A low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod and its production method

Abstract

This invention relates to a low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod and its production method. The chemical composition of the rod, by mass percentage, is: C: 0.080%–0.110%, Si: 0.80%–1.10%, Mn: 1.60%–1.80%, P≤0.020%, S: 0.006%–0.018%, Ca≤0.0010%, Al≤0.015%, Cr≤0.15%, Ni≤0.15%, Cu≤0.20%, with the remainder being Fe and unavoidable impurities. By employing a "low-aluminum, low-calcium, controlled-sulfur" composition design, combined with a "controlled rolling and cooling + insulated channel slow cooling" production process, the produced G4Si1 gas-shielded welding wire rod meets the requirements for mechanical properties, drawing performance, welding performance, and user application. The G4Si1 gas-shielded welding wire exhibits less spatter and fewer porosity defects during use.

Description

Technical Field

[0001] This invention relates to the field of wire rod production technology, and in particular to a low-aluminum, low-calcium controlled-sulfur gas shielded welding wire for manufacturing G4Si1 welding wire and its production method. Background Technology

[0002] Gas metal arc welding (GMAW) wire is filler metal used in MIG / MAG welding. The wire melts with an electric arc to form a weld with the base metal. Based on material type, it is classified into carbon steel and low alloy steel welding wire, stainless steel welding wire, aluminum and aluminum alloy welding wire, nickel-based alloy welding wire, etc.

[0003] G4Si1 welding wire is a common type of welding wire used in gas metal arc welding. It belongs to the silicon-manganese alloy system and is suitable for welding low-carbon steel and low-alloy steel such as Q235 and Q345 (16Mn). It has good welding performance and mechanical properties and is widely used in industries such as steel structure, automobile manufacturing, engineering machinery, bridge, and pressure vessel manufacturing.

[0004] G4Si1 gas-shielded welding wire is mainly used for welding high-quality carbon steel and low-alloy high-strength steel. The tensile strength of its weld metal is required to reach more than 500MPa, and it has good toughness. At the same time, the welding wire has the advantages of less spatter, stable arc and good weld formation during the welding process.

[0005] Currently, there are still some problems with gas shielded welding wire in practical applications. For example, there is severe metal spatter during the welding process, which is related not only to the shielding gas ratio and welding parameters, but also directly to the composition of the welding wire. Another problem is porosity (including hydrogen porosity and nitrogen porosity) and slag inclusions. If the molten steel used to manufacture the wire rod contains too much aluminum, it is easy to react with oxygen in the air to generate Al2O3. During continuous casting, this can easily cause turbulence. When welding, the welding wire made from this wire has a strong affinity between Al and O, which leads to a decrease in the partial pressure of oxygen and an increase in the partial pressure of hydrogen in the weld pool, resulting in the formation of hydrogen porosity. Summary of the Invention

[0006] This invention provides a low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod and its production method. The rod adopts a "low-aluminum, low-calcium, controlled-sulfur" composition design and is combined with a "controlled rolling and cooling + heat preservation channel slow cooling" production process. The produced G4Si1 gas-shielded welding wire rod can meet the mechanical properties, drawing properties, welding properties and user requirements. The G4Si1 gas-shielded welding wire has less spatter and fewer porosity defects during use.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod has the following chemical composition by mass percentage: C: 0.080%–0.110%, Si: 0.80%–1.10%, Mn: 1.60%–1.80%, P≤0.020%, S: 0.006%–0.018%, Ca≤0.0010%, Al≤0.015%, Cr≤0.15%, Ni≤0.15%, Cu≤0.20%, with the remainder being Fe and unavoidable impurities.

[0009] The finished wire rod has a ferrite + pearlite structure, with ferrite accounting for 85% to 90% and pearlite accounting for 10% to 15% by volume.

[0010] The finished properties of the wire rod are: tensile strength 530-560 MPa, elongation after fracture 28%-33%, and reduction of area 74%-81%.

