A method for producing a high-strength low-residue alloy wire rod

Abstract

The application discloses a production method of high-strength low-slag alloy welding wire wire rod, the chemical composition of the wire rod is as follows: C=0.08%-0.12%, Si=0.03%-0.15%, Mn=1.40%-1.70%, P<=0.015%, S<=0.005%, Ti=0.06%-0.10%, Al<=0.010%, Ca<=0.0008%, As<=0.007%, O<=0.004%, N<=0.005%; the process route is as follows: hot metal pretreatment, converter smelting, LF furnace refining, 150mm square billet continuous casting, heating furnace, rolling, roller slow cooling and heat preservation passageway heat preservation. The molten steel obtained by the process of hot metal pretreatment, converter smelting and LF furnace external refining is stable in composition, good in castability and meets the requirement of gas content, the smelting process and rolling cooling process can prevent the wire rod from generating abnormal structures such as martensite and bainite which affect drawing, and the wire rod of the specification of Φ5.5mm high-strength alloy welding wire rod which can be drawn to Φ1.0mm without annealing is obtained.

Description

Technical Field

[0001] This invention belongs to the field of steel manufacturing technology and relates to a method for producing high-strength, low-slag alloy welding wire rods. Background Technology

[0002] With the widespread adoption of automated welding and robotic production lines, the slag produced by traditional welding wire has gradually evolved from a "tolerable byproduct" into a core bottleneck restricting continuous production. Welding slag not only interferes with the accurate tracking of sensors, forcing frequent production line shutdowns for cleaning, but also becomes a source of poor fusion in multi-layer welds and subsequent coating defects. Meanwhile, in high-end applications such as high-strength steel and marine engineering equipment, residual slag in welds directly affects the long-term service safety of structures, and the advancement of green manufacturing strategies requires reducing waste emissions and energy consumption at the source. It is precisely in this shift from a "passive slag removal" to a "proactive slag control" technological paradigm that low-slag welding wire has emerged, becoming a key breakthrough in solving process constraints and quality risks.

[0003] The development of low-slag welding wire has several advantages: First, it clears the way for intelligent production lines, enabling unmanned continuous operation by eliminating slag and unleashing the efficiency potential of automated equipment. Second, it fulfills the stringent requirements for green and low-carbon technologies, as self-protected low-slag welding wire reduces shielding gas consumption and solid waste, aligning with the concept of environmental protection throughout the entire life cycle. Third, it ensures the reliability of high-end equipment, as slag-free welds effectively prevent corrosion cracks caused by welding slag residue, meeting the extreme safety requirements of fields such as nuclear power and marine engineering. Fourth, it reshapes the cost structure for downstream users, offering a more advantageous overall manufacturing cost by eliminating slag removal processes, improving production line efficiency, and reducing rework rates. Summary of the Invention

[0004] The purpose of this invention is to provide a method for producing high-strength, low-slag alloy welding wire rods. The produced rods can be directly drawn into welding wires with a minimum diameter of 1.0 mm without annealing, while the tensile strength of the deposited metal is above 500 MPa. Furthermore, the produced welding wires produce less spatter and less slag during the welding process, eliminating the need for post-weld slag removal and greatly improving the production efficiency and appearance quality of the welding process.

