Production method for controlling hydrogen content in high-carbon manganese steel

Abstract

The invention relates to the technical field of metallurgy, in particular to a production method for controlling the hydrogen content in high-carbon manganese steel. According to the method, the packaging specification of the metallurgical auxiliary materials is improved, and the field storage time and the water content of the metallurgical auxiliary materials, the temperature of terminal molten steel of an electric arc furnace, and the adding time and the adding sequence of all materials in the steel ladle pre-deoxidation, precipitation deoxidation and alloying procedures are controlled; in the LF refining process, foam white slag is rapidly formed, the thickness, the components and the retention time of the foam white slag are controlled, the silicon-calcium wire feeding time and the flow of soft blowing argon are controlled, the baking time and the baking temperature of a tundish are controlled in the continuous casting process, casting is protected in the whole process, the fluctuation range of the liquid level of a crystallizer is controlled, and the slow cooling time is prolonged. The hydrogen control mechanism and the hydrogen removal mechanism are closely linked with all the processes, the hydrogen content of the obtained casting blank is reduced to 4.5 ppm or below, air holes, cracks and other defects do not appear on the surface of the casting blank, and subsurface bubbles of 0.5 grade or above do not appear on the low magnification of the casting blank.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a production method for controlling the hydrogen content in high-carbon manganese steel. Background Art

[0002] Hydrogen in steel will have an adverse effect on the mechanical properties and corrosion resistance of steel. The main sources of hydrogen in molten steel include: rust on the surface of scrap steel, hydrogen in ferroalloys, moisture in lime, carburizer, deoxidizer, covering agent and protective slag, moisture in undried ladle and tundish, and moisture in the atmosphere that reacts with molten steel or slag and enters the steel.

[0003] Since the solubility of hydrogen dissolved in steel in liquid steel is higher than that in solid steel, hydrogen in liquid steel will precipitate during the solidification of molten steel. Due to the small radius of hydrogen atoms, the precipitated hydrogen atoms diffuse and aggregate at the grain boundary or inclusion interface to form hydrogen molecules, thereby causing defects such as pores on the surface of the ingot, cracks in the ingot, and subcutaneous bubbles. The hydrogen that is not precipitated in time before the molten steel solidifies and is sealed in the solid steel will reduce the strength, cross-sectional shrinkage, elongation, and impact toughness of the steel. According to research by Yi Lianggang and others, the average hydrogen content of 5.0ppm in steel is the main cause of the pore defects of the ingot, and high carbon manganese steel is more sensitive to hydrogen due to its high carbon content and low alloy content. Therefore, it is of great significance to reduce the hydrogen content of high carbon manganese steel to 5.0ppm to reduce the defects of high carbon manganese steel ingots and improve the comprehensive performance of steel for the production of high carbon manganese steel.

[0004] At present, if the hydrogen content in high carbon manganese steel is to be reduced to below 5.0ppm, the molten steel needs to be vacuum treated, but vacuum treatment increases the steelmaking process and costs. However, if conventional processes are used without vacuum treatment to remove hydrogen, the hydrogen content in the molten steel can be as high as 7-8ppm, especially in the rainy season every year in my country, causing batch quality problems in the ingots. Summary of the invention

[0005] In view of this, the present invention provides a production method for controlling the hydrogen content in high carbon manganese steel. The method does not require vacuum treatment, but only controls the parameters in the furnace auxiliary materials, precise arc furnace steel alloying process, LF refining process and continuous steel casting process, so as to reduce the hydrogen content in the high carbon manganese steel continuous casting round billet to below 4.5ppm.

[0006] In order to solve the above technical problems, the present invention provides a production method for controlling the hydrogen content in high carbon manganese steel, including controlling the auxiliary materials entering the furnace, the arc furnace steel alloying process, the LF refining process and the continuous steel casting process, and the specific steps are as follows:

[0007] S1. The control of the auxiliary materials entering the furnace is to control the on-site storage time, packaging specifications and moisture content of the auxiliary materials;

[0008] S2, in the electric arc furnace steel tapping alloying process, after smelting in the electric arc furnace, an electric arc furnace terminal molten steel with a C content of 0.08-0.20%, a P content of ≤0.010%, and a temperature of ≥1610°C is obtained, and the steel is tapped; when the tapping reaches 5%-10%, silicon carbide is added to the ladle for pre-deoxidation, when the tapping reaches 14%-23%, aluminum ingots are added to the ladle to start precipitation deoxidation, and then a carburizer is added, and when the tapping reaches 28%-41%, refined slag and silicon-manganese alloy are added to the ladle, and then fluorite and lime are added, and all materials are added before the tapping reaches 65%, to obtain a metallurgical melt;

