A high-quality high-carbon steel wire and a method for smelting the same using all scrap steel

Abstract

The present invention provides a high-quality high-carbon steel wire and a method for smelting all scrap steel thereof, and belongs to the technical field of steelmaking. The present invention systematically optimizes the all-scrap steel electric furnace smelting process, and reduces the amount of harmful elements such as nickel, chromium, copper, arsenic and molybdenum introduced by improving the type, size and matching method of the scrap steel entering the furnace in terms of raw materials. At the same time, in order to control the problem of difficult-to-control nitrogen content in steel caused by long-term power-on of all-scrap steel smelting in the electric furnace, a low-nitrogen carburizer is added to the scrap steel entering the furnace to increase the carbon content of the molten pool during electric furnace smelting, and at the same time, the furnace wall gun oxygen supply and carbon powder spraying process are optimized to improve the foam slag effect and reduce the nitrogen absorption of molten steel. A precise continuous casting and rolling control method is adopted to obtain highly homogenized ingots and high-quality wire rods, providing high-purity parent materials for high-end wire products. The present invention is used to produce high-cleanliness and high-homogenization wire products, and reduce the carbon emission level of the entire smelting process.

Description

Technical Field

[0001] The invention relates to a high-quality high-carbon steel wire and a full scrap steel smelting method thereof, belonging to the technical field of steelmaking. Background Art

[0002] High-carbon steel wire products are diverse and widely used. High-quality high-carbon steel products represented by spring steel, cord steel and cable steel have very strict control requirements on cleanliness, segregation, surface and internal quality during the production process. Traditional high-quality high-carbon steel wire is generally produced by blast furnace-KR hot metal pretreatment-converter-refining (LF or LF-VD / RH)-continuous casting process, which has a long production process and high carbon emissions.

[0003] The patent application with publication number CN111069280A provides a method for producing low-strength cord steel wire rods, which improves the wire rod structure performance by designing parameters such as the number of cooling water tanks after finishing rolling, the pressure of the water cooling box, the spinning temperature, the roller speed and the fan air volume.

[0004] The patent application with publication number CN113061799A provides a high-cleanliness spring steel and a production method thereof, which is produced by deep desulfurization of molten iron, dephosphorization in converter, LF refining, RH vacuum and continuous casting process, controls the bottom blowing of converter steel tapping and refining process, and combines RH vacuum treatment process and tundish induction heating technology to control the inclusions in molten steel throughout the process to obtain spring steel wire rod with high cleanliness.

[0005] The patent application with publication number CN113388710A provides a smelting control method for ultra-high strength cord steel, which adopts KR desulfurization-converter smelting-LF furnace deoxidation and slag-continuous casting process to finally complete the smelting of ultra-high strength cord steel. The invention controls the KR molten iron desulfurization, converter double slag operation, terminal carbon content, steel tapping temperature, and refining deoxidation and slag making processes to minimize the nitrogen content of molten steel, reduce TiN inclusions in molten steel, improve the purity of molten steel, shorten the process, and reduce the processing time.

[0006] The patent application with publication number CN113215354A provides a full scrap steel smelting process, in which the smelting efficiency of the top-loading electric arc furnace is improved by optimizing the scrap steel batching, oxygen supply and power supply processes. However, this process mainly starts from improving the smelting efficiency and cannot be used to produce high-quality high-carbon steel wire with high impurity elements and high cleanliness requirements.

[0007] High-grade, important-purpose high-carbon steel wire products have strict requirements on impurity elements, inclusions, composition and uniformity of organization. Therefore, controlling the content of impurity elements, inclusion types, sizes and uniformity of composition and organization has always been the focus of the research and development of high-grade high-carbon steel wire. At present, the commonly used high-quality high-carbon steel wire is mainly produced by the long process of converter. The converter production has the problems of long process and high carbon emissions. With the increasing demand of customers for low-carbon wire products, the use of electric furnace short process to produce high-quality high-carbon steel wire is gradually increasing. However, due to the increase in the use of scrap steel, residual elements such as nickel, chromium, copper, arsenic and molybdenum brought into the scrap steel will endanger the quality of steel. At the same time, there are problems such as nitrogen, sulfur and cleanliness that are difficult to control when smelting all scrap steel in an electric furnace, which seriously restricts the production of high-quality high-carbon steel wire by the short process of electric furnace all scrap steel.

[0008] It can be seen that how to use electric furnace short process to produce high-quality high-carbon steel wire is a current research hotspot, and there is no reliable and stable process. Summary of the invention

[0009] In order to solve the above-mentioned problems, the present invention discloses a high-quality high-carbon steel wire and a full scrap steel smelting method thereof, aiming to solve the problems of difficult control of impurity elements and cleanliness that exist in the current high-quality high-carbon steel wire using electric arc furnace short-process full scrap steel smelting.

[0010] The high carbon steel described in the present application is a grade 60 or higher high carbon steel, and the carbon content of the high carbon steel is above 0.6%.

[0011] The high-quality high-carbon steel wire described in this application is a high-end product steel represented by spring steel, cord steel and cable steel.

