WO2022236900A1 - 一种极地用钢的超高磷铁水低成本冶炼方法 - Google Patents

一种极地用钢的超高磷铁水低成本冶炼方法 Download PDF

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Publication number
WO2022236900A1
WO2022236900A1 PCT/CN2021/098736 CN2021098736W WO2022236900A1 WO 2022236900 A1 WO2022236900 A1 WO 2022236900A1 CN 2021098736 W CN2021098736 W CN 2021098736W WO 2022236900 A1 WO2022236900 A1 WO 2022236900A1
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steel
slag
smelting
converter
low
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PCT/CN2021/098736
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English (en)
French (fr)
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麻衡
何康
王中学
王腾飞
邹稳蓬
杜传治
陈爱娇
张佩
宁伟
王月香
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莱芜钢铁集团银山型钢有限公司
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Priority to KR1020237006365A priority Critical patent/KR20230077719A/ko
Priority to JP2022574397A priority patent/JP7507895B2/ja
Priority to EP21941469.5A priority patent/EP4215627A4/en
Priority to US17/928,185 priority patent/US20230220504A1/en
Publication of WO2022236900A1 publication Critical patent/WO2022236900A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/34—Blowing through the bath
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/36—Processes yielding slags of special composition
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/072—Treatment with gases
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C2007/0093—Duplex process; Two stage processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention belongs to the field of iron and steel metallurgy, and relates to a method for smelting low-phosphorus steel with ultra-high-phosphorus hot metal for polar steel.
  • Patent document CN 109593907 A published "a method for smelting low-phosphorus steel”. This patent produces finished products with P ⁇ 0.005% by controlling the converter blowing gun position, oxygen supply intensity, bottom blowing flow rate, and tapping slag control. Qualified slab, but this method is only applicable to molten iron with phosphorus content less than or equal to 0.10%.
  • Patent document CN 109897933 A announced "a high-efficiency smelting process for producing low-phosphorus clean steel by converter”. Slag treatment is easy to produce phosphorus back phenomenon, which is not suitable for ultra-high phosphorus hot metal smelting.
  • Patent document CN 109402323 A published "A Method for Smelting Ultra-low Phosphorus Steel by Ultra-high Phosphorus Hot Metal”. This patent optimizes the ratio of lime and slag modification agent in the LF refining process, and adjusts the composition of steel slag to increase the phosphorus content of steel slag. Capacity, thereby increasing the distribution ratio of phosphorus in steel slag and molten steel, providing favorable conditions for dephosphorization.
  • this smelting method does not describe the converter smelting process in detail, and the P content in the LF furnace in-situ molten steel is at a low level, and the LF refining process takes too long, which is not conducive to high-efficiency and low-cost mass industrial production.
  • the purpose of this application is to provide a low-cost smelting method for ultra-high phosphorus molten iron for polar steel, which can realize the requirement of using molten iron with a phosphorus content higher than 0.150% to smelt steel with a phosphorus content less than 0.007%, and can Significantly lower the ductile-brittle transition temperature of steel to meet the requirements of extreme cold conditions.
  • the present invention adopts the following technical solutions:
  • a low-cost smelting method of ultra-high phosphorus hot metal for polar steel comprising sequentially:
  • Converter smelting steps smelting, deoxidizing and tapping alloying of raw materials including molten iron;
  • LF refining step adjusting slag and refining the molten steel obtained in the converter smelting step to obtain refined molten steel
  • RH degassing step vacuum degassing the refined molten steel
  • Continuous casting step performing continuous casting on the molten steel obtained after the RH degassing step to obtain a cast slab.
  • the converter smelting step when the content of P element in the molten iron as raw material is ⁇ 0.15wt%, Si The content of the element is 0.15-0.6wt%, the content of the S element is ⁇ 0.006wt%, and the content of the As element is ⁇ 0.006wt%; preferably, the temperature of the molten iron is ⁇ 1230°C; if the temperature of the molten iron is too low, it may cause Molten steel back blowing is serious, large blowing damage, high consumption of steel material, high cost, no guarantee of molten steel quality, reduced furnace life and other problems.
  • the converter smelting step when the mass content of silicon in the molten iron used as a raw material is ⁇ 0.30%, the The raw material also includes scrap steel; preferably, the mass of scrap steel/(mass of molten iron + scrap steel) ⁇ 8%.
  • the double slag process specifically includes: step 1): adding a part of slag material to the raw material, and then using an oxygen lance to blow oxygen into the raw material until the primary slag is completely melted Finally, put the oxygen lance out of the converter and carry out slag dumping; step 2): use the oxygen lance to blow oxygen into the molten steel obtained in step 1), then add the remaining slag material in batches, continue smelting, and measure during the smelting process
  • lime or sinter is selected to be added according to the measurement results to ensure the basicity in the later stage and promote the penetration of slag.
  • the time from adding the remaining slag to measuring the TSC temperature and C content of the molten steel is 70-90s.
  • the total time for blowing oxygen (that is, the total reaction time of step 2)) is 240-300s.
  • the slag material includes a slagging agent and a coolant; preferably, the slagging agent is lime and dolomite; the coolant is sintered ore; preferably, in the step 1), the The addition amount of lime is 20-22.5kg/ton steel, the addition amount of described dolomite is 3.5-5.5kg/ton steel, the addition amount of described sintered ore is 28.5-32kg/ton steel;
  • the time for blowing oxygen is 5-6min;
  • step 1) after the primary slag has melted through, the oxygen lance is taken out of the converter within 15-30s;
  • the lime is added in an amount of 21-25kg/ton of steel
  • the dolomite is added in an amount of 3.5-5.0kg/ton of steel
  • the sintered ore The addition amount is 14-20kg/ton of steel
  • the TSC temperature is controlled at 1540°C-1590°C, and the carbon content is controlled at 0.25wt%-0.40wt%.
  • the lime is added to continue the oxygen blowing smelting; when the measured TSC ⁇ 1590°C, the sintered ore is added.
