RH aluminum heating method for ultra-low carbon steel

Abstract

The invention discloses an ultra-low carbon steel RH aluminum heating method which comprises the following steps: when more than half of converter tapping is carried out, 1-2kg / (t.steel) active lime is added into a steel ladle, and then 1.5-2.5 kg / (t.steel) aluminum-containing modifier is added; after converter tapping is completed, 0.5-1 kg / (t.steel) of active lime is added into a steel ladle; after RH decarburization is finished, metal needed by RH aluminum heating treatment, RH aluminum deoxidation treatment and in-steel adjustment is added into molten steel in a vacuum chamber at a time, then RH aluminum heating treatment, RH aluminum deoxidation treatment and in-steel adjustment are conducted, and the oxygen blowing amount needed by oxygen blowing aluminum heating is controlled to be smaller than or equal to 1.0 m < 3 > / (t.steel); limestone is added into molten steel in a vacuum chamber, active lime is added to the surface of steel ladle top slag for slag adjusting treatment, and the steel ladle top slag is required to be within the range of 1.2-1.8. According to the method, RH refined aluminum heating and precise cooperative control over refining slag components and fluidity are achieved, and the requirements of ultra-low carbon steel production for the temperature, components and cleanliness of molten steel are met.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and particularly relates to a method for heating ultra-low carbon steel with RH aluminum. Background Technology

[0002] The RH refining furnace is an important piece of equipment for producing high-grade ultra-low carbon steel products. With the rapid development of the automotive and home appliance markets, extremely high requirements have been placed on the control of the content of elements such as C and N in ultra-low carbon steel products, as well as the size, quantity and type of inclusions in the steel. The RH refining process is the key process to complete the above control tasks.

[0003] When producing ultra-low carbon steel using the RH refining process, the RH inlet temperature is often low. Therefore, it is necessary to use aluminum-oxygen blowing to raise the temperature of the molten steel in the RH refining furnace. However, during the RH aluminum heating process, a large number of Al2O3 inclusions will appear in the steel. If these inclusions cannot be quickly floated and removed, they will remain in the steel and will very likely cause inclusion defects on the surface of the cold-rolled sheet, thus affecting the steel yield.

[0004] For example, patent document CN117701827A discloses a low-cost RH oxygen blowing heating method. This method, targeting furnaces requiring aluminum heating, calculates the amount of silicon carbide or ferrosilicon added and the amount of oxygen blown in based on the heating amount. After aluminum deoxidation, slag-forming material is added, and the resulting new slag layer isolates silicon oxides from the aluminum-containing molten steel, reducing silicon enrichment and compensating for insufficient silicon content, effectively lowering the cost of RH heating. However, using SiC or ferrosilicon to heat the steel will generate SiO2 inclusions, significantly increasing the SiO2 content in the ladle slag. During subsequent steel casting, this easily leads to secondary oxidation of Al in the molten steel, resulting in [Al]... S Increased burn-off and higher inclusion defect rate are detrimental to improving the cleanliness of molten steel.

[0005] Patent document CN101392311A discloses an RH-OB steel refining method; it involves adding Al and oxygen blowing to raise the temperature, while simultaneously adding remelted slag with a particle size of 10-20 mm at 0.7-1.4 times the amount of Al added. The remelted slag contains 45%-49% CaO, 42%-48% Al2O3, 2%-6% MgO, and 1%-3% SiO2, preventing the formation of Al2O3 cluster inclusions in the steel and minimizing the area of ​​Al2O3 inclusions. The fraction was reduced to 0.0020%, and the total oxygen was reduced to 0.0015%~0.0020%, which greatly reduced the amount of scrap generated by Al2O3 inclusions on the surface of cold-rolled plates. However, this method does not specify the amount of oxygen blown or the specific amount of Al added for RH-OB oxygen blowing heating. It only limits the amount and composition of remelting slag. Obviously, this cannot achieve precise control over the cleanliness of molten steel and the refining slag system. At the same time, if the amount of remelting slag added is too large, it will cause the temperature drop of the molten steel to be too high, which will also be detrimental to the smooth operation of production.

[0006] Therefore, there is an urgent need for a method that can achieve precise control of temperature and composition and ensure the cleanliness of steel during the heating process of RH aluminum. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a method for heating ultra-low carbon steel with RH aluminum, which can facilitate precise control of temperature and composition and ensure the cleanliness of the steel.

