WO2022042621A1 - 一种超薄热轧宽带钢的制造方法 - Google Patents

一种超薄热轧宽带钢的制造方法 Download PDF

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WO2022042621A1
WO2022042621A1 PCT/CN2021/114657 CN2021114657W WO2022042621A1 WO 2022042621 A1 WO2022042621 A1 WO 2022042621A1 CN 2021114657 W CN2021114657 W CN 2021114657W WO 2022042621 A1 WO2022042621 A1 WO 2022042621A1
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hot
steel
thin
rolled
iron
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PCT/CN2021/114657
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English (en)
French (fr)
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方园
张健
吴建春
支卫军
彭程
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宝山钢铁股份有限公司
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
    • 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
    • C21C5/52—Manufacture of steel in electric furnaces
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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 technical field of continuous production of metal sheets and strips, and particularly relates to a method for manufacturing ultra-thin hot-rolled wide-band steel.
  • Nippon Steel has developed stainless steel Two-roll continuous casting and rolling technology DSC, American Nucor Corporation, Japan IHI, Australia BHP jointly developed the carbon steel two-roll continuous casting and rolling technology Castrip, South Korea's Posco developed stainless steel two-roll continuous casting and rolling technology Rolling technology poStrip, Europe jointly developed the stainless steel twin-roll continuous casting and rolling technology Eurostrip, China Baosteel developed the carbon steel twin-roll thin strip continuous casting and rolling technology Baostrip.
  • molten steel is mainly supplied to thin strip continuous casting through electric furnace or converter.
  • converter steelmaking to provide molten steel requires the manufacturer to have the conditions to provide molten iron.
  • blast furnace ironmaking or non-blast furnace ironmaking equipment is required, which belongs to the current long-process iron and steel production mode.
  • scrap steel is used as the main raw material.
  • Traditional processes such as die casting or thick plate continuous casting have a solidification and cooling rate of only 1 to 10 °C/s. These residual elements in scrap steel will be in the solidification process. Grain boundary segregation occurs, which deteriorates the performance and quality of steel. In severe cases, cracking and fracture occur directly. Therefore, in the traditional process, these harmful elements must be strictly controlled.
  • some pre-screening is required, and In the steelmaking process, some special treatments are required, such as adding some concentrate for dilution, etc., which undoubtedly increases the cost of production operations. Due to the need to control the composition of the steel, there are certain quality requirements for the scrap steel raw materials used.
  • the scrap steel needs to be pre-screened and classified.
  • Steel mills with blast furnaces and electric furnaces at the same time use self-produced molten iron to be mixed into electric furnaces as raw materials for electric furnaces to improve the production efficiency of electric furnaces, thereby greatly shortening the tapping time of electric furnaces, and the blending ratio of molten iron in electric furnaces can reach 30-50%.
  • the purpose of the present invention is to provide a method for manufacturing ultra-thin hot-rolled wide-band steel, which greatly simplifies the process flow, and the thickness of the obtained thin-gauge steel plate can reach the thickness of the steel plate after cold rolling, truly realizes "replacing cooling with heat", and greatly improves the product quality.
  • Competitiveness the overall process is more environmentally friendly, more efficient, high heat utilization rate, high metal yield, this method not only directly reduces the cost of thin gauge strip, but also can significantly reduce the one-time investment cost.
  • the technical scheme of the present invention is:
  • a method for manufacturing ultra-thin hot-rolled wide-band steel comprising the steps of:
  • iron powder, coal powder and lime powder evenly, press them into pellets or agglomerates and dry them; place the pellets or agglomerates in the rotary hearth furnace, heat the rotary hearth furnace, and make the pellets or agglomerates in the rotary hearth furnace.
  • the agglomerates are reduced, carburized, and melted, and then rapidly water-cooled to 750-850° C., and the granulated iron and slag are separated and discharged respectively;
  • the weight ratio of the iron powder, coal powder and lime powder is 70-80: 15- 25:3 ⁇ 7, the heating temperature of the rotary hearth furnace is 1350 ⁇ 1450°C;
  • the granulated iron prepared above is transported into the electric furnace to be mixed with the scrap steel preheated by the electric furnace preheating device, and then melted and smelted to obtain molten steel; 400 ⁇ 900°C;
  • the molten steel flowing out of the electric furnace is subjected to VD vacuum degassing and LF refining in sequence;
  • Continuous casting adopts twin-roll thin strip continuous casting to obtain cast strips with a thickness of 1.5 to 2.5 mm and a width of 1000 to 1600 mm;
  • the molten steel pouring temperature is T+(30 to 80) °C, where T is the liquidus temperature, and the cast strip is The temperature is 1300 ⁇ 1450°C, the inside of the crystallizing roller is cooled by water, and the casting speed of the casting machine is 60 ⁇ 150m/min;
  • the cast strip is sent to the double-stand rolling unit through the pinch rollers for hot continuous rolling, and the reduction rate of a single stand is ⁇ 50%; the thickness of the steel plate after hot continuous rolling is 0.4 to 2.0 mm;
  • the hot-rolled steel sheet is atomized and cooled, and the cooled steel sheet is cut or slit and sent to a coiler for coiling; the coiling temperature is 400-750°C.
  • the content of iron fine powder is 70-80%, the content of coal powder is 15-25%, and the content of lime powder is 3-7%.
  • the steel coil obtained after the coiling is air-cooled or slow-cooled after being coded and bundled.
  • the air-cooled or slow-cooled steel coil is trimmed and leveled to obtain a black skin coil; or a hot-rolled hot-dip galvanized coil is obtained by pickling and galvanizing; or a hot-rolled pickled coil is obtained by pickling and leveling ; or trimming, leveling, and jet descaling to obtain thin-gauge hot-rolled coils.
  • the iron concentrate is one or more of magnetite powder, hematite powder, limonite powder or siderite powder.
  • the pulverized coal is one or more of non-coking pulverized coal, ordinary pulverized coal, and petroleum coke.
  • the scrap steel is one or more of light and thin material, general waste, and heavy waste.
  • step 2) the way of conveying the granulated iron and scrap steel into the electric furnace is continuous conveying or intermittent conveying.
  • the thickness of the steel plate after hot continuous rolling in step 5) is 0.4-0.6 mm.
  • the coiling in step 6) adopts Carrousel coiling.
  • the total reduction ratio is greater than or equal to 50%, preferably greater than or equal to 80%.
  • a protective cover is provided at the belt outlet of the crystallization roll, and an inert gas is passed through the protective cover, so as to reduce the influence of high temperature oxidation on the cast belt.
  • step 5 adopts a two-stand four-high hot tandem rolling mill for hot tandem rolling.
  • the rotary hearth furnace + electric furnace is used to complete molten steel smelting, and the molten steel composition adjustment and inclusion control are completed through vacuum degassing (VD) and refining furnace (LF), and then through twin-roll thin strip continuous casting +
  • VD vacuum degassing
  • LF refining furnace
  • the invention designs an extremely streamlined and intensive metallurgical production process through the organic combination of rotary hearth furnace preparation of granulated iron, electric furnace smelting molten steel, double-roller thin strip continuous casting and double-stand hot rolling processes, which can not only reduce one time It also reduces the carbon emission, energy consumption, and metal consumption, and reduces the processing cost of thin-gauge strip steel products. It can directly obtain products with cold-rolled thickness specifications, and truly realize "replacing cooling with heat", which greatly improves the product competitiveness.