  • the lime or sintered ore is selected to be added to continue blowing, so as to ensure that the TSO temperature of the converter is controlled at 1600°C-1650°C, and the carbon content is controlled at 0.07%-0.09% %;
  • the TSO temperature of the converter is less than 1600°C, the temperature is raised by spot blowing.
  • the converter smelting step when the silicon content in the molten iron used as raw material is ⁇ 0.30wt%, the The raw materials are molten iron and scrap steel; preferably, the mass ratio of scrap steel to the raw material is ⁇ 8%.
  • a single slag process for smelting when the silicon content in the molten iron used as a raw material is less than 0.30%, a single slag process for smelting; preferably, the specific process of the single slag process is: step a) adding lime, sinter and dolomite to the raw materials, step b) waiting for the slag to be fully melted, measuring TSC, and then according to the measured TSC As a result, choose to add lime or sinter;
  • the lime is added in 2-3 batches, and the amount added per ton of steel is 42.9-46.2kg/t (that is, 42.9-46.2kg per ton of molten iron); preferably, the The sintered ore is added in 3-4 batches, and the amount added per ton of steel is 39.2-42.8kg/t; preferably, the dolomite is added in 2-3 batches, and the amount added per ton of steel is 8.57-10.7kg/t;
  • the lime or sinter is added in an amount of 2.15-3.57Kg per ton of molten iron; preferably, when the measured TSC ⁇ 1540°C, the lime is added Continue oxygen blowing smelting; when the measured TSC is ⁇ 1590°C, add sintered ore as a coolant to control the reaction rhythm.
  • step b) according to the measurement result of TSO, if the C content is greater than or equal to 0.10%, spot blowing is performed to control the C and P contents of the molten steel.
  • the converter smelting step nitrogen is blown at the bottom 7-8 minutes before smelting, wherein the nitrogen flow rate in the first 1-3 minutes is 450-580Nm 3 /h, the nitrogen flow rate increased to 800-900Nm 3 /h in the later stage (the volume of nitrogen is: the pressure is one atmosphere, the temperature is the gas volume at 0°C); 7-8 minutes after smelting bottom blowing nitrogen, switch to argon Gas, argon gas flow rate increased to 1000-1100Nm 3 /h.
  • the agitation of the molten pool is strengthened to promote the melting of lime and increase the speed of slagging; in the final stage of blowing, the agitation intensity of the molten pool is increased to promote the reaction balance of slag steel and strengthen the dephosphorization effect.
  • the converter smelting step when the carbon-oxygen product of the converter is ⁇ 0.0021, and the carbon at the end point of the converter measurement is ⁇ 0.045%, the direct output Steel; when the carbon and oxygen product of the converter is > 0.0032, the steel can only be tapped when the TSO composition of the converter is determined to be C: 0.06-0.09wt%, P ⁇ 0.006wt%, S ⁇ 0.020wt%; the carbon and oxygen product of the converter is 0.0021 When between -0.0032, the carbon at the furnace measurement end point needs to be ⁇ 0.045%, otherwise point blowing is carried out.
  • a high-low-low gun position (2000mm-1500mm-500mm) Nitrogen is used for slag splashing to protect the furnace.
  • the pressure gun is repeatedly lifted. After the slag splashes dry, the nitrogen is turned off and the gun is lifted.
  • the slag splashing time is 140-200s; Furnace slag splashing, and the thickness uniformity of slag splashing is good; compared with oxygen, a strong redox reaction will occur, which is not suitable for slag splashing to protect the furnace.
  • the price of argon gas is high, and the economy is poor.
  • the present invention can fully utilize The final slag with high alkalinity of the converter and the nitrogen by-product of the oxygen plant have low cost, and the invention directly adopts the oxygen lance to blow nitrogen and splash the slag to protect the furnace, which is easy to operate and high in efficiency.
  • the deoxidation is carried out by using ferro-aluminum manganese, and the addition amount of ferro-aluminum manganese is 1.7 -2.5kg/t steel.
  • the alloy used in the alloying includes: metal manganese, ferrosilicon, ferroniobium, vanadium Iron and nickel plates.
  • the substances used in the slag adjustment are aluminum slag and calcium carbide.
  • the slag adjustment also include lime; preferably, the slag is adjusted until the final slag alkalinity is ⁇ 2.2, and the top slag must be yellow and white slag or white slag before leaving the station, and the yellow and white slag or white slag must be kept for no less than 10 minutes.
  • the refining time is 30-45 minutes.
  • the vacuum degree is ⁇ 133Pa
  • the circulation time is not less than 15 minutes
  • the pure degassing time is greater than 5 minutes.
  • the superheat of the molten steel is controlled within 25°C.
  • the casting speed during continuous casting is 1.25-1.35m/min;
  • the casting speed is 1.2-1.4m/min;
  • the casting speed is 1.1-1.3m/min;
  • the casting speed is 0.85-0.95m/min;
  • the crystallizer in the above low-cost smelting method of ultra-high phosphorus molten iron for polar steel, as a preferred embodiment, in the continuous casting step, the crystallizer is covered with peritectic steel mold slag; the tundish is covered with a covering agent combined with carbonized rice husk , to ensure good coverage of the tundish liquid surface: the long nozzle of the tundish is sealed with argon, and the flow rate is 90-120L/min; if the flow rate is less than 90L ⁇ min, it is difficult to achieve the effect of isolating the air, and if the flow rate is >120L ⁇ min, argon is wasted .
  • the P content in the steel composition obtained by the smelting method is lower than 0.007%; more preferably, the The steel components obtained by the above smelting method include: C: 0.06-0.10%, Si: 0.20-0.35%, Mn: 1.5-1.65%, Nb: 0.010-0.030%, V: 0.010-0.035%, Ti: 0.010- 0.035%, Al: 0.015-0.040.
  • the method for smelting low-phosphorus steel with ultra-high-phosphorus molten iron for polar steels described in this application determines whether to adopt the double-slag process according to the silicon content of the molten iron. If the silicon content of the molten iron is ⁇ 0.30%, the converter smelting adopts the double-slag process; the silicon content of the molten iron is less than 0.30% % time: the converter adopts the single slag process, and then adopts the refining deep dephosphorization process for further dephosphorization.
