CN112024865B - Stopper rod, tundish and method for removing inclusions in liquid metal - Google Patents

Stopper rod, tundish and method for removing inclusions in liquid metal Download PDF

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CN112024865B
CN112024865B CN202011206337.XA CN202011206337A CN112024865B CN 112024865 B CN112024865 B CN 112024865B CN 202011206337 A CN202011206337 A CN 202011206337A CN 112024865 B CN112024865 B CN 112024865B
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stopper rod
reaction layer
inclusion
inclusion reaction
stopper
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CN112024865A (en
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刘威
杨树峰
徐志强
李京社
赵梦静
杨曙磊
赵朋
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University of Science and Technology Beijing USTB
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University of Science and Technology Beijing USTB
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/14—Closures
    • B22D41/16—Closures stopper-rod type, i.e. a stopper-rod being positioned downwardly through the vessel and the metal therein, for selective registry with the pouring opening
    • B22D41/18—Stopper-rods therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • 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

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  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention provides a stopper rod, a tundish and a method for removing inclusions in liquid metal, and relates to the field of metallurgy. The stopper rod comprises a stopper rod body; and an inclusion reaction layer is arranged on the surface of the stopper rod body. The tundish comprises the stopper rod. A method of removing inclusions from liquid metal by treating the liquid metal with the stopper rod or the tundish. The application provides a stopper rod, through setting up inclusion reaction layer, make full use of metal liquid natural flow time with the chance of stopper rod contact, can improve the clearance of high melting point inclusion.

Description

Stopper rod, tundish and method for removing inclusions in liquid metal
Technical Field
The invention relates to the field of metallurgy, in particular to a stopper rod, a tundish and a method for removing inclusions in liquid metal.
Background
The removal of the inclusion is a key limiting link in the current clean steel smelting production. After a series of processes aiming at removing inclusions in molten steel, such as bottom blowing argon, electromagnetic stirring, tundish flow control devices, refining slag optimization, and the like, are applied, the inclusion removal has reached the limit. However, in the continuous casting process, the nozzle is still disturbed by the nodulation of the nozzle caused by the inclusion with high melting point in the molten steel. The removal of the inclusions is not thorough, and the existing inclusion removal process and means cannot meet the increasingly severe requirement on cleanliness of new steel grades, and further innovation and development are needed.
In view of this, the present application is specifically made.
Disclosure of Invention
The object of the present invention is to provide a stopper rod, a tundish and a method for removing inclusions in liquid metal, which solve the above problems.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a stopper rod comprises a stopper rod body; an inclusion reaction layer is arranged on the surface of the stopper rod body;
preferably, the thickness of the inclusion reaction layer is 5 to 50 mm.
Alternatively, the thickness of the inclusion reaction layer may be any value between 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, and 5-50 mm.
Preferably, the inclusion reaction layer comprises, in mass percent:
Al2O3 70％-90%、MgO 5-10％、SiO21% -5%, SiC 3-5% and C1% -10%;
preferably, the apparent porosity of the inclusion reaction layer is 15-20%, the compressive strength is 30-40MPa, the breaking strength is 10-20MPa, and the thermal shock frequency is 5-15 times.
Aiming at alumina inclusions, the chemical components are most suitable according to the principle that the alumina has low interfacial energy and mutual affinity in molten steel.
The rough surface is advantageous for increasing the adhesion area, so that the stopper rod surface layer material should satisfy the above physical property conditions.
Optionally, the inclusion reaction layer is calculated by mass percent, Al2O3Can be any value between 70%, 75%, 80%, 85%, 90% and 70% -90%, the content of MgO can be any value between 5%, 6%, 7, 8%, 9%, 10% and 5-10%, SiO2The content of (C) may be any value between 1%, 2%, 3%, 4%, 5% and 1% -5%, the content of SiC may be any value between 3%, 4%, 5% and 3-5%, and the content of C may be any value between 1%, 2%, 3%, 4%, 5%, 6%, 7, 8%, 9%, 10% and 1% -10%. The inclusion reaction layer may have an apparent porosity of 15%, 16%, 17%, 18%, 19%, 20% or 15% to 20%, and a compressive strength of 30MPa, 31MPa, 32MPa, 33MPa, 34MPa, 35MPa, 36MPa, 37MPa, 38MPa, 39MPa or 40MPa or moreAnd any value between 30 and 40MPa, the breaking strength can be any value between 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, 15MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa and 10 to 20MPa, and the thermal shock frequency can be any value between 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times, 15 times and 5 to 15 times.
