CN117300086A - Method for pre-judging casting blank longitudinal crack risk before production and continuous casting method based on pre-production - Google Patents
Method for pre-judging casting blank longitudinal crack risk before production and continuous casting method based on pre-production Download PDFInfo
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- 238000005266 casting Methods 0.000 title claims abstract description 133
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- 238000009749 continuous casting Methods 0.000 title claims abstract description 53
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- 229910000831 Steel Inorganic materials 0.000 claims description 60
- 239000010959 steel Substances 0.000 claims description 60
- 239000002893 slag Substances 0.000 claims description 33
- 229910052799 carbon Inorganic materials 0.000 claims description 30
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 25
- 230000000903 blocking effect Effects 0.000 claims description 23
- 230000004907 flux Effects 0.000 claims description 21
- 238000011156 evaluation Methods 0.000 claims description 10
- 238000005507 spraying Methods 0.000 claims description 9
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 5
- 229910000746 Structural steel Inorganic materials 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims description 4
- 230000007547 defect Effects 0.000 abstract description 27
- 230000000694 effects Effects 0.000 abstract description 3
- 239000007921 spray Substances 0.000 description 28
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 239000000498 cooling water Substances 0.000 description 8
- 238000007689 inspection Methods 0.000 description 8
- 238000005336 cracking Methods 0.000 description 7
- 238000006073 displacement reaction Methods 0.000 description 7
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- 238000005096 rolling process Methods 0.000 description 7
- 239000012535 impurity Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 238000007796 conventional method Methods 0.000 description 5
- 238000011160 research Methods 0.000 description 5
- 238000001816 cooling Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 239000002436 steel type Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 3
- 230000005499 meniscus Effects 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910000621 Ultra-high-carbon steel Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
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- 238000004458 analytical method Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000035876 healing Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000005457 optimization 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
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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
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Abstract
The invention discloses a method for pre-judging casting blank longitudinal crack risk before production and a continuous casting method based on pre-judging, wherein the state of casting machine equipment is rated, and the rating rules are respectively evaluated from A, B, C, D four grades; the crystallizer vibrates: the longitudinal deflection is < + -0.2 mm, and the transverse deflection is < + -0.05 mm, which is grade A; the longitudinal deflection is less than or equal to +/-0.2 mm, and the transverse deflection is less than or equal to +/-0.05 mm, and the transverse deflection is less than or equal to +/-0.2 mm, which is B grade; the longitudinal deflection is less than or equal to +/-0.25 mm and the transverse deflection is less than or equal to +/-0.2 mm, and the C level is the same; the D level is that the longitudinal deflection is less than or equal to +/-0.25 mm and the transverse deflection is less than or equal to +/-0.3 mm. The method can effectively avoid the generation of longitudinal crack defects on the surface of the casting blank and the risk of the casting blank flowing into the next working procedure by establishing the equipment rating rule for pre-production, improves the surface quality of the casting blank on the basis of not increasing the production cost, and achieves the effects of high efficiency and high quality.
Description
Technical Field
The invention belongs to the technical field of continuous casting, and particularly relates to a method for pre-judging casting blank longitudinal crack risk before production and a continuous casting method based on the pre-judging before production.
Background
Casting blank longitudinal cracking is a common surface defect in the production process of continuous casting slabs, and occurs on the surface and subsurface of the casting blank. Aiming at the continuous casting billet longitudinal crack defect, students at home and abroad also do a great deal of research, the root of the research is initiated in a crystallizer, and the secondary cooling zone is expanded and deteriorated. The longitudinal cracks on the surface of the casting blank can be found through thermal inspection or cold inspection of the casting blank, can be eliminated through finishing manual gun pulling treatment, does not influence subsequent rolling, but can cause iron and steel material loss and increase of labor cost, and meanwhile, planning and arrangement are also influenced; the subsurface cracks of the casting blank, which are also called subcutaneous cracks, are difficult to find when the casting blank is inspected, are very easy to flow into the next working procedure, inherit for hot rolling and cold rolling, cause the linear quality defect of the surface of the steel coil, and seriously influence the product yield and the contract redemption of key customers.
Casting blank longitudinal cracking is a typical defect generated in a crystallizer, and is reflected on the casting blank, the casting blank is shorter than a few millimeters, the casting blank can be 3-4 meters long, and serious defects even penetrate through the whole surface of the casting blank. The root cause of the casting blank longitudinal cracking is that in the meniscus area of the crystallizer, the molten steel is subjected to volume shrinkage in the process of solidifying to form a blank shell, so that an air gap is generated between the blank shell and the wall of the crystallizer, the thermal resistance is increased, and the heat transfer efficiency is reduced. Because the air gap generated in the crystallizer is nonuniform, the uniformity of heat transfer from the blank shell to the crystallizer is affected, the thickness of the blank shell and the internal stress distribution of the blank shell are further uneven, and fine microcracks are formed at the weak part of the blank shell under the action of the ferrostatic pressure. If the precision state of the casting machine is poor, the cooling intensity of the casting blank entering the secondary cooling area is uneven, and the micro cracks formed by the crystallizer can be further expanded and extended, so that the longitudinal crack defect on the surface of the casting blank is formed. Therefore, the casting blank longitudinal cracking prevention is closely related to the casting powder performance, the heat flow of the crystallizer, the superheat degree of molten steel, the constant-pull-rate casting, the immersion nozzle insertion depth, the abrasion of the surface of a copper plate of the crystallizer and the like, and the precision of casting equipment and the secondary cooling strength are also important to pay attention.
At present, research at home and abroad mainly analyzes and researches the cause of the longitudinal crack defect on the surface of a casting blank and rapidly identifies on-line detection, but in order to avoid the longitudinal crack risk, classification production of different steel grades by combining a casting machine arc line and a spraying state classification, pre-production fresh judgment is reported.
The Chinese patent application with publication number of CN114346193A discloses a process method for preventing longitudinal cracks and bonding steel leakage in the starting process of a slab caster, which reduces the longitudinal cracks and steel leakage rate of casting blanks by controlling the pulling rate after the emergence of a tundish, and automatically sets the pulling rate to 0.28 m/min; after the pull speed reaches 0.70m/min, the pull speed is controlled to be increased by 40 seconds to be increased by 0.03m/min to the normal pull speed. The method is not related to other technological parameters affecting longitudinal fracture.