  • Rotary hearth furnace production of granulated iron is an environmentally friendly short-flow granulated iron production process, and this process can continuously and economically produce granulated iron, and iron fine powder (iron fine powder is iron ore after crushing, grinding, beneficiation)
  • iron fine powder also includes oxidized dust recovered from iron and steel plants
  • coal powder and lime powder are mixed in a certain proportion
  • pellets or agglomerates are obtained by pelletizing or briquetting machine, and dried. Then, as the raw material for the production of granulated iron in the rotary hearth furnace, the dried pellets or agglomerates are put into the rotary hearth furnace.
  • the briquette passes through the charging area, the smoke exhaust area, the preheating area, the medium temperature reduction area, the high temperature reduction area and the discharge area in turn), and is heated to 1350 ⁇ 1450 °C under the static state of the pellets or briquette and the hearth. Reduction, carburizing and melting reactions, the slag and iron are melted and aggregated separately. The whole process takes about 10 minutes (coal powder and iron oxides are in close contact, and the reduction speed is very fast) to complete the reduction and fusion; After rapid cooling to 750 ⁇ 850 ° C, the discharge device is used to complete the separate discharge of granulated iron and slag.
  • the traditional method of using the rotary hearth furnace is to cool the produced granulated iron to room temperature, then bag it for external sales, or transport it to the steelmaking process as a steelmaking raw material.
  • the present invention utilizes the high-temperature granulated iron at 750-850°C produced by the rotary hearth furnace to be directly transported into the electric furnace through the conveyor belt, and greatly utilizes the waste heat of the high-temperature granulated iron to preheat the mixed scrap steel and improve the thermal efficiency of the electric furnace. , reducing energy consumption.
  • the iron concentrate powder of the present invention can be one or more of magnetite powder, hematite powder, limonite powder or siderite powder, the source of raw materials is wide, and there is no strict requirement on the grade of raw materials;
  • the annual output of granulated iron in a rotary hearth furnace is 50,000 to 200,000 tons.
  • the non-coking coal pulverized coal refers to coal that cannot be coked with a single coal, including lignite, bituminous coal and anthracite.
  • Petroleum coke is a product obtained by separating light and heavy oil from crude oil by distillation, and then converting heavy oil through thermal cracking.
  • Ordinary coal is relative to industrial coal.
  • Industrial coal mainly refers to coking coal used to make coke, while ordinary coal is mainly used for residential heating.
  • the granulated iron produced by the rotary hearth furnace is transported to the electric furnace to be mixed with scrap steel to complete molten steel smelting.
  • the scrap steel is continuously or intermittently transported to the preheating device.
  • the electric furnace has its own preheating device. After preheating, it is mixed with granulated iron and then smelted in the electric furnace, which can reduce heat loss. Raise the preheating temperature of scrap steel, make the scrap steel preheat temperature to 400 ⁇ 900°C, and at the same time utilize the temperature of pellet iron produced, which greatly reduces the power consumption of the electric furnace and effectively improves the thermal efficiency of the electric furnace.
  • the requirements for scrap steel quality can be greatly reduced, the amount of scrap steel added to the electric furnace can also be increased, and the weight ratio of granulated iron to scrap steel can be expanded to 1:2 ⁇ 9, 1:3-9 are preferable, and 1:4-9 are more preferable.
  • the obtained molten steel is transported to the refining station for processing.
  • decarburization, desulfurization, and dehydrogenation are performed in the VD vacuum degasser, and then the composition adjustment and temperature increase are performed in the LF refining furnace.
  • the refining of molten steel before the conventional continuous casting process is generally first processed by the LF refining furnace, and then processed in the VD furnace; however, the refined molten steel needs to be cast through the thin strip continuous casting process. , and then enter the LF refining furnace for processing.
  • the refined molten steel undergoes twin-roll thin-strip continuous casting.
  • the twin-roll thin-strip continuous casting technology is a typical sub-rapid solidification process.
  • the solidification cooling rate is as high as 10 2 ⁇ 10 4 °C/s.
  • the scrap does not need any pre-screening and can be light and thin.
  • one or more of general waste and heavy waste, some harmful residual elements in scrap steel, such as Cu, Sn, P, etc. can be solid-dissolved into the steel matrix to the greatest extent without producing grain boundary segregation, thereby playing a role in The effect of solid solution strengthening; it has the effect of "turning harm into benefit” and "waste utilization" for these harmful residual elements, which greatly reduces the cost of raw materials.
  • general waste and heavy waste have the meanings well known in the art.
  • General waste refers to the mixture of various scrap steels
  • heavy waste refers to heavy scrap steel, including automobile girders, bearings, wheels, etc.
  • the thickness of the cast strip after it comes out is thin, the thinnest can reach 1.5mm, and the temperature of the cast strip is also high, generally at 1300 ⁇ 1450 °C.
  • a protective cover, and a certain amount of inert gas (such as N2 or Ar) is passed through the protective cover to form a slight positive pressure in the protective cover to meet the gas protection effect.
  • the obtained cast strip can be steel grades such as medium and low carbon steel, low carbon microalloy steel, alloy steel, stainless steel, electrical steel and the like.
  • Thin strip continuous casting obtains thinner cast strips combined with hot continuous rolling of double-stand rolling units, the reduction rate of a single stand can reach 50%, the total reduction rate can reach 100%, and the thickness of the strip after hot rolling can reach 0.4 ⁇ 0.6mm, the world's first.
  • the present invention adopts a double-stand four-high hot continuous rolling mill, which has the functions of bending and tandem rolls, or the functions of bending and crossing rolls, and has the functions of strip pressing, strip guiding and deviation correction;
  • the four-high rolling mill has the function of online roll changing; the reduction ratio of a single hot rolling mill ranges from 0 to 50%, and the thickness of the finished product after rolling reaches 0.4 to 2.0 mm, of which the thinnest thickness of the hot rolled product reaches 0.4 to 0.6 mm. range.
  • the two rolling mills usually work at the same time, but under special circumstances, if the surface roughness of the work rolls of one rolling mill will increase sharply, causing the surface quality of the strip to deteriorate, the other rolling mill will be put into use.
  • a rolling mill reduction rate of 0% means that the roll gap of the rolling mill is open and does not roll. In one case, it can be used when producing thicker strips (thickness 1.2-2.0 mm), that is, one rolling mill is empty without rolling, and the other is not rolled. The first rolling mill is put into rolling; another situation is that one of the rolling mills has reached the end of its life for online roll change, and the other rolling mill is continuously put into rolling. It can be seen that continuous and stable rolling can be achieved by using the double-stand hot tandem rolling mode, and the online roll change function can overcome the problem of shutdown of the entire line due to surface wear of the work rolls.
  • the specific description of the roll changing process is as follows: When the tonnage of the strip rolled by the No.1 hot rolling mill reaches 400-800t, the surface roughness of the work roll of the rolling mill will increase sharply, causing the surface quality of the strip to deteriorate.
  • the No.2 hot rolling mill is coordinated, that is, the No.1 hot rolling mill is slowly opened, and the No.2 hot rolling mill is slowly pressed down. After the No.1 hot rolling mill is fully opened, the No.2 hot rolling mill is pressed down at this time. After the No. 1 hot rolling mill is in place, the No. 1 hot rolling mill will perform online roll change (work roll) operation. After the change is completed, it will be reset on standby, and the above operation will be repeated when the No. 2 hot rolling mill needs to be replaced.
  • online roll change work roll
  • the strip after hot continuous rolling is continuously produced by the Carrousel double-reel coiler, and the coiling temperature difference of each steel coil can be controlled within 10°C.