[0005] The technical solution of this invention: A method for producing high-strength, low-slag alloy welding wire rod, wherein the chemical composition of the wire rod is C=0.08%~0.12%, Si=0.03%~0.15%, Mn=1.40%~1.70%, P≤0.015%, S≤0.005%, Ti=0.06%~0.10%, Al≤0.010%, Ca≤0.0008%, As≤0.007%, O≤0.004%, N≤0.005%, with the remainder being Fe and unavoidable impurities; the process route is hot metal pretreatment + converter smelting + LF ladle refining + 150mm square billet continuous casting + heating + rolling + roller table slow cooling, to obtain high-strength alloy welding wire rod with stable composition, good castability, and direct drawing to Φ1.0mm~Φ5.5mm specifications; the key process steps are as follows: 1) Hot metal pretreatment: The hot metal entering the furnace is pretreated and desulfurized using the KR method. After desulfurization, the desulfurization slag is completely removed. The sulfur content of the hot metal entering the furnace is controlled to be ≤0.020%, and the residual elements Cu ≤0.10% and As ≤0.007%. 2) Converter smelting: Endpoint control [O]≤450ppm, [C]≤0.06%, [P]≤0.008%, [S]≤0.015%; During tapping, add 200kg±5kg lime + 150kg±5kg low-Al synthetic slag for washing and argon blowing and stirring; Add low-nitrogen and low-aluminum micro-carbon ferromanganese alloy to the converter; 3) LF furnace refining: Lime and submerged arc slag are added during the refining process and then heated by electricity. During the power supply process, silicon powder is added according to the top slag condition for deoxidation. When the S content reaches the target, low-alumina ferrotitanium is added to adjust the titanium content. Throughout the refining process, the furnace cover is kept well sealed and low-blowing Ar gas is turned on. After the composition and temperature reach the target, Ar gas is kept in soft blowing for 15 minutes. 4) Continuous casting: Before casting, Ar gas is used to purge the tundish. The ladle is cast using an immersion long nozzle with a sealing ring and Ar gas ring on the nozzle for sealing. The tundish is cast using an integral nozzle. The superheat of the tundish is controlled at 20~30℃, the casting speed is 2.5~2.6m / min, the secondary cooling water volume is 0.5L / kg, and the electromagnetic stirring current of the crystallizer is 200A and the frequency is 3HZ. 5) Heating and rolling: Preheating section temperature ≤850℃, heating section temperature 1050~1100℃, soaking temperature 1080~1120℃, heating time 100~180min, furnace exit temperature 1050±20℃; high-pressure water descaling pressure 20~35Mpa, finishing mill entry temperature 850±20℃, sizing and reducing temperature 820±20℃, wire drawing temperature 800±10℃; 6) Roller slow cooling: The first of the air-cooled roller insulation covers is opened, and the rest are all closed; the roller speed is 0.10~0.18m / s; all roller cooling fans are closed, all dampers are closed, the gap between the insulation cover and each section of the roller is ≤5mm, and all gaps are covered with insulation material; the roller is preheated with slow-cooled steel for no less than 10 coils before rolling; the temperature of the steel exiting the insulation cover is 500~550℃; high-strength alloy welding wire rods that can be directly drawn to Φ1.0mm~Φ5.5mm specifications are obtained.

[0006] Through the above-mentioned process control, this invention can obtain high-strength alloy welding wire rods with stable composition, good castability, uniform coil strength (≤30MPa), and F+P microstructure. After being made into welding wire, the welding process produces less spatter and less slag, eliminating the need for post-weld slag removal and greatly improving the production efficiency and appearance quality of the welding process. Attached Figure Description

[0007] Figure 1 The metallographic structure of the wire rod in Example 1 (500×).

[0008] Figure 2 The metallographic structure of the wire rod in Example 2 (500×). Detailed Implementation Example 1

[0009] A method for producing high-strength, low-slag alloy welding wire rod involves pre-treating molten iron entering the converter. Before pre-treatment, the molten iron has a phosphorus content of 0.138%, a sulfur content of 0.039%, and an arsenic content of 0.006%. The method includes the following process steps: 1) Hot metal pretreatment: The hot metal entering the furnace is pretreated and desulfurized using the KR method. The sulfur content of the hot metal after pretreatment is 0.018%.

[0010] 2) Converter smelting: The endpoint is [O]=410ppm, [C]=0.05%, [P]=0.009%, [S]=0.018%, and the endpoint temperature is 1588℃. During the tapping process, 202kg of lime and 148kg of low-Al synthetic slag are added for washing, and argon blowing and stirring are carried out. Low-nitrogen and low-aluminum micro-carbon ferromanganese alloy is added. The slag thickness during the tapping process is ≤20mm.

