A high-quality low-carbon and low-silicon hot-rolled wire rod for welding and its preparation method

Abstract

The present invention discloses a high-quality, low-carbon, low-silicon hot-rolled wire rod for welding and a preparation method thereof, relating to the technical field of welding wire steel. The chemical composition of the hot-rolled wire rod is, by mass percentage, as follows: C: 0.035% to 0.080%, Si≤0.030%, Mn: 0.42% to 0.55%, P≤0.012%, S≤0.012%, Cu≤0.20%, Ni≤0.30%, Cr≤0.20%, and the balance is Fe. The present invention optimizes the process flow of molten iron pretreatment, converter smelting, LF refining, and billet continuous casting, and strictly controls the P and S contents of the molten steel to ensure that the purity, O, and N contents of the wire rod meet standard requirements. The present invention formulates reasonable controlled rolling and controlled cooling processes and other means to ensure that the mechanical properties of the product meet user requirements, and that it has the characteristics of high elongation, easy drawing, and pickling-free drawing, thereby achieving the goals of energy saving and consumption reduction, reducing environmental pollution, and increasing product added value.

Description

Technical Field

[0001] The invention relates to the technical field of welding wire steel, and in particular to a high-quality low-carbon and low-silicon hot-rolled wire rod for welding and a preparation method thereof. Background Art

[0002] For a long time, welding materials have played an extremely important role in the national economic construction and have also played a vital role in production and life. With the continuous expansion of the application scope of automatic welding equipment in my country and the continuous improvement of welding automation level, the proportion of large components using submerged arc welding has increased year by year, and the demand for submerged arc welding wire has shown a clear upward trend.

[0003] Hot-rolled wire rod for welding is the primary raw material for submerged arc welding wire. It typically undergoes pickling, annealing, and multiple drawing passes before further processing. As the country's environmental protection requirements for businesses become increasingly stringent, welding wire steel manufacturers are increasingly using mechanical descaling instead of traditional pickling processes. The effectiveness of mechanical descaling depends largely on the stripping properties of the wire rod's scale. The better the stripping properties, the more thorough the descaling, and the better the surface quality of the semi-finished product after drawing. Furthermore, to improve production efficiency and reduce costs, welding wire manufacturers have imposed stricter requirements on wire breakage rates during drawing, the degree of spark spatter during welding, and the surface quality and strength of the weld seam. As a result, some common grades of welding wire steel available on the market are no longer able to meet user production needs. Therefore, focusing on key technical indicators such as high efficiency, high output, high welding performance, and pickling-free drawing, through precise control of the chemical composition of welding wire steel, controlled rolling, and delayed Stelmor cooling process after rolling, PF online slow cooling process and other measures, a high-quality welding wire steel with "low carbon, low silicon, low phosphorus, and low sulfur" composition characteristics, high elongation, easy drawing, annealing-free, and pickling-free is developed. This has important practical significance both in serving the national economic construction and in improving corporate profitability. Summary of the Invention

[0004] To solve the problems of the prior art, the present invention provides a high-quality low-carbon, low-silicon hot-rolled wire rod for welding and a preparation method thereof. By rationally controlling the content of elements such as carbon, silicon, phosphorus, sulfur, and nitrogen in the steel, the plasticity of the wire rod can be improved, and the strength and hardness of the weld can be increased. Therefore, the present invention develops a hot-rolled wire rod for welding having the composition characteristics of "low carbon, low silicon, low phosphorus, and low sulfur" and possessing the processing characteristics of "high elongation, easy drawing, and no pickling required". This can not only increase the added value of the product and create benefits for the enterprise, but also reduce environmental pollution and serve the national economic construction, which can be said to kill two birds with one stone. The present invention optimizes the processes such as composition design, molten iron pretreatment, converter smelting, LF refining, and rolling, so that the product can not only meet the low P and S requirements of steel for welding wire, but also has the characteristics of no pickling required and drawing required, thus saving energy and reducing consumption, reducing environmental pollution, increasing the added value of the product, and meeting the user's requirements for high efficiency, high output, and high welding performance of welding products.

[0005] The invention relates to a high-quality low-carbon and low-silicon hot-rolled wire rod for welding. The chemical composition and mass percentage of the wire rod are as follows: C: 0.035% to 0.080%, Si≤0.030%, Mn: 0.42% to 0.55%, P≤0.012%, S≤0.012%, Cu≤0.20%, Ni≤0.30%, Cr≤0.20%, and the balance is Fe.

