Preparation method of high-plasticity welding wire steel

Abstract

The invention belongs to the technical field of steel manufacturing, and particularly discloses a preparation method of high-plasticity welding wire steel, which comprises the following steps: controlling the tapping temperature and components of a converter, feeding molten steel to an LF (ladle furnace) for refining, adding lime into top slag in a ratio of 4: 3: 3 for three times during LF refining, adding aluminum particles and ferrosilicon powder into a steel ladle, transporting the steel ladle to an RH (Ruhrstahl Heraeus) refining position, and controlling parameters of RH vacuum treatment, aluminum particles are added into a steel ladle, the insertion depth of a submersed nozzle and the argon flow velocity are adjusted during continuous casting, and a final steel strip comprises the following components in percentage by weight: 0.01-0.035% of C, less than or equal to 0.006% of Si, 0.2-0.25% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.03% of Cu, less than or equal to 0.04% of Cr, less than or equal to 0.01% of Ni, less than or equal to 0.0030% of N, less than or equal to 0.00015% of H and the balance of Fe and inevitable impurities; the purity of molten steel is improved by strictly controlling components of refining slag and top slag in smelting, refining and rolling forming; the problems that in the smelting, refining and rolling forming stages of welding wire steel production, too many non-metallic inclusions exist, and consequently air holes and slag inclusions are generated in the welding process are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel manufacturing, in particular to a preparation method of high plasticity welding wire steel. BACKGROUND

[0002] High plasticity welding wire steel is a special steel material designed for welding materials, such as welding wire and welding rod. Its core feature is excellent plastic deformation capability and cold working performance, which can withstand severe deformation such as drawing and rolling without cracking. This type of steel is designed with low carbon (C≤0.08%) and low sulfur and phosphorus (S / P≤0.010%) pure composition, and adds trace elements such as titanium and boron to refine the grain, ensuring the toughness and crack resistance of the deposited metal during welding. Its typical applications include automatic welding of high-strength steel, low-temperature steel, and weather-resistant steel, which need to meet the process requirements of low spatter and high wire feeding stability, and are suitable for different protective gas environments. Strict control of rolling, cooling and annealing is required during production to balance strength and plasticity, and it is widely used in key welding fields such as ships, bridges and pressure vessels.

[0003] The preparation process of high plasticity welding wire steel mainly includes: molten iron pretreatment, converter smelting, refining, continuous casting, controlled rolling and cooling, annealing, multi-pass drawing, surface copper plating and precision winding. Non-metallic inclusions are generated during the smelting, refining and rolling forming stages of welding wire steel production. These non-metallic inclusions mainly include oxides (such as Al2O3, SiO2, MgO·Al2O3 spinel), sulfides (such as MnS, CaS) and complex inclusions (such as calcium aluminate). Among them, hard oxides such as Al2O3 and spinel can easily cause stress concentration during drawing, leading to welding wire fracture; although MnS has a certain plasticity, excessive existence can reduce the impact toughness of the weld metal, and the brittle characteristics of CaS make it a potential crack source; complex inclusions can destroy the uniformity of the material if the size is too large. These inclusions can also cause porosity and slag inclusion during welding, reducing the mechanical properties of the welded joint. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of high plasticity welding wire steel to solve the problem of excessive non-metallic inclusions in the smelting, refining and rolling forming stages of welding wire steel production, which leads to porosity and slag inclusion during welding.