[0012] The specific technical solutions of this application are as follows:

[0013] A method for smelting high-quality high-carbon steel wire rods from scrap steel is produced according to the process flow of electric arc furnace smelting - electric arc furnace steel tapping - LF refining - large square billet continuous casting - billet opening - high-speed wire rolling. The specific steps are as follows:

[0014] Step 1: Electric Arc Furnace Smelting

[0015] Step 1.1: Scrap steel in batches: The scrap steel is divided into two batches and added into the furnace through the material bag respectively. The first material bag is added with 10t-12t of clean scrap steel crushing material, 2.5t-2.8t of carburizer, 15t-17t of high carbon scrap steel, 18t-20t of clean scrap steel briquettes, 13t-15t of high carbon scrap steel and 9t-10t of clean scrap steel crushing material from bottom to top; the second material bag is added with 4t-5t of clean scrap steel crushing material, 29t-30t of high carbon scrap steel and 4t-5t of clean scrap steel briquettes from bottom to top; the total loading amount of scrap steel is 110t±2t, the loading amount of scrap steel in the first bag is 65t-70t, and the rest is loaded into the second bag;

[0016] Step 1.2: Smelting of the first batch of scrap steel: After the first batch of scrap steel is added to the electric arc furnace, close the furnace cover, lower the electrode to energize, and turn on the three furnace wall cluster oxygen lances to preheat the scrap steel. Each furnace wall cluster oxygen lance has three channels: main oxygen, auxiliary oxygen and fuel gas. The main oxygen flow rate and auxiliary oxygen flow rate of the furnace wall cluster oxygen lance are 200-250Nm 3 / h, gas flow rate is 400-500Nm 3 / h; when the total power consumption is greater than 6000kWh, the three furnace wall oxygen lances start blowing mode, and the main oxygen flow rate is controlled at 1200-1400Nm 3 / h, auxiliary oxygen is controlled at 100-120Nm 3 / h, gas flow rate is 100-120Nm 3 / h, add 1000kg-1200kg of lime;

[0017] Step 1.3: Smelting of the second batch of scrap steel: When the power consumption is greater than 20,000 kWh, stop supplying power, and adjust the furnace wall cluster oxygen lance to the holding mode; open the furnace cover to add the scrap steel of the second material bag, close the furnace cover after the scrap steel is added, and turn on the power, and open the three furnace wall cluster oxygen lances to preheat the scrap steel; when the total power consumption is greater than 23,000 kWh, the three furnace wall cluster oxygen lances start the blowing mode, and add 1,200 kg to 1,500 kg of lime at the same time; when the power consumption is greater than 30,000 kWh, open the furnace wall carbon powder gun to start spraying carbon powder, and the carbon powder spraying flow rate is controlled at 0.9 kg / t﹒ min-1.0 kg / t﹒ min; at the same time, according to the foam slag situation, add lime in multiple batches, 200 kg to 300 kg of lime is added in each batch, and the final slag basicity is controlled at 2.8 to 3.2;

[0018] Step 1.4: The final tapping temperature of the electric arc furnace smelting is greater than 1600°C, the final carbon content is greater than 0.04%, the final phosphorus content is less than 0.012%, the nitrogen content is less than 50ppm, and the sulfur content is less than 0.012%;

[0019] Step 2: Electric Arc Furnace Steelmaking

[0020] Step 2.1: When one third of the steel is tapped from the electric arc furnace, add 300kg-350kg of low nitrogen carburizer to the ladle; add manganese metal for pre-deoxidation, the amount of manganese metal added is 3kg / t-4kg / t; add low titanium and low aluminum ferrosilicon, the amount of low titanium and low aluminum ferrosilicon added is 1.5 kg / t-2kg / t;

[0021] Step 2.2: After the steel is tapped, 400kg to 450kg of low nitrogen carburizer is added to the ladle, and the bottom blowing argon flow rate is 400NL / min-600NL / min;

[0022] Step 3: LF Refining

[0023] Step 3.1: The ladle is hoisted into the LF refining station, 1.8t~2t synthetic slag is added, the power is turned on to increase the temperature, 100kg~150kg of SiC is added to diffuse and deoxidize the slag; 50kg~100kg of lime is added, the slag basicity is controlled to 0.92~1.05, and the bottom blowing argon flow rate is controlled at 600NL / min~800NL / min;

[0024] Step 3.2: Take samples by temperature measurement, and add the remaining low-nitrogen carburizer, metallic manganese and low-titanium and low-aluminum ferrosilicon to adjust the composition according to the composition of the molten steel sample and the requirements of the steel grade;

[0025] Step 3.3: After the composition is adjusted, the temperature of the molten steel is controlled at 1525℃~1535℃;

[0026] Step 3.4: After the composition adjustment is completed, soft stirring is performed to remove inclusions, and the argon gas blowing at the bottom of the ladle is gradually reduced to a soft stirring state, with a flow rate of 60 NL / min-110NL / min, and the soft stirring time is controlled at 26min-31min;

[0027] Step 4: Bloom continuous casting: Bloom continuous casting machine is used for casting, and the casting is protected during the whole casting process. Low basicity and low alumina tundish covering agent is used to control the superheat of molten steel in the tundish at 20℃~30℃, low melting point crystallizer protection slag is used, and electromagnetic stirring of the crystallizer is used; the water volume of the crystallizer is 2975 L / min-3025L / min; the second cooling section adopts weak cooling mode, and the water volume of the second cooling section from zone 1 to zone 4 is respectively: 60 NL / min-100 NL / min in zone 1, 20 NL / min-50 NL / min in zone 2, 20NL / min-40 NL / min in zone 3, and 10 NL / min-30 NL / min in zone 4;

[0028] Step 5: Blanking process: the blanking heating temperature is 1180℃-1250℃;

[0029] Step 6: High-speed wire rolling process: heating temperature is 1080℃-1160℃, rolling temperature is 960℃-1030℃, and spinning temperature is 860℃-920℃.