[0009] S3, in the LF refining process, lime and refined slag are added to the metallurgical melt to make slag, aluminum particles and calcium carbide are used for rapid deoxidation to form foamy white slag 8 minutes before smelting in the refining process, and silicon carbide is used to maintain the foamy white slag, and the refining time of the foamy white slag is ≥20 minutes, and silicon-calcium wire is fed into the molten steel after LF is turned off and before steel is tapped, a covering agent is added to evenly cover the slag surface, and argon gas is used for soft blowing, and the soft blowing time is ≥10 minutes;

[0010] S4. In the continuous steel casting process, the baking time of the tundish is controlled to be 5.0-6.0h, the baking temperature is ≥1100°C, full-process protective pouring is adopted, protective slag is automatically added, and the crystallizer liquid level fluctuation range is ±3mm; finally, the continuously cast round billet is put into the pit for slow cooling, and the slow cooling time is ≥72h.

[0011] The invention closely links the hydrogen control and dehydrogenation mechanism with each process by improving the packaging specifications of metallurgical auxiliary materials, controlling the on-site storage time and water content of metallurgical auxiliary materials, the temperature of the terminal molten steel of the electric arc furnace, the timing and order of adding various materials in the ladle pre-deoxidation, precipitation deoxidation and alloying processes, quickly forming foamy white slag and controlling the thickness, components and retention time of the foamy white slag in the LF refining process, controlling the feeding time of silicon calcium wire and the flow rate of soft blowing argon gas, controlling the baking time and baking temperature of the tundish in the continuous casting process, adopting full-process protective casting, controlling the fluctuation range of the liquid level of the crystallizer and extending the slow cooling time, thereby reducing the hydrogen content of the finished molten steel, reducing the defects of the casting billet and improving various properties of the steel.

[0012] In combination with the first aspect, in step S1, the on-site storage time, packaging specifications and moisture content of the auxiliary materials are controlled as follows: the storage time of lime at the production site is ≤72h, and it is packaged in double-layer moisture-proof ton bags; the storage time of the recarburizer, silicon carbide and calcium carbide at the production site is ≤7 days, and they are packaged in large bags wrapped in small bags, and both the large bags and small bags are double-layered; the moisture content of the recarburizer, silicon carbide, calcium carbide, refining slag, covering agent and protective slag is ≤0.3%.

[0013] Preferably, the outer layer of the double-layer moisture-proof ton bag, large bag and small bag is a polyester fiber bag, and the inner layer is a moisture-proof film or plastic film. The use of double-layer packaging bags can effectively prevent the auxiliary materials from absorbing moisture, reduce the moisture in the auxiliary materials to a minimum from the source, and improve the guarantee for reducing the hydrogen content.

[0014] Preferably, the recarburizer is artificial graphite, with a carbon content greater than 96%, and the rest being impurities. The amount of recarburizer added is determined according to the carbon content in the final steel liquid of the electric arc furnace and the target controlled carbon content.

[0015] Preferably, the covering agent can be a high-basicity covering agent, and its chemical composition is: CaO 40%-48%, Al2O3 18%-25%, SiO2 7%-13%, MgO 3%-11%, C 2%-6%, Fe2O3≤3%; the particle size of the covering agent is 0.5-3mm; the protective slag can be high-carbon steel protective slag, and its chemical composition is: C19%-23%, CaO 24%-29%, Al2O3 5%-10%, SiO2 28%-34%, Na2O+K2O5%-8%, F 4%-7%; the particle size of the protective slag is 0.25-1mm.

[0016] In combination with the first aspect, the chemical composition of the high carbon manganese steel is: 0.45%≤C≤0.55%, 0.15%≤Si≤0.35%, 0.60%≤Mn≤1.00%, P≤0.020%, S≤0.010%, Cr≤0.25%, Ni≤0.25%, Cu≤0.20%, Mo≤0.10%, V≤0.05%, 0.008%≤Al≤0.04%, N≤0.0090%, O≤0.0040%, and the remainder of Fe and impurity elements.

[0017] In combination with the first aspect, in step S2, scrap steel and briquettes are used as raw materials, and graphite ore with a carbon content of 80% to 90% is used to control the average carbon content of the charge added to the electric arc furnace to 1.2% to 1.8%. The scrap steel and briquettes are melted and heated by power supply, natural gas and oxygen blowing to produce foamed slag, dephosphorize, and blow oxygen to decarbonize, so as to obtain electric arc furnace terminal molten steel with a C content of 0.08% to 0.20%, a P content of ≤0.010%, and a temperature of ≥1610°C.

[0018] By controlling the carbon content to 1.2% to 1.8% through carbon blending, the discharge of hydrogen and nitrogen gases can be ensured, while reducing the oxidation loss of iron elements. The carbon content at the end of the electric arc furnace is controlled between 0.08% and 0.20% to avoid overoxidation of the molten steel and control the oxygen content in the molten steel at the end of the electric arc furnace.