[0011] A method for producing low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod includes the following steps:

[0012] 1) KR molten iron pretreatment: Desulfurizing agent is injected into the molten iron ladle for desulfurization. After pretreatment, the S mass content in the molten iron is ≤0.005%, and the slag is removed.

[0013] 2) Converter smelting: A top-and-bottom blown converter is used for smelting. The purity of the top-blown oxygen is >99.6%, and the oxygen pressure is 1.1-1.3 MPa. Argon is supplied for the bottom-and-bottom blown converter, and the argon pressure is 1.1-1.3 MPa. The tapping temperature is 1595-1650℃. The final tapping concentration is C≤0.05% and P≤0.012% by mass percentage. Slag feeding is strictly prohibited, and spot blowing should be avoided.

[0014] 3) Steel ladle alloying: Alloying is carried out 2 minutes after tapping the steel, and the argon blowing time is ≥5 minutes; 27.02~27.76 kg / t steel of active lime and 10.2~10.8 kg / t steel of dolomite are added; in addition, 24.5~25.5 kg / t steel of silicon-manganese alloy is added.

[0015] 4) Static argon blowing: Argon blowing time ≥ 5 min; molten steel temperature after treatment is 1560℃~1570℃;

[0016] 5) LF furnace refining: Maintain a slight positive pressure of 40-70 kPa inside the furnace, employ submerged arc heating, and ensure no arc leakage; add 5.3-5.6 kg / t steel of active lime, 0.80-1.20 kg / t steel of fluorite, 0.45-0.50 kg / t steel of calcium carbide slag, and 0.30-0.34 kg / t steel of ferrosilicon powder; form a reducing slag with a basicity R=CaO / SiO2=1.0-1.5; after deoxidation, fine-tune silicon and manganese content by adding 4.65-5.35 kg / t steel of low-aluminum ferrosilicon, 2.5-3.5 kg / t steel of medium-carbon ferromanganese, and 0.2-0.3 kg / t steel of carbon raiser; soft blowing time ≥15 min; LF furnace temperature at the station 1575℃-1590℃;

[0017] 6) Continuous casting: A full-process protective casting process is adopted. Before casting begins, the tundish is cleaned with argon gas for ≥2 minutes. The crystallizer electromagnetic stirring adopts a continuous stirring mode with an electromagnetic stirring current of 230-270A and a frequency of 2-4Hz. The end electromagnetic stirring adopts an alternating forward and reverse stirring mode with an electromagnetic stirring current of 300-340A and a frequency of 6-10Hz. Low-carbon or carbon-free covering agent is used in the tundish, and calcium wire is prohibited. Low-carbon protective slag for billets is used in the crystallizer. The platform ladle temperature is 1573±5℃, the tundish temperature is 1530℃-1550℃, the superheat is maintained at 25℃-35℃, and the casting speed is 2.0-2.4m / min, a constant casting speed. The billet is placed in the insulation pit for slow cooling for more than 48 hours after leaving the line.

[0018] 7) Heating: A walking beam furnace is used for heating. The preheating section temperature is 880±20℃, the heating section temperature is 1100±20℃, the soaking section temperature is 1110±20℃, and the total heating time is 1.5~2.5h.

[0019] 8) Rolling, wire drawing, and cooling: Roughing mill temperature: 980±20℃; Finishing mill inlet temperature: 900±20℃; Inlet temperature of the reducing and sizing mill: 880±20℃; Wire drawing temperature: 880±20℃; Air-cooled roller speed: Head roller speed 0.15~0.20m / s, roller speed increase set at 2%~5% increments; First half insulation cover closed, second half insulation cover open; Fans all off; The opening degree of the cooling device throughout the entire process is 20%~30%;

[0020] 9) Slow cooling in the insulation channel: The rolled wire rod is slowly cooled in the insulation channel on the Stellmore slow cooling line, and the temperature of the insulation channel is ≥60℃.

[0021] In step 1), during converter smelting, the proportion of molten iron is 85% to 88% by weight, and the proportion of scrap steel is 12% to 15%.

