CN115369203A - Comprehensive control method for corner cracks of fine blanking steel plate blank - Google Patents
Comprehensive control method for corner cracks of fine blanking steel plate blank Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
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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
- 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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- 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
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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Abstract
The invention belongs to the technical field of steel making, and further relates to a comprehensive control method for corner cracks of a fine blanking steel slab. The invention comprises the following steps: controlling the temperature drop of the process; step two: controlling converter smelting; step three: and (3) LF (ladle furnace) rapid refining: step four: RH circulation degassing; step five: controlling cold water in the second continuous casting step; step six: controlling argon blowing; the invention effectively eliminates and reduces the corner cracks caused by non-metallic inclusions in steel, the precipitation of the net proeutectoid ferrite on the surface grain boundary of the casting blank and the third brittle interval; the oxygen content of steel is reduced by improving converter smelting; part of the deoxygenated product was further removed by LF refining, RH refining and calcium treatment.
Description
Technical Field
The invention belongs to the technical field of steel making, and further relates to a comprehensive control method for corner cracks of a fine blanking steel slab.
Background
The fine blanking process is an efficient and economic processing technology for manufacturing precise and complex stamping parts by combining fine blanking and plate forming, can obtain high-quality parts, and has strict requirements on chemical components, dimensional precision, surface quality and processing performance of steel. In the production process, because the carbon and alloy contents of the low-carbon low-alloy steel are higher than those of low-carbon low-alloy steel produced by the traditional hot continuous rolling enterprises, the continuous casting billet is easy to generate corner transverse cracks, and then the edge of a hot rolled plate coil is caused to generate the defect of warping, so that the plate coil is directly judged to be waste.
The casting blank has the universal characteristic of generating corner cracks, particularly, microalloy steel (containing Nb, V, ti and B) is serious, a great deal of research is carried out at home and abroad on the control of the continuous casting corner cracks of the microalloy steel, and the research on the fine blanking steel with high carbon and alloy contents is less. The corner crack control measures of the microalloy steel are mainly focused on the following aspects: and (1) controlling the components of the molten steel. Reducing segregation of solutes such as crystal boundary P, S and the like in the solidification process of the casting blank; (2) A nitrogen control and fixation process is adopted in the refining process, so that the precipitation of carbonitrides in the solidification process of the continuous casting billet is reduced, and the corner structure strength of the casting billet is improved; (3) Controlling water distribution in the secondary cooling arc and straightening area to ensure that the surface temperature of the casting blank avoids a third brittleness temperature range of the steel in the bending and straightening processes; (4) The casting blank is slowly cooled by adjusting the taper, vibration and cooling strength, physical parameters of the casting powder and the like, the initial solidification structure of the casting blank is lightened, and the generation of cracks at the corner of the casting blank is prevented.
However, in the actual fine blanking steel production process, the main causes of corner cracks are as follows: (1) The operation condition is unstable during pouring, so that large-particle nonmetallic inclusions in the steel are involved, the continuity of a metal matrix is damaged, and stress concentration is generated in the bending process; (2) When the continuous casting blank enters a bending section, the temperature of a corner is in a third brittle section, so that the high-temperature thermoplasticity of the corner of the casting blank is deteriorated; (3) Before the casting blank exits the crystallizer and enters the bending section, the cooling strength is low, so that the net ferrite at the grain boundary of the corner of the casting blank is seriously separated, and the high-temperature plasticity of the casting blank is deteriorated. Therefore, the key of fundamentally controlling the production of the fine blanking steel is to control the cleanliness of molten steel, stabilize the operation process of each unit and ensure the stability of casting conditions; and strengthening secondary cold water distribution from the crystallizer to the bending section, so that the temperature of the corner part is kept away from a third brittleness area when the continuous casting billet enters the bending section, and the precipitation of inter-crystalline reticular precipitated ferrite is reduced. At present, no process or method for effectively controlling cracks of continuous casting corners of steel enterprises in the production process of fine blanking steel exists.
Disclosure of Invention
In order to solve the above problems, an object of the present invention is to provide a method capable of effectively solving the generation of cracks at a continuous casting corner.
