CN114472836A - Method for preventing slab continuous casting high-carbon steel from casting and breakout - Google Patents
Method for preventing slab continuous casting high-carbon steel from casting and breakout Download PDFInfo
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- 229910000677 High-carbon steel Inorganic materials 0.000 title claims abstract description 88
- 238000005266 casting Methods 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000009749 continuous casting Methods 0.000 title claims abstract description 25
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 81
- 239000010959 steel Substances 0.000 claims abstract description 81
- 239000000463 material Substances 0.000 claims abstract description 35
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000007789 sealing Methods 0.000 claims abstract description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 40
- 238000001816 cooling Methods 0.000 claims description 27
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 16
- 229910052802 copper Inorganic materials 0.000 claims description 16
- 239000010949 copper Substances 0.000 claims description 16
- 229910052742 iron Inorganic materials 0.000 claims description 16
- 239000010425 asbestos Substances 0.000 claims description 12
- 229910052895 riebeckite Inorganic materials 0.000 claims description 12
- 239000000835 fiber Substances 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000003566 sealing material Substances 0.000 claims description 7
- 239000002893 slag Substances 0.000 claims description 7
- 238000003892 spreading Methods 0.000 claims description 6
- 230000001133 acceleration Effects 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 4
- 238000006073 displacement reaction Methods 0.000 claims description 4
- 239000002657 fibrous material Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000004886 process control Methods 0.000 claims 1
- 238000007711 solidification Methods 0.000 abstract description 11
- 230000008023 solidification Effects 0.000 abstract description 11
- 238000002844 melting Methods 0.000 description 8
- 230000008018 melting Effects 0.000 description 8
- 239000000843 powder Substances 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 230000003014 reinforcing effect Effects 0.000 description 3
- 229910000621 Ultra-high-carbon steel Inorganic materials 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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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
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/08—Accessories for starting the casting procedure
- B22D11/088—Means for sealing the starter bar head in the moulds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/168—Controlling or regulating processes or operations for adjusting the mould size or mould taper
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
- B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
- B22D11/182—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by measuring temperature
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Abstract
The invention relates to a method for preventing high-carbon steel from casting breakout in slab continuous casting, which comprises the following steps: step 1: loading a dummy bar, and step 2: pouring high-carbon steel, guiding ingot and sealing; and step 3: controlling the casting process; and 4, step 4: finishing the whole high-carbon steel breakout-preventing casting process flow; according to the scheme, the open casting breakout accident caused by insufficient strength of the head billet shell due to solidification characteristics during the open casting of high-carbon steel is well solved by optimizing key continuous casting process parameters such as the carbon content of a sealing dummy ingot material, optimizing sealing dummy ingot parameters, setting the taper of a crystallizer, controlling the superheat degree of molten steel in open casting, optimizing the parameters in the open casting process and the like.
Description
Technical Field
The invention relates to a method, in particular to a method for preventing high-carbon steel from casting breakout during slab continuous casting, and belongs to the technical field of ferrous metallurgy continuous casting.
Background
In the current continuous casting process in the steel industry, high-carbon steel (the carbon content exceeds more than 0.40%) is gradually produced by adopting a slab continuous casting production process so as to realize the purpose of batch continuous production. However, since the high-carbon steel is non-equilibrium solidified during the solidification process, and the solidus temperature of the high-carbon steel is similar to the surface temperature of the casting blank, the effective shell thickness generated by the high-carbon steel initially is thin and is only about 50% of peritectic steel. Meanwhile, the high-carbon steel has serious dendrite segregation, delayed solidification, large dendrite brittleness, low crystal boundary strength and low strength and plasticity of the initial solidified shell. Due to the initial solidification characteristic of the high-carbon steel, the hidden danger of casting and breakout is particularly great when the sealed dummy ingot of the high-carbon steel is cast in the early stage of slab continuous casting. For example, in a certain steel plant, when high-carbon steel is produced, the breakout rate of the cast-on sealed dummy ingot is more than 5 times that of other steel grades. The breakout is poured once, so that a crystallizer, a bending section and a dummy bar chain for continuous casting are all burnt, and direct economic loss is over 200 ten thousand yuan. Therefore, how to eliminate the hidden danger of high carbon steel casting breakout accident by optimizing the casting process of high carbon steel is very important.