Preferably, the inclusion reaction layer comprises, in mass percent:
Al2O3 30％-40%、MgO 40-50％、SiO21% -5%, SiC 3-5% and C1% -10%;
preferably, in the inclusion reaction layer, Al2O3The mass ratio of MgO to MgO is less than or equal to 0.9;
preferably, the apparent porosity of the inclusion reaction layer is 5-15%, the compressive strength is 30-40MPa, the breaking strength is 10-20MPa, and the thermal shock frequency is 5-15 times.
For calcium aluminate inclusions (calcium treated aluminum killed steel), the reaction with the stopper rod to produce low melting point substances should be avoided, and the inclusion reaction layer is preferably made of the above components.
Optionally, the inclusion reaction layer is calculated by mass percent, Al2O3Can be any value between 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% and 30% -40%; the content of MgO may be any value between 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50% and 40-50%; SiO 22Can be any value between 1%, 2%, 3%, 4%, 5% and 1% -5%; the content of SiC may be any value between 3%, 4%, 5% and 3-5%; the content of C may be any value between 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% and 1% -10%. The inclusion reaction layer may have an apparent porosity of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or 5% to 15%, and a compressive strength of 30MPa, 31MPa, 32MPa, 33MPa, 34MPa, 35MPa, 36MPa, 37MPa, 38MPa, 39MPa, 40MPa or 3MPaThe breaking strength can be any value between 0 and 40MPa, the breaking strength can be any value between 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, 15MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa and 10 to 20MPa, and the thermal shock frequency can be any value between 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times, 15 times and 5 to 15 times.
Preferably, the inclusion reaction layer comprises, in mass percent:
Al2O3 80％-90%、MgO 1-5％、SiO21% -5%, SiC 3-5% and C1% -10%;
preferably, the apparent porosity of the inclusion reaction layer is 15-20%, the compressive strength is 30-40MPa, the breaking strength is 10-20MPa, and the thermal shock frequency is 5-15 times.
Aiming at magnesium aluminate spinel and magnesia inclusions (molten magnesium-containing steel, magnesium-treated aluminum deoxidized steel and the like), the principle of easy reaction is adopted, the surface layer of the stopper rod is mainly made of alumina, and the inclusion reaction layer is preferably made of the components.
The rough surface is advantageous for increasing the adhesion area, so that the stopper rod surface layer material should satisfy the above physical property conditions.
Optionally, the inclusion reaction layer is calculated by mass percent, Al2O3May be present in an amount of any one of 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, and between 80% and 90%; the content of MgO can be any value between 1%, 2%, 3%, 4%, 5% and 1-5%; SiO 22Can be 1%, 2%, 3%, 4%, 5% and any value between 1% and 5%; the content of SiC may be any value between 3%, 4%, 5% and 3-5%; the content of C may be any value between 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% and 1% -10%. The inclusion reaction layer may have an apparent porosity of 15%, 16%, 17%, 18%, 19%, 20% or 15% to 20%, a compressive strength of 30MPa, 31MPa, 32MPa, 33MPa, 34MPa, 35MPa, 36MPa, 37MPa, 38MPa, 39MPa, 40MPa or 30 to 40MPa, and a flexural strength of 10MPa, 1MPa or 30MPa1MPa, 12MPa, 13MPa, 14MPa, 15MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa and any value between 10 and 20MPa, and the number of thermal shock times can be any value between 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times, 15 times and 5 to 15 times.
