CN116334398A - Method for prolonging molten metal dripping track in electroslag remelting process - Google Patents
Method for prolonging molten metal dripping track in electroslag remelting process Download PDFInfo
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- CN116334398A CN116334398A CN202310057924.4A CN202310057924A CN116334398A CN 116334398 A CN116334398 A CN 116334398A CN 202310057924 A CN202310057924 A CN 202310057924A CN 116334398 A CN116334398 A CN 116334398A
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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
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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
- C22B9/006—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals with use of an inert protective material including the use of an inert gas
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Abstract
The invention relates to a method for prolonging a molten metal drop falling track in an electroslag remelting process, which comprises the following steps: in the electroslag remelting system, a spray pipe is arranged, argon is blown into a slag pool through the spray pipe to stir the slag in the electroslag remelting process, so that the original vertical dropping mode of the metal liquid drops is changed into a non-vertical dropping mode, and the contact time of the metal liquid drops and the slag is prolonged. According to the invention, the falling track of the metal liquid drop heated and melted by the consumable electrode in the electroslag remelting process is changed, so that the residence time of the metal liquid drop in the liquid slag is prolonged, and the full contact between the metal liquid drop and the liquid slag is further increased, thereby achieving the further purification effect on metal and realizing the production of the ultra-clean metal electroslag ingot.
Description
Technical Field
The invention belongs to the technical field of electroslag remelting metallurgy, and particularly relates to a method for prolonging a molten metal drop falling track in an electroslag remelting process.
Background
Electroslag remelting is the processing of steel (typically electric furnace steel and converter steel) made by a common smelting process into consumable electrodes, the electrodes being heated by a slag bath through which current is passed during the remelting process, the top of the consumable electrodes being progressively heated by the slag bath and producing droplets of metal falling down in the slag bath. In the process that the metal liquid drops fall in the slag pool, impurities in the metal liquid drops can migrate to the surfaces of the liquid drops, contact with liquid slag and are adsorbed by the liquid slag, and then the purification process of the metal liquid drops is completed. Since impurities among the metal droplets need to migrate to the surface and impurities on the surface need to be adsorbed for a certain time, the time for the metal droplets to fall down is very important for metal purification. The depth of the liquid slag pool is increased, which is favorable for purifying the metal liquid drops, but in actual production, the higher the depth of the liquid slag pool is, the higher the heat taken away by cooling water is, so that the electricity consumption is increased, and the cost is increased. Thus, in electroslag production in general, the control depth of the slag bath is relatively shallow. This would make the removal of impurities by the metal droplets disadvantageous, and how to extend the falling trajectory of the metal droplets in a relatively shallow slag bath would be of great significance for further purification of the metal droplets.
The literature (simulation study of the dripping behavior and the shape of a molten pool in the electroslag remelting process of a rotating electrode) (the steel research journal 2021, 1 st year) reports that the falling track of a metal droplet in a slag bath can be changed by a rotating electrode method in the electroslag remelting process, so that the effect of prolonging the residence time of the metal droplet in the slag bath is achieved, and the quality of an electroslag steel ingot is further improved. The method requires a relatively high degree of shape and warpage of the consumable electrode, which is relatively easy to achieve for round ingots, but not for non-round ingots, such as slab ingots, due to the need to rotate the consumable electrode. In addition, even a circular consumable electrode cannot complete the rotation of the electrode if the electrode itself is bent or not flat, because the electrode is easily scraped against a crystallizer during the rotation to cause accidents. The limitation of changing the falling track of the metal liquid drop in the slag pool by a rotating method is too large, so that the method is not suitable for being applied to the field of electroslag remelting.
Disclosure of Invention
The invention provides a method for prolonging the falling track of molten metal drops in an electroslag remelting process, which prolongs the residence time of the molten metal drops in the liquid slag by changing the falling track of the molten metal drops heated by a consumable electrode in the electroslag remelting process, so as to further increase the full contact between the molten metal drops and the liquid slag, further achieve the effect of purifying metal and realize the production of ultra-clean metal electroslag ingots.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
a method for prolonging a molten metal drop falling track in an electroslag remelting process comprises the following steps: in the electroslag remelting system, a spray pipe is arranged, argon is blown into a slag pool through the spray pipe to stir the slag in the electroslag remelting process, so that the original vertical dropping mode of the metal liquid drops is changed into a non-vertical dropping mode, and the contact time of the metal liquid drops and the slag is prolonged.