  • Coiled 10-30 tons of steel coils are sprayed with code, bundled, and then air-cooled or slow-cooled.
  • the material and mechanical properties of the steel coil that meet the process requirements can be trimmed and leveled to make a black skin coil; or pickled and galvanized to make a hot-rolled hot-dip galvanized coil; or pickled and leveled to make a hot-rolled pickling coil Coils; or trimming, leveling, and jet descaling to obtain thin-gauge hot-rolled coils.
  • Chinese patent application CN201710763021.2 discloses "a direct-reduced iron-based short-flow production process for thin strip steel", which includes the following process steps: 1) direct reduction iron making; 2) electric furnace or converter steelmaking; 3) LF Refining; 4) RH vacuum treatment; 5) Thin strip casting and rolling.
  • the DRI described in the invention is obtained by the shaft furnace smelting technology.
  • the production of DRI takes the shaft furnace process as the main sponge iron production scheme, the reduction temperature is about 1000°C, and the reduced iron is added to the steelmaking furnace (electric furnace, or converter), the amount of raw iron added is 55% to 90% of the total weight of the raw materials.
  • the process for preparing granulated iron in the present invention is completely different from the process for preparing granulated iron in the rotary hearth furnace of the present invention.
  • Steel is the complete production process for the main hot rolled product.
  • US patent US9725780B2 discloses "a process route and production line layout method for connecting an induction furnace to a rod, a wire rod caster, and a rod and wire rod hot rolling mill".
  • This invention uses an induction furnace to melt scrap steel to obtain molten steel. Scrap is pre-screened, and the production efficiency is relatively low.
  • the source of molten steel is different, the subsequent refining process and rolling process are different from those of the present invention, and the final product is also different.
  • Chinese patent application CN201210317195.3 discloses "a method for producing steel strip by using low-temperature on-line static recrystallization", the invention adopts double-stand low-temperature austenite on-line static recrystallization rolling, the rolling temperature is 900-1050 °C, and the total The reduction is 50-70%.
  • the present invention is different from this invention in that the present invention emphasizes how to obtain molten steel, that is, the use of a rotary hearth furnace to prepare granulated iron, and then mixed with scrap steel and smelted in an electric furnace to obtain molten steel, which is not involved in this invention;
  • the rate of reduction can reach 100%, the thinnest thickness of the product can reach 0.4mm, and the maximum total reduction of the invention is only 70%.
  • Chinese patent application CN200910053806.6 discloses "high-strength atmospheric corrosion-resistant steel with Cu 2-x S dispersed precipitates and its manufacturing method", the invention adopts converter top-bottom composite blowing to obtain molten steel, and thin strip continuous casting to obtain cast iron
  • the strip is rolled by a double-stand rolling mill to obtain a strip of 0.6-2.0 mm, wherein the reduction rate of the first stand is not less than 30%, and the reduction rate of the second stand is 0-30%.
  • the present invention is different from this invention in that the present invention adopts a rotary hearth furnace to prepare granulated iron, and then mixes it with scrap steel in an electric furnace to obtain molten steel, and obtains a thinner cast strip through continuous casting of thin strips.
  • the reduction rate can reach 50%, and the thinnest strip produced can reach 0.4mm.
  • the present invention designs an extremely streamlined and intensive metallurgical production process through the organic combination of rotary hearth furnace preparation of granulated iron, electric furnace smelting molten steel, double-roll thin strip continuous casting and double-stand hot rolling processes, which can not only Significantly reduce the one-time investment cost, at the same time greatly simplify the process flow, significantly reduce carbon emissions, energy consumption, metal consumption, electrode consumption, directly reduce the processing cost of thin-gauge strip steel products, and can directly obtain products with cold-rolled thickness specifications , and truly realize "replacing cold with heat", which greatly improves the competitiveness of products.
  • the present invention combines the electric furnace smelting molten steel and the double-roller thin strip process, the weight ratio of granulated iron and scrap steel can reach 1:2-9, a large proportion of light and thin scrap steel can be used, and the molten steel after smelting adopts the double-roller thin strip
  • the continuous casting technology is used for casting.
  • the twin-roll thin strip continuous casting technology is a typical sub-rapid solidification process.
  • the solidification cooling rate is as high as 10 2 ⁇ 10 4 °C/s.
  • Some harmful residual elements in scrap steel such as Cu, Sn, P, etc., It can be dissolved into the steel matrix to the maximum extent without producing grain boundary segregation, thus playing a role in solid solution strengthening; it has the effect of "turning harm into benefit” and "waste utilization” for these harmful residual elements, which greatly improves the Reduce raw material costs.
  • the invention adopts the double-stand hot continuous rolling technology, and the reduction rate of a single stand can reach 50%, and the total reduction rate can reach 100%, so that the thickness of the produced metal strip can reach the thinnest 0.4-0.6mm
  • the thickness of the steel plate obtained by hot rolling in the prior art has not yet been reported to reach 0.4mm; the thickness of the steel plate after hot continuous rolling is 0.4 to 2.0 mm, which can completely replace most of the thickness of 0.4 to 1.2 mm prepared by cold rolling. products, so as to truly realize "replacing cold with heat".
  • the present invention directly mixes granulated iron and scrap steel as raw materials for smelting, effectively utilizes the temperature of granulated iron produced by the rotary hearth furnace, increases the preheating temperature of scrap steel, greatly reduces the power consumption of the electric furnace, and effectively improves the efficiency of the electric furnace. Thermal efficiency, energy saving and environmental protection.
  • the liquid metal is directly cast into thin (thickness ⁇ 2.5mm) cast strips using the twin-roll thin strip technology, replacing the traditional thick slab (thickness> 150mm) hot-rolled sheet after rough rolling and multi-pass hot rolling , to achieve a very compact short process process to meet the requirements of excellent low carbon emissions and short plant construction requirements.
  • FIG. 1 is a schematic diagram of a process of an ultra-thin hot-rolled wide-band steel according to an embodiment of the present invention.
  • 1 Rotary Hearth Furnace; 2: Electric Furnace; 3: VD Vacuum Degassing Furnace; 4: LF Refining Furnace; 5: Ladle Rotary Table; 6: Ladle; 7: Tundish; 8: Crystallizing Roll; 9: Casting Belt ; 10: pinch roller; 11: hot continuous rolling unit; 12: atomization cooling system; 13: flying shear; 14: Carrousel coiler; 15: baler; 16: conveying mechanism.
  • the granulated iron discharged from the rotary hearth furnace 1 is transported to the electric furnace 2, and the scrap preheated by the preheating device is mixed, melted and smelted in the electric furnace 2 for about 40 minutes, and then tapped.
  • the molten steel After being transported to the refining station for processing, the molten steel firstly undergoes decarburization, desulfurization and dehydrogenation in the VD vacuum degassing furnace 3, and then enters the LF refining furnace 4 for composition adjustment and temperature increase.
  • the refined molten steel is transported to the ladle turntable 5 of the twin-roll thin-strip continuous casting unit, and the molten steel pouring temperature is controlled at 40°C above the liquidus line. After the ladle 6 is poured, the molten steel enters the tundish 7 and passes through the tundish. 7. Send the molten steel into the molten pool formed by the two crystallizing rollers 8, and distribute and distribute the molten steel entering the molten pool at the same time. The molten steel is solidified on the two crystallizing rolls 8 of the twin-roll thin-strip continuous casting unit, and a cast strip 9 with a thickness of 2.0 mm of qualified quality is cast. At this time, the temperature of the cast belt 9 is 1340°C.