Preferably, the inclusion reaction layer comprises, in mass percent:
Al2O3 5％-10%、MgO 75-85％、SiO21% -5%, SiC 1% -5% and C1% -10%;
preferably, the apparent porosity of the inclusion reaction layer is 15-20%, the compressive strength is 30-40MPa, the breaking strength is 10-20MPa, and the thermal shock frequency is 5-15 times.
The inclusion reaction layer is made of a material which is the same as or easy to react with the inclusion to be removed, and the inclusion removal rate is improved. Therefore, the above inclusion reaction layer can be selected for the alumina-based inclusions.
Optionally, the inclusion reaction layer is calculated by mass percent, Al2O3Can be any value between 5%, 6%, 7%, 8%, 9%, 10% and 5% -10%; the content of MgO may be any value between 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85% and 75-85%; SiO 22Can be any value between 1%, 2%, 3%, 4%, 5% and 1% -5%; the content of SiC may be any value between 1%, 2%, 3%, 4%, 5% and 1-5%; the content of C may be any value between 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% and 1% -10%. The apparent porosity of the inclusion reaction layer can be any value between 15%, 16%, 17%, 18%, 19%, 20% and 15% -20%, the compressive strength can be any value between 30MPa, 31MPa, 32MPa, 33MPa, 34MPa, 35MPa, 36MPa, 37MPa, 38MPa, 39MPa, 40MPa and 30-40MPa, the breaking strength can be any value between 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, 15MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa and 10-20MPa, the number of thermal shock times can be any value between 5 times, 6 times, 7 times, 8 times and 9 times, and the number of thermal shock times can be any value between 5 times, 6 times, 7 times, 8 times and 9 times10, 11, 12, 13, 14, 15 and between 5 and 15.
Preferably, the stopper rod further comprises a stopper rod core for providing a cold source, the stopper rod core being arranged within the stopper rod body.
The surface temperature of the stopper rod is above the liquidus line of the molten steel and below the precipitation temperature of the high melting point inclusions, so that the inclusion removal rate is higher.
Preferably, the stopper rod body is in a hollow column shape, one end of the stopper rod body is provided with an opening for loading or taking out the core part of the stopper rod, and the other end opposite to the opening is provided with a stopper rod head;
preferably, the material of the stopper rod body comprises graphite;
preferably, the stopper rod head comprises a corundum and/or aluminium carbon refractory material.
The stopper rod head is made of a material which is not easy to react with the inclusions, so that the shape and the performance of the stopper rod head are stable, and the stopper rod can exert corresponding effects by matching with a tundish nozzle inlet.
Preferably, the stopper rod core comprises a cooling pipe for circulating a cooling medium and a heat transfer medium filled between the cooling pipe and the stopper rod body;
preferably, the cooling medium comprises water or gas, and the heat-conducting medium comprises graphite and/or gas.
The stopper rod can be divided into a water cooling type and a gas cooling type according to requirements; the water-cooling type stopper rod adopts cooling water as a cooling medium, and graphite powder is filled in a cavity between the cooling pipe and the stopper rod body as a heat-conducting medium so as to ensure the cooling effect; the air-cooled stopper rod needs to ensure that a larger cavity is arranged in the stopper rod body, and a gas circuit with reasonable design can increase the contact area and time of gas and the inner wall and improve the cooling efficiency.
Preferably, the stopper rod body is provided with a connecting part for fixing the stopper rod;
preferably, the connecting portion is provided with a thread or a groove cooperating with the clamping mechanism.
It should be noted that the cooling pipe can be wound around the periphery of the connecting part to cool the connecting part, so that the thermal deformation of the connecting structure is reduced to enhance the use stability.
A tundish comprises the stopper rod.
A method of removing inclusions from a liquid metal by treating the liquid metal with the stopper rod or the tundish;
preferably, the liquid metal is molten steel, and the surface of the stopper rod is at a temperature between the liquidus line of the molten steel and the precipitation temperature of inclusions.