[0005] To achieve the above purpose, the basic scheme provided by the present application is: a preparation method of high plasticity welding wire steel, comprising the following steps: S1. The converter tapping temperature is 1620-1640℃, the composition of the converter tapping molten steel is controlled, and after tapping is completed, the top slag of the ladle is added with 200-250kg / furnace of sintered material of composite refining slag based on active lime, dolomite and high alumina bauxite, and then the molten steel after smelting is sent to the LF refining furnace through the ladle; S2. During the temperature raising process in the LF refining furnace, 100-150 kg / furnace of active lime is added to the ladle top slag, the lime is added in three times according to the amount of 4:3:3, the temperature is raised to 1610-1635℃, and the composition of the refining slag system is controlled; S3. After the LF refining, 80 kg / furnace of aluminum particles and 50 kg / furnace of ferrosilicon powder are added to the ladle top slag, the bottom argon blowing of the ladle is closed, and then the ladle is transported to the RH vacuum treatment; S4. The RH vacuum degree is controlled to be 75-90 Pa, the oxygen is determined after vacuum treatment for 13 min, aluminum particles are added according to the oxygen content in the molten steel, the ring flow is 80 t / min, the vacuum circulation time is ≥8 min after adding aluminum, the total RH treatment time is 22-25 min, and the aluminum particles are added to the ladle top slag for modification; S5. The ladle after RH treatment is sent to the tundish of the continuous casting machine, the tundish is protected by the covering agent, the slag is discharged when the tundish slag is >30 mm, the double-ring argon sealing ring is used for the long nozzle of the ladle, and the graphite-ceramic composite gasket is arranged at the connection between the submerged entry nozzle and the tundish; S6. During continuous casting, the casting speed is controlled to be 1.1-1.4 m / min, the submerged entry nozzle insertion depth is adjusted according to the casting speed, and the crystallizer argon flow rate is adjusted according to the slab width; S7. After the molten steel is continuously cast, cut and cooled, it is hot sent and hot charged for rolling, the slab heating temperature is 1170-1200℃, the finish rolling temperature is 870±5℃, the coiling temperature is 650±10℃, and the final steel strip composition is controlled to be: 0.01-0.035% C, Si≤0.006% and 0.2-0.25% Mn, wherein the impurity elements are P≤0.015%, S≤0.008%, Cu≤0.03%, Cr≤0.04%, Ni≤0.01%, N≤0.0030% and H≤0.00015%, and the balance is Fe and unavoidable impurities.

[0006] The principle and benefit of the present application are as follows: when the molten steel is transferred from the converter to the ladle, the temperature of the molten steel is 1620-1640℃, the composition of the molten steel is controlled, after the tapping is finished, 200-250kg / ton of sintered material of the composite refining slag is added to the top slag of the ladle, then the molten steel after smelting is sent to the LF refining furnace through the ladle, in the process of temperature rising in the LF refining furnace, 100-150kg / ton of lime is added to the top slag of the ladle, which is added in three times according to the amount of 4:3:3, when the temperature of the LF refining furnace is raised to 1610-1635℃, the composition of the refining slag is controlled, then 80kg / ton of aluminum particles and 50kg / ton of ferrosilicon powder are added to the top slag of the ladle, the bottom argon blowing of the ladle is closed, then the ladle is transported to the RH vacuum treatment, the vacuum degree of the RH is 75-90Pa, the oxygen is fixed after the vacuum treatment for 13min, according to the oxygen content in the molten steel, the aluminum particles are added, the circulation flow is 80t / min, the vacuum circulation time after the addition of aluminum is ≥8min, the total time of the RH treatment is 22-25min, finally the top slag of the ladle is added with aluminum particles for modification, the ladle after the RH treatment is sent to the tundish of the continuous casting machine, the tundish is protected by the covering agent for pouring, when the thickness of the tundish slag is >30mm, the slag is discharged, during the continuous casting, the pulling speed is controlled to be 1.1-1.4m / min, the immersion depth of the submerged nozzle is adjusted according to the width of the slab, the argon flow rate of the crystallizer is adjusted according to the width of the slab, after the molten steel is continuously cast, cut and cooled, the hot sending, hot charging and rolling are carried out, the heating temperature of the slab is 1170-1200℃, the final rolling temperature is 870±5℃, the coiling temperature is 650±10℃, the composition of the final steel strip is controlled to be: 0.01-0.035% of C, ≤0.006% of Si and 0.2-0.25% of Mn, wherein the impurity elements are ≤0.015% of P, ≤0.008% of S, ≤0.03% of Cu, ≤0.04% of Cr, ≤0.01% of Ni, ≤0.0030% of N and ≤0.00015% of H, the balance is Fe and inevitable impurities.

[0007] By controlling the composition of the refining slag at the processes of converter tapping, LF refining and RH vacuum treatment, the purity of the molten steel is improved, then the composition of the refining slag is further controlled in the continuous casting process, the inclusions in the slab are reduced, the purity of the slab is improved, the tensile strength of the strip steel is controlled to be 290-340MPa, the yield strength is 190-240MPa, and the elongation is 50-59%.

[0008] In the second scheme, which is a preferred embodiment of the basic scheme, in step S1, the composition of the molten steel is 0.035-0.055% C, P≤0.012%, and S≤0.008%, and the composition of the sintered material of the combined refining slag is 20-25% CaO, SiO2≤5%, 40-45% Al2O3, 4-5% MgO, and 25% Al. Strict control of the composition of the sintered material of the combined refining slag can ensure stable physicochemical properties of the refining slag, thereby improving refining efficiency, reducing slag consumption, ensuring molten steel purity, reducing operating fluctuations, and ultimately improving molten steel quality and production stability.