[0006] Carbon significantly impacts the mechanical properties of steel. For hot-rolled wire rod for welding, increasing carbon content increases yield point and tensile strength, but reduces plasticity and impact toughness, leading to an increased tendency for weld cracking. Too low a carbon content can also lead to a softer wire and reduced weld strength. It can also cause a sharp increase in oxygen content in the molten steel, worsening the inclusion content and morphology, increasing hard phases in the steel, and causing pull-out fractures. Furthermore, it requires the addition of large amounts of alloying agents for deoxidation, increasing alloy consumption and driving up costs. Therefore, the carbon content in steel is controlled between 0.035% and 0.080%.

[0007] Silicon has a significant impact on the cold working properties of welding wire. When the silicon content in steel is high and fluctuates greatly, it can easily lead to low elongation and high wire breakage rate. Therefore, the silicon content in steel is controlled to ≤ 0.030%.

[0008] Manganese can increase the tensile strength of welds, improve plasticity and toughness, and eliminate the hot brittleness of steel. However, when the manganese content is too high, it will significantly increase the supercooling ability of austenite, which will increase the formation of cold cracks. Therefore, the manganese content in steel is controlled at 0.42% to 0.55%.

[0009] Phosphorus and sulfur are harmful impurities in steel. Phosphorus tends to segregate in steel, significantly reducing its plasticity and toughness and increasing its brittleness. Sulfur can easily cause hot brittleness in steel, reducing its ductility and toughness. Copper, nickel, and chromium are residual elements; the lower they are, the better, unless they cause other adverse effects. The patent for this invention requires that the wire rod contain P ≤ 0.012%, S ≤ 0.012%, Cu ≤ 0.20%, Ni ≤ 0.30%, and Cr ≤ 0.20%.

[0010] In order to ensure the purity of steel (high-quality low-carbon, low-silicon hot-rolled wire rod for welding), the oxygen content of the steel must be ≤100ppm and the nitrogen content must be ≤60ppm.

[0011] The preparation method of the above-mentioned high-quality low-carbon and low-silicon hot-rolled wire rod for welding comprises molten iron pretreatment → converter smelting → LF refining → argon blowing at an argon station → continuous casting → heating process → rolling process;

[0012] The converter smelting process involves smelting scrap steel and molten iron, with the scrap steel accounting for 12-15% by weight and the pretreated molten iron making up the remainder. The scrap steel is first loaded into an oxygen top-bottom double-blown converter, followed by the pretreated molten iron. The furnace is then shaken, and the lower oxygen lance begins to heat up. Lime, dolomite, limestone, and Australian ore are then added to form slag for phosphorus and carbon removal. The present invention uses Australian ore as a coolant instead of some scrap steel because it contains a higher oxygen content, leading to a more active carbon-oxygen reaction in the molten steel, which is beneficial for denitrification. Furthermore, the heat absorbed per unit of Australian ore is approximately three times that of scrap steel, but its price is lower than that of scrap steel, which can reduce production costs. Finally, Australian ore has a strong slagging effect, which is beneficial for dephosphorization and desulfurization. It is also necessary to ensure that the nitrogen content of scrap steel and auxiliary materials (lime, dolomite, limestone, Australian ore) used as raw materials into the furnace is controlled below 60ppm as much as possible, and reduce the nitrogen content brought into the furnace by the raw and auxiliary materials, including 24.0-30.0kg / t steel of lime, 8.0-12.0kg / t steel of dolomite, 23.0-28.0kg / t steel of limestone, and 15.0-18.0kg / t steel of Australian ore. When the smelting is approaching the end point, the gun position should be appropriately lowered and the stirring of the molten pool should be strengthened. The end point C should be controlled at 0.030%-0.045%, P≤0.012%, and end point O≤750ppm to ensure a successful one-time pouring. The end point temperature is 1620-1660℃, the ladle and alloy are fully baked, the ladle is pre-blown with argon for 2-3 minutes, argon is supplied throughout the tapping process, slag is blocked for tapping, slag is prevented, circular flow is used for tapping, and the molten steel is prohibited from flowing loosely. The tapping time is controlled at 5-6 minutes.