In order to achieve the purpose, the invention provides the following technical scheme:
a comprehensive control method for corner cracks of a fine blanking steel slab comprises the following steps:
the method comprises the following steps: controlling the process temperature drop:
ΔT general (1) =ΔT 1 +ΔT 2 +ΔT 3 +ΔT 4 +ΔT 5
ΔT General (1) The total temperature drop in the molten steel process; delta T 1 The tapping temperature is reduced; delta T 2 Cooling the steel after tapping in the process of refining and transporting the molten steel outside the furnace; delta T 3 The temperature of the molten steel is reduced in the ladle treatment process; delta T 4 The temperature of the steel ladle is reduced in the process of transporting the steel ladle to the tundish; delta T 5 And the temperature of the molten steel in the tundish is reduced.
Controlling the oxygen content at the end point of the converter to reduce the alloy addition and turnoverSteel ladle is less than or equal to 6, steel is tapped in red ladle, the tapping time is 6-8min, delta T 1 At most 20 ℃; reasonably arranging and planning a production plan, covering the whole course of non-treatment time, waiting time of molten steel in each furnace is less than or equal to 5min, cooling rate is less than 1 ℃/min, and delta T 2 Less than or equal to 10 ℃; controlling the temperature rise speed of molten steel in the LF treatment process at 3-4 ℃/min, confirming the heat storage state of the ladle (the temperature reduction rate is less than 0.5 ℃/min), adjusting production section to ensure the subsequent appropriate treatment time, and controlling the RH treatment temperature drop, namely delta T 3 Less than or equal to 25 ℃; controlling the time of initial sedation at 20min, delta T 4 Less than or equal to 10 ℃; the baking time of the tundish is not less than 150 minutes, and the tundish low-density carbonized rice hull heat preservation agent is selected to cover the surface of the molten steel, so that the temperature difference delta T of the molten steel poured into a furnace is ensured 5 Is less than or equal to 5 ℃. Under the condition of LF furnace temperature compensation, the total temperature drop Delta T from converter tapping (molten steel in a ladle) to continuous casting pouring (molten steel in a tundish) is controlled General assembly ≤70℃。
Step two: controlling converter smelting:
controlling the oxygen content, the carbon content and the sulfur content at the end point of the converter, reducing the tapping temperature, reducing primary deoxidation products in steel by tapping through a full deoxidation process, and pre-manufacturing desulfurization slag by utilizing tapping convection mixed impact;
step three: and (3) LF (ladle furnace) rapid refining:
the LF enters a station and is supplemented with desulfurized lime, bottom blowing is adjusted after slagging, primary main heating and temperature rising are carried out, aluminum deoxidation and strong stirring desulfurization are added after the temperature meets the requirement, alloying is carried out after desulfurization, part of deoxidation products are taken out through soft stirring, and finally the products are taken out of the station;
step four: RH circulation degassing:
performing conventional degassing circulation treatment after RH entering a station, then performing calcium treatment, and fully floating impurities and removing the impurities after soft stirring;
step five: controlling the secondary cooling water of continuous casting:
adjusting the secondary cooling ratio water quantity to be 0.89, increasing the cooling water quantity of the sufficient roller section, the first cooling area to the third cooling area, and keeping the original water quantity for the rest.
Step six: and (3) argon blowing control:
and adjusting the argon blowing flow of the stopper rod and the submerged nozzle to be 2-3L/min, and adjusting the argon sealing flow between the tundish upper nozzle and the submerged nozzle to be 5L/min.