[0011] 3) LF furnace refining: During the refining process, white slag is produced and ferrosilicon powder is sprinkled on the slag surface for deoxidation. The white slag is maintained for 20 minutes. The S content of the refining sample is 0.004%. Low-alumina ferrotitanium is added, and other components of the molten steel are adjusted. Calcium wire is strictly prohibited from being fed. Throughout the refining process, the furnace cover is kept well sealed and low-blowing Ar gas is turned on. After the composition and temperature reach the target, the soft blowing time is 16 minutes.

[0012] 4) Continuous casting: A high-basicity covering agent is used in the tundish, and a low-carbon protective slag is used in the crystallizer for casting protection. The superheat of the tundish is controlled at 28 degrees Celsius. The pouring speed is 2.5 m / min, the secondary cooling water volume is 0.5 L / kg, and the electromagnetic stirring current of the crystallizer is 200 A with a frequency of 3 Hz.

[0013] 5) Heating and rolling: The preheating section temperature of the heating furnace is 660-670℃, the heating section temperature is 1080-1090℃, the soaking temperature is 1100-1110℃, the heating time is 140min, and the furnace exit temperature is 1040-1050℃; the finishing mill entry temperature is 850-860℃, the sizing entry temperature is 820-830℃, and the wire drawing temperature is 800-810℃.

[0014] 6) Roller conveyor slow cooling: The first insulation cover of the air-cooled roller conveyor is opened, and all other insulation covers are closed. The roller conveyor speed is 0.10-0.18m / s, and the outlet temperature is 520-530 degrees.

[0015] The actual chemical composition control of the finished steel from this furnace is shown in Table 1, and the metallographic structure of the hot-rolled wire rod is shown in Table 2. Figure 1 The properties of the hot-rolled wire rod at both ends are shown in Table 2. Example 2

[0016] A method for producing high-strength, low-slag alloy welding wire rod involves pre-treating molten iron entering the converter. Before pre-treatment, the molten iron has a phosphorus content of 0.130%, a sulfur content of 0.036%, and an arsenic content of 0.006%. The method includes the following process steps: 1) Hot metal pretreatment: The hot metal entering the furnace is pretreated and desulfurized using the KR method. The sulfur content of the hot metal after pretreatment is 0.017%.

[0017] 2) Converter smelting: The endpoint of converter smelting is: oxygen content: 420ppm, [C]: 0.05%, [P]: 0.010%, [S]: 0.019%, endpoint temperature: 1595℃; during the tapping process, 201kg of lime and 150kg of low-Al synthetic slag are added for washing, and argon blowing and stirring are carried out. Low-nitrogen and low-aluminum micro-carbon ferromanganese alloy is added. The slag thickness during the tapping process is ≤20mm.

[0018] 3) LF furnace refining: During the refining process, white slag is produced and ferrosilicon powder is sprinkled on the slag surface for deoxidation. The white slag is maintained for 20 minutes. The S content of the refining sample is 0.003%. Low-alumina ferrotitanium is added, and other components of the molten steel are adjusted. Calcium wire is strictly prohibited from being fed. Throughout the refining process, the furnace cover is kept well sealed and low-blowing Ar gas is turned on. After the composition and temperature reach the target, the soft blowing time is 17 minutes.

[0019] 4) Continuous casting: A high-basicity covering agent is used in the tundish, and a low-carbon protective slag is used in the crystallizer for casting protection. The superheat of the tundish is controlled at 26 degrees Celsius. The pouring speed is 2.5 m / min, the secondary cooling water volume is 0.5 L / kg, and the electromagnetic stirring current of the crystallizer is 200 A with a frequency of 3 Hz.

[0020] 5) Heating and rolling: The preheating section temperature of the heating furnace is 660-670℃, the heating section temperature is 1090-1100℃, the soaking temperature is 1100-1110℃, the heating time is 135min, and the furnace exit temperature is 1040-1050℃; the finishing mill entry temperature is 850-860℃, the sizing entry temperature is 810-820℃, and the wire drawing temperature is 790-800℃.

