80 kg welding wire wire rod and production method thereof

Abstract

The present application provides a wire rod for an 80 kg welding wire and a production method thereof, wherein the wire rod comprises C: 0.13-0.15%, Si: 0.60-0.80%, Mn: 1.80-2.10%, P≤0.012%, S: 0.008-0.013%, Al≤0.008%, N: 0.004-0.007%, Ti: 0.16-0.21%, Cr: 0.90-1.20%, B: 0 .0050~0.0070%, V: 0.08~0.11%, and the rest are Fe and impurities; in the production method, the finishing rolling entrance temperature is 830~850℃, the rolling speed is 90~100m / s, and the spinning temperature is 790~810℃; during cooling, the cooling rate is ≤0.5℃ / s, and the final cooling temperature is ≤530℃; in the insulation process, the insulation time is ≥40min, and the temperature of the wire rod at the end of insulation is ≤300℃.

Description

Technical Field

[0001] The present application relates to the technical field of metal smelting, and in particular to a wire rod for 80 kg welding wire and a production method thereof. Background Art

[0002] With the continuous development of the coal mining machinery industry, the materials and welding materials used in coal mining machinery and engineering machinery are also constantly updated and improved. Steel materials with high strength, high toughness and good crack resistance have been widely used in the coal mining machinery industry, replacing the previous bulky hydraulic supports and wooden supports. Engineering machinery generally requires -40℃ low temperature impact performance, while the coal mining machinery industry requires -20℃ low temperature impact performance. This means that the coal mining machinery industry has relatively low performance requirements for welding materials, but still needs to have certain low temperature impact performance. In coal mining machinery and engineering machinery, the composition system of 80 kg supporting welding materials is usually similar, and both require the addition of expensive nickel and molybdenum elements, and cooperate with the annealing process to achieve high strength and high toughness requirements, but it will increase production costs. Summary of the invention

[0003] The purpose of the present application is to provide an 80 kg grade wire rod for welding wire and a production method thereof, to control the rolling temperature and speed, to improve the structural uniformity of the wire rod, to prevent the transformation of austenite into martensite through cooling and heat preservation and to affect the drawing of the wire rod into welding wire, thereby solving the problem in the prior art that expensive alloys are added to the wire rod used to produce welding wire and that annealing is required, which leads to an increase in production costs.

[0004] In order to achieve one of the above-mentioned invention purposes, an embodiment of the present application provides a method for producing a wire rod for an 80 kg-grade welding wire, wherein the chemical composition of the wire rod comprises, by weight percentage: C: 0.13-0.15%, Si: 0.60-0.80%, Mn: 1.80-2.10%, P≤0.012%, S: 0.008-0.013%, Al≤0.008%, N: 0.004-0.007%, Ti: 0.16-0.21%, Cr: 0.90-1.20%, B: 0.0050-0.0070%, V: 0.08-0.11%, and the rest is Fe and unavoidable impurities;

[0005] The production method of the wire rod comprises subjecting a steel billet having the chemical composition as described above to heating, rolling, cooling and heat preservation steps to obtain the wire rod, wherein:

[0006] In the rolling process, the steel billet is fed into the rolling mill for rolling to obtain the wire rod, wherein the finishing rolling inlet temperature is 830-850°C, the rolling speed is 90-100 m / s, and the wire laying temperature is 790-810°C;

[0007] In the cooling process, the cooling rate of the wire rod is controlled to be ≤0.5℃ / s, and the final cooling temperature of the wire rod is ≤530℃;

[0008] In the insulation process, the insulation time of the wire rod is ≥40min, and the temperature of the wire rod at the end of insulation is ≤300℃.

[0009] As a further improvement of an implementation mode of the present application, in the heating process, the steel billet is sent to a heating furnace for heating, the temperature of the soaking section of the heating furnace is 1110-1140° C., and the time in the furnace is 80-90 minutes.

[0010] As a further improvement of one embodiment of the present application, in the cooling process, the wire rod is placed on a roller, and the roller is evenly divided into multiple sections along its length direction, and the roller speed of the entrance section is 0.19~0.25m / s, and the speed of each section is increased by 3% thereafter.