Through the search of the inventor, the related documents and patents of the slab continuous casting high-carbon steel production disclosed at present focus on the process parameter setting in the smelting and continuous casting production process of the high-carbon steel. Such as the method for improving the casting starting effect of the high-carbon steel continuous casting with the publication number CN 106270422A. The method is mainly characterized in that the method that the silico-calcium powder is added into the tundish before the high-carbon steel is continuously cast and poured is adopted, and after the molten steel flows into the tundish, the oxygen in the molten steel reacts with the silico-calcium powder to release heat, so that the temperature drop of the molten steel is reduced, the phenomenon that the molten steel is cooled at the bottom of the tundish is eliminated, and the continuous casting and pouring effect is improved. However, the method has the defects of high operation difficulty, large dust on the site of adding the calcium silicate powder and high casting cost in the actual operation process. Meanwhile, the scheme can only reduce the phenomenon of bottom cold steel, and how to prevent casting and breakout is not involved at all. The invention discloses a high-carbon steel plate blank continuous casting method with application number 201510698849.5, which has the innovative key points that: controlling the casting superheat degree of the high-carbon steel plate blank by adopting a low superheat degree, and controlling the superheat degree to be 10-20 ℃; carrying out low-drawing-speed continuous casting on the high-carbon steel plate blank, and controlling the drawing speed to be 0.9-1.1 m/min; carrying out aerial fog cooling on the high-carbon steel plate blank; and controlling the taper of the crystallizer according to the variable taper. The alkalinity of the covering slag in the crystallizer is controlled to be 0.93-0.99, the melting point of the covering slag is less than or equal to 1050 ℃, and the viscosity of the covering slag is less than or equal to 0.140pa · s. Although the scheme also mentions that the high-carbon steel has large hidden danger of casting failure and breakout due to the solidification characteristic, the scheme does not relate to how to prevent casting breakout of the high-carbon steel and how to optimize the process technology aiming at the solidification characteristic of the high-carbon steel, so that a new scheme is urgently needed to solve the technical problems.
Disclosure of Invention
The invention provides a method for preventing high-carbon steel from casting and breakout in slab continuous casting aiming at the problems in the prior art, and the technical scheme prevents the high-carbon steel from casting and breakout by reasonably setting the continuous casting and casting technological parameters. According to the scheme, the open casting breakout accident caused by insufficient strength of the head billet shell due to solidification characteristics during the open casting of high-carbon steel is well solved by optimizing key continuous casting process parameters such as the carbon content of a sealing dummy ingot material, optimizing sealing dummy ingot parameters, setting the taper of a crystallizer, controlling the superheat degree of molten steel in open casting, optimizing the parameters in the open casting process and the like.
In order to achieve the above object, the present invention provides a method for preventing the open casting of high-carbon steel in slab continuous casting, the method comprising the steps of:
step 1: and setting the taper of the crystallizer before casting before the dummy bar is installed and the dummy bar head is in place, wherein the taper is reduced by 5 percent compared with the target taper. The reason for the high-carbon steel open casting breakout is that the casting resistance is large, the strength of the initial billet shell is not enough (the strength of the initial high-carbon steel billet shell is small), and the strength of the billet shell is not enough to resist the casting friction force, so that the cast breakout accident is caused by the casting breakout. And by reducing the target taper of the crystallizer, the blank drawing friction force can be effectively reduced, so that the potential risk of casting and breakout is reduced.
