Cu-containing high-strength high-toughness welding steel wire rod and production method thereof

Abstract

The invention relates to the technical field of metallurgy, in particular to a Cu-containing high-strength high-toughness welding steel wire rod and a production method thereof, and the Cu-containing high-strength high-toughness welding steel wire rod comprises the following components in percentage by weight: 0.09-0.12% of C, 0.90-1.00% of Si, 1.65-1.75% of Mn, less than or equal to 0.010% of P, less than or equal to 0.010% of S, less than or equal to 0.10% of Cr, 0.80-1.10% of Ni, 0.40-0.60% of Cu, less than or equal to 0.05% of Mo, less than or equal to 0.01% of Ti, 0.03-0.08% of V, 0.003-0.006% of B, 0.05-0.08% of lanthanum, 0.05-0.09% of neodymium and the balance of Fe and inevitable impurities. According to the Cu-containing high-strength and high-toughness welding steel wire rod developed by the invention, various performance indexes of deposited metal meet the use requirements of users through welding performance tests, the replacement of import is realized, and the domestic blank is filled.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and in particular to a Cu-containing high-strength and high-toughness welding steel wire rod and a production method thereof. Background Art

[0002] The bogie is a key component of rail vehicles, bearing the operational loads of mounted components, as well as traction, braking, and inertia forces during operation. The bogie frame, the framework of the bogie and the foundation for mounting other components, connects the bogie components, transmits forces in all directions, and maintains the position of the axles within the bogie. The significantly increased dynamic loads borne by the bogie link frame place higher demands on the bogie material and its welding materials.

[0003] Current locomotive bogies typically utilize high-strength, high-toughness weathering steel, which offers excellent resistance to atmospheric corrosion and possesses excellent mechanical and weldability. Common materials for bogie welded frames include Q345E, S355, and SMA490 series steels. Weathering steel, also known as atmospheric corrosion-resistant steel, is produced by adding a certain amount of alloying elements, such as Cu, P, Cr, and Ni, to low-carbon steel. This enrichment of trace elements on the steel surface creates a dense, amorphous rust layer, improving its structure and density. This stabilized rust layer provides a degree of protection against the intrusion of harmful atmospheric ions and moisture, preventing further corrosion of the base metal. Among these elements, copper plays the greatest role, promoting the formation of a dense, amorphous corrosion product film on the surface of low-alloy steel, weakening the steel's anodic activity and thereby reducing the corrosion rate. However, during the hot rolling process, Cu-containing weathering steel exhibits severe cracking at the edges and corners of the steel. During hot rolling, steel corners experience the greatest deformation and residual stress. Furthermore, these corners cool first and faster than other parts, making it difficult to fully release the residual stress through recrystallization. In this situation, if there are factors that induce cracking in these corners, the steel is more likely to crack, affecting the final quality of the steel.

[0004] Weathering-resistant welding consumables for locomotive bogies include CHW-55CNH, G424M21Z, and TH550-NQ-Ⅱ. In recent years, with the continuous increase in train speeds in my country, higher requirements have been placed on the impact resistance of bogie welded structures. Actual use results show that due to the complex structure of bogie frames, unstable welding quality is a prominent issue, such as weld strength, low-temperature impact toughness, and porosity.

[0005] Cu-containing high-strength and high-toughness welding steel wire rod is primarily used to manufacture gas shielded welding wire for locomotive bogies. Due to the special operating conditions of this welding wire, the deposited metal impact strength must be ≥47J at -40°C. Therefore, there is an urgent need to produce qualified weather-resistant welding wire steel wire rod for rail transit bogies that meets the welding performance requirements of locomotive bogies and ensures that the deposited metal's mechanical, impact, and crack resistance properties meet standard requirements, thereby filling the domestic gap in related welding materials. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to propose a Cu-containing high-strength and high-toughness welding steel wire rod and its production method to meet the welding performance of railway locomotive bogies, and its deposited metal mechanical, impact and crack resistance meet the standard requirements, thereby replacing imports and filling the domestic gap in related welding materials.