The scheme is further improved as follows: the temperature drop control is specifically as follows:
the oxygen content at the end point of the converter is controlled, the alloy addition is reduced, and the delta T is controlled 1 ≤20℃；
Covering in the whole course of non-treatment time, waiting for molten steel in each furnace for less than or equal to 5min, and controlling delta T 2 ≤10℃；
Controlling the temperature rise speed of the molten steel in the LF treatment process to be 3-4 ℃/min and the RH treatment temperature drop to control delta T 3 ≤25℃；
Controlling the start-pouring sedation time to be 20min and controlling delta T 4 ≤10℃；
Baking the tundish for not less than 150 minutes, covering the surface of the molten steel with a tundish low-density carbonized rice hull heat preservation agent, and controlling the temperature difference delta T of the molten steel poured into a furnace 5 ≤5℃；
Under the condition of LF furnace temperature compensation, the total temperature drop Delta T from converter tapping to continuous casting pouring is controlled General assembly ≤70℃。
The further improvement of the scheme is as follows: in the first step, the turnover ladle is controlled to be less than or equal to 6, the tapping time is controlled to be 6-8min, the abnormal waiting time of molten steel in each furnace is controlled to be less than or equal to 5min, the total temperature drop in the process is controlled to be less than or equal to 70 ℃, and the stability of the superheat degree in the casting process is guaranteed.
The further improvement of the scheme is as follows: in the second step, the range of the carbon content at the end point of the converter is controlled to be 0.06 +/-0.02%, and the range of the tapping temperature is controlled to be 1610 +/-5 ℃. The oxygen content of tapping is reduced, and the deoxidation output generation is reduced.
The further improvement of the scheme is as follows: and in the second step, aluminum, manganese and calcium are added during tapping, and desulfurized lime and ladle slag modifier are added in advance.
The further improvement of the scheme is as follows: in the first, third and fourth steps, the molten steel sedation time between the RH station leaving and the continuous casting start is prolonged to 20min, the LF and RH weak stirring time is prolonged to 8min, and endogenetic inclusions are floated upwards.
The further improvement of the scheme is as follows: in the fourth step, the calcium treatment comprises feeding pure calcium wires in a repeated pressing mode, and then carrying out soft stirring and soft blowing.
The scheme is further improved as follows: in the fifth step, the cooling water quantity of the first zone to the third zone of the continuous casting secondary cooling zone is increased, and the surface temperature of the casting blank is ensured to avoid a brittle temperature range of 710-765 ℃ during bending operation.
The further improvement of the scheme is as follows: in the sixth step, the stopper rod, the water gap and the argon seal gas flow are reduced.
The invention has the beneficial effects that: by adopting the method, the operation orders in the whole process can be optimized and matched, the exclusive metallurgical function of each smelting unit is fully exerted, the cleanliness of the molten steel is improved, the pouring temperature is stabilized, secondary cooling water adjustment is carried out by combining specific steel types, and the reduction of corner cracks caused by non-metallic inclusions in the steel, the precipitation of the net-shaped proeutectoid ferrite on the surface of a casting blank and a third brittle interval is effectively eliminated; the oxygen content of steel is reduced by improving converter smelting; part of the deoxygenated product is further removed by LF refining, RH refining and calcium treatment.
Drawings
FIG. 1 is a schematic flow chart of an embodiment of the present invention.
Detailed Description
Example 1
As shown in figure 1, the invention is applied to the production practice of fine blanking steel A, and the first furnace comprises the following specific steps:
the method comprises the following steps: controlling the temperature drop of the process:
the duplex steel grade adopts 5 turnover bags, and the use of the temperature raising bags is forbidden. Tapping in red ladle, wherein the tapping time is 6min, delta T 1 =20 ℃; covering in the whole non-treatment time, and waiting for molten steel for 1min, delta T 2 =8 ℃; the temperature rise speed of molten steel in the LF treatment process is controlled to be 3-4 ℃/min, the temperature drop of RH treatment is controlled, and delta T 3 =25 ℃; sedation for 20min, delta T 4 =10 ℃; the baking time of the tundish is not less than 150 minutes, and the tundish low-density carbonized rice hull heat preservation agent is selected to cover the surface of the molten steel, so that the temperature difference delta T of the molten steel poured into a furnace is ensured 5 =5 ℃. Total temperature drop Δ T of process General (1) =68℃。