Step 2: pouring high-carbon steel, guiding ingot and sealing;
2.1 dummy bar head sealing material selection: refractory asbestos fiber material is selected as a filling material between a dummy bar head and a crystallizer copper plate, and common angle steel, scrap iron and springs are used as high-carbon steel casting cooling materials. Because of the low melting point and long solidification characteristic of the high-carbon steel, the scrap iron and the spring used in the technical scheme are selected as special materials for the high-carbon steel, and the carbon content of the two sealing materials is required to be more than 0.40 percent. By selecting the cooling material with the carbon content close to the melting point of the high-carbon steel, the initial blank shell with enough strength can be effectively cooled and quickly formed, and the hidden danger of low initial strength of the high-carbon steel blank shell is solved.
2.2 dummy head seal
2.2.1 the dummy bar is installed in place, and the stop position of the dummy bar head is controlled within the range of 400mm-480mm away from the upper opening of the crystallizer.
2.2.2 controlling the streamline driving roller pressing system to apply a certain pressure to the dummy bar in the streamline of the casting machine, so as to ensure the stability of the dummy bar in the streamline and avoid displacement, wherein the highest pressure of the streamline hydraulic system is generally selected, and the pressure range is selected from 180bar to 250 bar. 2.2.3 cleaning up impurities on the dummy bar head, and ensuring the dummy bar head to be dry by using compressed air.
2.2.4 refractory fiber filling materials are put into the dummy bar head and the inner cambered surface of the crystallizer, and the filling depth is 1/3 of the height of the filling materials. 2.2.5 filling asbestos refractory fibers in the gaps between the crystallizer and the rest three surfaces of the dummy bar head, compacting, and finally compacting the filling material of the inner arc surface.
2.2.6 after the dummy ingot head is plugged by asbestos, iron chips with the carbon content of more than 0.4 percent are spread, the thickness is controlled to be 15-20mm, and the thickness is forbidden to exceed 20 mm. The thickness of the scrap iron is controlled, the aim is to increase the cooling of the molten steel which is initially poured into the crystallizer through the dummy bar head, and the cooling quantity of the bottom is ensured, so that enough blank shell strength is formed.
2.2.7 placing angle steel and a straight steel plate above the scrap iron in sequence, and fixedly placing the angle steel and the straight steel plate on the bevel edge of the dovetail groove of the dummy bar head.
2.2.8 high-carbon steel special springs are transversely placed into the dummy bar head dovetail groove one by one to be flush with the section of the dummy bar head, and the angle steel is tightly attached to the copper plate and the bevel edge of the dovetail groove by the springs to be firmly fixed.
2.2.9 spreading angle steel and straight steel plates along the periphery of the dummy bar head section, and controlling the gap between the angle steel and the straight steel plates to be 3-5 mm.
2.2.10 the use of three layers of high carbon seal spring as the primary cooling material, the high carbon steel spring and the common cooling material has the advantage of effectively forming the reinforcing rib function of the initial blank shell by cold, eliminating the hidden trouble of insufficient strength of the initial blank shell of high carbon steel. The special spring fixing mode for the high-carbon steel comprises the following steps:
2.2.10.1 the long springs are extended to a length about 50mm longer than the width of the cross section of the crystallizer, and the first layer of springs are fully paved along the width direction of the crystallizer.
2.2.10.2 the length specification is spring length with narrow side thickness close, the spring is stretched to be larger than the narrow side thickness of the crystallizer, the second layer of spring is fully paved from the narrow side copper plate along the thickness direction of the crystallizer, the second layer of spring pushes the copper plate tightly and compacts the first layer of spring.
2.2.10.3 the long length springs are elongated to a length about 50mm larger than the width of the cross section of the current crystallizer, and the third layer of springs are fully paved along the width direction of the crystallizer.
And step 3: controlling the casting process;
3.1 the control target range of the superheat degree of molten steel poured on the upper stage is 15-20 degrees. The melting point of the ultra-high carbon steel is low, and the control of low temperature is helpful to form an initial shell with effective strength in the time of initial seedling emergence, so that the occurrence of a pulling crack accident is prevented.