[0007] Based on the above objectives, the present invention provides a Cu-containing high-strength and high-toughness welding steel wire rod, comprising the following components in weight percentage: C 0.09-0.12%, Si 0.90-1.00%, Mn 1.65-1.75%, P≤0.010%, S≤0.010%, Cr≤0.10%, Ni 0.80-1.10%, Cu 0.40-0.60%, Mo≤0.05%, Ti≤0.01%, V 0.03-0.08%, B 0.003-0.006%, lanthanum 0.05-0.08%, neodymium 0.05-0.09%, and the remainder being Fe and unavoidable impurities.

[0008] A method for producing a Cu-containing high-strength and high-toughness welding steel wire rod comprises the following steps: Chemical composition setting: The weather-resistant welding wire steel for rail locomotive bogies adopts a MnCu-based alloy system, with 0.80-1.10% Ni added for alloying. Currently, the company-standard weather-resistant welding wire steel for railway locomotives usually adopts a NiCrCu system, with a relatively low Ni content. Excessive Cu content is not conducive to surface quality control of billets and wire rods. However, due to the presence of 0.80-1.10% Ni, a NiCu-rich layer with a higher melting point is formed, which can prevent "Cu brittle" cracks on the product surface. In addition, this welding wire steel innovatively adds the metallic element vanadium, the non-metallic element boron, and the rare earth elements lanthanum and neodymium. Rare earth elements can effectively improve the product's resistance to atmospheric corrosion. Our independently developed welding wire steel for rail locomotive bogies has successfully eliminated the addition of Cr by optimizing the composition system. Not only does the mechanical properties of the weld metal, weld strength, low-temperature impact, and welding performance of the welding wire meet user requirements, but it also saves wire rod production costs.

[0009] The metallographic structure of the steel wire rod is ferrite and pearlite.

[0010] The method for producing Cu-containing high-strength and high-toughness welding steel wire rod adopts a one-fire material forming process, including the following steps: BOF converter → LF furnace refining → VD furnace degassing → continuous casting → steel billet windproof pile cooling → shot blasting + grinding → wire rolling → testing.

[0011] The BOF converter method adopts oxygen top-blown converter steelmaking method to make steel, controls the steel composition through the converter endpoint to be: C≤0.05%, P≤0.005%, and the steel tapping temperature≥1600°C; and performs deoxidation and alloying control and refining and slag making process control during steel tapping.

[0012] Through the double slag method smelting, the temperature is raised in advance to make slag, and light-burned dolomite is used in combination with calcium oxide to increase the slag basicity to 2.7. Pure aluminum is used for deep deoxidation during steelmaking, with a dosage of 1.0-2.0kg / t.

[0013] BOF smelting: Utilizing BOF smelting technology with narrow chemical composition control, steelmaking is performed using the top-blown oxygen converter method. Using Class A hot metal and nickel-containing pig iron as scrap, the addition of nickel-containing pig iron effectively reduces the amount of nickel added during the refining process, keeping the nickel-containing pig iron addition to 2.5 tons per furnace. Smelting is performed using the double-slag method. By raising the temperature early and slagging with light-burned dolomite and calcium oxide, the basicity of the slag is increased to 2.7. High-purity aluminum beans are used for deep deoxidation during tapping at a rate of 1.0-2.0 kg / t to reduce the oxygen content of the molten steel and increase alloy yield. Precise control of alloy additions allows for narrow chemical composition control. A sliding plate is used to block slag during tapping to prevent rephosphorization of the molten steel.

[0014] The slag-making material components added in the LF refining are 4-8 kg / t of lime and 0-3 kg / t of fluorite, so that the alkalinity is 2.0-5.0; the refining process uses calcium carbide and ferrosilicon powder in a weight percentage of 1:4-5 for diffusion deoxidation, and the total addition amount is 2.1-2.5 kg / t.