[0009] In the third scheme, which is a preferred embodiment of the basic scheme, in step S2, lime is added at 4-5 min, 7-8 min, and 10 min after the start of power supply, and the refining slag system is CaO-Al2O3-SiO2-MgO, with a composition of 52-55% CaO, 30-32% Al2O3, 5-8% SiO2, and 3-4% MgO. Strict control of the lime addition time and the composition of the refining slag system can precisely control the basicity, melting point, and reactivity of the slag system, avoid premature addition of lime leading to caking and failure or late addition affecting desulfurization and deoxidization efficiency, ensure that the slag system has stable and predictable metallurgical properties, thereby improving molten steel purity and reducing smelting fluctuations.

[0010] In the fourth scheme, which is a preferred embodiment of the basic scheme, in step S4, when oxygen is determined, the amount of aluminum particles added to the molten steel is 0.17 kg / ppm, and the amount of aluminum particles added to the ladle is 50-60 kg / heat. After the top slag of the ladle is modified, the composition of the final slag in the ladle after RH treatment is controlled. Precise addition of aluminum particles according to the oxygen content in the molten steel can achieve precise stoichiometric control of aluminum deoxidization reaction, avoiding excessive aluminum leading to excessive aluminum content in the molten steel or generating too much Al2O3 inclusions, and preventing insufficient aluminum causing incomplete deoxidization. At the same time, it can optimize the morphology of deoxidization products, improve molten steel purity, and reduce aluminum resource waste.

[0011] In the fifth scheme, which is a preferred embodiment of the fourth scheme, after the top slag of the ladle is modified, the composition of the top slag is 40-46% CaO, 27-30% Al2O3, 4-6% SiO2, 7-9% MgO, CaF2≤1.5%, and 4-7% FeO. Strict control of the composition of the top slag after RH treatment and modification of the top slag of the ladle is conducive to maintaining high basicity, low oxidizability, and suitable fluidity of the top slag, which can effectively inhibit secondary oxidation of the molten steel, promote adsorption and assimilation of deoxidization products, prevent phosphorus and sulfur from returning, and form a stable protective slag layer, thereby significantly improving molten steel purity and ensuring continuous casting castability.

[0012] Scheme six, this is the preferred of the basic scheme, in step S5, the ratio in the composite covering agent is CaO / Al2O3=1.5 / 1.8, the melting point is ≤1100℃, the spreading thickness is 30-40mm;The inner ring pressure of the double ring sealing argon gas sealing ring is 0.15-0.25MPa, and the outer ring pressure is 0.05-0.1MPa;By adjusting the slag phase composition of the composite covering agent, the melting temperature and spreading property of the covering agent are optimized, so as to form a dense liquid slag layer, effectively isolate air, reduce secondary oxidation of molten steel and increase nitrogen, and promote inclusion adsorption;By adjusting the pressure difference between the inner ring and the outer ring, a dynamic air curtain barrier from inside to outside is formed, which effectively isolates air, suppresses secondary oxidation and increases nitrogen, reduces the risk of slag entrainment, and significantly improves the cleanliness of molten steel.

[0013] Scheme seven, this is the preferred of scheme six, a layer of ZrO2 ceramic layer stabilized by Y2O3 is prepared on the inner wall of the submerged nozzle, with a thickness of 200-300μm;The ceramic layer has high melting point, low thermal conductivity and excellent thermal shock resistance, forms a physical and chemical inert barrier, significantly reduces the erosion and penetration of molten steel / slag on refractory materials, reduces the increase of inclusions in molten steel caused by refractory material melting loss;At the same time, it inhibits the eutectic corrosion caused by the reaction of FeO and other oxides with the matrix, and reduces the pollution caused by the dissolution of refractory material components into molten steel, finally guarantees the cleanliness of molten steel and production continuity.