The Chinese patent application with publication number of CN101985166A discloses a continuous casting slab longitudinal crack steel leakage prediction method, which is characterized in that analysis and judgment are carried out according to temperature data detected by a thermocouple, the transverse temperature difference, the longitudinal temperature change rule and the amplitude of the thermocouple are comprehensively considered, and the occurrence of longitudinal crack is determined by combining the characteristics of steel types, so that the limitation of single transverse temperature difference or single longitudinal thermocouple temperature change rate is overcome; however, no study is made on the relevant influencing factors such as the mold flux performance, the taper of the crystallizer, the steady-state control of the liquid level and the like.
The Chinese patent application with publication number of CN113584254A discloses a method for reducing the incidence of longitudinal cracking of an ultra-high carbon steel casting blank, which reduces the incidence of longitudinal cracking of the ultra-high carbon steel casting blank by controlling the superheat degree and H content of molten steel after LF refining and controlling the alkalinity, viscosity and melting temperature of protective slag; but does not involve optimization of parameters such as mold vibration, mold taper, segment conditions, etc.
The Chinese patent application with publication number of CN 115586215A discloses a continuous casting billet surface longitudinal crack logic judging method based on temperature characteristics, which comprises the steps of establishing a continuous casting billet surface longitudinal crack sample database; calculating a thermocouple temperature characteristic value of the continuous casting crystallizer; acquiring a temperature characteristic value range of the longitudinal cracks on the surface of the continuous casting blank, and rapidly and accurately identifying the longitudinal cracks on the surface of the continuous casting blank; the method only provides an effective method for online detection of the longitudinal cracks on the surface of the continuous casting billet, and corresponding research on control, evaluation and prediction of the longitudinal cracks is not carried out.
The Chinese patent application with publication number of CN109136782A discloses a control method for longitudinal crack of 1000MPa grade cold-rolled strip steel casting blank, which controls cracks with depth less than or equal to 1mm generated in a crystallizer in aspects of casting powder of the continuous casting crystallizer, taper of the crystallizer, vibration mode, heat flow density and the like, and does not analyze the control after the casting powder is discharged from the crystallizer.
Control of casting blank surface longitudinal crack of No. 4 slab caster (album of paper of steel-making continuous casting annual meeting in the eleven provinces of the bead-making triangle in 2007, F09 period of 2007, pages 264-267), which comprehensively analyze and study parameters affecting longitudinal crack from the aspects of molten steel composition, casting powder performance, molten steel temperature, crystallizer vibration, crystallizer liquid level fluctuation control, sector state and the like.
Disclosure of Invention
The invention aims to provide a method for pre-judging casting blank longitudinal crack risk before delivery; the invention also provides a continuous casting method based on the pre-production judgment so as to improve the surface quality of the casting blank.
In order to solve the technical problems, the invention adopts the following technical scheme: rating the state of the casting machine equipment, and respectively evaluating the rating rules from four grades A, B, C, D;
the crystallizer vibrates: the longitudinal deflection is < + -0.2 mm, and the transverse deflection is < + -0.05 mm, which is grade A; the longitudinal deflection is less than or equal to +/-0.2 mm, and the transverse deflection is less than or equal to +/-0.05 mm, and the transverse deflection is less than or equal to +/-0.2 mm, which is B grade; the longitudinal deflection is less than or equal to +/-0.25 mm and the transverse deflection is less than or equal to +/-0.2 mm, and the C level is the same; the D level is that the longitudinal deflection is less than or equal to +/-0.25 mm and less than or equal to +/-0.3 mm, and the transverse deflection is less than or equal to +/-0.2 mm;
outer arc deviation of the sector: all points are < + -0.5 mm as class A; the deviation of 1 to 3 points of the camber line with the length of plus or minus 0.5mm is less than or equal to plus or minus 1.0mm, and the deviation of other points with the length of minus or plus 0.5mm is grade B; the deviation of 4 to 5 points of the outer arc line with the length of plus or minus 0.5mm is less than plus or minus 1.0mm, and the deviation of other points with the length of plus or minus 0.5mm is C grade; the deviation of 6 to 8 points of the outer arc line with the length of plus or minus 0.5mm is less than plus or minus 1.0mm, the deviation of not more than 2 points is more than or equal to plus or minus 1.0mm, and the other deviations are all less than or equal to plus or minus 0.5mm and are grade D;
spraying state: the blocking rate of the straightening section before continuous casting and blank drawing is less than or equal to 3 percent and is A grade; the blocking rate is more than 3 percent and less than or equal to 5 percent and is B grade; the blocking rate is more than 5 percent and less than or equal to 8 percent and is C grade; 8% < blocking rate grade D;
the equipment rating is pre-judged to be a short plate, and the worst conditions of the vibration of the crystallizer, the deviation of the outer arc line of the sector section and the spraying state are used as standards to pre-judge the casting blank surface longitudinal crack risk: the comprehensive evaluation A is the minimum risk of longitudinal fracture, the comprehensive evaluation B is the second grade and the comprehensive evaluation C is the maximum risk of longitudinal fracture.
The continuous casting method adopts the method to pre-judge before production: the casting machine equipment comprehensively evaluates the grade A to produce sensitive steel with carbon equivalent of more than or equal to 0.3 and less than 0.6; comprehensively evaluating the acid-washed steel and structural steel with carbon equivalent of 0.1-0.3 in the class B; and comprehensively evaluating the grade C and grade D to produce common ultra-low carbon steel and low carbon steel.
Further, the pulling speed of the continuous casting is controlled: after starting, the mixture passes through the lower opening of the crystallizer at the pulling speed of 0.4m/min and then passes through the lower opening of the crystallizer at the pulling speed of 0.3-0.4 m/min 2 Accelerating to 0.8m/min, keeping for 2-3 min and then using 0.2m/min 2 Is increased to the target pull speed.
