CN114703373A - Process method for improving quality of molten steel by gradually regulating and controlling electroslag remelting high-temperature slag system - Google Patents
Process method for improving quality of molten steel by gradually regulating and controlling electroslag remelting high-temperature slag system Download PDFInfo
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- 229910052751 metal Inorganic materials 0.000 claims description 25
- 239000002184 metal Substances 0.000 claims description 25
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- 238000002844 melting Methods 0.000 claims description 12
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- 239000012467 final product Substances 0.000 claims 1
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- 229910052593 corundum Inorganic materials 0.000 description 9
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/16—Remelting metals
- C22B9/18—Electroslag remelting
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/005—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using exothermic reaction compositions
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
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- Mechanical Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Analytical Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention discloses a process method for gradually regulating and controlling an electroslag remelting high-temperature slag system to improve the quality of molten steel, which comprises the steps of uniformly scattering a special slag system gradual regulating and controlling agent into a slag pool gradually after and during a period of time after the start of electroslag remelting, calculating the electroslag remelting time, gradually regulating the addition amount to achieve the aim of stabilizing the physical and chemical properties of the high-temperature slag system and improving the quality of the molten steel, wherein the slag system gradual regulating and controlling agent can gradually and slowly release slag system regulating and controlling substances along with the electroslag process to supplement the substance consumption of the high-temperature slag system. The density change of the regulating agent in the internal melting process of the slag pool is further limited, the regulating agent is ensured to be suspended at the bottom of the slag pool, and meanwhile, the regulating agent can be ensured to sink rapidly and slowly float to the upper surface layer of the slag pool along with the reaction, but does not contact and react with air, so that the loss caused by the reaction between aluminum particles, silicon powder and the like in the regulating agent and oxygen in the air is effectively avoided, and the performance of the regulating agent is ensured.
Description
Technical Field
The invention relates to the technical field of special metallurgy, in particular to a process method for improving the quality of molten steel by gradually regulating and controlling an electroslag remelting high-temperature slag system.
Background
Electroslag remelting is a common method for smelting high-temperature alloys. The slag system plays an important role in the electroslag remelting process. The composition of the electroslag remelting slag system is directly related to the smelting quality of the high-temperature alloy and the surface quality of the cast ingot. The better high-temperature alloy electroslag remelting slag system has a lower melting point which is 100-150 ℃ lower than the alloy melting point; the viscosity is low so as to obtain good fluidity; the catalyst has higher alkalinity so as to be beneficial to desulfurization; the electric slag remelting device has proper conductivity and higher resistivity so as to ensure the temperature of the electroslag remelting process and the heat required by remelting; the material has lower mass fractions of unstable oxides and variable oxides so as to prevent the excessive burning loss of easily-oxidized elements such as aluminum, titanium and the like; has smaller high-temperature permeability so as to prevent the metal melting pool from sucking air to generate gaseous inclusions and influence the purity of molten steel.
The common slag system for high-temperature alloy electroslag remelting is basically based on CaF2, proper A12O3, CaO, MgO and other oxides are added, and different components in the slag system have different functions, wherein CaF2 can reduce the melting point, viscosity and surface tension of slag, but CaF2 has higher conductivity and is easy to cause environmental pollution; CaO can increase the alkalinity of slag, improve the desulfurization efficiency and reduce the conductivity of the slag, but CaO has strong water absorption and is easy to bring hydrogen and oxygen into the alloy; the A12O3 can obviously reduce the conductivity of the slag, reduce the power consumption and improve the productivity, but the A12O3 can increase the melting point and the viscosity of the slag and reduce the desulfurization effect of the slag; MgO can prevent oxygen absorption in a slag pool and oxygen transmission of the valence oxides in the slag to a metal molten pool, but MgO easily improves the viscosity of the slag;
based on the basic requirements and composition characteristics of the high-temperature alloy electroslag remelting slag system, production practices and researches find that along with the continuous process of the electroslag remelting process, particularly when large-size and high-quality electrode rods are remelted, due to the fact that the duration is long, the high-temperature slag system and certain elements in the electrode rods are subjected to complex chemical reactions, and the slag system composition substances are fundamentally changed, so that the physicochemical properties of the slag system are also influenced, such as the melting point, viscosity, density, conductivity, desulfurized phosphorus performance and the like of the slag. The quality of the high-temperature molten steel is directly influenced by the change of the physical and chemical properties of the high-temperature slag system, for example, the internal quality of the molten steel is poorer than that of a normal steel ingot due to the factors of insufficient feeding, dropping liquid slag entrapment, short floating time of inclusions and the like, for example, the center is loose, the center is shrunk, the content of the inclusions and the content of gas are higher, and therefore, the quality of steel ingot products is ensured by ensuring the stability of the physical and chemical properties of the high-temperature slag system in the actual production.