[0014] Scheme eight, this is the preferred of the basic scheme, in step S6, the calculation formula of the insertion depth of the submerged nozzle is: Wherein H is the insertion depth of the submerged nozzle, V is the pulling speed;The calculation formula of the argon flow rate of the crystallizer is: Wherein Q is the argon flow rate of the crystallizer, B is the slab width;Dynamic adjustment of nozzle depth can stabilize the molten steel flow field and meniscus fluctuation in the crystallizer, effectively reduce the risk of protective slag mixing, secondary oxidation of molten steel and increase of nitrogen, and at the same time promote the floating separation of inclusions;Dynamic adjustment of argon flow rate can not only prevent nozzle blockage, but also inhibit the overturning of meniscus and the mixing of protective slag;At the same time, fine argon bubbles can effectively carry inclusions to float up, reduce subsurface porosity and large inclusion defects, and significantly improve the cleanliness and surface quality of the cast slab. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the inclusion detection result graph before the preparation method of the high plasticity welding wire steel is improved; Figure 2 is the inclusion detection result graph after the preparation method of the high plasticity welding wire steel is improved. DETAILED DESCRIPTION

[0016] The application will be further described in detail by specific embodiments: EMBODIMENT As Figure 1 andFigure 2 The application discloses a preparation method of a high-plasticity welding wire steel. S1. The converter tapping temperature is 1620-1640 DEG C, the converter tapping molten steel composition is controlled, the molten steel composition is 0.035-0.055%C, P≤0.012%, S≤0.008%, at the end of tapping, 200-250kg / ton of active lime, dolomite and high bauxite based composite refining slag sintering material is added into the ladle top slag, the composition of the composite refining slag sintering material is 20-25%CaO, SiO2≤5%, 40-45%Al2O3, 4-5%MgO and 25%Al, then the smelted molten steel is sent to the LF refining furnace through the ladle; S2. During the temperature raising process of the LF refining furnace, 100-150kg / ton of active lime is added into the ladle top slag, the lime is added in three times according to the amount of 4:3:3, the lime adding time is 4-5min, 7-8min and 10min after starting to send electricity, the temperature is raised to 1610-1635 DEG C, the composition of the refining slag system is controlled, the refining slag system is CaO-Al2O3-SiO2-MgO, the composition is 52-55%CaO, 30-32%Al2O3, 5-8%SiO2 and 3-4%MgO; S3. After the LF refining, 80kg / ton of aluminum particles and 50kg / ton of ferrosilicon powder are added into the ladle top slag, the ladle bottom argon blowing is closed, then the ladle is transported to the RH vacuum treatment; S4. The RH vacuum degree is controlled to be 75-90Pa, the ring flow is 80t / min, the oxygen is fixed after the vacuum treatment for 13min, during the oxygen fixing, the aluminum particle adding amount in the molten steel is 0.17kg / ppm, the vacuum is pumped after the aluminum is added, the circulating time is greater than or equal to 8min, the total RH treatment time is 22-25min, the aluminum particle is added into the ladle top slag for modification, the aluminum particle adding amount is 50-60kg / ton, after the ladle top slag is modified, the top slag composition is 40-46%CaO, 27-30%Al2O3, 4-6%SiO2, 7-9%MgO, CaF2≤1.5% and 4-7%FeO; S5. The ladle after the RH treatment is sent to the tundish of the continuous casting machine, the tundish is protected from pouring by using a covering agent, the ratio of the composite covering agent is CaO / Al2O3=1.5 / 1.8, the melting point is less than or equal to 1100 DEG C, the spreading thickness is 30-40mm, the slag is discharged when the tundish slag thickness is greater than 30mm, the double-ring argon sealing ring is used for the double-ring argon sealing of the long nozzle of the ladle, the inner ring pressure of the double-ring argon sealing ring is 0.15-0.25MPa, the outer ring pressure is 0.05-0.1MPa, the graphite-ceramic composite gasket is arranged at the connection between the submerged nozzle and the tundish, a Y2O3 stabilized ZrO2 ceramic layer is prepared on the inner wall of the submerged nozzle, and the thickness is 200-300μm; S6. During continuous casting, the pulling speed is controlled to be 1.1-1.4 m / min, the insertion depth of the submerged entry nozzle is adjusted according to the pulling speed, and the calculation formula of the insertion depth of the submerged entry nozzle is: wherein H is the insertion depth of the submerged entry nozzle, and V is the pulling speed; the argon flow rate of the crystallizer is adjusted according to the slab width, and the calculation formula of the argon flow rate of the crystallizer is: wherein Q is the argon flow rate of the crystallizer, and B is the slab width; S7. After the molten steel is subjected to continuous casting, cutting and cooling, the molten steel is subjected to hot charging and rolling, the slab heating temperature is 1170-1200℃, the finish rolling temperature is 870±5℃, the coiling temperature is 650±10℃, and the component mass percentage of the final steel strip is controlled to be: 0.01-0.035% C, Si≤0.006% and 0.2-0.25% Mn, wherein the impurity elements are P≤0.015%, S≤0.008%, Cu≤0.03%, Cr≤0.04%, Ni≤0.01%, N≤0.0030% and H≤0.00015%, and the balance is Fe and inevitable impurities.