  • This method can realize the continuous and stable smelting of steel with a phosphorus content of less than 0.007% using ultra-high phosphorus molten iron as raw material, and the consumption of auxiliary materials is relatively low , The production pace is fast, and it has broad prospects for promotion.
  • Smelting in single and double slag areas is distinguished according to the Si content of molten iron, which greatly saves the consumption of smelting raw materials, shortens the smelting cycle, and speeds up the production process.
  • the optimized slagging material ratio and reasonable oxygen blowing flow rate and oxygen blowing time are adopted to obtain ultra-low phosphorus hot metal through converter smelting.
  • the method for smelting low-phosphorus steel with ultra-high-phosphorus molten iron described in this application is relatively cheap, and the process is simple and easy to operate.
  • the slab-rolled steel plate produced by this smelting method is suitable for extreme cold conditions and has comprehensive properties. In demanding projects.
  • a method for smelting low-phosphorus steel with ultra-high phosphorus hot metal for polar steel :
  • a 140t top-bottom combined blowing converter is used, and the raw materials are composed of: 141t of high-phosphorus desulfurization molten iron (C: 5.65%, Mn: 0.213%, P: 0.151%, S: 0.002%, Si: 0.54%, AS : 0.0020%, molten iron
  • the temperature is 1310°C)
  • the double slag process is used for smelting. During the smelting, the oxygen is first lowered and blown, and the gun position is controlled at about 1500mm.
  • the flow rate of the oxygen lance is adjusted to about 25000m 3 /h, the lance position is at 1800mm, 3050kg of lime, 3600kg of sintered ore and 400kg of dolomite are added, and the first batch of materials is added 150s before the start of blowing.
  • the pressure gun is repeatedly lifted. After the slag splashes dry, the nitrogen lift gun is turned off.
  • the slag splashing time is 186s.
  • the carbon-oxygen product of the converter is ⁇ 0.0021 and the carbon at the end point of the converter measurement is ⁇ 0.045wt%
  • the steel is tapped, and the tapping temperature of the converter is 1620°C.
  • 260kg of ferro-aluminum manganese, 2100kg of metal manganese, 120kg of nickel plate, 60kg of ferro-vanadium, and niobium are added. 50kg of iron, 440kg of ferrosilicon; 600kg of synthetic slag and 200kg of pre-melted slag are added along the steel flow.
  • LF refining adds 200kg of lime, 200kg of fluorite, 50kg of calcium carbide, and 80kg of aluminum slag for slag adjustment; feeds 150m of aluminum wire to increase aluminum, and feeds 130m of titanium wire to increase titanium.
  • the basicity of the final slag is controlled above 2.2.
  • argon is blown and stirred at the bottom.
  • the argon pressure can be appropriately increased in the early stage, and soft blowing with low pressure is used before leaving the station to ensure that the inclusions float up.
  • the soft argon blowing time for refining is 5 minutes, and the overall refining time is 45 minutes.
  • the insertion depth of the dipping tube is 400mm; the vacuum degree during treatment is 30Pa, the circulation time is 22 minutes, and the pure degassing time is 10 minutes.
  • feed the calcium aluminum wire 90 meters per furnace, soft blow for 10 minutes, and the RH smelting cycle is 23 minutes.
  • the crystallizer is made of peritectic steel mold slag; the tundish is covered with a covering agent combined with carbonized rice husk to ensure good coverage of the liquid surface of the tundish.
  • the long nozzle of the ladle is sealed with argon, the flow rate is 90L/min, and the crystallizer adopts a non-sinusoidal vibration mode.
  • the section size of the continuous casting slab is 250mm*2400mm, and the casting speed is 1.1m/min.
  • the end condition of the heat is C: 0.07%, Si: 0.28%, Mn: 1.52%, P: 0.006%, S: 0.001%, Nb: 0.025%, Ti: 0.015%, V: 0.025%, Ni: 0.11%, Als: 0.020%; the furnace consumption is: lime 48.53kg/ton steel, total slag consumption 54.41kg/ton steel, oxygen consumption 47.05Nm 3 /ton steel.
  • the P content in the steel is all lower than 0.007wt%.
  • the yield strength of the steel plate is 425-510MPa
  • the tensile strength is 520-590MPa
  • the impact energy at -60°C is 150- 210J, reduction of area 22-32%.
  • a method for smelting low-phosphorus steel with ultra-high phosphorus hot metal for polar steel :
  • a 140t top-bottom combined blowing converter is used, and the raw material composition is: high-phosphorus desulfurization hot metal 92% (C: 4.437%, Mn: 0.213%, P: 0.148%, S: 0.003%, Si: 0.294%, AS : 0.0018%, The temperature of molten iron is 1316°C), and the balance is steel scrap.
  • the single slag process is adopted in the smelting process, and the position of the lance is controlled at about 1500mm when the oxygen lance is blown; after the oxygen lance is ignited, the flow rate of the oxygen lance is adjusted to about 26000m 3 /h, the lance position is at 1800mm, and the oxygen supply pressure is 0.8MPa ;8 minutes before smelting, nitrogen was blown at the bottom, the flow rate of nitrogen was 560m 3 /h, and then increased to 880m 3 /h, after 8 minutes of bottom blowing, it was switched to argon, and the flow rate increased to 1200m 3 /h, and 6200kg of sintered ore was added , 6040kg of lime, 800kg of dolomite, to ensure the alkalinity in the later stage and promote the penetration of slag; the position of the end gun is controlled at about 1200mm.
  • the high-low-low gun position (2000mm-1500mm-500mm) is used to protect the furnace by slag splashing.
  • the pressure gun is repeatedly lifted.
  • the nitrogen lift gun is turned off.
  • the slag splashing time is 163s.
  • the tapping temperature of the converter is 1646°C. 240kg of ferro-aluminum manganese, 2040kg of metal manganese, 120kg of nickel plate, 60kg of ferro-vanadium, 50kg of ferro-niobium, and 440kg of ferrosilicon are added during tapping; 600kg of synthetic slag and 200Kg of pre-melted slag are added along the steel flow.