[0011] As a further improvement of an embodiment of the present application, before the heating process, the process further includes steelmaking, continuous casting and blanking processes performed in sequence, wherein:

[0012] In the blanking process, the continuous casting blank obtained by continuous casting is first sent to a heating furnace for heating, and then the continuous casting blank is blanked and rolled. The temperature of the heating furnace's soaking section is 1200~1230℃, and the blanking temperature is 1060~1080℃.

[0013] As a further improvement of an embodiment of the present application, the steelmaking process includes converter smelting, LF refining and RH vacuum refining processes performed in sequence. In the converter smelting process, the iron-water ratio is ≥75%, the P content of the molten iron when entering the furnace is ≤0.1%, the converter steel tapping slag basicity is controlled to be 1.7-2.3, the converter steel tapping temperature is ≥1610°C, and the S content of the steel tapping is ≤0.005%;

[0014] In the LF refining process, calcium carbide is used to diffuse deoxidize the slag and feed it into the sulfur line according to the sampling test results to ensure that the S content meets the requirements of the wire rod composition;

[0015] In the RH vacuum refining process, deep vacuum degassing is performed for 15 to 20 minutes, and after the vacuum degree is less than 2 mbar, titanium-iron alloy is added for alloying.

[0016] As a further improvement of one embodiment of the present application, in the continuous casting process, the superheat is 36~39°C, the pulling speed is 0.60~0.64m / s, the crystallizer water flow rate is 2820~2880L / min, and the crystallizer electromagnetic stirring current is 700A.

[0017] An embodiment of the present application further provides a wire rod, wherein the volume proportion of ferrite is ≥10%, the grain size of ferrite is ≥8 levels, and the volume proportion of martensite-austenite structure is ≤5%.

[0018] As a further improvement of an embodiment of the present application, its chemical composition, in weight percentage, includes: C: 0.13~0.15%, Si: 0.60~0.80%, Mn: 1.80~2.10%, P≤0.012%, S: 0.008~0.013%, Al≤0.008%, N: 0.004~0.007%, Ti: 0.16~0.21%, Cr: 0.90~1.20%, B: 0.0050~0.0070%, V: 0.08~0.11%, and the rest is Fe and unavoidable impurities.

[0019] As a further improvement of one embodiment of the present application, the tensile strength of the wire rod is 750~800MPa, and the cross-sectional shrinkage rate is ≥75%.

[0020] As a further improvement of one embodiment of the present application, the wire rod is drawn at a drawing speed ≤ 10 m / s to obtain a welding wire, the welding wire is used to carry out a deposited metal test, preheating before welding and insulation after welding are carried out during welding, and the tensile strength of the deposited metal weld is ≥ 800 MPa, and the low-temperature impact toughness of -20°C is ≥ 80 J.

[0021] One or more technical solutions provided by this application have at least the following technical effects or advantages:

[0022] In the production method of the 80 kg welding wire wire provided in the present application, the rolling temperature and speed are controlled, and a lower rolling speed is adopted to make the wire rod structure more uniform. A lower cooling speed is adopted during cooling to avoid the generation of harmful structures, and during heat preservation, austenite is allowed to have a long enough time to transform into bainite and ferrite that are beneficial to wire rod drawing, while austenite is prevented from having too little time for phase transformation to form martensite-austenite (MA) structure that is not conducive to wire rod drawing. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The embodiment of the present application provides a method for producing a wire rod, wherein the chemical composition of the wire rod includes, by weight percentage: C: 0.13-0.15%, Si: 0.60-0.80%, Mn: 1.80-2.10%, P≤0.012%, S: 0.008-0.013%, Al≤0.008%, N: 0.004-0.007%, Ti: 0.16-0.21%, Cr: 0.90-1.20%, B: 0.0050-0.0070%, V: 0.08-0.11%, and the rest is Fe and unavoidable impurities;

[0025] The production method of the wire rod comprises subjecting a steel billet having the chemical composition as described above to heating, rolling, cooling and heat preservation steps to obtain the wire rod, wherein:

[0026] In the rolling process, the steel billet is fed into the rolling mill for rolling to obtain the wire rod, wherein the finishing rolling inlet temperature is 830-850°C, the rolling speed is 90-100 m / s, and the wire laying temperature is 790-810°C;

[0027] In the cooling process, the cooling rate of the wire rod is controlled to be ≤0.5℃ / s, and the final cooling temperature of the wire rod is ≤530℃;

[0028] In the insulation process, the insulation time of the wire rod is ≥40min, and the temperature of the wire rod at the end of insulation is ≤300℃.