[0015] LF furnace refining: The LF furnace inlet temperature is raised to 1530°C. Our proprietary welding steel top slag process is employed, using 4-8 kg / t lime and 0-3 kg / t fluorite. White slag is produced, and the white slag time is ≥20 minutes. Nickel granules, copper nuggets, ferrovanadium, and rare earth alloys specifically designed for welding steel are added after the white slag. Manganese-ferroalloys are used to increase [Mn], while ferrosilicon alloys are used to increase Si. If the Cr content in the molten steel is insufficient, ferrochromium alloys can be added. Before soft blowing, low-aluminum titanium iron wire and ferroboron iron wire are fed simultaneously, as much as possible. The argon flow rate is adjusted to ensure slight fluctuations in the slag surface, and the molten steel must not be exposed. A carbon-free covering agent is added to the tundish for insulation. Carbonized rice hulls may be added depending on the condition of the slag surface, ensuring that the entire slag surface is covered and evenly distributed.

[0016] The VD furnace vacuum degassing controls the gas O in the steel to ≤30ppm and N to ≤60ppm, and the soft blowing time is ≥20 minutes. VD vacuum degassing is used to improve the purity of molten steel, controlling the gas [O] in the steel to ≤30ppm and [N] to ≤60ppm, and the inclusions of categories A, B, C, and D to ≤1.0.

[0017] Vacuum degassing in VD furnaces: Increase the vacuum level and vacuum time from 60 MPa to 70 MPa, and from 5 minutes to 8 minutes. Using high vacuum and extended vacuum time for degassing reduces O, N, and inclusions in the steel, improving molten steel purity. Adjust the argon flow rate to ensure slight fluctuations on the slag surface, preventing any exposed molten steel. Carbonized rice husks are added as a carbon-free covering agent to cover the entire slag surface and spread evenly. The soft blowing time must be ≥ 20 minutes.

[0018] The continuous casting adopts continuous casting and light pressure casting to cast the billet, and the casting process parameters are: superheat 25~35℃, pulling speed 2.3m / min, secondary cooling system 0.8~1.0L / kg, current intensity 300~400A, frequency 3~4Hz; end electromagnetic stirring parameters are: current intensity 250~300A, frequency 8~10Hz; the light pressure reduction amount is 3-4mm.

[0019] Continuous casting with light reduction casting: Protected casting is performed on a straight arc 160m³ Danieli continuous casting machine using a dynamic light reduction mold. The light reduction technique applies a certain pressure to the end of the liquid core of the continuous casting to reduce the thickness of the billet. This not only compensates for solidification shrinkage and eliminates central porosity, but also hinders the flow of concentrated molten steel caused by negative pressure, eliminating central segregation. Casting process parameters include a liquidus temperature of 1530°C, a superheat of 25-35°C, a casting speed of 2.3m / min, and a heavy reduction technique with a light reduction of 3-4mm. This effectively improves the internal quality of the billet and reduces inclusions and segregation. Low-magnification central porosity, central segregation, and shrinkage porosity are all ≤ 0.5.

[0020] During the pit cooling, the billet entering the pit has a temperature of 500-650°C; the pit cooling time is ≥48h, and the billet exiting the pit has a temperature ≤150°C.

[0021] The wire rod rolling parameters are as follows: furnace gas air-fuel ratio 0.54~0.64, soaking section temperature range 1100~1160℃, start rolling temperature 980~1050℃, finish rolling temperature 820~880℃, spinning temperature 800~830℃, insulation cover exit temperature 470~560℃, and coiling temperature 370~480℃.

[0022] The welding wire steel adopts the pioneering low-temperature low-roller rolling process. The rolling control method is low-temperature offline control. The roller speed is controlled at 0.1m / s~0.2m / s throughout the process. A thermal insulation cover is added throughout the process, and all fans of the air cooling line are turned off. This method can effectively reduce the tensile strength of the wire rod, increase the surface shrinkage of the wire rod, and thus improve the mechanical properties of the wire rod. After actual testing, the metallographic structure of the wire rod is uniform and no martensite is produced. Feedback from downstream customers shows that the welding wire drawing process is smooth and the processing and use performance is good.