[0019] Preferably, the pressing blocks are pressed from industrial waste materials such as hot and cold plates, flower iron and galvanized plates.

[0020] In combination with the first aspect, in step S2, when the total amount of steel produced is 85-89t, the amount of silicon carbide added is 20-40kg, the amount of aluminum ingot added is 60-100kg, the amount of carburizer added is 320-380kg, the amount of fluorite added is 40-80kg, the amount of refined slag added is 300-400kg, the amount of lime added is 400-500kg, and the amount of silicon-manganese alloy added is 900-1000kg. The chemical composition of the refined slag is: CaO 32%-40%, Al2O3 46%-54%, SiO2 2%-8%, MgO 1%-3%; the particle size of the refined slag is 5-50mm.

[0021] The main purpose of adding silicon carbide is to react it with oxygen in the molten steel to generate CO and SiO2. The generated CO can provide a protective atmosphere, which can alleviate the air absorption of the molten steel to a certain extent. The generated SiO2 further stabilizes the SiO2 content in the ladle slag between 6% and 10%.

[0022] The added aluminum ingot is in direct contact with the molten steel to ensure rapid melting of the aluminum ingot. Under the conditions of steel flow impact and argon stirring, the deoxidation reaction proceeds rapidly to ensure the pre-deoxidation effect. At this time, the inclusions produced by deoxidation are large particles of Al2O3 that are easy to float and be discharged.

[0023] Fluorite is added to reduce the viscosity of the ladle slag, which facilitates the floating and discharge of inclusions and gases.

[0024] The addition of refined slag is mainly to control the Al2O3 content in the ladle slag between 25% and 30% and the SiO2 content between 6% and 10%, so as to ensure that the ladle slag has good desulfurization ability, inclusion adsorption ability and gas discharge ability.

[0025] The main purpose of adding lime is to control the CaO content in the ladle slag to 50% to 60%, so that the ladle slag has a good ability to absorb inclusions and discharge gas.

[0026] Through the ladle pre-deoxidation and alloying process, the ladle slag has good solubility, fluidity and appropriate basicity when it reaches the LF refining station, and the color is grayish white or yellowish white.

[0027] In combination with the first aspect, in step S3, when the electric arc furnace is tapping steel to the LF refining station, argon gas is connected, and the flow rate of the argon gas is controlled at 300-350NL / min.

[0028] The stirring and floating of argon bubbles in the steel are beneficial to the discharge of gas and inclusions. After escaping, the argon covers the surface of the molten steel, which can prevent the molten steel from secondary oxidation and gas absorption. Controlling the argon flow rate at 300-350NL / min is beneficial to the rapid shell breaking of the ladle slag without exposing the slag surface of the molten steel, thereby reducing the air intake of the molten steel.

[0029] In combination with the first aspect, in step S3, the amount of additional lime added is 270-350kg, the amount of refined slag added is 80-120kg, the amount of aluminum particles added is 10-20kg, the amount of calcium carbide added is 20-30kg, and the amount of silicon carbide added is 30-40kg; the content of each component of the foamed white slag is controlled within the following range: CaO 50%-60%, SiO2 6%-10%, Al2O3 25%-30%, MgO4%-8%, FeO≤0.4%, MnO≤0.3%, CaF2 2%-5%, and the thickness of the foamed white slag is 120-140mm.

[0030] Adding lime can ensure the total slag amount and slag layer thickness, improve the desulfurization effect, and avoid electrode arc exposure during power transmission, ionized gas, and cause steel liquid to absorb air; adding refined slag can ensure the basicity and viscosity of the slag, enhance the desulfurization effect and gas discharge; the aluminum particles, calcium carbide, and silicon carbide can float in the slag layer of the ladle, quickly remove oxygen in the ladle slag, and form foamy white slag.

[0031] In combination with the first aspect, step S3 also includes, after the foamed white slag is made, sampling and analysis are performed, and alloy and carburizer are added according to the analysis results. When adding alloy and carburizer, the flow rate of argon is controlled to be 270-330NL / min, and then silicon carbide is added according to the amount of added alloy and carburizer to maintain the foamed white slag.

[0032] When adding alloy and carburizer, adjust the argon flow rate to 270-330NL / min to accelerate the reaction rate of slag, promote the removal of inclusions and gas in the molten steel, melt the alloy quickly, and make the composition and temperature of the molten steel uniform.

[0033] In combination with the first aspect, in step S3, calcium silicon wire is fed to make the Ca content in the finished molten steel be between 0.0010% and 0.0018%. Controlling the calcium content within this range has the best effect on modifying inclusions, and the inclusions in the molten steel are better controlled.

[0034] Preferably, the amount of the silicon-calcium wire fed is 80-100 m, and the wire feeding speed is 3.0-3.2 m / s. The wire feeding amount can satisfy the Ca content in the range of 0.0010% to 0.0018%.

