Production method for reducing content of oxygen and nitrogen in SWRH82B steel

Abstract

The invention provides a production method for reducing the content of oxygen and nitrogen in SWRH82B steel. According to the method, the oxygen content in the SWRH82B steel can be effectively reduced, meanwhile, stable control over the nitrogen content can be achieved, the wire rod drawing wire breakage rate caused by fluctuation of the oxygen content and the nitrogen content is reduced, the production cost is reduced, the service life of a product is prolonged, and meanwhile the green and environment-friendly sustainable development requirement is met. According to the production method provided by the invention, the content of oxygen and nitrogen in the SWRH82B steel can be reasonably controlled, and through full-process control and reasonable distribution of deoxidation and denitrification capacities among procedures, the wire rod drawing wire breakage rate is reduced, the service life of the wire rod is prolonged, and the use performance of the SWRH82B high-carbon steel wire rod is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of SWRH82B steel ingot production and relates to a production method for reducing oxygen and nitrogen contents in SWRH82B steel. Background Art

[0002] SWRH82B high carbon steel wire rod is mainly used in prestressed steel wire rope, steel strand and other wire products. In the process of product preparation, it needs to be drawn multiple times before it can be used by users. In the drawing process, the problem of wire breakage caused by excessive oxygen and nitrogen content often occurs. Especially with the further reduction of the final drawing diameter of the wire, the high oxygen and nitrogen content will have a serious impact on the wire drawing process and service life. Although there are some improved technical solutions in the existing research, such as CN114908282 discloses a production process for controlling the oxygen and nitrogen content of SWRH42B carbon steel hot-rolled wire rod, although a series of measures are taken to reduce the oxygen and nitrogen content in molten steel, and control O≤40ppm and N≤50ppm in molten steel, as wire products gradually move towards high-end, the requirements for oxygen and nitrogen content in molten steel are more stringent, and the current process cannot meet the development and production of high-end wire products. For example, CN102211159 discloses a method for producing 82B steel strands. By adopting technologies such as argon blowing at the bottom of the converter throughout the process, argon blowing after steel tapping, RH vacuum degassing and inclusion removal, and electromagnetic stirring of the crystallizer, the clean production of 82B steel strands is achieved, and the total oxygen content in the steel is less than 0.0020%. However, the nitrogen content is not controlled. Excessive nitrogen content will increase the timeliness of the wire rod, reduce welding performance, and easily cause wire rod drawing fracture and increase wire breakage rate. In addition, as the final diameter of the product drawing becomes thinner, the total oxygen content in the steel becomes more stringent, and excessive total oxygen will also increase the risk of drawing fracture.

[0003] In addition, such as the "Research on Nitrogen Control Technology of Hard Wire Steel SWRH82B" published in the 6th issue of "Tianjin Metallurgy" in 2021, the "Practice of Controlling Nitrogen Content in SWRH82B Steel Production" published in the 6th issue of "Metallurgy and Materials" in 2023, and the "RH Vacuum Refining Nitrogen Control Process Practice" published in the 3rd issue of "China Metallurgy" in 202, etc., all only selectively control oxygen or nitrogen, and some processes do not consider nitrogen control throughout the entire process, and do not reasonably distribute the deoxidation and denitrification burden of the smelting process.

[0004] Therefore, how to find a more suitable SWRH82B high carbon steel preparation process to solve the above-mentioned problems existing in the existing process has become one of the urgent issues to be solved by many front-line researchers in the industry. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a production method for reducing the oxygen and nitrogen content in SWRH82B steel. The production method provided by the present invention can not only effectively reduce the oxygen content in SWRH82B steel, but also achieve stable control of the nitrogen content, reduce the wire breakage rate caused by fluctuations in oxygen and nitrogen content, achieve a reduction in production costs, and meet the requirements of green and environmentally friendly sustainable development while improving the service life of the product. Moreover, the preparation method has a simple process, good controllability, strong operability, and is more suitable for industrial promotion and application.

[0006] The present invention provides a production method for reducing the oxygen and nitrogen content in SWRH82B steel, comprising the following steps:

[0007] 1) spraying passivation magnesium powder and passivation lime into molten iron to perform KR desulfurization treatment, and then performing slagging treatment to obtain pretreated molten iron;

[0008] The sulfur content in the pretreated molten iron is ≤0.010wt%;

[0009] 2) adopting the top and bottom composite blowing method, pouring the pretreated molten iron and scrap steel obtained in the above steps into a converter for converter smelting, and obtaining molten steel after tapping;

[0010] 3) adding molten steel refining slag conditioning agent, high basicity refined slag, quartz sand and fluorite slag making to the molten steel obtained in the above step, blowing argon gas for LF refining, and obtaining LF refined molten steel;

[0011] 4) The molten steel obtained after LF refining in the above step is subjected to RH vacuum refining under the condition of blowing argon gas to obtain refined molten steel out of the station;

[0012] 5) Pour the refined molten steel obtained in the above steps into a tundish and then cast it to obtain SWRH82B steel ingot.

[0013] Preferably, the addition amount of the passivation magnesium powder is 1.0-1.5 kg / t 钢 ;

[0014] The amount of passivation lime added is 5.0-5.5 kg / t 钢 ;

[0015] The KR method desulfurization treatment time is 5 to 8 minutes;

[0016] The temperature of the molten iron is ≥1320°C.

[0017] Preferably, the slag removal treatment is specifically to remove slag until the exposed molten iron liquid surface area accounts for a ratio of greater than or equal to 75% of the total area;

[0018] The sulfur content in the pretreated molten iron is ≤0.010wt%;

[0019] The scrap steel includes clean scrap steel;

[0020] The mass ratio of molten iron to scrap steel after the pretreatment is (19-22):1.