[0022] In step 3), low-aluminum ferrosilicon and low-carbon ferromanganese are used for alloying treatment.

[0023] In step 4), the argon gas is first blown strongly for 2-3 minutes, then blown weakly; the strong argon gas flow rate is 780-820 m³ / min. 3 / h, the weak blowing argon flow rate is 95~105m³ / h. 3 / h.

[0024] In step 5), the added low-aluminum ferrosilicon is FeSi75Al0.5-A, and by mass percentage, the aluminum content in FeSi75Al0.5-A is <0.5% and the calcium content is <1%.

[0025] A typical production process route is as follows: blast furnace hot metal → KR desulfurization pretreatment → 100t converter smelting → LF furnace refining → 150mm×150mm eight-strand square billet continuous casting → regenerative walking beam heating furnace heating → high-pressure water descaling → rough rolling → intermediate rolling → pre-finish rolling → finish rolling → sizing → wire drawing → air cooling → coiling → slow cooling in the insulation channel of the Steyrmo slow cooling line.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1) Adopting a composition design of "low aluminum, low calcium and controlled sulfur", combined with the production process of "controlled rolling and controlled cooling + heat preservation channel slow cooling", the produced G4Si1 gas shielded welding wire rod can meet the mechanical properties, drawing performance, welding performance and user requirements. G4Si1 gas shielded welding wire has less spatter and fewer porosity defects when used.

[0028] 2) The refining process adopts a different process from conventional refining. It fully considers the effects of reducing slag basicity, slag quantity, reducing atmosphere, and argon blowing and stirring on desulfurization, and accurately controls the S content in the molten steel. Under the premise of ensuring that O in the steel is ≤50ppm, the S content is controlled within the range of 0.006% to 0.018%, which meets the user's strict requirements for the S content of wire rod and ensures that the welding wire products can meet the welding performance requirements of end users.

[0029] 3) To reduce spatter generated during welding, the present invention controls the calcium content throughout the steelmaking process; by analyzing the sources of calcium in the molten steel, it is required that materials with high aluminum and calcium content be strictly prohibited from being used for deoxidation, slag formation, alloying, etc. during the converter tapping and LF furnace refining processes. For example, low-aluminum ferrosilicon FeSi75Al0.5-A (aluminum content <0.5%, calcium content <1%) is used instead of ordinary ferrosilicon (aluminum and calcium content are not required) for alloying; no calcium treatment is performed in the LF refining furnace.

[0030] 4) When making white slag in the LF furnace, ferrosilicon powder is used for deoxidation to avoid using aluminum-containing deoxidizers that increase Al2O3 inclusions in the steel, ensuring that the Al content in the wire rod steel for G4Si1 welding wire is controlled within 0.010%; the inclusions such as Al2O3 in the molten steel are effectively controlled, improving the castability of the molten steel.

[0031] 5) A combination of "Stelmore controlled rolling and cooling process + PF line slow cooling process" is adopted (the PF line is a key piece of equipment in the finishing area of ​​the high-speed wire rod production line and an important link in the steel rolling production line. It is mainly used for the coils to be collected on the coiler, and the coil turning machine turns the coils from vertical to horizontal. The coil transport trolley transports the loose coils and hooks them onto the C-shaped hooks in the waiting position. During the operation, the temperature of the loose coils slowly decreases as they pass through the cooling area of ​​the PF line. The cooling area is equipped with inspection, head and tail cutting, and sampling operation stations. When the carrier trolley carrying the loose coils passes through the cooling area, each coil undergoes appearance inspection, dimensional inspection, and trimming, and batch sampling inspection is also carried out). This strictly controls the metallographic structure of the wire rod and ensures that the tensile strength of the wire rod is less than 560MPa, which is convenient for downstream users to carry out drawing production. Attached Figure Description

[0032] Figure 1 This is a metallographic photograph of the low-aluminum, low-calcium controlled sulfur gas shielded welding wire rod described in this invention. Detailed Implementation

[0033] The present invention discloses a low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod. The chemical composition of the rod, by mass percentage, is: C: 0.080%–0.110%, Si: 0.80%–1.10%, Mn: 1.60%–1.80%, P≤0.020%, S: 0.006%–0.018%, Ca≤0.0010%, Al≤0.015%, Cr≤0.15%, Ni≤0.15%, Cu≤0.20%, with the remainder being Fe and unavoidable impurities. The rationale for this composition design is as follows:

[0034] While carbon (C) can improve the yield strength and tensile strength of welds, it is detrimental to toughness and increases the weld's susceptibility to cold cracking. This invention controls the C content to be between 0.080% and 0.110%.