[0029] In the present application, the strength of the wire rod is improved by a higher C content, while the temperature and speed of the billet rolling are controlled, and rolling is performed at a lower rolling speed to ensure the uniformity of the wire rod structure. A lower cooling speed is maintained when the wire rod is cooled to avoid the generation of harmful structures. During insulation, austenite is allowed to have a long enough time to transform into bainite and ferrite that are beneficial to the drawing of the wire rod, and austenite is prevented from not having enough time to undergo a phase transformation, forming a martensite-austenite structure that is not conducive to the drawing of the wire rod. The wire rod obtained by the wire rod production method of the present application eliminates the thermal stress generated by rolling in the wire rod during the cooling and insulation processes, and can adapt to drawing at a drawing speed of ≤10m / s, that is, the wire rod obtained by the wire rod production method provided in the present application can be directly drawn to produce welding wire without the need for an annealing step.

[0030] The effects of each chemical component have the following characteristics:

[0031] Carbon (C): C is one of the most effective elements for improving the strength of weld metal. At the same time, increasing the C content can improve the hardenability of weld metal, increase the martensitic transformation tendency and welding cold crack sensitivity, and thus deteriorate the low-temperature impact toughness. Therefore, in the wire rod of this application, the C content is controlled to be 0.13~0.15%.

[0032] Silicon (Si): Si is the main deoxidizing element in the welding process, but if the Si content is too high, it can increase the tendency of hot cracking of the weld metal and promote the formation tendency of grain boundary ferrite and side plate ferrite in the weld metal, thereby damaging the low-temperature impact toughness. Therefore, in the wire rod of this application, the Si content is controlled to be 0.60~0.80%.

[0033] Manganese (Mn): Mn is one of the main deoxidizing elements in weld metal and can also improve the strength of weld metal. However, too high Mn content will significantly reduce the low-temperature impact toughness of weld metal. Therefore, in the wire rod of this application, the Mn content is controlled to 1.80~2.10%.

[0034] Titanium (Ti): Ti is a common element in weld metal. Ti oxide can promote the nucleation of intracrystalline acicular ferrite, refine the effective grain size of the weld, and improve the strength and toughness of the weld. Therefore, its content is controlled at 0.16~0.21%.

[0035] Vanadium (V): As an important microalloying element in steel, V can refine the weld structure and simultaneously improve the weld strength and toughness. Therefore, its content is controlled at 0.08~0.11%.

[0036] Boron (B): Boron is one of the elements that effectively improves the hardenability and strength of weld metal. It can promote the formation of intragranular structure in weld metal by utilizing its easy segregation at grain boundaries, and inhibit the formation of bainite and martensite structures formed by grain boundary nucleation, thereby improving the low-temperature toughness of weld metal. Therefore, its content is controlled to be 0.0050~0.0070%.

[0037] Sulfur (S): Increasing the S content can significantly improve the fluidity of the welding pool and reduce the surface tension, thereby ensuring good weld formation and low spatter. However, if the S content is too high, the low-temperature impact toughness of the weld metal will be reduced. In the wire rod of this application, the S content is 0.008~0.013%.

[0038] Chromium (Cr): Cr is a medium-strong carbide-forming element that can combine with C to form stable carbides. These carbides help to improve weld strength, but will reduce plasticity and toughness to a certain extent. In the wire rod of this application, the Cr content is 0.90~1.20%.

[0039] Phosphorus (P): P will increase the "cold brittleness" phenomenon of the weld metal, which means that at lower temperatures, the toughness of the weld metal decreases significantly and brittle fracture is prone to occur, so P≤0.012%.

[0040] Aluminum (Al): Al is a strong oxidizing element. During the welding process, high melting point inclusions Al2O3 are formed, which can easily destroy the arc stability and form large particle spatter. Therefore, Al is required to be ≤0.008%.