[0035] Preferably, the soft blowing argon flow rate is controlled at 6-8NL / min. Controlling the argon flow rate at 6-8NL / min only causes slight fluctuations in the slag surface of the foamy white slag in the ladle, thereby ensuring the soft blowing effect of the molten steel and promoting the flotation and discharge of inclusions and gas in the molten steel.

[0036] Preferably, in the continuous steel casting process, the high carbon steel protective slag is baked in a baking oven for 2 to 3 hours, the baking temperature is 80 to 100° C., the amount of protective slag added is 95 to 110 g / min, and the total thickness of the protective slag layer is 45 to 55 mm.

[0037] The baking temperature and baking time can ensure that the moisture content in the protective slag is below 0.30%, and can also ensure that the contents of Na2O, K2O and F in the protective slag do not change.

[0038] The amount of mold slag added can ensure that the total thickness of the mold slag layer is 45-55mm. The total thickness of the slag layer can make the mold slag melt evenly in the crystallizer, stabilize the liquid slag layer, and maintain a certain powder slag layer, which plays a role in heat insulation and reducing steel liquid absorption. If the mold slag layer is too thick, it will affect the workers' correct judgment of the steel liquid level and may cause accidents.

[0039] In combination with the first aspect, in step S4, the surface temperature of the continuous casting round billet when entering the pit for slow cooling is ≥550°C, which can avoid the rapid cooling of the billet at high temperature to generate large thermal stress and structural stress. After at least 72 hours of slow cooling, the billet temperature drops below 200°C, which promotes the release of hydrogen and stress in the billet. This temperature ensures that the billet completes the martensitic phase transformation.

[0040] The beneficial effects of the present invention are as follows: the hydrogen content of the high-carbon manganese steel continuous casting round billet produced by the above-mentioned production method for controlling the hydrogen content in high-carbon manganese steel can be guaranteed to be below 4.5ppm, no defects such as pores and cracks appear on the surface of the billet, no subcutaneous bubbles of level 0.5 or above appear at low magnification of the billet, and the proportion of subcutaneous bubbles drops to 0.5%. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] Example 1

[0043] This embodiment provides a method for producing hydrogen content in high carbon manganese steel, wherein the produced steel grade is 50Mn, comprising the following steps:

[0044] S1. Control the auxiliary materials entering the furnace: confirm that the storage time of lime at the production site is ≤72h, and the storage time of recarburizer, silicon carbide and calcium carbide at the production site is ≤7 days; lime is packed in double-layer moisture-proof ton bags with outer polyester fiber bag + inner moisture-proof film, and recarburizer, silicon carbide and calcium carbide are packed in large bags wrapped in small bags. Both large bags and small bags are double-layered, with the outer layer of polyester fiber and the inner layer of plastic film; confirm that the moisture content of recarburizer, silicon carbide, calcium carbide, refining slag, covering agent and protective slag is ≤0.3%.

[0045] S2. Put the smelting raw materials (75% scrap steel and 25% briquettes) into the furnace body and send electricity for smelting. Use graphite ore with a carbon content of 80% to 90% to control the average carbon content of the charge added to the electric arc furnace to 1.2% to 1.8%. Use electricity, natural gas and oxygen blowing to melt and heat the smelting raw materials, make foamy slag, dephosphorize, and blow oxygen to decarbonize, and obtain the electric arc furnace terminal molten steel with a C content of 0.15%, a P content of 0.0076%, and a temperature of 1613°C, and tap the steel.

[0046] When the steel is tapped to 7t, silicon carbide is added to the ladle for pre-deoxidation. When the steel is tapped to 16t, aluminum ingots are added to the ladle to start precipitation deoxidation, and then a carburizer is added. When the steel is tapped to 30t, refined slag and silicon-manganese alloy are added to the ladle, and then fluorite and lime are added. All materials are added before the steel is tapped to 56t to obtain a metallurgical melt. The total amount of steel tapped is 87t, of which 30kg of silicon carbide, 80kg of aluminum ingots, 360kg of carburizer, 952kg of silicon-manganese alloy, 60kg of fluorite, 350kg of refined slag, and 450kg of lime are added.

[0047] S3, connect argon gas, and control the flow rate at 320NL / min, add 310kg lime and 100kg refined slag to the metallurgical melt to make slag, add 15kg aluminum particles and 25kg calcium carbide 8min before smelting in the refining process to quickly deoxidize and form foamy white slag. After the foamy white slag is made, sample and analyze, add 73kg high carbon ferromanganese and 20kg carburizer according to the analysis results, control the flow rate of argon gas to 300NL / min when adding high carbon ferromanganese and carburizer, and then add 35kg silicon carbide according to the amount of high carbon ferromanganese and carburizer, keep the foamy white slag, and refine the foamy white slag for 23min. The content of the foamy white slag is analyzed and tested as follows: CaO 57.2%, SiO2 8.4%, Al2O3 25.9%, MgO 5.3%, FeO 0.25%, MnO 0.23%, CaF2 2.3%, and the thickness is 128mm.