[0008] The objective of this invention is achieved through the following technical solution: A method for heating ultra-low carbon steel to RH aluminum includes the following steps: When more than half of the steel has been tapped from the converter, add 1~2 kg / (t·steel) of active lime and 1.5~2.5 kg / (t·steel) of aluminum-containing modifier into the ladle. After the converter tapping is completed, add 0.5~1 kg / (t·steel) of active lime to the ladle, and control the ladle top slag thickness to be 60~120 mm before tapping. Content of 300~500ppm, steel tapping Content of 300~600ppm in ladle top slag Content ≤6% and in ladle top slag ≥2.0; After RH decarburization and control, the oxygen activity of the molten steel is 200~300ppm; In a vacuum chamber, RH aluminum is added to molten steel for a one-time heating treatment, RH aluminum deoxidation treatment, and steel incorporation. Adjust the required metal Then, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel processing are carried out. Adjustment; Limestone is added to the molten steel in the vacuum chamber, and active lime is added to the surface of the top slag of the ladle for slag conditioning treatment; Add alloy circulation to the molten steel in the vacuum chamber for 6-8 minutes until the RH refining is completed, and then let the ladle out of the station and calm it for 15-30 minutes.

[0009] Furthermore, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel... Adjust the total metal required quantity The calculation formula is:

[0010] in, Metals required for RH aluminum heating treatment quantity, Metals required for RH aluminum deoxidation treatment quantity, For steel Adjust the required metal quantity; Metals required for RH aluminum heating treatment quantity The calculation formula is:

[0011] in, The total mass of the molten steel. Let be the specific heat capacity of molten steel, and take it as 0.84 kJ / (kg·℃). For the target continuous casting temperature, The temperature of the molten steel at the end of RH decarburization. The temperature drop during the process from the end of RH decarburization to continuous casting. To determine the maximum temperature drop caused by adding limestone to molten steel, and taking the maximum temperature drop caused by adding 3 kg / (t·steel) of limestone as 9℃. The heat released by the aluminum-oxygen reaction in steel is taken as 28981 kJ / kg. The heat utilization coefficient for RH aluminum heating treatment is taken as 0.7~0.9; Metals required for RH aluminum deoxidation quantity The calculation formula is:

[0012] in, This represents the oxygen content in the steel at the end of RH decarburization. The target oxygen content at the end of RH aluminum deoxidation is ≤0.002%; Steel Adjust the required metal quantity The calculation formula is:

[0013] in, For steel Content control target value, For RH refining to continuous casting The loss value is ≤0.01%.

[0014] Furthermore, the oxygen blowing volume required for RH aluminum heating treatment The calculation formula is:

[0015] in, The oxygen yield from RH aluminum heating treatment is taken as 0.75~0.95%.

[0016] Furthermore, the RH aluminum heating treatment employs top-gun oxygen blowing with the oxygen blowing volume controlled to ≤1m³. 3 / (t·steel).

[0017] Furthermore, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel... Generate and remove when loss occurs Total amount of inclusions The calculation formula is as follows:

[0018] in, for The relative molecular mass, for relative atomic mass, For steel Loss amount is ≤100ppm. For generated The proportion of total impurities removed by upward floating is taken as 70% to 80%.

[0019] Furthermore, the slag treatment required Amount added The calculation formula is:

[0020] in, Ladle top slag after RH refining top slag modification The target value is set between 1.2 and 1.8. The density of steel slag is taken as 3000 kg / m³. 3 , The surface area of ​​the top slag of the ladle. The thickness of the top slag of the ladle, For the top slag of the steel ladle entering the RH refining station The mass fraction, For the top slag of the steel ladle entering the RH refining station The quality score.

[0021] Furthermore, the amount of limestone required for slag treatment. The calculation formula is:

[0022] in, This refers to the amount of active lime required for slag treatment. In limestone The quality score.

[0023] Furthermore, the formula for calculating the effect of RH aluminum heating treatment on the temperature rise of molten steel is as follows:

[0024] in, The heating effect of RH aluminum heating treatment on molten steel; RH aluminum deoxidation treatment and steel Loss causes the molten steel to heat up The calculation formula is as follows:

[0025] in, Dissolved in steel The heat utilization coefficient of the reaction process with dissolved oxygen is taken as 0.8~1; The decrease in molten steel temperature caused by the addition of limestone The calculation formula is:

[0026] in, In limestone The mass fraction, In limestone The decomposition reaction absorbs heat, which is taken as 1780 kJ / kg. In limestone The thermal efficiency of decomposition is taken as 0.5~0.8; The formula for calculating the overall molten steel temperature control effect in RH refining is:

[0027] in, The effect of temperature control of total molten steel in RH refining.