In order to solve the defect and the quality problem, at present, steel enterprises and scientific researchers at home and abroad also make some attempts to improve the problems, but mainly focus on changing the structure of a high-temperature slag system, compressing electroslag remelting time and the like. The technical measures play a certain positive role in improving the quality of common steel ingots, but cannot be generally applied to the production of electrode rods with all sizes and varieties, particularly for the production of steel ingots for large specification, aerospace and maritime engineering, because the section is large, the remelting time is long, the requirement on the quality of molten steel is high, the improvement technical measures have a limited positive effect on improving the production of the steel type, and a process method for gradually regulating and controlling the quality of the molten steel by an electroslag remelting high-temperature slag system is provided to solve the problems.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to solve the problems that the physicochemical property of a high-temperature slag system is changed along with the easy and unstable structure of the high-temperature slag system in the prior electroslag remelting technology, and the quality stability of a steel ingot is further influenced, and provides a process method for gradually regulating and controlling the electroslag remelting high-temperature slag system to improve the quality of molten steel. The invention uniformly sprinkles a special slag system gradual regulating agent into a slag pool after and in the process of electroslag remelting for a period of time, calculates the electroslag remelting time, and gradually adjusts the addition amount to achieve the aims of stabilizing the physicochemical property of a high-temperature slag system and improving the quality of molten steel. The slag system gradual change regulator can gradually and slowly release slag system regulating substances along with the electroslag process so as to supplement the substance consumption of a high-temperature slag system, and is uniformly distributed and stably suspended in the middle of the high-temperature slag system under the condition of no harmful substances or side effects, and the slow-release oxygen absorption substance forms a passivation film layer to isolate gas elements in air from transferring into molten steel, so that the aims of improving the purity of the molten steel and improving the quality of a molten steel solidification structure are fulfilled.
The technical purpose of the invention is realized by the following technical scheme:
a process method for improving the quality of molten steel by gradually regulating and controlling an electroslag remelting high-temperature slag system comprises the following steps: uniformly scattering a special slag system gradual change regulating agent into the slag pool step by step after and in the process of electroslag remelting for a period of time, calculating the electroslag remelting time, and gradually adjusting the addition amount to achieve the aims of stabilizing the physicochemical property of the high-temperature slag system and improving the quality of molten steel; the slag system gradual change regulator comprises calcium core particles (metal calcium is arranged inside and iron sheet wrapping is arranged outside), MgO, TiO2, aluminum particles, iron particles, silicon powder and a binder, and is formed by pressing after the proportion of each component is calculated by a model. The slag system gradual change regulating agent is added into the slag pool, then suspended at the lower part of the slag pool, and gradually floats upwards to be melted, but is not contacted with molten steel at the lower part and air at the upper part.
As a further improvement of the invention, the density gradient range of the slag system gradient regulator is 3.6-4.2 g-cm3The initial value of the density of the finished product is set to be 4.2 g.cm3The density is gradually reduced to 3.6 g-cm along with the progress of electroslag remelting reaction3。
As a further improvement of the invention, the alkalinity of the regulator is controlled to be 10-12, and the calcium-aluminum ratio is controlled to be 1.8-2.0.
As a further improvement of the invention, the components of the regulating agent are that the weight percentage of calcium core particles (the interior is metallic calcium, and the exterior is wrapped by iron sheet) is 35-40%; the weight percentage of MgO is 5-10%; the weight percentage of TiO2 is 2-5%; the weight percentage of the aluminum particles is 25-30%; the weight percentage of the iron particles is 5-8%; the weight percentage of the silicon powder is 5 percent.
As a further improvement of the invention, the regulating agent is in the shape of a cylinder, the volume of the regulating agent is controlled to be 13.63-14.15cm3, and the regulating agent is added into the slag pool until the total melting time is not more than 1 min.
