A method for producing a high-titanium sulfur-containing welding wire steel

Abstract

The present application relates to a kind of high titanium sulphur welding wire steel production method, comprising: 1) converter smelting: control end point temperature, carbon content and phosphorus content;2) refining: carry out slagging and diffusion deoxidation, use low calcium ferrosilicon, high-silicon silicon manganese, low-carbon ferromanganese and titanium-iron cored wire alloying;Power supply is supplied twice, control the content of acid-soluble aluminum and dissolved oxygen in molten steel, control the nitrogen content of molten steel after refining is completed;3) continuous casting: control the casting speed and tundish superheat, add carbon-free pre-melted high-alkalinity covering agent, control the alkalinity, viscosity and composition of protective slag, control the nitrogen absorption amount of molten steel.The present application is aimed at the problem of nozzle clogging in continuous casting, adopts BOF-LF-CC production process, through the optimization of steelmaking, refining, continuous casting and mixed pouring process, can effectively avoid nozzle clogging, at the same time, improve the number of continuous casting furnace, the yield of casting blank and the surface quality of casting blank, reduce the production cost, provide strong technical support for small billet production of high titanium sulphur welding wire steel.

Description

Technical Field

[0001] This invention relates to the field of steelmaking technology, and in particular to a method for producing high-titanium sulfur-containing welding wire steel. Background Technology

[0002] Current welding technology is developing towards higher energy efficiency and higher performance. CO2 gas shielded welding wire is characterized by high efficiency, low cost, and environmental friendliness; however, it is prone to welding spatter. Research shows that adding an appropriate amount of titanium to the welding wire steel can refine the weld droplets, stabilize the arc, reduce spatter by about 50%, and reduce welding fumes by about 25%. This achieves high deposition rate and high-speed welding while reducing post-processing workload, improving welding efficiency, and enhancing weld bead formation. It is an effective way to achieve high energy efficiency and high performance welding. Titanium, as a strong deoxidizer and microalloying element, can refine weld grains, improve strength (such as yield strength and tensile strength), and maintain good weld toughness, resulting in excellent weld mechanical properties. The TiN formed by the combination of titanium and nitrogen can inhibit the formation of coarse nitrides, significantly improving the resistance to brittle fracture in low-temperature welded joints (suitable for use in environments below -40℃). Titanium reacts with sulfur (S) and oxygen (O) to form high-melting-point compounds (such as TiO2 and TiS), which can reduce low-melting-point eutectic phases and decrease hot cracking. Titanium oxides (such as TiO2) can stabilize the electric arc and reduce spatter. Furthermore, Ti can combine with nitriding to form TiN, which acts as a nitrogen fixation agent, preventing nitrogen porosity in the weld metal. Compared to equivalent products alloyed with large amounts of nickel, molybdenum, and other elements, titanium-containing alloy welding wire steel has a significant cost advantage, thus its application in high-strength steel gas shielded welding has been widely promoted. However, due to the high titanium content in the steel, the weld metal molten pool has a high interfacial viscosity and poor fluidity, affecting the welding effect. Generally, sulfur is added to the steel to reduce the interfacial tension of the molten pool and improve its fluidity.

[0003] When the titanium content in welding wire steel is high, the molten steel has high viscosity and poor fluidity, and is prone to forming high-melting-point titanium oxide inclusions during smelting. The wetting angle between titanium oxide and molten steel is less than 90°, and the titanium oxide has good contact with the molten steel, making it difficult to float and remove. During casting, as the molten steel temperature drops, it solidifies on the inclusions, exacerbating the blockage at the immersion nozzle. Furthermore, as the temperature decreases during casting, TiN precipitates at the nozzle, leading to TiN precipitation at the outlet and further blockage. Nozzle blockage not only deteriorates billet quality but can also cause production interruptions, making it a key factor limiting the industrial production of this steel grade. In conventional steelmaking, calcium treatment is performed on the molten steel to inhibit oxide nodule formation. However, calcium treatment results in excessive residual calcium content in the steel, leading to increased spatter during welding and affecting weld quality. Therefore, calcium treatment cannot be performed when producing titanium-containing welding wire steel, and the residual calcium content in the steel must be controlled.

