% or more and 0.5% or less. If the aluminum content exceeds 0.05%, non-metallic inclusions are excessively formed and need to be removed during refining. However, if removal is insufficient, problems such as wire breakage during drawing due to non-metallic inclusions may occur.

Boron (B): 0.0005 ~ 0.01%

Boron (B) is an element that segregates at austenite grain boundaries and suppresses the formation of proeutectoid ferrite nuclei. In addition, as a hardenability improvement element, it can contribute to improving the strength of the weld zone, and its addition in a small amount (0.0005 to 0.003%) significantly increases hardenability. However, if added excessively, it forms Fe ₃ B and/or BN and causes red heat embrittlement, so it is desirable to limit the maximum value to 0.01%.

Nitrogen (N): 0.001 ~ 0.01%

Nitrogen (N) is an element that forms precipitates by combining with elements such as Al, Ti, V, and Nb. If the nitrogen content is less than 0.001%, there is a problem of insufficient formation of precipitates, which reduces strength, increases strength deviation, and reduces toughness. If the nitrogen content exceeds 0.01%, excessive precipitate formation increases strength deviation and brittleness. This problem appears.

The billet for forming the wire for the welding rod of the present invention may further include one or more selected from the group consisting of V: 0.05 to 0.2%, Nb: 0.005 to 0.1%, and Ti: 0.05 to 0.3%.

Vanadium (V): 0.05 ~ 0.2%

Vanadium (V) is a V-based precipitate forming element and an element that improves strength and increases toughness. Vanadium has a large carbide-forming ability, making fine-grained carbides to refine the structure of steel, and its temper softening resistance is better than that of molybdenum. Vanadium can also improve high-temperature strength, but if the content is less than 0.05%, the effect cannot be expected, and if it exceeds 0.2%, the strength is reduced due to coarse precipitates that do not dissolve during rolling and may cause strength deviation. .

Niobium (Nb): 0.005 to 0.1%

Niobium (Nb) is an element that forms Nb-based precipitates and is an element that improves strength and increases toughness. It is a powerful grain refinement element that increases the grain coarsening temperature. Decreases hardenability and reduces tempering brittleness. In the present invention, it is preferable to limit the niobium content to 0.005 to 0.1%. If the niobium content is less than 0.005%, it is difficult to secure strength and toughness due to insufficient precipitate formation, and if it exceeds 0.1%, the strength is reduced due to coarse precipitates that do not dissolve during rolling and may cause strength deviation.

Titanium (Ti): 0.05 ~ 0.3%

Titanium (Ti) is an element that forms Ti-based precipitates and is an element that increases strength, toughness, and improves weldability. Titanium has very high resistance to corrosion and acts as an arc stabilizer at high currents during welding. Since this is a slag generating element, in the present invention, it is preferable to limit the Ti content to 0.05 to 0.3%. If the titanium content is less than 0.05%, weldability is reduced, and it is difficult to secure the strength and toughness of the weld zone due to insufficient formation of precipitates. If the titanium content exceeds 0.3%, there is a problem in that the toughness of the weld zone decreases and the manufacturing cost increases.

The method of manufacturing a wire for a welding rod according to an embodiment of the present invention is, in weight percent, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: greater than 0 and less than or equal to 0.03%, S: 0 and less than 0.03%, Cu: 0 and less than 0.5%, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 to 0.01%, N : 0.001 ~ 0.01%, at least one of V, Nb, and Ti, V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance providing a billet containing Fe and inevitable impurities. Step (S10); Reheating the billet in the range of 950 to 1100°C (S20); Wire rolling the billet under the condition of a finishing rolling entrance temperature of 860 to 980°C (S30); and a step (S40) of winding the rolled wire under conditions of a coiling temperature of 800 to 900°C.

The step of providing a billet (S10) may include a process of manufacturing the bloom shown in FIG. 1 and a step of manufacturing a billet from the bloom shown in FIG. 2. The reheating step (S20) includes reheating the billet shown in FIG. 2 in a heating furnace, and the wire rolling step (S30) includes rough rolling, intermediate rolling, finishing rolling, and rough rolling of the billet shown in FIG. It includes precision rolling, and the winding step (S40) may include winding the wire rod using the laying head shown in FIG. 2.

Figure 3 is a diagram showing the equilibrium phase fraction according to temperature change in the composition of the wire rod for a welding rod according to an embodiment of the present invention.