[0035] Mn and Si: Alloying elements Mn and Si are important strengthening elements in steel. Their strengthening effect mainly comes from solid solution strengthening and microstructure strengthening. In addition, during welding, Mn and Si are important deoxidizers in the weld pool, preventing porosity and suppressing spatter. If the added Mn and Si content is properly matched (e.g., Mn / Si ratio of 3–6), it can also reduce the inclusion content in the weld, resulting in a high level of strength and toughness. Therefore, this invention controls Si to 0.80%–1.10% and Mn to 1.60%–1.80%.

[0036] P: P can strengthen weld metal, but it is detrimental to the low-temperature toughness of steel. Therefore, the P content in this invention is controlled below 0.020%.

[0037] Sulfur (S): As a harmful element, controlling its content can improve the purity of the weld and the welding performance of the welding wire. This invention controls S content to be 0.006%–0.018%.

[0038] Ca: By controlling the Ca content, spatter during welding can be prevented. This invention controls Ca to be ≤0.0010%.

[0039] Al: Excessive aluminum content in molten steel easily reacts with oxygen in the air to form Al2O3, which can cause turbulence during continuous casting. During welding, Al has a strong affinity for O, which lowers the oxygen partial pressure and increases the hydrogen partial pressure in the weld pool, resulting in hydrogen porosity. In this invention, aluminum is strictly controlled as a harmful element, requiring Al ≤ 0.015%.

[0040] The production method of low-aluminum, low-calcium controlled sulfur gas shielded welding wire rod of the present invention has the following typical production process route: blast furnace hot metal → KR desulfurization pretreatment → 100t converter smelting → LF furnace refining → 150mm×150mm eight-strand square billet continuous casting → regenerative walking beam heating furnace heating → high-pressure water descaling → rough rolling → intermediate rolling → pre-finish rolling → finish rolling → sizing → wire drawing → air cooling → coiling → slow cooling in the insulation channel of the Steyrmo slow cooling line.

[0041] It must be emphasized that the use of aluminum-containing steel ladles or calcium-treated steel ladles is strictly prohibited during the steelmaking process; the use of materials with high aluminum or calcium content for deoxidation, slag formation, alloying, or other treatments is strictly prohibited.

[0042] The production method of low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod according to the present invention includes the following specific steps:

[0043] 1. KR molten iron pretreatment: Desulfurizing agent (preferably 90% lime powder + 10% fluorite powder) is injected into the molten iron ladle for desulfurization. After treatment, the S content in the molten iron should be ≤0.005%, and the slag should be removed.

[0044] 2. Converter Smelting: The preferred hot metal weight ratio is 85%–88%, and the scrap steel weight ratio is 12%–15%. A top-and-bottom blowing converter is used for smelting. Top-blown oxygen purity > 99.6%, oxygen pressure 1.1–1.3 MPa; Argon gas is supplied for the second blowing, argon pressure 1.1–1.3 MPa; tapping temperature is 1595–1650℃, with a final tapping carbon content of C ≤ 0.05% and a final powder content of P ≤ 0.012%. Slag addition is strictly prohibited, and spot blowing should be avoided. Ensure the final carbon content and temperature are achieved on the first attempt. If secondary spot blowing occurs, the hood must be lowered first, and a circular flow tapping method should be adopted to avoid nitrogen absorption.