[0004] In summary, avoiding nozzle nodules and surface scars on the billet caused by titanium oxide and titanium nitride during the production of high-titanium sulfur-containing welding wire steel billets is a pressing problem that needs to be solved. Currently, aluminum deoxidation is generally used to improve and stabilize the absorption rate of titanium when producing this type of steel. At the same time, in order to avoid the formation of alumina and titanium oxide nodules and precipitated titanium nitride nodules during continuous casting, it is necessary to strictly limit the content of acid-soluble aluminum and nitrogen in the molten steel.

[0005] Chinese invention patent CN101457273B discloses a "production method for steel used in small square continuous casting high-titanium alloy welding wire". This method involves adding aluminum-silicon-barium alloy and aluminum for pre-deoxidation during converter tapping, and feeding CaSi wire in the later stages of LF refining to modify inclusions, thus solving the problem of nozzle clogging during continuous casting. However, alkaline oxides such as CaO and MgO increase the surface tension and size of the molten droplets during welding, making them unstable and resulting in large-particle welding spatter. Furthermore, feeding CaSi wire also leads to a higher residual calcium content in the steel, causing severe spatter during welding.

[0006] Chinese invention patent CN102212749B discloses a "Production Method of High-Efficiency Alloy Welding Wire Steel for Small Billet Continuous Casting." The process route is as follows: smelting low-sulfur molten iron and scrap steel in a top-and-bottom blowing converter → slag-blocking tapping and ladle deoxidation → steel alloying → LF refining → RH refining → continuous casting with full protection on a small billet casting machine. By controlling the oxygen and nitrogen content in the molten steel through various process measures during refining and continuous casting, the aim is to control nitrogen oxides in titanium and reduce the risk of immersion nozzle blockage. However, this process requires RH vacuum nitrogen control treatment, and the sulfur content of the molten steel needs to be adjusted during RH refining. The process route is long, the operation is complex, and the production cost is high.

[0007] Chinese patent application CN102586685A discloses a smelting process for high-titanium alloy welding wire steel. The process route is: smelting low-sulfur molten iron and scrap steel in a top-and-bottom blowing electric furnace → refining → VD degassing → refining → continuous casting. By controlling the oxygen and nitrogen content in the molten steel through various process measures, the reaction between titanium and oxygen and nitrogen is controlled, thereby reducing the risk of immersion nozzle blockage. However, this process includes two refining processes and a VD vacuum treatment, resulting in a long process route, complex operation, and high production costs.

[0008] Chinese invention patent CN115351458B discloses "a steel, wire rod, and submerged arc welding wire and its preparation method for the same," which reduces the oxygen content in the steel through calcium treatment, thereby reducing the content of aluminum and titanium oxides in the molten steel and improving Al2O3 and TiOx type nozzle nodules. However, it overlooks the secondary oxidation of the molten steel caused by calcium treatment, as well as the formation of calcium sulfide and calcium titanate nodules in sulfur-containing and titanium-containing welding wire steel caused by calcium treatment. Furthermore, calcium treatment can result in excessive residual calcium in the steel, causing welding spatter.

[0009] Chinese patent application CN104259414A discloses a "Production Method for Titanium-Containing Welding Wire Steel to Reduce Nodule Formation in Continuous Casting." This method reduces nodule formation in titanium-containing welding wire steel by establishing thermodynamic boundary conditions for competitive oxidation of aluminum and titanium, controlling oxygen activity in the steel, controlling aluminum and titanium content, determining the titanium-nitrogen product, selecting nozzle refractory materials and tundish covering agents, and controlling continuous casting process parameters. However, it does not fundamentally solve the problem of small inclusions easily accumulating at the head of the stopper rod and the nozzle bowl of small square billets, and the control measures for oxygen, nitrogen, aluminum, and calcium content in the steel are also unclear.

[0010] Chinese invention patent CN120366635B discloses "A small square billet containing sulfur and titanium welding wire steel and its preparation method." In the continuous casting process, a stopper rod shaking method is used to control the accumulation of inclusions at the stopper rod head and the nozzle bowl to solve the nozzle blockage problem. However, this method requires the addition of stopper rod shaking equipment, is complex to operate, and places higher demands on the quality of the stopper rod refractory material. The casting stability also needs further evaluation. In addition, controlling the superheat of the tundish within a relatively high range of 45℃ to 55℃ will increase costs.