[0023] The present invention has the following beneficial effects: Currently, companies typically use a two-fire electric furnace process for billet production. This invention utilizes a single-fire converter process for finished product, significantly reducing energy consumption and production steps. By adding metal, non-metallic, and rare earth elements, the welding wire's deposited metal properties and atmospheric corrosion resistance are successfully improved. Through rational smelting and rolling techniques, the Cu-containing high-strength, high-toughness welding steel wire rod developed has been shown to meet user requirements in welding performance testing, replacing imported steel and filling a domestic gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 1 is a comparison diagram of the pickling low magnification sample detection of Example 1 of the present invention and Comparative Example 1, wherein (a) is a detection diagram of the first stream pickling low magnification sample detection of Example 1, (b) is a detection diagram of the first stream pickling low magnification sample detection of Comparative Example 1, (c) is a detection diagram of the second stream pickling low magnification sample detection of Example 1, and (d) is a detection diagram of the second stream pickling low magnification sample detection of Comparative Example 1; Figure 2 1 is a schematic diagram of the metallographic structure of a comparative example magnified 500 times according to an embodiment of the present invention; Figure 3 Schematic diagram of the tensile strength curve of Example 1 of the present invention and the comparative example. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0027] It should be noted that, unless otherwise defined, technical or scientific terms used in the present invention should have the same ordinary meaning as those understood by persons of ordinary skill in the art to which the present invention belongs. Words such as "include" or "comprising" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, but do not exclude other elements or objects. Example 1

[0028] A Cu-containing high-strength and high-toughness welding steel wire rod, whose composition, in weight percentage, is: C 0.10%, Si 0.95%, Mn 1.70%, P≤0.010%, S≤0.010%, Cr≤0.10%, Ni 0.95%, Cu 0.50%, Mo≤0.05%, Ti≤0.01%. This weathering welding wire steel innovatively adds non-metallic elements and rare earth elements: V element range 0.05%, B element range 0.004%, lanthanum element range 0.06%, neodymium range 0.07%, and the rest is Fe and unavoidable impurities.

[0029] The method for producing Cu-containing high-strength and high-toughness welding steel wire rod of this embodiment comprises the following steps: Step S1, BOF steelmaking: steelmaking is performed using a top-blown oxygen furnace steelmaking process, with a MnNiCu main alloy system. Smelting is performed using a double-slag process, with the temperature raised in advance to form slag. Lightly burned dolomite and calcium oxide are used to form slag with a basicity increased to 2.7. The tapping composition is controlled by the converter endpoint to be: C ≤ 0.05%, P ≤ 0.005%, and the tapping temperature is ≥ 1600°C. Deoxidation and alloying control and refining and slag process control are performed during tapping. Pure aluminum is used for deep deoxidation during tapping at a dosage of 1.5 kg / t. Step S2, LF refining furnace: The LF refining furnace is heated to 1530°C. Slag-making material is then added. The slag-making material comprises 6 kg / t of lime and 2 kg / t of fluorite, so that the slag basicity R is 2.8. During the refining process, calcium carbide and ferrosilicon powder are diffused and deoxidized in a ratio of 1:5 by weight. The material is added to the slag surface in small amounts and multiple times, with a total addition amount of 2.5 kg / t. The target carbon content is ±0.01%, and the target Mn, Ni, and Cu content is ±0.02%. VD furnace degassing: Improve the original vacuum degree and vacuum time from 60MPa to 70MPa, and from 5 minutes to 8 minutes; VD furnace vacuum degassing controls the gas O≤30ppm and N≤60ppm in the steel, and the soft blowing time is 20 minutes.

[0030] Step S3, casting the ingot under light pressure: protective casting is performed using a straight arc 160 square Danieli continuous casting machine, and the casting process parameters are: superheat 35°C, casting speed 2.3m / min, secondary cooling system 1.0L / kg, current intensity 400A, frequency 4Hz, end electromagnetic stirring parameters are: current intensity 300A, frequency 9Hz; the light pressure reduction amount is 3.5mm.