As a further improvement of the invention, the model of the addition amount of the regulating agent is as follows:
wherein m is the specific addition of the regulating agent, kg, in the remelting end time of a single electrode rod;
lambda is the empirical value of the remelting coefficient of the steel type, 1.0-1.2 is taken as the high-carbon steel, and 0.5-0.8 is taken as the medium-low carbon steel;
i is electroslag remelting current intensity, A;
r is the resistivity of the high-temperature slag, omega.m;
s is the electrode rod surface area, cm 2;
l is the length of the electrode bar, m;
v is the remelting rate of the electrode bar, cm/min;
and t is the electrode bar remelting time min.
As a further improvement of the invention, the sequence of adding the regulating agent into the slag bath is as follows: the additive is added from the center of the slag pool close to the electrode rod, and then is uniformly scattered to the periphery to be fully paved on the surface of the whole slag pool.
As a further improvement of the invention, the adding time of each time is controlled not to exceed 2min, and the adding interval time is not less than 5 min.
In conclusion, the invention has the following beneficial effects:
the invention relates to a process method for gradually regulating and controlling electroslag remelting high-temperature slag system to improve molten steel quality, which is characterized in that a slag system gradual regulating and controlling agent is uniformly added into a slag pool to supplement the material consumption of the high-temperature slag system, the regulating and controlling agent is suspended at the lower part of the slag pool and gradually floats upwards for melting, but is not contacted with lower molten steel and upper air, sulfur is transferred from an electrode rod into the slag pool under the action of high temperature, the part of desulfurization reaction at the stage mainly comprises an electrode melting tail end, a metal molten drop passes through a slag layer to enter a molten pool, and a metal molten pool and a slag pool interface, and the reaction formula is that
[S]+(CaO)＝(CaS)+[O] (1)
Because CaO in the high-temperature slag system reacts with the S element in the electrode bar, thereby achieving the aim of removing impurities by desulfurization, but also bringing about the reduction of CaO content in the slag system and gradually consuming the CaO, along with the continuous proceeding of the reaction, the CaO content in the slag bath continuously reduces, the alkalinity of the slag system continuously reduces, after the sulfur capacity in the slag reaches a certain level, the restrictive link of electroslag remelting desulfurization is no longer the migration of sulfur on the interface of slag and gold, the desulfurization effect of the slag system obviously reduces, the gradual change regulating agent added into the slag bath carries out continuous supplement on CaO in the slag system at the moment, thereby realizing the continuous desulfurization of the slag system, and improving the purity of the molten steel.
Secondly, in the electroslag remelting process, the phenomenon of uneven aluminum and titanium components along the height direction of the ingot body often occurs. This non-uniformity occurs as a result of the interaction of the aluminum and titanium with the oxides in the slag. Reaction formula is
4[Al]+3(TiO2)＝2(Al2O3)+3[Ti] (2)
In general, the reaction proceeds to the right. However, in the initial stage of electroslag remelting, the mass fraction of TiO2 in the slag is low, while the mass fraction of Al2O3 is high, and the reaction formula is performed leftward to some extent, namely, titanium at the bottom of the ingot is oxidized by Al2O3 in the slag, and (Al3+) in Al2O3 is reduced into Al which enters the alloy. After the TiO2 in the slag reaches the equilibrium concentration, the reaction is in dynamic equilibrium, so the TiO2 in the slag system can be supplemented by adding the gradual change regulating agent, and the problem of uneven aluminum and titanium of the cast ingot is solved.
③ because TiO2 is a variable oxide, oxygen can be supplied to the metal melting bath, thereby leading to the burning loss of titanium element in the alloy. The reaction formula is
1/2[Ti]+5/2(TiO2)＝(Ti3O5) (3)
(Ti3O5)+1/2(O2)＝3(TiO2) (4)
4[Al]+3(O2)＝2(Al2O3) (5)
The method is characterized in that a gradual change regulating agent is added to supplement aluminum to a high-temperature slag system, TiO2 in the slag is reduced, the burning loss of titanium elements is reduced, meanwhile, aluminum particles can react with O2 in the atmosphere, reaction (5) is carried out to inhibit reaction (4), A12O3 generated in the reaction (5) forms a passivation film to cover the upper surface of a slag pool, oxygen in the air is further prevented from entering, and in addition, the problem of the burning loss of aluminum in the electroslag remelting process of certain high-aluminum low-titanium type high-temperature alloys can be solved by a compensation method of adding the aluminum particles in the remelting process.