[0011] In existing publicly available technologies, there is no effective method to solve the problem of nozzle clogging during the casting process of high-titanium sulfur-containing welding wire steel in small square billets, and the surface quality of the cast billet is often neglected. To address these issues, this invention provides a method for producing high-titanium sulfur-containing welding wire steel in small square billets. Targeting the clogging problem at the continuous casting nozzle and immersion gate, a BOF-LF-CC production process is adopted. Through optimization of the steelmaking, refining, continuous casting, and mixed casting processes, nozzle clogging is avoided, increasing the number of continuous casting heats, billet yield, and billet surface quality, effectively reducing production costs and providing technical support for the production of high-titanium sulfur-containing welding wire steel from small square billets. Summary of the Invention

[0012] This invention provides a method for producing high-titanium sulfur-containing welding wire steel. Addressing the issue of nodule formation at the continuous casting gate and immersion gate, a BOF-LF-CC production process is adopted. Through optimization of the steelmaking, refining, continuous casting, and mixed casting processes, nodule formation can be effectively avoided. Simultaneously, the number of continuous casting heats, billet yield, and billet surface quality are improved, while production costs are reduced. This provides strong technical support for the production of high-titanium sulfur-containing welding wire steel from small billets.

[0013] To achieve the above objectives, the present invention employs the following technical solution: A method for producing high-titanium sulfur-containing welding wire steel includes a converter smelting process, a refining process, and a continuous casting process, with the following specific process controls: 1) Converter smelting: The final steel temperature in the converter smelting process is controlled at 1610-1640℃, the final carbon content is controlled at 0.025%-0.045%, and the final phosphorus content is controlled below 0.010%. Low-carbon ferrosilicon and silicomanganese are used for deoxidation and alloying during tapping, and calcium carbide and lime are added for pre-slag formation. The bottom blowing flow rate is controlled at 1200-1600 NL / min. After tapping, the dissolved oxygen content in the steel is ≤35ppm. 2) Refining: Lime, calcium carbide, and fluorite are added for slag formation and diffusion deoxidation. After slag formation, the slag basicity is controlled at CaO / SiO2 = 1.8–2.2. The slag composition by mass percentage is: Al2O3 ≤ 5%, MgO: 6%–8%, (FeO + MnO) ≤ 0.5%; CaO: 52%–56%, SiO2: 24%–28%, with the remainder being unavoidable impurities. Low-alumina ferrosilicon, high-silicon ferromanganese, low-carbon ferromanganese, and titanium-iron cored wire are used as alloying materials. Power is supplied in two stages. The first power supply is mainly for slag formation, arc submersion, and heating, with lime, calcium carbide, and fluorite added in batches. Ash slag formation; the second power supply uses ferrosilicon powder and calcium carbide for diffusion deoxidation and reduction slag formation in the slag, while simultaneously raising the temperature and fine-tuning the alloy; the acid-soluble aluminum content in the molten steel is controlled at 50-100 ppm, and the dissolved oxygen content is ≤7 ppm; low-aluminum ferrosilicon, high-silicon ferromanganese, and low-carbon ferromanganese are added for alloying, and when the white slag is maintained for 10-20 minutes, sulfur wire is fed above the argon blowing point, and titanium-iron cored wire is fed after an interval of 8-10 minutes, and then soft stirring is started, with a soft stirring time of ≥15 minutes; the furnace is kept under slight positive pressure during the refining process, and the nitrogen increase in the molten steel is controlled to ≤3 ppm after refining. 3) Continuous casting: The casting speed is controlled at 2.0-2.4 m / min, and the tundish superheat is controlled at 30-40℃. A carbon-free pre-melted high-basicity covering agent is added to the tundish. By mass percentage, the carbon-free pre-melted high-basicity covering agent contains CaO: 40%-55%, SiO2 < 6%, and Fe2O3 < 3%. The basicity of the protective slag is controlled at 0.82-0.90, and the viscosity is controlled at 1.0-1.1 Pa·s. By mass percentage, the protective slag composition is SiO2: 30%-32%, CaO: 25%-29%, MgO: 2.0%-2.5%, TiO2: 1%-3%, Fe2O3: 0.5%-1.0%, Al2O3: 5%-7%, free carbon (FC): 11%-13%, moisture ≤ 0.5%, and the balance being unavoidable impurities. Integral nozzle protection is used for casting, and the nitrogen absorption of molten steel is controlled to ≤ 3 ppm during the casting process.