[0031] Step S4, billet pit cooling: the billet entering the pit is at a temperature of 580°C; the pit cooling time is 48 hours, and the billet exiting the pit is at a temperature of 150°C. Hot billets are placed in the left and right stacks, top and bottom, in the pit. Step S5: Shot blasting and grinding the steel billet to remove defects such as cracks and scars on the steel billet surface corners; Step S6, wire rolling, the rolling control method is low-temperature offline control, the roller speed is controlled at 0.15 m / s throughout the process, and the rolling process parameters are: high-pressure water dephosphorization at 18 MPa, furnace gas air-fuel ratio of 0.58, soaking section temperature range of 1140°C to 1000°C, finishing rolling temperature of 850°C, spinning temperature of 815°C, insulation cover exit temperature of 515°C, and coiling temperature of 425°C; Step S7: Qualified products are put into storage. Example 2

[0032] A Cu-containing high-strength and high-toughness welding steel wire rod, whose composition, in weight percentage, is: C 0.09%, Si 0.90%, Mn 1.65%, P≤0.010%, S≤0.010%, Cr≤0.10%, Ni 0.80%, Cu 0.40%, Mo≤0.05%, Ti≤0.01%. This weathering welding wire steel innovatively adds non-metallic elements and rare earth elements: V element range 0.03%, B element range 0.003%, lanthanum element range 0.05%, neodymium range 0.05%, and the rest is Fe and unavoidable impurities.

[0033] The method for producing Cu-containing high-strength and high-toughness welding steel wire rod of this embodiment comprises the following steps: Step S1, BOF steelmaking: steelmaking is performed using a top-blown oxygen furnace steelmaking process, with a MnNiCu main alloy system. Smelting is performed using a double-slag process, with the temperature raised in advance to form slag. Lightly burned dolomite and calcium oxide are used to form slag with a basicity increased to 2.7. The tapping composition is controlled by the converter endpoint to be: C ≤ 0.05%, P ≤ 0.005%, and the tapping temperature is ≥ 1600°C. Deoxidation and alloying control and refining and slag process control are performed during tapping. Pure aluminum is used for deep deoxidation during tapping at a dosage of 1.0 kg / t. Step S2, LF refining furnace: The LF refining furnace is heated to 1550°C. Slag-making material is then added. The slag-making material comprises 4 kg / t of lime and 1 kg / t of fluorite, so that the slag basicity R is 2.1. During the refining process, calcium carbide and ferrosilicon powder are diffused and deoxidized in a ratio of 1:4 by weight. The material is added to the slag surface in small amounts and multiple times, with a total addition amount of 2.1 kg / t. The target carbon content is ±0.01%, and the target Mn, Ni, and Cu content is ±0.02%. VD furnace degassing: Improve the original vacuum degree and vacuum time, adjust from 60MPa to 70MPa, and adjust from 5 minutes to 8 minutes; VD furnace vacuum degassing controls the gas O≤30ppm, N≤60ppm in the steel, and the soft blowing time is 25 minutes.

[0034] Step S3, casting the ingot under light pressure: protective casting is performed using a straight arc 160 square Danieli continuous casting machine, and the casting process parameters are: superheat 30°C, casting speed 2.2m / min, secondary cooling system 0.8L / kg, current intensity 300A, frequency 3Hz, end electromagnetic stirring parameters are: current intensity 250A, frequency 8Hz; the light pressure reduction amount is 3mm.

[0035] Step S4, billet pit cooling: the billet entering the pit is at a temperature of 500°C; the pit cooling time is 52 hours, and the billet exiting the pit is at a temperature of 140°C. Hot billets are placed in the left and right stacks, top and bottom, in the pit. Step S5: Shot blasting and grinding the steel billet to remove defects such as cracks and scars on the steel billet surface corners; Step S6, wire rolling, the rolling control method is low-temperature offline control, the roller speed is controlled at 0.1 m / s throughout the process, and the rolling process parameters are: high-pressure water dephosphorization at 18 MPa, furnace gas air-fuel ratio of 0.54, soaking section temperature range of 1100°C to 980°C, finishing rolling temperature of 820°C, spinning temperature of 800°C, insulation cover exit temperature of 470°C, and coiling temperature of 380°C; Step S7: Qualified products are put into storage. Example 3

[0036] A Cu-containing high-strength and high-toughness welding steel wire rod, whose composition, in weight percentage, is: C 0.12%, Si 1.00%, Mn 1.75%, P≤0.010%, S≤0.010%, Cr≤0.10%, Ni 1.10%, Cu 0.60%, Mo≤0.05%, Ti≤0.01%. This weathering welding wire steel innovatively adds non-metallic elements and rare earth elements: V element range 0.08%, B element range 0.006%, lanthanum element range 0.08%, neodymium element range 0.08%, and the rest is Fe and unavoidable impurities.