Further, in the continuous casting process, controlling the thickness of the slag layer to be 8-15 mm, and calculating the consumption of the protective slag according to a formula (I);
Q＝0.8(1/A 0.3 )(60/f)(nV 2 ) -0.5 +0.13 (Ⅰ)
wherein Q: consumption of mold flux, kg/m 2 The method comprises the steps of carrying out a first treatment on the surface of the A: the amplitude of the vibration of the crystallizer is mm; f: frequency of vibration of the crystallizer, times/min; n: the viscosity of the covering slag, pa.s; v: target pulling speed, m/min.
Further, in the continuous casting process, the heat flow ratio of the wide side to the narrow side of the crystallizer is controlled to be 1.1-1.25, and the superheat degree of molten steel is controlled to be 15-30 ℃.
Furthermore, the crystallizer vibration in the continuous casting process adopts a smooth sawtooth wave negative slip mode, the deflection rate is 60%, the smoothness is 25%, the negative slip time is controlled to be 0.12-0.15 s, and the negative slip time rate is controlled to be 39-43%.
The beneficial effects of adopting above-mentioned technical scheme to produce lie in: the invention can rapidly and effectively judge the risk of longitudinal cracking on the surface of the casting blank by establishing the equipment rating rule to perform pre-production judgment, and provides basis for further production.
The continuous casting method of the invention can effectively avoid the generation of longitudinal crack defects on the surface of the casting blank and the risk of the casting blank flowing into the next procedure by establishing the equipment rating rule for pre-production judgment, and improves the surface quality of the casting blank on the basis of not increasing the production cost, thereby achieving the effects of high efficiency and high quality. In particular, steady-state control such as molten steel carbon equivalent, crystallizer vibration, spraying state, sector segment precision, crystallizer cooling water inlet and outlet temperature difference, quick casting start-up expansion and pull speed, molten steel superheat degree and the like is integrated, so that the occurrence of casting blank surface longitudinal crack risks can be further avoided, and the casting blank surface quality is improved.
Drawings
The invention will be described in further detail with reference to the drawings and the detailed description.
FIG. 1 is a schematic view of a casting blank surface longitudinal crack defect obtained by a conventional method;
FIG. 2 is a schematic view of the surface longitudinal crack defect of a strip steel obtained by a conventional method;
FIG. 3 is a schematic view showing the surface appearance of a cast slab obtained in example 2 of the method of the present invention;
FIG. 4 is a schematic view of the surface of a strip obtained in example 2 of the method of the present invention.
Detailed Description
Casting billet longitudinal cracks are generated in the crystallizer, and if the state of the casting machine is poor, the casting billet longitudinal cracks are further deteriorated after exiting the crystallizer. Considering that the alloy compositions of different steel types are different, the carbon equivalent in the molten steel is different, the thermal expansion and shrinkage stress generated in the solidification process of the blank shell in the crystallizer is different, and the crack sensitivity is different; when the equipment state after the crystallizer is abnormal, crack defects can be continuously expanded. Based on the thought, the method for prejudging the casting blank longitudinal crack risk before production establishes a set of rating rules of casting machine equipment by rating the state of the casting machine equipment, wherein the rating rules are respectively evaluated from A, B, C, D grades, wherein A represents that the state of the equipment is best, B represents that the state of the equipment is good, C represents that the state of the equipment is general, and D represents that the state of the equipment is poor; the evaluation procedure was as follows:
(1) The crystallizer vibrates: the longitudinal deflection is < + -0.2 mm, and the transverse deflection is < + -0.05 mm, which is grade A; the longitudinal deflection is less than or equal to +/-0.2 mm, and the transverse deflection is less than or equal to +/-0.05 mm, and the transverse deflection is less than or equal to +/-0.2 mm, which is B grade; the longitudinal deflection is less than or equal to +/-0.25 mm and the transverse deflection is less than or equal to +/-0.2 mm, and the C level is the same; the D level is that the longitudinal deflection is less than or equal to +/-0.25 mm and the transverse deflection is less than or equal to +/-0.3 mm. The longitudinal deflection is less than or equal to +/-0.2 mm, and is understood to be that the longitudinal position point of the crystallizer when not vibrating is taken as a reference center, and the deflection distance in the two longitudinal directions is within 0.2 mm; the transverse deflection is less than or equal to +/-0.05 mm, and is understood to be taking a transverse position point when the crystallizer does not vibrate as a reference center, and the distance of deflection in the transverse direction is within 0.05mm or less; other distance ranges are also understood in this logic.
(2) Outer arc deviation of the sector: the casting machine has 17 segments in total, and each segment has 4 points; all points of the outer arc line are < +/-0.5 mm as class A; the deviation of 1 to 3 points of the camber line with the length of plus or minus 0.5mm is less than or equal to plus or minus 1.0mm, and the deviation of other points with the length of minus or plus 0.5mm is grade B; the deviation of 4 to 5 points of the outer arc line with the length of plus or minus 0.5mm is less than plus or minus 1.0mm, and the deviation of other points with the length of plus or minus 0.5mm is C grade; the deviation of 6-8 points of the outer arc line less than or equal to +/-0.5 mm is less than or equal to +/-1.0 mm, the deviation of less than or equal to 2 points is more than or equal to +/-1.0 mm, and the other deviations are all less than or equal to +/-0.5 mm and are grade D. The deviation of 1 to 3 points of the outer arc line with the length of plus or minus 0.5mm is less than or equal to 1 to 3 points with the length of plus or minus 1.0mm, which is understood that the distance that 1 to 3 points deviate to two directions is more than or equal to 0.5mm and is not more than 1.0mm by taking the original position of the outer arc line of the sector section as the reference center; other deviation ranges are likewise understood in this logic.
(3) Spraying state: the spraying state is normally in a scattered mist state, the blocking phenomenon is in a poor state, and 1-8 sections before the straightening section are blank shell sensitive areas in the continuous casting and blank drawing process; the blockage rate before the straightening section is less than or equal to 3 percent and is grade A; the blocking rate before 3 percent is less than or equal to 5 percent of the straightening section is B grade; the blocking rate before the straightening section is less than or equal to 8 percent and is C grade; the blockage rate before the straightening section is more than 8 percent and is grade D.