3.2 the preheating temperature of the standby tundish is controlled to be more than 1100 degrees, and after the preheating is finished, the tundish car is controlled to carry the preheated tundish to move to a production pouring position.
3.3 after the ladle is cast, the tonnage of the molten steel injected into the tundish is between 18 and 25 tons, and the flow control system is controlled to inject the molten steel from the crystallizer.
3.4 the time for pouring until the liquid level submerges the bottom of the side hole of the tundish at the water testing port is more than or equal to 60 s. The limitation of the time period is mainly to ensure that the high-carbon steel molten steel can have enough time to be cooled to form a high-strength initial blank shell after being injected into the crystallizer.
3.5 the starting time (emergence time) from the pouring of the molten steel into the crystallizer to the casting machine is controlled between 90 seconds and 110 seconds.
3.6 after meeting the seedling emergence time, adding heating type casting start slag into the crystallizer, and aiming at solving the problem of steel cooling at the liquid level of the crystallizer caused by early-stage enhanced cooling and low-temperature casting.
3.7 after the seedling emergence time is set, starting the casting machine to perform throwing. The casting starting and pulling speed is set to be 0.2m/min, and the initial acceleration slope is set to be 0.4m/min2. The starting pulling speed is properly reduced, so that the instant throwing force is reduced, and the tearing hidden danger is reduced. And 4, step 4: and finishing the whole high-carbon steel breakout-preventing casting process flow.
Compared with the prior art, the invention has the advantages that the technical scheme effectively strengthens the initial shell strength after the high-carbon steel is cast, the high-carbon steel casting breakout accident is obviously improved, 1.86 ten thousand tons of high-carbon steel is produced in the plum steel plant in the experimental stage in an accumulated way, the casting breakout accident is performed for 18 times, and the occurrence of '0' is realized.
Drawings
FIG. 1: a high-carbon steel sealed dummy ingot three-layer spring schematic diagram;
FIG. 2 is a schematic flow chart of the present invention.
In the figure: 1. three layers of springs, 2, a crystallizer, 3 and a dummy bar head.
The specific implementation mode is as follows:
for the purpose of promoting an understanding of the present invention, reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings.
Example 1: referring to fig. 1, a method for preventing breakout of a slab continuous cast high carbon steel, the method comprising the steps of:
step 1: and setting the taper of the crystallizer before casting before the dummy bar is installed and the dummy bar head is in place, wherein the taper is reduced by 5 percent compared with the target taper. The reason for the high-carbon steel open casting breakout is that the casting resistance is large, the strength of the initial billet shell is not enough (the strength of the initial high-carbon steel billet shell is small), and the strength of the billet shell is not enough to resist the casting friction force, so that the cast breakout accident is caused by the casting breakout. And by reducing the target taper of the crystallizer, the blank drawing friction force can be effectively reduced, so that the potential risk of casting and breakout is reduced.
Step 2: pouring high-carbon steel, guiding ingot and sealing;
2.1 dummy bar head sealing material selection: refractory asbestos fiber material is selected as a filling material between a dummy bar head and a crystallizer copper plate, and common angle steel, scrap iron and springs are used as high-carbon steel casting cooling materials. Because of the low melting point and long solidification characteristic of the high-carbon steel, the scrap iron and the spring used in the technical scheme are selected as special materials for the high-carbon steel, and the carbon content of the two sealing materials is required to be more than 0.40 percent. By selecting the cooling material with the carbon content close to the melting point of the high-carbon steel, the initial blank shell with enough strength can be effectively cooled and quickly formed, and the hidden danger of low initial strength of the high-carbon steel blank shell is solved.