[0014] After the steel is tapped from the converter and enters the argon station, pre-slag formation is carried out. The amount of calcium carbide added is 0.08-0.16 kg / t steel, and the amount of lime added is 0.8-1.6 kg / t steel.

[0015] During the refining process, the amount of lime added during slag formation and diffusion deoxidation is 4.2–5.8 kg / t steel, the amount of calcium carbide added is 0.5–0.58 kg / t steel, and the amount of fluorite added is 1.25–1.33 kg / t steel.

[0016] During the refining process, the alloying materials include low-aluminum ferrosilicon at a rate of 5–5.8 kg / t steel, high-silicon ferromanganese at a rate of 21.7–21.9 kg / t steel, low-carbon ferromanganese at a rate of 1.67–2 kg / t steel, and ferrotitanium-coated wire at a rate of 11.67–12.5 m / t steel.

[0017] During the refining process, after the first power supply, the amount of lime added is 5-5.8 kg / t steel, and the target temperature is 1580-1590℃; after the second power supply, the amount of ferrosilicon powder added is 0.17-0.25 kg / t steel, the amount of calcium carbide added is 0.17-0.25 kg / t steel, and the target temperature is 1610-1620℃.

[0018] During the refining process, the feeding speed of ferro-titanium cored wire and sulfur wire is controlled at 200-300 m / min, the amount of sulfur wire added is 0.83-1.25 m / t steel, and the bottom blowing flow rate during wire feeding is 100-200 NL, based on the creep of the slag surface.

[0019] The cross-sectional dimensions of the continuously cast billet are 140-160mm × 140-160mm.

[0020] By mass percentage, the chemical composition of the high-titanium sulfur-containing welding wire steel is: C: 0.040%–0.070%, Si: 0.75%–0.85%, Mn: 1.40%–1.55%, Ti: 0.15%–0.22%, Al: 0.005%–0.01%, P≤0.015%, S: 0.012%–0.018%, Ca≤0.0005%, N≤0.003%, with the remainder being Fe and other unavoidable impurities.

[0021] Compared with the prior art, the beneficial effects of the present invention are: 1) Employ silicon-manganese deoxidation and diffusion deoxidation methods, combined with steel slag balance control, to ensure that the total oxygen content in the steel is ≤20ppm, thus avoiding oxide inclusions causing nozzle nodules.

[0022] 2) By using converter endpoint control, refining foam slag and micro-positive pressure control, and continuous casting integral nozzle protection casting, the nitrogen content in steel is controlled to be ≤30ppm; at the same time, integral nozzles are used to reduce nozzle temperature drop and avoid nozzle nodule formation caused by titanium nitride precipitation.

[0023] 3) This invention achieves extremely low calcium, nitrogen and oxygen content control during the production of high titanium sulfur-containing welding wire steel, avoiding problems such as nozzle nodules and slag inclusions on the surface of the billet, improving the castability of molten steel, increasing the number of consecutive castings, billet yield and billet surface quality, and reducing production costs. Detailed Implementation

[0024] The present invention discloses a method for producing high-titanium sulfur-containing welding wire steel, comprising a converter smelting process, a refining process, and a continuous casting process, wherein the specific control of the process is as follows: 1) Converter smelting: The final steel temperature of the converter smelting is controlled at 1610-1640℃, the final carbon content is controlled at 0.025%-0.045%, and the final phosphorus content is controlled below 0.010%. Low-carbon ferrosilicon and silicomanganese are used for deoxidation and alloying during tapping, and calcium carbide and lime are added for pre-slag formation. The bottom blowing flow rate is controlled at 1200-1600 NL / min. After tapping, the dissolved oxygen content in the steel is ≤35ppm. After the converter tapping steel enters the argon station, pre-slag formation is carried out. The amount of calcium carbide added is 0.08-0.16 kg / t steel, and the amount of lime added is 0.8-1.6 kg / t steel.