[0045] 3. Steel ladle alloying: 2 minutes after tapping, alloying treatment is performed using low-aluminum ferrosilicon and low-carbon ferromanganese, with argon blowing time ≥ 5 minutes. Auxiliary materials include 27.02–27.76 kg / t steel of active lime and 10.2–10.8 kg / t steel of dolomite; target alloy addition amount: 24.5–25.5 kg / t steel of high-silicon ferromanganese.

[0046] 4. Static Argon Blowing: Argon blowing time ≥ 5 minutes, first strong blowing for 3 minutes, then weak blowing; strong blowing argon flow rate is 780~820m³ / h. 3 / h, the weak blowing argon flow rate is 95~105m³ / h. 3 / h. The temperature of the molten steel after treatment is 1560℃~1570℃.

[0047] 5. LF Furnace Refining: Maintain a slight positive pressure (40-70 kPa) inside the furnace, employing submerged arc heating to prevent arc leakage. Add 5.3-5.6 kg / t steel of active lime, 0.80-1.20 kg / t steel of fluorite, 0.45-0.50 kg / t calcium carbide slag, and 0.30-0.34 kg / t steel of ferrosilicon powder; the active lime should be added in batches and evenly in the early stages of refining, and its addition in the later stages is strictly prohibited. Use ferrosilicon powder and calcium carbide for diffusion deoxidation in the slag to create a reducing slag (basicity R = CaO / SiO2 = 1.0-1.5). Silicon and manganese fine-tuning is carried out after deoxidation. 4.65–5.35 kg / t of low-aluminum ferrosilicon (preferably FeSi75Al0.5-A, with aluminum content <0.5% and calcium content <1%), 2.5–3.5 kg / t of medium-carbon ferromanganese, and 0.2–0.3 kg / t of carburizer (preferably petroleum coke carburizer) are added. When the process sulfur content is low, sulfur adjustment is performed using sulfur-treated iron wire after power supply is completed; soft blowing time is ≥15 min. The LF furnace temperature at the station is 1575℃–1590℃.

[0048] 6. Continuous Casting: To ensure billet quality, defects such as carbon center segregation, central porosity, or shrinkage cavities in the billet are avoided by controlling the superheat of the molten steel, the casting speed, and employing electromagnetic stirring in the continuous casting mold and at the end of the casting process. A full-process protective casting process is adopted. Before casting begins, the tundish is cleaned with argon gas for at least 2 minutes. The electromagnetic stirring current in the mold is 230–270 A, the frequency is 2–4 Hz, and continuous stirring is performed. The end electromagnetic stirring current is 300–340 A, the frequency is 6–10 Hz, and alternating forward and reverse stirring is performed (preferably with a time interval of 8s–3s–8s). Low-carbon or carbon-free covering agents are used in the tundish; the addition of calcium wire is prohibited. Low-carbon protective slag from square billets is used as the mold flux. The platform ladle temperature is 1573±5℃, the tundish temperature is 1530℃–1550℃, the superheat is maintained at 25℃–35℃, and the casting speed is controlled at 2.0–2.4 m / min, using a constant casting speed to reduce liquid level fluctuations. The steel billets are placed in an insulated pit for slow cooling for more than 48 hours after they come off the production line.

[0049] 7. Heating: A walking beam furnace is used for heating. The preheating section temperature is 880±20℃, the heating section temperature is 1100±20℃, the soaking section temperature is 1110±20℃, and the total heating time is 1.5~2.5h.

[0050] 8. Rolling, Wire Output, and Cooling: Roughing mill inlet temperature is 980±20℃; Finishing mill inlet temperature is 900±20℃; Inlet temperature of the reducing and sizing mill is 880±20℃; Wire output temperature is 880±20℃; Air-cooled roller speed: Head roller speed 0.15~0.20m / s, roller speed increase set at 2%~5% increments. The insulation cover is closed for the first half of the process and opened for the second half (e.g., insulation covers 1#-20# are closed, insulation covers 21#-22# are open); all fans are off; the opening degree of the Jialing device is 20~30% for the entire process (e.g., 1#-25#).