[0030] Furthermore, in the electric furnace smelting process in step 1, the thickness of the clean scrap steel entering the furnace is ≥3.0mm, and the chemical composition includes S content ≤0.005%, Ni content ≤0.01%, Cr content ≤0.03%, Cu content ≤0.01%, Al content ≤0.01%, and Ti content ≤0.01%. The thickness of the high-carbon scrap steel entering the furnace is ≥3.0mm, and the chemical composition includes C content >0.7%, S content <0.012%, Ni content ≤0.03%, Cr content ≤0.03%, Cu content ≤0.05%, Al content ≤0.01%, and Ti content ≤0.01%.

[0031] Furthermore, the carbon content of the recarburizer added to the electric furnace in step 1.1 is greater than 95%, and the sulfur content is less than 0.20%.

[0032] The low nitrogen recarburizer added during steel tapping in step 2.1 has a carbon content greater than 95%, a sulfur content less than 0.20%, and a nitrogen content less than 0.02%.

[0033] Furthermore, in step 1.3, the furnace wall cluster oxygen lance is kept in the mode, and the main oxygen flow rate is 100Nm 3 / h—120Nm 3 / h, auxiliary oxygen 100Nm 3 / h—120Nm 3 / h, gas flow rate 50Nm 3 / h—100Nm 3 / h;

[0034] In step 1.3, the main oxygen flow rate of the furnace wall cluster oxygen lance blowing mode is 1200Nm 3 / h—1400Nm 3 / h, auxiliary oxygen flow rate 100Nm 3 / h—120Nm 3 / h, gas flow 100Nm 3 / h—120Nm 3 / h.

[0035] Furthermore, in the electric furnace smelting process in step 1, the injection amount of carbon powder during the electric furnace smelting process is controlled at 20 kg / t to 22 kg / t.

[0036] Furthermore, the mass percentages of the components of the synthetic slag are: SiO2 content 45%-49%, CaO content 38%-43%, Al2O3 content 1%-4%, MgO content 4%-7%, T.Fe content ≤1%, MnO content ≤2%, and other inevitable impurity components.

[0037] Furthermore, the continuous casting machine is a straight arc rectangular billet continuous casting machine, the cross-sectional dimensions of the continuous casting billet are 300 mm×390 mm, and the arc radius is 12.5 m.

[0038] Furthermore, the tonnage of the continuous casting tundish is ≥18t when starting to pour, the tonnage of the tundish is ≥35t during normal pouring, and the tonnage of the tundish is ≥30t during continuous casting and ladle replacement.

[0039] Furthermore, during the continuous casting process, the argon flow rate of the ladle long shroud is 250 NL / min-350NL / min; the thickness of the mold protective slag layer is maintained at 15mm-22mm, and the added amount is 0.25 kg / t-0.35kg / t.

[0040] Furthermore, the continuous casting billet is lightly pressed in a tension and leveling machine, with a total pressing amount of 8 mm-15 mm and a pressing roller pressure of 30 bar-40 bar.

[0041] Furthermore, the electromagnetic stirring current of the crystallizer is 400A-600A, the frequency is 5 Hz-7 Hz, the continuous casting speed is controlled at 0.5 m / min-0.7 m / min, and the C segregation of the cast billet is 0.95-1.05.

[0042] A high-quality high-carbon steel wire is obtained by the above-mentioned high-quality high-carbon steel wire full-scrap steel smelting method.

[0043] Furthermore, in addition to Si, Mn, Cr, V alloy elements and Fe elements, the high-quality high-carbon steel wire also includes the following chemical components in mass percentage: C: 0.7%-0.9%, P≤0.015%, S≤0.012%, TO≤0.0020%, N≤0.005%, Alt≤0.0015%, Ti≤0.0005%, Ni≤0.02%, Cu≤0.015%, Mo≤0.005%, Sn≤0.010% and As≤0.008%.

[0044] Furthermore, the inclusions in the high-quality high-carbon steel wire include SiO2-MnO-Al2O3 low-melting-point inclusions, and the number density of inclusions larger than 1 μm is ≤5 / mm 2 , the number density of inclusions larger than 5μm is ≤0.12 / mm 2The maximum size of transverse inclusions is ≤15μm, the rating of longitudinal inclusions A, B, C, D, and Ds are all ≤1, and the size of brittle inclusions is ≤5μm.

[0045] The principle of the present invention is:

[0046] At present, the commonly used high-quality high-carbon steel wire is mainly produced by the long converter process, which has the problems of long process and high carbon emission. With the increasing demand of customers for low-carbon wire products, the use of electric furnace short process to produce high-quality high-carbon steel wire is gradually increasing. However, due to the increase in the use of scrap steel, the residual elements such as nickel, chromium, copper, arsenic and molybdenum brought into the steel by the scrap steel will endanger the quality of the steel. At the same time, there are problems such as nitrogen, sulfur and cleanliness that are difficult to control when smelting all scrap steel in the electric furnace, which seriously restricts the production of high-quality high-carbon steel wire by the short process of all scrap steel in the electric furnace.

[0047] The present invention redesigns the product production process, using the electric arc furnace - LF refining furnace - large square billet continuous casting - billet opening - high-speed wire rolling process for production. The core technical points of the entire process are as follows:

[0048] (1) In the electric furnace smelting process, optimize the type, size and combination of scrap steel entering the furnace in the material bag to reduce the amount of harmful elements such as nickel, chromium, copper, arsenic and molybdenum brought in from the source. The content of impurity elements in each type of scrap steel is different. In order to control impurity elements, sulfur and nitrogen, etc., the silicon steel scrap and high carbon scrap steel used in this application have requirements for each type of scrap steel. At the same time, the sulfur content of the recarburizer entering the furnace is also limited.