[0025] 2) Refining: Lime, calcium carbide, and fluorite are added for slag formation and diffusion deoxidation. After slag formation, the slag basicity is controlled at CaO / SiO2 = 1.8–2.2. The slag composition, by mass percentage, is: Al2O3 ≤ 5%, MgO: 6%–8%, (FeO + MnO) ≤ 0.5%; CaO: 52%–56%, SiO2: 24%–28%, with the remainder being unavoidable impurities. Low-aluminum ferrosilicon, high-silicon ferromanganese, low-carbon ferromanganese, and ferrotitanium-coated wire are used as alloying materials. Power is supplied in two stages. The first power supply is mainly for slag formation, arc submersion, and heating, while alloy fine-tuning is performed simultaneously. Lime is added in batches to form slag; the second power supply uses ferrosilicon powder and calcium carbide to diffuse deoxidize and reduce slag in the slag, while simultaneously raising the temperature and fine-tuning the alloy; the acid-soluble aluminum content in the molten steel is controlled at 50-100 ppm and the dissolved oxygen content is ≤7 ppm; low-alumina ferrosilicon, high-silicon ferromanganese and low-carbon ferromanganese are added for alloying, and when the white slag is maintained for 10-20 minutes, sulfur wire is fed above the argon blowing point, and titanium-iron cored wire is fed after an interval of 8-10 minutes, and then soft stirring is started, with a soft stirring time of ≥15 minutes; the furnace is kept under slight positive pressure during the refining process, and the nitrogen increase in the molten steel is controlled to ≤3 ppm after refining.

[0026] During the refining process, the amount of lime added during slag formation and diffusion deoxidation is 4.2–5.8 kg / t steel, the amount of calcium carbide added is 0.5–0.58 kg / t steel, and the amount of fluorite added is 1.25–1.33 kg / t steel. During the refining process, among the alloying materials, the amount of low-aluminum ferrosilicon added is 5–5.8 kg / t steel, the amount of high-silicon ferromanganese added is 21.7–21.9 kg / t steel, the amount of low-carbon ferromanganese added is 1.67–2 kg / t steel, and the amount of ferrotitanium-iron cored wire added is 11.67–12.5 m / t steel. After the first power supply, the amount of lime added is 5–5.8 kg / t steel, with a target temperature of 1580–1590℃; after the second power supply, the amount of ferrosilicon powder added is 0.17–0.25 kg / t steel, the amount of calcium carbide added is 0.17–0.25 kg / t steel, and the target temperature is 1610–1620℃. During the refining process, the feeding speed of ferro-titanium cored wire and sulfur wire is controlled at 200-300 m / min, the amount of sulfur wire added is 0.83-1.25 m / t steel, and the bottom blowing flow rate during wire feeding is 100-200 NL, based on the creep of the slag surface.

[0027] 3) Continuous casting: The cross-sectional dimensions of the continuously cast billet are 140~160mm×140~160mm. The continuous casting speed is controlled at 2.0–2.4 m / min, the tundish superheat is controlled at 30–40℃, and a carbon-free pre-melted high-basicity covering agent is added to the tundish. By mass percentage, the carbon-free pre-melted high-basicity covering agent contains CaO: 40%–55%, SiO2 < 6%, and Fe2O3 < 3%. The basicity of the protective slag is controlled at 0.82–0.90, and the viscosity is controlled at 1.0–1.1 Pa·s. By mass percentage, the protective slag composition is SiO2: 30%–32%, CaO: 25%–29%, MgO: 2.0%–2.5%, TiO2: 1%–3%, Fe2O3: 0.5%–1.0%, Al2O3: 5%–7%, free carbon (FC): 11%–13%, moisture ≤ 0.5%, and the balance being unavoidable impurities. Integral nozzle protection is used for casting, and the nitrogen absorption of molten steel is controlled to ≤ 3 ppm during the casting process.

[0028] By mass percentage, the chemical composition of the high-titanium sulfur-containing welding wire steel is: C: 0.040%–0.070%, Si: 0.75%–0.85%, Mn: 1.40%–1.55%, Ti: 0.15%–0.22%, Al: 0.005%–0.01%, P≤0.015%, S: 0.012%–0.018%, Ca≤0.0005%, N≤0.003%, with the remainder being Fe and other unavoidable impurities.