[0021] Preferably, in the converter smelting, argon gas blowing is used at the bottom of the furnace;

[0022] The flow rate of the argon gas is 1000-1200 NL / min;

[0023] The final carbon content of the converter smelting is 0.10wt% to 0.20wt%;

[0024] The temperature of the steel tapping is 1630-1650°C;

[0025] The time for tapping steel from the converter is 4 to 5 minutes.

[0026] Preferably, the steel tapping process includes a step of adding ferrosilicon alloy for deoxidation when the steel tapping amount is greater than or equal to 25%;

[0027] After the deoxidation, the step of adding silicon-manganese alloy for alloying is also included;

[0028] The amount of silicon-manganese alloy added is 6.0-7.0 kg / t 钢 ;

[0029] The alloying step also includes adding active lime to make slag;

[0030] After the slag making, the step of adding a carburizer to increase carbon is also included.

[0031] Preferably, the amount of the recarburizer added is 5.0-6.0 kg / t 钢 ;

[0032] After the steel is tapped, the step of blowing argon gas into the molten steel is also included;

[0033] The argon blowing process specifically includes adding aluminum and blowing argon;

[0034] The argon blowing time is 6 to 8 minutes;

[0035] The argon gas flow rate of the argon blowing is 100-200 NL / min.

[0036] Preferably, the Al2O3 content of the molten steel refining slag conditioning agent is 50.0wt% to 80.0wt%;

[0037] The amount of the molten steel refining slag conditioning agent added is 200-300kg;

[0038] The specific process of adding is to first add the molten steel refining slag conditioning agent and then heat it up, and then add 2.5-3.5 kg / t 钢 High basicity refined slag, 1.5~2.5kg / t 钢 Quartz sand and 0~1.0kg / t 钢 Fluorite slag making;

[0039] In the step 3), the argon gas flow rate of the argon gas is 100-200 NL / min;

[0040] In the step 3), blowing argon gas is specifically bottom blowing argon gas.

[0041] Preferably, the pressure in the refining furnace of the LF refining is 50-80 kPa;

[0042] The CaO content of the high basicity refined slag is 70.0wt% to 90.0wt%;

[0043] The SiO2 content of the quartz sand is ≥90.0wt%;

[0044] The binary basicity of the slag system in the LF refining process is controlled at 1.5 to 2.5;

[0045] The LF refining temperature is 1565-1585°C.

[0046] Preferably, the RH vacuum refining time is 13 to 18 minutes;

[0047] In the step 4), the argon gas flow rate of the argon gas is 30 to 50 NL / min;

[0048] In the step 4), blowing argon gas is specifically bottom blowing argon gas;

[0049] After the RH vacuum refining, the steps of adding calcium silicon wire and blowing argon gas after adding the calcium silicon wire are also included;

[0050] The time of blowing argon gas after adding calcium silicon wire is 9 to 15 minutes;

[0051] The argon flow rate of the argon gas blown after adding the calcium silicon wire is 50-80NL / min.

[0052] Preferably, the vacuum pressure of the RH vacuum refining is ≤3 mbar;

[0053] The outlet temperature is 1525-1540°C;

[0054] The casting method includes casting using a six-machine six-strand billet continuous casting machine;

[0055] The temperature of the molten steel in the tundish is 1485-1495°C;

[0056] The superheat degree of the molten steel in the tundish is 20-30°C;

[0057] The casting pulling speed is 1.3-1.5 m / min.

[0058] The invention provides a production method for reducing the oxygen and nitrogen content in SWRH82B steel. The method comprises the following steps: firstly, spraying passivation magnesium powder and passivation lime into molten iron for KR desulfurization treatment, and then performing slag removal treatment to obtain pretreated molten iron; the sulfur content in the pretreated molten iron is less than or equal to 0.010wt%; then adopting a top and bottom composite blowing method, pouring the pretreated molten iron and scrap steel obtained in the above steps into a converter for converter smelting, and obtaining molten steel after tapping; then adding molten steel refining slag adjusting agent, high basicity refining slag, quartz sand and fluorite slag making into the molten steel obtained in the above steps, blowing argon gas for LF refining, and obtaining LF refined molten steel; then, the LF refined molten steel obtained in the above steps is subjected to RH vacuum refining under the condition of blowing argon gas, and refined molten steel is obtained after exiting the station; finally, the refined molten steel obtained in the above steps is poured into a tundish, and then cast to obtain a SWRH82B steel ingot. Compared with the prior art, the present invention specially designs a SWRH82B steel ingot production method with specific control parameters and steps, which is particularly used to reduce the oxygen and nitrogen content in SWRH82B steel. The production process of molten iron pretreatment-converter smelting-LF refining-RH refining-square billet continuous casting is adopted. By reducing the sulfur content in the molten iron, the subsequent LF refining desulfurization burden is reduced, the LF refining heating time is reduced, and the LF refining nitrogen increase is reduced; the molten steel is deeply deoxidized by adding ferrosilicon into the converter and adding aluminum wire deoxidation process after the furnace; LF refining produces low-basicity slag, and a calcium treatment process is added to ensure the low melting point liquefaction of inclusions; argon is blown from the bottom during the RH refining process to promote the floating removal of inclusions and the denitrification of molten steel, and a series of measures such as continuous casting protective casting are taken to control the whole process of production, reduce the oxygen and nitrogen content in steel, and improve product quality.