[0037] The method for producing Cu-containing high-strength and high-toughness welding steel wire rod of this embodiment comprises the following steps: Step S1, BOF steelmaking: steelmaking is performed using a top-blown oxygen converter steelmaking process, with a MnNiCu main alloy system. Smelting is performed using a double-slag process, with the temperature raised in advance to form slag. Lightly burned dolomite and calcium oxide are used to form slag with a basicity increased to 2.7. The tapping composition is controlled by the converter endpoint to be: C ≤ 0.05%, P ≤ 0.005%, and the tapping temperature ≥ 1600°C. Deoxidation and alloying control and refining and slag process control are performed during tapping. Pure aluminum is used for deep deoxidation during tapping at a dosage of 2.0 kg / t. Step S2, LF refining furnace: The LF refining furnace is heated to 1540°C. Slag-making material is then added. The slag-making material comprises 8 kg / t of lime and 3 kg / t of fluorite, so that the slag basicity R is 3.0. During the refining process, calcium carbide and ferrosilicon powder are diffused and deoxidized in a ratio of 1:5 by weight. The material is added to the slag surface in small amounts and multiple times, with a total addition amount of 2.5 kg / t. The target carbon content is ±0.01%, and the target Mn, Ni, and Cu content is ±0.02%. VD furnace degassing: Improve the original vacuum degree and vacuum time, adjust from 60MPa to 70MPa, and adjust from 5 minutes to 8 minutes; VD furnace vacuum degassing controls the gas O≤30ppm, N≤60ppm in the steel, and the soft blowing time is 25 minutes.

[0038] Step S3, casting the ingot under light pressure: protective casting is performed using a straight arc 160 square Danieli continuous casting machine, and the casting process parameters are: superheat 33°C, casting speed 2.3m / min, secondary cooling system 1.0L / kg, current intensity 400A, frequency 4Hz, end electromagnetic stirring parameters are: current intensity 300A, frequency 10Hz; the light pressure reduction amount is 3.8mm.

[0039] Step S4, billet pit cooling: the billet entering the pit is at a temperature of 620°C; the pit cooling time is 55 hours, and the billet exiting the pit is at a temperature of 130°C. Hot billets are placed in the left, right, and upper and lower stacks in the pit. Step S5: Shot blasting and grinding the steel billet to remove defects such as cracks and scars on the steel billet surface corners; Step S6, wire rolling, the rolling control method is low-temperature offline control, the roller speed is controlled at 0.2 m / s throughout the process, and the rolling process parameters are: high-pressure water dephosphorization at 18 MPa, furnace gas air-fuel ratio of 0.62, soaking section temperature range of 1150°C and 1020°C, finishing rolling temperature of 870°C, spinning temperature of 820°C, insulation cover exit temperature of 530°C, and coiling temperature of 450°C; Step S7: Qualified products are put into storage.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that in step S1, the tapping composition is controlled to be: C: 0.06%, P: 0.006% through the converter endpoint, and the tapping temperature is 1550° C.; deoxidation and alloying control and refining and slag making process control are performed during tapping.

[0041] After the S2LF refining furnace enters the station, slag-making material is added. The components of the slag-making material are 8kg / t of lime and 5kg / t of fluorite, so that the slag has good fluidity and an alkalinity R of 2.0. The refining process uses calcium carbide and ferrosilicon powder in a weight percentage of 1:3 for diffusion deoxidation. Small amounts are added to the slag surface multiple times, with a total addition amount of 2.0kg / t. The C content target is ±0.01%, and the content of elements such as Mn, Ni, Cr, and Mo is targeted at ±0.02%.