  • 352kg of lime, 157kg of fluorite, 180kg of aluminum slag, and 20Kg of calcium carbide are added to LF refining for slag adjustment; 120m of aluminum wire is fed to increase aluminum, and 150m of titanium wire is fed to increase titanium.
  • the basicity of the final slag is controlled above 2.2.
  • the argon pressure can be appropriately increased in the early stage, and soft blowing with low pressure is used before leaving the station to ensure that inclusions float up.
  • the soft argon blowing time is 5 minutes, and the total smelting time is 42 minutes.
  • the insertion depth of the dipping tube is 400mm; the vacuum degree during treatment is 30Pa, the circulation time is 22 minutes, and the pure degassing time is 10 minutes.
  • 80 meters of calcium-aluminum wire is fed, soft blowing is performed for 10 minutes, and the RH smelting cycle is 22 minutes.
  • the crystallizer is made of peritectic steel mold slag; the tundish is covered with a covering agent combined with carbonized rice husk to ensure good coverage of the liquid surface of the tundish.
  • the long nozzle of the ladle is sealed with argon, the flow rate is 90L/min, and the crystallizer adopts a non-sinusoidal vibration mode.
  • the section size of the continuous casting slab is 300mm, and the casting speed is 0.85m/min.
  • the end condition of the heat is C: 0.07%, Si: 0.27%, Mn: 1.51%, P: 0.0065%, S: 0.001%, Nb: 0.026%, Ti: 0.015%, V: 0.026%, Ni: 0.12%, Als: 0.020%
  • the furnace consumption is: lime 47kg/ton steel, slag material consumption 51.5kg/ton steel, oxygen consumption 47.79Nm 3 /ton steel, steel material consumption 1.10t/ton steel.
  • the P content in the steel is all lower than 0.007wt%.
  • the yield strength of the steel plate is 440-500MPa
  • the tensile strength is 525-605MPa
  • the impact energy at -60°C is 130- 190J, reduction of area 23-29%.

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Abstract

本发明公开了一种极地用钢的超高磷铁水低成本冶炼方法，所述方法依次包括：转炉冶炼步骤：对包括铁水的原料进行冶炼、脱氧和出钢合金化；LF精炼步骤：对所述转炉冶炼步骤所得的钢液进行调渣、精炼，得到精炼钢液；RH脱气步骤：对所述精炼钢液进行真空脱气；连铸步骤：对所述RH脱气步骤后所得的钢液进行连铸，得到铸坯。本发明根据铁水Si含量进行区分单双渣区冶炼，大幅度节约冶炼原料消耗，缩短冶炼周期，加快生产流程。

Description

一种极地用钢的超高磷铁水低成本冶炼方法 技术领域
本发明属于钢铁冶金领域，涉及一种极地用钢的超高磷铁水冶炼低磷钢的方法。
背景技术
随着世界能源的日益短缺，各国相继加大极地油气能源开发力度并建造诸多海洋平台，极地用耐超低温钢的需求量猛增。由于极地温度极低，钢中磷含量对钢的韧性至关重要，但目前国内铁水磷含量差异较大，部分钢厂受矿石原料影响，产出的超高磷铁水不适合生产低磷钢，这严重拖慢了生产节奏。随着用户对低磷优质钢材需求量的不断增大，如何在最低的成本下利用转炉实现此类超高磷铁水冶炼极地用低磷钢是现阶段研究的重点。目前，国内外部分企业广泛采用转炉双联法生产低磷钢，如JFE的LD-NRP法、神户制钢的H炉、宝钢的BRP法等，此类工艺对设备要求较高，且转炉铁水倒运过程中热量损失大，生产效率较低；也有在同一座转炉上连续进行铁水脱磷和脱碳的操作的双渣法，该工艺操作简单，无需新增设备，已在国内外广泛采用。
虽然目前关于利用高磷铁水冶炼低磷钢的专利较多，但是此类冶炼工艺普遍存在工艺流程长、成本高等缺点。以下简要介绍几个相似的专利：
专利文献CN 109593907 A公布了“一种冶炼低磷钢的方法”，该专利通过控制转炉吹炼枪位、供氧强度、底吹流量、出钢下渣控制等步骤生产成品P≤0.005％的合格铸坯，但该方法仅适用于磷含量小于等于0.10％铁水。