[0059] The production method for reducing the oxygen and nitrogen content in SWRH82B steel provided by the present invention can not only effectively reduce the oxygen content in SWRH82B steel, but also achieve stable control of the nitrogen content, reduce the wire breakage rate in wire rod drawing caused by fluctuations in oxygen and nitrogen content, achieve a reduction in production costs, and meet the requirements of green and environmentally friendly sustainable development while improving the service life of the product. The production method provided by the present invention can reasonably control the oxygen and nitrogen content in SWRH82B steel, and through full-process control and reasonable allocation of deoxidation and denitrification capabilities between processes, thereby reducing the wire breakage rate in wire drawing and improving the service life of the wire, and improving the performance of SWRH82B high-carbon steel wire rods. Moreover, the present invention is not limited to 82B wire products such as prestressed steel wire ropes and steel strands, but can also be used in high-end wire products such as tire meridians and cutting wires.

[0060] Experimental results show that by adopting the production method provided by the present invention, high-quality production of low-oxygen and low-nitrogen SWRH82B steel can be successfully achieved, with the total oxygen content in the steel being ≤0.0015wt% and the nitrogen content in the steel being ≤0.0040wt%. DETAILED DESCRIPTION

[0061] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0062] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0063] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses industrial purity or conventional purity of SWRH82B steel in the casting field.

[0064] The brands and abbreviations of all raw materials of the present invention are conventional brands and abbreviations in the art. Each brand and abbreviation is clear and definite in the field of its related use. Those skilled in the art can purchase them from the market or prepare them by conventional methods according to the brands, abbreviations and corresponding uses.

[0065] The present invention provides a production method for reducing the oxygen and nitrogen content in SWRH82B steel, comprising the following steps:

[0066] 1) spraying passivation magnesium powder and passivation lime into molten iron to perform KR desulfurization treatment, and then performing slagging treatment to obtain pretreated molten iron;

[0067] The sulfur content in the pretreated molten iron is ≤0.010wt%;

[0068] 2) adopting the top and bottom composite blowing method, pouring the pretreated molten iron and scrap steel obtained in the above steps into a converter for converter smelting, and obtaining molten steel after tapping;

[0069] 3) adding molten steel refining slag conditioning agent, high basicity refined slag, quartz sand and fluorite slag making to the molten steel obtained in the above step, blowing argon gas for LF refining, and obtaining LF refined molten steel;

[0070] 4) The molten steel obtained after LF refining in the above step is subjected to RH vacuum refining under the condition of blowing argon gas to obtain refined molten steel out of the station;

[0071] 5) Pour the refined molten steel obtained in the above steps into a tundish and then cast it to obtain SWRH82B steel ingot.

[0072] The present invention first provides a production method for reducing the oxygen and nitrogen content in SWRH82B steel, characterized in that it comprises the following steps:

[0073] 1) spraying passivation magnesium powder and passivation lime into molten iron to perform KR desulfurization treatment, and then performing slagging treatment to obtain pretreated molten iron;

[0074] In the present invention, the sulfur content in the pretreated molten iron is ≤0.010wt%, may be ≤0.009wt%, or may be ≤0.008wt%.

[0075] In the present invention, the addition amount of the passivated magnesium powder is preferably 1.0 to 1.5 kg / t 钢 , more preferably 1.1 to 1.4 kg / t 钢 , more preferably 1.2 to 1.3 kg / t 钢 .

[0076] In the present invention, the amount of passivation lime added is preferably 5.0-5.5 kg / t 钢 , more preferably 5.1-5.4 kg / t 钢 , more preferably 5.2-5.3 kg / t 钢 .

[0077] In the present invention, the time of the KR desulfurization treatment is preferably 5 to 8 minutes, more preferably 5 to 7 minutes, more preferably 5 to 5 minutes, and can be 5 minutes.

[0078] In the present invention, the temperature of the molten iron is preferably ≥1320°C, more preferably ≥1330°C, and more preferably ≥1350°C.

[0079] In the present invention, the slag removal treatment is preferably performed such that the ratio of the area of ​​the molten iron surface exposed by slag removal to the total area is greater than or equal to 75%, more preferably greater than or equal to 77%, and more preferably greater than or equal to 80%.

[0080] In the present invention, the sulfur content in the pretreated molten iron is preferably ≤0.010wt%, more preferably ≤0.009wt%, and more preferably ≤0.008wt%.

[0081] The present invention further adopts a top-bottom composite blowing method, pours the pretreated molten iron and scrap steel obtained in the above steps into a converter for converter smelting, and obtains molten steel after tapping.

[0082] In the present invention, the scrap steel preferably includes clean scrap steel. Specifically, the clean scrap steel ensures that residual elements such as Sn and Cu in the scrap steel do not exceed 0.0005%.

[0083] In the present invention, the mass ratio of the molten iron to the scrap steel after the pretreatment is preferably (19-22):1, more preferably (19.5-21.5):1, and more preferably (20-21):1.

[0084] In the present invention, in the converter smelting, it is preferred to use argon blowing treatment at the bottom of the furnace.

[0085] In the present invention, the flow rate of the argon gas is preferably 1000 to 1200 NL / min, more preferably 1040 to 1160 NL / min, and even more preferably 1080 to 1120 NL / min.

[0086] In the present invention, the final carbon content of the converter smelting is preferably 0.10wt% to 0.20wt%, more preferably 0.12wt% to 0.18wt%, and more preferably 0.14wt% to 0.16wt%.

[0087] In the present invention, the tapping temperature is preferably 1630-1650°C, more preferably 1634-1646°C, and more preferably 1638-1642°C.

[0088] In the present invention, the time for tapping steel from the converter is preferably 4 to 5 minutes, more preferably 4.2 to 4.8 minutes, and more preferably 4.4 to 4.6 minutes.

[0089] In the present invention, the steel tapping process preferably includes a step of adding ferrosilicon alloy for deoxidation when the steel tapping amount is greater than or equal to 25%.

[0090] In the present invention, the deoxidation step preferably further includes adding silicon-manganese alloy for alloying.