Compared with the prior art, the invention has the beneficial effects that:
according to the stopper rod and the tundish, the inclusion reaction layer is arranged on the surface of the stopper rod body, so that the chance of contact with the stopper rod when molten steel naturally flows can be fully utilized, and the removal rate of high-melting-point inclusions is improved;
according to the method for removing the inclusions in the liquid metal, the liquid metal is treated through the stopper rod or the tundish, and the inclusions in the liquid metal are removed through the inclusion reaction layer arranged on the surface of the stopper rod body.
Drawings
To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope of the present invention.
FIG. 1 is a schematic view of the structure of a stopper rod provided in example 1;
FIG. 2 is a schematic view of a water-cooled stopper rod provided in examples 2 and 3;
fig. 3 is a schematic view of an air-cooled stopper rod provided in example 4.
Reference numerals:
1-a stopper body; 2-inclusion reaction layer; 3-a stopper rod core; 4-opening; 5-stopper rod head; 6-a cooling pipe; 7-a connecting part; 8-stopper rod slag line.
Detailed Description
The terms as used herein:
"prepared from … …" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.
The conjunction "consisting of … …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of … …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.
When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when the range "1 ~ 5" is disclosed, the ranges described should be construed to include the ranges "1 ~ 4", "1 ~ 3", "1 ~ 2 and 4 ~ 5", "1 ~ 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.
In these examples, the parts and percentages are by mass unless otherwise indicated.
"part by mass" means a basic unit of measure indicating a mass ratio of a plurality of components, and 1 part may represent any unit mass, for example, 1g or 2.689 g. If we say that the part by mass of the component A is a part by mass and the part by mass of the component B is B part by mass, the ratio of the part by mass of the component A to the part by mass of the component B is a: b. alternatively, the mass of the A component is aK and the mass of the B component is bK (K is an arbitrary number, and represents a multiple factor). It is unmistakable that, unlike the parts by mass, the sum of the parts by mass of all the components is not limited to 100 parts.
"and/or" is used to indicate that one or both of the illustrated conditions may occur, e.g., a and/or B includes (a and B) and (a or B).
Embodiments of the present invention will be described in detail below with reference to specific examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The design principle is first explained as follows:
the inclusion in the molten steel is removed mainly by floating to the top and being absorbed by the liquid slag. However, due to the limitations of smelting time, flowing conditions and the like, a part of inclusions cannot float upwards in time to be removed, and a part of small-size inclusions are difficult to float upwards due to the drag force of molten steel and are dispersed in the molten steel. Molten steel can all pass through stopper stick, immersion nozzle before flowing out in the middle of the continuous casting, and when the contact stopper stick, the high melting point inclusion in the molten steel, like alumina inclusion, under suitable temperature condition, the aluminium oxide of dissolved state can react with stopper stick surface spontaneous, takes place the crystallization of inclusion and adheres to and the combination of refractory material, and the reaction formula is as follows:
Figure 892250DEST_PATH_IMAGE001
in the formula: [ Al ]]And [ O]Is aluminum and oxygen in molten steel in dissolved state, Al2O3(s) precipitated alumina, MgO(s) solid magnesia refractory, MgAl2O4 (s) is the precipitated magnesium aluminate spinel, and suspended solid-phase alumina inclusion exists in the molten steelThe molten steel adheres to the surface of the stopper rod when being brought into contact with the stopper rod with a relatively low temperature.
The precipitation modes of the dissolved aluminum, magnesium and other elements in the molten steel mainly comprise homogeneous nucleation and heterogeneous nucleation, wherein the homogeneous nucleation has larger interface energy to overcome, and is generally more difficult than the heterogeneous nucleation unless the conditions are very suitable. Heterogeneous nucleation requires a suitable heterogeneous interface, which is one of the conditions provided by the stopper. The melting point of the precipitated inclusion in the molten steel is higher than the temperature of the molten steel, but the inclusion is difficult to grow and float upwards to remove due to the limitation of conditions such as growth kinetics and the like, and is distributed in the molten steel in a dispersed manner, and if the inclusion is suspended in a proper heterogeneous interface and meets the conditions required by reaction, the suspended inclusion tends to nucleate and grow in the heterogeneous interface. Besides meeting the conditions of nucleation and growth, the heterogeneous interface provided by the stopper rod has low interfacial tension and mutual affinity with the inclusions, so that the inclusions are more easily adhered and grow on the surface of the stopper rod. According to the definition of surface/interface tension and the influence factors thereof, the aluminum oxide inclusion has affinity with the similar substances and affinity with the magnesium aluminate spinel, which is one of the bases for selecting the material of the inclusion reaction layer on the surface of the stopper rod.