2.2 sealing the dummy bar head;
2.2.1 installing the dummy bar in place, and controlling the stop position of the dummy bar head within the range of 400mm-480mm away from the upper opening of the crystallizer;
2.2.2 controlling the streamline driving roller pressing system to apply a certain pressure to the dummy bar in the streamline of the casting machine, so as to ensure the stability of the dummy bar in the streamline and avoid displacement, wherein the highest pressure of the streamline hydraulic system is generally selected, and the pressure range is selected from 180bar to 250 bar. 2.2.3 cleaning up sundries on the dummy bar head, and ensuring the dummy bar head to be dry by using compressed air;
2.2.4 refractory fiber filling materials are put into the dummy bar head and the inner cambered surface of the crystallizer, and the filling depth is 1/3 of the height of the filling materials. 2.2.5 filling asbestos refractory fibers in all gaps between the crystallizer and the rest three surfaces of the dummy ingot head and compacting, and finally compacting the filling material of the inner cambered surface;
2.2.6 after the dummy ingot head is plugged by asbestos, iron chips with the carbon content of more than 0.4 percent are spread, the thickness is controlled to be 15-20mm, and the thickness is forbidden to exceed 20 mm. The thickness of the scrap iron is controlled, the aim is to increase the cooling of the molten steel which is initially poured into the crystallizer through the dummy bar head, and the cooling quantity of the bottom is ensured, so that enough blank shell strength is formed.
2.2.7 placing angle steel and a straight steel plate above the scrap iron in sequence, and fixedly placing the angle steel and the straight steel plate on the bevel edge of the dovetail groove of the dummy bar head.
2.2.8 high-carbon steel special springs are transversely placed into the dummy bar head dovetail groove one by one to be flush with the section of the dummy bar head, and the angle steel is tightly attached to the copper plate and the bevel edge of the dovetail groove by the springs to be firmly fixed.
2.2.9 spreading angle steel and straight steel plates along the periphery of the dummy bar head section, and controlling the gap between the angle steel and the straight steel plates to be 3-5 mm.
2.2.10 the use of three layers of high carbon seal spring as the primary cooling material, the high carbon steel spring and the common cooling material has the advantage of effectively forming the reinforcing rib function of the initial blank shell by cold, eliminating the hidden trouble of insufficient strength of the initial blank shell of high carbon steel. The special spring fixing mode for the high-carbon steel comprises the following steps:
2.2.10.1 elongating the long springs to a length greater than the width of the cross section of the crystallizer by about 50mm, and spreading a first layer of springs along the width direction of the crystallizer;
2.2.10.2 the length specification is spring length with narrow side thickness close to that of the crystallizer, the spring is stretched to be larger than the narrow side thickness of the crystallizer, a second layer of springs is paved from the narrow side copper plate along the thickness direction of the crystallizer, the second layer of springs tightly pushes the copper plate and compacts the first layer of springs.
2.2.10.3 the long length springs are elongated to a length about 50mm larger than the width of the cross section of the current crystallizer, and the third layer of springs are fully paved along the width direction of the crystallizer.
And step 3: controlling the casting process;
3.1 the control target range of the superheat degree of molten steel poured on the upper stage is 15-20 degrees. The ultra-high carbon steel has low melting point, and the control of low temperature is favorable for forming an initial blank shell with effective strength in the casting seedling emergence time, so that the occurrence of a pulling crack accident is prevented.
3.2 the preheating temperature of the standby tundish is controlled to be more than 1100 degrees, and after the preheating is finished, the tundish car is controlled to carry the preheated tundish to move to a production pouring position.
3.3 after the ladle is cast, the tonnage of the molten steel injected into the tundish is between 18 and 25 tons, and the flow control system is controlled to inject the molten steel from the crystallizer.
3.4 the time for pouring until the liquid level submerges the bottom of the side hole of the tundish at the water testing port is more than or equal to 60 s. The limitation of the time period is mainly to ensure that the high-carbon steel molten steel can have enough time to be cooled to form a high-strength initial blank shell after being injected into the crystallizer.
3.5 the starting time (emergence time) from the pouring of the molten steel into the crystallizer to the casting machine is controlled between 90 seconds and 110 seconds.