Step two: controlling converter smelting: the components of the converter tapping terminal point are controlled to be 0.05 percent of carbon, 500ppm of oxygen and 0.012 percent of sulfur, and the tapping temperature is controlled to be 1610 ℃; 400kg of aluminum, manganese and calcium, 600kg of ferrosilicon, 4000kg of medium carbon ferrochromium, 800kg of metal manganese and 500kg of carburant are added into the steel tapping for deoxidation and prealloying, 500kg of desulfurized lime and 1000kg of ladle slag modifier are used for pre-manufacturing refined slag by utilizing the convection and mixing of the steel tapping;
step three: and (3) LF (ladle furnace) rapid refining: the Al content of the LF entering the station is 0.006 percent, the S content is 0.007 percent, and the temperature is 1580 ℃; adding 600kg of desulfurized lime 350kg of steel ladle slag modifier, heating the slag for 10min to 1610 ℃, then adding 70kg of aluminum for deoxidation and strong stirring for desulfurization, adding other alloys to the lower limit of the standard requirement of the chemical components of the steel grade after the desulfurization is finished, blowing argon at the bottom after the uniform mixing, using a soft stirring mode, carrying out soft stirring for 5-8min, and leaving the steel grade;
step three: RH circulation degassing: the sulfur content of the RH station is 0.0018%, the contents of other alloys are added to the lower limit of the standard requirement of the chemical components of the steel grade, and the temperature is 1590 ℃; then vacuumizing, supplementing alloy to the target composition, starting to circularly degas for 12min when the vacuum degree reaches 0.27Kpa, feeding 355m pure calcium wire of about 80kg under repeated pressure, softly blowing for 8min, and discharging, wherein the temperature is 1580 ℃.
Step five: controlling the secondary cooling water of continuous casting: according to the conventional technology, the high-temperature brittleness interval of the fine blanking steel grade is 710-765 ℃; the temperature of the upper platform is controlled to ensure stable pouring parameters of molten steel, the specific water quantity and water quantity distribution of a secondary cooling area are adjusted, namely the specific water quantity of the secondary cooling area is adjusted to be 0.89, the cooling water quantities of a foot roller section and a first to a third cooling areas of the cooling area are increased, the cooling rate of the foot roller and a bending section of the crystallizer is increased, the corner temperature of a casting blank is kept in a temperature brittleness area where crack defects are easy to generate in the bending section, and the rest of the casting blank keeps the original water quantity.
Step six: and (3) argon blowing control:
and adjusting the argon blowing flow of the stopper rod and the submerged nozzle to be 2-3L/min, and adjusting the argon sealing flow between the tundish upper nozzle and the submerged nozzle to be 5L/min.
Example 2
As shown in figure 1, the invention is applied to the production practice of fine blanking steel A, and the second furnace comprises the following specific steps:
5 turnover bags are adopted for duplex steel grades, and the use of a temperature raising bag is forbidden for the steel grades. Tapping in red ladle, wherein the tapping time is 8min, delta T 1 =22 ℃; covering the whole course of the non-treatment time,waiting time of molten steel 5min, delta T 2 =10 ℃; the temperature rise speed of molten steel in the LF treatment process is controlled to be 3-4 ℃/min, the temperature drop of RH treatment is controlled, and delta T 3 =20 ℃; sedation for 20min, delta T 4 =8 ℃; the baking time of the tundish is not less than 150 minutes, and the tundish low-density carbonized rice hull heat preservation agent is selected to cover the surface of the molten steel, so that the temperature difference delta T of the molten steel poured into a furnace is ensured 5 =6 ℃. Total temperature drop Δ T of process General assembly =66℃。
Step two: controlling converter smelting: the components of the converter tapping endpoint are controlled to be 0.069 percent of carbon, 350ppm of oxygen and 0.016 percent of sulfur, and the tapping temperature is controlled to be 1600 ℃; 400kg of aluminum-manganese-calcium, 600kg of ferrosilicon, 4000kg of medium carbon ferrochromium, 700kg of metal manganese and 440kg of carburant are added into the steel for deoxidation and prealloying, 530kg of desulfurized lime and 1400kg of ladle slag modifier are mixed and flushed by utilizing the convection of the steel to pre-manufacture refined slag;
step three: and (3) LF rapid refining: the LF inbound aluminum content is 0.0018%, the sulfur content is 0.010%, and the temperature is 1570 ℃; adding 700kg of desulfurized lime and 600kg of steel ladle slag modifier, heating the slag for 15min to 1610 ℃, adding 25kg of aluminum for deoxidation and strong stirring for desulfurization, adding other alloys to the lower limit after desulfurization, uniformly mixing, then bottom-blowing and adjusting to a soft stirring mode, carrying out soft stirring for 5-8min, and finally leaving the station;