Referring to Figure 3, when the reheating temperature of the billet exceeds 1100°C, the precipitates are rapidly decomposed and the stock capacity in the base increases, and the fine precipitates re-precipitated during rolling and cooling cause tension due to precipitation strengthening and grain refinement. The intensity increases, causing deviation. In addition, when the reheating temperature is less than 950°C, the load on the rolling equipment increases and defects such as cobbles may occur during rolling, which may reduce productivity.

If the finishing rolling entrance temperature is less than 860℃, the matrix structure is rolled in a two-phase region of ferrite and austenite, so surface defects such as rolling folds may occur due to differences in the strength of the material.

In addition, when the inlet temperature of the finishing rolling exceeds 980°C, some redissolved precipitates may not re-precipitate stably when the billet is reheated, and the rolled texture (AGS) may become unevenly coarsened in some areas, resulting in deviations in tensile strength. may be expanded. Therefore, it is preferable that the entrance temperature of finishing rolling is performed in the temperature range of 860 to 980°C.

If the coiling temperature falls below 800°C, the difference with the rolling temperature may be large, which may cause coiling shape defects. In addition, if the coiling temperature exceeds 900°C, heterogeneity in the rolled structure (AGS) may result, and thus the variation in tensile strength by location may increase in wire rod products. Therefore, it is desirable to carry out the coiling temperature in the temperature range of 800 to 900°C.

The welding rod wire realized by the manufacturing method of the welding rod wire realized through the above-described composition and process is, in weight%, C: 0.01 ~ 0.15%, Si: 0.001 ~ 0.15%, Mn: 0.5 ~ 3.0%, P: 0 Exceeding 0.03% or less, S: 0 exceeding 0.03% or less, Cu: 0 exceeding 0.5% or less, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B : 0.0005 ~ 0.01%, N: 0.001 ~ 0.01%, at least one of V, Nb, and Ti, V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance is Fe and inevitable It contains impurities, has a tensile strength of up to 700 MPa, and has a deviation of tensile strength of 40 MPa or less. The tensile strength may be, for example, 600 to 700 MPa, and the deviation of the tensile strength may be 30 to 40 MPa.

In the wire for welding rods, the final microstructure of the wire may be composed of ferrite and pearlite, and the average size of precipitates in the final microstructure of the wire may be 100 to 150 nm.

A welding rod wire can be produced through the process shown in Table 1 below using the above-described wire for a welding rod as a raw material.

Process 1 Process 2 Process 3 Process 4 Process 5 Process 6 Annealing heat treatment Surface pickling treatment 1st fresh copper plating 2nd fresh winding

The welding electrode wire according to the technical idea of the present invention can be implemented by omitting the annealing heat treatment (process 1) shown in Table 1 and performing processes 2 to 6.

A welding method using a welding electrode wire according to another embodiment of the present invention is provided. The welding method using the above welding electrode wire is in weight percent, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 and less than 0.03%, S: more than 0 but less than 0.03%, Cu : 0 and less than 0.5%, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 to 0.01%, N: 0.001 to 0.01%, V , at least one of Nb and Ti, V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance includes Fe and inevitable impurities, but the tensile strength is up to 700 MPa and the tensile strength is Providing a welding electrode wire implemented by drawing the welding electrode wire having a deviation of 40 MPa or less; and supplying the welding electrode wire in a welding process using the welding electrode wire.

In particular, in the welding method using a welding electrode wire according to another embodiment of the present invention, the standard deviation for the feeding speed of the welding electrode wire is 90 or less, for example, 30 to 50.

Meanwhile, welded metal using a welding electrode wire according to another embodiment of the present invention is provided. The welded metal using the welding electrode wire contains, in weight percent of the weld base material, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 but less than 0.03%, S: more than 0.03%. % or less, Cu: more than 0 but less than 0.5%, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 to 0.01%, N: 0.001 to 0.01%, at least one of V, Nb, and Ti, V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance includes Fe and inevitable impurities, and the tensile strength is up to 700 MPa. and is a deposited metal obtained by welding using a welding electrode wire obtained by drawing the welding electrode wire having a tensile strength variation of 40 MPa or less, wherein slag is attached to the surface of the deposited metal, and with respect to the entire surface area of the deposited metal, It is characterized in that the area fraction occupied by silicon-based oxide slag is 5% or less.

Below, preferred experimental examples are presented to aid understanding of the present invention. However, the following experimental examples are only intended to aid understanding of the present invention, and the present invention is not limited by the following experimental examples.