3.6 after meeting the seedling emergence time, adding heating type casting start slag into the crystallizer, and aiming at solving the problem of steel cooling at the liquid level of the crystallizer caused by early-stage enhanced cooling and low-temperature casting.
3.7 after the seedling emergence time is set, starting the casting machine to perform throwing. The casting starting and pulling speed is set to be 0.2m/min, and the initial acceleration slope is set to be 0.4m/min2. The starting pulling speed is properly reduced, so that the instant blank pulling force is reduced, and the tearing hidden danger is reduced. And 4, step 4: whole high-carbon steel anti-leakage steel casting process flow knotAnd (4) bundling.
The specific embodiment is as follows:
in the experimental stage, the thickness of a crystallizer of an enterprise is 230mm, the width of the crystallizer is 1200mm, high-carbon steel with the carbon content exceeding 0.65 percent is produced, and in order to prevent casting and breakout, the method is implemented according to the technical scheme and mainly comprises the following steps:
2.1 dummy bar head sealing material selection: refractory asbestos fiber material is selected as a filling material between a dummy bar head and a crystallizer copper plate, and common angle steel, scrap iron and springs are used as high-carbon steel casting cooling materials. Because of the low melting point of the high-carbon steel and the long solidification characteristic of the solidification interval, the scrap iron and the spring used in the technical scheme are selected as special materials for the high-carbon steel, the carbon content of the scrap iron is 0.56 percent, and the carbon content of the high-carbon spring is 0.48 percent. 2.2 dummy head seal
2.2.1 the dummy bar is installed in place, and the stop position of the dummy bar head is controlled to be 450mm away from the upper opening of the crystallizer.
2.2.2 controlling the streamline driving roller pressing system to apply a certain pressure to the dummy bar in the streamline of the casting machine, so as to ensure the stability of the dummy bar in the streamline and avoid displacement, wherein the highest pressure of the streamline hydraulic system is generally selected, and the pressure is 200 bar.
2.2.3 cleaning up impurities on the dummy bar head, and ensuring the dummy bar head to be dry by using compressed air.
2.2.4 refractory fiber filling materials are put into the dummy bar head and the inner cambered surface of the crystallizer, and the filling depth is 1/3 of the height of the filling materials. 2.2.5 filling all gaps between the crystallizer and the rest three surfaces of the dummy bar head with asbestos refractory fibers and compacting, and finally compacting the filling material of the inner cambered surface.
2.2.6 after the dummy ingot head is plugged by asbestos, iron chips with the carbon content of 0.56 percent are spread, the thickness of the iron chips is controlled to be 18mm, and the thickness of the iron chips is forbidden to exceed 20 mm. The thickness of the scrap iron is controlled, the aim is to increase the cooling of the molten steel which is initially poured into the crystallizer through the dummy bar head, and the cooling quantity of the bottom is ensured, so that enough blank shell strength is formed.
2.2.7 placing angle steel and a straight steel plate above the scrap iron in sequence, and fixedly placing the angle steel and the straight steel plate on the bevel edge of the dovetail groove of the dummy bar head.
2.2.8 high-carbon steel special springs are transversely placed into the dummy bar head dovetail groove one by one to be flush with the section of the dummy bar head, and the angle steel is tightly attached to the copper plate and the bevel edge of the dovetail groove by the springs to be firmly fixed.
2.2.9 spreading angle steel and straight steel plates along the periphery of the dummy bar head section, and controlling the gap between the angle steel and the straight steel plates to be 3-5 mm.
2.2.10 the use of three layers of high carbon seal spring as the primary cooling material, the high carbon steel spring and the common cooling material has the advantage of effectively forming the reinforcing rib function of the initial blank shell by cold, eliminating the hidden trouble of insufficient strength of the initial blank shell of high carbon steel. The special spring fixing mode for the high carbon steel is as follows (see figure 1):
2.2.10.1 the long specification spring is elongated to a length about 50mm larger than the width of the cross section of the current crystallizer, the length of the spring is 1250mm when the current specification is 1200mm, and the first layer of spring is fully paved along the width direction of the crystallizer.