[0028] Furthermore, the addition of limestone reduces the carbon content of molten steel. The calculation formula is:

[0029] in, for relative atomic mass, For generated and The reaction limit is ≤1%. for The relative molecular mass.

[0030] Furthermore, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel... After adjustment, the molten steel is circulated for 3-4 minutes, then limestone is added to the molten steel in the vacuum chamber, and active lime is added to the surface of the top slag of the ladle for slag adjustment.

[0031] The beneficial effects of this invention are as follows: This invention employs top slag modification to control the thickness, final carbon and oxygen content, and composition of the ladle top slag during converter tapping. This effectively avoids the problem of strong oxidation of the ladle top slag caused by excessive oxygen content at the converter endpoint and excessive slag discharge. Reasonable lime consumption can eliminate the risk of slag caking caused by excessive lime addition. This invention relates to RH aluminum heating treatment based on the temperature requirements of continuous casting steel grades, and specifically addresses the RH aluminum heating treatment of metals. Addition amount, oxygen blowing amount during RH aluminum heating treatment, deoxidation and steel Demand is precisely controlled to meet the temperature and composition requirements of molten steel in the continuous casting process. In the RH refining process, the proportion of active lime and limestone with calcium carbonate as the main component is precisely adjusted to significantly enhance the fluidity of ladle top slag and its ability to dissolve inclusions in steel, thereby ensuring the smooth production of high-purity molten steel. The present invention adds a large amount of calcium carbonate to the limestone added to molten steel, which decomposes to produce calcium carbonate. Microbubbles enhance the agitation of molten steel and promote the flotation and removal of inclusions, effectively improving the cleanliness of the molten steel. They also enhance the RH degassing effect, thus contributing to the purification of ultra-low carbon steel. and Elemental depth removal. Attached Figure Description

[0032] The invention will now be described in more detail with reference to embodiments and the accompanying drawings. Figure 1 A flowchart of the present invention is shown; In the accompanying drawings, the same parts use the same reference numerals. The drawings are not to scale. Detailed Implementation

[0033] The invention will now be further described with reference to the accompanying drawings.

[0034] This invention provides a method for heating ultra-low carbon steel with RH aluminum, such as... Figure 1 As shown, it includes the following steps: When more than half of the steel has been tapped from the converter, add 1~2 kg / (t·steel) of active lime and 1.5~2.5 kg / (t·steel) of aluminum-containing modifier into the ladle. After the converter tapping is completed, add 0.5~1 kg / (t·steel) of active lime to the ladle, and control the ladle top slag thickness to be 60~120 mm before tapping. Content of 300~500ppm, steel tapping Content of 300~600ppm in ladle top slag Content ≤6% and in ladle top slag ≥2.0; After RH decarburization and control, the oxygen activity of the molten steel is 200~300ppm; Based on the temperature requirements of the steel grades in continuous casting, RH aluminum is added to the molten steel in the vacuum chamber at one time for heating treatment, RH aluminum deoxidation treatment, and steel middlings treatment. Adjust the required metal Then, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel processing are carried out. Adjustment; Limestone is added to the molten steel in the vacuum chamber, and active lime is added to the surface of the top slag of the ladle for slag conditioning treatment; Add titanium alloys or other alloys to the molten steel in the vacuum chamber and circulate for 6-8 minutes until the RH refining is completed. After the ladle leaves the station, it is calmed for another 15-30 minutes before being sent to the continuous casting process to complete the steel pouring task.