专利文献CN 109897933 A公布了“一种转炉生产低磷洁净钢的高效冶炼工艺”，该专利通过转炉双渣法冶炼低磷钢，但冶炼方法用铁水磷含量均在低于0.13％，且留渣处理易产生回磷现象，不适用于超高磷铁水冶炼。
专利文献CN 109402323 A公布了“一种超高磷铁水冶炼超低磷钢的方 法”，该专利通过在LF精炼过程中优化白灰与熔渣改制剂的配比，调整钢渣成分增大钢渣的磷容量，从而增大磷在钢渣与钢液中的分配比，为脱磷提供有利条件。但该冶炼方法并未对转炉冶炼过程进行详尽描述，且LF炉就位钢水中P含量处于较低水平，且LF精炼过程用时过长，不利于高效率低成本的批量化工业生产。
发明内容
针对现有技术的不足，本申请的目的是提供一种极地用钢的超高磷铁水低成本冶炼方法，可实现利用磷含量高于0.150％的铁水冶炼磷含量小于0.007％钢的要求，能显著降低钢材的韧脆性转变温度，满足极地极寒工况下要求。
为实现上述目的，本发明采用以下技术方案：
一种极地用钢的超高磷铁水低成本冶炼方法，依次包括：
转炉冶炼步骤：对包括铁水的原料进行冶炼、脱氧和出钢合金化；
LF精炼步骤：对所述转炉冶炼步骤所得的钢液进行调渣、精炼，得到精炼钢液；
RH脱气步骤：对所述精炼钢液进行真空脱气；
连铸步骤：对所述RH脱气步骤后所得的钢液进行连铸，得到铸坯。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，当作为原料的所述铁水中P元素的含量≥0.15wt％时，Si元素的含量为0.15-0.6wt％，S元素的含量为≤0.006wt％，As元素的含量为≤0.006wt％；优选地，所述铁水的温度≥1230℃；若铁水温度过低会可能造成钢水后吹严重，吹损大，钢铁料消耗高，成本高，钢水质量无保障，炉龄下降等问题。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，当作为原料的所述铁水中硅的质量含量≥0.30％时，所述原料还包括废钢；优选地，所述废钢的质量/(铁水+废钢的质量)≤8％。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，当作为原料的所述铁水中硅的质量含量≥0.30％时，采用双渣工艺进行所述冶炼；优选地，所述双渣工艺具体包括：步骤1)：向所述原料中加入一部分的渣料，之后采用氧枪向所述原料中吹氧气，待初渣化透后，将氧枪提出转炉、进行倒渣；步骤2)：采用氧枪向步骤1)所得的钢液中吹氧气，然后分批加入剩余的所述渣料，继续进行冶炼，冶炼过程中测定钢水的TSC温度和C含量，根据测定结果选择加入石灰或烧结矿，以保证后期碱度并促进渣化透。
优选地，在所述步骤2)中，从加入剩余的所述渣料到测定钢水的TSC温度和C含量之间的时间为70-90s。
优选地，在所述步骤2)中，吹氧气的总时间(即步骤2)的总反应时间)为240-300s。
优选地，所述渣料包括造渣剂和冷却剂；优选地，所述造渣剂为石灰和白云石；所述冷却剂为烧结矿；优选地，在所述步骤1)中，所述石灰的加入量为20-22.5kg/吨钢，所述白云石的加入量3.5-5.5kg/吨钢，所述烧结矿的加入量为28.5-32kg/吨钢；
优选地，在步骤1)中，所述吹氧气的时间为5-6min；
优选地，在步骤1)中，待初渣化透后，15-30s内将氧枪提出转炉；
优选地，在所述步骤2)的所述渣料中，所述石灰的加入量为21-25kg/吨钢，所述白云石的加入量为3.5-5.0kg/吨钢，所述烧结矿的加入量为14-20kg/吨钢；
优选地，在所述步骤2)中，所述TSC温度控制为1540℃-1590℃，碳含量控制为0.25wt％-0.40wt％。优选地，当测得到的TSC≤1540℃时，加入所述石灰继续吹氧冶炼；当测得的TSC≥1590℃时，加入烧结矿。
优选地，在所述步骤2)中，根据测定的TSC温度结果选择加入所述石灰或烧结矿继续吹炼，以保证转炉TSO温度控制为1600℃-1650℃，碳含量控制为0.07％-0.09％；优选地，若所述转炉TSO温度小于1600℃，则进行点吹升温。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方 式，在所述转炉冶炼步骤中，当作为原料的所述铁水中硅的含量＜0.30wt％时，所述原料为铁水和废钢；优选地，废钢占所述原料的质量比≤8％。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，当作为原料的所述铁水中硅的质量含量＜0.30％时，采用单渣工艺进行冶炼；优选地，所述单渣工艺的具体过程为：步骤a)向所述原料加入石灰、烧结矿和白云石，步骤b)待全程渣子化透，测量TSC，然后根据测定TSC结果选择加入石灰或烧结矿；
优选地，在所述步骤a)中，所述石灰分2-3批次加入，吨钢加入量为42.9-46.2kg/t(即每吨铁水中加入42.9-46.2kg)；优选地，所述烧结矿分3-4批次加入，吨钢加入量为39.2-42.8kg/t；优选地，所述白云石分2-3批次加入，吨钢加入量为8.57-10.7kg/t；
优选地，在所述步骤b)中，每吨所述铁水中，所述石灰或烧结矿的加入量为2.15-3.57Kg；优选地，当测得的TSC≤1540℃时，加入所述石灰继续吹氧冶炼；当测得的TSC≥1590℃时，加入烧结矿，作为冷却剂，控制反应节奏。
优选地，在所述步骤b)中，根据TSO的测定结果，若C含量≥0.10％，则进行点吹，以控制钢水的C、P含量。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，冶炼全过程采用转炉底吹氮气和氩气。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，冶炼前7-8分钟，底吹氮气，其中前1-3min氮气流量为450-580Nm 3/h，后期氮气流量增加为800-900Nm 3/h(氮气的体积为：压力为一个大气压，温度是0℃的气体体积)；冶炼底吹氮气7-8分钟后切换为氩气，氩气气流量增加到1000-1100Nm 3/h。在吹炼前期，加强熔池搅拌，促进石灰熔解，提高成渣速度；在吹炼末期，提高熔池搅拌强度，促进渣钢反应平衡，强化脱磷效果。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，当转炉碳氧积≤0.0021，转炉测量终点碳≤0.045％时，直接出钢；当转炉碳氧积＞0.0032时，需等转炉TSO成分测定为C：0.06-0.09wt％，P≤0.006wt％，S≤0.020wt％时，方能出钢；转炉碳 氧积在0.0021-0.0032之间时，炉测量终点碳需要≤0.045％，否则进行点吹。