In order to make the liquid slag have good stirring force under the condition of blowing gas, a slag system with low viscosity is needed to be selected, and the pseudo-ginseng slag (70% CaF) which is conventionally used at 1500℃ at present 2 +30％Al 2 O 3 ) The viscosity is 0.148Pa.s, the relatively high stirring effect is not ideal, and the production test shows that the viscosity of the slag system is below 0.08Pa.s at 1500 ℃, and the slag system can ensure good stirring force under the condition of blowing gas, so that the stirring of metal liquid drops is easy to realize. To this end CaF is formulated 2 +Al 2 O 3 The ternary slag system of +CaO is used as the bulk slag.
The ternary slag system is CaF 2 -Al 2 O 3 CaO with a composition ranging from CaF 2 ：60％-70％；Al 2 O 3 :20-30%; caO:5-10% and a viscosity in the range of 0.065-0.075Pa.s at 1500 ℃.
Because the prepared ternary slag system contains CaO, moisture in the air is easy to absorb, and baking is needed before use, the baking temperature is controlled to be 300-500 ℃, and the baking time is controlled to be not less than 2 hours.
Preferably, the method for prolonging the molten metal drop falling track in the electroslag remelting process specifically comprises the following steps of:
1) Placing a conductive guard plate made of industrial pure iron or the same material as an electroslag ingot to be produced on a bottom water tank, uniformly scattering a first layer of conductive arc starting slag on the conductive guard plate, controlling the thickness of the slag layer to be 10-30 mm, then placing a crystallizer on the bottom water tank, and sealing the joint of the crystallizer and the bottom water tank;
2) Inserting the spray pipe into the crystallizer, horizontally placing the horizontal section of the spray pipe on the first layer of conductive arc starting slag, ensuring that the horizontal section of the spray pipe is positioned on the central line of the bottom of the crystallizer, and connecting the spray pipe with argon;
3) Then a second layer of conductive arc starting slag is scattered, and the thickness of the second layer of conductive arc starting slag is controlled to be capable of burying the horizontal section of the spray pipe;
4) Lowering the consumable electrode into the crystallizer, keeping the front end and the conductive arc starting slag in contact with each other, starting cooling water of a bottom water tank, starting a power supply to start arc starting slag for the conductive arc starting slag through the consumable electrode, adding body slag into the crystallizer in the process, and controlling the depth of a slag pool to be 200-500 mm after the body slag is completely melted;
5) The distance between the horizontal section of the spray pipe and the bottom end surface of the consumable electrode is adjusted, the distance is controlled to be 100-300 mm, then argon is blown, the blowing pressure is controlled to be 0.7-0.8 MPa, the slag pool is stirred by blowing the argon, the dropping track of the molten metal drops is changed, the dropping time of the molten metal drops in slag is further prolonged, and the purifying effect of the molten metal drops is further improved;
6) And in the final stage of electroslag remelting feeding, the distance between the horizontal section of the spray pipe and the bottom end surface of the consumable electrode is regulated again, the distance is controlled to be 50-100 mm, the spraying pressure is controlled to be 0.5-0.6 MPa, after the consumable electrode is melted, the spraying pipe is lifted out of the liquid slag pool, the spraying pressure is regulated to be more than or equal to 0.8MPa, the spraying is carried out for 5-10 seconds, the adhesive slag in the pipe and around the spray hole is removed, and the electroslag remelting smelting process is completed.
In the electroslag remelting process, the temperature of the liquid slag is up to 1700 ℃, and in order to be capable of jetting gas into the liquid slag, the material of the spray pipe is a high-temperature-resistant tungsten pipe.
The spray pipe is L-shaped, and the upper side wall of the horizontal section of the spray pipe is uniformly provided with air spraying holes at intervals of 50 mm; the height of the vertical section of the spray pipe is H, and 2>H/H is required to be more than 1.5, wherein H is the height of the crystallizer; the length of the horizontal section of the nozzle is S, and 1.2> S/D >1.0 is required, wherein D is the equivalent diameter of the consumable electrode.
The cross section of the spray pipe is circular or rectangular, the equivalent diameter of the inner diameter is 5-20 mm, the wall thickness is 5-10 mm, the cross section of the spray holes distributed on the horizontal section is in a truncated cone shape with large upper part and small lower part, the height of the spray holes is the wall thickness of the spray pipe, the diameter of the upper part of the spray holes is 4-6 mm, and the diameter of the lower part of the spray holes is 2-3 mm.