First Experimental Example

1. Composition of the Psalm

In this experimental example, in weight%, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 and less than 0.03%, S: more than 0 but less than 0.03%, Cu: more than 0 and 0.5 % or less, Ni: 0.05 ~ 0.9%, Cr: 0.001 ~ 0.1%, Mo: 0.001 ~ 0.5%, Al: 0.001 ~ 0.05%, B: 0.0005 ~ 0.01%, N: 0.001 ~ 0.01%, V: 0.05 ~ 0.2 %, Nb: 0.005 to 0.1%, Ti: 0.05 to 0.3%, and the remainder is Fe. Specifically, all experimental examples in Table 2 below were C: 0.08%, Si: 0.02%, Mn: 1.8%, P: 0.01%, S: 0.008%, Cu: 0.1%, Ni: 0.28%, Cr: 0.005, It has a composition of Mo: 0.005%, Al: 0.005%, B: 0.0027%, N: 0.006%, Ti: 0.110%, and the balance is Fe.

2. Process conditions and physical property evaluation

Table 2 shows the results of evaluating the structure and physical properties of the wire rod for welding rods after applying various process conditions in the experimental examples of the present invention. Figure 4 is an optical microscope photograph comparing the size of crystal grains in Comparative Example 1 (A) and Example 1 (B) of the experimental example of the present invention, and Figure 5 is Comparative Example 1 (A) and Example 1 of the experimental example of the present invention. This is a scanning electron microscope photo comparing the size of the precipitates in 1(B). The size distribution of the precipitates in Figure 5 is the result of measuring precipitates with a size of 50 nm or more, which can be measured at a magnification of 15,000 times using a scanning electron microscope.

division Reheating temperature (℃) sand rolling
Inlet temperature (℃) Winding temperature (℃) Average tensile strength (MPa) Tensile strength deviation (MPa) precipitate
average size
Range (nm) Example 1 961 884 825 629 35 139 Example 2 1032 938 857 623 31 125 Example 3 1088 964 896 632 37 107 Comparative Example 1 1110 880 825 713 69 87 Comparative example 2 1130 920 853 736 54 82 Comparative example 3 1150 940 866 785 66 73 Comparative example 4 1170 910 890 727 58 67 Comparative Example 5 1097 996 897 695 56 88 Comparative Example 6 1065 955 931 665 53 92

Referring to Table 2, Examples 1 to 3 include reheating the billet in the range of 950 to 1100°C; Wire rolling the billet under the condition of a finishing rolling entrance temperature of 860 to 980°C; and winding the rolled wire at a coiling temperature of 800 to 900°C. In this case, the wire for welding rods has a tensile strength of up to 700 MPa, satisfies a range of deviation of 40 MPa or less, and the average size of precipitates in the final microstructure of the wire satisfies a range of 100 to 150 nm.

On the other hand, Comparative Examples 1 to 4 do not satisfy the range of reheating temperature for reheating the billet: 950 to 1100°C, and the tensile strength of the wire for the welding rod: does not satisfy the range of 700 MPa or less, Deviation in tensile strength: It is not satisfactory as it exceeds the range of 40 MPa or less, and the average size of precipitates in the final microstructure of the wire rod is not satisfactory as it falls below the range of 100 to 150 nm. When the reheating temperature of the billet exceeds 1100℃, the precipitates are rapidly decomposed, increasing the stock capacity in the base, and the tensile strength increases due to precipitation strengthening and crystal grain refinement due to fine precipitates re-precipitated during rolling and cooling. The deviation of increases (see Figures 4 and 5).

In addition, Comparative Example 5 was not satisfied as the finishing rolling entrance temperature exceeded the range of 860 to 980°C in the step of wire rolling the billet, and the deviation in tensile strength: exceeded the range of 40 MPa or less, so it was not satisfied, and the temperature of the wire rod was not satisfied. The average size of the precipitates in the final microstructure is below the range of 100 to 150 nm, which is not satisfactory. When the inlet temperature of finishing rolling exceeds 980℃, some redissolved precipitates cannot be stably re-deposited when the billet is reheated, and the rolling texture (AGS) may become unevenly coarsened in some areas, thereby increasing the deviation in tensile strength. It can be.

In Comparative Example 6, the coiling temperature in the step of winding the rolled wire rod was not satisfied because it exceeded the range of 800 to 900°C, the deviation in tensile strength was not satisfied because it exceeded the range of 40 MPa or less, and the final microstructure of the wire rod was not satisfied. The average size of the precipitates is below the range of 100 to 150 nm and is therefore not satisfactory. If the coiling temperature exceeds 900°C, it may cause heterogeneity in the rolled structure (AGS), which may increase the variation in tensile strength by location in wire rod products.