2.2.10.2 the length specification is chosen to be the length of the spring with the narrow side thickness close to that of the spring, and the spring is stretched to be larger than the thickness of the narrow side of the crystallizer, namely, the length of the spring is larger than 230 mm. And a second layer of springs are fully paved from the narrow-edge copper plate along the thickness direction of the crystallizer, and the second layer of springs tightly push the copper plate and compact the first layer of springs.
2.2.10.3 the long length spring is elongated to a length about 50mm larger than the width of the cross section of the crystallizer, the current specification is 1200mm, the length of the spring is 1250mm, and the third layer of spring is fully paved along the width direction of the crystallizer.
3.1 the control target range of the superheat degree of molten steel poured on the upper stage is 15-20 degrees. The liquidus temperature of the high-carbon steel at this time is 1469 degrees, and the superheat degree of the molten steel for casting is controlled to 1487 degrees.
3.2 the preheating temperature of the standby tundish is controlled at 1320 degrees, and after the preheating is finished, the tundish car is controlled to carry the preheated tundish to move to a production pouring position.
3.3 after the ladle is cast, the tonnage of the molten steel injected into the tundish is 20 tons, and the flow control system is controlled to inject the molten steel from the crystallizer.
3.4 the time for pouring until the liquid level submerges the bottom of the side hole of the tundish at the water testing port is more than or equal to 60 s. The limitation of the time period is mainly to ensure that the high-carbon steel molten steel can have enough time to be cooled to form a high-strength initial blank shell after being injected into the crystallizer.
3.5 the starting time (emergence time) from the time when the molten steel is poured into the crystallizer to the time when the casting machine starts is controlled to be 105 seconds.
3.6 after meeting the seedling emergence time, adding heating type casting start slag into the crystallizer, and aiming at solving the problem of steel cooling at the liquid level of the crystallizer caused by early-stage enhanced cooling and low-temperature casting.
3.7 after the seedling emergence time is set, starting the casting machine to perform throwing. The casting starting and throwing speed is set to be 0.2m/min, and the initial acceleration slope is set to be 0.4m/min2. The starting pulling speed is properly reduced, so that the instant blank pulling force is reduced, and the tearing hidden danger is reduced.
And 4, finishing the whole high-carbon steel breakout-preventing casting process flow.
It should be noted that the above-mentioned embodiments are not intended to limit the scope of the present invention, and all equivalent modifications and substitutions based on the above-mentioned technical solutions are within the scope of the present invention as defined in the claims.
Claims (5)
1. A method for preventing cast-on breakout of high-carbon steel in slab continuous casting is characterized by comprising the following steps:
step 1: loading a dummy bar;
step 2: pouring high-carbon steel, guiding ingot and sealing;
and step 3: controlling the casting process;
and 4, step 4: and finishing the whole high-carbon steel breakout-preventing casting process flow.
2. The method for preventing cast-on breakout of a slab continuous casting high carbon steel according to claim 1, wherein the step 1: the dummy bar is installed as follows: the taper of the crystallizer before casting is set before the dummy bar head is in place, and is reduced by 5 percent compared with the target taper setting.