[0049] (2) In order to control the problem of difficult-to-control nitrogen content in steel caused by long-term power-on during electric furnace smelting of all scrap steel, a recarburizer is added to the scrap steel entering the furnace to increase the carbon content of the molten pool during electric furnace smelting and improve the decarburization speed. The higher the carbon content, the faster the decarburization speed, which reduces nitrogen absorption by the molten steel. At the same time, the furnace wall gun oxygen supply and carbon powder spraying process are optimized to improve the foam slag effect and the height of the foam slag, which has a good submerged arc effect, avoids nitrogen absorption during the power-on process, and reduces the amount of nitrogen absorbed by the molten steel.

[0050] (3) In the early stage of the refining process, the composition is adjusted quickly, and an appropriate amount of synthetic slag and lime are added to control the slag basicity. The steel slag reaction promotes the transformation of the inclusion composition to the low melting point area, which is beneficial to the deformation of the inclusions during the rolling process. Then, the bottom blowing argon gas size is adjusted for soft stirring to promote the floating removal of inclusions.

[0051] (4) Continuous casting adopts low superheat narrow range and constant pulling speed casting technology, while controlling the pressure distribution to achieve precise segmented pressure reduction, reduce the segregation of various elements in the ingot, and reduce the formation of precipitate inclusions; at the same time, avoid problems such as internal cracks caused by inappropriate pressure distribution.

[0052] (5) High temperature and long time heating technology is used in the process of blanking and rolling to promote uniform diffusion of elements and eliminate problems such as element segregation. At the same time, the full grinding of blanks and the application of new coating materials are combined to reduce the decarburization of the surface of the wire rod.

[0053] The beneficial effects of the present invention are:

[0054] In order to solve the problem that when high-quality high-carbon steel wire is produced from all scrap steel in an electric arc furnace, the residual elements such as nickel, chromium, copper, arsenic and molybdenum exceed the standard due to the increase in the amount of scrap steel used, and the nitrogen, sulfur and cleanliness are difficult to control, the present invention redesigns the product production process of high-quality high-carbon steel wire, and uses the process flow of electric arc furnace-LF refining furnace-large square billet continuous casting-bill opening-high wire rolling for production. In the electric furnace smelting process, all scrap steel is used for smelting, and the amount of harmful elements such as nickel, chromium, copper, arsenic and molybdenum introduced is reduced from the source by optimizing the type, size and matching method of the scrap steel entering the furnace in the material bag. In order to control the problem that the nitrogen content in the steel is difficult to control due to long-term power supply during the smelting of all scrap steel in the electric furnace, a carburizer is added to the scrap steel entering the furnace to increase the carbon content of the molten pool during the electric furnace smelting, increase the decarburization rate, and reduce the nitrogen absorption of the molten steel. The more carbon, the faster the carbon-oxygen reaction rate, and the more carbon monoxide bubbles generated in the molten steel, which can prevent the molten steel from absorbing nitrogen. At the same time, the furnace wall gun oxygen supply and carbon powder spraying process are optimized to improve the foam slag effect, increase the height of the foam slag, improve the arc effect, and reduce the nitrogen absorption of the molten steel. The slag basicity is controlled during the refining process, and the inclusion composition is promoted to change to the low melting point area through the slag reaction. The bottom blowing argon gas size is adjusted for soft stirring to promote the floating removal of inclusions. The continuous casting adopts low superheat narrow interval and constant pulling speed casting technology, and at the same time realizes the control of pressure distribution to achieve precise segmented pressure reduction, reducing the segregation of various elements in the ingot. DETAILED DESCRIPTION

[0055] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0056] The all-scrap steel smelting method of high-quality high-carbon steel wire adopts the process flow of electric arc furnace-LF refining-large square billet continuous casting-blowing-high-wire rolling for production, which specifically includes the following steps:

[0057] Step 1: Electric arc furnace smelting, scrap steel is added into the furnace in two batches through the material bag. The first material bag is added with 10t-12t of clean scrap steel crushing material, 2.5t-2.8t of carburizer, 15t-17t of high carbon scrap steel, 18t-20t of clean scrap steel briquettes, 13t-15t of high carbon scrap steel and 9t-10t of clean scrap steel crushing material from bottom to top. In the second bag, 4t-5t of clean scrap steel crushing material, 29t-30t of high carbon scrap steel and 4t-5t of clean scrap steel briquettes are added from bottom to top. The total loading amount of scrap steel is 110t±2t. The loading amount of scrap steel in the first bag is 65t-70t, and the rest is loaded into the second bag. The thickness of clean scrap steel entering the furnace is ≥3.0mm.

[0058] Step 2: After the first bag of scrap steel is added into the electric arc furnace, the furnace cover is closed, the electrode is lowered to energize, and three furnace wall cluster oxygen lances are turned on to preheat the scrap steel. The main oxygen flow rate and auxiliary oxygen flow rate of the furnace wall cluster oxygen lance are 250Nm 3 / h, gas flow rate is 500Nm 3 / h. The three furnace wall cluster oxygen lances are all located 600mm-650mm above the furnace molten pool liquid level. When the total power consumption is greater than 6000kWh, the three furnace wall cluster oxygen lances start the blowing mode, and the main oxygen flow rate is controlled at 1200Nm 3 / h—1400Nm 3 / h, auxiliary oxygen is controlled at 100Nm 3 / h—120Nm 3 / h, gas flow rate is 100Nm 3 / h—120Nm 3 / h, add 1000kg - 1200kg of lime.