(4) The equipment rating is pre-judged to be a short plate, and the worst conditions of the vibration of the crystallizer, the deviation of the outer arc line of the sector section and the spraying state are used as standards to pre-judge the casting blank surface longitudinal crack risk: the comprehensive evaluation A is the minimum risk of longitudinal fracture, the second is the B and the third is the C, and the comprehensive evaluation D is the maximum risk of longitudinal fracture.
The continuous casting method based on the prenatal pre-judgment adopts the method to carry out the prenatal pre-judgment and comprises the following process control: (1) According to the pre-production judgment result, the casting machine equipment comprehensively evaluates the grade A, so that the casting machine is used for producing sensitive steel with carbon equivalent of more than or equal to 0.3 and less than or equal to 0.6, including high-strength steel with the grade of 780MP and pipeline steel with the grade of more than or equal to X65; comprehensively evaluating the grade B, wherein the casting machine is used for producing acid-washed steel and structural steel with carbon equivalent of more than or equal to 0.1 and less than 0.3 and containing trace alloy; and comprehensively evaluating the grade C and grade D to produce common ultralow carbon steel, low carbon steel and other steel types which are not easy to longitudinally crack. The carbon equivalent calculation formula is as follows: ceq=c+mn/6+ (cr+mo+v)/5+ (ni+cu)/15.
(2) The quick expansion and pulling speed control is carried out at the initial stage of continuous casting, namely, the continuous casting passes through the lower opening of the crystallizer at 0.4m/min after starting; then 0.3 to 0.4m/min 2 The acceleration rate rises to 0.8m/min; after 2-3 minutes, at 0.2m/min 2 The speed increasing reference is lifted to the target pulling speed so as to shorten the unsteady control time of the expanding pulling speed; finally, the target pulling speed pouring control is kept, and the constant pulling speed is kept at best; the target pulling speed is preferably 0.9-1.6 m/min. The control process shortens the unsteady control time of the expansion and pulling speed by carrying out quick expansion and pulling at the initial stage of continuous casting, and reduces the occurrence of the condition of uneven thickness of the shell of the blank shell and air gap generation in the unsteady control time of the expansion and pulling speed.
(2) The mold flux is added for a few times, duty and even, namely, the mold flux is added once for 5 to 8 minutes, and the addition amount of each time is 4 to 7kg, and the mold flux is evenly dispersed on the surface of the molten steel of the mold, so that the black surface operation is ensured, namely, the surface of the molten steel is not exposed, and the phenomena of local reddening and steel bloom are avoided. The casting process does not pick slag strips, the steady casting of the liquid level of the crystallizer is kept, the thickness of a slag layer is ensured to be 8-15 mm, the consumption of the protective slag is calculated according to a formula (I), and the consumption is preferably controlled to be 0.35-0.6 kg/t;
Q＝0.8(1/A 0.3 )(60/f)(nV 2 ) -0.5 +0.13 (Ⅰ)
in formula (I), Q: consumption of mold flux, kg/m 2 The method comprises the steps of carrying out a first treatment on the surface of the A, A is as follows; the amplitude of the vibration of the crystallizer is mm; f: frequency of vibration of the crystallizer, times/min; n: the viscosity of the covering slag, pa.s; v: target pulling speed, m/min.
The control process ensures that slag lubricates and flows into the meniscus and fills the air gap between the copper plate of the crystallizer and the blank shell by controlling the mold flux to reasonably slag layer slag thickness and consumption.
(3) Ensures the steady casting of heat flow, and controls the heat flow deviation to be less than or equal to 0.2MW/m 2 The heat flow ratio of the wide side to the narrow side of the crystallizer is controlled to be 1.1-1.25; the temperature difference between the cooling water inlet and outlet of the crystallizer is controlled to be 3-8 ℃, preferably 3-6 ℃ in summer and 5-8 ℃ in winter; and the control of the superheat temperature of molten steel at 15-30 ℃ is ensured by adopting the control of the temperature with narrow superheat.
(4) The crystallizer vibration adopts a smooth sawtooth wave negative slip vibration mode, the deflection rate is 60 percent, the smoothness is 25 percent, when the pulling speed is 0.9-1.6 m/min, the frequency is 130-180 (1/min), the negative slip time is controlled to be 0.12-0.15 s, the negative slip displacement is controlled to be 2.5-3.5 mm, and the negative slip time rate is controlled to be 39-43 percent.
The skew ratio: (total time of upstroke/total time of one vibration cycle) ×100;
the negative slip time rate: ratio of negative slip time to half vibration period in one vibration period, ts=2s/T; wherein, negative slip time rate: ts; negative slip time: s, S; vibration cycle: t.
In the control process, the crystallizer vibration adopts a smooth sawtooth wave negative slip mode, the deflection rate is 60 percent, the smoothness is 25 percent, the rising time is longer than the falling time, the speed is gentle, the mold flux consumption is increased, the molten steel friction force near the meniscus of the crystallizer can be reduced, the tensile stress born by a primary green shell is reduced, and the steel leakage risk is reduced; the negative slip vibration is that when the crystallizer vibrates downwards, the vibration speed is higher than the blank pulling speed, negative slip is formed, during the period, the blank shell is pressed more than the tension, and the solidified blank shell is pressed to enable the split blank shell to be welded, so that the blank shell is beneficial to healing. However, the negative slip time is too long, the deeper the vibration mark is, the more serious the slag is clamped on the blank shell at the vibration mark, so that the negative slip time is controlled to be 0.12-0.15 s, and the negative slip time rate is controlled to be 39-43%.
(5) The implementation effect is as follows: FIGS. 1 and 2 are schematic views of surface longitudinal crack defects of casting blanks and strip steel obtained by a conventional method, wherein the depth of the longitudinal crack is 0.25mm in FIG. 1, and the longitudinal crack is in a black long line shape in FIG. 2; fig. 3 and 4 are surface perspective views of the casting blank and the strip steel obtained by the method, and the continuous casting method can effectively improve the surface quality of the casting blank and the strip steel. After the continuous casting method is adopted, the occurrence rate of the casting blank surface longitudinal crack defect is reduced to 1.5 to 1.8 percent from 16 to 21 percent of the conventional method, and the occurrence rate of the strip steel surface longitudinal crack defect is reduced to 0.9 to 1.2 percent from 8 to 13 percent of the conventional method.