[0035] In one embodiment, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel... Adjust the total metal required quantity The calculation formula is:

[0036] in, Metals required for RH aluminum heating treatment quantity, Metals required for RH aluminum deoxidation treatment quantity, For steel Adjust the required metal quantity, , , and The units are all in kg; Based on the molten steel temperature at the end of RH decarburization, the target continuous casting temperature, the temperature drop during the process from the end of RH decarburization to continuous casting, and the maximum temperature drop of the molten steel caused by adding limestone, calculate the metal required for RH aluminum heating treatment. Quantity; Metal required for RH aluminum heating treatment quantity The calculation formula is:

[0037] in, The total mass of the molten steel is expressed in kg. The specific heat capacity of molten steel is taken as 0.84 kJ / (kg·℃); The target continuous casting temperature is expressed in °C. The temperature of the molten steel at the end of RH decarburization is expressed in °C. The temperature drop from the end of RH decarburization to continuous casting is expressed in °C. To determine the maximum temperature drop caused by adding limestone to molten steel, and taking the maximum temperature drop caused by adding 3 kg / (t·steel) of limestone as 9℃. The heat released by the aluminum-oxygen reaction in steel is taken as 28981 kJ / kg. The heat utilization coefficient for RH aluminum heating treatment is taken as 0.7~0.9; Calculate the required metal for RH aluminum deoxidation treatment based on the oxygen content in the steel at the end of RH decarburization and the target oxygen content at the end of RH aluminum deoxidation. Quantity; Metals required for RH aluminum deoxidation treatment quantity The calculation formula is:

[0038] in, The oxygen content in the steel at the end of RH decarburization is expressed in % (%). This refers to the target oxygen content at the end of RH aluminum deoxidation, and is generally taken as ≤0.002%. To meet the requirements of steel composition, steel... Adjust the required metal quantity The calculation formula is:

[0039] in, For steel Content control target value, in % For RH refining to continuous casting The loss value is generally ≤0.01%.

[0040] In one embodiment, the RH aluminum heating treatment employs top-gun oxygen blowing with the oxygen blowing volume controlled to be ≤1m³. 3 / (t·steel), oxygen required for RH aluminum heating treatment The calculation formula is:

[0041] in, The unit is m 3 ; The oxygen yield from RH aluminum heating treatment is taken as 0.75~0.95%.

[0042] In one embodiment, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel... Generate and remove when loss occurs Total amount of inclusions The calculation formula is as follows:

[0043] in, The unit is kg; for The relative molecular mass, expressed in g / mol; for The relative atomic mass, expressed in g / mol; For steel Loss amount is ≤100ppm. For generated The proportion of total impurities removed by upward floating is taken as 70% to 80%.

[0044] In one embodiment, the slag treatment requires Amount added The calculation formula is:

[0045] in, The unit is kg; Ladle top slag after RH refining top slag modification The target value is set between 1.2 and 1.8. The density of steel slag is taken as 3000 kg / m³. 3 ; This refers to the surface area of ​​the top slag of the ladle, in m². 2 ; This refers to the thickness of the top slag in the ladle, in mm. For the top slag of the steel ladle entering the RH refining station Mass fraction, expressed as % For the top slag of the steel ladle entering the RH refining station Mass fraction, expressed as %.

[0046] In one embodiment, the amount of limestone required for slag treatment is... The calculation formula is:

[0047] in, The unit is kg; The amount of active lime required for slag conditioning is expressed in kg. In limestone The quality score must be ≥50%.

[0048] In one embodiment, the formula for calculating the heating effect of RH aluminum heating treatment on molten steel is:

[0049] in, The heating effect of RH aluminum heating treatment on molten steel, expressed in °C; RH aluminum deoxidation treatment and steel Loss causes the molten steel to heat up The calculation formula is as follows:

[0050] in, The unit is ℃; Dissolved in steel The heat utilization coefficient of the reaction process with dissolved oxygen is taken as 0.8~1; The main components of the limestone added to the molten steel are , The addition of limestone causes the molten steel to absorb heat and undergo a decomposition reaction, resulting in a decrease in the temperature of the molten steel. The calculation formula is:

[0051] in, The unit is ℃; In limestone The quality score must be ≥95%; In limestone The decomposition reaction absorbs heat, approximately 1780 kJ / kg. In limestone The thermal efficiency of decomposition is taken as 0.5~0.8; The formula for calculating the overall molten steel temperature control effect in RH refining is:

[0052] in, The temperature control effect of RH refining total molten steel is shown in °C.