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，在所述冶炼之后，所述脱氧之前，采用高-低-低枪位(2000mm-1500mm-500mm)利用氮气进行溅渣护炉，溅渣过程重复提压抢，渣溅干后关氮提枪，溅渣时间为140-200s；本发明采用三阶段枪位可实现全炉膛溅渣，且溅渣厚度均匀性好；相对于氧气会发生强烈氧化还原反应，不适用于溅渣护炉，氩气价格较高，经济性差，本发明采用氮气溅渣护炉可充分利用转炉高碱度终渣和制氧厂的氮气副产品，成本较低，且本发明直接采用氧枪吹氮溅渣护炉操作简便，效率高。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，采用铝锰铁进行所述脱氧，所述铝锰铁的加入量为1.7-2.5kg/t钢。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述转炉冶炼步骤中，所述合金化采用的合金包括：金属锰、硅铁、铌铁、钒铁和镍板。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述LF精炼步骤，所述调渣所用的物质为铝渣和碳化钙，优选地，所述调渣所用的物质还包括石灰；优选地，调渣至终渣碱度≥2.2，出站前顶渣必须为黄白渣或白渣，黄白渣或白渣保持时间不低于10分钟。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述LF精炼步骤，在所述调渣后，喂入铝线进行增铝，喂入钛线进行增钛。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述LF精炼步骤，所述精炼的时间为30-45min。在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述LF精炼步骤，调渣所用渣料的质量比为：石灰：萤石：碳化钙：铝渣＝(3-5)：(3-5)：1：(1-2)，优选地，石灰：萤石：碳化钙：铝渣＝(4-5)：(4-5)：1：(1-2)。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述RH脱气步骤中，所述真空脱气时，真空度为≤133Pa，环流时间不低于15分钟，纯脱气时间大于5分钟。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述RH脱气步骤中，所述真空脱气之后，喂入钙铝线80-100米/炉，软吹不低于10分钟。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述连铸步骤中，所述钢液的过热度控制在25℃以内。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述连铸步骤中，对于175断面，所述连铸时拉速为1.25-1.35m/min；对于200断面，所述连铸时拉速为1.2-1.4m/min；对于250断面，所述连铸时拉速为1.1-1.3m/min；对于300mm断面，所述连铸时拉速为0.85-0.95m/min；
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，在所述连铸步骤中，结晶器采用包晶钢保护渣；中间包采用覆盖剂结合碳化稻壳覆盖，保证中间包液面覆盖良好：大包长水口采用氩封，流量90-120L/min；若流量＜90L\min时，难以起到隔绝空气效果，若流量＞120L\min，则浪费氩气。
在上述极地用钢的超高磷铁水低成本冶炼方法中，作为一种优选实施方式，按质量百分比，所述冶炼方法得到的钢成分中P含量低于0.007％；更优选地，所述所述冶炼方法得到的钢成分按质量百分比包括：C：0.06-0.10％，Si：0.20-0.35，Mn：1.5-1.65％，Nb：0.010-0.030％，V：0.010-0.035％，Ti：0.010-0.035％，，Al：0.015-0.040。
与现有技术相比，本发明的有益效果是
1.本申请所述极地用钢的超高磷铁水冶炼低磷钢的方法根据铁水硅含量判定是否采取双渣工艺，若铁水硅≥0.30％时，转炉冶炼采用双渣工艺；铁水硅＜0.30％时：转炉采用单渣工艺，再采用精炼深脱磷工艺进一步脱磷，该方法可实现以超高磷铁水为原料连续稳定冶炼磷含量低于0.007％的钢，且所需辅料消耗较低，生产节奏快，具有广阔的推广前景。
2.根据铁水Si含量进行区分单双渣区冶炼，大幅度节约冶炼原料消耗，缩短冶炼周期，加快生产流程。
3.对超高P铁水采用最优化造渣料配比及合理的吹氧流量、吹氧时间，通过转炉冶炼获得超低磷铁水。
4.LF精炼阶段，采用合理的渣料配比及冶炼方式，减少钢水回P量。
5.本申请所述极地用钢的超高磷铁水冶炼低磷钢的方法成本相对低廉，工艺简单易于操作，本冶炼方法生产的铸坯轧制的钢板适合应用于极寒工况、综合性能要求高的工程中。
6.本方法冶炼、连铸后的钢坯，经轧制后，钢板屈服强度≥420MPa、抗拉强度520-680MPa、-52℃冲击功≥100J、断面收缩率≥19％。
具体实施方式
为了突出表达本发明的目的、技术方案及优点，下面结合实施例对本发明进一步说明，示例通过本发明的解释方式表述而非限制本发明。本发明技术方案不局限于以下所列举的具体实施方式，还包括各具体实施方式之间的任意组合。
本说明书中公开的任一特征，除非特别叙述，均可被其他等效或具有类似目的的替代特征加以替换。除非特别叙述，每个特征只是一系列等效或者类似特征中的一个例子而已。
实施例1
一种极地用钢的超高磷铁水冶炼低磷钢的方法：
(1)转炉冶炼
采用140t顶底复吹转炉，原料组成为：高磷脱硫铁水141t(C：5.65％、Mn：0.213％、P：0.151％、S：0.002％、Si：0.54％、A S：0.0020％，铁水温度1310℃)，废钢用量为10t。采用双渣工艺进行冶炼，在冶炼时，氧气第一次下枪开吹阶段，枪位控制在1500mm左右。氧枪打火后，氧枪流量调整为25000m 3/h左右，枪位在1800mm，加入石灰3050kg，烧结矿3600kg，白云石400kg，第一批料在开吹150s前加入完毕。初渣化透后30秒提枪倒渣，提枪时机原则上在5分钟左右。