[0091] In the present invention, the addition amount of the silicon-manganese alloy is preferably 6.0-7.0 kg / t 钢 , more preferably 6.2 to 6.8 kg / t 钢 , more preferably 6.4 to 6.6 kg / t 钢。

[0092] In the present invention, the step of adding active lime to make slag is preferably included after the alloying.

[0093] In the present invention, the slag making preferably further includes a step of adding a carburizer to increase carburization.

[0094] In the present invention, the amount of the recarburizer added is preferably 5.0-6.0 kg / t 钢 , more preferably 5.2-5.8 kg / t 钢 , more preferably 5.4-5.6 kg / t 钢 .

[0095] In the present invention, after the steel tapping, the step of blowing argon gas into the molten steel is preferably further included.

[0096] In the present invention, the argon blowing process is preferably performed by adding aluminum and then blowing argon.

[0097] In the present invention, the argon blowing time is preferably 6 to 8 minutes, more preferably 6.4 to 7.6 minutes, and more preferably 6.8 to 7.2 minutes.

[0098] In the present invention, the argon gas flow rate of the argon blowing is preferably 100 to 200 NL / min, more preferably 120 to 180 NL / min, and even more preferably 140 to 160 NL / min.

[0099] The present invention then adds molten steel refining slag adjusting agent, high basicity refined slag, quartz sand and fluorite slag making to the molten steel obtained in the above steps, blows argon gas for LF refining, and obtains LF refined molten steel.

[0100] In the present invention, the Al2O3 content of the molten steel refining slag conditioning agent is preferably 50.0wt% to 80.0wt%, more preferably 55.0wt% to 75.0wt%, and more preferably 60.0wt% to 70.0wt%.

[0101] In the present invention, the addition amount of the molten steel refining slag conditioning agent is preferably 200-300 kg, more preferably 200-260 kg, and more preferably 200-220 kg.

[0102] In the present invention, the adding process is preferably to first add the molten steel refining slag conditioning agent and then raise the temperature, and then add 2.5-3.5 kg / t 钢High basicity refined slag, 1.5~2.5kg / t 钢 Quartz sand and 0~1.0kg / t 钢 Fluorite slag making, more preferably adding 2.7-3.3 kg / t in batches 钢 High basicity refined slag, 1.7~2.3kg / t 钢 Quartz sand and 0.2~0.8kg / t 钢 Fluorite slag making, more preferably adding 2.9-3.1 kg / t in batches 钢 High basicity refined slag, 1.9~2.1kg / t 钢 Quartz sand and 0.4~0.6kg / t 钢 Fluorite slag.

[0103] In the present invention, in the step 3), the argon gas flow rate of the argon gas blowing is preferably 100 to 200 NL / min, more preferably 120 to 180 NL / min, and more preferably 140 to 160 NL / min.

[0104] In the present invention, in the step 3), blowing argon is preferably bottom blowing argon.

[0105] In the present invention, the pressure in the refining furnace of the LF refining is preferably 50 to 80 kPa, more preferably 55 to 75 kPa, and even more preferably 60 to 70 kPa.

[0106] In the present invention, the CaO content of the high basicity refined slag is preferably 70.0wt% to 90.0wt%, more preferably 74.0wt% to 86.0wt%, and more preferably 78.0wt% to 82.0wt%.

[0107] In the present invention, the SiO2 content of the quartz sand is preferably ≥90.0wt%, more preferably ≥92.0wt%, and more preferably ≥95.0wt%.

[0108] In the present invention, the binary basicity of the refined slag system in the LF refining process is preferably controlled at 1.5 to 2.5, more preferably at 1.7 to 2.3, and more preferably at 1.9 to 2.1.

[0109] In the present invention, the temperature of LF refining is preferably 1565-1585°C, more preferably 1569-1581°C, and more preferably 1574-1577°C.

[0110] The present invention then conducts RH vacuum refining on the LF refined molten steel obtained in the above steps under the condition of blowing argon gas, and obtains the refined molten steel out of the station.

[0111] In the present invention, the pressure in the refining furnace of the LF refining is preferably 50 to 80 kPa, more preferably 55 to 75 kPa, and even more preferably 50 to 70 kPa.

[0112] In the present invention, the CaO content of the high basicity refined slag is preferably 70.0wt% to 90.0wt%, more preferably 74.0wt% to 86.0wt%, and more preferably 78.0wt% to 82.0wt%.

[0113] In the present invention, the SiO2 content of the quartz sand is preferably ≥90.0wt%, more preferably ≥92.0wt%, and more preferably ≥94.0wt%.

[0114] In the present invention, the binary basicity of the refined slag system in the LF refining process is preferably controlled at 1.5 to 2.5, more preferably at 1.7 to 2.3, and more preferably at 1.9 to 2.1.

[0115] In the present invention, the temperature of LF refining is preferably 1565-1585°C, more preferably 1569-1581°C, and more preferably 1574-1577°C.

[0116] In the present invention, the RH vacuum refining time is preferably 13 to 18 minutes, more preferably 14 to 17 minutes, and more preferably 15 to 16 minutes.

[0117] In the present invention, in the step 4), the argon gas flow rate of the argon gas blowing is preferably 30 to 50 NL / min, more preferably 34 to 46 NL / min, and more preferably 38 to 42 NL / min.

[0118] In the present invention, in the step 4), blowing argon is preferably bottom blowing argon.

[0119] In the present invention, after the RH vacuum refining, the steps of preferably adding calcium silicon wire and blowing argon gas after adding the calcium silicon wire are also included.

[0120] In the present invention, the time for blowing argon gas after adding the calcium silicon wire is preferably 9 to 15 minutes, more preferably 10 to 14 minutes, and more preferably 11 to 13 minutes.