[0042] Step S3, Soft Reduction Casting: The continuous casting machine was used to cast the slab. The casting parameters were: superheat 40°C, casting speed 2.5 m / s, secondary cooling rate 1.0 L / kg, current 400 A, frequency 4 Hz, and end-stage electromagnetic stirring parameters: current 300 A, frequency 9 Hz. The soft reduction depth was 3.5 mm. Soft reduction was not used.

[0043] Step S6, wire rolling, the rolling process parameters are: high-pressure water dephosphorization of 16 MPa, furnace gas air-fuel ratio of 0.50, soaking section temperature range of 1200°C, 1000°C, finishing rolling temperature of 950°C, spinning temperature of 850°C, heat preservation cover exit temperature of 580°C, and coiling temperature of 500°C; Effect comparison: Figure 1 The following are comparison diagrams of the pickling low magnification sample detection of Example 1 and Comparative Example 1 of the present invention, wherein (a) is the pickling low magnification sample detection diagram of the first stream of Example 1, (b) is the pickling low magnification sample detection diagram of the first stream of Comparative Example 1, (c) is the pickling low magnification sample detection diagram of the second stream of Example 1, and (d) is the pickling low magnification sample detection diagram of the second stream of Comparative Example 1. Figure 1 It can be explained that: the refining process in the steelmaking process increases the amount of slag, and the continuous casting adopts the light pressure technology, which can effectively eliminate the center segregation and center shrinkage of the steel billet. It is not difficult to find that the shrinkage cavity of the steel billet in the embodiment is significantly smaller than that of the comparative example. The shrinkage cavity of the steel billet will seriously affect the steel billet rolling process. The shrinkage cavity of the finished wire rod is too large. Due to the influence of the center tension, when the downstream customers process it, due to high-speed drawing, the core structure is hollow, and the broken wire affects the production rhythm. Therefore, the steel billet in Example 1 is significantly better than the comparative example.

[0044] Figure 2Example 1 of the present invention and a schematic diagram of the metallographic structure of comparative example 1 are magnified 500 times. By comparison, it is explained that the slag amount is increased during refining during steelmaking, the continuous casting adopts the light reduction technology, and the steel rolling adopts the low-temperature slow roller controlled rolling and cooling technology specially used for welding wire steel. It is not difficult to find that the metallographic structure in the embodiment is more uniform, which is ferrite and pearlite structure, while the structure in the comparative example is ferrite, pearlite and bainite structure; the presence of bainite is not conducive to the processing and drawing of downstream customers, and will increase the risk of wire breakage during customer drawing. There will be subsequent customer trial results.

[0045] Among them, the tensile strength of the same circle is extremely different. A whole circle is randomly selected and cut into 8 specimens for mechanical testing, and the difference between the highest tensile strength and the lowest tensile strength is obtained.

[0046] Table 1 Comparison of mechanical properties of the same ring in Examples 1-3 and Comparative Example

[0047] Figure 3 Example 1 of the present invention, a schematic diagram of the curve diagram of the same-circle mechanical project, is illustrated by comparison: the slag amount is increased during refining during steelmaking, the continuous casting adopts the light reduction technology, and the steel rolling adopts the low-temperature slow roller controlled rolling and controlled cooling technology specially used for welding wire steel. It is not difficult to find that the mechanical tensile strength of the same circle in the embodiment is lower, with an average tensile strength of 750 MPa, and the tensile strength of the control example is higher at 950 MPa. It can be seen that low-temperature slow roller rolling can significantly improve the mechanical properties of the wire rod in the same circle, and the lower tensile strength is more conducive to drawing processing, which can save the annealing cost for users.

[0048] The steel wire rods produced in Example 1 of the present invention and Comparative Example 1 were put into practical use and welding performance tests and evaluations were performed. The obtained usage data are shown in Table 2 below: Table 2 Comparison of application of examples and comparative examples

[0049] From the results in Table 2, it can be seen that the steel wire rod prepared by the present invention is easier to draw, is not prone to wire breakage, does not require an annealing process, and has good welding test evaluation and excellent low-temperature impact performance.