[0017] The embodiment of the present application is that when the top and bottom combined blowing converter is tapped into the ladle, the tapping amount is 120 tons, the component of the molten steel is 0.042% C, 0.01% P and 0.006% S, and the molten steel temperature is 1625-1635℃, after the tapping is completed, 220 kg of sintered material of the combined refining slag with the component of 23% CaO, 5% SiO2, 42% Al2O3, 4% MgO and 25% Al is added into the top slag of the ladle, and the molten steel after smelting is sent to the LF refining furnace by the ladle.

[0018] During the process of sending the ladle to the LF refining furnace, the LF refining furnace is first powered to heat, at the same time, 100 kg of lime is added into the top slag of the ladle, the lime is added in three times according to the ratio of 4:3:3, the adding time is 4 min, 7 min and 10 min after the LF refining furnace starts to be powered, the component of the refining slag system is controlled to be 53% CaO, 31% Al2O3, 5% SiO2 and 3% MgO, when the LF refining furnace is heated to 1615-1630℃, 80 kg of aluminum particles and 50 kg of ferrosilicon powder are added into the top slag of the ladle, the bottom argon blowing of the ladle is closed, and the bottom argon blowing stirring of the molten steel in the ladle is prohibited, and the ladle is transported to the RH vacuum treatment.

[0019] During the RH vacuum treatment, the RH vacuum degree is controlled to be 75-90 Pa, the ring flow is 80 t / min, the oxygen is fixed after vacuum treatment for 13 min, during the oxygen fixation, the aluminum particle addition amount in the molten steel is 0.17 kg / ppm, the vacuum is pumped after the aluminum addition, the vacuum circulation time is ≥8 min, the total RH treatment time is 24 min, then the aluminum particle is added to the ladle top slag for modification, the aluminum particle addition amount is 54 kg / ton, after the ladle top slag modification, the top slag composition is: 41% CaO, 29% Al2O3, 4.5% SiO2, 7.2% MgO, 1% CaF2 and 6% FeO.

[0020] The ladle after the RH treatment is sent to the tundish of the continuous casting machine, first, the tundish is protected by pouring with the composite covering agent with the ratio of CaO / Al2O3 = 1.5 / 1.8, the melting point ≤1100℃, the spreading thickness is 30-40 mm, the slag is discharged when the tundish slag thickness is >30 mm, the inner ring pressure in the double-ring argon sealing ring is controlled to be 0.15-0.25 MPa, the outer ring pressure is 0.05-0.1 MPa, the thickness of the ceramic layer is controlled to be 200-300 μm, during the continuous casting, the pulling speed is controlled to be 1.1 m / min, the immersion nozzle insertion depth is 120 mm; the slab width is controlled to be 1230 mm, the thickness is 250 mm, the crystallizer argon flow rate is 7.3 L / min.