[0121] In the present invention, the argon flow rate of the argon gas blown after adding the calcium silicon wire is preferably 50 to 80 NL / min, more preferably 55 to 75 NL / min, and more preferably 60 to 70 NL / min.

[0122] In the present invention, the vacuum pressure of the RH vacuum refining is preferably ≤3 mbar, more preferably ≤2.5 mbar, and more preferably ≤2 mbar.

[0123] In the present invention, the outlet temperature is preferably 1525-1540°C, more preferably 1528-1537°C, and more preferably 1531-1534°C.

[0124] Finally, the present invention pours the refined molten steel obtained in the above steps into a tundish and then casts it to obtain a SWRH82B steel ingot.

[0125] In the present invention, the casting method preferably includes casting using a six-machine six-strand billet continuous casting machine.

[0126] In the present invention, the temperature of the molten steel in the tundish is preferably 1485-1495°C, more preferably 1487-1493°C, and more preferably 1489-1491°C.

[0127] In the present invention, the superheat degree of the molten steel in the tundish is preferably 20-30°C, more preferably 22-28°C, and more preferably 24-26°C.

[0128] In the present invention, the casting speed is preferably 1.3 to 1.5 m / min, more preferably 1.34 to 1.46 m / min, and more preferably 1.38 to 1.42 m / min.

[0129] The present invention is a complete and detailed overall technical solution, which can better improve the comprehensive performance of SWRH82B steel ingots and further reduce the oxygen content and nitrogen content in SWRH82B steel. The production method for reducing the oxygen and nitrogen content in SWRH82B steel can specifically include the following contents:

[0130] A production method for reducing the oxygen and nitrogen content in SWRH82B steel comprises the following steps:

[0131] 1) Hot metal pretreatment: spray passivation magnesium powder and passivation lime into the hot metal for KR desulfurization treatment. The amount of passivation magnesium powder added is 1.0-1.5 kg / t 钢 , the amount of passivation lime added is 5.0~5.5kg / t 钢 The desulfurization time is 5 minutes, the molten iron temperature is ≥1320℃, and the slag is removed after the desulfurization is completed to ensure that the liquid surface is exposed to ≥3 / 4. After pretreatment, the sulfur content in the molten iron is required to be ≤0.010wt%.

[0132] 2) Converter smelting: The pre-treated molten iron and scrap steel are respectively 钢 、46kg / t 钢The added amount is poured into the converter for smelting, top and bottom composite blowing is adopted, argon is blown at the bottom throughout the whole process, the argon flow rate is 1000-1200NL / min, the carbon content of the converter end point is 0.10-0.20wt%, the steel tapping temperature is 1630-1650℃, the converter steel tapping time is controlled at 4-5min, and 100kg ferrosilicon alloy is added for deoxidation when the steel tapping amount is ≥1 / 4, and then 6.0-7.0kg / t is added. 钢 Silicon manganese alloy is alloyed, 400kg active lime is added for slag making, and 5.0~6.0kg / t 钢 Petroleum coke is used as a recarburizer to increase carbon. After steelmaking is completed, the ladle is sent to the argon blowing station behind the furnace, 80m of aluminum wire is fed in and argon is blown for 6 to 8 minutes, and the argon flow rate is 100 to 200NL / min.

[0133] 3) LF refining: transport the molten steel to the LF furnace refining station, add 200kg of molten steel refining slag conditioning agent, turn on the power to increase the temperature, and add 2.5-3.5kg / t 钢 High basicity refined slag, 1.5~2.5kg / t 钢 Quartz sand, 0~1.0kg / t 钢 Fluorite slag making. The furnace is maintained at a slight positive pressure of 50-80 kPa, and submerged arc heating is adopted. At the same time, argon gas is blown from the bottom, and the argon gas flow rate is 100-200 NL / min. The LF outlet temperature is 1565-1585℃.

[0134] Among them, the Al2O3 content of the molten steel refining slag adjusting agent is 50.0-80.0wt%, the CaO content of the high basicity refining slag is 70.0-90.0wt%, the SiO2 content of the quartz sand is ≥90.0wt%, and the binary basicity of the refining slag system in the LF refining process is controlled at 1.5-2.5, which can not only ensure that the inclusion component is closer to the low-melting point liquid component, but also ensure the slag system desulfurization effect to a certain extent, and reduce the erosion of the furnace lining material.

[0135] 4) RH refining: The molten steel is hoisted to the RH furnace refining station, and vacuum treatment is carried out. The vacuum degree is controlled at ≤3mbar, and the treatment time is 13-18min. During the treatment, argon is blown from the bottom, and the argon flow rate is 30-50NL / min. During the vacuum treatment process, the molten steel composition is sampled and analyzed, and alloy is added through the alloy silo. The cycle time is ≥6min. By extending the cycle time and blowing argon from the bottom, the stirring dynamics of the molten steel are enhanced, which is conducive to the floating removal of inclusions and vacuum denitrification. After the vacuum treatment, 3-5m / t of argon is fed to the molten steel. 钢 For calcium silicon wire, argon is blown for 9 to 15 minutes after wire feeding, the argon flow rate is 50 to 80NL / min, and the RH outlet temperature is 1525 to 1540℃.

[0136] 5) Billet continuous casting: The molten steel is delivered to the continuous casting platform. The tundish is purged with argon before pouring. The casting is protected throughout the whole process. A six-machine six-strand billet continuous casting machine is used for casting. The tundish temperature is 1485-1495°C. The superheat of the molten steel is controlled at 20-30°C. The casting machine pulling speed is specifically 1.3-1.5m / min.