[0050] Those skilled in the art will understand that the discussion of any of the above embodiments is merely illustrative and is not intended to limit the scope of the present invention to these examples. Within the spirit and principles of the present invention, the technical features of the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and many other variations exist for the various aspects of the present invention described above, which are not provided in detail for the sake of clarity. Any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A Cu-containing high-strength and high-toughness welding steel wire rod, characterized in that: The invention comprises the following components in weight percentage: C 0.09-0.12%, Si 0.90-1.00%, Mn 1.65-1.75%, P≤0.010%, S≤0.010%, Cr≤0.10%, Ni 0.80-1.10%, Cu 0.40-0.60%, Mo≤0.05%, Ti≤0.01%, V 0.03-0.08%, B 0.003-0.006%, lanthanum 0.05-0.08%, neodymium 0.05-0.09%, and the rest is Fe and unavoidable impurities.

2. The Cu-containing high-strength and high-toughness welding steel wire rod according to claim 1, characterized in that: The metallographic structure of the steel wire rod is ferrite and pearlite.

3. The method for producing Cu-containing high-strength and high-toughness welding steel wire rod according to claim 1 or 2, characterized in that: The production method adopts a one-fire process, including the following steps: BOF converter → LF furnace refining → VD furnace degassing → continuous casting → billet windproof pile cooling → shot blasting + grinding → wire rolling → testing.

4. The method for producing Cu-containing high-strength and high-toughness welding steel wire rod according to claim 3, characterized in that: The BOF converter method adopts oxygen top-blown converter steelmaking method to make steel, controls the steel composition through the converter endpoint to be: C≤0.05%, P≤0.005%, and the steel tapping temperature≥1600°C; and performs deoxidation and alloying control and refining and slag making process control during steel tapping.

5. The method for producing Cu-containing high-strength and high-toughness welding steel wire rod according to claim 4, characterized in that: Through the double slag method smelting, the temperature is raised in advance to make slag, and light-burned dolomite is used in combination with calcium oxide to increase the slag basicity to 2.

7. Pure aluminum is used for deep deoxidation during steelmaking, with a dosage of 1.0-2.0kg / t.

6. The method for producing Cu-containing high-strength and high-toughness welding steel wire rod according to claim 3, characterized in that: The slag-making material components added in the LF furnace refining are 4-8 kg / t of lime and 0-3 kg / t of fluorite, so that the basicity is 2.0-5.0; the refining process uses calcium carbide and ferrosilicon powder in a weight percentage of 1:4-5 for diffusion deoxidation, and the total addition amount is 2.1-2.5 kg / t.

7. The method for producing Cu-containing high-strength and high-toughness welding steel wire rod according to claim 3, characterized in that: The VD furnace vacuum degassing controls the gas O in the steel to be ≤30ppm, N to be ≤60ppm, and the soft blowing time to be ≥20 minutes.

8. The method for producing Cu-containing high-strength and high-toughness welding steel wire rod according to claim 3, characterized in that: The continuous casting adopts continuous casting and light pressure casting to cast the billet, and the casting process parameters are: superheat 25~35℃, pulling speed 2.3m / min, secondary cooling system 0.8~1.0L / kg, current intensity 300~400A, frequency 3~4Hz; end electromagnetic stirring parameters are: current intensity 250~300A, frequency 8~10Hz; the light pressure reduction amount is 3-4mm.

9. The method for producing Cu-containing high-strength and high-toughness welding steel wire rod according to claim 3, characterized in that: The pit cooling is carried out such that the billet enters the pit at a temperature of 500-650°C; the pit cooling time is ≥48h, and the billet exits the pit at a temperature of ≤150°C.

10. The method for producing Cu-containing high-strength and high-toughness welding steel wire rod according to claim 3, characterized in that: The wire rod rolling parameters are as follows: furnace gas air-fuel ratio 0.54~0.64, soaking section temperature range 1100~1160℃, start rolling temperature 980~1050℃, finish rolling temperature 820~880℃, spinning temperature 800~830℃, insulation cover exit temperature 470~560℃, and coiling temperature 370~480℃.

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