[0013] The heating process is as follows: the billet is hoisted into a walking beam heating furnace for heating, the time the billet spends in the furnace is reduced, the temperature of the soaking section is controlled below 1150°C, the amount of Fe2SiO4 generated is reduced, and the scale peeling performance is improved. Therefore, the preheating section is set at 900±30°C, the heating section at 1100±30°C, the soaking section at 1060±20°C, and the time in the furnace is set at 2.0±0.5h.

[0014] The rolling process is as follows: high-pressure water is applied to the square billet leaving the heating furnace to remove scale, and no visible residual iron oxide scale shall be left on the surface of the billet. The billet is sequentially sent to rough rolling → intermediate rolling → finishing rolling → wire laying → Stelmor air-cooling conveying line → coiling → PF conveying line for slow cooling to obtain the finished welding wire steel coil.

[0015] Based on the above technical solution, further, in the rolling process step, the water pressure of the high-pressure water is ≥14MPa.

[0016] Based on the above technical solution, further, in the rolling process steps, the rough rolling temperature is 960±20℃, the finishing rolling inlet temperature is 880±20℃, and the spinning temperature is 910±20℃; the head roller speed on the Stelmor air-cooled transport line is 0.25~0.30m / s, the temperature out of the insulation cover is lower than 600℃, the roller speed increase is 2~5%, only the first three groups of insulation covers and the last two groups of insulation covers are opened, and the remaining insulation covers are closed, and slow cooling is carried out in the range of 450~150℃ in the insulation channel.

[0017] Based on the above technical solution, further, the molten iron pretreatment is: sending the molten iron to the desulfurization station, spraying passivation magnesium powder and lime powder for pre-desulphurization, the magnesium powder dosage is 0.3~0.7kg / t molten iron, the lime powder dosage is 1.5~2.5kg / t molten iron, the treatment time is 20~25min, and after skimming, there is no slag layer on the surface of the molten iron, and then the molten iron is discharged from the station. After pre-desulfurization, the S of the molten iron is ≤0.008%, and the molten iron temperature is 1320~1350℃.

[0018] Based on the above technical solution, further, the argon blowing at the argon station is as follows: the ladle is sent into the argon station, the argon blowing time at the argon station is controlled at 7 to 12 minutes, the argon flow rate is controlled well, and the principle is that the steel liquid surface is not exposed; 300 to 500 m of aluminum wire is fed per furnace for deoxidation, and the temperature out of the argon station is 1590 to 1610°C.

[0019] Based on the above technical solution, further, the LF refining is as follows: the molten steel after leaving the argon station is sent to the LF furnace for refining, the LF arrival temperature is 1535~1575℃, the LF furnace cover is ensured to be in close contact with the ladle, a slightly positive pressure (10~20pa) is maintained in the furnace, submerged arc heating is used to prevent arc light from leaking out, and large argon blowing is prohibited during the process to prevent nitrogen absorption. Then, lime, carbide slag and other auxiliary materials are added to make white slag, and medium carbon ferromanganese, manganese silicon, ferrosilicon, aluminum particles and aluminum wire are added for deoxidation and adjustment of the composition. Among them, lime is 7.5-9.0kg / t steel, electric slag stone is 0.10-0.40kg / t steel, medium carbon ferromanganese is 2.5-3.5kg / t steel, manganese silicon is 1.3-2.3kg / t steel, ferrosilicon is 0-0.13kg / t steel, aluminum particles are 0.1-0.2kg / t steel, and aluminum wire is 0-50 meters / furnace. The soft blowing time is ≥10min to promote the floating of inclusions. After refining, the liquid surface is strictly prohibited from being exposed during the transfer of the ladle. Before the molten steel leaves the station, 100-150kg / furnace of carbonized rice husk is added for insulation and then transferred to the continuous casting process.

[0020] Based on the above technical solution, further, in the LF refining step, the alloy composition used is as shown in Table 1:

[0021] Table 1 Alloy composition

[0022]

[0023]

[0024] Based on the above technical solution, the continuous casting is further as follows: the refined molten steel is hoisted to the casting position, the superheat of the molten steel is controlled at 20-40°C, the electromagnetic stirring of the crystallizer and the end electromagnetic stirring are turned on, the constant pulling speed is 2.2m / min-2.8m / min, and the billet is cast.

[0025] Based on the above technical solution, further, in the continuous casting step, the crystallizer electromagnetic stirring current is 220-260A, the frequency is 4-6Hz, and the rotation is forward and reverse; the end electromagnetic stirring current is 230-270A, and the frequency is 4-8Hz.