Based on the conditions which should be met by the reaction formula, the surface refractory material component of the stopper rod is controlled, namely, the stopper rod designed by the application realizes a proper heterogeneous (homogeneous) phase interface, thereby being beneficial to the precipitation and growth of inclusions. The reaction that takes place has two benefits: firstly, impurities are adsorbed through reaction, and because molten steel can be fully contacted with a stopper rod, the impurities in the molten steel can be fully purified; secondly, form new surface layer material through reaction product on stopper rod surface, for traditional "consumable" type stopper rod, the stopper rod that this application provided is "hyperplasia of oneself" formula, can increase substantially stopper rod life.
In addition, set up the stopper rod core portion that is used for cooling in stopper rod body is inside, can provide relatively lower temperature, also is favorable to the inclusion to precipitate on the one hand, grows up, and on the other hand also can improve the life of stopper rod.
Example 1
As shown in FIG. 1, a stopper rod, which is generally cylindrical, includes a stopper rod body 1 and an inclusion reaction layer 2 provided on the surface of the stopper rod body 1.
The inclusion reaction layer 2 comprises the following components in percentage by mass: al (Al)2O3 75%、MgO 6％、SiO 25%, SiC 4% and C10%; the physicochemical properties of the inclusion reaction layer are as follows: apparent porosity of 15%, compressive strength of 30MPa, breaking strength of 15MPa, thermal shock frequency of 10 times, and density of 2500kg/m3。
The production of aluminium deoxidized molten steel, because of the limited refining time, the alumina in the molten steel is included with impurities (Al)2O3) Cannot completely float and remove. Aiming at alumina inclusions which cannot be completely removed, the stopper rod is adopted for an 8-machine 8-flow tundish in a continuous casting link. Because 8 flow tundish need 8 stopper rods with large contact area, the cooling mode selects an air cooling mode, the main material of the stopper rod surface material selects the same kind of substances with the inclusion, namely the compatible interface inclusion is formed and is easy to adhere. The alumina inclusions can cluster and grow in a crystallization mode on the surface of the stopper rod, and the effects of further removing the alumina inclusions and prolonging the service life of the stopper rod can be achieved. And because the molten steel is purified before entering the water gap of the crystallizer, the probability of water gap nodulation is reduced. Through sampling statistics, the number of inclusions in the final casting blank is reduced by about 20% and the total oxygen in the steel is reduced by about 2ppm relative to the large ladle molten steel. Meanwhile, the service life of the stopper rod is greatly prolonged, the theoretical service life can meet the requirement that the continuous casting heat is more than 20 furnaces, and the probability of casting stop accidents caused by the replacement of the stopper rod is reduced.
Example 2
As shown in FIG. 2, a stopper rod comprises a stopper rod body 1, an inclusion reaction layer 2 provided on the surface of the stopper rod body 1, and a stopper rod core 3 provided in the stopper rod body 1. The stopper rod body 1 is in a hollow cylindrical shape, one end of the stopper rod body is provided with an opening 4 for loading or taking out the stopper rod core part 3, and the other end, opposite to the opening 4, of the stopper rod body is provided with a stopper rod head 5; the material of the stopper rod body 1 is graphite; the stopper rod head 5 is made of corundum. The stopper rod core 3 comprises a cooling pipe 6 (water cooling preferably uses a cooling coil) for circulating a cooling medium and a heat-conducting medium filled between the cooling pipe 6 and the stopper rod body 1; the cooling medium is water, and the heat-conducting medium is graphite powder.