3. The method for preventing cast-on breakout of a slab continuous casting high carbon steel according to claim 2, wherein the step 2: the high-carbon steel casting ingot guiding seal comprises the following concrete steps:
2.1 dummy bar head sealing material selection: refractory asbestos fiber material is selected as a filling material between a dummy bar head and a crystallizer copper plate, common angle steel, scrap iron and a spring are used as high-carbon steel casting cooling materials, and the carbon content of two sealing materials of the scrap iron and the spring is more than 0.40 percent;
2.2 sealing the dummy bar head;
2.2.1 installing the dummy bar in place, and controlling the stop position of the dummy bar head within the range of 400mm-480mm away from the upper opening of the crystallizer;
2.2.2 controlling a streamline driving roller pressing-down system, applying certain pressure to an dummy bar in a streamline of the casting machine, ensuring the dummy bar to be stable in the streamline and avoiding displacement, selecting the highest pressure of a system of a streamline hydraulic system, and selecting the pressure range to be 180-250 bar;
2.2.3 cleaning up sundries on the dummy bar head, and ensuring the dummy bar head to be dry by using compressed air;
2.2.4 refractory fiber filling materials are firstly put into the dummy bar head and the inner cambered surface of the crystallizer, and the filling depth is 1/3 of the height of the filling materials;
2.2.5 filling asbestos refractory fibers in all gaps between the crystallizer and the rest three surfaces of the dummy ingot head and compacting, and finally compacting the filling material of the inner cambered surface;
2.2.6 after the dummy ingot head is plugged by asbestos, iron chips with the carbon content of more than 0.4 percent are spread, the thickness of the iron chips is controlled to be 15-20mm, and the thickness of the iron chips is forbidden to exceed 20 mm;
2.2.7 placing angle steel and a straight steel plate above the scrap iron in sequence, and fixedly placing the angle steel and the straight steel plate on the bevel edge of the dovetail groove of the dummy bar head;
2.2.8, high-carbon steel special springs are transversely placed into the dummy bar head dovetail groove one by one to be flush with the section of the dummy bar head, and the angle steel is tightly attached to the copper plate and the bevel edge of the dovetail groove by the springs to be firmly fixed;
2.2.9 paving angle steel and straight steel plates around the section of the dummy bar head, and controlling the gap between the angle steel and the straight steel plates to be 3-5 mm;
2.2.10 use three layers of high carbon seal springs as primary cooling material.
4. The method for preventing cast-on breakout of slab continuous casting high carbon steel according to claim 2, characterized in that the step 2.2.10 uses three layers of high carbon sealing springs as primary cooling material:
the method comprises the following specific steps:
the special spring fixing mode for the high-carbon steel comprises the following steps:
2.2.10.1 elongating the long springs to a length greater than the width of the cross section of the crystallizer by about 50mm, and spreading a first layer of springs along the width direction of the crystallizer;
2.2.10.2 selecting spring length with narrow side thickness close to that of the crystallizer, stretching the spring to be larger than the narrow side thickness of the crystallizer, spreading a second layer of spring from the narrow side copper plate along the thickness direction of the crystallizer, tightly pushing the copper plate by the second layer of spring and compacting the first layer of spring;
2.2.10.3 the long length springs are elongated to a length about 50mm larger than the width of the cross section of the current crystallizer, and the third layer of springs are fully paved along the width direction of the crystallizer.
5. The method for preventing the open casting breakout of the slab continuous casting high-carbon steel according to claim 3, wherein the step 3 is a process control of the open casting process, and specifically comprises the following steps:
3.1 the control target range of the superheat degree of molten steel poured on the upper stage is 15-20 degrees;
3.2 the preheating temperature of the standby tundish is controlled to be more than 1100 degrees, and after the preheating is finished, the tundish car is controlled to carry the preheated tundish to move to a production pouring position;
3.3 after the ladle is cast, controlling the flow control system to start to inject molten steel from the crystallizer, wherein the tonnage of the molten steel injected into the tundish is between 18 and 25 tons;
3.4 the time for pouring until the liquid level of the molten steel submerges the bottom of the side hole of the water testing port is more than or equal to 60s,
3.5 the starting time (seedling emergence time) from the step of pouring molten steel into the crystallizer to the casting machine is controlled to be 90-110 seconds;
3.6 after the seedling emergence time is met, adding heating type casting slag into the crystallizer,
3.7 after the seedling emergence time is set, starting the casting machine to perform blank drawing, setting the casting starting blank drawing speed to be 0.2m/min, and setting the initial acceleration slope to be 0.4m/min2。
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