[0021] 6) Roller conveyor slow cooling: The first insulation cover of the air-cooled roller conveyor is opened, and all other insulation covers are closed. The roller conveyor speed is 0.10-0.18m / s, and the outlet temperature is 510-520 degrees.

[0022] The actual chemical composition control of the finished steel from this furnace is shown in Table 1, and the metallographic structure of the hot-rolled wire rod is shown in Table 2. Figure 2 The properties of the beginning and end rings of hot-rolled wire rod are shown in Table 3.

[0023] Table 1. Chemical composition (wt%) of the wire rod produced in the examples. .

[0024] Table 2 Performance test results of the wire rod produced in Example 1 .

[0025] Table 3 Performance test results of the wire rod produced in Example 1 .

Claims

1. A method for producing high-strength, low-slag alloy welding wire rod, characterized in that: The chemical composition of the wire rod, by mass percentage, is C = 0.08%–0.12%, Si = 0.03%–0.15%, Mn = 1.40%–1.70%, P ≤ 0.015%, S ≤ 0.005%, Ti = 0.06%–0.10%, Al ≤ 0.010%, Ca ≤ 0.0008%, As ≤ 0.007%, O ≤ 0.004%, N ≤ 0.005%, with the remainder being Fe and unavoidable impurities. The key process steps are as follows: 1) Hot metal pretreatment: The hot metal entering the furnace is pretreated and desulfurized using the KR method. After desulfurization, the desulfurization slag is completely removed. The sulfur content of the hot metal entering the furnace is controlled to be ≤0.020%, and the residual elements Cu ≤0.10% and As ≤0.007%. 2) Converter smelting: Endpoint control [O]≤450ppm, [C]≤0.06%, [P]≤0.008%, [S]≤0.015%; During tapping, add 200kg±5kg lime + 150kg±5kg low-Al synthetic slag for washing and argon blowing and stirring; Add low-nitrogen and low-aluminum micro-carbon ferromanganese alloy to the converter; 3) LF furnace refining: Lime and submerged arc slag are added during the refining process and then heated by electricity. During the power supply process, silicon powder is added according to the top slag condition for deoxidation. When the S content reaches the target, low-alumina ferrotitanium is added to adjust the titanium content. Throughout the refining process, the furnace cover is kept well sealed and low-blowing Ar gas is turned on. After the composition and temperature reach the target, Ar gas is kept in soft blowing for 15 minutes. 4) Continuous casting: Before casting, Ar gas is used to purge the tundish. The ladle is cast using an immersion long nozzle with a sealing ring and Ar gas ring on the nozzle for sealing. The tundish is cast using an integral nozzle. The superheat of the tundish is controlled at 20~30℃, the casting speed is 2.5~2.6m / min, the secondary cooling water volume is 0.5L / kg, and the electromagnetic stirring current of the crystallizer is 200A and the frequency is 3HZ. 5) Heating and rolling: Preheating section temperature ≤850℃, heating section temperature 1050~1100℃, soaking temperature 1080~1120℃, heating time 100~180min, furnace exit temperature 1050±20℃; high-pressure water descaling pressure 20~35Mpa, finishing mill entry temperature 850±20℃, sizing and reducing temperature 820±20℃, wire drawing temperature 800±10℃; 6) Roller slow cooling: The first of the air-cooled roller insulation covers is opened, and the rest are all closed; the roller speed is 0.10~0.18m / s; all roller cooling fans are closed, all dampers are closed, the gap between the insulation cover and each section of the roller is ≤5mm, and all gaps are covered with insulation material; the roller is preheated with slow-cooled steel for no less than 10 coils before rolling; the temperature of the steel exiting the insulation cover is 500~550℃; high-strength alloy welding wire rods that can be directly drawn to Φ1.0mm~Φ5.5mm specifications are obtained.

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