The inclusion reaction layer 2 comprises the following components in percentage by mass: al (Al)2O3 10%、MgO 80％、SiO22%, SiC 2% and C6%; the physicochemical properties of the inclusion reaction layer are as follows: the apparent porosity is 12 percent, the compressive strength is 30MPa, the breaking strength is 20MPa, the thermal shock frequency is 15 times, and the density is 3000kg/m3。
The stopper body 1 is provided with a connecting portion 7 for fixing the stopper, and the connecting portion 7 is provided with a screw thread (not shown in the drawings). In other embodiments, the connecting portion 7 may be provided with a recess for cooperation with the clamping mechanism. The boundary of the connecting part 7 and the stopper rod body 1 forms a stopper rod slag line 8.
The stopper provided by the application is arranged in a tundish and is used during casting. The production of aluminium deoxidized molten steel, because of the limited refining time, the alumina in the molten steel is included with impurities (Al)2O3) Cannot completely float and remove. Aiming at alumina inclusions which cannot be completely removed, the water cooling stopper rod is adopted according to a heterogeneous reaction principle, so that the inclusions in molten steel can react to generate high-melting-point spinel to be attached to the surface of the stopper rod. The proper water flow strength is controlled to maintain the surface temperature of the stopper rod to be slightly lower than the molten steel temperature (generally 1-5 ℃), alumina inclusions can generate magnesia-alumina spinel generation reaction on the surface of the stopper rod, the magnesia-alumina spinel is also a high-melting-point substance, can be attached to the surface of the stopper rod nearby after being generated, and can realize the effects of improving the removal rate of the alumina inclusions and prolonging the service life of the stopper rod.
Example 3
The stopper used in this example was the same in structure as the stopper provided in example 2. The difference lies in that the inclusion reaction layer 2 comprises the following components in percentage by mass: al (Al)2O3 40%、MgO 50％、SiO22%, SiC 3% and C5%; the physicochemical properties of the inclusion reaction layer are as follows: the apparent porosity is 8 percent, the compressive strength is 30MPa, the breaking strength is 20MPa, the thermal shock frequency is 15 times, and the density is 2650kg/m3。
The calcium treatment is carried out due to the limited refining time in the production of the calcium-treated aluminum deoxidized molten steelHigh melting point calcium aluminate inclusion (CaO. Al) in post-molten steel2O3) Cannot completely float and remove. Aiming at the calcium aluminate inclusion which cannot be completely removed, the water-cooled stopper rod is adopted, the content of alumina and magnesia in the inclusion is increased due to the reaction with the inclusion, the melting point of the inclusion is improved, and the inclusion is easy to precipitate and adhere to the surface of the stopper rod. Meanwhile, the proper water flow strength is controlled to maintain the surface temperature of the stopper rod within the range of 1570-1600 ℃ (the surface temperature of the stopper rod is between the liquid phase line of molten steel and the precipitation temperature of inclusions), most of calcium aluminate inclusions are high-melting-point substances, the surface adhesion of the stopper rod is easy to form, and the effects of further removing the calcium aluminate inclusions and prolonging the service life of the stopper rod can be realized. And the low-melting-point calcium aluminate inclusion does little harm to the performance of the steel.
Example 4
Referring to fig. 3, a stopper rod includes a stopper rod body 1, an inclusion reaction layer 2 disposed on a surface of the stopper rod body 1, and a stopper rod core 3 disposed in the stopper rod body 1. The stopper rod body 1 is in a hollow cylindrical shape, one end of the stopper rod body is provided with an opening 4 for loading or taking out the stopper rod core part 3, and the other end, opposite to the opening 4, of the stopper rod body is provided with a stopper rod head 5; the material of the stopper rod body 1 is graphite; the stopper rod head 5 is made of an aluminum-carbon refractory material. The stopper rod core part 3 comprises a cooling pipe 6 (an optional U-shaped pipe for air cooling) for circulating a cooling medium and a heat-conducting medium filled between the cooling pipe 6 and the stopper rod body 1; the cooling medium and the heat-conducting medium are both argon.