[0026] Based on the above technical solution, further, in the continuous casting step, the size of the billet is 150 mm×150 mm.

[0027] The tensile strength of the high-quality low-carbon and low-silicon hot-rolled wire rod (steel) for welding is ≤380Mpa, the elongation after fracture is ≥30%, and the cross-sectional shrinkage is ≥65%.

[0028] The present invention can improve the plasticity of the wire rod and increase the strength and hardness of the weld by reasonably controlling the content of elements such as carbon, silicon, phosphorus, sulfur, and nitrogen in the steel. A hot-rolled wire rod for welding with the composition characteristics of "low carbon, low silicon, low phosphorus, and low sulfur" and the processing characteristics of "high elongation, easy drawing, and no pickling required" can not only enhance the added value of the product and create benefits for the enterprise, but also reduce environmental pollution and serve the national economic construction, which can be said to kill two birds with one stone.

[0029] The beneficial effects of the present invention are:

[0030] (1) The present invention optimizes the process flow of molten iron pretreatment, converter smelting, LF refining, and billet continuous casting, and strictly controls the P and S contents of molten steel to ensure that the purity, O, and N contents of the wire rod meet the standard requirements.

[0031] (2) Develop reasonable controlled rolling and controlled cooling processes to ensure that the mechanical properties of the product meet user requirements and have the characteristics of high elongation, easy drawing, and pickling-free drawing, so as to achieve the purpose of energy saving and consumption reduction, reduce environmental pollution, and increase product added value. DETAILED DESCRIPTION

[0032] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0033] Example 1

[0034] High-quality, low-carbon, low-silicon hot-rolled welding wire rod. Its chemical composition and weight percentages are: C: 0.037%, Si: 0.020%, Mn: 0.44%, P: 0.007%, S: 0.007%, Cu: 0.01%, Ni: 0.01%, Cr: 0.03%, and the balance is Fe. The steel has an oxygen content of 90 ppm and a nitrogen content of 18 ppm.

[0035] The method for preparing the high-quality low-carbon, low-silicon hot-rolled wire rod for welding comprises the following steps:

[0036] (1) Pretreatment of molten iron: The molten iron is sent to the desulfurization station and pre-desulphurized by spraying passivation magnesium powder and lime powder. The passivation magnesium powder is 0.36 kg / t and the lime powder is 2.12 kg / t. The treatment time is 22 min. After slag removal, there is no slag layer on the surface of the molten iron. The molten iron is then discharged from the station. After pre-desulphurization, the S content of the molten iron is 0.007% and the molten iron temperature is 1345°C.

[0037] (2) Converter smelting: First, 25.1 tons of scrap steel were loaded into an oxygen top-bottom double-blown converter, and then 150.8 tons of pre-treated molten iron was added. The furnace body was shaken, and the lower oxygen lance began to heat up. 25.0 kg / t of lime, 11.3 kg / t of dolomite, 23.6 kg / t of limestone and 15.5 kg / t of Australian ore were added in batches to carry out slag making, P removal and C removal operations. The end point carbon was 0.039%, phosphorus was 0.011%, and the end point oxygen was 661 ppm. The furnace was successfully poured once, and the end point temperature was 1626 ° C. The ladle and alloy were fully baked. The ladle was pre-blown with argon for 2 to 3 minutes. Argon was supplied during the whole tapping process. Slag was blocked during tapping to prevent slag from falling. The steel was tapped in a circular flow and the molten steel was prohibited from flowing loosely. The tapping time was controlled within 5 to 6 minutes.

[0038] (3) Argon blowing at the argon station: The ladle is sent to the argon station. The argon blowing time at the argon station is 7 minutes and 48 seconds. It is strictly forbidden to expose the molten steel surface. 469m / furnace aluminum wire is fed for deoxidation. The temperature out of the argon station is 1597℃.

[0039] (4) LF refining: The molten steel after leaving the argon station is sent to the LF furnace for refining. The temperature of the LF station is 1538℃. Ensure that the LF furnace cover is in close contact with the ladle. Maintain a slightly positive pressure in the furnace. Use submerged arc heating to prevent arc light leakage. During the process, do not blow large amounts of argon to prevent nitrogen absorption. Then add 8.53kg / t of white lime, 0.11kg / t of electroslag, 3.30kg / t of medium carbon ferromanganese, 1.36kg / t of manganese silicon, and 0.1kg / t of aluminum particles. The soft blowing time is 12 minutes to promote the floating of inclusions. After refining, the liquid surface must not be exposed during the transfer of the ladle. Before the molten steel leaves the station, add 100kg / furnace of carbonized rice husks for heat preservation and then enter the continuous casting process.