二次下枪氮气打渣后切换氧气，待氧枪打火后，氧枪流量调整为24500m 3/h左右，枪位在1700mm左右，随后分批次共加入石灰3200kg、烧结矿2700kg、白云石550kg，同时避免吹炼返干。TSC温度在1540℃-1590℃，碳含量控制在0.25％-0.40％，测完TSC后，加入150kg石灰，调整TSO温度为1600℃-1650℃。最后采用高-低-低枪位(2000mm-1500mm-500mm)进 行溅渣护炉，溅渣过程重复提压抢，渣溅干后关氮提枪，溅渣时间为186s。当转炉碳氧积≤0.0021，转炉测量终点碳≤0.045wt％时出钢，转炉出钢温度为1620℃，出钢时加入铝锰铁260kg、金属锰2100kg、镍板120kg、钒铁60kg、铌铁50kg、硅铁440kg；顺钢流加入600kg合成渣，200Kg预熔渣。
冶炼全程底吹氮气和氩气，冶炼前8分钟，底吹氮气，其中前3min氮气流量为500m 3/h，后5min氮气流量增加为850m 3/h；冶炼底吹氮气8分钟后切换为氩气，氩气气流量增加到1050m 3/h。
(2)LF冶炼
LF精炼加入石灰200kg、萤石200kg、碳化钙50kg、铝渣80kg进行调渣；喂铝线150m进行增铝，喂入钛线130m增钛。终渣碱度控制在2.2以上。
冶炼过程全程底吹氩搅拌，前期可适当调高氩气压力，出站前采用小压力软吹，保证夹杂物上浮，精炼软吹氩时间为5分钟，总体精炼时间为45分钟。
(3)RH冶炼
RH处理时，浸渍管***深度为400mm；处理时真空度为30Pa，环流时间为22分钟，纯脱气时间10分钟。RH处理结束后，喂钙铝线90米/炉，软吹10分钟，RH冶炼周期为23分钟。
(4)连铸
结晶器采用包晶钢保护渣；中间包采用覆盖剂结合碳化稻壳覆盖，保证中间包液面覆盖良好。大包长水口采用氩封，流量90L/min，结晶器采用非正弦振动模式。连铸坯断面尺寸为250mm*2400mm，拉速为1.1m/min。
该炉次终点情况C：0.07％，Si：0.28％，Mn：1.52％，P：0.006％，S：0.001％，Nb：0.025％，Ti：0.015％，V:0.025％，Ni：0.11％，Als:0.020％；该炉消耗情况为：石灰48.53kg/吨钢，渣料总消耗为54.41kg/吨钢，氧气消耗为47.05Nm 3/吨钢。
采用本实施例方法生产5炉次钢，钢中P含量都低于0.007wt％，所得钢坯经轧制后，钢板屈服强度425-510MPa、抗拉强度520-590MPa、-60℃冲击功150-210J、断面收缩率22-32％。
实施例2：
一种极地用钢的超高磷铁水冶炼低磷钢的方法：
(1)转炉冶炼
采用140t顶底复吹转炉，原料组成为：高磷脱硫铁水92％(C：4.437％、Mn：0.213％、P：0.148％、S：0.003％、Si：0.294％、A S：0.0018％，铁水温度1316℃)，余量为废钢。在冶炼时采用单渣工艺，氧气下枪开吹阶段，枪位控制在1500mm左右；氧枪打火后，氧枪流量调整为26000m 3/h左右，枪位在1800mm，供氧气压力为0.8MPa；冶炼前8分钟，底吹氮气，氮气底吹流量为560m 3/h，而后增加为880m 3/h，底吹8分钟后切换为氩气，流量增加到1200m 3/h，加入烧结矿6200kg，石灰6040kg，白云石800kg，保证后期碱度并促进渣化透；终点枪位控制在1200mm左右。最后采用高-低-低枪位(2000mm-1500mm-500mm)进行溅渣护炉，溅渣过程重复提压抢，渣溅干后关氮提枪，溅渣时间为163s。转炉出钢温度为1646℃，出钢时加入铝锰铁240kg、金属锰2040kg、镍板120kg、钒铁60kg、铌铁50kg、硅铁440kg；顺钢流加入600kg合成渣、200Kg预熔渣。
(2)LF冶炼
LF精炼加入石灰352kg、萤石157kg、铝渣180kg，碳化钙20Kg进行调渣；喂铝线120m进行增铝，喂入钛线150m增钛。终渣碱度控制在2.2以上。
冶炼过程全程底吹氩搅拌，前期可适当调高氩气压力，出站前采用小压力软吹，保证夹杂物上浮，软吹氩时间为5分钟，总冶炼时间为42分钟。
(3)RH冶炼
RH处理时，浸渍管***深度为400mm；处理时真空度为30Pa，环流时间为22分钟，纯脱气时间10分钟。RH处理结束后，喂钙铝线80米，软吹10分钟，RH冶炼周期为22分钟。
(4)连铸
结晶器采用包晶钢保护渣；中间包采用覆盖剂结合碳化稻壳覆盖，保证中间包液面覆盖良好。大包长水口采用氩封，流量90L/min，结晶器采用非正弦振动模式。连铸坯断面尺寸为300mm，拉速为0.85m/min。
该炉次终点情况C：0.07％，Si：0.27％，Mn：1.51％，P：0.0065％，S：0.001％，Nb：0.026％，Ti：0.015％，V:0.026％，Ni：0.12％，Als:0.020％该炉消耗情况为：石灰47kg/吨钢，渣料总消耗为51.5kg/吨钢，氧气消耗为 47.79Nm 3/吨钢，钢铁料消耗1.10t/吨钢。
采用本实施例方法生产5炉次钢，钢中P含量都低于0.007wt％，所得钢坯经轧制后，钢板屈服强度440-500MPa、抗拉强度525-605MPa、-60℃冲击功130-190J、断面收缩率23-29％。

Claims (10)

  1. 一种极地用钢的超高磷铁水低成本冶炼方法，其特征在于，依次包括：
    转炉冶炼步骤：对包括铁水的原料进行冶炼、脱氧和出钢合金化；
    LF精炼步骤：对所述转炉冶炼步骤所得的钢液进行调渣、精炼，得到精炼钢液；
    RH脱气步骤：对所述精炼钢液进行真空脱气；
    连铸步骤：对所述RH脱气步骤后所得的钢液进行连铸，得到铸坯。
  2. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，在所述转炉冶炼步骤中，当作为原料的所述铁水中P元素的含量≥0.15wt％时，Si元素的含量为0.15-0.6wt％，S元素的含量为≤0.006wt％，As元素的含量为≤0.006wt％；优选地，所述铁水的温度≥1230℃；
    优选地，在所述转炉冶炼步骤中，所述原料还包括废钢；
    优选地，所述废钢的质量/(铁水+废钢的质量)≤8％。
  3. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，在所述转炉冶炼步骤中，当作为原料的所述铁水中硅的质量含量≥0.30％时，采用双渣工艺进行所述冶炼；