[0048] After LF is turned off and before steel is tapped, 90m of silicon calcium wire is fed into the molten steel at a feeding speed of 3m / s, and the Ca content in the finished molten steel is 0.0014%. High basicity covering agent is added to evenly cover the slag surface, and argon gas is used for soft blowing at a flow rate of 6NL / min for 18 minutes.

[0049] S4. Carry out continuous steel casting process, control the baking time of the tundish to 5.5h, the baking temperature to 1156℃, adopt full-process protective pouring, automatically add protective slag, bake the protective slag at 90℃ in the baking oven for 2.5h, the protective slag addition amount is 98-106g / min, the total thickness of the protective slag layer is controlled at 47-53mm, and the crystallizer liquid level fluctuation range is within ±3mm; put the continuously cast round billet into the pit for slow cooling for 74h when the surface temperature is in the range of 553-576℃.

[0050] Example 2

[0051] This embodiment provides a method for producing hydrogen content in high carbon manganese steel, wherein the produced steel grade is 50Mn, comprising the following steps:

[0052] S1. Control the auxiliary materials entering the furnace: confirm that the storage time of lime at the production site is ≤72h, and the storage time of recarburizer, silicon carbide and calcium carbide at the production site is ≤7 days; lime is packed in double-layer moisture-proof ton bags with outer polyester fiber bag + inner moisture-proof film, and recarburizer, silicon carbide and calcium carbide are packed in large bags wrapped in small bags. Both large bags and small bags are double-layered, with the outer layer of polyester fiber and the inner layer of moisture-proof film; confirm that the moisture content of recarburizer, silicon carbide, calcium carbide, refining slag, covering agent and protective slag is ≤0.3%.

[0053] S2. Put the smelting raw materials (76% scrap steel and 24% briquettes) into the furnace body and send electricity for smelting. Use graphite ore with a carbon content of 80% to 85% to control the average carbon content of the charge added to the electric arc furnace to 1.2 to 1.5%. Use electricity, natural gas and oxygen blowing to melt and heat the smelting raw materials, make foamy slag, dephosphorize, and blow oxygen to decarbonize, and obtain the electric arc furnace terminal molten steel with a C content of 0.18%, a P content of 0.0083%, and a temperature of 1616°C, and tap the steel.

[0054] When the steel is tapped to 5t, silicon carbide is added to the ladle for pre-deoxidation. When the steel is tapped to 13t, aluminum ingots are added to the ladle to start precipitation deoxidation, and then a carburizer is added. When the steel is tapped to 25t, refined slag and silicon-manganese alloy are added to the ladle, and then fluorite and lime are added. All materials are added before the steel is tapped to 58t to obtain a metallurgical melt. The total amount of steel tapped is 89t, the amount of silicon carbide added is 20kg, the amount of aluminum ingot added is 60kg, the amount of carburizer added is 360kg, the amount of silicon-manganese alloy added is 945kg, the amount of fluorite added is 40kg, the amount of refined slag added is 300kg, and the amount of lime added is 400kg.

[0055] S3, connect argon gas, and control the flow rate at 310NL / min, add 270kg lime and 80kg refined slag to the metallurgical melt to make slag, add 10kg aluminum particles and 20kg calcium carbide to quickly deoxidize and form foamy white slag 8min before smelting in the refining process. After the foamy white slag is made, sample and analyze, add 65kg high carbon ferromanganese and 15kg carburizer according to the analysis results, control the flow rate of argon gas to 290NL / min when adding high carbon ferromanganese and carburizer, then add 30kg silicon carbide according to the amount of high carbon ferromanganese and carburizer, keep the foamy white slag, and refine the foamy white slag for 20min. The content of the foamy white slag is analyzed and tested as follows: CaO 56.5%, SiO27.9%, Al2O3 27.2%, MgO 4.6%, FeO 0.31%, MnO 0.27%, CaF2 2.8%, and the thickness is 124mm.

[0056] After LF is turned off and before tapping, 80m of silicon calcium wire is fed into the molten steel at a feeding speed of 3.2m / s, and the Ca content in the finished molten steel is 0.0012%. High basicity covering agent is added to evenly cover the slag surface, and argon gas is used for soft blowing at a flow rate of 8NL / min for 15 minutes.

[0057] S4. Carry out continuous steel casting process, control the baking time of the tundish to 5.0h, the baking temperature to 1132℃, adopt full-process protective pouring, automatically add protective slag, bake the protective slag at 80℃ in a baking oven for 3h, add 96-105g / min of protective slag, control the total thickness of the protective slag layer to 46-53mm, and keep the crystallizer liquid level fluctuation range within ±3mm; put the continuously cast round billet into the pit for slow cooling for 78h when the surface temperature is 561-584℃.