[0041] Nitrogen (N): N forms hard and stable nitrides with metals. These nitrides are dispersed in the metal matrix, which can hinder the movement of dislocations and play a strengthening role. In addition, the formation of nitrides helps to pin the grain boundaries and inhibit grain growth, thereby obtaining finer grains. However, excessive N will increase the brittleness of the weld, so the N content is 0.004~0.007%.

[0042] In some embodiments, during the heating process, the steel billet is sent to a heating furnace for heating, the temperature of the soaking section of the heating furnace is 1110-1140°C, and the time in the furnace is 80-90 minutes. Since the C content in this application is relatively high, a relatively high heating temperature is used to heat the steel billet, which can avoid segregation in the steel billet affecting the uniformity of the structure.

[0043] In some embodiments, during the cooling process, the wire rod is placed on a roller, and the roller is evenly divided into multiple sections along its length, and the roller speed of the entrance section is 0.19-0.25 m / s, and the speed of each section increases by 3% thereafter. The cooling process usually adopts a Stelmor cooling line for cooling, and the Stelmor cooling line includes a roller, a heat preservation cover and a fan arranged at intervals along the length of the roller. When the present application adopts a Stelmor cooling line for the cooling process, all the heat preservation covers on the Stelmor cooling line are closed to reduce the cooling speed of the wire rod.

[0044] In some embodiments, before the heating process, the process further includes steelmaking, continuous casting and blanking processes performed in sequence. The steelmaking process smelts molten steel with the aforementioned chemical composition, and the continuous casting process continuously casts the molten steel to form a continuous casting blank, which is a large square billet. The blanking process is required to blank the continuous casting blank into a small square billet, i.e., the aforementioned steel billet.

[0045] In the process of opening the billet, the continuous casting billet is first sent to a heating furnace for heating, and then the continuous casting billet is rolled. The temperature of the heating furnace's soaking section is 1200-1230°C, and the opening temperature is 1060-1080°C. A higher continuous casting billet heating temperature can also avoid the segregation of C elements in the continuous casting billet.

[0046] In some embodiments, the steelmaking process includes converter smelting, LF refining and RH vacuum refining processes performed sequentially. In the converter smelting process, the iron-water ratio is ≥75%, the P content of the molten iron when entering the furnace is ≤0.1%, the slag basicity of the converter steel is controlled to be 1.7-2.3, the converter steel tapping temperature is ≥1610°C, and the S content of the steel is ≤0.005%;

[0047] In the LF refining process, calcium carbide is used to diffuse deoxidize the slag and feed it into the sulfur line according to the sampling test results to ensure that the S content meets the requirements of the wire rod composition;

[0048] In the RH vacuum refining process, deep vacuum degassing is performed for 15 to 20 minutes, and after the vacuum degree is less than 2 mbar, titanium-iron alloy is added for alloying.

[0049] During the steelmaking process, the molten steel is refined in two steps: LF refining and RH vacuum refining to control the purity of the molten steel and improve the low-temperature impact toughness of the final wire rod. In the LF refining process, the sulfur wire is fed to ensure that the S content meets the above-mentioned component requirements. The structure of the sulfur wire is sulfur powder wrapped in an iron shell.

[0050] In some embodiments, during the continuous casting process, the superheat is 36-39°C, the pulling speed is 0.60-0.64 m / s, the water flow rate of the crystallizer is 2820-2880 L / min, and the electromagnetic stirring current of the crystallizer is 700 A. During continuous casting, a large-bag long nozzle and an immersed nozzle full-protection casting method are adopted to continuously cast the continuous casting billet.

[0051] The present application also provides a wire rod, wherein the volume proportion of ferrite is ≥10%, the grain size of ferrite is ≥8 levels, and the volume proportion of martensite-austenite structure is ≤5%.

[0052] In some embodiments, the chemical composition of the wire rod includes, by weight percentage: C: 0.13~0.15%, Si: 0.60~0.80%, Mn: 1.80~2.10%, P≤0.012%, S: 0.008~0.013%, Al≤0.008%, N: 0.004~0.007%, Ti: 0.16~0.21%, Cr: 0.90~1.20%, B: 0.0050~0.0070%, V: 0.08~0.11%, and the rest is Fe and unavoidable impurities.