And fourthly, because the reaction formula (5) is an exothermic reaction, and aluminum particles in the gradual change regulating agent can also perform an exothermic reaction with FeO in the components of the metal pool, sufficient heat is provided for each area of the whole electroslag remelting pool, the solidification rate of metal liquid drops is reduced, and meanwhile, metallic iron generated by the exothermic reaction enters the metal pool, so that feeding is performed on the steel ingot, the internal solidification structure is improved, the structure crystal grains are refined, the compactness of the steel ingot is improved, the quality defects of looseness, shrinkage cavities, cleanliness, gas content and the like of the steel ingot at the bottom are improved, and the yield of the metal pool is improved.
The process method for improving the quality of molten steel by gradually regulating and controlling the electroslag remelting high-temperature slag system has the advantages that the density change of the regulating and controlling agent in the melting process in the slag pool is further limited, the regulating and controlling agent is enabled to suspend at the bottom of the slag pool, meanwhile, the regulating and controlling agent is enabled to sink rapidly, the regulating and controlling agent can slowly float to the upper surface layer of the slag pool along with the reaction, but does not contact with air for reaction, so that the loss caused by the reaction of aluminum particles, silicon powder and the like in the regulating and controlling agent with oxygen in the air is effectively avoided, and the performance of the regulating and controlling agent is ensured; in addition, the regulating agent has the advantages of high compactness, low possibility of being broken and the like, and is favorable for storage of the regulating agent.
According to the process method for gradually regulating and controlling the quality of the molten steel by the electroslag remelting high-temperature slag system, as the molten steel in the metal pool is cooled and solidified from the periphery to the center, the regulating and controlling agent is firstly added to the center of the electrode rod of the metal pool in the adding process, acts on the center of the metal pool, then is uniformly dispersed to the periphery, and gradually covers the whole metal pool, so that the regulating and controlling agent can provide uniform heat for the whole electroslag remelting process, and the condition that the solidification in a local area is caused to reduce the quality of a solidification structure of the whole steel ingot is effectively avoided.
Drawings
FIG. 1 is a schematic structural diagram of states of three different slag system regulators in an electroslag remelting slag bath;
FIG. 2 is a diagram of a gradual change slag system regulating agent;
FIG. 3 is a macrostructure of an electroslag remelting steel ingot without using a gradual change slag system regulating agent;
FIG. 4 shows an electroslag remelting ingot produced using a graded slag system regulating agent;
FIG. 5 is a macrostructure of an electroslag remelting steel ingot using a gradual change slag system regulating agent;
FIG. 6 is a plot comparing the slag density (1650 deg.C) as measured in the laboratory and as calculated by the model.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The invention discloses a process method for improving molten steel quality by gradually regulating and controlling an electroslag remelting high-temperature slag system in a preferred embodiment, which comprises the following steps:
as shown in figure 2, after a period of time and in the process of electroslag remelting, a special slag system gradual change regulating agent is uniformly scattered into a slag pool step by step, the electroslag remelting time is calculated, and the adding amount is gradually adjusted to achieve the aims of stabilizing the physical and chemical properties of a high-temperature slag system and improving the quality of molten steel.
The gradual change regulating agent added into the high-temperature slag bath can quickly sink to the bottom of the slag bath, namely the position of a ball in figure 1, then specific gravity regulating substances in the regulating agent are gradually melted in equal proportion along with the continuous operation of electroslag reaction, the specific gravity regulating substances can be made of iron sheets or iron particles, the density of the regulating agent is correspondingly lightened, the regulating agent gradually floats to the upper part of the slag bath, and the slag surface is not exposed all the time. The regulating agent gradually and slowly releases a slag system regulating substance while slowly floating, the regulating substance is calcium core, MgO, TiO2, aluminum particles, iron particles or silicon powder to supplement the defect of corresponding substance elements caused by the reaction of a high-temperature slag system and an electrode rod, the gradual-change regulating agent is uniformly distributed and stably suspended at the inner position of the high-temperature slag system under the condition of no harmful substances or side effects, and the oxygen absorption substance is slowly released to form a passivation film layer to isolate gas elements in air from being transferred into molten steel.