[0058] Example 3

[0059] This embodiment provides a method for producing hydrogen content in high carbon manganese steel, wherein the produced steel grade is 50Mn, comprising the following steps:

[0060] S1. Control the auxiliary materials entering the furnace: confirm that the storage time of lime at the production site is ≤72h, and the storage time of recarburizer, silicon carbide and calcium carbide at the production site is ≤7 days; lime is packed in double-layer moisture-proof ton bags with outer polyester fiber bag + inner moisture-proof film, and recarburizer, silicon carbide and calcium carbide are packed in large bags wrapped in small bags. Both large bags and small bags are double-layered, with the outer layer of polyester fiber and the inner layer of moisture-proof film; confirm that the moisture content of recarburizer, silicon carbide, calcium carbide, refining slag, covering agent and protective slag is ≤0.3%.

[0061] S2. Put the smelting raw materials (72% scrap steel and 28% briquettes) into the furnace body and send electricity for smelting. Use graphite ore with a carbon content of 85% to 90% to control the average carbon content of the charge added to the electric arc furnace to 1.5 to 1.8%. Use electricity, natural gas and oxygen blowing to melt and heat the smelting raw materials, make foamy slag, dephosphorize, and blow oxygen to decarbonize, and obtain the electric arc furnace terminal molten steel with a C content of 0.13%, a P content of 0.0067%, and a temperature of 1621°C, and tap the steel.

[0062] When the steel is tapped to 8.5t, silicon carbide is added to the ladle for pre-deoxidation. When the steel is tapped to 19t, aluminum ingots are added to the ladle to start precipitation deoxidation, and then 360kg of carburizer is added. When the steel is tapped to 34t, refined slag and 969kg of silicon-manganese alloy are added to the ladle, and then fluorite and lime are added. All materials are added before the steel is tapped to 55t to obtain a metallurgical melt. The total amount of steel tapped is 85t, the amount of silicon carbide added is 40kg, the amount of aluminum ingot added is 100kg, the amount of carburizer added is 360kg, the amount of silicon-manganese alloy added is 969kg, the amount of fluorite added is 80kg, the amount of refined slag added is 400kg, and the amount of lime added is 500kg.

[0063] S3, connect argon gas, and control the flow rate at 320NL / min, add 350kg lime and 120kg refined slag to the metallurgical melt to make slag, add 20kg aluminum particles and 30kg calcium carbide to quickly deoxidize and form foamy white slag 8min before smelting in the refining process. After the foamy white slag is made, sample and analyze, add 58kg high carbon ferromanganese and 20kg carburizer according to the analysis results, control the flow rate of argon gas to 310NL / min when adding alloy and carburizer, then add 40kg silicon carbide according to the amount of high carbon ferromanganese and carburizer, keep the foamy white slag, refine the foamy white slag for 25min, analyze and test the content of the foamy white slag: CaO 55.8%, SiO27.6%, Al2O3 29.2%, MgO 4.3%, FeO 0.28%, MnO 0.23%, CaF2 2.5%, thickness is 137mm.

[0064] After LF is turned off and before tapping, 100m of calcium silicon wire is fed into the molten steel at a feeding speed of 3.2m / s, and the Ca content in the finished molten steel is 0.0016%. High basicity covering agent is added to evenly cover the slag surface, and argon gas is used for soft blowing for 13 minutes with a flow rate controlled at 8NL / min.

[0065] S4. Carry out continuous steel casting process, control the baking time of the tundish to 5.8h, the baking temperature to 1236℃, adopt full-process protective pouring, automatically add protective slag, bake the protective slag at 100℃ in the baking oven for 2h, the amount of protective slag added is 95-108g / min, the total thickness of the protective slag layer is controlled at 45-55mm, and the crystallizer liquid level fluctuation range is within ±3mm; put the continuously cast round billet into the pit for slow cooling for 75h when the surface temperature is 559-582℃.

[0066] Comparative Example 1

[0067] This comparative example provides a method for producing hydrogen content in high carbon manganese steel. The steel produced is the same as that in Example 1, and the steps are similar to those in Example 1, except that step S3 is:

[0068] Steps S1, S2 and S4 are the same as S1, S2 and S4 in Example 1.