[0029] The technical principle of the method for producing high-titanium sulfur-containing welding wire steel described in this invention is as follows: Adding low-carbon ferrosilicon, ferromanganese, calcium carbide, and lime during converter tapping for deoxidation, alloying, and pre-slag formation not only controls the total oxygen content of the molten steel but also reduces the oxidizing properties of the slag. During tapping, the combined use of molten steel and increased bottom blowing flow enhances the mixing and agitation between the slag and metal, facilitating the removal of large amounts of non-metallic inclusions through slag washing.

[0030] The refining process controls a slight positive pressure inside the furnace, while simultaneously controlling the nitrogen increase in the molten steel to ≤3ppm. The slag basicity and composition are also controlled (mainly FeO+MnO ≤0.5%, Al2O3 ≤5%). Calcium carbide and fluorite are spread on the slag surface for diffusion deoxidation. The aim is to control the acid-soluble aluminum and total oxygen content in the steel, keeping the acid-soluble aluminum (Als) content within the range of 50-100ppm and the dissolved oxygen content below 7ppm. The refining process inevitably reduces the sulfur content in the steel to a low level; therefore, sulfur wire needs to be fed in the later stages of refining to meet the composition requirements. Precise control of the wire feeding speed and timing not only reduces secondary oxidation of the molten steel but also ensures sufficient time for inclusions to float.

[0031] The continuous casting process uses an integral nozzle instead of the conventional segmented nozzle, with proper protective casting to control the nitrogen increase in the molten steel to ≤3ppm. By increasing the basicity of the protective slag, the reaction between SiO2 in the protective slag and Ti in the molten steel is inhibited. Compared to segmented nozzles, the integral nozzle, in addition to protecting the casting process, also reduces the temperature drop of the molten steel at the nozzle during casting, preventing TiN precipitation and nodulation on the inner wall of the nozzle.

[0032] During continuous casting, non-titanium-containing welding wire steel is used for the initial pour, followed by titanium-containing and sulfur-containing welding wire steel. This avoids contamination of the molten steel by refractory materials such as ladles and tundishes during the initial pour and reduces nozzle clogging.

[0033] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0034]

Example

[0035] 1. Converter smelting process; The converter tapping capacity is 130-135t, the converter endpoint [C] is 0.025%-0.040%, [P] is ≤0.012%, and the molten steel temperature is 1610℃-1640℃.

[0036] During tapping, low-carbon ferrosilicon and ferromanganese are used for deoxidation and alloying, and lime and calcium carbide are added for pre-slag formation. In this embodiment, when the tapping volume reaches 40t, low-carbon ferrosilicon and ferromanganese are added sequentially for deoxidation and alloying. When the tapping volume reaches 80t, 200-300kg of lime is added for pre-slag formation. After tapping is completed, 30-100kg of calcium carbide is added.

[0037] The slag-metal mixing is carried out by simultaneously increasing the bottom blowing flow rate while molten steel is mixed. The bottom blowing flow rate is controlled at 1000-1500 NL / min, and the dissolved oxygen content in the steel at the argon station is controlled to be ≤35ppm.

[0038] The endpoint test and off-site parameters of converter smelting in each embodiment are shown in Table 1.

[0039] Table 1 2. Refining process; Lime, calcium carbide, and fluorite are added for slag formation and diffusion deoxidation. After slag formation, the slag basicity is controlled to be CaO / SiO2 = 1.8 to 2.2.

[0040] The control targets for the refining slag system are as follows: the slag composition, by mass percentage, includes Al2O3 ≤ 5%, MgO: 6%~10%, (FeO+MnO) ≤ 0.5%; CaO: 52%~56%, SiO2: 24%~28%, with the remainder being unavoidable impurities.

[0041] It uses low-calcium ferrosilicon, high-silicon ferromanganese, low-carbon ferromanganese, and titanium-iron cored wire alloying.

[0042] Power is supplied in two stages. Calcium carbide is added during each power supply to ensure effective submerged arc firing. Based on the slag reduction status, it is determined whether to continue diffusion deoxidation in the slag to create reducing slag. Temperature and alloy fine-tuning are performed simultaneously. The first power supply focuses on slag formation, submerged arc firing, and temperature increase (lime is added in batches). After slag formation, a low-current, high-temperature rise is used to avoid repeated high-current, low-temperature heating and rapid high-current heating. The second power supply uses ferrosilicon powder and calcium carbide for diffusion deoxidation in the slag to create reducing slag, while temperature increase and alloy fine-tuning are performed simultaneously. The acid-soluble aluminum (Als) content in the molten steel is controlled at 50–100 ppm, and the dissolved oxygen content is ≤7 ppm.