In the whole process, aluminum particles in the gradual change regulating agent can also perform exothermic reaction with FeO in the metal pool component, so that sufficient heat is provided for each area of the whole electroslag remelting pool, the solidification rate of metal liquid drops can be reduced, and meanwhile, metallic iron generated by the exothermic reaction can enter the metal pool to perform feeding on steel ingots, so that the internal solidification group structure is improved, the tissue crystal grains are refined, the density of the steel ingots is improved, the quality defects of looseness, shrinkage cavities, cleanliness, gas content and the like of the steel ingots at the bottom are improved, and the yield of the metal pool is improved.
In order to facilitate the gradual change of the regulating agent to generate a specific slag system regulating effect, what needs to be solved is the position state of the regulating agent in the high-temperature slag bath, as shown in fig. 1, which is a schematic position diagram of three different slag system regulating agents in an electroslag remelting slag bath.
In the figure, the b position is that the density of the slag system regulating agent is too small, the slag system regulating agent directly floats above the slag surface when added into a slag pool and cannot sink into molten slag, most of aluminum particles and silicon powder in the regulating agent react with oxygen in the air, SiO2 and Al2O3 are generated and dissolved in the slag system, the alkalinity of the slag system is reduced, the deterioration effect on the dephosphorization and desulfurization performance of the slag system is generated, in addition, the A12O3 in the slag is increased, the increase of aluminum elements in a steel ingot can also be caused, and the content of the element components in the steel ingot cannot reach the standard.
The position c in the figure is that the slag system regulating agent has overlarge density, and is directly sunk into the metal pool when being added into the slag pool, and various substances in the slag system regulating agent are melted by high-temperature molten steel in the metal pool to form the following series of reactions:
Ca+[O]＝(CaO)
Si+[O]＝(SiO2)
4[Al]+3(TiO2)＝2(Al2O3)+3[Ti]
Fe+[O]＝(FeO)
the reaction causes excessive burning loss of iron element in molten steel, generates Al2O3 inclusion, and remains in the molten steel, thereby polluting the molten steel and causing double reduction of the yield and quality of steel ingot metal.
Therefore, the slag system regulating agent in this embodiment has two different substances in the state of the position, the density of which is slightly greater than that of the molten slag, and the slag system regulating agent can sink rapidly after being added into the slag bath and gradually float upwards slowly until the slag system regulating agent is completely melted, namely the position of the ball a in fig. 1. To determine the density of the slag-based modifier, first, the slag specific volume V1250 ℃, (the inverse density V1 /) at low temperature 1250 ℃ was calculated using a slag specific volume calculation model as follows:
in the above formula, the percentage content of the slag oxide is shown in brackets, and then according to the slag density models at different temperatures:
t-temperature/DEG C in the above formula;
the density of 200 groups of electroslag high-temperature slag systems with different compositions at the temperature of 1650 ℃ is subjected to experimental measurement and model calculation comparison and correction, and the comparison result is shown in figure 6.
From the table, it can be seen that in different types of slag samples, the actual measurement value is basically consistent with the result of model calculation, the error is within +/-0.15 g/cm3 and is within the tolerance range of the error, thereby providing a data base for the preparation of the slag system regulating agent.
According to the 200 groups of data, the average density value range of different high-temperature slag systems is 3.176-3.204g/cm3 through experimental measurement and model calculation, so the density value range of the slag system regulating agent is set to be 3.6-4.2g/cm3, the regulating agent is subjected to laboratory high-pressure compression molding according to the determined density range of the regulating agent, the shape of the regulating agent is a cylinder, the volume of the regulating agent is controlled to be 13.63-14.15cm3, and the detailed component composition range of the regulating agent is shown in Table 2.
TABLE 2 slag System Conditioning agent compositions
The embodiment limits the density of the slag system regulating agent, can ensure that the slag system regulating agent is added into a slag pool and then quickly sinks and suspends below molten slag, reduces the burning loss of silicon powder and metal aluminum in the formula, improves the metallurgical effect and improves the field operation environment.
The slag system regulating agent has the advantages of high compactness, difficult breakage and the like, and is convenient to store. In addition, the alkalinity of the slag system regulator is controlled to be 10-12, and the calcium-aluminum ratio is controlled to be 1.8-2.0, so that the slag system regulator has good capabilities of dephosphorizing, desulfurizing and adsorbing Al2O3 inclusions when being melted.