In order to prevent the spray pipe from being damaged due to overlarge thermal stress, the horizontal section of the spray pipe is preheated before the spray pipe is inserted into a crystallizer, the preheating temperature is controlled to be 900-1200 ℃, and the spray hole of the spray pipe is also required to be plugged before preheating in order to prevent liquid slag from entering the spray hole and affecting gas spraying in the initial use process.
The plugging material is a ceramic plug, and quartz powder is coated on the side wall of the plugging plug in order to blow out the plugging plug by argon gas at high temperature without affecting the blowing-in of the gas.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, argon is blown into the liquid slag, so that the liquid slag in the liquid slag pool can be stirred to change the falling track of the metal liquid drops, and the atmosphere in the crystallizer can be controlled, and the method is specifically shown as follows:
1) The original vertical falling mode of the metal liquid drops can be changed into a non-vertical falling mode by argon blowing and liquid slag stirring, and 0.5-2 s of metal liquid drops and liquid can be addedThe contact time of slag, the number of inclusions smaller than 3-5 mu m in metal is changed from original 5-10 inclusions/cm 2 Down to 2-5 pieces/cm 2 Greatly improves the metal purification effect and is beneficial to producing ultra-pure electroslag ingots;
2) The oxygen in the air can be prevented from entering the crystallizer by blowing argon, the burning loss rate of easily oxidized elements in the electroslag ingot is reduced, the burning loss rate of each easily oxidized and burned alloy element is reduced by 30-50% compared with the original technology, the stable control of the elements in the alloy is facilitated, the components of the electroslag ingot, particularly the component qualification rate of easily oxidized metal elements, can be improved from the original average 94% to more than 98%.
Drawings
FIG. 1 is a schematic diagram of an initial stage of electroslag remelting according to the invention;
FIG. 2 is a schematic diagram of the electroslag remelting process stage according to the invention;
FIG. 3 is a schematic diagram of a nozzle cross-section nozzle portion.
In the figure: 1-a vertical section of the spray pipe; 2-crystallizer; 3-bottom tank; 4-a conductive guard plate; 5-a consumable electrode; 6-conducting arcing slag; 7-a horizontal section of the spray pipe; 8-a power supply; 9-electroslag ingots; 10-metal droplets; 11-a liquid slag pool; 12-a metal bath; 7-1-spraying holes; 7-2-plugging plugs.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In order to change the falling track of the molten metal liquid drop heated by the consumable electrode in the electroslag remelting process, prolong the residence time of the molten metal liquid drop in the liquid slag, further increase the full contact between the metal liquid drop and the liquid slag, further achieve the effect of purifying metal and realize the production of ultra-clean metal electroslag ingots, the invention provides a method for prolonging the falling track of the molten metal liquid drop in the electroslag remelting process, and the scheme is described as follows by combining a schematic diagram:
example 1:
the method is adopted to produce the bearing steel electroslag ingot with the diameter of 500mm and the height of 1500 mm.
Ternary slag system (65% CaF) 2 +25％Al 2 O 3 +10% cao) was baked at a temperature of 350 ℃ for 4 hours.
An L-shaped spray pipe with the vertical section height of 2300mm and the horizontal section length of 300mm is selected, a ceramic plug is adopted to seal the spray hole 7-1 (shown in figure 3), and then the spray pipe horizontal section 7 is preheated to 1000 ℃.
As shown in fig. 1, an industrial pure iron conductive guard plate 4 is placed on a bottom water tank 3, then a first layer of conductive arc-forming slag 6 with the thickness of 15mm is uniformly scattered on the conductive guard plate 4, then a spray pipe is connected with argon gas, the spray pipe is inserted into a crystallizer 2, so that a spray pipe horizontal section 7 is horizontally placed on the first layer of conductive arc-forming slag 6, the spray pipe horizontal section 7 is ensured to be positioned on the diameter of the center circle of the bottom of the crystallizer 2, and a second layer of conductive arc-forming slag 6 is added to submerge the spray pipe horizontal section 7;
the consumable electrode 5 is lowered into the crystallizer 2, the front end and the conductive arcing slag 6 are kept in contact with each other, the cooling water of the bottom water tank 3 is started, then the power supply 8 is started to perform arcing and deslagging on the conductive arcing slag 6 through the consumable electrode 5, and ternary system body slag (65% CaF) is added into the crystallizer 2 in the process 2 +25％Al 2 O 3 +10% CaO), and after the bulk slag is completely melted, the depth of the slag pool is controlled to be 280mm.