  • a protective cover is usually added at the belt outlet of the crystallization roll 8, and a certain amount of inert gas (such as N2 ) is passed through the protective cover. ), forming a protective cover with a slight positive pressure to meet the gas protection effect.
  • inert gas such as N2
  • the cast strip 9 protected by the atmosphere smoothly enters the double-stand pinch roll 10 through the guide device, and then enters the double-stand four-high hot tandem rolling line 11.
  • the reduction rate of No.1 hot rolling mill is 40%, and No.2
  • the reduction ratio of the hot rolling mill is 50%, which is used to improve the shape of the strip, and at the same time improve the internal structure and mechanical properties.
  • the rolled strip (thickness 0.6mm) is cooled to 660°C through the atomization cooling system 12 and then coiled, and the coiling temperature in the width direction and the length direction of the plate surface is uniform.
  • the strip is cut by the flying shear 13 (the first coil) or slit, and then rolled by the Carrousel coiler 14.
  • the coiled 25-ton steel coil passes through the coding and baling machine 15. After baling, they are sent to the intermediate steel coil storehouse by the conveying mechanism 16 for air cooling.
  • the hot-rolled strip with the material and mechanical properties that meet the process requirements enters the acid-plating integrated unit in sequence to produce hot-rolled hot-dip galvanized coils.
  • the iron powder, coal powder and lime powder uniformly according to the proportion shown in Table 1, press them into pellets or agglomerates and dry them; place them in the rotary hearth furnace 1, heat the rotary hearth furnace 1, and make the rotary hearth furnace 1.
  • the pellets or agglomerates in 1 are reduced, carburized and melted, and after rapid cooling, the granulated iron and slag are separated and discharged respectively; the heating temperature is 1400°C.
  • the granulated iron discharged from the rotary hearth furnace 1 is transported to the electric furnace 2, mixed with the scrap preheated by the preheating device, and then melted and smelted in the electric furnace 2 for about 50 minutes.
  • the ladle is transported to the refining station for processing.
  • the molten steel is firstly subjected to decarburization, desulfurization and dehydrogenation in the VD vacuum degassing furnace 3, and then enters the LF refining furnace 4 for composition adjustment and heating.
  • the refined molten steel is transported to the ladle turntable 5 of the twin-roll thin-strip continuous casting unit, and the molten steel pouring temperature is controlled at 30°C above the liquidus line. After the ladle 6 is poured, the molten steel enters the tundish 7 and passes through the tundish. 7. Send the molten steel into the molten pool formed by the two crystallizing rollers 8, and distribute and distribute the molten steel entering the molten pool at the same time. The molten steel is solidified on the two crystallizing rolls 8 of the twin-roll thin strip continuous casting unit, and a cast strip 9 with a thickness specification of 1.5 mm with qualified quality is cast. At this time, the temperature of the cast belt 9 is 1360°C.
  • a protective cover is usually added at the exit of the crystal 8, and a certain amount of inert gas (such as Ar) is passed through the protective cover. A slight positive pressure is formed in the protective cover to meet the gas protection effect.
  • inert gas such as Ar
  • the cast strip 9 protected by the atmosphere smoothly enters the double-stand pinch roll 10 through the guide device, and then enters the double-stand four-high hot tandem rolling line 11.
  • the reduction ratio of No.1 hot rolling mill is 47%, and No.2
  • the reduction ratio of the hot rolling mill is 50%, which is used to improve the shape of the strip, and at the same time improve the internal structure and mechanical properties.
  • the rolled strip (thickness 0.4mm) is cooled to 700°C through the atomization cooling system 12 and then coiled, and the coiling temperature in the width direction and the length direction of the plate surface is uniform.
  • the strip is cut by the flying shear 13 (the first coil) or slit, and then rolled by the Carrousel coiler 14.
  • the coiled 25-ton steel coil passes through the coding and baling machine 15. After baling, they are sent to the intermediate steel coil storehouse by the conveying mechanism 16 for air cooling.
  • the hot-rolled strip that meets the material and mechanical performance indicators of the process requirements enters the trimming, leveling, and jet descaling units in sequence, and produces thin-sized hot-rolled coils, which can be "hot-rolled”. Generation cold.
  • the iron powder, coal powder and lime powder uniformly according to the proportion shown in Table 1, press them into pellets or agglomerates and dry them; place them in the rotary hearth furnace 1, heat the rotary hearth furnace 1, and make the rotary hearth furnace 1.
  • the pellets or agglomerates in 1 are reduced, carburized and melted, and after rapid cooling, the iron granules and slag are separated and discharged respectively; the heating temperature is 1420°C.
  • the granulated iron discharged from the rotary hearth furnace 1 is transported to the electric furnace 2, mixed with the scrap preheated by the preheating device, melted and smelted in the electric furnace for about 60 minutes, and then tapped.
  • the molten steel After being transported to the refining station for processing, the molten steel firstly undergoes decarburization, desulfurization and dehydrogenation in the VD vacuum degassing furnace 3, and then enters the LF refining furnace 4 for composition adjustment and temperature increase.
  • the refined molten steel is transported to the ladle turntable 5 of the twin-roll thin-strip continuous casting unit, and the molten steel pouring temperature is controlled at 40°C above the liquidus line. After the ladle 6 is poured, the molten steel enters the tundish 7 and passes through the tundish. 7. Send the molten steel into the molten pool formed by the two crystallizing rollers 8, and distribute and distribute the molten steel entering the molten pool at the same time. The molten steel is solidified on the two crystallizing rolls 8 of the twin-roll thin-strip continuous casting unit, and a cast strip 9 with a thickness of 1.6 mm of qualified quality is cast. At this time, the temperature of the cast belt 9 is 1380°C.
  • a protective cover is usually added at the belt outlet of the crystallization roll 8, and a certain amount of inert gas (such as Ar) is passed through the protective cover. , forming a protective cover with a slight positive pressure to meet the gas protection effect.
  • the cast strip 9 protected by the atmosphere smoothly enters the double-stand pinch roll 10 through the guide device without leader head, and then enters the double-stand four-high hot tandem rolling unit 11.
  • the reduction rate of No.1 hot rolling mill is 50%
  • the reduction rate of No.2 hot rolling mill is 0%, which is used to improve the shape of the strip, and at the same time improve the internal structure and mechanical properties.
  • the tonnage of the No.1 hot rolling mill reaches 400-800t, the surface roughness of the work rolls of the rolling mill will increase sharply, causing the surface quality of the strip to deteriorate. Before that, it can cooperate with the No.2 hot rolling mill. That is, the No.1 hot rolling mill is slowly opened, and the No.2 hot rolling mill is slowly pressed down.
  • the No.1 hot rolling mill After the No.1 hot rolling mill is fully opened, the No.2 hot rolling mill is pressed in place, and the reduction rate reaches 50%. Subsequently, the No. 1 hot rolling mill performs an online roll change (work roll) operation. After the change is completed, it is reset to standby, and the above operation is repeated when the No. 2 hot rolling mill needs to be changed.
  • an online roll change work roll
  • the rolled strip (thickness 0.8mm) is cooled to 600°C through the atomization cooling system 12 and then coiled, and the coiling temperature in the width direction and the length direction of the plate surface is uniform.
  • the strip is cut by the flying shear 13 (the first coil) or slit, and then rolled by the Carrousel coiler 14.
  • the coiled 25-ton steel coil passes through the coding and baling machine 15. After baling, they are sent to the intermediate steel coil storehouse by the conveying mechanism 16 for air cooling.