[0040] (5) Continuous casting: The refined molten steel was hoisted to the casting position, the superheat of the molten steel was controlled at 31°C, the electromagnetic stirring of the crystallizer was turned on at 240A, the frequency was 5Hz, the forward and reverse and end electromagnetic stirring currents were 250A, the frequency was 6Hz, the constant pulling speed was 2.8m / min, and the casting was carried out into 150mm×150mm square billets.

[0041] (6) Heating process: The billet is hoisted into a walking beam heating furnace for heating, with a preheating section of 890°C, a heating section of 1080°C, and a soaking section of 1050°C. The furnace time is 3 hours.

[0042] (7) Rolling process: The billets leaving the heating furnace are descaled with high-pressure water at a water pressure of 16 MPa. No visible residual iron oxide scale should remain on the surface of the billets. The billets are then sent to the rough rolling → intermediate rolling → finishing rolling → spinning → Stelmor air-cooled conveyor line → coiling → PF conveyor line for slow cooling to obtain finished welding wire steel wire rods. The rough rolling temperature is 940-980°C, the finishing rolling inlet temperature is 860-900°C, the spinning temperature is 890-930°C, and the roller speed is 0.25-0.30 m / s. The temperature out of the insulation cover is lower than 600°C, the roller speed is increased by 2-5%, and only the first three groups of insulation covers and the last two groups of insulation covers are opened. Slow cooling is carried out in the range of 450-150°C in the insulation channel.

[0043] Table 2 Mechanical properties test results

[0044] Example Tensile strength Mpa Elongation% Sectional shrinkage% 1 338 44.0 77 1 339 42.5 77

[0045] Example 2

[0046] High-quality, low-carbon, low-silicon hot-rolled welding wire rod. Its chemical composition and weight percentages are: C: 0.055%, Si: 0.018%, Mn: 0.46%, P: 0.004%, S: 0.007%, Cu: 0.004%, Ni: 0.009%, Cr: 0.02%, and the balance is Fe. The steel has an oxygen content of 75ppm and a nitrogen content of 43ppm.

[0047] The method for preparing the high-quality low-carbon, low-silicon hot-rolled wire rod for welding comprises the following steps:

[0048] (1) Pretreatment of molten iron: The molten iron is sent to the desulfurization station and pre-desulphurized by spraying passivation magnesium powder and lime powder. The passivation magnesium powder is 0.38 kg / t and the lime powder is 1.70 kg / t. The treatment time is 20 min. After slag removal, there is no slag layer on the surface of the molten iron. The molten iron is then discharged from the station. After pre-desulphurization, the S content of the molten iron is 0.012% and the molten iron temperature is 1345°C.

[0049] (2) Converter smelting: First, 22.5 tons of scrap steel are loaded into an oxygen top-bottom double-blown converter, and then 152.8 tons of pre-treated molten iron is added. The furnace body is shaken, and the lower oxygen lance begins to heat up. 29.7 kg / t of lime, 10.4 kg / t of dolomite, 28.0 kg / t of limestone and 15.8 kg / t of Australian ore are added in batches to carry out slagging, P removal and C removal operations. The end point carbon is 0.046%, phosphorus is 0.009%, and the end point oxygen is 620 ppm. Successful one-time pouring is guaranteed. The end point temperature is 1650℃. The ladle and alloy are fully baked. The ladle is pre-blown with argon for 2 to 3 minutes. Argon is supplied throughout the tapping process. Slag is blocked during tapping to prevent slag from falling. The steel is tapped in a circular flow and the molten steel is prohibited from flowing loosely. The tapping time is controlled within 5 to 6 minutes.

[0050] (3) Argon blowing at the argon station: The ladle is sent to the argon station. The argon blowing time at the argon station is 6 minutes and 0 seconds. It is strictly forbidden to expose the molten steel surface. 430m / furnace aluminum wire is fed for deoxidation. The temperature out of the argon station is 1595℃.