Second experimental example

Figure 6 is a diagram comparing the bead surface slag generation pattern according to the silicon content in the welding electrode wire in an experimental example of the present invention. In the above experimental example, welding was performed using welding electrode wires made from welding electrode wires with different silicon components. Table 3 shows the composition (unit: weight %) of the wire for welding rods in the second experimental example. Comparative Examples 7 and 8 are general-purpose standard materials, and Comparative Example 9 has a different silicon content compared to Example 1. Example 1 of Tables 2 and 3 is implemented by the manufacturing method of the wire for welding rods of the present invention described above.

division C Si Mn P S Ni Ti B N Comparative Example 7 0.08 0.85 1.50 0.009 0.020 0.04 0.0005 0.0007 0.0056 Comparative example 8 0.08 0.70 1.20 0.010 0.015 0.03 0.0004 0.0005 0.0051 Comparative Example 9 0.08 0.20 1.79 0.009 0.009 0.30 0.109 0.0025 0.0058 Example 1 0.08 0.02 1.80 0.010 0.008 0.28 0.110 0.0027 0.0060

Referring to Figure 6 and Table 3, it can be seen that by limiting the silicon content to 0.15% by weight or less, the amount of slag generated in the weld bead is reduced, resulting in excellent electrodeposition coating properties and advantageous corrosion resistance. In particular, referring to Example 1, it can be confirmed that the deposited metal obtained by welding using a welding electrode wire has slag attached to its surface, and that the area fraction occupied by the silicon-based oxide slag is 5% or less with respect to the total surface area of the deposited metal. You can.

Third Experimental Example

FIG. 7A is a graph showing the welding current under the conditions of a welding process using the welding electrode wire of Comparative Example 9, and FIG. 7B is a graph showing the welding current under the conditions of the welding process using the welding electrode wire of Example 1. Figure 8a is a graph showing the welding voltage under the conditions of the welding process using the welding electrode wire of Comparative Example 9, and Figure 8b is a graph showing the welding voltage under the conditions of the welding process using the welding electrode wire of Example 1. Figure 9a is a graph showing the wire feeding speed among the conditions of the welding process using the welding electrode wire of Comparative Example 9, and Figure 9b is a graph showing the wire feeding speed among the conditions of the welding process using the welding electrode wire of Example 1.

Table 4 shows the average and standard deviation of welding current, welding voltage, and feeding speed among the conditions of the welding process using a welding electrode wire in an experimental example of the present invention.

Comparative Example 9 Example 1 welding current
(A) average 229.3 225.2 Standard Deviation 37.5 32.9 welding voltage
(V) average 24.9 23.9 Standard Deviation 6.6 7.1 Delivery speed
(cpm) average 982.4 970.0 Standard Deviation 98.8 37.3

Referring to FIGS. 7A, 7B, 8A, 8B, 9A, 9B and Table 4, it can be seen that the decrease in the tensile strength deviation of the material during the welding rod manufacturing process leads to a decrease in the tensile strength deviation of the final welding rod product after wire drawing. You can. If the deviation in tensile strength is large, an annealing heat treatment process must be added before drawing. The comparative example is the result of measuring the welding waveform of a welding rod with a large deviation in tensile strength. The standard deviation of feed increases during welding, which has a negative effect on welding performance such as the appearance of the weld bead and the generation of spatter. In the Example, as a result of measuring the welding waveform of a welding rod with reduced tensile strength deviation, it can be confirmed that the standard deviation of the feeding speed is significantly reduced (reduced feeding resistance) compared to the comparative example. From these results, it can be confirmed that it is possible to manufacture a heat-treated welding rod wire with excellent electrodeposition coating properties by reducing the deviation of tensile strength.

Looking at the experimental examples described above, since a lot of slag is generated as a component of the comparative example, semi-finished products (blooms, billets) made with the components of the example with a low silicon content were rolled under the same rolling conditions as Examples 1 to 3 in Table 2. When manufactured, it can be confirmed that a wire for welding rods with a low average and deviation of tensile strength is realized, and when welding using this, the deviation in feed speed is reduced and the generation of slag on the surface of the weld bead can be reduced.