[0137] The above content of the present invention provides a production method for reducing the oxygen and nitrogen content in SWRH82B steel, which is a SWRH82B steel ingot production method with specific control parameters and steps, which is particularly used to reduce the oxygen and nitrogen content in SWRH82B steel. The present invention adopts a production process of molten iron pretreatment-converter smelting-LF refining-RH refining-square billet continuous casting, which reduces the subsequent LF refining desulfurization burden by reducing the sulfur content of molten iron, reduces the LF refining heating time, and reduces the LF refining nitrogen increase; through the deoxidation process of adding ferrosilicon to the converter and adding aluminum wire after the furnace, deep deoxidation of molten steel is achieved; LF refining produces low-basicity slag, and a calcium treatment process is added to ensure the low melting point liquefaction of inclusions; through the bottom blowing of argon during the RH refining process, the floating removal of inclusions and the denitrification of molten steel are promoted, and a series of measures such as continuous casting protection casting are added to control the whole process production, reduce the oxygen and nitrogen content in steel, and improve product quality.

[0138] The production method for reducing the oxygen and nitrogen content in SWRH82B steel provided by the present invention can not only effectively reduce the oxygen content in SWRH82B steel, but also achieve stable control of the nitrogen content, reduce the wire breakage rate in wire rod drawing caused by fluctuations in oxygen and nitrogen content, achieve a reduction in production costs, and meet the requirements of green and environmentally friendly sustainable development while improving the service life of the product. The production method provided by the present invention can reasonably control the oxygen and nitrogen content in SWRH82B steel, and through full-process control and reasonable allocation of deoxidation and denitrification capabilities between processes, thereby reducing the wire breakage rate in wire drawing and improving the service life of the wire, and improving the performance of SWRH82B high-carbon steel wire rods. Moreover, the present invention is not limited to 82B wire products such as prestressed steel wire ropes and steel strands, but can also be used in high-end wire products such as tire meridians and cutting wires.

[0139] Experimental results show that by adopting the production method provided by the present invention, high-quality production of low-oxygen and low-nitrogen SWRH82B steel can be successfully achieved, with the total oxygen content in the steel being ≤0.0015wt% and the nitrogen content in the steel being ≤0.0040wt%.

[0140] In order to further illustrate the present invention, a production method for reducing the oxygen and nitrogen content in SWRH82B steel provided by the present invention is described in detail below in combination with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.

[0141] Comparative Example

[0142] The molten steel smelting adopts the process flow of "molten iron pretreatment-converter smelting-LF refining-RH refining-square billet continuous casting".

[0143] 1) Hot metal pretreatment: spray passivation magnesium powder and passivation lime into the hot metal for KR desulfurization treatment. The amount of passivation magnesium powder added is 1.0-1.5 kg / t 钢 , the amount of passivation lime added is 5.0~5.5kg / t 钢 The desulfurization time is 5 minutes, the molten iron temperature is ≥1320℃, and the slag is removed after the desulfurization is completed to ensure that the liquid surface is exposed to ≥3 / 4. The sulfur content in the molten iron after pretreatment is required to be ≤0.030wt%.

[0144] 2) Converter smelting: The pre-treated molten iron and scrap steel are respectively 钢 、46kg / t 钢 The added amount is poured into the converter for smelting, top and bottom composite blowing is adopted, argon is blown at the bottom throughout the whole process, the argon flow rate is 1000-1200NL / min, the carbon content of the converter end point is 0.10-0.20wt%, the steel tapping temperature is 1630-1650℃, the converter steel tapping time is controlled at 4-5min, and 100kg ferrosilicon alloy is added for deoxidation when the steel tapping amount is ≥1 / 4, and then 6.0-7.0kg / t is added. 钢 Silicon manganese alloy is alloyed, 400kg active lime is added for slag making, and 7.0~9.0kg / t 钢 Anthracite is used to increase carbon. After steel is tapped, the ladle is sent to the argon blowing station behind the furnace and argon is blown for 6 to 8 minutes with an argon flow rate of 100 to 200NL / min.

[0145] 3) LF refining: The molten steel is hoisted to the LF furnace refining station, 200kg of molten steel refining slag conditioning agent is added, and then the temperature is raised by electricity, and 3.0-4.0kg / t 钢 High basicity refined slag, 1.5~2.5kg / t 钢 Quartz sand, 0~1.0kg / t 钢Fluorite slag making. Submerged arc heating is adopted, and argon is blown from the bottom at the same time, the argon flow rate is 150-250NL / min, and the LF outlet temperature is 1565-1585°C. Among them, the Al2O3 content of the molten steel refining slag adjusting agent is 50.0-80.0wt%, the CaO content of the high basicity refining slag is 70.0-90.0wt%, the SiO2 content of the quartz sand is ≥90.0wt%, and the binary basicity of the refining slag system in the LF refining process is controlled at 2.5-3.5.

[0146] 4) RH refining: The molten steel is hoisted to the RH furnace refining station, and vacuum treatment is carried out. The vacuum degree is controlled at ≤3mbar, and the treatment time is 12-16min. During the vacuum treatment process, the molten steel composition is sampled and analyzed, and alloy is added through the alloy silo. The cycle time is ≥6min. After the vacuum treatment, 3-5m / t of molten steel is fed into the molten steel. 钢 For calcium silicon wire, argon is blown for 8 to 13 minutes after wire feeding, the argon flow rate is 50 to 80NL / min, and the RH outlet temperature is 1525 to 1540℃.

[0147] 5) Billet continuous casting: The molten steel is sent to the continuous casting platform and the casting is protected throughout the whole process. A six-machine six-strand billet continuous casting machine is used for casting. The middle ladle temperature is 1485-1495°C, the superheat of the molten steel is controlled at 20-30°C, and the casting machine pulling speed is 1.3-1.5m / min.