  • the hot-rolled strip that meets the material and mechanical properties of the process requirements will enter the trimming and leveling unit in sequence according to the quality requirements of the cold-rolled strip at the rear, and the black coil will be produced.
  • Examples 4-10 were carried out in the order of Example 1.
  • the specific process parameters of Examples 4-10 and the foregoing Examples 1-3 are shown in Table 1.

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Abstract

本发明提供一种超薄热轧宽带钢的制造方法。本发明利用铁精粉、煤粉和石灰粉在转底炉内完成粒铁的制备，并将生成的粒铁和废钢作为原料在电炉内进行冶炼，在冶炼时提高废钢预热温度，同时利用粒铁的高温特性，有效提高电炉热效率；之后利用VD真空脱气、LF精炼、双辊薄带连铸和热连轧制备得到钢板。本发明整体工艺流程更紧凑、更环保、更高效、热利用率高、金属收得率更高，降低了薄规格带钢的加工成本，所得钢板厚度能够达到冷轧后钢板厚度，真正实现"以热代冷"，大大提高产品竞争力。

Description

一种超薄热轧宽带钢的制造方法 技术领域
本发明属于金属板带的连续生产技术领域，特别涉及一种超薄热轧宽带钢的制造方法。
背景技术
现代钢铁生产企业为节省投资成本与生产成本，积极对现有生产工艺流程进行技术革新，为此，国内外冶金设备供应商和钢铁制造商纷纷提出自己的新技术理念并付诸于实际开发。针对现有热带钢生产工艺流程长、设备多且复杂的问题，逐步发展了源于亨利·贝塞麦提出的双辊薄带连铸连轧技术的产业化技术，日本新日铁开发了不锈钢双辊薄带连铸连轧技术DSC，美国纽柯公司与日本IHI、澳大利亚BHP合作开发了碳钢双辊薄带连铸连轧技术Castrip，韩国浦项开发了不锈钢双辊薄带连铸连轧技术poStrip，欧洲联合开发了不锈钢双辊薄带连铸连轧技术Eurostrip，中国宝钢开发了碳钢双辊薄带连铸连轧技术Baostrip。
为充分发挥薄带连铸连轧工艺技术优势，许多生产厂家将薄带连铸连轧技术与传统工艺紧密结合，以满足薄带连铸连轧工艺的需求。
连铸连轧生产钢的过程中，主要是通过电炉或转炉给薄带连铸供应钢水。采用转炉炼钢提供钢水，则需要生产厂家具备有提供铁水的条件，一般情况下，需要有高炉炼铁或者非高炉炼铁设备，属于目前长流程钢铁生产模式。
采用电炉炼钢提供钢水，则以废钢为主要原料，传统工艺比如模铸或者厚板连铸，其凝固冷却速度仅有1～10℃/s，废钢中的这些残余元素，会在凝固过程中发生晶界偏析，恶化钢的性能和质量，严重时直接发生开裂、断裂现象，所以在传统工艺中，要对这些有害元素严加控制，在废钢原料的选择上，需要进行一些预筛选，以及在炼钢过程中需要进行一些特殊处理，比如添加一些精料进行稀释等等，这无疑增加了生产作业成本。由于需要控制钢的成分，对采用的废钢原料有一定的质量要求，一般情况下，需要对废钢进行预筛选分类。同时拥有高炉和电炉的钢厂利用自产铁水兑入到电炉中作为电炉原料来提高电炉的生产效率，从而大大缩短电炉的 出钢时间，电炉中的铁水勾兑比可达到30～50％。
发明内容
本发明的目的在于提供一种超薄热轧宽带钢的制造方法，极大精简工艺流程，所得薄规格钢板厚度能够达到冷轧后钢板的厚度，真正实现“以热代冷”，大大提高产品竞争力，整体工艺更环保、更高效、热利用率高、金属收得率高，该方法不仅直接降低了薄规格带钢的成本，而且能够显著降低一次性投资成本。
为达到上述目的，本发明的技术方案是：
一种超薄热轧宽带钢的制造方法，其包括如下步骤：
1)粒铁制备
将铁精粉、煤粉和石灰粉混合均匀，压制成球团或团块并干燥；将球团或团块置于转底炉中，加热转底炉，使转底炉内的球团或团块进行还原、渗碳、熔融，之后快速水冷至750～850℃，将粒铁和渣分离后分别排出；所述铁精粉、煤粉和石灰粉的重量比为70～80：15～25：3～7，转底炉加热温度为1350～1450℃；
2)冶炼
将上述制备的粒铁输送至电炉内与经过电炉预热装置预热后的废钢混合，进行熔化和冶炼，获得钢水；粒铁和废钢的重量比为1:2～9，废钢预热温度为400～900℃；
3)精炼
从电炉流出的钢水依次进行VD真空脱气、LF精炼；
4)连铸
连铸采用双辊薄带连铸，获得厚度为1.5～2.5mm、宽度为1000～1600mm的铸带；钢水开浇温度为T+(30～80)℃，其中T为液相线温度，铸带温度1300～1450℃，结晶辊内部通水冷却，铸机浇铸速度为60～150m/min；
5)热连轧
铸带经夹送辊送至双机架轧机组进行热连轧，单台机架的压下率≤50％；热连轧后钢板厚度为0.4～2.0mm；
6)卷取
热轧后的钢板经过雾化冷却，冷却后的钢板经切头或分切处理后送至卷取 机进行卷取；卷取温度为400～750℃。
进一步，以铁精粉、煤粉和石灰粉的总重计，铁精粉的含量为70～80％，煤粉的含量为15～25％，石灰粉的含量为3～7％。
进一步，所述卷取后获得的钢卷经喷码、打捆后进行空冷或缓冷。
进一步，所述空冷或缓冷后的钢卷进行切边、平整制得黑皮卷；或酸洗、镀锌制得热轧热镀锌卷；或酸洗、平整制得热轧酸洗卷；或切边、平整、射流除鳞，制得薄规格热轧卷。
优选的，所述铁精粉为磁铁矿粉、赤铁矿粉、褐铁矿粉或菱铁矿粉中的一种或多种。
优选的，所述煤粉为非焦煤粉、普通煤粉、石油焦中的一种或多种。
优选的，所述废钢为轻薄料、统废、重废中的一种或多种。
优选的，步骤2)中，粒铁和废钢输送至电炉内的输送方式为连续输送或间歇式输送。
优选的，步骤5)所述热连轧后钢板厚度为0.4～0.6mm。
优选的，步骤6)所述卷取采用卡罗塞尔卷取。
优选的，步骤5)中，总压下率≥50％，优选≥80％。
优选的，步骤5)中，在结晶辊出带口设保护罩，且在保护罩内通惰性气体，以降低铸带受高温氧化的影响。
优选的，步骤5)采用双机架四辊热连轧机组进行热连轧。
在本发明的工艺设计中，采用转底炉+电炉完成钢水冶炼，通过真空脱气(VD)和精炼炉(LF)完成对钢水成分调整和夹杂物控制，之后经过双辊薄带连铸+双机架轧机组完成质量合格、性能优良的超薄热轧带钢卷的生产，实现绿色化、全连续化、智能化、简约化、以热代冷的短流程冶金生产工艺布置。