As shown in fig. 2, the distance between the horizontal section 7 of the spray pipe and the bottom end surface of the consumable electrode 5 is adjusted to be 120mm, and then argon is sprayed, and the spraying pressure is controlled to be 0.78MPa;
and in the final stage of electroslag remelting feeding, the distance between the horizontal section 7 of the spray pipe and the bottom end face of the consumable electrode 5 is regulated again, the distance is controlled to be 60mm, the spraying pressure is controlled to be 0.52MPa, after the consumable electrode 5 is melted, the spraying pipe is lifted out of the liquid slag pool, the spraying pressure is regulated to be the upper limit of 0.8MPa, the spraying is carried out for 5-10 seconds, and the slag in the pipe and around the spray hole is removed, so that the electroslag remelting smelting process is completed.
Example 2:
the method is used for producing 1000mm 450mm high 1200mm die steel electroslag ingots.
Ternary slag system (65% CaF) 2 +25％Al 2 O 3 +10% cao) was baked at 400 ℃ for 3 hours.
An L-shaped spray pipe with the vertical section height of 2000mm and the horizontal section length of 350mm is selected, a ceramic plug is adopted to seal the spray hole 7-1 (shown in figure 3), and then the spray pipe horizontal section 7 is preheated to 1100 ℃.
As shown in fig. 1, an industrial pure iron conductive guard plate 4 is placed on a bottom water tank 3, then a first layer of conductive arc starting slag 6 with the thickness of 20mm is uniformly spread on the conductive guard plate 4, then a spray pipe is connected with argon gas, the spray pipe is inserted into a crystallizer 2, a spray pipe horizontal section 7 is horizontally placed on the first layer of conductive arc starting slag 6, meanwhile, the spray pipe horizontal section 7 is ensured to be positioned on the central line of the bottom of the crystallizer 2, and a second layer of conductive arc starting slag 6 is added to submerge the spray pipe horizontal section 7;
lowering the consumable electrode 5 to the inside of the crystallizer 2, keeping the front end and the conductive arc starting slag 6 in contact with each other, starting the cooling water of the bottom water tank 3, starting the power supply 8 to start the arc starting slag 6 through the consumable electrode 5, and adding ternary system body slag (65% CaF) into the crystallizer 2 in the process 2 +25％Al 2 O 3 +10% CaO), and controlling the depth of the slag bath to 300mm after the bulk slag is completely melted.
Referring to FIG. 2, the distance between the horizontal section 7 of the spray pipe and the bottom end face of the consumable electrode 5 is adjusted to be 150mm, then argon is sprayed, and the spraying pressure is controlled to be 0.79MPa;
and in the final stage of electroslag remelting feeding, the distance between the horizontal section 7 of the spray pipe and the bottom end face of the consumable electrode 5 is regulated again, the distance is controlled to be 65mm, the spraying pressure is controlled to be 0.55MPa, after the consumable electrode 5 is melted, the spraying pipe is lifted out of the liquid slag pool, the spraying pressure is regulated to be the upper limit of 0.8MPa, the spraying is carried out for 5-10 seconds, and the slag in the pipe and around the spray hole is removed, so that the electroslag remelting smelting process is completed.
The process of the invention is adopted for production, the use effect is compared with the prior process, and the effect is shown in Table 1:
table 1:
Claims (10)
1. the method for prolonging the dropping track of the molten metal drops in the electroslag remelting process is characterized by comprising the following steps of: in the electroslag remelting system, a spray pipe is arranged, argon is blown into a slag pool through the spray pipe to stir the slag in the electroslag remelting process, so that the original vertical dropping mode of the metal liquid drops is changed into a non-vertical dropping mode, and the contact time of the metal liquid drops and the slag is prolonged.
2. The method for extending the drop trajectory of molten metal in an electroslag remelting process as claimed in claim 1, wherein CaF is prepared 2 +Al 2 O 3 The ternary slag system of +CaO is used as the bulk slag.
3. The method for extending a molten metal drop trajectory in an electroslag remelting process as claimed in claim 2, wherein the ternary slag system has a composition ranging from CaF 2 ：60％～70％；Al 2 O 3 :20% -30%; caO:5 to 10 percent, and the viscosity range is 0.065 to 0.075Pa.s at 1500 ℃.