[0148] In the specific comparative examples, the main process parameters of molten iron pretreatment and converter smelting are shown in Table 1, the main process parameters of LF refining are shown in Table 2, the main process parameters of RH refining are shown in Table 3, and the main process parameters of billet continuous casting are shown in Table 4.

[0149] Table 1 Main process parameters of hot metal pretreatment and converter smelting

[0150] Comparative Example Sulfur content in hot metal (wt%) Converter end carbon wt% Steel tapping temperature ℃ <![CDATA[Anthracite recarburizer kg / t 钢 > 1 0.020 0.20 1630 7.0 2 0.030 0.11 1650 8.0

[0151] Table 2 Main process parameters of LF refining

[0152] Comparative Example Final slag basicity Refining time min Argon gas flow rate NL / min LF outgoing temperature ℃ 1 2.7 15 150 1565 2 3.1 18 200 1575

[0153] Table 3 Main process parameters of RH refining

[0154]

[0155] Table 4 Main process parameters of billet continuous casting

[0156] Comparative Example Section of ingot mm×mm Middle package temperature ℃ Pulling speed m / min 1 200×200 1485 1.4 2 200×200 1490 1.3

[0157] After the above steps, the chemical composition of the finished product SWRH82B is shown in Table 5.

[0158] Table 5 Chemical composition

[0159]

[0160]

[0161] Example

[0162] The molten steel smelting adopts the process flow of "molten iron pretreatment-converter smelting-LF refining-RH refining-square billet continuous casting".

[0163] 1) Hot metal pretreatment: spray passivation magnesium powder and passivation lime into the hot metal for KR desulfurization treatment. The amount of passivation magnesium powder added is 1.0-1.5 kg / t 钢 , the amount of passivation lime added is 5.0~5.5kg / t 钢 The desulfurization time is 5 minutes, the molten iron temperature is ≥1320℃, and the slag is removed after the desulfurization is completed to ensure that the liquid surface is exposed to ≥3 / 4. After pretreatment, the sulfur content in the molten iron is required to be ≤0.010wt%.

[0164] 2) Converter smelting: The pre-treated molten iron and scrap steel are respectively 钢 、46kg / t 钢 The added amount is poured into the converter for smelting, top and bottom composite blowing is adopted, argon is blown at the bottom throughout the whole process, the argon flow rate is 1000-1200NL / min, the carbon content of the converter end point is 0.10-0.20wt%, the steel tapping temperature is 1630-1650℃, the converter steel tapping time is controlled at 4-5min, and 100kg ferrosilicon alloy is added for deoxidation when the steel tapping amount is ≥1 / 4, and then 6.0-7.0kg / t is added. 钢 Silicon manganese alloy is alloyed, 400kg active lime is added for slag making, and 5.0~6.0kg / t 钢 Petroleum coke is used as a recarburizer to increase carbon. After steelmaking is completed, the ladle is sent to the argon blowing station behind the furnace, 80m of aluminum wire is fed in and argon is blown for 6 to 8 minutes, and the argon flow rate is 100 to 200NL / min.

[0165] 3) LF refining: transport the molten steel to the LF furnace refining station, add 200kg of molten steel refining slag conditioning agent, turn on the power to increase the temperature, and add 2.5-3.5kg / t 钢 High basicity refined slag, 1.5~2.5kg / t 钢 Quartz sand, 0~1.0kg / t 钢Fluorite slag making. The furnace is kept at a slight positive pressure of 50-80kPa, and submerged arc heating is adopted. At the same time, argon is blown from the bottom, and the argon flow rate is 100-200NL / min. The LF outlet temperature is 1565-1585°C. Among them, the Al2O3 content of the molten steel refining slag adjusting agent is 50.0-80.0wt%, the CaO content of the high basicity refining slag is 70.0-90.0wt%, the SiO2 content of the quartz sand is ≥90.0wt%, and the binary basicity of the refining slag system in the LF refining process is controlled at 1.5-2.5, which can not only ensure that the inclusion component is closer to the low melting point liquid component, but also ensure the slag system desulfurization effect to a certain extent, and reduce the erosion of the furnace lining material.

[0166] 4) RH refining: The molten steel is hoisted to the RH furnace refining station, and vacuum treatment is carried out. The vacuum degree is controlled at ≤3mbar, and the treatment time is 13-18min. During the treatment, argon is blown from the bottom, and the argon flow rate is 30-50NL / min. During the vacuum treatment process, the molten steel composition is sampled and analyzed, and alloy is added through the alloy silo. The cycle time is ≥6min. By extending the cycle time and blowing argon from the bottom, the stirring dynamics of the molten steel are enhanced, which is conducive to the floating removal of inclusions and vacuum denitrification. After the vacuum treatment, 3-5m / t of argon is fed to the molten steel. 钢 For calcium silicon wire, argon is blown for 9 to 15 minutes after wire feeding, the argon flow rate is 50 to 80NL / min, and the RH outlet temperature is 1525 to 1540℃.

[0167] 5) Billet continuous casting: The molten steel is sent to the continuous casting platform. The tundish is purged with argon before pouring. The casting is protected throughout the whole process. A six-machine six-strand billet continuous casting machine is used for casting. The tundish temperature is 1485-1495°C. The superheat of the molten steel is controlled at 20-30°C. The casting machine pulling speed is 1.3-1.5m / min.

[0168] In the specific embodiment, the main process parameters of molten iron pretreatment and converter smelting are shown in Table 6, the main process parameters of LF refining are shown in Table 7, the main process parameters of RH refining are shown in Table 8, and the main process parameters of billet continuous casting are shown in Table 9.