[0069] S3, connect argon gas, and control the flow rate at 320NL / min, add 400kg lime and 150kg refined slag to the metallurgical melt to make slag, add 30kg aluminum particles and 30kg calcium carbide to quickly deoxidize and form foamy white slag 8min before smelting in the refining process. After the foamy white slag is made, sample and analyze, add 66kg high carbon ferromanganese and 15kg carburizer according to the analysis results, control the flow rate of argon gas to 310NL / min when adding high carbon ferromanganese and carburizer, then add 20kg silicon carbide according to the amount of high carbon ferromanganese and carburizer, keep the foamy white slag, and refine the foamy white slag for 23min. The content of the foamy white slag is analyzed and tested as follows: CaO 61.6%, SiO2 5.3%, Al2O3 27.5%, MgO 3.2%, FeO 0.24%, MnO 0.21%, CaF2 1.2%, and the thickness is 134mm.

[0070] After LF is turned off and before tapping, 90m of silicon calcium wire is fed into the molten steel at a feeding speed of 3m / s, and the Ca content in the finished molten steel is 0.0015%. High basicity covering agent is added to evenly cover the slag surface, and argon gas is used for soft blowing for 15 minutes with a flow rate controlled at 8NL / min.

[0071] Comparative Example 2

[0072] This comparative example provides a method for producing hydrogen content in high carbon manganese steel. The steel produced is the same as that in Example 1, and the steps are similar to those in Example 1, except that step S3 is:

[0073] Steps S1, S2 and S4 are the same as S1, S2 and S4 in Example 1.

[0074] S3, connect argon gas, and control the flow rate at 320NL / min, add 80kg lime and 30kg refined slag to the metallurgical melt to make slag, add 30kg aluminum particles and 20kg calcium carbide to quickly deoxidize and form foamy white slag 8min before smelting in the refining process. After the foamy white slag is made, sample and analyze, add 54kg high carbon ferromanganese and 20kg carburizer according to the analysis results, control the flow rate of argon gas to 280NL / min when adding high carbon ferromanganese and carburizer, then add 10kg silicon carbide according to the amount of high carbon ferromanganese and carburizer, keep the foamy white slag, and refine the foamy white slag for 23min. The content of the foamy white slag is analyzed and tested as follows: CaO 57.5%, SiO26.0%, Al2O3 28.1%, MgO 5.1%, FeO 0.23%, MnO 0.26%, CaF2 2.6%, and the thickness is 94mm.

[0075] After LF is turned off and before tapping, 90m of silicon calcium wire is fed into the molten steel at a feeding speed of 3m / s, and the Ca content in the finished molten steel is 0.0012%. High basicity covering agent is added to evenly cover the slag surface, and argon gas is soft-blown for 16 minutes with a flow rate controlled at 6NL / min.

[0076] Comparative Example 3

[0077] This comparative example provides a method for producing hydrogen content in high carbon manganese steel. The steel produced is the same as that in Example 1, and the steps are similar to those in Example 1, except that step S4 is:

[0078] Steps S1, S2 and S3 are the same as S1, S2 and S3 in Example 1.

[0079] S4. Carry out continuous steel casting process, control the baking time of the tundish to 5.5h, the baking temperature to 1159℃, adopt full-process protective pouring, automatically add protective slag, bake the protective slag at 90℃ in the baking oven for 2.5h, the amount of protective slag added is 98-107g / min, the total thickness of the protective slag layer is controlled at 45-51mm, and the crystallizer liquid level fluctuation range is within ±3mm; put the continuously cast round billet into the pit for slow cooling for 25h when the surface temperature is 561-584℃.

[0080] Test example

[0081] The hydrogen content in the continuous casting round billets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was tested respectively, and the pores, cracks on the billet surface and the low-magnification inspection of the billet (intermediate cracks, subcutaneous cracks and subcutaneous bubbles) were observed. The results are shown in Table 1.

[0082] Table 1

[0083]

[0084]

[0085] It can be seen from Table 1 that the hydrogen content of the ingots in the embodiments within the control parameter range of the present invention is below 4.5ppm, there are no pores on the surface of the ingot, no intermediate cracks at low magnification, and the maximum level of subcutaneous bubbles at low magnification is 0.5; when the foamy white slag component, the thickness of the foamy white slag, and the slow cooling time do not meet the control parameter range (Comparative Examples 1 to 3), the quality of the ingot is significantly deteriorated, the hydrogen content is above 5.0ppm, the level of subcutaneous bubbles at low magnification is high, there are pores on the surface of the ingot or there are intermediate cracks of level 0.5 at low magnification.