[0051] (4) LF refining: The molten steel after leaving the argon station is sent to the LF furnace for refining. The temperature of the LF station is 1547℃. Ensure that the LF furnace cover is in close contact with the ladle. Maintain a slightly positive pressure in the furnace. Use submerged arc heating to prevent arc light leakage. During the process, do not blow large amounts of argon to prevent nitrogen absorption. Then add 8.55kg / t of white lime, 0.40kg / t of electroslag, 2.91kg / t of medium carbon ferromanganese, 1.60kg / t of manganese silicon, and 0.2kg / t of aluminum particles. The soft blowing time is 22 minutes to promote the floating of inclusions. After refining, the liquid surface must not be exposed during the transfer of the ladle. Before the molten steel leaves the station, add 100kg / furnace of carbonized rice husks for heat preservation and then enter the continuous casting process.

[0052] (5) Continuous casting: The refined molten steel was hoisted to the casting position, the superheat of the molten steel was controlled at 39 °C, the electromagnetic stirring of the crystallizer was turned on at 240A, the frequency was 5Hz, the forward and reverse and end electromagnetic stirring currents were 250A, the frequency was 6Hz, the constant pulling speed was 2.3m / min, and the casting was carried out into 150mm×150mm square billets.

[0053] (6) Heating process: The billet is hoisted into a walking beam heating furnace for heating, with a preheating section of 890°C, a heating section of 1080°C, and a soaking section of 1050°C. The furnace time is 3 hours.

[0054] (7) Rolling process: The billets leaving the heating furnace are descaled with high-pressure water at a water pressure of 16 MPa. No visible residual iron oxide scale should remain on the surface of the billets. The billets are then sent to the rough rolling → intermediate rolling → finishing rolling → spinning → Stelmor air-cooled conveyor line → coiling → PF conveyor line for slow cooling to obtain finished welding wire steel wire rods. The rough rolling temperature is 940-980°C, the finishing rolling inlet temperature is 860-900°C, and the spinning temperature is 890-930°C. The temperature out of the insulation cover is lower than 600°C, the roller speed is increased by 2-5%, and only the first three groups of insulation covers and the last two groups of insulation covers are opened. Slow cooling is carried out in the range of 450-150°C in the insulation channel.

[0055] Table 3 Mechanical properties test results

[0056] Example Tensile strength Mpa Elongation% Sectional shrinkage% 2 330 43 77 2 333 43.5 76

Claims

1. A high-quality low-carbon, low-silicon hot-rolled wire rod for welding, characterized in that: The chemical composition of the hot-rolled wire rod is as follows by mass percentage: C: 0.037% to 0.080%, Si≤0.030%, Mn: 0.42% to 0.55%, P≤0.012%, S≤0.012%, Cu≤0.20%, Ni≤0.30%, Cr≤0.20%, and the balance is Fe; The preparation method of the hot-rolled wire rod comprises molten iron pretreatment → converter smelting → LF refining → argon blowing in an argon station → continuous casting → heating process → rolling process; The converter smelting comprises the following steps: using scrap steel and molten iron as raw materials for smelting, wherein the weight percentage of scrap steel is 12-15%, and the pretreated molten iron is the balance; first, the scrap steel is loaded into an oxygen top-bottom double-blown converter, and then the pretreated molten iron is added, the furnace body is shaken, and then lime, dolomite, limestone, and Australian ore are added to make slag, and P and C removal operations are performed, with the end point C controlled at 0.030%-0.045%, P≤0.012%, end point O≤750ppm, and end point temperature at 1620-1660°C; wherein, the amount of lime used is 24.0-30.0kg / t steel, the amount of dolomite used is 8.0-12.0kg / t steel, the amount of limestone used is 23.0-28.0kg / t steel, and the amount of Australian ore used is 15.0-18.0kg / t steel; The heating process is as follows: the continuous casting billet is hoisted into a walking beam heating furnace for heating, with a preheating section at 950±20°C, a heating section at 1120±20°C, a soaking section at 1100±20°C, and a furnace time of 2.0±0.5h; The rolling process is as follows: the continuous casting billet coming out of the heating furnace is subjected to high-pressure water descaling, and is sequentially sent to rough rolling → intermediate rolling → finishing rolling → spinning → Stelmor air-cooling conveying line → coiling → PF conveying line for slow cooling to obtain the finished welding wire steel wire rod; In the rolling process steps, the rough rolling temperature is 960±20℃; the finishing rolling entrance temperature is 880±20℃; the spinning temperature is 910±20℃; the roller speed of the Stelmor air-cooled transport line is 0.25~0.30m / s, the temperature out of the insulation cover is lower than 600℃, the roller speed increase is 2~5%, only the first three groups of insulation covers and the last two groups of insulation covers are opened, and the other insulation covers are closed, and slow cooling is carried out in the range of 450~150℃ in the insulation channel.