[0053] In one embodiment, a vacuum chamber The endothermic decomposition produced Under the circulation of RH molten steel, it rapidly reaches the surface of the ladle top slag to complete the slag-forming reaction; the released... In the vacuum chamber, the gas forms numerous tiny bubbles in the molten steel, thereby promoting the degassing process, such as the removal of gas from the molten steel. and take off Etc.; The addition of limestone causes a decrease in carbon content in molten steel. The calculation formula is:

[0054] in, The unit is %; for The relative atomic mass, expressed in g / mol; For generated and The reaction limit is generally ≤1%. for The relative molecular mass, expressed in g / mol; at the same time, Gases enhance the stirring of molten steel and promote the process of steel formation. The inclusions collide and grow, achieving efficient adsorption and removal of inclusions in steel by the top slag of the ladle.

[0055] In one embodiment, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel... After adjustment, the molten steel is circulated for 3-4 minutes. Then, limestone is added to the molten steel in the vacuum chamber, and active lime is added to the surface of the top slag of the ladle for slag conditioning. The amount of limestone added is controlled to be 2.0-3.0 kg / (t·steel), and the limestone particle size is ≤50 mm.

[0056] The first specific embodiment is given below, which uses a converter-RH-continuous casting process to produce DC05 series ultra-low carbon steel. The converter capacity is 200t and the ladle diameter is 2.8m. When the converter has tapped halfway through the tapping process, add 350 kg of quicklime to the ladle, followed by 400 kg of aluminum-containing modifier; at the end of tapping, add another 150 kg of quicklime to the ladle before tapping. The content is 450ppm, and the steel is produced. The content is 500 ppm; the thickness of the ladle top slag reaching the RH process is 100 mm, and the ladle top slag contains... The content is 5.5% in the top slag of the ladle. 2, ladle top slag The content is 50%, ladle top slag The content is 25%; During RH decarburization, the molten steel temperature was 1580℃, and the oxygen activity of the molten steel was 0.028%. The content is 15 ppm in molten steel. The content is 14 ppm; the target continuous casting temperature for this steel grade is 1590℃; the temperature drop from the end of RH decarburization to continuous casting is approximately 10℃; the maximum temperature drop caused by adding limestone to the molten steel is taken as 9℃; calculate the metal required for RH aluminum deoxidation treatment. The volume is 210 kg and the oxygen blowing volume is 145 m³. 3 The target oxygen content at the end of RH aluminum deoxidation is 0.001%. The metal required for RH aluminum deoxidation treatment... The weight is 61 kg; in the steel The content control target value is 0.03%, RH refining to continuous casting The loss value is approximately 0.006% in the steel. Adjust the required metal The quantity is 72 kg; therefore, 343 kg of metal is added at once after RH decarburization is completed. After completing the RH aluminum deoxidation treatment, the granules undergo RH aluminum deoxidation treatment and are then processed in the steel. Adjust and circulate for 3.5 minutes to homogenize the composition and temperature of the molten steel; RH refining top slag modification ladle top slag The target value is 1.6, and aluminum oxide is generated and removed through the reaction. The total amount of inclusions is approximately 401 kg. Based on the slag composition, the required amount for slag conditioning is calculated. The amount added was 457 kg, and ≈96%, therefore, 513 kg of limestone was added from the alloy silo to the molten steel in the vacuum chamber, and 200 kg of active lime was added to the surface of the top slag of the ladle for slag conditioning. After the RH slag treatment is completed, the alloy hopper is added to the alloy circulation for 6 minutes, and the RH refining is completed. The ladle is then left the station and calmed for 25 minutes before reaching the continuous casting process. After the first specific embodiment was applied, the initial steel pouring temperature was 1603℃, and the top slag of the ladle was... Reduced to 1.68, ladle top slag The content is 5.1%, molten steel in the ladle. The content is 13 ppm. The content is 0.031%, in the medium-sized steel package. The inclusion number density decreased to 3.8 inclusions / mm. 2 Zhongbao Steel Reduced to 12 ppm, in medium-sized steel. The content is 13ppm, which meets the temperature and composition requirements for smooth steel production. Furthermore, the molten steel has a high degree of cleanliness during ladle casting, which can improve the RH degassing effect and achieve the RH aluminum heating technology control target.