Although the above description focuses on the embodiments of the present invention, various changes and modifications can be made at the level of those skilled in the art. These changes and modifications can be said to belong to the present invention as long as they do not depart from the scope of the present invention. Therefore, the scope of rights of the present invention should be determined by the claims described below.

Claims (9)

In weight percent, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 but not more than 0.03%, S: more than 0 but not more than 0.03%, Cu: more than 0 but not more than 0.5%, Ni : 0.05 ~ 0.9%, Cr: 0.001 ~ 0.1%, Mo: 0.001 ~ 0.5%, Al: 0.001 ~ 0.05%, B: 0.0005 ~ 0.01%, N: 0.001 ~ 0.01%, at least one of V, Nb, and Ti As above, V: 0.05 to 0.2%, Nb: 0.005 to 0.1%, Ti: 0.05 to 0.3%, the balance includes Fe and inevitable impurities,
Characterized by a tensile strength of up to 700 MPa and a deviation of 40 MPa or less,
Wire rod for welding rods. According to claim 1,
The final microstructure of the wire rod consists of ferrite and pearlite,
Wire rod for welding rods. According to claim 2,
The average size of the precipitates in the final microstructure of the wire is 100 to 150 nm,
Wire rod for welding rods. In weight percent, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 but not more than 0.03%, S: more than 0 but not more than 0.03%, Cu: more than 0 but not more than 0.5%, Ni : 0.05 ~ 0.9%, Cr: 0.001 ~ 0.1%, Mo: 0.001 ~ 0.5%, Al: 0.001 ~ 0.05%, B: 0.0005 ~ 0.01%, N: 0.001 ~ 0.01%, at least one of V, Nb, and Ti As above, providing a billet containing V: 0.05 to 0.2%, Nb: 0.005 to 0.1%, Ti: 0.05 to 0.3%, the balance containing Fe and inevitable impurities;
Reheating the billet in the range of 950 to 1100°C;
Wire rolling the billet under the condition of a finishing rolling entrance temperature of 860 to 980°C; and
Including, winding the rolled wire rod under the condition of a winding temperature of 800 to 900°C.
Method of manufacturing wire for welding rods. According to claim 4,
The wire for welding rods has a tensile strength of up to 700 MPa and a deviation of 40 MPa or less.
Method of manufacturing wire for welding rods. According to claim 4,
The final microstructure of the wire rod consists of ferrite and pearlite,
Method of manufacturing wire for welding rods. According to claim 6,
The average size of the precipitates in the final microstructure of the wire is 100 to 150 nm,
Method of manufacturing wire for welding rods. In weight percent, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 but not more than 0.03%, S: more than 0 but not more than 0.03%, Cu: more than 0 but not more than 0.5%, Ni : 0.05 ~ 0.9%, Cr: 0.001 ~ 0.1%, Mo: 0.001 ~ 0.5%, Al: 0.001 ~ 0.05%, B: 0.0005 ~ 0.01%, N: 0.001 ~ 0.01%, at least one of V, Nb, and Ti As above, the wire for welding rods contains V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance contains Fe and inevitable impurities, and has a tensile strength of up to 700 MPa and a tensile strength deviation of 40 MPa or less. providing fresh implemented welding electrode wire; and
Including the step of supplying the welding electrode wire in a welding process using the welding electrode wire,
Characterized in that the standard deviation for the feeding speed of the welding electrode wire is 30 to 50,
Welding method using welding rod wire. Welding base material, in weight percent, C: 0.01 to 0.15%, Si: 0.001 to 0.15%, Mn: 0.5 to 3.0%, P: more than 0 but less than 0.03%, S: more than 0 but less than 0.03%, Cu: more than 0.5 % or less, Ni: 0.05 to 0.9%, Cr: 0.001 to 0.1%, Mo: 0.001 to 0.5%, Al: 0.001 to 0.05%, B: 0.0005 to 0.01%, N: 0.001 to 0.01%, V, Nb and Ti At least one of V: 0.05 ~ 0.2%, Nb: 0.005 ~ 0.1%, Ti: 0.05 ~ 0.3%, the balance includes Fe and inevitable impurities, and the tensile strength is up to 700 MPa and the deviation of the tensile strength is 40 MPa or less. As a welded metal obtained by welding using a welding rod wire obtained by drawing a wire for a welding rod,
The deposited metal has slag attached to its surface, and the area fraction occupied by the silicon-based oxide slag is 5% or less with respect to the total surface area of the deposited metal.
Welding metal using welding rod wire.