本发明通过转底炉制备粒铁、电炉冶炼钢水、双辊薄带连铸和双机架热轧工艺的有机结合，设计了一种极其精简的集约化冶金生产工艺，该工艺不仅能降低一次性投资成本，并且显著降低了碳排放、能源消耗、金属消耗，同时降低了薄规格带钢产品的加工成本，可以直接得到冷轧厚度规格的产品，真正实现“以热代冷”，大大提高产品的竞争力。
转底炉生产粒铁工艺是一种环保的短流程粒铁生产工艺，且该工艺能够连续、经济地生产粒铁，将铁精粉(铁精粉是铁矿石经过破碎、磨碎、选矿等加工处理成 的矿粉；本发明中，铁精粉也包括钢铁厂回收的氧化粉尘)、煤粉和石灰粉按一定比例混合，用造球或压块机得到球团或团块，干燥后作为转底炉生产粒铁的原料，将干燥后的球团或团块放入转底炉，料层不能过厚(1～3层为宜)，原料随炉床匀速转动一周(球团或团块依次经过装料区、排烟区、预热区、中温还原区、高温还原区和出料区)，在球团或团块与炉床静止状态下加热到1350～1450℃，发生还原、渗碳及熔融反应，渣铁熔化，各自聚集，整个过程约需10min(煤粉与铁氧化物紧密接触，还原速度很快)完成还原熔分；充分还原熔分后的凝聚态渣铁经快速冷却至750～850℃，之后使用排料装置完成粒铁与渣的分别排出。
转底炉的传统使用方法是将生产的粒铁冷却到室温后，装袋进行对外销售，或者是输送到炼钢工序作为炼钢原料。本发明利用转底炉生产出的750～850℃的高温粒铁直接通过输送带输送至电炉内，大大利用高温粒铁的余热，对混合在一起的废钢起到预热效果，提高电炉的热效率，减少了能源消耗。
本发明所述铁精粉可以是磁铁矿粉、赤铁矿粉、褐铁矿粉或菱铁矿粉中的一种或多种，原料来源广泛，且对原料品位无严格要求；煤粉用非焦煤粉、普通煤、石油焦中的一种或多种；转底炉产生的废烟气经热交换器后除尘排出，实现节能环保要求，一台转底炉粒铁年产量在5～20万吨。本文中，所述非焦煤粉指不能以单种煤炼制成焦的煤，包括褐煤、烟煤和无烟煤。石油焦是原油经蒸馏将轻重质油分离后，重质油再经热裂的过程转化而成的产品。普通煤是相对于工业煤来说的，工业煤主要是指用来做焦炭的焦煤，而普通煤主要是居民取暖用的煤。
转底炉生产的粒铁输送至电炉内与废钢混合后完成钢水冶炼。废钢连续输送或间歇式输送至预热装置中，电炉自带预热装置，预热后与粒铁混合后在电炉内进行冶炼，可以减少热量损耗。提高废钢预热温度，将废钢预热温度至400～900℃，同时利用生产的粒铁温度，大大降低了电炉的电耗，有效提高电炉的热效率。
由于薄带连铸的亚快速凝固特征，对废钢质量的要求可以大幅度降低，加入到电炉内的废钢量也可以增大，粒铁与废钢的重量比例范围可以扩大到1:2～9，优选1:3～9，更优选1:4～9。
获得的钢水被运送至精炼工位进行处理，首先在VD真空脱气装置进行脱碳、脱硫、脱氢，其次在LF精炼炉进行成分调整和升温。常规连铸工艺前的钢水精炼一般是先经过LF精炼炉处理，然后再进入到VD炉处理；但是精炼后的钢水需要经过薄带连铸工艺进行铸造，由于其工艺特点，因此要求先经VD、再进入到LF 精炼炉处理。
精炼后的钢水经过双辊薄带连铸，双辊薄带连铸技术是典型的亚快速凝固过程，凝固冷却速度高达10 2～10 4℃/s，废钢无需任何预筛选，可以是轻薄料、统废、重废中一种或多种，废钢中的一些有害残余元素，比如Cu、Sn、P等，可以最大限度地固溶到钢的基体中而不产生晶界偏析，从而起到固溶强化的作用；对这些有害的残余元素起到“化害为利”，“废物利用”的效果，大大降低原料成本。本文中，统废和重废具有本领域周知含义。统废指各种废钢的混杂物，重废指重型废钢，包括汽车大梁、轴承、轮子等。
铸带出来之后的厚度较薄，最薄可以达到1.5mm，铸带温度也较高，一般在1300～1450℃，为降低铸带受高温氧化等因素的影响，通常在结晶辊出带口增设保护罩，且在保护罩内通一定量的惰性气体(如N 2或Ar)，在保护罩内形成微正压以满足气体保护效果。所得的铸带，可以是中、低碳钢、低碳微合金钢、合金钢、不锈钢、电工钢等钢种。
薄带连铸获得较薄的铸带结合双机架轧机组热连轧，单台机架压下率可到50％，总压下率可达到100％，热轧后板带厚度可达0.4～0.6mm，实现世界首创。
本发明采用双机架四辊热连轧机组，其带有控制板型的弯辊、串辊功能，或弯辊、交叉辊功能，且具有带钢压下、带钢导向、纠偏功能；采用的四辊轧机具有在线换辊功能；单台热轧机的压下率范围为0～50％，轧后成品厚度达到0.4～2.0mm，其中，热轧态产品厚度最薄达到0.4-0.6mm的范围。两台轧机通常情况下同时工作，也可以在特殊情况下如一轧机工作辊表面粗糙度会急剧增大造成带钢表面质量恶化，则另一轧机交叉投入使用。
一台轧机压下率0％表示该轧机辊缝打开不轧，一种情况是在生产较厚(厚度1.2～2.0mm)的带钢时可以采用，即一台轧机空过不轧，另一台轧机投入轧制；另一种情况是其中一台轧机工作辊达到寿命进行在线换辊，另一台轧机持续投入轧制。可见，采用双机架热连轧模式可以实现持续稳定的轧制，在线换辊功能可以克服因工作辊表面磨损而全线停机的问题。
换辊过程具体描述如下：在No.1热轧机轧制带钢吨位达到400-800t时，轧机工作辊表面粗糙度会急剧增大造成带钢表面质量恶化，在此事件发生之前，可以和No.2热轧机进行协同，即No.1热轧机缓慢打开，No.2热轧机缓慢压下，待No.1热轧机完全打开后，此时No.2热轧机压下到位，随后No.1热轧机进行在线换辊(工 作辊)操作，换完后复位待命，等待No.2热轧机需要换辊时重复上述操作。
热连轧后的板带采用卡罗塞尔双卷筒卷取机实现连续生产，每一个钢卷的卷取温度差可以控制在10℃以内。
卷取后的10～30吨的钢卷进行喷码、打捆后进行空冷或缓冷。满足工艺要求的材质和力学性能指标钢卷，可以进行切边、平整制得黑皮卷；或酸洗、镀锌制得热轧热镀锌卷；或酸洗、平整制得热轧酸洗卷；或切边、平整、射流除鳞，制得薄规格热轧卷。
本发明与已有技术的区别及改进之处：
中国专利申请CN201710763021.2公开了“一种基于直接还原铁的薄带钢短流程生产工艺”，该工艺包括如下工艺步骤：1)直接还原炼铁；2)电炉或转炉炼钢；3)LF精炼；4)RH真空处理；5)薄带铸轧。该发明所述的直接还原炼铁采用竖炉冶炼技术得到，直接还原铁的生产以竖炉工艺为主要海绵铁生产方案，还原温度为1000℃左右，还原铁加入到炼钢炉内(电炉、或转炉)，原铁加入量为原料总重量的55％～90％。该发明制备粒铁的工艺与本发明转底炉制备粒铁的工艺完全不同，本发明重点强调了从原料到薄带连铸全流程的可控生产超薄热轧带钢，并以低碳钢为主要热轧产品的完整生产流程。
美国专利US9725780B2公开了“一种采用感应电炉与棒、线材连铸机、棒线材热轧机连接的工艺路线和产线布置方式”，该发明采用感应电炉熔化废钢的方式得到钢水，还需要对废钢进行预筛选，生产效率比较低。钢水来源不同，后序精炼工艺、轧制工艺与本发明均不同，最终产品也不一样。