[0057] The second specific embodiment is given below, which uses a converter-RH-continuous casting process to produce DC06 series ultra-low carbon steel. The converter capacity is 300t and the ladle diameter is 3.1m. When the converter has tapped halfway through the steelmaking process, add 500 kg of quicklime to the ladle, followed by 600 kg of aluminum-containing modifier; at the end of tapping, add another 200 kg of quicklime to the ladle before tapping. The content is 400ppm, and it is produced in steel. The content is 550 ppm; the thickness of the ladle top slag at the RH process is 90 mm, and the ladle top slag contains... The content was 5.1% in the top slag of the ladle. The value is 2.3, and the top slag of the ladle is... The content is 51%, ladle top slag The content is 22%; During RH decarburization, the molten steel temperature was 1575℃, and the oxygen activity of the molten steel was 0.027%. The content is 17 ppm in molten steel. The content is 18 ppm; the target continuous casting temperature for this steel grade is 1585℃; the temperature drop from the end of RH decarburization to continuous casting is approximately 15℃; the maximum temperature drop caused by adding limestone to the molten steel is taken as 9℃; calculate the metal required for RH aluminum deoxidation treatment. The volume is 370 kg and the oxygen blowing volume is 255 m³. 3 The target oxygen content at the end of RH aluminum deoxidation is 0.0015%. The metal required for RH aluminum deoxidation treatment... The weight is 86 kg; in the steel The content control target value is 0.04%, RH refining to continuous casting The loss value is approximately 0.007% in steel. Adjust the required metal The quantity is 141 kg; therefore, 597 kg of metal is added at once after RH decarburization is completed. After completing the RH aluminum deoxidation treatment, the granules undergo RH aluminum deoxidation treatment and are then processed in the steel. Adjust and cycle for 4 minutes to homogenize the composition and temperature of the molten steel; RH refining top slag modification ladle top slag The target value is 1.8, and aluminum oxide is generated and removed through the reaction. The total amount of inclusions is approximately 675 kg. Based on the slag composition, the required amount for slag conditioning is calculated. The amount added was 1039 kg, and ≈96.5%, therefore, 766 kg of limestone was added from the alloy silo to the molten steel in the vacuum chamber, and 600 kg of active lime was added to the surface of the top slag of the ladle for slag conditioning treatment. After the RH slag treatment is completed, the alloy hopper is added to the alloy circulation for 7 minutes, and the RH refining is completed. The ladle is then left the station and calmed for 28 minutes before reaching the continuous casting process. After the second specific embodiment was applied, the initial pouring temperature was 1597℃, and the top slag of the ladle was... The concentration dropped to 1.81, and the top slag of the ladle decreased. The content is 5.3%, molten steel in the tundish. The content is 15 ppm. The content is 0.0395%, in medium-sized steel packages. The inclusion number density decreased to 4.1 inclusions / mm. 2 Zhongbao Steel Reduced to 15.5 ppm, in medium-sized steel. The content is 16.5 ppm, which meets the temperature and composition requirements for smooth steel production. Furthermore, the molten steel has a high degree of cleanliness during ladle casting, which can improve the RH degassing effect and achieve the RH aluminum heating technology control target.

[0058] The third specific embodiment is given below, which uses a converter-RH-continuous casting process to produce DC07 series ultra-low carbon steel. The converter capacity is 120t and the ladle diameter is 2.5m. When the converter has tapped half of the steel, add 240 kg of quicklime to the ladle, followed by 240 kg of aluminum-containing modifier; at the end of tapping, add another 100 kg of quicklime to the ladle before tapping. The content is 420ppm, and the steel is produced. The content is 450 ppm; the thickness of the ladle top slag reaching the RH process is 80 mm, and the ladle top slag contains... The content was 4.8% in the top slag of the ladle. 2.1, ladle top slag The content is 48%, ladle top slag The content is 22.5%; During RH decarburization, the molten steel temperature is 1555℃, the oxygen activity of the molten steel is 0.025%, and the molten steel... The content is 20 ppm in molten steel. The content is 20 ppm; the target continuous casting temperature for this steel grade is 1570℃; the temperature drop from the end of RH decarburization to continuous casting is approximately 8℃; the maximum temperature drop caused by adding limestone to the molten steel is taken as 9℃; calculate the metal required for RH aluminum deoxidation treatment. The volume is 139 kg and the oxygen blowing volume is 96 m³. 3 The target oxygen content at the end of RH aluminum deoxidation is 0.001%. The metal required for RH aluminum deoxidation treatment... The quantity is 32kg; in the steel The content control target value is 0.04%, RH refining to continuous casting The loss value is approximately 0.004% in steel. Adjust the required metal The quantity is 47 kg; therefore, 218 kg of metal is added at once after RH decarburization is completed. After completing the RH aluminum deoxidation treatment, the granules undergo RH aluminum deoxidation treatment and are then processed in the steel. Adjust and cycle for 3.8 minutes to homogenize the composition and temperature of the molten steel; RH refining top slag modification ladle top slag The target value is 1.5, and aluminum oxide is generated and removed through the reaction. The total amount of inclusions is approximately 250 kg. Based on the slag composition, the required amount for slag conditioning is calculated. The amount added was 207 kg, and ≈96%, therefore, 214 kg of limestone was added from the alloy silo to the molten steel in the vacuum chamber, and 100 kg of active lime was added to the surface of the top slag of the ladle for slag conditioning. After the RH slag treatment is completed, the alloy hopper is added to the alloy circulation for 6.5 minutes, and the RH refining is completed. The ladle is discharged from the station and calmed for 21 minutes before arriving at the continuous casting process. After the third specific embodiment was applied, the initial pouring temperature was 1582℃, and the top slag of the ladle was... Dropped to 1.49, ladle top slag The content is 4.9%, molten steel in the ladle. The content is 11 ppm. The content is 0.038%, in medium-sized steel packages. The inclusion number density decreased to 2.5 inclusions / mm. 2 Zhongbao Steel Reduced to 18.5 ppm, in medium-sized steel. The content is 19ppm, which meets the temperature and composition requirements for smooth steel production. Furthermore, the molten steel has a high degree of cleanliness during ladle casting, which can improve the RH degassing effect and achieve the RH aluminum heating technology control target.