[0059] Step 3: Electric arc furnace smelting, when the power consumption is greater than 20000kWh, stop supplying power, and adjust the furnace wall cluster oxygen lance to the holding mode. Open the furnace cover to add the second bag of scrap steel. After the scrap steel is added, close the furnace cover and turn on the power, and open the three furnace wall cluster oxygen lances to preheat the scrap steel. When the total power consumption is greater than 23000kWh, the three furnace wall cluster oxygen lances start the blowing mode. In the blowing mode, the main oxygen flow rate of the furnace wall cluster oxygen lance is controlled at 1200Nm 3 / h~1400Nm 3 / h. At the same time, add 1200kg-1500kg of lime. When the power consumption is greater than 30000kWh, open the carbon powder gun on the furnace wall to start spraying carbon powder, and the carbon powder spraying flow rate is controlled at 0.9kg / t﹒ min-1.0kg / t﹒ min. At the same time, according to the foam slag situation, add lime in small batches, 200kg-300kg of lime is added in each batch, and the final slag basicity is controlled at 2.8-3.2. The spraying amount of carbon powder in the electric furnace smelting process is controlled at 20 kg / t~22kg / t.

[0060] Step 4: Electric arc furnace smelting, the final steel-making temperature is greater than 1600℃, the final carbon content is greater than 0.04%, the final phosphorus content is less than 0.012%, the nitrogen content is less than 50ppm, and the sulfur content is less than 0.012%.

[0061] Step 5: When the arc furnace is tapping steel, add 300kg-350kg of low nitrogen carburizer to the ladle when one third of the steel is tapped. Add manganese metal for pre-deoxidation, the amount of manganese metal added is 3kg / t-4kg / t. Add low titanium and low aluminum ferrosilicon, the amount of low titanium and low aluminum ferrosilicon added is 1.5 kg / t-2kg / t;

[0062] Step 6: After steel tapping is completed, 400kg to 450kg of low nitrogen carburizer is added to the ladle, and the bottom blowing argon flow rate is 400 NL / min-600 NL / min;

[0063] Step 7: The ladle is hoisted into the LF refining station, and 1.8t~2t of synthetic slag is added. The mass percentages of the components of the synthetic slag are: SiO2 content 45%-49%, CaO content 38%-43%, Al2O3 content 1%-4%, MgO content 4%-7%, T.Fe content ≤1%, MnO content ≤2%, and other unavoidable impurity components. Start to power on and heat up. Add 100kg~150kg of SiC to diffuse and deoxidize the slag; add 50kg~100kg of lime, control the slag basicity to 0.92~1.05, and control the bottom blowing argon flow rate to 600NL / min~800NL / min;

[0064] Step 8: Take samples by temperature measurement, and add the remaining low-nitrogen carburizer, metallic manganese and low-titanium and low-aluminum ferrosilicon to adjust the composition according to the composition of the molten steel sample and the requirements of the steel grade;

[0065] Step 9: After the composition is adjusted, the temperature of the molten steel is controlled at 1525℃~1535℃;

[0066] Step 10: After the composition adjustment is completed, soft stirring is performed to remove inclusions, and the argon gas blowing at the bottom of the ladle is gradually reduced to a soft stirring state, with a flow rate of 60 NL / min-110NL / min. In the early stage, the fluctuation of the slag surface should be frequently observed, and the soft stirring time should be controlled within 26min-31min when the slag surface fluctuates slightly;

[0067] Step 11: Use a large square billet continuous casting machine for casting. The continuous casting machine is a straight arc rectangular billet continuous casting machine. The cross-sectional size of the continuous casting billet is 300mm×390mm, and the arc radius is 12.5m. The tonnage of the continuous casting tundish is ≥18t, the tonnage of the tundish is ≥35t during normal casting, and the tonnage of the tundish is ≥30t during continuous casting and changing tundishes. Protect the casting throughout the continuous casting process, use a low-alkalinity and low-alumina tundish covering agent, control the superheat of the molten steel in the tundish to 20℃~30℃, use low-melting point crystallizer protection slag, and use crystallizer electromagnetic stirring. The crystallizer electromagnetic stirring current is 400A-600A, the frequency is 5 Hz-7Hz, the continuous casting speed is controlled at 0.5 m / min-0.7m / min, the continuous casting billet is lightly pressed in the straightening machine, the total pressure reduction is 8 mm-15mm, the pressure of the pressing roller is 30 bar-40bar, and the C segregation of the casting billet is 0.95-1.05. The crystallizer water volume is 2975 L / min-3025L / min; the second cooling section adopts weak cooling mode, and the water volume of the second cooling section from zone 1 to zone 4 is: 60 NL / min-100 NL / min in zone 1, 20 NL / min-50 NL / min in zone 2, 20 NL / min-40 NL / min in zone 3, and 10 NL / min-30 NL / min in zone 4. During the continuous casting process, the argon flow rate of the ladle long shroud is 250 NL / min-350NL / min; the thickness of the mold protective slag layer is maintained at 15mm-22mm, and the addition amount is 0.25 kg / t-0.35kg / t.

[0068] Step 12: blanking process, the blanking heating temperature is 1180℃-1250℃;

[0069] Step 13: High-speed wire rolling process: heating temperature is 1080℃-1160℃, rolling temperature is 960℃-1030℃, and wire laying temperature is 860℃-920℃.

[0070] The present invention also applies for protection of a high-quality high-carbon steel wire obtained by a full scrap steel smelting method of a high-quality high-carbon wire. In addition to Si, Mn, Cr, V alloy elements and Fe elements, the high-quality high-carbon steel wire also includes the following chemical components in mass percentage: C: 0.7%-0.9%, P≤0.015%, S≤0.012%, TO≤0.0020%, N≤0.005%, Alt≤0.0015%, Ti≤0.0005%, Ni≤0.02%, Cu≤0.015%, Mo≤0.005%, Sn≤0.010% and As≤0.008%.