step four: RH circulation degassing: the content of sulfur in RH entering station is 0.0019%, the content of other alloys is at the lower limit, and the temperature is controlled to be 1590 ℃; vacuumizing, adding alloy to a target component, starting to circularly degas for 12min when the vacuum degree reaches 0.27Kpa, feeding 355m pure calcium wire (80 kg) under repeated pressure, soft-blowing for 8min, and discharging, wherein the temperature is 1580 ℃;
step five: controlling continuous casting secondary cooling water: according to the conventional technology, the high-temperature brittleness interval of the fine blanking steel grade is 710-765 ℃; controlling the temperature of the upper platform, ensuring stable pouring parameters of molten steel, adjusting the specific water quantity and water distribution of the secondary cooling area, namely adjusting the specific water quantity of the secondary cooling area to be 0.89, increasing the cooling water quantities of the first to third areas of the foot roll section and the cooling area, controlling the temperature of the corner of the casting blank to avoid a high-temperature brittle section when the casting blank enters the bending section, and keeping the original water quantity for the rest.
Step six: and (3) argon blowing control: and adjusting the argon blowing flow of the stopper rod and the submerged nozzle to be 2-3L/min, and adjusting the argon sealing flow between the tundish upper nozzle and the submerged nozzle to be 5L/min.
In the above examples, no corner crack was found in any of 12 continuous slabs produced 2 passes of fine blanking steel a, and the comparative flow slab cracking rate was 6%.
In the above embodiment, the oxygen content in steel is reduced and the total amount of deoxidation products is reduced by controlling smelting in a converter in the step two, the total amount of deoxidation products is reduced by desulphurization and weak stirring in LF refining in the step two, the total amount of deoxidation products is reduced by degassing and vacuum circulation in RH refining and calcium treatment in the step three, and the total amount of deoxidation products is reduced by controlling cooling water and cooling of a casting blank in continuous casting in the step four. The deoxidation product is reduced (namely, the endogenic inclusions are reduced), the continuity of the casting blank matrix is improved, the microcrack source caused by the inclusions is effectively controlled, and the generation probability of corner cracks of the casting blank is reduced.
The present invention is not limited to the above embodiments, and any technical solutions formed by equivalent substitutions fall within the scope of the present invention.
Claims (10)
1. A comprehensive control method for corner cracks of a fine blanking steel slab is characterized by comprising the following steps:
the method comprises the following steps: controlling the process temperature drop:
controlling total temperature drop Delta Total in the molten steel process, wherein Delta Total = Delta T 1 +ΔT 2 +ΔT 3 +ΔT 4 +ΔT 5 (ii) a In the formula,. DELTA.T 1 For the temperature drop, delta T, of the tapping 2 The temperature drop and delta T are measured in the process of refining and transporting outside the furnace from tapping to molten steel 3 The temperature drop and delta T of molten steel in the ladle treatment process 4 The temperature drop and delta T of the steel ladle in the process of transporting the steel ladle to the tundish 5 The temperature drop of the molten steel in the tundish is measured;
step two: controlling converter smelting:
controlling the oxygen content, the carbon content and the sulfur content at the end point of the converter, reducing the tapping temperature, reducing primary deoxidation products in steel by tapping through a full deoxidation process, and pre-manufacturing desulfurization slag by utilizing tapping convection mixed impact;
step three: and (3) LF (ladle furnace) rapid refining:
the LF enters a station and is supplemented with desulfurized lime, bottom blowing is adjusted after slagging, primary main heating and temperature rising are carried out, after the temperature meets the requirement, aluminum deoxidation and strong stirring desulfurization are added, alloying is carried out after desulfurization, part of deoxidation products are removed by soft stirring, and finally the LF is taken out of the station;
step four: RH circulation degassing:
performing conventional degassing circulation treatment after RH entering a station, then performing calcium treatment, and fully floating impurities and removing the impurities after soft stirring;
step five: controlling the secondary cooling water of continuous casting:
adjusting the secondary cooling specific water quantity to 0.89, increasing the cooling water quantity of the foot roller section and the first to third cooling areas, and keeping the original water quantity in the rest areas;
step six: and (3) argon blowing control:
and adjusting the argon blowing flow of the stopper rod and the submerged nozzle to be 2-3L/min, and adjusting the argon sealing flow between the tundish upper nozzle and the submerged nozzle to be 5L/min.