[0059] In summary, this invention, by using top slag modification to control the thickness, final carbon and oxygen content, and composition of the ladle top slag during converter tapping, can effectively avoid the problem of strong oxidation of the ladle top slag caused by excessive oxygen content at the converter endpoint and excessive slag discharge. Reasonable lime consumption can eliminate the risk of slag caking caused by excessive lime addition. This invention relates to RH aluminum heating treatment based on the temperature requirements of continuous casting steel grades, and specifically addresses the RH aluminum heating treatment of metals. Addition amount, oxygen blowing amount during RH aluminum heating treatment, deoxidation and steel Demand is precisely controlled to meet the temperature and composition requirements of molten steel in the continuous casting process. In the RH refining process, the proportion of active lime and limestone with calcium carbonate as the main component is precisely adjusted to significantly enhance the fluidity of ladle top slag and its ability to dissolve inclusions in steel, thereby ensuring the smooth production of high-purity molten steel. The present invention adds a large amount of calcium carbonate to the limestone added to molten steel, which decomposes to produce calcium carbonate. Microbubbles enhance the agitation of molten steel and promote the flotation and removal of inclusions, effectively improving the cleanliness of the molten steel. They also enhance the RH degassing effect, thus contributing to the purification of ultra-low carbon steel. and Elemental depth removal; Therefore, this invention facilitates precise control of temperature and composition and ensures the cleanliness of steel.

[0060] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0061] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A method for heating ultra-low carbon steel with RH aluminum, characterized in that, Includes the following steps: When more than half of the steel has been tapped from the converter, add 1~2 kg / (t·steel) of active lime and 1.5~2.5 kg / (t·steel) of aluminum-containing modifier into the ladle. After the converter tapping is completed, add 0.5~1 kg / (t·steel) of active lime to the ladle, and control the ladle top slag thickness to be 60~120 mm before tapping. Content of 300~500ppm, steel tapping Content of 300~600ppm in ladle top slag Content ≤6% and in ladle top slag ≥2.0; After RH decarburization and control, the oxygen activity of the molten steel is 200~300ppm; In a vacuum chamber, RH aluminum is added to molten steel for a one-time heating treatment, RH aluminum deoxidation treatment, and steel incorporation. Adjust the required metal Then, RH aluminum heating treatment, RH aluminum deoxidation treatment, and steel processing are carried out. Adjustment; Limestone is added to the molten steel in the vacuum chamber, and active lime is added to the surface of the top slag of the ladle for slag conditioning treatment; Add alloy circulation to the molten steel in the vacuum chamber for 6-8 minutes until the RH refining is completed, and then let the ladle out of the station and calm it for 15-30 minutes.