[0071] The inclusions in high-quality high-carbon steel wire are mainly SiO2-MnO-Al2O3 low-melting-point inclusions, and the number density of inclusions larger than 1μm is ≤5 / mm 2, the number density of inclusions larger than 5μm is ≤0.12 / mm 2 The maximum size of transverse inclusions is ≤15μm, the rating of longitudinal inclusions A, B, C, D, and Ds are all ≤1, and the size of brittle inclusions is ≤5μm.

[0072] Three specific application examples of the present invention are given below:

[0073] In electric furnace smelting, scrap steel is added into the furnace in two batches through the material bag. The first material bag is added with clean scrap steel crushing material, carburizer, high carbon scrap steel, clean scrap steel briquettes, high carbon scrap steel and clean scrap steel crushing material from bottom to top; the second material bag is added with clean scrap steel crushing material, high carbon scrap steel and clean scrap steel briquettes from bottom to top. The specific amount of scrap steel added is shown in Table 1:

[0074] Table 1

[0075]

[0076] The clean scrap steel entering the furnace is silicon steel scrap steel, and its chemical composition includes S content ≤0.005%, Ni content ≤0.01%, Cr content ≤0.03%, Cu content ≤0.01%, Al content ≤0.01%, and Ti content ≤0.01%. The thickness of high carbon scrap steel entering the furnace is ≥3.0mm, and its chemical composition includes C content>0.7%, S content<0.012%, Ni content ≤0.03%, Cr content ≤0.03%, Cu content ≤0.05%, Al content ≤0.01%, and Ti content ≤0.01%.

[0077] After the first bag of scrap steel is added to the electric arc furnace, the furnace cover is closed, the electrode is lowered to energize, and at the same time, three cluster oxygen lances on the furnace wall are turned on to preheat the scrap steel. The main oxygen flow rate and auxiliary oxygen flow rate of the cluster oxygen lance are 250Nm 3 / h, gas flow rate is 500Nm 3 / h; when the total power consumption is greater than 6000kWh, the three furnace wall oxygen lances start blowing mode, and the main oxygen flow rate is controlled at 1400Nm 3 / h, auxiliary oxygen is controlled at 100Nm 3 / h, gas flow rate is 100Nm 3 / h, add 1000kg of lime.

[0078] When the power consumption is greater than 20000kWh, the power supply is stopped, the furnace wall gun is adjusted to the holding mode, and the main oxygen flow rate is controlled at 100Nm 3 / h, auxiliary oxygen is controlled at 100Nm 3 / h, gas flow rate is 100Nm 3 / h; open the furnace cover and add the scrap steel of the second material bag. After the scrap steel is added, close the furnace cover and turn on the power, and turn on the three furnace wall cluster oxygen guns to preheat the scrap steel; when the total power consumption is greater than 23000kWh, the three furnace wall oxygen guns start the blowing mode, and add 1200kg of lime at the same time; when the power consumption is greater than 30000kWh, open the furnace wall carbon powder gun to start spraying carbon powder, and the carbon powder spraying flow rate is controlled at 1.0kg / t﹒min; at the same time, according to the foam slag situation, add lime in multiple batches, 300kg of lime is added in each batch, and the final slag basicity is controlled at 3.2. Electric furnace smelting, regarding the steel-out temperature, the final phosphorus, sulfur and nitrogen contents are shown in Table 2:

[0079] Table 2

[0080]

[0081] When the electric arc furnace is one-third of the way through, add low-nitrogen recarburizer to the ladle, add metal manganese for pre-degassing, and add low-titanium and low-aluminum ferrosilicon. After the steel is tapped, add low-nitrogen recarburizer to the ladle and control the bottom blowing argon flow rate. The amount of recarburizer and alloy added during the steel tapping process, the amount of recarburizer added after the steel is tapped, and the bottom blowing control mode are shown in Table 3:

[0082] Table 3

[0083]

[0084] The ladle is hoisted into the LF refining station, synthetic slag is added, the power is turned on to increase the temperature, and SiC is added to diffuse and deoxidize the slag. Lime is added to control the slag basicity and the bottom blowing argon flow rate. The synthetic slag, SiC, lime, slag basicity and bottom blowing control are shown in Table 4:

[0085] Table 4

[0086]

[0087] Temperature measurement and sampling, according to the composition of the molten steel sample and the requirements of the steel grade, add the remaining low-nitrogen recarburizer, metallic manganese and low-titanium low-aluminum ferrosilicon to adjust the composition. After the composition is adjusted, the temperature of the molten steel is controlled in an appropriate range. Soft stirring is used to remove inclusions, and the argon gas at the bottom of the ladle is gradually reduced to a soft stirring state, and the soft stirring time is controlled. The recarburizer, alloy, molten steel temperature, soft stirring bottom blowing flow rate and soft stirring time are shown in Table 5:

[0088] Table 5

[0089]

[0090] Then enter the continuous casting machine casting process, the continuous casting machine is a straight arc rectangular billet continuous casting machine, the continuous casting billet cross-sectional size is 300mm×390mm, the arc radius is 12.5m. Set the continuous casting tundish tonnage to 19t, the tundish tonnage to 35t during normal casting, and the tundish tonnage to 32t during continuous casting and changing tundishes. Control the molten steel superheat of the tundish to 28℃, and the continuous casting speed to 0.6m / min. The section reduction, reduction roller pressure, mold protective slag layer thickness, long water inlet argon flow, mold electromagnetic current, mold frequency, and mold water volume are shown in Table 6:

[0091] Table 6

[0092]

[0093] The secondary cooling section adopts weak cooling mode, and the water volume of the secondary cooling section from zone 1 to zone 4 is: 80 NL / min in zone 1, 45NL / min in zone 2, 30NL / min in zone 3, and 25 NL / min in zone 4. The final C segregation of the ingot is 0.98, which greatly reduces the formation of precipitate inclusions.