[0086] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A production method for controlling the hydrogen content in high carbon manganese steel, characterized in that: It includes the control of the auxiliary materials entering the furnace, the alloying process of the electric arc furnace steel, the LF refining process and the continuous steel casting process. The specific steps are as follows: S1. The control of the auxiliary materials entering the furnace is to control the on-site storage time, packaging specifications and moisture content of the auxiliary materials; S2, in the electric arc furnace steel tapping alloying process, after smelting in the electric arc furnace, an electric arc furnace terminal molten steel with a C content of 0.08% to 0.20%, a P content of ≤0.010%, and a temperature of ≥1610°C is obtained, and the steel is tapped; when the tapping reaches 5% to 10%, silicon carbide is added to the ladle for pre-deoxidation, when the tapping reaches 14% to 23%, aluminum ingots are added to the ladle to start precipitation deoxidation, and then a carburizer is added, and when the tapping reaches 28% to 41%, refined slag and silicon-manganese alloy are added to the ladle, and then fluorite and lime are added, and all materials are added before the tapping reaches 65%, to obtain a metallurgical melt; S3, in the LF refining process, lime and refined slag are added to the metallurgical melt to make slag, aluminum particles and calcium carbide are used for rapid deoxidation to form foamy white slag 8 minutes before smelting in the refining process, and silicon carbide is used to maintain the foamy white slag, and the refining time of the foamy white slag is ≥20 minutes, and silicon-calcium wire is fed into the molten steel after LF is turned off and before steel is tapped, a covering agent is added to evenly cover the slag surface, and argon gas is used for soft blowing, and the soft blowing time is ≥10 minutes; S4. In the continuous steel casting process, the baking time of the tundish is controlled to be 5.0-6.0h, the baking temperature is ≥1100°C, full-process protective pouring is adopted, protective slag is automatically added, and the crystallizer liquid level fluctuation range is ±3mm; finally, the continuously cast round billet is put into the pit for slow cooling, and the slow cooling time is ≥72h.

2. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 1, characterized in that: In step S1, the on-site storage time, packaging specifications and moisture content of the auxiliary materials are controlled specifically as follows: the storage time of lime at the production site is ≤72h, and it is packaged in double-layer moisture-proof ton bags; the storage time of the recarburizer, silicon carbide and calcium carbide at the production site is ≤7 days, and they are packaged in large bags wrapped in small bags, and both the large bags and small bags are double-layered; the moisture content of the recarburizer, silicon carbide, calcium carbide, refining slag, covering agent and protective slag is ≤0.3%.

3. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 1, characterized in that: The chemical composition of the high carbon manganese steel is: 0.45%≤C≤0.55%, 0.15%≤Si≤0.35%, 0.60%≤Mn≤1.00%, P≤0.020%, S≤0.010%, Cr≤0.25%, Ni≤0.25%, Cu≤0.20%, Mo≤0.10%, V≤0.05%, 0.008%≤Al≤0.04%, N≤0.0090%, O≤0.0040%, and the remainder of Fe and impurity elements.

4. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 1, characterized in that: In step S2, scrap steel and briquettes are used as raw materials, and graphite ore with a carbon content of 80% to 90% is used to control the average carbon content of the charge added to the electric arc furnace to 1.2% to 1.8%. The scrap steel and briquettes are melted and heated by power supply, natural gas and oxygen blowing to produce foamed slag, dephosphorize, and blow oxygen to decarbonize, so as to obtain electric arc furnace terminal molten steel with a C content of 0.08% to 0.20%, a P content of ≤0.010%, and a temperature of ≥1610°C.

5. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 1, characterized in that: In step S2, when the total amount of steel produced is 85-89t, the amount of silicon carbide added is 20-40kg, the amount of aluminum ingot added is 60-100kg, the amount of recarburizer added is 320-380kg, the amount of fluorite added is 40-80kg, the amount of refined slag added is 300-400kg, the amount of lime added is 400-500kg, and the amount of silicon-manganese alloy added is 900-1000kg.

6. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 1, characterized in that: In step S3, when the electric arc furnace is tapped to the LF refining station, argon gas is connected, and the flow rate of the argon gas is controlled at 300-350 NL / min.

7. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 1, characterized in that: In step S3, the amount of additional lime added is 270-350kg, the amount of refined slag added is 80-120kg, the amount of aluminum particles added is 10-20kg, the amount of calcium carbide added is 20-30kg, and the amount of silicon carbide added is 30-40kg; the content of each component of the foamed white slag is controlled within the following range: CaO 50%-60%, SiO2 6%-10%, Al2O3 25%-30%, MgO 4%-8%, FeO≤0.4%, MnO≤0.3%, CaF2 2%-5%, and the thickness of the foamed white slag is 120-140mm.

8. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 6 or 7, characterized in that: Step S3 also includes, after the foamed white slag is made, sampling and analysis are performed, and alloy and carburizer are added according to the analysis results. When adding alloy and carburizer, the flow rate of argon is controlled to be 270-330NL / min, and then silicon carbide is added according to the amount of added alloy and carburizer to maintain the foamed white slag.

9. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 1, characterized in that: In step S3, calcium silicon wire is fed to make the Ca content in the finished molten steel be between 0.0010% and 0.0018%.

10. The production method for controlling the hydrogen content in high carbon manganese steel according to claim 1, characterized in that: In step S4, the surface temperature of the continuously cast round billet when entering the pit for slow cooling is ≥550°C.

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