It is worth to be noted that, the slag system regulating agent of the embodiment adopts calcium core particles, iron particles, silicon powder, aluminum particles, MgO and TiO2 as raw materials, although the raw materials are conventional, the content of each raw material is controlled to ensure that the slag system regulating agent plays an unexpected timely effect in the whole electroslag remelting process, that is, the slag system regulating agent can provide sufficient heat for molten steel in a metal pool to delay the solidification time of the molten steel, and simultaneously, the slag system regulating agent can be used for feeding steel ingots, thereby reducing the quality defects of the steel ingots and improving the yield of the electroslag steel ingots; in addition, the slag system regulating agent can not bring any harmful elements and impurities, so that secondary pollution can not be caused, and the quality of steel ingots is effectively ensured.
In the embodiment, in order to ensure that the slag system regulating agent can continuously and slowly release the supplementary substance in the whole electroslag remelting process and continuously provide heat, namely that the supplementary substance in the slag system regulating agent can be slowly released to supplement consumption caused by slag system reaction, the solidification time of molten steel is prolonged, and the amount of the slag system regulating agent added into a slag pool is controlled, the addition amount m is determined according to the following regulating agent addition amount model:
wherein m is the specific addition of the regulating agent in kg within the remelting end time of a single electrode rod;
lambda is the empirical value of the remelting coefficient of the steel type, 1.0-1.2 is taken as the high-carbon steel, and 0.5-0.8 is taken as the medium-low carbon steel;
i is electroslag remelting current intensity, A;
r is the resistivity of the high-temperature slag, omega.m;
s is the electrode rod surface area, cm 2;
l is the length of the electrode bar, m;
v is the remelting rate of the electrode bar, cm/min;
and t is the electrode bar remelting time min.
In addition, the slag system regulating agent is made into a dough shape, and the size of the prepared dough shape is limited, so that in order to further ensure that the slag system regulating agent can continuously provide substances and heat, the total melting time of a single slag system regulating agent added into the electric slag pool is not more than 1min, the adding interval time of each batch is not less than 5min, the time limitation is not a specific value due to the influence of factors such as manual operation, equipment running speed and the like, and the corresponding adjustment can be carried out according to the actual production situation on site.
Example 2
The process method for improving the quality of molten steel by gradually regulating and controlling the electroslag remelting high-temperature slag system is basically the same as that in the embodiment 1, and is different in that the material composition is more detailed: in the slag system regulating agent of the embodiment, the weight percentage of the calcium core particles is 36 percent; the weight percentage of MgO is 10 percent; 4% by weight of TiO 2; the weight percentage of the aluminum particles is 28 percent; the weight percentage of the iron particles is 8 percent; the weight percentage of the silicon powder is 5%, and the amount of the epoxy resin glue used in the binder in the embodiment is 5 ml. In addition, the alkalinity of the slag system regulator in the embodiment is 10, and the calcium-aluminum ratio is 1.8.
To further illustrate the advancement and creativity of the present invention, the inventor performed a gradual change control test of slag system in the process of electroslag remelting in a certain plant, and detailed test conditions are as follows.
Experimental basic industrial data: 2 tons of electroslag remelting furnace, the production steel grade is S355J2, the production section size is phi 505 x 250mm, and the steel ingot produced by adding the slag system regulating agent is shown in figure 3.
As shown in fig. 3 and 5, in order to clearly show that the comparison is performed on the existence of the slag system regulating agent, the macroscopic structure comparison analysis is performed on the steel ingot in the embodiment, and the reason that the steel ingot is loosened at the edge and the center when the slag system regulating agent is not added is that the steel liquid is solidified earlier and has no obvious feeding sign; the solidification of molten steel is delayed after the slag system regulating agent is added, the high-temperature slag system is effectively supplemented, and the overall quality performance of the steel ingot is better.
In addition, in order to further explain the influence of the slag system regulating agent on the quality of the steel ingot and the yield of the molten steel, the statistical analysis was performed on the 15 electrode rods produced in the field in the batch, and the results are shown in table 3.
TABLE 3 statistical table of steel ingot quality
The production condition of 15 electrode rods shows that the overall quality of the steel ingot is comprehensively improved after the slag system regulating agent is added, the comprehensive grade (central shrinkage and loosening) of the macrostructure is 86.67 percent within 0.5 grade, and the yield of the molten steel is 14 electrode rods with the yield of more than 95 percent.