[0094] In the process of blanking and rolling, the blanking heating temperature, rolling heating temperature, rolling temperature and wire laying temperature of the blanking into 140mm×140mm are set as shown in Table 7:

[0095] Table 7

[0096]

[0097] Finally, the example of high carbon steel wire is obtained as shown in Table 8.

[0098] Table 8

[0099]

[0100] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for smelting high-quality high-carbon steel wire with all scrap steel, characterized in that: The production is carried out according to the process flow of electric arc furnace smelting - electric arc furnace steel tapping - LF refining - large square billet continuous casting - billet opening - high-speed wire rolling. The specific steps are: Step 1: Electric Arc Furnace Smelting Step 1.1: Scrap steel in batches: The scrap steel is divided into two batches and added into the furnace through the material bag respectively. The first material bag is added with 10t-12t of clean scrap steel crushing material, 2.5t-2.8t of carburizer, 15t-17t of high carbon scrap steel, 18t-20t of clean scrap steel briquettes, 13t-15t of high carbon scrap steel and 9t-10t of clean scrap steel crushing material from bottom to top; the second material bag is added with 4t-5t of clean scrap steel crushing material, 29t-30t of high carbon scrap steel and 4t-5t of clean scrap steel briquettes from bottom to top; the total loading amount of scrap steel is 110t±2t, the loading amount of scrap steel in the first bag is 65t-70t, and the rest is loaded into the second bag; Step 1.2: Smelting of the first batch of scrap steel: After the first batch of scrap steel is added to the electric arc furnace, close the furnace cover, lower the electrode to energize, and turn on the three furnace wall cluster oxygen lances to preheat the scrap steel. Each furnace wall cluster oxygen lance has three channels: main oxygen, auxiliary oxygen and fuel gas. The main oxygen flow rate and auxiliary oxygen flow rate of the furnace wall cluster oxygen lance are 200Nm 3 / h—250Nm 3 / h, gas flow rate is 400Nm 3 / h—500Nm 3 / h; when the total power consumption is greater than 6000kWh, the three furnace wall oxygen lances start blowing mode, and the main oxygen flow rate is controlled at 1200Nm 3 / h—1400Nm 3 / h, auxiliary oxygen is controlled at 100Nm 3 / h—120Nm 3 / h, gas flow rate is 100Nm 3 / h—120Nm 3 / h, add 1000kg-1200kg of lime; Step 1.3: Smelting of the second batch of scrap steel: When the power consumption is greater than 20,000 kWh, stop supplying power, and adjust the furnace wall cluster oxygen lance to the holding mode; open the furnace cover to add the scrap steel of the second material bag, close the furnace cover after the scrap steel is added, and turn on the power, and open the three furnace wall cluster oxygen lances to preheat the scrap steel; when the total power consumption is greater than 23,000 kWh, the three furnace wall cluster oxygen lances start the blowing mode, and add 1,200 kg to 1,500 kg of lime at the same time; when the power consumption is greater than 30,000 kWh, open the furnace wall carbon powder gun to start spraying carbon powder, and the carbon powder spraying flow rate is controlled at 0.9 kg / t﹒ min-1.0 kg / t﹒ min; at the same time, according to the foam slag situation, add lime in multiple batches, 200 kg to 300 kg of lime is added in each batch, and the final slag basicity is controlled at 2.8 to 3.2; Step 1.4: The final tapping temperature of the electric arc furnace smelting is greater than 1600°C, the final carbon content is greater than 0.04%, the final phosphorus content is less than 0.012%, the nitrogen content is less than 50ppm, and the sulfur content is less than 0.012%; The thickness of clean scrap steel entering the furnace is ≥3.0mm, and the chemical composition includes S content ≤0.005%, Ni content ≤0.01%, Cr content ≤0.03%, Cu content ≤0.01%, Al content ≤0.01%, and Ti content ≤0.01%; the thickness of high carbon scrap steel entering the furnace is ≥3.0mm, and the chemical composition includes C content>0.7%, S content<0.012%, Ni content ≤0.03%, Cr content ≤0.03%, Cu content ≤0.05%, Al content ≤0.01%, and Ti content ≤0.01%; The carbon content of the recarburizer added to the electric furnace in step 1.1 is greater than 95%, and the sulfur content is less than 0.20%; Step 2: Electric Arc Furnace Steelmaking Step 2.1: When one third of the steel is tapped from the electric arc furnace, add 300kg-350kg of low nitrogen carburizer to the ladle; add manganese metal for pre-deoxidation, the amount of manganese metal added is 3kg / t-4kg / t; add low titanium and low aluminum ferrosilicon, the amount of low titanium and low aluminum ferrosilicon added is 1.5 kg / t-2kg / t; The low nitrogen recarburizer added during steel tapping in step 2.1 has a carbon content greater than 95%, a sulfur content less than 0.20%, and a nitrogen content less than 0.02%; Step 2.2: After steel tapping is completed, 400kg to 450kg of low nitrogen carburizer is added to the ladle, and the bottom blowing argon flow rate is 400 NL / min-600 NL / min; Step 3: LF Refining Step 3.1: The ladle is hoisted into the LF refining station, 1.8t~2t synthetic slag is added, the power is turned on to increase the temperature, 100kg~150kg of SiC is added to diffuse and deoxidize the slag; 50kg~100kg of lime is added, the slag basicity is controlled to 0.92~1.05, and the bottom blowing argon flow rate is controlled at 600NL / min~800NL / min; Step 3.2: Take samples by temperature measurement, and add the remaining low-nitrogen carburizer, metallic manganese and low-titanium and low-aluminum ferrosilicon to adjust the composition according to the composition of the molten steel sample and the requirements of the steel grade; Step 3.3: After the composition is adjusted, the temperature of the molten steel is controlled at 1525℃~1535℃; Step 3.4: After the composition adjustment is completed, soft stirring is performed to remove inclusions, and the argon gas blowing at the bottom of the ladle is gradually reduced to a soft stirring state, with a flow rate of 60 NL / min-110NL / min, and the soft stirring time is controlled at 26min-31min; Step 4: Bloom continuous casting: Bloom continuous casting machine is used for casting, and the casting is protected during the whole casting process. Low basicity and low alumina tundish covering agent is used, and the superheat of molten steel in the tundish is controlled at 20℃~30℃. Low melting point crystallizer protection slag is used, and electromagnetic stirring of the crystallizer is used; the water volume of the crystallizer is 2975 L / min-3025L / min; the second cooling section adopts weak cooling mode, and the water volume of the second cooling section from zone 1 to zone 4 is respectively: 60 NL / min-100 NL / min in zone 1, 20 NL / min-50 NL / min in zone 2, 20 NL / min-40 NL / min in zone 3, and 10 NL / min-30 NL / min in zone 4; Step 5: Blanking process: the blanking heating temperature is 1180℃-1250℃; Step 6: High-speed wire rolling process: heating temperature is 1080℃-1160℃, rolling temperature is 960℃-1030℃, and spinning temperature is 860℃-920℃.