中国专利申请CN201210317195.3公开了“一种利用低温在线静态再结晶生产钢带的方法”，该发明采用双机架低温奥氏体在线静态再结晶轧制，开轧温度900-1050℃，总压下量50-70％。本发明与该发明不同，本发明强调了钢水如何获得，即详细阐述了采用转底炉制备粒铁，然后与废钢混合在电炉内冶炼得到钢水，而该发明未涉及；本发明的总压下率可达到100％，产品最薄厚度可达0.4mm，而该发明最大总压下量仅为70％。
中国专利申请CN200910053806.6公开了“具有Cu 2-xS弥散析出相的高强度耐大气腐蚀钢及其制造方法”，该发明采用转炉顶底复合吹炼获得钢水，通过薄带连铸获得铸带，采用双机架轧机对带钢进行轧制获得0.6-2.0mm的带钢，其中第一机架压下率不小于30％，第二机架的压下率在0-30％。本发明与该发明不同，本发明 采用转底炉制备粒铁，然后与废钢混合在电炉内冶炼得到钢水，通过薄带连铸得到较薄的铸带，双机架轧机的每台轧机最大压下率都可达到50％，生产的带钢最薄可以达到0.4mm。
本发明的有益效果：
1、本发明通过转底炉制备粒铁、电炉冶炼钢水、双辊薄带连铸和双机架热轧工艺的有机结合，设计了一种极其精简的集约化冶金生产工艺，该工艺不仅能显著降低一次性投资成本，同时极大精简工艺流程，显著降低了碳排放、能源消耗、金属消耗、电极消耗，直接降低了薄规格带钢产品的加工成本，可以直接得到冷轧厚度规格的产品，真正实现“以热代冷”，大大提高产品的竞争力。
2、本发明将电炉冶炼钢水和双辊薄带工艺相结合，粒铁和废钢的重量比可达1:2～9，可以采用大比例的轻薄料废钢，冶炼后的钢水采用双辊薄带连铸技术进行铸造，双辊薄带连铸技术是典型的亚快速凝固过程，凝固冷却速度高达10 2～10 4℃/s，废钢中的一些有害残余元素，比如Cu、Sn、P等，可以最大限度地固溶到钢的基体中而不产生晶界偏析，从而起到固溶强化的作用；对这些有害的残余元素起到“化害为利”，“废物利用”的效果，大大降低原料成本。
3、本发明采用双机架热连轧技术，并且单台机架压下率可达到50％，总压下率可达到100％，使产出的金属板带厚度最薄达到0.4-0.6mm的范围，现有技术使用热轧得到的钢板厚度还未见有达到0.4mm的报道；热连轧后钢板厚度为0.4～2.0mm，可以完全替代冷轧制备厚度规格0.4～1.2mm的大部分产品，从而真正实现“以热代冷”。
4、本发明将粒铁与废钢直接混合作为冶炼原料，高效利用了转底炉生产出来粒铁的温度，并提高了废钢的预热温度，大大降低了电炉的电耗，有效提高了电炉的热效率，节能环保。
5、采用双辊薄带技术直接对液态金属浇注成薄规格(厚度＜2.5mm)铸带，取代传统的厚板坯(厚度＞150mm)通过粗轧与多道次热轧之后的热轧板，实现非常紧凑的短流程工艺，以满足优异的低碳排放要求与较短的厂房建设要求。
附图说明
图1为本发明实施例超薄热轧宽带钢的工艺示意图。1：转底炉；2：电炉；3：VD真空脱气炉；4：LF精炼炉；5：大包回转台；6：大包；7：中间包；8：结晶 辊；9：铸带；10：夹送辊；11：热连轧机组；12：雾化冷却系统；13：飞剪；14：卡罗塞尔卷取机；15：打捆机；16：输送机构。
具体实施方式
下面通过实施例及附图对本发明作进一步说明，但这并非是对本发明的限制，本领域技术人员根据发明的基本思路可以做出修改或改进，但只要不脱离本发明的基本思想，均在本发明的范围之内。
实施例1
将铁精粉、煤粉和石灰粉按表1所示比例混合均匀，压制成球团或团块并干燥；将其置于转底炉1中，加热转底炉1，使转底炉1内的球团或团块进行还原、渗碳、熔融，快速冷却后将粒铁和渣分离后分别排出；加热温度为1380℃。
转底炉1排出的粒铁输送至电炉2，先经过预热装置预热后的废钢进行混合在电炉2中熔化冶炼约40min后出钢，钢水倒入60吨级的钢包，通过台车钢包被运至精炼工位进行处理，钢水首先在VD真空脱气炉3进行脱碳、脱硫、脱氢，其次进入LF精炼炉4进行成分调整和升温。
精炼后的钢水运送至双辊薄带连铸单元的大包回转台5上，钢水开浇温度控制在液相线以上40℃，大包6开浇后，钢水进入中间包7，通过中间包7把钢水送入两个结晶辊8所形成的熔池中，同时对进入熔池的钢水进行分配和布流。钢水在双辊薄带连铸单元的两个结晶辊8上完成凝固，铸造出质量合格的厚度规格2.0mm的铸带9。此时铸带9的温度为1340℃，为降低铸带9受高温氧化等因素影响，通常在结晶辊8出带口增设保护罩，且在保护罩内通一定量的惰性气体(如N 2)，形成保护罩内具有微正压以满足气体保护效果。
受气氛保护的铸带9通过导向装置顺利进入双机架夹送辊10，然后进入双机架四辊热连轧机组11，No.1热轧机的压下率为40％，No.2热轧机的压下率为50％，用于改善带钢的板形，同时改善内部的组织结构和机械性能。
轧制后的带钢(厚度0.6mm)经过雾化冷却系统12降温到660℃之后进行卷取，且保证板面的宽度方向、长度方向的卷取温度均匀。冷却处理后的带钢通过飞剪13切头(第一卷)或分切后，进行卡罗塞尔卷取机14成卷，成卷后的25吨钢卷经过喷码、打捆机15打捆后由输送机构16送入中间钢卷库进行空冷。满足工艺要求的材质和力学性能指标的热轧带钢，顺次进入酸镀一体单元，生产出热轧热镀 锌卷。
实施例2
将铁精粉、煤粉和石灰粉按表1所示的比例混合均匀，压制成球团或团块并干燥；将其置于转底炉1中，加热转底炉1，使转底炉1内的球团或团块进行还原、渗碳、熔融，快速冷却后将粒铁和渣分离后分别排出；加热温度为1400℃。
转底炉1排出的粒铁输送至电炉2，与经过预热装置预热后的废钢进行混合后在电炉2中熔化冶炼约50min后出钢，钢水倒入80吨级的钢包，通过台车钢包被运至精炼工位进行处理，钢水首先在VD真空脱气炉3进行脱碳、脱硫、脱氢，其次进入LF精炼炉4进行成分调整和升温。
精炼后的钢水运送至双辊薄带连铸单元的大包回转台5上，钢水开浇温度控制在液相线以上30℃，大包6开浇后，钢水进入中间包7，通过中间包7把钢水送入两个结晶辊8所形成的熔池中，同时对进入熔池的钢水进行分配和布流。钢水在双辊薄带连铸单元的两个结晶辊8上完成凝固，铸造出质量合格的厚度规格1.5mm的铸带9。此时铸带9的温度为1360℃，为降低铸带9受高温氧化等因素影响，通常在结晶8出带口增设保护罩，且在保护罩内通一定量的惰性气体(如Ar)，形成保护罩内具有微正压以满足气体保护效果。
受气氛保护的铸带9通过导向装置顺利进入双机架夹送辊10，然后进入双机架四辊热连轧机组11，No.1热轧机的压下率为47％，No.2热轧机的压下率为50％，用于改善带钢的板形，同时改善内部的组织结构和机械性能。
轧制后的带钢(厚度0.4mm)经过雾化冷却系统12降温到700℃之后进行卷取，且保证板面的宽度方向、长度方向的卷取温度均匀。冷却处理后的带钢通过飞剪13切头(第一卷)或分切后，进行卡罗塞尔卷取机14成卷，成卷后的25吨钢卷经过喷码、打捆机15打捆后由输送机构16送入中间钢卷库进行空冷。满足工艺要求的材质和力学性能指标的热轧带钢，按照后部冷轧带钢的质量要求，顺次进入切边、平整、射流除鳞单元，出薄规格热轧卷，可“以热代冷”。