[0021] After the molten steel is continuously cast, cut and cooled, it is hot sent and hot rolled, the slab heating temperature is 1185℃, the finish rolling temperature is 872℃, the coiling temperature is 654℃, during the primary cooling, the temperature is reduced from 654℃ to 400℃, during the final cooling, the temperature is reduced from 400℃ to room temperature, the final steel strip composition is controlled to be: 0.025% C, Si ≤0.002% and 0.21% Mn, wherein the impurity elements are 0.012% P, 0.0065% S, 0.015% Cu, Cr ≤0.012%, 0.0018% Ni, 0.0028% N and H ≤0.00015%, the balance is Fe and inevitable impurities, the tensile strength of the final cold rolled strip steel is 297 MPa, the yield strength is 203 MPa, the elongation is 56%, the results of the inclusion detection in the strip steel before and after the improvement of the production method are shown in Table 1: Table 1 Results of inclusion detection in the strip steel before and after the improvement of the production method The above-mentioned are only embodiments of the present application, and the common knowledge of specific structures and characteristics in the scheme is not described too much. It should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope claimed in this application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A method for preparing high-ductility welding wire steel, characterized in that, Includes the following steps: S1. The converter tapping temperature is 1620~1640℃. Control the composition of the molten steel tapped from the converter. After tapping, add 200-250kg / furnace of composite refining slag sintering material based on active lime, dolomite and high alumina bauxite to the top slag of the ladle. Then, send the molten steel to the LF refining furnace through the ladle. S2. During the heating process of the LF refining furnace, add 100-150 kg / furnace of active lime to the top slag of the ladle. The lime is added in three batches in a ratio of 4:3:3 to raise the temperature to 1610-1635℃ and control the composition of the refining slag system. S3. After LF refining, add 80kg / furnace aluminum granules and 50kg / furnace ferrosilicon powder to the top slag of the ladle, shut off the bottom blowing argon in the ladle, and then transport the ladle to RH vacuum treatment; S4. Control the RH vacuum degree to 75-90Pa, determine the oxygen after vacuum treatment for 13min, add aluminum particles according to the oxygen content of the molten steel, with a circulation flow rate of 80t / min, vacuum circulation time after adding aluminum ≥8min, total RH treatment time 22-25min, add aluminum particles to the ladle top slag for modification. S5. The RH-treated ladle is sent to the tundish of the continuous casting machine. The tundish is protected with a covering agent and poured. When the slag thickness in the tundish is >30mm, the slag is discharged. The long nozzle of the ladle adopts a double-ring argon gas sealing ring. A graphite-ceramic composite gasket is installed at the connection between the submerged nozzle and the tundish. S6. During continuous casting, control the casting speed to 1.1-1.4 m / min, adjust the insertion depth of the submerged nozzle according to the casting speed, and adjust the argon flow rate in the crystallizer according to the slab width; S7. After continuous casting, cutting, and cooling, the molten steel is hot-charged and rolled. The slab heating temperature is 1170-1200℃, the finishing rolling temperature is 870±5℃, and the coiling temperature is 650±10℃. The final steel strip composition is controlled to be 0.01-0.035% C, Si≤0.006% and 0.2-0.25% Mn, with impurity elements being P≤0.015%, S≤0.008%, Cu≤0.03%, Cr≤0.04%, Ni≤0.01%, N≤0.0030% and H≤0.00015%, and the balance being Fe and unavoidable impurities.

2. The method for preparing a high-ductility welding wire steel according to claim 1, characterized in that, In step S1, the composition of the molten steel is: 0.035-0.055%C, P≤0.012%, S≤0.008%, and the composition of the composite refining slag sinter is: 20-25%CaO, SiO2≤5%, 40-45%Al2O3, 4-5%MgO and 25%Al.

3. The method for preparing a high-ductility welding wire steel according to claim 1, characterized in that, In step S2, the lime is added at 4-5 min, 7-8 min, and 10 min after the power is turned on. The refining slag system is CaO-Al2O3-SiO2-MgO, with a composition of 52-55% CaO, 30-32% Al2O3, 5-8% SiO2, and 3-4% MgO.

4. The method for preparing a high-ductility welding wire steel according to claim 1, characterized in that, In step S4, during oxygen determination, the amount of aluminum particles added to the molten steel is 0.17 kg / ppm; the amount of aluminum particles added to the ladle is 50-60 kg / furnace; after the ladle top slag is modified, the composition of the final slag in the ladle after RH treatment is controlled.

5. The method for preparing a high-ductility welding wire steel according to claim 4, characterized in that, After the ladle top slag is modified, the top slag composition is: 40-46% CaO, 27-30% Al2O3, 4-6% SiO2, 7-9% MgO, CaF2≤1.5% and 4-7% FeO.

6. The method for preparing a high-ductility welding wire steel according to claim 1, characterized in that, In step S5, the ratio of CaO / Al2O3 in the composite covering agent is 1.5 / 1.8, the melting point is ≤1100℃, and the spreading thickness is 30-40mm; the inner ring pressure in the double-ring argon sealing ring is 0.15-0.25MPa, and the outer ring pressure is 0.05-0.1MPa.

7. The method for preparing a high-ductility welding wire steel according to claim 6, characterized in that, A ZrO2 ceramic layer stabilized by Y2O3 with a thickness of 200-300 μm is prepared on the inner wall of the immersion nozzle.

8. The method for preparing a high-ductility welding wire steel according to claim 1, characterized in that, In step S6, the formula for calculating the insertion depth of the submersible nozzle is: Where H is the insertion depth of the submersible nozzle and V is the pulling speed; the formula for calculating the argon flow rate in the crystallizer is: Where Q is the argon flow rate in the crystallizer and B is the slab width.

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