[0053] The wire rod provided in the embodiment of the present application does not add expensive alloys such as Mo and Ni, but improves the strength by increasing the C content. In order to ensure tensile strength while having excellent low-temperature impact toughness, less Ti and V elements are added. The S element is also added to improve fluidity during welding and reduce surface tension, thereby ensuring good weld formation and low spatter.

[0054] In some embodiments, the wire rod has a tensile strength of 750-800 MPa and a cross-sectional shrinkage of ≥75%. The wire rod having the aforementioned organization and chemical composition has excellent strength and cross-sectional shrinkage.

[0055] In some embodiments, a wire rod is drawn at a drawing speed ≤ 10 m / s to obtain a welding wire, and the welding wire is used to perform a deposited metal test. Preheating before welding and insulation after welding are performed during welding. The tensile strength of the deposited metal weld is ≥ 800 MPa, and the low-temperature impact toughness of -20°C is ≥ 80 J.

[0056] The preheating temperature before welding is 135~165℃, and the insulation time after welding is 2 hours. Preheating during welding and insulation after welding can avoid the problem of cold cracks caused by high carbon content and ensure that the tensile strength of the weld is ≥800MPa.

[0057] The technical solution of the present application is further described below in conjunction with some specific embodiments.

[0058] Example 1

[0059] The chemical composition of the 80 kg welding wire wire rod provided in Example 1 is shown in Table 1. The production method of the wire rod comprises the following steps:

[0060] Converter smelting process: the iron-to-water ratio is 75%, the P content of the molten iron when entering the furnace is 0.1%, the slag basicity is controlled at 1.7 for converter steelmaking, the converter steelmaking temperature is 1610°C, and the S content of the steel is 0.004%.

[0061] LF refining process: Use calcium carbide to diffuse and deoxidize the slag and feed it into a 30-meter sulfur line to ensure that the S content meets the wire rod component requirements.

[0062] RH vacuum refining process: deep vacuum degassing for 15 minutes, after which the vacuum degree is 1.8 mbar, titanium-iron alloy is added for alloying to obtain molten steel having the chemical composition in Table 1.

[0063] Continuous casting process: The molten steel is continuously cast to obtain a continuous casting billet, the superheat is controlled at 37°C, the pulling speed is 0.62m / s, the crystallizer water flow rate is 2850L / min, and the crystallizer electromagnetic stirring current is 700A.

[0064] Billeting process: first send the continuous casting billet obtained by continuous casting into a heating furnace for heating, and then billet rolling the continuous casting billet to obtain small square billets. The temperature of the heating furnace's soaking section is 1200°C, and the billeting temperature is 1060°C.

[0065] Heating process: send the small square billet into the heating furnace for heating. The temperature of the heating furnace's soaking section is 1110°C and the time in the furnace is 80 minutes.

[0066] Rolling process: The heated small square billet is sent to the rolling mill for rolling to obtain wire rod, wherein the finishing rolling inlet temperature is 830°C, the rolling speed is 95m / s, and the spinning temperature is 790°C.

[0067] Cooling process: The roller speed of the wire rod at the entrance section of the roller is 0.19m / s, and the speed increases by 3% in each section thereafter. The cooling rate of the wire rod is controlled at 0.5℃ / s, and the final cooling temperature of the wire rod is 490℃.

[0068] Insulation process: The insulation time of the wire rod is 40 minutes, and the temperature of the wire rod at the end of insulation is 300℃.

[0069] Example 2

[0070] The chemical composition of the 80 kg welding wire wire rod provided in Example 2 is shown in Table 1. The production method of the wire rod comprises the following steps:

[0071] Converter smelting process: the iron-to-water ratio is 77%, the P content of the molten iron when entering the furnace is 0.08%, the slag basicity is controlled at 1.9 for converter steelmaking, the converter steelmaking temperature is 1615°C, and the S content of the steel is 0.003%.

[0072] LF refining process: The slag is diffused and deoxidized with calcium carbide and fed into a 36-meter sulfur line to ensure that the S content meets the wire rod component requirements.