The inclusion reaction layer 2 comprises the following components in percentage by mass: al (Al)2O3 80%、MgO 5％、SiO 25%, SiC 5% and C5%; the physicochemical properties of the inclusion reaction layer are as follows: apparent porosity of 15%, compressive strength of 30MPa, breaking strength of 20MPa, thermal shock frequency of 15 times, and density of 3000kg/m3。
The production of the magnesium-treated aluminum deoxidized steel has the defect that magnesia-alumina spinel and magnesia inclusions in molten steel cannot completely float upwards and be removed after the magnesium treatment due to the limited refining time. Aiming at magnesia-alumina spinel and magnesia-alumina inclusions which cannot be completely removed, the gas-cooled stopper rod is adopted, the proper airflow strength is controlled to maintain the surface temperature of the stopper rod, substances in an inclusion reaction layer react with the inclusions to separate and attach the inclusions on the surface of the stopper rod, and the effects of further removing the magnesia-alumina spinel inclusions and prolonging the service life of the stopper rod can be achieved.
Comparative example 1
The common stopper rod is adopted to produce the aluminum deoxidized steel, and the surface of the stopper rod does not have the reaction condition for adsorbing the impurities completely. Through sampling analysis statistics of molten steel in a refined steel ladle and in a crystallizer respectively, the fact that the quantity and size distribution difference of inclusions in the molten steel using a common stopper rod in the steel ladle and the crystallizer are not large is found, due to the effect of a tundish, the inclusions have a certain probability to be removed through floating in the ladle, the quantity in the crystallizer is reduced by about 5% relative to that in the steel ladle in the total quantity, the total oxygen content of the steel is not obviously changed in a detection error range. The stopper rod of the invention can obviously reduce the number of the impurities in the crystallizer relative to the steel ladle, generally about 10-30 percent, and reduce the total oxygen content of the steel by 1-5ppm aiming at different types of impurities.
Comparative example 2
The common stopper rod is easy to react with molten steel at high temperature to cause refractory decomposition due to the fact that the common stopper rod cannot adsorb the impurities, the stopper rod is easy to damage due to the fact that the slag is dissolved relative to the surface of the stopper rod by scouring caused by steel-slag interface fluctuation near a slag line, the general service life is about 10 heats, part of high-quality stopper rods can reach 20-30 times, and a new stopper rod needs to be replaced after continuous casting. The stopper rod is self-growth type, the surface of the stopper rod is subjected to adsorption and growth reaction through proper reaction conditions to generate a high-melting-point substance attached to the surface as a new refractory material, and meanwhile, the cooling mechanism takes away high heat of the surface and the core of the stopper rod to ensure that the stopper rod is always in a stable temperature environment, so that continuous casting with the maximum of 20-30 heats can be theoretically met, and the stopper rod can be put into use again after a continuous casting machine stops casting gaps and is repaired by simple machinery, and the service life of the stopper rod is 5-10 times that of a common stopper rod.