2. The method for heating ultra-low carbon steel to RH aluminum according to claim 1, characterized in that, RH aluminum heating treatment, RH aluminum deoxidation treatment and steel Adjust the total metal required quantity The calculation formula is: in, Metals required for RH aluminum heating treatment quantity, Metals required for RH aluminum deoxidation treatment quantity, For steel Adjust the required metal quantity; Metals required for RH aluminum heating treatment quantity The calculation formula is: in, The total mass of the molten steel. Let be the specific heat capacity of molten steel, and take it as 0.84 kJ / (kg·℃). For the target continuous casting temperature, The temperature of the molten steel at the end of RH decarburization. The temperature drop during the process from the end of RH decarburization to continuous casting. To determine the maximum temperature drop caused by adding limestone to molten steel, and taking the maximum temperature drop caused by adding 3 kg / (t·steel) of limestone as 9℃. The heat released by the aluminum-oxygen reaction in steel is taken as 28981 kJ / kg. The heat utilization coefficient for RH aluminum heating treatment is taken as 0.7~0.9; Metals required for RH aluminum deoxidation quantity The calculation formula is: in, This represents the oxygen content in the steel at the end of RH decarburization. The target oxygen content at the end of RH aluminum deoxidation is ≤0.002%; Steel Adjust the required metal quantity The calculation formula is: in, For steel Content control target value, For RH refining to continuous casting The loss value is ≤0.01%.

3. The method for heating ultra-low carbon steel to RH aluminum according to claim 2, characterized in that, Oxygen blowing volume required for RH aluminum heating treatment The calculation formula is: in, The oxygen yield from RH aluminum heating treatment is taken as 0.75~0.95%.

4. The method for heating ultra-low carbon steel to aluminum using RH according to claim 3, characterized in that, RH aluminum heating treatment uses top-gun oxygen blowing with the oxygen blowing volume controlled to ≤1m³. 3 / (t·steel).

5. The method for heating ultra-low carbon steel with RH aluminum according to claim 2, characterized in that, RH aluminum heating treatment, RH aluminum deoxidation treatment and steel Generate and remove when loss occurs Total amount of inclusions The calculation formula is as follows: in, for The relative molecular mass, for relative atomic mass, For steel Loss amount is ≤100ppm. For generated The proportion of total impurities removed by upward floating is taken as 70% to 80%.

6. The method for heating ultra-low carbon steel to aluminum using RH according to claim 5, characterized in that, Slag treatment required Amount added The calculation formula is: in, Ladle top slag after RH refining top slag modification The target value is set between 1.2 and 1.

8. The density of steel slag is taken as 3000 kg / m³. 3 , The surface area of ​​the top slag of the ladle. The thickness of the top slag of the ladle, For the top slag of the steel ladle entering the RH refining station The mass fraction, For the top slag of the steel ladle entering the RH refining station The quality score.

7. The method for heating ultra-low carbon steel to RH aluminum according to claim 6, characterized in that, The amount of limestone required for slag treatment The calculation formula is: in, This refers to the amount of active lime required for slag treatment. In limestone The quality score.

8. The method for heating ultra-low carbon steel with RH aluminum according to claim 7, characterized in that, The formula for calculating the effect of RH aluminum heating treatment on the temperature rise of molten steel is as follows: in, The heating effect of RH aluminum heating treatment on molten steel; RH aluminum deoxidation treatment and steel Loss causes the molten steel to heat up The calculation formula is as follows: in, Dissolved in steel The heat utilization coefficient of the reaction process with dissolved oxygen is taken as 0.8~1; The decrease in molten steel temperature caused by the addition of limestone The calculation formula is: in, In limestone The mass fraction, In limestone The decomposition reaction absorbs heat, which is taken as 1780 kJ / kg. In limestone The thermal efficiency of decomposition is taken as 0.5~0.8; The formula for calculating the overall molten steel temperature control effect in RH refining is: in, The effect of temperature control of total molten steel in RH refining.

9. A method for heating ultra-low carbon steel to RH aluminum according to claim 7 or 8, characterized in that, The addition of limestone reduces the carbon content of molten steel. The calculation formula is: in, for relative atomic mass, For generated and The reaction limit is ≤1%. for The relative molecular mass.

10. The method for heating ultra-low carbon steel to aluminum using RH according to claim 1, characterized in that, RH aluminum heating treatment, RH aluminum deoxidation treatment and steel After adjustment, the molten steel is circulated for 3-4 minutes, then limestone is added to the molten steel in the vacuum chamber, and active lime is added to the surface of the top slag of the ladle for slag adjustment.

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