[0073] RH vacuum refining process: deep vacuum degassing for 15 minutes, after which the vacuum degree is 1.6 mbar, titanium-iron alloy is added for alloying to obtain molten steel having the chemical composition in Table 1.

[0074] Continuous casting process: The molten steel is continuously cast to obtain a continuous casting billet, the superheat is controlled at 38°C, the pulling speed is 0.64m / s, the crystallizer water flow rate is 2880L / min, and the crystallizer electromagnetic stirring current is 700A.

[0075] Billeting process: first send the continuous casting billet obtained by continuous casting into a heating furnace for heating, and then billet rolling the continuous casting billet to obtain small square billets. The temperature of the heating furnace's soaking section is 1230°C, and the billeting temperature is 1080°C.

[0076] Heating process: send the small square billet into the heating furnace for heating. The temperature of the heating furnace's soaking section is 1130°C and the time in the furnace is 90 minutes.

[0077] Rolling process: The heated small square billet is sent to the rolling mill for rolling to obtain wire rod, wherein the finishing rolling inlet temperature is 850°C, the rolling speed is 100m / s, and the spinning temperature is 810°C.

[0078] Cooling process: The roller speed of the wire rod at the entrance section of the roller is 0.21m / s, and the speed increases by 3% in each section thereafter. The cooling rate of the wire rod is controlled to be 0.4℃ / s, and the final cooling temperature of the wire rod is 530℃.

[0079] Insulation process: The insulation time of the wire rod is 50 minutes, and the temperature of the wire rod at the end of insulation is 285℃.

[0080] Example 3

[0081] The chemical composition of the 80 kg welding wire wire rod provided in Example 3 is shown in Table 1. The production method of the wire rod comprises the following steps:

[0082] Converter smelting process: the iron-water ratio is 80%, the P content of the molten iron when entering the furnace is 0.01%, the slag basicity is controlled at 2.3 for converter steelmaking, the converter steelmaking temperature is 1625℃, and the S content of the steel is 0.003%.

[0083] LF refining process: The slag is diffused and deoxidized with calcium carbide and fed into a 34-meter sulfur line to ensure that the S content meets the wire rod component requirements.

[0084] RH vacuum refining process: deep vacuum degassing for 15 minutes, after which the vacuum degree is 1.9 mbar, titanium-iron alloy is added for alloying to obtain molten steel having the chemical composition in Table 1.

[0085] Continuous casting process: The molten steel is continuously cast to obtain a continuous casting billet, the superheat is controlled at 39°C, the pulling speed is 0.64m / s, the crystallizer water flow rate is 2820L / min, and the crystallizer electromagnetic stirring current is 700A.

[0086] Billeting process: first send the continuous casting billet obtained by continuous casting into a heating furnace for heating, and then billet rolling the continuous casting billet to obtain small square billets. The temperature of the heating furnace's soaking section is 1225°C, and the billeting temperature is 1073°C.

[0087] Heating process: send the small square billet into the heating furnace for heating. The temperature of the heating furnace's soaking section is 1125°C and the time in the furnace is 84 minutes.

[0088] Rolling process: The heated small square billet is sent to the rolling mill for rolling to obtain wire rod, wherein the finishing rolling inlet temperature is 845°C, the rolling speed is 90m / s, and the spinning temperature is 805°C.

[0089] Cooling process: The roller speed of the wire rod at the entrance section of the roller is 0.25m / s, and the speed increases by 3% in each section thereafter. The cooling speed of the wire rod is controlled at 0.4℃ / s, and the final cooling temperature of the wire rod is 510℃.

[0090] Insulation process: The insulation time of the wire rod is 45 minutes, and the temperature of the wire rod at the end of insulation is 270℃.

[0091] Example 4

[0092] The chemical composition of the 80 kg grade welding wire wire rod provided in Example 4 is shown in Table 1. The production method of the wire rod comprises the following steps:

[0093] Converter smelting process: the iron-to-water ratio is 85%, the P content of the molten iron when entering the furnace is 0.09%, the slag basicity is controlled at 2.1 for converter steelmaking, the converter steelmaking temperature is 1621°C, and the S content of the steel is 0.005%.