2. The method for smelting high-quality high-carbon steel wire rods from all scrap steel according to claim 1, characterized in that: In step 1.3, the furnace wall cluster oxygen lance is kept in the mode, and the main oxygen flow rate is 100Nm 3 / h—120Nm 3 / h, auxiliary oxygen 100Nm 3 / h—120Nm 3 / h, gas flow rate 50Nm 3 / h—100Nm 3 / h; In step 1.3, the main oxygen flow rate of the furnace wall cluster oxygen lance blowing mode is 1200Nm 3 / h—1400Nm 3 / h, auxiliary oxygen flow rate 100Nm 3 / h—120Nm 3 / h, gas flow 100Nm 3 / h—120Nm 3 / h.

3. The method for smelting high-quality high-carbon steel wire rods from all scrap steel according to claim 1, characterized in that: In the electric furnace smelting process in step 1, the injection amount of carbon powder during the electric furnace smelting process is controlled at 20 kg / t to 22 kg / t.

4. The method for smelting high-quality high-carbon steel wire rods from all scrap steel according to claim 1, characterized in that: The components of the synthetic slag have a mass percentage of: SiO2 content of 45%-49%, CaO content of 38%-43%, Al2O3 content of 1%-4%, MgO content of 4%-7%, T.Fe content ≤1%, MnO content ≤2%, and other inevitable impurity components.

5. The method for smelting high-quality high-carbon steel wire rods from all scrap steel according to claim 1, characterized in that: The continuous casting machine is a straight arc rectangular billet continuous casting machine, the cross-sectional dimensions of the continuous casting billet are 300 mm×390 mm, and the arc radius is 12.5 m.

6. The method for smelting high-quality high-carbon steel wire rods from all scrap steel according to claim 1, characterized in that: The tonnage of the continuous casting tundish is ≥18t when starting to pour, ≥35t when pouring normally, and ≥30t when changing tundishes for continuous casting.

7. The method for smelting high-quality high-carbon steel wire rods from all scrap steel according to claim 1, characterized in that: During the continuous casting process, the argon flow rate of the ladle long shroud is 250 NL / min-350NL / min; the thickness of the mold protective slag layer is maintained at 15mm-22mm, and the added amount is 0.25 kg / t-0.35kg / t.

8. The method for smelting high-quality high-carbon steel wire rods from all scrap steel according to claim 1, characterized in that: The continuous casting billet is lightly pressed in a tension and leveling machine, with a total pressing amount of 8 mm-15 mm and a pressing roller pressure of 30 bar-40 bar.

9. The method for smelting high-quality high-carbon steel wire rods from all scrap steel according to claim 1, characterized in that: The crystallizer electromagnetic stirring current is 400A-600A, the frequency is 5 Hz-7 Hz, the continuous casting speed is controlled at 0.5 m / min-0.7 m / min, and the C segregation of the cast billet is 0.95-1.

05.

10. A high-quality high-carbon steel wire, characterized in that: The high-quality high-carbon steel wire is obtained by the full scrap steel smelting method described in any one of claims 1 to 9.

11. The high-quality high-carbon steel wire according to claim 10, characterized in that: In terms of mass percentage, the high-quality high-carbon steel wire, in addition to Si, Mn, Cr, V alloy elements and Fe elements, also includes the following chemical components in terms of mass percentage: C: 0.7%-0.9%, P≤0.015%, S≤0.012%, TO≤0.0020%, N≤0.005%, Alt≤0.0015%, Ti≤0.0005%, Ni≤0.02%, Cu≤0.015%, Mo≤0.005%, Sn≤0.010% and As≤0.008%.

12. The high-quality high-carbon steel wire according to claim 10, characterized in that: The inclusions in the high-quality high-carbon steel wire include SiO2-MnO-Al2O3 low-melting-point inclusions, and the number density of inclusions larger than 1 μm is ≤5 / mm 2 , the number density of inclusions larger than 5μm is ≤0.12 / mm 2 The maximum size of transverse inclusions is ≤15μm, the rating of longitudinal inclusions A, B, C, D, and Ds are all ≤1, and the size of brittle inclusions is ≤5μm.

Images