2. The hot rolled wire rod according to claim 1, characterized in that The oxygen content of the hot-rolled wire rod is ≤100 ppm, and the nitrogen content is ≤60 ppm.

3. The hot rolled wire rod according to claim 1, characterized in that The hot-rolled wire rod has a tensile strength of ≤380 MPa, an elongation after fracture of ≥30%, and a cross-sectional shrinkage of ≥65%.

4. The hot rolled wire rod according to claim 1, characterized in that The molten iron pretreatment comprises: sending the molten iron to a desulfurization station, spraying passivation magnesium powder and lime powder for pre-desulfurization, wherein the molten iron S after pre-desulfurization is less than or equal to 0.012%, and the molten iron temperature is 1320-1350° C., wherein the amount of magnesium powder is 0.3-0.7 kg / t molten iron, the amount of lime powder is 1.5-2.5 kg / t molten iron, and the treatment time is 20-25 minutes; The argon station blows argon: the ladle is sent to the argon station, the argon blowing time of the argon station is controlled at 7-12 minutes, the argon flow rate is 25-40m3 / h; 300-500m of aluminum wire is fed / furnace for deoxidation, and the temperature out of the argon station is 1590-1610℃.

5. The hot rolled wire rod according to claim 1, characterized in that The LF refining comprises the following steps: feeding the molten steel after leaving the argon station into the LF furnace for refining; the LF arrival temperature is 1535-1575° C.; maintaining a slightly positive pressure in the furnace of 10-20 Pa; adopting submerged arc heating; then adding lime and carbide slag as auxiliary materials to make white slag; adding medium carbon ferromanganese, manganese silicon, ferrosilicon, aluminum particles, and aluminum wire; and soft blowing for 10 minutes or longer; and adding 100-150 kg / furnace of carbonized rice husk for heat preservation before the molten steel leaves the station; wherein, the amount of lime is 9.5-10.5 kg / t steel, the amount of electroslag is 0.10-0.40 kg / t steel, the amount of medium carbon ferromanganese is 3.4-4.4 kg / t steel, the amount of manganese silicon is 1.5-2.5 kg / t steel, the amount of ferrosilicon is 0-0.13 kg / t steel, the amount of aluminum particles is 0.1-0.2 kg / t steel, and 0-50 m / furnace of aluminum wire is fed; The continuous casting comprises the following steps: hoisting the refined molten steel to the casting position, controlling the superheat of the molten steel at 20-40° C., turning on the electromagnetic stirring of the crystallizer and the end electromagnetic stirring, and casting the billet at a constant pulling speed of 2.2 m / min-2.8 m / min.

6. The hot rolled wire rod according to claim 1, characterized in that In the converter smelting step, argon is pre-blown in the ladle for 2 to 3 minutes, argon is supplied throughout the steel tapping process, and the steel tapping time is controlled within 5 to 6 minutes.

7. The hot rolled wire rod according to claim 1, characterized in that In the LF refining step, the composition of the medium carbon ferromanganese is as follows: Mn: 75-82%, C≤2.0%, Si≤2.5%, P≤0.33%, S≤0.03%, and the balance is Fe; The composition of manganese silicon, calculated by mass percentage, is: Mn ≥ 60%, Si ≥ 12%, C ≤ 3%, Fe 20%; The composition of ferrosilicon, calculated by mass percentage, is as follows: Si: 72-80%, C≤0.02%, Mn:≤0.05%, P≤0.04%, S≤0.02%, and the balance is Fe; During the continuous casting step, the crystallizer electromagnetic stirring current is 220-260A, the frequency is 4-6Hz, and the rotation is forward and reverse; the end electromagnetic stirring current is 230-270A, and the frequency is 4-8Hz; The size of the billet is 150mm×150mm.

8. The hot rolled wire rod according to claim 1, characterized in that In the rolling process, the water pressure is ≥14 MPa.

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