[0094] LF refining process: Use calcium carbide to diffuse and deoxidize the slag and feed it into a 25-meter sulfur line to ensure that the S content meets the wire rod component requirements.

[0095] RH vacuum refining process: deep vacuum degassing for 15 minutes, after which the vacuum degree is 1.8 mbar, titanium-iron alloy is added for alloying to obtain molten steel having the chemical composition in Table 1.

[0096] Continuous casting process: The molten steel is continuously cast to obtain a continuous casting billet, the superheat is controlled at 36°C, the pulling speed is 0.60m / s, the crystallizer water flow rate is 2830L / min, and the crystallizer electromagnetic stirring current is 700A.

[0097] Billeting process: first send the continuous casting billet obtained by continuous casting into a heating furnace for heating, and then billet rolling the continuous casting billet to obtain small square billets. The temperature of the heating furnace's soaking section is 1220°C, and the billeting temperature is 1068°C.

[0098] Heating process: send the small square billet into the heating furnace for heating. The temperature of the heating furnace's soaking section is 1140°C and the time in the furnace is 87 minutes.

[0099] Rolling process: The heated small square billet is sent to the rolling mill for rolling to obtain wire rod, wherein the finishing rolling inlet temperature is 840°C, the rolling speed is 93m / s, and the wire drawing temperature is 800°C.

[0100] Cooling process: The roller speed of the wire rod at the entrance section of the roller is 0.23m / s, and the speed increases by 3% in each section thereafter. The cooling rate of the wire rod is controlled at 0.5℃ / s, and the final cooling temperature of the wire rod is 496℃.

[0101] Insulation process: The insulation time of the wire rod is 60 minutes, and the temperature of the wire rod at the end of insulation is 266℃.

[0102] The wire rods of Examples 1 to 4 are directly drawn without annealing treatment at a drawing speed of 10 m / s, and then copper-plated and coiled.

[0103] Composition and performance testing: The copper plating on the surface of the finished welding wire was ground off, and the composition was tested using ICP and CS instruments. The chemical composition is expressed in weight percentage, as shown in Table 1. The deposited metal test was carried out with reference to standard GB∕T 39281-2020, and then the mechanical properties test and grain size measurement were carried out with reference to standard GB / T 25774.1-2023 and standard GB / T 6394-2002, respectively. The test results are shown in Table 2.

[0104] Table 1

[0105]

[0106] Table 2

[0107]

[0108] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0109] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present application. They are not intended to limit the scope of protection of the present application. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present application should be included in the scope of protection of the present application.

Claims

1. A method for producing a wire rod, characterized in that: The chemical composition of the wire rod includes, by weight percentage: C: 0.13-0.15%, Si: 0.60-0.80%, Mn: 1.80-2.10%, P≤0.012%, S: 0.008-0.013%, Al≤0.008%, N: 0.004-0.007%, Ti: 0.16-0.21%, Cr: 0.90-1.20%, B: 0.0050-0.0070%, V: 0.08-0.11%, and the rest is Fe and unavoidable impurities; The production method of the wire rod comprises subjecting a steel billet having the chemical composition as described above to heating, rolling, cooling and heat preservation steps to obtain the wire rod, wherein: In the rolling process, the steel billet is fed into the rolling mill for rolling to obtain the wire rod, wherein the finishing rolling inlet temperature is 830-850°C, the rolling speed is 90-100 m / s, and the wire laying temperature is 790-810°C; In the cooling process, the cooling rate of the wire rod is controlled to be ≤0.5℃ / s, and the final cooling temperature of the wire rod is ≤530℃; In the heat preservation process, the heat preservation time of the wire rod is ≥40min, and the temperature of the wire rod at the end of heat preservation is ≤300℃; The insulated wire rod is drawn at a drawing speed of ≤10m / s to obtain welding wire, and the welding wire is used for deposited metal test. Preheating before welding and insulation after welding are performed during welding. The tensile strength of the deposited metal weld is ≥800MPa, and the low-temperature impact toughness of -20℃ is ≥80J.