[0051] 9. Slow cooling in the insulation channel: The insulation channel is used for slow cooling. The temperature of the insulation channel is ≥60℃ to ensure the effective release of structural stress and internal stress, thereby ensuring the performance requirements of the finished product and the welding wire.

[0052] The finished wire rod has a ferrite + pearlite microstructure, with ferrite accounting for 85%–90% and pearlite accounting for 10%–15% by volume. The finished wire rod has a tensile strength of 530–560 MPa, an elongation after fracture of 28%–33%, and a reduction of area of ​​74%–81%. A metallographic photograph of the wire rod for low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire is shown below. Figure 1 As shown.

[0053] The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0054] Example:

[0055] This embodiment uses the production method described in this invention to manufacture G4Si1 wire rod for low-aluminum and low-calcium gas-shielded welding wire. The chemical composition of the steel in each embodiment is shown in Table 1. The converter smelting process, ladle alloying and static argon blowing parameters in each embodiment are shown in Table 2. The LF furnace refining and continuous casting process parameters in each embodiment are shown in Table 3. The rolling and cooling process parameters in each embodiment are shown in Table 4. The low-magnification defect inspection results of the billet in each embodiment are shown in Table 5. The mechanical properties of the finished product in each embodiment are shown in Table 6. The microstructure and non-metallic inclusion inspection results of the finished product in each embodiment are shown in Table 7.

[0056] Table 1 Chemical composition of steel (mass percentage, %)

[0057]

[0058] Table 2 Process parameters for converter smelting, ladle alloying, and static argon blowing.

[0059]

[0060] Table 3. LF Furnace Refining and Continuous Casting Process Parameters

[0061]

[0062] Table 4 Rolling and Cooling Process Parameters

[0063]

[0064] Table 5. Results of Low-Magnification Defect Inspection of Cast Billets (Grade)

[0065]

[0066] Table 6 Mechanical Properties of Finished Products

[0067]

[0068] Table 7. Inspection results of microstructure and non-metallic inclusions of the finished product.

[0069]

[0070] 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 low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod, characterized in that, The chemical composition of the wire rod, by mass percentage, is: C: 0.080%–0.110%, Si: 0.80%–1.10%, Mn: 1.60%–1.80%, P≤0.020%, S: 0.006%–0.018%, Ca≤0.0010%, Al≤0.015%, Cr≤0.15%, Ni≤0.15%, Cu≤0.20%, with the remainder being Fe and unavoidable impurities. The finished wire rod has a ferrite + pearlite microstructure, with ferrite accounting for 85%–90% and pearlite accounting for 10%–15% by volume. The finished wire rod has the following properties: tensile strength 530–560 MPa, elongation after fracture 28%–33%, and reduction of area 74%–81%.