[0169] Table 6 Main process parameters of hot metal pretreatment and converter smelting

[0170]

[0171] Table 7 Main process parameters of LF refining

[0172] Example Final slag basicity Refining time min Argon gas flow rate NL / min LF outgoing temperature ℃ 1 1.5 15 100 1565 2 2.0 16 150 1570 3 2.5 17 200 1575

[0173] Table 8 Main process parameters of RH refining

[0174]

[0175] Table 9 Main process parameters of billet continuous casting

[0176] Example Section of ingot mm×mm Middle package temperature ℃ Pulling speed m / min 1 200×200 1485 1.5 2 200×200 1490 1.4 3 200×200 1490 1.3

[0177] After the above steps, the chemical composition of the finished product SWRH82B is shown in Table 10.

[0178] Table 10 Chemical composition

[0179]

[0180] The above is a detailed introduction to a production method for reducing the oxygen and nitrogen content in SWRH82B steel provided by the present invention. The principle and implementation method of the present invention are explained in this article using specific examples. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A production method for reducing the oxygen and nitrogen content in SWRH82B steel, characterized in that: The following steps are involved: 1) spraying passivation magnesium powder and passivation lime into molten iron to perform KR desulfurization treatment, and then performing slagging treatment to obtain pretreated molten iron; The sulfur content in the pretreated molten iron is ≤0.010wt%; 2) adopting the top and bottom composite blowing method, pouring the pretreated molten iron and scrap steel obtained in the above steps into a converter for converter smelting, and obtaining molten steel after tapping; 3) adding molten steel refining slag conditioning agent, high basicity refined slag, quartz sand and fluorite slag making to the molten steel obtained in the above step, blowing argon gas for LF refining, and obtaining LF refined molten steel; 4) The molten steel obtained after LF refining in the above step is subjected to RH vacuum refining under the condition of blowing argon gas to obtain refined molten steel out of the station; 5) Pour the refined molten steel obtained in the above steps into a tundish and then cast it to obtain SWRH82B steel ingot.

2. The production method according to claim 1, characterized in that The addition amount of the passivation magnesium powder is 1.0-1.5 kg / t 钢 ; The amount of passivation lime added is 5.0-5.5 kg / t 钢 ; The KR method desulfurization treatment time is 5 to 8 minutes; The temperature of the molten iron is ≥1320°C.

3. The production method according to claim 1, characterized in that The slag removal treatment specifically includes that the ratio of the exposed molten iron surface area to the total area is greater than or equal to 75%; The sulfur content in the pretreated molten iron is ≤0.010wt%; The scrap steel includes clean scrap steel; The mass ratio of molten iron to scrap steel after the pretreatment is (19-22):

1.

4. The production method according to claim 1, characterized in that In the converter smelting, argon gas blowing is used at the bottom of the furnace; The flow rate of the argon gas is 1000-1200 NL / min; The final carbon content of the converter smelting is 0.10wt% to 0.20wt%; The temperature of the steel tapping is 1630-1650°C; The time for tapping steel from the converter is 4 to 5 minutes.

5. The production method according to claim 1, characterized in that: The steel tapping process includes the step of adding ferrosilicon alloy for deoxidation when the steel tapping amount is greater than or equal to 25%; After the deoxidation, the step of adding silicon-manganese alloy for alloying is also included; The amount of silicon-manganese alloy added is 6.0-7.0 kg / t 钢 ; The alloying step also includes adding active lime to make slag; After the slag making, the step of adding a carburizer to increase carbon is also included.

6. The production method according to claim 5, characterized in that The amount of the recarburizer added is 5.0-6.0 kg / t 钢 ; After the steel is tapped, the step of blowing argon gas into the molten steel is also included; The argon blowing process specifically includes adding aluminum and blowing argon; The argon blowing time is 6 to 8 minutes; The argon gas flow rate of the argon blowing is 100-200 NL / min.

7. The production method according to claim 1, characterized in that: The Al2O3 content of the molten steel refining slag conditioning agent is 50.0wt% to 80.0wt%; The amount of the molten steel refining slag conditioning agent added is 200-300kg; The specific process of adding is to first add the molten steel refining slag conditioning agent and then heat it up, and then add 2.5-3.5 kg / t 钢 High basicity refined slag, 1.5~2.5kg / t 钢 Quartz sand and 0~1.0kg / t 钢 Fluorite slag making; In the step 3), the argon gas flow rate of the argon gas is 100-200 NL / min; In the step 3), blowing argon gas is specifically bottom blowing argon gas.

8. The production method according to claim 1, characterized in that: The pressure in the refining furnace of the LF refining is 50-80 kPa; The CaO content of the high basicity refined slag is 70.0wt% to 90.0wt%; The SiO2 content of the quartz sand is ≥90.0wt%; The binary basicity of the slag system in the LF refining process is controlled at 1.5 to 2.5; The LF refining temperature is 1565-1585°C.

9. The production method according to claim 1, characterized in that: The RH vacuum refining time is 13 to 18 minutes; In the step 4), the argon gas flow rate of the argon gas is 30 to 50 NL / min; In the step 4), blowing argon gas is specifically bottom blowing argon gas; After the RH vacuum refining, the steps of adding calcium silicon wire and blowing argon gas after adding the calcium silicon wire are also included; The time of blowing argon gas after adding calcium silicon wire is 9 to 15 minutes; The argon flow rate of the argon gas blown after adding the calcium silicon wire is 50-80NL / min.

10. The production method according to claim 1, characterized in that: The vacuum pressure of the RH vacuum refining is ≤3 mbar; The outlet temperature is 1525-1540°C; The casting method includes casting using a six-machine six-strand billet continuous casting machine; The temperature of the molten steel in the tundish is 1485-1495°C; The superheat degree of the molten steel in the tundish is 20-30°C; The casting pulling speed is 1.3-1.5 m / min.

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