2. The method for producing wire rod according to claim 1, characterized in that: In the heating process, the steel billet is sent to a heating furnace for heating. The temperature of the soaking section of the heating furnace is 1110~1140℃, and the time in the furnace is 80~90min.

3. The method for producing wire rod according to claim 1, characterized in that: During the cooling process, the wire rod is placed on a roller, and the roller is evenly divided into multiple sections along its length. The roller speed at the entrance section is 0.19~0.25m / s, and the speed of each section increases by 3% thereafter.

4. The method for producing wire rod according to claim 1, characterized in that: Before the heating process, the process also includes steelmaking, continuous casting and billeting, which are carried out in sequence, among which: In the blanking process, the continuous casting blank obtained by continuous casting is first sent to a heating furnace for heating, and then the continuous casting blank is blanked and rolled. The temperature of the heating furnace's soaking section is 1200~1230℃, and the blanking temperature is 1060~1080℃.

5. The method for producing wire rod according to claim 4, characterized in that: The steelmaking process includes converter smelting, LF refining and RH vacuum refining processes in sequence. In the converter smelting process, the molten iron ratio is ≥75%, the P content of the molten iron when entering the furnace is ≤0.1%, the slag basicity of the converter steel is controlled to be 1.7~2.3, the converter steel tapping temperature is ≥1610℃, and the S content of the steel is ≤0.005%; In the LF refining process, calcium carbide is used to diffuse and deoxidize the slag, and the sulphur line is fed according to the sampling test results to ensure that the S content meets the requirements of the wire rod composition; In the RH vacuum refining process, deep vacuum degassing is performed for 15 to 20 minutes, and after the vacuum degree is less than 2 mbar, titanium-iron alloy is added for alloying.

6. The method for producing wire rod according to claim 4, characterized in that: During the continuous casting process, the superheat is 36~39℃, the pulling speed is 0.60~0.64m / s, the crystallizer water flow rate is 2820~2880L / min, and the crystallizer electromagnetic stirring current is 700A.

7. A wire rod, characterized in that: The chemical composition of the wire rod includes, by weight percentage: C: 0.13-0.15%, Si: 0.60-0.80%, Mn: 1.80-2.10%, P≤0.012%, S: 0.008-0.013%, Al≤0.008%, N: 0.004-0.007%, Ti: 0.16-0.21%, Cr: 0.90-1.20%, B: 0.0050-0.0070%, V: 0.08-0.11%, and the rest is Fe and unavoidable impurities; The production method of the wire rod comprises subjecting a steel billet having the chemical composition as described above to heating, rolling, cooling and heat preservation steps to obtain the wire rod, wherein: In the rolling process, the steel billet is fed into the rolling mill for rolling to obtain the wire rod, wherein the finishing rolling inlet temperature is 830-850°C, the rolling speed is 90-100 m / s, and the wire laying temperature is 790-810°C; In the cooling process, the cooling rate of the wire rod is controlled to be ≤0.5℃ / s, and the final cooling temperature of the wire rod is ≤530℃; In the heat preservation process, the heat preservation time of the wire rod is ≥40min, and the temperature of the wire rod at the end of heat preservation is ≤300℃; The volume proportion of ferrite in the wire rod is ≥10%, the grain size of ferrite is ≥8, and the volume proportion of martensite-austenite structure is ≤5%; The wire rod is drawn at a drawing speed of ≤10m / s to obtain the welding wire, and the welding wire is used for the deposited metal test. Preheating before welding and insulation after welding are performed during welding. The tensile strength of the deposited metal weld is ≥800MPa, and the low-temperature impact toughness of -20℃ is ≥80J.

8. The wire rod according to claim 7, characterized in that Its chemical composition, in weight percentage, includes: C: 0.13~0.15%, Si: 0.60~0.80%, Mn: 1.80~2.10%, P≤0.012%, S: 0.008~0.013%, Al≤0.008%, N: 0.004~0.007%, Ti: 0.16~0.21%, Cr: 0.90~1.20%, B: 0.0050~0.0070%, V: 0.08~0.11%, and the rest is Fe and unavoidable impurities.

9. The wire rod according to claim 8, characterized in that The tensile strength of the wire rod is 750~800MPa, and the cross-sectional shrinkage rate is ≥75%.

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