实施例3
将铁精粉、煤粉和石灰粉按表1所示的比例混合均匀，压制成球团或团块并干燥；将其置于转底炉1中，加热转底炉1，使转底炉1内的球团或团块进行还原、 渗碳、熔融，快速冷却后将粒铁和渣分离后分别排出；加热温度为1420℃。
转底炉1排出的粒铁输送至电炉2，与经过预热装置预热后的废钢进行混合在电炉中熔化冶炼约60min后出钢，钢水倒入100吨级的钢包，通过台车钢包被运至精炼工位进行处理，钢水首先在VD真空脱气炉3进行脱碳、脱硫、脱氢，其次进入LF精炼炉4进行成分调整和升温。
精炼后的钢水运送至双辊薄带连铸单元的大包回转台5上，钢水开浇温度控制在液相线以上40℃，大包6开浇后，钢水进入中间包7，通过中间包7把钢水送入两个结晶辊8所形成的熔池中，同时对进入熔池的钢水进行分配和布流。钢水在双辊薄带连铸单元的两个结晶辊8上完成凝固，铸造出质量合格的厚度规格1.6mm的铸带9。此时铸带9的温度为1380℃，为降低铸带9受高温氧化等因素影响，通常在结晶辊8出带口增设保护罩，且在保护罩内通一定量的惰性气体(如Ar)，形成保护罩内具有微正压以满足气体保护效果。
受气氛保护的铸带9通过无引带头的导向装置顺利进入双机架夹送辊10，然后进入双机架四辊热连轧机组11，No.1热轧机的压下率为50％，No.2热轧机的压下率为0％，用于改善带钢的板形，同时改善内部的组织结构和机械性能。在No.1热轧机轧制带钢吨位达到400-800t时，轧机工作辊表面粗糙度会急剧增大造成带钢表面质量恶化，在此之前，可以和No.2热轧机进行协同，即No.1热轧机缓慢打开，No.2热轧机缓慢压下，待No.1热轧机完全打开后，此时No.2热轧机压下到位，压下率达到50％，随后No.1热轧机进行在线换辊(工作辊)操作，换完后复位待命，等待No.2热轧机需要换辊时重复上述操作。
轧制后的带钢(厚度0.8mm)经过雾化冷却系统12降温到600℃之后进行卷取，且保证板面的宽度方向、长度方向的卷取温度均匀。冷却处理后的带钢通过飞剪13切头(第一卷)或分切后，进行卡罗塞尔卷取机14成卷，成卷后的25吨钢卷经过喷码、打捆机15打捆后由输送机构16送入中间钢卷库进行空冷。满足工艺要求的材质和力学性能指标的热轧带钢，按照后部冷轧带钢的质量要求，顺次进入切边、平整单元，出黑皮卷。
按照实施例1的顺序实施实施例4-10。实施例4-10以及前述实施例1-3的具体工艺参数见表1。
表1
Figure PCTCN2021114657-appb-000001

Claims (14)

  1. 一种超薄热轧宽带钢的制造方法，其特征是，包括如下步骤：
    1)粒铁制备
    将铁精粉、煤粉和石灰粉混合均匀，压制成球团或团块并干燥；将球团或团块置于转底炉中，加热转底炉至1350～1450℃，使转底炉内的球团或团块进行还原、渗碳、熔融，之后快速水冷至750～850℃，将粒铁和渣分离后分别排出；其中，所述铁精粉、煤粉和石灰粉的重量比为70～80：15～25：3～7；
    2)冶炼
    将上述制备的750～850℃的粒铁输送至电炉内，与经过电炉预热装置预热后的废钢混合，进行熔化和冶炼，获得钢水；其中，粒铁和废钢的重量比为1:2～9，废钢预热温度为400～900℃；
    3)精炼
    从电炉流出的钢水依次进行VD真空脱气、LF精炼；
    4)连铸
    连铸采用双辊薄带连铸，获得厚度为1.5～2.5mm、宽度为1000～1600mm的铸带；钢水开浇温度为T+(30～80)℃，其中T为液相线温度，铸带温度1300～1450℃，结晶辊内部通水冷却，铸机浇铸速度为60～150m/min；
    5)热连轧
    铸带经夹送辊送至双机架轧机组进行热连轧，单台机架的压下率≤50％；热连轧后钢板厚度为0.4～2.0mm；
    6)卷取
    热轧后的钢板经过雾化冷却，冷却后的钢板经切头或分切处理后送至卷取机进行卷取；卷取温度为400～750℃。
  2. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，所述卷取后获得的钢卷经喷码、打捆后进行空冷或缓冷。
  3. 如权利要求2所述的超薄热轧宽带钢的制造方法，其特征是，所述空冷或缓冷后的钢卷进行切边、平整制得黑皮卷；或酸洗、镀锌制得热轧热镀锌卷；或酸洗、平整制得热轧酸洗卷；或切边、平整、射流除鳞，制得薄规格热轧卷。
  4. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，所述铁精粉为磁铁矿粉、赤铁矿粉、褐铁矿粉或菱铁矿粉中的一种或多种。
  5. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，所述煤粉为非焦煤粉、普通煤粉、石油焦中的一种或多种。
  6. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，所述废钢为轻薄料、统废、重废中的一种或多种。
  7. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，步骤2)中，所述粒铁和废钢输送至电炉内的输送方式为连续输送或间歇式输送。
  8. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，步骤5)所述热连轧后钢板厚度为0.4～0.6mm。
  9. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，步骤6)所述卷取采用卡罗塞尔卷取。
  10. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，步骤5)中，在结晶辊出带口设保护罩，且在保护罩内通惰性气体，以降低铸带受高温氧化的影响。
  11. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，步骤5)中，总压下率≥50％。
  12. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，步骤5)中，总压下率≥80％。
  13. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，步骤2)中，粒铁和废钢的重量比为1:3～9。
  14. 如权利要求1所述的超薄热轧宽带钢的制造方法，其特征是，步骤2)中，粒铁和废钢的重量比为1:4～9。
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