Example 1: the method for prejudging the casting blank longitudinal crack risk and the continuous casting method based on the prenatal prejudgment are specifically as follows.
(1) Pre-judging before labor: rating the state of the casting machine, wherein the vibration longitudinal deflection of the crystallizer is less than or equal to +/-0.1 mm, and the transverse deflection is +/-0.08 to +/-0.17 mm, which is the B grade;
the deviation of 2 points of the outer arc line of the sector section is more than or equal to 0.5mm (wherein 1 point is 0.5mm,1 point is 0.7 mm), and the deviation of other points is less than or equal to 0.5mm, and the outer arc line of the sector section is B grade;
the spray state is in a scattered mist form, 1-8 sections of the spray state totally comprise 140 sprays (70 inner arcs and 70 outer arcs), 3 spray nozzles are blocked (2 inner arcs and 1 outer arcs are blocked), the blocking rate is 2.1%, the requirement that the blocking rate is less than or equal to 3% is met, and the spray state is A level;
the comprehensive equipment rating is prejudged as class B.
(2) The continuous casting process comprises the following steps: the method is used for producing a pickling product QSTE420TM, and comprises the following chemical components in percentage by mass: 0.08% of C, 0.06% of Si, 1.21% of Mn, 0.011% of P, 0.006% of S, 0.03% of Al, 0.022% of Nb, 0.011% of Ti, and the balance of Fe and unavoidable impurities. And the carbon equivalent formula is combined to calculate that the carbon equivalent of the QSTE420TM of the pickling product is 0.28, and the requirement that the carbon equivalent is more than or equal to 0.1 and less than 0.3 in the B-stage equipment is met.
Casting QSTE420TM casting blank with section of 1500mm and casting blank thicknessThe temperature is 240mm, the quick expansion and pull speed is in the initial casting stage, after starting, the quick expansion and pull speed passes through the lower opening of the crystallizer at 0.4m/min, and then at 0.4m/min 2 Accelerating to 0.8m/min, maintaining for 2.5 min, and then adjusting the speed to 0.2m/min 2 The speed-increasing reference is lifted to the target pulling speed of 1.3m/min, and the constant pulling speed casting is kept;
adding the mold flux for 6-8 min once, wherein the adding amount of each time is 5-7 kg, the mold flux is uniformly dispersed on the surface of the molten steel of the mold, the surface of the molten steel is not exposed, the phenomena of local reddening and steel bloom do not occur, slag strips are not selected in the casting process, the thickness of a slag layer is 10mm, and the slag consumption is 0.45kg/t;
the heat flow of the crystallizer is controlled to be less than or equal to 0.15MW/m 2 In the range, the heat flow ratio of the wide side and the narrow side is controlled within the range of 1.1-1.2, the temperature difference of cooling water inlet and outlet of the crystallizer is 5 ℃ (winter), and the narrow superheat degree is controlled to be 18-30 ℃;
the crystallizer vibration control adopts a smooth sawtooth wave negative slip vibration mode, the deflection rate is 60%, the smoothness is 25%, the pulling speed is 1.3m/min, the vibration frequency is 165/min, the negative slip time is 0.12s, the negative slip displacement is 2.8mm, and the negative slip time rate is 40%.
(3) And (3) detecting products: cold inspection is carried out on the obtained casting blank, and the longitudinal crack defect on the surface of the casting blank is not found; tracking the subsequent rolling, and ensuring that the surface state of the cold coil is good and no surface longitudinal crack defect exists.
Example 2: the method for prejudging the casting blank longitudinal crack risk and the continuous casting method based on the prenatal prejudgment are specifically as follows.
(1) Pre-judging before labor: rating the state of the casting machine, wherein the vibration longitudinal deflection of the crystallizer is less than or equal to +/-0.18 mm, and the transverse deflection is less than or equal to +/-0.03 mm, which is grade A;
the outer arc deviation of the sector section is less than or equal to 0.5mm, and the sector section is A grade;
the spray state is in a scattered mist form, 1-8 sections are totally 140 sprays (70 inner arcs and 70 outer arcs), 4 spray nozzles are blocked (2 inner arcs and 2 outer arcs), the blocking rate is 2.8%, the requirement that the blocking rate is less than or equal to 3% is met, and the spray state is A grade;
the comprehensive equipment rating is prejudged as class A.
(2) The continuous casting process comprises the following steps: the method is used for producing the high-strength steel product DP780, and comprises the following chemical components in percentage by mass: 0.13% of C, 0.3% of Si, 1.75% of Mn, 0.015% of P, 0.01% of S, 0.045% of Al, 0.3% of Cr, and the balance of Fe and unavoidable impurities. The DP780 carbon equivalent of the high-strength steel product is 0.47 by combining with a carbon equivalent formula, and the requirement of sensitive steel types with carbon equivalent of 0.3-0.6 in the equipment A level is met.
The casting DP780 casting blank has 1300mm cross section, 240mm casting blank thickness, quick expansion and pulling speed in the initial casting stage, and after starting, the casting blank passes through the lower opening of the crystallizer at 0.4m/min and then at 0.3m/min 2 Accelerating to 0.8m/min, keeping for 2 min, and then adding the accelerator at 0.2m/min 2 The speed-increasing reference is lifted to the target pulling speed of 1.4m/min, and the constant pulling speed casting is kept;
adding the mold flux of the crystallizer for 5-7 min once, wherein the adding amount of each time is 4-6 kg, the mold flux is uniformly dispersed on the surface of molten steel of the crystallizer, the surface of the molten steel is not exposed, the phenomena of local reddening and steel bloom do not occur, slag strips are not selected in the casting process, the thickness of a slag layer is 15mm, and the slag consumption is 0.6kg/t;
the heat flow of the crystallizer is controlled to be less than or equal to 0.2MW/m 2 In the range, the heat flow ratio of the wide side and the narrow side is controlled within the range of 1.15-1.2, the temperature difference between the cooling water inlet and outlet of the crystallizer is 6 ℃ (winter), and the narrow superheat degree is controlled to be 15-23 ℃;
the crystallizer vibration control adopts a smooth sawtooth wave negative slip vibration mode, the deflection rate is 60%, the smoothness is 25%, the pulling speed is 1.4m/min, the vibration frequency is 175/min, the negative slip time is 0.13s, the negative slip displacement is 2.6mm, and the negative slip time rate is 43%.