    优选地，所述双渣工艺具体包括：步骤1)：向所述原料中加入一部分的渣料，之后采用氧枪向所述原料中吹氧气，待初渣化透后，将氧枪提出转炉、进行倒渣；步骤2)：采用氧枪向步骤1)所得的钢液中吹氧气，然后分批加入剩余的所述渣料，继续进行冶炼，冶炼过程中测定钢水的TSC温度和C含量，根据测定结果选择加入石灰或烧结矿，以保证后期碱度并促进渣化透；
    优选地，在所述步骤2)中，从加入剩余的所述渣料到测定钢水的TSC温度和C含量之间的时间为70-90s；
    优选地，所述步骤2)的总反应时间为240-300s；
    优选地，所述渣料包括造渣剂和冷却剂；
    优选地，所述造渣剂为石灰和白云石；所述冷却剂为烧结矿；
    优选地，在所述步骤1)中，所述石灰的加入量为20-22.5kg/吨钢，所述 白云石的加入量3.5-5.5kg/吨钢，所述烧结矿的加入量为28.5-32kg/吨钢；
    优选地，在步骤1)中，所述吹氧气的时间为5-6min；
    优选地，在步骤1)中，待初渣化透后，15-30s内将氧枪提出转炉；
    优选地，在所述步骤2)的所述渣料中，所述石灰的加入量为21-25kg/吨钢，所述白云石的加入量为3.5-5.0kg/吨钢，所述烧结矿的加入量为14-20kg/吨钢；
    优选地，在所述步骤2)中，所述TSC温度控制为1540℃-1590℃，碳含量控制为0.25wt％-0.40wt％；
    优选地，在所述步骤2)中，根据测定的TSC温度结果选择加入所述石灰或烧结矿继续吹炼，以保证转炉TSO温度控制为1600℃-1650℃，碳含量控制为0.07wt％-0.09wt％；
    优选地，若所述转炉TSO温度小于1600℃，则进行点吹升温。
  4. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，在所述转炉冶炼步骤中，当作为原料的所述铁水中硅的质量含量＜0.30％时，采用单渣工艺进行冶炼；
    优选地，所述单渣工艺的具体过程为：步骤a)向所述原料加入石灰、烧结矿和白云石，步骤b)待全程渣子化透，测量TSC，然后根据测定TSC结果选择加入石灰或烧结矿；
    优选地，在所述步骤a)中，所述石灰分2-3批次加入，吨钢加入量为42.9-46.2kg/t；
    优选地，所述烧结矿分3-4批次加入，吨钢加入量为39.2-42.8kg/t；
    优选地，所述白云石分2-3批次加入，吨钢加入量为8.57-10.7kg/t；
    优选地，在所述步骤b)中，每吨所述铁水中，所述石灰或烧结矿的加入量为2.15-3.57Kg；
    优选地，当TSC≤1540℃时，加入所述石灰继续吹氧冶炼；当TSC≥1590℃时，加入烧结矿；
    优选地，在所述步骤b)中，根据TSO的测定结果，若C含量≥0.10％，则进行点吹，以控制钢水的C、P含量。
  5. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，在所述转炉冶炼步骤中，冶炼全过程采用转炉底吹氮气和氩气；
    优选地，在所述转炉冶炼步骤中，冶炼前7-8分钟，底吹氮气，其中前1-3min氮气流量为450-580Nm 3/h，后期氮气流量增加为800-900Nm 3/h；冶炼底吹氮气7-8分钟后切换为氩气，氩气气流量增加到1000-1100Nm 3/h；
    优选地，在所述转炉冶炼步骤中，当转炉碳氧积≤0.0021，转炉测量终点碳≤0.045％时，直接出钢；当转炉碳氧积＞0.0032时，需等转炉TSO成分测定为C：0.06-0.09wt％，P≤0.006wt％，S≤0.020wt％时，方能出钢；转炉碳氧积在0.0021-0.0032之间时，炉测量终点碳需要≤0.045％，否则进行点吹。
  6. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，在所述转炉冶炼步骤中，在所述冶炼之后，所述脱氧之前，采用高-低-低枪位利用氮气进行溅渣护炉，溅渣过程重复提压抢，渣溅干后关氮提枪，溅渣时间为140-200s；
    优选地，采用铝锰铁进行所述脱氧，所述铝锰铁的加入量为1.7-2.5kg/t钢；
    优选地，所述合金化采用的合金包括：金属锰、硅铁、铌铁、钒铁和镍板。
  7. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，在所述LF精炼步骤，所述调渣所用的物质为铝渣和碳化钙：
    优选地，所述调渣所用的物质还包括石灰；
    优选地，调渣至终渣碱度≥2.2，出站前顶渣必须为黄白渣或白渣，黄白渣或白渣保持时间不低于10分钟；
    优选地，在所述调渣后，喂入铝线进行增铝，喂入钛线进行增钛；
    优选地，所述精炼的时间为30-45min；
    优选地，调渣所用渣料的质量比为：石灰：萤石：碳化钙：铝渣＝(3-5)：(3-5)：1：(1-2)。
  8. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，在所述RH脱气步骤中，所述真空脱气时，真空度为≤133Pa，环流时间不低于15分钟，脱气时间大于5分钟；
    优选地，在所述RH脱气步骤中，所述真空脱气之后，喂入钙铝线80-100米/炉，软吹不低于10分钟。
  9. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，在所述连铸步骤中，所述钢液的过热度控制在25℃以内；
    优选地，在所述连铸步骤中，对于175断面，所述连铸时拉速为1.25-1.35m/min；对于200断面，所述连铸时拉速为1.2-1.4m/min；对于250断面，所述连铸时拉速为1.1-1.3m/min；对于300mm断面，所述连铸时拉速为0.85-0.95m/min；
    优选地，在所述连铸步骤中，结晶器采用包晶钢保护渣；中间包采用覆盖剂结合碳化稻壳覆盖，保证中间包液面覆盖良好：大包长水口采用氩封，流量90-120L/min。
  10. 根据权利要求1所述的极地用钢的超高磷铁水低成本冶炼方法，其特征在于，按质量百分比，所述冶炼方法得到的钢成分中P含量低于0.007wt％；
    更优选地，所述冶炼方法得到的钢成分按质量百分比包括：C：0.06-0.10％，Si：0.20-0.35，Mn：1.5-1.65％，Nb：0.010-0.030％，V：0.010-0.035％，Ti：0.010-0.035％，Al：0.015-0.040％。
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