The application provides a stopper rod sets up inclusion reaction layer on stopper rod body surface, and the clearance of high melting point inclusion can be improved to the chance that fully utilized molten steel natural flow contacted with the stopper rod when. Through set up stopper rod core portion in the stopper rod body, further improve the inclusion clearance, can improve the life of stopper rod and the stability of continuous casting process simultaneously.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims (12)

1. A stopper rod is characterized by comprising a stopper rod body; an inclusion reaction layer is arranged on the surface of the stopper rod body; the thickness of the inclusion reaction layer is 5-50 mm;
the inclusion reaction layer comprises the following components in percentage by mass:
Al2O3 70％-90%、MgO 5-10％、SiO21% -5%, 3-5% of SiC and 1% -10% of C, wherein the apparent porosity of the inclusion reaction layer is 15% -20%, the compressive strength is 30-40MPa, the breaking strength is 10-20MPa, and the thermal shock frequency is 5-15 times; alternatively, the first and second electrodes may be,
the inclusion reaction layer comprises the following components in percentage by mass:
Al2O3 30％-40%、MgO 40-50％、SiO21% -5%, SiC 3-5% and C1% -10%; in the inclusion reaction layer, Al2O3The mass ratio of MgO to MgO is less than or equal to 0.9; the apparent porosity of the inclusion reaction layer is 5-15%, the compressive strength is 30-40MPa, the breaking strength is 10-20MPa, and the thermal shock frequency is 5-15 times; alternatively, the first and second electrodes may be,
the inclusion reaction layer comprises the following components in percentage by mass:
Al2O3 80％-90%、MgO 1-5％、SiO21% -5%, SiC 3-5% and C1% -10%; the apparent porosity of the inclusion reaction layer is 15-20%, the compressive strength is 30-40MPa, the breaking strength is 10-20MPa, and the thermal shock frequency is 5-15 times; alternatively, the first and second electrodes may be,
the inclusion reaction layer comprises the following components in percentage by mass:
Al2O3 5％-10%、MgO 75-85％、SiO21% -5%, SiC 1% -5% and C1% -10%; the apparent porosity of the inclusion reaction layer is 15-20%, the compressive strength is 30-40MPa, the breaking strength is 10-20MPa, and the thermal shock frequency is 5-15 times.
2. The stopper rod of claim 1, further comprising a stopper rod core for providing a cold source, the stopper rod core being disposed within the stopper rod body.
3. Stopper rod according to claim 2, wherein the stopper rod body is in the form of a hollow cylinder provided with an opening at one end for inserting or removing the stopper rod core and a stopper rod head at the other end opposite the opening.
4. The stopper rod of claim 2, wherein the stopper rod body comprises graphite.
5. A stopper rod according to claim 3, wherein the stopper rod head comprises a corundum and/or an alumino-carbonaceous refractory material.
6. A stopper rod according to claim 2, wherein the stopper rod core comprises a cooling tube for circulating a cooling medium and a heat transfer medium filled between the cooling tube and the stopper rod body.
7. Stopper rod according to claim 6, wherein the cooling medium comprises water or a gas and the heat conducting medium comprises graphite and/or a gas.
8. Stopper rod according to any one of claims 1 to 7, wherein the stopper rod body is provided with a connection for securing the stopper rod.
9. Stopper rod according to claim 8, wherein the connecting portion is provided with a thread or a groove cooperating with a clamping means.
10. A tundish comprising a stopper rod according to any one of claims 1 to 9.
11. A method of removing inclusions from liquid metal, characterised in that the liquid metal is treated with a stopper rod according to any one of claims 1 to 9 or a tundish according to claim 10.
12. The method of claim 11, wherein the liquid metal is molten steel and the surface of the stopper rod is at a temperature between the liquidus line of the molten steel and the inclusion precipitation temperature.
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US20060249546A1 (en) * 2005-05-03 2006-11-09 Foseco International Limited Tundish stopper rod for continuous molten metal casting
CN102151811B (en) * 2011-03-09 2013-06-26 钢铁研究总院 Method for capturing continuous casting inclusion and novel submersed nozzle
CN103008636B (en) * 2013-01-21 2015-01-07 河北联合大学 Gun insertion type stopper rod device and method using same for absorbing inclusions at gate
CN104475695B (en) * 2014-12-30 2016-06-08 武汉科技大学 Molten steel inclusion trap setting for continuous casting production exit
CN104726638A (en) * 2015-03-12 2015-06-24 东北大学 Method for removing impurities from liquid steel in steel ladle
CN105753489B (en) * 2016-01-21 2019-02-05 宝山钢铁股份有限公司 A kind of integrated stopper rod used for continuous casting and its manufacturing method
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CN111112594B (en) * 2020-02-26 2021-09-10 江苏省沙钢钢铁研究院有限公司 Stopper rod for pouring low-carbon low-alloy steel and steelmaking process using stopper rod

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