(3) And (3) detecting products: cold inspection is carried out on the obtained casting blank, and as shown in fig. 3 and 4, no longitudinal crack defect on the surface of the casting blank is found; tracking the subsequent rolling, and ensuring that the surface state of the cold coil is good and no surface longitudinal crack defect exists.
Example 3: the method for prejudging the casting blank longitudinal crack risk and the continuous casting method based on the prenatal prejudgment are specifically as follows.
(1) Pre-judging before labor: rating the state of the casting machine, wherein the vibration longitudinal deflection of the crystallizer is less than or equal to +/-0.15 mm, and the transverse deflection is +/-0.05 to +/-0.12 mm, which is the B grade;
the deviation of 3 points of the outer arc line of the sector section is more than or equal to 0.5mm (wherein 1 point is 0.5mm,1 point is 0.7mm, 1 point is 0.8 mm), and the deviation of other points is less than or equal to 0.5mm, and the sector section is class B;
the spray state is in a scattered mist form, 1-8 sections of the spray state totally comprise 140 sprays (70 inner arcs and 70 outer arcs), 6 spray nozzles are blocked (4 inner arcs and 2 outer arcs), the blocking rate is 4.3%, the requirement that the blocking rate is less than or equal to 5% and less than 3% is met, and the spray state is B grade;
the comprehensive equipment rating is prejudged as class B.
(2) The continuous casting process comprises the following steps: the method is used for producing structural steel SAPH440, and comprises the following chemical components in percentage by mass: 0.075% C, 0.05% Si, 1.15% Mn, 0.016% P, 0.008% S, 0.025% Al, 0.008% Nb, 0.009% Ti, and the balance Fe and unavoidable impurities. The structural steel product SAPH440 carbon equivalent was 0.26 as calculated by the carbon equivalent formula. Meets the requirement that the carbon equivalent is less than or equal to 0.1 and less than 0.3 when the equipment is in the B level.
Casting SAPH440 casting blank with a section of 1200mm, a casting blank thickness of 240mm, and a quick expansion and pulling speed at the initial stage of casting, wherein the casting blank passes through a lower opening of a crystallizer at 0.4m/min after starting, and then passes through the casting blank at 0.4m/min 2 Accelerating to 0.8m/min, maintaining for 3 min, and then adjusting the speed to 0.2m/min 2 The speed-increasing reference is lifted to the target pulling speed of 1.5m/min, and the constant pulling speed casting is kept;
adding the mold flux of the crystallizer for 5-7 min once, wherein the adding amount of each time is 4-6 kg, the mold flux is uniformly dispersed on the surface of molten steel of the crystallizer, the surface of the molten steel is not exposed, the phenomena of local reddening and steel bloom do not occur, slag strips are not selected in the casting process, the thickness of a slag layer is 8mm, and the slag consumption is 0.35kg/t;
the heat flow of the crystallizer is controlled to be less than or equal to 0.2MW/m 2 In the range, the heat flow ratio of the wide side and the narrow side is controlled within the range of 1.15-1.25, the cooling water inlet and outlet temperature difference of the crystallizer is 4 ℃ (summer), and the narrow superheat degree is controlled to be 17-28 ℃;
the crystallizer vibration control adopts a smooth sawtooth wave negative slip vibration mode, the deflection rate is 60%, the smoothness is 25%, the pulling speed is 1.5m/min, the vibration frequency is 180/min, the negative slip time is 0.13s, the negative slip displacement is 2.5mm, and the negative slip time rate is 39%.
(3) And (3) detecting products: cold inspection is carried out on the obtained casting blank, and the longitudinal crack defect on the surface of the casting blank is not found; tracking the subsequent rolling, and ensuring that the surface state of the cold coil is good and no surface longitudinal crack defect exists.
Example 4: the method for prejudging the casting blank longitudinal crack risk and the continuous casting method based on the prenatal prejudgment are specifically as follows.
(1) Pre-judging before labor: rating the state of the casting machine, wherein the vibration longitudinal deflection of the crystallizer is +/-0.20 to +/-0.23 mm, and the transverse deflection is less than or equal to +/-0.2 mm, and the state is C grade;
the deviation of the outer arc line of the sector section is 1 point which is more than or equal to 0.5mm (0.9 mm), and the deviation of other points is less than or equal to 0.5mm, which is class B;
the spray state is in a scattered mist form, 1-8 sections of the spray state totally comprise 140 sprays (70 inner arcs and 70 outer arcs), 8 spray nozzles are blocked (5 inner arcs and 3 outer arcs), the blocking rate is 5.7%, the requirements that the blocking rate is more than 5% and less than or equal to 8% are met, and the spray state is C level;
the comprehensive equipment rating is prejudged as class C.
(2) The continuous casting process comprises the following steps: the method is used for producing a common low-carbon product DC01, and comprises the following chemical components in percentage by mass: 0.025% of C, 0.12% of Mn, 0.02% of P, 0.015% of S, 0.03% of Al, and the balance of Fe and unavoidable impurities. And the DC01 carbon equivalent of the common low-carbon product is 0.045 calculated by combining a carbon equivalent formula, and the common low-carbon product is a common steel grade which is not easy to longitudinally crack.