4. A method for extending a drop trajectory of molten metal in an electroslag remelting process according to claim 3, wherein the ternary slag system is baked at a temperature of 300 to 500 ℃ for a baking time of not less than 2 hours before use.
5. A method for extending the drop trajectory of molten metal during electroslag remelting as claimed in any one of claims 1 to 4 wherein the specific method comprises:
1) Placing a conductive guard plate made of industrial pure iron or the same material as an electroslag ingot to be produced on a bottom water tank, uniformly scattering a first layer of conductive arc starting slag on the conductive guard plate, controlling the thickness of the slag layer to be 10-30 mm, then placing a crystallizer on the bottom water tank, and sealing the joint of the crystallizer and the bottom water tank;
2) Inserting the spray pipe into the crystallizer, horizontally placing the horizontal section of the spray pipe on the first layer of conductive arc starting slag, ensuring that the horizontal section of the spray pipe is positioned on the central line of the bottom of the crystallizer, and connecting the spray pipe with argon;
3) Then a second layer of conductive arc starting slag is scattered, and the thickness of the second layer of conductive arc starting slag is controlled to be capable of burying the horizontal section of the spray pipe;
4) Lowering the consumable electrode into the crystallizer, keeping the front end and the conductive arc starting slag in contact with each other, starting cooling water of a bottom water tank, starting a power supply to start arc starting slag for the conductive arc starting slag through the consumable electrode, adding body slag into the crystallizer in the process, and controlling the depth of a slag pool to be 200-500 mm after the body slag is completely melted;
5) Adjusting the distance between the horizontal section of the spray pipe and the bottom end surface of the consumable electrode, controlling the distance to be 100-300 mm, and then spraying argon, wherein the spraying pressure is controlled to be 0.7-0.8 MPa;
6) And in the final stage of electroslag remelting feeding, the distance between the horizontal section of the spray pipe and the bottom end surface of the consumable electrode is regulated again, the distance is controlled to be 50-100 mm, the spraying pressure is controlled to be 0.5-0.6 MPa, after the consumable electrode is melted, the spraying pipe is lifted out of the liquid slag pool, the spraying pressure is regulated to be more than or equal to 0.8MPa, the spraying is carried out for 5-10 seconds, the adhesive slag in the pipe and around the spray hole is removed, and the electroslag remelting smelting process is completed.
6. The method for extending the drop trajectory of molten metal in an electroslag remelting process of claim 5 wherein the material of the nozzle is tungsten.
7. The method for prolonging the falling track of molten metal drops in an electroslag remelting process according to claim 5, wherein the spray pipe is L-shaped, and the upper side wall of the horizontal section of the spray pipe is uniformly provided with air spraying holes; the height of the vertical section of the spray pipe is H, and 2>H/H is required to be more than 1.5, wherein H is the height of the crystallizer; the length of the horizontal section of the nozzle is S, and 1.2> S/D >1.0 is required, wherein D is the equivalent diameter of the consumable electrode.
8. The method for extending the dropping track of molten metal in the electroslag remelting process according to claim 5, wherein the cross section of the spray pipe is circular or rectangular, the equivalent diameter of the inner diameter is 5-20 mm, the wall thickness is 5-10 mm, the cross section of the spray holes distributed on the horizontal section is in a truncated cone shape with a large upper part and a small lower part, the diameter of the upper part of the spray holes is 4-6 mm, and the diameter of the lower part of the spray holes is 2-3 mm.
9. The method for extending the falling track of molten metal drops in an electroslag remelting process according to claim 5, wherein the horizontal section of the spray pipe is preheated before the spray pipe is inserted into the crystallizer, the preheating temperature is controlled to be 900-1200 ℃, and the spray holes of the spray pipe are plugged before preheating.
10. The method for extending the drop trajectory of molten metal in an electroslag remelting process according to claim 9, wherein the plugging material is a ceramic plug, and the side wall of the plug is coated with quartz powder.
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| CN202310057924.4A CN116334398A (en) | 2023-01-18 | 2023-01-18 | Method for prolonging molten metal dripping track in electroslag remelting process |
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| CN202310057924.4A CN116334398A (en) | 2023-01-18 | 2023-01-18 | Method for prolonging molten metal dripping track in electroslag remelting process |
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