2. The comprehensive control method for corner cracks of fine blanking steel slabs according to claim 1, characterized by comprising the following steps: the temperature drop control is specifically as follows:
the oxygen content at the end point of the converter is controlled, the alloy addition is reduced, and the delta T is controlled 1 ≤20℃；
Covering in the whole course of non-treatment time, waiting for molten steel in each furnace for less than or equal to 5min, and controlling delta T 2 ≤10℃；
Controlling delta T by controlling the heating rate of molten steel in the LF treatment process to be 3-4 ℃/min and the RH treatment temperature drop 3 ≤25℃；
Controlling the time of the initial sedation to be 20min and controlling the delta T 4 ≤10℃；
Baking the tundish for not less than 150 minutes, covering the surface of the molten steel with a tundish low-density carbonized rice hull heat preservation agent, and controlling the temperature difference delta T of the molten steel poured into a furnace 5 ≤5℃；
Under the condition of LF furnace temperature compensation, the total temperature drop delta T from converter tapping to continuous casting pouring is controlled General assembly ≤70℃。
3. The comprehensive control method for corner cracks of the fine blanking steel plate blank according to claim 1, characterized by comprising the following steps: the scheme is further improved as follows: in the first step, the turnover ladle is controlled to be less than or equal to 6, the tapping time is controlled to be 6-8min, the abnormal waiting time of molten steel in each furnace is controlled to be less than or equal to 5min, the total temperature drop in the process is controlled to be less than or equal to 70 ℃, and the stability of the superheat degree in the casting process is guaranteed.
4. The comprehensive control method for corner cracks of fine blanking steel slabs according to claim 1, characterized by comprising the following steps: in the second step, the range of the carbon content at the end point of the converter is controlled to be 0.06 +/-0.02%, and the range of the tapping temperature is controlled to be 1610 +/-5 ℃.
5. The oxygen content of the steel is reduced, and the deoxidation output generation is reduced.
6. The comprehensive control method for corner cracks of the fine blanking steel plate blank according to claim 1, characterized by comprising the following steps: and in the second step, aluminum, manganese and calcium are added during tapping, and desulfurized lime and ladle slag modifier are added in advance.
7. The comprehensive control method for corner cracks of fine blanking steel slabs according to claim 1, characterized by comprising the following steps: in the first, third and fourth steps, the molten steel sedation time between the RH station leaving and the continuous casting start is prolonged to 20min, the LF and RH weak stirring time is prolonged to 8min, and endogenetic inclusions are floated upwards.
8. The comprehensive control method for corner cracks of fine blanking steel slabs according to claim 1, characterized by comprising the following steps: in the fourth step, the calcium treatment comprises feeding pure calcium wires in a repeated pressing mode, and then carrying out soft stirring and soft blowing.
9. The comprehensive control method for corner cracks of the fine blanking steel plate blank according to claim 1, characterized by comprising the following steps: in the fifth step, the cooling water amount of one to three areas of the continuous casting secondary cooling area is increased, so that the surface temperature of the casting blank is ensured to avoid a brittle temperature range of 710-765 ℃ during bending operation.
10. The comprehensive control method for corner cracks of fine blanking steel slabs according to claim 1, characterized by comprising the following steps: and in the sixth step, the stopper rod, the water gap and the argon seal gas flow are reduced.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110545951.7A CN115369203B (en) | 2021-05-19 | 2021-05-19 | Comprehensive control method for corner cracks of fine-stamped steel slab |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110545951.7A CN115369203B (en) | 2021-05-19 | 2021-05-19 | Comprehensive control method for corner cracks of fine-stamped steel slab |
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