The SPHC casting blank is poured with 1600mm of cross section, 240mm of casting blank thickness, quick expansion and pulling speed in the initial stage of casting, passes through the lower opening of the crystallizer at 0.4m/min after starting, and then passes through the lower opening of the crystallizer at 0.35m/min 2 Accelerating to 0.8m/min, keeping for 2 min, and then adding the accelerator at 0.2m/min 2 The speed-increasing reference is lifted to the target pulling speed of 1.2m/min, and the constant pulling speed casting is kept;
adding the mold flux of the crystallizer for 6-8 min once, wherein the adding amount of each time is 6-7 kg, and the mold flux is uniformly dispersed on the surface of molten steel of the crystallizer, so that the surface of the molten steel is not exposed, the phenomena of local reddening and steel bloom do not occur, slag strips are not selected in the casting process, the thickness of a slag layer is 15mm, and the slag consumption is 0.5kg/t;
the heat flow of the crystallizer is controlled to be less than or equal to 0.1MW/m 2 In the range, the heat flow ratio of the wide side and the narrow side is controlled within the range of 1.15-1.2, the temperature difference of cooling water inlet and outlet of the crystallizer is 5 ℃ (summer), and the narrow superheat degree is controlled to be 16-25 ℃;
the crystallizer vibration control adopts a smooth sawtooth wave negative slip vibration mode, the deflection rate is 60%, the smoothness is 25%, the pulling speed is 1.2m/min, the vibration frequency is 160/min, the negative slip time is 0.15s, the negative slip displacement is 3.2mm, and the negative slip time rate is 43%.
(3) And (3) detecting products: cold inspection is carried out on the obtained casting blank, and the longitudinal crack defect on the surface of the casting blank is not found; tracking the subsequent rolling, and ensuring that the surface state of the cold coil is good and no surface longitudinal crack defect exists.
Example 5: the method for prejudging the casting blank longitudinal crack risk and the continuous casting method based on the prenatal prejudgment are specifically as follows.
(1) Pre-judging before labor: firstly, grading the state of a casting machine, wherein the vibration longitudinal deflection of a crystallizer is less than or equal to +/-0.18 mm, and the transverse deflection is less than or equal to +/-0.04 mm, and is grade A;
the outer arc deviation of the sector section is less than or equal to 0.5mm, and the sector section is A grade;
the spray state is in a scattered mist form, 1-8 sections of the spray state totally comprise 140 sprays (70 inner arcs and 70 outer arcs), the number of nozzles is 2 (1 inner arc and 1 outer arc), the blocking rate is 1.4%, the requirement that the blocking rate is less than or equal to 3% is met, and the spray state is A level;
the comprehensive equipment rating is prejudged as class A.
(2) The continuous casting process comprises the following steps: the method is used for producing the high-strength steel product 980FG, and comprises the following chemical components in percentage by mass: 0.13% of C, 0.5% of Si, 1.86% of Mn, 0.01% of P, 0.007% of S, 0.035% of Al, 0.3% of Cr, 0.02% of Ti, and the balance of Fe and unavoidable impurities. The high strength steel product 980FG carbon equivalent is 0.51 calculated in combination with the carbon equivalent formula. Meets the requirement that the carbon equivalent of equipment A is more than or equal to 0.3 and less than 0.6.
Casting 980FG casting blank with 1100mm section, 240mm thickness, quick expansion and pulling speed in initial casting stage, starting, passing through the crystallizer lower port at 0.4m/min, and then at 0.3m/min 2 Accelerating to 0.8m/min, keeping for 2 min, and then adding the accelerator at 0.2m/min 2 The speed-increasing reference is lifted to the target pulling speed of 1.6m/min, and the constant pulling speed casting is kept;
adding the mold flux of the crystallizer for 5-7 min once, wherein the adding amount of each time is 4-6 kg, the mold flux is uniformly dispersed on the surface of molten steel of the crystallizer, the surface of the molten steel is not exposed, the phenomena of local reddening and steel bloom do not occur, slag strips are not selected in the casting process, the thickness of a slag layer is 12mm, and the slag consumption is 0.4kg/t;
the heat flow of the crystallizer is controlled to be less than or equal to 0.1MW/m 2 In the range, the heat flow ratio of the wide side and the narrow side is controlled to be 1.1-1.15In the cooling water inlet and outlet temperature difference of the crystallizer is 4 ℃ (summer), and the narrow superheat degree is controlled to be 12-20 ℃;
the crystallizer vibration control adopts a smooth sawtooth wave negative slip vibration mode, the deflection rate is 60%, the smoothness is 25%, the pulling speed is 1.6m/min, the vibration frequency is 180/min, the negative slip time is 0.12s, the negative slip displacement is 2.5mm, and the negative slip time rate is 39%.
(3) And (3) detecting products: cold inspection is carried out on the obtained casting blank, and the longitudinal crack defect on the surface of the casting blank is not found; tracking the subsequent rolling, and ensuring that the surface state of the cold coil is good and no surface longitudinal crack defect exists.
Example 6: the method for prejudging the casting blank longitudinal crack risk and the continuous casting method based on the prenatal prejudgment are specifically as follows.
(1) Pre-judging before labor: rating the state of the casting machine, wherein the vibration longitudinal deflection of the crystallizer is +/-0.25-0.28 mm, and the transverse deflection is less than or equal to +/-0.18 mm, which is grade D;
the deviation of 4 points of the outer arc line of the sector section is more than or equal to 0.5mm (wherein 1 point is 0.5mm, 2 points are 0.7mm, 1 point is 0.9 mm), and the deviation of other points is less than or equal to 0.5mm, and the sector section is class C;
the spray state is in a scattered mist form, 1-8 sections of the spray state totally comprise 140 sprays (70 inner arcs and 70 outer arcs), 9 spray nozzles are blocked (5 inner arcs and 4 outer arcs), the blocking rate is 6.4%, the requirements that the blocking rate is more than 5% and less than or equal to 8% are met, and the spray state is C level;
the comprehensive equipment rating is prejudged as class D.
(2) The continuous casting process comprises the following steps: the method is used for producing the ultra-low carbon product DC05, and comprises the following chemical components in percentage by mass: 0.0018% of C, 0.003% of Si, 0.097% of Mn, 0.012% of P, 0.006% of S, 0.037% of Al, 0.061% of Ti, 0.0005% of B, 0.0022% of N, and the balance of Fe and unavoidable impurities. And the DC05 carbon equivalent of the common low-carbon product is 0.018, which is a common steel grade not easy to longitudinally crack.