[0043] When the refined white slag has been maintained for 10-20 minutes, sulfur wire is fed above the argon blowing point. After an interval of 8-10 minutes, titanium wire is fed. After feeding the titanium wire, soft stirring is started and the soft stirring time is ≥15 minutes. The feeding speed of titanium wire and sulfur wire is controlled at 200-300 m / min, and the bottom blowing flow rate during wire feeding is 100-200 NL, based on the creep of the slag surface.

[0044] During the refining process, maintain a slight positive pressure inside the furnace, and after the refining process is completed, control the nitrogen addition in the molten steel to be ≤3ppm.

[0045] The main refining process parameters for each embodiment are shown in Table 2.

[0046] Table 2 3. Continuous casting process; In this embodiment, the cross-sectional dimensions of the continuously cast billet are 150mm×150mm, the continuous casting speed is controlled at 2.1~2.4m / min, and the superheat of the tundish is 20~35℃.

[0047] The continuous casting process uses an integral nozzle, and proper protection is ensured during casting to control the nitrogen content in the molten steel to ≤3ppm.

[0048] The intermediate ladle uses a high-alkalinity carbon-free pre-melted high-alkalinity covering agent (by mass percentage, the composition is CaO: 40%–55%, SiO2 < 6%, Fe2O3 < 3%).

[0049] The basicity of the protective slag is controlled between 0.82 and 0.90, and the viscosity is controlled between 1.0 and 1.1 Pa·s. The composition of the protective slag, by mass percentage, includes SiO2: 30%–32%, CaO: 25%–29%, MgO: 2.0%–2.5%, TiO2: 1%–3%, Fe2O3: 0.5%–1.0%, Al2O3: 5%–7%, free carbon (FC): 11%–13%, and moisture ≤0.5%, with the balance being unavoidable impurities.

[0050] In this embodiment, non-titanium-containing welding wire steel is used for initial casting, followed by titanium-containing and sulfur-containing welding wire steel, to avoid nozzle clogging caused by the high oxidizability of molten steel in the initial casting furnace.

[0051] The main process parameters for continuous casting in each embodiment are shown in Table 3.

[0052] Table 3 The chemical composition of the high-titanium sulfur-containing welding wire steel products in each embodiment is shown in Table 4 (mass percentage).

[0053] Table 4 The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for producing high-titanium sulfur-containing welding wire steel, characterized in that, This includes the converter smelting process, refining process, and continuous casting process, with specific control measures implemented for the following processes: 1) Converter smelting: The final steel temperature in the converter smelting process is controlled at 1610-1640℃, the final carbon content is controlled at 0.025%-0.045%, and the final phosphorus content is controlled below 0.010%. Low-carbon ferrosilicon and silicomanganese are used for deoxidation and alloying during tapping, and calcium carbide and lime are added for pre-slag formation. The bottom blowing flow rate is controlled at 1200-1600 NL / min. After tapping, the dissolved oxygen content in the steel is ≤35ppm. 2) Refining: Lime, calcium carbide, and fluorite are added for slag formation and diffusion deoxidation. After slag formation, the slag basicity is controlled at CaO / SiO2 = 1.8–2.