2. A method for producing low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod as described in claim 1, characterized in that, Includes the following steps: 1) KR molten iron pretreatment: Desulfurizing agent is injected into the molten iron ladle for desulfurization. After pretreatment, the S mass content in the molten iron is ≤0.005%, and the slag is removed. 2) Converter smelting: A top-and-bottom blown converter is used for smelting. The purity of the top-blown oxygen is >99.6%, and the oxygen pressure is 1.1-1.3 MPa. Argon is supplied for the bottom-and-bottom blown converter, and the argon pressure is 1.1-1.3 MPa. The tapping temperature is 1595-1650℃. The final tapping concentration is C≤0.05% and P≤0.012% by mass percentage. Slag feeding is strictly prohibited, and spot blowing should be avoided. 3) Steel ladle alloying: Alloying is carried out 2 minutes after tapping the steel, and the argon blowing time is ≥5 minutes; 27.02~27.76 kg / t steel of active lime and 10.2~10.8 kg / t steel of dolomite are added; in addition, 24.5~25.5 kg / t steel of silicon-manganese alloy is added. 4) Static argon blowing: Argon blowing time ≥ 5 min; molten steel temperature after treatment is 1560℃~1570℃; 5) LF furnace refining: Maintain a slight positive pressure of 40-70 kPa inside the furnace, employ submerged arc heating, and ensure no arc leakage; add 5.3-5.6 kg / t steel of active lime, 0.80-1.20 kg / t steel of fluorite, 0.45-0.50 kg / t steel of calcium carbide slag, and 0.30-0.34 kg / t steel of ferrosilicon powder; form a reducing slag with a basicity R=CaO / SiO2=1.0-1.5; after deoxidation, fine-tune silicon and manganese content by adding 4.65-5.35 kg / t steel of low-aluminum ferrosilicon, 2.5-3.5 kg / t steel of medium-carbon ferromanganese, and 0.2-0.3 kg / t steel of carbon raiser; soft blowing time ≥15 min; LF furnace temperature at the station 1575℃-1590℃; 6) Continuous casting: A full-process protective casting process is adopted. Before casting begins, the tundish is cleaned with argon gas for ≥2 minutes. The crystallizer electromagnetic stirring adopts a continuous stirring mode with an electromagnetic stirring current of 230-270A and a frequency of 2-4Hz. The end electromagnetic stirring adopts an alternating forward and reverse stirring mode with an electromagnetic stirring current of 300-340A and a frequency of 6-10Hz. Low-carbon or carbon-free covering agent is used in the tundish, and calcium wire is prohibited. Low-carbon protective slag for billets is used in the crystallizer. The platform ladle temperature is 1573±5℃, the tundish temperature is 1530℃-1550℃, the superheat is maintained at 25℃-35℃, and the casting speed is 2.0-2.4m / min, a constant casting speed. The billet is placed in the insulation pit for slow cooling for more than 48 hours after leaving the line. 7) Heating: A walking beam furnace is used for heating. The preheating section temperature is 880±20℃, the heating section temperature is 1100±20℃, the soaking section temperature is 1110±20℃, and the total heating time is 1.5~2.5h. 8) Rolling, wire drawing, and cooling: Roughing mill temperature: 980±20℃; Finishing mill inlet temperature: 900±20℃; Inlet temperature of the reducing and sizing mill: 880±20℃; Wire drawing temperature: 880±20℃; Air-cooled roller speed: Head roller speed 0.15~0.20m / s, roller speed increase set at 2%~5% increments; First half insulation cover closed, second half insulation cover open; Fans all off; The opening degree of the cooling device throughout the entire process is 20%~30%; 9) Slow cooling in the insulation channel: The rolled wire rod is slowly cooled in the insulation channel on the Stellmore slow cooling line, and the temperature of the insulation channel is ≥60℃.

3. The method for producing low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod according to claim 2, characterized in that, In step 1), during converter smelting, the proportion of molten iron is 85% to 88% by weight, and the proportion of scrap steel is 12% to 15%.

4. The method for producing low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod according to claim 2, characterized in that, In step 3), low-aluminum ferrosilicon and low-carbon ferromanganese are used for alloying treatment.

5. The method for producing low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod according to claim 2, characterized in that, In step 4), the argon gas is first blown strongly for 2-3 minutes, then blown weakly; the strong argon gas flow rate is 780-820 m³ / min. 3 / h, the weak blowing argon flow rate is 95~105m³ / h. 3 / h.

6. The method for producing low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod according to claim 2, characterized in that, In step 5), the added low-aluminum ferrosilicon is FeSi75Al0.5-A, and by mass percentage, the aluminum content in FeSi75Al0.5-A is <0.5% and the calcium content is <1%.

7. The method for producing low-aluminum, low-calcium controlled-sulfur gas-shielded welding wire rod according to claim 2, characterized in that, A typical production process route is as follows: blast furnace hot metal → KR desulfurization pretreatment → 100t converter smelting → LF furnace refining → 150mm×150mm eight-strand square billet continuous casting → regenerative walking beam heating furnace heating → high-pressure water descaling → rough rolling → intermediate rolling → pre-finish rolling → finish rolling → sizing → wire drawing → air cooling → coiling → slow cooling in the insulation channel of the Steyrmo slow cooling line.

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