The casting DC05 casting blank has a section of 1500mm, a casting blank thickness of 240mm, a quick expansion and pulling speed at the initial stage of casting, and passes through a lower opening of a crystallizer at 0.4m/min after starting, and then passes through the casting blank at 0.4m/min 2 Accelerating to 0.8m/min, keeping for 2 min, and then adding the accelerator at 0.2m/min 2 Is lifted to the target pulling speed of 1.3m/min and kept constant pullingCasting at a high speed;
adding the mold flux of the crystallizer for 6-8 min once, wherein the adding amount of each time is 6-7 kg, and the mold flux is uniformly dispersed on the surface of molten steel of the crystallizer, so that the surface of the molten steel is not exposed, the phenomena of local reddening and steel bloom do not occur, slag strips are not selected in the casting process, the thickness of a slag layer is 12mm, and the slag consumption is 0.45kg/t;
the heat flow of the crystallizer is controlled to be less than or equal to 0.1MW/m 2 In the range, the heat flow ratio of the wide side and the narrow side is controlled within the range of 1.15-1.2, the cooling water inlet and outlet temperature difference of the crystallizer is 5 ℃ (summer), and the narrow superheat degree is controlled to be 18-26 ℃;
the crystallizer vibration control adopts a smooth sawtooth wave negative slip vibration mode, the deflection rate is 60%, the smoothness is 25%, the pulling speed is 1.3m/min, the vibration frequency is 130/min, the negative slip time is 0.14s, the negative slip displacement is 3.5mm, and the negative slip time rate is 41%.
(3) And (3) detecting products: cold inspection is carried out on the obtained casting blank, and the longitudinal crack defect on the surface of the casting blank is not found; tracking the subsequent rolling, and ensuring that the surface state of the cold coil is good and no surface longitudinal crack defect exists.
Claims (6)
1. A method for pre-judging casting blank longitudinal crack risk before production is characterized in that: rating the state of the casting machine equipment, and respectively evaluating the rating rules from four grades A, B, C, D;
the crystallizer vibrates: the longitudinal deflection is < + -0.2 mm, and the transverse deflection is < + -0.05 mm, which is grade A; the longitudinal deflection is less than or equal to +/-0.2 mm, and the transverse deflection is less than or equal to +/-0.05 mm, and the transverse deflection is less than or equal to +/-0.2 mm, which is B grade; the longitudinal deflection is less than or equal to +/-0.25 mm and the transverse deflection is less than or equal to +/-0.2 mm, and the C level is the same; the D level is that the longitudinal deflection is less than or equal to +/-0.25 mm and less than or equal to +/-0.3 mm, and the transverse deflection is less than or equal to +/-0.2 mm;
outer arc deviation of the sector: all points are < + -0.5 mm as class A; the deviation of 1 to 3 points of the camber line with the length of plus or minus 0.5mm is less than or equal to plus or minus 1.0mm, and the deviation of other points with the length of minus or plus 0.5mm is grade B; the deviation of 4 to 5 points of the outer arc line with the length of plus or minus 0.5mm is less than plus or minus 1.0mm, and the deviation of other points with the length of plus or minus 0.5mm is C grade; the deviation of 6 to 8 points of the outer arc line with the length of plus or minus 0.5mm is less than plus or minus 1.0mm, the deviation of not more than 2 points is more than or equal to plus or minus 1.0mm, and the other deviations are all less than or equal to plus or minus 0.5mm and are grade D;
spraying state: the blocking rate of the straightening section before continuous casting and blank drawing is less than or equal to 3 percent and is A grade; the blocking rate is more than 3 percent and less than or equal to 5 percent and is B grade; the blocking rate is more than 5 percent and less than or equal to 8 percent and is C grade; 8% < blocking rate grade D;
the equipment rating is pre-judged to be a short plate, and the worst conditions of the vibration of the crystallizer, the deviation of the outer arc line of the sector section and the spraying state are used as standards to pre-judge the casting blank surface longitudinal crack risk: the comprehensive evaluation A is the minimum risk of longitudinal fracture, the comprehensive evaluation B is the second grade and the comprehensive evaluation C is the maximum risk of longitudinal fracture.
2. A continuous casting method based on prenatal pre-judgment, which adopts the method of claim 1 to perform prenatal pre-judgment, and is characterized in that: the casting machine equipment comprehensively evaluates the grade A to produce sensitive steel with carbon equivalent of more than or equal to 0.3 and less than 0.6; comprehensively evaluating the acid-washed steel and structural steel with carbon equivalent of 0.1-0.3 in the class B; and comprehensively evaluating the grade C and grade D to produce common ultra-low carbon steel and low carbon steel.
3. The continuous casting method based on prenatal prediction according to claim 2, wherein the drawing speed control of the continuous casting start-up is: after starting, the mixture passes through the lower opening of the crystallizer at the pulling speed of 0.4m/min and then passes through the lower opening of the crystallizer at the pulling speed of 0.3-0.4 m/min 2 Accelerating to 0.8m/min, keeping for 2-3 min and then using 0.2m/min 2 Is increased to the target pull speed.
4. The continuous casting method based on prenatal prediction according to claim 2, characterized in that: in the continuous casting process, controlling the thickness of a slag layer to be 8-15 mm, and calculating the consumption of the protective slag according to a formula (I);
Q=0.8(1/A 0.3 )(60/f)(nV 2 ) -0.5 +0.13 （Ⅰ）
wherein Q: consumption of mold flux, kg/m 2 The method comprises the steps of carrying out a first treatment on the surface of the A: the amplitude of the vibration of the crystallizer is mm; f: frequency of vibration of the crystallizer, times/min; n: the viscosity of the covering slag, pa.s; v: target pulling speed, m/min.
5. The continuous casting method based on prenatal prediction according to claim 2, characterized in that: in the continuous casting process, the heat flow ratio of the wide side to the narrow side of the crystallizer is controlled to be 1.1-1.25, and the superheat degree of molten steel is controlled to be 15-30 ℃.
6. The continuous casting method based on prenatal prediction according to any one of claims 2 to 5, characterized in that: the crystallizer vibration in the continuous casting process adopts a smooth sawtooth wave negative slip mode, the deflection rate is 60%, the smoothness is 25%, the negative slip time is controlled to be 0.12-0.15 s, and the negative slip time rate is controlled to be 39-43%.
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