By comparing and analyzing the production condition of the electrode bar and the appearance characteristics of the solidification structure of the steel ingot, the slag system regulating agent has the main beneficial effects on the electroslag remelting process and the electroslag ingot production: the high-temperature slag system is fully supplemented, and the dephosphorization and desulfurization effects of the slag system are effectively prolonged and enhanced; TiO2 in the slag system is supplemented, so that the problem of uneven aluminum and titanium of the cast ingot is solved; feeding steel ingots, improving the internal solidification group structure, refining tissue grains, improving the compactness of the steel ingots, improving the quality defects of looseness, shrinkage cavity, cleanliness, gas content and the like of the steel ingots at the bottom, and improving the yield of metal pools.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (7)
1. A process method for improving the quality of molten steel by gradually regulating and controlling an electroslag remelting high-temperature slag system is characterized by comprising the following steps of:
uniformly scattering a special slag system gradual change regulating agent into a slag pool step by step after and in the process of electroslag remelting starting for a period of time, calculating the electroslag remelting time,
the gradual regulating agent can gradually release slag system regulating substances along with the electroslag process to supplement the substance consumption of the high-temperature slag system, and is uniformly distributed and stably suspended in the high-temperature slag system under the condition of no harmful substances or side effects, and the slow-release oxygen absorption substance forms a passivation film layer to isolate gas elements in air from being transferred into molten steel.
2. The process method for improving the quality of molten steel by gradually regulating and controlling the electroslag remelting high-temperature slag system according to claim 1, which is characterized by comprising the following steps of: the density gradient range of the slag system gradient regulating agent is 3.6-4.2 g-cm3The initial value of the density of the final product is set to 4.2 g.cm3The density is gradually reduced to 3.6 g-cm along with the progress of electroslag remelting reaction3。
3. The process method for improving the quality of molten steel by gradually regulating and controlling the electroslag remelting high-temperature slag system according to claim 2, which is characterized by comprising the following steps of: the slag system regulating agent comprises 35-40 wt% of calcium core particles (metal calcium inside and iron sheet wrapped outside); the weight percentage of MgO is 5-10%; the weight percentage of TiO2 is 2-5%; the weight percentage of the aluminum particles is 25-30%; the weight percentage of the iron particles is 5-8%; the weight percentage of the silicon powder is 5 percent, the alkalinity of the regulator is controlled to be 10-12, and the calcium-aluminum ratio is controlled to be 1.8-2.0.
4. The process method for improving the quality of molten steel by gradually regulating and controlling the electroslag remelting high-temperature slag system according to claim 2, characterized in that: the shape of the slag system regulating agent is a cylinder, the volume is controlled to be 13.63-14.15cm3, and the slag system regulating agent is added into a slag pool until the total melting time is not more than 1 min.
5. The process method for improving the quality of molten steel by gradually regulating and controlling the electroslag remelting high-temperature slag system according to any one of claims 1 to 4, which is characterized in that: the slag system regulating agent addition model is as follows:
wherein m is the specific addition of the regulating agent, kg, in the remelting end time of a single electrode rod;
lambda is the empirical value of the remelting coefficient of the steel type, 1.0-1.2 is taken as the high-carbon steel, and 0.5-0.8 is taken as the medium-low carbon steel;
i is electroslag remelting current intensity, A;
r is the resistivity of the high-temperature slag, omega.m;
s is the electrode rod surface area, cm 2;
l is the length of the electrode bar, m;
v is the remelting rate of the electrode bar, cm/min;
and t is the electrode bar remelting time min.
6. The process method for improving the quality of molten steel by gradually regulating and controlling the electroslag remelting high-temperature slag system according to claim 1, which is characterized by comprising the following steps of: the sequence of adding the slag system regulating agent into the slag pool is as follows: the slag is added from the center of the slag pool close to the electrode rod, then is uniformly scattered all around, is spread on the surface of the whole slag pool and quickly sinks to the lower part of the slag.
7. The process method for improving the quality of molten steel by gradually regulating and controlling the electroslag remelting high-temperature slag system according to claim 6, which is characterized by comprising the following steps of: the adding time is controlled not to exceed 2min every time, and the adding interval time is not less than 5 min.
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| CN116607015A (en) * | 2023-04-11 | 2023-08-18 | 宝立合金有限公司 | Slag pool dynamic balancing method in electroslag smelting process |
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