2. The slag composition by mass percentage is: Al2O3 ≤ 5%, MgO: 6%–8%, (FeO + MnO) ≤ 0.5%; CaO: 52%–56%, SiO2: 24%–28%, with the remainder being unavoidable impurities. Low-alumina ferrosilicon, high-silicon ferromanganese, low-carbon ferromanganese, and titanium-iron cored wire are used as alloying materials. Power is supplied in two stages. The first power supply is mainly for slag formation, arc submersion, and heating, with lime, calcium carbide, and fluorite added in batches. Ash slag formation; the second power supply uses ferrosilicon powder and calcium carbide for diffusion deoxidation and reduction slag formation in the slag, while simultaneously raising the temperature and fine-tuning the alloy; the acid-soluble aluminum content in the molten steel is controlled at 50-100 ppm, and the dissolved oxygen content is ≤7 ppm; low-aluminum ferrosilicon, high-silicon ferromanganese, and low-carbon ferromanganese are added for alloying, and when the white slag is maintained for 10-20 minutes, sulfur wire is fed above the argon blowing point, and titanium-iron cored wire is fed after an interval of 8-10 minutes, and then soft stirring is started, with a soft stirring time of ≥15 minutes; the furnace is kept under slight positive pressure during the refining process, and the nitrogen increase in the molten steel is controlled to ≤3 ppm after refining. 3) Continuous casting: The casting speed is controlled at 2.0-2.4 m / min, and the tundish superheat is controlled at 30-40℃. A carbon-free pre-melted high-basicity covering agent is added to the tundish. By mass percentage, the carbon-free pre-melted high-basicity covering agent contains CaO: 40%-55%, SiO2 < 6%, and Fe2O3 < 3%. The basicity of the protective slag is controlled at 0.82-0.90, and the viscosity is controlled at 1.0-1.1 Pa·s. By mass percentage, the protective slag composition is SiO2: 30%-32%, CaO: 25%-29%, MgO: 2.0%-2.5%, TiO2: 1%-3%, Fe2O3: 0.5%-1.0%, Al2O3: 5%-7%, free carbon (FC): 11%-13%, moisture ≤ 0.5%, and the balance being unavoidable impurities. Integral nozzle protection is used for casting, and the nitrogen absorption of molten steel is controlled to ≤ 3 ppm during the casting process.

2. The method for producing high-titanium sulfur-containing welding wire steel according to claim 1, characterized in that, After the steel is tapped from the converter and enters the argon station, pre-slag formation is carried out. The amount of calcium carbide added is 0.08-0.16 kg / t steel, and the amount of lime added is 0.8-1.6 kg / t steel.

3. The method for producing high-titanium sulfur-containing welding wire steel according to claim 1, characterized in that, During the refining process, the amount of lime added during slag formation and diffusion deoxidation is 4.2–5.8 kg / t steel, the amount of calcium carbide added is 0.5–0.58 kg / t steel, and the amount of fluorite added is 1.25–1.33 kg / t steel.

4. The method for producing high-titanium sulfur-containing welding wire steel according to claim 1, characterized in that, During the refining process, the alloying materials include low-aluminum ferrosilicon at a rate of 5–5.8 kg / t steel, high-silicon ferromanganese at a rate of 21.7–21.9 kg / t steel, low-carbon ferromanganese at a rate of 1.67–2 kg / t steel, and ferrotitanium-coated wire at a rate of 11.67–12.5 m / t steel.

5. The method for producing high-titanium sulfur-containing welding wire steel according to claim 1, characterized in that, During the refining process, after the first power supply, the amount of lime added is 5-5.8 kg / t steel, and the target temperature is 1580-1590℃; after the second power supply, the amount of ferrosilicon powder added is 0.17-0.25 kg / t steel, the amount of calcium carbide added is 0.17-0.25 kg / t steel, and the target temperature is 1610-1620℃.

6. The method for producing high-titanium sulfur-containing welding wire steel according to claim 1, characterized in that, During the refining process, the feeding speed of ferro-titanium cored wire and sulfur wire is controlled at 200-300 m / min, the amount of sulfur wire added is 0.83-1.25 m / t steel, and the bottom blowing flow rate during wire feeding is 100-200 NL, based on the creep of the slag surface.

7. The method for producing high-titanium sulfur-containing welding wire steel according to claim 1, characterized in that, The cross-sectional dimensions of the continuously cast billet are 140-160mm × 140-160mm.

8. The method for producing high-titanium sulfur-containing welding wire steel according to claim 1, characterized in that, By mass percentage, the chemical composition of the high-titanium sulfur-containing welding wire steel is: C: 0.040%–0.070%, Si: 0.75%–0.85%, Mn: 1.40%–1.55%, Ti: 0.15%–0.22%, Al: 0.005%–0.01%, P≤0.015%, S: 0.012%–0.018%, Ca≤0.0005%, N≤0.003%, with the remainder being Fe and other unavoidable impurities.

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